
20221026: Why Did Quantum Entanglement Win the Nobel Prize in Physics?
 08:16: But in Clauser’s experiment, the polarizers were fixed in position through the whole experiment.
 16:44: ... themselves, the ones that propelled these craft to their position as antennae, which has got to ...


20221012: The REAL Possibility of Mapping Alien Planets!
 10:07: ... pearl learn, which will be following in about a years time. And improved positioning and observing strategies will flow down the string of ...


20220928: Why Is 1/137 One of the Greatest Unsolved Problems In Physics?
 05:34: Those probabilities depend on many things, like the particles’ positions and momenta, spins, charges, masses, etc.
 11:33: ... Constant is the relationship between the uncertainty in measuring position and ...


20220824: What Makes The Strong Force Strong?
 13:40: The position of each object in the hexagon tells you how much they have of a certain kind of quark, a certain color charge, or actual color.


20220720: What If We Live in a Superdeterministic Universe?
 08:34: ... of Bob’s location should have been able to influence what happens at his position. ...


20220630: Could We Decode Alien Physics?
 06:55: ... of all particles with quantum spin. If we build the device with positions that are spinning the wrong way then, I dunno, maybe ...


20220601: What If Physics IS NOT Describing Reality?
 08:49: ... that the product of the measurement error in a particle’s position and momentum has to be greater than the Planck constant divided by ...


20220525: The Evolution of the Modern Milky Way Galaxy
 01:41: ... night on Las Campanas, enormous surveys have tracked the positions and motions of more than a billion Milky Way stars. We’re now ...
 06:57: ... because of the satellite’s incredible ability to pinpoint stellar positions. That enables the telescope to detect tiny motions, which in turn ...


20220330: Could The Universe Be Inside A Black Hole?
 04:13: ... path through the ground that could have brought the ball to its current position. ...


20220323: Where Is The Center of The Universe?
 01:06: ... principle are actual laws of physics  they’re philosophical positions  guiding principles that so far have not led us ...


20220308: Is the Proxima System Our Best Hope For Another Earth?
 00:11: He made careful note of the position of a bright star that hung just above the southern horizon.
 12:50: ... been enough material so close to the star for it to have formed in that position. ...


20220216: Is The Wave Function The Building Block of Reality?
 13:19: ... real? Or is it a statistical or subjective fiction? Did I measure position precisely or was it momentum? Who put my cat in that funny box, and why ...


20220210: The Nature of Space and Time AMA
 00:03: ... of stages okay the pages of the flip book in which the puzzles positions are updated due to due to all of our beautiful newtonian mechanics ...


20220119: How To Build The Universe in a Computer
 03:06: And then to solve those equations to find their positions at any time in the future.
 06:16: It works like this: you start with a volume full of particles, each with its starting position and velocity.
 11:13: ... in a typical simulation, which just tracks particle positions and ...


20220112: How To Simulate The Universe With DFT
 06:59: ... mechanics contains nonlocal correlations which arise because the position of one quantum particle can restrict the set of possible positions for ...
 09:59: ... complicated, the properties of that system are uniquely determined by position density of those ...
 10:11: ... position density  or more commonly the charge density  is just a tiny fragment ...


20211210: 2021 End of Year AMA!
 00:02: ... heisenberg uncertainty principle if a particle has perfectly defined position perfectly defined momentum it has perfectly undefined position so it ...


20211117: 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.


20211102: Is ACTION The Most Fundamental Property in Physics?
 01:22: ... on each body at each time, which lets you calculate its exact vector positions, velocities, and accelerations at each ...
 06:47: ... run at different rates depending on things like relative speed and position in a gravitational field. Proper time is the time that an object will ...
 08:39: ... probable than others. The particle then appears to randomly select a position from that ...
 12:16: ... configuration space could mean phase space  the space of possible positions and momenta  or it could be more general state space, representing all ...


20211020: 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: ... particle moving in free space does have a range of possible positions defined by the spread of its position wavefunction, so ...


20211013: New Results in Quantum Tunneling vs. The Speed of Light
 02:35: Between observations, quantum particles don’t have well defined properties  and that includes their positions.
 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.


20210921: How Electron Spin Makes Matter Possible
 00:26: ... an electron around twice  720 degrees  to get it back to its starting position. They are, we say, spin½  because one normal rotation only gets you ...
 04:43: ... case we can do another experiment. What happens if the ends exchange positions? If we’re careful again not to rotate either end with respect to each ...
 05:59: ... property being observed. For example, the wavefunction representing the position of a particle can look like a sine wave moving through space. If you ...


20210818: How Vacuum Decay Would Destroy The Universe
 02:18: ... deformed ring, a quantum field wants to return to its equilibrium position. That position is the field value where the energy is minimized. ...


20210810: How to Communicate Across the Quantum Multiverse
 00:53: ... complex bath of density fluctuations. A snapshot of particle positions in the room would reveal a hopeless scramble. And yet somehow your ear ...
 07:14: ... to the wavefunction. The normal linear observables are things like position, momentum, spin  the physical stuff that makes up our world. Extra ...


20210721: How Magnetism Shapes The Universe
 15:28: ... of photon number we get countably infinite splits, and for particle position it’s uncountably infinite splits per ...
 15:58: For example, particle position wavefunction is typically a smooth distribution of possible locations  some more probable than others.


20210713: Where Are The Worlds In Many Worlds?
 04:23: ... particle position and momentum and orientation is chosen from a vast array of ...
 04:54: ... example of this behavior is in the doubleslit experiment, where the position wavefunction of an electron passes through two gaps in a screen and then ...
 10:19: Ultimately your body’s position wavefunction splits  in one version you move left, in the other you move right.
 11:02: Well, sort of  in the sense that the position wavefunctions of the two yous can be mapped to these spatial locations.


20210707: Electrons DO NOT Spin
 10:30: A particle's momentum is fundamentally connected to its position.
 10:33: ... conservation of momentum. For related reasons in quantum mechanics position and momentum are conjugate ...
 10:58: If position is the companion variable of momentum, what's the companion of angular momentum?
 11:05: Well it's angular position. In other words the orientation of the particle.


20210623: How Quantum Entanglement Creates Entropy
 00:27: ... entropy always increases holds, I think, the supreme position among the laws of Nature... if your theory is found to be ...
 02:48: ... in a corner of the room for example, then you know more about the positions of the individual particles  they’re all in the ...
 03:45: ... particles are bunched up in the corner then measuring their exact positions gets you some information. But if you measure their ...
 17:55: ... the episode. When using the Heisenberg microscope to measure position, I said that the uncertainty in the final momentum of ...


20210616: Can Space Be Infinitely Divided?
 04:30: ... object, and replace wavelength with uncertainty in its position. Rearrange and voila, Heisenberg. Or close enough  A ...
 04:49: ... previously. It also applies to other pairs of variables besides position and ...
 08:37: ... light. Imagine we want to precisely define the position of an elementary particle  let’s say an electron. To define its ...


20210525: What If (Tiny) Black Holes Are Everywhere?
 11:34: verus our partially facetious mantra that it's never aliens. I want to clarify my position on this.


20210519: 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.
 02:47: ... to measure the position more precisely, you would need a higher energy photon, which would kick ...
 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 we’re ...
 06:11: Phase refers to the relative positions of the peaks and troughs of the waves.
 06:56: In this case, the complementary variables in question are not position and momentum, but rather phase and amplitude.
 08:43: Those outgoing photons have entangled phases  the relative positions of their peaks and troughs are correlated.


20210421: The NEW Warp Drive Possibilities
 16:40: Actually, in quantum mechanics, velocity isn’t just change in position with time.
 16:45: Momentum, which incorporates velocity, is as fundamental as position.


20210323: Zeno's Paradox & The Quantum Zeno Effect
 02:04: In this case let’s say our quantum arrow’s position is quantized  it can exist only at the start and end of its path, but not in between.
 02:58: ... arrow exists as just the distribution of probability amplitudes of its position; its wavefunction is spread between the start and end of the ...
 03:47: ... you observe the arrow now, most likely it’ll “collapse” to the starting position, but there’s a small chance it would suddenly appear at the final state  ...
 04:28: Every observation you make of the arrow collapses its wavefunction into one of its possible positions  start or end.
 10:09: We would say that the wavefunction for different electron states or quantum arrow positions are in phase with each other, or “coherent”.
 11:18: But in this case, you’re not forcing the wavefunction to collapse back to its starting position through the power of observation.
 11:48: And then you enter the world of of the possible outcome states  again, most likely the starting position.


20210316: The NEW Crisis in Cosmology
 08:03: ... blurring effect of Earth’s atmosphere it’s possible to make better position measurements. The Hubble Space Telescope has done great ...


20210309: How Does Gravity Affect Light?
 11:43: ... enabled him to measure the slight offset in the apparent positions of stars around the sun, due to their light rays being “refracted” in ...


20210224: Does Time Cause Gravity?
 00:27: Our GPS satellites tick faster by a factor of 1inabillion  enough to thrown their position accuracy off by 11km per day.
 07:11: ... actually, nothing truly occupies only a single, perfectly defined position in space  quantum uncertainty means that everything is always at ...


20210217: Gravitational Wave Background Discovered?
 00:00: ... pattern to the lag experienced by pulsar signals as a function of their position it's the socalled antenna pattern a gravitational wave coming from here ...


20210126: Is Dark Matter Made of Particles?
 14:52: The shockwave hits the base of the ladder at the same position in the barn from either the ladder or the barn’s point of view.


20201215: The Supernova At The End of Time
 08:14: Suddenly it’ll find itself one row over  teleported due to fundamental quantum uncertainty in its position.
 15:25: ... in the double slit experiment, because after the measurement of particle position is made, the state of the wavefunction before that measurement is ...


20201208: Why Do You Remember The Past But Not The Future?
 03:15: ...  well, any omniscient supergenius physicist could measure the exact positions and velocities of every particle comprising the asteroid and calculate ...


20201118: The Arrow of Time and How to Reverse It
 02:31: ... motion combined with Coulomb’s law perfectly describe how the electrons’ positions change over time. But if we flip this diagram on its head  reverse the ...
 04:50: ... The 2nd law just tells us how a system is likely to change from a position of low entropy  in either time direction. To understand why one ...
 07:17: ... We know that entropy was lower in the past because we can trace the positions of galaxies and the particles that comprise them back and calculate a ...
 12:35: ... weren’t mentioned, given that they define the the philosophical positions we discussed. Well I wanted to make sure it was more of a physics ...


20201111: Can Free Will be Saved in a Deterministic Universe?
 00:57: ... had perfect knowledge of the current state of the universe, like the positions and velocities of all particles, and perfect knowledge of the laws of ...
 01:47: ... reality, but we do wanna look at the most popular way this question is positioned in physics, the idea that determinism negates free ...


20201104: Electroweak Theory and the Origin of the Fundamental Forces
 04:50: ... of certain outcomes being measured for observables like particle position and ...
 05:07: Like all waves, the wavefunction has a phase  the current position of the peaks and troughs.


20201013: Do the Past and Future Exist?
 01:27: ... of the deterministic universe  the idea that, by knowing the current position and velocity of every particle in the universe, as well as the forces ...


20200810: Theory of Everything Controversies: Livestream
 00:00: ... that i had before i didn't realize that the community wasn't in a position to offer it anymore so having effectively lied and failed uh to say ...


20200615: What Happens After the Universe Ends?
 05:03: If I draw the line of constant time for all possible travelers passing by my position, I get these nested curves  hyperbolas.


20200527: Does Gravity Require Extra Dimensions?
 10:15: ... geometry of modern devices allow more precise positioning between the test masses, and the displacement of the masses is measured ...


20200518: Mapping the Multiverse
 03:33: Your past light cone shows you the parts of the multiverse that you can see, because light has had time to reach your position from those parts.
 14:25: Elliot Heath wonders if we are now in a similar position to the end of the 19th century now  in that we might be on the cusp of massive change.


20200511: How Luminiferous Aether Led to Relativity
 04:06: ... he also studies his own urine isn’t clear. But he eventually came to the position that Huygen’s luminiferous aether was bunk. He reasoned that if any ...


20200407: How We Know The Earth Is Ancient
 04:32: ... now swear by the Copernican principle  Earth is not in a privileged position in the universe, and so the laws of physics work the same everywhere. ...


20200316: 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 come back ...
 10:14: ... only see the crude, macroscopic characteristics of the device  like the position of a pointer on a ...
 12:33: ... Schrodinger’s Cat? Well an important example of a pointer state is the position of a particle. Most quantum interactions depend heavily on the relative ...
 13:47: ... propagating pointer states. The observable qualities of reality  object positions, feline mortality statuses, even the results of quantum measurements  do ...


20200224: How Decoherence Splits The Quantum Multiverse
 03:38: ... a probability wave that ultimately “collapses” to leave it as a single position on a screen, and multiple independent particles then land in these bands ...


20200203: Are there Infinite Versions of You?
 03:19: ... universe, the starting conditions in any given region  like positions, velocities, etc of all particles  perfectly determines the future ...


20200120: Solving the Three Body Problem
 00:20: ... a perfectly tuned machine of clockwork predictability. Given the current positions and velocities of the bodies of the solar system, Newton’s equations ...
 01:24: ... into that equation and its solved. Those numbers are the starting positions and velocities of your gravitating bodies, plus a value for ...
 10:30: ... what we call a phase space  a space of possible arrangements of position and velocity. Well, for a pseudorandom system, statistical mechanics ...


20191118: Can You Observe a Typical Universe?
 00:34: ... presented his model of the solar system which demoted the Earth from its position at the center of the universe into just one of several planets orbiting ...
 01:00: ... notion that we occupy neither a central nor privileged position in the universe is called the Copernican principle after the guy who ...
 01:38: It states that we don’t occupy a central, privileged position, but that’s only half true.


20191015: Loop Quantum Gravity Explained
 03:33: ... classical physics, we have variables like position, time, momentum, energy  mathematical expressions that represent the ...
 03:45: Some of these  say, position and time  also form our background coordinate system.
 04:06: In the first formulations of quantum mechanics, that wavefunction describes the distribution of possible positions and momenta of, say, a particle.
 04:16: These can then be resolved into concrete, measured values by acting on the wavefunction with socalled position and momentum operators.
 04:30: ... all, the position and momentum of quantum mechanics literally describes location on a ...
 05:19: ... let you calculate changing properties of a particle  like its position or momentum  relative to the background coordinate ...
 05:35: So maybe instead of thinking about the quantum fuzziness of position and momentum we can think about the quantum fuzziness of the metric itself.
 06:37: You can also imagine analogies of the position and momentum in this space of metrics.


20190826: How To Become an Astrophysicist + Challenge Question!
 00:00: ... a nice job working with the Gemini observatories This was a postdoctoral position a postdoc which means a shortterm job typically two to four years Most ...
 03:35: ... numbers are against us There are way more astro postdocs than permanent positions whether at universities Observatories NASA or private foundations in my ...
 08:59: ... situation as it is the odds are stacked against getting that permanent position So you better love the journey and all the awesome science you get to do ...


20190812: Exploring Arecibo in VR 180
 03:24: ... scared Look below that's the azimuth arm It can maneuver on two axes to position the receiver within one millimeter precision of whatever Astronomical ...


20190725: Deciphering The Vast Scale of the Universe
 07:10: Every dot we see is a known galaxy, it’s position, velocity, and even stellar content measured and cataloged.


20190715: The Quantum Internet
 08:29: Just position repeaters along the quantum channel between Bill and Ted.


20190509: Why Quantum Computing Requires Quantum Cryptography
 04:38: ... the values of certain pairs of properties – for example, a particle’s position and ...


20190410: The Holographic Universe Explained
 17:21: Realmaml summarizes my position well: Chronicals is the third best Riddick movie but it is still better than any Marvel movie.


20190220: Secrets of the Cosmic Microwave Background
 07:42: ... mass then it falls and then bounces up again always back to the original position if it's a perfect spring But the heavier the mass the further it will ...


20190207: Sound Waves from the Beginning of Time
 09:08: ... gives distance. And with careful measurements of galaxies' positions on the sky, a redshift survey can produce a threedimensional atlas of ...


20190130: Perpetual Motion From Negative Mass?
 06:56: At first glance this tells us that any object, no matter its mass, will follow the geodesic determined by its starting position and velocity.
 07:40: But those trajectories only depend on the active gravitational mass of the central object, and on the velocity and starting position of the apple.


20181212: Quantum Physics in a Mirror Universe
 00:02: ... symmetry in the case of those other symmetries I mentioned the shift in position time or phase can be by any amount small or large these are continuous ...


20181031: Are Virtual Particles A New Layer of Reality?
 07:29: The Heisenberg uncertainty principle tells us that the perfectly defined momenta of virtual particles means completely undefined position.


20181025: Will We Ever Find Alien Life?
 05:47: ... star has a binary companion which may have caused a wobble in the star's position and that, in turn, may have messed with the star's parallax distance ...


20180920: Quantum Gravity and the Hardest Problem in Physics
 05:32: The more precisely you want to measure position, the higher the energy of that interaction.
 05:57: ... turns out that to measure a position to an accuracy better than a Planck length around 10 to the power of ...
 06:28: Steady viewers will remember that the uncertainty principle talks about the tradeoff between position and momentum.
 07:01: ... know that for a particle to have a highly defined location, its position wave function needs to be constructed from a wide range of momentum wave ...
 07:20: So position can be defined to within a Planck length.
 07:33: Particles whose positions are defined within a Planck length can spontaneously become black holes.


20180912: How Much Information is in the Universe?
 04:18: Particles have more information than just their position.
 04:21: ... use the number of grid points in a quantum phase space, which includes position, but also other degrees of freedom, like momentum, spin direction, et ...


20180905: The Black Hole Entropy Enigma
 03:46: ... to perfectly describe the system's internal state like all the particle positions, velocities, et ...


20180823: How Will the Universe End?
 16:03: If we know with 100% certainty the position of an electron, then the size of its quantum wave function becomes zero.


20180718: The Misunderstood Nature of Entropy
 04:22: By configuration, I mean the exact arrangement, of positions, velocities, et cetera of all microscopic particles.
 06:32: ... been talking a lot about particle position, but really, that Go board is an analogy for all possible combinations of ...
 06:49: And instead of particles being distributed through position space, a microstate is really defined by how energy is distributed through phase space.


20180711: Quantum Invariance & The Origin of The Standard Model
 02:49: The best we can do is make a measurement of physical observables, like position or momentum.
 03:02: In this episode, we'll be talking about the position wave function.
 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: ... can shift phase 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 ...
 05:16: This position dependent phase shift is called a local phase shift, instead of a global phase shift.
 05:56: That shouldn't change our probabilities for the positions of the particles, but what about observables besides positions?


20180620: The Black Hole Information Paradox
 08:11: ... are certain pairs of quantumobservable complimentary observables, like position and momentum, that can't both be perfectly measured at the same ...


20180613: What Survives Inside A Black Hole?
 12:10: We said that there's always a 100% chance, for example, that the particle position always has some value.


20180523: Why Quantum Information is Never Destroyed
 05:10: ... will be found in this or that location if we were to try to measure its position. ...
 06:27: In the case of particle position, probability of adding to 1 just means that the particle is definitely somewhere.


20180516: Noether's Theorem and The Symmetries of Reality
 08:53: During her life, she was repeatedly refused any paid academic position due to her gender, until late in her career.
 09:01: ... said in her memorial address, I was ashamed to occupy such a preferred position beside her whom I knew to be my superior as a mathematician in many ...
 10:39: But Gaia is really optimized for extreme astrometry phenomenally accurate position data that actually allows measurements of velocities.


20180509: How Gaia Changed Astronomy Forever
 00:46: Gaia blows this out of the water, with positions, colors, and brightnesses of nearly 1.7 billion stars.
 01:04: Gaia can pin down a star's position to the equivalent of a human hairs width at 1,000 kilometers.
 01:47: As it traverses its orbit, Gaia detects the tiny shifts in the positions of stars due to this motion, a phenomenon called stellar parallax.
 02:07: Coupled with its incredible position measurements, this enables Gaia to measure distances to stars as far away as the galactic center.
 04:36: ... most telescopes, but Gaia's incredible astrometry revealed the change in positions of stars over the five years of its ...
 05:07: ... putting such complete velocity measurements together with our position data, it's now possible to model the dynamics of the Milky Way with ...
 05:53: ... the current velocities and positions of the stars, we can actually wind the clocks backwards and forwards, to ...
 07:51: Gaia has also mapped the position and brightnesses of over half a million quasars the cause of distant active galaxies.


20180315: Hawking Radiation
 10:32: ... example, uncertainty in position or momentum can lead to particle pairs that we'll want in the same ...


20180228: The Trebuchet Challenge
 02:35: Kinetic and potential energy are defined as combinations of more basic quantities, for example, position, velocity, and mass.


20180131: Kronos: Devourer Of Worlds
 02:38: ... Space Agency in 2013 on a fiveyear mission to measure the precise positions and distances of about a billion objects in the Milky ...


20180117: Horizon Radiation
 02:45: That oscillation can be distributed over some region of space, representing the possible positions of the particle.
 05:35: Quantum wave functions and quantum fields can be described in terms of variation with position or variations with momentum.
 05:44: So instead of writing the field as having a value at every possible position in space, we can write it as having a value for every possible momentum.
 06:13: ... in momentum space, that single, perfectly localized position oscillation can also be described as an infinite number of unlocalized ...


20171206: Understanding the Uncertainty Principle with Quantum Fourier Series
 01:40: The uncertainty principle is most often expressed in terms of position and momentum.
 01:44: We cannot simultaneously know both position and momentum for a quantum system with absolute precision.
 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.
 06:25: It only changes with position in space.
 06:33: So position, rather than time, becomes the first of our Fourier pair.
 07:08: ... call matter waves wave functions, and we can describe them in terms of position or momentum, just as a traveling sound wave can be expressed in terms of ...
 07:29: ... of it as the particle being smeared over possible positions or as a combination of many momenta with accompanying intensities, in ...
 07:41: And of course, this means that position and momentum have the same kind of uncertainty relation that time and frequency had in the sound wave.
 07:50: But what does it even mean for a particle to be comprised of waves of many different positions or momenta?
 08:12: ... we're expressing the wave function in terms of position, then applying the Born rule tells us how likely we are to find the ...
 08:22: Or put another way, the range of positions in which the particle is likely to be located were we to look.
 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.
 08:48: ... resulting particle wave packet, now constrained in position, can only be described as a superposition of waves with a very large ...
 09:06: ... more precisely we try to measure position, the narrower we make its position wave function, and so the less certain ...
 09:22: ... we increase our certainty of the position of a particle by narrowing the slit, we also increase the uncertainty of ...
 09:55: Waves that can be represented in terms of either position or momentum.
 10:18: Well, the key to understanding these things is to be able to switch between thinking about quantum fields in terms of position versus momentum.
 10:45: The uncertainty principle, therefore, tells us that they must be completely unconstrained in position.


20171019: The Nature of Nothing
 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.
 03:39: We saw that it's impossible to simultaneously fix position and momentum.


20171011: Absolute Cold
 04:52: Well, its position relative to its neighbors would be fixed, and its momentum would be 0.
 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.


20170802: Dark Flow
 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.


20170707: Feynman's Infinite Quantum Paths
 01:20: It's initial and final positions are known, but what path does it take in between?


20170628: The First Quantum Field Theory
 02:22: ... string is displaced by some distance from its relaxed or equilibrium position, and that displacement changes over time as the string oscillates back ...
 05:52: It follows the changing position and momentum and generally the physical quantum state of every individual particle but that's extremely inefficient.
 07:12: Instead of quantizing particles' physical properties like position and momentum, as did Schrodinger, Dirac quantized the electromagnetic field itself.
 07:43: So Dirac described a space of quantum states, including position and momentum/frequency, like an infinite array of springs.


20170621: AntiMatter and Quantum Relativity
 02:21: ... describes particles as simple wave functions, distributions of possible positions and momenta that have no internal ...


20170517: Martian Evolution
 13:15: ... measured the very slight offset in the positions of stars around the limb, the edge, of the sun due to the powers of ...
 13:25: The difference in position is something like 1.7 arcseconds.
 13:28: So you need a position precision significantly better than that.
 13:40: ... need to compare the positions of stars on either side of the sun during the eclipse and then several ...
 14:36: And that's from one position on the Earth.


20170503: Are We Living in an Ancestor Simulation? ft. Neil deGrasse Tyson
 15:57: ... principle, a perfect set of particle positions and velocities could be found such that the subsequent series of ...


20170426: Are You a Boltzmann Brain?
 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.
 03:18: Entropy increases because particle positions and velocities get randomized over time.


20170222: The Eye of Sauron Reveals a Forming Solar System!
 08:07: ... system and flung the gas giants into their current, more spread out positions. ...


20170119: The Phantom Singularity
 16:22: ... differentials and large magnetic fields around a very sensitive position measuring ...


20161208: What Happens at the Event Horizon?
 06:16: Weirdly, the lines of constant position and constant time switch.
 15:11: ... theory states that the particle riding the wave does have a definite position at all times and that position defines its future ...
 15:22: So if you know the position perfectly and you know the wave function, you can perfectly predict future locations.
 15:30: However, you can't perfectly measure a particle position without changing it slightly in ways that themselves aren't perfectly predictable.
 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.


20161130: Pilot Wave Theory and Quantum Realism
 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 future ...
 05:01: Apparent randomness arises because we can't ever have a perfect measurement of initial position, velocity, or other properties.


20160907: Is There a Fifth Fundamental Force? + Quantum Eraser Answer
 05:49: The photon positions are decided and presumably those patterns are embedded in the distribution.


20160810: How the Quantum Eraser Rewrites the Past
 05:54: And then later, its untangled partner reaches detector A or B, and somehow retroactively influences the previous landing position.


20160727: The Quantum Experiment that Broke Reality
 03:25: ... spot and so they appear to be acting like particles of welldetermined position. ...
 04:07: No, the pattern emerges in the distribution of final positions of many completely unrelated photons.
 05:37: It looks like a wave of possible undefined positions that at some point, for some reason, resolves itself into a single certain position.
 05:47: We also saw this waviness in position when we talked about quantum tunneling.
 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 ...
 09:08: There's an interaction between possible realities that is seen in the distribution of final positions in the interference pattern.


20160706: Juno to Reveal Jupiter's Violent Past
 00:50: In fact, its effect during the first billion years of the solar system's formation defines the positions of all planetary orbits.
 05:46: ... have slowly migrated back outwards until Jupiter reached its current position. ...
 06:03: Well, computer simulations show that something like this may be expected given the right starting position for Jupiter.
 11:54: ... closing the remaining gap every time he reaches the tortoise's last position. ...


20160629: Nuclear Physics Challenge
 00:24: These matter waves don't have perfectlydefined positions, but rather, occupy a range of possible positions.
 00:31: One consequence of this uncertainty in position is the phenomenon of quantum tunneling.


20160622: Planck's Constant and The Origin of Quantum Mechanics
 00:44: Run as fast as you like, by the time you reach the tortoise's initial position, it'll have moved forward.
 00:50: Reach that second position, it'll would moved forward again.
 00:53: To overtake a tortoise, you need to travel to its previous position infinite times.
 13:22: ... that produce the same distribution of light seen in the lens, so image positions and ...


20160615: The Strange Universe of Gravitational Lensing
 02:11: ... catch an eclipse of the sun and to measure the tiny change in the position of nearby stars due to the deflection of their light by the sun's ...
 11:07: So some of the language I used to describe the collapse of the wave function and possible positions did echo the Copenhagen interpretation.
 11:28: The idea is that a physical system doesn't have the familiar classical properties like position, momentum, spin, et cetera, until it is observed.
 12:39: ... collapses its wave function into the classical physical properties like position and ...


20160601: Is Quantum Tunneling Faster than Light?
 01:39: It can be described as a wave packet of positioned probability.
 01:46: This de Broglie Wavelength defines how well determined an object's position is.
 01:52: A large wavelength means a highly uncertain position.
 01:57: A small wavelength means a welldefined position.
 03:36: Their positions are not well defined.
 04:19: ... off the wall, the particle will, at the last minute, resolve its position in that unlikely outside bit of its possibility space that looks like ...
 08:39: ... photon, because its wave packet includes that in its range of possible positions. ...


20160127: The Origin of Matter and Time
 01:17: It's just a graph of position in space just one special dimension for simplicity versus position in time.
 02:01: Now, it moves both in space and time, because position is changing.
 02:11: Constant speed equals constant change in position x with time t.
 02:16: The slope tells you how much position is changing for each tick of the clock.


20151209: How to Build a Black Hole
 03:04: For a neutron star, this is the space of both 3D position and 3D momentum.
 04:09: In the case of a neutron star, position momentum phase space is completely full of neutrons.
 06:04: ... uncertainty principle tells us that particular pairs of quantities, position and momentum or time and energy, must, when taken together, contain a ...
 06:27: Its constituent neutrons are about as constrained in position as you can get.
 06:44: To put it another way, the neutrons are packed so close together in position space that their momentum space becomes gigantic.
 07:19: But it doesn't expand in position space.
 07:25: In position space, it actually gets smaller.
 09:13: All position space collapses towards the singularity.


20151125: 100 Years of Relativity + Challenge Winners!
 02:13: ... much mass is needed to accelerate Apophis to get the desired change in position and then the rocket equation to see how much fuel we'll need to achieve ...
 03:41: ... to use one of the basic kinematic equations, the one relating change in position, average acceleration, and time, with a starting velocity of zero in the ...


20151111: Challenge: Can you save Earth from a Killer Asteroid?
 01:14: ... couple of Earth diameters, say 25,000 kilometers, ahead of its expected position by the impact date, then it will miss ...


20151007: The Speed of Light is NOT About Light
 06:00: Under our new transformation, the laws of physics will work the same regardless of position, orientation, or velocity.
 06:17: Position, orientation, and velocity are changing massively.


20150805: What Physics Teachers Get Wrong About Tides!
 13:22: ... same rate everywhere and ask, relative to that clock, are the coordinate positions of two points on Earth's surface ...


20150729: General Relativity & Curved Spacetime Explained!
 00:55: Well, between our gravity illusion episode and your comments, we've seem that Einstein's position seems internally inconsistent.
 02:19: Now for Einstein's position.
 03:18: OK, Einstein's position is that Newton is making the same mistake as the ant.


20150715: Can You Trust Your Eyes in Spacetime?
 06:01: So now, we are finally in a position to state some things that may have seemed visually obvious, but that I don't think really were.
 07:58: ... of tracking changes in the monkey's position on my axis with respect to ticks of my clock that's ordinary ...


20150624: The Calendar, Australia & White Christmas
 01:55: Halfway through that, or after 13,000 years, the summer and winter solstices should end up swapping positions.


20150415: Could NASA Start the Zombie Apocalypse?
 04:06: Since our understanding of the nuances of disease in space is still in its infancy, it's not like anyone was in a position to say its impossible.


20150311: What Will Destroy Planet Earth?
 03:07: All they changed from one initial set up to another was Mercury's current position by about a meter.


20150218: Is It Irrational to Believe in Aliens?
 01:48: Is it impossible to take a rational statistical scientific position on whether or not aliens exist?
