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	2022-12-14: How Can Matter Be BOTH Liquid AND Gas? 01:14: But high pressure helps to keep particles together so that it takes more heat energy to break bonds. 04:28: The particles of a liquid are loosely bound to each other, which manifests as a surface tension and results in liquids having a distinct surface. 05:02: Gas particles zip around without significantly interacting with each other. 05:13: ... the container and the gas will expand, but it’ll take longer for each particle to travel between walls, so pressure drops; vice versa if you shrink the ... 05:23: Increase temperature and the gas particles move faster, hit harder, again increasing the pressure. 09:15: The high density of a supercritical fluid means that its particles do interact with each other, unlike an ideal gas. 11:59: ... for their ability to deposit dissolved elements for growing nano-scale particles and ... 17:00: Excitations in those fields are proper elementary particles, not quasiparticles. 17:18: Actual magnetic monopoles, if they really exist, would be elementary particles, and we’ve done an episode on these before.
	2022-12-08: How Are Quasiparticles Different From Particles? 00:12: But the only elementary particle actually flowing in the circuit are the negatively charged electrons. 00:19: And yet those flowing positive charges are there, in the form of a particle you may never have heard of. 00:53: Now electrons, which are regular particles, are pushed around inside electrical circuits, but it’s only half the story. 02:37: We can model it as though it’s a real particle. 05:43: But this seems a bit more like a sound wave than a particle. 06:16: So now we have something like a particle - a quantum of vibrational energy moving around the lattice. 07:45: ... is often transferred between phonons and other particles - quasi- and real - and modeling this is needed for modeling the ... 08:40: ... elementary particles can be combined into composite particles, for example an atom is ... 14:06: It seems quasiparticles can build into complex hierarchies, just like regular particles. 14:13: Which shouldn’t be so surprising, because quasiparticles are like regular particles in many ways. 14:20: After all, the elementary particles like electrons, photons, and quarks are just excitations in the elementary quantum fields. 14:39: And it turns out that any field, elementary or not, will give rise to particles as long as that field has quantized energy states.
	2022-11-23: How To See Black Holes By Catching Neutrinos 00:03: Neutrinos are one of the most bizarre of known particles. 00:42: ... far less attention in the media - in fact it’s almost as elusive as the particle it depends on - and yet mapping the neutrino sky will surely unlock ... 01:16: ... elementary particles are fermions - so particles of matter rather than force-carrying bosons ... 03:50: ... through the ice, emitting light as it interacts with other charged particles. ... 04:01: This is seen as a cone of blue light that trails the particle. 04:32: ... expanding EM waves created by the charged particle expand slower than the particle itself, so their wavefronts overlap each ... 06:09: More challenging are confounding particles from our own atmosphere. 06:13: When cosmic rays hit molecules in our atmosphere, many different particles can be produced, but the most annoying are muons and neutrinos. 09:26: ... magnetic fields because in many of them we see jets of high energy particles blasted out from the vicinity of the black hole, and these have all the ... 09:41: They are natural particle accelerators, far more powerful than the ones we can build on earth. 09:47: And collisions of magnetic-field-accelerated particles is exactly how we make neutrinos in our experiments. 10:24: Relativistic boosting due to the jet particles racing towards us at near the speed of light.
	2022-11-16: Are there Undiscovered Elements Beyond The Periodic Table? 02:36: ... foil that had been part of Ernest Lawrence’s newly invented cyclotron particle ... 13:56: ... we want to get there our conventional nuclear reactors and particle accelerators will not be enough, we will have to come up with something ...
	2022-11-09: What If Humanity Is Among The First Spacefaring Civilizations? 18:04: So, “spooky action at a distance” does refer to wavefunction collapse, including to the wavefunction collapse of entangled particles. 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. 20:06: ... considered the ghost particles from our recent standard model lagrangian episode, Schrodinger’s ...
	2022-10-26: Why Did Quantum Entanglement Win the Nobel Prize in Physics? 02:36: ... “quantum balls” could be any particle from subatomic to molecular scale, and the entangled property could be ... 04:54: ... relationship between the measured properties of entangled particles if the particles themselves hold the information about their ... 05:16: In particular, the so-called Bell inequality would be true if there are hidden variables contained in the particles,  and violated otherwise. 05:46: ... without breaking the exceedingly delicate correlation between the particles. ... 08:08: Bell’s theorem assumes the choice of measurement is completely free and independent of the particle creation process. 10:46: The first I already mentioned: what if the choice of measurement is not independent of the creation of the entangled particles? 10:53: Aspect’s experiment seemed to eliminate that possibility by making that choice after the particles were produced. 11:16: ... called  superdeterminism - basically   stating that the particles are not only correlated with each other, but also with the random number ... 11:55: It can rule out that the secret information about the entangled particle states lives in the particles themselves - that’s what local means here. 12:04: But there could still be hidden variables that exist in the global wavefunction of the entangled particles. 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. 15:54: And then the one were were went through the entire Lagrangian equation of the standard model of particle physics. 19:09: On the other hand, I’m not a particle physicist, as is evident from my analogy which has nothing to do with particle physics. 19:41: 05TE informs us that if you recite the full  Lagrangian equation three times in front of a mirror, the particle ghosts will appear.
	2022-10-19: The Equation That Explains (Nearly) Everything! 00:00: ... Standard Model of particle physics is arguably the most successful theory in the history of ... 03:24: ... traveled by a ball through the air or the probability that two quantum particles will ... 04:36: ... a Lagrangian. To get the real Lagrangian that describes the behavior of particles in a certain volume, we have to add up infinitely many Lagrangian ... 05:37: ... symmetries I mentioned allow the particles to have two different types of spins. They can either have an integer ... 06:02: ... Particles with half integer spin are called Fermions, and they are stuff, ... 07:51: ... dimensions of spacetime, the number of charges, the number of different particles, or things like that Next we do something similar for the fields of the ... 10:57: ... but, this Lagrangian is haunted, it has ghosts. There are ghosts of particles that cannot be measured, and of infinities that make no sense. But it ... 11:57: ... bear with me. We’re getting there. The particles described by the Lagrangian so far are massless. To add mass we need the ... 12:23: ... of each different fermion. This equation doesn’t actually predict the particle masses - that’s still an unsolved problem. Instead, we have to measure ... 13:07: ... weird. Really, though this term describes the Higgs boson itself. That particle was the last prediction of the Standard Model to be verified, and that ... 13:49: ... it works. Putting in your particle wavefunction and setting your indices right and including the correct ... 14:00: ... that I said “known particle”. There may be unknown particles that are not covered by the standard ...
	2022-10-12: The REAL Possibility of Mapping Alien Planets! 18:29: ... this is just the amount of energy available in a particle interaction for the creation of the interaction   products. It comes from ...
	2022-09-28: Why Is 1/137 One of the Greatest Unsolved Problems In Physics? 05:14: ... two particles get close to each other  there's a chance they will interact, and ... 05:27: ... diagrams are used to  add up the probabilities   of particles interacting by all the different ways that interaction could ... 05:34: Those probabilities depend on many things,  like the particles’ positions and momenta, spins, charges, masses, etc. 13:07: Or perhaps it hints at a deeper connection  between the properties of  the elementary particles, like the mass and charge of the electron.
	2022-09-21: Science of the James Webb Telescope Explained! 13:37: ... attempt to understand QCD, before being abandoned because it predicted a particle which behaves like a ... 15:23: OK, on to our episode on how the Higgs boson could be the key to discovering the dark matter particle. 16:13: nyrdybyrd points out that the info from this Higgs episode is an influential argument for a badass new particle collider. 16:24: I’ve heard it argued that it’s silly to build new particle colliders in the hope of discovering particles that we don’t know exist. 16:30: But that’s not the only, or even best reasons to improve our particle collider capacities.
	2022-09-14: Could the Higgs Boson Lead Us to Dark Matter? 00:12: It was the final piece needed to confirm the standard model of particle physics as that model now stands. 00:27: So the discovery of the Higgs wasn’t the end of particle physics - but it may be the way forward. 00:33: Many physicists think that the secret to finding the elusive dark matter particle will come by studying the Higgs. 01:01: These particles dominate our experience of the universe because they are strongly interacting. 01:11: But there are other matter particles that interact only weakly, and so we don’t see them even though they’re insanely abundant. 01:33: We know that there’s some source of gravity out there in the universe NOT caused by the particles of the standard model. 01:46: ... “dark matter” might be a new kind of particle, or, in fact, there could be an entire family of different particles that ... 01:59: So how do you go about detecting a particle whose defining quality is being almost undetectable? 02:05: Let’s start by looking at how we detect new particles in general. 02:17: ... Feynman diagram is just a way to represent the interactions of particles, plotting time versus space so we have two particles coming together, ... 02:37: This particular diagram shows a dark matter particle scattering off a standard model particle in some way. 02:44: The standard model particle could be a quark, an electron, or anything that makes up normal matter. 02:50: ... would call this a direct detection experiment - because a dark matter particle is actually interacted with one of the particles in our say ... 03:06: But with enough particles and enough time, we should eventually see an interaction between a dark matter particle and a matter particle. 03:24: ... have yet to spot even a single collision compatible with the dark matter particle ... 03:51: ... space axes are flipped, so now we’re looking at the annihilation of a particle anti-particle pair from the dark sector, resulting in the creation of a ... 04:06: ... example, two dark matter particles somewhere in space could annihilate to produce gamma ray photons, which ... 04:48: ... particles become dark matter that’s created from the annihilation of some standard ... 05:10: In the LHC we smash together particles of regular matter, like protons or heavier nuclei. 05:17: All sorts of exotic particles get created in those collisions. 05:21: Those particles are sometimes detected directly when they smash into one of the many detectors surrounding the collision point. 05:35: But of all the particles produced in these events, we think that the elusive Higgs boson has the best shot at producing a dark matter particle. 05:46: ... particles with electrical charge OR color charge can’t decay into Higgs bosons, ... 06:01: ... that excludes the electrically charged leptons: electrons, muons and tau particles; it excludes the quarks and whatever is made of quarks; it excludes the W ... 06:30: ... could potentially decay into dark matter particles, but if they do it’s going to be near impossible to spot the event, so ... 07:19: We know that the Higgs field is what gives most of the standard model particles their masses. 07:46: Physicists playfully called it a portal since the Higgs could be the doorway that connects our standard sector of particles to the dark universe. 08:20: After all, those particles are going to fly right through all of our detectors. 08:36: And there is a trick for detecting undetectable particles. 08:48: ... of momentum tells us that the product of velocity times mass of all particles going into a collision has to be the same as the same product for all ... 09:00: ... know pretty well the momentum of the particles going into our collision, and we can measure and add up the momentum of ... 09:19: ... due to the fact that there’s variation in the speed of the colliding particles. ... 09:51: ... momentum perpendicular to the direction of the particle beams is called the transverse momentum, and it’s zero by definition. ... 10:13: ... every particle scattering to the left, you need something scattering the right to ... 10:30: ... stuff firing out in the opposite direction of the jet, but no visible particles appeared on that ... 10:38: The only explanation is that particles were projected in that direction, they're just invisible. 10:44: You might ask - can’t those invisible particles just be neutrinos? 10:50: But every neutrino has to be created with an electron, muon or tau particle partner. 11:24: And the Higgs lives for only a fraction of a second before decaying. The hope is that sometimes it decays into a dark matter particle. 11:59: This number tells you the fraction of times a Higgs decayed into particles that can’t be detected. 12:31: If this number holds up, then ,the Higgs could be decaying into new invisible particles! 12:59: The discovery of the Higgs boson was the end of one era of particle physics but very much the beginning of another. 13:08: ... physics, and we don’t know what it’ll reveal —- hopefully a dark matter particle, perhaps an entire dark sector, perhaps much ...
	2022-08-24: What Makes The Strong Force Strong? 01:29: ... the strong force came in the 1940s when we switched on our first particle colliders and started to detect a veritable zoo of new ... 01:41: As physicists tried to understand the aptly named particle zoo, certain peculiar relationships were observed. 01:48: ... particular, Murray Gell-Mann and others realized that the way these particles were created in particle collisions suggested the existence of a new ... 02:03: ... and Yuval Ne'eman noticed that if you arrange particles according to their strangeness and their electric charge, they fall into ... 02:16: This is known as the Eightfold Way and it’s like a periodic table but for particles. 02:22: ... too long it was realized that the particles of the particle zoo were not elementary - they were made of smaller ... 02:31: It turns out that location on these shapes represent the quark content of the particle. 02:41: By the way, these particles of multiple quarks are now called hadrons. 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. 03:24: That includes electrons, quarks, and many of the particles that are composed of quarks. 04:13: It can’t be spin, because with 3 particles and only two possible spin states two will always have the same spin. 04:39: If our Omega particle’s quarks are going to wear the same dress, they better be different colours. 05:34: It turns out that all of these particles are made of three or two quarks. 05:39: It’s possible to briefly create larger combinations in particle colliders, but not in nature. 06:03: Electrically charged particles interact with each other via the electromagnetic field. 06:07: We can think of each charged particle as generating a constant buzz of virtual photons around it, forming what we think of as its EM field. 06:17: That buzz weakens the further you get from the particle. 06:31: Assuming the strong force works roughly the same way, we need a field to mediate it, and that field should have its own particles. 06:39: We call those particles gluons. 07:34: ... new pions from a single pion. And the same would happen with any other particle made of ... 07:46: If you want to break them apart you just end up forming new particles, so quarks never end up alone except in the most extreme energies. 07:55: ... energy, like in the very early universe or at impact point in a large particle collider, space gets sort of saturated so that new quarks can’t be ... 11:25: This is possible because the mediating particle of electromagnetism, the photon, is itself electrically neutral. 12:07: This means gluons are unable to interact with neutral particles like the combinations of quarks that form the hadrons. 16:52: Starting with Lattice QCD, although the questions are more generally about particle physics. 16:59: Jeremiah Young asks whether relativistic time dilation occurs due to the thermal motion of particles. 17:05: In other words, if heating something up means its particles are moving faster, does time slow down for those particles? 17:41: There’s also weird stuff, like the fact that there’s enough kinetic energy in this matter to cause spontaneous particle-antiparticle creation. 17:53: ... and Gabriel Monteiro de Castro Both ask the same question: if virtual particles don’t actually exist, but instead are a calculation tool to describe ... 18:07: After all, Hawking radiation is sometimes portrayed as a virtual particle-antiparticle pair being separated by a black hole event horizon. 18:15: ... the answer is that the story about separation of virtual particles by the event horizon is a meant to be an intuitive picture of what’s ... 18:42: But the event horizon changes the balance of these modes causing imperfect canceling, which looks like particles are being radiated by the black hole. 20:27: Speaking of which, Marik Zilberman asked whether a particle of the quintessence field could account for Dark Matter? 20:38: ... would need to be coupled strongly with the Higgs field to give the particle enough mass, but it would still need to couple extremely weakly with all ...
	2022-08-17: What If Dark Energy is a New Quantum Field? 00:36: ... space buzzes with random activity that we sometimes describe as virtual particles popping into and out of existence, driving accelerated expansion. But ... 09:13: ... of state depends on this field strength and the kinetic energy of the particles of the field. The field strength can also change over time AND over ... 13:27: ... said, physicists are trying. The most direct test would be to find the particles of this field, for example in one of our particle colliders. But there ...
	2022-08-03: What Happens Inside a Proton? 00:45: ... a previous  episode, it takes as many bits as there   are particles in the universe to store all the information in the wavefunction of ... 01:31: ... describes the interactions of electrons and any other charged particle   via photons. We’re going to come back  to a full description of QCD ... 02:06: ... own - they’re always   bound to other quarks in composite particles called hadrons, of which protons and neutrons   are an example. To ... 06:37: ... Feynman diagram approach   even with computers. Now Before any particle physicists start shouting at me,   I’ll quickly add the caveat that there ... 07:07: ... Feynman diagrams.   In fact, we need to abandon the idea of particles altogether. See, it turns out that the virtual   particles that we were ... 07:53: ... are way too tumultuous to be easily   approximated by virtual particles. Instead we have to try to model the field more ... 08:30: ... the number of field configurations by approximating them as virtual particles.   But for QCD we have to stick with fields, so we need a different ... 08:58: ... the Feynman path integral. It calculates the probability that a particle will move from one   location to another by adding up the ... 10:43: ... each path comes from adding up all the little   shifts in the particle phase from each step. Then at the end of the path, you add ... 14:08: ... field more directly. That helps us put to bed the idea that virtual particles are   more than an approximation of what these ... 15:29: ... said that   it is defined as zero kinetic energy in the  particles, but actually this doesn’t account   for particle vibrations, ...
	2022-07-27: How Many States Of Matter Are There? 00:42: ... up and those bonds break and we’re left with weaker bonds that allow the particles to slip and slide around each other while nonetheless generally sticking ... 00:56: Heat it further and the weak bonds break, allowing particles to fly freely around the room - and voila, a gas. 03:12: The two numbers related on the phase diagram - temperature and pressure - are statistical properties of a large collection of particles. 05:05: ... plasma still consists of composite particles: the electrons are elementary, but the atomic nuclei are little bundles ... 05:47: You might wonder if this stuff is even more plasma-like that plasma - with the particles more free to zip around the room. 06:02: We routinely make this stuff in our particle accelerators, but the quantity is tiny - the result of smashing two nucleons together. 07:54: The states of matter we’re most familiar with can be explained as particles interacting under classical forces. 08:26: These are configurations of entangled particles that oscillate between states even when they have no energy. 08:32: In regular thermodynamics, the lowest energy corresponds to absolute zero temperature, which in turn means zero motion of particles. 08:58: Subatomic particles can have their own states of matter. 09:54: Here’s something we don’t usually think of as particles: human beings, but they can behave in ways eerily close to states of matter. 11:28: The fact is, the concept of "states of matter" can help us to understand many kinds of interactions, even between macroscopic “particles”.
	2022-07-20: What If We Live in a Superdeterministic Universe? 02:56: And a wavefunction can also span multiple particles, holding information about the relationships between those particles. 10:24: ... of how they make their measurements, and the states of the measured particles? ... 16:56: For example, Planck units, or the energies or masses or decay timescales of common particles and elements.
	2022-06-30: Could We Decode Alien Physics? 00:00: ... even if it is insanely complex. We know  this because the particle carried by the   alien circuitry looks like the electron. ... 01:25: ... equations   which govern the interactions of charged  particles will reveal that they use a flipped   sign convention. Nope. ... 04:59: ... - the Maxwell’s equations. Those equations tell us how particles with    electric charges respond to each other. ... 05:33: ... symmetry breaking. The classic example is the decay of the kaon particle,   which we’ve talked about in detail previously. The long story short ... 06:55: ... for the sign of electrically charged   particles is not the only arbitrary choice we’ve  made in our development of ... 07:38: ... convention, and its choice also determines how we   define particle handedness or partical chirality. What if our aliens were ... 10:41: ... is the symmetry between left and right handed chirality for particles with quantum spin,   and in our universe P-symmetry is broken ... 16:39: ... a magnetic shield may be   enough to block many charged particles, but  neutral particles like dust would pass right   ...
	2022-06-22: Is Interstellar Travel Impossible? 03:50: And that’s to say nothing of cosmic rays - particles moving fast enough to kill all on their own. 04:02: ... can a ship large enough to carry humans be adequately shielded from tiny particles without adding so much extra mass that accelerating such a ship becomes ... 08:19: The kinetic energy deposited by each particles is 1/2 times mass times velocity squared. 08:26: ... in the relative densities, particle masses and speeds, the heat deposited onto our ship by the ISM is around ... 08:51: In a 2016 paper, Thiem Hoang and collaborators calculated the damage by individual particle impacts. 12:22: Interstellar space is flooded with high energy particles, from simple protons to massive iron nuclei. 16:16: Yash Chaurasia asks whether asking an electron "are you a particle?" automatically answers "are you a wave?”. 16:34: But if there are only two possible answers - particle or wave - then asking one answers the other. 17:09: ... ask about the wave-like properties (for example the phase), or about the particle-like properties (which detector), but not both at the same time with the same ... 17:20: ... inside a black hole, given that they do so in the high energies of particle ... 18:11: ... Hegvik asks whether by collecting the information from the entangled particles that emerge from a black hole as Hawking radiation, could we in ... 19:10: Otinane Yos asks whether we can be sure that virtual particle - antiparticle pairs get separated near a Black Hole event horizon. 19:26: And most of those lines of reasoning say nothing about virtual pairs of particles. 19:36: ... virtual particle picture is a sort of colloquial interpretation of what’s going on, ...
	2022-06-15: Can Wormholes Solve The Black Hole Information Paradox? 02:43: ... Neumann entropy. This is the entropy of   entanglement. If two particles are entangled then they share mysterious correlations - you can ... 03:20: ... you can entangle a particle you can entangle a black hole. One way to think about ... 04:44: ... radiation with that quantum information,   so that each new particle is entangled  with all previously emitted ... 07:24: ... integral  calculates the probability of some quantum   particle traveling between two points by adding up all ways the particle ... 08:14: ... black hole,   as its geometry changes with each  outgoing particle of Hawking ...
	2022-06-01: What If Physics IS NOT Describing Reality? 00:25: ... formulate mathematically in quantum theory deal  no longer with the particles themselves but with   our knowledge of the elementary ... 02:44: ... those parts.   In quantum mechanics, we have things like  particles and fields which can only take on   discrete or quantized ... 03:22: ... we have — for example, about  the location or speed or mass of a particle.   Zeilinger calls such a statement a proposition  - it’s an answer to ... 04:56: ... spin.   From a physical point of view, think of it as  a particle’s orientation - a spin axis that   can point either up or down. ... 05:53: ... You started out with one bit of knowledge  about the particle’s up-down alignment.   According to Zeilinger, by definition, ... 07:23: ... to have a spin direction that’s  defined relative to another particle’s spin.   For example, a pair of electrons could be  ... 08:49: ... example, that the product of the measurement error   in a particle’s position and momentum has to be  greater than the Planck constant ... 10:02: ... experiment causes a photon to behave like a wave  or a particle depending on the question asked   of it. And that question ... 10:33: ... only one answer to two complementary questions:   just as our particle could only tell you if it was up or down, but not left or ...
	2022-05-18: What If the Galactic Habitable Zone LIMITS Intelligent Life? 06:56: ... as a slightly overdense spot  in the near perfectly smooth cloud of particles   that filled the universe after the Big Bang. As  it cooled, our ...
	2022-05-04: Space DOES NOT Expand Everywhere 11:59: ... Empty space has a very weak energy density, even in the absence of particles. As space expands, that density doesn't change - remember, the balloon ... 13:50: ... asks How the heck do you weigh a subatomic particle? Good question. Riley Schroeder quips “carefully and hypothetically” - ...
	2022-04-27: How the Higgs Mechanism Give Things Mass 00:10: ... culminated in the April 7 announcement  that this obscure particle’s mass seems to be 0.1%   heavier than expected. So why do we ... 00:46: ... this is the weirdness   of the weak force - in particular the particles  that carry this force. Its W and Z bosons have a   property ... 01:48: ... packets of energy that can move  around - and those are the particles of a ... 04:08: ... far so good except that the predicted particles  are massless, while the real weak force bosons   are, as I ... 07:33: ... Particles of this field are just oscillations  of the field strength across ... 08:09: ... Lagrangian describes a simple  quantum field made of massive particles which   interact with each other. Let me talk you ... 10:15: ... the other hand, the particle of  the original field needs a rest mass   energy to be ... 11:56: ... vacuum expectation value. The original massive  particles of the field now oscillate in the   radial direction, but no ... 12:26: ... valley in what we’ll call the theta direction.   The resulting particle is called a  Goldstone boson and it’s massless   because ... 13:44: ... potential. Weird stuff happens when the gauge  field couples to the particles of that ... 16:02: ... mechanism. The Higgs field also gives mass   to the matter particles - the fermions -  but that’s for another time. But what ...
	2022-04-20: Does the Universe Create Itself? 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 ... 04:57: ... in his expression “it from bit.” In his words, “Every it — every particle, every field of force, even the spacetime continuum itself — derives its ... 07:43: ... experiment. If we measure the spin of one member of a pair of entangled particles - the choice of the direction of the spin measurement seems to have an ... 12:05: ... could well be code for “interaction”, in which every time two particles bump together and become entangled we have an act of measurement. If ...
	2022-03-23: Where Is The Center of The Universe? 16:27: Al H asks what particles and interactions existed before the electroweak force split into electromagnetism and the weak force. 16:37: Well, the big one is that the elementary particles were massless back then due to the absense of the Higgs mechansism. 16:42: Also, before that split, particles could transfer their isospin a lot more easily. 16:55: Just like it makes no sense to distinguish electrons with up or down spin as different particles. 17:02: In fact the universe seemed to be made of only six particles, three quarks and three leptons. 17:09: When the universe cooled down and the electroweak symmetry was broken, particles were locked in whatever isospin state they happened to be in. 17:22: ... given that it’s defined in reference to the momentum vector of the particle. ... 17:32: For example, if a particle races past you you observe its chirality based on its direction of motion. 17:38: What happens if you then you accelerate and overtake the particle so it appears to be moving in the reverse direction. 18:05: It’s only equal to helicity for particles that you can’t overtake - aka light speed, massless particles.
	2022-03-16: What If Charge is NOT Fundamental? 00:57: It seems to just be a property that particles can have or not have - as fundamental as mass. 01:30: ... and the answers will take us   through the birth of Particle Physics, and, in fact, through the birth of the universe ... 02:10: Heisenberg wondered if the two particles were in fact just different states of a single particle which he called the nucleon. 02:18: At this point we already knew of particles that had internal states. 02:49: ... if the protons and neutrons are just two states of the same particle, Heisenberg reasoned that they may be differentiated by a property  ... 03:29: ... precise predictions of the outcome of  collisions between these particles. ... 04:02: Our particle colliders advanced, leading to the discovery of weird new particles. 04:07: So many of them, in fact, that physicists struggled to make sense of this so-called particle zoo. 04:14: For example, some of these particles had very similar masses but very different electric charges, which I hope reminds you of the proton and neutron. 04:24: So maybe each of these groups were really a single particle in different states - with different isospins. 04:43: Peering into the depths of the particle zoo, they noticed another pattern. 04:49: There seemed to be a family of particles that were only created in pairs. 05:00: But these new particles weren’t doing this to conserve charge, nor isospin, nor any other known property. 05:30: Electric charge, isospin and hypercharge were intimately connected across all particles. 05:57: Charge alone couldn’t explain the patterns of interactions and particle types observed in the particle zoo. 06:22: Plotting particles according to their isospin and hypercharge revealed peculiar geometric patterns. 06:29: For example some groups of eight particles formed hexagons, and one group of ten particles formed a triangle. 06:41: No big deal - Gell-Mann just hypothesized an undiscovered particle - the omega baryon - with the right isospin and hypercharge to fill that hole. 07:34: ... of the geometric symmetry if nucleons themselves were not elementary particles, but rather made up of smaller components, which he dubbed ... 07:53: He showed that isospin and hypercharge were just emergent properties that reflected the different types of quarks that make up one of these particles. 08:21: ... something that lives in the hearts of these quarks and other elementary particles - that governs these differences between particle groups, and that also ... 09:20: First, the weak force can transform particles into  other particles - something no other force can do. 09:28: Second, it only works on left-handed particles. 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. 09:52: ... Particles can have right-handed chirality if their spin is clockwise relative to ... 10:02: Only particles with left-handed chirality feel the weak force. 10:10: Only the left-handed component can emit one of the weak-force carrier particles - the W boson - and in doing so transform into a neutrino. 10:39: Only left-handed particles have it, and so it has an intimate connection to the quantum spin. 11:20: ... must be fundamental because they are properties of elementary particles that can't be broken into smaller ... 11:30: Particles like the electron, the neutrino, and even the quark. 11:40: ... old strong-force versions of isospin and hypercharge in the composite particles of the particle zoo emerge from their different quark content, but are ... 13:08: Which, by the way, grants mass to elementary particles - yet another supposedly “fundamental” property”. 14:39: David, the swiss are famous for their chocolatiers  and for their giant particle colliders.
	2022-03-08: Is the Proxima System Our Best Hope For Another Earth? 11:22: ... the star to have powerful outbursts - flares - that blast high energy particles and radiation through the planetary ... 11:36: During flares, Proxima B is blasted with X-rays and ultraviolet light and high energy particles.
	2022-02-23: Are Cosmic Strings Cracks in the Universe? 00:58: ... transition occurs in the quantum fields that   underlie all particles. Just as with water, a  field’s inherent temperature massively ...
	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 states at the same time, or to teleport ... 00:49: ... quantum mechanics, particles don’t have definite properties. Rather they are described by something ... 01:06: ... example when we make a measurement of a particle, the property that we’re measuring seems to be plucked from the wide ... 02:24: ... because it’s confusing. Quantum superpositions can involve many quantum particles. So how far can the superposition extend? The atom, the radioactive ... 03:24: ... ideas in the past. We also have de Broglie-Bohm pilot wave theory, where particles already have defined properties that are hidden within the wave ... 06:41: ... are very rare. It’s incredibly unlikely that a single isolated quantum particle will undergo collapse during the course of an ... 06:53: ... the more particles you add, the more likely that one of them experiences collapse, and that ... 07:17: ... for the quantum-classical divide - it simply depends on the number of particles involved. Small things can stay quantum, but the chance of collapse to ... 07:35: GRW suggested that the collapse rate should be about 10^-16 hits per second per particle. 07:44: ... this value, a single particle wave function remains uncollapsed for around 100 million years. But if ...
	2022-02-10: The Nature of Space and Time AMA 00:03: ... in the case of space it's the coordinate system it's the grid on which particles move they exert forces on each other and then of course we have time ...
	2022-01-27: How Does Gravity Escape A Black Hole? 06:08: Now in quantum mechanics - or more specifically quantum field theory - forces are mediated by particles, not by the geometry of spacetime. 06:16: ... example the electromagnetic force is communicated between charged particles by transferring virtual photons - ephemeral excitations in the ... 06:28: In theories of quantum gravity, the gravitational force should probably also have a mediating particle - usually called the graviton. 06:42: If gravity is really communicated by a particle, how does that particle escape the event horizon? 06:54: There’s a bit of a misconception in how we think about virtual particles. 07:02: Virtual particles aren’t localized like that. 07:16: But those photons don’t follow a well defined path between the interacting particles. 07:21: ... and their summed effect leads to a repulsive force between the particles. ... 07:55: That’s easy - these are virtual particles, and in quantum field theory, virtual particles are not restricted by the speed of light. 08:06: ... between particles result from the sum of all virtual particle interactions, possible and ...
	2022-01-19: How To Build The Universe in a Computer 00:47: ... hydrodynamic interactions of countless stars and gas and dark matter particles over billions of future ... 03:59: ... field is constant - it only changes in the next step, after all the particles have made their ... 05:02: In the simplest type of N-body simulation you need to compute the effect of every particle on every other particle. 05:09: So if there are N particles  that’s N^2 calculations. 05:14: For a modern one-million particle simulation of a star cluster, that’s a trillion computations per time step. 05:51: Perhaps the most important is to avoid having to consider every single particle pair. 06:00: ... nearby particles it’s important to consider every individual interaction, but for more ... 06:16: It works like this: you start with a volume full of particles, each with its starting position and velocity. 06:28: You stop dividing in any given part of the volume when there is no more than one particle per cube in that path. 06:36: Next, you run an N-body simulation by calculating  the summed gravitational pull on each given particle. 06:43: ... the effect from distant locations, you don’t do it for each particle - instead you do it for all particles inside one of these ... 06:55: ... you need to do goes down from N^2 to N-times-log-N, which for large particle numbers is much, much ... 07:08: ... approach is the particle-mesh method,  in which particles are converted into a density ... 07:24: Adaptive particle meshes can be used to add higher resolution where needed - say, where the stars have higher density or structure. 07:33: Modern mesh codes also do  classic particle-particle   interactions at short ranges to improv accuracy at small scales. 07:41: These mesh codes are useful for systems of particles interacting under gravity. 08:26: Particle-mesh approaches can do this, but these  days it’s more common to use an approach called smoothed-particle hydrodynamics or SPH. 08:35: ... codes don’t use a rigid grid, but rather they  track tracer particles within the fluid - those particles effectively make up a constantly ... 09:05: ... an amalgam of these methods - for example SPH for large scale flows and particle-particle N-body for small-scale ... 10:28: It simulated 13-billion light years wide cube containing over 300 billion particles, each representing a billion-Suns worth of dark matter. 10:39: ... is AbacusSummit, which just last year simulated 70 trillion particles on the supercomputers at the Center for Computational Astrophysics in ... 11:13: ... than is contained in a typical simulation,  which just tracks particle  positions and ...
	2022-01-12: How To Simulate The Universe With DFT 00:00: ... you used every particle in the observable universe to solve the schrodinger equation and do full ... 00:23: And yet we routinely simulate systems with thousands, or even millions of particles. 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. 01:21: You need exponentially more computing power and more storage the more particles you have. 01:28: In fact you need more particles than exist in the solar system to store the wavefunction of the electrons in a single iron atom. 01:48: ... describes how the wavefunction of a quantum particle - that’s this psi thing - changes over space, assuming the particle is ... 02:30: ... quantum mechanics - it’s an approximation that works for slower moving particles that don’t change over ... 04:06: ... atom on a course grid, you’d need to store more numbers than there are particles in the solar ... 04:52: ... particles to the Schrodinger equation is like adding dice to this system- every ... 05:52: ... to solve the impossible case of many interacting quantum particles, we should start by thinking about the completely solvable case of many ... 06:06: When we use Newton to solve, say, the three-body problem, we can solve the equations for each of the 3 particles separately. 06:18: In fact astrophysicists do huge galaxy simulations of millions of particles without doing millions-of-dimension calculations. 06:37: ... space and consider just the few points in that space where the particles actually exist at a given point in ... 06:59: ... non-local correlations which arise because the position of one quantum particle can restrict the set of possible positions for the other particles, for ... 07:15: In the Newtonian case, particles only interact locally, and that means the Newtonian equations of motion are what we call separable. 07:33: ... this is true then we can take an equation for N particles in 3D and reduce it from a 3^N dimensional equation to simply N coupled ... 07:46: ... mechanics we can not only write down the equations of motion for each particle separately, we can write the x, y, and z equations of motion separately ... 08:11: We need to know the wavefunction for every particle everywhere. 08:15: And we can’t reduce the dimensionality by treating particles separately because the Schrodinger equation can’t be made “separable”. 08:26: ... impossibility of solving the Schrodinger equation for more than a few particles, researchers still manage to do quantum simulations of some extremely ... 09:14: So how does DFT do a calculation that should need to manipulate vastly more bits of information than there are particles in the entire universe?
	2021-12-20: What Happens If A Black Hole Hits Earth? 01:12: The early universe was a wild place. All space everywhere was a boiling particle soup. 06:02: ... accelerates matter to incredible speeds. Near the event horizons, particles collide with each other sizable fractions of the speed of light. This ...
	2021-12-10: 2021 End of Year AMA! 00:02: ... um and the question is when an electron emits a photon and another particle let's say a proton absorbs it what causes the particles to be um ...
	2021-11-17: Are Black Holes Actually Fuzzballs? 02:27: But these few numbers emerge from the motion of every air molecule — and to describe that we’d need the positions and momenta of 10^27ish particles. 05:52: ... string theory, all elementary particles are oscillations in 1-dimensional strands that themselves are embedded ...
	2021-11-10: What If Our Understanding of Gravity Is Wrong? 01:02: ... some of the speculative ideas of what it might be made of - from exotic particles to black ... 10:21: One of the most important pieces of evidence  for dark matter as a particle is seen in the light that comes from the very early universe. 13:10: ... MOND proponents say that it’s the behavior of  dark matter particles that have to be carefully fine-tuned to produce the phenomena that ... 13:32: ... of possibilities for what it might be beyond our standard model of particle ... 14:01: ... whether we’re led beyond the standard model by dark matter  particles, or beyond general relativity by hidden gravitational modes of space ...
	2021-11-02: Is ACTION The Most Fundamental Property in Physics? 01:22: ... gave us the instant and miraculous power to explain the motion of all particles in the universe. To do this, all you needed to do was know the exact ... 08:39: ... 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 ... 09:24: ... seems to be a conflict here. The principle of least action says that a particle will always land where the action of the trajectory is at a minimum or ... 10:26: ... this story is Richard Feynman. Remember that the action tells us about a particle’s history along some hypothetical path. Feynman realized that the path of ... 11:59: ... Dirac started to guess, particles tend to end up near the stationary points of the quantum action. In the ... 13:23: ... Lagrangian for each quantum field which describes how that field and its particles tend to evolve. Combining these gives us the Standard Model Lagrangian, ...
	2021-10-20: Will Constructor Theory REWRITE Physics? 00:32: describe some aspect of the universe with numbers - like the temperature, pressure, etc of a gas or the position, velocity, etc. of a particle Step 2. 12:30: ... page has a great question: Could a particle  tunnel through .. nothing. As in could it   quantum teleport ... 14:00: ... space. This is a tough one. It’s not clear that  the particle itself is ever “inside the barrier”,   but its wavefunction ... 14:48: ... being an emergent   consequence of causality. If every particles  wavefunction is really spread over all of space   can anything ... 15:34: ... that the universe saves CPU space by not fully  rendering particles that aren't being viewed by   the player. This leads to ...
	2021-10-13: New Results in Quantum Tunneling vs. The Speed of Light 00:32: It describes how quantum particles are able to move across seemingly impenetrable barriers - for example, when atomic nuclei decay. 00:40: ... the quantum world weird - it’s also that the tunneling motion may move particles faster than they could travel if the barrier wasn’t there - and even ... 01:51: ... similar thing happens in the world of quantum mechanics, where particles are pushed and pulled by the fundamental forces, forming energetic hills ... 02:11: If one of these particles had enough energy it could punch through that barrier. 02:22: In radioactive decay, particles that should never have enough energy to escape the nucleus are found to leak out. 02:35: Between observations, quantum particles don’t have well defined properties - and that includes their positions. 02:52: ... measurement, or upon interaction with another particle, the proton can end up anywhere within that wavefunction, with some ... 04:22: For example, is the transition of the particle from one side of the barrier to the other instantaneous, or does it take some time? 05:02: In other words, you can double the length of your barrier, and your particle will take the same amount of time to travel all the way through. 05:48: If the position of the tunneling particle isn’t perfectly known, how do we know when to start and stop our tunneling stopwatch? 07:01: Launch a particle through empty space with a well defined starting position, and it’s position wavefunction will spread out before the finish line. 07:08: ... can’t travel faster than the speed of light, but upon measurement, the particle may appear to be at the leading edge of its wavefunction - potentially ... 08:09: Imagine you try to send a message encoded in a collection of particles to a friend, and you want it to arrive as soon as possible. 08:31: ... you can count the message received at the instant the first particle arrives, then the new study finds that the tunneling message really does ... 09:09: The study finds that the average travel time for tunneling particles is shorter than the average time the free-flying particles. 09:17: But that’s only for the tunneling particles that make it through. 09:31: ... over and over, your friend will most likely receive a free-flying particle long before they receive a tunneling particle - staggeringly more likely ... 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. 10:48: ... phenomenon is called Larmor precession, in which a particle’s dipole magnetic field, which is defined by its spin axis, precesses like ... 11:17: Some particles, naturally, did manage to tunnel through anyway. 11:30: Did the particles travel faster than light? 11:50: ... with should still show the effect under FTL circumstances, with faster particles and a thicker ...
	2021-10-05: Why Magnetic Monopoles SHOULD Exist 00:00: Physicists have been hunting for one particle longer than perhaps any other. 00:04: It’s not the tachyon or some supersymmetric particle. 00:08: It’s the magnetic monopole - and of all the fantastical beasts of particle physics, this is perhaps the most likely to actually exist. 05:37: The great Paul Dirac had a habit of discovering particles just by staring at the math. 06:49: So magnetic fields affect charged particles. 06:52: In quantum mechanics, this works by shifting the phase of the particle’s wavefunction. 06:57: Imagine a charged particle - say an electron - passing by a Dirac string. 07:56: ... argued that this makes it a mathematical figment, kind of like virtual particles. ... 10:55: And it turns out these knots in the Higgs field in GUT theories behave as massive particles with magnetic charge - magnetic monopoles. 13:37: We have been hunting for magnetic monopoles for longer than just about any particle.
	2021-09-21: How Electron Spin Makes Matter Possible 00:26: ... cute case of quantum mechanics being a bit silly. The fact that some particles have this property is the entire reason that stuff in our universe has ... 01:13: ... Particles with spin-½ - or more generally any half-integer spin - 3/2, 5/2, etc. ... 02:18: ... I’m going to show you why this is the inevitable behavior of groups of particles that have two properties: 1) this weird rotational symmetry, and 2) ... 03:46: ... in each hand so the belt is flat. Let’s think of the belt buckle as a particle - say an electron - and the belt is its connection to whatever - the ... 04:43: ... can think both ends of the belt as spinor particles like electrons, and in that case we can do another experiment. What ... 05:59: ... observed. For example, the wavefunction representing the position of a particle can look like a sine wave moving through space. If you have two such ... 09:08: ... Psi(A,B) = -Psi(B,A) Wavefunctions that change sign like this when it's particle labels are swapped are called anti-symmetric under particle interchange, ... 09:45: ... But it seems like the two-particle wavefunction changes if we swap the particles. Doesn’t that give us a way to “distinguish” the swap? Actually no - no ... 10:12: ... distinguish electron A from electron B through observation of these particles, it turns out that this subtle “unobservable” property has a powerful ... 11:21: ... one. We’re choosing it because it works. To prove it, let’s switch the particles and the wavefunction sign should flip. We want Psi(A,B) to become ... 12:31: The two particle wavefunction would then look like this. The fs become gs. 13:03: ... anti-symmetric wavefunctions, is the pauli exclusion principle. That is, particles with half integer spin have antisymmetric wavefunctions (the belt trick ... 13:25: ... - which is the quantum equation of motion for electrons and other spin-½ particles. ... 14:00: ... can continually remove energy from the system by lowering the state of a particle forever. But if you use the correct anti-symmetric wavefunction then ... 17:29: ... Prot Eus tells us that the hole can only be filled by an adjacent particle, which then just shifts the location of the hole. In this way the hole ...
	2021-09-15: Neutron Stars: The Most Extreme Objects in the Universe 02:00: ... photons in the magnetic field.   That field then becomes a particle accelerator, with electron currents flowing one way and   ... 07:06: ... we can duplicate these energies and these  neutron-rich nuclei in particle ... 08:15: ... forces reshaping the nuclei. The result is this game   of particle tug-of-war, with all its pushing and pulling, we see a complete ... 11:29: ... particular way to form Cooper pairs,  which act as spin-0 or spin-1 particles.   Some of our fermions effectively become bosons - which means they ... 12:23: ... may be that these extreme pressures and energies we find ‘hyperon’ particles containing   ‘strange quarks’. Or, they might not be ...
	2021-09-07: First Detection of Light from Behind a Black Hole 01:13: We talked about this soon after it came out - but to remind you, here we have radio light from charged particles whirling around the black hole. 14:25: ... big bang - what with it producing an expanding bubble full of energetic particles. ... 15:03: ... yield universe whose interior is expanding quickly - in the sense of particles racing apart from each other. You can look at our past episodes on ...
	2021-08-18: How Vacuum Decay Would Destroy The Universe 00:21: ... has just the right expansion rate, and has just the right particle properties to allow stars and   planets and people to exist. ... 03:11: ... universe is filled with this soup of  Higgsiness. Most elementary particles that have   mass gain their mass due to interactions with ... 04:00: ... the big bang or near a black   hole or in a sufficiently large particle accelerator. But there’s another to make this ... 06:08: ... points across space, which is why  their oscillations propagate as particles.   Now this isn’t necessarily an instant disaster. The interior of the ... 08:08: ... the expanding bubble with a hot soup of energetic  particles. It’s similar to how the energy held in   the latent heat of ... 08:30: ... the worst of it. As I mentioned, the Higgs field gives elementary particles their   masses. Those masses depend on the energy in the ... 09:38: ... shape of the Higgs field with   precise measurements of the particles  that gain their mass from the Higgs.   The most important are ... 10:54: ... rapidly evaporating. Now,   there was some fear that our giant particle  colliders like the LHC might nucleate a vacuum   decay bubble. ...
	2021-08-10: How to Communicate Across the Quantum Multiverse 00:53: ... a fantastically complex bath of density fluctuations. A snapshot of particle positions in the room would reveal a hopeless scramble. And yet somehow ... 02:29: ... only one reality; or de Broglie-Bohm pilot wave theory, which says that particles are particles and waves are waves - and the wavefunction’s job is to ... 08:08: ... would mean that information could be sent between entangled pairs of particles. Now we’ve been over entanglement before, but to remind you: if two ... 08:55: ... make it possible to send real information between entangled pairs of particles, enabling instant communication at any distance, and even backwards in ... 09:57: ... Basically it’s a pair of magnets - a north and south pole - that deflect particles with spin and charge. It measures the direction of spin by whether the ... 16:27: ... is exactly it. The supernova shock front is a mixture of high energy particles and magnetic fields. Those magnetic fields do lots of things - including ...
	2021-08-03: How An Extreme New Star Could Change All Cosmology 06:21: ... - specifically, by the Pauli exclusion principle, which tells us that particles in the fermion family, like elelectrons, can never occupy the same ... 09:51: ... planets are generated by dynamos - self-sustaining currents of charged particles. A collision like this could well produce the sort of turbulent motion to ...
	2021-07-21: How Magnetism Shapes The Universe 01:39: It’s generated when electrically charged particles move. 02:30: ... a moving charged particle will feel a force perpendicular to both its direction of motion and to ... 04:21: We can see those tangled field lines in ultraviolet light as charged particles spiral along them, up and down from the Sun’s surface. 04:29: ... that magnetic field out into the solar system - carrying high energy particles with ... 08:30: These are the densest regions of those galactic disks - places where magnetic fields have confined the charged particles of the interstellar plasma. 10:53: The other cool thing that galactic magnetic fields do is that they act as colossal particle accelerators. 11:47: Those fields grab particles of matter and accelerate them to incredible energies, flinging cosmic rays out into the universe. 15:28: ... measurement of photon number we get countably infinite splits, and for particle position it’s uncountably infinite splits per ... 15:47: If you mean every possible configuration of particle properties in the universe - then the answer is there are infinite worlds. 15:54: A world for every infinitesimal difference in every particle property. 15:58: For example, particle position wavefunction is typically a smooth distribution of possible locations - some more probable than others. 16:18: To get this sort of splitting, two parts of that wavefunction need to influence other particles in ways that are distinguishable from each other.
	2021-07-13: Where Are The Worlds In Many Worlds? 04:23: ... particle position and momentum and orientation is chosen from a vast array of ... 06:11: ... a great cosmic wavefunction that includes every electron and every other particle in the ... 06:23: ... wavefunction, which encompasses the piece-wise wavefunctions of many particles as it makes its way to ... 07:42: ... slit, we had two broad classes of world - one for each slit that the particle may have passed ...
	2021-07-07: Electrons DO NOT Spin 01:26: ... far more fundamental than simple rotation - it’s a quantum property of particles, like mass or the various charges. But it doesn’t just cause magnets to ... 08:50: ... But let me say a couple of things to give you a taste. They describe particles that have very strange rotation properties. For familiar  objects, ... 10:30: A particle's momentum is fundamentally  connected to its position. 10:47: Meaning you can represent a particle wavefunction  in terms of either of these properties. 11:05: Well it's angular position. In other  words the orientation of the particle. 12:02: ... say that particles described by spinors have spin quantum numbers that are half-integers - ... 12:13: ... onto whichever direction  you try to measure it. We call these particles fermions. Particles that have integer  spin - 0, 1, 2, etc. are ... 15:31: ... high. Energy was as spread out as it could get between all of the particles and the different  ways they could move. The low gravitational ... 16:45: ... say you have a bunch of particles that are not entangled with each other but are all entangled with ...
	2021-06-23: How Quantum Entanglement Creates Entropy 01:02: ... laws arise from the statistical   behavior of large numbers of particles. For example, a room full of air has a temperature,   ... 01:45: ... than the properties and   laws governing individual particles. Entropy IS a thermodynamic property, and the 2nd law   is ... 02:48: ... in terms of the number of configurations   of particles that give the same set of crude thermodynamic properties. For ... 03:45: ... gain by making a measurement on the system.   If all the particles are bunched up in the corner then measuring their exact positions ... 05:55: ... driven by entanglement - this mysterious connection between quantum particles that Einstein called   “spooky action at a distance”. As a bit ... 07:14: ... that can exhibit these superposition states - like a   particle simultaneously having spin up and spin down as revealed in the ... 11:00: ... - but as a  quantum object interacts with the countless   particles of a macroscopic environment, and those particles interact with ... 11:50: ... the coin’s countless   constituent quantum parts and every particle they’ve ever interacted with. That network of   entanglement IS in a ... 12:35: ... about the detailed quantum states of all particles becomes increasingly inaccessible,   leaving only crude ... 17:55: ... said that the uncertainty in the final momentum of   the particle is roughly equal to the momentum of the photon used to measure that ...
	2021-06-16: Can Space Be Infinitely Divided? 03:47: ... will happen,   you’ll always have an uncertainty in the  particle’s final momentum that’s roughly equal   to the momentum of the ... 08:37: ... we want to precisely   define the position of an elementary particle - let’s say an electron. To define its position   we need to be ... 09:58: ... uncertain.   In the same way that you get virtual particles on subatomic scales, on the Planck scale you   get virtual ...
	2021-06-09: Are We Running Out of Space Above Earth? 14:49: ... you could somehow get an elementary particle like an electron within that range then perhaps it would be absorbed and ... 15:02: That will happen long before the next particle is likely to hit it.
	2021-05-25: What If (Tiny) Black Holes Are Everywhere? 01:51: It came from thinking about how black holes interact with the quantum fields from which all elementary particles arise. 02:17: To a distant observer it would look like the black hole is radiating particles. 02:28: The distribution of particle energies should follow a blackbody spectrum, as though the black hole has a real temperature. 02:36: In the common pop-sci description of Hawking radiation you often hear about particle-antiparticle pairs appearing at the event horizon. 02:52: ... the wavelength of the emitted particles are about the size of the whole event horizon, so they sort of emerge ...
	2021-05-19: Breaking The Heisenberg Uncertainty Principle 01:31: Perfect knowledge of a particle’s position means its momentum is undefined. 02:31: He hit on it while considering what would happen if he wanted to measure the position of a particle with a photon. 02:37: ... reasoned that the photon would give the particle a momentum kick, which would account for a greater uncertainty in its ... 03:31: ... how can a quantum object sometimes be a “wave” and some times be a “particle?” In a sense it is both, and in a sense it is neither - rather, there are ... 04:30: ... for example, if we only care about a particle’s position we can in principle measure it to extreme precision as long as ...
	2021-05-11: How To Know If It's Aliens 15:39: ... a way to protect the ship from impacts because hitting even a tiny particle at those speeds would be devestating. So people have actually looked ... 16:32: ... 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 ... 17:34: ... certain types of supersymmetric counterparts to the standard model particles might serve as dark ...
	2021-04-21: The NEW Warp Drive Possibilities 14:04: We’ll start with the muon g-2 result, which revealed a possible a crack in the standard model of particle physics. 14:09: A few of you asked whether similar experiments could be performed using the tau particle. 14:18: The probability that a particle will interact with other massive virtual particles is proportional to the square of that particle’s own mass. 14:26: At nearly 17 times the mass of the muon, the tau should be even more sensitive to unknown particles. 14:41: ... makes it pretty hard to watch tau particles precess in magnetic fields, and so far the g-factor for the tau hasn’t ... 14:52: That said, there are other ways to track a particle’s interactions with virtual particles. 15:01: ... decays products are sensitive to the complex interactions with virtual particles that happen during the ... 16:49: So a particle at an instant in time really does have an instantaneous velocity.
	2021-04-13: What If Dark Matter Is Just Black Holes? 00:30: ... most dark matter hunters are trying to hypothesize or detect exotic new particles to explain the stuff - and we recently discussed some of the ... 01:25: ... dark matter - it’s more than we can say for any of the other dark matter particle ...
	2021-04-07: Why the Muon g-2 Results Are So Exciting! 00:29: (bright music) The Standard Model of particle physics describes the elementary building blocks of nature with incredible success. 01:56: ... comes from the part of the Standard Model that describes how particles with electric charge interact via the electromagnetic force, quantum ... 02:05: One of the interactions that QED describes is how a charge particle will tend to rotate to align with a magnetic field. 02:13: The strength of that interaction is defined by something called, the g-factor for the particle. 02:31: If this works so well for electrons surely it works for other particles too. 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 ... 04:33: In this theory, electromagnetic interactions result from charge particles communicating by exchanging virtual photons. 05:14: For a deeper dive in Feynman diagrams, virtual particles, and quantum electrodynamics, we have you covered, episode list in the description. 05:57: Same particles in and same particles out, but a slightly more complicated sequence of events. 06:48: Measure that leftover bit and you are testing the sudless interactions of the particle. 07:01: An obvious next step is to do the same for other particles. 07:08: It has two heavier cousins, the muon and the tau particle. 07:43: The quantum vacuum is seething with an incredible variety of possible virtual particles. 07:58: ... when we include every possibility encompassed by the Standard Model of particle physics, we get a g-factor that's ever so slightly off the experimental ... 08:19: The probability of interaction between a particle and some massive virtual particle is proportional to mass squared. 08:39: And it's 40,000 times more likely to encounter any completely unknown virtual particles that might be hiding out there. 08:46: Accounting for all of the known particles, still gives a Muon g-factor that's off. 08:51: So the rising hope, is that an as yet unknown particle is at work here. 10:02: The frequency of the precession also governs the energy of the particles that these muons decay into. 10:08: ... by measuring the energies of those particles, positrons in particular, the researchers can determine the precession ... 10:19: ... ago, physicists at the Large Hadron Collider thought they detected a new particle based on a slight bump at a particular energy of the decay ... 11:10: ... error, some unknown factor influencing the measurement that is not a new particle, the g-2 team worked very hard to rule anything like that ...
	2021-03-23: Zeno's Paradox & The Quantum Zeno Effect 07:47: ... as the freezing of quantum tunneling - the same phenomenon that allows particles to “teleport” out of nuclei during nuclear ...
	2021-03-09: How Does Gravity Affect Light? 00:38: ... 1783, the English clergyman John Michell proposed that a particle of light gripped by the gravitational field of a sufficiently massive ... 00:52: ... the subject, and Cavendish followed similar reasoning to predict that a particle of light would be deflected in its path as it passed near a massive ... 01:17: ... of gravity was the full picture, and that light behaves like any other particle in response to Newtonian ... 04:47: ... redshift is exactly the same as is required to turn a light-speed particle around and have it fall back, as calculated by Michell from totally ... 06:57: ... imagine light as a perfectly narrow ray, or even as a massless, timeless particle, none of our intuitive explanations say that it should be deflected by ... 07:24: The Dutch physicist Christiaan Huygens disagreed with Newton on many things - including the idea that light is a particle. 12:32: Light is a wave and a particle; time slows or space flows in gravitational fields.
	2021-02-24: Does Time Cause Gravity? 02:58: ... we move particles through time according to those velocities, we have this sense of time ... 03:36: Each atom, each subatomic particle trying to tick at its own rate. 05:57: ... direction into space - although technically photons and other massless particles don’t have a 4-velocity, which is defined according to the ticking of ... 07:05: Like - what about a particle with no size - supposedly point-like particles like electrons, quarks, etc. 08:08: ... ways to see how the flow of time determines the path of even timeless particles. ...
	2021-02-17: Gravitational Wave Background Discovered? 00:00: ... weird quantum forces neutron stars tend to channel jets of high energy particles due to their intense magnetic fields they also rotate rapidly with the ...
	2021-01-26: Is Dark Matter Made of Particles? 00:00: By the time I finish this sentence, up to a billion billion dark matter particles may have streamed through your body like ghosts. 00:07: The particle or particles of the dark sector make up the vast majority of the mass in the universe - so to them, you are the ghostly one. 00:39: Even more disturbing is that there doesn’t even seem to be a candidate for dark matter in the known family of particles. 00:45: ... eerie reality of the dark sector - perhaps there’s an entire family of particles that exists in parallel to those we can see - a dark universe that ... 01:07: When we talk about the “dark sector” we typically mean a particle or family of particles that contribute to dark matter. 01:13: Now it’s possible that dark matter is not particles - it could be black holes or failed stars or even weirder so-called “compact objects”. 01:36: ... the Standard Model - which describes the behavior of the known family of particles with incredible ... 01:44: ... visible universe is made of these particles, interacting with each other through the standard model forces - the ... 01:55: In general, the behavior of a particle is determined by the forces it interacts with. 02:00: We can think of forces as the languages that particles use to communicate. 02:05: Any electrically charged particle experiences the electromagnetic force and can communicate with other charged particles by exchanging photons. 02:14: But for an electrically neutral particle like a neutrino, electromagnetism is a language it doesn’t speak. 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. 02:34: ... fields fill the universe, overlapping each other - and if a particle field is connected to - coupled with a force field then it can speak the ... 02:45: The force of gravity is a sort of lingua franca, a common language that every particle with mass can speak. 02:58: The main requirement for a dark matter particle is that it doesn’t “speak electromagnetism”. 04:07: And that tells us a lot about any prospective dark matter particle. 04:51: More accurately, it tells us how far dark matter particles were able to travel in the early universe. 04:57: ... “free-streaming length” of dark matter is how far a dark matter particle could travel before interacting with something - typically another such ... 05:25: ... let’s review - if dark matter is a particle, it’s electrically neutral and doesn’t interact much with itself, and ... 05:35: For a long time people thought the neutrino might be dark matter - being neutral and the most abundant known particle in the universe. 05:52: ... gets physicists very excited - because discovering a dark matter particle may be our best for finding a bigger, deeper theory than the standard ... 06:06: It would also be a no-brainer Nobel prize - and many researchers have devoted their lives to hunting down this particle. 06:17: ... type searches for new evidence out there in the universe or in our particle experiments here on Earth for evidence of particles that don’t fit the ... 06:25: The other delves deep into theory - in speculative mathematics beyond the standard model for signs of new particles. 07:25: This is a weird little particle that popped up in the math when physicists were trying to solve another mystery of physics - the so-called CP problem. 07:52: Explorations of the theoretical landscape have led physicists to multiple possibilities for dark matter particles. 08:07: ... an extension of the standard model which proposes that all the regular particles - both matter and force-carrying - have twins - counterparts on the ... 08:18: Every matter particle or fermion has a supersymmetric force-carrier, or boson. 08:25: ... expected that these supersymmetric particles are much heavier than their standard model counterparts - and that may ... 08:42: ... supersymmetry is called a ‘neutralino.’ It’s a sort of ‘three in one particle’ where the electrically neutral superpartners of the Z boson, photon, and ... 08:55: In some models these are the lightest supersymmetric particles possible - ”LSPs” - but they’re still incredibly heavy. 09:03: ... to decay to lighter things, if these can’t decay into Standard Model particles then they’d be stable and long lived- an almost perfect dark matter ... 09:26: ... expected mass of these particles is eerily close to the mass expected for a certain type of dark matter - ... 09:45: ... dark matter particles like the neutralino are examples of a general dark matter particle type ... 09:59: It’s a description of what some physicists thought dark matter particles had to be like- which is to say, weakly interacting and massive. 10:07: ... you want to make up 80% of the mass in the universe, and also slows the particle down - helps make it ... 10:33: ... idea is this: In the first fractions of a second after the Big Bang, particles and their antimatter counterparts would have been popping into existence ... 10:46: And then when the particle bumps into its antiparticle they both annihilate, releasing that energy again. 10:57: We were left with a universe full of particle-antiparticle pairs that would then just annihilate over time. 11:02: But its possible some particles may not have been able to find an antiparticle counterpart before the expanding universe pulled them too far apart. 11:20: The universe didn’t expand fast enough to throw these particles apart, and so almost all annihilated. 11:36: ... out you can do a calculation of what interaction strength such a relic particle would need to have in order to survive in sufficient numbers to give us ... 12:03: ... possible that an entire ecosystem of particles are going about their dark business across the universe - interacting by ...
	2021-01-19: Can We Break the Universe? 14:15: ... of quantum mechanics is "true" is like asking if light is made up of particles or if light is a ...
	2021-01-12: What Happens During a Quantum Jump? 05:34: ... and others were using the behavior of systems of many, many individual particles to infer the behavior of individual ... 05:44: He believed that it was completely nonsensical to even think about single particles.
	2020-12-22: Navigating with Quantum Entanglement 04:56: Magnetic fields exert a force on a moving or rotating charged particle. 06:08: When two particles are entangled, it means one or more of their quantum properties are correlated. 06:14: ... an apparent faster-than-light influence - measure the property of one particle and you instantaneously influence the entangled ... 09:49: ... in highly controlled environments - ideally isolated systems of very few particles, perhaps in a vacuum or near absolute zero ...
	2020-12-15: The Supernova At The End of Time 15:25: ... time in the double slit experiment, because after the measurement of particle position is made, the state of the wavefunction before that measurement ...
	2020-12-08: Why Do You Remember The Past But Not The Future? 02:40: ... it formed billions of years ago, before even Earth formed, when tiny particles of dust from a past supernova found each other in the forming solar ... 03:15: ... physicist could measure the exact positions and velocities of every particle comprising the asteroid and calculate their paths backwards to recover ... 04:02: ... age of the universe and the asteroid will decay into a mist of subatomic particles. ... 04:23: ... in the crazy energy of the early universe, a positron and a neutral pion particle combine to form a ... 04:41: Let’s say this process is reversible - the particle physics jury is still out on whether protons can decay - but for this episode they can. 06:02: ... “Feynman diagram” of our asteroid looks like countless particles coming together in many different ways - first subatomic particles ... 06:34: ... asteroid just assembles from subatomic particles with all of its detailed structure mysteriously in place - cosmic ray ... 07:25: Even if we can’t perfectly retrace its formation down to the subatomic particle, it has many crude features that recall that past. 08:36: ... we have an asteroid formed from an incredibly improbable coalescence of particles - but the most improbable things are yet to ... 09:01: It had a streak that freakishly already matched a particle buzzing towards it but hadn’t hit yet. 12:45: ... Particle locations were restricted to being very close to each other - a state ...
	2020-11-18: The Arrow of Time and How to Reverse It 01:38: ... the direction of time? Basically, if you reversed the motion of all particles in the universe - sent them back exactly in the direction they came, and ... 02:08: ... in a particular sequence, like a flip book. OK, so imagine two particles moving towards each other - let’s say, electrons. They move up in time ... 05:10: ... start with a handful of particles with low entropy. You can do low entropy by having a weird distribution ... 06:19: ... of the starting, low-entropy point, you perceive an asymmetry in time - particles expanding, entropy increasing on one side, or particles converging,and ... 06:57: ... and, typically, on very small scales due to random alignments of particle trajectories or however else energy is moving around. Entropy can ... 07:17: ... the universal arrow of time? Well it’s no accident I chose “expanding particles” to illustrate evolving entropy. When we measure the velocities of ... 08:11: ... it right now. But one possible consequence is that if you trace all particles backwards in time to this original “special” slice, at which velocities ...
	2020-11-11: Can Free Will be Saved in a Deterministic Universe? 00:57: ... current state of the universe, like the positions and velocities of all particles, and perfect knowledge of the laws of nature could calculate perfectly ...
	2020-11-04: Electroweak Theory and the Origin of the Fundamental Forces 00:02: We have a weird zoo of elementary particles, which interact through very different fundamental forces. 00:47: And this dive into electroweak unification will lead us inevitably to the Higgs field and an understanding of how particles gain mass. 01:17: The electron was called a beta particle by Ernest Rutherford back in 1899 before we knew that these things were electrons. 01:24: It’s one of the main ways radioactive nuclei decay - the other being alpha decay, where the emitted “alpha particle” is really a helium-4 nucleus. 01:54: Basically, he tried to model this as a direction interaction - in which all four “fermion” particles literally touch. 02:36: ... effort was quantum electrodynamics, in which charged particles interact not by actually touching - but via a mediating particle that ... 02:50: By the way, force-mediating particles are bosons, as opposed to the fermions that make up matter. 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. 03:12: Given that the weak interaction could change a neutral particle into a pair of charged particles this mediating particle must itself be charged. 03:20: This was an early hint that somehow the electromagnetic force, which acts on charged particles, was playing a role here. 04:33: ... see, the simple requirement that the weak force was mediated by massive particles ultimately unified the weak force with electromagnetism, and revealed ... 04:50: ... probabilities of certain outcomes being measured for observables like particle position and ... 05:50: That resulted in a new quantum field and a corresponding particle. 08:08: The fields and corresponding particles produced by the pure symmetries we described are fundamentally massless. 09:56: But the individual magnetic particles interact with each other, they want to align with their neighbours. 10:03: ... temperatures - above the Curie temperature - thermal energy causes the particles to rotate randomly so the overall magnetization of the material is ... 10:13: However, if we cool the material down, the interactions between magnetic particles can start to come into play. 10:23: If we cool the system enough all particles get frozen into one aligned state. 12:18: ... was the electroweak era, and we can also produce these conditions in our particle accelerators - and in fact we’ve verified this whole electroweak thing ... 12:39: The very existence of those symmetries requires a family of fields and particles that we now observe in nature. 13:19: ... from which arises the fantastically rich palette of particles and the complexity they enable, inevitable consequences of the broken ...
	2020-10-27: How The Penrose Singularity Theorem Predicts The End of Space Time 02:16: ... black hole,   singularity and all. Makes sense - if all  particles are falling directly towards each   other on a perfect ... 13:38: ... a boltzmann brain is the simplest  explanation.” You’re just random particles   accidentally assembled from the void with your current memories and ...
	2020-10-20: Is The Future Predetermined By Quantum Mechanics? 04:08: All particles take on defined properties, and one actual reality is chosen from the many possible ones. 11:10: ... that doesn't have multiple realities, just a wave function that guides particles in a perfectly determined way defined by Bohmiam ... 14:59: ... state of the brain, the momentary spatial configuration of its particles at that instant that gives rise to our conscious ...
	2020-10-13: Do the Past and Future Exist? 01:27: ... - the idea that, by knowing the current position and velocity of every particle in the universe, as well as the forces that act between those particles, ... 02:08: Newton assumed that all particles, all observers, all points in space were ruled by a single, constantly ticking clock.
	2020-09-21: Could Life Evolve Inside Stars? 02:31: ... materials, where the direction of the poles of the little magnetic particles changes across the ...
	2020-09-08: The Truth About Beauty in Physics 05:32: ... within circles could describe the motion of anything, from a planet to a particle of air - but it wouldn’t explain that ... 11:43: ... for the slightly ugly but fantastically successful standard model of particle ... 15:11: ... Awesome Octagon dropped some knowledge on a different next-generation particle collider that's worth ... 16:35: Particle.
	2020-08-24: Can Future Colliders Break the Standard Model? 00:02: ... a theory of everything, and by eggs I mean a billion billion subatomic particles obliterated in the next generation of giant particle ... 00:18: ... June, the consortium of Europe’s top particle physicists published their vision for the next several years of particle ... 00:28: ... is the Future Circular Collider, which, if it happens, will accelerate particles in a 100 kilometer circumference underground ring encircling ... 00:38: ... size of the Large Hadron Collider, and it would be capable of colliding particle beams with 8 times the current LHC ... 01:16: Physicists have been building machines to accelerate and subsequently obliterate particles since the 1920s. 01:22: ... or linac, which uses oscillating electric fields to accelerate charged particles in a straight line, while the beam is focused by magnetic ... 01:32: ... cyclotron quickly followed - here the particles are still accelerated by electric fields, but now a constant magnetic ... 01:41: Once accelerated, the particles were typically slammed into a motionless target - often just a slab of metal. 01:47: Some particles would collide with enough energy to be destroyed, and their energy would be released in the form of new particles. 01:55: ... those first collision experiments, all sorts of never-before-seen particles were observed allowing physicists to begin to map out the subatomic ... 02:03: There’s a serious limit to the energy you can muster by colliding particles into a stationary object. 02:29: The key to doing this is to store the particle beams in a ring so that they can be collided at your leisure. 02:37: To that end, the particle storage ring was invented by Gerard K. O’Neill in the mid 1950s. 02:44: Within a few years, an Italian group built the first particle beam collider - the AdA, or Anello di Accumuliazione. Apologies for my pronunciation. 03:08: In collider-speak, luminosity is a measure of the number of particle collisions across an area over a time period. 03:15: More collisions means more chance of producing weird particles. 04:09: ... top quark, and so enabled the discovery of the final Fermion - or matter particle - in the standard ... 04:46: The existence of the Higgs confirms our explanation of how the elementary particles acquire mass - which of course we’ve covered previously. 04:56: In a sense this was the last missing piece of the standard model - the one remaining particle that physicists thought MUST exist. 05:04: ... particle hunters expected that to be just the beginning - that their giant ... 05:14: The most highly anticipated were the particles predicted by supersymmetry - or SUSY. 05:25: ... forces, and a huge difference between the measured masses of the known particles and what we expect their masses to be from quantum field theory ... 05:40: The Higgs particle in particular should have an enormous mass if our Standard Model understanding is the whole picture. 05:58: SUSY solves the hierarchy problem by proposing symmetric counterparts to the known particles. 06:02: ... those counterparts should help cancel out the interactions of the known particles with the elementary quantum fields on which those particles live, ... 06:26: The Large Hadron Collider reaches energy a few times higher than the top of that range, so it should have seen such particles by now. 07:00: It doesn’t seem to give us a particle that could explain dark matter. 07:07: ... that unifies our understanding of the Standard Model’s motley zoo of particles and forces, we probably need to achieve higher energies - energies even ... 07:25: ... other clever ways to probe these energies - for example using natural particle accelerators like the sun or supernovae or quasars or galactic magnetic ... 07:41: ... ultra-high energy cosmic rays are rare, and to reliably detect a new particle we need to watch the result of billions of billions of collisions - we ... 08:37: ... of this upgrade isn’t primarily to access higher energies where new particles might exist, but rather to make the LHC much better at studying the ... 08:47: IF either SUSY or other very high-mass particles do exist, then they may be actually a good way beyond the energy range of the LHC. 09:11: ... and positrons with the express intention of making as many Higgs particles as possible. Okay firstly, why electrons and ... 09:25: ... remember that the first particle colliders worked with electron-positron beams, and for good reason: they ... 09:33: It’s easier to achieve the energies and luminosities to produce, for example, large numbers of Higgs particles in relatively clean collisions. 09:59: The Higgs can also be used as a direct search for new particles. 10:24: However there’s no guarantee that any new particles exist in the expanded energy range that the FCC will probe. 10:41: Ever since Europe won the giant collider game with the LHC, particle physicists in the US have focused on smaller experiments. 10:58: ... - and when we visited FermiLab earlier this year we saw the linear particle accelerator that is under development to become DUNE’s neutrino ... 14:04: If any of those particular protons happens to produce a previously undiscovered particle in the collider, we’ll be naming it the Alec S-L-ino. 15:40: In principle there should be a point right at the center where there is no flow - if you were a point-like particle you could just hang there.
	2020-08-17: How Stars Destroy Each Other 04:38: ... charged particles spiral along the magnetic field lines they emit synchrotron radiation, ... 06:16: ... powerful magnetic field channels high energy particles into a jet that traces a circle across the sky - and often sweeping past ...
	2020-08-10: Theory of Everything Controversies: Livestream 00:00: ... joining forces to bring together some of the leading researchers uh in particle physics and in cosmology to look for a way forward brian great to have ...
	2020-07-28: What is a Theory of Everything: Livestream 00:00: ... here uh uh quick introductions so we have james beacham who's a particle physicist with um the atlas experiment at the large hadron collider at ...
	2020-07-20: The Boundary Between Black Holes & Neutron Stars 13:53: A couple of you asked why we think there had to be an actual imbalance in the number of antimatter versus matter particles in the early universe. 14:12: Cool thought - but that doesn’t work because when they are created, each particle - antiparticle pair is close together.
	2020-07-08: Does Antimatter Explain Why There's Something Rather Than Nothing? 00:22: ... particle in our universe has its exact counterpart: an anti-particle identical in ... 01:25: ... little more matter compared to anti-matter. If there were slightly more particles than anti-particles, then almost everything would have annihilated, ... 01:56: And there’s the mystery: why were particles created with that 1-in-a-billion overabundance compared to anti-particles? 02:04: ... be something inherently different in the way the universe interacts with particles versus anti-particles. The universe must not treat the two ... 02:12: ... the universe is reflected through a mirror; and time reversal, where all particles have their direction of motion and spins exactly ... 02:51: ... you apply all three of these transformations to a particle - if you apply a CPT transformation - then it becomes its own ... 06:00: ... more exotic antimatter like anti-protons can be created in particle accelerators - just by smashing regular matter together. The problem is, ... 07:21: ... These high-energy protons then hit a metal target and produce a zoo of particles and anti-particles. Some of these by-products are ... 09:19: ... determined by many different factors: the precise mass and charge of the particles, their orbital angular momentum, their magnetic and electric dipole ...
	2020-06-30: Dissolving an Event Horizon 05:33: That radiation cian be any type of elementary particle - but in the case of the most massive black holes, it’s mostly just photons. 06:31: ... us with a strange situation - in the far distant future, even if all particles in the universe decay, we may be left with only radiation and these ... 09:37: Then surely we can just throw charged particles into the black hole. 09:41: ... have to be careful, because those particles increase the mass of the black hole as well as the charge - and if the ... 13:46: Inyobill asks if we’re assuming that the lightest particles are without dimension, so they have an undefined size relative to the universe. 13:59: A pointlike particle has size zero - that’s zero volume, zero radius. 14:17: ... an interaction crosssection, which defines the probability of another particle interacting with the electron as a function of ...
	2020-06-22: Building Black Holes in a Lab 05:25: ... as a type of radiation. The popular description is that pairs of virtual particles appear near the event horizon and are separated - one escapes and one ... 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. 06:33: ... is that energy gets sapped from the black hole because the infalling particles-slash-vibrations themselves acquire negative energy. This effect on the black hole is ... 08:04: ... that rotating black holes can donate some of their rotational energy to particles or waves that pass close by. This is the Penrose process, and when the ... 09:09: These waves are analogous to incoming particles. The waves are only 1 millimeter high, but superradiance can increase their height by as much as 10%. 10:13: ... of the Hawking radiation. Taking the temperature of the evaporating particles from a BEC provides the strongest direct experimental evidence for ...
	2020-06-15: What Happens After the Universe Ends? 00:45: ... exponentially to to an unthinkably large size, and every black hole and particle has decayed into faint radiation .... that infinite stretch of space and ... 06:11: For light, or any light-speed particle, the beginning and end of every journey is the same. 07:06: ... will decay - black holes will evaporate by Hawking radiation, and particles of matter will decay into their lightest possible ... 07:16: ... and positrons, and neutrinos, as well as gravitons - the quantum particles of ... 07:46: The standard model of particle physics predicts eternal electrons. 07:53: ... masses of the elementary particles are not some fundamental property of those particles - they come from ... 08:17: Surely it was full of particles. 08:19: Well yeah, but those particles were effectively massless also. 08:24: Two ways to think about this: A particle's energy is a combination of its kinetic energy and rest mass energy. 08:31: Kinetic energies were so high at the big bang that rest mass energy was completely negligible - all particles behaved like light-speed particles. 08:57: ... field - if it decayed to a lower energy - could eliminate elementary particle masses in the late universe ... 09:05: In the first tiny fraction of a second we can think of the universe as being full of effectively or actually massless particles. 11:10: Only radiation - light and other massless particles - can cross over this conformal boundary from one aeon into the next.
	2020-05-27: Does Gravity Require Extra Dimensions? 05:14: ... but we all know that the apparently 2-D ground is made up of 3-D particles, and if we zoomed in on a seemingly flat floor to small enough scale, we ... 11:58: This is the negative pressure due to the exclusion of quantum vacuum modes, or virtual particles, between two very closely separated plates.
	2020-05-11: How Luminiferous Aether Led to Relativity 04:06: ... Newton also favoured his own corpuscular theory of light - light as tiny particles rather than ... 05:08: ... versus Newton. Light as a wave versus a particle. Most accepted Newton - as most always did. This was until the beginning ... 12:25: ... the near vacuum state of spacetime in which quantum physicists believe particle pairs are quickly born and destroyed. In retrospect, Descartes seems ...
	2020-04-28: Space Time Livestream: Ask Matt Anything 00:00: ... simple theory of everything there's a TED talk it's an e 8 theory for particle physics and Garrett Lisi found it says here say so so our leasing can ...
	2020-04-22: Will Wormholes Allow Fast Interstellar Travel? 01:09: ... idea - but not into a theory of wormholes - instead as a theory of particles. Einstein and Rosen imagined two regions described by the Schwarzschild ... 01:52: ... turns out that this is almost certainly NOT what particles are, but the Einstein-Rosen paper inspired others to take the wormhole ... 02:08: ... for another 20 years before it was resurrected - this time not to build particles, but in an attempt to break causality. John Archibald Wheeler, along with ... 15:35: ... hydrogen - protons stripped of their electrons, with densities between 1 particle per cubic centimeter and 1 particle per cubic meter. It's vacuum-y ...
	2020-04-14: Was the Milky Way a Quasar? 02:33: ... astronomers believe that when dark matter particles crash into and annihilate each other, the result could be a fireworks ... 04:15: The protons sometimes obliterate each other to form a neutral pion particle plus some other stuff.
	2020-04-07: How We Know The Earth Is Ancient 07:17: ... atomic nuclei decay into lighter nuclei by splitting or by ejecting particles. The rate of decay is expressed in terms of “half-life” - which is the ...
	2020-03-31: What’s On The Other Side Of A Black Hole? 12:02: ... Mich always thought entanglement could only occur between two particles. What you're thinking about is the principle of monogamy of entanglement, ...
	2020-03-24: How Black Holes Spin Space Time 10:51: ... of space in the ergosphere spins up the magnetic field into a gigantic particle accelerator. Charged particles are accelerated along those magnetic ...
	2020-03-16: How Do Quantum States Manifest In The Classical World? 00:57: ... properties can be expressed as superpositions - for example a particle’s position can be expressed as a superposition of momentum states. I’ll ... 02:56: ... quantum particles have a property called quantum spin. That spin has an axis that points ... 04:28: ... A high energy photon decays into an electron and a positron. These particles both have spin values of 1/2, but the original photon had spin 0. So the ... 05:32: ... crazy thing is if I measure the spin of one particle - say the electron - my choice of measurement basis defines the spin of ... 06:24: ... happening when I try to measure the spin of one of those entangled particles. I’ll try to do that in the most subtle way possible. Here’s our ... 10:41: ... out why this might be the case. It turns out that as more and more particles join our entanglement web, information about quantum states get spread ... 10:53: ... possible to extract this information if you could perfectly measure all particles in your measurement device. But eventually this entanglement cascade ... 12:33: ... Cat? Well an important example of a pointer state is the position of a particle. Most quantum interactions depend heavily on the relative location of ... 13:47: ... consistent entanglement, even spooky-action-at-a-distance entangled particles maintain their correlations, no matter how far separated in boring old ... 16:29: ... to produce a new big bang? Could a random perfect alignment of all particle trajectories produce a big bang density? Maybe - some physicsts think ...
	2020-03-03: Does Quantum Immortality Save Schrödinger's Cat? 13:33: ... in a typical quantum eraser experiment you use entangled photon or other particle pairs - one of the pairs goes through a double-slit experiment and the ... 13:59: ... true decoherence - relative phase information is spread across only two particles, and so decoherence is ... 14:38: Well these days double-slit experiments are usually done with single photons or other particles. 14:54: ... of a typical double-slit experiment without actually scattering off air particles, and more minor interactions don't necessarily decohere the light - ...
	2020-02-24: How Decoherence Splits The Quantum Multiverse 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. 04:57: Because the wavefunction is amplified at that spot, there’s a high probability of the particle landing there. 05:22: That’s destructive interference and the probability of the particle ending up there goes to zero. 05:36: And so on - so we ultimately see this series of bands - lots of particles where the wavefunction is amplified, few where it’s canceled. 07:54: For example, add a collection of particles to one of the slits. 07:58: The part of the wavefunction - corresponding to a possible path of the photon - is now disturbed by those particles. 08:05: ... slice as the “possible photon” being absorbed and reemitted by those particles, and so the wavefunction leaving that slit picks up a random phase offset ... 09:54: We can think about the photon wavefunction becoming mixed with the wavefunctions of the quantum particles along this chain. 11:25: The once coherent particles with their superposition of both separate histories that could merge, become decoherent. 13:34: That includes yourself and your measuring device, unless you know the exact quantum state of all of the particles of both.
	2020-02-18: Does Consciousness Influence Quantum Mechanics? 02:40: ... of this experiment by saying that the electron does NOT travel as a particle or as a physical wave along one of these ... 13:01: ... - a little about he laundry detergent, but mostly about the hypothetical particle that might solve the mystery of dark matter - if we could just detect ... 13:54: ... mean right at the beginning - before the Higgs mechanism gave elementary particles their ... 15:01: ... Francisco Martinez asked whether we would get new quantum fields and new particles if other fundamental constants turned out to vary over space, in the ... 15:25: Would it be a quantum field with particles? 15:28: ... theta field yields particles because it has a lowest energy state - a value for theta where potential ... 15:37: ... field can oscillate within that dip - and that oscillation is our axion particle if you also assume quantized energy ... 15:49: ... are just scaling factors and so varying them shouldn't lead to quantum particles - but perhaps other constants could give us a ...
	2020-02-11: Are Axions Dark Matter? 00:51: ... the unexpected discovery? A brand new particle - the axion - which, while not yet proven to exist, may explain a much ... 01:05: ... sign of the x, y, and z axes. Another example is flipping the charges of particles - positive to negative and vice versa - most of the equations of physics ... 02:11: ... quarks together into protons and neutrons, and is mediated by the gluon particle. ... 03:59: ... state of a field - which is what you’ll find when there are no actual particles around, and as we saw in previous episodes, the vacuum is a very lively ... 05:16: ... why theta should be zero - at least not within the standard model of particle physics. This fundamental constant may have ended up very close to zero ... 06:54: ... you might recall that in quantum field theory a particle is just an oscillation in a quantum field. So with a new field - this ... 07:53: ... how can we expect to detect such an elusive particles? Well, even though axions have no electric charge, they can still ... 11:03: This all seems like a lot of work for a hypothetical particle predicted from speculative math. 11:08: ... and only weak interactions via the other forces. And although these particles are extremely light, axions, if they exist, are likely to have been ... 12:47: ... compares that to an estimate of the number of possible configurations of particles in the universe - 10^90 factorial. Now, I assume Ethan got that number ...
	2020-02-03: Are there Infinite Versions of You? 01:41: ... a raffle draw in which there are as many raffle tickets as there are particles in the ... 03:19: ... conditions in any given region - like positions, velocities, etc of all particles - perfectly determines the future history of any point with that ... 03:57: ... probability of getting every particle just right is unthinkably smaller than the already unthinkably small ... 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. 07:12: I should also note that it’s not just the particles that define starting conditions, there’s also the laws of physics themselves. 07:24: ... repetition of both the laws of physics AND the arrangement of particles. ... 07:55: ... things like the mass or charge or other properties of individual particles, an infinite range means going to very, very high values for these ... 08:48: ... histories because the number of possible configurations of particles at every instant is still ... 14:20: RobTheImpure would like to know what is meant when we talk about "spaceless timeless particle scattering" in the context of the s-matrix. 14:32: How can particles scatter off each other without some notion of cause and effect or location? 14:37: Well to start with, there is a causal order for the incoming and outgoing particles - the former cause the latter, and so they must come first. 15:00: Imagine an interaction where an electron emits a virtual photon which then deflects another particles - say, a proton. 15:42: ... t channel is where 2 particles scatter off each other by exchanging a virtual particle, while the ...
	2020-01-27: Hacking the Nature of Reality 00:00: In particle physics we try to understand reality by looking for smaller and smaller building blocks. 02:16: ... clockwork of reality led to quantum field theory, in which all particles are described by vibrations in elementary fields that fill the universe, ... 03:24: Those nuclear particles were originally thought to be elementary - to have no internal structure, just like the electron. 03:33: But new experiments were revealing that they seemed to have some real size - as though they were made of yet-smaller particles. 03:40: ... were scattering experiments - particles were shot into atomic nuclei, and the internal structure was probed by ... 03:50: ... experiments revealed that the forces binding these sub-nuclear particles together must be so strong that space and time should break down at ... 04:25: In this case the observables were the particles that entered and left the nucleus in a scattering experiment. 04:44: The S-matrix is a map of the probabilities of all possible outgoing particles, or out-states, for a given set colliding particles - in-states. 06:04: At the time, nuclear scattering experiments were producing a startling variety of different particles. 06:19: But at the time, prior to the discovery of quarks, no point-like, elementary nuclear particles were known. 06:25: ... than searching for smaller and smaller particles, Chew and collaborators promoted a “nuclear democracy”, in which no ... 06:37: They attempted to build scattering matrices with no elementary particles at all, and with no details of nuclear structure. 07:12: ... of quantum properties like spin, and the assumption of a family of particles that can be involved in the ... 07:53: Imagine two particles scattering off each other. 07:56: Two go in, and two go out - the out particles could be the different to the in particles, or they could be the same just with different momenta. 08:05: ... are two broad ways this can happen as follows: 1) the ingoing particles exchange a virtual particle which deflects or transforms them into the ... 10:33: And as we discussed in our episode on virtual particles, the physical-ness of these states are questionable at best. 12:22: Those fluctuations sometimes caused by individual particles. 13:10: These only emerge later as a consequence of spaceless, timeless particle scattering.
	2020-01-20: Solving the Three Body Problem 13:37: ... with electrons and if they interact again, they make only electrons. In particle beams, neutrinos are made with muons and can subsequently only make ... 14:24: ... >>DOES<< interact in the argon, we can see the path of the particles made in the interaction. From that, we can reconstruct the collision and ...
	2020-01-13: How To Capture Black Holes 06:15: ... in a rotating disk, it will exert a gravitational tug on the surrounding particles. Depending on the local properties of the disk, that can cause the object ...
	2020-01-06: How To Detect a Neutrino 00:07: ♪ (𝘢𝘥𝘥 𝘥𝘦𝘦𝘱𝘦𝘳 𝘴𝘺𝘯𝘵𝘩) ♪ For over half a century, ♪ ♪ this has been the premier particle accelerator facility of the United States. 00:13: ... the super-powered geniuses of Fermilab are tackling ♪ ♪ the most feeble particle in the universe: ♪ (𝘩𝘪𝘨𝘩 𝘥𝘪𝘨𝘪𝘵𝘢𝘭 𝘴𝘺𝘯𝘵𝘩 𝘦𝘯𝘵𝘦𝘳𝘴 𝘳𝘩𝘺𝘵𝘩𝘮𝘪𝘤𝘢𝘭𝘭𝘺) ♪ the ... 00:23: ... ♪ Because, this elusive particle may hold powerful secrets, ♪ ♪ from the unification of the forces of ... 00:42: ... (𝘫𝘰𝘺𝘧𝘶𝘭 / 𝘢𝘯𝘵𝘪𝘤𝘪𝘱𝘢𝘵𝘰𝘳𝘺 𝘴𝘺𝘯𝘵𝘩 𝘨𝘶𝘪𝘵𝘢𝘳 𝘱𝘶𝘭𝘴𝘦𝘴) ♪ So Don is a particle physics researcher here at Fermilab, ♪ ♪ So Don is a particle physics ... 01:27: ♪ (𝘥𝘢𝘳𝘬 𝘴𝘺𝘯𝘵𝘩 𝘧𝘳𝘰𝘮 𝘪𝘯𝘵𝘳𝘰) ♪ ♪ (𝘥𝘢𝘳𝘬 𝘴𝘺𝘯𝘵𝘩 𝘧𝘳𝘰𝘮 𝘪𝘯𝘵𝘳𝘰) ♪ DR. DON: Neutrinos are elementary particles of a type called leptons. 01:31: ♪ ♪ DR. DON (voiceover): That's the same family as the familiar electron ♪ ♪ and it's heavier cousins the muon and tau particle. 01:57: ♪ ♪ ♪ ♪ Neutrinos are among the most elusive elementary particles of nature, ♪ ♪ only interacting by the weak nuclear force and gravity. 03:02: ♪ ♪ Those protons are then smashed into a graphite barrier, ♪ ♪ and as they collide with nuclei they produce all sorts of particles. 03:09: ♪ ♪ More magnetic fields are used to sort the positively charged pion particles from the debris ♪ ♪ and focus *them* into a beam. 05:37: ... in our detector, ♪ ♪ an Argon nucleus is broken apart and charged particles are released - in particular, pions and ... 05:47: ♪ ♪ Those particles then travel through the liquid argon knocking electrons free from atoms. 05:58: ... to the walls of the tank, which lets us trace out the path of the particles ♪ ♪ From those paths, we can learn all about the neutrino oscillation, ♪ ... 07:38: ... ♪ MATT (voiceover): Our best understanding of particle physics tells us that matter and antimatter ♪ (𝘭𝘰𝘸 𝘦𝘯𝘥 𝘰𝘧 𝘴𝘺𝘯𝘵𝘩 𝘧𝘢𝘥𝘦𝘴) ♪ ... 07:51: ... leave a bit of leftover stuff to produce the stars and galaxies and ♪ ♪ particle physicists that we see around us ... 08:31: ... neutrinos in the early universe may have decayed into other matter particles, ♪ ♪ with matter neutrinos producing antimatter particles, ♪ ♪ and ... 09:25: ♪ ♪ ♪ ♪ And that is how you study the most elusive particle in the universe.
	2019-12-17: Do Black Holes Create New Universes? 06:48: ... effect of other stars - and that seems to require the presence of tiny particles of ice and hydrocarbon ... 09:25: Now it may be that in the cores of the most massive neutron stars, some particles can convert into strange quarks. 09:41: And the lower the mass of the strange quark, the easier it is to convert lighter particles into strange quarks.
	2019-11-18: Can You Observe a Typical Universe? 05:45: All particles in the observable universe were packed together in a subatomic-sized dot. 06:01: ... high entropy - iron stars, black holes, and a mist of cold elementary particles, not very hospitable to ... 13:55: To speed that up, we've linked to your amazing lectures on particle physics and general relativity in the description.
	2019-11-11: Does Life Need a Multiverse to Exist? 00:50: ... the speed of light, the Planck constant, the masses of the elementary particles, and the constants defining the relative strengths of the fundamental ... 01:02: ... the general theory of relativity and the standard model of particle physics, there are something like 20 independent fundamental constants ... 07:14: Mess with these much in either direction and the universe remains a mist of subatomic particles. 08:01: Another set of free parameters are the masses of the elementary particles. 08:05: ... are determined by the interaction of those particles with the Higgs field - but again, there’s no apparent pattern and we ... 08:25: ... balance of the strengths of the forces and the masses of the elementary particles, is just right for things like stars and complex matter to form in our ... 09:04: ... which fill all of space and whose oscillations produce the familiar particles of matter or radiation, were expected to have a so-called zero-point ... 09:16: ... should interact with themselves even when there are no particles around, resulting in a quantum buzz of energy everywhere in the universe ...
	2019-10-21: Is Time Travel Impossible? 02:47: We call a particle with imaginary mass a tachyon.
	2019-10-15: Loop Quantum Gravity Explained 00:16: ... to connect our understanding of the tiny scales of atoms and subatomic particles with that of the vast scales of planets, galaxies, and the entire ... 01:58: Like actors on a stage, where the actors are particles and wavefunctions and fields and the stage is the coordinates of space and time. 04:06: In the first formulations of quantum mechanics, that wavefunction describes the distribution of possible positions and momenta of, say, a particle. 05:19: ... of quantum mechanics let you calculate changing properties of a particle- - like its position or momentum - relative to the background coordinate ...
	2019-09-30: How Many Universes Are There? 07:54: Each different configuration results in a different family of particles and also a different cosmological constant. 08:07: But it’s lucky it does – because the resulting particles allow for things like complex chemistry. 08:24: All different vacuum states exist, and our universe necessarily has one that leads to life-friendly particles.
	2019-09-03: Is Earth's Magnetic Field Reversing? 00:38: Magnetic fields exert a force on moving charged particles, causing them to spiral around those force lines. 00:46: Now, that’s helpful, because Earth is constantly bombarded by very fast moving charged particles, especially coming from the Sun. 02:58: ... iron, the sum total of the tiny magnetic fields of their constituent particles align to give a global ... 03:15: Alternatively, flows of many charged particles like electrons – so electrical currents - can produce magnetic fields. 11:54: ... be higher incidents of cancer and other mutation from more high energy particles reaching the ground, and probably we’ll have to get much better at ...
	2019-08-19: What Happened Before the Big Bang? 01:36: ... bizarre property of containing a ton of energy even in the absence of particles. ... 02:24: Other fields like the particle field or the electromagnetic field are described by multiple components and vectors instead of single numbers. 02:37: That's the Higgs field which gives elementary particles their mass. 02:50: I mentioned last time that quantum fields can hold energy without actually having particles. 02:58: You can think of a field with a high field strength as being full of virtual particles. 03:15: ... energy would be converted into another form, for example into real particles. ... 03:54: When that state decays, potential energy is released as real particles, ending inflation, and re-heating the universe in an expanding bubble. 11:46: Then an ocean of inflaton particles released by the decaying inflaton field turned into extremely energetic particles and radiation.
	2019-08-06: What Caused the Big Bang? 01:09: And these are strange particles predicted to have been produced in the early universe. 05:09: The field strength determines how much force a quantum field exerts on other fields and particles. 05:22: ... the way, an elementary particle is just an oscillation in this field strength - a little packet of ... 05:41: Particles get dispersed and so the energy density goes down. 05:45: ... quantum field can contain an intrinsic energy even without particles. In that case, it will always try to drop to the lowest energy state and ... 07:02: It would have a lot of energy but no particles. 10:04: The energy that existed in the inflaton field doesn't just go away, it remains in that field very briefly, but now in the form of inflaton particles. 10:14: ... what was once pure inflaton field is converted to a stack of inflaton particles. ... 10:26: ... particles are unstable and they very quickly disperse their energy into the other ... 10:39: So, the vacuum of inflation is converted into an extremely hot ocean of particles.
	2019-07-18: Did Time Start at the Big Bang? 11:12: ... Bang given infinite time or The same amount of time could lead to all particles randomly converging back to the same spot Or maybe black holes birth new ...
	2019-07-15: The Quantum Internet 06:00: A pair of entangled particles are created, and Bill and Ted receive one each via the quantum channel. 08:22: It can also be used to transmit quantum information over longer distances than we could normally send entangled particles. 09:07: ... means transferring a quantum state between a photon and a matter particle – say, an electron whose up or down spin direction can be entangled with ... 10:14: These are great because they’re much, much faster than repeaters that have to transfer quantum states between photons and matter particles.
	2019-07-01: Thorium and the Future of Nuclear Energy 00:33: ... atmosphere At the other end of the spectrum is the energy released when particles of matter and antimatter are brought together They annihilate each other ...
	2019-06-06: The Alchemy of Neutron Star Collisions 02:47: ... it drives material outwards we tend to think of neutrinos as ghostly particles that barely interact with matter but here both the neutrino and matter ...
	2019-05-09: Why Quantum Computing Requires Quantum Cryptography 04:38: ... know the values of certain pairs of properties – for example, a particle’s position and ... 11:04: ... the super-brief summary: create a pair of particles with a quantum property that is correlated between the two – for ... 11:25: ... comes in: choose an axis or basis on which to measure one of those particles – say up-down for spin or rectilinear for polarization - and the other ... 12:02: This time Albert creates a set of entangled particle pairs and transmits one half of those pairs to Niels. 12:09: He then chooses a set of bases to measure his own particles. 12:18: Niels chooses a random set of bases to measure the particles he receives. 12:40: But it was probably that Werner dude – he must have made some measurements and disentangled the particles en route. 15:04: ... assuming that dark matter is some sort of exotic particle - which is the going hypothesis - then black holes would definitely ... 15:27: Occasional dark matter particles would be snared by black holes - and they would add to its mass just like regular matter.
	2019-05-01: The Real Science of the EHT Black Hole 05:39: It’s also blasting out a jet of energetic particles, channeled by the intense magnetic fields around the black hole.
	2019-04-24: No Dark Matter = Proof of Dark Matter? 00:03: ... universe is invisible and formed by something not explained by modern particle physics or our understanding of gravity is completely broken the debate ...
	2019-04-10: The Holographic Universe Explained 03:27: ... only is any surface sufficient to fully describe the locations of all particles in its volume, but also the full machinery of the volume can exist on ... 05:03: For example, the resolution of our microscope or the power of our particle collider. 08:23: ... dimension you get the wave equation for a graviton – the quantum particle of ... 09:02: We now have a several versions string theory that try to explain how vibrating strings can lead to the familiar particles of this universe. 10:37: ... a quantum field theory like the ones that gives us our standard model of particle physics – a Yang-Mills theory, but with supersymmetry added ... 11:58: ... space – like in black holes – look like a solvable configuration of particles in the low-D ...
	2019-04-03: The Edge of an Infinite Universe 00:46: It’s boundary is called the particle horizon. 01:22: To review: the particle horizon defines the limit of the visible past, and there’s also cosmic event horizon defining the limit of the visible future. 08:44: He concluded that the black hole must generate particles – Hawking radiation. 14:49: Every particle, every gravitational effect in the bulk is represented by quantum fields on an infinitely distant surface.
	2019-03-28: Could the Universe End by Tearing Apart Every Atom? 08:00: The final result is that no particles will be close enough to interact with each other, ever. 10:03: ... a big rip universe will be nothing but hopelessly isolated elementary particles separated by infinitely expanding space. That's a hell of a ... 13:28: ... quark pairs?" For background, when you try to separate composite quark particles - hadrons, the energy put into breaking the bond just generates new ... 14:05: ... fun - that the exponentially increasing dark energy leads to exponential particle production, which ends up looking like a new Big ...
	2019-03-20: Is Dark Energy Getting Stronger? 02:40: ... of study and calculation suggest that dark matter is a particle of some unknown type, cold, diffuse, and immune to electromagnetic ...
	2019-03-13: Will You Travel to Space? 14:05: Now to remind you, the Brownian ratchet has this flywheel that turns a cog due to random motions of particles hitting the flywheel. 14:28: So, what if the cog is in a vacuum, so there are no particles to turn it backwards? 14:33: Well, the cog itself is made of particles that vibrate thermally. 14:38: ... light enough to rotate its flywheel due to being hit by individual particles will also have a lot of internal thermal vibration. Even in a vacuum, ... 16:00: ... and giving them your 2's aka entropy, and Yeah, this is where we leave particle gambling metaphors to the great ...
	2019-03-06: The Impossibility of Perpetual Motion Machines 04:00: Individual gas particles are moving around with random – or Brownian motion. 06:55: Due to the intrinsic quantum randomness of all particles, as expressed by the Heisenberg uncertainty principle, everything moves. 13:47: ... and also from individual electrons either bumping into other charged particles or circling in magnetic fields Fortunately we can model that stuff ...
	2019-02-07: Sound Waves from the Beginning of Time 01:57: These particles of matter are our baryons. 03:08: ... interaction between the charged particles of the plasma via the trapped photons meant that ripples in the plasma ...
	2019-01-30: Perpetual Motion From Negative Mass? 08:33: All of this assumes the simplistic case of what we call test particles – small objects moving in a much larger gravitational field. 10:58: ... GR analogs of Newton’s second law and give the equations of motion of particles. ...
	2019-01-24: The Crisis in Cosmology 11:34: One: A new type of very fast-moving particle. 11:44: That particle could be the sterile neutrino,... 11:53: Two: Dark matter particles behave differently to how we thought. 13:05: ...or of unknown particles beyond the standard model. 16:31: And a negative mass particle, moving backwards in time,... 16:34: ...is mathematically the same as a positive mass particle moving forward in time That notion makes sense in the math,...
	2019-01-16: Our Antimatter, Mirrored, Time-Reversed Universe 03:02: ... symmetry appears to hold not just in an imaginary clocks but also in the particles of the standard model the great parity violating process is the weak ... 08:43: ... is conserved in this type of time rehearsal. Mathematically, the particles in a rewinding universe actually look like they underwent a charge ... 10:54: ... evolution of a physical system - an explosion becomes an implosion and particle decay becomes particle creation. You're not rewinding time, you're not ... 13:52: ... be at that scale at all for the purpose of string theory supersymmetric particles could be far beyond the energies detected by the Large Hadron Collider - ... 17:15: ... has no obligation to make itself currently testable to any particular particle collider building technology level. It's under no obligation to make ...
	2019-01-09: Are Dark Matter And Dark Energy The Same? 00:32: And it’s pretty wild: negative mass particles continuously popping into existence between the galaxies. 01:39: We call it dark matter, and try as we might we can’t find the presumably-exotic particle that constitutes it. 06:15: The author uses these ideas about the interactions of negative and positive mass particles to create an N-body simulation. 06:22: ... virtual universe into his computer with both positive and negative mass particles, along with his interpretations of Newton’s ... 06:32: Those simulations showed that galaxies do indeed spin more quickly when surrounded by negative mass particles.
	2018-12-20: Why String Theory is Wrong 01:35: ... of its inclusion of quantum gravity, its promise to unify all particles under one umbrella, and there's also the convergence of many versions of ... 04:42: It also predicted an unknown field, the dilaton field, and a corresponding particle that had never been seen. 06:20: Five different approaches to getting all of the desired particles out of the basic premise of strings wiggling in ten dimensions. 08:55: ... or mode number divided by radius can be used to define the momentum of a particle produced by this ... 13:08: ... set of porperties for vibrating strings, and so a different family of particles and different laws of physics to go with ... 14:05: Physicists at the Large Hadron Collider had expected to find supersymmetric particles by now.
	2018-12-12: Quantum Physics in a Mirror Universe 00:02: ... so does spinning flying balls so do many molecules and some quantum particles but chirality in quantum mechanics means something quite specific ...
	2018-11-21: 'Oumuamua Is Not Aliens 13:46: Last week we talked about the possible detection of what may be the first supersymmetric particle. 16:34: Neutrinos are detected by the Cherenkov radiation produced by particles produced in neutrino collisions. 17:03: Many of you are impressed by Ice Cube's incredible contributions to particle physics and how the guy has had such a diverse career.
	2018-11-14: Supersymmetric Particle Found? 00:03: ... for clues to a deeper theory of physics, we're going to need a bigger particle ... 00:14: And the particles the galaxy flings at us may have finally revealed particles beyond the standard model. 00:34: Your theory predicts a new particle. 00:36: Build a particle accelerator big enough to see it. 00:49: The LHC has thoroughly tested the standard model of particle physics. 01:02: There must be a more fundamental theory that explains the origin of this rich family of particles. 01:59: ... between fermions and bosons is, in general, a step towards unifying the particles of the standard ... 02:15: Supersymmetry predicts that every single standard model of particle has a supersymmetric partner particle of the opposite type. 02:30: ... that's relevant for today's episode is that these supersymmetric particles are all expected to be way more massive than their known partners in the ... 02:41: To solve the hierarchy problem perfectly, those particles would need to have masses at around what we call the electroweak energy. 02:54: ... had hoped that, by smashing particles together hard enough in the Large Hadron Collider, there'd be enough ... 03:18: It may just be that these new particles are way more massive than expected. 03:27: To detect more massive supersymmetric particles, you need higher energy particle collisions. 03:48: The universe itself is a pretty good particle accelerator. 03:52: ... bursts, black hole magnetic fields are all expected to blast high energy particles like electrons and atomic nuclei into the ... 04:11: Unfortunately, for particle physics experiments cosmic rays at these energies are extremely rare. 04:17: So it's not surprising that we haven't seen supersymmetric particles in our cosmic ray observations yet, or have we? 05:14: Neutrinos are almost ghost like particles that travel through the CMB unimpeded. 05:36: We detect neutrinos because very, very rarely one will interact with an atomic nucleus and produce a shower of particles. 05:53: It spots neutrinos when they're decayed or electrons, muons, or tau particles, which in turn produce visible light as they streak through the ice. 07:29: ... energy radio bursts that could only have been produced by a high energy particle passing all the way through the middle of the ... 08:05: It produces a Cherenkov burst when it's created and then a second burst when it decays into a shower of secondary particles. 08:34: Physicists are having trouble accounting for these events with any known standard model particle, which brings us back to supersymmetry. 08:43: ... that there's a version of supersymmetry that predicts exactly the right particle to do this ... 08:52: It's the supersymmetric partner of the tau lepton, the stau particle. 08:58: You put an S in front to get the SUSY particle. 09:07: A stau particle was produced on the opposite side of the planet by an incoming ultra high energy neutrino plowing into the earth. 09:39: This particle is also not in the standard model but has nothing to do with supersymmetry. 09:44: Hints of its existence have been found in the Fermilab particle accelerator experiments. 11:38: Given the painful absence of new particles from the Large Hadron Collider, any hint of something new is bound to get physicists excited. 13:11: ... to operate in a way that is currently testable by any particular size particle accelerator, nor does it have any obligation to be simple enough to be ...
	2018-11-07: Why String Theory is Right 00:59: ... waves simply by changing the vibrational mode and you get different particles analogous to how different vibrational modes on guitar strings give ... 01:36: ... come together so neatly towards a unified description of all forces and particles, and most importantly that unification includes ... 03:24: Let's actually start with the regular old point particles of the standard model. 03:29: When a point particle is moving through space and time it traces a line. 03:40: In quantum theories of gravity, the gravitational force is communicated by the graviton particle. 03:47: When the graviton acts on another particle, it exerts its effect at an intersection in their world lines over some distance. 04:22: OK, let's switch to string theory where particles are not points. 06:31: It quantizes the equations of motion of slow-moving, point-like particles. 11:35: These are particles, and the first mode looks like the graviton, a quantum particle in the aforementioned gravitational field. 11:57: ... a caveat-- you can only get the right particles, including the graviton and the photon, out of string theory for a very ... 14:14: ... most misunderstood concepts in quantum mechanics, the idea of virtual particles and their tenuous connection to ... 14:44: ... fluctuations can be approximated as the sum of many virtual particles, but the particles themselves are just convenient mathematical building ... 14:56: Eddie Mitch asked whether the virtual particles are required to explain the Casimir force. 15:02: ... effect is sometimes explained as resulting from the exclusion of virtual particles between two very closely separated conducting plates which results in ... 15:14: ... but if it is, then it's still misleading to attribute it to virtual particles. ... 15:40: Those horizons perturb the vacuum which can lead to the creation of very real particles, as in Hawking radiation. 15:47: ... effect, the double horizon between the plates restricts what real particles can be produced there whereas there's less restriction on the outside of ...
	2018-10-31: Are Virtual Particles A New Layer of Reality? 00:02: Let me tell you a story about virtual particles. 00:08: Out there in the emptiest places of the universe, phantom particles appear and vanish again out of nowhere. 00:29: And every time two particles interact, an infinite number of virtual particles mediate infinite versions of that one interaction. 00:39: Virtual particles sound pretty cool, I guess, but is this really how they work? 00:45: Seriously, what are virtual particles? 01:26: A more recent mathematical hack is the virtual particle. 01:41: So will virtual particles also prove to represent a new underlying aspect of reality? 01:57: First, let's get to the origin of virtual particles. 02:01: So quantum field theory is the machinery behind the standard model of particle physics. 02:05: In it, particles are excitations in fundamental fields that exist everywhere in space. 02:12: In particle interactions, packets of energy are exchanged between these fields. 03:12: Those interactions are mediated by virtual particles. 03:16: In that sense, virtual particles are the building blocks of our approximation of the behavior of quantum fields. 03:54: Every one of these interactions is described with a simple excitation and transfer of particles-- virtual particles. 04:22: The virtual particles never exist independently. 04:25: Instead, virtual particles are the mathematical building blocks we use to approximate the complex states of interacting fields. 04:48: Particles that either enter or leave these diagrams are our real particles. 04:53: All those that both start and end within the diagram are virtual particles. 04:58: ... calculations, but they also add to the misconception about virtual particles. ... 05:09: They sure make it look like virtual particles are doing regular particle stuff like traveling through space but that's just not the case. 05:18: ... particles share some properties with their real counterparts-- in particular, ... 05:30: In fact, they ignore a lot of the physics of real particles. 05:45: Virtual particles are our mathematical representation of the quantum mechanical behavior of fields, and that behavior is weird. 06:12: How can throwing photons between particles cause them to be drawn together? 06:55: But how do they make the journey between the particles? 07:03: These virtual particles sort of exist everywhere at once, which is confusing. 07:09: ... one of these infinite possible virtual particles represents a quantum of energy in a single possible vibrational mode of ... 07:20: In a way, a virtual particle represents a pure excitation of the field, an idealized case of perfectly defined momentum. 07:29: The Heisenberg uncertainty principle tells us that the perfectly defined momenta of virtual particles means completely undefined position. 07:39: In contrast, real particles are mixed up combinations of many excitations, many different momentum modes. 08:03: ... out moving in the wrong direction and then quantum tunnels between the particles, kicking them towards each other like a teleporting ... 08:42: So that's the deal with virtual particles in particle interactions, but we also hear about the role of virtual particles in a complete vacuum. 08:52: ... have heard the quantum vacuum described as his roiling ocean of virtual particle-antiparticle pairs popping into and out of existence, the so-called vacuum ... 09:06: So the quantum fields are composed of these vibrational modes of all different frequencies/momenta that can be excited to become particles. 09:48: So there's a chance that when measured the vacuum will appear to have energy and so have particles. 09:54: But the key word here is "measured." Do those particles exist if you're not looking? 10:00: Or more to the point, do vacuum fluctuations produce actual particles when there's nothing else around? 10:21: Regarding its particle content, it remains in a steady state of uncertainty. 10:27: ... a quantum state in a superposition of "yep particles" and "nope, no particles." The quantum state is not fluctuating on its ... 10:48: Virtual particles are not popping into and out of existence in the absence of any else. 11:03: Stephen Hawking himself was the first to use virtual particles as an intuitive way to describe his radiation. 11:37: This disturbance of the vacuum generates particles. 11:50: ... these, and just like with Hawking radiation, you don't need for virtual particles to have an independent existence to explain these ... 12:00: So to recap, virtual particles are best thought of as a mathematical device to represent the behavior of quantum fields. 12:08: ... original idea of virtual particles came about as a calculation tool in perturbation theory as we tried to ... 12:42: So what about virtual particles? 12:53: It turns out there is a version of quantum field theory that doesn't use virtual particles at all. 13:05: It doesn't rely on perturbation theory, and so it doesn't use virtual particles while ultimately giving the same results. 13:13: Ergo, virtual particles are probably just a mathematical artifact. 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.
	2018-10-25: Will We Ever Find Alien Life? 13:01: ... example, you can check out Particle Fever, which follows the first round of experiments at the Large Hadron ... 13:24: Sam Pollard asks, how does adding more particles require fewer dimensions?
	2018-10-18: What are the Strings in String Theory? 00:10: There are these tiny vibrating strings, and that's where all the force's particles, including gravity, in the entire universe come from. 00:47: This is why the standard model of particle physics is considered incomplete. 00:59: We need to use physical measurement to fix 19 free parameters like the masses of particles. 03:01: It's a particle. 03:03: And one of those modes appeared to be a massless spin-2 particle. 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 ... 03:51: In fact, what if all force-carrying particles result from oscillations in tiny strings? 07:02: The hope is that tweaked just right, those discrete vibrational modes can be made to match the properties of known particles. 07:10: Particle mass just comes from the length of the string and its tension. 07:24: And those modes, in turn, define particle properties like electric charge and spin. 07:32: ... tension, or equivalently, string length scale, all of the possible particles should be automatically ... 07:56: They have vibrational modes that define particle properties. 08:51: These last properties are important because it gives a mechanism for the particles of string theory to interact and to decay into other particles. 09:31: String theory fixes this because the graviton is a loop, not a point particle. 10:01: ... themselves are 1-D, but to even start to produce the properties of known particles, they need to vibrate in more than just the three dimensions of ... 10:23: In short, without exactly this number of dimensions, you don't get gravitons or any other massless particle. 15:57: Like I said, our black hole computer is only simulating particles, not black holes.
	2018-10-10: Computing a Universe Simulation 01:04: ... neighbors by a simple set of rules, leading to oscillations, elementary particles, atoms, and ultimately to all of the emergent laws of physics, physical ... 03:48: ... like 10 to the power of 90 bits, roughly corresponding to the number of particles of matter and ... 04:21: How large would that black hole need to be to store all of the information about all of the particles in the universe? 04:38: If we instead count all the elementary particles with mass, we might get 10 to the 81 particles. 04:43: But let's just go with a nice, round order of magnitude-- 10 to the 80 bits assuming 1 bit per particle. 05:13: ... you could store the entire observable universe of non-radiation particles on the surface area of a black hole the size of ... 08:14: ... get that, if every single particle in the universe were used to make a computation, it should process 5 by ... 08:45: And that's actually independent of the number of particles or degrees of freedom the universe is using to do that computation. 08:52: The number is based on its energy content, and it has to spread that computational power over its particles.
	2018-10-03: How to Detect Extra Dimensions 06:07: ... number of dimensions on which the quantum field and their corresponding particles can ...
	2018-09-20: Quantum Gravity and the Hardest Problem in Physics 02:25: It describes particles as waves of infinite possibility whose observed properties are intrinsically uncertain. 05:21: In order to measure a location in space-- say, the location of a particle-- you need to interact with it. 05:28: You would typically do that by bouncing a photon or other particle off the object. 05:44: So let's say we shoot a particle with a beam from a particle accelerator to measure its location with extreme precision. 07:01: ... know that for a particle to have a highly defined location, its position wave function needs to ... 07:33: Particles whose positions are defined within a Planck length can spontaneously become black holes. 11:09: The non-renormalizability of quantized general relativity is connected to the idea that precisely localized particles produce black holes. 15:01: VoodooD0g points out that the vacuum isn't really empty, what, with all the virtual particles popping into and out of existence. 15:09: Well, actually, those don't really contain information because they aren't real in the sense that we think of normal particles. 15:16: The phantom virtual particles represent both the absence of particles and every possibility of particles.
	2018-09-12: How Much Information is in the Universe? 00:19: Hundreds of billions of galaxies, each with hundreds of billions of stars, each with rather a lot of particles in them. 00:25: ... stuff that isn't stars-- the dark matter, black holes, planets, and the particles, and radiation in between the stars and galaxies, not to mention space ... 04:18: Particles have more information than just their position. 05:59: In other words, one bit per elementary particle. 06:11: Most other particles are much rarer, so we're still in the realm of 10 to 80 to 10 to the 81. 06:34: So almost all of the information, and for that matter, the entropy in particles is in neutrinos and in the cosmic microwave background photons. 06:42: The situation with dark matter is unclear, so let's just round up to 10 to the power of 90 bits of information in particles in our universe. 08:43: The universe can keep having particles, and you can leave your horribly bloated email inbox alone. 08:52: Say, in the form of too many particles. 10:07: Assume one bit per elementary particle.
	2018-09-05: The Black Hole Entropy Enigma 02:47: He described a mechanism by which the information contained by infalling particles could be preserved on the event horizon of the black hole. 03:46: ... need to perfectly describe the system's internal state like all the particle positions, velocities, et ... 03:55: The higher the entropy, the more randomly distributed its particles and the more possible configurations lead to the same macroscopic state. 04:03: ... the entropy, the less you can guess about the properties of individual particles based on the global properties like temperature, volume, pressure, et ... 04:12: ... must always increase, which means energy tends to spread out evenly and particles tend to randomize, reducing our information about their microscopic ... 04:36: Now that's a high entropy based, super hot and full of randomly moving particles. 04:41: We have almost no information about the individual particles, but that information still exists in the universe. 04:47: Like, I guess, the particles know where they are. 08:05: Essentially he built a black hole out of idealized elementary particles that each contained a single bit of information. 09:04: He showed that black holes radiate random particles exactly as though they have a peak glow for a particular temperature that depends on their mass.
	2018-08-23: How Will the Universe End? 06:09: But in short, protons have the most stable composite particles. 06:13: According to the standard model of particle physics, they should last forever. 07:44: They slowly leak away their mass as a cool heat [INAUDIBLE] of random particles for the most part faint radio light. 08:38: ... though we don't know exactly what it is, dark matter particles will likely either annihilate themselves as they collide with each other ... 09:03: And after that, just particles and light, now not even bound gravitationally. 11:36: ... universe will be nothing but an increasingly diffuse void of elementary particles with maybe a bit of dust if you're ... 15:25: ... far as quantum mechanics is concerned, size is a property of composite particles, things that are made up of multiple elementary ... 15:35: It's the size of that bundle of elementary particles. 15:39: But elementary particles themselves don't have size in this sense. 15:43: All they have is their quantum wave function, which tells the probability of the particle's location, momentum, spin, direction, et cetera. 16:20: ... randomly to the observations when we come up with stuff like virtual particles and that it's so weird that that actually ...
	2018-08-15: Quantum Theory's Most Incredible Prediction 00:50: Quantum field theory describes a universe filled with different quantum fields in which particles are excitations, quantized vibrations. 01:13: ... calculations of QED describe how this field interacts with charged particles to give us the electromagnetic force, which binds electrons to atoms, ... 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. 08:54: ... particles in and out, so it leads to the same overall result. But now the electron ... 09:50: ... electron can interact with the EM field, with crazy networks of virtual particles and virtual matter, anti-matter loops between the real ingoing and ... 10:45: One way to do it is to watch the way electrons process in the constant magnetic field of a cyclotron, a type of particle accelerator. 11:32: This is the fundamental constant governing the strength of the electromagnetic interaction of charged particles.
	2018-08-01: How Close To The Sun Can Humanity Get? 01:22: Magnetic storms driving a constant stream of energy and potentially, destructive particles. 02:19: Charged particles traveling at nearly 1% the speed of light bombarded the earth. 04:08: Finally, it will detect radio waves from processes responsible for the acceleration of particles in the solar wind. 04:18: The solar wind electrons, alphas, and protons instrument-- or SWEAP-- will directly detect the particles that make up most of the solar wind. 04:27: The most common types are electrons, helium ions, AKA alpha particles, and protons. 04:51: ... will capture the most energetic particles of the solar wind-- charged particles like electrons, protons, and ... 09:51: ... we talked about Maxwell's demon-- the thought experiment in which the particles in two halves of a box are sorted without using ... 10:42: ... represents some physical system that can detect incoming particles, measure their velocity, and then open the door based on a decision about ... 11:40: Surely, when you open and close the gate to admit the particle, you use energy. 12:48: That energy can come from the incoming particle. 12:50: And it can be returned to that particle reversibly by either the latch or the gate, depending on how you set it up. 12:57: So an incoming particle is detected and the latch releases, the gate opens, closes, and the particle passes through without losing any energy.
	2018-07-25: Reversing Entropy with Maxwell's Demon 01:31: ... defined by the number of possible configurations of particles-- or microstates in physics-speak-- that could produce the same observed ... 03:06: ... those stones all being on one side could represent particles that all have high or all have low energies, or particles that are all ... 03:20: The particles would quickly flow to fill the available space, and you could extract energy from that flow. 03:43: The particles are pretty well mixed. 05:41: The demon has the ability to observe speed and trajectories of individual particles in the system. 05:50: ... time the demon sees a high speed particle approaching from the right, it opens the door to let it pass to the left ... 06:00: Soon enough, the left side is full of fast particles and is hot, while the right contains slow particles and is cold. 06:46: ... non-demonic-- or even intelligent-- mechanisms to detect approaching particles and open the door, mechanisms which, in principle, don't increase ... 06:58: But it turns out, there's one last step in the process of sorting particles where the increase of entropy is unavoidable. 07:08: Weirdly, it's not in the measurement of particle trajectories or the motion of the door. 07:18: See, in order for the demon to do its job, it must learn about the particles. 07:22: ... demon, or the particle sorting system it represents, must start in some known predictable ... 07:34: From our point of view, the randomness of the particles decreases, but that randomness is transferred to the memory of the demon. 07:45: At some point, the system for sorting particles needs to be reset to continue its work. 08:56: ... you have perfect knowledge of the state of all particles in the box, you could open and close the door in exactly the right ...
	2018-07-18: The Misunderstood Nature of Entropy 03:57: This theory explained thermodynamic behavior as the summed result of the individual motion of tiny particles under Newton's laws of motion. 04:11: For a given set of large-scale observable properties, every possible configuration of particles that could give those properties is equally likely. 04:22: By configuration, I mean the exact arrangement, of positions, velocities, et cetera of all microscopic particles. 04:37: Macrostates are entirely defined by thermodynamic properties, temperature, pressure, volume, and number of particles. 04:52: ... macrostates, there are lots of different microstates or arrangements of particles that lead to roughly the same thermodynamic properties, while other ... 05:15: All particle arrangements will eventually happen. 06:32: ... been talking a lot about particle position, but really, that Go board is an analogy for all possible ... 06:49: And instead of particles being distributed through position space, a microstate is really defined by how energy is distributed through phase space. 06:58: The average distribution of individual particles in phase space defines the thermodynamic properties of the system. 07:13: So if you leave a system alone long enough, its particles and its energy will find its way into all the different forms that are possible. 08:04: ... the way, there are certain special microstates, special arrangements of particles that look highly ordered but are still consistent with their ... 08:27: ... thermodynamic entropy, the only special arrangements of particles that change entropy are the ones that change the thermodynamic ... 10:04: But entropy is also statistical and emerges from behavior of particles under the laws of motion.
	2018-07-11: Quantum Invariance & The Origin of The Standard Model 00:03: ... standard model of particle physics is the most successful, most accurate physical theory ever ... 00:55: The most amazing example of this is the standard model of particle physics. 02:44: We can never see the underlying wave function of, say, a particle. 03:11: The square of the magnitude of this wave function tells us the probability distribution of a particle's position. 03:18: The position that we observe when we look at the particle is picked randomly from that distribution. 04:26: It determines the particle's position. 04:31: ... by any amount and you wouldn't change the resulting position of the particle, as long as you do the same shift to both the real and imaginary ... 05:56: That shouldn't change our probabilities for the positions of the particles, but what about observables besides positions? 06:08: Among other things, messing with local phase really screws up our prediction for the particle's momentum. 06:45: To do that, we need to alter the part of the Schrodinger equation that gives us the momentum of a particle, the momentum operator. 07:34: ... we've discovered that the only way for particles to have local phase invariance is for us to introduce a new fundamental ... 08:12: And now we know how it interacts with particles of matter to give them this symmetry. 08:24: Any particle that has this kind of charge will interact with and be affected by the electromagnetic field and be granted local phase invariance. 08:35: In order to have this particular type of local phase invariance, particles must possess electric charge. 09:28: But what about all those fundamental particles without electric charge? 09:32: Neutral particles like neutrinos. 10:02: ... and they all have their associated oscillations, their associated particles. ... 10:49: And following those mathematical labyrinths reveals physical theory with stunning predictive power, like the standard model of particle physics. 11:10: Last time on Space Time Journal Club, we looked at a new result potentially detecting a particle beyond the standard model, the sterile neutrino. 11:28: And no one, not even the researchers, are claiming the actual discovery of this new particle, yet.
	2018-07-04: Will A New Neutrino Change The Standard Model? 00:07: Since the discovery of the Higgs boson, physicists have searched and searched for any hint of new particles. 00:18: ... Club, we'll look at a paper that reports a compelling hint of a new particle outside the standard model, the sterile ... 02:10: ... going to drop through the standard model of particle physics, electric charge and antimatter, the bizarreness of quantum ... 02:25: ... the standard model of particle physics-- as we'll see in upcoming episodes, these particles are divided ... 03:16: An antimatter version of a particle has the same mass and the opposite electric charge. 03:46: Helicity is just the direction of a particle's spin relative to its direction of motion. 04:04: It's related to the direction in which the particle's phase shifts under rotations. 04:10: Helicity depends on your own motion relative to the particle in question. 04:14: It flips direction if you start moving faster than the particle. 04:17: However, chirality is fundamental to the particle and doesn't depend on your own velocity. 04:23: ... is where we need to expand our picture of the particles of the standard model a little and open up the possibility of the ... 04:42: ... quarks and electrons are actually a combination of left and right chiral particles that oscillate back and forth between those particles through ... 04:55: That oscillation is what gives these particles their mass. 05:05: ... charged electrons have their own positively charged antimatter particles, which are right and left chiral, ... 05:16: These different chiralities are thought of as completely separate particles, and there's a good reason for this. 05:21: Chirality determines whether a particle can interact with the weak nuclear force. 09:05: If this is right, then it's the first particle outside the standard model since the Higgs boson. 09:21: Forgive the particle-physics energy units for mass.
	2018-06-20: The Black Hole Information Paradox 02:13: If we see a black hole, how can we possibly figure out what particles went in to form it? 03:02: That distortion looks like particles flowing away from the black hole. 03:06: And the energy to create those particles must come from the mass of the black hole itself. 03:11: What type of particles? 03:13: According to Hawking's calculation, those particles should come out with energies that follow the black-body spectrum. 03:44: The black hole radiates particles, mostly photons, that contain no information. 03:49: Eventually the black hole must completely evaporate into those particles, leaving no clue as to what fell into it in the first place. 10:51: ... suggests that each particle of Hawking radiation should be simultaneously entangled with the ... 14:11: Virtual particles in general are just a way to mathematically account for the infinite ways a quantum field can communicate its influence. 14:19: Virtual particles don't have the same restrictions as regular particles. 14:35: ... this picture, virtual particles can escape a black hole to communicate the influence of the charge ...
	2018-06-13: What Survives Inside A Black Hole? 08:15: ... black hole with nonzero charge will quickly attract particles with the opposite charge until positive and negative charges within the ... 10:06: An example would be the number of particles of different types, like the balance between quarks and antiquarks represented by baryon number. 10:24: So what if the universe forgets what type of particles a black hole is made of? 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. 12:10: We said that there's always a 100% chance, for example, that the particle position always has some value. 12:16: So what if the particle is destroyed? 12:18: ... particle creation and annihilation is described by quantum-field theory, and ... 12:28: QFT describes the evolution of quantum fields in which particles are excited states. 12:34: Now it's the evolution of the fields, not the particles, that conserves probability.
	2018-05-23: Why Quantum Information is Never Destroyed 00:07: If you have perfect knowledge of every single particle in the universe, can you use the laws of physics to rewind all the way back to the Big Bang? 02:38: ... would be time-reversal symmetric if knowing the exact state of every particle in the universe at one point in time allowed us to calculate its exact ... 03:30: For example, what if many different configurations of particles in the present could converge on a single configuration of particles in the future? 05:10: ... example, the wave function of a particle encapsulates the probability that it will be found in this or that ... 06:27: In the case of particle position, probability of adding to 1 just means that the particle is definitely somewhere. 06:34: And as time goes on, a particle's properties will continue to have possible values. 09:35: And in the case of pilot wave theory, the wave function contains hidden information that is carried with the final measured particle. 10:55: I'm talking black hole thermodynamics and some pretty deep particle physics.
	2018-05-16: Noether's Theorem and The Symmetries of Reality 07:45: ... by any amount, and the observable properties of that field, like its particles, don't ... 08:08: They predict a rich family of conserved charges that govern the interactions of the particles of the standard model. 08:22: The entire standard model of particle physics is what we call a gauge theory. 08:30: ... what these symmetries really are and how they lead to the family of particles and interactions that make up our ...
	2018-04-11: The Physics of Life (ft. It's Okay to be Smart & PBS Eons!) 01:07: The particles that make up any system all have some degree of random motion. 01:13: That random motion tends to drive the system towards the most common arrangement of particles. 01:40: So entropy is sort of a measure of the boringness of a system, the commonness of the arrangement of particles. 09:15: ... than the turbulent flow because there are fewer ways to rearrange the particles in the former while preserving its global ... 10:57: Last week, we talked about the mysterious Unruh effect, in which accelerating observers find themselves bathed in a sea of particles. 11:07: ... out that from the point of view of an inertial observer, an accelerating particle detector emits particles instead of absorbing ... 11:23: ... in short, the inertial observer sees the accelerating particle detector click as though it registered a particle, but the excitation ... 12:05: The answer is that the accelerating observer perceives themselves to be plowing through a bath of Unruh particles, and these produce the drag. 12:18: Ultimately, that's the source of energy for whatever effects those Unruh particles cause, whether or not you actually see the Unruh particles.
	2018-04-04: The Unruh Effect 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. 01:14: It tells us that accelerating observers find themselves in a warm bath of particles. 01:53: A particle not moving at all has a vertical world line. 06:20: ... in the accelerating frame of reference, which leads to the creation of particles in that accelerating ... 06:31: Those particles should have the same type of spectrum as Hawking radiation, a thermal spectrum. 07:33: Where does that energy appear to come from if not from particles? 07:37: A little less gruesomely, imagine the Rindler observer has a particle detector. 07:41: Every time an Unruh particle hits the detector, it would click. 07:45: And the inertial observer would agree that it clicked, but they wouldn't see the particle that triggered it. 07:59: This is a fancy name for a particle in a box. 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. 08:15: So as the detector accelerates, Unruh particles appear. 08:19: The detector particle gets excited by an Unruh particle, causing the detector to click. 08:36: ... field theory calculation to understand the coupling between the detector particle and the field, they get that there's a sort of drag or friction turn ... 08:51: That causes energy to be dumped into the detector particle. 08:58: The upshot is that the very existence of particles is observer-dependent. 09:06: A charged particle accelerating in a magnetic field emits radiation, bremsstrahlung radiation. 09:13: An inertial observer sees the charged particle itself radiating, its energy extracted from the magnetic field. 09:19: But an observer accelerating with that charged particle sees it absorbing Unruh particles and then spitting them out again. 09:46: ... difficult to directly observe Unruh particles, although analogies have been observed even in classical systems, like ... 10:29: ... the relationship between the Unruh particle seen by someone hovering at the event horizon and the particles of ...
	2018-03-28: The Andromeda-Milky Way Collision 05:06: They used simulations of the gravitational interactions of millions of particles representing groups of stars and dark matter. 07:22: ... Marel, et al's, simulation follows several candidate suns, simulation particles with similar orbits and masses to our sun, and they track their final ... 10:17: That's very fair, Patrick, but I would say that the evidence is converging on dark matter being some sort of particle or at least a stuff.
	2018-03-15: Hawking Radiation 01:54: ... pairs of virtual particles, matter and antimatter, spontaneously appear and then annihilate each ... 03:01: A particle is like a note on the string. 03:04: And just like a real guitar note, real particles tend to be comprised of many vibrational modes. 03:09: Those underlying vibrational modes are still present in the absence of real particles. 03:17: And those fluctuations give us what we think of as virtual particles. 03:21: Now don't take the existence of virtual particles too seriously. 03:51: ... can crudely think of as a balance between virtual matter and antimatter particles. ... 04:03: These all virtually annihilate or cancel out so that no real particles exist. 05:37: By the time this trajectory has found its way back out into flat space again, those fluctuations look like real particles. 05:54: ... the black hole, regions where the nature of vacuums, quantum fields, and particles are perfectly well ... 07:10: That distorted vacuum looks like it's full of particles. 07:29: It produces particles that also have wavelengths about as large as the event horizon. 08:07: OK, so what about the whole picture of particle/antiparticle pairs being pulled apart by the event horizon? 08:19: It's fair to interpret this mixing as the promotion of what were once virtual particles into reality. 08:57: Well, these are the de Broglie wavelengths of created particles. 09:00: And they tell us that there is an enormous quantum uncertainty in the location of these particles. 09:28: When you turn on your jet pack and hover a fixed distance above the horizon, then you do see particles. 09:39: By the way, Hawking radiation is mostly going to be photons and other massless particles. 09:44: To produce particles with mass, the energy of the radiation has to be high enough to cover the rest mass of the particle. 10:17: ... got the same thermal spectrum for Hawking radiation by thinking about particles escaping from beneath the event horizon through quantum ... 10:32: ... example, uncertainty in position or momentum can lead to particle pairs that we'll want in the same location or modes that we'll want on ... 10:43: Alternatively, uncertainty in energy can lead to particle creation. 10:48: Whichever way you interpret it, it's hard to avoid the conclusion that black holes emit particles. 11:23: For example, what happens to the particles or modes trapped by the black hole?
	2018-02-28: The Trebuchet Challenge 02:14: ... motion and potential for motion, remains constant, and not just for one particle, but for any system of any number of interacting ... 02:27: After all, the interactions between particles are ultimately due to fundamental forces, which are always conservative.
	2018-02-21: The Death of the Sun 09:44: ... asked whether the combination of two particles has a different mass when those particles are close together versus when ... 10:59: It represents the energy exchange that would result from a particle or system moving between two points under the action of a conservative force.
	2018-02-14: What is Energy? 01:15: He realized that the sum of mass times velocity squared for a system of particles bouncing around on a flat surface is conserved. 01:22: It adds up to the same number, even though the speeds of individual particles changes, at least assuming there's no friction and perfect bounciness. 05:45: But ultimately, all fundamental forces are conservative, as long as you consider all of the particles involved. 05:52: For example, the molecules causing air resistance are just tiny particles. 05:57: They exchange kinetic energy with perfect efficiency with the particles comprising the ball. 06:02: If we account for every particle and field involved, then the transaction between kinetic and potential energy is a zero sum game. 06:20: In the case of air resistance, the kinetic energy transfer to the air particles ends up as heat. 06:35: ... to account for the potential energy in the forces that bind subatomic particles together, the energy of mass, which we talk about in earlier ... 07:14: But try to describe the behavior of the countless particles in, say, a stream of water or a universe, and it's pretty hopeless. 07:22: Such systems contain an impossibly large number of particles. 07:26: But there are also an impossibly large number of ways those particles can move from one spot to another. 07:32: Energy doesn't care what the individual particles are doing. 07:53: It ignores the individual particles in the fluid. 08:25: ... equation describes the motion of individual particles but can also describe the evolution of extremely complex systems, for ... 08:50: ... system and allows us to describe anything from the motion of a single particle in Schrodinger's equation to complex interactions of particles and ... 09:26: And the Lagrangian quantum field theory is the basis for high-energy particle physics.
	2018-01-24: The End of the Habitable Zone 11:00: Existenceisillusion asked about the nature of the thermal particles produced in horizon radiation. 11:20: ... means the thermal bath of particles should include all particles and their energy distribution should be the ... 11:31: Actually, now that I think about it, that might mean that you would only see particles whose rest masses are less than the allowed energy. 12:13: In fact, as far as I know, there is no derivation of Hawking radiation that invokes the splitting of particle-antiparticle pairs.
	2018-01-17: Horizon Radiation 00:12: This theory tells us that particles can be created and destroyed during interactions. 00:17: Even so, every observer agrees on whether a particle exists or not, right? 01:45: As it turns out, what gives is the nature of the vacuum, and in fact, the notion of what a particle is becomes observer dependent. 02:22: ... get at this idea of observer dependent particles and vacua, we're going to need some quantum field theory, and we're ... 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. 02:45: That oscillation can be distributed over some region of space, representing the possible positions of the particle. 02:51: The properties of the particles are encoded in the properties of the fields. 02:56: The laws of physics, as we know them, are the rules defining how particles interact. 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. 04:08: To see how this happens, we need to think about how particles, interactions, and vacuums are described in quantum field theory. 04:35: A particle perfectly localized in space-- a single spring or a single point on the drum skin. 04:47: And we interpret each quantum of energy as representing a single particle. 05:03: This coupling allows the oscillation-- the particle to evolve through space. 05:56: So let's take our spatial quantum field-- our drum skin, with its single, localized particle, and transform to momentum space. 06:04: That momentum field also has infinite oscillators, but now each one represents a different possible momentum for the particle. 06:31: ... cancel out everywhere except at the spatial location of the original particle. ... 06:40: The superposition of infinite universe size momentum oscillators-- momentum particles can represent a single spatial oscillator. 06:51: One particle at one point in the universe. 07:06: If we were to make an excitation at a particular spot-- make a particle, we hit that spot with a drumstick and set the oscillation going. 08:12: However, changing the momentum modes does affect the superposition-- the sum of all oscillations, for example, by creating or destroying particles. 08:22: OK, so a single particle can be described as many oscillations in momentum space. 08:28: ... oscillations can be reconfigured with our infinite drumstick to add new particles or remove old ones, for example, to describe a particle interaction like ... 08:51: ... and an annihilation operator that can raise or lower the number of particles, one at a time, by changing the number of particles or oscillations in ... 09:22: As discussed in a previous episode, we can think of the vacuum as a sea of virtual particles. 09:35: Infinite spatially undefined particles with defined momenta, and these just happen to cancel each other out, leaving 0 particles or a vacuum. 10:06: ... we want to make the same particle as before, we need to strike the remaining part of the skin in a very ... 10:26: ... our infinite drumstick, in order to create and annihilate the same particles as we had in an infinite, horizonless ... 11:01: What was once a vacuum now has particles. 11:23: It appears to be bathed in thermal particles-- particles that don't exist for an observer who doesn't see that horizon. 11:31: In some cases, changing the boundaries of space time actually reduces the number of particles, for example, in the Casimir effect. 12:07: It's hard to be sure of anything in this relative universe, whether it's the existence of a particle or funds for a YouTube show.
	2018-01-10: What Do Stars Sound Like? 12:39: In fact, the magnetic field of a gamma ray burst focuses charged particles-- electrons and the nuclei of the exploding star. 12:48: Those particles can then fire photons in our direction in a couple of different possible ways. 12:56: The charged particles spiral around the axial magnetic fields and emit photons as they do. 13:05: ... Particles in the jet bump into existing photons, perhaps synchrotron photons, and ... 13:17: ... the light emitted in the same direction as the near light speed charged particles of the ...
	2017-12-20: Extinction by Gamma-Ray Burst 02:46: ... light, so ultraviolet, x-rays, gamma rays, and near-light-speed particles-- so cosmic rays-- into the surrounding interstellar ...
	2017-12-13: The Origin of 'Oumuamua, Our First Interstellar Visitor 09:50: [INAUDIBLE] Leonard asks whether a particle can have momentum higher than its mass times the speed of light.
	2017-12-06: Understanding the Uncertainty Principle with Quantum Fourier Series 00:58: ... universe we experience seems to be constructed of singular particles with well-defined properties, but this intuitive, mechanical reality is ... 01:19: The vacuum itself can be thought of as constructed from the sum of infinite possible particles. 01:51: Try to perfectly nail down a particle's position, and we have complete uncertainty about its momentum. 01:59: And it's not just because our measurement of position requires us to interact with the particle, therefore changing its momentum, no. 06:58: ... De Broglie extended this idea to particles, and his De Broglie relation generalizes the relationship between ... 07:21: So any particle, any wave function, can be represented as a combination of many locations in space, with accompanying intensities. 07:29: ... of it as the particle being smeared over possible positions or as a combination of many ... 07:50: But what does it even mean for a particle to be comprised of waves of many different positions or momenta? 08:06: The magnitude of the wave function squared is the probability distribution for the particle. 08:12: ... then applying the Born rule tells us how likely we are to find the particle at any given point when we make a ... 08:22: Or put another way, the range of positions in which the particle is likely to be located were we to look. 08:30: If we apply the Born rule to the momentum function, then we learn the range of momenta the particle is likely to have. 08:38: So if we measure a particle's position, then from our point of view, it's wave function is highly localized in space. 08:45: We know where the particle is. 08:48: ... resulting particle wave packet, now constrained in position, can only be described as a ... 09:22: ... we increase our certainty of the position of a particle by narrowing the slit, we also increase the uncertainty of its momentum ... 09:50: It's an unavoidable outcome of describing particles as the superposition of waves. 10:26: ... a single particle, a quantum field vibration, perfectly localized at one spot in space, can ... 10:39: But each of these oscillations in momentum space are equivalent to particles with highly specific momenta. 10:51: So a perfectly specially localized particle is equally an infinite number of momentum particles that themselves occupy all locations in the universe. 11:01: ... strange momentum space, by adding and removing these spatially infinite particles, that we can describe how the quantum vacuum changes to give us phenomena ...
	2017-11-29: Citizen Science + Zero-Point Challenge Answer 08:42: ... wavelengths shorter than 0.1 millimeters definitely exist, and we see particle interactions that require the exchange of much shorter wavelength ...
	2017-11-22: Suicide Space Robots 12:46: Hawking radiation is related to this whole vacuum energy virtual particle thing.
	2017-11-08: Zero-Point Energy Demystified 02:18: Entropy can be thought of as a measure of the specialness of the arrangement of a system of particles. 02:59: It's a special unusual configuration of particles. 04:22: If you bring a pair of conducting plates very close together, a proportion of the virtual particles will be excluded from between them. 06:02: The fact is, any acceleration of a real particle involves a transfer of momentum between real particles via virtual particles. 06:10: Virtual particles, and hence, the quantum vacuum, mediate all forces. 06:15: However, it's not possible to transfer momentum from a particle to the vacuum without getting another real particle out the other end. 06:23: That momentum must be given up by the vacuum to produce real particles again. 06:28: Those particles would become the propellant carrying momentum away. 06:41: ... particles are somehow extracting momentum from the resonant cavity, then they're ...
	2017-11-02: The Vacuum Catastrophe 00:35: Virtual particles appear and vanish from nowhere in seeming violation of our intuitions about the conservation of mass and energy. 00:51: ... zero point energy in the quantum fields that can briefly manifest as particles. ... 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. 01:40: Higher energy oscillations represent the presence of real particles. 01:45: However, even the lowest possible energy oscillation, the one corresponding to the absence of particles, the so-called vacuum state, has some energy. 04:12: In fact, in both quantum mechanics and classical mechanics, a particle's equations of motion depend only on changes in energy. 06:19: An extension to the standard model of particle physics called supersymmetry may partially allow this. 06:25: It gives particles a supersymmetric counterpart that may precisely cancel out their vacuum energy. 10:23: This means it doesn't take much energy to accelerate the particles to very high speeds. 10:28: Temperature is just a measure of the average kinetic energy per particle, so a little bit of energy leads to very high temperatures. 10:43: And how do the particles stay hot? 10:47: As particles essentially never encounter each other, then they aren't bumping around, and that makes it hard to radiate away their heat.
	2017-10-25: The Missing Mass Mystery 02:30: By the way, a baryon is a 3-quark particle like a proton or a neutron. 11:02: Last week, we talked about virtual particles, zero point energies and the nature of nothing. 11:59: ... Zambelli asked whether the annihilation of virtual matter anti-matter particles would introduce energy into the universe and therefore violate the law ... 12:16: On particle annihilation, it's given back without producing a real photon. 12:21: ... also asks, if virtual particles control faster than the speed of light, can't they escape the event ...
	2017-10-19: The Nature of Nothing 00:30: There's also the ambient electromagnetic buzz from the surrounding city and a stream of exotic particles from the surrounding cosmos. 01:03: Zero kelvin means no motion whatsoever in a substances constituent particles. 01:09: ... that perfect stillness implies that a particle's position and momentum are simultaneously perfectly defined, and this is ... 01:21: Fix a particle's position, and its momentum, and so its motion, becomes a quantum blur of many possible momenta. 01:42: But hypothetically, what would perfectly empty space look like, far from the nearest particle of matter or radiation? 02:08: In short, space itself is comprised of fundamental quantum fields, one for each elementary particle. 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: ... to these quantum oscillators having no energy, which means there are no particles in a given quantum ... 04:13: But sometimes the field finds itself with enough energy to create a particle, seemingly out of nothing. 04:20: ... call these virtual particles, and they seem to be the machinery under the hood of all particle ... 04:33: For example, QFT describes the electromagnetic force as the exchange of virtual photons between charged particles. 04:41: Virtual particles are the links governing all particle interactions in the famous Feynman diagrams. 04:48: But to properly calculate an interaction of real particles, every imaginable behavior of the connecting virtual particles must be accounted for. 05:01: For example, in QFT, virtual particles can have any mass and any speed, including speeds faster than light, and can even travel backwards in time. 05:16: The ambiguous realness of virtual particles seems to grant them some surreal freedoms, but there are restrictions. 05:24: For example, quantum conservation laws must be obeyed, so most virtual particles are created in particle-antiparticle pairs. 05:33: But the ultimate price is that virtual particles can exist only for the instant allowed by the Heisenberg uncertainty principle. 05:41: And the higher the energy of the particle, the less time it can exist. 06:23: ... can be argued that virtual particles are just a mathematical tool to describe the behavior of a dynamic ... 06:45: Real or not, the calculations of QFT, which hinge on these particles, are stunningly accurate. 06:57: They live in the interval between measurements of real particles. 07:10: ... first hint of the existence of virtual particles came in 1947, when Willis Lamb and Robert Rutherford noticed a tiny ... 07:50: Virtual particle-antiparticle pairs in the space between the orbitals and the nucleus align themselves with the electric field. 08:15: Another way to hunt for virtual particles is through their bulk effect on the vacuum. 08:20: ... if quantum fields are abuzz with particles popping into and out of existence, then the so-called zero point energy ... 10:53: ... field theory, with its dependence on virtual particles and vacuum fluctuations, is one of the most successful theories in all ... 13:26: Any particle with integer spin is a boson. 13:32: ... we typically think of meta particles as fermions because the elementary particles that form atoms are all ... 14:26: ... normal positive temperatures, particle kinetic energies span a large range, but always have a distribution ... 14:38: But at negative temperatures, most particles are excited towards the highest possible energy states. 15:11: But when you stack particles towards the highest energy states, that's a special arrangement, making it low entropy. 15:20: Add more energy, and more particles reach the highest energy state, which decreases entropy further.
	2017-10-11: Absolute Cold 00:16: [MUSIC PLAYING] The mystical-seeming quality of heat is nothing more than the motion of a substance component particles. 00:37: But what if we reduce temperatures so much that all particle motion ceases? 01:45: In these states of matter, particles have an enormous range of individual energies, some moving or vibrating fast, some slow. 01:52: Temperature just represents the average kinetic energy of the countless particles. 01:57: And while a substance can theoretically have any temperature above absolute zero, its component particles cannot. 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. 02:46: As we sap energy out of certain substances, its particles drop into the lowest possible energy state. 02:53: Once nearly all particles occupy that one quantum state, they share a single, coherent wave function. 03:08: Individual particles can no longer be bumped or jostled out of that lower state. 04:00: Helium 4 has a total spin of 0, which makes it a boson so a particle with integer spin. 04:40: In theory, absolute zero temperature means no thermal energy so no internal motion of particles whatsoever. 04:49: But what does it mean for a particle to be completely still? 05:11: For example, the more precisely a quantum particle's position is defined, the less defined is its momentum. 05:20: A particle with a perfectly defined position has a perfectly undefined 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. 06:00: For a group of particles that make up any form of matter, that zero-point energy isn't actually zero.
	2017-10-04: When Quasars Collide STJC 05:02: That field can accelerate narrow streams of high-energy particles away from the black hole. 11:06: The standard model of particle physics contains 26 independent parameters, things like the coupling constants and the masses of each particle type.
	2017-09-28: Are the Fundamental Constants Changing? 00:30: [MUSIC PLAYING] The laws of physics are the relationships we observe between space and time, and the fields and particles that occupy it. 00:50: ... example, the standard model of particle physics is comprised of equations that predict the existence and ...
	2017-09-20: The Future of Space Telescopes 08:46: ... proposed we use photon pressure to suspend a cloud of tiny reflective particles in Earth's ... 09:01: ... particles would be fractions of a millimeter in size, small enough that commercial ...
	2017-09-13: Neutron Stars Collide in New LIGO Signal? 02:39: ... have enormous magnetic fields that result in jets of near light speed particles that sweep through space like a ...
	2017-08-16: Extraterrestrial Superstorms 12:11: ... natural extension would be that every elementary particle along with its anti-particle counterpart is the same particle bouncing ...
	2017-08-10: The One-Electron Universe 02:34: It exists as a line traced by its passage through space and time, rather than as a point-like particle at one instant in time. 03:45: Well, moving charged particles also produce a current-- an electric currents. 04:36: But reversing a particle's motion is mathematically the same as watching it in reverse time. 04:43: ... goes backwards, just that if you reverse the ticking of the clock in the particles coordinate frame, its direction of motion appears reversed, which has ... 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. 05:21: P is parity inversion, which can be thought of as reflecting the particle like in a mirror. 05:27: ... at the same time-- flip the charge, invert the parity, reverse time-- a particle should end up back where it ... 05:56: But a charge flip just turns a particle into its anti-matter counterpart. 06:49: That virtual particle in the middle may be an electron traveling forwards or backwards in time. 07:11: Similarly, the creation of a particle pair is the electron being scattered in time. 08:45: ... that every electron-- indeed every particle in our bodies, in everyone's bodies-- is the same particle separated ... 10:05: As long as the incoming and outgoing particles have the same momenta, these two are part of the same overall interaction.
	2017-08-02: Dark Flow 10:30: Incoming and outgoing particles must obey energy and momentum conservation. 10:53: Well, actually, the spatial positions and even directions of motions of particles in the diagrams don't mean much at all. 11:01: Each incoming and outgoing particle is identified with a numerical position and momentum. 11:27: The answer is that the states of the outgoing particles are also entangled with that other electron. 11:34: Upon measurement of the properties of the outgoing particles, weed entanglement correlations can still occur.
	2017-07-26: The Secrets of Feynman Diagrams 00:03: ... Feynman diagrams revolutionized particle physics by providing a simple system to sort out the infinite ... 00:19: ... path integral shows us that to properly calculate the probability of a particle traveling between two points, we need to add up the contributions from ... 02:47: None of these particles are doing anything worth calculating. 02:59: Particle/field interactions are represented as a vertex, a point where the lines representing the different particles come together. 03:31: ... represents an initial electron that emits a photon, after which, both particles move off in opposite ... 04:35: ... of conservation laws-- energy and momentum conservation requires that particles not just vanish or appear from nothing, which guarantees that if ... 05:11: ... are other more complex ways in which ingoing and outgoing particles can balance charge, but as we'll see, all of these can be built up from ... 05:25: The overall interaction described by a set of Feynman diagrams is defined by the particles going in and the particles going out. 05:34: These are the particles that we actually measure. 05:45: We say that these particles are on the mass shell, or just on shell. 06:06: Each possible diagram that results in the same ingoing and outgoing particles is a valid part of the possibility space for that interaction. 06:15: The particles that have their entire existence between vertices within the diagram but don't enter or leave are called virtual particles. 06:25: Their correspondence to anything resembling real particles is debatable. 06:33: Otherwise, they'd be one of our ingoing or going particles. 06:37: These particles do not obey mass-energy equivalence. 06:44: These particles aren't even limited by the speed of light or the direction of time, which leads to all sorts of fun. 07:47: To start with, each of the particle paths are actually infinite paths. 07:51: As well as infinite possibilities for particle momenta, we have to consider even impossible faster than light paths. 08:01: For any particle besides the going and outgoing on shell particles, any energy, speed, and even direction in time is possible. 08:56: ... that intermediate stage between vertices, the electron is a virtual particle, which means we include all possible paths it might take, as long as they ... 09:20: The same particles go in and out, but now, the interactions look very different.
	2017-07-19: The Real Star Wars 10:08: ... based lasers, which supposedly blinded some US spy satellites, and particle beams, actual death rays, which never really ... 17:50: I think we have a particle physicist in the house.
	2017-07-12: Solving the Impossible in Quantum Field Theory 00:27: ... of quantum field theory allow us to calculate the behavior of subatomic particles by expressing them as vibrations in quantum ... 02:55: There are other types of virtual particle whose existence is similarly ambiguous. 08:21: ... loop interactions, like when a photon momentarily becomes a virtual particle-anti-particle pair and then reverts to a photon again, or when a single electron emits ... 10:27: ... for example, the infinite shielding of electric charge due to virtual particle-anti-particle pairs popping into and out of ... 11:08: ... diagrams successfully describe everything from particle scattering, self-energy interactions, matter-anti-media creation and ... 11:41: The results led to the standard model of particle physics. 13:41: In Schrodinger's equation, all of the particles are tracked according to one universal master clock. 13:48: ... Feynman's approach, each particle is tracked according to its own proper time clock, which can vary in its ... 14:10: [INAUDIBLE] points out that the final probability for a particle journey is the square of the length of the complex probability amplitude vector. 15:03: Feynman didn't limit particle velocity to the speed of light.
	2017-07-07: Feynman's Infinite Quantum Paths 00:44: Knowing a particle's location perfectly means its velocity is unknowable. 01:10: ... the too long, didn't watch for the double-slit experiment is this-- a particle, say a photon or an electron, travels through a barrier containing two ... 01:27: ... interference pattern produced by particles on the screen can only be explained if each of them travels through both ... 01:52: ... prof showed how the locations of the particles on the screen can be calculated by adding the amplitude of a wave ... 03:09: ... idea is essentially this-- to know the likelihood of a particle traveling between two points, A to B, we need to take into account all ... 03:40: ... combine the infinite paths to give a very real finite probability of a particle reaching its final ... 03:51: ... for the journey into small intervals and at each time step allow the particle to take any conceivable straight-line step in ... 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. 05:33: ... from all of those infinite possible paths to find the probability of a particle making that simple journey from A to ... 06:32: But to get the total probability that a particle travels from A to B, you connect the probability amplitude arrows for all possible paths end to end. 07:51: ... a bit more work and help from others, like figuring out how to add particles with spin, the path integral approach is both mathematically equivalent ... 08:10: This action quantity is a function of the particle's path through space-time. 08:50: See, when I say there are lots of ways for a particle to travel from point A to B, I mean lots. 08:56: It's not just that a particle can travel infinite physical paths. 09:00: Also, infinite things can happen to the particle on the way. 09:17: And a traveling electron could emit and reabsorb a photon, which itself could make its own particle-antiparticle pair ad infinitum. 09:26: Let's not even get started with the complexity of two or more particles interacting. 09:31: ... oscillating fields just as well as it can describe a universe of moving particles. ... 09:44: Instead of adding up all possible paths that particles can take, you instead add up all possible histories of quantum fields. 10:54: However, unlike the ridiculous infinite trajectories a particle can take, those infinite events don't cancel out nearly so neatly. 14:06: ... points out that if matter and antimatter particles are always created in pairs, shouldn't there be just as much antimatter ... 14:27: Almost all of the matter and antimatter annihilated each other, leaving only one in a billion particles of matter. 15:07: Quantum field theory describes particles as a field vibration in 4D space-time. 15:13: And each elementary particle has its own field. 15:16: String theory states that all particles are different vibrational modes in one-dimensional objects called strings.
	2017-06-28: The First Quantum Field Theory 01:18: ... Field Theory, QFT, describes all elementary particles as vibrational modes in fundamental fields that exist at all points in ... 05:48: It's terrible for many particle systems. 05:52: It follows the changing position and momentum and generally the physical quantum state of every individual particle but that's extremely inefficient. 06:02: See, two of the same type of elementary particle are indistinguishable from each other. 06:15: ... the quantum state of every individual particle is like trying to do your finances by tagging and tracking the movement ... 06:50: If you try to track individual particles, you're at risk of double-counting. 06:55: You end up with multiple arrangements of particles that are actually the same arrangement due to the particles being identical to each other. 07:12: Instead of quantizing particles' physical properties like position and momentum, as did Schrodinger, Dirac quantized the electromagnetic field itself. 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. 08:36: Schrodinger's approach of tracking the changing quantum state of each particle became the first quantization. 08:50: See, Schrodinger's approach has no idea how to destroy a particle. 08:56: All it can do is move particles around via their evolving wave functions. 09:02: Yet, in particle interactions, particles are created and destroyed all the time. 09:18: But the second quantization is all about creating and destroying particles. 10:13: Spurred by its success in describing electromagnetism, physicists soon extended the second quantization approach to other elementary particles. 10:26: ... or electron quark, et cetera, per quantum state, rather than infinite particles in the case of the ... 10:39: Nonetheless, second quantization works for all elementary particles. 10:55: So does this mean that all particles are also oscillations in fields? 11:02: In fact, every base elementary particle has its own field. 11:13: Fields are fundamental and particles and their antimatter counterparts are just ways in which that field vibrates. 11:28: ... for every type of quark-antiquark pair, for every type of force-carrying particle-- so-called bosons, like photons and gluons-- and of course for the famous ... 14:18: However, the Klein Gordon equation is actually the exactly right description for particles with no spin.
	2017-06-21: Anti-Matter and Quantum Relativity 00:50: By the late 1920s, Einstein and Planck had already shown that light is a particle, as well as a wave. 01:01: Bohr, Heisenberg, Born, Pauli, and others pieced together a mathematical description for the weird nature of subatomic particles. 01:56: ... the Schrodinger equation tracks the evolution of a particle's wave function according to one and only one clock, typically the clock ... 02:17: Subatomic particles are often moving at close to the speed of light. 02:21: ... other problem with the Schrodinger equation is that it describes particles as simple wave functions, distributions of possible positions and ... 02:33: Yet, we now know that many elementary particles have an internal property called spin. 03:20: In fact, it applies to all particles called fermions. 05:45: The resulting Dirac equation describes the spacetime evolution of this weird four-component particle-wave function, represented by the symbol psi. 07:45: That hole should act like a particle all by itself. 08:38: We now know that every elementary particle has an associated field, that fills all of space. 08:53: And the elementary particles that we know and love are just regions where a field has a bit more energy. 10:20: So all elementary particles have a quantum field and all have an anti-matter counterpart. 10:27: Just as with the holes in the Dirac sea, anti-matter particles have the same mass as their counterparts, but opposite charge. 11:03: ... and quantum field theory and the development of the standard model of particle physics, which have become our best description of the underlying ... 14:38: ... to fill that universe, fundamentally changing the way its elementary particles ...
	2017-05-17: Martian Evolution 07:15: Even more dangerous than the UV are high-energy cosmic rays and solar particles.
	2017-05-03: Are We Living in an Ancestor Simulation? ft. Neil deGrasse Tyson 08:01: ... is that in an infinite multiverse, it should be vastly more common for particles to randomly assemble into a brain that is having exactly your current ... 13:06: So today we're going to talk about both the oh my god particle and Boltzmann brains. 13:12: So OxFFF1 wants to know what would happen to the unlucky sap struck in the head by an OMG particle. 13:19: Well, these particles are usually single atomic nuclei. 13:24: The particle may pass straight through your body, only depositing a bit of ultraviolet drink of radiation. 13:34: However, the particle might also hit a molecule. 13:52: ... the Boltzmann brain thought experiment fails because it assumes random particle motion, and that particle motion is actually ... 14:02: Well, particle motion may be purely deterministic. 14:36: ... true that particles all converging on one spot in a room is resisted by more than just the ... 14:58: Particles can start out in a high density configuration, say, in the corner of a room, and then expand. 15:06: ... principle, if you were to take such an expanded cloud of particles and exactly reverse their velocities, then they would all end up back in ... 15:17: That perfect time reversal would include the reverse of every particle interaction that happened in the original expansion. 15:26: Now it's those same particle interactions that gives rise to pressure. 15:33: Interactions can drive particles either outwards or inwards. 15:37: Because particles can be pushed beyond the edge of the cloud, there end up being somewhat more interactions driving particles outwards than inwards. 15:57: ... principle, a perfect set of particle positions and velocities could be found such that the subsequent series ...
	2017-04-26: Are You a Boltzmann Brain? 00:14: Your memory of your entire life also just came into being through a chance arrangement of particles. 00:44: He showed that the laws of thermodynamics can be explained by thinking of gas as a collection of microscopic particles in constant, random motion. 02:14: Entropy is just a measure of the specialness, or the degree of order, in the current arrangement of positions and velocities of a system's particles. 03:06: If you count up all the possible arrangements of particles, only a tiny proportion do weird, highly ordered stuff like that. 03:18: Entropy increases because particle positions and velocities get randomized over time. 03:37: For example, tiny, localized dips in entropy happen all the time, when you get a chance convergence of a few particles in one corner of the room. 03:52: ... an incredibly tiny chance that all of the particles in a room of gas will happen to all end up in one corner of the room, ... 04:26: ... Particles will occasionally converge into a dense environment like a black hole or ... 04:42: However, there's one arrangement that those particles could randomly fall into that would be even less probable than all of the above. 04:50: All the particles in a region much larger than our universe could randomly end up in almost the exact same location. 07:12: For example, why collapse a whole universe worth of particles? 07:28: ... not just have particles converge directly into a single human brain, in exactly the right ...
	2017-04-19: The Oh My God Particle 00:00: ... PLAYING] Long before the God particle, there is the Oh-My-God particle, a cosmic ray vastly more energetic than ... 00:46: The nucleus quickly disintegrated into a shower of subatomic particles and lights. 01:30: The particle was dubbed the Oh-My-God particle. 01:48: High energy particles, electrons, and small atomic nuclei, as well as gamma rays, are ejected when heavier radioactive elements decay. 02:35: And that meant there had to be a source of these high-energy particles somewhere above. 02:44: ... ride, and even following the Fly's Eye detection of the Oh-My-God particle, we've come a long way in the art of catching cosmic ... 03:40: The result is a cascade of subatomic particles, the debris of the collision, that can spread itself out over several kilometers. 03:48: These cascades are called air showers, streams of charged particles cause the air to fluoresce, a glow that can be seen by specialized telescopes. 03:58: Many of the debris particles also reach the ground and can be detected there. 04:25: ... giant tanks of water designed to see Cherenkov radiation when air shower particles pass through them, as well as telescopes to spot fluorescence in the air ... 04:51: ... simple slabs of acrylic between metal plates designed to stop air shower particles and detect the light produced as they smack into nuclei within the ... 05:16: We also see gamma rays and even anti-matter particles. 05:19: ... crazy 10 to the power of 20 electron volts or higher, like the Oh-My-God particle. ... 05:33: At the lowest energies, the cosmos flings one particle every second per square meter of the Earth's surface. 05:39: At energies up near that of the OMG particle, they are incredibly rare. 05:54: To accelerate a particle to the energies of cosmic rays, you need a particle accelerator. 06:05: It turns out that the universe is full of natural particle accelerators. 06:24: It can trap particles and accelerate them until they're energetic enough to escape the shock. 06:47: The most ridiculous cosmic rays, like the Oh-My-God particle, shouldn't exist at all. 06:53: See, the universe is basically opaque to particles with such high energies. 07:27: For years, it was thought that no cosmic ray could exceed it, except that the OMG particle was six times more energetic. 07:36: Only a very small number of these extreme energy cosmic rays have been seen since the OMG particle. 08:22: For cosmic ray astrophysicists, there's a giant invisible particle accelerating elephant in the room. 08:39: ... from cosmic rays passing through their eye's vitreous humor, or from the particles hitting their optic ... 09:07: ... we figure out the origins of these particles, cosmic ray astronomy is becoming an increasingly powerful tool for ... 09:16: But even now, these particles are extremely useful. 09:20: ... highest energy cosmic rays, like the Oh-My-God particle, generate collisions far more energetic than our largest particle ...
	2017-04-05: Telescopes on the Moon 05:17: Hit by sunlight, tiny regolith particles build up electric charge, and so repel each other into dust fountains in the low lunar gravity. 11:54: You'd also expect that surface to contain a vast amount of energetic particles converted from infalling material.
	2017-03-22: Superluminal Time Travel + Time Warp Challenge Answer 00:53: ... using tachyons, hypothetical faster-than-light or superluminal particles, it's possible to receive and reply to a message before the message is ...
	2017-03-15: Time Crystals! 02:01: Wilczek came up with a simple model in which charged particles in a superconducting ring break what we call continuous time translational symmetry.
	2017-02-15: Telescopes of Tomorrow 03:08: It can scatter off a dust grain, like a particle.
	2017-02-02: The Geometry of Causality 08:50: From the point of view of a particle communicating some causal influence, those points are equivalent. 12:07: ... at the center of black holes is with string theory, which proposes that particles that we see in regular 4D spacetime result from oscillations within many ...
	2017-01-25: Why Quasars are so Awesome 01:19: Sometimes they even have jets of near light speed particles filling the surrounding universe with giant radio plumes.
	2017-01-11: The EM Drive: Fact or Fantasy? 07:28: To exchange momentum with virtual particles over a distance longer than a Planck length, those particles need to become real. 07:36: Photons would need to give up their energy, producing particle anti-particle pairs. 07:45: If it were, those particles would also be trapped in the cavity.
	2016-12-08: What Happens at the Event Horizon? 14:50: ... asks how it can be that pilot wave theory predicts different particle trajectories, given that the particles supposedly all start at exactly ... 15:02: Well, the simple answer is that the particles don't start at exactly the same points. 15:11: ... pilot wave theory states that the particle riding the wave does have a definite position at all times and that ... 15:30: However, you can't perfectly measure a particle position without changing it slightly in ways that themselves aren't perfectly predictable. 15:38: As a result, you never know exactly where a particle is. 16:05: ... knowledge and that the universe itself knows exactly where all these particles ... 16:16: Vacuum Diagrams correctly points out that to know the future trajectory of a particle, you only need position, not velocity, as I had stated. 18:01: In fact, De Broglie was never a huge fan even of his own simplistic particle carried by a wave idea. 18:08: ... be a much more intricate double solution theory in which the so-called particle was actually a matter wave itself embedded in and carried by the sine ... 18:25: ... Solvay Conference, and so derived the simpler description in which the particle is ...
	2016-11-30: Pilot Wave Theory and Quantum Realism 00:55: ... explanations claim stuff like things are both waves and particles at the same time, the act of observation defines reality, cats are both ... 02:36: ... fundamental randomness determines the properties of, say, the particle that would emerge from its wave ... 02:59: This required an almost mystical duality between the wave and particle-like nature of matter. 03:11: ... full theory that described how a quantum object could show both wave and particle-like behavior at the same time without being fundamentally ... 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. 03:46: Why not just have real waves that push around real particles? 03:59: This wave guides the motion of a real point-like particle that has a definite location at all times. 04:37: Because particles follow the paths etched out by the wave, it'll end up landing according to that pattern. 04:45: The wave defines a set of possible trajectories and the particle takes one of those trajectories. 04:51: ... the choice of path isn't random-- if you know the exact particle position and velocity at any point, you could figure out its entire ... 07:05: ... function how to change, it also has a guiding equation that tells the particle how to move within that wave ... 07:44: Bohmian mechanics has so-called hidden variables, details about the state of the particle that are not described by the wave function. 09:07: The entire wave function knows the location, velocity, and spin of each particle. 09:18: Not only does the entire wave function know the properties of the particle, but the entire wave function can be effected instantaneously. 09:30: This can therefore affect the trajectories and properties of particles carried by that wave, potentially very far away. 09:47: Again, we've gone into the non-locality of entangled particles in detail before. 11:05: Quantum field theory pretty explicitly requires that all possible particle trajectories be considered equally real. 11:13: Pilot-wave theory postulates that the particle really takes a single actual trajectory, the Bohm trajectory. 11:41: Also, we can't ignore the fact that the initial motivation behind pilot-wave theory was to preserve the idea of real particles. 14:00: And the resulting particles are called strangelets. 14:37: That might seem a problem for an object made up of neutral particles like a neutron star.
	2016-11-16: Strange Stars 03:19: Degenerate matter is so compressed that particles can't get any closer together without occupying the same quantum states. 03:27: The Pauli exclusion principle states that this is forbidden for fermions, the family of particles that neutrons belong to. 04:17: And we have good reason to think that, because we can actually make this stuff in our largest particle accelerators. 04:25: Minuscule flecks of quark-gluon plasma exist for tiny fractions of a second after very high-speed particle collisions. 04:33: We can study its nature based on the particles that decay from it. 05:40: It has three quark types instead of two, and that means more particles can occupy the lowest quantum energy states.
	2016-11-02: Quantum Vortices and Superconductivity + Drake Equation Challenge Answers 00:36: ... a liquid to a solid as temperature drops, and the motion of individual particles in the material gets slower and ... 01:33: ... extremely low temperatures, the spins of a material's particles tend to line up, but you get these little twists at certain points: a ... 01:45: These vortices occur in pairs and have some amazing behaviors that resemble the behavior of elementary particles.
	2016-10-26: The Many Worlds of the Quantum Multiverse 00:53: Mathematically, this is encapsulated in the wave function of a quantum particle or system of particles. 01:17: These particles arrive at the screen distributed like the interference pattern you would expect from a simple wave. 01:24: Quantum mechanics very successfully predicts this result by describing each particle's journey as a superposition of all possible trajectories. 01:33: In other words, the particle simultaneously takes all possible paths, which means it passes through both slits. 04:27: Instead, it chooses an end result-- say, particle location on a screen or cat alive or deadness-- based on those histories. 06:20: ... Copenhagen interpretation tells us that the superposition of particle trajectories, of histories, merges into the single timeline of the ... 07:07: ... states diverge into different possibilities-- for example, at every particle interaction everywhere in the ...
	2016-09-29: Life on Europa? 09:45: ... couple of you asked what result you would get if you measured one particle with a vertically-aligned measurement device and a second particle with ... 09:57: ... theory versus pure quantum mechanics is if you measure the spins of both particles with the same measurement ... 10:17: ... relationship of the chosen measurement axis with the hidden spins of the particle. ... 10:29: ... other at 90 degrees, then the pure quantum prediction is that the second particle is aligned one way 50% of the time and the other way 50% of the ... 10:54: ... contrast, a local hidden variable prediction is that the second particle doesn't care how the first was measured, so it aligns itself according ... 11:30: Rather, observation may just mean any interaction that destroys quantum coherence between the entangled particles. 11:37: ... is that this measurement interaction effectively entangles the measured particle and its partner with a macroscopic system so complex that we no longer ... 12:47: ... no need for a faster-than-light signal to tell particle a what measurement has been carried out on particle B because the ...
	2016-09-21: Quantum Entanglement and the Great Bohr-Einstein Debate 03:24: Two particles interact briefly. 03:36: ... mechanics requires that we describe the particle pair with a single combined wave function that encompasses all possible ... 03:45: We call such particles an entangled pair. 03:49: ... according to the Copenhagen interpretation, any measurement of one particle automatically collapses the entire entangled wave function, and so ... 04:45: When spontaneously created from a photon, these particles will always be spinning in opposite directions to each other. 05:04: Measurement of the spin of one of these particles tells us the spin of the other, no matter how large the distance between them. 05:48: Measurement forces the alignment of the measured particle. 06:00: ... one, if Einstein was right, imagine the response of each particle to all possible spin measurements is encoded in each particle at the ... 06:16: Nothing we do later to one particle will then affect the other. 06:20: When we later measure the spins of both particles, there will be a correlation in the results because the particles were once connected. 06:43: In that case, measurement of one particle spin should cause the entire wave function to collapse, to take on defined values. 06:51: Both particles should then manifest opposite spins along whichever axis we choose for one of the particles. 06:59: That should lead to a correlation between our choice of measurement axis for the first particle and the spin direction then measured for the second. 09:34: Non-locality requires that entangled particles affect each other instantaneously. 09:57: But none of these entanglement experiments allow any real information to be transmitted between particles. 10:41: ... example, entangled particles may be dimensionally connected by Einstein-Rosen bridges, wormholes that ...
	2016-09-07: Is There a Fifth Fundamental Force? + Quantum Eraser Answer 00:21: ... that told physicists that for a tiny fraction of a second an unknown particle may have ... 00:45: And when they settle down again, they give off that energy as photons, but also sometimes as a particle or a particle-antiparticle pair. 01:09: It's as though something with a mass energy equivalence of 17 MEV was decaying into those particles. 01:29: Just recently a new very slow excess of the LHC was originally thought to be a new particle. 01:52: But why do they think that the mysterious 17 MEV particle is a new type of fundamental force? 02:20: Such a particle would be a mild extension of the standard model, not too crazy, but certainly brand new physics. 02:49: Well, the standard wisdom for finding new particles is to create higher and higher energies; hence, the Large Hadron Collider. 02:56: Any particle capable of existing at lower energies should have been spotted. 03:01: But that's not true if the particle is a ninja. 03:25: ... the decay product of such a transition is very weakly interacting, these particles could be everywhere and we wouldn't know it, like ninjas and like dark ... 03:46: I mean that this new particle may have something to do with dark matter.
	2016-08-17: Quantum Eraser Lottery Challenge 01:38: They just land in a single pile as though they had traveled as particles through the entire experiment.
	2016-08-10: How the Quantum Eraser Rewrites the Past 00:20: We recently talked about the weird results of the single particle double slit experiment. 00:51: ... the single particle double slit experiment suggests that things may not exist as ... 01:03: There's a fuzzy space in which we don't know the particle's location or path. 01:08: The Copenhagen interpretation would tell us that in this space, a particle is only its wave function, a distribution of possible properties. 01:29: At that point, the Copenhagen interpretation tells us that a true transition happens between wave and particle. 01:42: Does observation of the particle's location force the universe into settling down and deciding which particular reality we happen to be in? 02:19: The great mystery of the experiment is that very particle-like things appear to traverse both slits simultaneously, like you might expect of a wave. 02:30: ... and so have tried very, very hard to peek to see which slit these particles actually travel through before they produce the famous interference ... 02:44: Any experiment that determines unambiguously which slit the particle traverses destroys the interference pattern. 02:52: Instead, particles land in simple clumps, one for each slit, as though they were traveling as simple particles the whole time. 03:01: ... true if you place detectors on the far side of the slits after the wave particle thing should have already been interfering with itself, just like the ... 03:20: Better pretend like you are particles that whole time. 04:20: So they've come up with clever ways to measure which way the particle traveled while still preserving coherence. 08:01: ... resolves itself into a set of known properties, say, the location of a particle on the double slit screen, somehow the entire wave function knows to do ... 09:21: As we'll see in the future, entangled particles really are able to influence each other instantaneously.
	2016-08-03: Can We Survive the Destruction of the Earth? ft. Neal Stephenson 10:46: See you next time on "Space Time." Last week we talked about the spectacular weirdness of the single particle double-slit experiments. 11:15: ... that when the wave function collapses, the properties of the resulting particle are picked randomly from that probability ... 11:50: ... communication across the wave function, or between entangled particle pairs, in order to satisfy experimental ... 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.
	2016-07-27: The Quantum Experiment that Broke Reality 00:06: One of the strangest experimental results ever observed has got to be that of the single particle double-slit experiment. 03:25: ... their energy at a single spot and so they appear to be acting like particles of well-determined ... 05:23: ... the peaks of that pattern are regions where there's more chance that the particle will find ... 06:21: We know where the particle is at both ends. 06:36: So the particle seems to be more particle-like at either end but wave-like in between. 06:44: ... wave holds the information about all the possible final positions of the particle but also about its possible positions at every stage in the ... 06:55: In fact, the wave must map out all possible paths that the particle could take. 07:26: Within that mysterious span between the creation and the detection, is the particle anything more than a space of possibility? 08:09: ... suggests that a particle traversing the double-slit experiment exists only as a wave of possible ... 08:21: It's only when the particle is detected that a location and the path it took to get there are decided. 08:27: ... tells us that prior to the collapse, it's meaningless to try to define a particle's ... 09:54: ... field and quantum field theory tells us that all fundamental particles are waves in their own ...
	2016-07-20: The Future of Gravitational Waves 05:41: ... question, we asked you to calculate the probability that an alpha particle-- so a package of two protons and two neutrons-- would tunnel out of the ... 06:03: You needed to figure out how many times the alpha particle would encounter the walls of the nucleus in this time. 06:16: To do this, you needed to assume that the alpha particle bounces back and forth between the walls of the nucleus with a constant velocity. 06:32: ... get the alpha particle velocity from its kinetic energy, which I gave you, and you get the size ... 06:41: You'll get that there's approximately a 10 to the power of minus 15 chance of the alpha particle tunneling on each encounter. 06:57: And the extra credit question asked, what physical distance does the particle actually tunnel? 07:03: ... the nuclear protons, reaches the 8.78 mega electron volts of the alpha particle's kinetic ... 07:21: So how far did the alpha particle tunnel?
	2016-06-29: Nuclear Physics Challenge 00:19: But here's TL;DR. Particles of matter have wave-like properties. 00:37: For example, a particle bound within an atomic nucleus may spontaneously find itself outside the nucleus, where the binding force no longer holds it. 00:52: But don't literally take it, because it's one of the most radioactive elements known, and it decays as alpha particles tunnel out of its nucleus. 01:02: It's so radioactive that it glows blue as these alpha particles ionize the air around it. 01:34: The challenge for today is for you to figure out the tunneling probability for an alpha particle to escape from a polonium 212 nucleus. 01:46: Picture an alpha particle as being trapped inside a box. 01:57: The particle is bouncing between these force walls. 02:19: A good first step might be to figure out how many times the alpha particle encounters the wall in that 0.3 microseconds. 02:46: You'll also need the velocity of the alpha particle. 02:49: The alpha particle ejected in the decay of polonium 212 has a kinetic energy of 8.78 MEV. 02:56: And you can calculate the velocity using the equation for kinetic energy and the mass of the alpha particle. 03:04: ... some basic algebra is enough to get you the probability that an alpha particle will tunnel out of the polonium 212 nucleus on any one encounter with ... 03:19: And the extra credit question-- how far does the alpha particle teleport from the nucleus when it pulls off this tunneling trick? 03:28: To successfully tunnel, the alpha particle needs to reach a lower energy state. 03:34: That happens when the potential energy of the cooling force trying to drive it away from the nucleus is equal to the kinetic energy of the particle.
	2016-06-22: Planck's Constant and The Origin of Quantum Mechanics 03:10: Heat is just the energy in the random motion of particles comprising an object. 03:19: And so an object made of jiggling charged particles, like electrons and protons, glows. 03:26: The hotter an object is, the faster its particles jiggle. 03:30: And so the average frequency of the resulting particles of light, of photons, increases with temperature. 05:12: It states that an object's heat energy will end up juggling all of its particles in all the ways that they can be jiggled. 06:28: The Rayleigh-Jeans calculation allows particles to vibrate with any amount of energy, all the way down to infinitesimally tiny wiggles. 07:26: He decided that those particles could only vibrate with energies that were a multiple of some minimum energy. 07:38: He set this minimum energy to be the frequency of a particle's vibration times a very, very small number, a number that had yet to be measured. 09:36: ... little vibrating particles do have quantized energies, but it's because they can only gain or lose ... 09:52: ... needed to hypothesize the existence of the photon-- part wave, part particle, carrying a quantum of energy equal to the now familiar frequency of the ...
	2016-06-15: The Strange Universe of Gravitational Lensing 10:18: Think about that alpha particle trying to tunnel through the potential energy wall of the strong nuclear force. 10:29: The particle could find itself located anywhere that its wave function is non-zero. 12:58: ... is another way of saying that a particle's wave function gets so hopelessly mixed with those of other particles ...
	2016-06-08: New Fundamental Particle Discovered?? + Challenge Winners! 00:00: ... CERN's Large Hadron Collider reported a hint of evidence of a brand new particle, one that does not fit anywhere within the standard model of particle ... 00:18: ... the standard model is basically the periodic table of fundamental particles and forces that represents our entire current understanding of the ... 00:30: Even the incredible discovery of the Higgs bosun in 2012 was a confirmation of the final particle of the standard model. 00:50: Well, let's first think about how particle accelerators-- and especially the LHC-- work. 01:34: Their energy is released and reshapes itself into new particles. 01:39: Many, many weird particles come out of such a collision. 01:51: We only know they ever existed because the resulting gamma radiation has an energy corresponding to the mass of the decayed particle. 02:17: This suggests a new particle with a mass much larger than anything in the standard model. 02:56: But particle physicists are completely losing their minds. 03:14: There are theoretical ideas of particles that could cause a bump at this energy, and would also make pretty decent dark matter candidates. 03:47: A highly speculative particle responsible for the transmission of the gravitational force. 03:52: But it's not yet even known whether such a particle exists, or is needed to explain gravity. 03:59: Or five-- it's a composite of other smaller particles.
	2016-06-01: Is Quantum Tunneling Faster than Light? 02:00: That's true of subatomic particles, and it's sort of true of anything. 02:37: ... are made up of several tens of kilograms of thermal moving particles and have de Broglie wavelengths a couple of orders of magnitude smaller ... 02:56: But what about something much smaller, say a tightly bound bundle of two protons and two neutrons that we call an alpha particle? 03:13: There an alpha particle is snugly bound into the nucleus by the strong nuclear force. 03:19: We can imagine an alpha particle as being like a ball trapped in a steep valley of potential energy. 03:39: As an alpha particle approaches the force barrier of the nucleus, its wave packet is reflected backwards, usually. 03:48: See, that wave packet describes a range of possible locations for the approaching particle. 04:19: ... there is a very tiny chance that instead of bouncing off the wall, the particle will, at the last minute, resolve its position in that unlikely outside ... 04:41: When it's an alpha particle escaping a nucleus, this is one of the most important mechanisms for radioactive decay. 04:52: Protons, neutrons, electrons, and alpha particles can quantum tunnel into nuclei in various types of fusion and particle capture phenomena. 05:14: But how quickly does the alpha particle move through this barrier? 06:18: ... just like with the alpha particle, as the photon approaches the barrier the wave packet defining its ... 08:20: A particle resolves its location anywhere within the vicinity of its de Broglie wavelength.
	2016-05-18: Anti-gravity and the True Nature of Dark Energy 04:14: That's the pressure due to fast-moving particles and radiation. 04:30: The internal gas pushes outwards as fast-moving particles collide with the walls. 04:36: ... if fast-moving particles produce an outward push in pressure, then is this how dark energy is ... 05:00: In order for the pressure of fast-moving particles to create an outward push, the region beyond them has to be an area of lower pressure. 05:25: See, high pressure from regular matter and energy means very fast-moving particles. 05:33: And the motion of these particles results in a combination of relativistic corrections. 05:39: ... effect is that the massive of a region of the universe is higher if its particles are moving quickly compared to a region where the particles are moving ... 09:38: Part of the problem is that negative pressure doesn't come from the motion of dark energy particles, whatever they might be.
	2016-04-06: We Are Star Stuff 00:39: ... blocks of matter, the elementary fields that fill our universe, and the particles that they manifest through their vibrations, these all lend themselves ... 01:04: ... when those elementary particles start interacting to form nuclei, atoms, and molecules-- chemistry-- ... 03:06: In fact, those protons will outlast almost every other nonelementary particle in the universe. 03:46: Two protons, two neutrons, 12 quarks, a complicated but very stable marriage of particles. 12:56: Well, we can sort of answer that for two particles at opposite sides of the currently observable part of the universe.
	2016-03-30: Pulsar Starquakes Make Fast Radio Bursts? + Challenge Winners! 04:21: ... and helium nuclei, the other common charged particles hanging around the universe at this time, have much smaller scattering ...
	2016-03-02: What’s Wrong With the Big Bang Theory? 01:40: In a previous episode, we talked about how the Higgs field gives particles mass. 01:52: ... turns out that when you take this Higgs mass away from the particles that carry the weak nuclear force, they become just like the photon, ... 07:05: Another way to say this is that those edges of the universe have always been beyond each other's particle horizons.
	2016-02-24: Why the Big Bang Definitely Happened 01:15: ... and are supported by many experiments, from astronomical observations to particle collider experiments to supercomputer ... 08:05: We've recreated those insane energies in our particle accelerators.
	2016-02-03: Will Mars or Venus Kill You First? 01:35: ... has allowed the solar wind, the constant stream of energetic particles from the sun, to whittle away at Mars' ... 05:27: This is when a magnetic storm on the sun's surface sends out a blast of extremely high energy particles, most notably protons and electrons.
	2016-01-27: The Origin of Matter and Time 03:37: Now remember, a photon clock marks time with a particle of light bouncing between two mirrors. 06:17: ... confined not by mirrored walls, but by interactions with other particles and force ... 06:28: ... in which the familiar electrons and quarks are composites of massless particles confined by the Higgs ... 06:50: At each interaction, particles exchange energy, charge, and other properties that result in change. 06:56: In those particles, and in the configuration of the ensemble-- the object itself-- the internal machinery of the thing evolves. 09:18: Kovacs asks, how can it be that if an elementary particle doesn't experience time, that they can still decay? 09:26: ... any particle that can decay, or even oscillate between states, like the electron's ... 09:44: In fact, these guys are really composite particles. 09:58: So when I say that elementary particles don't feel time, that's what I'm talking about. 10:04: ... the time that the electron or quark feels-- is felt by the composite particle, not by their ...
	2016-01-13: When Time Breaks Down 02:04: A particle moving at the speed of light experiences no time. 02:17: And in a sense, the most elementary particles are intrinsically timeless. 02:22: The familiar smooth flow of time only emerges as these particles are bundled into what we think of as matter. 02:34: ... why time depends on motion, which in turn will show us why light speed particles are timeless, and why having mass and experiencing time are ... 03:46: All observers, regardless of their own speed, will report seeing the same speed for any particle of light-- any photon. 05:50: ... a fast moving photon box, we perceive that its internal particles have further to travel to bounce off the walls compared to an identical ... 06:38: ... an atom, that ticking corresponds to interactions between its component particles and fields, in which the internal parts exchange energy, momentum, and ... 07:14: So the confinement of light speed particles gives matter mass. 07:24: But now it looks like this same bundling of light speed particles can also given matter time.
	2016-01-06: The True Nature of Matter and Mass 05:31: Take away the Higgs field, and they are massless speed of light particles. 05:36: ... mass is composed of a combination of intrinsically massless, light-speed particles that are prevented from streaming freely through the universe, as well ... 05:52: Is it just the result of massless particles and fields bumping and sloshing around inside things resisting acceleration? 07:39: So confined massless particles generate a very real gravitational field. 07:44: OK, so mass is an emergent property of the interactions of massless particles. 07:51: A single photon experiences no time, nor does any massless particle. 08:18: ... of "Space Time," we talked about how the Higgs field gives elementary particles ... 08:48: It doesn't act like friction, because friction slows down particles. 08:53: The Higgs field doesn't slow particles down. 09:37: It's really the composite particle that has mass.
	2015-12-16: The Higgs Mechanism Explained 00:02: In 2012, a new particle was discovered by the Large Hadron Collider. 00:14: ... that's made of atoms, doesn't come from the mass of the elementary particles. ... 00:41: Now, today I want to talk about this so-called intrinsic mass of the elementary particles. 01:08: Now, QFT describes the fundamental particles as excitations in fields, fields that fill our entire universe. 01:43: ... elementary particle is a vibration in its own field, and these vibrations and fields ... 02:19: As we'll see in the next couple of episodes, this masslessness means that particles should travel only at the speed of light and experience no time. 02:29: But these particles are distinctly not timeless. 04:09: It actually cares whether a particle has left or right-handed chirality. 05:34: ... poor electron is bombarded by a flow of particles into and out of the Higgs field from all directions, giving and taking ... 06:32: This particle actually has nothing to do with giving anything mass. 06:36: However, if we observe the particle, then it means the field also exists. 06:50: ... 2012, the LHC spotted the debris produced by the decay of an unknown particle, and those decay products are consistent with the disintegration of the ...
	2015-12-09: How to Build a Black Hole 03:41: And by thing, I mean fermion, the particle type comprising all regular matter. 04:32: ... the degeneracy pressure, resulting from particles not having anywhere else to collapse into, is incredibly strong-- strong ... 05:25: Certain numerical properties that you can assign to a particle exist in a wave of varying degrees of maybe. 05:46: Location remains a possibility cloud until the neutron interacts with another particle, at which point, its location is resolved.
	2015-11-05: Why Haven't We Found Alien Life? 11:14: ... you'd see nothing unless it stopped, in which case all the photons and particles that are captured on its journey would blast you into ...
	2015-10-15: 5 REAL Possibilities for Interstellar Travel 04:50: When matter meets it's antimatter counterpart, both particles are annihilated, liberating most of the rest mass as energy. 05:09: We can make in particle accelerators but it's slow and hellishly expensive. 12:04: ... you collapse the way function of one entangled particle, your choice of measurement affects the state of its entangled partner ...
	2015-10-07: The Speed of Light is NOT About Light 08:53: Because of this, it's the only speed that any massless particle can travel. 09:56: There is only massless particles traveling at infinite speed. 11:17: RedomaxRedomax asks what you would see if you traveled 18 times the distance to the particle horizon to come back to where you started. 11:26: ... that number, 18 times the particle horizon, only applies if the universe has positive curvature, making it ...
	2015-09-30: What Happens At The Edge Of The Universe? 01:47: We call this the particle horizon of the universe. 01:56: Anything inside the particle horizon is referred to as the known universe. 02:33: To travel to the particle horizon, we need to move through expanding space. 03:33: The event horizon of the universe is actually closer to us than the particle horizon. 04:22: But for now, let's just assume we have a nice Alcubierre-class warp-ship and we burn the mass energy of entire stars to chase the particle horizon. 04:36: Remember, the particle horizon is just defined by the limit of our current view. 04:43: Wait a minute, and my particle horizon expands. 04:46: Travel to the particle horizon instantaneously and you'll see the Milky Way as a cute baby CMB blob on your new particle horizon. 05:37: So if it's true, what happens if you cross the particle horizon? 06:46: ... you'd need to travel an absolute minimum of 18 times the distance to the particle horizon to get back to where you started, assuming expansion froze for ... 09:16: ... informs us that upon winning a Nobel Prize for discovering dark matter particles, he or she would spend all of the prize money on Phoenix ...
	2015-09-23: Does Dark Matter BREAK Physics? 01:33: One, best case scenario, it comes from particles that we've already discovered, just in a form that's very difficult to detect. 01:41: Two, not so great, dark matter is a type of particle that's beyond our current understanding of particle physics. 02:02: The standard model of particle physics is basically the periodic table of known fundamental particles and fields. 03:10: Either particle physics is wrong, or at least horribly incomplete, in that we're missing 80% to 90% of the mass in the universe, or Einstein is wrong. 04:39: They either need some serious fine-tuning or you have to add back in some actual dark matter particles, which kind of defeats the purpose. 05:08: ... if dark matter is an unseen particle, and it's the type of particle we think it might be, then that dark ... 05:29: This tells us that matter is a real particle, not just broken gravity. 05:35: Dark matter exists and it represents, if not broken, at least incomplete particle physics. 06:23: And even then, galaxies could only have formed if dark matter particles are cold, massive, and weakly interacting. 06:30: Weakly interacting massive particles, WIMPs, actually refers to a specific and popular contender for dark matter. 06:37: WIMPs are a family of particles that may arise out of supersymmetry. 06:41: This is a funky extension to the standard model of particle physics. 06:46: ... the existence of a set of counterparts to the familiar standard model particles, but that are hundreds of times more ... 07:10: But it's all mathematical fantasy until we detect the particle. 07:14: ... fall-out between the unthinkably rare collisions between a dark matter particle and an atomic ... 07:22: We also watch the heavens for the equally elusive gamma radiation produced when dark matter particles annihilate each other out in space. 07:36: ... I'll report any previously undiscovered dark matter particles on the next episode of "SpaceTime." Last time on "SpaceTime," we talked ...
	2015-08-27: Watch THIS! (New Host + Challenge Winners) 00:03: Which of two particles, one orbiting around the outside of a planet and one going straight through the middle, reaches the other side first? 00:15: ... challenge was getting an expression for the gravitational force on the particle that's falling through the planet when it's a distance r from the center ... 00:30: Now there's another force that comes up in elementary physics that's also proportional to the distance of a particle from an equilibrium point. 00:50: ... and figure out an expression for the period of oscillation of a particle falling through a ... 01:09: ... said, you can also work out an expression for the orbital period of a particle moving under the planet's gravity in a circular orbit right at the ... 01:18: ... to the expression that you get for the oscillatory period of a particle going through the center, you find that algebraically, they're ... 01:32: But nonetheless, it means that the half periods are also the same, and it turns out that the particles tie.
	2015-08-19: Do Events Inside Black Holes Happen? 04:13: ... the way, for every particle that enters the black hole, some event on its world line is always the ...
	2015-08-12: Challenge: Which Particle Wins This Race? 00:46: Suppose that a particle is orbiting the planet right at the surface. 00:59: ... gravity, you can work out an expression for the orbital speed of this particle in terms of the mass and radius of the planet, or in terms of the ... 01:12: ... that in mind, and now imagine a second particle that we release from rest at the planet's surface and that we allow to ... 01:26: But I think it's easier to pretend that the planet is a uniformly dense fluid, and that this particle can pass through that fluid without friction. 01:37: At the same time that the orbiting particle passes this point, let's release the second particle from rest from exactly the same height. 01:56: When the second particle is inside the planet, how do you calculate the gravitational force on it? 02:15: ... any given location inside the planet, the particle will feel only the gravitational force from whatever mass is closer to ... 02:26: ... you should be able to get a formula for the gravitational force on the particle when it's a distance little r from the center of the ... 02:40: ... expression for the gravitational force on the second particle when it's inside the planet should algebraically resemble a familiar ... 02:50: ... is actually the key to figuring out the travel time of the second particle without using ... 03:04: The answer to which particle wins the race comes out the same regardless of the mass and radius of the planet, or of the masses of the two particles. 04:13: ... if the particles depart simultaneously as measured by the clock at one end of the planet, ...
	2015-08-05: What Physics Teachers Get Wrong About Tides! 10:09: ... field theory, forces are described as being mediated by some kind of particle like electromagnetism by the photons, strong nuclear forces by the ...
	2015-05-20: The Real Meaning of E=mc² 04:10: All the energy in sunlight came at the expense of other energy, kinetic and potential energy, of the particles that make up the sun. 04:25: Those 4 billion kilograms that the sun loses every second is really a reduction in the kinetic and potential energies of its constituent particles. 04:32: What we've been weighing is the energies of the particles in objects all along. 06:33: They're made of particles called quarks, whose combine mass is about 2,000 to 3,000 times smaller than a proton's or neutron's mass. 06:57: At least in the standard model of particle physics, they're not made up of smaller parts, so where does their mass come from?
	2015-04-22: Are Space and Time An Illusion? 01:01: Suppose two observers are moving relative to each other, and particles count as observers.
	2015-04-09: How to Weigh a Fart 00:20: ... the mass of the fart once you know the average molecular mass of a fart particle. ...
	2015-04-08: Could You Fart Your Way to the Moon? 01:21: ... its temperature and causing it to expand until it becomes a gas of particles bouncing off the walls of the combustion ... 01:31: Particles strike the lateral sides equally often, so there's no net push sideways. 01:35: ... along the longitudinal axis, there's only one wall to strike, and the particles push the rocket forward as they ricochet and escape out the open ...
	2015-03-25: Cosmic Microwave Background Explained 02:12: In fact, it's called a thermal spectrum because the light is generated by the random motions of particles in the material. 03:00: During that era, a supercharged particle with a temperature of several thousand degrees permeated all of space.
	2015-03-18: Can A Starfox Barrel Roll Work In Space? 08:10: Physicists have considered this possibility, and if it were likely, it probably would have occurred in particle accelerators already.

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