
20221208: How Are Quasiparticles Different From Particles?
 05:16: And we can make another one by making a very different tweak to the local energy in the crystal.
 13:28: ... are magnons  quanta of waves in that lattice, or skyrmions, which are localized, stable topological field configurations sort of like knots  all very ...


20221026: Why Did Quantum Entanglement Win the Nobel Prize in Physics?
 11:49: Bell’s theorem can be used to rule out the existence of local hidden variables.
 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.
 12:09: ... ruled out local hidden variables, but that may mean they ruled out locality rather than hidden ...
 12:18: Any violation of locality still means that some sort of influence travels faster than light  the sort of spookiness that Einstein hated.


20220720: What If We Live in a Superdeterministic Universe?
 00:00: Today we’re going to try to save reality  or at least save realism. Actually just local realism.
 07:24: According to the Bell theorem, any localrealist theory must obey the Bell inequality.
 07:32: So the violation of the inequality could be a violation of realism OR of locality.
 07:40: ... a local realist theory, every point in space and time  every event  can only ...
 07:52: There are ways to save realism in quantum mechanics by crossing Einstein and abandoning locality.
 08:04: On the other hand, Many Worlds interpretation of quantum mechanics saves local realism at the cost of requiring multiple realities.
 08:34: ... travels a 45 degree angle, and so if local realism holds, only events in what we call the past light cone of Bob’s ...
 08:54: That violates local realism.
 09:36: Locality and realism would have been saved if it turned out that the states of the electrons were fixed when their past lightcones overlapped.
 09:52: In Bell’s theorem, his inequality is satisfied in localrealist theories  but there is another condition to the validity of the theorem.
 10:35: It may still be possible to violate Bell’s inequality without saying anything about local realism.
 12:53: ... inequality with extremely high significance, which they claim ensures no localrealist influences could have messed with Alice and Bob’s decisions except in ...
 13:20: That pushed back any possible localrealist influence more than half the age of the universe.
 13:43: ... many Bell tests, cosmic and regular, tell us that either locality or realism are wrong OR there are multiple realities OR the universe ...


20220622: Is Interstellar Travel Impossible?
 06:08: ... cubic centimeter, however the Sun is in an underdense region called the local ...


20220615: Can Wormholes Solve The Black Hole Information Paradox?
 02:43: ... a measure of how much quantum information is not stored locally in the system itself, but rather in whatever it’s entangled ...


20220601: What If Physics IS NOT Describing Reality?
 07:23: ... chose to align it. Our distributed information becomes local to each electron, and in the process appears to force an ...


20220525: The Evolution of the Modern Milky Way Galaxy
 13:17: ... than its meal. That’s going to change with the final merger of our local group of galaxies  when Andromeda and the Milky Way collide. This ...


20220518: What If the Galactic Habitable Zone LIMITS Intelligent Life?
 04:32: ... demonstrated that most stars have planets  at least in the local part of the galaxy. Kepler also revealed that there are ...
 06:56: ... that filled the universe after the Big Bang. As it cooled, our local lump started to pull itself together under its own gravity. ...


20220504: Space DOES NOT Expand Everywhere
 01:24: ... in the mutual gravity of their galaxies, galaxies whirl and collide in local groups and clusters. But if you expand your view to large enough scales, ...


20220427: How the Higgs Mechanism Give Things Mass
 02:31: ... wavefunction from one point in space to the next  local phase  doesn’t affect measurable quantities  only relative phase ...
 03:09: ... that the laws of physics are invariant under changes in local phase. The set transformations that can change local phase ...
 09:34: ... symmetry. Repeating our electromagnetism trick means requiring local U(1) invariance. We need the laws of physics to still make sense ...
 12:59: ... and electromagnetic interactions, so we need simultaneous local U(1) and SU(2) symmetry. Let’s just do U(1) because that ...


20220330: Could The Universe Be Inside A Black Hole?
 06:35: But there’s still an “outside” in which the white hole appears as a bright, localized point in space.


20220323: Where Is The Center of The Universe?
 18:46: So it looks like local interferenced.


20220216: Is The Wave Function The Building Block of Reality?
 08:02: ... theory that inspired many subsequent models, like Continuous Spontaneous Localization. In CSL, physicists imagined that the localizing mechanism was a randomly ...


20220210: The Nature of Space and Time AMA
 00:03: ... of time is entirely defined by the direction of entropy then does a local decrease in entropy does uh a even even if the entire cosmos is ...


20220127: How Does Gravity Escape A Black Hole?
 03:42: ... directly interacting with the Sun itself, it’s interacting only with the local part of the gravitational ...
 07:02: Virtual particles aren’t localized like that.
 11:18: You interact with the local curvature of spacetime, which is produced by the past mass, which from your point of view is on the event horizon.
 16:08: But on small scales, local gravitational influences dominate.


20220112: How To Simulate The Universe With DFT
 07:15: In the Newtonian case, particles only interact locally, and that means the Newtonian equations of motion are what we call separable.


20211229: How to Find ALIEN Dyson Spheres
 11:40: ... or so we’ll either discover one or rule out anything interesting in the local part of the Milky ...


20211220: What Happens If A Black Hole Hits Earth?
 05:13: ... But I do not recommend standing right under a falling black hole  locally the encounter is catastrophic. Which is actually a good thing if you ...


20211117: Are Black Holes Actually Fuzzballs?
 10:37: The resulting fuzzball doesn’t have a local event horizon  in that there’s no single surface of noreturn.


20211020: Will Constructor Theory REWRITE Physics?
 09:04: That entanglement has to be initially induced by a local interaction  the qubits must come into contact.


20210915: Neutron Stars: The Most Extreme Objects in the Universe
 08:15: ... wavefunction is so spread out that it becomes hard to even localize it to being inside a given nucleus. By the time we reach the ...


20210818: How Vacuum Decay Would Destroy The Universe
 05:03: ... prefer to spend its time given the choice. And then there’s another local minimum with a higher energy  what we call that a false ...


20210810: How to Communicate Across the Quantum Multiverse
 11:11: ... wavefunction to a nonlinear field. That field sort of spreads the local information from each branch  each world  through the entire electron ...


20210721: How Magnetism Shapes The Universe
 06:08: These specks tend to align with the local magnetic field of the Galaxy in exactly the same way as our iron filings align around a bar magnet.


20210616: Can Space Be Infinitely Divided?
 00:00: ... Assuming perfect coordination and the ability to localize my palms to the quantum level. 15 halvings gets them to within a ...
 08:37: ... energy induces a process called pair production. The act of localiuzing the electron causes pairs of virtual electrons and ...


20210421: The NEW Warp Drive Possibilities
 00:05: His whole “nothing travels faster than light” rule seems to ensure that exploration of even the local part of our galaxy will be an excruciating slow.


20210316: The NEW Crisis in Cosmology
 08:03: ... satellite, which tracked the motion of 100,000 stars in our local patch of the galaxy But to really nail down the lowest rung of the ...


20210309: How Does Gravity Affect Light?
 09:46: The only thing that’s not relative is the speed of light  everyone observes the same local speed of light  300,000 km/s in a vacuum.
 09:55: But notice that I said LOCAL speed of light  that means everyone measures the same speed of light passing through their own local patch of space.


20210119: Can We Break the Universe?
 07:45: Relativity tells us that there’s not a preferred LOCAL frame of reference.


20201215: The Supernova At The End of Time
 02:54: On one of those planets  the third one out  a steamship is making its slow journey to a place that the local carbon based lifeforms call “England”.


20201118: The Arrow of Time and How to Reverse It
 04:13: ... a statistical effect  it’s possible for small fluctuations to happen, local drops in entropy, but the larger the system the less likely it is for ...


20201104: Electroweak Theory and the Origin of the Fundamental Forces
 05:42: So there we go  we insisted on a symmetry  that the Schrodinger equation is invariant to changes in the local phase of the wavefunction.
 06:20: ... is the magnitude of the wavefunction, and the rotation amount is our local phase ...
 08:50: ... in the Schrodinger equation so that it would no longer be invariant to local phase ...


20200810: Theory of Everything Controversies: Livestream
 00:00: ... do with foundations of quantum mechanics with the notion of space of locality and that the overall set of problems stemming from cosmology the ...


20200720: The Boundary Between Black Holes & Neutron Stars
 12:03: We’re shipping it to you from a little star cluster in Sagittarius  made locally from humanely sourced ogiant star of course.


20200511: How Luminiferous Aether Led to Relativity
 16:14: ... 85 million light years across. That’s about half again the size of the local Virgo supercluster. That's so weird to think about  the most distant ...


20200113: How To Capture Black Holes
 06:15: ... exert a gravitational tug on the surrounding particles. Depending on the local properties of the disk, that can cause the object to either gain or lose ...
 06:53: ... the local properties of a disk will change with the distance from the center. In ...


20190930: How Many Universes Are There?
 14:43: Alexander has been traveling the bubble universes for many years, supporting local youtube space shows where he finds them.


20190819: What Happened Before the Big Bang?
 03:43: Guth's idea is that there's a local minimum in potential energy that allows the inflaton field to get stuck in a false vacuum state.
 04:35: ... idea of slow roll inflation is that the inflaton field isn't stuck at a local minimum in the potential but rather it's on a very weakly sloping ...


20190806: What Caused the Big Bang?
 06:47: For now, let's just go with it. One possibility is that the field could have what we call a local energy minimum.
 06:55: If such a quantum field found itself near that local minimum then it would roll to the bottom and get stuck there.
 07:46: But then, it gets stuck in this local energy minima.
 08:43: Somewhere in the inflating universe, the inflaton field is going to fluctuate to the other side of this local minimum barrier.
 09:07: ... of space adjacent to that point would also be dragged out of the local minimum towards the true vacuum and so the entire inflaton field would ...


20190725: Deciphering The Vast Scale of the Universe
 06:50: As we zoom out, now at several trillion times the speed of light, our local group of galaxies comes into view.
 07:03: That’s the Virgo cluster – the nearest big city, of which our local group is an outlying suburb.


20190617: How Black Holes Kill Galaxies
 01:35: ... directly responsible for the speed of stellar orbits outside their local region Sure, Galaxies and their Black Holes probably grew together but ...
 02:54: ... very first generation of stars they would fall to the centres of their local wispy protor galaxy and when wisps merged their central Black Holes ...


20190410: The Holographic Universe Explained
 06:25: By making this a conformal field theory we’ve added a symmetry –invariance under local changes in scale – also known as Weyl invariance.
 07:15: ... which the rules of physics stay the same, and c) imposes some kind of locality – for example, elements of that number line need to be next to each ...


20190403: The Edge of an Infinite Universe
 07:44: ... represent a universe that is “asymptotically flat” – it may have some local curvature due to gravity of massive objects inside, but at its ...
 11:02: The other feature of a conformal mapping is that shapes are preserved – at least locally.


20190306: The Impossibility of Perpetual Motion Machines
 14:25: Abe Dillon asks whether the "moment" of recombination should depend on the local density.


20181107: Why String Theory is Right
 08:35: ... the Schrodinger equation that fixes these phase differences preserving local phase ...
 11:07: ... as local phase invariance required us to add the electromagnetic field to the ...


20181025: Will We Ever Find Alien Life?
 04:14: Thrillingly, one proposed explanation was an alien mega structure, perhaps a vast fleet of solar collectors built by the local inhabitants.


20180920: Quantum Gravity and the Hardest Problem in Physics
 11:09: The nonrenormalizability of quantized general relativity is connected to the idea that precisely localized particles produce black holes.


20180823: How Will the Universe End?
 03:40: There'll be no evidence of a universe beyond the local galaxy and no evidence that there was ever a Big Bang.


20180711: Quantum Invariance & The Origin of The Standard Model
 05:16: This position dependent phase shift is called a local phase shift, instead of a global phase shift.
 05:21: We'll try this because, well, we already know that the magnitude squared of the wave function should still stay the same under local phase shifts.
 05:38: ... if we do a local phase shift, say, only this point here, only that location changes, as ...
 05:50: If you allow this sort of local phase shift, you can change each point in a different way and really mess up the wave function.
 06:08: Among other things, messing with local phase really screws up our prediction for the particle's momentum.
 06:19: Change the shape of that wave function with local phase shifts and you actually break conservation of momentum.
 06:26: Local phase is not a gauge symmetry of the basic Schrodinger equation.
 06:38: Just for funsies, maybe we can change the Schrodinger equation to find a version that really is invariant to local phase shifts.
 07:06: If we choose this term correctly, it absorbs any local changes we make to the phase.
 07:34: ... we've discovered that the only way for particles to have local phase invariance is for us to introduce a new fundamental field that ...
 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.
 08:48: In this case, the symmetry is local phase invariance and the conserved quantity is electric charge.
 09:41: It turns out that local phase invariance is just the simplest of the larger suite of gauge symmetries of the standard model.


20180613: What Survives Inside A Black Hole?
 09:54: However, there are some important conserved properties that are entirely local.


20180418: Using Stars to See Gravitational Waves
 11:36: But you decrease entropy locally.


20180411: The Physics of Life (ft. It's Okay to be Smart & PBS Eons!)
 06:58: ... this local rise in complexity would all cease when the system reaches thermal ...
 09:39: ... internal entropy than its chaotic surroundings, but the source of that local incidence of low entropy is the streamline flow that it formed ...


20180328: The AndromedaMilky Way Collision
 05:20: They also included the Triangulum, or Pinwheel Galaxy, the thirdlargest member of the Local Group.


20180315: Hawking Radiation
 08:47: Firstly, this radiation is not localized.
 09:17: To them, space is locally flat.


20180117: Horizon Radiation
 04:35: A particle perfectly localized in space a single spring or a single point on the drum skin.
 05:56: So let's take our spatial quantum field our drum skin, with its single, localized particle, and transform to momentum space.
 06:13: ... in momentum space, that single, perfectly localized position oscillation can also be described as an infinite number of ...


20180110: What Do Stars Sound Like?
 06:58: The Doppler shifts due to local gas moving are completely washed out.
 07:58: But at least for the sun, it's possible to learn about current local events that are hidden from our view.


20171213: The Origin of 'Oumuamua, Our First Interstellar Visitor
 11:23: Actually, I think you need an infinite series of PBS Space Time to get a Space Time localization of PBS infinite series.


20171206: Understanding the Uncertainty Principle with Quantum Fourier Series
 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.
 10:26: ... a single particle, a quantum field vibration, perfectly localized at one spot in space, can so be described as infinite oscillations in ...
 10:51: So a perfectly specially localized particle is equally an infinite number of momentum particles that themselves occupy all locations in the universe.


20170802: Dark Flow
 07:26: Since 1973, we've noticed that galaxies in the local part of the universe seem to be drawn in that direction due to an unseen gravitational influence.


20170621: AntiMatter and Quantum Relativity
 14:02: ... vacuum field can have one or more local minima, where the vacuum energy can come to a rest in an eternally ...


20170426: Are You a Boltzmann Brain?
 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.


20170410: Here's Why I Love PBS
 00:13: ... for Public Broadcasting, which provides critical financial support to local PBS stations, is one such organization on the chopping ...
 01:18: One way you can help is to contact your local congressperson or go to a town hall meeting.
 01:23: Tell them what your local station and PBS mean to you.


20170301: The Treasures of Trappist1
 10:48: ... is the maximum size region of cloud can be before it fragments, because local gravitational collapse happens faster than pressure can equalize across ...


20161221: Have They Seen Us?
 05:56: Perhaps we miss each other because we can't easily peer through our own local VHF soups.
 06:10: Two radio telescopes separated by a large enough distance can filter out local transmissions.
 06:38: ... TV bubble to many light years and that is large enough to filter out local ...
 12:35: If anyone else inhabits this very local region of the galaxy, then they may have been aware of us for some time now.


20161130: Pilot Wave Theory and Quantum Realism
 08:27: It turns out that the restriction against hidden variables only applies to local hidden variables.
 08:57: This helped the resuscitation of pilotwave theory, because Bohmian mechanics doesn't use local hidden variables its hidden variables are global.


20161102: Quantum Vortices and Superconductivity + Drake Equation Challenge Answers
 04:05: ... all wiped themselves out before even making the slightest dent in the local interstellar ...
 06:34: That tells me that we may be the only advancedish civilization to have emerged in the local region, but probably not within the whole galaxy.


20161019: The First Humans on Mars
 03:35: That means either living underground or building dense shelters from local material.


20161012: Black Holes from the Dawn of Time
 03:00: ... were, at some point in the early expansion, intense enough to resist the local expansion of the universe and form a black ...


20160929: Life on Europa?
 09:57: ... first, the simplest observable difference between the predictions of a local hidden variable theory versus pure quantum mechanics is if you measure ...
 10:17: ... the local hidden variable theory, you'd expect to sometimes measure spins in the ...
 10:54: ... contrast, a local hidden variable prediction is that the second particle doesn't care how ...


20160921: Quantum Entanglement and the Great BohrEinstein Debate
 02:40: ... of realism, you also had to abandon a concept almost as sacred locality. ...
 03:00: Locality is the idea that each bit of the universe only acts on its immediate surroundings.
 04:01: ... instantly across any distance, and even back in time, violating locality and possibly violating ...
 04:17: ... universe must be real and physical and defined by knowable quantities, local hidden variables that could affect each other no faster than the speed ...
 06:00: ... in each particle at the moment of their creation as hidden variables local to each ...
 07:13: ... to see in the case that Einstein was right and quantum mechanics needs local hidden ...
 07:27: But if an entanglement experiment violates the Bell inequalities, then local realism is also violated.
 08:41: ... inequalities are violated, suggesting that the wave function cannot have local hidden ...
 08:56: So does this confirm the Copenhagen interpretation and kill both locality and realism?
 09:15: The results of these entanglement experiments do seem to violate local realism.
 09:19: But that may mean a violation of realism, or just of locality.
 09:25: In fact, it was Doctor Bell's opinion that the violation of his inequalities disproved only locality.
 10:33: However, realist and hidden variable interpretations are also consistent as long as they abandon locality.
 11:01: There is even a way around all of this without sacrificing realism or locality.


20160810: How the Quantum Eraser Rewrites the Past
 13:04: In the event of End of World, you guys should show up at your local spaceport.


20160420: Why the Universe Needs Dark Energy
 09:53: ... field of the Milky Way and Andromeda to not dominate the shape of local ...


20160413: Will the Universe Expand Forever?
 08:14: Over billions of years, they will slip beyond our cosmic horizon, leaving only darkness beyond the local region of the Milky Way.


20160127: The Origin of Matter and Time
 06:02: It's defined locally for any observer, or indeed, thing.
 06:10: What defines that local time flow?


20151028: Is The Alcubierre Warp Drive Possible?
 01:40: ... faster than light, even if the galaxies are relatively still in their local frames of ...


20150930: What Happens At The Edge Of The Universe?
 06:01: The surface of the Earth looks pretty flat to us because we really can't see the curvature locally.


20150923: Does Dark Matter BREAK Physics?
 08:48: The monkey may see some time dilation effects from the local part of its universe.
 09:36: In fact, in the vicinity of the black hole, this radiation is poorly localized, having a wavelength of all of the Schwarzschild radius.


20150812: Challenge: Which Particle Wins This Race?
 04:31: ... symmetric perfect fluid whose energy density is the same when measured locally by an observer that's instantaneously at rest at any location in that ...


20150805: What Physics Teachers Get Wrong About Tides!
 14:27: In other words, Einstein says the standard of nonacceleration can only be defined locally in small spacetime patches.


20150729: General Relativity & Curved Spacetime Explained!
 03:01: Stated another way, a sphere can accommodate local Euclidean grids in tiny patches, but not global ones.
 03:47: ... world lines will be geodesics, and their axis and clocks can serve as local inertia frames, provided that we think of them as being reset in each ...


20150702: Can a Circle Be a Straight Line?
 06:38: ... those lines might close on themselves, but locally, snippet by snippet, geometry and straightness and tangency and ...
 06:53: Topology is global, but geometry and curvature are local.


20150527: Habitable Exoplanets Debunked!
 09:45: How that can be, even though locally, in local pockets, you can have energy conservation, seems weird and contradictory.


20150520: The Real Meaning of E=mc²
 08:58: ... Challenge." Submit your answers no earlier than 5:00 PM New York City local time on this ...


20150429: What's the Most Realistic Artificial Gravity in SciFi?
 00:58: There's simply no known way to produce the equivalent of 1 Earth g on stacked, flat surfaces, like decks of a ship, in any localized region of space.
