
20221214: How Can Matter Be BOTH Liquid AND Gas?
 14:26: ... superfluids; nuclear matter of various types; photonic matter; various spinbased states from ferromagnets to quantum spin liquids to time crystals; come ...
 17:24: ... a regular dipole magnetic field, for example by careful manipulation of spins in a crystal ...


20221208: How Are Quasiparticles Different From Particles?
 12:37: Each electron is spin half, making them fermions, but two electrons have spin 1  like a photon and that's for reasons we can’t get into.
 13:28: ... for today  for example, quasiparticles appear in lattices of quantum spin, like are magnons  quanta of waves in that lattice, or skyrmions, which ...


20221116: Are there Undiscovered Elements Beyond The Periodic Table?
 09:23: The magic numbers are all even, and that’s because nucleons pair up according to their quantum spin, just like electrons in their shells.
 09:34: One spin up and one spin down results in a net zero spin.
 09:37: ... sort of spin coupling means that even if we aren’t at a magic number of protons or ...
 09:54: Pairs of updown nucleons form these stablelittle spinzero partnerships in socalled nuclear pairing interactions.
 10:02: Having a rogue proton or neutron with an uncanceled spin seems to be bad for stability.
 10:49: It seems there are more mysterious forces at work besides neutronpadding, nuclearshell filling, and spin coupling.


20221026: Why Did Quantum Entanglement Win the Nobel Prize in Physics?
 02:36: ... subatomic to molecular scale, and the entangled property could be spin, momentum, or any other quantum ...
 06:42: ... electron transitions was between two states that had zero quantum spin, and which also resulted in the creation of two ...
 06:51: Spin is the quantum version of angular momentum.
 06:54: ... the atom’s spin hadn’t changed in this transition, in order to conserve angular momentum ...


20221019: The Equation That Explains (Nearly) Everything!
 05:37: ... I mentioned allow the particles to have two different types of spins. They can either have an integer amount of spin, like 1, 2 or 3, or even ...
 06:02: ... with half integer spin are called Fermions, and they are stuff, literally, they are what stuff ...


20220928: Why Is 1/137 One of the Greatest Unsolved Problems In Physics?
 02:36: ... as well as the fact that the energy levels of electrons with opposite spins are separated slightly by their interaction with their own orbital ...
 05:34: Those probabilities depend on many things, like the particles’ positions and momenta, spins, charges, masses, etc.


20220824: What Makes The Strong Force Strong?
 03:38: Well, slight correction: electron orbitals can contain two electrons, but that’s because those electrons can have a different spin state.
 04:13: It can’t be spin, because with 3 particles and only two possible spin states two will always have the same spin.


20220803: What Happens Inside a Proton?
 16:44: ... done with a pair of electrons with undefined but opposite spins to each other. In the case of the gloves, their states ...
 18:44: ... under superdeterminism, we could determine the spin direction of an electron without measuring it, only confirming it ...


20220720: What If We Live in a Superdeterministic Universe?
 00:26: Photons passing through two slits at once, electrons being spin up and down, cats being both alive and dead.
 02:50: For example an electron can be spinning in two different directions simultaneously.
 03:06: Let’s say we have a pair of electrons; each is in a superposition of spin states, say, with spin axis simultaneously up and down.
 03:17: ... the electrons could also be entangled with each other so that their spins are guaranteed to be opposite to each other, even if they aren’t defined ...
 03:49: Their spin direction is undefined; all we know is that they are opposite to each other.
 03:54: We give one electron to Alice and one to Bob who then go back to their separate labs to measure the spin.
 04:02: According to standard quantum mechanics, that spin is undefined until measurement.
 04:12: Let's say Alice uses a vertical orientation  she’ll measure either spin up or spin down, with a 5050 chance of each.
 04:21: Say she measures spin up.
 04:22: But that means we now know what Bob’s spin must be. It must be spin down, even before he measures it.
 04:29: If Bob then chooses to measure using the same vertical orientation he’ll definitely measure spin down.
 04:51: ... between their choices of measurement axis and the other’s measured spin. ...
 05:44: We can imagine the same scenario in the case where the electrons do know their own spin all along.
 05:51: In that case the spins are set at the beginning  still opposite to each other, but defined, even if Alice and Bob don’t know what they are just yet.
 06:10: When the two compare results, they will see correlations between the spin measurements because the original spin directions were correlated.
 06:36: ...  the Bell inequality that is true in the case that the electron spins are set from the beginning and contained within the electron  but false ...
 08:56: Now let’s look at the case where the electrons start out with defined spins.
 09:01: ... no surprise that Alice and Bob observe opposite spins because we can see that both electron’s spins were determined by a ...
 12:46: Now, this experiment used the polarization direction of photons rather than the spin direction of electrons, but it’s the same deal.


20220630: Could We Decode Alien Physics?
 00:00: ... through a process of elimination. The aliens describe two sets of spin1/2 particles, each with 3 generations  these must be the ...
 06:55: ... and lefthanded versions of all particles with quantum spin. If we build the device with positions that are spinning the ...
 07:38: ... put aside quantum spin for a minute to define this rule. Say you have an electron ...
 10:41: ... between left and right handed chirality for particles with quantum spin, and in our universe Psymmetry is broken in much more obvious ways ...


20220622: Is Interstellar Travel Impossible?
 18:50: ... that can be observed about a black hole from its exterior are mass, spin, and ...


20220601: What If Physics IS NOT Describing Reality?
 04:56: ... seems to give a meaningful “physical” answer. Consider quantum spin. From a physical point of view, think of it as a particle’s ...
 05:38: ... say we prepare an electron’s spin to all point up relative to our apparatus. The spin contains ...
 05:53: ... what if we asked the electron spin a different question “are you pointing left or right?” We ...
 07:23: ... also fits this picture. When we prepared our electrons to be spinup, that spin was relative to a chosen direction  the vertical in ...
 08:49: ... respect to a certain type of question that you ask of it. Spin direction in the last example. This idea leads us naturally ...


20220420: Does the Universe Create Itself?
 07:43: ... another experiment. If we measure the spin of one member of a pair of entangled particles  the choice of the ...


20220323: Where Is The Center of The Universe?
 16:55: Just like it makes no sense to distinguish electrons with up or down spin as different particles.
 17:49: The answer is that chirality isn’t as simple as a projection of spin onto the momentum vector.
 17:54: That spin projection is actually called helicity, and it does change depending on your reference frame.


20220316: What If Charge is NOT Fundamental?
 02:23: For example electrons have this thing called spin  a quantum analogy to angular momentum.
 02:30: ... Spin can take on discrete values; in the electrons it can be +1/2 or ...
 02:43: And spin is conserved  flip an electron’s spin and the difference has to be transferred by a photon.
 02:49: ... that they may be differentiated by a property analogous to spin, governed by analogous ...
 03:02: ... of matter: Isospin, a contraction of isotopic or isobaric spin, depending on who you ...
 05:13: ... same way that isospin followed the same mathematics as regular quantum spin, this new property seemed to obey the math for our old friend electric ...
 09:32: ...  but it's the thing that's going to connect all of this back to quantum spin, which is sort of where we ...
 09:41: One consequence of quantum spin is this thing called chirality, which is sort of the projection of spin in the direction that a particle is moving.
 09:52: ... can have righthanded chirality if their spin is clockwise relative to their momentum vector and lefthanded chirality ...
 10:39: Only lefthanded particles have it, and so it has an intimate connection to the quantum spin.


20211210: 2021 End of Year AMA!
 00:02: ... bucketness or cupness is relative uh kenny hewton asks is the bucket spinning or not spinning referencing um the classic isaac newton thought ...


20211117: Are Black Holes Actually Fuzzballs?
 02:56: The nohair theorem says that there’s no information beyond charge, mass and spin that’s observable above the event horizon.


20211110: What If Our Understanding of Gravity Is Wrong?
 06:35: ... of rotation and their luminosity  the brighter they are the faster they spin. ...


20211102: Is ACTION The Most Fundamental Property in Physics?
 13:16: Well it turns out that this equation is just the Lagrangian for a spin½ quantum field.


20211013: New Results in Quantum Tunneling vs. The Speed of Light
 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: ... in which a particle’s dipole magnetic field, which is defined by its spin axis, precesses like a top in an external magnetic ...
 11:20: ... those ones, their spins were altered by the magnetic field of the laser, and the longer they ...
 11:38: They were just trying to verify whether using spins as an internal clock would work at all, and they were successful.
 11:45: The spins were altered by pretty much the same amount that theory predicted they would be.
 11:50: ... are still relevant for the fasterthanlight Hartman effect, because the spinbased clocks that they were working with should still show the effect under ...


20211005: Why Magnetic Monopoles SHOULD Exist
 01:51: ...  where were push electrons around in a circle In both cases  electron spin or or a circular electric current there’s a sense of electric charge in ...
 14:55: ... week we talked about how quantum spin leads to the universe as we know it  for example all the structure of ...
 15:16: ... at the same energy but different quantum states by allowing for opposite spin ...
 15:39: ... points out that we don’t need to keep talking about spin as this incomprehensible quantum property that has no intuitive analogy ...
 15:55: We actually did mention this result in our episode on what is spin.
 16:16: Still, it would be nice to have a physical picture of spin that doesn’t involve me taking off my belt.
 17:12: Tom Rostrom asks whether any of this spin statistics stuff explains why USB plugs need to be turned 540° to return to the correct orientation?
 17:28: USB plugs have spin 2/3s  a 360 degree rotation gets you 2/3 of the way around.
 18:01: Or maybe you could just use USBC  they’re spin2 bosons like gravitons, so easily understood with a basic theory of quantum gravity.


20210921: How Electron Spin Makes Matter Possible
 00:26: ... now we’ve established that quantum spin is very weird. We talked all about that recently  how electrons have ...
 01:13: ... with spin½  or more generally any halfinteger spin  3/2, 5/2, etc. are called ...
 02:18: ...  there is no observable change when you swap two electrons. Combining spin behavior and indistinguishability gives us something called the spin ...
 02:59: ... we get to my belt, let me remind you about spinors. We talked all about it in the recent episode  but for now just know ...
 03:19: ... environment. Crazily the bands disentangle every 720 degrees. So a spinor’s rotational weirdness is not necessarily all that “quantum”  it’s a ...
 03:46: ... the twists are gone. So the system under these sorts of rotations is a spinor because a 720 twist is topologically equivalent to no twist  simple ...
 04:43: ... can think both ends of the belt as spinor particles like electrons, and in that case we can do another experiment. ...
 05:44: ... call these things spinors. For these same objects  spinors  a 360 degree rotation is the same ...
 06:49: ... spinor wavefunction of the electron can “wave” through space, but it includes ...
 07:22: ... so summarizing again: Electrons are spinors and so require a 720 degree rotation to be returned to their initial ...
 13:03: ... together with what we saw from the belttrick previously about spinors having antisymmetric wavefunctions, is the pauli exclusion principle. ...
 13:25: ... full spin statistics theorem has a lot more to it. One part of it is a rather more ...
 14:00: ... out great. So it’s a proof by contradiction: particles described by spinors have to have an antisymmetric wavefunction and so must obey the Pauli ...
 14:58: ... you for interacting with us lowly, fermionic lifeforms  our heads are spinning in gratitude for your ...


20210915: Neutron Stars: The Most Extreme Objects in the Universe
 11:29: ... in the entire modern universe. Here, pairs of spin½ neutrons become connected in a particular way to form Cooper ...


20210810: How to Communicate Across the Quantum Multiverse
 07:14: ... The normal linear observables are things like position, momentum, spin  the physical stuff that makes up our world. Extra observables would be ...
 09:57: ... 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 particles ...
 11:11: ... do that by making a choice: either you leave the electron with spindown, or you rotate it to spinup. After that, both you’s send their version ...
 14:02: ... that a white dwarf could potentially gain a lot of angular momentum or spin by absorbing material from another star, hence perhaps explaining that ...
 15:35: ... this tells me that yes, you can greatly spin up a white dwarf by feeding it the envelope of its binary partner. But ...
 15:46: ... its outer layers. The question is the can you absorb just enough gas to spin up the white dwarf while still allowing the partner star to explode? ...


20210803: How An Extreme New Star Could Change All Cosmology
 00:47: ... dwarf that, at first glance, looked suspicious  a bit too massive and spinning a bit too fast. That spin was seen in its rapid but periodic flickering ...
 01:31: ... confirmed that it’s 1) definitely a white dwarf, and 2) definitely spinning way too fast to make ...
 02:13: ... formed. But something is off with Zee  particularly with how fast it’s spinning. Now we do expect white dwarfs to rotate. After all, stars rotate and so ...
 09:51: ... less and we get a bigger, much weirder white dwarf. That star would be spinning really really fast because it doesn’t just have the angular momentum ...
 15:19: ... levels. Now we’ll actually be coming back to this when we get into the spin statistic ...


20210721: How Magnetism Shapes The Universe
 00:02: As far as the north magnetic pole, where the needle starts spinning wildly?
 02:43: ... the electric current in an electromagnet, or the aligned electron spins in a ferromagnet, then that current will want to loop around the ...
 13:47: ... we’re covering comments from our episode on the weirdness of quantum spin, and then our episode that tried to answer the question where exactly are ...
 14:06: On the spin episode.
 14:30: In ferromagnets, the “moving” charges are the electron spins.
 15:28: ... that for every measurement of a spin1/2 state we get 2 worlds, but for every measurement of photon number we get ...


20210707: Electrons DO NOT Spin
 00:00: ... that everyone agrees that no one understands. I’m talking about quantum spin. Let’s find out how chasing this elusive little behavior of the electron ...
 00:22: ... courses  the physics professor sits on a swivel stool and holds a spinning bicycle wheel. They flip the wheel over and suddenly begin to rotate on ...
 00:47: ... to violate conservation of angular momentum because there was nothing spinning to start with. Except there was  or at least there sort of was. The ...
 01:26: ... explanation makes sense if we imagine electrons like spinning bicycle wheels  or spinning anything. Which might sound fine because ...
 02:25: ... Einstein and deHaas in 1915. It wasn’t the first indication of the spinlike properties of electrons. That came from looking at the specific ...
 03:48: ... for that to make sense, we really need to think of electrons as balls of spinning charge  but that has huge problems. For example, in order to produce ...
 04:40: ... so electrons aren’t spinning, but somehow they act like they have angular momentum. And this is ...
 07:02: ... momentum is fundamentally quantum. The direction of this "spin" property is quantized  it can only take on specific values. And that ...
 07:30: ... is far deeper than that. To understand why we need to see how spin is described in quantum mechanics. It was again Pauli who had the ...
 08:28: ... we’ve discussed before. Dirac wasn’t even trying to incorporate spin, but the only way the equation could be derived was by using ...
 08:50: ... spinors are exceptionally weird and cool, and really deserve their own ...
 09:20: Here’s an example of spinorlike behavior. If I rotate this mug without letting go my arm gets a twist. A second rotation untwists me.
 09:59: ... two brings it back to normal. To get a little more technical  the spinor wavefunction has a phase that changes with orientation angle  and ...
 10:22: To get some insight into what spin really is, think not about angular momentum, but regular or linear momentum.
 11:26: Some physicists think that spin is more physical than this. Han Ohanian, author of one of the most used quantum textbooks.
 11:34: ... that you can derive the right values of the electron spin angular momentum and magnetic moment by looking at the energy and ...
 11:44: ... the quantum field surrounding the Dirac spinor aka the electron, imply that even if the electron is point ...
 11:57: However you explain it, we have an excellent working definition of how spin works.
 12:02: ... say that particles described by spinors have spin quantum numbers that are halfintegers  ½, 3/2, 5/2, etc. The ...
 12:13: ... it. We call these particles fermions. Particles that have integer spin  0, 1, 2, etc. are called bosons, and include the forcecarrying ...
 13:00: ... fundamental behavior? Well this is all part of what we call the spin statistics theorem  which we’ll come back to in an episode very ...
 13:30: ... aren’t spinning  they’re doing something far more interesting. The thing we call spin ...


20210623: How Quantum Entanglement Creates Entropy
 07:14: ... superposition states  like a particle simultaneously having spin up and spin down as revealed in the SternGerlach ...


20210525: What If (Tiny) Black Holes Are Everywhere?
 12:24: That said, as Simone Spinozi wittily queries: Aren't aliens also a natural phenomena?


20210407: Why the Muon g2 Results Are So Exciting!
 03:01: Let's start by talking about quantum spin.
 03:09: Every particle with electric charge also has quantum spin.
 03:15: ... particles with quantum spin do generate a magnetic field, same as if you send an electric charge ...
 04:00: An electron also has a dipole field and a dipole moment which depends on the electron spin charge and mass.
 07:23: They have the same exact charge, interact with the same forces, and have the same quantum spin.


20210217: Gravitational Wave Background Discovered?
 00:00: ... and supernovae have been exploding and stellar remnants have been spinning and probably at or before the instant of the big bang insanely energetic ...


20201222: Navigating with Quantum Entanglement
 05:00: An electron, for example, can be thought of as a spinning charge, and magnetic fields can cause that spin to flip direction.
 05:08: ... and their magnetic fields come from countless electrons with aligned spins. ...
 06:29: The entangled properties are the quantum spins of the two valence electrons in two separate radical molecules.
 06:35: ... are four possible combinations for the spins: the first is the socalled singlet state, where the spins are pointing ...
 06:58: ... other three states are when the electrons have the same spin direction  either both up, both down, or a quantum superposition of ...
 07:10: ... you have just one radical, its valence electron spin tends to stay fixed until disturbed by its environment. And Earth's ...
 07:21: But in a radical pair spin states will oscillate between the singlet and triplet states.
 07:41: ... system will spend more time in the triplet state  with both electron spins aligned in the same direction, and less in the singlet state where they ...
 07:53: ... by Earth's magnetic field, and how does the simple slipping of electron spins go on to give the bird ...
 08:36: But there’s the key  those byproducts are sensitive to the spin state of the valence electrons at the time of the reaction.
 08:43: ... during the short lifespan of the radical pair, its valence spin state can be modified if the bird changes the orientation of its head ...
 10:40: ... electrons were just interacting due to their magnetic fields  socalled spinspin interactions  rather than true entangled states  their spin state ...


20201104: Electroweak Theory and the Origin of the Fundamental Forces
 11:06: Spinning vectors and magnetic materials.


20200810: Theory of Everything Controversies: Livestream
 00:00: ... which is okay there's uh 16 particles in a generation has to do with spinner groups there are weird ways in which spinners and what would be called ...


20200728: What is a Theory of Everything: Livestream
 00:00: ... stuff you know here we are almost 80 billion of us on this little spinning ball in space who've actually amazingly after 13.8 billion years of ...


20200708: Does Antimatter Explain Why There's Something Rather Than Nothing?
 00:22: ... antiparticle identical in every way, but with the opposite charge and spin. An electron has a positron; a proton, an antiproton; and so on. And ...
 02:12: ... time reversal, where all particles have their direction of motion and spins exactly ...
 05:19: ... exact same properties as its matter counterpart, besides the charge and spin thing — it must have the same mass, the same quantum energy levels, and ...


20200630: Dissolving an Event Horizon
 02:22: According to the socalled nohair theorem, black holes can have only three properties  mass, electric charge, and spin.
 03:34: As the spin of a Kerr black hole increases, the spacetime waterfall is beaten back, and so the inner horizon grows.
 03:51: Instead, there’s a smooth run of normal  albeit rapidly spinning space all the way down to the singularity ring.
 04:43: ... we call an extremal black hole  a black hole with the maximum amount of spin or charge while still having an event ...
 05:07: More mass means more inward gravity, and so the black hole can hold more spin and charge before going extremal.
 05:20: Just add enough spin or charge to an existing black hole.
 06:52: So why shouldn’t it be possible to add a little more spin or charge to produce true naked singularities?
 08:23: Therefore just on the verge of becoming extremal, the black hole can’t gain spin from accretion anymore.
 08:43: An alternative is to throw in something that’s actually spinning itself  so it has intrinsic angular momentum.
 08:55: ... colliding black holes and various other methods for estimate black hole spin has not yet reveals a single black hole with a spin high enough to be ...


20200622: Building Black Holes in a Lab
 07:41: ... vortices are fantastic laboratories for spinning black holes in particular. Now we’ve looked deeply into rotating, or ...
 08:42: ... Water pours in from two sides, creating a slow rotation that eventually spins into a carefully shaped funnel, forming a ...


20200518: Mapping the Multiverse
 01:28: Add a little spin or charge and things get even weirder.
 01:47: It describes the way spacetime warps and flows in the vicinity of a spinning mass.
 02:04: Think of the worst spinny amusement park rides, or an astronaut highg training machine  you'd feel yourself flung outwards by centrifugal force.
 06:43: But those that approach the disk experience an overwhelming antigravitational force from the spinning singularity.


20200331: What’s On The Other Side Of A Black Hole?
 12:02: ... other quantum state. The key word here is "maximal". As an example, the spin of a newly created electronpositron pair are perfectly correlated as ...


20200324: How Black Holes Spin Space Time
 01:01: ... black hole has no rotation. But all real, astrophysical black holes are spinning. ...
 01:35: According to the nohair theorem, black holes can have three and only three properties: mass, electric charge, and spin.
 01:44: ... charges. But essentially all real black holes will be rotating. The spin of a black hole comes from the combined angular momentum of everything ...
 02:26: ... black holes might not have MUCH spin  because angular momentum can cancel out if objects fall in with ...
 02:36: ... the importance of spin in black holes, it took nearly half a century before Einstein’s ...
 05:14: ... in the gravitational field  is dragged in the direction of the object’s spin. Gravity Probe B measured the Earth’s frame dragging and it was exactly ...
 05:49: ... As long as you’re traveling in the same direction as the black hole spin. If you’re orbiting in the opposite direction, there are no stable orbits ...
 07:33: ... everything  even light  must move in the direction of the black hole’s spin. ...
 08:37: ... spherical  it’s squished at the poles, like the rotating Earth. More spin equals more squished. The ergosphere has a similar shape  but also dips ...
 09:37: ... from the rotational energy in the ergosphere, slowing the black hole’s spin. To get a little more technical  it works because the weird spacetime ...
 10:51: ... the black hole in an accretion disk. The flow of space in the ergosphere spins up the magnetic field into a gigantic particle accelerator. Charged ...


20200316: How Do Quantum States Manifest In The Classical World?
 02:56: ... quantum particles have a property called quantum spin. That spin has an axis that points in some direction, analogous to the ...
 03:12: ... vertically and you might see that the spin axis is pointing up or down, measure horizontally and it’ll be pointing ...
 03:37: ... the value for quantum spin depends on how you choose to measure it  it depends on your ...
 04:28: ... 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 axes of the ...
 05:32: ... crazy thing is if I measure the spin of one particle  say the electron  my choice of measurement basis ...
 06:24: ... think about exactly what’s happening when I try to measure the spin of one of those entangled particles. I’ll try to do that in the most ...
 07:02: But we can try to measure the spin state by placing a detection apparatus on one path.
 07:15: ... of those two states doesn’t matter as long as it doesn’t change the spin or sap energy from the electron. One possibility would be that the spin ...
 07:37: ... to just look at the atom to learn the electron’s path, and so learn its spin. But what happens after the electron passes through our device. Does its ...
 08:44: ... could prove that by measuring the spin of the positrion, which would instantaneously influence the combined ...
 09:19: See, the entangled atom now holds information about the electron’s leftright spin.
 09:28: ... here  suffice to say that it's possible to recover the horizontal spin information, even if it’s more straightforward to recover the vertical ...


20200211: Are Axions Dark Matter?
 06:54: ... hypothetical axion particle would have no electric charge, no quantum spin, be extreme ly light  a tiny fraction of the mass of the already tiny ...


20200127: Hacking the Nature of Reality
 07:12: ... of energy and momentum, the behavior of quantum properties like spin, and the assumption of a family of particles that can be involved in the ...
 08:57: ... him to explain the peculiar relationship between the mass and the spin of ...


20200113: How To Capture Black Holes
 08:27: ... Yang and co. also predict a particular distribution of black hole spins  again to be tested with more LIGO ...


20191209: The Doomsday Argument
 12:16: ... or not doom is coming soon or late, here’s a positive spin on the whole doomsday argument: the chances of us being in the final ...


20191104: Why We Might Be Alone in the Universe
 05:59: ... solid iron inner core spins suspended in a molten metal outer core, and this motion generates a ...
 13:32: Dig into spin networks and spin foam if you want a headache too.


20191021: Is Time Travel Impossible?
 08:51: The maelstrom of spinning spacetime may generate closed timelike curves deep down below the event horizon.


20191015: Loop Quantum Gravity Explained
 08:20: ... one in which you parallel transport not a vector but something called a spinor  a vectorlike thing that also represents a quantum of angular momentum ...
 08:39: Ashketar rewrote general relativity in terms of these spinconnections  now known as Ashketar variables.
 09:04: ... WheelerdeWitt equation by representing spatial metrics using Ashketar's spin ...
 10:15: 3D space can be sort of woven from these loops into something called a spinnetwork  which is a concept too abstract for even this episode.
 15:26: I talked about the maximum rate of spin of a back hole, and so Lucas rightly asks how fast is that maximum rate?


20191007: Black Hole Harmonics
 06:10: ... what parameters went into the signal – in particular black hole mass and spin, so you know if you got the right answer when you try to predict these ...
 07:12: Similarly, the overtone structure of a black hole ringdown can identify the fundamental properties of that black hole – namely its mass and spin.
 07:22: ... researchers found that they could pinpoint the mass and spin of the simulated black holes with much greater precision than if they’d ...
 08:50: ... also get a spin for the final black hole – a socalled dimensionless spin magnitude of ...
 09:13: ... the mass and spin derived from the ringdown are consistent with the estimate that was ...
 09:44: General relativity predicts that black holes should be completely defined by three properties – their mass, spin, and electric charge.
 10:08: ... black holes are also expected to have no electric charge, so mass and spin should define everything – including the nature of the oscillations ...
 10:34: The oscillations are consistent with a black hole purely defined by its mass and spin.


20190916: Could We Terraform Mars?
 16:42: ... more complex fields like vector fields and spinor fields can do the job too  and some inflationary models use them, ...


20190903: Is Earth's Magnetic Field Reversing?
 08:30: In fact, HOW can it flip? – surely the direction of the magnetic field depends on the direction Earth is spinning.
 10:29: For those who don’t trust computer simulations – how about building our own giant spinning ball of molten metal?


20190715: The Quantum Internet
 09:07: ... a photon and a matter particle – say, an electron whose up or down spin direction can be entangled with the polarization state of a ...
 09:27: ... in a cloud of caesium atoms, a kind of quantum atomic disk drive, or the spinstate of a single electron in a nitrogen atom embedded in diamond ...


20190701: Thorium and the Future of Nuclear Energy
 17:49: ... region in the middle of the accretion disk that depends on black hole spin It's one way we'll be able to measure that spin But this definitely ...


20190516: The Cosmic Dark Ages
 05:45: ... this is just the tl;dr. When the electron in cold hydrogen gas flips its spin direction it either absorbs or emits a radio photon with a wavelength of ...


20190509: Why Quantum Computing Requires Quantum Cryptography
 11:04: ... is correlated between the two – for example, electrons with opposite spin axes or photons with 90degree ...
 11:18: Our choice of measurement direction will set the diection of those spin or polarizations axes.
 11:25: ... or basis on which to measure one of those particles – say updown for spin or rectilinear for polarization  and the other also becomes “measured” ...


20190501: The Real Science of the EHT Black Hole
 06:53: Measuring the radius of the photon sphere potentially gives you both black hole mass and spin.
 07:05: That disk terminates at a few times the Schwarzschild radius – again depending on black hole spin.
 09:19: ... team simulated a wide range of parameters like black hole mass and spin rate, while they were able to nail down the rotational axis rotation ...
 09:51: The black hole is indeed spinning – almost as fast as it can spin.


20190424: No Dark Matter = Proof of Dark Matter?
 00:03: ... mass of their visible stars alone they should throw themselves to pieces spinning that quickly that is unless a gravitational force of unseen origin was ...


20190320: Is Dark Energy Getting Stronger?
 16:28: That said, Virgin Orbit  a spinoff of Virgin Galactic has airlaunch rocket that is expected to put satellites in orbit this year.


20190130: Perpetual Motion From Negative Mass?
 03:48: ... this is also what quantum field theory predicts: fields with even spin have to work in the opposite way to fields with odd ...
 04:00: ... time to get into why this is the case, or what the spin of a field even means, but the gravitational field is spin 2 – even  so ...
 04:13: Electromagnetism is spin 1  odd  so attraction and repulsion are flipped compared to gravity.


20190116: Our Antimatter, Mirrored, TimeReversed Universe
 00:42: ... universe the same decay should be in the opposite direction so with that spin axis which is fundamentally different physical behavior. So, what does ...
 02:02: ... counterparts but now the decay electrons travel upwards with the nuclear spin and away from the detector such a clock wouldn't tick at all taken to ...
 03:02: ... but also theoretically required. Starting with Julian Schwinger's "Spin statistics theorem" in 1951 it became increasingly clear that quantum ...
 10:54: ... converting matter to antimatter  you're just reversing all momentum and spin. Essentially you're taking all particles in the universe and pointing ...


20190109: Are Dark Matter And Dark Energy The Same?
 01:18: So, dark matter: the galaxies are spinning too fast.
 06:32: Those simulations showed that galaxies do indeed spin more quickly when surrounded by negative mass particles.
 06:50: This confines the galaxy from the outside so it can spin faster than if it were held together by its gravity alone.


20181220: Why String Theory is Wrong
 16:28: ... us of filming that episode in a mirror universe apparently balls were spinning clockwise when I said counter clockwise left became right and viceversa ...


20181212: Quantum Physics in a Mirror Universe
 00:02: ... in the reflection but what if we try something else let's put some spin on the ball say clockwise spin the reflected ball is still spinning ...


20181121: 'Oumuamua Is Not Aliens
 09:54: Certainly a working probe shouldn't be spinning end over end.


20181031: Are Virtual Particles A New Layer of Reality?
 05:18: ... their real counterparts in particular, quantum numbers like charge and spin, but they don't need to obey Einstein's relationship between energy mass ...


20181018: What are the Strings in String Theory?
 03:03: And one of those modes appeared to be a massless spin2 particle.
 03:08: But the only hypothetical massless spin2 particle is the graviton, the conjectured quantum particle of the gravitational field.
 07:24: And those modes, in turn, define particle properties like electric charge and spin.


20181010: Computing a Universe Simulation
 07:16: For example, a simple quantum system would be a group of electrons with spins pointing up or down, corresponding to a single bit the information each.
 07:25: ... the spin of an electron is a change to an orthogonal state, but it can also be ...
 07:35: This sort of quantum spin array is exactly the system used in most quantum computers.


20180920: Quantum Gravity and the Hardest Problem in Physics
 14:25: As they lose spin, angular momentum, they become more spherical.


20180912: How Much Information is in the Universe?
 04:21: ... includes position, but also other degrees of freedom, like momentum, spin direction, et ...


20180905: The Black Hole Entropy Enigma
 02:08: From the point of view of the outside universe, black holes can only have three properties mass, spin, and electric charge.
 04:59: We can easily measure its mass, spin, and electric charge, and according to the nohair theorem that's all there is to know.
 06:29: There's also the Penrose process in which you can extract rotational energy of a spinning black hole.


20180823: How Will the Universe End?
 14:59: That's the classical theory, which is wrong and also suggested that electrons should spin faster than light.
 15:43: All they have is their quantum wave function, which tells the probability of the particle's location, momentum, spin, direction, et cetera.


20180815: Quantum Theory's Most Incredible Prediction
 04:02: Nonetheless, electrons do have a sort of intrinsic, angular momentum, a fundamental quantum spin that is as intrinsic as mass and charge.
 04:12: Despite not being the same as classical rotation, this quantum spin does grant electrons a dipole magnetic field.
 05:42: This equation is the origin of quantum electrodynamics and the first to correctly capture the notion of quantum spin.
 05:49: It describes electrons as weird, four component objects with quantum spin magnitudes of half.
 10:54: Electron spin axes are always slightly misaligned with an external magnetic field, due to quantum uncertainty in the spin direction.


20180801: How Close To The Sun Can Humanity Get?
 07:54: ... spin roughly, 11 days doing science during each orbital cycle, while spending ...


20180718: The Misunderstood Nature of Entropy
 06:32: ... for all possible combinations of all properties position, momentum, spin, vibration, really any degree of freedom that the system can ...


20180704: Will A New Neutrino Change The Standard Model?
 03:46: Helicity is just the direction of a particle's spin relative to its direction of motion.


20180613: What Survives Inside A Black Hole?
 08:40: And so if the black hole is spinning or racing past you, you'll see that magnetic field.
 08:52: In Einstein's general relativity, a spinning mass drags the fabric of space time around with it in a phenomenon known as frame dragging.
 09:19: ... material with angular momentum falls into a black hole, whether it's a spinning star or a whirlpool of gas, it will either add or subtract from this ...
 09:30: Its angular momentum is remembered in the frame dragging as though the entire black hole was spinning.


20180321: Scientists Have Detected the First Stars
 01:31: ... or absorbed, when the ground state electron and hydrogen flips its spin ...
 01:47: ... the early universe, the rate of hydrogen spin flip was in equilibrium with the CMB, meaning that for every CMB photon ...
 01:57: We say that the electron spin temperature was coupled to the CMB temperature.
 02:20: ... light from those stars shifted the equilibrium so that the electron spin temperature became connected to the temperature of the gas, instead of ...


20171019: The Nature of Nothing
 13:26: Any particle with integer spin is a boson.
 13:29: All those with halfinteger spin are fermions.
 13:32: ... as fermions because the elementary particles that form atoms are all spinhalf fermions, so electrons and quarks, while the forcecarrying particles ...
 13:47: Protons and neutrons, which combine three quarks, all have spins of half.
 13:53: But in a helium4 nucleus, the protons pair up and have opposite spins, so they cancel out, same with the neutrons and the electrons.
 14:02: The result is zero spin, which is an integer.


20171011: Absolute Cold
 04:00: Helium 4 has a total spin of 0, which makes it a boson so a particle with integer spin.
 04:07: Now bosons are able to occupy the same quantum state as each other unlike the halfinteger spin fermions, which cannot.


20170928: Are the Fundamental Constants Changing?
 05:13: And these electrons have spins pointing in opposite directions.
 05:17: Now, quantum spin gives electrons what we call a magnetic moment.
 05:38: ... magnetic fields produced by an electron's spin and by its orbital motion actually interact with each other in an effect ...
 06:02: So when electrons jump between orbitals, the energy they absorb or emit depends on their spin alignment.


20170830: White Holes
 02:45: ... describes a black hole the simplest black possible, one without spin, without charge, or without change, an eternal black that doesn't grow or ...


20170816: Extraterrestrial Superstorms
 02:09: Any object moving over a spinning surface will appear to follow a curved path relative to an observer moving with that surface.
 13:59: Well, my barber just shaves halfinteger spin off the sides.


20170707: Feynman's Infinite Quantum Paths
 07:51: ... work and help from others, like figuring out how to add particles with spin, the path integral approach is both mathematically equivalent to and more ...


20170628: The First Quantum Field Theory
 09:40: ... the tiny difference in atomic electron energy levels due to electron spins spins interacting with magnetic fields in the socalled hyperfine ...
 14:02: ... emission line energies in hydrogen due to not accounting for electron spin. ...
 14:18: However, the Klein Gordon equation is actually the exactly right description for particles with no spin.


20170621: AntiMatter and Quantum Relativity
 02:33: Yet, we now know that many elementary particles have an internal property called spin.
 02:42: But spin does result in a sort of quantum angular momentum.
 02:47: For example, an electron's spin causes them to align themselves with magnetic fields, just like a rotating electric charge would.
 02:55: The axis of spin can point in different directions; for example, up or down.
 03:00: The discovery of quantum spin starts with an Austrian physicist named Wolfgang Pauli.
 04:05: ... physicists soon figured out that this new quantum state represented spin and the up and down degrees of freedom were the direction of pointing of ...
 04:16: We now call these two component wave functions, spinors.
 04:20: Now, it's OK to ignore spin in the old Schrodinger equation and get approximate answers.
 04:26: But when a magnetic field is present, spin direction becomes very important.
 05:27: Instead of having a twocomponent spinor, up and down, as in Pauli's theory, he needed four components.
 09:48: ... two extra components correspond to the up and down spins of the electron's antimatter counterpart, two spin directions for the ...


20170405: Telescopes on the Moon
 06:41: It spins a six meter dish of mercury at 8.5 revolutions per minute, creating the cheapest telescope of that size ever constructed.
 11:24: One possibility could be in a ReissnerNordstrom black hole, so one with electric charge, but no spin.


20170329: How Time Becomes Space Inside a Black Hole
 12:02: The systems that were tested use electron spins, which pull on each other to cause a cascading flow of flipping spins the cycles back and forth.
 12:28: Colin Brown asks if the spin flip oscillation is only dependent on the electromagnetic field oscillation.


20170315: Time Crystals!
 04:07: These atoms have spin values, quantum mechanical angular momenta from their electrons.
 04:13: Spins in nearby atoms like to line up with each other due to interacting magnetic fields.
 04:28: So you prepare a string of ions where the line spins.
 04:32: Now cause those spins to flip back and forth using a laser.
 04:43: The spinflip oscillation will be determined by the period of the laser.
 04:54: Causing spins to flip in a laser isn't particularly exciting.
 05:01: But the paper proposes that if you let go of the electrons, their spin oscillations should continue.
 05:19: ... addition, other researchers theorized that spins should not oscillate at the same period as the laser, but at an integer ...
 05:29: So two, three, four, et cetera spin oscillations for every EM field oscillation in the laser.
 05:54: The analogous phase diagram for time crystals plots interaction strength between atoms versus imperfection in the spinflip driving signal.
 06:30: If the connections between the spins of the ions become too strong, then a wormhole forms and sends your graduate students back to the Paleocene era.
 07:08: They used microwaves to generate oscillations in the spins of nitrogen impurities inside a diamond.
 07:18: Both spin systems developed periods that were integer multiples of the drivers.
 08:34: ... to building a quantum computing memory element is to use electron spins, which can represent the ones and zeros of a classical computer in the ...
 08:51: ... motion from heat to scramble a carefully prepared array of entangled spin alignments, completely messing up your ...
 09:00: Time crystals with their resilient spinflip cycle could be the next step in building stable quantum memory.


20170222: The Eye of Sauron Reveals a Forming Solar System!
 02:51: Conservation of angular momentum has the central star spinning rapidly.


20161208: What Happens at the Event Horizon?
 11:13: We'll also come back to what happens if we set the black hole spinning or add some electric charge.


20161130: Pilot Wave Theory and Quantum Realism
 09:07: The entire wave function knows the location, velocity, and spin of each particle.
 14:30: Well, to create and sustain a magnetic field, you need some charge that's moving or spinning in some way.


20161116: Strange Stars
 02:16: The remaining neutron star is millions of Kelvin in temperature, and may be spinning thousands of times per second.
 02:28: These jets may sweep across the Earth due to the spinningtoplike procession of the neutron star.


20161102: Quantum Vortices and Superconductivity + Drake Equation Challenge Answers
 01:33: ... extremely low temperatures, the spins of a material's particles tend to line up, but you get these little ...
 01:53: Vortices are essentially holes in the spin distribution, and so define the topology of the material.
 02:11: ... superconductors and superfluids, and providing new ways to move charge, spin, and even information around ...


20161019: The First Humans on Mars
 09:36: Black holes exhibit only three properties mass, electric charge, and spin.


20160929: Life on Europa?
 08:15: However, in its 2016 budget, Congress threw a spinner in the works well, sort of.
 09:57: ... variable theory versus pure quantum mechanics is if you measure the spins of both particles with the same measurement ...
 10:10: In that case, the pure quantum, nohiddenvariable prediction is that you'll always measure opposite spins.
 10:17: ... the local hidden variable theory, you'd expect to sometimes measure spins in the same direction, depending on the relationship of the chosen ...
 10:29: ... instead, you measure one spin in one direction and the other at 90 degrees, then the pure quantum ...
 10:54: ... the first was measured, so it aligns itself according to its original spin, which probably won't lead to an even 50/50 ...


20160921: Quantum Entanglement and the Great BohrEinstein Debate
 04:45: When spontaneously created from a photon, these particles will always be spinning in opposite directions to each other.
 04:53: However, until measured, we can't know which direction either is spinning.
 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.
 05:15: In the case of quantum spin, that measurement effect is especially weird.
 05:20: We define spin direction according to the spin axis.
 05:26: But to measure spin direction, we need to choose an axis to align our measuring device.
 05:31: We always find that the observed quantum spin aligns itself with our chosen measurement axis.
 05:38: If we choose to measure vertically, the spin will turn out to be up or down.
 05:51: But how does this affect the spin of its entangled partner?
 06:00: ... was right, imagine the response of each particle to all possible spin measurements is encoded in each particle at the moment of their creation ...
 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.
 07:57: Instead of looking at the entangled spins of an electron positron pair, he used photon pairs with entangled polarizations.


20160907: Is There a Fifth Fundamental Force? + Quantum Eraser Answer
 02:06: That transition meant a difference in energy, but also a difference in some of the quantum stuff, spin parity and isospin.
 02:14: And the easiest way to explain this is if a spin1 gauge boson was created.
 02:27: Yes, a new spin1 gauge boson.


20160824: Should We Build a Dyson Sphere?
 07:22: ... material, or by extracting angular momentum from the black hole's spin. ...


20160727: The Quantum Experiment that Broke Reality
 05:52: In fact, several quantum properties, like momentum, energy, and spin, all display similar waviness in different situations.


20160706: Juno to Reveal Jupiter's Violent Past
 02:39: ... own Milankovitch cycles, periodic changes in Earth's orbit and spin, are largely driven by Jupiter's influence and give us our cycles of ...


20160615: The Strange Universe of Gravitational Lensing
 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.


20160525: Is an Ice Age Coming?
 04:11: Our spin axis is now tilted at 23 1/2 degrees relative to the axis of our orbit.


20160323: How Cosmic Inflation Flattened the Universe
 12:29: A couple of you asked about the shape of a black hole and its accretion disk based on the spin of the black hole.
 12:47: Yet that doesn't have much to do with the spin of the black hole itself.
 13:00: Although the magnetic field of a spinning black hole can also play a part here.
 13:05: However, the shape of the event horizon of the black hole itself does depend on spin.


20160316: Why is the Earth Round and the Milky Way Flat?
 07:51: In the case of the Earth, how flat does it get due to its spin?
 08:56: They also start out spinning very slowly, but that spin speeds up as they collapse, just like a spinning ice skater.
 09:28: The cloud can still collapse in the down direction, and it does so, ending up as a spinning disk when it finds itself in equilibrium.


20160211: LIGO's First Detection of Gravitational Waves!
 06:24: And potentially, even the actual spin of neutron stars.


20160203: Will Mars or Venus Kill You First?
 01:23: ... size, it's molten interior has solidified long ago, grinding its once spinning iron core to a halt and essentially turning off its magnetic ...


20151216: The Higgs Mechanism Explained
 02:35: ... has this type of intrinsic quantum spin that we call chirality, and this can either be clockwise or ...
 02:48: Now, that spin constantly flips back and forth.
 03:23: It has spin, but the spin never flips.
 03:59: To understand how this works, we need to come back to this spin flip thing.
 04:43: It's an open question why the universe cares which direction you're spinning.


20151209: How to Build a Black Hole
 10:24: The black hole retains mass, electric charge, and spin.


20151022: Have Gravitational Waves Been Discovered?!?
 00:48: There's the dragging of spacetime by spinning masses.
 02:03: But two objects orbiting each other, or an asymmetrically spinning or exploding thing, does.


20150923: Does Dark Matter BREAK Physics?
 00:18: The Milky Way galaxy is spinning so fast that it should be scattering its stars into the void.
 03:20: Remember when I said that the Milky Way spinning too fast?


20150708: The Leap Second Explained
 02:09: Earth is spinning down, yeah, but not that quickly.


20150624: The Calendar, Australia & White Christmas
 00:48: The reason for this discrepancy is that the spinning Earth is basically a giant gyroscope.
 00:53: See, Earth bulges slightly at the equator due to centrifugal effects from its own spin.
 01:14: But instead, it causes the spin axis to precess, like a top.
 04:40: ... is also slowly spinning down due to its interactions with the moon, so that the mean solar day ...


20150520: The Real Meaning of E=mc²
 09:11: ... on the next episode of "Space Time." Last week we talked about NASA spinoffs. ...
 09:25: ... mentioned some things, to set the record straight, that are not NASA spinoffs microwave ovens, Tang, Velcro, cordless power tools, the space pen, MRI ...
 09:36: But you did mention some NASA spinoffs that we missed.


20150513: 9 NASA Technologies Shaping YOUR Future
 00:02: If you were born in the US after the mid 1990s, you most likely ingested a spinoff of NASA technology.
 00:15: NASA spinoffs are everywhere.
 01:35: So what's a spinoff?
 01:43: Another spinoff?
 03:23: So that's right, the NASA spinoff in this case is earthquake proof buildings.
 05:42: So I think you can see the spinoff coming goggles for firefighters that can see through walls of smoke and flame, which is super bad ass.
 06:14: The spinoff?
 06:29: If you want to learn more, NASA Spinoffs actually has it own YouTube channel, magazine, and Twitter account, all linked in the description.
 06:37: Let us know your favorite spinoff, or let us know any good ones we missed down in the comments.


20150506: Should the First Mars Mission Be All Women?
 09:04: ... in your neck because there's less gravity there compressing your spine. ...


20150429: What's the Most Realistic Artificial Gravity in SciFi?
 01:54: In there, it doesn't look like anything is spinning.
 03:39: Say you and a friend are on a merrygoround that spins counterclockwise as viewed from above.
 07:12: ... instead, one about 8 kilometers long and half a kilometer in radius spinning around its longitudinal ...


20150408: Could You Fart Your Way to the Moon?
 07:44: ... the moon to orbit around the planet at the same rate that the planet spins on its axis, which I agree is not something that should happen if the ...


20150325: Cosmic Microwave Background Explained
 06:16: ... isn't wrong, but wasn't we were going for, is to take the already spinning flywheel, just one of them, and slow down its ...
 06:29: ... as you do from actually rotating a gyroscope without changing its spin. ...


20150318: Can A Starfox Barrel Roll Work In Space?
 01:45: So how do you torque the ship to get it spinning and then stop it after a full 360?
 01:50: Because in case it isn't obvious, once you get the ship spinning, it won't stop on its own.
 01:56: ... any rigid spinning object, like a planet, will continue to spin at exactly the same rate, ...
 02:09: ... hand would point if you curl your fingers in the sense of the object's spin. ...
 03:23: By rotating the flywheel quickly, I end up transferring its angular momentum to myself, so I start spinning.
 03:36: Imagine the ship has been preloaded with an alreadyspinning flywheel, like the spinning bike wheel you see on the screen.
 03:42: That flywheel is spinning clockwise, as seen from the rear of the ship, or counterclockwise as seen from the nose.
 05:19: If you want to feel this physics in action, just get a bike wheel with some pegs, clamps to add mass, a spinning chair, and a couple of friends.
 05:33: ... you'd flip them mechanics or with magnets, or how fast they'd have to spin in the first place to store up enough angular momentum for the barrel ...
 05:50: ... assuming you can spin a massive enough flywheel fast enough, without it breaking apart, and ...


20150211: What Planet Is Super Mario World?
 02:06: ... had Mario do regular jumps in place, not the spin jumps, and I used to some tape to mark where the top of his hat was at ...
