YouSaid · the spoken record

Sean Carroll

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2024-04-22
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2024-04-22
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  1. “Yeah, I mean, it's a good question. One of the things that quantum field theory indirectly suggests is that there's not that much information in you and me compared to the volume of spacetime we take up. As far as quantum field theory is concerned, you and I are mostly empty space.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  2. “The idea that information is sort of encoded on a boundary really came into its own was with Juan Maldesena in the 1990s and the ADS CFD correspondence, which we don't have to get into that into any detail, but it's a whole full-blown theory, it's two different theories. One theory in n dimensions of spacetime without gravity and another theory in n plus one dimensions of spacetime with gravity. And the idea is that this n-dimensional theory is casting a hologram into the n plus 1 dimensional universe to make it look like it has gravity. And that's holography with a vengeance. That's an enormous source of interest for theoretical physicists these days.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  3. “Yeah, ideas. Exploration of ideas. But anyway, what I was trying to get at was Suskin and also a Toft were a little vague. They were a little hand wavy about holography and what it meant, where holography”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  4. “That idea just told you was the original holographic principle put forward by people like Gerard de Tuft and Leonard Suskind, superfamous physicist. Leonard Suskind was on my podcast and gave a great talk. He's very, very good at explaining these things.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  5. “So people thought about that in both deep and superficial ways for a long time, and they proposed what we now call the holographic principle that the way that spacetime in quantum gravity convey information or hold information is not different bits or qubits for quantum information at every point in space-time. It is something holographic, which means it's sort of embedded in or located in or can be thought of as pertaining to one dimension less of the three dimensions of space that we live in. So in the case of the black hole, the event horizon is two-dimensional, embedded in a three-dimensional universe, and the holographic principle would say all of the information contained in the black hole can be thought of as living on the event horizon rather than in the interior of the black hole. I need to say one more thing about that, which is that this was an idea.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  6. “You might expect if I have a box and I'm going to put information in it. And I don't tell you how I'm going to put the information in, but I ask, how does the information I can put in scale with the size of the box? You might think, well, it goes as the volume of the box because the information takes up some volume and I can only fit in a certain amount. And that is what you might guess for the black hole, but it's not what the answer is. The answer is that the maximum information as reflected in the black hole entropy scales as the area of the black hole's event horizon, not the volume inside.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  7. “Well, it goes back to this question that we were talking about with the information and how it gets out. In quantum mechanics, certainly, arguably even before quantum mechanics comes along in classical statistical mechanics, there's a relationship between information and entropy. Entropy is my favorite thing to talk about. I've written books about, and we'll continue to write books about. So Hawking tells us that black holes have entropy. And it's a finite amount of entropy. It's not an infinite amount. But the belief is, and now we're already getting quite speculative, the belief is that the entropy of a black hole is the largest amount of entropy that you can have in a region of spacetime. It's sort of the most densely packed that entropy can be. And what that means is there's sort of a maximum amount of information that you can fit into that region of space and you call it a black hole.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  8. “I think, I mean, I'm in favor of this kind of humility, this intellectual humility that we won't know because we should be prepared for surprises. But I do always keep coming back to the idea that we all live in the same physical universe. And if... Well, let's put it this way. The development of our intelligence has certainly been connected to our ability to manipulate the physical world around us. And so I would guess without 100% credence by any means, but my guess would be that in any advanced kind of life would also have that capability. Both dolphins and octopuses are potential counter examples to that. But I think in the details there would be enough similarities that we would recognize it.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  9. “Well, again, if it's intelligent and technologically advanced, the more short-term question of if we get some spectroscopic data from an exoplanet, so we know a little bit about what is in its atmosphere. How can we judge whether or not that atmosphere is giving us a signature of life existing? That's a very hard question that people are debating about. I mean, one very simple-minded, but perhaps interesting approach is to say, Small molecules don't tell you anything because even if life could make them, something else could also make them. But long molecules, that's the kind of thing that life would produce.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  10. “I think we would figure out that language thing Pretty quickly. I mean, maybe not as quickly as we do when different human tribes find each other, because obviously there's a lot of commonalities in humanity. But there is logic and math, and there is the physical world. You can point to a rock and go rock. I don't think it would take that long. I know that arrival, the movie, based on a Ted Chang story, suggested that the way that aliens communicate is going to be fundamentally different. But also they had recognition and other things. I don't believe in. So I think that if we actually find aliens, that will not be our long-term problem.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  11. “Sort of quiescent alien artifact in our solar system than I would to catch a radio signal from an intelligent civilization.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  12. “That's not a very promising way to find intelligent life elsewhere because why in the world would a super intelligent alien civilization waste all of his energy by beaming it in random directions into the sky? For one thing, it just passes you by, right? So if we're here on Earth, we've only been listening to radio waves for a couple hundred years. If an intelligent alien civilization exists for a billion years, they have to pinpoint exactly the right time to send us this signal. It is much, much more efficient to send probes and to park, to go to the other solar systems, just sit there and wait for an intelligent civilization to arise in that solar system. This is kind of the 2001 monolith hypothesis, right? I would be less surprised to find”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  13. “Yes, and what you should do. So, if you want the optimistic spin, here's the optimistic spin People looking for intelligent life elsewhere often tune in with their radio telescopes, right? At least we did before Arecibo was decommissioned.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  14. “That is absolutely possible. I'm actually putting less credence on that one just because you need to happen every single time, right? If even one, I mean, this goes back to von Neumann pointing, John von Neumann pointed out that you don't need to send the aliens around the galaxy. You can build self-reproducing probes and send them around the galaxy. And you might think, well, the galaxy is very big. It's really not. It's some tens of thousands of light years across. And billions of years old. So you don't need to move at a high fraction the speed of light to fill the galaxy.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  15. “I don't believe that very strongly. Look, I'm not going to place a lot of bets here. I would not, I'm both pretty up in the air about whether or not life itself is all over the place. It's possible when we visit other worlds, other solar systems. There's very tiny microscopic life ubiquitous, but none of it has reached some complex form. It's also possible there's just there isn't any. It's also possible that there are intelligent civilizations that have better things to do than knock on our doors. So I think we should be very humble about these things we know so little about.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  16. “I mean, I get it. I get exactly what you're thinking. I think it's a perfectly reasonable. Attitude to have before you confront the data. I would not have expected Earth to be special in any way. I would have expected there to be plenty of very noticeable extraterrestrial civilizations out there. But even if life finds a way, even if we buy everything you say, how long does it take for life to find a way? What if it typically takes 100 billion years, then we'd be alone?”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  17. “Yeah, I have no idea, but I think. Your intuition is right that it would have been easy for there to be lots of civilizations, and then we would have noticed them already. And we haven't. So absolutely the simplest explanation for why we haven't is that they're not there”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  18. “I think that's fair. Yeah. It's always interesting when something is difficult but happens anyway, right? I mean, the probability of making a black hole could have been zero. It could have been one, but it's this interesting number between, which is kind of fun.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  19. “I love them. I love black holes. But the universe weirdly makes it hard to make a black hole, right? Because you really need to squeeze an enormous amount of matter and energy into a very, very small region of space. So we know how to make stellar black holes, a supermassive star can collapse to make a black hole. We know we also have these supermassive black holes at the center of a galaxy. We're a little unclear where they came from. I mean, maybe stellar black holes that got together and combined, but that's one of the exciting things about new data from the James Webb Space Telescope is that quite large black holes seem to exist relatively early in the history of the universe. So it was already difficult to figure out where they came from. Now is an even tougher puzzle.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  20. “So, you don't want them to be too tiny or they're exploding, right? They're very bright and then they will be visible. But there's an absolutely regime where black holes are large enough not to be visible because the larger ones are fainter, right? Not giving off radiation, but small enough to not be detected through their gravitational effect. Yeah.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  21. “Right now, we are nowhere close to observing Hawking radiation. Here is the sad fact. The larger the black hole is, the lower its temperature is. So, a small black hole, like a microscopically small black hole, might be very visible. It's given off light, but something like the black hole in the center of our galaxy, three million times the mass of the sun or something like that, Sagittarius A star, that is so cold and low temperature that its radiation will never be observable. Black holes are hard to make. We don't have any nearbying. The ones we have out there in the universe are very, very faint. So there's no immediate hope for detecting Hawking radiation.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  22. “So either that information is destroyed, like you said, or it is somehow transferred to the radiation that is coming out, to the Hawking radiation. The large majority of people who think about this believe that the information is somehow transferred to the radiation and information is conserved. That is a feature both of general relativity by itself and of quantum mechanics by itself. So when you put them together, that should still be a feature. We don't know that for sure. There are people who have doubted it, including Stephen Hawking, for a long time. But that's what most people think. And so what we're trying to do now in a topic which has generated many, many hundreds of papers called The Black Hole Information Loss Puzzle is figure out how to get the information from you or the book into the radiation that is escaping the black hole.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  23. “Well, you've raised a crucially difficult point. So. That's why I keep needing to distinguish between black holes according to Einstein's theory of general relativity, which is book one of spacetime and geometry, which is perfectly classical. And then come the 1970s. We start asking about quantum mechanics and what happens in quantum mechanics. According to classical general relativity, the information that makes up u when you fall into the black hole is lost to the outside world. It's there, it's inside the black hole, but we can't get it anymore. In the 1970s, Stephen Hawking comes along and points out that black holes radiate. They give off photons and other particles to the universe around them. And as they radiate, they lose mass, and eventually they evaporate. They disappear. So once that happens, I can no longer say the information about you or a book that I threw in the black hole or whatever is still there as hidden behind the black hole because the black hole has gone away.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  24. “Literally the equivalent of escaping a black hole would be moving faster than the speed of light. They're both precisely equally difficult. You would have to move faster than the speed of light to escape from the black hole. So once you're in, that's fine. In principle, you don't even notice when you cross the event horizon, as we call it. The event horizon is that point of no return, where once you're inside, you can't leave. But meanwhile, the space-time is sort of collapsing around you to ultimately a singularity in your future, which means that the gravitational forces are so strong. They tear your body apart, and you will die in a finite amount of time. The time it takes, if the black hole is about the mass of the sun to go from the event horizon to the singularity takes about one millionth of a second.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  25. “It's best to think of a black hole as not an object so much as a region of spacetime. It's a region with the property, at least in classical general relativity, quantum mechanics makes everything harder, but let's imagine we're being classical for the moment. It's a region of spacetime with the property that if you enter, you can't leave.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  26. “It is absolutely hard to imagine, and a black hole is very different in many ways from what we're used to. On the other hand, I mean, the real reason, of course, is that between 1915 and 1955, there's a bunch of other things that are really interesting going on in physics, all of particle physics and quantum field theory. So many of the greatest minds were focused on that. But still, if the universe hands you a solution to general relativity in terms of curved spacetime, and it's kind of mysterious, certain features of it, I would put some effort into trying to figure it out.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  27. “Derives the solution to Einstein's equation that represents a black hole, the short shield solution. No one recognized it for what it was until the fifties, David Finkelstein and other people. And that's just one of these examples of physicists not being as clever as they should have been.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  28. “We don't, I mean, how would we? Because it's always possible that right at the last minute it had a change if heart and starts accelerating away, right? If you don't see it pass in, you don't know. And let's point out that as smart as Einstein was, he never figured out black holes. And he could have. It's kind of embarrassing. It took decades for people thinking about general relativity to understand that there are such things as black holes. Because basically Einstein comes up with general relativity in 1915. Two years later, Schwartzshield, Carl Schwartz,”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  29. “It's not like I'm equally bright. I basically fade from view in that picture. Okay, so that's one approximation. The other approximation is I do have a gravitational field of my own. And therefore, as I approach the black hole, the black hole doesn't just sit there and let me pass through. It kind of moves out to eat me up because its net energy mass is going to be mine plus its. Roughly speaking, yes, I think so I don't like to go to the dramatic extremes because that's where the approximations break down. But if you see something falling into a black hole, you see its clock ticking more and more slowly.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  30. “Yes and no. It depends on exactly how careful we are being. So here's a bunch of things I think are correct. So like the whole solution Einstein's equation and you treat you and me as what we call test particles. So we don't have any gravitational fields ourselves. We just move around in the gravitational field. And that's obviously an approximation, okay? But let's imagine that. And you stand outside the black hole and I fall in. And as I'm falling in, I'm waving to you, you know, because I'm going into the black hole, you will see me move more and more slowly and also the light from me is redshifted. So I kind of look embarrassed because I'm falling into a black hole. And there is a limit. There's a last moment that light will be emitted from me from your perspective forever. Now, you don't literally see it because I'm emitting photons more and more slowly, right? Because from your point of view.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  31. “But I do think that people kind of are a little overly casual about the relationship between what we observe and objective reality in the following sense. Of course, in order to explain the world, our starting point and our ending point is our observations, our experimental input, the phenomena we experience and see around us in the world. But in between, there's a theory. There's a mathematical formalization of our idea. And if a theory fits the data and is very simple and makes sense in its own terms, then we say that the theory is right. And that means that we should attribute some reality to the entities that play an important role in that theory, at least provisionally until we come up with a better theory down the road.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  32. “If you have a curve in time, which is, by the way, literally all of our lives, right? We all evolve in time. So you can start with one event in spacetime and another event in space-time. What Minkowski points out is that the time you measure along your trajectory in the universe is precisely analogous to the distance you travel on a curve through space. And by precisely I mean, it is also true that the actual distance you travel through depends on your path and go straight lines, shortest distance, you can curb line to be longer, the time you measure in spacetime, the literal time that ticks off in your clock, also depends on your path. But it depends on it the other way so that the longest time between two points is a straight line. And if you zig back and forth in space-time, you take less and less time to go from point A to point B.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  33. “There is almost no difference. There's one difference that is kind of important, which is the following. If you have a curve in space, I'm going to draw it horizontally because that's usually what we do in spacetime diagrams. If you have a curve in space, you've heard the motto before that the shortest distance between two points is a straight line.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  34. “Oh, yeah, all the time. I mean, we, of course, make our lives easy by ignoring two of the dimensions of space. So instead of four-dimensional space-time, we just draw pictures of one dimension of space, one dimension of time, the so-called spacetime diagram. But, you know, I mean, maybe this is lurking underneath your question, but even the best physicists will draw a vertical axis and a horizontal axis and they'll go space, time. But deep down, that's wrong because you're sort of preferring one direction of space and one direction of time. And it's really the whole two-dimensional thing that is spacetime. The more legitimate thing to draw on that picture are rays of light, our light cones from every point there is a fixed direction at which the speed of light would represent. And that is actually inherent in the structure. The division into space and time.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  35. “I honestly don't know what was going through Minkowski's mind when he thought that I'm not sure if he was so mathematically adept that it was just clear to him or he was really struggling it and he did trial and error for a while. I'm not sure.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  36. “Certainly not simple actually. It's a profound insight. That's why I said I think we should give Minkowski more credit than we do. You know, he's the one who really put the finishing touches on special relativity. Again, many people had talked about how things change when you move closer to the speed of light, what Maxwell's equations of electromagnetism predict and so forth, what their symmetries are. So people like Lorentz and Fitzgerald and Planck Array, there's a story that goes there. And the usual telling, Einstein sort of puts the capstone on it. He's the one who says, all of this makes much more sense if there just is no ether. It is undetectable. We don't know how fast everything is relative. Thus, the name relativity. But he didn't take the actual final step, which was to realize that the underlying structure that he had invented is best thought of as unifying space and time together.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  37. “Leap he makes is, oh, it's because it's the curvature of spacetime, right? It's a feature of spacetime, it's not a force on top of it, and the feature that it is is curvature. And then finally, he says, okay, clearly I'm going to need the mathematical tools necessary to describe curvature. I don't know them, so I will learn them. And they didn't have MOOCs or AI helpers back in those days. He had to sit down and read the math papers, and he taught himself differential geometry and invented general relativity.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  38. “Accelerating at 1G, at 1 acceleration due to gravity, if the rocket ship were very quiet, you wouldn't be able to know the difference between being in a rocket ship and being on the surface of the Earth. Gravity is sort of not detectable, or at least not distinguishable from acceleration. So number one, that's a pretty clever thing to think. But number two, if you or I had had that thought, we would have gone, huh, we're pretty clever. He reasons from there to say, okay, if gravity is not detectable, then it can't be like an ordinary force, right? The electromagnetic force is detectable. We can put charged particles around, positively charged particles and negatively charged particles respond differently to an electric field or to a magnetic field. He realizes that what his thought experiment showed, or at least suggested, is that gravity isn't like that. Everything responds in the same way to gravity. How could that be the case? And then this other...”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  39. “Relativistic theories of gravity, but he really applied himself to it. And I think as your question suggests, the solution was not a matter of turning a crank. It was something fundamentally creative. You know, in his own telling of the story, his greatest moment, his happiest moment was when he realized that the way that we would modern and say it in modern terms, if you were in a rocket ship.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  40. “Brownie in motion is another one, which is just, you know, the little vibrations of tiny little dust specks in the air. But who cares about that? What matters is it proves the existence of atoms. He explains Brownie in motion by imagining their molecules in the air and deriving their properties. Brilliant. And then he basically starts the world on the road to quantum mechanics with his paper on, which again is given a boring label of the photoelectric effect. What it really was is he invented photons. He showed that light should be thought of as particles as well as waves. And he did all three of those very different things in one year. Okay. But the other thing that gets him genius status is, like you say, general relativity. So this takes 10 years from 1905 to 1915. He wasn't only doing general relativity. He was working on other things. He wrote, he invented a refrigerator. He did various interesting things. And he wasn't even the only one working on the problem. There were other people who suggested.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  41. “Consider space time together and to imagine that there's a curvature to this whole thing. Yeah, that's a great question. I think that if you want to make the case for Einstein's greatness, which is not hard to do, there's two things you point at. One is in 1905, his famous miracle year, he writes three different papers on three wildly different subjects, all of which would make you famous just for writing that one paper special relativity is one of them.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  42. “Did what he achieved in trying to think these problems through is to really basically understand the idea of quantum entanglement, which is kind of important these days when it comes to understanding quantum mechanics. Now it's true that in the 40s and 50s he placed his efforts in hopes for unifying electricity and magnetism with gravity that didn't really work out very well. All of us try things that don't work out. I don't hold that against him. But in terms of IQ points, in terms of trying to be a clear thinking physicist, he was really, really great. What does greatness look like for a physicist? So how difficult is it? Take the leap from special relativity to general relativity. How difficult is it to imagine that”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  43. “You say that Einstein is a better physicist than he gets credit for. I know that's hard. That's a little bit of a joke there, right? Because we all give Einstein a lot of credit. But then we also partly based on fact, but partly to make ourselves feel better, tell ourselves a story about how later in life Einstein couldn't keep up. There were younger people doing quantum mechanics and quantum field theory and particle physics, and he was just sort of unable to really philosophically get over his objections to that. And I think that that story about the latter part is completely wrong. Like almost 180 degrees wrong. I think that Einstein understood quantum mechanics as well as anyone, at least up through the 1930s. I think that his philosophical objections to it are correct. So he should actually have been taken much more seriously about that. And what he...”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  44. “If space-time is a thing, it can have properties, and in particular it can have a geometry, it can be curved from place to place, and that was what let him solve the problem of gravity. He was always he had previously been trying to fit in what we knew about gravity from Newtonian mechanics, the inverse square law of gravity, to his new relativistic theory. It didn't work. So the final leap was to say gravity is the curvature of spacetime. And that statement is basically general relativity. And the tension with Minkowski was he was a mathematician. Yes. So it's the tension between physics and mathematics. In fact, in your lecture about this equation, one of them.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  45. “Then it was Minkowski who used to be Einstein's professor in 1907 who realized the most elegant way of thinking about this idea of Einstein's was to blend space and time together into spacetime, to really imagine that there is no hard and fast division of the four-dimensional world in which we live into space and time separately. Einstein was at first dismissive of this. He thought it was just like, oh, the mathematicians are overformalizing again. But then he later realized that”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  46. “In Book I of the series The Biggest Ideas in the Universe called Space Time Motion, you take on classical mechanics, general relativity by taking on the main equation of general relativity and making it accessible, easy to understand. So maybe at the high level, what is general relativity? What's a good way to start to try to explain it? Probably the best way to start to try to explain it is special relativity, which came first, 1905. It was the culmination, right, of many decades of people putting things together, but it was Einstein in 1905. In fact, it wasn't even Einstein. I should give more credit to Minkowski in 1907. So Einstein in 1905 figured out that you could get rid of the ether, the idea of a rest frame for the universe, and all the equations of physics would make sense with the speed of light being a maximum.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  47. “How you have the difficult components of the company finding a common language that manages all the stuff, the HR, the financial, the banary supply, e-commerce, all that kind of stuff. Over 37,000 companies have upgraded to NetSuite by Oracle, take advantage of NetSuite's flexible financing plan at NetSuite dot com slash lex. That's netsuite dot com slash lex. This is Alex Friedman podcast. To support it, please check out our sponsors in the description. And now, dear friends, here Sean Carroll.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  48. “This episode is brought to you by NetSweet, an all in one cloud, business management system. I have to be honest and say that there's a big part of me that enjoys working at a company at a large company and sort of being an individual contributor in a larger system of people working together. Like being an individual contributor on a great team is really fun for me. And one of the things I miss having left Google and to go to MIT and now spending quite a bit of time outside of MIT, all of that, I just miss large teams working together on a big mission. There's a beauty to that. There's a camaraderie to that. There's a celebration of the best of humanity in that because that's how we create special things is a large number of humans working together. And there is a science, there's an art to running a large company. I think that's what NetSuite tackles is.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  49. “I think I have a Bikowski shirt, book shirts, like a Frankenstein shirt that is really cool. It has some funny shirts like Carl Young, Forever Young, all that kind of stuff. Anyway, if you have shirts like this, you can create a Shopify store, sell them, and spread joy into the world, but you can sell really anything, and they integrate with a bunch of third-party apps that make all of that super easy. Sign up for a $1 per month trial period at Shopify dot com slash Lex. That's all lowercase. Go to Shopify. comtake your business to the next level today.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  50. “The great looking online store. I have a store set up at Lexstreama.com store. I should probably put on more stuff there, more shirts. Because shirts are fun. I love wearing shirts. Actually, tweet at me or whatever if you know cool shirt places. Basically most of the time what I wear is either suit and tie or a black shirt and jeans. But I also love owning shirts that represents something that I enjoy. So for example, I have a bunch of Metallica shirts, so a bunch of shirts of the different bands I like. You know, lots of classic rock, Jimmy Hendrix, Led Zeppelin, Pink Floyd.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source