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	2022-12-14: How Can Matter Be BOTH Liquid AND Gas? 14:26: ... types; photonic matter; various spin-based states from ferromagnets to quantum spin liquids to time crystals; come to think of it, let’s not review all ... 15:11: ... I can go back to the 1920’s and debate interpretations of quantum mechanics with Einstein and Schrödinger!” – well, then you’d need to ... 16:53: Dark matter suffuses the near-vacuum of space, where we mostly just have the elementary quantum fields. 15:11: ... I can go back to the 1920’s and debate interpretations of quantum mechanics with Einstein and Schrödinger!” – well, then you’d need to learn ... 14:26: ... types; photonic matter; various spin-based states from ferromagnets to quantum spin liquids to time crystals; come to think of it, let’s not review all the ...
	2022-12-08: How Are Quasiparticles Different From Particles? 05:51: But remember we’re at the quantum scale here. 06:16: So now we have something like a particle - a quantum of vibrational energy moving around the lattice. 06:25: ... through solids via these vibrations - so this makes the phonon a quantum of a sound wave, similar to how a photon is a quantum of light - of an ... 07:07: As well as being a quantum of sound in solids, they are also the quantum of heat. 07:30: ... understanding of the behavior of both sound and heat in solids at the quantum scale And phonons are also really important for your computer, which, as ... 07:45: ... - and modeling this is needed for modeling the behavior of heat on the quantum ... 12:47: But this means they act like photons in that many Cooper pairs can occupy the same quantum state. 13:28: ... I had time for today - for example, quasiparticles appear in lattices of quantum spin, like are magnons - quanta of waves in that lattice, or skyrmions, ... 13:51: In superfluids we have rotons - a quantum of a vortex in the fluid. 14:20: After all, the elementary particles like electrons, photons, and quarks are just excitations in the elementary quantum fields. 05:51: But remember we’re at the quantum scale here. 07:30: ... understanding of the behavior of both sound and heat in solids at the quantum scale And phonons are also really important for your computer, which, as you ... 07:45: ... - and modeling this is needed for modeling the behavior of heat on the quantum scale. ... 13:28: ... I had time for today - for example, quasiparticles appear in lattices of quantum spin, like are magnons - quanta of waves in that lattice, or skyrmions, which ... 12:47: But this means they act like photons in that many Cooper pairs can occupy the same quantum state.
	2022-11-16: Are there Undiscovered Elements Beyond The Periodic Table? 09:23: The magic numbers are all even, and that’s because nucleons pair up according to their quantum spin, just like electrons in their shells.
	2022-11-09: What If Humanity Is Among The First Spacefaring Civilizations? 16:59: Today’s comment responses are for the episode on the 2022 Nobel prize, which went to three scientists for their work on quantum entanglement. 17:08: ... to wavefunction collapse when he said "spooky action at a distance" not quantum entanglement as is commonly ... 17:37: ... together with Boris Podolsky and Nathan Rosen and basically discovered quantum entanglement in an effort to disprove wavefunction collapse through a ... 18:28: It’s call transactional quantum mechanics. 18:50: ... description implied by this interpretation is equivalent to standard quantum field theory, with the time-reversed signals corresponding to negative ... 19:50: Radar they plan to dress as a Quantum Entangled Particle this Halloween and so doing causing lots of spooky action at a distance. 20:17: And then I figured it out - for my costume I entered a quantum superposition of both going and not-going to all of the parties. 19:50: Radar they plan to dress as a Quantum Entangled Particle this Halloween and so doing causing lots of spooky action at a distance. 16:59: Today’s comment responses are for the episode on the 2022 Nobel prize, which went to three scientists for their work on quantum entanglement. 17:08: ... to wavefunction collapse when he said "spooky action at a distance" not quantum entanglement as is commonly ... 17:37: ... together with Boris Podolsky and Nathan Rosen and basically discovered quantum entanglement in an effort to disprove wavefunction collapse through a reductio ad ... 18:50: ... description implied by this interpretation is equivalent to standard quantum field theory, with the time-reversed signals corresponding to negative ... 18:28: It’s call transactional quantum mechanics. 20:17: And then I figured it out - for my costume I entered a quantum superposition of both going and not-going to all of the parties.
	2022-10-26: Why Did Quantum Entanglement Win the Nobel Prize in Physics? 00:21: ... ingenious experiments that proved that the strangest prediction of  quantum mechanics is actually ... 00:34: ... the prediction that Einstein refused to accept - the idea that two quantum systems can be entangled - bound to each other such that they can ... 00:58: ... our understanding and practical application of the phenomenon of quantum ... 01:11: ... course, we’ve talked about quantum entanglement once or twice in the past, but today I want to tell ... 01:58: Now imagine these are quantum balls  with entangled “quantum” colors. 02:03: ... to quantum mechanics, we not only  don’t know which is which until the box is ... 02:36: ... “quantum balls” could be any particle from subatomic to molecular scale, and ... 03:01: Well, because quantum mechanics  in it's standard form says so. 03:07: Quantum systems are described by a mathematical object called the wavefunction, which evolves according to the Schrodinger equation. 03:28: For our quantum balls to know their own color the whole time, there would need to be extra information not contained in their wavefunction. 03:36: ... are a few different interpretations of quantum mechanics that allow this hidden information, and they’re collectively ... 03:46: ... insisted that the wavefunction was the complete  description of a quantum ... 04:03: Quantum mechanics was just too successful, and Neils Bohr was aggressive in pushing his Copenhagen interpretation. 06:12: Apparently Feynman thought it was pointless because standard quantum mechanics was clearly correct. 06:42: ... possible electron transitions was between two states that had zero quantum spin, and which also resulted in  the creation of two ... 06:51: Spin is the quantum version of angular momentum. 07:09: ... quantum mechanics says that those polarizations are undefined until ... 07:33: ... was convincingly violated in their experiments, which means quantum mechanics was working exactly as expected, implying no hidden ... 07:56: ... result of a quantum measurement depends on how you make the measurement - in the case ... 08:35: ... direction the whole time and sort of conspire to look like standard quantum mechanics, even if they had real hidden ... 10:35: There are two ways that the Bell inequalities could be violated without quantum entanglement being as spooky as Einstein feared. 12:37: ... and Aspect's work was all about testing the fundamentals of quantum mechanics - about getting closer to what its weirdness  is really ... 12:50: They, and others like them, advanced our ability to create and manipulate entangled quantum states. And Zeilinger put these to good use. 12:57: He may be the most famous for  demonstrating quantum teleportation. 13:02: This is a phenomenon in which a quantum state is transferred between two particles via an interrmediate particle that’s entangled with them both. 13:13: ... teleportation and the corresponding ability to move around quantum information is critical for quantum ... 13:21: ... of advances in manipulating entanglement, and has applied these to quantum cryptography and to  the development of quantum ... 13:38: Einstein because, one way or another,  the quantum world is indeed quite spooky. 13:43: ... Feynman was right in thinking that Clauser would never disprove standard quantum mechanics - but he was wrong in thinking  that Clauser shouldn’t ... 14:06: ... this case, our better understanding of quantum entanglement has brought us very close to the age of quantum ... 19:16: ... in general a lot of problematic features appear in quantum field theory that have to be removed by hand - for example, ... 02:36: ... “quantum balls” could be any particle from subatomic to molecular scale, and the ... 03:28: For our quantum balls to know their own color the whole time, there would need to be extra information not contained in their wavefunction. 01:58: Now imagine these are quantum balls  with entangled “quantum” colors. 13:13: ... ability to move around quantum information is critical for quantum computers. ... 13:21: ... applied these to quantum cryptography and to  the development of quantum computers. ... 14:06: ... of quantum entanglement has brought us very close to the age of quantum computing  and quantum ... 13:21: ... of advances in manipulating entanglement, and has applied these to quantum cryptography and to  the development of quantum ... 14:06: ... has brought us very close to the age of quantum computing  and quantum cryptography. ... 00:58: ... our understanding and practical application of the phenomenon of quantum entanglement. ... 10:35: There are two ways that the Bell inequalities could be violated without quantum entanglement being as spooky as Einstein feared. 14:06: ... this case, our better understanding of quantum entanglement has brought us very close to the age of quantum computing  and ... 01:11: ... course, we’ve talked about quantum entanglement once or twice in the past, but today I want to tell you all about the series ... 19:16: ... in general a lot of problematic features appear in quantum field theory that have to be removed by hand - for example, various  ... 13:13: ... teleportation and the corresponding ability to move around quantum information is critical for quantum ... 07:56: ... result of a quantum measurement depends on how you make the measurement - in the case of this ... 00:21: ... ingenious experiments that proved that the strangest prediction of  quantum mechanics is actually ... 02:03: ... to quantum mechanics, we not only  don’t know which is which until the box is open, but ... 03:36: ... are a few different interpretations of quantum mechanics that allow this hidden information, and they’re collectively known as ... 04:03: Quantum mechanics was just too successful, and Neils Bohr was aggressive in pushing his Copenhagen interpretation. 06:12: Apparently Feynman thought it was pointless because standard quantum mechanics was clearly correct. 07:09: ... quantum mechanics says that those polarizations are undefined until measurement, when ... 07:33: ... was convincingly violated in their experiments, which means quantum mechanics was working exactly as expected, implying no hidden ... 08:35: ... direction the whole time and sort of conspire to look like standard quantum mechanics, even if they had real hidden ... 12:37: ... and Aspect's work was all about testing the fundamentals of quantum mechanics - about getting closer to what its weirdness  is really telling us ... 13:43: ... Feynman was right in thinking that Clauser would never disprove standard quantum mechanics - but he was wrong in thinking  that Clauser shouldn’t ... 12:37: ... and Aspect's work was all about testing the fundamentals of quantum mechanics - about getting closer to what its weirdness  is really telling us ... 13:43: ... Feynman was right in thinking that Clauser would never disprove standard quantum mechanics - but he was wrong in thinking  that Clauser shouldn’t ... 03:01: Well, because quantum mechanics  in it's standard form says so. 02:36: ... and the entangled property could be spin,  momentum, or any other quantum property. ... 06:42: ... possible electron transitions was between two states that had zero quantum spin, and which also resulted in  the creation of two ... 13:02: This is a phenomenon in which a quantum state is transferred between two particles via an interrmediate particle that’s entangled with them both. 12:50: They, and others like them, advanced our ability to create and manipulate entangled quantum states. And Zeilinger put these to good use. 00:34: ... the prediction that Einstein refused to accept - the idea that two quantum systems can be entangled - bound to each other such that they can influence ... 03:07: Quantum systems are described by a mathematical object called the wavefunction, which evolves according to the Schrodinger equation. 12:57: He may be the most famous for  demonstrating quantum teleportation. 06:51: Spin is the quantum version of angular momentum.
	2022-10-19: The Equation That Explains (Nearly) Everything! 01:33: ... example, if we insist that the phase of the quantum wavefunction is fundamentally unmeasurable, then we need to add a term ... 03:24: ... the path traveled by a ball through the air or the probability that two quantum particles will ... 03:36: ... distance an object or system travels through the space of all possible quantum states. For classical physics it simplifies to just Kinetic Energy minus ... 06:36: ... are actually shorthand for the separate interaction of each of the three quantum ... 03:24: ... the path traveled by a ball through the air or the probability that two quantum particles will ... 03:36: ... distance an object or system travels through the space of all possible quantum states. For classical physics it simplifies to just Kinetic Energy minus ... 01:33: ... example, if we insist that the phase of the quantum wavefunction is fundamentally unmeasurable, then we need to add a term to the ...
	2022-10-12: The REAL Possibility of Mapping Alien Planets! 15:45: ... Bang. First let me say that in the extremely early,   the 3 quantum forces were coupled with a high joint interaction ... 18:29: ... of that tiny patch of space, and   that can change the way the quantum fields behave - including raising the fine structure ... 15:45: ... Bang. First let me say that in the extremely early,   the 3 quantum forces were coupled with a high joint interaction strength.   ...
	2022-09-28: Why Is 1/137 One of the Greatest Unsolved Problems In Physics? 00:19: This is the fine structure constant, and it appears everywhere in our equations of quantum physics, and we’re still trying to figure out why. 00:48: But there’s something so weird and so compelling  about this number that many of the founders of quantum mechanics obsessed over it. 01:34: As with much of quantum mechanics, it started  with us watching the light produced as electrons flicked between energy levels in atoms. 02:04: ... spectral lines was a major driver  of the development of quantum mechanics, and one of its first great successes, first with  the ... 00:48: But there’s something so weird and so compelling  about this number that many of the founders of quantum mechanics obsessed over it. 01:34: As with much of quantum mechanics, it started  with us watching the light produced as electrons flicked between energy levels in atoms. 02:04: ... spectral lines was a major driver  of the development of quantum mechanics, and one of its first great successes, first with  the Bohr model ... 00:48: But there’s something so weird and so compelling  about this number that many of the founders of quantum mechanics obsessed over it. 00:19: This is the fine structure constant, and it appears everywhere in our equations of quantum physics, and we’re still trying to figure out why.
	2022-09-21: Science of the James Webb Telescope Explained! 12:19: ... for the two recent episodes - the one about the strong force and quantum chromodynamics, and then the one about how the Higgs boson could tell us ... 14:20: Quantum chromodynamics actually started to explain was going on, so it suplanted hadronic string theory. 14:28: ... in size by about 20 orders of magnitude and developed into a theory of quantum ... 17:09: ... quantum theorists of various colours can tell themselves that they’re hunting ... 12:19: ... for the two recent episodes - the one about the strong force and quantum chromodynamics, and then the one about how the Higgs boson could tell us what dark ... 14:20: Quantum chromodynamics actually started to explain was going on, so it suplanted hadronic string theory. 14:28: ... in size by about 20 orders of magnitude and developed into a theory of quantum gravity. ... 17:09: ... quantum theorists of various colours can tell themselves that they’re hunting for the ...
	2022-08-24: What Makes The Strong Force Strong? 00:00: Quantum mechanics gets weirder as you go to smaller sizes and higher energies. 00:10: And today we’re going nuclear, as we dive into the weird world of quantum chromodynamics. 01:20: The answers to these questions lie in the complex behavior of quarks and gluons via the rules of quantum chromodynamics. 03:15: For the class of particles called fermions, no more than one particle can wear the same dress or occupy the same quantum state. 04:52: And this colourful convention led to the naming of our science of strong force interactions: quantum chromodynamics. 17:53: ... exist, but instead are a calculation tool to describe fluctuation quantum fields, what does that mean for Hawking ... 18:28: Hawking’s original derived his radiation by calculating the disturbances on the quantum fields due to the appearance of an event horizon. 21:07: ... don't get caught in the same trap as the proponents of theories of quantum consciousness, or that aliens built the pyramids, or that Elvis shot ... 00:10: And today we’re going nuclear, as we dive into the weird world of quantum chromodynamics. 01:20: The answers to these questions lie in the complex behavior of quarks and gluons via the rules of quantum chromodynamics. 04:52: And this colourful convention led to the naming of our science of strong force interactions: quantum chromodynamics. 21:07: ... don't get caught in the same trap as the proponents of theories of quantum consciousness, or that aliens built the pyramids, or that Elvis shot ... 17:53: ... exist, but instead are a calculation tool to describe fluctuation quantum fields, what does that mean for Hawking ... 18:28: Hawking’s original derived his radiation by calculating the disturbances on the quantum fields due to the appearance of an event horizon. 00:00: Quantum mechanics gets weirder as you go to smaller sizes and higher energies. 03:15: For the class of particles called fermions, no more than one particle can wear the same dress or occupy the same quantum state.
	2022-08-17: What If Dark Energy is a New Quantum Field? 05:18: ... that there are problems with the explanation where dark energy is due to quantum fluctuations. For example, it’s actually very difficult to get the ... 05:50: ... energy density of dark energy. You can reduce that number if the quantum fields sort of cancel each other out. A perfectly symmetric canceling ... 07:31: ... for a mechanism for accelerating expansion due being some other than quantum fluctuations. It’s because we know there must be one to explain cosmic ... 10:55: ... us another explanation. The quintessence field could be coupled to the quantum fields responsible for radiation and matter, and its behavior could be ... 11:51: ... a little bit ambiguous, and all of these could result from a new scalar quantum ... 14:41: ... coincidental with a quintessentially consistent dark energy, or scalar quantum fields shift in a quintessence-saturated space ... 07:31: ... energy could be solved. There are a few options for dark energy as a new quantum field. Perhaps the most prominent is quintessence, proposed by Robert Caldwell, ... 11:51: ... a little bit ambiguous, and all of these could result from a new scalar quantum field. ... 05:50: ... energy density of dark energy. You can reduce that number if the quantum fields sort of cancel each other out. A perfectly symmetric canceling could get ... 07:31: ... during the big bang. That expansion must have been due to one or more quantum fields being in a highly energetic state, rather than all quantum fields ... 10:55: ... us another explanation. The quintessence field could be coupled to the quantum fields responsible for radiation and matter, and its behavior could be ... 14:41: ... coincidental with a quintessentially consistent dark energy, or scalar quantum fields shift in a quintessence-saturated space ... 07:31: ... more quantum fields being in a highly energetic state, rather than all quantum fields fluctuating a teensy bit above their energy minima. So if a specific field was ... 10:55: ... us another explanation. The quintessence field could be coupled to the quantum fields responsible for radiation and matter, and its behavior could be connected to the ... 14:41: ... coincidental with a quintessentially consistent dark energy, or scalar quantum fields shift in a quintessence-saturated space ... 05:50: ... energy density of dark energy. You can reduce that number if the quantum fields sort of cancel each other out. A perfectly symmetric canceling could get you ... 05:18: ... that there are problems with the explanation where dark energy is due to quantum fluctuations. For example, it’s actually very difficult to get the vacuum energy to be ... 07:31: ... for a mechanism for accelerating expansion due being some other than quantum fluctuations. It’s because we know there must be one to explain cosmic inflation. This ...
	2022-08-03: What Happens Inside a Proton? 00:45: ... systems.   That’s especially true when we study the  quantum world, where the information density is   obscenely high. As ... 01:31: ... The messy interactions of quarks via gluons   is described by quantum chromodynamics,  or QCD, in the same way that quantum   ... 03:12: ... before we do the hard stuff, let’s review the comparatively “easy” quantum electrodynamics.   Say we want to predict what happens ... 07:07: ... fact previously. Real particles  are sustained oscillations in a quantum field   that have real energy and consistent ... 07:53: ... that’s where lattice QCD comes in. It’s an effort to model how the quantum fields themselves evolve   over the course of a strong force ... 08:58: ... to do here. We want the probability for   some wiggly quantum field wiggles between two states. Let’s go back to electromagnetism ... 11:28: ... quantum field is a 3-D pixelated lattice that evolves through time. As with ... 12:15: ... the connections are the gluon field.   Getting rid of the quantum probabilities means this isn’t really even a quantum problem any ... 14:08: ... QCD even works gives us deep insights into the nature of the quantum fields.   For one thing, because it doesn’t use ... 01:31: ... The messy interactions of quarks via gluons   is described by quantum chromodynamics,  or QCD, in the same way that quantum   electrodynamics ... 03:12: ... before we do the hard stuff, let’s review the comparatively “easy” quantum electrodynamics.   Say we want to predict what happens when two electrons are shot ... 08:58: ... to do here. We want the probability for   some wiggly quantum field wiggles between two states. Let’s go back to electromagnetism just ... 11:28: ... quantum field is a 3-D pixelated lattice that evolves through time. As with the ... 14:08: ... use virtual particles at all, but rather simulates the   quantum field more directly. That helps us put to bed the idea that virtual ... 08:58: ... to do here. We want the probability for   some wiggly quantum field wiggles between two states. Let’s go back to electromagnetism just ... 07:07: ... fact previously. Real particles  are sustained oscillations in a quantum field   that have real energy and consistent properties. Virtual particles ... 07:53: ... that’s where lattice QCD comes in. It’s an effort to model how the quantum fields themselves evolve   over the course of a strong force ... 14:08: ... QCD even works gives us deep insights into the nature of the quantum fields.   For one thing, because it doesn’t use virtual particles at all, but ... 12:15: ... the connections are the gluon field.   Getting rid of the quantum probabilities means this isn’t really even a quantum problem any ... 08:58: ... came up with his famous diagrams, he devised a way to calculate quantum probabilities   called the Feynman path integral. It calculates the probability ... 12:15: ... rid of the quantum probabilities means this isn’t really even a quantum problem any more.   The structure looks like a crystal - ... 13:36: ... trick of transforming quantum  fields into a lattice was first   discovered by Ken Wilson all ... 07:07: ... general, if we can’t calculate what quantum chromodynamics predicts for the behavior of   quarks, how can we even test ... 01:31: ... described by quantum chromodynamics,  or QCD, in the same way that quantum   electrodynamics describes the interactions of electrons and any ...
	2022-07-27: How Many States Of Matter Are There? 07:00: The stuff of quarks is generically called quark matter or QCD matter - for quantum chromodynamics - the physics of quark and gluon interactions. 08:00: But once you bring quantum mechanics into the picture, many strange states of matter become possible. 08:07: ... in degenerate matter like neutronium or Bose-Einstein condensates, all quantum states are occupied, leading to some surprising and useful emergent ... 08:21: Time crystals are the latest and perhaps weirdest quantum state of matter. 12:09: ... matter allows us to use the tools of our material sciences - for example quantum mechanics and condensed matter physics - to help us understand why we ... 07:00: The stuff of quarks is generically called quark matter or QCD matter - for quantum chromodynamics - the physics of quark and gluon interactions. 08:00: But once you bring quantum mechanics into the picture, many strange states of matter become possible. 12:09: ... matter allows us to use the tools of our material sciences - for example quantum mechanics and condensed matter physics - to help us understand why we see the ... 08:21: Time crystals are the latest and perhaps weirdest quantum state of matter. 08:07: ... in degenerate matter like neutronium or Bose-Einstein condensates, all quantum states are occupied, leading to some surprising and useful emergent properties, ...
	2022-07-20: What If We Live in a Superdeterministic Universe? 00:33: These quantum superpositions only collapse into single states when we try to measure them. 01:06: There have been many efforts to find a realist interpretation of quantum mechanics. 01:34: Erwin Schrodinger, co-inventer of quantum mechanics with Werner Heisenberg, was a big proponent of realism. 01:55: Albert Einstein also came up with a scenario in which he tried to refute the non-realist implications of pure quantum mechanics. 02:20: ... “standard” quantum mechanics, the fundamental building block of reality is the ... 02:55: This is quantum superposition. 03:04: This is quantum entanglement. 03:36: Standard quantum mechanics says that this is possible, but it leads to the seemingly absurd result of the EPR paradox. 04:02: According to standard quantum mechanics, that spin is undefined until measurement. 05:34: ... in a way that was somehow hidden from the wavefunction of standard quantum ... 06:36: ... the beginning and contained within the electron - but false if standard quantum mechanics is right and spin is undefined until ... 06:59: That test thoroughly supported standard quantum mechanics. 07:52: There are ways to save realism in quantum mechanics by crossing Einstein and abandoning locality. 08:04: On the other hand, Many Worlds interpretation of quantum mechanics saves local realism at the cost of requiring multiple realities. 08:47: But quantum mechanics says that when Alice measures her electron, Bob’s electron is instantly affected. 14:09: Quantum mechanics has been telling us that we are not that for 100 years. 03:04: This is quantum entanglement. 01:06: There have been many efforts to find a realist interpretation of quantum mechanics. 01:34: Erwin Schrodinger, co-inventer of quantum mechanics with Werner Heisenberg, was a big proponent of realism. 01:55: Albert Einstein also came up with a scenario in which he tried to refute the non-realist implications of pure quantum mechanics. 02:20: ... “standard” quantum mechanics, the fundamental building block of reality is the wavefunction, which ... 03:36: Standard quantum mechanics says that this is possible, but it leads to the seemingly absurd result of the EPR paradox. 04:02: According to standard quantum mechanics, that spin is undefined until measurement. 05:34: ... in a way that was somehow hidden from the wavefunction of standard quantum mechanics. ... 06:36: ... the beginning and contained within the electron - but false if standard quantum mechanics is right and spin is undefined until ... 06:59: That test thoroughly supported standard quantum mechanics. 07:52: There are ways to save realism in quantum mechanics by crossing Einstein and abandoning locality. 08:04: On the other hand, Many Worlds interpretation of quantum mechanics saves local realism at the cost of requiring multiple realities. 08:47: But quantum mechanics says that when Alice measures her electron, Bob’s electron is instantly affected. 14:09: Quantum mechanics has been telling us that we are not that for 100 years. 08:04: On the other hand, Many Worlds interpretation of quantum mechanics saves local realism at the cost of requiring multiple realities. 02:55: This is quantum superposition. 00:33: These quantum superpositions only collapse into single states when we try to measure them.
	2022-06-30: Could We Decode Alien Physics? 06:55: ... right-handed and left-handed   versions of all particles with quantum spin.  If we build the device with positions that   are ... 07:38: ... put aside quantum spin for a minute to  define this rule. Say you have an electron ... 10:41: ... symmetry between left and right handed chirality for particles with quantum spin,   and in our universe P-symmetry is broken in  much ... 07:38: ... put aside quantum spin for a minute to  define this rule. Say you have an electron ... 06:55: ... right-handed and left-handed   versions of all particles with quantum spin.  If we build the device with positions that   are spinning the ... 10:41: ... symmetry between left and right handed chirality for particles with quantum spin,   and in our universe P-symmetry is broken in  much more obvious ways ...
	2022-06-22: Is Interstellar Travel Impossible? 15:08: We talked about how quantum mechanics can be derived as a model of our information about the world, rather than the world itself. 15:31: Clay Farris Naff asks whether Zeilinger description of informational quantum mechanics is consistent with Hawking's late-in-life anti-realist stance? 16:09: But this is the philosophy behind Zeilinger’s interpretation of quantum mechanics. 16:24: ... the wave-particle duality was explained in the context of informational quantum mechanics in that you couldn’t simultaneously extract answers to both ... 16:41: ... know what questions are the most elementary, and so we don’t know if a quantum system’s wave-particle nature has a binary ... 17:58: We have robust theories for the unification of the three quantum forces. 18:03: And we even have ideas for black holes in theories of quantum gravity - for example, the fuzzball of string theory, which we did an episode on. 19:30: Hawking’s original argument talked about perturbing the positive and negative frequency modes of the quantum vacuum. 17:58: We have robust theories for the unification of the three quantum forces. 18:03: And we even have ideas for black holes in theories of quantum gravity - for example, the fuzzball of string theory, which we did an episode on. 15:08: We talked about how quantum mechanics can be derived as a model of our information about the world, rather than the world itself. 15:31: Clay Farris Naff asks whether Zeilinger description of informational quantum mechanics is consistent with Hawking's late-in-life anti-realist stance? 16:09: But this is the philosophy behind Zeilinger’s interpretation of quantum mechanics. 16:24: ... the wave-particle duality was explained in the context of informational quantum mechanics in that you couldn’t simultaneously extract answers to both ... 16:41: ... know what questions are the most elementary, and so we don’t know if a quantum system’s wave-particle nature has a binary ... 19:30: Hawking’s original argument talked about perturbing the positive and negative frequency modes of the quantum vacuum.
	2022-06-15: Can Wormholes Solve The Black Hole Information Paradox? 00:26: ... But there is another less well known  glitch between GR and quantum theory   that might provide a way forward. I’m ... 01:40: ... This conflicts with the law of   conservation of quantum information, which is a non-negotiable constraint of quantum ... 02:43: ... quantum version of entropy is called  von Neumann entropy. This is the ... 03:20: ... of the black hole are entangled. The  black hole interior contains quantum information   about the radiation. But when the black ... 04:44: ... have largely focused on ways to encode Hawking radiation with that quantum information,   so that each new particle is entangled  ... 06:54: ... the Page curve using only general relativity  and accepted quantum mechanics - no string   theories attached. To be fair, these ... 07:24: ... papers  pulls ideas from string theory, holography,   quantum field theory, and  quantum computing to name a few ... 02:43: ... entangled particle or system of particles is a measure of how much quantum information   is not stored locally in the system itself,  but rather in whatever ... 03:20: ... of the black hole are entangled. The  black hole interior contains quantum information   about the radiation. But when the black hole  eventually ... 04:44: ... have largely focused on ways to encode Hawking radiation with that quantum information,   so that each new particle is entangled  with all previously emitted ... 02:43: ... by measuring its entangled partner. Some   of the quantum inimformation of each of the pair is stored in its partner. The von Neumann ... 01:40: ... of quantum information, which is a non-negotiable constraint of quantum mechanics. ... 06:54: ... the Page curve using only general relativity  and accepted quantum mechanics - no string   theories attached. To be fair, these US ... 00:26: ... But there is another less well known  glitch between GR and quantum theory   that might provide a way forward. I’m talking about the black hole ... 02:43: ... quantum version of entropy is called  von Neumann entropy. This is the entropy ... 12:09: ... transitional geometries   allow the radiation to leak quantum  information from the black hole ... 00:26: ... there’s an uncomfortable conflict between general relativity and quantum   mechanics when we try to describe the tiniest scales and the ... 03:20: ... But when the black hole  eventually evaporates, its internal quantum   information seems like it should disappear, violating the law of ... 07:24: ... Richard Feynman’s path integral  calculates the probability of some quantum   particle traveling between two points by adding up all ways the ... 00:26: ... there’s an uncomfortable conflict between general relativity and quantum   mechanics when we try to describe the tiniest scales and the highest ... 07:24: ... Richard Feynman’s path integral  calculates the probability of some quantum   particle traveling between two points by adding up all ways the particle ...
	2022-06-01: What If Physics IS NOT Describing Reality? 00:25: ... which laws work best. But actually, some of the   founders of quantum theory were convinced that  the role of physics was one step ... 01:41: ... started talking  about informational interpretations   of quantum mechanics. Then we discussed  one of the more radical ... 02:20: ... right, but we  can explore the power of informational   quantum mechanics without committing  to quite such a radical ... 02:44: ... see  if we can rebuild the world from those parts.   In quantum mechanics, we have things like  particles and fields which can only ... 03:22: ... Anton Zeilinger has proposed an  informational approach to quantum mechanics   in which the world is broken up not into  ... 04:05: ... of well-chosen yes-no questions. So Zeilinger  says that any quantum system can be broken   into the results of binary questions. ... 04:56: ... simplest way to start is to look at a  quantum system where the answer to a single   binary question seems to ... 05:53: ... The up-down alignment becomes undefined. So   by thinking of quantum systems as being made  of these elementary “quanta of ... 07:23: ... Quantum entanglement also fits this picture.  When we prepared our ... 08:49: ... we’ve seen how an elementary quantum system’s  information content has to exist with respect to ... 09:26: ... one of the   original and most mysterious features of  quantum mechanics - wave-particle ... 10:33: ... both questions. So, they found that the  wave-particle duality of quantum mechanics   arises from the limited information, the  ... 11:24: ... one thing to use quantum information theory  as a mathematical tool, but quite another to ... 12:09: ... And it turns out that   a lot of the weirdness we see in the quantum world  make more sense if we pay attention to the fact   ... 07:23: ... Quantum entanglement also fits this picture.  When we prepared our electrons to be ... 02:44: ... components   that we call entanglement. But as weird  as quantum fields and particles are,   this still feels like a very physical ... 04:05: ... of   quantum mechanics suddenly make sense. Things  like quantum indeterminacy, entanglement, and the   uncertainty principle turn out to be ... 01:41: ... started talking  about informational interpretations   of quantum mechanics. Then we discussed  one of the more radical ... 02:20: ... right, but we  can explore the power of informational   quantum mechanics without committing  to quite such a radical ... 02:44: ... see  if we can rebuild the world from those parts.   In quantum mechanics, we have things like  particles and fields which can only take ... 04:05: ... answer  - a surprising number of the weird results of   quantum mechanics suddenly make sense. Things  like quantum indeterminacy, ... 09:26: ... one of the   original and most mysterious features of  quantum mechanics - wave-particle ... 11:24: ... believe to be the building blocks of reality. In  quantum mechanics, we tend to think of the quantum   wavefunction as pretty ... 09:26: ... one of the   original and most mysterious features of  quantum mechanics - wave-particle ... 04:05: ... answer  - a surprising number of the weird results of   quantum mechanics suddenly make sense. Things  like quantum indeterminacy, entanglement, and ... 01:41: ... pithily  summarized with the expression “it from bit”.   Quantum mechanics tells us that asking questions  of the universe radically changes how it ... 02:20: ... Today we’re going to see how a lot  of the weirdness of quantum mechanics   can make sense if we think about it as a  model of our information ... 03:22: ... Anton Zeilinger has proposed an  informational approach to quantum mechanics   in which the world is broken up not into  physical parts, but into ... 10:33: ... both questions. So, they found that the  wave-particle duality of quantum mechanics   arises from the limited information, the  inability to answer two ... 04:56: ... question seems to give a meaningful  “physical” answer. Consider quantum spin.   From a physical point of view, think of it as  a particle’s ... 11:24: ... results you might get if you tried to  measure the properties of a quantum system.   Zeilinger and supporters would say that the wavefunction does not ... 05:53: ... The up-down alignment becomes undefined. So   by thinking of quantum systems as being made  of these elementary “quanta of ... 08:49: ... we’ve seen how an elementary quantum system’s  information content has to exist with respect to a   certain ... 00:25: ... which laws work best. But actually, some of the   founders of quantum theory were convinced that  the role of physics was one step further ... 05:53: ... “quanta of information”,   we see the indeterminacy of quantum theory arises  naturally. Zeilinger even managed to derive the   ... 00:25: ... “The laws of nature which   we formulate mathematically in quantum theory deal  no longer with the particles themselves but with   our ... 08:49: ... This idea leads us   naturally to some other staples of quantum theory  - like the Heisenberg uncertainty principle.   In a previous ... 12:09: ... And it turns out that   a lot of the weirdness we see in the quantum world  make more sense if we pay attention to the fact   that our ... 02:44: ... which can only take on   discrete or quantized values. These quantum  components also have weird properties like   fundamental ... 03:22: ... to a question we could ask   about the world. He says that a quantum  system is a collection of propositions.   A quantum system ... 02:44: ... which can only take on   discrete or quantized values. These quantum  components also have weird properties like   fundamental uncertainty in ... 05:53: ... by definition, that’s  all the information that the elementary quantum   system of spin can contain. That means the  left-right orientation ... 11:24: ... blocks of reality. In  quantum mechanics, we tend to think of the quantum   wavefunction as pretty fundamental. It describes  the evolving ...
	2022-05-04: Space DOES NOT Expand Everywhere 08:51: ... made out of, if anything. That’s the province of a long-sought theory of quantum ... 10:33: ... that at the smallest scales, general relativity comes into conflict with quantum mechanics. There is a smallest measurable length called the Planck ... 14:34: ... of phrasing has led to all  sorts of misunderstanding  and quantum charlatanry. But I think the reason people like Wheeler and Bohr used ... 15:31: ... electron thing from his advisor, and using it to help develop quantum electrodynamics. So what can we build using ideas from the participatory ... 14:34: ... of phrasing has led to all  sorts of misunderstanding  and quantum charlatanry. But I think the reason people like Wheeler and Bohr used these terms is ... 15:31: ... electron thing from his advisor, and using it to help develop quantum electrodynamics. So what can we build using ideas from the participatory ... 08:51: ... made out of, if anything. That’s the province of a long-sought theory of quantum gravity. ... 10:33: ... that at the smallest scales, general relativity comes into conflict with quantum mechanics. There is a smallest measurable length called the Planck length. When ... 14:34: ... that they couldn’t directly observe. Unfortunately, practitioners of quantum woo are not so careful and definitely not so ...
	2022-04-27: How the Higgs Mechanism Give Things Mass 01:48: ... can wiggle,  twist, oscillate in different ways.   A quantum field just represents one of these  modes. And these wiggles are ... 02:31: ... quantum mechanics, such a “redundant degree  of freedom” leads to a gauge ... 02:50: ... we enforce this requirement, we find  that we have to add a new quantum field to   the Schrodinger equation that lets the  ... 07:01: ... in a similar way. The equivalent of the  simple valley exists. A quantum field   can oscillate around some “zero-point” value  ... 08:09: ... particular Lagrangian describes a simple  quantum field made of massive particles which   interact with each ... 01:48: ... can wiggle,  twist, oscillate in different ways.   A quantum field just represents one of these  modes. And these wiggles are ... 02:50: ... we enforce this requirement, we find  that we have to add a new quantum field to   the Schrodinger equation that lets the  universe ... 08:09: ... particular Lagrangian describes a simple  quantum field made of massive particles which   interact with each other. ... 02:50: ... we enforce this requirement, we find  that we have to add a new quantum field to   the Schrodinger equation that lets the  universe counteract these ... 07:01: ... in a similar way. The equivalent of the  simple valley exists. A quantum field   can oscillate around some “zero-point” value  like a ball rolling ... 02:31: ... quantum mechanics, such a “redundant degree  of freedom” leads to a gauge field. We’ve ... 08:09: ... Let me talk you through  the hieroglyphics. Firstly, phi is the quantum   field itself - it just means there’s a numerical  strength of the ...
	2022-04-20: Does the Universe Create Itself? 00:59: ... then came the 20th century, and quantum mechanics. In quantum mechanics, not only does the act of measurement ... 01:59: ... to go to these crazy lengths to explain the universe, let’s review some quantum weirdness. We’ll start with the good ol’ Schrodinger’s cat thought ... 04:03: ... put the whole mess behind them and get on with the job of actually using quantum mechanics to invent the modern ... 04:14: ... others. Wheeler was never completely satisfied with any of the proposed quantum interpretations. Although he started out as a pure realist, he came to ... 05:56: ... or reflected by the beamsplitter. But remember I said that the quantum world appears to live in a state of uncertainty until it’s ... 06:13: ... this case, quantum mechanics states that the photon is in a state of having been both ... 11:11: ... power over reality, as claimed by some of the worst practitioners of quantum woo. But the role of consciousness was something Wheeler really ... 12:27: ... In the broad category of “participatory realism” we have things like quantum bayesianism and relational quantum mechanics, in which the universe ... 16:10: ... horizons will lead to a disconnection in the vibrational modes of the quantum fields in a way that looks like thermal radiation. That radiation has a ... 12:27: ... In the broad category of “participatory realism” we have things like quantum bayesianism and relational quantum mechanics, in which the universe emerges from the ... 01:59: ... for example, Hugh Everett’s many worlds interpretation and the ideas of quantum decoherence. And then we have Richard Feynmann’s “no interpretation” interpretation ... 00:59: ... which say that the universe exists not so much in physical particles and quantum fields, nor solely in the mind of the observer, but rather in the interaction of ... 16:10: ... horizons will lead to a disconnection in the vibrational modes of the quantum fields in a way that looks like thermal radiation. That radiation has a ... 00:59: ... I’ll come back to. Today I want to begin a discussion of a family of quantum interpretations which say that the universe exists not so much in physical particles and ... 04:14: ... others. Wheeler was never completely satisfied with any of the proposed quantum interpretations. Although he started out as a pure realist, he came to believe that the ... 00:59: ... then came the 20th century, and quantum mechanics. In quantum mechanics, not only does the act of measurement profoundly ... 01:59: ... alive and dead until the box is open - a superposition of states. Or so quantum mechanics seems to suggest. This seems even more absurd when you add the so-called ... 04:03: ... put the whole mess behind them and get on with the job of actually using quantum mechanics to invent the modern ... 06:13: ... this case, quantum mechanics states that the photon is in a state of having been both transmitted and ... 12:27: ... realism” we have things like quantum bayesianism and relational quantum mechanics, in which the universe emerges from the information that some set of real ... 06:13: ... this case, quantum mechanics states that the photon is in a state of having been both transmitted and ... 01:59: ... cat in a closed box that is either killed or not killed by a random quantum process. For a scientist running the experiment, the cat is in a twin state of ... 00:59: ... Einstein himself. We’ve talked about this debate between the founders of quantum theory before, and of some of the supposed resolutions, which I’ll come back ... 01:59: ... to go to these crazy lengths to explain the universe, let’s review some quantum weirdness. We’ll start with the good ol’ Schrodinger’s cat thought experiment, ... 11:11: ... power over reality, as claimed by some of the worst practitioners of quantum woo. But the role of consciousness was something Wheeler really struggled ...
	2022-03-23: Where Is The Center of The Universe? 10:45: Stand by for our theory of quantum gravity to resolve that one.
	2022-03-16: What If Charge is NOT Fundamental? 00:37: The math that describes it - Maxwell's equations  or quantum electrodynamics - seem to wrap it up nicely. 01:39: As with much of modern physics, this story begins with Werner Heisenberg, whose epiphanies birthed quantum mechanics. 02:23: For example electrons have this thing called spin - a quantum analogy to angular momentum. 05:13: ... the same way that isospin followed the same mathematics as regular quantum spin, this new property seemed to obey the math for our old friend ... 08:32: The quark model for nucleons led to a description  of the strong nuclear force via this SU(3) stuff to give us quantum chromodynamics. 09:07: The secrets of electric charge are actually hiding in the last, most obscure of the quantum forces - the weak force. 09:32: ... it is - but it's the thing that's going to connect all of this back to quantum spin, which is sort of where we ... 09:41: One consequence of quantum spin is this thing called chirality, which is sort of the projection of spin in the direction that a particle is moving. 10:39: Only left-handed particles have it, and so it has an intimate connection to the quantum spin. 02:23: For example electrons have this thing called spin - a quantum analogy to angular momentum. 08:32: The quark model for nucleons led to a description  of the strong nuclear force via this SU(3) stuff to give us quantum chromodynamics. 00:37: The math that describes it - Maxwell's equations  or quantum electrodynamics - seem to wrap it up nicely. 09:07: The secrets of electric charge are actually hiding in the last, most obscure of the quantum forces - the weak force. 01:39: As with much of modern physics, this story begins with Werner Heisenberg, whose epiphanies birthed quantum mechanics. 05:13: ... the same way that isospin followed the same mathematics as regular quantum spin, this new property seemed to obey the math for our old friend electric ... 09:32: ... it is - but it's the thing that's going to connect all of this back to quantum spin, which is sort of where we ... 09:41: One consequence of quantum spin is this thing called chirality, which is sort of the projection of spin in the direction that a particle is moving. 10:39: Only left-handed particles have it, and so it has an intimate connection to the quantum spin.
	2022-03-08: Is the Proxima System Our Best Hope For Another Earth? 17:13: But in general it means different branches of the wavefunction are able to influence each other, which is not the case in standard quantum mechanics. 17:20: Check out our episode on the many-worlds or Everett-Wheeler telephone for juicy details on non-linear quantum mechanics. 17:45: ... that produce hopeless contradictions between general relativity and quantum ... 17:58: ... quantum mechanics and quantum field theory assume a well-defined underlying ... 18:22: Resolving that has been the major work of all of our searches for quantum gravity and theories of everything. 17:58: ... quantum mechanics and quantum field theory assume a well-defined underlying framework, upon which all the ... 18:22: Resolving that has been the major work of all of our searches for quantum gravity and theories of everything. 17:13: But in general it means different branches of the wavefunction are able to influence each other, which is not the case in standard quantum mechanics. 17:20: Check out our episode on the many-worlds or Everett-Wheeler telephone for juicy details on non-linear quantum mechanics. 17:45: ... that produce hopeless contradictions between general relativity and quantum mechanics. ... 17:58: ... quantum mechanics and quantum field theory assume a well-defined underlying framework, ...
	2022-02-23: Are Cosmic Strings Cracks in the Universe? 00:00: ... a nice, clear ice cube for your drinks, it’s important to consider quantum fields.   First, boil to release dissolved gasses, ... 00:58: ... exist, we need to understand phase transitions   in quantum fields - we need to see how a whole  universe can freeze like a ... 04:51: ... just like a ball sitting at the top of a hill. But  the slightest quantum jiggle would send the ball,   or the Higgs, rolling down in a ... 07:33: ... that’s for another time. OK, so we’ve managed to freeze the   quantum fields amidst the first bawlings of the baby universe and woven ... 12:19: ... about the origins of the universe, or the nature  of quantum fields, or the validity of string   theory. Many murky ... 00:58: ... of this field that can give us our cosmic strings.   Now a quantum field is just some numerical  property that the fabric of space can ... 00:00: ... meet - what we call topological defects. So where do quantum fields come into all of this? Well, it turns out the   universe is a ... 00:58: ... exist, we need to understand phase transitions   in quantum fields - we need to see how a whole  universe can freeze like a badly-made ... 07:33: ... that’s for another time. OK, so we’ve managed to freeze the   quantum fields amidst the first bawlings of the baby universe and woven some ... 12:19: ... about the origins of the universe, or the nature  of quantum fields, or the validity of string   theory. Many murky mysteries may ... 00:58: ... exist, we need to understand phase transitions   in quantum fields - we need to see how a whole  universe can freeze like a badly-made ... 07:33: ... that’s for another time. OK, so we’ve managed to freeze the   quantum fields amidst the first bawlings of the baby universe and woven some cosmic ... 00:58: ... But at very high temperatures,   the complexities of the quantum fields sort of  get ironed out, a little like how the complex   ... 00:00: ... a nice, clear ice cube for your drinks, it’s important to consider quantum fields.   First, boil to release dissolved gasses, then make sure the ... 04:51: ... just like a ball sitting at the top of a hill. But  the slightest quantum jiggle would send the ball,   or the Higgs, rolling down in a random ... 00:58: ... Big Bang energy,   formed from topological defects in the quantum fields, aka cosmic strings. They have subatomic   thickness but ...
	2022-02-16: Is The Wave Function The Building Block of Reality? 00:03: ... the world of quantum mechanics, it’s no big deal for particles to be in multiple different ... 00:49: ... quantum mechanics, particles don’t have definite properties. Rather they are ... 01:24: ... decayed OR not, and the cat is alive or dead, not alive and dead. The quantum becomes classical at some point between the subatomic and the ... 02:24: ... first proposed by Werner Heisenberg, one of the principle founders of quantum theory. Heisenberg and his friend Neils Bohr were convinced that this ... 03:24: ... forever, splitting into parallel realities. And we have the idea of quantum decoherence, where different parts of the wave function simply become ... 04:17: ... to become known as GRW theory - the first in a new class of alternate quantum theories called “objective collapse ... 04:54: To understand how objective collapse theories work, we need just a little more quantum mechanics. 06:04: ... collapse in just the right way to explain why subatomic systems could be quantum but large systems were always ... 06:41: ... hits are very rare. It’s incredibly unlikely that a single isolated quantum particle will undergo collapse during the course of an ... 06:53: ... wave function of the entire system. Any attempt to measure an isolated quantum system necessarily means bringing lots of particles into the picture - ... 07:17: ... depends on the number of particles involved. Small things can stay quantum, but the chance of collapse to classicality increases with size, and big ... 08:55: ... explain two mysteries of physics. 1. What causes the transition from quantum to classical? And 2. Why can’t gravity be quantized like the other ... 09:25: ... Quantum mechanics rules when things are small, but add enough mass, and the ... 10:19: ... to the Schrödinger equation, they are not mere interpretations of quantum mechanics — they are distinct theories with unique predictions. This ... 11:09: ... indirect signs of collapse models. For example, the models imply that a quantum wave function will be randomly tossed about and jostled by gravity or ... 12:55: ... in physics. And one that we’ll be coming back to. What, in fact, is the quantum wave function? And how does this abstract system of shifting realities ... 03:24: ... forever, splitting into parallel realities. And we have the idea of quantum decoherence, where different parts of the wave function simply become unable to ... 08:55: ... because gravity isn’t quantum. They proposed that gravity and the three quantum forces are diametrically ... 00:03: ... the world of quantum mechanics, it’s no big deal for particles to be in multiple different states at the ... 00:49: ... quantum mechanics, particles don’t have definite properties. Rather they are described by ... 02:24: ... was real. It’s a central part of their Copenhagen interpretation of quantum mechanics. But neither physicist claimed to know where or how wave function ... 04:54: To understand how objective collapse theories work, we need just a little more quantum mechanics. 09:25: ... Quantum mechanics rules when things are small, but add enough mass, and the gravity of the ... 10:19: ... to the Schrödinger equation, they are not mere interpretations of quantum mechanics — they are distinct theories with unique predictions. This means that, ... 00:49: ... quantum mechanics, particles don’t have definite properties. Rather they are described by something ... 09:25: ... Quantum mechanics rules when things are small, but add enough mass, and the gravity of the ... 11:09: ... about and jostled by gravity or some other collapsing field. If the quantum object happens to be electrically charged, then the constant jiggling and ... 06:41: ... hits are very rare. It’s incredibly unlikely that a single isolated quantum particle will undergo collapse during the course of an ... 02:24: ... enough, because it’s confusing. Quantum superpositions can involve many quantum particles. So how far can the superposition extend? The atom, the radioactive ... 04:17: ... to become known as GRW theory - the first in a new class of alternate quantum theories called “objective collapse ... 02:24: ... first proposed by Werner Heisenberg, one of the principle founders of quantum theory. Heisenberg and his friend Neils Bohr were convinced that this wave ... 11:09: ... indirect signs of collapse models. For example, the models imply that a quantum wave function will be randomly tossed about and jostled by gravity or some ... 12:55: ... in physics. And one that we’ll be coming back to. What, in fact, is the quantum wave function? And how does this abstract system of shifting realities give ... 11:09: ... indirect signs of collapse models. For example, the models imply that a quantum wave function will be randomly tossed about and jostled by gravity or some other ... 12:55: ... in physics. And one that we’ll be coming back to. What, in fact, is the quantum wave function? And how does this abstract system of shifting realities give rise to our ... 07:17: ... this “hitting” mechanism gives a potential explaination for the quantum-classical divide - it simply depends on the number of particles involved. Small ... 00:03: ... scale of human beings - even though our world is made entirely of quantum-weird building blocks. The explanations of this transition range from the ...
	2022-02-10: The Nature of Space and Time AMA 00:03: ... the planck time and we know this because general relativity and quantum mechanics come into impossible conflict below these planck units of ...
	2022-01-27: How Does Gravity Escape A Black Hole? 03:17: First we’ll see what Einstein has to say on the matter, and then we’ll go deeper, into the speculative realm of quantum gravity. 05:54: ... believe that general relativity needs to be replaced by a theory of quantum gravity to explain the behavior of gravity in these ... 06:03: So can gravity escape from a “real” black hole of quantum gravity? 06:08: Now in quantum mechanics - or more specifically quantum field theory - forces are mediated by particles, not by the geometry of spacetime. 06:28: In theories of quantum gravity, the gravitational force should probably also have a mediating particle - usually called the graviton. 07:55: That’s easy - these are virtual particles, and in quantum field theory, virtual particles are not restricted by the speed of light. 08:39: ... talking about the classical gravity of Einstein or some deeper theory of quantum ... 13:06: ... ingenious method for simulating the insane amount of information in the quantum wavefunction with density functional theory, and then went from the tiny ... 13:25: Starting with the quantum, manonthedollar asks - given the incredible amount of power required to simulate quantum interactions... 06:08: Now in quantum mechanics - or more specifically quantum field theory - forces are mediated by particles, not by the geometry of spacetime. 07:55: That’s easy - these are virtual particles, and in quantum field theory, virtual particles are not restricted by the speed of light. 06:08: Now in quantum mechanics - or more specifically quantum field theory - forces are mediated by particles, not by the geometry of spacetime. 07:55: That’s easy - these are virtual particles, and in quantum field theory, virtual particles are not restricted by the speed of light. 03:17: First we’ll see what Einstein has to say on the matter, and then we’ll go deeper, into the speculative realm of quantum gravity. 05:54: ... believe that general relativity needs to be replaced by a theory of quantum gravity to explain the behavior of gravity in these ... 06:03: So can gravity escape from a “real” black hole of quantum gravity? 06:28: In theories of quantum gravity, the gravitational force should probably also have a mediating particle - usually called the graviton. 08:39: ... talking about the classical gravity of Einstein or some deeper theory of quantum gravity. ... 13:25: Starting with the quantum, manonthedollar asks - given the incredible amount of power required to simulate quantum interactions... 06:08: Now in quantum mechanics - or more specifically quantum field theory - forces are mediated by particles, not by the geometry of spacetime. 13:06: ... ingenious method for simulating the insane amount of information in the quantum wavefunction with density functional theory, and then went from the tiny to the ...
	2022-01-19: How To Build The Universe in a Computer 11:13: ... we discussed recently,   a full quantum description of the world  contains unthinkably more information ... 11:23: No conceivable technology could  fully simulate a quantum universe,   except perhaps a cosmically-sized quantum computer. 11:13: ... we discussed recently,   a full quantum description of the world  contains unthinkably more information than is ... 11:23: No conceivable technology could  fully simulate a quantum universe,   except perhaps a cosmically-sized quantum computer.
	2022-01-12: How To Simulate The Universe With DFT 00:00: ... in the observable universe to solve the schrodinger equation and do full quantum simulation of some chunk of the universe, how big would that chunk ... 00:18: That’s how insanely information dense the quantum wavefunction really is. 00:38: Quantum mechanics allows us to predict the behavior of the subatomic world with truly incredible precision. 01:12: But for almost every practical use you’d need to do that math for multiple quantum particles interacting - and then the blackboard doesn’t cut it. 01:48: ... describes how the wavefunction of a quantum particle - that’s this psi thing - changes over space, assuming the ... 02:30: ... time independent Schrodinger equation isn’t the be all and end all of quantum mechanics - it’s an approximation that works for slower moving particles ... 02:39: But it’s where we start learning quantum mechanics, and it works for a lot of simple cases. 05:39: ... in quantum mechanics often means finding a solution to a problem that’s much ... 05:52: ... to solve the impossible case of many interacting quantum particles, we should start by thinking about the completely solvable ... 06:48: In quantum mechanics, we’re dealing with the wavefunction, and the wavefunction fills all of configuration space. 06:59: ... only that, but quantum mechanics contains non-local correlations which arise because the ... 08:02: But if we want to keep the quantum behaviour of quantum mechanics we can’t throw away most of configuration space like we do in Newtonian mechanics. 08:22: Doing so destroys quantum correlations. 08:26: ... equation for more than a few particles, researchers still manage to do quantum simulations of some extremely complex ... 08:49: ... to tackling the extreme dimensionality problem when solving realistic quantum ... 09:01: ... an example, here’s a quantum simulation of the millions of atoms comprising the capsid of a virus ... 09:41: And through a very mysterious quality of the quantum world, it's possible to map that fake solution to real answers. 08:02: But if we want to keep the quantum behaviour of quantum mechanics we can’t throw away most of configuration space like we do in Newtonian mechanics. 08:22: Doing so destroys quantum correlations. 06:59: ... particles, for example through the Pauli exclusion principle and through quantum entanglement. ... 00:38: Quantum mechanics allows us to predict the behavior of the subatomic world with truly incredible precision. 02:30: ... time independent Schrodinger equation isn’t the be all and end all of quantum mechanics - it’s an approximation that works for slower moving particles that ... 02:39: But it’s where we start learning quantum mechanics, and it works for a lot of simple cases. 05:39: ... in quantum mechanics often means finding a solution to a problem that’s much simpler than ... 06:48: In quantum mechanics, we’re dealing with the wavefunction, and the wavefunction fills all of configuration space. 06:59: ... only that, but quantum mechanics contains non-local correlations which arise because the position of one ... 08:02: But if we want to keep the quantum behaviour of quantum mechanics we can’t throw away most of configuration space like we do in Newtonian mechanics. 02:30: ... time independent Schrodinger equation isn’t the be all and end all of quantum mechanics - it’s an approximation that works for slower moving particles that don’t ... 01:48: ... describes how the wavefunction of a quantum particle - that’s this psi thing - changes over space, assuming the particle is ... 06:59: ... contains non-local correlations which arise because the position of one quantum particle can restrict the set of possible positions for the other particles, for ... 01:48: ... describes how the wavefunction of a quantum particle - that’s this psi thing - changes over space, assuming the particle is in ... 01:12: But for almost every practical use you’d need to do that math for multiple quantum particles interacting - and then the blackboard doesn’t cut it. 05:52: ... to solve the impossible case of many interacting quantum particles, we should start by thinking about the completely solvable case of many ... 01:12: But for almost every practical use you’d need to do that math for multiple quantum particles interacting - and then the blackboard doesn’t cut it. 00:00: ... in the observable universe to solve the schrodinger equation and do full quantum simulation of some chunk of the universe, how big would that chunk ... 09:01: ... an example, here’s a quantum simulation of the millions of atoms comprising the capsid of a virus done using ... 08:26: ... equation for more than a few particles, researchers still manage to do quantum simulations of some extremely complex ... 08:49: ... to tackling the extreme dimensionality problem when solving realistic quantum systems. ... 00:18: That’s how insanely information dense the quantum wavefunction really is. 12:51: ... functional theory has now been used to model the intricate quantum-level behavior of chemical reactions, of complex molecules even as far as DNA ...
	2021-12-20: What Happens If A Black Hole Hits Earth? 17:30: ... principle, which we covered previously. It, says that vibrations in a quantum field on the surface of a 4-D hyperbolic space are equivalent to objects ... 18:16: ... potentially detect deviations from general relativity in the form of quantum fluctuations near the event horizon that might be amplified by ... 19:14: ... 3+1 in my experience. And for that matter all hairballs are technically quantum. This teaches us one important lesson: next time you clean up after your ... 17:30: ... principle, which we covered previously. It, says that vibrations in a quantum field on the surface of a 4-D hyperbolic space are equivalent to objects ... 18:16: ... potentially detect deviations from general relativity in the form of quantum fluctuations near the event horizon that might be amplified by gravitational lensing. ...
	2021-12-10: 2021 End of Year AMA! 00:02: ... the so so so we have this strange uh description of of the forces in quantum mechanics in particular in quantum field theory where two particles ...
	2021-11-17: Are Black Holes Actually Fuzzballs? 01:00: At the central singularity, the known laws of physics break down - general relativity comes into irreconcilable conflict with quantum mechanics. 03:34: And that violates a very deep and fundamental law - the law of conservation of quantum information. 03:40: This threat of erasure of quantum information in a hairless black hole is the black hole information paradox. 04:17: Ultimately, the black hole paradoxes stem from the disagreement between quantum mechanics and general relativity. 04:23: The impossibility of the central singularity is the most obvious place where we need a theory of quantum gravity. 04:32: A theory of quantum gravity would have really helped Stephen Hawking in deriving his eponymous radiation. 04:49: ... pure general relativity but then analyze its effect on the surrounding quantum fields, which only worked if the gravity at the horizon was relatively ... 05:09: ... gravity starts to get quantum even above the event horizon, then it may be possible to actually encode ... 05:22: And it turns out that our most advanced theory of quantum gravity can do this quite neatly. 08:39: This property of black holes is actually quite hard to reproduce in theories of quantum gravity. 09:09: ... and branes, like the hairball coughed up from some hyperdimensional quantum ... 09:39: ... most amazing element of the fuzzball paradigm is the discovery that quantum gravity effects might not just be important at the center of the black ... 13:26: I should also add that fuzzballs are not the only quantum extension of the GR black hole. 13:38: And they’re one of our best hopes for understanding the union of general relativity with the quantum. 09:09: ... and branes, like the hairball coughed up from some hyperdimensional quantum cat. ... 13:26: I should also add that fuzzballs are not the only quantum extension of the GR black hole. 04:49: ... pure general relativity but then analyze its effect on the surrounding quantum fields, which only worked if the gravity at the horizon was relatively weak, in ... 04:23: The impossibility of the central singularity is the most obvious place where we need a theory of quantum gravity. 04:32: A theory of quantum gravity would have really helped Stephen Hawking in deriving his eponymous radiation. 04:49: ... worked if the gravity at the horizon was relatively weak, in which case quantum gravity effects shouldn’t play a ... 05:22: And it turns out that our most advanced theory of quantum gravity can do this quite neatly. 08:39: This property of black holes is actually quite hard to reproduce in theories of quantum gravity. 09:39: ... most amazing element of the fuzzball paradigm is the discovery that quantum gravity effects might not just be important at the center of the black hole but ... 04:49: ... worked if the gravity at the horizon was relatively weak, in which case quantum gravity effects shouldn’t play a ... 09:39: ... most amazing element of the fuzzball paradigm is the discovery that quantum gravity effects might not just be important at the center of the black hole but instead ... 01:00: At the central singularity, the known laws of physics break down - general relativity comes into irreconcilable conflict with quantum mechanics. 04:17: Ultimately, the black hole paradoxes stem from the disagreement between quantum mechanics and general relativity.
	2021-11-10: What If Our Understanding of Gravity Is Wrong? 15:45: ... if the configuration   space Lagrangian seems to bridge  quantum mechanics and relativity, what's missing to make this  a theory of ... 16:31: Check our episodes on Noether’s theorem, quantum invariance, and the electroweak force for some details, but we probably need to go even deeper. 15:45: ... if the configuration   space Lagrangian seems to bridge  quantum mechanics and relativity, what's missing to make this  a theory of ...
	2021-11-02: Is ACTION The Most Fundamental Property in Physics? 05:24: ... and into our modern theories - in particular general relativity and quantum mechanics. And perhaps in these we’ll find clues as to what the action ... 08:31: OK, it seems like we’re getting somewhere. Let’s see if quantum mechanics will get us any deeper, or perhaps just make everything more confusing. 08:39: ... with the famous double slit experiment, as we so often do when talking quantum mechanics. In it, a stream of quantum particles are launched at a ... 09:56: ... Dirac very nearly figured this out. He realized that a quantum analog of the action existed that was related to the integrated time ... 10:26: ... along some hypothetical path. Feynman realized that the path of a quantum object could be determined by adding together all possible paths that ... 11:12: ... is Feynman’s path integral formulation of quantum mechanics, and it exactly reproduces the predictions of previous ... 11:59: ... to guess, particles tend to end up near the stationary points of the quantum action. In the path integral, this happens for paths that take the ... 12:16: ... spacetime, where the shortest path minimizes proper time. In quantum mechanics configuration space could mean phase space - the space of ... 12:59: ... application of the quantum action principle to the evolution through quantum states underpins ... 13:16: Well it turns out that this equation is just the Lagrangian for a spin-½ quantum field. 13:23: ... there’s a Lagrangian for each quantum field which describes how that field and its particles tend to evolve. ... 17:54: ... assumptions (infinite/finite, discrete/continuous spacetime, invariance, quantum etc.) then constructor theory gives us insights as to what math is ... 09:56: ... experiment. It would lead to constructive interference only where this quantum action varied slowly - near it’s stationary points, just like with classical ... 10:26: ... together all possible paths that particle could take weighted by this quantum action. In this case the quantum action doesn’t come from adding up kinetic ... 11:59: ... to guess, particles tend to end up near the stationary points of the quantum action. In the path integral, this happens for paths that take the shortest ... 12:59: ... application of the quantum action principle to the evolution through quantum states underpins modern ... 10:26: ... particle could take weighted by this quantum action. In this case the quantum action doesn’t come from adding up kinetic minus potential energy nor the proper time. ... 12:59: ... application of the quantum action principle to the evolution through quantum states underpins modern quantum theory. ... 09:56: ... experiment. It would lead to constructive interference only where this quantum action varied slowly - near it’s stationary points, just like with classical ... 11:12: ... mechanics. And it’s no coincidence, because the path integral is the quantum analog of the Principle of Least ... 12:59: ... just for a moment. His eponymous equation was derived to describe the quantum evolution of the ... 13:16: Well it turns out that this equation is just the Lagrangian for a spin-½ quantum field. 13:23: ... there’s a Lagrangian for each quantum field which describes how that field and its particles tend to evolve. ... 08:39: ... the spots make out this series of bands - an interference pattern. The quantum interpretation of this is that the particle travels between its source and the screen ... 05:24: ... and into our modern theories - in particular general relativity and quantum mechanics. And perhaps in these we’ll find clues as to what the action is really ... 08:31: OK, it seems like we’re getting somewhere. Let’s see if quantum mechanics will get us any deeper, or perhaps just make everything more confusing. 08:39: ... with the famous double slit experiment, as we so often do when talking quantum mechanics. In it, a stream of quantum particles are launched at a barrier with two ... 11:12: ... is Feynman’s path integral formulation of quantum mechanics, and it exactly reproduces the predictions of previous versions of ... 12:16: ... spacetime, where the shortest path minimizes proper time. In quantum mechanics configuration space could mean phase space - the space of possible ... 11:12: ... and it exactly reproduces the predictions of previous versions of quantum mechanics - for example, Schrodinger’s wave mechanics that talks about the evolution ... 12:16: ... spacetime, where the shortest path minimizes proper time. In quantum mechanics configuration space could mean phase space - the space of possible positions and ... 10:26: ... along some hypothetical path. Feynman realized that the path of a quantum object could be determined by adding together all possible paths that particle ... 08:39: ... as we so often do when talking quantum mechanics. In it, a stream of quantum particles are launched at a barrier with two slits cut in it. When the stream ... 12:16: ... momenta - or it could be more general state space, representing all the quantum states that a system could evolve ... 12:59: ... application of the quantum action principle to the evolution through quantum states underpins modern quantum theory. Back to Paul Dirac just for a moment. ... 08:39: ... the screen not as a particle with a well-defined trajectory, but as a quantum wavefunction that represents all possible paths it could take. The wavefunction at ...
	2021-10-20: Will Constructor Theory REWRITE Physics? 01:43: ... mechanics and electromagnetism and so on from two master theories: quantum mechanics and Einstein’s general ... 02:40: ... uses theories like general relativity and quantum mechanics, along with more fundamental conservation laws, or principles, ... 03:05: Constructor theory is inspired by information theory and the theory of quantum computation. 03:11: ... David Deutsch says, if a quantum computer can, in principle, simulate any process in physics, then all of ... 04:42: For example, understanding the union of quantum mechanics and general relativity. 05:44: Again, this task is impossible, since it’s ruled out by the laws of quantum mechanics and the principle of conservation of energy. 08:07: For example Chiara Marletto has used constructor theory to describe a scenario for testing whether gravity is quantum in nature. 08:16: And we certainly don’t have a mechanistic theory for quantum gravity. 08:34: For example, for systems of quantum information there’s a particular task that is possible that is impossible for classical systems. 08:43: That task is entanglement between the information elements - the qubits in the quantum case. 09:17: From the definitions of what an information medium is, Marletto argues that this chain of quantum elements is equivalent to a quantum field. 09:27: And she argues that only a "superinformation medium" - aka a quantum field - could mediate the entanglement of two spatially separated qubits. 09:35: ... could induce entanglement between separated qubits, then gravity has quantum ... 09:47: This is cool because it gives us an experimental test of quantum gravity that has absolutely no dependence on a particular theory of quantum gravity. 09:55: It doesn't need the dynamical laws of such a theory, or even of quantum mechanics or general relativity as they currently stand. 10:51: ... Heisenberg came up with the first version of quantum mechanics by stripping away all but the bare facts about the nature of ... 12:21: Last time we talked about the latest ideas  on the weird world of quantum tunneling.   Let’s see what you had to say. 12:30: ... a particle  tunnel through .. nothing. As in could it   quantum teleport even through empty space in  Fact do particles even travel ... 08:43: That task is entanglement between the information elements - the qubits in the quantum case. 03:05: Constructor theory is inspired by information theory and the theory of quantum computation. 03:11: ... physics, then all of physics can be expressed in terms of the theory of quantum computation. ... 09:17: From the definitions of what an information medium is, Marletto argues that this chain of quantum elements is equivalent to a quantum field. 09:27: And she argues that only a "superinformation medium" - aka a quantum field - could mediate the entanglement of two spatially separated qubits. 08:16: And we certainly don’t have a mechanistic theory for quantum gravity. 09:47: This is cool because it gives us an experimental test of quantum gravity that has absolutely no dependence on a particular theory of quantum gravity. 01:43: ... mechanics and electromagnetism and so on from two master theories: quantum mechanics and Einstein’s general ... 02:40: ... uses theories like general relativity and quantum mechanics, along with more fundamental conservation laws, or principles, to rule ... 04:42: For example, understanding the union of quantum mechanics and general relativity. 05:44: Again, this task is impossible, since it’s ruled out by the laws of quantum mechanics and the principle of conservation of energy. 09:55: It doesn't need the dynamical laws of such a theory, or even of quantum mechanics or general relativity as they currently stand. 10:51: ... Heisenberg came up with the first version of quantum mechanics by stripping away all but the bare facts about the nature of ... 09:35: ... could induce entanglement between separated qubits, then gravity has quantum properties. ... 12:30: ... a particle  tunnel through .. nothing. As in could it   quantum teleport even through empty space in  Fact do particles even travel at all ... 12:21: Last time we talked about the latest ideas  on the weird world of quantum tunneling.   Let’s see what you had to say. 08:20: ... systems of information - called information media - and how systems of quantum  information - or superinformation  media - must differ from regular ...
	2021-10-13: New Results in Quantum Tunneling vs. The Speed of Light 00:10: ... efforts in quantum tunneling - both theory and experiment - show that superluminal motion ... 00:26: Quantum tunneling is one of the weirder phenomena in the generally very weird world of quantum mechanics. 00:32: It describes how quantum particles are able to move across seemingly impenetrable barriers - for example, when atomic nuclei decay. 00:40: ... it’s not just the Houdini-like power that makes the quantum world weird - it’s also that the tunneling motion may move particles ... 00:55: Now we covered quantum tunneling a long long time ago - in fact it was the first video we did on quantum mechanics. 01:05: I mean, we’ve learned a lot on this show and so we can dig deeper into the FTL aspect of quantum tunneling. 01:12: ... are bringing us closer to understanding the superluminal prospects of quantum ... 01:25: But first, a quick recap of quantum tunneling. 01:51: ... similar thing happens in the world of quantum mechanics, where particles are pushed and pulled by the fundamental ... 02:30: This is quantum tunneling. 02:31: The key to the escape is quantum uncertainty. 02:35: Between observations, quantum particles don’t have well defined properties - and that includes their positions. 04:31: ... to determine the so-called tunneling time because, in the fuzzy world of quantum mechanics, it’s hard to even define what we mean by tunnelling time or ... 06:45: It’s hard to measure the travel time of a quantum train OR a quantum wavefunction because it’s hard to define the start and end points. 08:22: Can quantum tunneling really speed up the transmission of the information contained in that message? 08:50: ... cut-off front end of the old wavefunction, or the first carriage of the quantum ... 10:40: In 2020, a paper was published in the journal Nature that used the swiveling axis of a particle’s quantum spin as the clock hand. 12:28: All signals in our universe, whether via quantum tunneling or quantum entanglement, seem to be bound by the same limits imposed by relativity. 13:38: ... as a scientist I may not know everything about the depths of quantum tunneling, but as a New Yorker I know that every tunnel needs a name so ... 13:59: ... goes through solid bedrock so there’s a low probability that your quantum wavefunction will make it through - but if you do then the trip is ... 16:55: It's hypothesized that portkeys are based on wormhole technology, but actually they may well use quantum tunneling. 17:04: And that process actually evades Hogwart's security wards because the wizards are rubbish at quantum mechanics. 12:28: All signals in our universe, whether via quantum tunneling or quantum entanglement, seem to be bound by the same limits imposed by relativity. 00:26: Quantum tunneling is one of the weirder phenomena in the generally very weird world of quantum mechanics. 00:55: Now we covered quantum tunneling a long long time ago - in fact it was the first video we did on quantum mechanics. 01:51: ... similar thing happens in the world of quantum mechanics, where particles are pushed and pulled by the fundamental forces, forming ... 04:31: ... to determine the so-called tunneling time because, in the fuzzy world of quantum mechanics, it’s hard to even define what we mean by tunnelling time or time for ... 17:04: And that process actually evades Hogwart's security wards because the wizards are rubbish at quantum mechanics. 00:32: It describes how quantum particles are able to move across seemingly impenetrable barriers - for example, when atomic nuclei decay. 02:35: Between observations, quantum particles don’t have well defined properties - and that includes their positions. 10:40: In 2020, a paper was published in the journal Nature that used the swiveling axis of a particle’s quantum spin as the clock hand. 06:45: It’s hard to measure the travel time of a quantum train OR a quantum wavefunction because it’s hard to define the start and end points. 08:50: ... cut-off front end of the old wavefunction, or the first carriage of the quantum train. ... 13:38: ... every tunnel needs a name so I’m proud to announce the Henry Van Styn Quantum Tunnel. ... 00:10: ... efforts in quantum tunneling - both theory and experiment - show that superluminal motion may be ... 00:26: Quantum tunneling is one of the weirder phenomena in the generally very weird world of quantum mechanics. 00:55: Now we covered quantum tunneling a long long time ago - in fact it was the first video we did on quantum mechanics. 01:05: I mean, we’ve learned a lot on this show and so we can dig deeper into the FTL aspect of quantum tunneling. 01:12: ... are bringing us closer to understanding the superluminal prospects of quantum tunneling. ... 01:25: But first, a quick recap of quantum tunneling. 02:30: This is quantum tunneling. 08:22: Can quantum tunneling really speed up the transmission of the information contained in that message? 12:28: All signals in our universe, whether via quantum tunneling or quantum entanglement, seem to be bound by the same limits imposed by relativity. 13:38: ... as a scientist I may not know everything about the depths of quantum tunneling, but as a New Yorker I know that every tunnel needs a name so I’m proud ... 16:55: It's hypothesized that portkeys are based on wormhole technology, but actually they may well use quantum tunneling. 00:10: ... efforts in quantum tunneling - both theory and experiment - show that superluminal motion may be ... 02:31: The key to the escape is quantum uncertainty. 06:45: It’s hard to measure the travel time of a quantum train OR a quantum wavefunction because it’s hard to define the start and end points. 13:59: ... goes through solid bedrock so there’s a low probability that your quantum wavefunction will make it through - but if you do then the trip is instantaneous, and ... 06:30: ... if this was a quantum-tunneling train, then only the front carriage would make it through the tunnel, ...
	2021-10-05: Why Magnetic Monopoles SHOULD Exist 04:24: But what about quantum mechanics? 04:26: ... quantum theory first appeared it quickly revolutionized our understanding of ... 04:37: ... arose automatically from requiring that the equations of quantum mechanics had a particular symmetry - the measurements they predict are ... 05:09: ... particular, the magnetic field emerging from the quantum theory must have zero divergence - its field lines can never end - so it ... 05:27: Quantum mechanics, as the saying goes, forbids it. 06:52: In quantum mechanics, this works by shifting the phase of the particle’s wavefunction. 08:45: Charge turns out to be quantized, so quantum mechanics doesn’t actually forbid monopoles. 14:55: ... week we talked about how quantum spin leads to the universe as we know it - for example all the structure ... 15:08: We represented very distinctly separated electron energy levels in our explanation of how fermion’s can’t occupy identical quantum states. 15:16: ... it’s possible to have two electrons at the same energy but different quantum states by allowing for opposite spin ... 15:29: ... more careful I would have said that we were trying to represent separate quantum states, not energy levels in an ... 15:39: ... that we don’t need to keep talking about spin as this incomprehensible quantum property that has no intuitive analogy - reminding us that Hans Ohanian, ... 16:49: Fermions never occupy the same quantum states. 16:51: When degeneracy pressure is broken it’s because new space in quantum states opens up. 18:01: Or maybe you could just use USBC - they’re spin-2 bosons like gravitons, so easily understood with a basic theory of quantum gravity. 04:26: ... our understanding of electromagnetism by explaining it in terms of quantum fields rather than charges and ... 18:01: Or maybe you could just use USBC - they’re spin-2 bosons like gravitons, so easily understood with a basic theory of quantum gravity. 04:24: But what about quantum mechanics? 04:37: ... arose automatically from requiring that the equations of quantum mechanics had a particular symmetry - the measurements they predict are unaltered ... 05:27: Quantum mechanics, as the saying goes, forbids it. 06:52: In quantum mechanics, this works by shifting the phase of the particle’s wavefunction. 08:45: Charge turns out to be quantized, so quantum mechanics doesn’t actually forbid monopoles. 15:39: ... that we don’t need to keep talking about spin as this incomprehensible quantum property that has no intuitive analogy - reminding us that Hans Ohanian, in his ... 14:55: ... week we talked about how quantum spin leads to the universe as we know it - for example all the structure of ... 15:08: We represented very distinctly separated electron energy levels in our explanation of how fermion’s can’t occupy identical quantum states. 15:16: ... it’s possible to have two electrons at the same energy but different quantum states by allowing for opposite spin ... 15:29: ... more careful I would have said that we were trying to represent separate quantum states, not energy levels in an ... 16:49: Fermions never occupy the same quantum states. 16:51: When degeneracy pressure is broken it’s because new space in quantum states opens up. 04:26: ... quantum theory first appeared it quickly revolutionized our understanding of ... 05:09: ... particular, the magnetic field emerging from the quantum theory must have zero divergence - its field lines can never end - so it can’t ...
	2021-09-21: How Electron Spin Makes Matter Possible 00:26: ... now we’ve established that quantum spin is very weird. We talked all about that recently - how electrons ... 01:44: ... no limit to the number of photons you can add - all of them in the same quantum state. But not fermions - no two fermions can share the same quantum ... 03:19: ... degrees. So a spinor’s rotational weirdness is not necessarily all that “quantum” - it’s a natural function of how it’s connected to the universe. So ... 05:59: ... Well electrons don’t really rotate in the classical sense. They’re quantum objects described by a quantum wavefunction. A wavefunction is this ... 08:00: ... just doing addition and subtraction here. Let’s think about the quantum state of an electron. We’ll call it Psi. Psi gives the distribution of ... 10:32: ... atom, but this works for any two possible wavefunctions - two possible quantum states - that our electrons could have. If electron A is in the ground ... 12:37: ... vanish electrons - so the transition of an electron into an occupied quantum state is ... 13:03: ... anti symmetric wavefunctions cannot have multiple particles in the same quantum ... 13:25: ... fact that you need to use spinors in the Dirac equation - which is the quantum equation of motion for electrons and other spin-½ ... 18:44: ... tells us that Space Time made him realize that he’s more interested in quantum physics than astrophysics. Hey, at least you didn’t devote decades of ... 03:19: ... degrees. So a spinor’s rotational weirdness is not necessarily all that “quantum” - it’s a natural function of how it’s connected to the universe. So allow ... 13:25: ... fact that you need to use spinors in the Dirac equation - which is the quantum equation of motion for electrons and other spin-½ ... 00:26: ... around. That particular weirdness is not just another cute case of quantum mechanics being a bit silly. The fact that some particles have this property is ... 18:44: ... kidding. I love astrophysics like my awe-inspiring first born child. But quantum mechanics is my weird and brilliant and deeply compelling second born and I love ... 05:59: ... Well electrons don’t really rotate in the classical sense. They’re quantum objects described by a quantum wavefunction. A wavefunction is this thing that ... 18:44: ... tells us that Space Time made him realize that he’s more interested in quantum physics than astrophysics. Hey, at least you didn’t devote decades of your ... 00:26: ... now we’ve established that quantum spin is very weird. We talked all about that recently - how electrons have ... 01:44: ... no limit to the number of photons you can add - all of them in the same quantum state. But not fermions - no two fermions can share the same quantum state, ... 08:00: ... just doing addition and subtraction here. Let’s think about the quantum state of an electron. We’ll call it Psi. Psi gives the distribution of ... 12:37: ... vanish electrons - so the transition of an electron into an occupied quantum state is ... 13:03: ... anti symmetric wavefunctions cannot have multiple particles in the same quantum state. ... 10:32: ... atom, but this works for any two possible wavefunctions - two possible quantum states - that our electrons could have. If electron A is in the ground state ... 05:59: ... rotate in the classical sense. They’re quantum objects described by a quantum wavefunction. A wavefunction is this thing that holds information about the ...
	2021-09-15: Neutron Stars: The Most Extreme Objects in the Universe 04:04: ... of the fermion family can’t occupy   the same quantum state. The matter has  become what we call degenerate, and ...
	2021-09-07: First Detection of Light from Behind a Black Hole 12:26: Blinkist has an array of categories – from the science of Quantum Mechanics to philosophy to futurism. 12:37: ... telephone, where we explored how to send messages across the quantum ... 12:26: Blinkist has an array of categories – from the science of Quantum Mechanics to philosophy to futurism. 12:37: ... telephone, where we explored how to send messages across the quantum multiverse. ...
	2021-08-18: How Vacuum Decay Would Destroy The Universe 00:21: ... universe is largely defined by the properties   of the quantum fields that pervade all space. The quantum fields give rise to the ... 01:15: ... that expands at the speed of light, rewriting  the nature of the quantum fields as it ... 01:24: To understand whether and when this might happen,   we first need to understand the  quantum fields that it threatens. 01:31: ... axes, or deform or more complex ways.   We can think of each quantum field as a set of these modes of oscillation. And each quantum ... 02:18: ... like the deformed ring, a quantum field  wants to return to its equilibrium position.   ... 02:52: ... most quantum fields, the minimum  energy is where the field value is ... 03:11: ... there’s one quantum field that breaks these rules. That’s the Higgs field. The minimum ... 04:00: ... dips in   our graph of energy versus field strength.  A quantum field with multiple minima   like this will tend to find its ... 04:42: ... in - well, pretty much everything, but certainly in the value of a quantum field. This results in   fluctuations in the field strength ... 06:08: ... field in a false vacuum. At a single point in space,   a quantum tunneling event drops the field into the true vacuum. This creates ... 07:01: ... true vacuum. This is vacuum decay. It’s a phase transition of the quantum fields.   In fact it has a lot of similarities with ... 01:31: ... axes, or deform or more complex ways.   We can think of each quantum field as a set of these modes of oscillation. And each quantum ... 02:18: ... like to represent this   by plotting the energy in the  quantum field versus field value.   It takes more energy to get further ... 03:11: ... there’s one quantum field that breaks these rules. That’s the Higgs field. The minimum ... 04:00: ... dips in   our graph of energy versus field strength.  A quantum field with multiple minima   like this will tend to find its way ... 04:42: ... in - well, pretty much everything, but certainly in the value of a quantum field. This results in   fluctuations in the field strength ... 07:01: ... of   these phase-transition bubbles in water or in a quantum field is called bubble ... 02:18: ... like to represent this   by plotting the energy in the  quantum field versus field value.   It takes more energy to get further away  ... 01:31: ... each quantum field as a set of these modes of oscillation. And each quantum field   - each type of oscillation - has a corresponding particle - that’s ... 00:21: ... universe is largely defined by the properties   of the quantum fields that pervade all space. The quantum fields give rise to the ... 01:15: ... that expands at the speed of light, rewriting  the nature of the quantum fields as it ... 01:24: To understand whether and when this might happen,   we first need to understand the  quantum fields that it threatens. 02:52: ... most quantum fields, the minimum  energy is where the field value is zero.   ... 07:01: ... true vacuum. This is vacuum decay. It’s a phase transition of the quantum fields.   In fact it has a lot of similarities with the sort of phase ... 04:42: ... and perhaps find itself stuck in an adjacent  dip. We call this quantum tunneling. ... 06:08: ... field in a false vacuum. At a single point in space,   a quantum tunneling event drops the field into the true vacuum. This creates a tiny ... 00:21: ... possible. In fact,   for most possible configurations of the quantum fields, no structures would exist at ... 06:08: ... surrounding Higgs field   down with it. This happens because quantum fields are connected and tug at their   adjacent points across space, ... 00:21: ... possible. In fact,   for most possible configurations of the quantum fields, no structures would exist at ... 06:08: ... surrounding Higgs field   down with it. This happens because quantum fields are connected and tug at their   adjacent points across space, ...
	2021-08-10: How to Communicate Across the Quantum Multiverse 00:00: ... Hello There. I’m Matt from a different quantum timeline. I figured out the secret truth behind quantum mechanics and ... 01:23: Everything I just described is real, but it’s also an analogy for the quantum multiverse. 01:29: ... principle. This principle also applies to the wavefunction in quantum ... 01:46: ... the Many Worlds interpretation of quantum mechanics, the universal wavefunction is the reality, encompassing all ... 02:29: ... are other ways to interpret the math of quantum mechanics that don’t require a multiverse. For example there’s the ... 02:56: ... now approaching 100 years since the discovery of quantum mechanics, and we still don’t know which of these - if any - are right. ... 03:30: ... Schrodinger equation describes how the wavefunction of a quantum system changes over space and time - and so it should completely ... 03:55: ... and even the ability to send messages between the worlds of the quantum multiverse - if it turns out that actually ... 06:28: ... equation as we usually write it is a perfectly linear equation, and in quantum mechanics it’s always assumed that linearity and the superposition ... 09:36: ... so he stumbles upon a way to communicate between the worlds of the quantum multiverse. And this time he actually tells us how to do it, inventing ... 09:57: ... spin by whether the particles are deflected to the north or south pole. Quantum particles will always be found to have a spin in the direction that you ... 11:53: You’ve now successfully transmitted a single bit of information between quantum timelines. 12:00: ... idea really just serves as a proof of concept that in a non-linear quantum mechanics, actions can influence the entire wavefunction - spanning ... 12:47: ... to summarize: either quantum mechanics is perfectly linear and you should forget I said anything, OR ... 06:28: ... tiny, that are non-linear, then everything changes. Not only can we test quantum interpretations, but we can do some things that really should be ... 00:00: ... from a different quantum timeline. I figured out the secret truth behind quantum mechanics and I’m sending it to Matt in your timeline so he can tell you. Stand ... 01:29: ... principle. This principle also applies to the wavefunction in quantum mechanics. ... 01:46: ... the Many Worlds interpretation of quantum mechanics, the universal wavefunction is the reality, encompassing all possible ... 02:29: ... are other ways to interpret the math of quantum mechanics that don’t require a multiverse. For example there’s the Copenhagen ... 02:56: ... now approaching 100 years since the discovery of quantum mechanics, and we still don’t know which of these - if any - are right. So what’s ... 06:28: ... equation as we usually write it is a perfectly linear equation, and in quantum mechanics it’s always assumed that linearity and the superposition principle hold. ... 12:00: ... idea really just serves as a proof of concept that in a non-linear quantum mechanics, actions can influence the entire wavefunction - spanning different ... 12:47: ... to summarize: either quantum mechanics is perfectly linear and you should forget I said anything, OR it’s ... 12:00: ... idea really just serves as a proof of concept that in a non-linear quantum mechanics, actions can influence the entire wavefunction - spanning different “worlds”. ... 01:23: Everything I just described is real, but it’s also an analogy for the quantum multiverse. 03:55: ... and even the ability to send messages between the worlds of the quantum multiverse - if it turns out that actually ... 09:36: ... so he stumbles upon a way to communicate between the worlds of the quantum multiverse. And this time he actually tells us how to do it, inventing what he calls ... 12:47: ... and back in time, OR we can communicate across the branches of the quantum multiverse. According to Polchinski exactly one and only one of those must be true. ... 03:55: ... and even the ability to send messages between the worlds of the quantum multiverse - if it turns out that actually ... 09:57: ... spin by whether the particles are deflected to the north or south pole. Quantum particles will always be found to have a spin in the direction that you choose to ... 00:00: ... Hello There. I’m Matt from a different quantum timeline. I figured out the secret truth behind quantum mechanics and I’m sending ... 11:53: You’ve now successfully transmitted a single bit of information between quantum timelines. 09:57: ... that you choose to align the magnets. So your choice affects the quantum wavefunction. Polchinski lays out the steps very clearly: you send a spin half ...
	2021-08-03: How An Extreme New Star Could Change All Cosmology 06:21: ... - they’d have to occupy the same energy states. But that’s forbidden by quantum mechanics - specifically, by the Pauli exclusion principle, which tells ... 08:05: ... known white dwarf it must also be the most massive. Doing a little quantum mechanics, it was found that it must weigh in at 1.32 times the Sun’s ... 14:14: ... enthusiasm, we’d probably have sunk to space-themed reaction videos and quantum mechanics based pranks. As always, thanks for everything. And today’s ... 06:21: ... - they’d have to occupy the same energy states. But that’s forbidden by quantum mechanics - specifically, by the Pauli exclusion principle, which tells us that ... 08:05: ... known white dwarf it must also be the most massive. Doing a little quantum mechanics, it was found that it must weigh in at 1.32 times the Sun’s mass. And ... 14:14: ... enthusiasm, we’d probably have sunk to space-themed reaction videos and quantum mechanics based pranks. As always, thanks for everything. And today’s extra ... 06:21: ... - they’d have to occupy the same energy states. But that’s forbidden by quantum mechanics - specifically, by the Pauli exclusion principle, which tells us that ... 14:14: ... enthusiasm, we’d probably have sunk to space-themed reaction videos and quantum mechanics based pranks. As always, thanks for everything. And today’s extra special ... 06:21: ... in the fermion family, like elelectrons, can never occupy the same quantum state. ...
	2021-07-21: How Magnetism Shapes The Universe 13:47: ... we’re covering comments from our episode on the weirdness of quantum spin, and then our episode that tried to answer the question where ... 15:15: For example Zapp Brannigan asks what percentage of quantum interactions separate into worlds versus recombining again. 16:27: The number of distinguishable worlds depends on the rate at which distinct decoherence happens - so far, far fewer than the number of quantum wiggles. 17:10: ... probabilities must be reflected in the number of worlds for each quantum outcome - because in the many worlds interpretation, an observer is more ... 18:20: ... Barefoot also point out that this divide isn’t needed for quantum mechanics to work - its perhaps only helpful in making us less freaked ... 18:42: Really, that entire series can be framed as an alternative interpretation of quantum mechanics. 15:15: For example Zapp Brannigan asks what percentage of quantum interactions separate into worlds versus recombining again. 13:47: ... exactly are the alternate worlds in the many worlds interpretation of quantum mechanics? ... 18:20: ... Barefoot also point out that this divide isn’t needed for quantum mechanics to work - its perhaps only helpful in making us less freaked out by the ... 18:42: Really, that entire series can be framed as an alternative interpretation of quantum mechanics. 17:10: ... probabilities must be reflected in the number of worlds for each quantum outcome - because in the many worlds interpretation, an observer is more likely ... 13:47: ... we’re covering comments from our episode on the weirdness of quantum spin, and then our episode that tried to answer the question where exactly are ... 16:27: The number of distinguishable worlds depends on the rate at which distinct decoherence happens - so far, far fewer than the number of quantum wiggles.
	2021-07-13: Where Are The Worlds In Many Worlds? 00:00: ... many worlds interpretation of quantum mechanics proposes that every time a quantum event gets decided, the ... 00:20: ... one branch of the splitting quantum multiverse a radioactive nucleus decay, in another it doesn’t; in one ... 00:44: We’ve talked before about this interpretation of quantum mechanics, and whether it’s plausibly true. 03:13: But the superposition principle seems to always hold for the waves that drive quantum mechanics. 03:20: ... the ability for the quantum wavefunction to co-exist and overlap without being affected by that ... 03:35: And by jump through a pond I mean learn some quantum mechanics. 03:39: Quantum mechanics is a theory about waves. 03:57: It represents the shifting distribution of possible results you might get if you were to try to measure a certain property of a quantum system. 04:32: The actual mechanics of quantum mechanics is all about determining the shape and evolution of the wavefunction. 05:22: ... most mainstream interpretation of quantum mechanics - the Copenhagen Interpretation - tells us that the ... 12:01: On a quantum scale, worlds - or wavefunction components - recombine all the time. 12:26: But that’s for another time - and I’ll do my best to bring it to every future branch of our splitting quantum space time. 00:00: ... worlds interpretation of quantum mechanics proposes that every time a quantum event gets decided, the universe splits so that every possible outcome really ... 00:20: ... a radioactive nucleus decay, in another it doesn’t; in one “world” a quantum event in your brain produces a neural cascade that leads you to choosing ... 00:00: ... many worlds interpretation of quantum mechanics proposes that every time a quantum event gets decided, the universe ... 00:44: We’ve talked before about this interpretation of quantum mechanics, and whether it’s plausibly true. 03:13: But the superposition principle seems to always hold for the waves that drive quantum mechanics. 03:35: And by jump through a pond I mean learn some quantum mechanics. 03:39: Quantum mechanics is a theory about waves. 04:32: The actual mechanics of quantum mechanics is all about determining the shape and evolution of the wavefunction. 05:22: ... most mainstream interpretation of quantum mechanics - the Copenhagen Interpretation - tells us that the wavefunction ... 00:00: ... many worlds interpretation of quantum mechanics proposes that every time a quantum event gets decided, the universe splits so ... 00:20: ... one branch of the splitting quantum multiverse a radioactive nucleus decay, in another it doesn’t; in one “world” a ... 12:01: On a quantum scale, worlds - or wavefunction components - recombine all the time. 12:26: But that’s for another time - and I’ll do my best to bring it to every future branch of our splitting quantum space time. 03:20: ... the ability for the quantum wavefunction to co-exist and overlap without being affected by that overlap is how ...
	2021-07-07: Electrons DO NOT Spin 00:00: ... Quantum mechanics has a lot of weird stuff  - but there’s one thing that ... 01:26: ... of an electron is far more fundamental than simple rotation - it’s a quantum property of particles, like mass or the various charges. But it doesn’t ... 04:40: ... they act like they have angular momentum. And this is how we think about quantum spin now. It’s  an intrinsic angular momentum that plays into the ... 07:30: ... than that. To understand why we need to see how spin is described in quantum mechanics. It  was again Pauli who had the first big success here. ... 10:33: ... us the law of the  conservation of momentum. For related reasons in quantum mechanics position and  momentum are conjugate ... 11:26: Some physicists think that spin is  more physical than this. Han Ohanian,   author of one of the most used quantum textbooks. 11:44: ... the quantum field surrounding  the Dirac spinor aka the electron,   ... 12:02: ... say that particles described by spinors have spin quantum numbers that are half-integers - ½, 3/2, 5/2, etc. The electron itself ... 12:44: ... with each other. Bosons, for example, are able to pile up in the same quantum states, while fermions can never occupy the same ... 13:49: ... time we talked about the connection between  quantum entanglement and entropy - this was a heady topic to say the least, but ... 15:09: ... it was at its minimum at the Big Bang, does that  mean there was no quantum entanglement at the Big Bang? To answer this we’d need to know why ... 15:31: ... beginning  of time, because that moment lost in our ignorance about quantum gravity and inflation and whatever  other crazy theory we haven’t ... 13:49: ... time we talked about the connection between  quantum entanglement and entropy - this was a heady topic to say the least, but you guys had ... 15:09: ... it was at its minimum at the Big Bang, does that  mean there was no quantum entanglement at the Big Bang? To answer this we’d need to know why entropy is so low ... 11:44: ... the quantum field surrounding  the Dirac spinor aka the electron,   imply ... 15:31: ... beginning  of time, because that moment lost in our ignorance about quantum gravity and inflation and whatever  other crazy theory we haven’t figure ... 04:40: ... electrons a magnetic field. An electron’s  spin is an entirely quantum mechanical property, and has all the weirdness you’d expect from  the weirdest ... 00:00: ... Quantum mechanics has a lot of weird stuff  - but there’s one thing that everyone ... 07:30: ... than that. To understand why we need to see how spin is described in quantum mechanics. It  was again Pauli who had the first big success here. By the mid ... 10:33: ... us the law of the  conservation of momentum. For related reasons in quantum mechanics position and  momentum are conjugate ... 07:30: ... than that. To understand why we need to see how spin is described in quantum mechanics. It  was again Pauli who had the first big success here. By the mid 1920s ... 10:33: ... us the law of the  conservation of momentum. For related reasons in quantum mechanics position and  momentum are conjugate ... 12:02: ... say that particles described by spinors have spin quantum numbers that are half-integers - ½, 3/2, 5/2, etc. The electron itself has spin ... 07:30: ... been given - the Schrodinger equation. This equation  describes how quantum objects behave as evolving distributions of probability - as ... 01:26: ... of an electron is far more fundamental than simple rotation - it’s a quantum property of particles, like mass or the various charges. But it doesn’t just ... 00:00: ... thing that everyone agrees that no one understands. I’m talking about quantum spin. Let’s find out how chasing this elusive little behavior of the electron ... 01:26: ... it doesn’t just cause magnets to move in funny ways - it turns out that quantum spin is a manifestation of a  much deeper property of particles - a ... 04:40: ... they act like they have angular momentum. And this is how we think about quantum spin now. It’s  an intrinsic angular momentum that plays into the ... 12:44: ... with each other. Bosons, for example, are able to pile up in the same quantum states, while fermions can never occupy the same ... 11:26: Some physicists think that spin is  more physical than this. Han Ohanian,   author of one of the most used quantum textbooks. 07:02: ... the direction of the underlying magnetic  momentum is fundamentally quantum.   The direction of this "spin" property is quantized - it can only take on ...
	2021-06-23: How Quantum Entanglement Creates Entropy 00:27: ... black hole information paradox—a solution that may one day unite quantum physics with ... 02:13: ... is often the case, getting more fundamental means getting quantum - and there is indeed a   type of entropy that applies to ... 05:19: ... quantum systems, and because everything else is   made of quantum systems, it may be the most fundamental definition of entropy, Even ... 05:55: ... entropy is at least incredibly powerful. It’s at the heart of quantum information theory,   enabling us to calculate how much ... 06:38: ... von Neumann entropy is about, let’s think  about information in quantum mechanics.   Quantum systems are described by what we ... 06:56: ... describes which side is up - heads or tails.  So you flip the quantum coin it enters what   we call a superposition of states ... 07:14: ... the way, the quantum coin is just like  the both alive-and-dead Schrodinger’s ... 07:44: ... a counter-intuitive thing about  superposition: after you flip the quantum coin,   you actually DO know its current unrevealed  ... 08:59: ... case superposition wasn’t weird enough, let’s bring in quantum entanglement. That means we need   a second quantum coin. ... 09:22: ... you flip your pair of entangled  quantum coins. There are   two ways this can turn out - either the ... 10:23: ... viewed WITH its entangled partner, the coin exhibits quantum weirdness like superposition.   That could be revealed in ... 11:00: ... similarity between the entangled but  isolated quantum coin is no coincidence. Its   entanglement is the first step ... 11:50: ... the entanglement is between the coin’s countless   constituent quantum parts and every particle they’ve ever interacted with. That network ... 12:35: ... about the detailed quantum states of all particles becomes increasingly ... 16:39: ... with good  answers - Daemonxblaze points out   that quantum teleportation, aka quantum tunneling,   is basically moving ... 02:13: ... is often the case, getting more fundamental means getting quantum - and there is indeed a   type of entropy that applies to ... 06:56: ... describes which side is up - heads or tails.  So you flip the quantum coin it enters what   we call a superposition of states -  it ... 07:14: ... the way, the quantum coin is just like  the both alive-and-dead Schrodinger’s ... 08:59: ... in quantum entanglement. That means we need   a second quantum coin. It’s  spookily connected to the first,   in that when ... 11:00: ... similarity between the entangled but  isolated quantum coin is no coincidence. Its   entanglement is the first step in the ... 08:59: ... in quantum entanglement. That means we need   a second quantum coin. It’s  spookily connected to the first,   in that when both coins are ... 10:23: ... But treated   individually, each separate entangled quantum coin behaves kind of like a regular classical coin -   for example it ... 07:44: ... a counter-intuitive thing about  superposition: after you flip the quantum coin,   you actually DO know its current unrevealed  state. That’s because ... 09:22: ... you flip your pair of entangled  quantum coins. There are   two ways this can turn out - either the first ... 12:35: ... diffusion of entanglement pointer states   in the language of quantum darwinism. Over time, systems move towards a state of maximum   ... 08:59: ... case superposition wasn’t weird enough, let’s bring in quantum entanglement. That means we need   a second quantum coin. It’s  ... 16:39: ... The answer is yes - and various people  have tried. Loop quantum gravity is a   good example - but for that to work the  ... 06:38: ... von Neumann entropy is about, let’s think  about information in quantum mechanics.   Quantum systems are described by what we call the wavefunction - ... 11:00: ... entanglement,   that becomes more difficult - but as a  quantum object interacts with the countless   particles of a macroscopic ... 05:55: ... driven by entanglement - this mysterious connection between quantum particles that Einstein called   “spooky action at a distance”. As a bit ... 11:50: ... the entanglement is between the coin’s countless   constituent quantum parts and every particle they’ve ever interacted with. That network ... 00:27: ... black hole information paradox—a solution that may one day unite quantum physics with ... 11:00: ... the ordinary macroscopic world emerges   from its very weird quantum pieces - and for a deeper dive into decoherence we do have you ... 07:44: ... about the unrevealed state.   Rather it changes the quantum state in a  random way - now 100% heads or 100% tails,   but ... 12:35: ... about the detailed quantum states of all particles becomes increasingly inaccessible,   ... 05:19: ... quantum systems, and because everything else is   made of quantum systems, it may be the most fundamental definition of entropy, Even ... 06:38: ... let’s think  about information in quantum mechanics.   Quantum systems are described by what we call the wavefunction - that’s the ... 07:14: ... these are just illustrative examples,   there are many real quantum systems that can exhibit these superposition states - like a   ... 02:13: ... - and there is indeed a   type of entropy that applies to quantum systems like our air molecule - it’s von Neumann entropy,   and ... 16:39: ... with good  answers - Daemonxblaze points out   that quantum teleportation, aka quantum tunneling,   is basically moving ... 10:23: ... viewed WITH its entangled partner, the coin exhibits quantum weirdness like superposition.   That could be revealed in experiments ... 11:00: ... the quantum and classical world.   Our capacity to observe quantum  effects like superposition   depends on being able to access ... 06:56: ... an example, imagine you have a quantum coin. It has a wavefunction that just   describes which side is up - ... 05:55: ... information theory,   enabling us to calculate how much quantum information is contained in a system,   and it can also be used to ... 13:09: ... of thermodynamics AND the emergence of the classical world from the quantum.   And, as an extra trick, it also defines the arrow of time which ... 05:19: ... brand of entropy. Von   Neumann entropy. Its the entropy of quantum systems, and because everything else is   made of quantum systems, it ...
	2021-06-16: Can Space Be Infinitely Divided? 00:00: ... coordination and the ability   to localize my palms to the quantum level. 15 halvings gets them to within a cell’s width.   ... 01:16: ... the final year of the 19th century,  Max Planck ushered in the quantum age by   thinking about hot pokers. He found the  ... 02:38: ... the scale at which space itself   is thought to “become quantum”. I say  “thought” because we’ve never been able   to ... 10:55: ... define distances. We think that space AND time - spacetime - “go quantum” at that   scale - but we just don’t know in what way. ... 11:26: ... length, at least for any   intuitive conception of space. Quantum uncertainty thwarts our attempt to understand the ... 01:16: ... the final year of the 19th century,  Max Planck ushered in the quantum age by   thinking about hot pokers. He found the  long-sought ... 10:55: ... scale - but we just don’t know in what way. We need a theory of quantum gravity to answer this.   We’ll come back to what the contending ... 00:00: ... coordination and the ability   to localize my palms to the quantum level. 15 halvings gets them to within a cell’s width.   33 to ... 01:16: ... the subatomic world. We now see it everywhere   in quantum mechanics - it’s a fundamental constant of nature that defines the scale of ... 11:26: ... length, at least for any   intuitive conception of space. Quantum uncertainty thwarts our attempt to understand the universe   by simply splitting ... 05:08: ... But it turns out that the Planck constant defines a new source of quantum   uncertainty that you can’t ever physics away. And we hit that ...
	2021-05-25: What If (Tiny) Black Holes Are Everywhere? 00:50: ... in 1974, a young genius named Stephen Hawking showed that if you bring quantum mechanics into the equation, quite literally, then the black hole is ... 01:07: In a way quantum mechanics saves us from the eternal black hole … except perhaps that it doesn’t. 01:16: ... the evaporation of the black hole all the way to the very last instant - quantum mechanics may well play a second trick and save that final speck of the ... 01:51: It came from thinking about how black holes interact with the quantum fields from which all elementary particles arise. 01:57: Now to do this properly, you really need a theory of quantum gravity, which we don’t even have now and certainly didn’t in 1974. 02:06: ... if an event horizon forms in a vacuum, then the vacuum states of the quantum fields have to be ... 04:02: Researchers have come up with different hacks for combining general relativity and quantum mechanics and they reached the same conclusion. 04:19: One big assumption is that the space near the event horizon isn’t TOO strongly curved compared to the smallest quantum scale. 04:37: ... falls apart when the black hole has shrunk down to the tiniest quantum ... 04:49: At that point you need a proper theory of quantum gravity to describe the process. 05:31: So a large black hole is like our entire poker - there are many ways that the quantum fields can fluctuate around it. 06:48: ... is the size-scale where general relativity and quantum mechanics come into hopeless conflict, and is sometimes thought of as ... 09:28: So you completely evaporate a black hole and then all the quantum information that went into it is deleted from the universe. 09:36: That breaks one of the most sacred rules of quantum mechanics - the conservation of quantum information. 14:24: ... to create squeezed states of light, they’re used in all sorts of other quantum optics applications like the various quantum eraser ... 01:51: It came from thinking about how black holes interact with the quantum fields from which all elementary particles arise. 02:06: ... if an event horizon forms in a vacuum, then the vacuum states of the quantum fields have to be ... 05:31: So a large black hole is like our entire poker - there are many ways that the quantum fields can fluctuate around it. 01:57: Now to do this properly, you really need a theory of quantum gravity, which we don’t even have now and certainly didn’t in 1974. 04:49: At that point you need a proper theory of quantum gravity to describe the process. 00:50: ... in 1974, a young genius named Stephen Hawking showed that if you bring quantum mechanics into the equation, quite literally, then the black hole is neither black ... 01:07: In a way quantum mechanics saves us from the eternal black hole … except perhaps that it doesn’t. 01:16: ... the evaporation of the black hole all the way to the very last instant - quantum mechanics may well play a second trick and save that final speck of the black hole ... 04:02: Researchers have come up with different hacks for combining general relativity and quantum mechanics and they reached the same conclusion. 06:48: ... is the size-scale where general relativity and quantum mechanics come into hopeless conflict, and is sometimes thought of as the smallest ... 09:36: That breaks one of the most sacred rules of quantum mechanics - the conservation of quantum information. 01:07: In a way quantum mechanics saves us from the eternal black hole … except perhaps that it doesn’t. 14:24: ... to create squeezed states of light, they’re used in all sorts of other quantum optics applications like the various quantum eraser ... 04:19: One big assumption is that the space near the event horizon isn’t TOO strongly curved compared to the smallest quantum scale. 04:37: ... falls apart when the black hole has shrunk down to the tiniest quantum scales. ...
	2021-05-19: Breaking The Heisenberg Uncertainty Principle 00:00: Quantum mechanics forbids us from measuringthe universe beyond a certain level of precision. 00:25: ... the recent g-2 experiment for measuring the muon’s interaction with quantum fields is good to to one part in a billion And also pretty recently we ... 00:47: ... become so precise that we’re starting to run up against the absolute quantum limit - the limit defined by the Heisenberg Uncertainty ... 01:41: ... quantum mechanics, we call these pairs of properties complementary variables, ... 01:58: Werner Heisenberg discovered the uncertainty principle when he was inventing his version of quantum mechanics back in the 1920s. 03:02: Heisenberg took his new idea to Niels Bohr - his mentor and one of the co-founders of quantum mechanics. 03:18: ... when trying to reconcile the perplexing apparent contradictions in quantum ... 03:31: ... example, how can a quantum object sometimes be a “wave” and some times be a “particle?” In a sense ... 03:45: A quantum object can project its nature up to our classical world in one way or another, but not both. 04:10: The Heisenberg uncertainty principle prevents us from being able to know everything about a quantum state all at once. 04:40: That’s not as easy as it sounds - normal quantum states tend to share the uncertainty between complementary partners fairly evenly. 04:47: ... theoretical and engineering tricks that enable us to manipulate quantum states to push the limits of the uncertainty ... 06:32: Quantum fluctuations result in a low level of noise - a flickering signal where you should see darkness. 06:44: ... quantum fluctuations in the phase of the laser beams are larger than the change ... 07:15: That would enable us to line up those waves more perfectly to reduce quantum fluctuations. 07:55: By playing quantum tricks on the light, we can squeeze the uncertainty in one direction at the cost of greater uncertainty in the other. 08:30: This phase squeezing is achieved by using quantum entanglement. 08:54: ... they’re recombined, they still have quantum fluctuations in the phase, but the fluctuations between the two beams ... 09:56: The use of squeezed light is just one example of how quantum mechanics can be used to increase measurement precision. 08:30: This phase squeezing is achieved by using quantum entanglement. 00:25: ... the recent g-2 experiment for measuring the muon’s interaction with quantum fields is good to to one part in a billion And also pretty recently we have the ... 06:32: Quantum fluctuations result in a low level of noise - a flickering signal where you should see darkness. 06:44: ... quantum fluctuations in the phase of the laser beams are larger than the change in the arm ... 07:15: That would enable us to line up those waves more perfectly to reduce quantum fluctuations. 08:54: ... they’re recombined, they still have quantum fluctuations in the phase, but the fluctuations between the two beams are now ... 06:32: Quantum fluctuations result in a low level of noise - a flickering signal where you should see darkness. 00:47: ... become so precise that we’re starting to run up against the absolute quantum limit - the limit defined by the Heisenberg Uncertainty ... 00:00: Quantum mechanics forbids us from measuringthe universe beyond a certain level of precision. 01:41: ... quantum mechanics, we call these pairs of properties complementary variables, and the ... 01:58: Werner Heisenberg discovered the uncertainty principle when he was inventing his version of quantum mechanics back in the 1920s. 03:02: Heisenberg took his new idea to Niels Bohr - his mentor and one of the co-founders of quantum mechanics. 03:18: ... when trying to reconcile the perplexing apparent contradictions in quantum mechanics. ... 09:56: The use of squeezed light is just one example of how quantum mechanics can be used to increase measurement precision. 00:00: Quantum mechanics forbids us from measuringthe universe beyond a certain level of precision. 03:31: ... example, how can a quantum object sometimes be a “wave” and some times be a “particle?” In a sense it is ... 03:45: A quantum object can project its nature up to our classical world in one way or another, but not both. 04:10: The Heisenberg uncertainty principle prevents us from being able to know everything about a quantum state all at once. 04:40: That’s not as easy as it sounds - normal quantum states tend to share the uncertainty between complementary partners fairly evenly. 04:47: ... theoretical and engineering tricks that enable us to manipulate quantum states to push the limits of the uncertainty ... 04:40: That’s not as easy as it sounds - normal quantum states tend to share the uncertainty between complementary partners fairly evenly. 07:55: By playing quantum tricks on the light, we can squeeze the uncertainty in one direction at the cost of greater uncertainty in the other.
	2021-05-11: How To Know If It's Aliens 14:48: ... Randlepp asks whether understanding quantum gravity might be helpful for developing warp drives. Good insight. All ... 16:32: ... when people talk about wimps they’re referring to some undiscovered quantum particle, but actually a micro black hole would have all the properties ... 14:48: ... Randlepp asks whether understanding quantum gravity might be helpful for developing warp drives. Good insight. All this warp ... 16:32: ... when people talk about wimps they’re referring to some undiscovered quantum particle, but actually a micro black hole would have all the properties to qualify ...
	2021-04-21: The NEW Warp Drive Possibilities 04:48: We can summarize this by saying that it requires a negative energy density, which should be impossible except perhaps on the tiniest, quantum scales. 11:07: Both of these papers are peer reviewed and published in the reputable journal Classical and Quantum Gravity. 13:55: Okay, onto today’s comments we’re covering two episodes - there’s the quantum Zeno effect and the recent result from Fermilab’s muon g-2 experiment. 16:15: OK, onto the quantum Zeno Effect, and the idea that you can freeze a quantum system by observing it. 16:40: Actually, in quantum mechanics, velocity isn’t just change in position with time. 16:54: For Flensdude the quantum Zeno effect reminds them of a poem composed by the Norse god Odin. 17:14: So we can conclude that Odin knew quantum mechanics. 17:17: I mean, stopping an arrow with the power of observation is a spell they teach you in undergrad quantum. 17:47: So maybe Odin learned his quantum mechanics watching space time like the rest of us. 17:54: ... Turner asks the real question: If the Quantum Zeno Effect plays a role in birds' ability to see magnetic fields, then ... 18:08: ... tiny but non-zero number of worlds where the freezing of cryptochrome quantum states randomly failed in all avian ... 11:07: Both of these papers are peer reviewed and published in the reputable journal Classical and Quantum Gravity. 16:40: Actually, in quantum mechanics, velocity isn’t just change in position with time. 17:14: So we can conclude that Odin knew quantum mechanics. 17:47: So maybe Odin learned his quantum mechanics watching space time like the rest of us. 16:40: Actually, in quantum mechanics, velocity isn’t just change in position with time. 17:47: So maybe Odin learned his quantum mechanics watching space time like the rest of us. 04:48: We can summarize this by saying that it requires a negative energy density, which should be impossible except perhaps on the tiniest, quantum scales. 18:08: ... tiny but non-zero number of worlds where the freezing of cryptochrome quantum states randomly failed in all avian ... 13:55: Okay, onto today’s comments we’re covering two episodes - there’s the quantum Zeno effect and the recent result from Fermilab’s muon g-2 experiment. 16:15: OK, onto the quantum Zeno Effect, and the idea that you can freeze a quantum system by observing it. 16:54: For Flensdude the quantum Zeno effect reminds them of a poem composed by the Norse god Odin. 17:54: ... Turner asks the real question: If the Quantum Zeno Effect plays a role in birds' ability to see magnetic fields, then ... 13:55: Okay, onto today’s comments we’re covering two episodes - there’s the quantum Zeno effect and the recent result from Fermilab’s muon g-2 experiment. 16:15: OK, onto the quantum Zeno Effect, and the idea that you can freeze a quantum system by observing it. 16:54: For Flensdude the quantum Zeno effect reminds them of a poem composed by the Norse god Odin. 17:54: ... Turner asks the real question: If the Quantum Zeno Effect plays a role in birds' ability to see magnetic fields, then according to ...
	2021-04-07: Why the Muon g-2 Results Are So Exciting! 01:56: ... particles with electric charge interact via the electromagnetic force, quantum ... 03:01: Let's start by talking about quantum spin. 03:09: Every particle with electric charge also has quantum spin. 03:15: ... particles with quantum spin do generate a magnetic field, same as if you send an electric ... 04:23: Quantum electrodynamics, tells us exactly what this difference is. 05:14: For a deeper dive in Feynman diagrams, virtual particles, and quantum electrodynamics, we have you covered, episode list in the description. 07:23: They have the same exact charge, interact with the same forces, and have the same quantum spin. 07:29: They have a different g-factor because there are slowly different ways that the muon can interact with the quantum fields. 07:43: The quantum vacuum is seething with an incredible variety of possible virtual particles. 11:56: And that dance, may just have revealed to us the next step on our path to a more complete understanding of our quantum space time. 01:56: ... particles with electric charge interact via the electromagnetic force, quantum electrodynamics. ... 04:23: Quantum electrodynamics, tells us exactly what this difference is. 05:14: For a deeper dive in Feynman diagrams, virtual particles, and quantum electrodynamics, we have you covered, episode list in the description. 04:23: Quantum electrodynamics, tells us exactly what this difference is. 07:29: They have a different g-factor because there are slowly different ways that the muon can interact with the quantum fields. 11:56: And that dance, may just have revealed to us the next step on our path to a more complete understanding of our quantum space time. 03:01: Let's start by talking about quantum spin. 03:09: Every particle with electric charge also has quantum spin. 03:15: ... particles with quantum spin do generate a magnetic field, same as if you send an electric charge ... 07:23: They have the same exact charge, interact with the same forces, and have the same quantum spin. 07:43: The quantum vacuum is seething with an incredible variety of possible virtual particles.
	2021-03-23: Zeno's Paradox & The Quantum Zeno Effect 00:04: This has now been proven true by quantum mechanics. 01:07: That’s what a mathematician might tell you - but quantum mechanics also has a thing or two to say about extremely tiny distances and time intervals. 01:15: ... fact, if we’re talking about a quantum arrow, there may be a way to freeze its motion simply by looking at it, ... 01:27: ... quantum Zeno effect predicts that certain quantum events - like the electrons ... 01:43: But first, let’s see if the Quantum Zeno Effect can save us from being shot by a quantum arrow. 01:50: ... we’ll give our arrow a few weird behaviours befitting a good quantum object: we have quantization - certain properties of our arrow can only ... 02:04: In this case let’s say our quantum arrow’s position is quantized - it can exist only at the start and end of its path, but not in between. 02:19: One way to do that is by executing a quantum jump, which we discussed in our recent episode. 02:24: OK, the next quantum property we need is superposition. 02:28: Just like Schrodinger’s cat, our quantum arrow can exist in multiple states at once. 02:52: In the language of the Copenhagen interpretation of quantum mechanics, we say that the “wavefunction collapses” on observation. 03:18: ... superposition thing actually gives our quantum arrow a way to travel its path smoothly and gradually, but still without ... 03:32: Here’s the scenario: someone shoots a quantum arrow at you. 04:10: Two ways this can play out: the arrow leaves the quantum bow with a quantum twang. 04:15: ... it allows the arrow’s wavefunction to evolve smoothly into the state of quantum ... 04:41: ... observing it and keep resetting it back again through the magic of the Quantum Zeno ... 04:54: So the message is clear - if anyone ever tries to shoot you with a quantum arrow, don’t blink. 05:01: Of course arrows don’t really behave this way, but it seems that this is exactly what real quantum systems should do. 05:23: ... for radioactive decay, even chemical reactions The basic idea of the quantum Zeno effect was first proposed by Alan Turing, but it got a full ... 05:47: These were some of the same people who first demonstrated quantum jumps, and using a similar scheme that we described in that episode. 06:09: Just like our quantum arrow, sometimes an electron is in state 1, sometimes state 2, but in between it’s a smoothly-varying superposition of both. 07:02: ... like a measurement - and remember, measurement should be able to freeze quantum arrows and presumably also electron transitions via the Quantum Zeno ... 07:41: Long story short: it appears you can freeze a quantum state by measuring it continuously. 07:47: ... studies have claimed successful observation of the quantum Zeno effect, including various studies of atomic energy levels, as well ... 08:02: ... even been proposed that the quantum Zeno effect plays a role in the photochemical reactions that give birds ... 08:13: Quantum Zeno effect verified? 08:29: ... argued that it’s not the abstract act of measurement that causes the quantum Zeno effect, but rather it’s a physical consequence of interacting with ... 08:43: ... objection gets to the very foundations of quantum mechanics: what exactly do we mean by a “measurement” and what do we ... 09:21: ... to achieve a true quantum Zeno-like freezing you’d need to hit the atom with many, many photons - ... 09:30: ... to have proved that it’s perturbation, not measurement, that causes the quantum Zeno effect by demonstrating that with the right type of “jiggling” a ... 10:09: We would say that the wavefunction for different electron states or quantum arrow positions are in phase with each other, or “coherent”. 10:32: In fact, as argued by Ballentine, you can force a quantum system back to its starting state without true decoherence. 10:38: ... to get a full quantum Zeno effect - a perfect freezing of your electron or quantum arrow - you ... 11:04: Obviously we’ve talked about decoherence and many worlds before, but let’s talk about what the quantum Zeno effect looks like in this picture. 11:32: For example, by forcing the electron or quantum arrow out of its superposition. 12:01: Like I said, if someone shoots you with a quantum arrow, don’t blink. 12:05: The quantum Zeno effect appears to be very real - but its interpretation is still hotly debated. 12:17: ... quantum zeno experiments are difficult, and perhaps future brilliant tests will ... 12:27: So there you have why a watched quantum pot never boils. And it's because you did watch space time. 13:04: ... the course you’ll explore everything from time in quantum mechanics to black hole entropy and learn what cutting-edge science has ... 01:15: ... fact, if we’re talking about a quantum arrow, there may be a way to freeze its motion simply by looking at it, through ... 01:43: But first, let’s see if the Quantum Zeno Effect can save us from being shot by a quantum arrow. 02:28: Just like Schrodinger’s cat, our quantum arrow can exist in multiple states at once. 03:18: ... superposition thing actually gives our quantum arrow a way to travel its path smoothly and gradually, but still without ... 03:32: Here’s the scenario: someone shoots a quantum arrow at you. 04:54: So the message is clear - if anyone ever tries to shoot you with a quantum arrow, don’t blink. 06:09: Just like our quantum arrow, sometimes an electron is in state 1, sometimes state 2, but in between it’s a smoothly-varying superposition of both. 10:09: We would say that the wavefunction for different electron states or quantum arrow positions are in phase with each other, or “coherent”. 10:38: ... get a full quantum Zeno effect - a perfect freezing of your electron or quantum arrow - you need to perfectly measure it, and that means decoherence - or the ... 11:32: For example, by forcing the electron or quantum arrow out of its superposition. 12:01: Like I said, if someone shoots you with a quantum arrow, don’t blink. 10:38: ... get a full quantum Zeno effect - a perfect freezing of your electron or quantum arrow - you need to perfectly measure it, and that means decoherence - or the ... 04:54: So the message is clear - if anyone ever tries to shoot you with a quantum arrow, don’t blink. 12:01: Like I said, if someone shoots you with a quantum arrow, don’t blink. 10:09: We would say that the wavefunction for different electron states or quantum arrow positions are in phase with each other, or “coherent”. 02:04: In this case let’s say our quantum arrow’s position is quantized - it can exist only at the start and end of its path, but not in between. 07:02: ... like a measurement - and remember, measurement should be able to freeze quantum arrows and presumably also electron transitions via the Quantum Zeno ... 02:04: In this case let’s say our quantum arrow’s position is quantized - it can exist only at the start and end of its path, but not in between. 04:10: Two ways this can play out: the arrow leaves the quantum bow with a quantum twang. 01:27: ... quantum Zeno effect predicts that certain quantum events - like the electrons moving between atomic energy levels, or the decay ... 02:19: One way to do that is by executing a quantum jump, which we discussed in our recent episode. 05:47: These were some of the same people who first demonstrated quantum jumps, and using a similar scheme that we described in that episode. 00:04: This has now been proven true by quantum mechanics. 01:07: That’s what a mathematician might tell you - but quantum mechanics also has a thing or two to say about extremely tiny distances and time intervals. 02:52: In the language of the Copenhagen interpretation of quantum mechanics, we say that the “wavefunction collapses” on observation. 08:43: ... objection gets to the very foundations of quantum mechanics: what exactly do we mean by a “measurement” and what do we mean by ... 12:17: ... will give us clues to unravel the deepest mysteries at the heart of quantum mechanics. ... 13:04: ... the course you’ll explore everything from time in quantum mechanics to black hole entropy and learn what cutting-edge science has to say ... 01:50: ... we’ll give our arrow a few weird behaviours befitting a good quantum object: we have quantization - certain properties of our arrow can only take on ... 04:15: ... it allows the arrow’s wavefunction to evolve smoothly into the state of quantum ouch. ... 12:27: So there you have why a watched quantum pot never boils. And it's because you did watch space time. 02:24: OK, the next quantum property we need is superposition. 07:41: Long story short: it appears you can freeze a quantum state by measuring it continuously. 05:01: Of course arrows don’t really behave this way, but it seems that this is exactly what real quantum systems should do. 09:30: ... Zeno effect by demonstrating that with the right type of “jiggling” a quantum transition could be forced to speed up rather than to freeze - in what’s called the ... 07:47: ... various studies of atomic energy levels, as well as the freezing of quantum tunneling - the same phenomenon that allows particles to “teleport” out of nuclei ... 04:10: Two ways this can play out: the arrow leaves the quantum bow with a quantum twang. 01:15: ... to freeze its motion simply by looking at it, through the aptly named quantum Zeno ... 01:27: ... quantum Zeno effect predicts that certain quantum events - like the electrons moving ... 01:43: But first, let’s see if the Quantum Zeno Effect can save us from being shot by a quantum arrow. 04:41: ... observing it and keep resetting it back again through the magic of the Quantum Zeno ... 05:23: ... for radioactive decay, even chemical reactions The basic idea of the quantum Zeno effect was first proposed by Alan Turing, but it got a full theoretical ... 07:02: ... freeze quantum arrows and presumably also electron transitions via the Quantum Zeno ... 07:47: ... studies have claimed successful observation of the quantum Zeno effect, including various studies of atomic energy levels, as well as ... 08:02: ... even been proposed that the quantum Zeno effect plays a role in the photochemical reactions that give birds their ... 08:13: Quantum Zeno effect verified? 08:29: ... argued that it’s not the abstract act of measurement that causes the quantum Zeno effect, but rather it’s a physical consequence of interacting with the ... 09:30: ... to have proved that it’s perturbation, not measurement, that causes the quantum Zeno effect by demonstrating that with the right type of “jiggling” a quantum ... 10:38: ... to get a full quantum Zeno effect - a perfect freezing of your electron or quantum arrow - you need ... 11:04: Obviously we’ve talked about decoherence and many worlds before, but let’s talk about what the quantum Zeno effect looks like in this picture. 12:05: The quantum Zeno effect appears to be very real - but its interpretation is still hotly debated. 12:17: ... quantum zeno experiments are difficult, and perhaps future brilliant tests will give ... 01:15: ... to freeze its motion simply by looking at it, through the aptly named quantum Zeno effect. ... 01:27: ... quantum Zeno effect predicts that certain quantum events - like the electrons moving between ... 01:43: But first, let’s see if the Quantum Zeno Effect can save us from being shot by a quantum arrow. 04:41: ... observing it and keep resetting it back again through the magic of the Quantum Zeno Effect. ... 05:23: ... for radioactive decay, even chemical reactions The basic idea of the quantum Zeno effect was first proposed by Alan Turing, but it got a full theoretical ... 07:02: ... freeze quantum arrows and presumably also electron transitions via the Quantum Zeno Effect. ... 07:47: ... studies have claimed successful observation of the quantum Zeno effect, including various studies of atomic energy levels, as well as the ... 08:02: ... even been proposed that the quantum Zeno effect plays a role in the photochemical reactions that give birds their ... 08:13: Quantum Zeno effect verified? 08:29: ... argued that it’s not the abstract act of measurement that causes the quantum Zeno effect, but rather it’s a physical consequence of interacting with the ... 09:30: ... to have proved that it’s perturbation, not measurement, that causes the quantum Zeno effect by demonstrating that with the right type of “jiggling” a quantum ... 10:38: ... to get a full quantum Zeno effect - a perfect freezing of your electron or quantum arrow - you need to ... 11:04: Obviously we’ve talked about decoherence and many worlds before, but let’s talk about what the quantum Zeno effect looks like in this picture. 12:05: The quantum Zeno effect appears to be very real - but its interpretation is still hotly debated. 12:17: ... quantum zeno experiments are difficult, and perhaps future brilliant tests will give us clues to ... 09:21: ... to achieve a true quantum Zeno-like freezing you’d need to hit the atom with many, many photons - and that ...
	2021-03-16: The NEW Crisis in Cosmology 16:28: ... principle feels like Feynman's  path integral formulation of quantum mechanics.   For those who don't know, the path ...
	2021-03-09: How Does Gravity Affect Light? 11:59: Light isn’t really a simple plane wave - it’s a much weirder quantum wave-particle thing.
	2021-02-24: Does Time Cause Gravity? 07:11: ... truly occupies only a single, perfectly defined position in space - quantum uncertainty means that everything is always at multiple places at once, ... 07:25: But actually general relativity doesn’t need quantum mechanics to explain gravity. 10:04: ... asks whether gravitational waves can be used to test ideas in quantum ... 10:56: ... inflation it’s believed that quantum gravitational effects would have been very important, so if we can get ... 10:04: ... asks whether gravitational waves can be used to test ideas in quantum gravity. ... 07:25: But actually general relativity doesn’t need quantum mechanics to explain gravity. 07:11: ... truly occupies only a single, perfectly defined position in space - quantum uncertainty means that everything is always at multiple places at once, and so ...
	2021-02-17: Gravitational Wave Background Discovered? 00:00: ... the edge of absolute collapse into black holes supported only by weird quantum forces neutron stars tend to channel jets of high energy particles due ...
	2021-02-10: How Does Gravity Warp the Flow of Time? 11:03: ... the photon - or whatever light-speed quantum components make up matter - actually do have to travel further - between ...
	2021-01-26: Is Dark Matter Made of Particles? 02:27: A more technical way to think about this stuff is in terms of quantum fields - where each particle and force is a vibration in its own field. 02:51: But gravity is a little different to the other forces - it’s not part of the Standard Model, and we don’t even know if it has a quantum field. 12:03: ... - interacting by dark forces, all of them oscillations in their own dark quantum fields - perhaps with their own complexity and ... 02:51: But gravity is a little different to the other forces - it’s not part of the Standard Model, and we don’t even know if it has a quantum field. 02:27: A more technical way to think about this stuff is in terms of quantum fields - where each particle and force is a vibration in its own field. 12:03: ... - interacting by dark forces, all of them oscillations in their own dark quantum fields - perhaps with their own complexity and ... 02:27: A more technical way to think about this stuff is in terms of quantum fields - where each particle and force is a vibration in its own field. 12:03: ... - interacting by dark forces, all of them oscillations in their own dark quantum fields - perhaps with their own complexity and ...
	2021-01-19: Can We Break the Universe? 13:01: ... - the protein not the browser bitcoin wallet - may give birds quantum ... 13:13: And also our episode on what happens during quantum jumps. 13:20: Regarding the experiment which showed that quantum jumps could be predicted, tracked, and even reversed in an artificial atom. 13:38: So the answer I think is that we don't yet know - but it's important to point out that the system used in the experiment IS a genuine quantum system. 13:48: The energy levels are represented by a very small number of photons in a cavity - 0 to 5 - so quite quantum. 13:56: Transitions involve quantum tunneling in a superconducting circuit - so entirely quantum. 14:15: ... possible question: Could it be that asking which interpretation of quantum mechanics is "true" is like asking if light is made up of particles or ... 15:10: And on to quantum magneto reception in birds. 13:13: And also our episode on what happens during quantum jumps. 13:20: Regarding the experiment which showed that quantum jumps could be predicted, tracked, and even reversed in an artificial atom. 15:10: And on to quantum magneto reception in birds. 13:01: ... - the protein not the browser bitcoin wallet - may give birds quantum magnetovision. ... 14:15: ... possible question: Could it be that asking which interpretation of quantum mechanics is "true" is like asking if light is made up of particles or if light is ... 13:56: Transitions involve quantum tunneling in a superconducting circuit - so entirely quantum.
	2021-01-12: What Happens During a Quantum Jump? 00:00: Since the very beginning of quantum mechanics, a debate has raged about how to interpret its bizarre predictions. 00:06: ... at the heart and origin of that debate is the quantum jump or quantum leap - the seemingly miraculous and instantaneous ... 00:24: The notion of a quantum jump or quantum leap is one of the founding concepts of quantum mechanics. 00:28: It’s really the OG of quantum weirdness - so much so that it’s become part of common lexicon, with very loose fidelity to the original meaning. 00:52: But one of the principal founders of quantum mechanics thought otherwise. 00:56: Erwin Schrodinger himself never accepted the idea of the quantum jump - but could also never prove it wrong. 01:07: However they exist now - and the reality of the quantum jump has finally been tested. 01:56: ... result was the Bohr model of the atom - the very first attempt at a quantum theory, and it very neatly explained the specific frequencies of light ... 02:25: But one thing remained mysterious - what was actually happening during the quantum jump, and what determined when a quantum jump would occur? 02:34: To address questions like this, Bohr and Heisenberg teamed up to develop the “Copenhagen interpretation” of quantum mechanics. 02:41: Copenhagen describes transitions in quantum states as fundamentally random - the dice are rolled, and the system transitions instantaneously. 02:55: ... with the environment causes the state transition - causes the quantum ... 03:14: ... said “If we are still going to have to put up with these damn quantum jumps, I am sorry that I ever had anything to do with quantum theory.” ... 03:40: ... 1952, Schrödinger published a two-part essay titled “Are there quantum jumps?” wherein he compared the theory of quantum jumps to that of ... 03:54: ... claimed that both epicycles and quantum jumps were “ingenious constructs of the human mind” that nevertheless ... 04:04: So why did Schrodinger hate quantum jumps so much? 04:07: Simply put, they seemed unnatural and unphysical - a hack added to cover up a phenomenon that quantum theory could not yet properly explain. 04:16: The debate over quantum jumps was just one part of the larger discussion about the quantum nature of reality. 04:54: He argued that most “spooky” quantum phenomena could be explained by classical resonance phenomena. 05:24: ... states during each transition, rather than undergoing instantaneous quantum ... 05:54: ... - and in 1952 we had never seen a single photon produced by a single quantum jump in a single ... 06:21: And in 1986, almost simultaneously, three different teams observed quantum jumps in such an atom. 07:14: ... wasn’t a direct observation of individual quantum jumps - that required an extra level of cleverness, as well as an extra ... 07:58: In this way, physicists were able to gain fairly direct evidence of a single quantum jump. 08:30: ... has advanced to the point that we can not only see individual quantum jumps - we can monitor their progress, and even interrupt them ... 08:48: The 3 different energy levels of this artificial atom corresponded to the number of electromagnetic quanta of energy stored in the circuits. 08:56: ... 1 using the notation from the previous experiment) corresponded to zero quanta in either circuit, states 2 and 3 corresponded to 1 quantum in either ... 09:28: They could actually zoom in on a quantum jump and finally figure out whether it truly was an instantaneous transition. 09:47: And that transition appeared to be perfectly described by theory - in this case quantum trajectory theory. 10:11: And that ability to predict also allowed them to reverse the quantum jumps midflight by adjusting the microwave field during the process. 10:19: ... that the quantum jump onset was predictable, and that its trajectory was extremely well ... 10:47: They explain this non-instantaneous quantum transition in terms of something called the Quantum Zeno Effect. 11:10: ... theorists showed how quantum states can transition very predictably through a series of superposition ... 11:31: The weaker the measurement, the less likely a true quantum jump is to occur. 11:44: For the longest time, physicists have shied away from asking which interpretation of quantum mechanics is correct. 12:06: ... and Schrodinger started the argument, we may be on the verge of the next quantum leap - to learning whether quantum jumps are instantaneous or ... 00:06: ... at the heart and origin of that debate is the quantum jump or quantum leap - the seemingly miraculous and instantaneous transitions ... 00:24: The notion of a quantum jump or quantum leap is one of the founding concepts of quantum mechanics. 00:56: Erwin Schrodinger himself never accepted the idea of the quantum jump - but could also never prove it wrong. 01:07: However they exist now - and the reality of the quantum jump has finally been tested. 02:25: But one thing remained mysterious - what was actually happening during the quantum jump, and what determined when a quantum jump would occur? 02:55: ... with the environment causes the state transition - causes the quantum jump. ... 05:54: ... - and in 1952 we had never seen a single photon produced by a single quantum jump in a single ... 07:58: In this way, physicists were able to gain fairly direct evidence of a single quantum jump. 09:28: They could actually zoom in on a quantum jump and finally figure out whether it truly was an instantaneous transition. 10:19: ... that the quantum jump onset was predictable, and that its trajectory was extremely well ... 11:31: The weaker the measurement, the less likely a true quantum jump is to occur. 00:56: Erwin Schrodinger himself never accepted the idea of the quantum jump - but could also never prove it wrong. 10:19: ... that the quantum jump onset was predictable, and that its trajectory was extremely well described by ... 03:14: ... said “If we are still going to have to put up with these damn quantum jumps, I am sorry that I ever had anything to do with quantum theory.” ... 03:40: ... 1952, Schrödinger published a two-part essay titled “Are there quantum jumps?” wherein he compared the theory of quantum jumps to that of epicycles—the ... 03:54: ... claimed that both epicycles and quantum jumps were “ingenious constructs of the human mind” that nevertheless were ... 04:04: So why did Schrodinger hate quantum jumps so much? 04:16: The debate over quantum jumps was just one part of the larger discussion about the quantum nature of reality. 05:24: ... states during each transition, rather than undergoing instantaneous quantum jumps. ... 06:21: And in 1986, almost simultaneously, three different teams observed quantum jumps in such an atom. 07:14: ... wasn’t a direct observation of individual quantum jumps - that required an extra level of cleverness, as well as an extra energy ... 08:30: ... has advanced to the point that we can not only see individual quantum jumps - we can monitor their progress, and even interrupt them ... 10:11: And that ability to predict also allowed them to reverse the quantum jumps midflight by adjusting the microwave field during the process. 11:10: ... - much as Schrodinger proposed - but in addition to these predictable quantum jumps there are fundamentally unpredictable ones--truly unpredictable and ... 12:06: ... we may be on the verge of the next quantum leap - to learning whether quantum jumps are instantaneous or continuous, and perhaps even whether the quantum ... 07:14: ... wasn’t a direct observation of individual quantum jumps - that required an extra level of cleverness, as well as an extra energy ... 08:30: ... has advanced to the point that we can not only see individual quantum jumps - we can monitor their progress, and even interrupt them ... 10:11: And that ability to predict also allowed them to reverse the quantum jumps midflight by adjusting the microwave field during the process. 00:06: ... at the heart and origin of that debate is the quantum jump or quantum leap - the seemingly miraculous and instantaneous transitions of quantum ... 00:24: The notion of a quantum jump or quantum leap is one of the founding concepts of quantum mechanics. 12:06: ... and Schrodinger started the argument, we may be on the verge of the next quantum leap - to learning whether quantum jumps are instantaneous or continuous, and ... 00:06: ... at the heart and origin of that debate is the quantum jump or quantum leap - the seemingly miraculous and instantaneous transitions of quantum ... 12:06: ... and Schrodinger started the argument, we may be on the verge of the next quantum leap - to learning whether quantum jumps are instantaneous or continuous, and ... 00:00: Since the very beginning of quantum mechanics, a debate has raged about how to interpret its bizarre predictions. 00:24: The notion of a quantum jump or quantum leap is one of the founding concepts of quantum mechanics. 00:52: But one of the principal founders of quantum mechanics thought otherwise. 01:56: ... and Erwin Schrodinger to develop the first complete formulations of quantum mechanics in ... 02:34: To address questions like this, Bohr and Heisenberg teamed up to develop the “Copenhagen interpretation” of quantum mechanics. 11:44: For the longest time, physicists have shied away from asking which interpretation of quantum mechanics is correct. 00:52: But one of the principal founders of quantum mechanics thought otherwise. 04:16: The debate over quantum jumps was just one part of the larger discussion about the quantum nature of reality. 04:54: He argued that most “spooky” quantum phenomena could be explained by classical resonance phenomena. 02:41: Copenhagen describes transitions in quantum states as fundamentally random - the dice are rolled, and the system transitions instantaneously. 11:10: ... theorists showed how quantum states can transition very predictably through a series of superposition states ... 00:06: ... quantum leap - the seemingly miraculous and instantaneous transitions of quantum systems that have always defied observation or ... 01:56: ... result was the Bohr model of the atom - the very first attempt at a quantum theory, and it very neatly explained the specific frequencies of light observed ... 03:14: ... these damn quantum jumps, I am sorry that I ever had anything to do with quantum theory.” Schrödinger became bed-ridden with an illness during that visit - ... 04:07: Simply put, they seemed unnatural and unphysical - a hack added to cover up a phenomenon that quantum theory could not yet properly explain. 03:14: ... these damn quantum jumps, I am sorry that I ever had anything to do with quantum theory.” Schrödinger became bed-ridden with an illness during that visit - perhaps he was ... 09:47: And that transition appeared to be perfectly described by theory - in this case quantum trajectory theory. 10:47: They explain this non-instantaneous quantum transition in terms of something called the Quantum Zeno Effect. 00:28: It’s really the OG of quantum weirdness - so much so that it’s become part of common lexicon, with very loose fidelity to the original meaning. 10:47: They explain this non-instantaneous quantum transition in terms of something called the Quantum Zeno Effect.
	2020-12-22: Navigating with Quantum Entanglement 00:00: ... often think of quantum mechanics as only affecting only the smallest scales of reality, with ... 00:08: ... in his 1944 book, What is Life?, the quantum physicist Erwin Schrödinger suggested that “incredibly small groups of ... 00:29: Because it turns out we might need all the weirdness of quantum mechanics to explain birds. 01:52: How do they do it and what does quantum mechanics have to do with all of this? 03:03: ... that proposes birds can in a sense see the Earth’s magnetic field due to quantum weirdness happening inside their ... 03:19: Before we get into all the cool quantum stuff, a quick review on Earth’s magnetic field is in order. 05:33: And this is where quantum mechanics comes in. 06:03: A quick review of quantum entanglement is in order here, although we’re talked about it before.. 06:08: When two particles are entangled, it means one or more of their quantum properties are correlated. 06:29: The entangled properties are the quantum spins of the two valence electrons in two separate radical molecules. 06:58: ... electrons have the same spin direction - either both up, both down, or a quantum superposition of both at the same ... 09:40: This “avian compass” presents a tantalizing possibility of quantum biology. 09:45: It’s strange to think of quantum effects being relevant in living organisms. 09:49: ... to observe the strange behavior of the quantum world we need to perform incredibly careful experiments in highly ... 10:07: Quantum entanglement is very quickly destroyed in such environments - but birds may have found a workaround. 10:12: ... entanglement is destroyed the subsequent chemical reactions remember the quantum state, and so remember the magnetic ... 10:24: So is this true quantum biology? 10:33: The team’s calculations showed that only a full quantum description of the process could produce the required sensitivity to magnetic fields. 10:54: So Erwin Schrodinger’s ideas about quantum mechanics influencing living organisms may be right. 10:59: And quantum magnetoreception in birds isn’t the only example of what we sometimes call “quantum biology”. 11:06: We know for sure that it happens in some cases - like the quantum tunneling that drives enzyme catalysis. 11:12: There are other contentious, but intriguing cases - like the idea that long-range quantum coherence may drive photosynthesis. 11:19: ... there are some highly contentious ideas - like quantum entanglement in the brain’s microtubule proteins as a key ingredient in ... 11:27: The quantum magnetoreception of the avian compass sits somewhere in the middle - not yet proved, but more and more favoured. 11:40: ... swallows - european especially - birds of many a feather using quantum physics to flock together to navigate the hidden lines of a geomagnetic ... 14:02: For more detail we would indeed need a whole episode Quantum fields asks what about neutron stars. 14:12: ... are two broad scenarios - first, if protons do NOT decay then quantum tunneling will cause the neutron star to collapse into a black hole over ... 15:21: So yeah, Russell’s teapot either evaporates as its protons decay, or quantum tunnels into an iron teapot - is that a kettle? 09:40: This “avian compass” presents a tantalizing possibility of quantum biology. 10:24: So is this true quantum biology? 10:59: And quantum magnetoreception in birds isn’t the only example of what we sometimes call “quantum biology”. 11:12: There are other contentious, but intriguing cases - like the idea that long-range quantum coherence may drive photosynthesis. 10:33: The team’s calculations showed that only a full quantum description of the process could produce the required sensitivity to magnetic fields. 09:45: It’s strange to think of quantum effects being relevant in living organisms. 06:03: A quick review of quantum entanglement is in order here, although we’re talked about it before.. 10:07: Quantum entanglement is very quickly destroyed in such environments - but birds may have found a workaround. 11:19: ... there are some highly contentious ideas - like quantum entanglement in the brain’s microtubule proteins as a key ingredient in human ... 14:02: For more detail we would indeed need a whole episode Quantum fields asks what about neutron stars. 10:59: And quantum magnetoreception in birds isn’t the only example of what we sometimes call “quantum biology”. 11:27: The quantum magnetoreception of the avian compass sits somewhere in the middle - not yet proved, but more and more favoured. 00:00: ... often think of quantum mechanics as only affecting only the smallest scales of reality, with classical ... 00:29: Because it turns out we might need all the weirdness of quantum mechanics to explain birds. 01:52: How do they do it and what does quantum mechanics have to do with all of this? 05:33: And this is where quantum mechanics comes in. 10:54: So Erwin Schrodinger’s ideas about quantum mechanics influencing living organisms may be right. 00:08: ... in his 1944 book, What is Life?, the quantum physicist Erwin Schrödinger suggested that “incredibly small groups of atoms, much ... 11:40: ... swallows - european especially - birds of many a feather using quantum physics to flock together to navigate the hidden lines of a geomagnetic space ... 06:08: When two particles are entangled, it means one or more of their quantum properties are correlated. 06:29: The entangled properties are the quantum spins of the two valence electrons in two separate radical molecules. 10:12: ... entanglement is destroyed the subsequent chemical reactions remember the quantum state, and so remember the magnetic ... 03:19: Before we get into all the cool quantum stuff, a quick review on Earth’s magnetic field is in order. 06:58: ... electrons have the same spin direction - either both up, both down, or a quantum superposition of both at the same ... 11:06: We know for sure that it happens in some cases - like the quantum tunneling that drives enzyme catalysis. 14:12: ... are two broad scenarios - first, if protons do NOT decay then quantum tunneling will cause the neutron star to collapse into a black hole over an ... 15:21: So yeah, Russell’s teapot either evaporates as its protons decay, or quantum tunnels into an iron teapot - is that a kettle? 03:03: ... that proposes birds can in a sense see the Earth’s magnetic field due to quantum weirdness happening inside their ...
	2020-12-15: The Supernova At The End of Time 01:39: ... hyperdense crystalline ball of quantum weirdness has supported itself against gravitational collapse by the ... 03:37: The new science of quantum mechanics had shattered our classical understanding of the world in many ways. 03:43: ... and then those electrons are crammed so close together that all possible quantum states are ... 03:58: Now electrons can’t overlap - can’t occupy identical quantum states - a weird quantum fact that had only been recently discovered. 08:14: Suddenly it’ll find itself one row over - teleported due to fundamental quantum uncertainty in its position. 08:22: This quantum tunneling lands the nucleus close enough to its neighbor that the two fuse into a heavier element. 09:20: ... quietly become black holes themselves through countless aeons of more quantum tunneling - something like 10^10^75 ... 15:21: This one depends entirely on your choice of interpretation of quantum mechanics. 03:58: Now electrons can’t overlap - can’t occupy identical quantum states - a weird quantum fact that had only been recently discovered. 03:37: The new science of quantum mechanics had shattered our classical understanding of the world in many ways. 15:21: This one depends entirely on your choice of interpretation of quantum mechanics. 03:43: ... and then those electrons are crammed so close together that all possible quantum states are ... 03:58: Now electrons can’t overlap - can’t occupy identical quantum states - a weird quantum fact that had only been recently discovered. 08:22: This quantum tunneling lands the nucleus close enough to its neighbor that the two fuse into a heavier element. 09:20: ... quietly become black holes themselves through countless aeons of more quantum tunneling - something like 10^10^75 ... 08:22: This quantum tunneling lands the nucleus close enough to its neighbor that the two fuse into a heavier element. 08:14: Suddenly it’ll find itself one row over - teleported due to fundamental quantum uncertainty in its position. 01:39: ... hyperdense crystalline ball of quantum weirdness has supported itself against gravitational collapse by the pressure ...
	2020-12-08: Why Do You Remember The Past But Not The Future? 05:16: We’re totally ignoring quantum indeterminacy, or that any information might be lost from the internal structure of the proton. 06:45: ... through in exactly the right way to erase their tracks, seemingly random quantum jiggling ejects these embedded clumps, and so on, until we’re left with ... 11:14: ... want to talk about how entropy is also connected to the spreading of quantum entanglement. If you have a universe of only pure quantum states they’ll ... 13:18: Ryan Christopherson asks whether the random nature of quantum mechanics isn’t a larger hurdle to the reversibility of time than entropy. 13:33: ... answer is that yes, IF quantum mechanics is fundamentally random, and IF the wavefunction collapse is a ... 11:14: ... want to talk about how entropy is also connected to the spreading of quantum entanglement. If you have a universe of only pure quantum states they’ll become more ... 05:16: We’re totally ignoring quantum indeterminacy, or that any information might be lost from the internal structure of the proton. 06:45: ... through in exactly the right way to erase their tracks, seemingly random quantum jiggling ejects these embedded clumps, and so on, until we’re left with a smooth ... 13:18: Ryan Christopherson asks whether the random nature of quantum mechanics isn’t a larger hurdle to the reversibility of time than entropy. 13:33: ... answer is that yes, IF quantum mechanics is fundamentally random, and IF the wavefunction collapse is a random ... 13:18: Ryan Christopherson asks whether the random nature of quantum mechanics isn’t a larger hurdle to the reversibility of time than entropy. 11:14: ... spreading of quantum entanglement. If you have a universe of only pure quantum states they’ll become more and more entangled in adjacent time steps, the arrow ...
	2020-11-18: The Arrow of Time and How to Reverse It 00:24: ... describe a universe in rewind. That’s true from the subatomic realm of quantum mechanics to the cosmic realm of Einstein’s general relativity. But if ... 09:39: ... we need to delve deeper. In fact it involves information theory and quantum entanglement, so we need another episode. Or more than one. Because on ... 11:16: ... Dr Diagrams also points us to Scott Aaronson’s essay "The Ghost in the Quantum Turing Machine”, which I’m going to go and read ... 13:36: ... back to matters quantum. Zahaquiel reminded us of the best proof regarding quantum ... 13:53: 2. Quantum electrodynamics has a pretty cool abbreviation. 13:58: therefore Quantum electrodynamics is better than other physics theories. 13:36: ... to matters quantum. Zahaquiel reminded us of the best proof regarding quantum electrodynamics, which comes from ontology: 1. A physics theory with a cool abbreviation ... 13:53: 2. Quantum electrodynamics has a pretty cool abbreviation. 13:58: therefore Quantum electrodynamics is better than other physics theories. 09:39: ... we need to delve deeper. In fact it involves information theory and quantum entanglement, so we need another episode. Or more than one. Because on Space Time ... 00:24: ... describe a universe in rewind. That’s true from the subatomic realm of quantum mechanics to the cosmic realm of Einstein’s general relativity. But if time ... 11:16: ... Dr Diagrams also points us to Scott Aaronson’s essay "The Ghost in the Quantum Turing Machine”, which I’m going to go and read ... 13:36: ... back to matters quantum. Zahaquiel reminded us of the best proof regarding quantum electrodynamics, which ...
	2020-11-11: Can Free Will be Saved in a Deterministic Universe? 02:03: Yes, we will mention the quantum, but importantly, that is not to say that free will or consciousness are necessarily related to it. 02:15: But understanding the implications of quantum mechanics is key to unraveling determinism and its connection to predictability. 02:22: Quantum mechanics seems to tell us that one of the following is true. 02:26: ... of quantum-scale events are fundamentally random or the outcomes of quantum events are perfectly determined by quantum laws and the apparent ... 02:46: One of the most important rules of quantum mechanics is the principle of conservation of quantum information. 02:51: It just says that quantum information can never be destroyed or created out of nothing. 03:00: Let's paint a cartoon representation of quantum information in a block universe. 03:15: Each bit of quantum information can be represented as a thread. 03:19: Threads are evolving quantum states. 03:21: These may transform and become entangled with each other, but if quantum information is conserved, a thread can never vanish nor start out of nothing. 04:23: ... form of a decision, either one, incorporates an entirely new thread of quantum information, in violation with the conservation principle, or two, that ... 05:37: Now, creating brand new information explicitly violates conservation of quantum information. 05:42: That said, the most mainstream interpretation of quantum mechanics has the same problem. 05:47: The Copenhagen interpretation insists that the apparent randomness of quantum events is really random. 05:52: The quantum information in the state of the wave function before collapse is destroyed, but information is also created. 05:59: The outcome of quantum interactions are chosen in fundamentally unpredictable ways. 06:21: Think about a new thread of quantum information starting from nothing, let's say emerging from a packet of space time where no information enters. 07:19: On the surface, the idea of randomly generating new streams of quantum information within a brain doesn't seem to help the cause of free will. 09:40: ... even the all-knowing Laplace demon may be out of luck, especially if quantum randomness or quantum indeterminacy is magnified to brain-level ... 09:50: Again, not saying consciousness is quantum. 10:17: All possible futures exist and develop according to the laws of quantum mechanics. 11:12: So this nexus of quantum information processing may truly be an unpredictable black box decision-making machine, at least some of the time. 02:26: ... of quantum-scale events are fundamentally random or the outcomes of quantum events are perfectly determined by quantum laws and the apparent randomness ... 05:47: The Copenhagen interpretation insists that the apparent randomness of quantum events is really random. 09:40: ... Laplace demon may be out of luck, especially if quantum randomness or quantum indeterminacy is magnified to brain-level ... 05:59: The outcome of quantum interactions are chosen in fundamentally unpredictable ways. 02:26: ... random or the outcomes of quantum events are perfectly determined by quantum laws and the apparent randomness comes from our limited ... 02:15: But understanding the implications of quantum mechanics is key to unraveling determinism and its connection to predictability. 02:22: Quantum mechanics seems to tell us that one of the following is true. 02:46: One of the most important rules of quantum mechanics is the principle of conservation of quantum information. 05:42: That said, the most mainstream interpretation of quantum mechanics has the same problem. 10:17: All possible futures exist and develop according to the laws of quantum mechanics. 09:40: ... even the all-knowing Laplace demon may be out of luck, especially if quantum randomness or quantum indeterminacy is magnified to brain-level ... 03:19: Threads are evolving quantum states. 02:26: ... the outcomes of quantum-scale events are fundamentally random or the outcomes of quantum events are ...
	2020-11-04: Electroweak Theory and the Origin of the Fundamental Forces 01:36: While the brand new field of quantum mechanics could describe the behaviour of electrons, nuclear processes remained mysterious. 01:46: Enrico Fermi made the first attempt at a full quantum description of beta decay with his ‘four fermion’ interaction. 02:36: ... effort was quantum electrodynamics, in which charged particles interact not by actually ... 02:56: QED is what we call a gauge theory - its force-carrying fields and particles arise from the symmetries of the quantum equations of motion. 04:50: ... try an example: In quantum mechanics, the wavefunction determines the probabilities of certain ... 05:01: Quantum mechanical equations of motion like the Schrodinger equation describe how the wavefunction evolves through space and time. 05:50: That resulted in a new quantum field and a corresponding particle. 06:49: The ‘U’ stands for unitary and tells us that elements of this group preserve vector length, or in our case quantum probability. 14:10: ... it’s bad because it causes unreconciled conflicts with other physics - quantum theory in this ... 01:46: Enrico Fermi made the first attempt at a full quantum description of beta decay with his ‘four fermion’ interaction. 02:36: ... effort was quantum electrodynamics, in which charged particles interact not by actually touching - but via a ... 02:56: QED is what we call a gauge theory - its force-carrying fields and particles arise from the symmetries of the quantum equations of motion. 05:50: That resulted in a new quantum field and a corresponding particle. 05:01: Quantum mechanical equations of motion like the Schrodinger equation describe how the wavefunction evolves through space and time. 01:36: While the brand new field of quantum mechanics could describe the behaviour of electrons, nuclear processes remained mysterious. 04:50: ... try an example: In quantum mechanics, the wavefunction determines the probabilities of certain outcomes being ... 06:49: The ‘U’ stands for unitary and tells us that elements of this group preserve vector length, or in our case quantum probability. 14:10: ... it’s bad because it causes unreconciled conflicts with other physics - quantum theory in this ...
	2020-10-27: How The Penrose Singularity Theorem Predicts The End of Space Time 11:10: ... points. The resolution must be the union of general relativity and quantum mechanics - a   theory of quantum gravity, from which both ... 12:51: ... quantum  mechanics had to say about the whole mess.   Quantum mechanics had a few things to say, but you guys had more. Let’s get to ... 13:38: ... type of communication between worlds, but only works if   quantum mechanics works in a particular non-linear way We should probably ... 11:10: ... general relativity and quantum mechanics - a   theory of quantum gravity, from which both quantum mechanics and relativity are just ... 12:51: ... quantum  mechanics had to say about the whole mess.   Quantum mechanics had a few things to say, but you guys had more. Let’s get to the ... 13:38: ... type of communication between worlds, but only works if   quantum mechanics works in a particular non-linear way We should probably do an ... 11:10: ... points. The resolution must be the union of general relativity and quantum mechanics - a   theory of quantum gravity, from which both ... 13:38: ... type of communication between worlds, but only works if   quantum mechanics works in a particular non-linear way We should probably do an episode on ... 12:51: ... and the block universe,   but this time weaving in what quantum  mechanics had to say about the whole mess.   Quantum mechanics ... 13:38: ... about we just do   that episode. Because I agree - relational quantum  mechanics is a really profound perspective,   in which the ... 12:51: ... and the block universe,   but this time weaving in what quantum  mechanics had to say about the whole mess.   Quantum mechanics had a few ... 13:38: ... about we just do   that episode. Because I agree - relational quantum  mechanics is a really profound perspective,   in which the “real” ... 11:10: ... mechanics - a   theory of quantum gravity, from which both quantum mechanics and relativity are just approximations.   Such a theory may ...
	2020-10-20: Is The Future Predetermined By Quantum Mechanics? 02:38: We need to see what quantum mechanics says about determinism and how it plays with relativity and the block universe. 02:46: According to quantum mechanics, physical systems, parts of the universe evolve as wave functions. 03:24: The big question is what causes the transition from this world of quantum indeterminacy to the solid singular reality of the macroscopic world. 03:50: ... is the so-called Copenhagen interpretation, which states that a quantum system is literally in a state of undefined-ness until ... 04:23: ... function evolves in a precise way, perfectly defined by the equations of quantum mechanics but at the moment of measurement, a single reality is randomly ... 04:45: Another popular interpretation of quantum mechanics is the Many-Worlds Interpretation, which simply states that the wave function never collapses. 04:53: Instead all possible states of the quantum system continue to exist. 04:57: ... than choosing one reality out of many, when we observe a quantum system, we sort of just become part of one of the realities and lose ... 08:15: Sometimes the quantum multiverse of Many-Worlds is depicted as this branching tree, in which the realities multiply as time progresses. 08:24: In the block universe picture, it's tempting to depict this as the entire block multiplying with every quantum event. 08:32: A division in the block universe can only propagate as quickly as the result of that quantum event can become known. 08:46: Really what's happening here is that parts of the universe become entangled with each other, correlated at a quantum level. 08:55: Each such web defines a set of properties of the universe correlated with some prior quantum decision. 09:07: Here we are bringing in the concept of decoherence and quantum Darwinism, which we've covered before. 09:23: According to the decoherence explanation, the quantum multiverse isn't a cleanly divided set of alternate realities. 09:59: However, light speed signaling is the surest way to transfer quantum correlations so this is still a useful picture. 11:06: Copenhagen and Many-Worlds aren't the only interpretations of quantum mechanics in town. 11:51: So does the future already exist according to quantum theory? 11:55: The answer depends on your favorite flavor of quantum interpretation. 12:00: ... ride the dice of Copenhagen into an unknown future or surf the splitting quantum multiverse into all futures of which you will become just ... 09:59: However, light speed signaling is the surest way to transfer quantum correlations so this is still a useful picture. 09:07: Here we are bringing in the concept of decoherence and quantum Darwinism, which we've covered before. 08:55: Each such web defines a set of properties of the universe correlated with some prior quantum decision. 08:24: In the block universe picture, it's tempting to depict this as the entire block multiplying with every quantum event. 08:32: A division in the block universe can only propagate as quickly as the result of that quantum event can become known. 03:24: The big question is what causes the transition from this world of quantum indeterminacy to the solid singular reality of the macroscopic world. 11:55: The answer depends on your favorite flavor of quantum interpretation. 08:46: Really what's happening here is that parts of the universe become entangled with each other, correlated at a quantum level. 02:38: We need to see what quantum mechanics says about determinism and how it plays with relativity and the block universe. 02:46: According to quantum mechanics, physical systems, parts of the universe evolve as wave functions. 04:23: ... function evolves in a precise way, perfectly defined by the equations of quantum mechanics but at the moment of measurement, a single reality is randomly selected ... 04:45: Another popular interpretation of quantum mechanics is the Many-Worlds Interpretation, which simply states that the wave function never collapses. 11:06: Copenhagen and Many-Worlds aren't the only interpretations of quantum mechanics in town. 02:46: According to quantum mechanics, physical systems, parts of the universe evolve as wave functions. 08:15: Sometimes the quantum multiverse of Many-Worlds is depicted as this branching tree, in which the realities multiply as time progresses. 09:23: According to the decoherence explanation, the quantum multiverse isn't a cleanly divided set of alternate realities. 12:00: ... ride the dice of Copenhagen into an unknown future or surf the splitting quantum multiverse into all futures of which you will become just ... 09:23: According to the decoherence explanation, the quantum multiverse isn't a cleanly divided set of alternate realities. 11:51: So does the future already exist according to quantum theory?
	2020-10-13: Do the Past and Future Exist? 01:44: Now quantum mechanics might argue otherwise, depending on which quantum mechanics you prefer, but we’ll come back to in an upcoming episode. 12:00: To rescue materialism without demanding a perfectly defined personal future we need quantum mechanics. 12:07: ... Quantum mechanics tells us that all this stuff outside our past lightcone - and ... 12:17: Depending on how you interpret quantum mechanics, that could be evidence in favor of this solipsistic denial of external reality. 12:24: ... quantum can also save materialism and determinism if you like- but to do so you ... 12:35: ... these ideas before - the Copenhagen and Many Worlds interpretations of quantum mechanics - but soon we’ll dive back in, to see what these idea imply ... 01:44: Now quantum mechanics might argue otherwise, depending on which quantum mechanics you prefer, but we’ll come back to in an upcoming episode. 12:00: To rescue materialism without demanding a perfectly defined personal future we need quantum mechanics. 12:07: ... Quantum mechanics tells us that all this stuff outside our past lightcone - and even ... 12:17: Depending on how you interpret quantum mechanics, that could be evidence in favor of this solipsistic denial of external reality. 12:35: ... these ideas before - the Copenhagen and Many Worlds interpretations of quantum mechanics - but soon we’ll dive back in, to see what these idea imply about time, ... 12:07: ... Quantum mechanics tells us that all this stuff outside our past lightcone - and even unobserved ...
	2020-10-05: Venus May Have Life! 14:02: ... - possible solutions to the impending cryptography-cracking powers of quantum computers that don’t themselves require quantum ... 15:19: Which I guess you don’t need a quantum computer for. 15:35: Really, there were doubts that any salad-based protocols would be meaty enough to resist quantum decryption. 15:19: Which I guess you don’t need a quantum computer for. 14:02: ... - possible solutions to the impending cryptography-cracking powers of quantum computers that don’t themselves require quantum ... 15:35: Really, there were doubts that any salad-based protocols would be meaty enough to resist quantum decryption. 14:02: ... powers of quantum computers that don’t themselves require quantum technology. ...
	2020-09-28: Solving Quantum Cryptography 00:10: ... math problem is prime number factoring, and the new era of quantum computers may lay bare your indiscretions, as well as collapse the ... 00:31: ... said that quantum computers will threaten the security of our digital civilization because ... 01:08: ... Peter Shor developed an algorithm - Shor’s algorithm - that could use a quantum computer to factor a prime number in, well, a human lifetime, or a human ... 01:23: ... Quantum computers did not exist in 1994, but just last year, Google’s quantum ... 01:33: ... to the researchers, Sycamore performed calculations to simulate another quantum system exponentially faster than would have been possible with a pure ... 01:51: ... quite - quantum computers need to become far more reliable - have better “fault ... 02:07: One option is to match quantum decryption with new quantum encryption techniques to replace prime factoring. 02:15: We talked about all this in our episode on quantum key distribution - and we’ve also talked about the challenges. 02:21: To distribute a quantum key, you also need a quantum internet to transport quantum states. 02:29: ... Quantum states are insanely fragile and difficult to transport, and the quantum ... 02:41: Fortunately there is another option - and one that’ll be a lot cheaper than building a quantum internet. 02:48: It turns out there are some ingenious non-quantum ways to thwart the hacking powers of quantum computers. 02:55: Enter post-quantum cryptography, or quantum resistant algorithms - which might replace our vulnerable prime factoring-based cryptography. 03:04: ... understand why some algorithms are vulnerable to quantum computing attacks while others are thought to be quantum resistant, we ... 04:21: It works great except for its vulnerability to Shor’s algorithm and quantum computers. 04:36: To understand that, we need a brief word on how quantum computers do their magic. 05:24: It turns out there’s a structure to factorization that can be exploited by quantum computers. 06:27: This is where quantum weirdness comes in. 06:35: ... Quantum computers store information in qubits, which, until they give an output, ... 06:59: ... across different computers, you’re processing in different parts of the quantum wavefunction - or in different parallel realities if you’re into the ... 07:23: ... you tried to use a quantum computer to guess the factors of a prime number, you’d read out one of ... 07:38: ... of qubits holds these repeating moduli of Shor’s algorithm - one per quantum state in the ... 08:20: So far, quantum computers are stuck under 100 qubits and none have managed to factor a number higher than 21 with Shor’s algorithm. 08:31: Does that mean I’m a quantum computer? 08:37: ... current technology isn’t there yet, when we figure out how to build quantum computers with thousands of qubits even the very high digit RSA keys ... 09:15: In 2022, NIST is expected to narrow it down to one or two quantum resistant algorithms. 09:20: ... signatures—and they’ll hopefully be able to protect our data from quantum computing ... 11:53: To be secure against quantum attacks for the foreseeable future, McEliece would need an 8 Mb public key—8,000 times larger. 12:45: So far there’s no known classical or quantum algorithm that solves it quickly for large lattices. 12:58: ... is the question is whether these algorithms are really robust against quantum and classical ... 13:34: ... true that these quantum resistant algorithms seem like they will be hard, if not impossible for ... 13:58: ... at the end of the day, quantum key distribution proponents would rather put their faith in fundamental ... 14:11: ... the meantime, post-quantum crypto may be our only hope as black hat quantum hackers attempt to decrypt your embarrassing emails across the parallel ... 12:45: So far there’s no known classical or quantum algorithm that solves it quickly for large lattices. 11:53: To be secure against quantum attacks for the foreseeable future, McEliece would need an 8 Mb public key—8,000 times larger. 01:08: ... Peter Shor developed an algorithm - Shor’s algorithm - that could use a quantum computer to factor a prime number in, well, a human lifetime, or a human ... 01:23: ... computers did not exist in 1994, but just last year, Google’s quantum computer, Sycamore, outsped the best classical computers for a very specific ... 07:23: ... you tried to use a quantum computer to guess the factors of a prime number, you’d read out one of the ... 08:31: Does that mean I’m a quantum computer? 01:23: ... computers did not exist in 1994, but just last year, Google’s quantum computer, Sycamore, outsped the best classical computers for a very specific ... 00:10: ... math problem is prime number factoring, and the new era of quantum computers may lay bare your indiscretions, as well as collapse the entire digital ... 00:31: ... said that quantum computers will threaten the security of our digital civilization because they can ... 01:23: ... Quantum computers did not exist in 1994, but just last year, Google’s quantum computer, ... 01:51: ... quite - quantum computers need to become far more reliable - have better “fault tolerance” and/or ... 02:29: ... to transport, and the quantum internet may not arrive before better quantum computers can crack current encryption techniques and collapse the modern digital ... 02:48: It turns out there are some ingenious non-quantum ways to thwart the hacking powers of quantum computers. 04:21: It works great except for its vulnerability to Shor’s algorithm and quantum computers. 04:36: To understand that, we need a brief word on how quantum computers do their magic. 05:24: It turns out there’s a structure to factorization that can be exploited by quantum computers. 06:35: ... Quantum computers store information in qubits, which, until they give an output, are in a ... 08:20: So far, quantum computers are stuck under 100 qubits and none have managed to factor a number higher than 21 with Shor’s algorithm. 08:37: ... current technology isn’t there yet, when we figure out how to build quantum computers with thousands of qubits even the very high digit RSA keys will not be ... 13:34: ... resistant algorithms seem like they will be hard, if not impossible for quantum computers to crack, but that doesn’t mean no one will come up with a way to do ... 06:35: ... Quantum computers store information in qubits, which, until they give an output, are in a ... 03:04: ... understand why some algorithms are vulnerable to quantum computing attacks while others are thought to be quantum resistant, we need to ... 09:20: ... signatures—and they’ll hopefully be able to protect our data from quantum computing ... 03:04: ... understand why some algorithms are vulnerable to quantum computing attacks while others are thought to be quantum resistant, we need to review a ... 09:20: ... signatures—and they’ll hopefully be able to protect our data from quantum computing attacks. ... 02:07: One option is to match quantum decryption with new quantum encryption techniques to replace prime factoring. 14:11: ... the meantime, post-quantum crypto may be our only hope as black hat quantum hackers attempt to decrypt your embarrassing emails across the parallel quantum ... 02:21: To distribute a quantum key, you also need a quantum internet to transport quantum states. 02:29: ... states are insanely fragile and difficult to transport, and the quantum internet may not arrive before better quantum computers can crack current ... 02:41: Fortunately there is another option - and one that’ll be a lot cheaper than building a quantum internet. 13:58: ... in fundamental laws of physics - pretty darn secure if only we had a quantum internet. ... 02:15: We talked about all this in our episode on quantum key distribution - and we’ve also talked about the challenges. 02:21: To distribute a quantum key, you also need a quantum internet to transport quantum states. 13:58: ... at the end of the day, quantum key distribution proponents would rather put their faith in fundamental laws ... 02:15: We talked about all this in our episode on quantum key distribution - and we’ve also talked about the challenges. 13:58: ... at the end of the day, quantum key distribution proponents would rather put their faith in fundamental laws of physics - ... 06:59: ... parallel realities if you’re into the Many Worlds interpretation of quantum mechanics. ... 02:55: Enter post-quantum cryptography, or quantum resistant algorithms - which might replace our vulnerable prime factoring-based cryptography. 03:04: ... vulnerable to quantum computing attacks while others are thought to be quantum resistant, we need to review a bit about bit about ... 09:15: In 2022, NIST is expected to narrow it down to one or two quantum resistant algorithms. 13:34: ... true that these quantum resistant algorithms seem like they will be hard, if not impossible for quantum ... 02:55: Enter post-quantum cryptography, or quantum resistant algorithms - which might replace our vulnerable prime factoring-based cryptography. 09:15: In 2022, NIST is expected to narrow it down to one or two quantum resistant algorithms. 13:34: ... true that these quantum resistant algorithms seem like they will be hard, if not impossible for quantum computers to ... 14:11: ... hackers attempt to decrypt your embarrassing emails across the parallel quantum space ... 07:38: ... of qubits holds these repeating moduli of Shor’s algorithm - one per quantum state in the ... 02:21: To distribute a quantum key, you also need a quantum internet to transport quantum states. 02:29: ... Quantum states are insanely fragile and difficult to transport, and the quantum ... 06:35: ... store information in qubits, which, until they give an output, are in a quantum superposition of 0 and 1, with some probability of either being measured when you try ... 06:59: ... across different computers, you’re processing in different parts of the quantum wavefunction - or in different parallel realities if you’re into the Many Worlds ... 06:27: This is where quantum weirdness comes in.
	2020-09-21: Could Life Evolve Inside Stars? 03:00: Quantum fields should also be able to develop topological defects. 03:16: But here, the quantum fields themselves changed state due to the rapidly dropping temperature. 10:14: So are the stars filled with thriving ecosystems of critters built from fractured quantum fields? 03:00: Quantum fields should also be able to develop topological defects. 03:16: But here, the quantum fields themselves changed state due to the rapidly dropping temperature. 10:14: So are the stars filled with thriving ecosystems of critters built from fractured quantum fields?
	2020-09-08: The Truth About Beauty in Physics 07:19: ... Dirac, one of the principal founders of quantum mechanics, said “It is more important to have beauty in one's equation ... 07:49: He sought to develop a quantum mechanical wave equation that agreed with Einstein’s special relativity. 08:11: The resulting Dirac equation is the entirely correct relativistic quantum description of the behavior of the electron. 11:30: His idea of introducing a new symmetry to space was translated to adding a new symmetry to the wavefunction in quantum mechanics. 08:11: The resulting Dirac equation is the entirely correct relativistic quantum description of the behavior of the electron. 07:49: He sought to develop a quantum mechanical wave equation that agreed with Einstein’s special relativity. 07:19: ... Dirac, one of the principal founders of quantum mechanics, said “It is more important to have beauty in one's equation than to have ... 11:30: His idea of introducing a new symmetry to space was translated to adding a new symmetry to the wavefunction in quantum mechanics.
	2020-09-01: How Do We Know What Stars Are Made Of? 00:39: A hundred years ago, we were starting to plumb the deepest mysteries of the universe with Einstein’s relativity and with quantum theory. 06:04: The brand new field of quantum mechanics was emerging in Europe, and a young astrophysicist named Cecilia Payne had just arrived at Harvard. 06:13: ... was widely read and so she knew about some groundbreaking work in early quantum theory that she could use to decode the complex patterns of absorption ... 07:00: ... her research, Indian astrophysicist Meghdad Saha had used early ideas in quantum theory to crack the ionization ... 06:04: The brand new field of quantum mechanics was emerging in Europe, and a young astrophysicist named Cecilia Payne had just arrived at Harvard. 00:39: A hundred years ago, we were starting to plumb the deepest mysteries of the universe with Einstein’s relativity and with quantum theory. 06:13: ... was widely read and so she knew about some groundbreaking work in early quantum theory that she could use to decode the complex patterns of absorption lines in ... 07:00: ... her research, Indian astrophysicist Meghdad Saha had used early ideas in quantum theory to crack the ionization ...
	2020-08-24: Can Future Colliders Break the Standard Model? 03:29: Finally we’d reached collision energies needed to test predictions of the still relatively new quantum electrodynamics. 03:36: This was huge in solidifying our understanding of the quantum world. 05:25: ... masses of the known particles and what we expect their masses to be from quantum field theory ... 06:02: ... cancel out the interactions of the known particles with the elementary quantum fields on which those particles live, eliminating most of their mass in ... 03:29: Finally we’d reached collision energies needed to test predictions of the still relatively new quantum electrodynamics. 05:25: ... masses of the known particles and what we expect their masses to be from quantum field theory ... 06:02: ... cancel out the interactions of the known particles with the elementary quantum fields on which those particles live, eliminating most of their mass in the ...
	2020-08-17: How Stars Destroy Each Other 11:50: ... think a theory of quantum gravity probably prevents the singularity from really forming - but ...
	2020-08-10: Theory of Everything Controversies: Livestream 00:00: ... for the past century after the great revolutions of relativity and quantum mechanics so together with professor brian keating astrophysicist and ...
	2020-07-28: What is a Theory of Everything: Livestream 00:00: ... a hugely broad range of interests including string theory and loop quantum gravity in principle we could do this entire conversation just with ...
	2020-07-20: The Boundary Between Black Holes & Neutron Stars 06:17: That ball of neutrons is a fundamentally quantum mechanical object. 11:08: Each will be rich in information on the nature of stars, and gravity, and strange quantum states of matter. 06:17: That ball of neutrons is a fundamentally quantum mechanical object. 11:08: Each will be rich in information on the nature of stars, and gravity, and strange quantum states of matter.
	2020-07-08: Does Antimatter Explain Why There's Something Rather Than Nothing? 04:05: ... universe of matter, and would undo a lot of what we think we know about quantum mechanics. So, good news bad news I ... 05:19: ... besides the charge and spin thing — it must have the same mass, the same quantum energy levels, and the same interactions with its ... 09:19: ... and even the strength of the coupling between the particles and the quantum fluctuations of the vacuum. Any difference in these properties in ... 05:19: ... besides the charge and spin thing — it must have the same mass, the same quantum energy levels, and the same interactions with its ... 09:19: ... and even the strength of the coupling between the particles and the quantum fluctuations of the vacuum. Any difference in these properties in anti-matter versus ... 04:05: ... universe of matter, and would undo a lot of what we think we know about quantum mechanics. So, good news bad news I ...
	2020-06-22: Building Black Holes in a Lab 05:25: ... involves the black hole scattering the vibrational modes of the quantum fields that have wavelengths similar to the black hole’s event ... 06:12: This perturbs the quantum fields in a way that look likes escaping particles if you’re very far away from the black hole. 06:20: ... case of an analog watery black hole you just replace “vibration in the quantum field” with “ripple on surface of water” and viola, same deal. ... 09:19: ... useful as classical analogs are, Hawking radiation is ultimately a quantum mechanical effect. Deeper insights may require an analog quantum black ... 10:37: Besides rubidium gas, there are other quantum systems which physicists are using as analogs. 10:44: ... are even quantum optical analogs, in which light sees an apparent horizon—usually caused ... 11:04: ... Hawking radiation need not necessarily depend on a specific theory of quantum gravity. Proponents of this line of thought have triumphantly pointed to ... 09:19: ... a quantum mechanical effect. Deeper insights may require an analog quantum black hole. Enter the Bose-Einstein condensate. Bose-Einstein condensates, or ... 06:20: ... case of an analog watery black hole you just replace “vibration in the quantum field” with “ripple on surface of water” and viola, same deal. ... 05:25: ... involves the black hole scattering the vibrational modes of the quantum fields that have wavelengths similar to the black hole’s event ... 06:12: This perturbs the quantum fields in a way that look likes escaping particles if you’re very far away from the black hole. 11:04: ... Hawking radiation need not necessarily depend on a specific theory of quantum gravity. Proponents of this line of thought have triumphantly pointed to ... 09:19: ... useful as classical analogs are, Hawking radiation is ultimately a quantum mechanical effect. Deeper insights may require an analog quantum black hole. Enter ... 10:44: ... are even quantum optical analogs, in which light sees an apparent horizon—usually caused by some ... 10:37: Besides rubidium gas, there are other quantum systems which physicists are using as analogs.
	2020-06-15: What Happens After the Universe Ends? 07:16: ... electrons and positrons, and neutrinos, as well as gravitons - the quantum particles of ... 07:53: ... particles - they come from the interactions of those particles with quantum fields - the Higgs field in the case of the ... 12:54: This is another issue with the CCC model - most physicists think quantum information can’t be destroyed. 07:53: ... particles - they come from the interactions of those particles with quantum fields - the Higgs field in the case of the ... 07:16: ... electrons and positrons, and neutrinos, as well as gravitons - the quantum particles of ...
	2020-06-08: Can Viruses Travel Between Planets? 16:13: Well I’d accuse you of propogating quantum woowoo, except that this theory is actually supported right at the top.
	2020-05-27: Does Gravity Require Extra Dimensions? 11:58: This is the negative pressure due to the exclusion of quantum vacuum modes, or virtual particles, between two very closely separated plates. 13:49: ... through black holes has nothing to do with the multiverse predicted by quantum ... 14:04: ... quantum multiverse is what you get when you accept Hugh Everett's many worlds ... 14:24: ... say the second multiverse is less likely to be real than the quantum multiverse - it's almost certainly a mathematical figment, arising from ... 14:04: ... worlds interpretation, which implies that the universe splits at every quantum event. ... 14:24: ... say the second multiverse is less likely to be real than the quantum multiverse - it's almost certainly a mathematical figment, arising from idealized ... 13:49: ... through black holes has nothing to do with the multiverse predicted by quantum physics. ... 11:58: This is the negative pressure due to the exclusion of quantum vacuum modes, or virtual particles, between two very closely separated plates.
	2020-05-18: Mapping the Multiverse 14:50: Will that next step be as surprising as relativity and the quantum revolution? 15:40: ... higher precision using other methods - lasers, vacuum chambers, strange quantum mechanical states of light - you name ... 14:50: Will that next step be as surprising as relativity and the quantum revolution?
	2020-05-11: How Luminiferous Aether Led to Relativity 12:25: ... aether” could explain the near vacuum state of spacetime in which quantum physicists believe particle pairs are quickly born and destroyed. In ... 13:18: ... But that death helped spark the revolutions of relativity and then quantum theory that revealed a much weirder, but still totally luminiferous ... 12:25: ... flowing fabric is the source of the gravitational field, and its full of quantum fields. ... 13:18: ... But that death helped spark the revolutions of relativity and then quantum theory that revealed a much weirder, but still totally luminiferous space ...
	2020-05-04: How We Know The Universe is Ancient 16:59: ... She loves crawling into boxes whenever possible, I assume to test quantum theory. Miraculously emerging definitely alive every time. She's become ...
	2020-04-28: Space Time Livestream: Ask Matt Anything 00:00: ... in the late 1900s late 1800s actually in the era of relativity and quantum physics and this is kind of you know Astro 101 except for the fact ...
	2020-04-22: Will Wormholes Allow Fast Interstellar Travel? 09:44: ... plates that are brought very close together will block components of the quantum vacuum from existing in that region. The gap between the plates will ... 11:03: ... - paths back to your own past - except in useless circumstances like on quantum scales or if they’re hidden by an event horizon. Combined with Roger ... 12:17: ... your needs. And there is one place natural wormholes might exist: in the quantum vacuum. This was another idea of John ... 13:26: ... Maldecina have speculated that the Einstein-Rosen bridge may explain quantum entanglement - itself first described by Einstein and Rosen, along with ... 11:03: ... - paths back to your own past - except in useless circumstances like on quantum scales or if they’re hidden by an event horizon. Combined with Roger Penrose’ ... 09:44: ... plates that are brought very close together will block components of the quantum vacuum from existing in that region. The gap between the plates will then have ... 12:17: ... your needs. And there is one place natural wormholes might exist: in the quantum vacuum. This was another idea of John ...
	2020-03-31: What’s On The Other Side Of A Black Hole? 11:37: ... comments for the last two episodes which are on rotating black holes and quantum darwinism. Let’s see what you had to ... 12:02: ... is the principle of monogamy of entanglement, which states that a given quantum state can only be maximally entangled with one other quantum state. The ... 13:01: ... this idea: the macroscopic "world" is a filter function which selects quantum states immune to entanglement diffusion. So that's almost it, but ... 14:15: ... points out that the way quantum states become increasingly entangled with their environment seems ... 14:25: ... connected. I've been meaning to get around to a whole episode on quantum entropy - aka von neumann entropy, and how it relates to entopy. We'll ... 11:37: ... comments for the last two episodes which are on rotating black holes and quantum darwinism. Let’s see what you had to ... 14:25: ... connected. I've been meaning to get around to a whole episode on quantum entropy - aka von neumann entropy, and how it relates to entopy. We'll get ... 12:02: ... is the principle of monogamy of entanglement, which states that a given quantum state can only be maximally entangled with one other quantum state. The key ... 13:01: ... environment, but in a coherent way that enables us to infer the intitial quantum state. ... 14:15: ... points out that the way quantum states become increasingly entangled with their environment seems analogous to ... 13:01: ... this idea: the macroscopic "world" is a filter function which selects quantum states immune to entanglement diffusion. So that's almost it, but actually ALL ...
	2020-03-16: How Do Quantum States Manifest In The Classical World? 00:04: ... from the information flowing through an impossibly complex network of quantum entanglement, that just happens to mutually agree that you and I exist ... 00:20: ... the quantum world things are routinely in multiple states at once - what we call a ... 00:44: ... Quantum mechanics tells us that the atom’s wavefunction can be in a ... 00:57: ... seems absurd - but quantum mechanics appears to allow this. In fact the idea of superposition is ... 01:48: ... states. But that doesn’t tell us why certain states that exist in the quantum world can survive this decoherence and become manifest in the classical ... 02:39: ... to lay out are mostly due to Wojciech Zurek, who calls this framework quantum darwinism - and you’ll see why. To get there we need to start by talking ... 02:56: ... quantum particles have a property called quantum spin. That spin has an axis ... 03:37: ... the value for quantum spin depends on how you choose to measure it - it depends on your ... 04:28: ... came up with to demonstrate an apparent absurdity predicted by pure quantum mechanics. This is the so-called Einstein-Podolsky-Rosen, or EPR ... 10:14: ... a chain of quantum systems between that original atom and the pointer. Information spreads ... 10:41: ... as more and more particles join our entanglement web, information about quantum states get spread amongst ... 10:53: ... environment - it’s no longer bounded, and so the information about most quantum states can’t be ... 11:11: ... there are certain very special quantum states whose information does NOT get hopelessly mixed through this ... 11:30: ... our dial’s pointer - are strongly correlated with these states of our quantum ... 11:48: ... what determines whether a quantum state can be a pointer state? Well to some extent the way you set up the ... 12:04: ... for environmentally induced superselection. And he coined the term quantum darwinism too, because we have these more “fit” states surviving and ... 12:33: ... important example of a pointer state is the position of a particle. Most quantum interactions depend heavily on the relative location of interacting ... 13:22: ... this fully solves the measurement problem it only tells us why certain quantum states are observable on macroscopic scales while Schroedinger Cat ... 13:47: ... - object positions, feline mortality statuses, even the results of quantum measurements - do NOT exist in the underlying quantum objects. Quantum ... 15:28: ... about a thought experiment to test the many worlds interpretation of quantum mechanics - quantum immortality, aka quantum suicide, in which a ... 16:29: ... had an excellent insight. If every possible combination of quantum events exists and if the increase of entropy is probabilistic, then is ... 18:58: ... declines our offer of quantum immortality, saying "I'll stick with classical immortality, thank you". ... 02:39: ... to lay out are mostly due to Wojciech Zurek, who calls this framework quantum darwinism - and you’ll see why. To get there we need to start by talking about ... 12:04: ... for environmentally induced superselection. And he coined the term quantum darwinism too, because we have these more “fit” states surviving and being ... 02:39: ... to lay out are mostly due to Wojciech Zurek, who calls this framework quantum darwinism - and you’ll see why. To get there we need to start by talking about ... 00:04: ... from the information flowing through an impossibly complex network of quantum entanglement, that just happens to mutually agree that you and I exist inside it. Oh, ... 01:48: ... in the classical world. To get the entire answer, we need to think about quantum entanglement. In fact we’ll see that the properties we think of as fundamental - for ... 15:28: ... suicide, in which a physicist will survive a long chain of deadly quantum events ONLY if all possible histories - or worlds - ... 16:29: ... had an excellent insight. If every possible combination of quantum events exists and if the increase of entropy is probabilistic, then is it ... 15:28: ... experiment to test the many worlds interpretation of quantum mechanics - quantum immortality, aka quantum suicide, in which a physicist will survive a long chain of ... 18:58: ... declines our offer of quantum immortality, saying "I'll stick with classical immortality, thank you". thanks for ... 15:28: ... experiment to test the many worlds interpretation of quantum mechanics - quantum immortality, aka quantum suicide, in which a physicist will survive a long chain of ... 12:33: ... important example of a pointer state is the position of a particle. Most quantum interactions depend heavily on the relative location of interacting particles. ... 00:57: ... states - the sum of those states is also a valid state. In fact, at the quantum level, there isn’t a clear way to define what states are the most basic. Even ... 13:47: ... - object positions, feline mortality statuses, even the results of quantum measurements - do NOT exist in the underlying quantum objects. Quantum objects remain ... 00:44: ... Quantum mechanics tells us that the atom’s wavefunction can be in a superposition of ... 00:57: ... seems absurd - but quantum mechanics appears to allow this. In fact the idea of superposition is fundamental ... 04:28: ... came up with to demonstrate an apparent absurdity predicted by pure quantum mechanics. This is the so-called Einstein-Podolsky-Rosen, or EPR paradox. A high ... 15:28: ... about a thought experiment to test the many worlds interpretation of quantum mechanics - quantum immortality, aka quantum suicide, in which a physicist will ... 00:57: ... seems absurd - but quantum mechanics appears to allow this. In fact the idea of superposition is fundamental to ... 00:44: ... Quantum mechanics tells us that the atom’s wavefunction can be in a superposition of states - ... 13:47: ... the results of quantum measurements - do NOT exist in the underlying quantum objects. Quantum objects remain in undefined and superposed states with no ... 02:56: ... quantum particles have a property called quantum spin. That spin has an axis that points ... 03:37: ... the value for quantum spin depends on how you choose to measure it - it depends on your ... 11:48: ... what determines whether a quantum state can be a pointer state? Well to some extent the way you set up the ... 00:57: ... of superposition is fundamental to quantum mechanics. Pick any two valid quantum states - the sum of those states is also a valid state. In fact, at the quantum ... 03:37: ... in any previous basis. This is an example of how seemingly-fundamental quantum states can be expressed as superpositions of other states. So again - why are ... 10:41: ... as more and more particles join our entanglement web, information about quantum states get spread amongst ... 10:53: ... environment - it’s no longer bounded, and so the information about most quantum states can’t be ... 11:11: ... there are certain very special quantum states whose information does NOT get hopelessly mixed through this ... 13:22: ... this fully solves the measurement problem it only tells us why certain quantum states are observable on macroscopic scales while Schroedinger Cat states - ... 00:57: ... of superposition is fundamental to quantum mechanics. Pick any two valid quantum states - the sum of those states is also a valid state. In fact, at the quantum ... 03:37: ... as superpositions of other states. So again - why are only certain quantum states observable on large scales? The answer lies in ... 15:28: ... worlds interpretation of quantum mechanics - quantum immortality, aka quantum suicide, in which a physicist will survive a long chain of deadly quantum events ... 02:39: ... - and you’ll see why. To get there we need to start by talking about quantum superposition. ... 10:14: ... a chain of quantum systems between that original atom and the pointer. Information spreads along ... 13:47: ... mutual agreement across the network of entanglements that connect those quantum systems. In a sense, WE exist in such a network. In this web of mutually ... 12:33: ... The individual particles do NOT have well-defined locations - they stay quantum-weird. But the entanglement network has this sort of collective consensus about ...
	2020-03-03: Does Quantum Immortality Save Schrödinger's Cat? 00:11: If the quantum multiverse is real there may be a version of you that lives forever. 00:22: In the last couple of episodes we’ve been delving into a key mystery of quantum mechanics - why don’t we have quantum magical powers? 00:30: Or, more scientifically, what causes the divide between the weird behavior of quantum world and our large-scale, macroscopic world? 00:39: ... particular, what causes quantum systems to transition from simultaneously existing in many states at the ... 01:18: ... in one of them, we need to embrace one of the interpretations of quantum ... 02:17: We’ll call this test quantum immortality. 02:33: ... of the radioactive decay over a certain period of time - that means the quantum wavefunction of the atom splits equally - the atom is simultaneously ... 04:33: ... which tells us that there’s ultimately only a single result from each quantum event, so a single result from the “Schrodinger’s physicist” ... 05:21: ... is right because the chance survival under any other interpretation of quantum mechanics is basically ... 05:31: Many Worlds, on the other hand, guarantees their survival in at least one branch of the quantum wavefunction. 05:59: This thought experiment is sometimes called quantum immortality. 06:04: ... that any process leading to mortality is ultimately a sequence of quantum events - so there are timelines in which those incremental steps towards ... 06:25: Hugh Everett, who first came up with the many Worlds interpretation, actually believed in this sort of quantum immortality. 06:43: Max Tegmark makes a good point regarding quantum immortality - which is that death is an incremental process, not a single quantum event. 07:19: ... Many Worlds might be wrong - I say live as though this is your one quantum timeline While we’re discussing dubious methods for predicting survival ... 10:45: ... tried to make sure all correct answers got a prize in at least one quantum timeline - so if you didn’t see your name here, please congratulate the ... 11:51: ... to address both our episodes on the role of conscious observation in quantum mechanics and on quantum decoherence as a better path to understanding ... 12:55: ... won't see multiple outcomes at the same time - you don't see macroscopic quantum ... 13:12: We're going to explore this in much more detail next week, when we look at the role of quantum entanglement in decoherence. 13:20: eddybox on the spacetime discord asked about the quantum eraser, as did several people in the comments. 13:33: ... answer is essentially yes - in a typical quantum eraser experiment you use entangled photon or other particle pairs - one ... 13:59: ... in the quantum eraser, we haven't reached true decoherence - relative phase information ... 14:10: ... exact mechanism varies by quantum eraser experiment, but this is true even in the infamous delayed choice ... 15:44: ... channel is pleased that we share his annoyance at horrible missuse of quantum mechanics to promote pseudoscientific ... 15:55: As Nick says, "Quantum mechanics is not magic!". 16:11: ... taking advantage of that fact - whether to sell snake oil, or books on quantum healing, or $80 crystal infused water ... 16:41: ... that a more interesting question than does consciousness influcence quantum mechanics is the other way around: "Does quantum mechanics influence ... 16:54: Despite my fascination with the subject, I've dosed off in MANY quantum mechanics lectures. 17:00: Quantum UNconsciousness achieved. 11:51: ... on the role of conscious observation in quantum mechanics and on quantum decoherence as a better path to understanding the measurement ... 13:12: We're going to explore this in much more detail next week, when we look at the role of quantum entanglement in decoherence. 13:20: eddybox on the spacetime discord asked about the quantum eraser, as did several people in the comments. 13:33: ... answer is essentially yes - in a typical quantum eraser experiment you use entangled photon or other particle pairs - one of the ... 13:59: ... in the quantum eraser, we haven't reached true decoherence - relative phase information is ... 14:10: ... exact mechanism varies by quantum eraser experiment, but this is true even in the infamous delayed choice quantum ... 13:33: ... answer is essentially yes - in a typical quantum eraser experiment you use entangled photon or other particle pairs - one of the pairs goes ... 14:10: ... exact mechanism varies by quantum eraser experiment, but this is true even in the infamous delayed choice quantum eraser, ... 04:33: ... which tells us that there’s ultimately only a single result from each quantum event, so a single result from the “Schrodinger’s physicist” ... 06:43: Max Tegmark makes a good point regarding quantum immortality - which is that death is an incremental process, not a single quantum event. 06:04: ... that any process leading to mortality is ultimately a sequence of quantum events - so there are timelines in which those incremental steps towards death ... 16:11: ... taking advantage of that fact - whether to sell snake oil, or books on quantum healing, or $80 crystal infused water ... 02:17: We’ll call this test quantum immortality. 05:59: This thought experiment is sometimes called quantum immortality. 06:25: Hugh Everett, who first came up with the many Worlds interpretation, actually believed in this sort of quantum immortality. 06:43: Max Tegmark makes a good point regarding quantum immortality - which is that death is an incremental process, not a single quantum event. 00:22: In the last couple of episodes we’ve been delving into a key mystery of quantum mechanics - why don’t we have quantum magical powers? 01:18: ... in one of them, we need to embrace one of the interpretations of quantum mechanics. ... 05:21: ... is right because the chance survival under any other interpretation of quantum mechanics is basically ... 11:51: ... to address both our episodes on the role of conscious observation in quantum mechanics and on quantum decoherence as a better path to understanding the ... 15:44: ... channel is pleased that we share his annoyance at horrible missuse of quantum mechanics to promote pseudoscientific ... 15:55: As Nick says, "Quantum mechanics is not magic!". 16:41: ... that a more interesting question than does consciousness influcence quantum mechanics is the other way around: "Does quantum mechanics influence ... 16:54: Despite my fascination with the subject, I've dosed off in MANY quantum mechanics lectures. 00:22: In the last couple of episodes we’ve been delving into a key mystery of quantum mechanics - why don’t we have quantum magical powers? 16:41: ... influcence quantum mechanics is the other way around: "Does quantum mechanics influence ... 16:54: Despite my fascination with the subject, I've dosed off in MANY quantum mechanics lectures. 00:11: If the quantum multiverse is real there may be a version of you that lives forever. 12:55: ... won't see multiple outcomes at the same time - you don't see macroscopic quantum superposition. ... 00:39: ... particular, what causes quantum systems to transition from simultaneously existing in many states at the same ... 07:19: ... Many Worlds might be wrong - I say live as though this is your one quantum timeline While we’re discussing dubious methods for predicting survival times - I ... 10:45: ... tried to make sure all correct answers got a prize in at least one quantum timeline - so if you didn’t see your name here, please congratulate the other you ... 17:00: Quantum UNconsciousness achieved. 02:33: ... of the radioactive decay over a certain period of time - that means the quantum wavefunction of the atom splits equally - the atom is simultaneously decayed and not ... 05:31: Many Worlds, on the other hand, guarantees their survival in at least one branch of the quantum wavefunction. 00:53: We’ve been exploring decoherence as a mechanism for this quantum-classical transition - and we’re not done yet. 10:59: I have a feeling it’s going to be a hell of a ride, even if we’re not a quantum-immortal in branch.
	2020-02-24: How Decoherence Splits The Quantum Multiverse 00:00: On the quantum scale, we can see these multiple histories play out and even talk to each other. 00:11: Many physicists believe that the answer lies in a process known as quantum decoherence. 00:29: Sure - but it’s also the elusive dividing line between the quantum and classical worlds. 00:35: ... the measurement problem - the question of why and where the blurry quantum wavefunction collapses into well-defined measurement ... 00:48: We focused on a simple question: does conscious observation of a quantum system cause the wavefunction to collapse? 01:25: ... why is it that we can see these multiple histories play out on the quantum scale, and why do lose sight of them on our macroscopic ... 01:36: Many physicists believe that the answer lies in quantum decoherence. 01:41: ... Quantum decoherence is a deep and developing subject, and today we’re going to ... 01:52: ... quantum systems are described by this wavefunction thing - it’s the mathematical ... 02:20: Over time the histories of a quantum system separate to represent every possible future the laws of physics allow. 02:44: This fact is also reflected in Richard Feynman’s path integral formulation of quantum mechanics. 03:33: The best way to illustrate quantum coherence is with the good ol’ double-slit experiment. 03:38: ... you remember it from last week - a quantum particle seems to pass through two slits simultaneously as a probability ... 04:04: This time we'll use particles of light - photons as our quantum particle. 06:53: And this is one of the weird, multiple history aspects of quantum mechanics that we can directly observe. 07:03: These also have a known phase relation, so they have quantum coherence relative to each other. 07:09: ... potentially bring those branches back together again to produce the same quantum state - for example by cutting slits in the second screen and producing ... 09:54: We can think about the photon wavefunction becoming mixed with the wavefunctions of the quantum particles along this chain. 12:59: ... order to do quantum experiments we need to isolate a slice of the global wavefunction and ... 13:34: That includes yourself and your measuring device, unless you know the exact quantum state of all of the particles of both. 13:55: There’s a lot more to discuss - including the connection to quantum entanglement and to entropy. 14:19: ... argue that it does - in the context of the Many Worlds interpretation of quantum mechanics, in which there is no wavefunction collapses at ... 03:33: The best way to illustrate quantum coherence is with the good ol’ double-slit experiment. 07:03: These also have a known phase relation, so they have quantum coherence relative to each other. 00:11: Many physicists believe that the answer lies in a process known as quantum decoherence. 01:36: Many physicists believe that the answer lies in quantum decoherence. 01:41: ... Quantum decoherence is a deep and developing subject, and today we’re going to dip our toes ... 13:55: There’s a lot more to discuss - including the connection to quantum entanglement and to entropy. 12:59: ... order to do quantum experiments we need to isolate a slice of the global wavefunction and maintain its ... 02:44: This fact is also reflected in Richard Feynman’s path integral formulation of quantum mechanics. 06:53: And this is one of the weird, multiple history aspects of quantum mechanics that we can directly observe. 14:19: ... argue that it does - in the context of the Many Worlds interpretation of quantum mechanics, in which there is no wavefunction collapses at ... 03:38: ... you remember it from last week - a quantum particle seems to pass through two slits simultaneously as a probability wave ... 04:04: This time we'll use particles of light - photons as our quantum particle. 09:54: We can think about the photon wavefunction becoming mixed with the wavefunctions of the quantum particles along this chain. 00:00: On the quantum scale, we can see these multiple histories play out and even talk to each other. 01:25: ... why is it that we can see these multiple histories play out on the quantum scale, and why do lose sight of them on our macroscopic ... 07:09: ... potentially bring those branches back together again to produce the same quantum state - for example by cutting slits in the second screen and producing an ... 13:34: That includes yourself and your measuring device, unless you know the exact quantum state of all of the particles of both. 07:09: ... potentially bring those branches back together again to produce the same quantum state - for example by cutting slits in the second screen and producing an ... 01:52: ... quantum systems are described by this wavefunction thing - it’s the mathematical object ... 00:35: ... the measurement problem - the question of why and where the blurry quantum wavefunction collapses into well-defined measurement ...
	2020-02-18: Does Consciousness Influence Quantum Mechanics? 00:00: If I focus really hard do my power of quantum mechanics allow me to manifest reality? 00:08: No, but then why did some of the founders of the theory seem to think that consciousness and quantum mechanics were inextricably linked. 00:22: The behavior of the quantum world is beyond weird. 00:36: The rules governing the tiny quantum world of atoms and photons seem alien. 00:41: ... set of rules that give us incredible power in predicting the behavior of quantum system - rules encapsulated in the mathematics of quantum ... 00:52: ... its stunning success, we are now nearly a century past the foundation of quantum mechanics and physicists are still debating how to interpret its ... 01:04: ... not surprising that the profound weirdness of the quantum world has inspired some outlandish explanations - nor that these ... 01:18: One particularly pervasive notion is the idea that consciousness can directly influence quantum systems - and so influence reality. 01:25: Today we’re going to see where this idea comes from, and whether quantum theory really supports it. 01:32: ... we're going to need to go back to one of the earliest interpretations of quantum mechanics - the Copenhagen interpretation, often associated with Neils ... 03:45: So when does the quantum transition to the classical actually happen? 04:59: The first electron to become excited in the detector is also a quantum object. 05:34: But all of these things are made of atoms - the “von Neumann chain” from detector to mind is a chain of quantum objects. 05:42: With no clear boundary between the quantum and the classical, where does the collapse of the wavefunction happen? 06:01: Another of the greats of early quantum theory agreed with him. 06:44: ... step in our von Neumann chain - before it the information about this quantum experiment reaches your conscious awareness, it has to pass through your ... 07:04: From your perspective, your friend’s entire brain exists in a quantum superposition of all possible results of the experiment. 08:49: With the greats of quantum physics inclined to speak in mystical terms, it’s not surprising that the idea stuck around. 08:56: ... Wu Li Masters drew parallels between eastern mystical traditions and quantum physics - which on its surface seems like a nice idea - poetic ... 09:40: ... as Richard Feynman said, "If you think you understand quantum mechanics, you don't understand quantum mechanics." The more you know ... 09:56: And yet the most confident claims about quantum mechanics seem to be the mystical ones. 10:21: The weird behavior of the quantum world demanded the courageous and open-minded speculation that characterizes a great scientist. 12:00: ... universal wavefunction - but that’s not going to give you any powers of quantum ... 12:09: ... the Measurement Problem - at least not with full consensus, modern quantum theory has come a very, very long way since its ... 12:44: We need to learn about quantum decoherence and the quantum multiverse. 15:01: ... and Francisco Martinez asked whether we would get new quantum fields and new particles if other fundamental constants turned out to ... 15:25: Would it be a quantum field with particles? 15:49: ... constant are just scaling factors and so varying them shouldn't lead to quantum particles - but perhaps other constants could give us a ... 12:44: We need to learn about quantum decoherence and the quantum multiverse. 06:44: ... step in our von Neumann chain - before it the information about this quantum experiment reaches your conscious awareness, it has to pass through your friend’s ... 15:25: Would it be a quantum field with particles? 15:01: ... and Francisco Martinez asked whether we would get new quantum fields and new particles if other fundamental constants turned out to vary over ... 00:00: If I focus really hard do my power of quantum mechanics allow me to manifest reality? 00:08: No, but then why did some of the founders of the theory seem to think that consciousness and quantum mechanics were inextricably linked. 00:41: ... behavior of quantum system - rules encapsulated in the mathematics of quantum mechanics. ... 00:52: ... its stunning success, we are now nearly a century past the foundation of quantum mechanics and physicists are still debating how to interpret its equations and the ... 01:32: ... we're going to need to go back to one of the earliest interpretations of quantum mechanics - the Copenhagen interpretation, often associated with Neils Bohr and ... 09:40: ... as Richard Feynman said, "If you think you understand quantum mechanics, you don't understand quantum mechanics." The more you know about this ... 09:56: And yet the most confident claims about quantum mechanics seem to be the mystical ones. 01:32: ... we're going to need to go back to one of the earliest interpretations of quantum mechanics - the Copenhagen interpretation, often associated with Neils Bohr and ... 12:44: We need to learn about quantum decoherence and the quantum multiverse. 04:59: The first electron to become excited in the detector is also a quantum object. 05:34: But all of these things are made of atoms - the “von Neumann chain” from detector to mind is a chain of quantum objects. 15:49: ... constant are just scaling factors and so varying them shouldn't lead to quantum particles - but perhaps other constants could give us a ... 08:49: With the greats of quantum physics inclined to speak in mystical terms, it’s not surprising that the idea stuck around. 08:56: ... Wu Li Masters drew parallels between eastern mystical traditions and quantum physics - which on its surface seems like a nice idea - poetic descriptions of ... 08:49: With the greats of quantum physics inclined to speak in mystical terms, it’s not surprising that the idea stuck around. 07:04: From your perspective, your friend’s entire brain exists in a quantum superposition of all possible results of the experiment. 01:18: One particularly pervasive notion is the idea that consciousness can directly influence quantum systems - and so influence reality. 01:25: Today we’re going to see where this idea comes from, and whether quantum theory really supports it. 06:01: Another of the greats of early quantum theory agreed with him. 12:09: ... the Measurement Problem - at least not with full consensus, modern quantum theory has come a very, very long way since its ... 06:01: Another of the greats of early quantum theory agreed with him. 03:45: So when does the quantum transition to the classical actually happen? 12:00: ... universal wavefunction - but that’s not going to give you any powers of quantum wishing. ... 12:49: ... is that your own future wavefunction includes a deeper dive into the quantum-classical divide, on an upcoming episode of Space ...
	2020-02-11: Are Axions Dark Matter? 02:35: ... best theoretical description of the strong force is quantum chromodynamics - QCD. That’s a deep and rich subject that will get its ... 03:42: ... before we can see how that happens, we need to understand why quantum chromodynamics predicts a CP violation in the first place. Compared to ... 03:59: ... You might ask how can a vacuum, aka “nothing” have structure? Well, in quantum field theories, the vacuum isn’t really nothing. “Vacuum” is the word we ... 04:33: ... between these different states. But because they're all the same energy, quantum weirdness allows the QCD vacuum to sort of simultaneously occupy all of ... 06:32: ... and so this solution is not generally accepted - turning theta into a quantum field is the most promising ... 06:54: ... you might recall that in quantum field theory a particle is just an oscillation in a quantum field. So ... 02:35: ... best theoretical description of the strong force is quantum chromodynamics - QCD. That’s a deep and rich subject that will get its own episode ... 03:42: ... before we can see how that happens, we need to understand why quantum chromodynamics predicts a CP violation in the first place. Compared to quantum ... 02:35: ... best theoretical description of the strong force is quantum chromodynamics - QCD. That’s a deep and rich subject that will get its own episode before ... 03:42: ... before we can see how that happens, we need to understand why quantum chromodynamics predicts a CP violation in the first place. Compared to quantum electrodynamics, ... 03:59: ... You might ask how can a vacuum, aka “nothing” have structure? Well, in quantum field theories, the vacuum isn’t really nothing. “Vacuum” is the word we use ... 04:33: ... but one way to describe it is that it’s a phase offset picked up by the quantum field as it moves between the different possible minimum energy states of the ... 06:32: ... and so this solution is not generally accepted - turning theta into a quantum field is the most promising ... 06:54: ... you might recall that in quantum field theory a particle is just an oscillation in a quantum field. So with a ... 03:59: ... You might ask how can a vacuum, aka “nothing” have structure? Well, in quantum field theories, the vacuum isn’t really nothing. “Vacuum” is the word we use to describe ... 06:54: ... you might recall that in quantum field theory a particle is just an oscillation in a quantum field. So with a new ... 04:33: ... between these different states. But because they're all the same energy, quantum weirdness allows the QCD vacuum to sort of simultaneously occupy all of those ...
	2020-02-03: Are there Infinite Versions of You? 03:38: The properties of each region are effectively random - set in the beginning of the universe by quantum processes. 06:08: It means that every particle, or chunk of quantum field, or whatever elementary pixel of reality - has matching properties between the two regions. 08:40: For example, you could argue that fundamental quantum randomness will cause even identical starting configurations to produce different results. 09:00: In fact, quantum randomness could allow different starting conditions to evolve into a universe that looks like this one. 12:19: ... first up we got the three-body problem and then we'll do our episode on quantum hacking with the s-matrix ... 14:48: But in s-matrix theory and quantum field theory, time and space in the interaction region are fuzzy. 16:21: ... depiction of the proton being made of lego bricks as a viable theory - quantum lego dynamics, as Steve Plegge puts ... 06:08: It means that every particle, or chunk of quantum field, or whatever elementary pixel of reality - has matching properties between the two regions. 14:48: But in s-matrix theory and quantum field theory, time and space in the interaction region are fuzzy. 12:19: ... first up we got the three-body problem and then we'll do our episode on quantum hacking with the s-matrix ... 16:21: ... depiction of the proton being made of lego bricks as a viable theory - quantum lego dynamics, as Steve Plegge puts ... 03:38: The properties of each region are effectively random - set in the beginning of the universe by quantum processes. 08:40: For example, you could argue that fundamental quantum randomness will cause even identical starting configurations to produce different results. 09:00: In fact, quantum randomness could allow different starting conditions to evolve into a universe that looks like this one.
	2020-01-27: Hacking the Nature of Reality 00:54: ... mathematical insights, with the final result being the birth of modern quantum theory and first complete formulation of quantum mechanics - matrix ... 01:08: ... representations of quantum mechanics soon followed - for example, the wave mechanics driven by the ... 01:53: ... its importance in the foundation of quantum mechanics, and being championed by Bohr and Heisenberg, most physicists ... 02:16: ... search for the underlying clockwork of reality led to quantum field theory, in which all particles are described by vibrations in ... 02:41: Early quantum theory was plagued by problems - for example, how do you compute infinite interactions? 02:55: ... tame the infinities and yielded the incredibly accurate predictions of quantum electrodynamics, which describes the interactions of the electromagnetic ... 03:14: At the beginning of the 1960s the atom was understood as fuzzy, quantum electron orbits surrounding a nucleus of protons and neutrons. 04:55: The idea was invented by John Archibald Wheeler in the late 30s as a convenient way to express the possible results of a quantum interaction. 05:03: In fact, it's still a very important tool in quantum mechanics today. 06:47: Remember, that quantum field theory fastidiously adds together a complete set of virtual interactions that contribute to the real interaction. 07:12: ... include things like conservation of energy and momentum, the behavior of quantum properties like spin, and the assumption of a family of particles that ... 08:28: In regular quantum field theory you’d need to add up all the different versions of both these two channels separately. 09:11: ... S-matrix approach to solving problems in quantum mechanics based on these global consistency conditions and taking ... 09:35: It presented severe challenges on par with those plaguing quantum field theory - and, as it happened, physicists solved the QFT challenges first. 09:45: ... actually approach infinite strength as was once feared, and so a full quantum field theoretic description of the strong nuclear force was possible ... 10:01: The result is quantum chromodynamics - our modern description of sub-nuclear physics. 10:10: ... the results was that S-matrix theory was sidelined, and quantum field theory reigns supreme to this day as our reductionist description ... 10:41: Quantum field theories like QCD surely gives us insights into the nature of the fundamental workings of the universe. 10:47: ... theory - but it turns out that it has led to deep insights that even quantum field theories could not ... 11:35: ... - at first as a description of strong nuclear force interactions before quantum chromodynamics took over - but then as a theory of quantum ... 12:13: ... in the universe today - galaxies and galaxy clusters - as collapsed from quantum fluctuations in the extremely early ... 12:56: ... the amplituhedron doesn’t just eliminate the fiddly mechanics of quantum field theory, it removes the very concepts of space and ... 13:17: ... ourselves up by our bootstraps towards a better understanding of the quantum weirdness of space ... 10:01: The result is quantum chromodynamics - our modern description of sub-nuclear physics. 11:35: ... - at first as a description of strong nuclear force interactions before quantum chromodynamics took over - but then as a theory of quantum ... 10:01: The result is quantum chromodynamics - our modern description of sub-nuclear physics. 02:55: ... tame the infinities and yielded the incredibly accurate predictions of quantum electrodynamics, which describes the interactions of the electromagnetic ... 03:14: At the beginning of the 1960s the atom was understood as fuzzy, quantum electron orbits surrounding a nucleus of protons and neutrons. 02:16: ... search for the underlying clockwork of reality led to quantum field theory, in which all particles are described by vibrations in elementary ... 06:47: Remember, that quantum field theory fastidiously adds together a complete set of virtual interactions that contribute to the real interaction. 08:28: In regular quantum field theory you’d need to add up all the different versions of both these two channels separately. 09:35: It presented severe challenges on par with those plaguing quantum field theory - and, as it happened, physicists solved the QFT challenges first. 09:45: ... actually approach infinite strength as was once feared, and so a full quantum field theoretic description of the strong nuclear force was possible after ... 10:10: ... the results was that S-matrix theory was sidelined, and quantum field theory reigns supreme to this day as our reductionist description of the ... 10:41: Quantum field theories like QCD surely gives us insights into the nature of the fundamental workings of the universe. 10:47: ... theory - but it turns out that it has led to deep insights that even quantum field theories could not ... 12:56: ... the amplituhedron doesn’t just eliminate the fiddly mechanics of quantum field theory, it removes the very concepts of space and ... 09:45: ... actually approach infinite strength as was once feared, and so a full quantum field theoretic description of the strong nuclear force was possible after ... 10:41: Quantum field theories like QCD surely gives us insights into the nature of the fundamental workings of the universe. 10:47: ... theory - but it turns out that it has led to deep insights that even quantum field theories could not ... 02:16: ... search for the underlying clockwork of reality led to quantum field theory, in which all particles are described by vibrations in elementary fields ... 06:47: Remember, that quantum field theory fastidiously adds together a complete set of virtual interactions that contribute to the real interaction. 08:28: In regular quantum field theory you’d need to add up all the different versions of both these two channels separately. 09:35: It presented severe challenges on par with those plaguing quantum field theory - and, as it happened, physicists solved the QFT challenges first. 10:10: ... the results was that S-matrix theory was sidelined, and quantum field theory reigns supreme to this day as our reductionist description of the ... 12:56: ... the amplituhedron doesn’t just eliminate the fiddly mechanics of quantum field theory, it removes the very concepts of space and ... 12:13: ... in the universe today - galaxies and galaxy clusters - as collapsed from quantum fluctuations in the extremely early ... 11:35: ... before quantum chromodynamics took over - but then as a theory of quantum gravity. ... 04:55: The idea was invented by John Archibald Wheeler in the late 30s as a convenient way to express the possible results of a quantum interaction. 00:54: ... the birth of modern quantum theory and first complete formulation of quantum mechanics - matrix ... 01:08: ... representations of quantum mechanics soon followed - for example, the wave mechanics driven by the ... 01:53: ... its importance in the foundation of quantum mechanics, and being championed by Bohr and Heisenberg, most physicists over the ... 05:03: In fact, it's still a very important tool in quantum mechanics today. 09:11: ... S-matrix approach to solving problems in quantum mechanics based on these global consistency conditions and taking advantage of ... 00:54: ... the birth of modern quantum theory and first complete formulation of quantum mechanics - matrix ... 09:11: ... S-matrix approach to solving problems in quantum mechanics based on these global consistency conditions and taking advantage of ... 05:03: In fact, it's still a very important tool in quantum mechanics today. 07:12: ... include things like conservation of energy and momentum, the behavior of quantum properties like spin, and the assumption of a family of particles that can be ... 01:08: ... equation and Paul Dirac’s notation representing evolution in a space of quantum states. ... 00:54: ... mathematical insights, with the final result being the birth of modern quantum theory and first complete formulation of quantum mechanics - matrix ... 02:41: Early quantum theory was plagued by problems - for example, how do you compute infinite interactions? 13:17: ... ourselves up by our bootstraps towards a better understanding of the quantum weirdness of space ...
	2020-01-13: How To Capture Black Holes 12:17: ... ridiculously large universe that multiplies the density of a high-energy quantum field powering inflation. Check out our episodes on cosmic inflation to ...
	2019-12-17: Do Black Holes Create New Universes? 03:48: The details of how this happens is presumably buried in the as-yet-unknown theory of quantum gravity. 07:16: ... proposed that if a universe lasts forever then in the distant future, quantum fluctuations of that near vacuum will cause black holes to spontaneously ... 07:38: ... by the biggest universes - more space means more chances for these quantum ... 07:56: ... be extrapolated to the insanely long timescales required for these quantum fluctuations to ... 07:16: ... proposed that if a universe lasts forever then in the distant future, quantum fluctuations of that near vacuum will cause black holes to spontaneously appear - and ... 07:38: ... by the biggest universes - more space means more chances for these quantum fluctuations. ... 07:56: ... be extrapolated to the insanely long timescales required for these quantum fluctuations to ... 03:48: The details of how this happens is presumably buried in the as-yet-unknown theory of quantum gravity.
	2019-12-09: The Doomsday Argument 01:57: ... 120 orders of magnitude higher according to the crudest predictions of quantum field ... 13:11: ... the future of humanity, the nature of space and time, the weirdness of quantum mechanics - you name ... 01:57: ... 120 orders of magnitude higher according to the crudest predictions of quantum field ... 13:11: ... the future of humanity, the nature of space and time, the weirdness of quantum mechanics - you name ...
	2019-12-02: Is The Universe Finite? 12:12: If you want to dive deeply into understanding the building blocks of space time then you need to study quantum theory. 12:18: Brillaint.org has a fun course called quantum objects that include interactive challenges and problems to solve. 12:25: Honestly, the best way to wrap your head around quantum theory is to play with it. 12:30: ... this course you can explore the experiments of quantum mechanics and use them to construct equations of motion, laws of ... 12:18: Brillaint.org has a fun course called quantum objects that include interactive challenges and problems to solve. 12:12: If you want to dive deeply into understanding the building blocks of space time then you need to study quantum theory. 12:25: Honestly, the best way to wrap your head around quantum theory is to play with it. 12:30: ... laws of physics, and systems of measurement based on the algebra of quantum theory. ...
	2019-11-11: Does Life Need a Multiverse to Exist? 09:04: ... quantum fields, which fill all of space and whose oscillations produce the ... 09:16: ... with themselves even when there are no particles around, resulting in a quantum buzz of energy everywhere in the universe that would accelerate its ... 10:02: One possibility is that the zero-point energies of unknown quantum fields cancel out the known contributions. 09:16: ... with themselves even when there are no particles around, resulting in a quantum buzz of energy everywhere in the universe that would accelerate its ... 09:04: ... quantum fields, which fill all of space and whose oscillations produce the familiar ... 10:02: One possibility is that the zero-point energies of unknown quantum fields cancel out the known contributions.
	2019-11-04: Why We Might Be Alone in the Universe 12:21: We skipped comment responses last episode, so today we're covering two episodes - loop quantum gravity and time travel. 12:30: A few of you wondered if there's a connection between the loops of loop quantum gravity and the closed strings of string theory. 12:52: Which brings us to the most common question - what actually ARE the loops of loop quantum gravity? 13:37: ... Receiver asked about the experiment to test Loop Quantum Gravity So LQG predicts that light of different wavelengths travels at ... 14:00: ... the very shortest wavelengths of light to be slightly perturbed by these quantum cells of space - sort of like traveling through cracked glass - they ... 14:15: Wavelengths longer than this quantum scale can ignore this fragmentation and so travel at normal speed. 15:16: Surely as time travelers you could have reminded me in the loop quantum gravity comments the week before. 14:00: ... the very shortest wavelengths of light to be slightly perturbed by these quantum cells of space - sort of like traveling through cracked glass - they interact ... 12:21: We skipped comment responses last episode, so today we're covering two episodes - loop quantum gravity and time travel. 12:30: A few of you wondered if there's a connection between the loops of loop quantum gravity and the closed strings of string theory. 12:52: Which brings us to the most common question - what actually ARE the loops of loop quantum gravity? 13:37: ... Receiver asked about the experiment to test Loop Quantum Gravity So LQG predicts that light of different wavelengths travels at very ... 15:16: Surely as time travelers you could have reminded me in the loop quantum gravity comments the week before. 14:15: Wavelengths longer than this quantum scale can ignore this fragmentation and so travel at normal speed. 13:17: But that doesn't mean the loops are physical, they're just a way to parameterize the quantum-scale geometry of space.
	2019-10-21: Is Time Travel Impossible? 10:54: ... alternative lies in Hugh Everett’s many-worlds interpretation of quantum mechanics, in which every possible universe exists, splitting off in an ... 11:17: ... be one fundamental law of physics that prohibits it - for example, the quantum vacuum may be unstable in the infinitely iterating loops of a closed ... 11:36: ... actual fact we can’t know until we have a full theory of quantum gravity – until then we’re working with the approximate theories general ... 10:54: ... alternative lies in Hugh Everett’s many-worlds interpretation of quantum mechanics, in which every possible universe exists, splitting off in an infinite ... 11:36: ... then we’re working with the approximate theories general relativity and quantum theory. ... 11:17: ... be one fundamental law of physics that prohibits it - for example, the quantum vacuum may be unstable in the infinitely iterating loops of a closed timelike ...
	2019-10-15: Loop Quantum Gravity Explained 00:00: It’s time we talked about loop quantum gravity. 00:28: To connect quantum physics with Einstein’s general theory of relativity. 00:32: ... search for a theory of quantum gravity is a century old, and we’ve talked about it quite a bit already, ... 00:47: ... the physics of the tiny and the gigantic - another way to a theory of quantum gravity that avoids a lot of conceptual baggage like tiny wiggling ... 01:03: That other way would be loop quantum gravity, and today we’re going to find out exactly what it is. 01:09: Back in the day we talked about why combining quantum mechanics with general relativity was so hard. 01:16: ... example, there’s the fact that general relativity - or perhaps quantum mechanics breaks down when we think about the extreme densities of the ... 01:34: ... thing because this is what really inspired the invention of loop quantum ... 01:46: ... Quantum mechanics, and indeed most theories in physics, involve a set of ... 02:06: In quantum mechanics that stage is flat and static and isn’t influenced by the actors. 02:11: It requires some giant hacks to even attempt regular quantum calculations in a non-flat geometry. 02:18: In short: quantum mechanics is NOT background independent. 03:10: ... quantum gravity tries to quantize general relativity with no strings attached, ... 03:24: The challenge really gets us to the fundamentals of what a quantum theory actually is. 03:30: So just quickly, let’s review all of quantum mechanics. 03:50: But in quantum mechanics, things aren’t so straightforward. 04:06: In the first formulations of quantum mechanics, that wavefunction describes the distribution of possible positions and momenta of, say, a particle. 04:30: ... all, the position and momentum of quantum mechanics literally describes location on a spatial coordinate system ... 04:43: There are other ways to formulate quantum mechanics, like quantum field theory, but these ultimately have the same issue But it gets worse actually. 04:51: In quantum mechanics, time is treated completely separately to other variables - there is no “time wavefunction” or “time operator”. 05:13: A quantum theory of gravity needs to fix both of these issues - but we’re going to focus on background independence for now. 05:19: ... equations of quantum mechanics let you calculate changing properties of a particle- - like ... 05:35: So maybe instead of thinking about the quantum fuzziness of position and momentum we can think about the quantum fuzziness of the metric itself. 05:45: ... instead of an equation that describes the quantum evolution of the properties of an object in spacetime, maybe there’s an ... 06:43: So the Wheeler-deWitt equation quantizes these - turns them into quantum operators. 06:48: The result is a quantum equation for the fabric of space. 06:52: A contender for a theory of quantum gravity. 07:16: ... what loop quantum gravity does - it takes us down the abstraction rabbit hole - past our ... 08:20: ... something called a spinor - a vector-like thing that also represents a quantum of angular momentum - or ... 08:47: In this formalism, the “space of metrics” looks just like a space of fields in quantum field theory. 08:59: And now we get to the loops of loop quantum gravity. 10:01: The result, of course, is loop quantum gravity. 10:10: Not with chunks of spacetime but with quantum circuits of gravitational field. 11:01: ... big success of loop quantum gravity is that it manages to combine general relativity and quantum ... 12:41: ... quantum gravity seems to predict that the speed of light should depend very ... 13:10: If there was any difference it was barely measurable, and that doesn't look great for loop quantum gravity. 13:16: Loop quantum gravity is an intriguing alternative to the more popular string theory. 13:58: David, we already spent all of your money ... on aspirin, after loop quantum gravity broke our brains. 02:11: It requires some giant hacks to even attempt regular quantum calculations in a non-flat geometry. 10:10: Not with chunks of spacetime but with quantum circuits of gravitational field. 06:48: The result is a quantum equation for the fabric of space. 05:45: ... instead of an equation that describes the quantum evolution of the properties of an object in spacetime, maybe there’s an equation ... 04:43: There are other ways to formulate quantum mechanics, like quantum field theory, but these ultimately have the same issue But it gets worse actually. 08:47: In this formalism, the “space of metrics” looks just like a space of fields in quantum field theory. 04:43: There are other ways to formulate quantum mechanics, like quantum field theory, but these ultimately have the same issue But it gets worse actually. 08:47: In this formalism, the “space of metrics” looks just like a space of fields in quantum field theory. 05:35: So maybe instead of thinking about the quantum fuzziness of position and momentum we can think about the quantum fuzziness of the metric itself. 00:00: It’s time we talked about loop quantum gravity. 00:32: ... search for a theory of quantum gravity is a century old, and we’ve talked about it quite a bit already, ... 00:47: ... the physics of the tiny and the gigantic - another way to a theory of quantum gravity that avoids a lot of conceptual baggage like tiny wiggling strings made ... 01:03: That other way would be loop quantum gravity, and today we’re going to find out exactly what it is. 01:34: ... thing because this is what really inspired the invention of loop quantum gravity. ... 03:10: ... quantum gravity tries to quantize general relativity with no strings attached, while ... 06:52: A contender for a theory of quantum gravity. 07:16: ... what loop quantum gravity does - it takes us down the abstraction rabbit hole - past our space of ... 08:59: And now we get to the loops of loop quantum gravity. 10:01: The result, of course, is loop quantum gravity. 11:01: ... big success of loop quantum gravity is that it manages to combine general relativity and quantum mechanics ... 12:41: ... quantum gravity seems to predict that the speed of light should depend very slightly on ... 13:10: If there was any difference it was barely measurable, and that doesn't look great for loop quantum gravity. 13:16: Loop quantum gravity is an intriguing alternative to the more popular string theory. 13:58: David, we already spent all of your money ... on aspirin, after loop quantum gravity broke our brains. 12:41: ... waves due to the way they propagate through the graininess of a loop quantum gravity spacetime. ... 01:09: Back in the day we talked about why combining quantum mechanics with general relativity was so hard. 01:16: ... example, there’s the fact that general relativity - or perhaps quantum mechanics breaks down when we think about the extreme densities of the black hole ... 01:46: ... Quantum mechanics, and indeed most theories in physics, involve a set of equations ... 02:06: In quantum mechanics that stage is flat and static and isn’t influenced by the actors. 02:18: In short: quantum mechanics is NOT background independent. 03:30: So just quickly, let’s review all of quantum mechanics. 03:50: But in quantum mechanics, things aren’t so straightforward. 04:06: In the first formulations of quantum mechanics, that wavefunction describes the distribution of possible positions and momenta of, say, a particle. 04:30: ... all, the position and momentum of quantum mechanics literally describes location on a spatial coordinate system and the ... 04:43: There are other ways to formulate quantum mechanics, like quantum field theory, but these ultimately have the same issue But it gets worse actually. 04:51: In quantum mechanics, time is treated completely separately to other variables - there is no “time wavefunction” or “time operator”. 05:19: ... equations of quantum mechanics let you calculate changing properties of a particle- - like its position ... 11:01: ... quantum gravity is that it manages to combine general relativity and quantum mechanics in their currently accepted forms, without taking away their most ... 01:16: ... example, there’s the fact that general relativity - or perhaps quantum mechanics breaks down when we think about the extreme densities of the black hole or the ... 04:30: ... all, the position and momentum of quantum mechanics literally describes location on a spatial coordinate system and the change in that ... 03:50: But in quantum mechanics, things aren’t so straightforward. 04:51: In quantum mechanics, time is treated completely separately to other variables - there is no “time wavefunction” or “time operator”. 06:43: So the Wheeler-deWitt equation quantizes these - turns them into quantum operators. 00:28: To connect quantum physics with Einstein’s general theory of relativity. 03:24: The challenge really gets us to the fundamentals of what a quantum theory actually is. 05:13: A quantum theory of gravity needs to fix both of these issues - but we’re going to focus on background independence for now.
	2019-09-16: Could We Terraform Mars? 16:31: This is the simplest type of quantum field, consisting of only a single scalar value at all points in space.
	2019-08-19: What Happened Before the Big Bang? 02:17: This is actually the simplest type of quantum field because it's described by a single number, a scalar everywhere in space. 02:50: I mentioned last time that quantum fields can hold energy without actually having particles. 05:07: But it wouldn't end as a random process, it wouldn't require quantum tunneling to get started. 06:49: I mentioned that quantum fields fluctuate due to the intrinsic randomness of the quantum world. 07:53: But seeding all of the structure in our universe is probably the least impressive thing those quantum fluctuations did. 08:06: ... differences in when the inflation ends from one point to the next But quantum fluctuations come in all sizes and a rare strong fluctuation would force ... 09:34: Assuming a quantum field of the right type and that speck will start inflating. 02:17: This is actually the simplest type of quantum field because it's described by a single number, a scalar everywhere in space. 09:34: Assuming a quantum field of the right type and that speck will start inflating. 02:50: I mentioned last time that quantum fields can hold energy without actually having particles. 06:49: I mentioned that quantum fields fluctuate due to the intrinsic randomness of the quantum world. 07:53: But seeding all of the structure in our universe is probably the least impressive thing those quantum fluctuations did. 08:06: ... differences in when the inflation ends from one point to the next But quantum fluctuations come in all sizes and a rare strong fluctuation would force the inflaton ... 05:07: But it wouldn't end as a random process, it wouldn't require quantum tunneling to get started.
	2019-08-06: What Caused the Big Bang? 02:14: In the case of inflation part of the appeal is that it fits extremely nicely into our modern understanding of gravity and quantum mechanics. 04:42: We need some quantum physics. In fact, we need some quantum field theory. 04:55: There's some more homework for you. For now, a review: the universe is filled with quantum fields. 05:09: The field strength determines how much force a quantum field exerts on other fields and particles. 05:22: ... this field strength - a little packet of energy held by the field. If a quantum field has energy in the form of particles and if space is expanding - as ... 05:45: ... quantum field can contain an intrinsic energy even without particles. In that ... 06:14: ... we graph a quantum field potential energy versus field strength, it might look something ... 06:55: If such a quantum field found itself near that local minimum then it would roll to the bottom and get stuck there. 08:29: ... super cooling would go on forever if the inflaton field stays stuck. But quantum fields have a tendency to randomly fluctuate to different values, thanks ... 08:51: ... going to quantum tunnel and on that other side, it sees a deeper truer minimum - perhaps ... 10:26: ... are unstable and they very quickly disperse their energy into the other quantum fields. The inflatons decay into the familiar particles of the standard ... 04:42: We need some quantum physics. In fact, we need some quantum field theory. 05:09: The field strength determines how much force a quantum field exerts on other fields and particles. 05:22: ... this field strength - a little packet of energy held by the field. If a quantum field has energy in the form of particles and if space is expanding - as is ... 05:45: ... quantum field can contain an intrinsic energy even without particles. In that case, it ... 06:14: ... we graph a quantum field potential energy versus field strength, it might look something like ... 06:55: If such a quantum field found itself near that local minimum then it would roll to the bottom and get stuck there. 05:09: The field strength determines how much force a quantum field exerts on other fields and particles. 06:14: ... we graph a quantum field potential energy versus field strength, it might look something like this: If the ... 04:42: We need some quantum physics. In fact, we need some quantum field theory. 04:55: There's some more homework for you. For now, a review: the universe is filled with quantum fields. 08:29: ... super cooling would go on forever if the inflaton field stays stuck. But quantum fields have a tendency to randomly fluctuate to different values, thanks to the ... 10:26: ... are unstable and they very quickly disperse their energy into the other quantum fields. The inflatons decay into the familiar particles of the standard model - ... 02:14: In the case of inflation part of the appeal is that it fits extremely nicely into our modern understanding of gravity and quantum mechanics. 04:42: We need some quantum physics. In fact, we need some quantum field theory. 08:51: ... going to quantum tunnel and on that other side, it sees a deeper truer minimum - perhaps the ...
	2019-07-18: Did Time Start at the Big Bang? 08:52: ... Bang singularity, and just after, GR comes into terrible conflict with quantum mechanics We've talked about that conflict and its possible resolutions ... 11:12: ... ways to get a new universe out of an old one for example an extreme quantum fluctuation could initiate a new Big Bang given infinite time or The ... 11:36: ... nothing moments physicists have a thing or two to say about that from quantum fluctuations from nothing - Stephen Hawking's timeless interpretation of ... 11:12: ... ways to get a new universe out of an old one for example an extreme quantum fluctuation could initiate a new Big Bang given infinite time or The same amount of ... 11:36: ... nothing moments physicists have a thing or two to say about that from quantum fluctuations from nothing - Stephen Hawking's timeless interpretation of internal ... 08:52: ... Bang singularity, and just after, GR comes into terrible conflict with quantum mechanics We've talked about that conflict and its possible resolutions before But ...
	2019-07-15: The Quantum Internet 00:00: When we finally have a quantum internet you’ll be able to simultaneously like and dislike this video. 00:43: ... classical cryptography, but one day soon this may not be enough and so quantum cryptographic methods and algorithms are being ... 01:00: To understand what needs to be done we need to get to the foundations of quantum mechanics - we need to talk about quantum information theory. 01:37: ... and certain fundamentals of physics - such as entropy, and also quantum ... 01:49: Quantum information theory parallels classical information theory, but instead of using classical bits, it deals bits of quantum information - qubits. 01:58: ... enjoy all of the weirdness of quantum mechanics - they can be in a superposition of many states at once, ... 02:21: Those restrictions, on top of all the weirdness, define the challenge of transmitting and storing quantum information. 02:27: But first, a reminder why we want to muck around with quantum info in the first place. 02:33: ... there’s the whole quantum computer thing - in those, the ability for a qubit to hold many ... 02:43: Partly motivated by the cryptographic-cracking power of the quantum computer, we also want to think about a quantum internet. 02:53: ... our episode on quantum key distribution we talked about two schemes for sharing cryptographic ... 03:03: ... these only work if you can actually send entangled quantum states between parties - that means transmitting qubits over long ... 03:19: We can already send photons of light very long distances using lasers or fiber optics - and those photons are pretty quantum. 03:27: The problem is that to transmit quantum information we have to pay attention to individual photons - quanta of light. 03:52: It’s much harder to transmit single photons in a way that perfectly maintains their quantum state. 04:09: It simply states that: “you cannot take a quantum state and copy it perfectly and end up with two copies of the same state existing at the same time”. 04:18: ... is connected to the law of conservation of quantum information, which we’ve talked about before - it comes from the fact ... 04:34: That prohibits a quantum state vanishing, but also splitting in two - or being copied. 04:40: ... such a way that you will never end up with two exact copies of the same quantum ... 04:53: ... you could copy it, you wouldn’t really be able to transmit an entangled quantum state because the act of reading in the state to copy it would destroy ... 05:32: But quantum information DOES allow us to massively extend the range over which we can send an intact qubit. 05:41: Think of it this way: Two people, let’s say Bill and Ted, are connected by a classical channel and a quantum channel. 05:49: ... optic cable, a telephone wire, the Pony Express, whatever, while the quantum channel needs to carry intact quantum states - so it's probably fibre ... 06:00: A pair of entangled particles are created, and Bill and Ted receive one each via the quantum channel. 07:18: ... this point the original quantum state of photon C, which contains the message, has been almost ... 07:36: The remaining information of the quantum state is actually obtained by observing the outcome of the process that generated the entanglement itself. 08:16: Combined with a quantum key distribution protocol, this can give a mechanism for secure communication. 08:22: It can also be used to transmit quantum information over longer distances than we could normally send entangled particles. 08:29: Just position repeaters along the quantum channel between Bill and Ted. 08:33: ... copy of the original qubit C. In principle this can be done without the quantum channel ever becoming ... 09:01: Quantum states have to somehow be stored – by Bill, by Ted, and by the repeaters in between. 09:07: ... typically means transferring a quantum state between a photon and a matter particle – say, an electron whose up ... 09:18: But storing delicate quantum states for any length of time is hard work – especially if you don’t want insanely expensive supercooled devices. 09:27: ... a number of ingenious solutions, ranging from storing entangled photon quantum states in a cloud of caesium atoms, a kind of quantum atomic disk drive, ... 10:00: This could also be done between many individuals in a centralized node – a sort of quantum switchboard. 10:14: These are great because they’re much, much faster than repeaters that have to transfer quantum states between photons and matter particles. 10:22: So the current state of the art is that entangled quantum states have been transmitted with photons using fibre optics and lasers. 10:34: ... serve as repeaters to extend the range and connect a network of these quantum ... 10:57: ... streams of 1’s and 0’s round the world, but if we could build truly quantum networks we’ll also be able to build the next generation of ... 11:18: The quantum information age is around the corner. 11:21: ... guessing we’ll go with “quantum age” - as the quantum internet enables us to take advantage of the ... 09:27: ... entangled photon quantum states in a cloud of caesium atoms, a kind of quantum atomic disk drive, or the spin-state of a single electron in a nitrogen atom ... 05:41: Think of it this way: Two people, let’s say Bill and Ted, are connected by a classical channel and a quantum channel. 05:49: ... optic cable, a telephone wire, the Pony Express, whatever, while the quantum channel needs to carry intact quantum states - so it's probably fibre ... 06:00: A pair of entangled particles are created, and Bill and Ted receive one each via the quantum channel. 08:29: Just position repeaters along the quantum channel between Bill and Ted. 08:33: ... copy of the original qubit C. In principle this can be done without the quantum channel ever becoming ... 10:34: ... serve as repeaters to extend the range and connect a network of these quantum channels. ... 02:33: ... there’s the whole quantum computer thing - in those, the ability for a qubit to hold many simultaneous ... 02:43: Partly motivated by the cryptographic-cracking power of the quantum computer, we also want to think about a quantum internet. 02:33: ... there’s the whole quantum computer thing - in those, the ability for a qubit to hold many simultaneous states can ... 10:57: ... to build the next generation of cryptographic protocols, distributed quantum computers, as well as achieve new levels of atomic clock synchronization and ... 00:43: ... classical cryptography, but one day soon this may not be enough and so quantum cryptographic methods and algorithms are being ... 02:27: But first, a reminder why we want to muck around with quantum info in the first place. 00:00: When we finally have a quantum internet you’ll be able to simultaneously like and dislike this video. 02:43: Partly motivated by the cryptographic-cracking power of the quantum computer, we also want to think about a quantum internet. 11:21: ... guessing we’ll go with “quantum age” - as the quantum internet enables us to take advantage of the incredible properties of our quantum ... 00:00: When we finally have a quantum internet you’ll be able to simultaneously like and dislike this video. 02:53: ... our episode on quantum key distribution we talked about two schemes for sharing cryptographic keys ... 08:16: Combined with a quantum key distribution protocol, this can give a mechanism for secure communication. 02:53: ... our episode on quantum key distribution we talked about two schemes for sharing cryptographic keys that should ... 08:16: Combined with a quantum key distribution protocol, this can give a mechanism for secure communication. 01:00: To understand what needs to be done we need to get to the foundations of quantum mechanics - we need to talk about quantum information theory. 01:58: ... enjoy all of the weirdness of quantum mechanics - they can be in a superposition of many states at once, defined only ... 01:00: To understand what needs to be done we need to get to the foundations of quantum mechanics - we need to talk about quantum information theory. 01:58: ... enjoy all of the weirdness of quantum mechanics - they can be in a superposition of many states at once, defined only when ... 10:57: ... streams of 1’s and 0’s round the world, but if we could build truly quantum networks we’ll also be able to build the next generation of cryptographic ... 11:21: ... enables us to take advantage of the incredible properties of our quantum space ... 03:52: It’s much harder to transmit single photons in a way that perfectly maintains their quantum state. 04:09: It simply states that: “you cannot take a quantum state and copy it perfectly and end up with two copies of the same state existing at the same time”. 04:18: ... which we’ve talked about before - it comes from the fact that every quantum state in the universe must be perfectly traceable - single quantum state to ... 04:34: That prohibits a quantum state vanishing, but also splitting in two - or being copied. 04:40: ... such a way that you will never end up with two exact copies of the same quantum state. ... 04:53: ... you could copy it, you wouldn’t really be able to transmit an entangled quantum state because the act of reading in the state to copy it would destroy the ... 07:18: ... this point the original quantum state of photon C, which contains the message, has been almost completely ... 07:36: The remaining information of the quantum state is actually obtained by observing the outcome of the process that generated the entanglement itself. 09:07: ... typically means transferring a quantum state between a photon and a matter particle – say, an electron whose up or ... 04:18: ... universe must be perfectly traceable - single quantum state to single quantum state - both forwards and backwards in ... 04:34: That prohibits a quantum state vanishing, but also splitting in two - or being copied. 03:03: ... these only work if you can actually send entangled quantum states between parties - that means transmitting qubits over long distances ... 05:49: ... Pony Express, whatever, while the quantum channel needs to carry intact quantum states - so it's probably fibre ... 09:01: Quantum states have to somehow be stored – by Bill, by Ted, and by the repeaters in between. 09:18: But storing delicate quantum states for any length of time is hard work – especially if you don’t want insanely expensive supercooled devices. 09:27: ... a number of ingenious solutions, ranging from storing entangled photon quantum states in a cloud of caesium atoms, a kind of quantum atomic disk drive, or the ... 10:14: These are great because they’re much, much faster than repeaters that have to transfer quantum states between photons and matter particles. 10:22: So the current state of the art is that entangled quantum states have been transmitted with photons using fibre optics and lasers. 05:49: ... Pony Express, whatever, while the quantum channel needs to carry intact quantum states - so it's probably fibre ... 10:00: This could also be done between many individuals in a centralized node – a sort of quantum switchboard. 01:37: ... and certain fundamentals of physics - such as entropy, and also quantum theory. ...
	2019-06-17: How Black Holes Kill Galaxies 11:24: ... problems so whether you wanna learn about special relativity, quantum physics or brush up on your complex algebra and differential equations ...
	2019-06-06: The Alchemy of Neutron Star Collisions 13:02: ... Grumpy's wavefunction - can't Has Cheezburger just by talking about it quantum mechanics forbids that anyway I'm sure grumpy is now in meme heaven ...
	2019-05-16: The Cosmic Dark Ages 13:07: ... time we talked about some quantum encryption - ways to secure messages using the weirdness of quantum ... 13:23: ... Ellen and EebstertheGreat note that both prime numbers in your quantum key need to be large numbers, not just one of them, as we stated. ... 13:43: ... others also point out that internet security isn't doomed in the wake of quantum computers without us also having quantum cryptography. There are a ... 14:26: ... as others mentioned, that condition is a big one - maintaining a quantum state over long distance is very difficult, requiring relays to ... 14:38: ... revert to classical information while being boosted. We'll talk about quantum relays in an upcoming ... 14:48: ... that episode we'll probably conclude that a real quantum internet is a long way off. That said, the entire point of talking about ... 15:04: ... Areani, regarding the quantum internet quips: "You might or might not have mail!" Nice. In ... 13:43: ... others also point out that internet security isn't doomed in the wake of quantum computers without us also having quantum cryptography. There are a number of ... 14:48: ... internet is a long way off. That said, the entire point of talking about quantum cryptography was as a way to describe some of the crazy properties of quantum ... 13:07: ... time we talked about some quantum encryption - ways to secure messages using the weirdness of quantum mechanics. One ... 14:48: ... that episode we'll probably conclude that a real quantum internet is a long way off. That said, the entire point of talking about quantum ... 15:04: ... Areani, regarding the quantum internet quips: "You might or might not have mail!" Nice. In Schrodinger's ... 13:23: ... Ellen and EebstertheGreat note that both prime numbers in your quantum key need to be large numbers, not just one of them, as we stated. Doesn't ... 13:07: ... some quantum encryption - ways to secure messages using the weirdness of quantum mechanics. One thing I learned is that you guys already know a lot about classical ... 14:48: ... cryptography was as a way to describe some of the crazy properties of quantum mechanics. Hopefully we managed to do ... 14:38: ... revert to classical information while being boosted. We'll talk about quantum relays in an upcoming ... 14:26: ... as others mentioned, that condition is a big one - maintaining a quantum state over long distance is very difficult, requiring relays to reprepare and ... 13:43: ... reason for that is that assuming the channel can actually maintain pure quantum states, in order to break quantum crypto you need to break the laws of physics - ...
	2019-05-09: Why Quantum Computing Requires Quantum Cryptography 00:03: Quantum computing is cool, but you know what would be extra awesome - a quantum internet. 00:12: And the first step to the quantum internet is quantum cryptography. 00:22: Quantum theory may seem like an obscure subject of questionable relevance to the average person. 00:27: But in fact much of our technological world depends on our understanding of the quantum properties of the subatomic universe. 00:35: ... soon, perhaps very soon, we’ll be interacting with the weirdness of quantum mechanics even more directly – with the coming of quantum computing and ... 00:48: Specifically quantum cryptography and quantum key distribution – the foundations of the prospective quantum internet. 00:56: We may come back to quantum computers in detail – but for now just a word on why their advent will demand a quantum internet. 01:04: The logic gates of a quantum computer exist in a state of quantum superposition of many simultaneous configurations. 01:21: For example, a quantum computer can calculate the prime factors of large numbers extremely quickly. 03:01: Once quantum computers can factorize public keys quickly the entire public key system falls apart. 03:52: Enter quantum key distribution. 04:21: Each highlights a different fundamental weirdness of quantum mechanics – the Heisenberg uncertainty principle and quantum entanglement. 04:29: These will be the keys to unbreakable cryptography of a quantum internet. 04:52: Another example is the polarization of a photon, a quantum of electromagnetic wave. 06:26: In fact here’s an quantum experiment you can do at home. 06:37: You just switched between different quantum representations of reality and then back again, and so invoked the uncertainty principle. 07:16: This is the basis of one of the first quantum key distribution algorithms developed in 1984 Bennett and Brassard and known as BB84. 08:44: If he doesn’t, they know something was up - and this is where the quantum part becomes useful. 10:34: So that’s BB84, and it's one path to a secure quantum internet. 10:40: Another way to generate secure keys using quantum mechanics was developed by Artur Ekert in 1991. 10:46: It uses a similar choice-of-quantum-basis mechanism but with the added frill of quantum entanglement. 10:58: Here we definitely have to direct you to our full episode on quantum entanglement for the details. 11:04: ... the super-brief summary: create a pair of particles with a quantum property that is correlated between the two – for example, electrons ... 13:13: Which to be fair will still be the case in a quantum internet. 13:16: But come quantum computers even the smartest classical security protocols will be compromised. 13:23: Then we’ll also need a quantum internet … which we know how to do in theory, but it’s a different matter to actually build one. 13:34: Quantum states – and particularly entangled states – are notoriously fragile and so it’s hard to transmit them across large distances. 13:42: We’ll show you how to construct a vast, planet-spanning network of encrypted quantum states real soon. 01:04: The logic gates of a quantum computer exist in a state of quantum superposition of many simultaneous configurations. 01:21: For example, a quantum computer can calculate the prime factors of large numbers extremely quickly. 01:04: The logic gates of a quantum computer exist in a state of quantum superposition of many simultaneous configurations. 00:56: We may come back to quantum computers in detail – but for now just a word on why their advent will demand a quantum internet. 03:01: Once quantum computers can factorize public keys quickly the entire public key system falls apart. 13:16: But come quantum computers even the smartest classical security protocols will be compromised. 00:03: Quantum computing is cool, but you know what would be extra awesome - a quantum internet. 00:35: ... weirdness of quantum mechanics even more directly – with the coming of quantum computing and the quantum ... 00:12: And the first step to the quantum internet is quantum cryptography. 00:48: Specifically quantum cryptography and quantum key distribution – the foundations of the prospective quantum internet. 04:21: Each highlights a different fundamental weirdness of quantum mechanics – the Heisenberg uncertainty principle and quantum entanglement. 10:46: It uses a similar choice-of-quantum-basis mechanism but with the added frill of quantum entanglement. 10:58: Here we definitely have to direct you to our full episode on quantum entanglement for the details. 06:26: In fact here’s an quantum experiment you can do at home. 00:03: Quantum computing is cool, but you know what would be extra awesome - a quantum internet. 00:12: And the first step to the quantum internet is quantum cryptography. 00:35: ... even more directly – with the coming of quantum computing and the quantum internet. ... 00:48: Specifically quantum cryptography and quantum key distribution – the foundations of the prospective quantum internet. 00:56: We may come back to quantum computers in detail – but for now just a word on why their advent will demand a quantum internet. 04:29: These will be the keys to unbreakable cryptography of a quantum internet. 10:34: So that’s BB84, and it's one path to a secure quantum internet. 13:13: Which to be fair will still be the case in a quantum internet. 13:23: Then we’ll also need a quantum internet … which we know how to do in theory, but it’s a different matter to actually build one. 00:48: Specifically quantum cryptography and quantum key distribution – the foundations of the prospective quantum internet. 03:52: Enter quantum key distribution. 07:16: This is the basis of one of the first quantum key distribution algorithms developed in 1984 Bennett and Brassard and known as BB84. 00:48: Specifically quantum cryptography and quantum key distribution – the foundations of the prospective quantum internet. 03:52: Enter quantum key distribution. 07:16: This is the basis of one of the first quantum key distribution algorithms developed in 1984 Bennett and Brassard and known as BB84. 00:35: ... soon, perhaps very soon, we’ll be interacting with the weirdness of quantum mechanics even more directly – with the coming of quantum computing and the ... 04:21: Each highlights a different fundamental weirdness of quantum mechanics – the Heisenberg uncertainty principle and quantum entanglement. 10:40: Another way to generate secure keys using quantum mechanics was developed by Artur Ekert in 1991. 00:27: But in fact much of our technological world depends on our understanding of the quantum properties of the subatomic universe. 11:04: ... the super-brief summary: create a pair of particles with a quantum property that is correlated between the two – for example, electrons with ... 06:37: You just switched between different quantum representations of reality and then back again, and so invoked the uncertainty principle. 13:34: Quantum states – and particularly entangled states – are notoriously fragile and so it’s hard to transmit them across large distances. 13:42: We’ll show you how to construct a vast, planet-spanning network of encrypted quantum states real soon. 01:04: The logic gates of a quantum computer exist in a state of quantum superposition of many simultaneous configurations. 00:22: Quantum theory may seem like an obscure subject of questionable relevance to the average person. 03:45: A metaphorical quantum-mechanical bridge, which allows the sharing of a secure private key.
	2019-04-10: The Holographic Universe Explained 01:02: We’ve moved from quantum field theory to black hole thermodynamics to string theory. 01:27: A black hole’s entropy represents the amount of quantum information of everything that ever fell into it. 02:11: ... information paradox, because this radiation was expected to erase the quantum information of everything that fell into the black ... 02:23: But destroying quantum information would break the foundations of quantum mechanics. 08:23: ... weird thing is that when you write the quantum wave equation for the gluon strand with length expressed as a separate ... 08:49: ... it was quickly rejigged to make it a theory of quantum gravity, and the scale invariance of the strings becoming a central ... 10:37: ... itself that field theory wasn’t stringy– rather it was a quantum field theory like the ones that gives us our standard model of particle ... 11:24: The conformal field theory in the original space included no gravity, but in the higher-dimensional space it became a full quantum theory of gravity. 13:23: The rules of interactions between cells on the surface is a quantum field theory. 15:28: ... a type of string theory, while the surface exhibits no gravity - only a quantum field theory similar to the field theory behind the standard ... 17:50: Personally, I'd always thought of him as a Jedi master - especially with all that dubious quantum consciousness stuff. 01:02: We’ve moved from quantum field theory to black hole thermodynamics to string theory. 10:37: ... itself that field theory wasn’t stringy– rather it was a quantum field theory like the ones that gives us our standard model of particle ... 13:23: The rules of interactions between cells on the surface is a quantum field theory. 15:28: ... a type of string theory, while the surface exhibits no gravity - only a quantum field theory similar to the field theory behind the standard ... 01:02: We’ve moved from quantum field theory to black hole thermodynamics to string theory. 10:37: ... itself that field theory wasn’t stringy– rather it was a quantum field theory like the ones that gives us our standard model of particle physics – a ... 13:23: The rules of interactions between cells on the surface is a quantum field theory. 15:28: ... a type of string theory, while the surface exhibits no gravity - only a quantum field theory similar to the field theory behind the standard ... 08:49: ... it was quickly rejigged to make it a theory of quantum gravity, and the scale invariance of the strings becoming a central feature of ... 02:23: But destroying quantum information would break the foundations of quantum mechanics. 08:23: ... as a separate dimension you get the wave equation for a graviton – the quantum particle of ... 11:24: The conformal field theory in the original space included no gravity, but in the higher-dimensional space it became a full quantum theory of gravity. 08:23: ... weird thing is that when you write the quantum wave equation for the gluon strand with length expressed as a separate ...
	2019-04-03: The Edge of an Infinite Universe 07:16: Only lightspeed paths – or in the language of quantum field theory “massless fields” can access these diagonal boundaries. 07:25: ... then we can do something that seems impossible – we can track a quantum field to infinite distance and calculate its behavior ... 08:01: That’s handy because flat space is the only space where quantum mechanics is fully solvable. 08:15: ... connected a quantum field between two points at infinite distance – past and future - where ... 08:26: Then he placed a black hole in between these points and calculated how it perturbed the balance of a quantum field traced between them. 14:04: ... realized that if you define a conformal quantum field theory in a 3+1-dimensional Minkowski space, that corresponded to ... 14:31: Quantum mechanics in the form of a conformal field theory in one space is a theory of quantum gravity in a space with one higher dimension. 14:49: Every particle, every gravitational effect in the bulk is represented by quantum fields on an infinitely distant surface. 07:16: Only lightspeed paths – or in the language of quantum field theory “massless fields” can access these diagonal boundaries. 07:25: ... then we can do something that seems impossible – we can track a quantum field to infinite distance and calculate its behavior ... 08:15: ... connected a quantum field between two points at infinite distance – past and future - where he ... 08:26: Then he placed a black hole in between these points and calculated how it perturbed the balance of a quantum field traced between them. 14:04: ... realized that if you define a conformal quantum field theory in a 3+1-dimensional Minkowski space, that corresponded to an ... 07:16: Only lightspeed paths – or in the language of quantum field theory “massless fields” can access these diagonal boundaries. 14:04: ... realized that if you define a conformal quantum field theory in a 3+1-dimensional Minkowski space, that corresponded to an ... 08:26: Then he placed a black hole in between these points and calculated how it perturbed the balance of a quantum field traced between them. 14:49: Every particle, every gravitational effect in the bulk is represented by quantum fields on an infinitely distant surface. 14:31: Quantum mechanics in the form of a conformal field theory in one space is a theory of quantum gravity in a space with one higher dimension. 08:01: That’s handy because flat space is the only space where quantum mechanics is fully solvable. 14:31: Quantum mechanics in the form of a conformal field theory in one space is a theory of quantum gravity in a space with one higher dimension. 08:15: ... distance – past and future - where he could define the state of the quantum vacuum in solvable flat ...
	2019-03-13: Will You Travel to Space? 13:51: Electrons escape their orbits by quantum tunneling, and protons themselves may eventually decay.
	2019-03-06: The Impossibility of Perpetual Motion Machines 06:50: In fact, quantum mechanics forbids it. 06:55: Due to the intrinsic quantum randomness of all particles, as expressed by the Heisenberg uncertainty principle, everything moves. 08:41: One popular source of free energy is the zero-point energy of the quantum vacuum, and it’s the most fun to debunk. 08:48: ... going to have to refer you to our entire playlist on the quantum vacuum for the physics, but the important point is that any energy of ... 06:50: In fact, quantum mechanics forbids it. 06:55: Due to the intrinsic quantum randomness of all particles, as expressed by the Heisenberg uncertainty principle, everything moves. 08:41: One popular source of free energy is the zero-point energy of the quantum vacuum, and it’s the most fun to debunk. 08:48: ... going to have to refer you to our entire playlist on the quantum vacuum for the physics, but the important point is that any energy of the ...
	2019-02-07: Sound Waves from the Beginning of Time 03:51: ... bit less there, These fluctuations probably were the remnants of random quantum fluctuations From when the universe was subatomic in ... 13:26: ... the probability of collapsing into a big crunch due to everything quantum tunneling towards a single ... 13:50: Almost certainly, there could be no quantum tunneling big crunch, but there is some smaller size that can eventually collapse that way. 13:58: ... you need to wait 10^(10^25) years for the first quantum tunneling to turn iron stars into black holes, and way, way longer than ... 14:33: Remember that things like general relativity and much of quantum field theory are verified to stunning precision. 03:51: ... bit less there, These fluctuations probably were the remnants of random quantum fluctuations From when the universe was subatomic in ... 13:26: ... the probability of collapsing into a big crunch due to everything quantum tunneling towards a single ... 13:50: Almost certainly, there could be no quantum tunneling big crunch, but there is some smaller size that can eventually collapse that way. 13:58: ... you need to wait 10^(10^25) years for the first quantum tunneling to turn iron stars into black holes, and way, way longer than that for ... 13:50: Almost certainly, there could be no quantum tunneling big crunch, but there is some smaller size that can eventually collapse that way.
	2019-01-30: Perpetual Motion From Negative Mass? 03:48: ... note, and at the risk of getting way too technical, this is also what quantum field theory predicts: fields with even spin have to work in the ... 12:23: I’m pretty sure that breaks quantum field theory as well as general relativity. 03:48: ... note, and at the risk of getting way too technical, this is also what quantum field theory predicts: fields with even spin have to work in the opposite way ... 12:23: I’m pretty sure that breaks quantum field theory as well as general relativity. 03:48: ... note, and at the risk of getting way too technical, this is also what quantum field theory predicts: fields with even spin have to work in the opposite way to ... 12:23: I’m pretty sure that breaks quantum field theory as well as general relativity.
	2019-01-24: The Crisis in Cosmology 15:47: ...as demonstrated by the different forward/backward reaction rates in certain quantum interactions. 16:41: ...and is used in, for example, Feynman's path integral formulation of quantum mechanics. 15:47: ...as demonstrated by the different forward/backward reaction rates in certain quantum interactions. 16:41: ...and is used in, for example, Feynman's path integral formulation of quantum mechanics.
	2019-01-16: Our Antimatter, Mirrored, Time-Reversed Universe 00:03: ... foundations of quantum theory rest on its symmetries for example it should be impossible to ... 02:02: ... of charge parity and time and this symmetry lies at the foundations of quantum field theory physics must work the same if we flip all of these ... 03:02: ... decay of neutral Kaons these things are extra weird and usual k on is a quantum mix of its own particle and antiparticle there are two ways to do this ... 08:43: ... don't we absolutely require time reversal symmetry in order to conserve quantum information which itself is required for all of quantum mechanics to ... 10:26: ... with Richard Feynman - it's essential to his path integral approach to quantum mechanics and to Feynman diagrams maybe that's why he was so into ... 10:54: ... then there's the whole entropy business although it's connection to quantum mechanics is still not well understood like I said this simple ... 16:49: ... of string theory is connected to the extreme energy scale of quantum gravity and that problem is not unique to string theory. Now we do talk ... 17:15: ... of physicists. We blasted through several reality layers from atoms to quantum fields in the past hundred years or so but maybe the next layer will ... 02:02: ... of charge parity and time and this symmetry lies at the foundations of quantum field theory physics must work the same if we flip all of these properties if ... 03:02: ... Valley California the 1950s was also the decade of the foundations of quantum field theory an SQFT emerged it became clear that there is a certain symmetry ... 02:02: ... of charge parity and time and this symmetry lies at the foundations of quantum field theory physics must work the same if we flip all of these properties if not ... 03:02: ... Valley California the 1950s was also the decade of the foundations of quantum field theory an SQFT emerged it became clear that there is a certain symmetry that's ... 17:15: ... of physicists. We blasted through several reality layers from atoms to quantum fields in the past hundred years or so but maybe the next layer will take ... 16:49: ... of string theory is connected to the extreme energy scale of quantum gravity and that problem is not unique to string theory. Now we do talk about ... 08:43: ... to conserve quantum information which itself is required for all of quantum mechanics to make sense - well to get at this we're going to need to talk about ... 10:26: ... with Richard Feynman - it's essential to his path integral approach to quantum mechanics and to Feynman diagrams maybe that's why he was so into building ... 10:54: ... then there's the whole entropy business although it's connection to quantum mechanics is still not well understood like I said this simple interpretation of T ... 03:02: ... decay of neutral Kaons these things are extra weird and usual k on is a quantum mix of its own particle and antiparticle there are two ways to do this ... 00:03: ... foundations of quantum theory rest on its symmetries for example it should be impossible to ... 10:54: ... take the same amount of time going forwards as backwards for example a quantum transition between one particle type and another should take the same time in ...
	2018-12-20: Why String Theory is Wrong 01:06: ... old idea did work when translated to the very particular case of a quantum string, which is part of what got string theory going in the first ... 01:35: ... seemed so beautiful, the effortlessness of its inclusion of quantum gravity, its promise to unify all particles under one umbrella, and ... 03:37: Klein realized that you can get a sensible quantum theory if you compactify that extra dimension. 07:50: Our tiny quantum strings can roam that small dimension. 14:34: ... entire field of gauge theory upon which much of our understanding of the quantum world ... 14:48: It also gave us the sought after quantum electromagnetism in the end, just with a slightly different symmetry. 15:37: ... whether you want to learn about special relativity in quantum physics or brush up on your complex algebra and differential equations ... 14:48: It also gave us the sought after quantum electromagnetism in the end, just with a slightly different symmetry. 01:35: ... seemed so beautiful, the effortlessness of its inclusion of quantum gravity, its promise to unify all particles under one umbrella, and there's also ... 15:37: ... whether you want to learn about special relativity in quantum physics or brush up on your complex algebra and differential equations you can ... 01:06: ... old idea did work when translated to the very particular case of a quantum string, which is part of what got string theory going in the first ... 07:50: Our tiny quantum strings can roam that small dimension. 03:37: Klein realized that you can get a sensible quantum theory if you compactify that extra dimension.
	2018-12-12: Quantum Physics in a Mirror Universe 00:02: ... in space-time and even the rather abstract phase of the wave function in quantum mechanics so it might be surprising to learn that with all the weird ...
	2018-11-21: 'Oumuamua Is Not Aliens 13:37: Whether you want to learn about astronomy, quantum physics, or even artificial neural networks, you can learn more at brilliant.org/spacetime.
	2018-11-07: Why String Theory is Right 00:06: ... theory as the one great hope for a theory of everything that will unify quantum mechanics and gravity and so unify all of physics into one great, ... 02:50: ... fact, it will be difficult to remove it, and the quantum gravity of string theory is immune to the main difficulty in uniting ... 03:07: ... did talk about this and other problems with developing a quantum theory of gravity in a recent episode, but before we get to the nuts and ... 03:40: In quantum theories of gravity, the gravitational force is communicated by the graviton particle. 05:06: ... illustrate why quantum gravity isn't hopelessly broken in string theory, and that's a huge ... 05:22: ... see, it turns out that tiny vibrating quantum strings automatically reproduce the theory of general relativity and, in ... 05:54: ... flying through the air or a vibrating rubber band and turning it into a quantum ... 06:05: ... follow a standard recipe to turn them into wave equations with various quantum weirdness added in like the uncertainty relation between certain ... 07:46: A really important type of symmetry in quantum mechanics is gauge symmetry. 08:11: So, we expect the phase of the quantum wave function to be a gauge symmetry of any quantum theory. 08:54: So in a way, electromagnetism was discovered in its quantum form by studying the symmetries of quantum mechanics. 10:25: That's on the 2D dimensional world sheet of a quantum string. 10:41: ... we can smooth out that surface mathematically and write a nice, simple quantum wave equation from the equations of motion, but only for 1D strings ... 11:28: So, with our quantized equations of motion in hand, you can predict the quantum oscillations of our string. 11:35: These are particles, and the first mode looks like the graviton, a quantum particle in the aforementioned gravitational field. 14:14: ... week we talked about one of the most misunderstood concepts in quantum mechanics, the idea of virtual particles and their tenuous connection to ... 14:37: These fundamental forces are mediated by fluctuations in the quantum fields of the relevant forces. 16:03: David Ratliff asks if a quantum tree falls in a vacuum and nobody is around to measure it, does it still have energy? 16:39: Quantum mechanics can't tell us whether anyone cares. 05:54: ... flying through the air or a vibrating rubber band and turning it into a quantum description. ... 14:37: These fundamental forces are mediated by fluctuations in the quantum fields of the relevant forces. 08:54: So in a way, electromagnetism was discovered in its quantum form by studying the symmetries of quantum mechanics. 02:50: ... fact, it will be difficult to remove it, and the quantum gravity of string theory is immune to the main difficulty in uniting general ... 05:06: ... illustrate why quantum gravity isn't hopelessly broken in string theory, and that's a huge point in ... 00:06: ... theory as the one great hope for a theory of everything that will unify quantum mechanics and gravity and so unify all of physics into one great, glorious theory ... 02:50: ... is immune to the main difficulty in uniting general relativity with quantum mechanics. ... 07:46: A really important type of symmetry in quantum mechanics is gauge symmetry. 08:54: So in a way, electromagnetism was discovered in its quantum form by studying the symmetries of quantum mechanics. 14:14: ... week we talked about one of the most misunderstood concepts in quantum mechanics, the idea of virtual particles and their tenuous connection to ... 16:39: Quantum mechanics can't tell us whether anyone cares. 11:28: So, with our quantized equations of motion in hand, you can predict the quantum oscillations of our string. 11:35: These are particles, and the first mode looks like the graviton, a quantum particle in the aforementioned gravitational field. 10:25: That's on the 2D dimensional world sheet of a quantum string. 05:22: ... see, it turns out that tiny vibrating quantum strings automatically reproduce the theory of general relativity and, in the ... 03:40: In quantum theories of gravity, the gravitational force is communicated by the graviton particle. 03:07: ... did talk about this and other problems with developing a quantum theory of gravity in a recent episode, but before we get to the nuts and bolts ... 05:22: ... and, in the same mechanism, seem to promise to reproduce all of quantum theory ... 08:11: So, we expect the phase of the quantum wave function to be a gauge symmetry of any quantum theory. 16:03: David Ratliff asks if a quantum tree falls in a vacuum and nobody is around to measure it, does it still have energy? 08:11: So, we expect the phase of the quantum wave function to be a gauge symmetry of any quantum theory. 10:41: ... we can smooth out that surface mathematically and write a nice, simple quantum wave equation from the equations of motion, but only for 1D strings making a ... 08:11: So, we expect the phase of the quantum wave function to be a gauge symmetry of any quantum theory. 06:05: ... follow a standard recipe to turn them into wave equations with various quantum weirdness added in like the uncertainty relation between certain ...
	2018-10-31: Are Virtual Particles A New Layer of Reality? 01:15: That math hack turned out to represent the very real quantum nature of the photon. 01:22: This insight led to the discovery of all quantum physics. 01:30: ... started out as a trick to make impossible calculations in quantum field theory possible-- possible, at least, for the sort of people who ... 01:47: Now, we're going to go pretty deep in this one, but it will bring us closer to a better understanding of the quantum nature of reality. 02:01: So quantum field theory is the machinery behind the standard model of particle physics. 03:16: In that sense, virtual particles are the building blocks of our approximation of the behavior of quantum fields. 03:25: ... field, transferring between them energy momentum and one photon worth of quantum properties in a single packet that we call a virtual ... 04:58: ... diagrams are an absolutely essential tool in most modern quantum field theory calculations, but they also add to the misconception about ... 05:18: ... share some properties with their real counterparts-- in particular, quantum numbers like charge and spin, but they don't need to obey Einstein's ... 05:45: Virtual particles are our mathematical representation of the quantum mechanical behavior of fields, and that behavior is weird. 06:00: One electron throws a virtual photon at the other one causing them to be deflected from each other like a game of quantum dodgeball. 07:09: ... one of these infinite possible virtual particles represents a quantum of energy in a single possible vibrational mode of the underlying ... 08:03: ... a bit like the photon starts out moving in the wrong direction and then quantum tunnels between the particles, kicking them towards each other like a ... 08:40: Did I mention that quantum mechanics is weird? 08:52: ... might have heard the quantum vacuum described as his roiling ocean of virtual particle-antiparticle ... 09:06: So the quantum fields are composed of these vibrational modes of all different frequencies/momenta that can be excited to become particles. 09:20: ... mode should have 0 energy in a vacuum, but in quantum mechanics, nothing can be so exact-- thanks, again, to the Heisenberg ... 10:27: ... a quantum state in a superposition of "yep particles" and "nope, no particles." ... 11:28: In his actual mathematical derivation, he instead talks about vibrational modes of the quantum vacuum being cut off by the event horizon. 11:44: A similar perturbation of the quantum vacuum is also seen in the Casimir and Unruh effects. 12:00: So to recap, virtual particles are best thought of as a mathematical device to represent the behavior of quantum fields. 12:08: ... tool in perturbation theory as we tried to approximate the behavior of quantum ... 12:18: ... in the case of Max Planck discovery of the quantum nature of photons, it turned out that a mathematical artifact ... 12:31: ... there was no way to express his Planck law without an artifact of that quantum nature-- namely, the Planck ... 12:45: If they represent a physical reality, then there should be no way to do quantum field theory calculations without them. 12:53: It turns out there is a version of quantum field theory that doesn't use virtual particles at all. 13:17: There is no good reason to believe that virtual particles exist outside the math we use to approximate the behavior of quantum fields. 13:25: At best, they can be interpreted as a small component of possibility space for a quantum field doing something real. 13:32: That said, for something that doesn't exist, they're surprisingly useful for describing the weird underlying machinery in our quantum space-time. 06:00: One electron throws a virtual photon at the other one causing them to be deflected from each other like a game of quantum dodgeball. 01:30: ... started out as a trick to make impossible calculations in quantum field theory possible-- possible, at least, for the sort of people who can do ... 02:01: So quantum field theory is the machinery behind the standard model of particle physics. 04:58: ... diagrams are an absolutely essential tool in most modern quantum field theory calculations, but they also add to the misconception about ... 07:09: ... of energy in a single possible vibrational mode of the underlying quantum field. ... 12:45: If they represent a physical reality, then there should be no way to do quantum field theory calculations without them. 12:53: It turns out there is a version of quantum field theory that doesn't use virtual particles at all. 13:25: At best, they can be interpreted as a small component of possibility space for a quantum field doing something real. 01:30: ... started out as a trick to make impossible calculations in quantum field theory possible-- possible, at least, for the sort of people who can do quantum ... 02:01: So quantum field theory is the machinery behind the standard model of particle physics. 04:58: ... diagrams are an absolutely essential tool in most modern quantum field theory calculations, but they also add to the misconception about virtual ... 12:45: If they represent a physical reality, then there should be no way to do quantum field theory calculations without them. 12:53: It turns out there is a version of quantum field theory that doesn't use virtual particles at all. 03:16: In that sense, virtual particles are the building blocks of our approximation of the behavior of quantum fields. 09:06: So the quantum fields are composed of these vibrational modes of all different frequencies/momenta that can be excited to become particles. 12:00: So to recap, virtual particles are best thought of as a mathematical device to represent the behavior of quantum fields. 12:08: ... tool in perturbation theory as we tried to approximate the behavior of quantum fields. ... 13:17: There is no good reason to believe that virtual particles exist outside the math we use to approximate the behavior of quantum fields. 05:45: Virtual particles are our mathematical representation of the quantum mechanical behavior of fields, and that behavior is weird. 08:40: Did I mention that quantum mechanics is weird? 09:20: ... mode should have 0 energy in a vacuum, but in quantum mechanics, nothing can be so exact-- thanks, again, to the Heisenberg uncertainty ... 01:15: That math hack turned out to represent the very real quantum nature of the photon. 01:47: Now, we're going to go pretty deep in this one, but it will bring us closer to a better understanding of the quantum nature of reality. 12:18: ... in the case of Max Planck discovery of the quantum nature of photons, it turned out that a mathematical artifact represented new ... 12:31: ... there was no way to express his Planck law without an artifact of that quantum nature-- namely, the Planck ... 05:18: ... share some properties with their real counterparts-- in particular, quantum numbers like charge and spin, but they don't need to obey Einstein's ... 01:22: This insight led to the discovery of all quantum physics. 03:25: ... field, transferring between them energy momentum and one photon worth of quantum properties in a single packet that we call a virtual ... 13:32: That said, for something that doesn't exist, they're surprisingly useful for describing the weird underlying machinery in our quantum space-time. 10:27: ... a quantum state in a superposition of "yep particles" and "nope, no particles." The ... 08:03: ... a bit like the photon starts out moving in the wrong direction and then quantum tunnels between the particles, kicking them towards each other like a ... 08:52: ... might have heard the quantum vacuum described as his roiling ocean of virtual particle-antiparticle pairs ... 11:28: In his actual mathematical derivation, he instead talks about vibrational modes of the quantum vacuum being cut off by the event horizon. 11:44: A similar perturbation of the quantum vacuum is also seen in the Casimir and Unruh effects.
	2018-10-18: What are the Strings in String Theory? 02:32: A lot of work went into figuring out a quantum theory for the strong interaction based on the physics of strings. 02:39: The theory had some success but kind of got stuck and was ultimately replaced by quantum chromodynamics. 02:58: What's a vibrational mode in a quantum field? 03:08: But the only hypothetical massless spin-2 particle is the graviton, the conjectured quantum particle of the gravitational field. 03:16: ... the gravitational field is made of quantum particles, which it might be-- we really don't know, but if it is-- then ... 03:45: What if the math of this theory could be used in a theory of quantum gravity? 05:29: To understand quantum strings, first we need to look at regular strings. 06:48: Niels Bohr came up with the first quantum model for electron orbits by thinking of them as ring-like standing waves around the hydrogen atom. 06:57: But quantum strings are much more ambitious than boring electron orbits. 09:10: ... you remember from our episode on quantum gravity, if you try to describe gravitational interactions on the ... 11:16: Very tiny objects like quantum strings could explore that extra dimension, and importantly, oscillate in it. 02:39: The theory had some success but kind of got stuck and was ultimately replaced by quantum chromodynamics. 02:58: What's a vibrational mode in a quantum field? 03:45: What if the math of this theory could be used in a theory of quantum gravity? 09:10: ... you remember from our episode on quantum gravity, if you try to describe gravitational interactions on the smaller scales, ... 06:48: Niels Bohr came up with the first quantum model for electron orbits by thinking of them as ring-like standing waves around the hydrogen atom. 03:08: But the only hypothetical massless spin-2 particle is the graviton, the conjectured quantum particle of the gravitational field. 03:16: ... the gravitational field is made of quantum particles, which it might be-- we really don't know, but if it is-- then the quanta ... 05:29: To understand quantum strings, first we need to look at regular strings. 06:57: But quantum strings are much more ambitious than boring electron orbits. 11:16: Very tiny objects like quantum strings could explore that extra dimension, and importantly, oscillate in it. 02:32: A lot of work went into figuring out a quantum theory for the strong interaction based on the physics of strings. 06:38: But this sort of behavior, where only specific, discrete energy modes are allowed, sounds very quantum-like.
	2018-10-10: Computing a Universe Simulation 00:44: ... or nonexistence like if the tiniest chunks of space time or chunks of quantum field or elements in the abstract space of quantum mechanical states can ... 02:01: That includes most formulations of quantum mechanics and proposals for theories of everything. 06:36: Every quantum state must be processed into the following state. 06:40: There's a fundamental limit to the speed with which quantum states can change. 06:46: ... Margolus-Levitin theorem tells us the maximum rate at which the quantum states of a system can shift into completely independent quantum states ... 07:04: The more energy in the system, the quicker it's quantum states can evolve. 07:16: For example, a simple quantum system would be a group of electrons with spins pointing up or down, corresponding to a single bit the information each. 07:35: This sort of quantum spin array is exactly the system used in most quantum computers. 07:41: ... Margolus-Levitin theorem also gives us the speed limit of operations in quantum computing, in fact, for any computing, but only quantum computing can ... 11:41: ... of physics, in particular very standard ideas on general relativity and quantum mechanics, to figure out the computational properties of our ... 11:53: This will be important as quantum computers develop. 07:35: This sort of quantum spin array is exactly the system used in most quantum computers. 11:53: This will be important as quantum computers develop. 07:41: ... Margolus-Levitin theorem also gives us the speed limit of operations in quantum computing, in fact, for any computing, but only quantum computing can expect to get ... 00:44: ... or nonexistence like if the tiniest chunks of space time or chunks of quantum field or elements in the abstract space of quantum mechanical states can ... 06:46: ... shift into completely independent quantum states or orthogonal states in quantum jargon-- the radius proportional to the average energy of the ... 00:44: ... time or chunks of quantum field or elements in the abstract space of quantum mechanical states can either be full or ... 02:01: That includes most formulations of quantum mechanics and proposals for theories of everything. 11:41: ... of physics, in particular very standard ideas on general relativity and quantum mechanics, to figure out the computational properties of our ... 07:35: This sort of quantum spin array is exactly the system used in most quantum computers. 06:36: Every quantum state must be processed into the following state. 06:40: There's a fundamental limit to the speed with which quantum states can change. 06:46: ... Margolus-Levitin theorem tells us the maximum rate at which the quantum states of a system can shift into completely independent quantum states or ... 07:04: The more energy in the system, the quicker it's quantum states can evolve.
	2018-10-03: How to Detect Extra Dimensions 06:07: ... structures of potentially any number of dimensions on which the quantum field and their corresponding particles can ... 12:23: ... in physics, exploring the conflicts between general relativity and quantum theory towards the development of a theory of quantum ... 12:47: Theories of quantum gravity go in both directions. 13:14: An example is loop quantum gravity. 13:22: If space-time is indefinitely divisible, then you get hopeless conflicts with quantum theory. 14:14: For the simplest attempts at quantum gravity, you need infinite measurements. 14:43: ... quickfire answers-- John Gibbs-- yes, if general relativity and quantum mechanics are both right, then we should have Planck-length virtual ... 14:57: ... the difference between deleting quantum information and just removing it from the universe, e.g., by dropping it ... 06:07: ... structures of potentially any number of dimensions on which the quantum field and their corresponding particles can ... 12:23: ... relativity and quantum theory towards the development of a theory of quantum gravity. ... 12:47: Theories of quantum gravity go in both directions. 13:14: An example is loop quantum gravity. 14:14: For the simplest attempts at quantum gravity, you need infinite measurements. 14:43: ... quickfire answers-- John Gibbs-- yes, if general relativity and quantum mechanics are both right, then we should have Planck-length virtual black holes ... 12:23: ... in physics, exploring the conflicts between general relativity and quantum theory towards the development of a theory of quantum ... 13:22: If space-time is indefinitely divisible, then you get hopeless conflicts with quantum theory.
	2018-09-20: Quantum Gravity and the Hardest Problem in Physics 00:00: [MUSIC PLAYING] MATT O'DOWD: Between them, general relativity and quantum mechanics seem to describe all of observable reality. 00:40: Then the quantum revolution of the '20s and '30s overturned all of our intuitions about the subatomic world. 00:47: Together, general relativity and quantum mechanics have allowed us to explain nearly every fundamental phenomenon observed. 01:12: ... discussion of the great quest for this union, the quest for a theory of quantum gravity and for a theory of ... 01:29: What exactly are the conflicts between general relativity, or GR, and quantum mechanics? 02:17: Where general relativity describes the universe of the large and the massive, quantum mechanics talks about the subatomic world. 03:06: Nowadays, modern quantum field theories fully incorporate the melding of space and time predicted by special relativity. 03:44: That's a big conflict with quantum theory right there, which tells us that quantum information should never be destroyed. 04:14: Hawking, actually, derived the latter by finding a way to unite general relativity and-- in quantum field theory. 04:30: In fact, it's very possible to shoehorn the curved geometry of general relativity into the way quantum field theory deals with space and time. 04:50: For that, you need a true quantum theory of gravity. 07:41: ... that tells us that something is missing in our description of either quantum theory or general relativity, or both, at the smaller ... 07:54: Standard quantum theories treat the fabric of space-time as the underlying arena on which all the weird quantum stuff happens. 08:01: Given that sensible underlying structure, it's relatively routine to apply quantum principles, or quantize, most of the forces of nature. 08:10: For example, classical electromagnetism becomes quantum electrodynamics when you quantize the electron field and the electromagnetic field. 08:19: But in the resulting math, the new quantum fields still lie on top of a smooth, continuous grid of space and time. 09:08: In quantum gravity, gravity itself becomes an excitation in our quantized space-time. 09:26: This type of self-interaction or self-energy is seen in other quantum field theories and is hard to deal with, even there. 09:33: ... example, in quantum electrodynamics, the electron has a self-interaction due to its electric ... 10:05: So perturbation theory is applied throughout quantum field theories of the standard model. 10:31: ... example, measurement of the mass and charge of an electron renormalizes quantum electrodynamics to allow incredibly precise calculation of the ... 10:46: When you have strong gravitational effects on the quantum scale, the self-energy corrections blow up to infinity. 10:53: But unlike other quantum field theories, there are no simple measurements you can do to renormalize those corrections. 11:27: Generations of physicists, starting with Einstein himself, spent their lives trying to fix this to unite quantum mechanics and general relativity. 11:54: ... leading example of this is loop quantum gravity, or you just assume that GR and, indeed, the mutable fabric of ... 12:11: ... crack the greatest problem in modern physics, the quest for a theory of quantum ... 15:27: No real quantum states means no information except, perhaps, whatever information you need to track the bulk properties, like vacuum energy. 08:10: For example, classical electromagnetism becomes quantum electrodynamics when you quantize the electron field and the electromagnetic field. 09:33: ... example, in quantum electrodynamics, the electron has a self-interaction due to its electric charge messing ... 10:31: ... example, measurement of the mass and charge of an electron renormalizes quantum electrodynamics to allow incredibly precise calculation of the electron's ... 03:06: Nowadays, modern quantum field theories fully incorporate the melding of space and time predicted by special relativity. 04:14: Hawking, actually, derived the latter by finding a way to unite general relativity and-- in quantum field theory. 04:30: In fact, it's very possible to shoehorn the curved geometry of general relativity into the way quantum field theory deals with space and time. 09:26: This type of self-interaction or self-energy is seen in other quantum field theories and is hard to deal with, even there. 10:05: So perturbation theory is applied throughout quantum field theories of the standard model. 10:53: But unlike other quantum field theories, there are no simple measurements you can do to renormalize those corrections. 03:06: Nowadays, modern quantum field theories fully incorporate the melding of space and time predicted by special relativity. 09:26: This type of self-interaction or self-energy is seen in other quantum field theories and is hard to deal with, even there. 10:05: So perturbation theory is applied throughout quantum field theories of the standard model. 10:53: But unlike other quantum field theories, there are no simple measurements you can do to renormalize those corrections. 04:14: Hawking, actually, derived the latter by finding a way to unite general relativity and-- in quantum field theory. 04:30: In fact, it's very possible to shoehorn the curved geometry of general relativity into the way quantum field theory deals with space and time. 08:19: But in the resulting math, the new quantum fields still lie on top of a smooth, continuous grid of space and time. 01:12: ... discussion of the great quest for this union, the quest for a theory of quantum gravity and for a theory of ... 09:08: In quantum gravity, gravity itself becomes an excitation in our quantized space-time. 11:54: ... leading example of this is loop quantum gravity, or you just assume that GR and, indeed, the mutable fabric of space-time ... 09:08: In quantum gravity, gravity itself becomes an excitation in our quantized space-time. 00:00: [MUSIC PLAYING] MATT O'DOWD: Between them, general relativity and quantum mechanics seem to describe all of observable reality. 00:47: Together, general relativity and quantum mechanics have allowed us to explain nearly every fundamental phenomenon observed. 01:29: What exactly are the conflicts between general relativity, or GR, and quantum mechanics? 02:17: Where general relativity describes the universe of the large and the massive, quantum mechanics talks about the subatomic world. 11:27: Generations of physicists, starting with Einstein himself, spent their lives trying to fix this to unite quantum mechanics and general relativity. 02:17: Where general relativity describes the universe of the large and the massive, quantum mechanics talks about the subatomic world. 08:01: Given that sensible underlying structure, it's relatively routine to apply quantum principles, or quantize, most of the forces of nature. 00:40: Then the quantum revolution of the '20s and '30s overturned all of our intuitions about the subatomic world. 10:46: When you have strong gravitational effects on the quantum scale, the self-energy corrections blow up to infinity. 12:11: ... crack the greatest problem in modern physics, the quest for a theory of quantum space-time. ... 15:27: No real quantum states means no information except, perhaps, whatever information you need to track the bulk properties, like vacuum energy. 07:54: Standard quantum theories treat the fabric of space-time as the underlying arena on which all the weird quantum stuff happens. 03:44: That's a big conflict with quantum theory right there, which tells us that quantum information should never be destroyed. 04:50: For that, you need a true quantum theory of gravity. 07:41: ... that tells us that something is missing in our description of either quantum theory or general relativity, or both, at the smaller ... 11:54: ... the mutable fabric of space-time itself are emergent phenomena from a quantum theory deeper than our currently accepted ...
	2018-09-12: How Much Information is in the Universe? 00:25: ... stars and galaxies, not to mention space itself, with its fluctuating quantum fields, dark energy, blah blah, stuff ... 03:10: ... we can describe the universe completely if we go through all of its quantum voxels, and answer the yes/no question of whether it's full or ... 04:21: ... will be better to use the number of grid points in a quantum phase space, which includes position, but also other degrees of freedom, ... 04:30: In other words, we should count all possible quantum states in the universe. 04:44: OK, so 10 to the power of 180 or so bits is the minimum if you want to describe every 3D quantum voxel completely independently. 15:41: ... that a metaphor for quantum fluctuations in impossibly distant futures spontaneously generating a ... 00:25: ... stars and galaxies, not to mention space itself, with its fluctuating quantum fields, dark energy, blah blah, stuff ... 15:41: ... that a metaphor for quantum fluctuations in impossibly distant futures spontaneously generating a new big bang by ... 04:21: ... will be better to use the number of grid points in a quantum phase space, which includes position, but also other degrees of freedom, like ... 04:30: In other words, we should count all possible quantum states in the universe. 04:44: OK, so 10 to the power of 180 or so bits is the minimum if you want to describe every 3D quantum voxel completely independently. 03:10: ... we can describe the universe completely if we go through all of its quantum voxels, and answer the yes/no question of whether it's full or ...
	2018-09-05: The Black Hole Entropy Enigma 01:09: They cause all sorts of problems with quantum theory, which we've talked about before and we'll review in a sec. 02:25: But a fundamental tenet of quantum mechanics is that quantum information can never be destroyed. 02:30: ... we also covered, this evaporation should destroy a black hole's internal quantum information, giving us the black hole information ... 05:24: If quantum information is stored on the surface of the black hole, can't we store entropy there also? 08:30: It's as though each of these minimum-possible quanta of area each contain a single bit of information. 02:25: But a fundamental tenet of quantum mechanics is that quantum information can never be destroyed. 01:09: They cause all sorts of problems with quantum theory, which we've talked about before and we'll review in a sec.
	2018-08-23: How Will the Universe End? 04:11: This is matter that is fully collapsed in a quantum mechanical sense. 04:15: It's so densely packed that all possible quantum states are completely filled and no further collapse is possible, short of becoming a black hole. 09:41: The fate of these depends on quantum mechanisms. 09:48: By a process called quantum tunneling, everything eventually reaches the lowest possible energy state. 09:54: ... the remaining matter in the universe, quantum tunneling allows the elements lighter than iron to fuse together, while ... 10:26: The same process of quantum tunneling eventually transport a star's material toward its center. 10:46: Quantum tunneling may actually bring on the Black Hole Era much earlier. 10:53: ... small, stable black holes are possible, then quantum tunneling should allow small regions within larger bodies to collapse ... 12:29: Or quantum fluctuations may spawn new universes from the void. 13:55: ... electron should have been equal to 1 in the classical case and 2 in the quantum ... 15:25: ... the answer is, essentially, that as far as quantum mechanics is concerned, size is a property of composite particles, ... 15:43: All they have is their quantum wave function, which tells the probability of the particle's location, momentum, spin, direction, et cetera. 15:50: Now, we can think of a quantum wave function as having a size because it can be spread out over space. 16:03: If we know with 100% certainty the position of an electron, then the size of its quantum wave function becomes zero. 13:55: ... electron should have been equal to 1 in the classical case and 2 in the quantum case. ... 12:29: Or quantum fluctuations may spawn new universes from the void. 04:11: This is matter that is fully collapsed in a quantum mechanical sense. 15:25: ... the answer is, essentially, that as far as quantum mechanics is concerned, size is a property of composite particles, things that are ... 09:41: The fate of these depends on quantum mechanisms. 04:15: It's so densely packed that all possible quantum states are completely filled and no further collapse is possible, short of becoming a black hole. 09:48: By a process called quantum tunneling, everything eventually reaches the lowest possible energy state. 09:54: ... the remaining matter in the universe, quantum tunneling allows the elements lighter than iron to fuse together, while elements ... 10:26: The same process of quantum tunneling eventually transport a star's material toward its center. 10:46: Quantum tunneling may actually bring on the Black Hole Era much earlier. 10:53: ... small, stable black holes are possible, then quantum tunneling should allow small regions within larger bodies to collapse into black ... 10:26: The same process of quantum tunneling eventually transport a star's material toward its center. 15:43: All they have is their quantum wave function, which tells the probability of the particle's location, momentum, spin, direction, et cetera. 15:50: Now, we can think of a quantum wave function as having a size because it can be spread out over space. 16:03: If we know with 100% certainty the position of an electron, then the size of its quantum wave function becomes zero. 15:43: All they have is their quantum wave function, which tells the probability of the particle's location, momentum, spin, direction, et cetera. 15:50: Now, we can think of a quantum wave function as having a size because it can be spread out over space. 16:03: If we know with 100% certainty the position of an electron, then the size of its quantum wave function becomes zero.
	2018-08-15: Quantum Theory's Most Incredible Prediction 00:07: Let's talk about the best evidence we have to the theories of quantum physics truly represent the underlying workings of reality. 00:17: [MUSIC PLAYING] Quantum field theory is notoriously complicated, built from mind-bendingly abstract mathematics. 00:43: We know this because the predictions of quantum field theory stand up to experimental test time and time again. 00:50: Quantum field theory describes a universe filled with different quantum fields in which particles are excitations, quantized vibrations. 00:59: We've talked about QFT many times before, starting with the very first quantum field theory, quantum electrodynamics. 03:32: As we'll see, their nature is predicted by quantum theory, measure electromagnetic moments, and you verify your quantum picture of reality. 04:02: Nonetheless, electrons do have a sort of intrinsic, angular momentum, a fundamental quantum spin that is as intrinsic as mass and charge. 04:12: Despite not being the same as classical rotation, this quantum spin does grant electrons a dipole magnetic field. 05:23: This difference between the quantum versus classical magnetic moments for the electron is called the G factor. 05:42: This equation is the origin of quantum electrodynamics and the first to correctly capture the notion of quantum spin. 05:49: It describes electrons as weird, four component objects with quantum spin magnitudes of half. 06:19: It doesn't consider the quantum nature of the field. 06:23: Only the fully developed quantum electrodynamics, the first true quantum field theory, does this. 06:29: And QED tells us that the quantum electromagnetic field is a messy, messy place. 06:35: It seethes with a faint quantum buzz, infinite phantom oscillations that add infinite complication to any electromagnetic interaction. 07:13: But in fact, we can calculate its effect extremely precisely and test this through experiments, showing the underlying truth of quantum theory. 07:22: So one way to think about this quantum buzz is with virtual photons. 07:27: Quantum field theory describes the interactions between particles as the sum total of all possible interactions that can lead to the same result. 07:36: In the case of electromagnetism, those interactions are mediated by virtual photons, which are just a mathematical way to describe quantum buzz. 08:02: So yeah, quantum field theory is a type of madness. 08:08: In particular, we've been at Feynman diagrams, which are our best tool for dealing with the absurd complexity of quantum fields. 08:17: They represent the possible interactions of the quantum field by way of virtual photons. 08:54: ... now the electron undergoes an additional interaction with the buzzing quantum ... 10:54: Electron spin axes are always slightly misaligned with an external magnetic field, due to quantum uncertainty in the spin direction. 12:16: The theory of quantum electrodynamics has been pushed to the experimental limit and come out unscathed. 12:23: That means that it and the quantum mechanical principles on which it is founded are good representations of reality. 06:35: It seethes with a faint quantum buzz, infinite phantom oscillations that add infinite complication to any electromagnetic interaction. 07:22: So one way to think about this quantum buzz is with virtual photons. 07:36: In the case of electromagnetism, those interactions are mediated by virtual photons, which are just a mathematical way to describe quantum buzz. 06:35: It seethes with a faint quantum buzz, infinite phantom oscillations that add infinite complication to any electromagnetic interaction. 00:59: We've talked about QFT many times before, starting with the very first quantum field theory, quantum electrodynamics. 05:42: This equation is the origin of quantum electrodynamics and the first to correctly capture the notion of quantum spin. 06:23: Only the fully developed quantum electrodynamics, the first true quantum field theory, does this. 12:16: The theory of quantum electrodynamics has been pushed to the experimental limit and come out unscathed. 06:29: And QED tells us that the quantum electromagnetic field is a messy, messy place. 00:17: [MUSIC PLAYING] Quantum field theory is notoriously complicated, built from mind-bendingly abstract mathematics. 00:43: We know this because the predictions of quantum field theory stand up to experimental test time and time again. 00:50: Quantum field theory describes a universe filled with different quantum fields in which particles are excitations, quantized vibrations. 00:59: We've talked about QFT many times before, starting with the very first quantum field theory, quantum electrodynamics. 06:23: Only the fully developed quantum electrodynamics, the first true quantum field theory, does this. 07:27: Quantum field theory describes the interactions between particles as the sum total of all possible interactions that can lead to the same result. 08:02: So yeah, quantum field theory is a type of madness. 08:17: They represent the possible interactions of the quantum field by way of virtual photons. 08:54: ... now the electron undergoes an additional interaction with the buzzing quantum field. ... 00:17: [MUSIC PLAYING] Quantum field theory is notoriously complicated, built from mind-bendingly abstract mathematics. 00:43: We know this because the predictions of quantum field theory stand up to experimental test time and time again. 00:50: Quantum field theory describes a universe filled with different quantum fields in which particles are excitations, quantized vibrations. 00:59: We've talked about QFT many times before, starting with the very first quantum field theory, quantum electrodynamics. 06:23: Only the fully developed quantum electrodynamics, the first true quantum field theory, does this. 07:27: Quantum field theory describes the interactions between particles as the sum total of all possible interactions that can lead to the same result. 08:02: So yeah, quantum field theory is a type of madness. 00:50: Quantum field theory describes a universe filled with different quantum fields in which particles are excitations, quantized vibrations. 08:08: In particular, we've been at Feynman diagrams, which are our best tool for dealing with the absurd complexity of quantum fields. 12:23: That means that it and the quantum mechanical principles on which it is founded are good representations of reality. 06:19: It doesn't consider the quantum nature of the field. 00:07: Let's talk about the best evidence we have to the theories of quantum physics truly represent the underlying workings of reality. 03:32: As we'll see, their nature is predicted by quantum theory, measure electromagnetic moments, and you verify your quantum picture of reality. 04:02: Nonetheless, electrons do have a sort of intrinsic, angular momentum, a fundamental quantum spin that is as intrinsic as mass and charge. 04:12: Despite not being the same as classical rotation, this quantum spin does grant electrons a dipole magnetic field. 05:42: This equation is the origin of quantum electrodynamics and the first to correctly capture the notion of quantum spin. 05:49: It describes electrons as weird, four component objects with quantum spin magnitudes of half. 03:32: As we'll see, their nature is predicted by quantum theory, measure electromagnetic moments, and you verify your quantum picture of reality. 07:13: But in fact, we can calculate its effect extremely precisely and test this through experiments, showing the underlying truth of quantum theory. 03:32: As we'll see, their nature is predicted by quantum theory, measure electromagnetic moments, and you verify your quantum picture of reality. 10:54: Electron spin axes are always slightly misaligned with an external magnetic field, due to quantum uncertainty in the spin direction. 05:23: This difference between the quantum versus classical magnetic moments for the electron is called the G factor.
	2018-07-25: Reversing Entropy with Maxwell's Demon 11:04: That's quantum entropy, also known as Von Neumann entropy. 11:09: It describes the hidden information in quantum systems, but more accurately, it's a measure of the entanglement within quantum systems. 11:17: ... fact, the evolution of quantum entanglement may be the ultimate source of entropy, the second law, the ... 13:20: ... him think of the game of Life and wonder whether the universe is a giant quantum cellular automata, which led him to a Wikipedia page on digital physics, ... 11:17: ... fact, the evolution of quantum entanglement may be the ultimate source of entropy, the second law, the limits of ... 11:04: That's quantum entropy, also known as Von Neumann entropy. 11:09: It describes the hidden information in quantum systems, but more accurately, it's a measure of the entanglement within quantum systems.
	2018-07-18: The Misunderstood Nature of Entropy 10:22: ... the laws of motion, whether Newtonian or quantum mechanical, don't care about the direction of time, and yet, the second ... 10:45: ... the most profound insights into the working of both the large-scale and quantum ... 10:22: ... the laws of motion, whether Newtonian or quantum mechanical, don't care about the direction of time, and yet, the second law of ... 10:45: ... the most profound insights into the working of both the large-scale and quantum realms. ...
	2018-07-11: Quantum Invariance & The Origin of The Standard Model 00:03: ... theory ever developed, describing with stunning accuracy the fundamental quantum building blocks of our ... 02:24: The standard model is ultimately based on quantum field theory, but we're going to use the Schrodinger equation. 02:31: That's the most basic equation of motion of quantum mechanics. 03:40: The function is an oscillation in quantum possibility, moving through space and time. 04:56: The equations of quantum mechanics have what we call global phase invariance. 08:05: By discovering how it fits into the Schrodinger equation, we've unlocked its quantum behavior. 08:53: At this point, we only need a couple of extra steps to produce the full description of electromagnetism in the quantum world. 09:00: Quantum electrodynamics, or QED. 09:13: ... we need to apply quantum principles to our field, like considering its internal or self energy ... 10:29: ... the greatest mystery here is not the nature of the quantum field nor the connection between symmetry and the fundamental forces, ... 08:05: By discovering how it fits into the Schrodinger equation, we've unlocked its quantum behavior. 00:03: ... theory ever developed, describing with stunning accuracy the fundamental quantum building blocks of our ... 09:00: Quantum electrodynamics, or QED. 02:24: The standard model is ultimately based on quantum field theory, but we're going to use the Schrodinger equation. 10:29: ... the greatest mystery here is not the nature of the quantum field nor the connection between symmetry and the fundamental forces, perhaps ... 02:24: The standard model is ultimately based on quantum field theory, but we're going to use the Schrodinger equation. 02:31: That's the most basic equation of motion of quantum mechanics. 04:56: The equations of quantum mechanics have what we call global phase invariance. 03:40: The function is an oscillation in quantum possibility, moving through space and time. 09:13: ... we need to apply quantum principles to our field, like considering its internal or self energy and allowing ...
	2018-07-04: Will A New Neutrino Change The Standard Model? 02:10: ... of particle physics, electric charge and antimatter, the bizarreness of quantum chirality and the Higgs mechanism, and finally, why all of this points ...
	2018-06-20: The Black Hole Information Paradox 00:12: But that same radiation threatens the very foundations of quantum mechanics. 00:59: The apparent destruction of quantum information by Hawking radiation defies our current understanding of quantum mechanics. 01:33: First, we looked at the law of conservation of quantum information. 01:37: We saw that the very foundations of quantum mechanics demand that quantum information be preserved forever. 02:57: The gravitational field of a black hole is expected to distort the surrounding quantum fields. 03:59: ... his radiation, Stephen Hawking found a way to erase quantum information, which is in severe violation of one of the foundational ... 04:18: After all, without a theory of quantum gravity, Hawking had to hack both general relativity and quantum-field theory to do the calculation. 04:41: ... understand them, then Hawking radiation must exist, and it must erase quantum ... 06:49: To resolve the bet, physicists had to figure out how quantum information could be transferred to Hawking radiation. 07:07: And two, if it did, it would break quantum mechanics as surely as the old information paradox. 07:16: ... turns out that by transferring quantum information to Hawking radiation, you may still violate the law of ... 07:43: Specifically, it would violate the quantum no-cloning theorem. 09:29: This led him to realize that the union of quantum mechanics and gravity may require that the entire 3D universe be a projection on a 2D structure. 10:09: ... Hawking himself has also jumped into that game, suggesting that quantum tunneling from within the black hole could interact with the holographic ... 14:11: Virtual particles in general are just a way to mathematically account for the infinite ways a quantum field can communicate its influence. 02:57: The gravitational field of a black hole is expected to distort the surrounding quantum fields. 04:18: After all, without a theory of quantum gravity, Hawking had to hack both general relativity and quantum-field theory to do the calculation. 00:12: But that same radiation threatens the very foundations of quantum mechanics. 00:59: The apparent destruction of quantum information by Hawking radiation defies our current understanding of quantum mechanics. 01:37: We saw that the very foundations of quantum mechanics demand that quantum information be preserved forever. 07:07: And two, if it did, it would break quantum mechanics as surely as the old information paradox. 09:29: This led him to realize that the union of quantum mechanics and gravity may require that the entire 3D universe be a projection on a 2D structure. 01:37: We saw that the very foundations of quantum mechanics demand that quantum information be preserved forever. 07:43: Specifically, it would violate the quantum no-cloning theorem. 03:59: ... which is in severe violation of one of the foundational tenets of quantum theory. ... 10:09: ... Hawking himself has also jumped into that game, suggesting that quantum tunneling from within the black hole could interact with the holographic horizon ... 04:18: After all, without a theory of quantum gravity, Hawking had to hack both general relativity and quantum-field theory to do the calculation. 04:41: ... So it turns out that if we assume that both general activity and quantum-field theory are correct as we currently understand them, then Hawking ... 05:08: A deeper understanding of general relativity or of quantum-field theory must resolve this. 14:01: But quantum-field theory imagines the electromagnetic force as being transmitted by virtual photons. 04:18: After all, without a theory of quantum gravity, Hawking had to hack both general relativity and quantum-field theory to do the calculation. 04:41: ... So it turns out that if we assume that both general activity and quantum-field theory are correct as we currently understand them, then Hawking radiation must ... 05:08: A deeper understanding of general relativity or of quantum-field theory must resolve this. 14:01: But quantum-field theory imagines the electromagnetic force as being transmitted by virtual photons. 09:16: ... Hooft realized that the three-dimensional gravitational and quantum-mechanical interior of a black hole could be fully described by interactions on a ... 08:11: ... might remember that there are certain pairs of quantum-observable complimentary observables, like position and momentum, that can't both ...
	2018-06-13: What Survives Inside A Black Hole? 01:21: ... conjecture with everything we learned recently about the conservation of quantum ... 10:31: We discussed recently why quantum mechanics demands the conservation of quantum information. 10:37: It's fundamental to quantum mechanics that the universe keeps track of its quantum states, which also means the types of particles it contains. 11:44: In our last episode we looked at what might be the most fundamental rule in quantum mechanics, the conservation of quantum information. 12:28: QFT describes the evolution of quantum fields in which particles are excited states. 12:54: Peter K. asks how the universe can be deterministic given the fundamental probabilistic random nature of the quantum world. 12:28: QFT describes the evolution of quantum fields in which particles are excited states. 10:31: We discussed recently why quantum mechanics demands the conservation of quantum information. 10:37: It's fundamental to quantum mechanics that the universe keeps track of its quantum states, which also means the types of particles it contains. 11:44: In our last episode we looked at what might be the most fundamental rule in quantum mechanics, the conservation of quantum information. 10:31: We discussed recently why quantum mechanics demands the conservation of quantum information. 10:37: It's fundamental to quantum mechanics that the universe keeps track of its quantum states, which also means the types of particles it contains. 12:18: ... particle creation and annihilation is described by quantum-field theory, and unitary evolution and the conservation of probability and ...
	2018-05-23: Why Quantum Information is Never Destroyed 00:36: Newton's equations for classical mechanics, Maxwell's equations for electromagnetism, and the Schrodinger equation for quantum mechanics. 01:16: Today, we learn why conservation of information is such a fundamental requirement of quantum mechanics. 04:33: Actually, quantum mechanics forbids this. 04:45: To get at this, let's think about the basic equation of motion of quantum mechanics. 05:02: ... in quantum mechanics, that means the probability distribution of all of its ... 05:19: ... evolution of a given wave function in any given environment, or in quantum speak, in any given ... 05:51: ... the conservation of information, as do the more advanced formulations of quantum mechanics, like the Dirac equation and quantum field ... 06:49: And this unitarity is a foundational assumption in all formulations of quantum mechanics and quantum field theories. 07:05: ... to explain without getting into some hairy math, but the upshot is that quantum states must remain independent of each other in order to preserve ... 07:16: Two independent quantum states can't evolve into the exact same quantum state. 07:27: ... to our first example, quantum states A and B can't both become quantum state C. The sum of the ... 07:41: The only type of evolution that preserves probability and unitarity is the evolution that also preserves the number of quantum states. 07:49: ... the preservation of quantum states means preservation of information, because you can trace a ... 07:58: But all of this talk of quantum mechanics being deterministic seems a bit at odds with the idea of quantum randomness and the uncertainty principle. 08:26: But that's not really what we mean by quantum information. 08:29: Quantum information refers to the full information content of the wave function, not just what we measure. 08:41: ... the collapse of the wave function in the Copenhagen interpretation of quantum mechanics actually does mess with conservation of ... 09:14: ... interpretations of quantum mechanics, for example, Everett's many-worlds or the de Broglie-Bohm ... 09:43: There is one situation where time-reversibility appears to be broken regardless of your favorite interpretation of quantum mechanics. 09:54: Stephen Hawking's eponymous radiation appears to destroy quantum information leading to the famous black hole information paradox. 10:02: In an upcoming episode, we'll see whether quantum information really can be deleted from the otherwise perfect memory of space time. 13:34: Black hole memory leaks, quantum rounding errors, and it took 10 billion years to compile the first life form. 05:51: ... advanced formulations of quantum mechanics, like the Dirac equation and quantum field ... 06:49: And this unitarity is a foundational assumption in all formulations of quantum mechanics and quantum field theories. 05:51: ... advanced formulations of quantum mechanics, like the Dirac equation and quantum field theories. ... 06:49: And this unitarity is a foundational assumption in all formulations of quantum mechanics and quantum field theories. 00:36: Newton's equations for classical mechanics, Maxwell's equations for electromagnetism, and the Schrodinger equation for quantum mechanics. 01:16: Today, we learn why conservation of information is such a fundamental requirement of quantum mechanics. 04:33: Actually, quantum mechanics forbids this. 04:45: To get at this, let's think about the basic equation of motion of quantum mechanics. 05:02: ... in quantum mechanics, that means the probability distribution of all of its properties, which ... 05:51: ... the conservation of information, as do the more advanced formulations of quantum mechanics, like the Dirac equation and quantum field ... 06:49: And this unitarity is a foundational assumption in all formulations of quantum mechanics and quantum field theories. 07:58: But all of this talk of quantum mechanics being deterministic seems a bit at odds with the idea of quantum randomness and the uncertainty principle. 08:41: ... the collapse of the wave function in the Copenhagen interpretation of quantum mechanics actually does mess with conservation of ... 09:14: ... interpretations of quantum mechanics, for example, Everett's many-worlds or the de Broglie-Bohm pilot wave ... 09:43: There is one situation where time-reversibility appears to be broken regardless of your favorite interpretation of quantum mechanics. 04:33: Actually, quantum mechanics forbids this. 07:58: But all of this talk of quantum mechanics being deterministic seems a bit at odds with the idea of quantum randomness and the uncertainty principle. 13:34: Black hole memory leaks, quantum rounding errors, and it took 10 billion years to compile the first life form. 05:19: ... evolution of a given wave function in any given environment, or in quantum speak, in any given ... 07:16: Two independent quantum states can't evolve into the exact same quantum state. 07:27: ... to our first example, quantum states A and B can't both become quantum state C. The sum of the probabilities prior to the merger would not equal the ... 07:49: ... states means preservation of information, because you can trace a quantum state indefinitely forwards and backwards in ... 07:05: ... to explain without getting into some hairy math, but the upshot is that quantum states must remain independent of each other in order to preserve ... 07:16: Two independent quantum states can't evolve into the exact same quantum state. 07:27: ... to our first example, quantum states A and B can't both become quantum state C. The sum of the probabilities ... 07:41: The only type of evolution that preserves probability and unitarity is the evolution that also preserves the number of quantum states. 07:49: ... the preservation of quantum states means preservation of information, because you can trace a quantum state ...
	2018-05-16: Noether's Theorem and The Symmetries of Reality 06:43: ... of classical mechanics to Feynman's path integral formulation of quantum ... 07:15: As long as we can identify that system's symmetries, this is useful in cosmology, but it's also useful in quantum physics. 07:42: That symmetry is the phase of the quantum field. 07:45: ... can rotate the complex phase of an oscillation in a quantum field by any amount, and the observable properties of that field, like ... 07:59: This quantum symmetry is just the simplest of a large number of symmetries exhibited by quantum fields, the so-called gauge symmetries. 08:14: For example, the color charge of quantum chromodynamics describes the strong interaction between quarks and gluons. 08:26: It's founded on the fundamental symmetries of quantum fields. 09:01: ... Weyl, also a giant in the mathematical foundation of quantum mechanics, said in her memorial address, I was ashamed to occupy such a ... 12:47: ... "Space Time," we only ask that you start with a passing familiarity with quantum physics and the etymological foundations of the languages of ... 08:14: For example, the color charge of quantum chromodynamics describes the strong interaction between quarks and gluons. 07:42: That symmetry is the phase of the quantum field. 07:45: ... can rotate the complex phase of an oscillation in a quantum field by any amount, and the observable properties of that field, like its ... 07:59: This quantum symmetry is just the simplest of a large number of symmetries exhibited by quantum fields, the so-called gauge symmetries. 08:26: It's founded on the fundamental symmetries of quantum fields. 06:43: ... of classical mechanics to Feynman's path integral formulation of quantum mechanics. ... 09:01: ... Weyl, also a giant in the mathematical foundation of quantum mechanics, said in her memorial address, I was ashamed to occupy such a preferred ... 07:15: As long as we can identify that system's symmetries, this is useful in cosmology, but it's also useful in quantum physics. 12:47: ... "Space Time," we only ask that you start with a passing familiarity with quantum physics and the etymological foundations of the languages of ... 07:59: This quantum symmetry is just the simplest of a large number of symmetries exhibited by quantum fields, the so-called gauge symmetries. 06:32: ... Fermat's principal to any object moving on any path or indeed any system quantum-mechanical to cosmological evolving between two ...
	2018-05-02: The Star at the End of Time 06:00: ... helium and will quietly contract into a helium white dwarf, supported by quantum mechanical electron degeneracy ...
	2018-04-25: Black Hole Swarms 11:11: Well, to answer that, I'd need a theory of quantum gravity so let me get back to you.
	2018-04-11: The Physics of Life (ft. It's Okay to be Smart & PBS Eons!) 11:38: That emission looks like a straightforward quantum process, analogous to photon emission by an accelerating electric charge. 11:49: ... there's a type of friction between the accelerating observer and the quantum field which should inhibit that acceleration by creating a type of ... 11:38: That emission looks like a straightforward quantum process, analogous to photon emission by an accelerating electric charge.
	2018-04-04: The Unruh Effect 00:44: They were independently studying how the nature of quantum fields appears to change depending on whether or not an observer is accelerating. 01:00: As we saw in our episode on horizon radiation, the presence of horizons distorts the quantum vacuum in a way that can create particles. 01:19: To understand this, we don't need general relativity with its space-time curvature and conflicts with quantum mechanics. 06:00: And just as with Hawking radiation, that horizon cuts off your access to certain fundamental frequency modes of the quantum vacuum. 08:02: This particle is coupled to the quantum field of interest, meaning it can exchange energy with that field. 08:08: That means the particle can be excited into a higher energy quantum state when it encounters a particle associated with that field. 08:02: This particle is coupled to the quantum field of interest, meaning it can exchange energy with that field. 00:44: They were independently studying how the nature of quantum fields appears to change depending on whether or not an observer is accelerating. 01:19: To understand this, we don't need general relativity with its space-time curvature and conflicts with quantum mechanics. 08:08: That means the particle can be excited into a higher energy quantum state when it encounters a particle associated with that field. 01:00: As we saw in our episode on horizon radiation, the presence of horizons distorts the quantum vacuum in a way that can create particles. 06:00: And just as with Hawking radiation, that horizon cuts off your access to certain fundamental frequency modes of the quantum vacuum.
	2018-03-15: Hawking Radiation 00:20: He made profound contributions across physics from quantum theory to cosmology. 01:31: ... this and in a follow-up 1975 paper, he attempted a new union of quantum mechanics and general relativity to show that black holes should not be ... 02:40: ... if you think you're ready, let's take a deep dive into the quantum field theory of curved space time to glimpse the true nature of Hawking ... 02:52: Space is filled with quantum fields. 03:14: They fluctuate in energy due to quantum uncertainty. 03:25: They're really just a tool for calculating the infinite ways in which a fluctuating quantum field can behave. 03:32: One way that quantum fields are very different to guitar strings is they can have both positive and negative frequencies. 03:51: ... a quantum field is in a vacuum state, there's a balance between positive and ... 04:11: But spatial curvature can mess with the balance of the underlying quantum field modes by introducing horizons. 04:18: Horizons cut off access to certain modes of the quantum fields, disturbing the balance that defines the vacuum. 04:25: Stephen Hawking knew that black holes with their insane spacetime curvature would wreak havoc on quantum fields in their vicinity. 04:35: To answer that properly, he would need a full union of general relativity and quantum mechanics, a theory of quantum gravity, a theory of everything. 05:21: Hawking imagined a simple quantum field tracing this path, a field that is in a perfect vacuum state before the formation of the black hole. 05:54: ... flat space far from the black hole, regions where the nature of vacuums, quantum fields, and particles are perfectly well ... 06:06: But to understand the effect of the close encounter with the black hole, he required an uneasy marriage of quantum mechanics and general relativity. 06:14: In the absence of a theory of quantum gravity, Hawking needed a hack. 06:23: These can be used to approximate the effect of curved spacetime on quantum fields by smoothly connecting regions of flat space. 06:49: Certain modes of the quantum field are scattered or deflected by the gravitational field of the forming black hole. 07:23: The quantum field that emerges is distorted in the same wavelength range. 08:27: And for the escaping modes, there exist a corresponding set of modes linked by quantum entanglement that are trapped behind the event horizon. 09:00: And they tell us that there is an enormous quantum uncertainty in the location of these particles. 10:17: ... thinking about particles escaping from beneath the event horizon through quantum ... 10:29: The common thread is quantum uncertainty. 11:13: Without a full quantum theory of gravity, the origin of Hawking radiation will remain mysterious. 11:32: ... radiation appears to destroy what should be a conserved quantity-- quantum ... 11:49: ... by the brilliant mind of Stephen Hawking and a mysterious quirk of quantum ... 08:27: And for the escaping modes, there exist a corresponding set of modes linked by quantum entanglement that are trapped behind the event horizon. 02:40: ... if you think you're ready, let's take a deep dive into the quantum field theory of curved space time to glimpse the true nature of Hawking ... 03:25: They're really just a tool for calculating the infinite ways in which a fluctuating quantum field can behave. 03:51: ... a quantum field is in a vacuum state, there's a balance between positive and negative ... 04:11: But spatial curvature can mess with the balance of the underlying quantum field modes by introducing horizons. 05:21: Hawking imagined a simple quantum field tracing this path, a field that is in a perfect vacuum state before the formation of the black hole. 06:49: Certain modes of the quantum field are scattered or deflected by the gravitational field of the forming black hole. 07:23: The quantum field that emerges is distorted in the same wavelength range. 04:11: But spatial curvature can mess with the balance of the underlying quantum field modes by introducing horizons. 02:40: ... if you think you're ready, let's take a deep dive into the quantum field theory of curved space time to glimpse the true nature of Hawking ... 05:21: Hawking imagined a simple quantum field tracing this path, a field that is in a perfect vacuum state before the formation of the black hole. 02:52: Space is filled with quantum fields. 03:32: One way that quantum fields are very different to guitar strings is they can have both positive and negative frequencies. 04:18: Horizons cut off access to certain modes of the quantum fields, disturbing the balance that defines the vacuum. 04:25: Stephen Hawking knew that black holes with their insane spacetime curvature would wreak havoc on quantum fields in their vicinity. 05:54: ... flat space far from the black hole, regions where the nature of vacuums, quantum fields, and particles are perfectly well ... 06:23: These can be used to approximate the effect of curved spacetime on quantum fields by smoothly connecting regions of flat space. 04:18: Horizons cut off access to certain modes of the quantum fields, disturbing the balance that defines the vacuum. 04:35: To answer that properly, he would need a full union of general relativity and quantum mechanics, a theory of quantum gravity, a theory of everything. 06:14: In the absence of a theory of quantum gravity, Hawking needed a hack. 01:31: ... this and in a follow-up 1975 paper, he attempted a new union of quantum mechanics and general relativity to show that black holes should not be so black ... 04:35: To answer that properly, he would need a full union of general relativity and quantum mechanics, a theory of quantum gravity, a theory of everything. 06:06: But to understand the effect of the close encounter with the black hole, he required an uneasy marriage of quantum mechanics and general relativity. 11:49: ... by the brilliant mind of Stephen Hawking and a mysterious quirk of quantum spacetime. ... 00:20: He made profound contributions across physics from quantum theory to cosmology. 11:13: Without a full quantum theory of gravity, the origin of Hawking radiation will remain mysterious. 10:17: ... thinking about particles escaping from beneath the event horizon through quantum tunneling. ... 03:14: They fluctuate in energy due to quantum uncertainty. 09:00: And they tell us that there is an enormous quantum uncertainty in the location of these particles. 10:29: The common thread is quantum uncertainty.
	2018-02-28: The Trebuchet Challenge 00:00: [JINGLE PLAYING] Energy is a powerful tool for predicting the behavior of our universe, from quantum to cosmological scales. 03:04: We could get into fluid or stellar dynamics, or even quantum mechanics.
	2018-02-21: The Death of the Sun 03:52: While the stars outer layers of hydrogen are expanding and cooling, the core continues to collapse until it hits a quantum mechanical limit. 04:08: ... rule that says is that fermions, like electrons, can't occupy the same quantum state as each ... 03:52: While the stars outer layers of hydrogen are expanding and cooling, the core continues to collapse until it hits a quantum mechanical limit. 04:08: ... rule that says is that fermions, like electrons, can't occupy the same quantum state as each ...
	2018-02-14: What is Energy? 08:43: The concept of energy is so versatile that Hamilton's approach was even adapted to quantum mechanics. 08:50: ... quantum Hamiltonian operator describes the total energy of a quantum system and ... 09:05: Actually, Lagrangian mechanics makes a quantum comeback here. 09:19: Lagrangian mechanics is the inspiration behind Feynman's path integral approach to quantum mechanics. 09:26: And the Lagrangian quantum field theory is the basis for high-energy particle physics. 09:05: Actually, Lagrangian mechanics makes a quantum comeback here. 08:50: ... equation to complex interactions of particles and fields in quantum field ... 09:26: And the Lagrangian quantum field theory is the basis for high-energy particle physics. 08:50: ... equation to complex interactions of particles and fields in quantum field theories. ... 09:26: And the Lagrangian quantum field theory is the basis for high-energy particle physics. 08:50: ... quantum Hamiltonian operator describes the total energy of a quantum system and allows us to ... 08:43: The concept of energy is so versatile that Hamilton's approach was even adapted to quantum mechanics. 09:19: Lagrangian mechanics is the inspiration behind Feynman's path integral approach to quantum mechanics.
	2018-01-24: The End of the Habitable Zone 11:09: Actually, all quantum fields are affected by the presence of a space time horizon.
	2018-01-17: Horizon Radiation 00:00: ... The most successful theory in physics combines the weirdness of quantum mechanics with, well, the weirdness of special relativity, to give ... 02:22: ... idea of observer dependent particles and vacua, we're going to need some quantum field theory, and we're going to need to draw heavily on this recent ... 02:33: In QFT, we think about each particle type as having its own quantum field that exists at all locations in space. 02:40: If the field vibrates with a single quantum of energy, we see a particle. 03:26: That means everyone has to agree on the fundamental nature of the quantum fields that describe these particles and the way they interact. 03:37: In fact, quantum field theory is what we call Lorentz invariant. 04:08: To see how this happens, we need to think about how particles, interactions, and vacuums are described in quantum field theory. 04:17: Imagine the simplest type of quantum field. 04:42: That oscillator can increase in energy in discrete chunks-- in quanta. 04:47: And we interpret each quantum of energy as representing a single particle. 05:35: Quantum wave functions and quantum fields can be described in terms of variation with position or variations with momentum. 05:56: So let's take our spatial quantum field-- our drum skin, with its single, localized particle, and transform to momentum space. 06:59: Now it starts out with no oscillations, analogous to the vacuum state in quantum field theory. 08:42: There's a nice mechanism in quantum field theory for doing this. 09:46: OK, so what happens when we add a horizon to our infinite quantum field? 11:53: So this year, keep your eye on the horizon-- the event horizon and the strange things it does to the quantum contents of space time. 13:44: ... wonders whether stars may actually be speaking, considering Penrose's quantum brain hypothesis, which states that any sufficiently complex system ... 14:00: ... would be regarding Penrose's idea that neurons perform a sort of quantum computation, and that this is the source of ... 14:17: It feels like it's in the family of, we don't understand it, so it must be quantum mechanics. 13:44: ... wonders whether stars may actually be speaking, considering Penrose's quantum brain hypothesis, which states that any sufficiently complex system creates ... 14:00: ... would be regarding Penrose's idea that neurons perform a sort of quantum computation, and that this is the source of ... 11:53: So this year, keep your eye on the horizon-- the event horizon and the strange things it does to the quantum contents of space time. 00:00: ... mechanics with, well, the weirdness of special relativity, to give quantum field ... 02:22: ... idea of observer dependent particles and vacua, we're going to need some quantum field theory, and we're going to need to draw heavily on this recent ... 02:33: In QFT, we think about each particle type as having its own quantum field that exists at all locations in space. 03:37: In fact, quantum field theory is what we call Lorentz invariant. 04:08: To see how this happens, we need to think about how particles, interactions, and vacuums are described in quantum field theory. 04:17: Imagine the simplest type of quantum field. 05:56: So let's take our spatial quantum field-- our drum skin, with its single, localized particle, and transform to momentum space. 06:59: Now it starts out with no oscillations, analogous to the vacuum state in quantum field theory. 08:42: There's a nice mechanism in quantum field theory for doing this. 09:46: OK, so what happens when we add a horizon to our infinite quantum field? 00:00: ... mechanics with, well, the weirdness of special relativity, to give quantum field theory. ... 02:22: ... idea of observer dependent particles and vacua, we're going to need some quantum field theory, and we're going to need to draw heavily on this recent ... 03:37: In fact, quantum field theory is what we call Lorentz invariant. 04:08: To see how this happens, we need to think about how particles, interactions, and vacuums are described in quantum field theory. 06:59: Now it starts out with no oscillations, analogous to the vacuum state in quantum field theory. 08:42: There's a nice mechanism in quantum field theory for doing this. 03:26: That means everyone has to agree on the fundamental nature of the quantum fields that describe these particles and the way they interact. 05:35: Quantum wave functions and quantum fields can be described in terms of variation with position or variations with momentum. 00:00: ... The most successful theory in physics combines the weirdness of quantum mechanics with, well, the weirdness of special relativity, to give quantum field ... 14:17: It feels like it's in the family of, we don't understand it, so it must be quantum mechanics. 05:35: Quantum wave functions and quantum fields can be described in terms of variation with position or variations with momentum.
	2017-12-06: Understanding the Uncertainty Principle with Quantum Fourier Series 00:07: Sometimes intuitive, large-scale phenomena can give us incredible insights into the extremely unintuitive world of quantum mechanics. 00:16: ... really understanding Heisenberg's uncertainty principle, and ultimately, quantum fields and Hawking ... 00:28: [MUSIC PLAYING] One of the most difficult ideas to swallow in quantum mechanics is Werner Heisenberg's famous uncertainty principle. 00:44: We've discussed it in earlier videos on quantum mechanics, but it's time we looked a little deeper. 01:44: We cannot simultaneously know both position and momentum for a quantum system with absolute precision. 02:10: It's, instead, a statement about how much information we are ever able to extract from a quantum system. 02:16: To understand the origin of the uncertainty principle, we don't need to know any quantum mechanics, at least not to start with. 02:24: See, quantum mechanics is a type of wave mechanics. 06:02: So how does this relate to the quantum world? 06:04: Well, before we get back to quantum fields, let's think about the wave function. 06:09: The solution to the Schrodinger equation that contains all of the information about a quantum system. 06:49: In the early days of quantum mechanics, it was realized that photons are electromagnetic wave packets whose momentum is given by their frequency. 09:43: It's a statement about how much of a quantum system's information is accessible at a fundamental level. 10:12: So what does this old-school quantum mechanics have to do with quantum field theory and Hawking radiation? 10:18: Well, the key to understanding these things is to be able to switch between thinking about quantum fields in terms of position versus momentum. 10:26: ... a single particle, a quantum field vibration, perfectly localized at one spot in space, can so be ... 11:01: ... only by manipulating quantum fields in this strange momentum space, by adding and removing these ... 11:53: Now, our recent discussions about the quantum world are leading up some pretty mind-blowing episodes. 11:59: ... yourself even better, you could check out Benjamin Shoemaker's series, "Quantum Mechanics," which includes a great episode on the uncertainty ... 10:12: So what does this old-school quantum mechanics have to do with quantum field theory and Hawking radiation? 10:26: ... a single particle, a quantum field vibration, perfectly localized at one spot in space, can so be described ... 10:12: So what does this old-school quantum mechanics have to do with quantum field theory and Hawking radiation? 10:26: ... a single particle, a quantum field vibration, perfectly localized at one spot in space, can so be described as ... 00:16: ... really understanding Heisenberg's uncertainty principle, and ultimately, quantum fields and Hawking ... 06:04: Well, before we get back to quantum fields, let's think about the wave function. 10:18: Well, the key to understanding these things is to be able to switch between thinking about quantum fields in terms of position versus momentum. 11:01: ... only by manipulating quantum fields in this strange momentum space, by adding and removing these spatially ... 00:07: Sometimes intuitive, large-scale phenomena can give us incredible insights into the extremely unintuitive world of quantum mechanics. 00:28: [MUSIC PLAYING] One of the most difficult ideas to swallow in quantum mechanics is Werner Heisenberg's famous uncertainty principle. 00:44: We've discussed it in earlier videos on quantum mechanics, but it's time we looked a little deeper. 02:16: To understand the origin of the uncertainty principle, we don't need to know any quantum mechanics, at least not to start with. 02:24: See, quantum mechanics is a type of wave mechanics. 06:49: In the early days of quantum mechanics, it was realized that photons are electromagnetic wave packets whose momentum is given by their frequency. 10:12: So what does this old-school quantum mechanics have to do with quantum field theory and Hawking radiation? 11:59: ... yourself even better, you could check out Benjamin Shoemaker's series, "Quantum Mechanics," which includes a great episode on the uncertainty ... 09:43: It's a statement about how much of a quantum system's information is accessible at a fundamental level. 11:01: ... these spatially infinite particles, that we can describe how the quantum vacuum changes to give us phenomena like Unruh and Hawking radiation, which you ...
	2017-11-29: Citizen Science + Zero-Point Challenge Answer 06:00: There were two, both quizzing you on the zero-point energy of the quantum vacuum. 06:06: The first question was about practical uses of the quantum vacuum. 06:00: There were two, both quizzing you on the zero-point energy of the quantum vacuum. 06:06: The first question was about practical uses of the quantum vacuum.
	2017-11-22: Suicide Space Robots 10:42: ... past couple of episodes have continued discussion of the quantum vacuum and zero-point energy, including some discussion of the ... 11:30: And just quickly regarding the objections of vacuum diagrams to some of my statements in this whole quantum vacuum series-- doctor diagrams, vacuum. 12:00: You say that quantum field theory makes no prediction about the energy of the vacuum. 12:12: QFT may not make a prediction about the zero-point energy, but it does predict the existence of a fluctuating quantum vacuum. 12:34: But as you mention on the subreddit, I'm more of a gravity guy than a quantum guy. 15:07: Now sometimes the path to truth is extremely surprising, like the invariance of the speed of light the quantum nature of subatomic world. 12:00: You say that quantum field theory makes no prediction about the energy of the vacuum. 12:34: But as you mention on the subreddit, I'm more of a gravity guy than a quantum guy. 15:07: Now sometimes the path to truth is extremely surprising, like the invariance of the speed of light the quantum nature of subatomic world. 10:42: ... past couple of episodes have continued discussion of the quantum vacuum and zero-point energy, including some discussion of the pseudoscience ... 11:30: And just quickly regarding the objections of vacuum diagrams to some of my statements in this whole quantum vacuum series-- doctor diagrams, vacuum. 12:12: QFT may not make a prediction about the zero-point energy, but it does predict the existence of a fluctuating quantum vacuum. 11:30: And just quickly regarding the objections of vacuum diagrams to some of my statements in this whole quantum vacuum series-- doctor diagrams, vacuum.
	2017-11-08: Zero-Point Energy Demystified 00:00: ... PLAYING] The mysterious zero-point energy, the quantum vacuum, has been a misrepresented subject of science fiction and ... 00:32: ... is the prediction of quantum field theory, that there exists an energy of the vacuum resulting from ... 01:17: Despite this minor glitch, quantum field theory is arguably the most successful theory in all of physics in terms of sheer predictive power. 01:54: Today I want to debunk some of the nonsense surrounding the quantum vacuum. 03:29: And this would be the case even with an extremely energetic quantum vacuum. 05:46: ... popular use for the quantum vacuum is as a medium to push against for propulsion engine systems, ... 06:10: Virtual particles, and hence, the quantum vacuum, mediate all forces. 06:33: In the case of the EM drive, the proposal is that microwaves within the drive's resonant cavity push against the quantum vacuum. 07:20: That said, the quantum vacuum does have its uses. 07:56: Geckos literally manipulate quantum vacuum energy to climb walls. 08:21: How many geckos do you need to catch and put on a leash in order to drag you up any wall, using only the power of the quantum vacuum? 00:32: ... is the prediction of quantum field theory, that there exists an energy of the vacuum resulting from the ... 01:17: Despite this minor glitch, quantum field theory is arguably the most successful theory in all of physics in terms of sheer predictive power. 00:32: ... is the prediction of quantum field theory, that there exists an energy of the vacuum resulting from the non-zero ... 01:17: Despite this minor glitch, quantum field theory is arguably the most successful theory in all of physics in terms of sheer predictive power. 00:00: ... PLAYING] The mysterious zero-point energy, the quantum vacuum, has been a misrepresented subject of science fiction and pseudoscience ... 01:54: Today I want to debunk some of the nonsense surrounding the quantum vacuum. 03:29: And this would be the case even with an extremely energetic quantum vacuum. 05:46: ... popular use for the quantum vacuum is as a medium to push against for propulsion engine systems, like the ... 06:10: Virtual particles, and hence, the quantum vacuum, mediate all forces. 06:33: In the case of the EM drive, the proposal is that microwaves within the drive's resonant cavity push against the quantum vacuum. 07:20: That said, the quantum vacuum does have its uses. 07:56: Geckos literally manipulate quantum vacuum energy to climb walls. 08:21: How many geckos do you need to catch and put on a leash in order to drag you up any wall, using only the power of the quantum vacuum? 07:56: Geckos literally manipulate quantum vacuum energy to climb walls. 06:10: Virtual particles, and hence, the quantum vacuum, mediate all forces.
	2017-11-02: The Vacuum Catastrophe 00:03: The most successful theory in all of physics is arguably quantum field theory. 00:32: The quantum vacuum is a seething ocean of activity. 00:51: ... tells us that there's a quantum fuzziness in the amount of energy contained at every point in space-- a ... 01:13: Quantum field theory predicts that the energy of the vacuum should be up to 120 orders of magnitude greater than the measured value. 01:30: From the perspective of quantum field theory, every point in space is represented by a quantum oscillator, one for each elementary particle type. 03:24: Until we develop a theory of quantum gravity, we can't say whether the photons above this energy are possible. 03:49: ... even if it were infinite-- we may not notice, at least according to quantum ... 04:12: In fact, in both quantum mechanics and classical mechanics, a particle's equations of motion depend only on changes in energy. 04:39: Long story short-- a crazily high, even infinite, vacuum energy doesn't affect the predictions of quantum field theory. 05:53: ... realization of this fact in the early days of quantum field theory was the beginning of what would become the vacuum ... 07:39: Compare that to the number predicted by quantum field theory. 00:03: The most successful theory in all of physics is arguably quantum field theory. 01:13: Quantum field theory predicts that the energy of the vacuum should be up to 120 orders of magnitude greater than the measured value. 01:30: From the perspective of quantum field theory, every point in space is represented by a quantum oscillator, one for each elementary particle type. 04:39: Long story short-- a crazily high, even infinite, vacuum energy doesn't affect the predictions of quantum field theory. 05:53: ... realization of this fact in the early days of quantum field theory was the beginning of what would become the vacuum catastrophe, ... 07:39: Compare that to the number predicted by quantum field theory. 00:03: The most successful theory in all of physics is arguably quantum field theory. 01:13: Quantum field theory predicts that the energy of the vacuum should be up to 120 orders of magnitude greater than the measured value. 01:30: From the perspective of quantum field theory, every point in space is represented by a quantum oscillator, one for each elementary particle type. 04:39: Long story short-- a crazily high, even infinite, vacuum energy doesn't affect the predictions of quantum field theory. 05:53: ... realization of this fact in the early days of quantum field theory was the beginning of what would become the vacuum catastrophe, but it ... 07:39: Compare that to the number predicted by quantum field theory. 00:51: ... contained at every point in space-- a non-zero zero point energy in the quantum fields that can briefly manifest as ... 03:24: Until we develop a theory of quantum gravity, we can't say whether the photons above this energy are possible. 04:12: In fact, in both quantum mechanics and classical mechanics, a particle's equations of motion depend only on changes in energy. 01:30: From the perspective of quantum field theory, every point in space is represented by a quantum oscillator, one for each elementary particle type. 03:49: ... even if it were infinite-- we may not notice, at least according to quantum theory. ... 00:32: The quantum vacuum is a seething ocean of activity.
	2017-10-19: The Nature of Nothing 01:21: Fix a particle's position, and its momentum, and so its motion, becomes a quantum blur of many possible momenta. 01:55: Our modern understanding of the quantum nature of space is described by quantum field theory. 02:08: In short, space itself is comprised of fundamental quantum fields, one for each elementary particle. 02:28: Now these fields are quantum fields, which means their oscillations can't just have any old energy. 02:41: In each quantum state, so each combination of particle properties, there is a ladder of energy levels, a bit like electron orbitals in an atom. 02:50: Each new rung of the ladder represents the existence of one additional particle in that quantum state. 02:57: In fact, the math of quantum field theory is all about going up and down this particle ladder, using so-called creation and annihilation operators. 03:12: ... bottom of this energy ladder corresponds to these quantum oscillators having no energy, which means there are no particles in a ... 03:51: ... more tightly we try to define the time window for the behavior of a quantum oscillator, the less certain we can be of its energy state in that time ... 04:00: On extremely short time scales, a quantum field exists as a blur of many energy states. 04:20: ... of all particle interactions in the universe, at least as described by quantum field ... 05:24: For example, quantum conservation laws must be obeyed, so most virtual particles are created in particle-antiparticle pairs. 06:23: ... and that no such particles actually exist, or that they are only the quantum possibilities of particles, which somehow govern the interactions of ... 08:20: ... if quantum fields are abuzz with particles popping into and out of existence, then ... 09:32: ... found to be drawn together by a force that matched the predictions of quantum field ... 10:53: ... Quantum field theory, with its dependence on virtual particles and vacuum ... 01:21: Fix a particle's position, and its momentum, and so its motion, becomes a quantum blur of many possible momenta. 05:24: For example, quantum conservation laws must be obeyed, so most virtual particles are created in particle-antiparticle pairs. 01:55: Our modern understanding of the quantum nature of space is described by quantum field theory. 02:57: In fact, the math of quantum field theory is all about going up and down this particle ladder, using so-called creation and annihilation operators. 04:00: On extremely short time scales, a quantum field exists as a blur of many energy states. 04:20: ... of all particle interactions in the universe, at least as described by quantum field ... 09:32: ... found to be drawn together by a force that matched the predictions of quantum field ... 10:53: ... Quantum field theory, with its dependence on virtual particles and vacuum ... 04:00: On extremely short time scales, a quantum field exists as a blur of many energy states. 01:55: Our modern understanding of the quantum nature of space is described by quantum field theory. 02:57: In fact, the math of quantum field theory is all about going up and down this particle ladder, using so-called creation and annihilation operators. 04:20: ... of all particle interactions in the universe, at least as described by quantum field theory. ... 09:32: ... found to be drawn together by a force that matched the predictions of quantum field theory. ... 10:53: ... Quantum field theory, with its dependence on virtual particles and vacuum fluctuations, is one ... 02:08: In short, space itself is comprised of fundamental quantum fields, one for each elementary particle. 02:28: Now these fields are quantum fields, which means their oscillations can't just have any old energy. 08:20: ... if quantum fields are abuzz with particles popping into and out of existence, then the ... 01:55: Our modern understanding of the quantum nature of space is described by quantum field theory. 03:51: ... more tightly we try to define the time window for the behavior of a quantum oscillator, the less certain we can be of its energy state in that time ... 03:12: ... bottom of this energy ladder corresponds to these quantum oscillators having no energy, which means there are no particles in a given quantum ... 06:23: ... and that no such particles actually exist, or that they are only the quantum possibilities of particles, which somehow govern the interactions of real particles ... 02:41: In each quantum state, so each combination of particle properties, there is a ladder of energy levels, a bit like electron orbitals in an atom. 02:50: Each new rung of the ladder represents the existence of one additional particle in that quantum state. 03:12: ... having no energy, which means there are no particles in a given quantum state. ...
	2017-10-11: Absolute Cold 00:11: We'll always have quantum fluctuations to warm our chilly bones. 01:06: Doing so has revealed some bizarre quantum states of matter. 01:11: But quantum mechanics may also prevent us from ever reaching absolute zero. 01:17: Understanding the limit to cold will lead us to an understanding of the nature of the quantum vacuum itself. 02:05: Those particles are quantum creatures. 02:15: This quantum nature is revealed when we look at the spectrum of light produced as those particles hop between energy levels. 02:27: It's mathematical form was our first hint at the quantum nature of the subatomic world. 02:34: The influence of the quantum world becomes far more apparent in the strange states of matter that exist at the cold end of the heat spectrum. 02:53: Once nearly all particles occupy that one quantum state, they share a single, coherent wave function. 04:07: Now bosons are able to occupy the same quantum state as each other unlike the half-integer spin fermions, which cannot. 04:30: The unfreezability of helium reveals an even deeper quantum mystery. 04:59: However, the most fundamental law of quantum mechanics forbids this. 05:11: For example, the more precisely a quantum particle's position is defined, the less defined is its momentum. 05:26: So try to fix a particle's position perfectly, try to hold it still, and its momentum enters a state of quantum haziness. 05:38: At the lowest temperatures, particle motion acquires a sort of quantum buzz. 05:55: We call the lowest possible energy of a quantum system it's zero-point energy. 06:14: All the quantum systems also have non-zero zero points, and that leads to even strange phenomena. 06:21: For example, the quantum fields that fill our universe also fluctuate due to the Uncertainty Principle resulting in what we know as vacuum energy. 06:31: And some quantum fields have an intrinsic non-zero zero point before even bringing Heisenberg into it. 06:56: We'll need another episode to explore the quantum nature of nothing as we peer deeper into the coldest, darkest, and emptiest patches of Space Time. 07:24: For example, Brian Greene's Exploring Quantum History delves much more deeply into the Heisenberg Uncertainty Principle. 05:38: At the lowest temperatures, particle motion acquires a sort of quantum buzz. 02:05: Those particles are quantum creatures. 06:21: For example, the quantum fields that fill our universe also fluctuate due to the Uncertainty Principle resulting in what we know as vacuum energy. 06:31: And some quantum fields have an intrinsic non-zero zero point before even bringing Heisenberg into it. 00:11: We'll always have quantum fluctuations to warm our chilly bones. 05:26: So try to fix a particle's position perfectly, try to hold it still, and its momentum enters a state of quantum haziness. 07:24: For example, Brian Greene's Exploring Quantum History delves much more deeply into the Heisenberg Uncertainty Principle. 01:11: But quantum mechanics may also prevent us from ever reaching absolute zero. 04:59: However, the most fundamental law of quantum mechanics forbids this. 04:30: The unfreezability of helium reveals an even deeper quantum mystery. 02:15: This quantum nature is revealed when we look at the spectrum of light produced as those particles hop between energy levels. 02:27: It's mathematical form was our first hint at the quantum nature of the subatomic world. 06:56: We'll need another episode to explore the quantum nature of nothing as we peer deeper into the coldest, darkest, and emptiest patches of Space Time. 05:11: For example, the more precisely a quantum particle's position is defined, the less defined is its momentum. 02:53: Once nearly all particles occupy that one quantum state, they share a single, coherent wave function. 04:07: Now bosons are able to occupy the same quantum state as each other unlike the half-integer spin fermions, which cannot. 01:06: Doing so has revealed some bizarre quantum states of matter. 06:14: All the quantum systems also have non-zero zero points, and that leads to even strange phenomena. 01:17: Understanding the limit to cold will lead us to an understanding of the nature of the quantum vacuum itself.
	2017-09-28: Are the Fundamental Constants Changing? 03:42: In the language of quantum field theory, it's the coupling strength between the electromagnetic field and a charged field like the electron field. 05:17: Now, quantum spin gives electrons what we call a magnetic moment. 03:42: In the language of quantum field theory, it's the coupling strength between the electromagnetic field and a charged field like the electron field. 05:17: Now, quantum spin gives electrons what we call a magnetic moment.
	2017-09-20: The Future of Space Telescopes 12:14: Basically, the electrons are crammed as close together as quantum mechanics allows.
	2017-09-13: Neutron Stars Collide in New LIGO Signal? 02:22: They are mostly composed of neutrons at the density of an atomic nucleus and are held up by a quantum mechanical force called degeneracy pressure. 02:32: We talk about the bizarre physics of these quantum and gravitational monsters in this video. 02:22: They are mostly composed of neutrons at the density of an atomic nucleus and are held up by a quantum mechanical force called degeneracy pressure.
	2017-08-10: The One-Electron Universe 01:46: ... path integral formulation and the following spacetime interpretation of quantum mechanics, which won him the 1965 Nobel Prize in ... 04:58: In a quantum field theory that's consistent with Einstein's special relativity, all particles must be symmetric under what we call CPT transformation. 06:22: ... anti-matter as time-reversed matter is extremely useful in simplifying quantum field theory calculations, because it massively cuts down the number of ... 04:58: In a quantum field theory that's consistent with Einstein's special relativity, all particles must be symmetric under what we call CPT transformation. 06:22: ... anti-matter as time-reversed matter is extremely useful in simplifying quantum field theory calculations, because it massively cuts down the number of ... 04:58: In a quantum field theory that's consistent with Einstein's special relativity, all particles must be symmetric under what we call CPT transformation. 06:22: ... anti-matter as time-reversed matter is extremely useful in simplifying quantum field theory calculations, because it massively cuts down the number of Feynman ... 01:46: ... path integral formulation and the following spacetime interpretation of quantum mechanics, which won him the 1965 Nobel Prize in ...
	2017-08-02: Dark Flow 09:54: Last week, we talked about the actual rules by which Feynman diagrams can be used to describe real interactions in quantum electrodynamics.
	2017-07-26: The Secrets of Feynman Diagrams 00:42: ... to Feynman's approach to quantum mechanics, every conceivable happening that leads from a measured ... 00:57: To calculate the probability of any quantum system evolving between two states, we need to sum over every conceivable intermediate state. 01:51: Then, you are going to apply them to do some quantum field theory yourself. 02:00: We're going to stick to quantum electrodynamics. 02:02: The first and most predictively powerful quantum field theory, QED, talks about the interaction of the electron field with the electromagnetic field. 10:02: ... fact makes Feynman diagrams an incredibly powerful tool in simplifying quantum field theory calculations, vastly reducing the number of contributing ... 02:00: We're going to stick to quantum electrodynamics. 01:51: Then, you are going to apply them to do some quantum field theory yourself. 02:02: The first and most predictively powerful quantum field theory, QED, talks about the interaction of the electron field with the electromagnetic field. 10:02: ... fact makes Feynman diagrams an incredibly powerful tool in simplifying quantum field theory calculations, vastly reducing the number of contributing ... 01:51: Then, you are going to apply them to do some quantum field theory yourself. 02:02: The first and most predictively powerful quantum field theory, QED, talks about the interaction of the electron field with the electromagnetic field. 10:02: ... fact makes Feynman diagrams an incredibly powerful tool in simplifying quantum field theory calculations, vastly reducing the number of contributing interactions ... 00:42: ... to Feynman's approach to quantum mechanics, every conceivable happening that leads from a measured initial state to ...
	2017-07-19: The Real Star Wars 14:40: ... week when we talked about tricks for solving the impossible equations of quantum field ...
	2017-07-12: Solving the Impossible in Quantum Field Theory 00:06: Quantum field theory is stunningly successful at describing the smallest scales of reality, but its equations are also stunningly complex. 00:27: ... PLAYING] The equations of quantum field theory allow us to calculate the behavior of subatomic particles ... 00:42: ... even the most elegant and complete formulations of quantum field theory, like the Dirac equation or Feynman's path integral, become ... 01:26: ... give you an idea of how messy quantum field theory can be, let's look at what should be a simple phenomenon-- ... 01:58: But in quantum field theory, specifically quantum electrodynamics, or QED, the story is very different. 03:08: ... developed these pictorial tools to organize the painful mathematics of quantum field theory, but they also serve to give a general idea of what these ... 04:24: Unfortunately, real electron scattering at a quantum level is a good deal more complicated than this. 04:45: The quantum event around the scattering is a mystery. 05:53: With infinite possible interactions behind this one simple process, a perfectly complete quantum field theoretic solution is impossible. 06:07: This is the philosophy behind perturbation theory, an absolutely essential tool to solving quantum field theory problems. 08:54: ... try to calculate the self-energy correction to an electron's mass using quantum electrodynamics, you get that the electron has infinite extra ... 09:27: The answer probably lies within a theory of quantum gravity which we don't yet have. 10:27: ... trick can be used to eliminate many of the infinities that arise in quantum field theory-- for example, the infinite shielding of electric charge ... 11:01: Nonetheless, renormalization saved quantum field theory from this plague of infinities. 11:26: ... these rules make Feynman's doodles an incredibly powerful tool for using quantum field theory to predict the behavior of the subatomic ... 12:07: The two-episode documentary "The Ultimate Formula" gives a really nice history of the development of quantum field theory. 13:12: Last week, we talked about Richard Feynman's brilliant contribution to the development of quantum field theory with his path integral formulation. 13:35: So the deal is that Schrodinger's equation is a special case of a more general formulation of quantum mechanics. 01:58: But in quantum field theory, specifically quantum electrodynamics, or QED, the story is very different. 08:54: ... try to calculate the self-energy correction to an electron's mass using quantum electrodynamics, you get that the electron has infinite extra ... 04:45: The quantum event around the scattering is a mystery. 00:06: Quantum field theory is stunningly successful at describing the smallest scales of reality, but its equations are also stunningly complex. 00:27: ... PLAYING] The equations of quantum field theory allow us to calculate the behavior of subatomic particles by ... 00:42: ... even the most elegant and complete formulations of quantum field theory, like the Dirac equation or Feynman's path integral, become ... 01:26: ... give you an idea of how messy quantum field theory can be, let's look at what should be a simple phenomenon-- ... 01:58: But in quantum field theory, specifically quantum electrodynamics, or QED, the story is very different. 03:08: ... developed these pictorial tools to organize the painful mathematics of quantum field theory, but they also serve to give a general idea of what these ... 05:53: With infinite possible interactions behind this one simple process, a perfectly complete quantum field theoretic solution is impossible. 06:07: This is the philosophy behind perturbation theory, an absolutely essential tool to solving quantum field theory problems. 10:27: ... trick can be used to eliminate many of the infinities that arise in quantum field theory-- for example, the infinite shielding of electric charge due to ... 11:01: Nonetheless, renormalization saved quantum field theory from this plague of infinities. 11:26: ... these rules make Feynman's doodles an incredibly powerful tool for using quantum field theory to predict the behavior of the subatomic ... 12:07: The two-episode documentary "The Ultimate Formula" gives a really nice history of the development of quantum field theory. 13:12: Last week, we talked about Richard Feynman's brilliant contribution to the development of quantum field theory with his path integral formulation. 05:53: With infinite possible interactions behind this one simple process, a perfectly complete quantum field theoretic solution is impossible. 00:06: Quantum field theory is stunningly successful at describing the smallest scales of reality, but its equations are also stunningly complex. 00:27: ... PLAYING] The equations of quantum field theory allow us to calculate the behavior of subatomic particles by expressing ... 00:42: ... even the most elegant and complete formulations of quantum field theory, like the Dirac equation or Feynman's path integral, become impossibly ... 01:26: ... give you an idea of how messy quantum field theory can be, let's look at what should be a simple phenomenon-- electron ... 01:58: But in quantum field theory, specifically quantum electrodynamics, or QED, the story is very different. 03:08: ... developed these pictorial tools to organize the painful mathematics of quantum field theory, but they also serve to give a general idea of what these interactions ... 06:07: This is the philosophy behind perturbation theory, an absolutely essential tool to solving quantum field theory problems. 10:27: ... trick can be used to eliminate many of the infinities that arise in quantum field theory-- for example, the infinite shielding of electric charge due to virtual ... 11:01: Nonetheless, renormalization saved quantum field theory from this plague of infinities. 11:26: ... these rules make Feynman's doodles an incredibly powerful tool for using quantum field theory to predict the behavior of the subatomic ... 12:07: The two-episode documentary "The Ultimate Formula" gives a really nice history of the development of quantum field theory. 13:12: Last week, we talked about Richard Feynman's brilliant contribution to the development of quantum field theory with his path integral formulation. 00:27: ... the behavior of subatomic particles by expressing them as vibrations in quantum fields. ... 09:27: The answer probably lies within a theory of quantum gravity which we don't yet have. 04:24: Unfortunately, real electron scattering at a quantum level is a good deal more complicated than this. 13:35: So the deal is that Schrodinger's equation is a special case of a more general formulation of quantum mechanics.
	2017-07-07: Feynman's Infinite Quantum Paths 00:00: ... PLAYING] Quantum mechanics seems to imply that all possible properties, paths, or events ... 00:13: ... description of this crazy idea led to the most powerful expression of quantum mechanics ever devised-- Richard Feynman's path integral ... 01:03: You might also want to catch up on the first two in our quantum field theory playlist because we are going to be building on that. 01:46: There's a story about a quantum mechanics professor explaining the double-slit experiment to a class. 02:45: And he'd just outlined the basics of what was to become the path integral formulation of quantum mechanics. 02:53: But it led to the most elegant formulation of quantum mechanics ever devised and became a key to quantum field theory. 04:28: From that, it was possible for him and others to re-derive all of quantum mechanics. 05:20: However, in the quantum universe, there is no single path. 05:24: Feynman instead used quantum action to assign an importance, a weight, to each of the infinite paths that a single particle could take. 07:51: ... equivalent to and more powerful than earlier derivations of quantum ... 08:37: But Feynman's solution produced a quantum mechanics that didn't need fixing. 08:42: But perhaps the greatest power of the path integral is that it very naturally converts into a true quantum field theory. 09:44: Instead of adding up all possible paths that particles can take, you instead add up all possible histories of quantum fields. 10:04: The quantum action principle gives the probability amplitude of changes in the state of the field. 10:25: ... the quantum field version of path integrals, we can describe all possible paths and ... 12:56: OK, now let's get to your comments on our episode on quantum electrodynamics, the first quantum field theory. 13:04: Jakub asks, what is the difference between the electromagnetic field of quantum field theory and the aether? 15:00: A few of you asked whether quantum field theory and string theory are the same thing. 15:07: Quantum field theory describes particles as a field vibration in 4D space-time. 05:24: Feynman instead used quantum action to assign an importance, a weight, to each of the infinite paths that a single particle could take. 10:04: The quantum action principle gives the probability amplitude of changes in the state of the field. 12:56: OK, now let's get to your comments on our episode on quantum electrodynamics, the first quantum field theory. 01:03: You might also want to catch up on the first two in our quantum field theory playlist because we are going to be building on that. 02:53: But it led to the most elegant formulation of quantum mechanics ever devised and became a key to quantum field theory. 08:42: But perhaps the greatest power of the path integral is that it very naturally converts into a true quantum field theory. 10:25: ... the quantum field version of path integrals, we can describe all possible paths and all ... 12:56: OK, now let's get to your comments on our episode on quantum electrodynamics, the first quantum field theory. 13:04: Jakub asks, what is the difference between the electromagnetic field of quantum field theory and the aether? 15:00: A few of you asked whether quantum field theory and string theory are the same thing. 15:07: Quantum field theory describes particles as a field vibration in 4D space-time. 01:03: You might also want to catch up on the first two in our quantum field theory playlist because we are going to be building on that. 02:53: But it led to the most elegant formulation of quantum mechanics ever devised and became a key to quantum field theory. 08:42: But perhaps the greatest power of the path integral is that it very naturally converts into a true quantum field theory. 12:56: OK, now let's get to your comments on our episode on quantum electrodynamics, the first quantum field theory. 13:04: Jakub asks, what is the difference between the electromagnetic field of quantum field theory and the aether? 15:00: A few of you asked whether quantum field theory and string theory are the same thing. 15:07: Quantum field theory describes particles as a field vibration in 4D space-time. 10:25: ... the quantum field version of path integrals, we can describe all possible paths and all possible ... 09:44: Instead of adding up all possible paths that particles can take, you instead add up all possible histories of quantum fields. 00:00: ... PLAYING] Quantum mechanics seems to imply that all possible properties, paths, or events that could ... 00:13: ... description of this crazy idea led to the most powerful expression of quantum mechanics ever devised-- Richard Feynman's path integral ... 01:46: There's a story about a quantum mechanics professor explaining the double-slit experiment to a class. 02:45: And he'd just outlined the basics of what was to become the path integral formulation of quantum mechanics. 02:53: But it led to the most elegant formulation of quantum mechanics ever devised and became a key to quantum field theory. 04:28: From that, it was possible for him and others to re-derive all of quantum mechanics. 07:51: ... equivalent to and more powerful than earlier derivations of quantum mechanics. ... 08:37: But Feynman's solution produced a quantum mechanics that didn't need fixing. 01:46: There's a story about a quantum mechanics professor explaining the double-slit experiment to a class. 05:20: However, in the quantum universe, there is no single path.
	2017-06-28: The First Quantum Field Theory 00:17: I'm talking about quantum electrodynamics-- the first true quantum field theory. 00:24: [MUSIC PLAYING] Quantum mechanics is perhaps the most unintuitive theory ever devised. 00:41: Simply by following the math of quantum mechanics, incredible discoveries have been made. 00:46: Its wild success tells us that the mathematical description provided by quantum mechanics reflects deep truths about reality. 00:55: And by far the most successful, most predictive formulation of quantum mechanics is quantum field theory. 01:07: And the first part of quantum field theory that was derived, quantum electrodynamics, is the most precise, most accurate of all. 01:18: ... Quantum Field Theory, QFT, describes all elementary particles as vibrational ... 01:30: Quantum ElectroDynamics, QED, provides this description for one such field, the ElectroMagnetic field. 01:55: Now before we start thinking about vibrating quantum fields or even fields at all, let's talk about vibrations. 03:42: OK, let's go quantum. 03:47: If this were a quantum mechanical guitar string, then there'd be a minimum amplitude for the vibration that depended on its frequency. 04:36: The electromagnetic field is a quantum field and so these oscillations have a minimum amplitude. 04:51: Quantum physics may have started with Planck's discovery of the quantum nature of light. 04:56: However, the first full formulation of quantum mechanics was Schrodinger's equation and it couldn't account for light at all. 05:52: It follows the changing position and momentum and generally the physical quantum state of every individual particle but that's extremely inefficient. 06:08: If you take a pair of electrons or photons in two quantum states and make them swap places, then nothing changes. 06:15: ... the quantum state of every individual particle is like trying to do your finances by ... 06:32: But bean counting in this way is not just inefficient in quantum mechanics. 06:38: ... given quantum event or interaction can happen in multiple different ways and the ... 07:31: ... complicated but it has to be built up from a number of minimum amplitude quantum oscillations, which is to say, ... 07:43: So Dirac described a space of quantum states, including position and momentum/frequency, like an infinite array of springs. 07:53: His mathematics, then, kept track of the number of particles, or quantum oscillations, in each of these states. 08:00: ... of the movement of individual photons-- only the shifting number in each quantum ... 08:21: He named the resulting theory quantum electrodynamics. 08:26: He also coined the name second quantization for the process of counting the changing number of quantum oscillations, or particles per state. 08:36: Schrodinger's approach of tracking the changing quantum state of each particle became the first quantization. 09:29: The resulting quantum electrodynamics describes the interactions of matter and radiation with stunning success. 10:26: ... that you can only have one fermion, or electron quark, et cetera, per quantum state, rather than infinite particles in the case of the ... 11:10: This is the postulate of quantum field theory. 11:43: The calculations of QED and of all quantum field theory are about counting the number of ways a quantum phenomenon can occur. 11:58: In fact, a huge part of quantum field theory is about taming the infinities that arise in any calculation. 12:45: ... you want to learn more about the relationship and the conflict between quantum mechanics and relativity, check out the course, The Theory of ... 13:21: Last week, we began our discussion of quantum field theory by looking at the amazing Dirac equation and how it predicts the existence of antimatter. 14:26: ... 100 asks, "Why was it possible to make quantum mechanics compatible with special relativity when we're still struggling ... 14:46: ... work for the infinities you get when you think about curved space on the quantum ... 15:11: And I guess it's possible there are quantum timelines where I missed it on the first attempt but it wasn't this one. 00:17: I'm talking about quantum electrodynamics-- the first true quantum field theory. 01:07: And the first part of quantum field theory that was derived, quantum electrodynamics, is the most precise, most accurate of all. 01:30: Quantum ElectroDynamics, QED, provides this description for one such field, the ElectroMagnetic field. 08:21: He named the resulting theory quantum electrodynamics. 09:29: The resulting quantum electrodynamics describes the interactions of matter and radiation with stunning success. 01:30: Quantum ElectroDynamics, QED, provides this description for one such field, the ElectroMagnetic field. 06:38: ... given quantum event or interaction can happen in multiple different ways and the probability ... 00:17: I'm talking about quantum electrodynamics-- the first true quantum field theory. 00:55: And by far the most successful, most predictive formulation of quantum mechanics is quantum field theory. 01:07: And the first part of quantum field theory that was derived, quantum electrodynamics, is the most precise, most accurate of all. 01:18: ... Quantum Field Theory, QFT, describes all elementary particles as vibrational modes in ... 04:36: The electromagnetic field is a quantum field and so these oscillations have a minimum amplitude. 11:10: This is the postulate of quantum field theory. 11:43: The calculations of QED and of all quantum field theory are about counting the number of ways a quantum phenomenon can occur. 11:58: In fact, a huge part of quantum field theory is about taming the infinities that arise in any calculation. 13:21: Last week, we began our discussion of quantum field theory by looking at the amazing Dirac equation and how it predicts the existence of antimatter. 00:17: I'm talking about quantum electrodynamics-- the first true quantum field theory. 00:55: And by far the most successful, most predictive formulation of quantum mechanics is quantum field theory. 01:07: And the first part of quantum field theory that was derived, quantum electrodynamics, is the most precise, most accurate of all. 01:18: ... Quantum Field Theory, QFT, describes all elementary particles as vibrational modes in ... 11:10: This is the postulate of quantum field theory. 11:43: The calculations of QED and of all quantum field theory are about counting the number of ways a quantum phenomenon can occur. 11:58: In fact, a huge part of quantum field theory is about taming the infinities that arise in any calculation. 13:21: Last week, we began our discussion of quantum field theory by looking at the amazing Dirac equation and how it predicts the existence of antimatter. 01:55: Now before we start thinking about vibrating quantum fields or even fields at all, let's talk about vibrations. 03:47: If this were a quantum mechanical guitar string, then there'd be a minimum amplitude for the vibration that depended on its frequency. 00:24: [MUSIC PLAYING] Quantum mechanics is perhaps the most unintuitive theory ever devised. 00:41: Simply by following the math of quantum mechanics, incredible discoveries have been made. 00:46: Its wild success tells us that the mathematical description provided by quantum mechanics reflects deep truths about reality. 00:55: And by far the most successful, most predictive formulation of quantum mechanics is quantum field theory. 04:56: However, the first full formulation of quantum mechanics was Schrodinger's equation and it couldn't account for light at all. 06:32: But bean counting in this way is not just inefficient in quantum mechanics. 12:45: ... you want to learn more about the relationship and the conflict between quantum mechanics and relativity, check out the course, The Theory of Everything, by ... 14:26: ... 100 asks, "Why was it possible to make quantum mechanics compatible with special relativity when we're still struggling to ... 00:41: Simply by following the math of quantum mechanics, incredible discoveries have been made. 00:46: Its wild success tells us that the mathematical description provided by quantum mechanics reflects deep truths about reality. 04:51: Quantum physics may have started with Planck's discovery of the quantum nature of light. 07:31: ... complicated but it has to be built up from a number of minimum amplitude quantum oscillations, which is to say, ... 07:53: His mathematics, then, kept track of the number of particles, or quantum oscillations, in each of these states. 08:26: He also coined the name second quantization for the process of counting the changing number of quantum oscillations, or particles per state. 11:43: The calculations of QED and of all quantum field theory are about counting the number of ways a quantum phenomenon can occur. 04:51: Quantum physics may have started with Planck's discovery of the quantum nature of light. 14:46: ... work for the infinities you get when you think about curved space on the quantum scale. ... 05:52: It follows the changing position and momentum and generally the physical quantum state of every individual particle but that's extremely inefficient. 06:15: ... the quantum state of every individual particle is like trying to do your finances by ... 08:00: ... of the movement of individual photons-- only the shifting number in each quantum state. ... 08:36: Schrodinger's approach of tracking the changing quantum state of each particle became the first quantization. 10:26: ... that you can only have one fermion, or electron quark, et cetera, per quantum state, rather than infinite particles in the case of the ... 06:08: If you take a pair of electrons or photons in two quantum states and make them swap places, then nothing changes. 07:43: So Dirac described a space of quantum states, including position and momentum/frequency, like an infinite array of springs. 15:11: And I guess it's possible there are quantum timelines where I missed it on the first attempt but it wasn't this one.
	2017-06-21: Anti-Matter and Quantum Relativity 00:24: And the emerging field of quantum mechanics had radically altered our understanding of the fundamental building blocks of the universe. 00:31: Yet, this year, 1928, one brilliant insight would bring these theories together and unveil the quantum fabric of reality. 01:21: ... change over time, and allowed physicists to predict the evolution of quantum systems, such as the strange interference pattern in the famous ... 02:42: But spin does result in a sort of quantum angular momentum. 03:00: The discovery of quantum spin starts with an Austrian physicist named Wolfgang Pauli. 03:16: It states that no electron can occupy the same quantum state as another electron. 03:24: In the case of electrons in atoms, it suggests that we should only find one electron per atomic orbital, if we count each orbital as a quantum state. 03:38: And so Pauli realized there must exist a hidden quantum state. 03:53: ... down, to occupy the same atomic energy level, without occupying the same quantum state and therefore violating the Pauli exclusion ... 04:05: ... physicists soon figured out that this new quantum state represented spin and the up and down degrees of freedom were the ... 05:02: He then used quantum mechanical expressions for energy and momentum. 05:55: It contains the marks of both quantum mechanics, in the Planck constant, and relativity, in the speed of light. 08:31: But it was one of the first attempts to describe something very real, the idea of a quantum field. 09:02: Now, quantum field theory is a very deep topic. 09:34: Well, it's a vibration in the same quantum field as its regular matter counterpart. 10:20: So all elementary particles have a quantum field and all have an anti-matter counterpart. 10:53: ... incredible insight in combining quantum mechanics and relativity reveal an entire flip side of our universe, ... 11:03: ... was also a key step in the discovery of quantum field and quantum field theory and the development of the standard model ... 11:17: And that's a quantum rabbit hole that we'll jump into very soon, right here on "SpaceTime." I'd like to thank Skillshare for sponsoring this episode. 15:04: This is the "Quantum Divide" by Chris Gerry and Kimberley Bruno. 15:08: It explores the key concepts in quantum physics through a description of the most important quantum experiments ever made. 02:42: But spin does result in a sort of quantum angular momentum. 15:04: This is the "Quantum Divide" by Chris Gerry and Kimberley Bruno. 15:08: It explores the key concepts in quantum physics through a description of the most important quantum experiments ever made. 00:31: Yet, this year, 1928, one brilliant insight would bring these theories together and unveil the quantum fabric of reality. 08:31: But it was one of the first attempts to describe something very real, the idea of a quantum field. 09:02: Now, quantum field theory is a very deep topic. 09:34: Well, it's a vibration in the same quantum field as its regular matter counterpart. 10:20: So all elementary particles have a quantum field and all have an anti-matter counterpart. 11:03: ... was also a key step in the discovery of quantum field and quantum field theory and the development of the standard model of ... 09:02: Now, quantum field theory is a very deep topic. 11:03: ... was also a key step in the discovery of quantum field and quantum field theory and the development of the standard model of particle physics, which ... 05:02: He then used quantum mechanical expressions for energy and momentum. 00:24: And the emerging field of quantum mechanics had radically altered our understanding of the fundamental building blocks of the universe. 05:55: It contains the marks of both quantum mechanics, in the Planck constant, and relativity, in the speed of light. 10:53: ... incredible insight in combining quantum mechanics and relativity reveal an entire flip side of our universe, with its ... 15:08: It explores the key concepts in quantum physics through a description of the most important quantum experiments ever made. 11:17: And that's a quantum rabbit hole that we'll jump into very soon, right here on "SpaceTime." I'd like to thank Skillshare for sponsoring this episode. 03:00: The discovery of quantum spin starts with an Austrian physicist named Wolfgang Pauli. 03:16: It states that no electron can occupy the same quantum state as another electron. 03:24: In the case of electrons in atoms, it suggests that we should only find one electron per atomic orbital, if we count each orbital as a quantum state. 03:38: And so Pauli realized there must exist a hidden quantum state. 03:53: ... down, to occupy the same atomic energy level, without occupying the same quantum state and therefore violating the Pauli exclusion ... 04:05: ... physicists soon figured out that this new quantum state represented spin and the up and down degrees of freedom were the ... 01:21: ... change over time, and allowed physicists to predict the evolution of quantum systems, such as the strange interference pattern in the famous double-slit ...
	2017-06-07: Supervoids vs Colliding Universes! 02:22: We think that they came from random quantum fluctuations from the very first instant after the Big Bang.
	2017-05-03: Are We Living in an Ancestor Simulation? ft. Neil deGrasse Tyson 03:43: Let's avoid the idea that the entire universe is simulated, right down to every atom, electron, or vibrating quantum field. 14:04: The truth of that statement depends on which interpretation of quantum mechanics you want to go with. 03:43: Let's avoid the idea that the entire universe is simulated, right down to every atom, electron, or vibrating quantum field. 14:04: The truth of that statement depends on which interpretation of quantum mechanics you want to go with.
	2017-03-29: How Time Becomes Space Inside a Black Hole 11:53: It refers to any quantum systems whose internal interactions result in a periodic change from one state to another and then back again.
	2017-03-15: Time Crystals! 03:23: ... arguments that time translational symmetry can't be broken by a quantum system in ... 04:07: These atoms have spin values, quantum mechanical angular momenta from their electrons. 08:30: Time crystals could have their first application in quantum computing. 08:34: ... the most popular approach to building a quantum computing memory element is to use electron spins, which can represent ... 08:45: One of the most serious challenges is that these quantum states are really hard to maintain. 09:00: Time crystals with their resilient spin-flip cycle could be the next step in building stable quantum memory. 09:08: Time crystals could also help bridge the gap between quantum mechanics and general relativity. 09:21: And unlike in relativity, quantum mechanics treats space and time very differently to each other. 09:29: ... in time just like in regular crystals, perhaps it's a first step in a quantum union of space ... 08:30: Time crystals could have their first application in quantum computing. 08:34: ... the most popular approach to building a quantum computing memory element is to use electron spins, which can represent the ones ... 04:07: These atoms have spin values, quantum mechanical angular momenta from their electrons. 09:08: Time crystals could also help bridge the gap between quantum mechanics and general relativity. 09:21: And unlike in relativity, quantum mechanics treats space and time very differently to each other. 09:00: Time crystals with their resilient spin-flip cycle could be the next step in building stable quantum memory. 08:45: One of the most serious challenges is that these quantum states are really hard to maintain. 09:29: ... in time just like in regular crystals, perhaps it's a first step in a quantum union of space ...
	2017-01-11: The EM Drive: Fact or Fantasy? 06:56: This isn't something we can get into properly without first doing some quantum field theory, so I'll keep it brief. 07:02: The paper invokes pilot wave theory as a way to justify treating the quantum vacuum as a sort of plasma with which it can exchange momentum. 07:19: Our understanding of the quantum vacuum in standard quantum field theory doesn't allow you to push off it, like you might row a boat on a lake. 07:59: Instead, they invoke pilot wave theory to justify treating the quantum vacuum as a deformable medium. 08:05: ... which he argues demonstrates that such a medium can reproduce certain quantum observables, like the energy levels of the hydrogen ... 08:18: ... the quantum vacuum is some sort of almost classical medium, then they argue that the ... 08:29: ... very different than described by the otherwise amazingly successful quantum field ... 09:01: A distant third is that it's something brand new, like this quantum vacuum stuff. 06:56: This isn't something we can get into properly without first doing some quantum field theory, so I'll keep it brief. 07:19: Our understanding of the quantum vacuum in standard quantum field theory doesn't allow you to push off it, like you might row a boat on a lake. 08:29: ... very different than described by the otherwise amazingly successful quantum field ... 06:56: This isn't something we can get into properly without first doing some quantum field theory, so I'll keep it brief. 07:19: Our understanding of the quantum vacuum in standard quantum field theory doesn't allow you to push off it, like you might row a boat on a lake. 08:29: ... very different than described by the otherwise amazingly successful quantum field theory. ... 08:05: ... which he argues demonstrates that such a medium can reproduce certain quantum observables, like the energy levels of the hydrogen ... 07:02: The paper invokes pilot wave theory as a way to justify treating the quantum vacuum as a sort of plasma with which it can exchange momentum. 07:19: Our understanding of the quantum vacuum in standard quantum field theory doesn't allow you to push off it, like you might row a boat on a lake. 07:59: Instead, they invoke pilot wave theory to justify treating the quantum vacuum as a deformable medium. 08:18: ... the quantum vacuum is some sort of almost classical medium, then they argue that the ... 09:01: A distant third is that it's something brand new, like this quantum vacuum stuff.
	2016-12-08: What Happens at the Event Horizon? 15:57: In the Copenhagen interpretation, the uncertainty principle describes the intrinsic randomness of the quantum world. 18:47: ... just don't know whether the reality that drives the strange results of quantum experiments is actually deterministic in the way that we understand ... 18:57: ... theory can at least go some way towards predicting the results of quantum ... 19:07: Personally, I'm agnostic towards the relative truth behind the Copenhagen, many-worlds, pilot wave, or the other interpretations of quantum mechanics. 18:47: ... just don't know whether the reality that drives the strange results of quantum experiments is actually deterministic in the way that we understand ... 18:57: ... theory can at least go some way towards predicting the results of quantum experiments. ... 19:07: Personally, I'm agnostic towards the relative truth behind the Copenhagen, many-worlds, pilot wave, or the other interpretations of quantum mechanics.
	2016-11-30: Pilot Wave Theory and Quantum Realism 00:00: ... PLAYING] There is one interpretation of the meaning of quantum mechanics that somehow manages to skip a lot of the wildly extravagant ... 00:26: ... PLAYING] Misinterpretation of the ideas of quantum mechanics has spawned some of the worst quackery pseudoscience hoo-ha ... 00:47: There are some pretty out there explanations for the processes at work behind the incredibly successful mathematics of quantum mechanics. 01:13: The weird results of quantum experiments seem to demand weird explanations of the nature of reality. 01:19: But there is one interpretation of quantum mechanics that remains comfortably, almost stodgily, physical. 01:47: Pilot-wave theory is perhaps the most solidly physical, even mundane, of the complete and self-consistent interpretations of quantum mechanics. 02:08: And the founding fathers of the Copenhagen interpretation of quantum mechanics-- Niels Bohr and Werner Heisenberg-- were radicals. 02:16: ... quantum theory was coming together in the '20s, they were fervent about the need ... 03:11: ... and Heisenberg there needed to be a full theory that described how a quantum object could show both wave and particle-like behavior at the same time ... 03:25: ... that matter could be described as waves right at the beginning of the quantum ... 03:36: De Broglie's theory reasoned that there was no need for quantum objects to transition in a mystical way between non-real waves and real particles. 04:13: That's the equation at the heart of all quantum mechanics that tells the wave function how to change across space and time. 04:21: This means that pilot-wave theory makes the same basic predictions as any other breed of quantum mechanics. 06:21: See, although pilot-wave theory makes all of the usual predictions of quantum mechanics, it has some really fundamental differences. 08:00: But hidden variables have a bad rap in quantum mechanics. 09:39: But quantum entanglement experiments show that this sort of "spooky" action at a distance is a very real phenomenon. 10:17: But we see many of the familiar quantum phenomena appear in this macroscopic system of a suspended oil droplet following its own pilot-wave. 10:56: While regular mechanics has quantum field theory as its relativistic version, pilot-wave theory hasn't quite got there yet. 11:05: Quantum field theory pretty explicitly requires that all possible particle trajectories be considered equally real. 11:21: This is not consistent with quantum field theory, and so there isn't a complete relativistic formulation of Bohmian mechanics yet. 11:33: Now let's not even start talking about gravity-- no version of quantum mechanics has that sorted out. 11:55: ... it shows us that it's possible to have a consistent interpretation of quantum mechanics that is both physical and deterministic, no hoo-ha ... 09:39: But quantum entanglement experiments show that this sort of "spooky" action at a distance is a very real phenomenon. 01:13: The weird results of quantum experiments seem to demand weird explanations of the nature of reality. 02:16: ... all classical thinking in interpreting the strange results of early quantum experiments. ... 10:56: While regular mechanics has quantum field theory as its relativistic version, pilot-wave theory hasn't quite got there yet. 11:05: Quantum field theory pretty explicitly requires that all possible particle trajectories be considered equally real. 11:21: This is not consistent with quantum field theory, and so there isn't a complete relativistic formulation of Bohmian mechanics yet. 10:56: While regular mechanics has quantum field theory as its relativistic version, pilot-wave theory hasn't quite got there yet. 11:05: Quantum field theory pretty explicitly requires that all possible particle trajectories be considered equally real. 11:21: This is not consistent with quantum field theory, and so there isn't a complete relativistic formulation of Bohmian mechanics yet. 00:00: ... PLAYING] There is one interpretation of the meaning of quantum mechanics that somehow manages to skip a lot of the wildly extravagant or ... 00:26: ... PLAYING] Misinterpretation of the ideas of quantum mechanics has spawned some of the worst quackery pseudoscience hoo-ha and ... 00:47: There are some pretty out there explanations for the processes at work behind the incredibly successful mathematics of quantum mechanics. 01:19: But there is one interpretation of quantum mechanics that remains comfortably, almost stodgily, physical. 01:47: Pilot-wave theory is perhaps the most solidly physical, even mundane, of the complete and self-consistent interpretations of quantum mechanics. 02:08: And the founding fathers of the Copenhagen interpretation of quantum mechanics-- Niels Bohr and Werner Heisenberg-- were radicals. 04:13: That's the equation at the heart of all quantum mechanics that tells the wave function how to change across space and time. 04:21: This means that pilot-wave theory makes the same basic predictions as any other breed of quantum mechanics. 06:21: See, although pilot-wave theory makes all of the usual predictions of quantum mechanics, it has some really fundamental differences. 08:00: But hidden variables have a bad rap in quantum mechanics. 11:33: Now let's not even start talking about gravity-- no version of quantum mechanics has that sorted out. 11:55: ... it shows us that it's possible to have a consistent interpretation of quantum mechanics that is both physical and deterministic, no hoo-ha ... 02:08: And the founding fathers of the Copenhagen interpretation of quantum mechanics-- Niels Bohr and Werner Heisenberg-- were radicals. 03:11: ... and Heisenberg there needed to be a full theory that described how a quantum object could show both wave and particle-like behavior at the same time without ... 03:36: De Broglie's theory reasoned that there was no need for quantum objects to transition in a mystical way between non-real waves and real particles. 10:17: But we see many of the familiar quantum phenomena appear in this macroscopic system of a suspended oil droplet following its own pilot-wave. 03:25: ... that matter could be described as waves right at the beginning of the quantum revolution. ... 02:16: ... quantum theory was coming together in the '20s, they were fervent about the need to ...
	2016-11-16: Strange Stars 01:02: What happens to the resulting ultra-dense material depends on quantum theory. 01:08: ... already talked about how quantum processes save a neutron star from collapse, but ultimately also doom ... 01:18: But just shy of that final transition, and on the fringe of our understanding of the quantum universe, a star may become very strange indeed. 03:19: Degenerate matter is so compressed that particles can't get any closer together without occupying the same quantum states. 05:40: It has three quark types instead of two, and that means more particles can occupy the lowest quantum energy states. 01:08: ... already talked about how quantum processes save a neutron star from collapse, but ultimately also doom the most ... 03:19: Degenerate matter is so compressed that particles can't get any closer together without occupying the same quantum states. 01:02: What happens to the resulting ultra-dense material depends on quantum theory. 01:18: But just shy of that final transition, and on the fringe of our understanding of the quantum universe, a star may become very strange indeed.
	2016-11-09: Did Dark Energy Just Disappear? 13:17: I want to respond to some of your thoughts on both colonizing Mars, as well as on the Many Worlds interpretation of quantum mechanics.
	2016-11-02: Quantum Vortices and Superconductivity + Drake Equation Challenge Answers 00:02: ... three researchers for major breakthroughs in understanding the strange quantum behavior of very, very cold ... 00:44: However, at extremely cold temperatures, this thermal motion is so small that quantum effects can dominate the behavior of certain materials. 00:53: Thouless, Kosterlitz, and Haldane massively advanced our understanding of these quantum phases by showing how topology drives this weird behavior. 02:11: ... behind a strange quantized magnetic field observed in the mysterious "quantum hole effect." These findings will lead to some spectacular applications ... 02:36: ... are very likely, and it may even be possible to build a topological quantum computer that uses entanglement between ... 00:02: ... three researchers for major breakthroughs in understanding the strange quantum behavior of very, very cold ... 02:36: ... are very likely, and it may even be possible to build a topological quantum computer that uses entanglement between ... 00:44: However, at extremely cold temperatures, this thermal motion is so small that quantum effects can dominate the behavior of certain materials. 02:11: ... behind a strange quantized magnetic field observed in the mysterious "quantum hole effect." These findings will lead to some spectacular applications in ... 00:53: Thouless, Kosterlitz, and Haldane massively advanced our understanding of these quantum phases by showing how topology drives this weird behavior.
	2016-10-26: The Many Worlds of the Quantum Multiverse 00:09: A huge outstanding question is when and why does the weirdness of quantum mechanics give way to classical physics. 00:27: [MUSIC PLAYING] One of the strangest features of the quantum description of reality is the idea of superposition. 00:53: Mathematically, this is encapsulated in the wave function of a quantum particle or system of particles. 01:00: The best illustration of why we need to describe the quantum world this way is the famous double-slit experiment. 01:24: Quantum mechanics very successfully predicts this result by describing each particle's journey as a superposition of all possible trajectories. 02:04: ... the original Copenhagen interpretation of quantum mechanics, the act of measurement was thought to collapse possibility ... 02:19: That collapse signifies the transition between the quantum and classical realms. 02:24: One of the founders of quantum mechanics, Erwin Schrodinger, found this ridiculous. 02:51: That radioactive decay is a purely quantum process. 03:04: But doesn't that mean that the entire macroscopic system attached to that quantum event is also in superposition? 03:22: And from its point of view, is the physicist outside also a quantum blur until the box is opened? 03:42: It's that quantum superposition doesn't extend to macroscopic scales. 03:48: It disappears when different quantum scale histories diverge. 03:55: ... the wave functions describing quantum systems overlap sufficiently-- in other words, they are coherent-- it's ... 05:06: However, there is another way to interpret the transition between the quantum and classical worlds. 05:33: ... box and find that the cat is alive, it's because we're part of an entire quantum timeline in which the radioactive decay and subsequent poisoning never ... 05:52: This sounds outrageous, but it's a very serious interpretation of the mathematics of quantum mechanics. 07:07: ... invites the idea that reality splits into different branches every time quantum states diverge into different possibilities-- for example, at every ... 07:43: But remember, the Copenhagen interpretation itself proposes multiple worlds in the superposition of paths or properties of a quantum system. 08:18: ... may, in fact, be the more pure interpretation of the mathematics of quantum mechanics because there's nothing in that math that requires the ... 08:29: ... is more economical in the number of unsupported concepts it adds to quantum mechanics, even if it isn't particularly economical in the number of ... 09:29: There's no more evidence for many worlds than there is for other mainstream interpretations of quantum mechanics. 09:47: ... so although it is supported by the incredibly successful mathematics of quantum mechanics, it has not yet added a prediction that might distinguish it ... 10:23: It explains the apparent randomness of quantum mechanics with a sort of observer bias. 03:22: And from its point of view, is the physicist outside also a quantum blur until the box is opened? 00:27: [MUSIC PLAYING] One of the strangest features of the quantum description of reality is the idea of superposition. 03:55: ... get interference in the double-slit experiment and spookily correlated quantum entanglement ... 03:04: But doesn't that mean that the entire macroscopic system attached to that quantum event is also in superposition? 00:09: A huge outstanding question is when and why does the weirdness of quantum mechanics give way to classical physics. 01:24: Quantum mechanics very successfully predicts this result by describing each particle's journey as a superposition of all possible trajectories. 02:04: ... the original Copenhagen interpretation of quantum mechanics, the act of measurement was thought to collapse possibility space into a ... 02:24: One of the founders of quantum mechanics, Erwin Schrodinger, found this ridiculous. 05:52: This sounds outrageous, but it's a very serious interpretation of the mathematics of quantum mechanics. 08:18: ... may, in fact, be the more pure interpretation of the mathematics of quantum mechanics because there's nothing in that math that requires the collapse of the ... 08:29: ... is more economical in the number of unsupported concepts it adds to quantum mechanics, even if it isn't particularly economical in the number of universes it ... 09:29: There's no more evidence for many worlds than there is for other mainstream interpretations of quantum mechanics. 09:47: ... so although it is supported by the incredibly successful mathematics of quantum mechanics, it has not yet added a prediction that might distinguish it from other ... 10:23: It explains the apparent randomness of quantum mechanics with a sort of observer bias. 02:24: One of the founders of quantum mechanics, Erwin Schrodinger, found this ridiculous. 00:53: Mathematically, this is encapsulated in the wave function of a quantum particle or system of particles. 02:51: That radioactive decay is a purely quantum process. 03:48: It disappears when different quantum scale histories diverge. 07:07: ... invites the idea that reality splits into different branches every time quantum states diverge into different possibilities-- for example, at every particle ... 03:42: It's that quantum superposition doesn't extend to macroscopic scales. 03:55: ... the wave functions describing quantum systems overlap sufficiently-- in other words, they are coherent-- it's possible ... 05:33: ... box and find that the cat is alive, it's because we're part of an entire quantum timeline in which the radioactive decay and subsequent poisoning never ...
	2016-10-12: Black Holes from the Dawn of Time 02:43: Back then, quantum fluctuations caused a sort of static fuzz across the minuscule cosmos.
	2016-09-29: Life on Europa? 09:31: ... next week on "Space Time." Last week we talked about the weirdness of quantum entanglement and the implications its results have for the nature of ... 09:57: ... between the predictions of a local hidden variable theory versus pure quantum mechanics is if you measure the spins of both particles with the same ... 10:10: In that case, the pure quantum, no-hidden-variable prediction is that you'll always measure opposite spins. 10:29: ... one spin in one direction and the other at 90 degrees, then the pure quantum prediction is that the second particle is aligned one way 50% of the ... 11:13: So I've done this in a couple of the quantum videos before, but it bears repeating. 11:18: The definition of observer sort of depends on what interpretation of quantum mechanics you're going with. 11:30: Rather, observation may just mean any interaction that destroys quantum coherence between the entangled particles. 11:37: ... with a macroscopic system so complex that we no longer observe clean quantum ... 11:30: Rather, observation may just mean any interaction that destroys quantum coherence between the entangled particles. 11:37: ... with a macroscopic system so complex that we no longer observe clean quantum effects. ... 09:31: ... next week on "Space Time." Last week we talked about the weirdness of quantum entanglement and the implications its results have for the nature of ... 09:57: ... between the predictions of a local hidden variable theory versus pure quantum mechanics is if you measure the spins of both particles with the same measurement ... 11:18: The definition of observer sort of depends on what interpretation of quantum mechanics you're going with. 10:10: In that case, the pure quantum, no-hidden-variable prediction is that you'll always measure opposite spins. 10:29: ... one spin in one direction and the other at 90 degrees, then the pure quantum prediction is that the second particle is aligned one way 50% of the time and the ... 11:13: So I've done this in a couple of the quantum videos before, but it bears repeating.
	2016-09-21: Quantum Entanglement and the Great Bohr-Einstein Debate 00:00: [MUSIC PLAYING] Is there a hidden physical reality that underlies the strange behavior of the quantum world? 00:12: The weird phenomenon of quantum entanglement gives us quite startling clues to the answer. 00:25: But they're actually surprisingly good at quantum mechanics. 01:27: But quantum mechanics is so bizarre that it still has scientists wondering if we need to reject even this basic premise. 01:34: This was the source of one of the most heated debates at the advent of quantum mechanics. 01:48: ... the intervals between measurement, quantum systems truly exist as a fuzzy mixture of all possible properties-- what ... 02:29: He insisted that the wave function, and by extension quantum mechanics, is incomplete. 02:40: ... idea, Einstein along with Doris Podolsky and Nathan Rosen proposed a quantum scenario that showed that in order to abandon the assumption of realism, ... 03:13: The Einstein Podolsky Rosen, or EPR, paradox introduces one of the most mysterious ideas in quantum mechanics-- quantum entanglement. 03:30: And yet we refrain from measuring these properties to preserve quantum uncertainty. 03:36: ... Quantum mechanics requires that we describe the particle pair with a single ... 05:10: But in quantum mechanics, measurement actually affects the thing you are measuring. 05:15: In the case of quantum spin, that measurement effect is especially weird. 05:31: We always find that the observed quantum spin aligns itself with our chosen measurement axis. 07:13: ... that we'd expect to see in the case that Einstein was right and quantum mechanics needs local hidden ... 07:42: It's a tricky experiment because entangled quantum states are hard to produce, but even harder to sustain. 08:41: ... delayed choice quantum eraser, which we already covered, is yet another example of this strange ... 09:02: Do we live in a peekaboo universe that vanishes into quantum abstraction when we aren't looking at it? 09:09: Are babies really better at quantum mechanics than Einstein? 10:04: ... those measurements are compared, just as we saw with the delayed choice quantum ... 10:23: The Copenhagen interpretation remains consistent with all quantum observations. 09:02: Do we live in a peekaboo universe that vanishes into quantum abstraction when we aren't looking at it? 00:12: The weird phenomenon of quantum entanglement gives us quite startling clues to the answer. 03:13: The Einstein Podolsky Rosen, or EPR, paradox introduces one of the most mysterious ideas in quantum mechanics-- quantum entanglement. 08:41: ... delayed choice quantum eraser, which we already covered, is yet another example of this strange result. ... 10:04: ... those measurements are compared, just as we saw with the delayed choice quantum eraser. ... 00:25: But they're actually surprisingly good at quantum mechanics. 01:27: But quantum mechanics is so bizarre that it still has scientists wondering if we need to reject even this basic premise. 01:34: This was the source of one of the most heated debates at the advent of quantum mechanics. 02:29: He insisted that the wave function, and by extension quantum mechanics, is incomplete. 03:13: The Einstein Podolsky Rosen, or EPR, paradox introduces one of the most mysterious ideas in quantum mechanics-- quantum entanglement. 03:36: ... Quantum mechanics requires that we describe the particle pair with a single combined wave ... 05:10: But in quantum mechanics, measurement actually affects the thing you are measuring. 07:13: ... that we'd expect to see in the case that Einstein was right and quantum mechanics needs local hidden ... 09:09: Are babies really better at quantum mechanics than Einstein? 05:10: But in quantum mechanics, measurement actually affects the thing you are measuring. 03:13: The Einstein Podolsky Rosen, or EPR, paradox introduces one of the most mysterious ideas in quantum mechanics-- quantum entanglement. 03:36: ... Quantum mechanics requires that we describe the particle pair with a single combined wave function ... 10:23: The Copenhagen interpretation remains consistent with all quantum observations. 02:40: ... idea, Einstein along with Doris Podolsky and Nathan Rosen proposed a quantum scenario that showed that in order to abandon the assumption of realism, you also ... 05:15: In the case of quantum spin, that measurement effect is especially weird. 05:31: We always find that the observed quantum spin aligns itself with our chosen measurement axis. 07:42: It's a tricky experiment because entangled quantum states are hard to produce, but even harder to sustain. 01:48: ... the intervals between measurement, quantum systems truly exist as a fuzzy mixture of all possible properties-- what we call ... 03:30: And yet we refrain from measuring these properties to preserve quantum uncertainty.
	2016-09-07: Is There a Fifth Fundamental Force? + Quantum Eraser Answer 02:06: That transition meant a difference in energy, but also a difference in some of the quantum stuff, spin parity and isospin. 03:59: OK, on to the solution to the quantum eraser challenge. 04:03: ... impossible to send any real data back in time using the delayed choice quantum eraser experiment, and so cheat on the ... 06:59: But there's still time for a mini-rant about the role of consciousness in quantum mechanics. 03:59: OK, on to the solution to the quantum eraser challenge. 04:03: ... impossible to send any real data back in time using the delayed choice quantum eraser experiment, and so cheat on the ... 03:59: OK, on to the solution to the quantum eraser challenge. 04:03: ... impossible to send any real data back in time using the delayed choice quantum eraser experiment, and so cheat on the ... 06:59: But there's still time for a mini-rant about the role of consciousness in quantum mechanics. 02:06: That transition meant a difference in energy, but also a difference in some of the quantum stuff, spin parity and isospin.
	2016-08-24: Should We Build a Dyson Sphere? 10:58: ... I travel and then coming back the following week with the answer to the quantum eraser lottery challenge and some intriguing physics ... 11:36: A couple of weeks ago, we talked about the mysterious delayed choice quantum eraser. 13:17: We'll go into all of this in more detail in the challenge question answer and also when we come back to quantum entanglement. 10:58: ... I travel and then coming back the following week with the answer to the quantum eraser lottery challenge and some intriguing physics ... 11:36: A couple of weeks ago, we talked about the mysterious delayed choice quantum eraser. 10:58: ... I travel and then coming back the following week with the answer to the quantum eraser lottery challenge and some intriguing physics ...
	2016-08-17: Quantum Eraser Lottery Challenge 00:00: [MUSIC PLAYING] The quantum eraser experiment tantalizes us with the apparent instantaneous flow of information between entangled photon pairs. 00:11: In fact, the delayed choice quantum eraser seems to show that information can travel backwards in time. 00:31: First, though, you really should go back and watch that quantum eraser episode, unless you memory is incredible. 05:12: ... detailed explanation to PBSSpaceTime@gmail.com with the subject line "Quantum Eraser Challenge Question." Be sure to use exactly these words because ... 00:00: [MUSIC PLAYING] The quantum eraser experiment tantalizes us with the apparent instantaneous flow of information between entangled photon pairs. 00:11: In fact, the delayed choice quantum eraser seems to show that information can travel backwards in time. 00:31: First, though, you really should go back and watch that quantum eraser episode, unless you memory is incredible. 05:12: ... detailed explanation to PBSSpaceTime@gmail.com with the subject line "Quantum Eraser Challenge Question." Be sure to use exactly these words because we ... 00:31: First, though, you really should go back and watch that quantum eraser episode, unless you memory is incredible. 00:00: [MUSIC PLAYING] The quantum eraser experiment tantalizes us with the apparent instantaneous flow of information between entangled photon pairs.
	2016-08-10: How the Quantum Eraser Rewrites the Past 00:09: That's the unsettling implication of the delayed choice quantum eraser experiment. 06:26: This is quantum mechanics. 06:29: This extra stuff is the quantum eraser. 08:57: Now the delayed choice quantum eraser double slit experiment doesn't tell us whether the wave function is physical or not. 09:15: In fact, the solution may lie in this fascinating phenomenon of quantum entanglement. 00:09: That's the unsettling implication of the delayed choice quantum eraser experiment. 06:29: This extra stuff is the quantum eraser. 08:57: Now the delayed choice quantum eraser double slit experiment doesn't tell us whether the wave function is physical or not. 00:09: That's the unsettling implication of the delayed choice quantum eraser experiment. 06:26: This is quantum mechanics.
	2016-08-03: Can We Survive the Destruction of the Earth? ft. Neal Stephenson 12:21: Well, wave functions for macroscopic objects are incredibly complicated because they're comprised of countless quantum particles. 13:03: Some of you wondered why we didn't talk about what happens when you try to measure which slit the particle went through or talk about quantum eraser. 12:21: Well, wave functions for macroscopic objects are incredibly complicated because they're comprised of countless quantum particles.
	2016-07-27: The Quantum Experiment that Broke Reality 00:13: It's one of the most stunning illustrations of how the quantum world is very, very different from the large-scale world of our physical intuition. 05:47: We also saw this waviness in position when we talked about quantum tunneling. 05:52: In fact, several quantum properties, like momentum, energy, and spin, all display similar waviness in different situations. 06:00: ... function." Describing the behavior of the wave function is the heart of quantum ... 07:42: In fact, the answers aren't known but the various interpretations of quantum mechanics do try. 07:49: Let's talk about the view favored by Werner Heisenberg and Niels Bohr, who pioneered quantum mechanics at the University of Copenhagen in the 1920s. 09:36: ... theory of quantum mechanics produces stunningly accurate predictions of reality and it's ... 09:54: ... we know that light is a wave in the electromagnetic field and quantum field theory tells us that all fundamental particles are waves in their ... 10:50: I have recently been exploring The Great Courses Plus quantum mechanics content. 09:54: ... we know that light is a wave in the electromagnetic field and quantum field theory tells us that all fundamental particles are waves in their own ... 06:00: ... function." Describing the behavior of the wave function is the heart of quantum mechanics. ... 07:42: In fact, the answers aren't known but the various interpretations of quantum mechanics do try. 07:49: Let's talk about the view favored by Werner Heisenberg and Niels Bohr, who pioneered quantum mechanics at the University of Copenhagen in the 1920s. 09:36: ... theory of quantum mechanics produces stunningly accurate predictions of reality and it's completely ... 10:50: I have recently been exploring The Great Courses Plus quantum mechanics content. 09:36: ... theory of quantum mechanics produces stunningly accurate predictions of reality and it's completely ... 05:52: In fact, several quantum properties, like momentum, energy, and spin, all display similar waviness in different situations. 05:47: We also saw this waviness in position when we talked about quantum tunneling.
	2016-07-20: The Future of Gravitational Waves 06:49: And that's actually close to the number you get from doing this with quantum mechanics so that's cool.
	2016-07-06: Juno to Reveal Jupiter's Violent Past 10:28: We recently talked about the origin of quantum theory with Max Planck's derivation of an equation to describe the black body spectrum. 11:33: A few of you rightly know that quantum mechanics isn't needed to resolve Zeno's paradox of Achilles and the tortoise. 10:28: We recently talked about the origin of quantum theory with Max Planck's derivation of an equation to describe the black body spectrum.
	2016-06-29: Nuclear Physics Challenge 00:06: We've been talking about quantum mechanics recently, and I think we're ready to do a bit of recreational nuclear physics. 00:13: A few episodes ago, we delved into quantum tunneling. 00:31: One consequence of this uncertainty in position is the phenomenon of quantum tunneling. 00:06: We've been talking about quantum mechanics recently, and I think we're ready to do a bit of recreational nuclear physics. 00:13: A few episodes ago, we delved into quantum tunneling. 00:31: One consequence of this uncertainty in position is the phenomenon of quantum tunneling.
	2016-06-22: Planck's Constant and The Origin of Quantum Mechanics 00:03: ... physics of our macroscopic reality gives way to the weirdness of the quantum ... 00:15: You might not expect the quantum behavior of the microscopic to be observable on all scales of the universe, but it is. 00:23: In fact, you can see the effect of this quantum behavior and even measure the Planck constant just by observing the color of sunlight. 01:14: As your distance to the tortoise becomes unthinkably small, there arises a quantum uncertainty in your location. 01:22: Get close enough to it, and this quantum blurriness means it's impossible to say whether your location is really behind or in front of the tortoise. 01:45: The tiny Planck constant, at 6.63 by 10 to the minus 34 joule seconds, sets the scale of this quantum blurriness. 01:59: In many ways, it defines the divisibility of the quantum world. 02:04: In fact, the Planck constant appears in essentially all equations that describe quantum phenomena. 02:36: It may define the scale of quantum reality, but the influence of the Planck constant can be seen even on our scale. 02:56: In fact, the mystery of why hot things glow the color that they do led us to discover the quantum universe in the first place. 04:23: But he didn't realize that the relative brightnesses of those colors held the key to the quantum world. 09:52: ... the existence of the photon-- part wave, part particle, carrying a quantum of energy equal to the now familiar frequency of the wave times the ... 10:20: These discoveries sparked a frenzy of sciencing that led to the quantum revolution of the 1920s. 10:27: And that little number that Max Planck came up with in his moment of desperation-- the Planck constant-- remains at the heart of all things quantum. 10:36: But not just quantum. 00:15: You might not expect the quantum behavior of the microscopic to be observable on all scales of the universe, but it is. 00:23: In fact, you can see the effect of this quantum behavior and even measure the Planck constant just by observing the color of sunlight. 01:22: Get close enough to it, and this quantum blurriness means it's impossible to say whether your location is really behind or in front of the tortoise. 01:45: The tiny Planck constant, at 6.63 by 10 to the minus 34 joule seconds, sets the scale of this quantum blurriness. 02:04: In fact, the Planck constant appears in essentially all equations that describe quantum phenomena. 02:36: It may define the scale of quantum reality, but the influence of the Planck constant can be seen even on our scale. 10:20: These discoveries sparked a frenzy of sciencing that led to the quantum revolution of the 1920s. 01:14: As your distance to the tortoise becomes unthinkably small, there arises a quantum uncertainty in your location. 02:56: In fact, the mystery of why hot things glow the color that they do led us to discover the quantum universe in the first place.
	2016-06-15: The Strange Universe of Gravitational Lensing 09:51: We recently started talking about quantum physics by looking at the bizarre phenomena of quantum tunneling. 10:05: ... can't quantum tunnel to the moon, because to properly tunnel, you need to ... 10:54: ... of possible locations is only true for the Copenhagen interpretation of quantum ... 11:19: ... interpretation was one of the early interpretations of some of the weird quantum effects developed in the ... 12:30: Mystyc Cheez and others ask, what is really meant by an observation in quantum mechanics? 12:39: ... a quantum system means doing something to it that collapses its wave function into ... 12:58: ... so hopelessly mixed with those of other particles that its observable quantum behavior can't be ... 11:19: ... interpretation was one of the early interpretations of some of the weird quantum effects developed in the ... 10:54: ... of possible locations is only true for the Copenhagen interpretation of quantum mechanics. ... 12:30: Mystyc Cheez and others ask, what is really meant by an observation in quantum mechanics? 09:51: We recently started talking about quantum physics by looking at the bizarre phenomena of quantum tunneling. 10:05: ... can't quantum tunnel to the moon, because to properly tunnel, you need to spontaneously find ... 09:51: We recently started talking about quantum physics by looking at the bizarre phenomena of quantum tunneling.
	2016-06-01: Is Quantum Tunneling Faster than Light? 00:08: According to quantum mechanics you are, at least a little bit. 00:12: [THEME MUSIC] Quantum mechanics is a spectacularly weird theory. 00:41: ... more accurately, until a quantum object interacts with something, all possible states are just as real as ... 00:52: There is a distribution of probabilities for each of an object's quantum properties. 01:19: For now, let's just look at the strange consequences of quantum uncertainty in an object's location. 01:26: This is one of the early realizations in the development of quantum theory. 03:33: But quantum objects aren't at all like balls. 04:38: This process is called quantum tunneling. 04:48: Quantum tunneling also goes in the other direction. 04:52: Protons, neutrons, electrons, and alpha particles can quantum tunnel into nuclei in various types of fusion and particle capture phenomena. 05:01: In fact, without quantum tunneling, stars could not fuse hydrogen into heavy nuclei. 06:11: In the absence of quantum tunneling, that barrier should reflect its photon 100% of the time. 07:04: To make that work you need to use a second, and perhaps even weirder feature of quantum mechanics, quantum entanglement. 08:13: Well, this apparent violation of relativity only occurs deep within the quantum realm. 09:28: But in the quantum realm, Heisenberg uncertainty does seem to allow instantaneous motion, and even perhaps causality violation within quantum limits. 09:39: Stay tuned for the implications of this on both quantum and cosmic scales of space time. 07:04: To make that work you need to use a second, and perhaps even weirder feature of quantum mechanics, quantum entanglement. 09:28: But in the quantum realm, Heisenberg uncertainty does seem to allow instantaneous motion, and even perhaps causality violation within quantum limits. 00:08: According to quantum mechanics you are, at least a little bit. 00:12: [THEME MUSIC] Quantum mechanics is a spectacularly weird theory. 07:04: To make that work you need to use a second, and perhaps even weirder feature of quantum mechanics, quantum entanglement. 00:41: ... more accurately, until a quantum object interacts with something, all possible states are just as real as each ... 03:33: But quantum objects aren't at all like balls. 00:52: There is a distribution of probabilities for each of an object's quantum properties. 08:13: Well, this apparent violation of relativity only occurs deep within the quantum realm. 09:28: But in the quantum realm, Heisenberg uncertainty does seem to allow instantaneous motion, and even perhaps causality violation within quantum limits. 01:26: This is one of the early realizations in the development of quantum theory. 04:52: Protons, neutrons, electrons, and alpha particles can quantum tunnel into nuclei in various types of fusion and particle capture phenomena. 04:38: This process is called quantum tunneling. 04:48: Quantum tunneling also goes in the other direction. 05:01: In fact, without quantum tunneling, stars could not fuse hydrogen into heavy nuclei. 06:11: In the absence of quantum tunneling, that barrier should reflect its photon 100% of the time. 05:01: In fact, without quantum tunneling, stars could not fuse hydrogen into heavy nuclei. 01:19: For now, let's just look at the strange consequences of quantum uncertainty in an object's location.
	2016-03-02: What’s Wrong With the Big Bang Theory? 04:20: See, at this point, general relativity comes into serious conflict with quantum mechanics. 04:26: And we need a theory of quantum gravity, a so-called theory of everything, to go further. 04:20: See, at this point, general relativity comes into serious conflict with quantum mechanics.
	2016-02-24: Why the Big Bang Definitely Happened 02:56: While general relativity is incredibly successful, it doesn't contain the machinery to describe the quantum scale gravity of that first speck.
	2016-02-03: Will Mars or Venus Kill You First? 10:11: For one thing, we don't have a theory of quantum gravity to get us into the Planck era.
	2016-01-27: The Origin of Matter and Time 07:28: We're extrapolating the validity of space time diagrams, and these tiny lifelike segments into the quantum realm. 10:04: ... basic vibrations of their quantum fields-- the time that the electron or quark feels-- is felt by the ... 07:28: We're extrapolating the validity of space time diagrams, and these tiny lifelike segments into the quantum realm.
	2016-01-06: The True Nature of Matter and Mass 09:32: There's a quantum blur surrounding the current state of the electron.
	2015-12-16: The Higgs Mechanism Explained 01:01: To understand how all this works, we're going to need to learn a bit of quantum field theory. 02:02: ... its incredible success, it was strange that quantum field theory, as it stood in the 1950s, gave a perfect description of ... 02:35: ... has this type of intrinsic quantum spin that we call chirality, and this can either be clockwise or ... 05:06: While most quantum fields hover around zero in empty space, the Higgs field has a positive strength at all points in the universe. 05:17: ... some stunning quantum weirdness, this complex, multi-component field not only carries the weak ... 06:04: Well, something like this must be true, because all of the rest of quantum field theory hangs together too well. 01:01: To understand how all this works, we're going to need to learn a bit of quantum field theory. 02:02: ... its incredible success, it was strange that quantum field theory, as it stood in the 1950s, gave a perfect description of the ... 06:04: Well, something like this must be true, because all of the rest of quantum field theory hangs together too well. 01:01: To understand how all this works, we're going to need to learn a bit of quantum field theory. 02:02: ... its incredible success, it was strange that quantum field theory, as it stood in the 1950s, gave a perfect description of the electron, ... 06:04: Well, something like this must be true, because all of the rest of quantum field theory hangs together too well. 05:06: While most quantum fields hover around zero in empty space, the Higgs field has a positive strength at all points in the universe. 02:35: ... has this type of intrinsic quantum spin that we call chirality, and this can either be clockwise or ... 05:17: ... some stunning quantum weirdness, this complex, multi-component field not only carries the weak ...
	2015-12-09: How to Build a Black Hole 00:06: To make one, we need both general relativity and quantum mechanics. 01:04: We need quantum mechanics. 02:33: Now, beneath the thin atmosphere of ion plasma, a neutron star is a quantum mechanical entity. 02:39: And it's a quantum phenomenon that saves it, for the moment, from final collapse. 02:44: It's also a different quantum phenomenon that will let us push it over the edge, creating a black hole. 02:51: ... understand how space works for a quantum object like this, we need to think not in regular 3D space or even 4D ... 03:15: ... the exact way that the matter of a neutron star fills this 6D quantum phase space depends on two important principles of quantum theory, the ... 03:48: Now, by place, I mean location in quantum phase space. 03:52: So two fermions can apply the same physical location just fine, as long as their momenta or any other quantum property is different. 04:53: Two fermions just can't ever occupy the same quantum state. 05:04: Fortunately, there's another quantum phenomenon that let's us get around the Pauli exclusion principle. 05:10: The Heisenberg uncertainty principle tells us that the properties of a quantum entity are fundamentally uncertain. 05:17: The details may be a topic for another episode, but in short, quantum mechanics describes matter as a distribution of possibilities. 05:55: This is the weirdest, coolest aspect of quantum mechanics. 07:31: This is a quantum effect, even though it's happening on the scale of a star. 05:10: The Heisenberg uncertainty principle tells us that the properties of a quantum entity are fundamentally uncertain. 02:33: Now, beneath the thin atmosphere of ion plasma, a neutron star is a quantum mechanical entity. 00:06: To make one, we need both general relativity and quantum mechanics. 01:04: We need quantum mechanics. 05:17: The details may be a topic for another episode, but in short, quantum mechanics describes matter as a distribution of possibilities. 05:55: This is the weirdest, coolest aspect of quantum mechanics. 05:17: The details may be a topic for another episode, but in short, quantum mechanics describes matter as a distribution of possibilities. 02:51: ... understand how space works for a quantum object like this, we need to think not in regular 3D space or even 4D space ... 03:15: ... the exact way that the matter of a neutron star fills this 6D quantum phase space depends on two important principles of quantum theory, the Pauli ... 03:48: Now, by place, I mean location in quantum phase space. 02:51: ... regular 3D space or even 4D space time but, rather, in six dimensional quantum phase space. ... 03:15: ... the exact way that the matter of a neutron star fills this 6D quantum phase space depends on two important principles of quantum theory, the Pauli ... 03:48: Now, by place, I mean location in quantum phase space. 02:39: And it's a quantum phenomenon that saves it, for the moment, from final collapse. 02:44: It's also a different quantum phenomenon that will let us push it over the edge, creating a black hole. 05:04: Fortunately, there's another quantum phenomenon that let's us get around the Pauli exclusion principle. 03:52: So two fermions can apply the same physical location just fine, as long as their momenta or any other quantum property is different. 04:53: Two fermions just can't ever occupy the same quantum state. 03:15: ... fills this 6D quantum phase space depends on two important principles of quantum theory, the Pauli exclusion principle and the Heisenberg uncertainty ...
	2015-10-28: Is The Alcubierre Warp Drive Possible? 03:44: We can create something like it, a negative pressure, on quantum scales via Casimir effect. 04:04: Except Stephen Hawking chronology protection conjecture states that quantum mechanics will always stop causality-breaking actions. 04:13: It suggests that there's something in the deeper union of GR and quantum mechanics, the theory of everything, that prohibits the warp drive. 04:21: One possible quantum disaster is that the extreme spacetime curvature of the warp bubble walls would roast the interior with crazy Hawking radiation. 06:02: Quantum scale manipulation of the vacuum energy a la the Casimir effect may be enough. 08:32: Quantum mechanics began as an abstract musing on the nature of reality. 08:36: ... that this crazy theory would lead to the invention of the transistor, a quantum mechanical device, let alone the computer, the smartphone, the Apple ... 04:21: One possible quantum disaster is that the extreme spacetime curvature of the warp bubble walls would roast the interior with crazy Hawking radiation. 08:36: ... that this crazy theory would lead to the invention of the transistor, a quantum mechanical device, let alone the computer, the smartphone, the Apple ... 04:04: Except Stephen Hawking chronology protection conjecture states that quantum mechanics will always stop causality-breaking actions. 04:13: It suggests that there's something in the deeper union of GR and quantum mechanics, the theory of everything, that prohibits the warp drive. 08:32: Quantum mechanics began as an abstract musing on the nature of reality. 06:02: Quantum scale manipulation of the vacuum energy a la the Casimir effect may be enough. 03:44: We can create something like it, a negative pressure, on quantum scales via Casimir effect.
	2015-10-22: Have Gravitational Waves Been Discovered?!? 06:08: Even quantum fluctuations in the photon rate causes noise.
	2015-10-15: 5 REAL Possibilities for Interstellar Travel 11:50: Jai Kolra and others ask, what about quantum entanglement?
	2015-10-07: The Speed of Light is NOT About Light 02:26: The first clues to the bizarre quantum nature of reality had emerged.
	2015-09-23: Does Dark Matter BREAK Physics? 06:58: Sinking down into the depths of quantum field and string theory, you can find all sorts of strange fish, WIMPs, axions, neutralinos.
	2015-08-19: Do Events Inside Black Holes Happen? 00:24: That means no Hawking radiation, no string theory, and no quantum anything-- baby steps.
	2015-08-05: What Physics Teachers Get Wrong About Tides! 10:09: ... may have heard that in quantum field theory, forces are described as being mediated by some kind of ... 10:33: ... field, you're quantization something different when you talk about the quantum version of general ... 10:53: ... when you start looking at very small scales, like what the quantum version of gravity tells you on very small scales or very high energies, ... 11:07: But from the philosophical perspective of quantum field theory, you should be able to quantize anything. 11:41: ... field theory versions of something and then add to them the machinery of quantum mechanics to sort of get a quantized version of the ... 10:09: ... may have heard that in quantum field theory, forces are described as being mediated by some kind of particle ... 11:07: But from the philosophical perspective of quantum field theory, you should be able to quantize anything. 10:09: ... may have heard that in quantum field theory, forces are described as being mediated by some kind of particle like ... 11:07: But from the philosophical perspective of quantum field theory, you should be able to quantize anything. 11:41: ... field theory versions of something and then add to them the machinery of quantum mechanics to sort of get a quantized version of the ... 10:33: ... field, you're quantization something different when you talk about the quantum version of general ... 10:53: ... when you start looking at very small scales, like what the quantum version of gravity tells you on very small scales or very high energies, that a ...
	2015-04-29: What's the Most Realistic Artificial Gravity in Sci-Fi? 10:30: Does quantum mechanics bring back free will since it attaches some inherent randomness to the future.

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