
20221109: What If Humanity Is Among The First Spacefaring Civilizations?
 17:23: ... at the instant a measurement is made, in apparent violation of relativity and the speed of light limit on causal ...


20221026: Why Did Quantum Entanglement Win the Nobel Prize in Physics?
 00:47: ... as Einstein called it, is in seeming violation of his own theory of relativity, which tells us that no causal influence can travel faster than ...


20221019: The Equation That Explains (Nearly) Everything!
 09:45: ... a series of matrices to ensure everything stays compliant with general relativity The D itself is made of two parts. We have a derivative, which as we ...


20221012: The REAL Possibility of Mapping Alien Planets!
 04:12: ... let’s review gravitational lensing. Einstein’s general theory of relativity tells us that gravity is due to curvature in the fabric of ...


20220928: Why Is 1/137 One of the Greatest Unsolved Problems In Physics?
 02:36: ... the discrepancy by including the effects of Einstein’s stillnew relativity, as well as the fact that the energy levels of electrons with opposite ...
 11:20: ... the translation factor between the dimensions of space and time in relativity; it’s also the relationship between mass and energy in Einstein’s ...


20220817: What If Dark Energy is a New Quantum Field?
 01:25: ... just a static number that you can add to Einstein’s equations of general relativity to represent the fabric of space having a constant, nonzero energy ...
 01:41: ... accelerates expansion requires a dive into the hairy math of general relativity  and we tried that in a couple of previous episodes. For today, I need ...
 13:04: ... These sorts of negative energy scenarios break the rules in general relativity in the same way that time travel does. So, if the big rip is possible, ...


20220720: What If We Live in a Superdeterministic Universe?
 05:17: A foundational axiom of relativity is that no causal influence can travel faster than the speed of light.


20220615: Can Wormholes Solve The Black Hole Information Paradox?
 00:26: ... Maxwell’s electromagnetism didn’t square with Galileo’s relativity led Einstein to his special theory of relativity, from which ...
 06:54: ... teams managed to predict the Page curve using only general relativity and accepted quantum mechanics  no string theories ...


20220601: What If Physics IS NOT Describing Reality?
 16:52: ... to expand space you just need to change space, and general relativity predicts that this should happen. Also, we wouldn’t expect ...


20220525: The Evolution of the Modern Milky Way Galaxy
 18:41: ... math that way. There is a valid interpretation of general relativity in which we can say that space is flowing inwards in a ...


20220504: Space DOES NOT Expand Everywhere
 00:19: ... us, and interpreted through the lens of Einstein’s general theory of relativity, this only makes sense if all distances everywhere are increasing evenly. ...
 01:59: ... but there’s a cleaner picture. Soon after Einstein finished general relativity, four scientists independently solved its equation for the entire ...
 02:38: ... spacetimes  representing single instants in time. If you use general relativity to track how the FLRW metric changes over time, you find that it has to ...
 09:16: ... general relativity, space can be infinitely divided. That means we can start with a universe ...
 10:33: ... infinitely divisible. But we know that at the smallest scales, general relativity comes into conflict with quantum mechanics. There is a smallest ...


20220420: Does the Universe Create Itself?
 17:08: ... that’s not the same as saying it requiring different physics  general relativity permits white or black holes of any ...


20220330: Could The Universe Be Inside A Black Hole?
 00:19: Einstein’s ridiculously successful general theory of relativity has never failed.
 01:01: In general relativity, that looks like a point of infinite density surrounded by an event horizon.
 03:37: In general relativity, objects that are not being acted on by a force follow something called a geodesic.
 04:41: In fact, in general relativity, singularities are defined as the end points of geodesics.


20220323: Where Is The Center of The Universe?
 02:57: His general theory of relativity explains gravity as the warping of space and time due to the presence of mass and energy.
 03:04: General relativity can be used to calculate the spacetime curvature produced by the Earth or the Sun to determine their gravitational effects.
 08:41: They’re the grid that defines the fabric of space time in general relativity, and correspond to the paths followed by light.
 11:45: And you can do it without breaking Einstein’s general relativity.
 14:10: To understand astrophysics, Brilliant believes it helps to have a solid understanding of relativity.
 14:15: Brilliant has a lesson on special relativity that includes interactive challenges and problems to solve.
 14:21: A handson approach can guide you through thinking strategies for challenging subjects like relativity.
 14:27: ... starts out explaining relativity in terms of boats passing by each other on a river, then goes into some ...


20220308: Is the Proxima System Our Best Hope For Another Earth?
 17:45: ... at large curvatures that produce hopeless contradictions between general relativity and quantum ...
 18:09: Even including relativity and the shifting nature of space into time and vice versa, you still have a consistent if mutable underlying grid.


20220216: Is The Wave Function The Building Block of Reality?
 09:25: ... will be “gravitized.” For example, consider a massive object. General relativity says that the mass from that object will warp the spacetime around it. ...


20220210: The Nature of Space and Time AMA
 00:03: ... as some kind of definite now or universal simultaneous moment the relativity of simultaneity showed us i guess that my perception of now could be ...


20220127: How Does Gravity Escape A Black Hole?
 00:35: ... presented to the world the equations behind his general theory of relativity, which describe gravity not as a traditional force, but rather in terms ...
 01:13: General relativity made many other predictions.
 01:21: ... \kappa T_{\mu\nu} so they would be consistent with his special theory of relativity, which describes how lengths and times and other properties depend on how ...
 01:33: Special relativity enshrined the speed of light as the absolute cosmic speed limit.
 01:49: Naturally enough, the “c” of the speed of light made its way into the equations of general relativity.
 03:25: Starting with good old fashioned general relativity.
 05:40: This explanation works for the black holes of general relativity.
 05:54: ... physicists believe that general relativity needs to be replaced by a theory of quantum gravity to explain the ...
 09:36: According to relativity, that means its clock slows.
 11:27: ... fact the whole idea of mass is poorly defined in general relativity in part because the gravitational field itself has energy, and so is a ...


20220119: How To Build The Universe in a Computer
 09:34: ... complexity of including magnetic fields, or of Einstein’s general relativity when the gravitational field becomes very ...


20211220: What Happens If A Black Hole Hits Earth?
 14:10: ... from the last two episodes, both on different ways to break general relativity. There was the one on modified newtonian dynamics as an explanation for ...
 14:26: ... to fit observation then it’s missing something. In the case of general relativity, it works almost everywhere  so if we find a place it doesn’t work we ...
 16:33: ... need to satisfy the equivalence principle  the founding idea of general relativity that says that freefall in a gravitational field is fundamentally the ...
 18:16: ... Event Horizon Telescope could potentially detect deviations from general relativity in the form of quantum fluctuations near the event horizon that might be ...


20211210: 2021 End of Year AMA!
 00:02: ... to fill um if you especially if you watch these episodes on general relativity you'll see how uh well how much of a genius gabe really is so uh i ...


20211117: Are Black Holes Actually Fuzzballs?
 00:20: ... perhaps even weirder than the regular type Einstein’s general theory of relativity tells us that if the density of matter is sufficiently ridiculous, ...
 01:00: At the central singularity, the known laws of physics break down  general relativity comes into irreconcilable conflict with quantum mechanics.
 01:14: ... the one hand, general relativity insists that no information from the matter that fell into a black hole ...
 02:52: Not so in the black holes of general relativity.
 04:17: Ultimately, the black hole paradoxes stem from the disagreement between quantum mechanics and general relativity.
 04:49: ... was able to describe the black hole using pure general relativity but then analyze its effect on the surrounding quantum fields, which ...
 08:55: In fact, if you have a bunch of strings dense enough to form a black hole in general relativity, it wouldn’t actually collapse.
 11:02: All classical effects of black holes from general relativity would be preserved.
 13:38: And they’re one of our best hopes for understanding the union of general relativity with the quantum.
 13:53: To understand astrophysics, Brilliant believes it helps to have a solid understanding of relativity.
 13:59: Brilliant has a lesson on special relativity that includes interactive challenges and problems to solve.
 14:04: A handson approach can guide you through thinking strategies for challenging subjects like relativity.
 14:10: ... starts out explaining relativity in terms of boats passing each other on a river, then goes into some ...


20211110: What If Our Understanding of Gravity Is Wrong?
 02:52: ... field gets too strong  there you need his general theory of relativity, which explains gravity as the curvature in the fabric of space and ...
 06:10: ... it’s not consistent with general relativity  in that general relativity does not reproduce MOND in what we call the ...
 08:25: And done the right way the result can also work with relativity.
 09:53: ... system scales, like MOND on galactic scales, and like regular general relativity for gravitational ...
 14:01: ... the standard model by dark matter particles, or beyond general relativity by hidden gravitational modes of space ...
 15:45: ... space Lagrangian seems to bridge quantum mechanics and relativity, what's missing to make this a theory of ...
 17:17: A few people pointed out an error  I said that the action reduces to an integral over proper time in general relativity.
 17:33: In fact, in general relativity objects in gravitational fields tend to maximize, not minimize their proper time.


20211102: Is ACTION The Most Fundamental Property in Physics?
 05:24: ... classical mechanics and into our modern theories  in particular general relativity and quantum mechanics. And perhaps in these we’ll find clues as to what ...
 05:52: ... start with Einstein’s General Theory of Relativity, which, as we’ve discussed before, describes the force of gravity in ...
 06:47: ... relativity, clocks run at different rates depending on things like relative speed ...
 07:09: ... of motion that are valid even in the shifting frames of Einstein’s relativity. And we also start to learn something about the nature of the Action. ...
 12:16: ... with its current Potential and Kinetic Energies. When we take this to relativity we see the configuration space becomes configuration spacetime, where ...


20211020: Will Constructor Theory REWRITE Physics?
 01:43: ... so on from two master theories: quantum mechanics and Einstein’s general relativity. ...
 02:40: ... uses theories like general relativity and quantum mechanics, along with more fundamental conservation laws, or ...
 04:42: For example, understanding the union of quantum mechanics and general relativity.
 05:31: ... laws of general relativity forbid this task: as a freefalling body the apple must follow a ...
 09:55: It doesn't need the dynamical laws of such a theory, or even of quantum mechanics or general relativity as they currently stand.
 10:42: ... general theory of relativity came from asking what were the inevitable implications of simple ...


20211013: New Results in Quantum Tunneling vs. The Speed of Light
 05:27: ... we’ve said before, his theory of special relativity explains that if you move faster than light, you can send signals into ...
 05:37: So in our previous tunneling episode, we offered an explanation for why this effect doesn’t break relativity.
 07:45: ... equation, which doesn’t incorporate Einsteins’s special theory of relativity and so has no speed limit baked into ...
 07:57: These new guys use the Dirac equation, which properly incorporates special relativity and so we can take any emerging FTL motion more seriously.
 12:28: All signals in our universe, whether via quantum tunneling or quantum entanglement, seem to be bound by the same limits imposed by relativity.
 12:49: To understand astrophysics, Brilliant believes it helps to have a solid understanding of relativity.
 12:54: Brilliant has a lesson on special relativity that includes interactive challenges and problems to solve.
 13:00: A handson approach can guide you through thinking strategies for challenging subjects like relativity.
 13:06: ... starts out explaining relativity in terms of boats passing by each other on a river, then goes into some ...


20210907: First Detection of Light from Behind a Black Hole
 11:33: ... black hole  30 million Suns  to verifying Einstein’s general theory of relativity. ...


20210707: Electrons DO NOT Spin
 08:28: ...  in this case to make it work with Einstein’s special theory of relativity  something we’ve discussed before. Dirac wasn’t even trying to ...


20210616: Can Space Be Infinitely Divided?
 10:55: ... scale. The nature of space is defined by Einstein’s general relativity, and GR breaks down at the Planck scale because we can’t sensibly ...


20210525: What If (Tiny) Black Holes Are Everywhere?
 00:41: At least, that’s the black hole as it appears in the mathematics of Einstein’s general theory of relativity.
 00:46: But general relativity is NOT the whole picture.
 04:02: Researchers have come up with different hacks for combining general relativity and quantum mechanics and they reached the same conclusion.
 06:48: ... is the sizescale where general relativity and quantum mechanics come into hopeless conflict, and is sometimes ...
 07:04: ... let me start by saying that we know for sure that general relativity doesn’t work on Planck scales, so even if Planck relics do exist they ...


20210511: How To Know If It's Aliens
 14:48: ... warp drives. Good insight. All this warp drive stuff is pure general relativity, and we know for sure that GR is not our final theory of nature because ...


20210421: The NEW Warp Drive Possibilities
 00:31: In 1915, Albert Einstein’s general theory of relativity revealed that the fabric of space and time is mutable and dynamic.
 00:51: And only 15 years after general relativity’s debut, the warp drive was invented, propelling humanity on its first journeys to the stars.
 02:30: His special theory of relativity just says that it takes infinite energy to accelerate anything with positive mass all the way to light speed.
 03:29: It’s a sp acetime geometry that is a valid solution to the equations general theory of relativity. The Einstein Field Equation.


20210413: What If Dark Matter Is Just Black Holes?
 00:44: ... to find holes in Einstein’s theory of gravity  the general theory of relativity  that might explain dark matter’s influence without the need for actual ...


20210323: Zeno's Paradox & The Quantum Zeno Effect
 12:55: ... you’ve enjoyed our recent series on time in general relativity and you want to dig deeper, you should check out Mysteries of Modern ...


20210316: The NEW Crisis in Cosmology
 13:38: ... of light its just one way to interpret the math of special relativity. In relativity, there's this thing called the spacetime interval ...
 17:08: ... Who knew George Lucas was such a jedi master of general relativity. But the whole series makes so much more sense when you ...


20210309: How Does Gravity Affect Light?
 00:28: That fact is guaranteed by Einstein’s general theory of relativity.
 01:52: And yet general relativity demands that gravity does affect light, in ways eerily close to the predictions of Mitchell and Cavendish.
 02:09: In general relativity, the best place to start is always the equivalence principle.
 09:41: As you might expect from a theory called “relativity”, stuff is relative.
 12:22: Relativity is relative  because so is our universe.


20210224: Does Time Cause Gravity?
 00:34: ... it follows as surely as 1+1=2 if we accept the two axioms of Einstein’s relativity theory: that the speed of light is constant for all observers, and that ...
 03:49: In Einstein’s relativity you have to remember that time and space are not independent of each other.
 05:15: There's a certain way of interpreting the math of relativity that says that everything travels at the speed of light.
 07:25: But actually general relativity doesn’t need quantum mechanics to explain gravity.
 07:56: In fact, the imaginary paths of light rays were one the most important tools that helped Einstein develop both special and general relativity.


20210217: Gravitational Wave Background Discovered?
 00:00: ... but dark matter may also not be matter at all it could be that general relativity breaks down at large scales these days most researchers are favoring ...


20210210: How Does Gravity Warp the Flow of Time?
 01:13: Einstein had his happy thought in 1907, a couple of years after he started his scientific revolution with the special theory of relativity.
 01:22: It took him another 8 years and a lot of help to grow this simple idea into his full theory of gravity  the general theory of relativity.
 01:30: General relativity, or “GR” explains the force of gravity as being due to curvature in space and time.
 02:54: It would actually be really helpful if you’ve already seen our recent video on paradoxes in special relativity.
 03:28: This is from special relativity, rather than general relativity, but even special relativity seems a near miraculous insight.
 03:40: But it’s fair to say that relativity was discovered in his own imagination  in his brilliant thought or gedankenexperiments.
 04:48: ... we have to invoke the great founding axiom of special relativity  that the speed of light is always measured to be the same for all ...
 05:30: That’s because there’s no preferred notion of “stillness” in relativity.
 09:25: ... of time between an inertial and accelerating frame using pure special relativity with its kinematic time dilation plus shifting reference frames, OR you ...


20210119: Can We Break the Universe?
 00:09: ... rocking our understanding of the universe with his special theory of relativity. ...
 00:43: ... going to delve into a couple of the most famous paradoxes of special relativity and see why, against our intuition, the universe really does work in ...
 01:09: ... relativity tells us that the clocks on the spaceship will appear to tick more ...
 01:23: But in relativity, every nonaccelerating frame of reference should be considered equal.
 03:13: However the resolution requires us to think about two much more famous paradoxes in relativity  the twin paradox and the ladder paradox.
 04:27: One of the consequences of special relativity is that different observers give different accounts of what events are simultaneous.
 07:38: Doesn’t that violate the fundamental tenet of relativity?
 07:45: Relativity tells us that there’s not a preferred LOCAL frame of reference.
 09:12: The solution to the ladder paradox also relies on the relativity of simultaneity.
 12:01: Relativity is weird, but its seeming paradoxes always have resolutions.


20201222: Navigating with Quantum Entanglement
 12:07: ...  you once asked me a question about space contraction in special relativity and whether or not a spaceship could travel so fast it bumped into its ...
 12:25: Instead I'm going to do a whole episode on some of the weirder paradoxes in relativity, that I think will make it all totally clear.


20201215: The Supernova At The End of Time
 05:27: ... failed to incorporate the effects of Albert Einstein’s relativity theory, which predicted that the world looks very different to things ...
 05:37: And in the extreme density of a white dwarf, electrons would indeed be traveling fast enough for relativity to change the physics.


20201118: The Arrow of Time and How to Reverse It
 00:24: ... realm of quantum mechanics to the cosmic realm of Einstein’s general relativity. But if time doesn’t have a preferred direction in physics, why does time ...


20201111: Can Free Will be Saved in a Deterministic Universe?
 00:25: ... in the context of the block universe idea that we get from Einstein's relativity. ...


20201104: Electroweak Theory and the Origin of the Fundamental Forces
 13:32: ... black hole and at the Big Bang are inevitable if you follow only general relativity. ...
 15:15: Wannabe technician says if they became a general in the army they would definitely change their last name to relativity.
 15:24: Start at Specialist Relativity and work your way up.


20201027: How The Penrose Singularity Theorem Predicts The End of Space Time
 00:34: ... Newtonian gravity was superseded by Einstein’s general theory of relativity. But that wasn’t the end of black holes or dark stars; it was their ...
 03:38: ... 1965 paper produced the first truly new advances in general relativity, half a century after the theory was ...
 04:06: ... into a small enough volume of space. At least according to general relativity. And his singularity theorem succeeded in that  but it succeeded in ...
 04:35: ... of Penrose’s breakthrough, and why it revolutionized general relativity. For a more complete picture I can refer you to a good ...
 05:01: ... literally comes to an end inside a black hole. In general relativity we map the fabric of spacetime with gridlines that we ...
 11:10: ... point to wrongness. They give us the predictions of pure general relativity, and assume the various energy conditions. We know that general ...
 12:11: ... means their are places in the universe where general relativity must break down or produce singularities. Nobelworthy insights, ...
 12:51: ... do that. Last week we continued our discussion of determinism in relativity and the block universe, but this time weaving in what ...


20201020: Is The Future Predetermined By Quantum Mechanics?
 00:00:  Einstein's Special Theory of Relativity combines space and time into one dynamic unified entity, spacetime.
 00:31: In a block universe of Einstein's relativity, there's no way to cleanly define the present and so no way to cleanly separate the future from the past.
 01:47: ... here's the big question, given that relativity is definitely a good description of space and time, what would it take ...
 02:31: Where relativity is the key to understanding the universe of the large and the very fast, we also need to understand the universe of the very tiny.
 02:38: We need to see what quantum mechanics says about determinism and how it plays with relativity and the block universe.
 05:31: So how do these interpretations connect with what relativity tells us about past, future, and present?
 08:03: This interpretation sits a bit better with the relativity of past, present, and future.
 11:27: ... figured out how to make Bohmian mechanics work properly with special relativity. ...
 12:23: ... everyone, last week we introduced the idea of the relativity of simultaneity and the block universe and what this might tell us about ...
 12:42: In Einstein's relativity, the definition of simultaneous events is well, relative.
 13:23: And that's where the relativity of simultaneity connects to eternalism.
 13:51: ... any rate, the relativity of simultaneity doesn't prove eternalism, rather it shows that ...


20201013: Do the Past and Future Exist?
 05:53: ... his special theory of relativity, Einstein showed that there’s no absolute way to define whether two ...
 08:29: ... that’s the effect of Einstein’s special relativity  space and time tilt into each other, so that different observers will ...


20200908: The Truth About Beauty in Physics
 02:41: Einstein’s equations of general relativity give even better precision than Newton’s law  perhaps perfect precision  in their description of gravity.
 02:50: And general relativity is also more explanatory than Newton  it tells us that gravity results from the warping of space and time.
 02:57: Yet the equations of general relativity are notoriously complex.
 07:49: He sought to develop a quantum mechanical wave equation that agreed with Einstein’s special relativity.
 09:39: And then there’s Einstein’s field equations of general relativity.
 10:01: ... couple of years after Einstein presented his general theory of relativity  Weyl found a simple, elegant way to unify Einsteinian gravity with the ...


20200901: How Do We Know What Stars Are Made Of?
 00:39: A hundred years ago, we were starting to plumb the deepest mysteries of the universe with Einstein’s relativity and with quantum theory.
 01:43: ... eclipse expedition in which he verified Einstein’s new general theory of relativity. ...


20200824: Can Future Colliders Break the Standard Model?
 15:06: ... general relativity calculations reveal an event horizon crosssection that’s called the ...


20200817: How Stars Destroy Each Other
 11:45: This conclusion is unavoidable if you’re only using general relativity.


20200810: Theory of Everything Controversies: Livestream
 00:00: ... be at an impasse for the past century after the great revolutions of relativity and quantum mechanics so together with professor brian keating ...


20200728: What is a Theory of Everything: Livestream
 00:00: ... called quantum field theory based upon quantum mechanics and special relativity that so accurately describes everything that goes on at the smallest ...


20200720: The Boundary Between Black Holes & Neutron Stars
 01:04: ... waveform, and based on calculations using Einstein’s general theory of relativity, the masses of those bodies were ...


20200708: Does Antimatter Explain Why There's Something Rather Than Nothing?
 04:48: ... CPT theorem says that, assuming our knowledge of special relativity and the Standard Model are correct, then CPT symmetry must hold. But, we ...


20200622: Building Black Holes in a Lab
 03:26: ... the equations governing the flow of spacetime  the equations of general relativity. And a vortex expressed in those equations of fluid flow resembles a ...


20200527: Does Gravity Require Extra Dimensions?
 01:28: ... general theory of relativity has a perfect track record predicting the behavior of gravity in terms ...


20200518: Mapping the Multiverse
 00:09: ... in english: when you solve Einstein’s equations of general relativity for a rotating black hole, the universe does not come to an abrupt halt ...
 05:33: ... create these maps of spacetime, physicists use the equations of general relativity to trace what we call geodesics  these are the paths that objects take ...
 10:37: ... physics are the same as where you started  at least as far as general relativity is ...
 14:05: ... aether, and so doing paved the way for the acceptance of Einstein's relativity. ...
 14:50: Will that next step be as surprising as relativity and the quantum revolution?


20200511: How Luminiferous Aether Led to Relativity
 01:09: ... aether helped open the way for the acceptance of Einstein’s theory of relativity. ...
 07:06: ... the velocity and direction of motion of the observer. This is Galilean relativity  after Galileo ...
 07:19: ... mechanics. I were a smug 19th century physicist, I’d wanna hope Galilean relativity is right OK, so if light is a classical wave in some medium then we ...
 11:20: ... contradicts Galilean relativity, and so revealed a crack in the sacred Newtonian mechanics. This directly ...
 11:42: ... and the Lorentz transformation are fundamental to his special theory of relativity, which was published 8 years after the MichelsonMorley experiment. Now ...
 13:18: ... of 19th century physics. But that death helped spark the revolutions of relativity and then quantum theory that revealed a much weirder, but still totally ...


20200504: How We Know The Universe is Ancient
 03:09: ... perfect sense in the context of Einstein’s thennew general theory of relativity. ...
 14:21: So, last time we talked wormholes  one of the most awesome entities in general relativity that probably don't exist.
 14:36: ... you into the parallel universe. You can construct a wormhole in general relativity that does not have an event horizon, but you need the nonexistent ...


20200428: Space Time Livestream: Ask Matt Anything
 00:00: ... death of the idea in the late 1900s late 1800s actually in the era of relativity and quantum physics and this is kind of you know Astro 101 except for ...


20200422: Will Wormholes Allow Fast Interstellar Travel?
 00:23: ... discovered a solution to Einstein’s brand new equations of general relativity  a solution that we now understand describes a black hole. But before ...
 07:52: ... how do you design a traversable wormhole? Well, the equations of general relativity permit any smoothlyvarying shape for the fabric of spacetime, and any ...
 09:11: In general, exotic matter violates the socalled energy conditions of general relativity.


20200331: What’s On The Other Side Of A Black Hole?
 01:53: ... just a couple of months after Einstein published his general theory of relativity. It allows us to calculate the path of an object moving in the insane ...
 05:00: ... relativity uses null geodesics  the paths taken by light rays  to grid spacetime, ...


20200324: How Black Holes Spin Space Time
 00:21: ... months after Einstein presented his complete general theory of relativity in 1915, a young German physicist named Karl Schwarzschild was the first ...
 02:56: ... why did it take so long? Well, general relativity is hard, and the spherical symmetry in the Schwarzschild solution ...
 04:26: ... around it. In fact it’s possible to construct a black hole in general relativity rotating or otherwise  without any mass. Warp spacetime so it looks ...


20200316: How Do Quantum States Manifest In The Classical World?
 15:11: ... the incompatibility between the standard model of physics and general relativity And learn what cutting edge science is doing to reconcile these two ...


20200211: Are Axions Dark Matter?
 14:39: ... interpetation of the cosmological equations derived from general relativity tell us that it it may be truly spatially infinite  in which case ...


20200203: Are there Infinite Versions of You?
 12:29: Ilavenya rightly points out that no nice analytical solutions to the 3body problem exist in general relativity  Einstein's modern theory of gravity.
 12:45: ... in fact it's worse than that  forget three bodies, general relativity gives no perfect analytical solutions for TWO bodies in orbit around ...


20200113: How To Capture Black Holes
 00:59: ... black hole mergers themselves were not so surprising. Einstein’s general relativity predicted gravitational waves and astrophysics predicted black hole ...


20191217: Do Black Holes Create New Universes?
 12:29: If you want to understand astrophysics you’re going to need to have a solid understanding of relativity.
 12:36: Brillaint.org has a course on special relativity that includes interactive challenges and problems to solve.
 12:42: ... can guide you through thinking strategies for challenging subjects like relativity. In this course you’ll begin by understanding Einstein’s postulates and ...


20191209: The Doomsday Argument
 16:05: ... for spacetimes that can be constructed within Einstein's general relativity, it's not clear how such a universe would form, and certainly forming a ...


20191202: Is The Universe Finite?
 02:59: Albert Einstein’s general theory of relativity allows for three simple geometries for our universe.


20191118: Can You Observe a Typical Universe?
 13:55: To speed that up, we've linked to your amazing lectures on particle physics and general relativity in the description.


20191111: Does Life Need a Multiverse to Exist?
 01:02: ... the general theory of relativity and the standard model of particle physics, there are something like 20 ...


20191021: Is Time Travel Impossible?
 00:41: ... special and general theories of relativity changed the way we think about time forever, and believe it or not, ...
 00:58: ... first approach to time travel uses only special relativity, which describes how intervals of time and space are stretched or ...
 02:23: ... notice I said “regular mass.” We can hack the equations of special relativity by allowing mass to take values in the weird realm of imaginary or ...
 03:14: So special relativity isn’t much help.
 03:16: ... we still have the general theory of relativity, which incorporates special relativity, but also explains the force of ...
 03:41: A wormhole is a particularly bizarre hypothetical consequence of general relativity.
 06:25: While the actual equations of general relativity themselves don’t prohibit it, there are a set of secondary rules in GR that do.
 08:06: So it turns out that it’s not so hard to find solutions in general relativity with closed timelike curves.
 09:08: Unless it’s an Interstellarstyle black hole . . . general relativity doesn’t directly refute black hole time machine libraries.
 11:36: ... gravity – until then we’re working with the approximate theories general relativity and quantum ...


20191015: Loop Quantum Gravity Explained
 00:28: To connect quantum physics with Einstein’s general theory of relativity.
 01:09: Back in the day we talked about why combining quantum mechanics with general relativity was so hard.
 01:16: ... example, there’s the fact that general relativity  or perhaps quantum mechanics breaks down when we think about the ...
 02:23: General relativity, on the other hand, has to be background independent  because that’s what its equations do  they change the background.
 03:10: ... quantum gravity tries to quantize general relativity with no strings attached, while preserving the background independence ...
 03:20: But why is quantizing general relativity so difficult in the first place?
 05:00: This is completely at odds with general relativity, in which time is treated as just another dimension.
 05:28: The equations of general relativity let you calculate the changing shape of the coordinate system itself, encapsulated in the metric.
 08:07: In the 1950s Einstein himself tried to rewrite general relativity in terms of these parallel transport vector connections, but the result was a mess.
 08:39: Ashketar rewrote general relativity in terms of these spinconnections  now known as Ashketar variables.
 10:03: It’s general relativity – our modern theory of gravity – cast in terms of very abstract building blocks.
 11:01: ... success of loop quantum gravity is that it manages to combine general relativity and quantum mechanics in their currently accepted forms, without taking ...
 11:54: ... to be successful it needs give you the equations of good old general relativity on large, nonquantum scales  in the socalled classical ...
 16:29: ... the answer lies in the Einstein field equation of general relativity That equation says that the amount stretching of spacetime is ...


20191007: Black Hole Harmonics
 05:53: ...  project basically the result of teaching a supercomputer general relativity and, among other things, telling it to collide thousands of black ...
 09:44: General relativity predicts that black holes should be completely defined by three properties – their mass, spin, and electric charge.
 10:43: ... of more black hole mergers, any deviations from the puregeneral relativity, hairless black hole will either become apparent or become less and less ...


20190806: What Caused the Big Bang?
 02:26: First up, the equations of Einstein's general theory of relativity.
 04:38: To see how this could happen we need to move beyond Einstein's general relativity.


20190718: Did Time Start at the Big Bang?
 00:25: ... Slipher, combined with Einstein's  then  brandnew general theory of relativity, revealed that our universe is expanding and if we reverse that expansion ...
 06:02: ... to the singularity We trace a path called a geodesic which in general relativity is the shortest path between two spacetime coordinates These are the ...
 08:14: ... push that theory too far That's what's happening here We used general relativity to rewind the universe, but we already know that despite its incredible ...
 08:52: ... universe behaves in those conditions But we do know that pure general relativity is not a good description and so he probably shouldn't believe its ...


20190620: The Quasar from The Beginning of Time
 07:27: ... to advances in our understanding of general relativity and some mindblowing advances in technology, there are other ways ...


20190617: How Black Holes Kill Galaxies
 11:24: ... and challenging problems so whether you wanna learn about special relativity, quantum physics or brush up on your complex algebra and differential ...


20190509: Why Quantum Computing Requires Quantum Cryptography
 16:30: The Inebriati logs the following: Day 37,736: Einstein still appears to be right about general relativity.


20190501: The Real Science of the EHT Black Hole
 08:55: ... the warped spacetime of a black hole using Einstein’s theory of general relativity. ...
 10:17: ... hole looks just like we predict based on Einstein’s general theory of relativity. ...
 10:27: Eerily so, in fact, given that general relativity was derived over 100 years ago.


20190424: No Dark Matter = Proof of Dark Matter?
 00:03: ... Newton's gravity but also requires modification of Einstein's general relativity over the years various efforts have been made to refine and justify such ...


20190403: The Edge of an Infinite Universe
 02:29: At least the three basic types described by Einstein’s general theory of relativity.
 03:00: In general relativity we call a universe with this geometry de Sitter space, after Dutch astronomer Willem de Sitter.


20190328: Could the Universe End by Tearing Apart Every Atom?
 00:25: ... cosmological constant in the equations of Einstein's general theory of relativity but what if dark energy is not constant what if the energy density in ...
 01:55: ... refresher on how dark energy works in the language of Einstein's general relativity I say refresher because we spent a whole playlist delving into the ...
 12:11: ... regular dark energy. It violates the same energy conditions of general relativity that prohibit negative mass and time ...


20190207: Sound Waves from the Beginning of Time
 14:33: Remember that things like general relativity and much of quantum field theory are verified to stunning precision.


20190130: Perpetual Motion From Negative Mass?
 05:47: ... much more complete description of gravity: Einstein’s general theory of relativity. ...
 05:58: General relativity was, in part, inspired by the equivalence of gravitational and inertial mass.
 06:31: General relativity describes gravity as the warping of the fabric of spacetime.
 07:05: In fact, in pure general relativity, inertial and passive gravitational masses don’t even appear in the equations.
 09:32: It also violates the energy conditions of general relativity.
 09:37: They are a set of conditions against negative energies that seem necessary in order for general relativity to describe a sensible universe.
 10:48: But we also got the same answer thinking about the geodesics in general relativity.
 10:58: ... geodesics of general relativity – the paths carved into the geometry of Einstein’s spacetime – are the ...
 12:23: I’m pretty sure that breaks quantum field theory as well as general relativity.


20190109: Are Dark Matter And Dark Energy The Same?
 02:25: According to Einstein’s general theory of relativity, any such positive energy produces an inwardpulling gravity.
 04:18: The answer is complicated  it’s not always obvious how weird stuff like negative masses translates from general relativity to Newton’s laws.
 08:10: That gives a positive pressure, and in general relativity positive pressure adds an attractive gravitational force, no matter what causes it.
 09:55: Plugging negative masses into general relativity allows you to break causality.


20181220: Why String Theory is Wrong
 00:35: Weyl had tried to explain electromagnetism by imposing on Einstein's general theory of relativity.
 02:35: He was playing around with the newfangled general relativity in five dimensions, 4 space and 1 time, because why not.
 02:43: ... into a 4D component that looks exactly like the familiar general relativity in our universe, plus an extra bit of math from the extra special ...
 14:34: ... of explaining electromagnetism by adding his gauge symmetry to general relativity was wrong, but it inspired the entire field of gauge theory upon which ...
 15:37: ... whether you want to learn about special relativity in quantum physics or brush up on your complex algebra and differential ...


20181212: Quantum Physics in a Mirror Universe
 00:02: ... and challenging problems so whether you want to learn about special relativity quantum physics or brush up on your complex algebra and differential ...


20181107: Why String Theory is Right
 02:50: ... of string theory is immune to the main difficulty in uniting general relativity with quantum ...
 05:22: ... vibrating quantum strings automatically reproduce the theory of general relativity and, in the same mechanism, seem to promise to reproduce all of quantum ...
 06:36: A while ago, we talked about Paul Dirac developed a wave equation for the electron that took into account Einstein's special theory of relativity.
 09:43: Hermann Weyl actually came up with this symmetry right after Einstein proposed his general theory of relativity.
 09:49: He tried to use it to unify general relativity with electromagnetism.


20181010: Computing a Universe Simulation
 11:41: ... understanding of physics, in particular very standard ideas on general relativity and quantum mechanics, to figure out the computational properties of our ...


20181003: How to Detect Extra Dimensions
 04:21: But even there, Einstein's general relativity describes gravity perfectly with three spatial dimensions.
 04:27: In general, general relativity in 3 plus 1 spacetime does a great job at describing gravity in the largescale universe.
 11:16: This ruled out or constrained various alternative theories to general relativity.
 12:23: ... the hardest problem in physics, exploring the conflicts between general relativity and quantum theory towards the development of a theory of quantum ...
 14:43: ... quickfire answers John Gibbs yes, if general relativity and quantum mechanics are both right, then we should have Plancklength ...


20180920: Quantum Gravity and the Hardest Problem in Physics
 00:00: [MUSIC PLAYING] MATT O'DOWD: Between them, general relativity and quantum mechanics seem to describe all of observable reality.
 00:34: First, Einstein's relativity utterly changed the way we think about space, time, motion, and gravity.
 00:47: Together, general relativity and quantum mechanics have allowed us to explain nearly every fundamental phenomenon observed.
 01:29: What exactly are the conflicts between general relativity, or GR, and quantum mechanics?
 01:41: General relativity, GR, is Einstein's great theory of gravity.
 01:56: General relativity incorporates the earlier special relativity, which describes how our perceptions of space and time also depend on motion.
 02:06: ... and time are treated as separate and universal, special and general relativity blend them together into a combined and mutable ...
 02:17: Where general relativity describes the universe of the large and the massive, quantum mechanics talks about the subatomic world.
 03:06: Nowadays, modern quantum field theories fully incorporate the melding of space and time predicted by special relativity.
 03:13: And yet they still don't directly incorporate the warping of space and time predicted by general relativity.
 03:33: ... black holes of pure general relativity swallow information in a way that can remove it completely from the ...
 04:14: Hawking, actually, derived the latter by finding a way to unite general relativity and in quantum field theory.
 04:30: In fact, it's very possible to shoehorn the curved geometry of general relativity into the way quantum field theory deals with space and time.
 06:22: So general relativity plus Heisenberg say it's impossible to measure a length smaller than the Planck length.
 07:41: ... is missing in our description of either quantum theory or general relativity, or both, at the smaller ...
 08:52: In general relativity, the presence of mass or energy warps the gravitational field.
 10:42: None of this works when you try to quantize general relativity.
 11:03: We say that a quantized spacetime of general relativity is nonrenormalizable.
 11:09: The nonrenormalizability of quantized general relativity is connected to the idea that precisely localized particles produce black holes.
 11:27: Generations of physicists, starting with Einstein himself, spent their lives trying to fix this to unite quantum mechanics and general relativity.
 11:46: One is that you search for a way to quantize general relativity in a way that avoids the infinities and nonrenormalizability.


20180905: The Black Hole Entropy Enigma
 00:40: At least they are inevitable according to the equations of Einstein's general theory of relativity.
 01:01: And yet if black holes exist, which apparently they do, they contradict other theories in physics that are as sacred as general relativity.
 06:02: The surface area of a blackhole event horizon can never decrease, at least not according to general relativity.


20180711: Quantum Invariance & The Origin of The Standard Model
 02:03: Newton's laws of motion and gravity, Maxwell's equations for electromagnetism, Einstein's general relativity, and of course, the standard model.
 09:03: First, we need to upgrade the Schrodinger equation to the Dirac equation so it works with Einstein's special relativity.


20180620: The Black Hole Information Paradox
 04:18: After all, without a theory of quantum gravity, Hawking had to hack both general relativity and quantumfield theory to do the calculation.
 05:08: A deeper understanding of general relativity or of quantumfield theory must resolve this.
 05:27: ... a slight modification of general relativity called EinsteinCartan theory, it's predicted that the formation of a ...
 11:44: Einstein's general theory of relativity reveals them to be regions of frozen time and cascading space.


20180613: What Survives Inside A Black Hole?
 03:24: In Einstein's general theory of relativity, we think of the gravitational field as curvature in the fabric of spacetime.
 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.


20180523: Why Quantum Information is Never Destroyed
 12:39: It's worth noting that you didn't really step in to tackle the energy problem that was dogging early general relativity.


20180516: Noether's Theorem and The Symmetries of Reality
 01:03: When it was published in 1915, Einstein's general theory of relativity opened as many questions as it answered.
 01:09: Among them is the fact that energy is not always conserved in general relativity.
 01:34: But the failure of energy conservation was still clear from the math of general relativity.
 01:49: She discovered why the law of conservation of energy broke down in general relativity.
 04:31: That includes the apparent breaking of conservation of energy in general relativity.


20180418: Using Stars to See Gravitational Waves
 02:09: Perhaps these gravitational waves signals were amplified by another phenomenon predicted by Einstein's general relativity, gravitational lensing.
 08:40: ... Einstein was able to derive his general theory of relativity, which predicted the existence of gravitational waves, he had to master ...


20180404: The Unruh Effect
 01:19: To understand this, we don't need general relativity with its spacetime curvature and conflicts with quantum mechanics.
 01:26: We just need a little special relativity and a spacetime diagram.
 05:06: ... system we use to describe a constantly accelerating observer in special relativity, Rindler coordinates, devised by Austrian physicist Wolfgang Rindler who, ...


20180315: Hawking Radiation
 00:34: ... PLAYING] Soon after Einstein revealed his great general theory of relativity in 1915, physicists realized that it allowed for the possibility of ...
 01:31: ... 1975 paper, he attempted a new union of quantum mechanics and general relativity to show that black holes should not be so black after ...
 04:35: To answer that properly, he would need a full union of general relativity and quantum mechanics, a theory of quantum gravity, a theory of everything.
 06:06: But to understand the effect of the close encounter with the black hole, he required an uneasy marriage of quantum mechanics and general relativity.
 11:49: ... scariest monsters of general relativity are ultimately unraveled by the brilliant mind of Stephen Hawking and a ...


20180214: What is Energy?
 09:09: The way it uses energy is inherently consistent with special relativity, unlike Hamiltonian mechanics.
 10:53: ... is generally invalid in the context of Einstein's general theory of relativity due to the potential time evolution of ...


20180117: Horizon Radiation
 00:00: ... the weirdness of quantum mechanics with, well, the weirdness of special relativity, to give quantum field ...
 00:26: [MUSIC PLAYING] Both theories of relativity, special and general, tell us that many things are observer dependent.
 00:54: But relativity can throw some weirder things into the mix, specifically the idea of a horizon.
 03:42: Special relativity is built in.


20171222: Space Time VR
 00:27: Three experiences are out now, and three more covering general relativity, black holes, and the shape of the universe, are on the way for early 2018.


20171102: The Vacuum Catastrophe
 04:52: However, you can't be so cavalier with general relativity.


20170830: White Holes
 00:05: Lurking in the depths of the mathematics of Einstein's general relativity is an object even stranger than the mysterious black hole.
 00:37: ... the idea first emerged from Einstein's general theory of relativity, physicists wondered how seriously to take this mathematical description ...
 02:31: ... a few months after Einstein published his general theory of relativity, Karl Schwarzschild solved its equations for a very particular case a ...
 08:46: It obeys general relativity.
 08:52: Yet general relativity is time reversal symmetric.
 09:12: ... although it's possible to build a white hole in general relativity, there are other laws of physics that the universe needs to obey for ...


20170810: The OneElectron Universe
 04:58: In a quantum field theory that's consistent with Einstein's special relativity, all particles must be symmetric under what we call CPT transformation.


20170802: Dark Flow
 01:20: Galilean relativity tells us that there is no preferred frame of reference to define absolute stillness.


20170712: Solving the Impossible in Quantum Field Theory
 13:23: ... how Feynman's path integral method, which is compatible with special relativity, can derive Schrodinger's equation when Schrodinger's equation is not ...


20170707: Feynman's Infinite Quantum Paths
 04:58: In relativity, it's proportional to the proper time, so the time measured by the clock on a given trajectory.
 08:16: That means it treats space and time symmetrically and so works very naturally with Einstein's theory of special relativity.
 08:23: On the other hand, the Schrodinger equation gave time a special role, so it doesn't work with relativity at all.


20170628: The First Quantum Field Theory
 05:07: Basically, the Schrodinger equation is incompatible with Einstein's relativity.
 05:21: We also saw how Paul Dirac managed to find an equation describing the behavior of the electron that worked with relativity the Dirac equation.
 12:45: ... about the relationship and the conflict between quantum mechanics and relativity, check out the course, The Theory of Everything, by Professor Don Lincoln ...
 14:26: ... "Why was it possible to make quantum mechanics compatible with special relativity when we're still struggling to reconcile it with general relativity?" ...


20170621: AntiMatter and Quantum Relativity
 00:16: Einstein's theory of special and general relativity had changed forever the way we think about motion, space, and time.
 01:40: First and most obvious, the Schrodinger equation is totally incompatible with Einstein's relativity.
 01:47: In relativity, the dimensions of space and time are intrinsically connected and they float into each other as frames of reference change.
 02:06: Relativity tells us that the passage of time depends on velocity.
 04:51: In a way, he started with relativity.
 05:55: It contains the marks of both quantum mechanics, in the Planck constant, and relativity, in the speed of light.
 10:53: ... incredible insight in combining quantum mechanics and relativity reveal an entire flip side of our universe, with its prediction of ...


20170517: Martian Evolution
 13:06: Martin Ketling asks whether a DIY of Arthur Ellington's confirmation of general relativity would be possible.


20170315: Time Crystals!
 09:08: Time crystals could also help bridge the gap between quantum mechanics and general relativity.
 09:21: And unlike in relativity, quantum mechanics treats space and time very differently to each other.


20170215: Telescopes of Tomorrow
 11:10: So last time, I showed you how you can visualize the effects of special relativity on spacetime using geometry.


20170202: The Geometry of Causality
 00:05: The special theory of relativity tells us that one person's past may be another's future.
 00:43: ... to think a little bit more about how the flow of time is described in relativity. ...
 01:04: First, let's recap a little bit of Einstein's special theory of relativity.
 01:16: Special relativity tells us that our experience of both distance and time are, well, relative.
 02:42: In relativity, 3D space and 1D time become a 4D entity called spacetime.
 04:29: ... which time flows, and etched into spacetime by the equations of special relativity. ...


20170125: Why Quasars are so Awesome
 10:35: ... Time builds up to some excellent lectures on the nature of time in relativity, and its behavior around black ...


20170119: The Phantom Singularity
 04:16: ... law gives the wrong answers, and we need Einstein's general theory of relativity, which is the far more complete theory of ...
 04:30: So does general relativity rid us of Newton's pesky singularity?
 05:59: We talk about this in a lot more detail in our relativity playlist.
 11:27: The apparent inevitability of this singularity may be evidence that general relativity is incomplete.


20170104: How to See Black Holes + Kugelblitz Challenge Answer
 04:41: ... of whether they behave as predicted by Einstein's general theory of relativity or whether there are tantalizing ...


20161221: Have They Seen Us?
 16:59: The correct way to get this number is by using general relativity to find the point where the flow of spacetime reaches the speed of light.


20161208: What Happens at the Event Horizon?
 01:07: ... growth, the simplest black hole of Einstein's general theory of relativity purely gravitational, static, and eternal is a subtle and ...
 12:02: It even takes you through the beginnings of Einstein's general relativity.
 16:59: Something I took from this is that Bohmian mechanics is, on its own, very unlikely to be the full picture, even ignoring the whole relativity issue.


20161130: Pilot Wave Theory and Quantum Realism
 10:46: And I don't think anyone could deny that, because it doesn't account for relativity, either special or general.


20161116: Strange Stars
 00:55: Einstein's general theory of relativity tells us that the core of a dead star must collapse under its own incredible weight.


20161109: Did Dark Energy Just Disappear?
 04:14: ... as lambda, is the thing you add to Einstein's equations of general relativity to give the antigravitational effect of dark ...


20161012: Black Holes from the Dawn of Time
 00:35: As long as a volume of space contains a high enough density of mass or energy, general relativity tells us that a black hole will form.


20160921: Quantum Entanglement and the Great BohrEinstein Debate
 03:05: This is fundamental to Einstein's relativity, which tells us that the chain of cause and effect can't propagate any faster than the speed of light.
 09:40: That sounds blasphemous to anyone who accepts Einstein's theory of relativity.
 09:44: However, nonlocality and relativity can actually be perfectly consistent.
 09:50: Relativity requires that causality is preserved, so no faster than light information flow.


20160720: The Future of Gravitational Waves
 03:59: It's kind of amazing that the signals observed look exactly like what we expect them to from the predictions of general relativity.


20160615: The Strange Universe of Gravitational Lensing
 01:27: ... general theory of relativity describes the real universe as a flexible, dynamic dimensional grid that ...
 01:50: The prediction of general relativity that gravity deflects the path of light rays was one of the first to be directly verified.
 02:37: This particular confirmation of general relativity was the one that shot Einstein to his great fame.


20160601: Is Quantum Tunneling Faster than Light?
 08:13: Well, this apparent violation of relativity only occurs deep within the quantum realm.


20160525: Is an Ice Age Coming?
 14:23: Described in general relativity, you can still come up with conserved quantities energy analogies that are invariant in, say, an expanding universe.


20160518: Antigravity and the True Nature of Dark Energy
 00:19: ... take a wild ride with me into the heart of Einstein's general theory of relativity and its description of the vaster of scales of our ...
 01:24: This dark energy is described by the cosmological constant in the equations of general relativity.
 02:25: We saw that general relativity demands this when we looked at the first Friedmann equation.
 04:18: In general relativity, energy slash mass and pressure both curve space time.
 11:43: In a universe governed by general relativity, this is no longer true.


20160427: What Does Dark Energy Really Do?
 00:16: ... fate of the universe can be described using Einstein's general theory of relativity via the Friedmann ...
 11:45: ... when the theory general relativity, in this case is so thoroughly verified in so many other ways, and the ...


20160420: Why the Universe Needs Dark Energy
 00:08: ... called "dark energy." [THEME MUSIC] Einstein's general theory of relativity allows us to describe the behavior of the cosmos on the largest scales ...
 00:52: ... the last episode, we looked at how general relativity, expressed in the first of the two Friedmann equations, can describe the ...
 06:23: Is general relativity wrong?
 12:23: Now, before we do any general relativity MAN: Start again had some eyebrow stuff doing on.


20160413: Will the Universe Expand Forever?
 00:04: This may be the one prediction of general relativity that we never directly verify until, well, the very end.
 00:19: ... MUSIC] Soon after Albert Einstein proposed his general theory of relativity, industrious physicists and, in particular, a brilliant Russian named ...
 01:09: We'll need to peer into the mathematics of general relativity.
 01:33: At the heart of general relativity are the Einstein field equations, which look like this.
 02:16: ... matter tells spacetime how to curve." Now, before we do any general relativity, let's develop intuition a bit by thinking about gravity from a Newtonian ...


20160406: We Are Star Stuff
 12:25: General relativity allows that two patches of space can move apart faster than the speed of light.


20160323: How Cosmic Inflation Flattened the Universe
 06:57: ... the field equations of his general theory of relativity, he added this as a way to allow his theory to describe a static space ...
 07:57: We'll delve pretty deep into how this works in terms of general relativity on a future episode on dark energy.


20160302: What’s Wrong With the Big Bang Theory?
 01:06: ... and in particular running the math of Einstein's general theory of relativity ...
 03:11: ... grand unified theories, except they aren't theories in the same sense as relativity or evolution because we don't know which, if any, are actually ...
 04:20: See, at this point, general relativity comes into serious conflict with quantum mechanics.
 04:46: Remember, we've been rewinding the universe using basic general relativity.
 06:11: ... based on the simplistic expansion you predict from general relativity, when the CMB was released, there just hadn't been enough time for this ...
 07:30: ... together, and then pow, blow it up in size much faster than general relativity would normally ...


20160224: Why the Big Bang Definitely Happened
 01:50: ... the context of Einstein's theory of general relativity, the only sensible interpretation for this fact is that space itself is ...
 02:28: If we rewind the universe using the mathematics of general relativity, then the further back you go, the smaller the universe is.
 02:36: ... fact, with raw general relativity, we get that the entire observable universe was once compacted into an ...
 02:56: While general relativity is incredibly successful, it doesn't contain the machinery to describe the quantum scale gravity of that first speck.
 03:05: So we know that at some point in our rewind, pure general relativity will give us the wrong predictions for the behavior of space time.
 08:55: Brendon Binns asks, given this detection, is the "theory" of general relativity still just a theory?


20160217: Planet X Discovered?? + Challenge Winners!
 03:49: ... see, special relativity tells us that a clock that's moving relative to you will have a slower ...


20160211: LIGO's First Detection of Gravitational Waves!
 00:17: ... these waves is the last major prediction of Einstein's theory of general relativity to be directly verified a century after the theory was first ...
 04:51: Well, everything else aside, it's a great vindication for Einstein's general relativity.
 05:11: Except that now we have the capacity to do detailed tests of general relativity in a regime previously unavailable, in the regime of extreme gravity.


20160127: The Origin of Matter and Time
 00:00: [MUSIC PLAYING] Einstein's theory of special relativity has shown us mass and time are not the concrete things we imagine them to be.
 04:40: ... speed of light, the other fundamental principle of Einstein's special relativity at play here is the Galilean relativity of ...
 10:14: So a lot of you independently realized that the time dilation of special relativity seems to generate a paradox.
 11:03: In this case, it's that special relativity doesn't fully describe the scenario here.
 11:16: And special relativity only describes the relative effects on time and space due to a constant relative motion.
 11:23: To account for the effect of acceleration, you need to use general relativity.


20160120: The Photon Clock Challenge
 00:02: Today we have a special relativity challenge question for you.
 00:35: And the resulting slowing of clock ticks due to motion is the time dilation of Einstein's theory of special relativity.


20160113: When Time Breaks Down
 04:28: This effect is the time dilation of Einstein's special relativity.
 05:35: This is the gravitational time dilation of general relativity.


20160106: The True Nature of Matter and Mass
 06:23: ... we accept Einstein's description of spacetime as described by general relativity, it's not so surprising that the photon box feels the pull of ...


20151209: How to Build a Black Hole
 00:06: To make one, we need both general relativity and quantum mechanics.
 00:37: And really, black holes were, at first, just a strange construction of general relativity.


20151125: 100 Years of Relativity + Challenge Winners!
 00:24: ... in 1915, Albert Einstein first presented his complete theory of general relativity to the Prussian Academy of Sciences in Berlin, completely changing the ...
 00:36: ... is an essential part of what inspires us here at "Space Time." General relativity's profound description of space and time, of matter and energy, emerged ...


20151028: Is The Alcubierre Warp Drive Possible?
 00:45: ... warp field in the mathematical language of Einstein's theory of general relativity, a real solution to the equations of GR that would actually allow faster ...
 01:34: However, according to general relativity, there's no limit on the relative speeds of two separate patches of spacetime.


20151022: Have Gravitational Waves Been Discovered?!?
 00:03: Gravitational waves are the last prediction of Einstein's Theory of General Relativity.
 00:22: It has a lot to do with his revolutionary Theory of General Relativity, in which he showed us that the force of gravity is an illusion.
 00:37: Now it turns out that General Relativity makes predictions far beyond the familiar gravity.
 04:36: And the results agreed exactly with the rates of gravitational radiation predicted by General Relativity.


20151007: The Speed of Light is NOT About Light
 01:21: But in his book, there's another, less well known idea his Principle of Relativity.
 01:25: This is not Einstein's Relativity, but, instead, the brilliant precursor.
 01:46: This Galilean Relativity is an incredible insight that Isaac Newton would later codify into his Laws of Motion.
 02:31: And more importantly for this episode, Maxwell's equations had cast confusion on the sacred Galilean Relativity.
 05:14: And it was discovered even before Einstein's Relativity.
 07:05: It's the only one that satisfies all of these pretty fundamental statements about the relativity, symmetry, and consistency of our universe.
 07:40: And honestly, just from the symmetry and relativity arguments that we made, c could be infinity.
 09:19: ... the meaning of the Lorentz transformation gives us the special theory of relativity time dilation, length contraction, and, of course, mass to energy ...


20150930: What Happens At The Edge Of The Universe?
 00:32: The universe is infinite because general relativity tells us that the universe is demonstrably flat and therefore the galaxies go on forever.
 07:07: In addition, although general relativity is pretty cool, it's not a theory of everything.
 07:36: ... it's contradictory or circular to use Einstein's theory of general relativity to prove ...
 07:58: And there are few theories with as many independent and accurate predictions as general relativity.


20150923: Does Dark Matter BREAK Physics?
 00:56: Thanks to general relativity, we know that light fall is the curved geodesics of a gravitational field.
 01:57: So general relativity, wrong.
 04:05: The original modified Newtonian dynamics hypothesis, and it's a general relativity extensions, tries to give us this basic relationship for gravity.
 04:17: But you can't just break general relativity and start over.


20150827: Watch THIS! (New Host + Challenge Winners)
 04:49: And that's doubly true in general relativity, where the ground is always shifting under your feet.
 05:00: Some of you might be daunted by the general relativity solution.


20150819: Do Events Inside Black Holes Happen?
 00:13: [THEME MUSIC] Today's episode, we'll only talk about black holes from the perspective of classical general relativity.
 00:50: So if you need a refresher, go watch our relativity playlist.
 07:25: In general relativity, remember, gravity is not a force at all.
 10:57: I'm not sure what the right answer is to interpretational questions like this or even if there is a right answer in vanilla general relativity.


20150812: Challenge: Which Particle Wins This Race?
 00:30: No spacetime, no relativity.
 04:21: Now this question can also be answered, but now you need some knowledge of general relativity, and you need calculus.


20150805: What Physics Teachers Get Wrong About Tides!
 09:10: Last week, we finished our series on general relativity and curved spacetime.
 10:33: ... something different when you talk about the quantum version of general relativity. ...
 10:44: ... large scale things and you get pretty good agreement with general relativity ...
 11:26: You can look up something called KaluzaKlein theory, which is a way of trying to get a geometric version of electromagnetism plus general relativity.
 12:21: ... to be inertial and then you work out what the equations of general relativity say the geodesics should be around the Earth and you down project them ...
 14:48: Iwon't tellmyname was asking what courses he would need to take to learn about general relativity.


20150729: General Relativity & Curved Spacetime Explained!
 00:04: A synopsis of general relativity that builds on these previous four episodes.
 05:21: ... we haven't fully fleshed out all of general relativity yet, but there's one experimental fact that I can use to show you that ...
 08:32: ... even when people are referring to relativity or string theory or whatever, it's just a lot easier to say the word ...


20150722: SPECIAL ANNOUNCEMENT + Flat Spacetime Geometry Comments
 00:03: Last week, part 2 of our general relativity series went a little deeper into some aspects of flat space time geometry.
 04:24: It is tricky to talk about the car's frame of reference in special relativity.


20150715: Can You Trust Your Eyes in Spacetime?
 00:02: But before we can graduate to the curves version and general relativity, we need a stronger foundation in spacetime geometry.
 01:07: Now, we're not going to do a complete treatment of special relativity or all aspects of flat spacetime geometry.


20150708: Curvature Demonstrated + Comments
 00:09: That material is really important to get down visually before we move on to the rest of the relativity series.


20150702: Can a Circle Be a Straight Line?
 00:16: ... general relativity, objects that fall or orbit aren't being pulled by a gravitational force, ...
 07:57: You should watch as many videos about special relativity as you can no matter who's made them.


20150624: The Calendar, Australia & White Christmas
 07:22: And finally, to everyone who's been clamoring for another general relativity episode, tune in next week.


20150617: How to Signal Aliens
 08:26: Lexis lex asked whether all frames are inertial in GR or even if the concept of inertial frame is an incoherent in general relativity.


20150603: Is Gravity An Illusion?
 00:42: ... and how it planted the seeds for what would eventually become general relativity. ...
 09:16: But once he did, a beautiful model of the world emerged called general relativity.
 09:26: And one of the central precepts of general relativity is that we inhabit the curved spacetime.


20150527: Habitable Exoplanets Debunked!
 09:38: The bottom line answer is that in general relativity, there actually is no such thing as energy conservation for the universe as a whole.
 09:50: But general relativity is quirky like that.


20150520: The Real Meaning of E=mc²
 03:08: This all gets a little bit more complicated in general relativity, but we'll deal with that another time.


20150513: 9 NASA Technologies Shaping YOUR Future
 06:50: ... "Spacetime." Second, in next week's episode I'll be explaining some more relativity ...


20150429: What's the Most Realistic Artificial Gravity in SciFi?
 10:17: And it's because that discussion is way more involved, especially in the context of relativity.
 10:26: But yes, I happen to think that special relativity suggests that free will is an illusion.


20150422: Are Space and Time An Illusion?
 04:13: ... shortly after relativity first came out, a former math professor of Einstein's named Hermann ...
 06:47: ... general relativity entered the mix, we'll find that there are many possible spacetimes with ...
