Pod Insights Lex Fridman Podcast #468 – Janna Levin: Black Holes, Wormholes, Aliens, Paradoxes & Extra Dimensions About this episode Janna Levin is a theoretical physicist and cosmologist specializing in black holes, cosmology of extra dimensions, topology of the universe, and gravitational waves.
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OUTLINE:
(00:00) – Introduction
(00:51) – Sponsors, Comments, and Reflections
(09:21) – Black holes
(16:55) – Formation of black holes
(27:45) – Oppenheimer and the Atomic Bomb
(34:08) – Inside the black hole
(47:10) – Supermassive black holes
(50:39) – Physics of spacetime
(53:42) – General relativity
(59:13) – Gravity
(1:15:47) – Information paradox
(1:24:17) – Fuzzballs & soft hair
(1:27:28) – ER = EPR
(1:34:07) – Firewall
(1:42:59) – Extra dimensions
(1:45:24) – Aliens
(2:01:00) – Wormholes
(2:11:57) – Dark matter and dark energy
(2:22:00) – Gravitational waves
(2:34:08) – Alan Turing and Kurt Godel
(2:46:23) – Grigori Perelman, Andrew Wiles, and Terence Tao
(2:52:58) – Art and science
(3:02:37) – The biggest mystery
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Transcript 30,230 words · 2 speakers
Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.
0:00 Lex Fridman? The following is a conversation with Janna Levin, a theoretical physicist and cosmologist specializing in black holes, cosmology of extra dimensions, topology of the universe, and gravitational waves in spacetime. She has also written some incredible books, including How the Universe Got Its Spots, on the topic of the shape and the size of the universe, A Mad Man Dreams of Touring Machines, on the topic of genius, madness, and the limits of knowledge, Black Hole Blues, and other songs from Outer Space, on the topic of LIGO and the detection of gravitational waves, and Black Hole Survival Guide, all about black holes.
0:45 Lex Fridman? This was a fun and fascinating conversation.
0:51 Lex Fridman? And now, a quick few-second mention of each sponsor. Check them out in the description. It's the best way to support this podcast. We've got Brain FM for focus, Better Health for mental health, NetSuite for your business, Shopify for selling stuff, and AG1 for your health. Choose wisely, my friends. I do these longer ad reads up in the beginning. I try to make them interesting, but I do also make it super easy to skip with timestamps on the screen and in the description. I do, however, try to make them personal, often related to stuff I'm reading or thinking about. Also, if you want to get in touch with me, for whatever reason, go to lexfridman.com/contact. And now, onto the full ad reads. Let's go.
1:34 Lex Fridman? This episode is brought to you by Brain.fm, a platform that offers music specially made for focus. And when I say music, I mean audio experience. If you ever see me out in the wild, like at Starbucks, I'm usually either writing or programming, deeply in focus with headphones. In those headphones are layers of audio, a mixture of some noise, beats, rain, layers, many layers that help me deeply, deeply, deeply focus.
2:13 Lex Fridman? Speaking of audio, did you know that the Roman Empire used synchronized war drums to coordinate legions? Just imagine the sound of those drums. I need to do a lot more episodes on ancient Rome, on ancient Greece, on ancient China. Anyway, now listening to war drums. I'm listening to Brain FM when I'm focusing. You too can increase your focus and try brain.fm free for 30 days by going to brain.fm/lex. That's brain.fm/lex for 30 days free. This episode is also brought to you by BetterHelp, spelled H E L P. Help.
2:57 Lex Fridman? It's raining outside, thunderstorms, like somebody's knocking on the window. If that's not a metaphor for prodding the subconscious mind, I don't know what is. Alan Turing comes up in this episode. He was crucial in the whole code breaking effort in World War II. I should probably do an episode on that. His work, his person, his mind has been a presence in my life. What an incredible human being. But anyway, I think of the human mind, the conscious and the subconscious is a kind of code. And therapy is a kind of code breaking process. I wonder if AI will be able to help with that.
3:42 Lex Fridman? Not just basic therapy, but ultra deep personalized therapy. Boy, that's a dangerous world. Anyway, check out a human therapist at betterhelp.com/lex and save in your first month. That's betterhelp.com/lex. This episode is also brought to you by NetSuite, an all in one cloud business management system. The more I study war, of course, the more I study business too, but war, the more I realize the importance of the organizational layer, of the supply chain, of the logistics, the stuff that nobody talks about, the stuff that most historians don't talk about.
4:24 Lex Fridman? And actually, I've read a lot of James Holland recently and spoken with him, had the great honor of speaking with him, had the great joy of speaking with him and learning from him. And he is one of the historians that does look at the logistics, does look at the Details of how everything is run. And NetSuite in the company setting is doing exactly that. The details of how everything is run. Because a business is not just a CEO with a bunch of sexy ideas. Or the late night engineer crouching over a table. Trying to fix a bug, trying to find a breakthrough idea. Nope, it's also all the other stuff that actually make the thing work. Make the thing efficient. Have great tools to do so.
5:09 Lex Fridman? Download the CFO's Guide to AI and Machine Learning at netsuite.com/lex. That's netsuite.com/lex. This episode is also brought to you by Shopify. A platform designed for anyone to sell anywhere with a great looking online store. Since I mentioned history, the merchant networks were crucially important. In ancient Greece, were crucially important in the Roman Empire. And of course, Genghis Khan. Very, very, very important. Of course, Genghis Khan was well known for protecting the merchants. And I think any empires, any civilizations, any state of the global affairs that protects
5:51 Lex Fridman? the merchants from the friction of geopolitics, of military tensions and military conflicts, is a successful empire, successful civilization. Because trade is really, really important. It's a kind of a financial freedom. So it's nice when in a digital age, we build systems like Shopify that allows you to exercise that financial freedom by buying stuff, selling stuff. Create the market at scale in the digital world. Sign up for a $1 per month trial period at Shopify.com/lex. That's all lowercase. Go to Shopify.com/lex to take your business to the next level today.
6:35 Lex Fridman? This episode is also brought to you by AG1. An all in one daily drink to support better health and peak performance. Because I mentioned peak performance, I'm reminded of Nietzsche. In the book I read, maybe freshman, maybe sophomore year in college. Thus spoke Zarathustra.
6:57 Lex Fridman? It's been forever. I've been reading summaries of Nietzsche
7:04 Lex Fridman? way more than Nietzsche directly since college. That's one of the worries I have with AI is the summaries, the talking about the talking about the talking is so damn efficient and fun and easy and even insightful that you don't want to go to the original sources because it's a lot of work. But you must, of course, if you want to understand. As the meme goes, but have you been there?
7:37 Lex Fridman? That never gets old.
7:40 Lex Fridman? And anyway, I think about that with some of the classics, but even some of the 20th century, 19th century works, you know, you want to read Marx directly. You want to read Nietzsche directly. You want to read Sigmund Freud and Kon Young directly. Because of course, there is great books about them, about their ideas, summarizing their ideas, elaborating on their ideas, putting them in the proper context, but there's nothing quite like reading it directly. But anyway, I brought that, I brought that up because in Thus Spoke Zarathustra, there's the pursuit of peak human potential. And we in the West on the health front have at times taken that to an almost ridiculous place.
8:24 Lex Fridman? I think it's still really useful, but sometimes it's also useful to fuck off a bit, to relax a bit and not care. Funny enough, AG1 helps me in a certain kind of way, relax and not care. I got my nutrition handled. I can do all kinds of crazy physical stuff, mental stuff because I'm drinking AG1. They'll give you a one month supply of fish oil when you sign up at drinkag1.com/lex.
8:56 Lex Fridman? This is the Lex Food Movement Podcast. To support it, please check out our sponsors in the description. And now, dear friends, here's Jenna Levin.
9:21 Lex Fridman? I should say that you sent me a message about not starting early in the morning. And that made me feel like we're kindred spirits. You wrote to me, when the great physicist Sidney Coleman was asked to attend a 9:00 a.m. meeting, his reply was, I can't stay up that late.
9:38 Speaker 01 Yeah, classic. Sidney was beloved.
9:41 Lex Fridman? I think all the best thoughts, honestly. Maybe the worst thoughts, too, are all come at night. There's something, there's something about the night. Maybe it's the silence. Maybe it's the peace all around. Maybe it's the darkness and you just, you could be with yourself and you could think deeply.
9:56 Speaker 01 I feel like there are stolen hours in the middle of the night because it's not busy. Your gadgets aren't pinging. There's really no pressure to do anything, but I'm often awake in the middle of the night. And so it's sort of like these extra hours of the day. I think we were exchanging messages at 4:00 in the morning.
10:14 Lex Fridman? Okay, so in that way, many other ways, we're kindred spirits. So let's go in one of the coolest objects in the universe, black holes. What are they? And maybe even a good way to start is to talk about how are they formed?
10:28 Speaker 01 Hmm, yeah. In a way, people often confuse how they're formed with the concept of the black hole in the first place. So when black holes were first proposed, Einstein was very surprised that such a solution could be found so quickly, but really thought nature would protect us from their formation. And then nature thinks of a way, nature thinks of a way to make these crazy objects, which is to kill off a few stars. But then I think that there's a confusion that dead stars, these very, very massive stars that die, are synonymous with the phenomenon of black hole. And it's really not the case. Black holes are more general and more fundamental than just the death state of a star.
11:11 Speaker 01 But even the history of how people realize that stars could form black holes is quite fascinating because the entire idea really just started as a thought experiment. And if you think of, it's 1915, 1916, when Einstein fully describes relativity in a way that's the canonical formulation. It was a lot of changing back and forth before then. And it's World War I, and he gets a message from the Eastern Front, from a friend of his, Carl Schorchild, who's Who solved Einstein's equations, you know, between sitting in the trenches and like cannon fire. It was joked that he was calculating ballistic trajectories.
11:52 Speaker 01 He's also perusing the proceedings of the Prussian Academy of Sciences, as you do. And he was an astronomer who had enlisted in his 40s. And he finds this really remarkable solution to Einstein's equations. And it's the first exact solution. He doesn't call it a black hole. It's not called a black hole for decades. But what I love about what Schwarzschild did is it's a thought experiment. It's not about observations. It's not about making these things in nature. It's really just about the idea. He sets up this completely untenable situation. He says, imagine I crush all the mass of a star to a point. Don't ask how that's done, because that's really absurd.
12:35 Speaker 01 But let's just pretend and let's just imagine that that's a scenario. And then he wants to decide what happens to spacetime? If I set up this confounding, but somehow very simple scenario? And really what Einstein's equations were telling everybody at the time was that matter and energy curve space and time. And then curved spacetime tells matter and energy how to fall once the spacetime's shaped. So he finds this beautiful solution. And the most amazing thing about his solution is he finds this demarcation, which is the event horizon, which is the region beyond which not even light can escape. And if you were to ask me today, all these decades, over 100 years later, I would say that is the black hole.
13:19 Speaker 01 The black hole is not the mass crushed to a point. The black hole is the event horizon. The event horizon is really just a point in spacetime or a region in spacetime. It's actually, in this case, a surface in spacetime. And it marks a separation in events, which is why it's called an event horizon. Everything outside is causally separated from the inside insofar as what's inside the event horizon can't affect events outside. What's outside can affect events inside. I can throw a probe into a black hole and cause something to happen on the inside. But the opposite isn't true. Somebody who fell in can't send a probe out.
13:59 Speaker 01 And this one way aspect really is what's profound about the black hole. Sometimes we talk about the black holes being nothing because at the event horizon, there's really nothing there.
14:12 Speaker 01 Sometimes when we think about black holes, we want to imagine a really dense dead star. But if you go up to the event horizon, it's an empty region of spacetime. It's more of a place than it is a thing. And Einstein found this fascinating. He helped get the work published, but he really didn't think these would form in nature. I doubt Carl Schwartzchild did either. I think they thought they were solving theoretical, mathematical problems, but not describing this, what turned out to be the end state of gravitational collapse.
14:49 Lex Fridman? And maybe the purpose of the thought experiment was to find the limitations of the theory. So you find the most extreme versions in order to understand where it breaks down.
14:59 Speaker 01 Yeah.
14:59 Lex Fridman? And it just so happens in this case that might actually predict these extreme kinds of objects.
15:06 Speaker 01 It does both. So it also describes the sun from far away. So the same solution does a great job helping us understand the Earth's orbit around the sun. It's incredible. It does a great job. It's almost overkill. You don't really need to be that precise as relativity. And yes, it predicts the phenomenon of black holes, but it doesn't really explain how nature would form them. But then it also, on top of that, does signal the breakdown of the theory. I mean, you're quite right about that. It actually says, oh, man. But you go all the way towards the center and yeah, this doesn't sound right anymore. Sometimes I liken it to, you know, it's like a dying man marking in the dirt that something's gone wrong here, right?
15:51 Speaker 01 It's signaling that there's some culprit. There's something wrong in the theory. And even Roger Penrose, who did this general work trying to understand the formation of black holes from gravitational collapse, he thought, oh, yeah, there's a singularity that's inevitable. It's in every, there's no way around it once you form a black hole. But he said, this is probably just a shortcoming of the fact that we've forgotten to include quantum mechanics and that when we do, we'll understand this differently.
16:25 Lex Fridman? So according to him, the closer you get to the singularity, the more quantum mechanics comes into play and therefore there is no singularity, there's something else.
16:32 Speaker 01 I think everybody would say that. I think everybody would say, the closer you get to the singularity, for sure, you have to include quantum mechanics. You just can't consistently talk about magnifying such small scales, having such enormous ruptures and, and curvatures and energy scales and not include quantum mechanics, that that's just inconsistent with the world as we understand it.
16:55 Lex Fridman? So you've described the brain breaking idea that a black hole is not so much a super dense matter, as it's sometimes described, but it's more akin to, you know, a region of spacetime, but even more so, just nothing.
17:13 Speaker 01 Yeah.
17:13 Lex Fridman? It's nothing. That's the thing you seem to like to say.
17:16 Speaker 01 I do. I do like to say that black holes are no thing.
17:21 Lex Fridman? No thing.
17:21 Speaker 01 They're nothing.
17:22 Lex Fridman? Okay. So what, what does that mean?
17:23 Speaker 01 And that's, that's what I mean. That's the more profound aspect of the black hole. So you asked originally, how do they form? And I think that, that, that even when you try to form them in messy astrophysical systems, there's still nothing at the end of the day left behind. And this was a very big surprise, even though Einstein accepted that this was a true prediction. He didn't think that, that they'd be made. And, and it was quite astounding that, that people like Oppenheimer, actually, it's probably Oppenheimer's most important theoretical work, who were thinking about nuclear physics and quantum mechanics, but in the context of these kind of utopian questions. Why do stars shine? Why is the
18:06 Speaker 01 sun radiant and hot and this amazing source of light? And it was people like Oppenheimer who began to ask the question, well, could stars collapse to form black holes? Could they become so dense that eventually not even light would escape? And that's why I think people think that.
18:28 Speaker 01 Black holes are these dense objects. That's often how it's described. But actually, what happens, these very massive stars, they're burning thermonuclear fuel. They're earthfuls of thermonuclear fuel they're burning and emitting energy. And E equals mc squared energy. So it's fusing, it's a fusion bomb. It's a constantly going thermonuclear bomb. And eventually, it's going to run out of fuel. It's going to run out of hydrogen, helium, stuff to fuse. It hits an iron core. Iron, to go past iron with fusion, is actually energetically expensive. So it's no longer going to do that so easily. So suddenly, it's run out of fuel. And if the star is very, very, very massive, much more massive than our sun, maybe 20,
19:10 Speaker 01 30 times the mass of our sun, it'll collapse under its own weight. And that collapse is incredibly fast and dramatic, and it creates a shock wave. So that's the supernova explosion. So a lot of these, they rebound because, once they crunch, they've reached a new critical capacity where they can reignite to higher elements, heavier elements. And that sets off a bomb, essentially. So the star explodes, hopefully, because that's why you and I are here, because stars send their material back out into space, and you and I get to be made of carbon and oxygen and all this good stuff. We're not just hydrogen. So the suns do that for us.
19:52 Speaker 01 And then what's left sometimes ends at a neutron star, which is a very cool object, very fascinating object, super dense, but bigger than a black hole, meaning it's not compact enough to become a black hole. It's an actual thing. A neutron star is a real thing. It's like a giant neutron. Literally, electrons get jammed into the protons and make this giant nucleus in this superconducting matter. Very strange, amazing objects. But if it's heavier than that, the core, and that's heavier than twice the mass of the sun.
20:28 Speaker 01 It will become a black hole. And Oppenheimer was, wrote this beautiful paper in 1939 with his student, saying that they believed that the end state of gravitational collapse is actually a black hole. This is stunning and really a visionary conclusion. Now, the paper is published the same day the Nazis advance on Poland. And so it does not get a lot of fanfare in the newspapers.
20:56 Lex Fridman? Yeah, we think there's a lot of drama today on social media. Imagine that. Like, here's a guy who predicts how actually in nature would be the formation of this most radical of object that broke even Einstein's brain, while one of the most evil, if not the most evil, humans in history is starting the first steps of a global war.
21:19 Speaker 01 What I also love about that lesson is how agnostic science is. Because he was asking these utopian questions, as were other people of the time, about the nuclear physics in stars. You might know this play Copenhagen by Michael Frayn. There's this line that he attributes to Bohr. And Bohr was the great thinker of early foundations of quantum mechanics, Danish physicist, where Bohr says to his wife, "Nobody's thought of a way to kill people using quantum mechanics." Now, of course, then there's the nuclear bomb. And what I love about this was the pressure scientists were under to do something with this nuclear physics and to enter this race over a nuclear weapon.
22:02 Speaker 01 But really, at the same time, 1939, really, Oppenheimer's thinking about black holes. There's even a small line in Chris Nolan's film. It's very hard to catch. There's a reference to it in the film where he, they're sort of joking, "Well, I guess nobody's going to pay attention to your paper now." You know? Because of the Nazi advance on Poland.
22:22 Lex Fridman? That's the other remarkable thing about Oppenheimer is he's also a central figure in the construction of the bomb.
22:27 Speaker 01 Right.
22:27 Lex Fridman? So it's theory and experiment clashing together.
22:30 Speaker 01 Right.
22:31 Lex Fridman? With the geopolitics.
22:32 Speaker 01 Exactly. So of course Oppenheimer, now known as the father of the atomic bomb, he talks about destroyers of worlds. But it's the same technology. And that's what I mean by science is agnostic, right? It's the same technology, overcoming a critical mass, igniting thermonuclear fusion. Eventually, there was a fission. The original bomb was a fission bomb. And fission was first shown by Lees Meitner, who showed that a certain uranium, when you bombarded it with protons, broke into smaller pieces that were less than the uranium, right? So some of that mass, that E equals mc squared energy, had escaped. And it was the first kind of concrete demonstration of this Einstein's most famous
23:15 Speaker 01 equation. So all of this comes together. But the story of, they still weren't called black holes. This is 1939. And they had these very long-winded ways of describing the end state, the catastrophic end state of gravitational collapse. But what you have to imagine is as this star collapses, so now, so what's the sun? The sun's a million and a half kilometers across. So imagine a star much bigger than the sun, much bigger radius, and it's so heavy, it collapses, it's supernovas. What's left is still maybe 10 times the mass of the sun, just what's left in that core. And it continues to collapse. And when that reaches about 60 kilometers across, like just imagine 10 times the mass
23:58 Speaker 01 of the sun, city sized. That is a really dense object. And now the black hole essentially has begun to form, meaning the curve in spacetime is so tremendous that not even light can escape. The event horizon forms, but the event horizon is almost imprinted on the spacetime, because the star can't sit there in that dense state any more than it can race outward at the speed of light. Because even light is forced to rain inwards. So the star continues to fall. And that's the magic part. The star leaves the event horizon behind. And it continues to fall. And it falls into the interior of the black hole. Where it goes, nobody really knows. But it's gone from sight. It goes dark.
24:45 Speaker 01 There's this quote by John Wheeler, who's like granddaddy of American relativity. And he has a line that's something to the effect, "The star like the Cheshire Cat fades from view. One leaves behind only its grin, the other only its gravitational attraction." And he was giving a lecture. It's actually above Tom's restaurant, you know, from Seinfeld, near Columbia in New York.
25:09 Lex Fridman? Nice.
25:09 Speaker 01 There was a place, or there still is a place there, where people were giving lectures about astrophysics. And it's 1967. Wheeler is exhaustively saying this loaded term, the end state of catastrophic gravitational collapse. And rumor is that someone shouts from the back row, "Well, how about black hole?" And apparently, he then foists this term on the world. Wheeler had a way of doing that.
25:36 Lex Fridman? Well, I love terms like that. Big Bang, black hole. There's some, I mean, it's just pointing out the elephant in the room and calling it an elephant. It is a black hole. That's a pretty accurate and deep description. I just wanted to point out that the, just looking for the first time, it's a 1939 paper from Oppenheimer. It's like two pages, it's like three pages.
25:57 Speaker 01 Oh, yeah, it's gorgeous.
25:59 Lex Fridman? The simplicity of some of these, that's so gangster. Just revolutionize all of physics with this. You know, Einstein did that multiple times in a simple year. "When all thermonuclear sources of energy are exhausted, a sufficiently heavy star will collapse." That's an opener. "Unless fission, due to rotation, the radiation of mass or the blowing off of mass by radiation reduce the star's mass to orders of that of the sun, this contraction will continue indefinitely." And it goes on that way.
26:28 Speaker 01 Yeah. Now, I have to say, Wheeler, who actually coins the term black hole, gives Oppenheimer quite a terrible time about this. He thinks he's wrong. And they entered What has sometimes been described as kind of a bitter, I don't know if you would actually say feud, but they were bad feelings. And Wheeler actually spent decades saying Oppenheimer was wrong. And eventually, with his computer work, that early work that Wheeler was doing, the computers, when he was also trying to understand nuclear weapons, and in peacetime, found themselves returning again to these astrophysical questions, decided that actually Oppenheimer had been right.
27:12 Speaker 01 He thought it was too simplistic, too idealized, a setup that they had used, and that if you looked at something that was more realistic and more complicated, that it just simply, it just would go away. And in fact, he draws the opposite conclusion. There's a story that Oppenheimer was sitting outside of the auditorium when Wheeler was coming forth with his declaration that, in fact, black holes were the likely end state of gravitational collapse for very, very heavy stars. And when asked about it, Oppenheimer sort of said, well, I've moved on to other things.
27:45 Lex Fridman? Because you've written in many places about the human beings behind the science. I have to ask you about this, about nuclear weapons, where it's the greatest of physicists coming together to create this most terrifying and powerful of a technology. And now I get to talk to world leaders for whom this technology is part of the tools that is used, perhaps implicitly, on the chessboard of geopolitics. What can you say, as a person who's a physicist and who have studied the physicists and written about the physicists, the humans behind this, about this moment in human history, when physicists came together and created this weapon that's powerful enough to destroy all of human civilization?
28:30 Speaker 01 I think it's an excruciating moment in the history of science. And
28:39 Speaker 01 People talk about Heisenberg, who stayed in Germany and worked for the Nazis in their own attempt to build the bomb. There was this kind of hopeful talk that maybe Heisenberg had intentionally derailed the nuclear weapons program. But I think that's been largely discredited, that he would have made the bomb, could he? Had he not made some really kind of simple errors in his original estimates about how much material would be required or how they would get over the energy barriers. And that's a terrifying thought. I don't know that any of us can really put ourselves in that position of imagining that we're faced with that quandary, having to take the initiative to participate in
29:24 Speaker 01 thinking of a way that quantum mechanics can kill people and then making the bomb. I think overwhelmingly physicists today feel we should not continue in the proliferation of nuclear weapons. Very few theoretical physicists want to see this continue.
29:41 Lex Fridman? That moment in history, the Soviet Union had incredible scientists, Nazi Germany had incredible scientists, and the United States had incredible scientists. And it's very easy to imagine that one of those three would have created the bomb first, not the United States.
29:57 Speaker 01 Yes.
29:58 Lex Fridman? And how different would the world be? The game theory of that, I think, say, the probability is 33% that it was the United States. If the Soviet Union had the bomb, I think they would have used it in a much more terrifying way in the European theater and maybe turn on the United States. And obviously with Hitler, he would have used it. I think there's no question he would have used it to kill hundreds of millions of people.
30:30 Speaker 01 In the game theory version, this was the least harmful outcome.
30:34 Lex Fridman? Yes.
30:34 Speaker 01 Yes. But there is no outcome with no bomb that any game theorist would, I think, would play.
30:42 Lex Fridman? But I think if we just remove the geopolitics and the ideology and the evil dictators.
30:49 Lex Fridman? All of those people are just scientists. I think they don't necessarily even think about the ideology. And it's a, it's a, it's a deep lesson about the connection between great science and the annoying, sometimes evil politicians that use that science for means that are either good or bad. And the scientists perhaps don't, boy, do they even have control of how that science is used.
31:17 Speaker 01 They don't have control, right? Once it's, once it's made, it's no longer scientific reasoning that dictates the use or restraint. But I will say that I do believe that it wasn't a thirty one-third down the line because America was different. And I think that's something we have to think about right now in this particular climate. So many scientists fled here. They fled to here. Americans weren't fleeing to Nazi Germany. They came here and, and they were motivated by, it's more than a patriotism, you know, it was a, I mean, it was a patriotism, obviously, but it was sort of more than that.
32:00 Speaker 01 It was really understanding the threat of Europe, what was going on in Europe and,
32:07 Speaker 01 and what that life, how quickly it turned, how quickly this free spirited Berlin culture, you know, was suddenly in this repressive and terrifying regime. So I think that it was a much higher chance that it happened here in America.
32:25 Lex Fridman? Yeah, there's something about the American system, the, you know, it's cliche to say, but the freedom, all the different individual freedoms that enable a very vibrant, at its best, a very vibrant scientific community, that's really exciting.
32:38 Speaker 01 Absolutely.
32:38 Lex Fridman? To scientists, and it's very valuable to maintain that. The vibrancy of the debate, of the funding laws mechanisms.
32:46 Speaker 01 Absolutely. The world flocked here and that won't be the case if we no longer have intellectual freedom.
32:54 Lex Fridman? Yeah, there's, there's something interesting to think about. The tension, the Cold War between China and the United States in the 21st century, you know, some of those same questions, some of those ideas will rise up again. And we want to make sure that there's a vibrant, free exchange of scientific ideas. And I believe most Nobel Prizes come from the United States, right?
33:15 Speaker 01 Oh, yeah, I don't have the number, but I-
33:17 Lex Fridman? It's disproportionately so.
33:18 Speaker 01 It's disproportionately so. In fact, a lot of them from particle physics came from the Bronx.
33:25 Speaker 01 And they were European immigrants.
33:27 Lex Fridman? How do we explain this?
33:28 Speaker 01 They fled Europe precisely because of the geopolitics we're describing.
33:32 Lex Fridman? Yeah.
33:32 Speaker 01 And so instead of being Nobel Prize winners from the Soviet Union or from the Eastern Bloc, they were from the Bronx.
33:40 Lex Fridman? And that's the thing you write about, and we'll return to it time and time again, that, you know, science is done by humans, and some of those humans are fascinating. There's tensions, there's battles, there's, some are loners, some are great collaborators, some are tormented, some are easygoing, all this kind of stuff. And that's the beautiful thing about it. We forget sometimes is that it's humans. And humans are messy and complicated and beautiful and all of that.
34:02 Speaker 01 Yeah.
34:03 Lex Fridman? So what were we talking about?
34:05 Speaker 01 Oh, the star is collapsing.
34:07 Lex Fridman? Okay. So can we just return to the collapse of a star that forms a black hole?
34:16 Lex Fridman? At which point does the super dense thing become nothing? If we can just like linger on this concept.
34:22 Speaker 01 Yeah, so if I were falling into a black hole and I, I tried really fast, right as I crossed this empty region, but this demarcation, I happened to know where it was, I calculated, because there's no line there, there's no sign that it's there, there's no signpost. I could emit a little light pulse and try to send it outward exactly at the event horizon. So it's racing outward at the speed of light. It can hover there because from my perspective, it's very strange. The spacetime is like a waterfall raining in and I'm being dragged in with that waterfall. I can't stop at the event horizon. It comes, it goes, it's behind me really quickly. That light beam can try to sit there because it's like, it's like a fish swimming against the Niagara.
35:07 Speaker 01 You know, swimming against the waterfall.
35:09 Lex Fridman? It's like stuck there.
35:09 Speaker 01 But it's like stuck there. And so that's one way you can have a little signpost. You know, if you fly by, you think it's moving at the speed of light. It flies past you at the speed of light, but it's sitting right there at the event horizon.
35:20 Lex Fridman? So you're falling back, cross the event horizon. Right at that point, you shoot outwards a photon.
35:26 Speaker 01 Yes.
35:27 Lex Fridman? And it's just stuck there.
35:28 Speaker 01 It is gets stuck there. Now, it's very unstable. So the star can't sit there is the point. It, it just can't. So it rains inward with this waterfall. But from the outside, all we should ever really care about is the event horizon. Because I can't know what happens to it. It could be pure matter and antimatter thrown together, which annihilates into photons on the inside and loses all its mass into the energy of light. Won't matter to me because I can't know anything about what happened on the inside.
35:56 Lex Fridman? Okay, can we just like linger on this? So what models do we have about what happens on the inside of the black hole at that moment? So I guess that one of the intuitions, one of the big reminders that you're giving to us is like, hey, we know very little about what can happen on the inside of a black hole. And that's why we have to be careful about making, it's better to think about the black hole as an event horizon. But what can we know? And what do we know about the physics of spacetime inside the black hole?
36:27 Speaker 01 I don't mind being incautious about thinking about what the math tells us. So I'm not such a, an observer, right? I'm very theoretical in my work. It's really pen on paper a lot. These are thought experiments that I think we, we can perform and contemplate. Whether or not we'll ever know is another question. And so one of the most beautiful things that we suspect happens on the inside of a black hole is that space and time in some sense swap places. So while I'm on the outside of the black hole, let's say I'm in a nice, comfortable space station. This black hole is maybe 10 times the mass of the sun, 60 kilometers across. I could be 100 kilometers out.
37:11 Speaker 01 That's very, very close, orbiting quite safely. No big deal, you know, hanging out. I don't bug the black hole. Black hole doesn't bug me. It won't suck me up like a vacuum or anything crazy. But my astronaut friend jumps in. As they cross the event horizon, what I'm calling space, I'm looking on the outside at this spherical shadow of the black hole cast by maybe light around it. It's a shadow because everything gets too close, falls in. It's just this contrast against a bright sky. I think, oh, there's a center of a sphere. And in the center of the sphere is the singularity. It's a point in space from my perspective.
37:54 Speaker 01 But from the perspective of the astronaut who falls in, it's actually a point in time. So their notions of space and time have rotated so completely that what I'm calling a direction in space towards the center of the black hole, like the center of a physical sphere, they're going to tell me, well, they can't tell me, but they're going to come to the conclusion, oh, no, that's not a location in space. That's a location in time. In other words, the singularity ends up in their future. And they can no more avoid the singularity than they can avoid time coming their way. So there's no shenanigans you can do once you're inside the black hole to try to skirt it, the singularity. You can't set yourself up in orbit around it.
38:38 Speaker 01 You can't try to fire rockets and stay away from it because it's in your future. And there's an inevitable moment when you will hit it. Usually for a stellar mass black hole, we think it's microseconds.
38:50 Lex Fridman? Microseconds to get from the event horizon to the...
38:53 Speaker 01 To the singularity.
38:54 Lex Fridman? To the singularity. Oh, boy. So that's describing from your astronaut friend's perspective.
39:02 Speaker 01 Yes, from their perspective, the singularity is in their future.
39:06 Lex Fridman? But from your perspective, what do you see when your friend falls into the black hole and you're chilling outside and watching?
39:14 Speaker 01 So one way to think about this is to think that as you're approaching the black hole...
39:23 Speaker 01 The astronaut's spacetime is rotating relative to your spacetime. So let's say right now, my left is your right. We're not shocked by the fact that there's this relativity in left and right. It's completely understood. And I can perform a spatial rotation to align my left with your left. Right now, I've completely rotated left out, right? If I just want to draw a kind of a compass diagram, not a compass diagram. You know, at the top of maps, there's a north, south, east, west. But now time is up, down, and one direction of space is, let's say, east, west. As you approach the black hole, it's as though you're rotating in spacetime, is one way of thinking about it.
40:08 Speaker 01 So what is the effect of that? The effect of that is as this astronaut gets closer and closer to the event horizon, part of their space is rotated into my time and part of their time is rotated into my space. So in other words, their clocks seem to be less aligned with my time. And the overall effect is that their time seems to dilate. The spacing between ticks on the clock of their watch, let's say, on the, on the face of their watch, is, is elongated, dilated, relative to mine. And it seems to me that their watches are running slowly, even though they were made in the same factory as mine.
40:51 Speaker 01 They were both synchronized beautifully and they're excellent Swiss watches. It seems as though time is elapsing more slowly for my companion. And likewise, for them, it seems like mine's going really fast. So years could elapse. In my space station, my plants come and go, they die, I age faster, I've got gray hair. And they're falling in and it's been minutes in their frame of reference. Flowers in their little rocket ship haven't rotted, they don't have gray hair. Their biological clocks have slowed down relative to ours. Eventually, at the event horizon, it's so extreme, it's so slow,
41:34 Speaker 01 it's as though their clocks have stopped altogether, from my point of view. And that's to say that it's as though their time is completely rotated into my space. And this is connected with the idea that inside the black hole, space and time have switched places. So I might see them hover there for millennia. Other astronauts could be born on my space station. Generations could be populated there, watching this poor astronaut never fall in.
42:06 Lex Fridman? So basically, the time almost comes to a standstill. But we still, they do fall in.
42:14 Speaker 01 Right, they do fall in eventually. Now, that's because they have some mass of their own.
42:19 Lex Fridman? Yeah.
42:19 Speaker 01 So they're not a perfectly light particle. And so they deform the event horizon a little bit. You will actually see the event horizon bobble and absorb the astronaut. So in some finite time, the astronaut will actually fall in.
42:35 Lex Fridman? So it's like this weird spacetime bubble that we have around us. And then there's a very big spacetime curvature bubble thing from the black hole. And there's a nice swirly type situation going on. That's how you get sucked up.
42:51 Speaker 01 Yeah.
42:51 Lex Fridman? So if you're a perfect, like infinitely small particle, you would just be
42:55 Speaker 01 It'd take longer and longer.
42:57 Lex Fridman? And probably just be stuck there or something. But no, there's quantum mechanics.
43:01 Speaker 01 Eventually, you'll fall in. Any perturbation will only go one way. It's unstable in one direction, in one direction only. But it's, it's really important to remember that from the point of view of the astronaut, not much time has passed at all. You just sail right across as far as you're concerned. And nothing dramatic happens there. You might not even realize you've come to the event horizon. You, you might not even realize you've crossed the event horizon. Because it's, there's nothing there. Right? This is an empty region of spacetime. There's no marker to tell you, you've reached this very dangerous point of no return. You can fire your rockets like hell when you're on the outside and maybe even escape. Right?
43:44 Speaker 01 But once you get to that point, there's no amount of energy. All the energy in the universe will not save you from this demise.
43:53 Lex Fridman? You know, there's different sized black holes. And maybe can we talk about the experience that you have falling into a black hole, depending on what the size of the black hole is?
44:02 Speaker 01 Yeah.
44:03 Lex Fridman? Because as I understand, if the, the, the bigger it is.
44:08 Lex Fridman? The less drastic the experience of falling into it.
44:13 Speaker 01 Yeah, that might surprise people.
44:15 Lex Fridman? Yeah.
44:15 Speaker 01 The bigger it is, the less noticeable it is that you've you've crossed the event horizon. One way to think about it is curvature is less noticeable, the bigger it is. So if I'm standing on a basketball, I'm very aware I'm balancing on a curved surface. I my two feet are in different locations and I really notice. But on the earth, you actually have to be kind of clever to deduce that the earth is curved. The bigger the planet, the less you're going to notice the curvature, the global curvature. And it's the same thing with a black hole, huge, huge black hole. It just is kind of feels like just flat. You don't really notice.
44:54 Lex Fridman? I'm trying to figure out how the because if you don't notice.
44:57 Speaker 01 And there's nothing there.
44:59 Lex Fridman? But the physics is weird.
45:01 Speaker 01 In your frame of reference.
45:04 Lex Fridman? No.
45:05 Speaker 01 Well, so another cool thing, so I'd like to dispel this.
45:09 Lex Fridman? Yeah.
45:10 Speaker 01 Do you need a minute? You're holding your head.
45:14 Lex Fridman? There's a sense like you should be able to know when you're inside of a black hole, when you've crossed the event horizon. But no, from your frame of reference, you might not be able to know.
45:24 Speaker 01 Yeah, at first, at least you might not realize what's happened. There are some hints. For instance, black holes are dark from the outside, but they're not necessarily dark on the inside. So this is a kind of fascinating that your experience could be that it's quite bright inside the black hole because all the light from the galaxy can be shining in behind you. And it's focusing down because you're all approaching this really focused region in the interior. And so you actually see a bright white flash of light as you approach the singularity. And I kind of I joke that it's a, you know, it's like a near death experience. We see the light at the end of the tunnel. So you would see millennia pass on earth.
46:09 Speaker 01 You could see the evolution of the entire galaxy, you know, one big bright flash of light. So it's like a near death experience, but it's a definitely a total death experience.
46:19 Lex Fridman? It goes pretty fast, but you looking out, you looking out, everything's going super fast.
46:25 Speaker 01 Yeah, the clocks.
46:28 Speaker 01 On the earth, on the space station, seem to be progressing very rapidly relative to yours. The light can catch up to you and you get this bright beam of light as you see the evolution of the galaxy unfold. And I mean, it sort of depends on the size of the black hole and how long you have to hang around. The bigger the black hole, the longer it takes you to expire in the center.
46:53 Lex Fridman? Obviously, the human sensory system are not able to process that information correctly.
46:59 Speaker 01 Right. It would be a microsecond and right, that would be too fast.
47:02 Lex Fridman? Yeah, but it would be, wow, it would be so cool to get that information.
47:06 Speaker 01 But a big black hole, you could actually, you know, hang around for some months.
47:10 Lex Fridman? So, yeah, what's, how are small black holes or just supermassive black holes formed? Just so people can kind of load that in. Are they, are they all, is it always a star?
47:24 Speaker 01 No. So this is also why it's important to think of black holes more abstractly. They are something very profound in the universe and there are probably multiple ways to make black holes. Making them with stars is most plentiful. There could be hundreds of millions, maybe even a billion black holes in our Milky Way galaxy alone. That many stars. It's only about 1% of stars that will end their lives in a death state. That is a black hole. But we now see, and this was really quite a surprise, that there are supermassive black holes. They're billions or even hundreds of billions of times the mass of the sun
48:07 Speaker 01 and millions to tens of billions, maybe even hundreds of billions. So extremely massive. We don't think that the universe has had enough time to make them from stars that just merge. We know that two black holes can merge and make a bigger black hole and then those can merge and make a bigger black hole. We don't think there's been enough time for that. So it's suspected that they're formed very early, maybe even a hun- a hundred, few hundred million years after the big bang and that they're formed directly by collapsing out of primordial stuff. That there's a direct collapse right into the black hole.
48:46 Lex Fridman? So like in the, in the very early universe. These are primordial black holes from the
48:53 Speaker 01 Well, they're different.
48:54 Lex Fridman? Star is not quite, wait, how do you get from that soup? Black holes right away?
48:58 Speaker 01 Right, so it's odd, but it's weirdly easier to make a big black hole out of something that's just the density of air. If it's really, really as big as what we're talking about. So in some sense, if they're just allowed to directly collapse very early in the universe's history, they can do that more easily. And it's so much so that we think that there's one of these supermassive black holes in the center of every galaxy. So they're not rare, and we know where they are. They're in the nuclei of galaxies. So they're bound to the very early formation of entire galaxies in a really surprising and deeply connected way.
49:39 Lex Fridman? I wonder if the, like, the chicken or the egg, is it, uh, like, how critical, how essential are the supermassive black holes to the formation of galaxies?
49:49 Speaker 01 Yeah, I mean, it's ongoing, right? It's ongoing, which came first? The black hole or the galaxy? Probably big, early stars, which were just made out of hydrogen and helium from the big bang. There wasn't anything else, not much of anything else. Those early stars were forming, and then maybe the black holes and kind of the galaxies were like these gassy clouds around them.
50:15 Speaker 01 But there's probably a deep relationship between the black hole powering jets, these jets blowing material out of the galaxy that shaped galaxies, maybe kind of curbed their growth. And so I think the mechanisms are still, are still ongoing, the attempts to understand exactly the ordering of these things.
50:39 Lex Fridman? Can we get back to spacetime? Just going back to the beginning of the 20th century. How do you imagine spacetime? How do we, as human beings, supposed to visualize and think about spacetime? Where, you know, time is just another dimension in this 4D space that combines space and time? Because we've been talking about morphing in all kinds of different ways, the curvature of spacetime. Like, how do you, how are we supposed to conceive of it? How do you think of it?
51:04 Speaker 01 Yeah.
51:05 Lex Fridman? Time is just another dimension?
51:06 Speaker 01 There are different ways we can think about it. We can imagine drawing a map of space and treating time as another direction in that map.
51:18 Speaker 01 But we're limited because as three dimensional beings, we can't really draw four dimensions, which is what I'd require. Three spatial, because I'm pretty sure there's at least three. I think there's probably more, but I'm happy just talking about the large dimensions. The three we see up, down, right? East, west, north, south, three spatial dimensions. And time is the fourth. Nobody can really visualize it. But we know mathematically how to unpack it on paper. I can mathematically suppress one of the spatial dimensions and then I can draw it pretty well. Now, the problem is that we'd call it a Euclidean spacetime.
52:02 Speaker 01 A Euclidean spacetime is when all the dimensions are orthogonal and are treated equally. Time is not another Euclidean dimension. It's actually a Minkowskiian spacetime. But it means that the spacetime, we're misrepresenting it when we draw it, but we're misrepresenting it in a way that we deeply understand. I can give you an example. The Earth, I can project onto a flat sheet of paper. I am now misrepresenting a map of the Earth. And I know that, but I understand the rules for how to add distances on this misrepresentation, because the Earth is not a flat sheet of paper. It's a sphere. And as long as I understand the rules for how I get from the North Pole to the South Pole,
52:45 Speaker 01 that I'm moving along really a great arc and I understand that the distance is not the distance I would measure on a flat sheet of paper, then I can do a really great job with a map. And understanding the rules of addition, multiplication in the geometry is not the geometry of a flat sheet of paper. I can do the same thing with spacetime. I can draw it on a flat sheet of paper, but I know that it's not actually a flat Euclidean space. And so my rules for measuring distances are different than the rules I would use that, for instance, Cartesian rules of geometry. I would know to use the correct rules for Minkowski spacetime. And that will allow me to calculate how long
53:28 Speaker 01 time has elapsed, which is now a kind of a length, a spacetime length on my map, between two relative observers, and I will get the correct answer. But only if I use these different rules.
53:42 Lex Fridman? So then, what does, according to general relativity, does
53:48 Lex Fridman? objects with mass do to the spacetime?
53:51 Speaker 01 Right, exactly. So Einstein struggled for this completely general theory, not a specific solution, like a black hole or an expanding spacetime, or galaxies make lenses, or those are all solutions. That's why what he did was so enormous. It's an entire paradigm that says, over here is matter and energy. I'm going to call that the right-hand side of the equation. Everything on the right-hand side of Einstein's equations is how matter and energy are distributed in spacetime. On the left-hand side tells you how space and time deform in response to that matter and energy. And it can be impossible to solve some of those equations. What was so amazing about what Schwarzschild did
54:36 Speaker 01 is he found this very elegant, simple solution within like a month
54:41 Speaker 01 of reading this final formulation. But Einstein didn't go through and try to find all the solutions. He sort of gave it to us, right? He shared this, and then lots of people since have been scrambling to try to, ah, I can predict the curvature of the spacetime if I tell you how the matter and energy is laid out. If it's all compact in a spherical system like a sun or even a black hole, I can understand the curves in the spacetime around it. I can solve for the for the shape of the spacetime. I can also say, well, what if the universe is full of gas or light and it's all kind of uniform everywhere? And I'll find a different and equally surprising solution, which is that the universe would expand.
55:24 Speaker 01 In response to that, that it's not static, that the distances between galaxies would grow. This was a huge surprise, Einstein. So all of these consequences of his theory, you know, came with revelations that were not at all obvious when he first wrote down the general theory.
55:44 Lex Fridman? And he was afraid to take the consequences of that theory seriously, which is a
55:49 Speaker 01 Often.
55:49 Lex Fridman? The theory itself, in its scope and grandeur and power, is scary, so I can understand. Then there's, you know, the edges of the theory where it falls apart, the consequences of the theory that are extreme. It's hard to take seriously. So you can sort of empathize.
56:07 Speaker 01 Yeah, he very much resisted the expansion. So if you think about 1905, when he's writing these sequence of unbelievable papers as a 25 year old who can't get a job, you know, as a physicist, and he writes all of these remarkable papers on relativity and quantum mechanics. And then even in 1915, 16, he does not know that there are other galaxies out there. This was not known. People had mused about it. There were these kind of smudges on the sky that people contemplated. What if there are other island universes? You know, going back to Kant, thought about this. But it wasn't until Hubble, it really wasn't until the late 20s, that it's confirmed that there are other galaxies.
56:51 Lex Fridman? Wow.
56:52 Speaker 01 Yeah.
56:52 Lex Fridman? He didn't, obviously, there's so much we think of now that he didn't think of. So there's no big bang.
57:01 Speaker 01 Right.
57:01 Lex Fridman? Static universe.
57:03 Speaker 01 But these are all connected.
57:05 Lex Fridman? Wow, yeah. So he's operating on very little information.
57:10 Speaker 01 Very little information. That's absolutely true. Actually, one of the things I like to point out is the idea of relativity was foisted on people in this kind of cultural way. But there's many ways in which you could call it a theory of absolutism. And the way Einstein got there with so little information is by adhering to certain very strict absolutes, like the absolute limit of the speed of light and the absolute constancy of the speed of light, which was completely bizarre when it was first discovered, really. That was observed. There were experiments trying to figure out.
57:54 Speaker 01 What would the relative speed of light be? It's the only, really, only massless particles have this property that they have an absolute speed. And if you think about it, it's incredibly strange.
58:03 Lex Fridman? Yeah, it's really strange.
58:04 Speaker 01 Incredibly strange.
58:05 Lex Fridman? And so from theoretical perspective, he takes that seriously.
58:10 Speaker 01 He takes it very seriously, and everyone else is trying to come up with models to make it go away, to make the speed of light be a little bit more reasonable, like everything else in the universe. You know, if I run at a car, two cars coming at each other, they're coming at each other faster than if one of them stops. It's really a basic observation of reality, right? Here, this is saying that if I'm racing at a light beam and you're standing still relative to the source, we'll measure the same exact speed of light. Very strange. And he gets to relativity by saying, well, what speed? Speed is distance, it's space, over time. It's how far you travel, it's the space you travel in a certain duration of time.
58:55 Speaker 01 And he said, well, I bet something must be wrong then with space and time. So this is an enormous leap. He's willing to give up the absolute character of space and time in favor of keeping the speed of light constant.
59:09 Lex Fridman? How was he able to intuit a world of curved spacetime? Like, I think it's like one of the most special leaps in human history, right? Because you're-
59:25 Speaker 01 It's amazing.
59:26 Lex Fridman? Like, it's very, very, very difficult to make that kind of leap.
59:30 Speaker 01 I'll tell you, it took me, I think, a long time to, I can't say this is how he got there exactly. It's not as though I studied the historical accounts of, or his description of his internal states. This is more- Having learned the subject, how I try to tell people how to get there in a few short steps. One is to start with the equivalence principle, which he called the happiest thought of his life. The equivalence principle comes pretty early on in his thinking. And it starts with something like this. Right now, I think I'm feeling gravity because I'm sitting in this chair and I feel the pressure of the chair and it's stopping me from falling.
1:00:15 Speaker 01 And I lie down in a bed and I feel heavy on the bed and I think of that as gravity. And I have this beautiful ability to remove all of these extraneous factors, including atoms. So let's imagine instead that you're in an elevator and you feel heavy on your feet because the floor of the elevator is resisting your fall. But I want to remove the elevator. What does the elevator have to do with fundamental properties of gravity? So I cut the cable. Now I'm falling, but the elevator is falling at the same rate as me. So now I'm floating in the elevator. And if this happened to me, if I woke up in this state of falling or floating in the
1:00:57 Speaker 01 elevator, I might not know if I was in empty space, just floating, or if I was falling around the earth. They would actually, they're equivalent situations. I would not be able to tell the difference. I'm actually, when I get rid of the elevator in this way by cutting the cable, I'm actually experiencing weightlessness. And that weightlessness is the purest experience of gravity. And so this idea of falling is actually fundamental. It's how we talk about it all the time. The earth is in a free fall around the sun. It's actually falling. It's not firing engines, right? It's just, it's just falling all the time, but it's just cruising so fast.
1:01:40 Lex Fridman? So actually, yeah, God, you said so many profound things. So one of them is really one of the ways to experience spacetime.
1:01:49 Lex Fridman? Is to be falling.
1:01:50 Speaker 01 To be falling. That is the purest experience of gravity. The experience of gravity unfettered, uninterrupted by atoms is weightlessness.
1:02:01 Lex Fridman? Yeah.
1:02:01 Speaker 01 That observation, no, it has an unhappy ending, the elevator story.
1:02:06 Speaker 01 Because of atoms again. That's the fault of the atoms in your body interacting electromagnetically with the crust of the earth, or the bottom of the building, or whatever it is. But this period of free fall, so the first observation is that that is the purest experience of gravity. Now I can convince you that things fall along curved paths. Because I could take, you know, a pen, and if I throw it, we both know it's going to follow an arc. And it's going to follow an arc until atoms interfere again and it hits the ground. But while it's in free fall, experiencing gravity at its purest, what the Einsteinian description would say is it is following the natural curve
1:02:48 Speaker 01 in spacetime, inscribed by the earth. So the earth's mass and shape curves the paths in space. And then those curvatures tell you how to fall, the paths along which you should fall when you're falling freely. And so the earth has found itself on a free fall that happens to be a closed circle. But it's, it's actually falling. The International Space Station uses this principle all the time. They get the space station up there, and then they turn off the engines. Can you imagine how expensive it would be if they had to fuel that thing at all times, right? They turn off the engines. They're just falling.
1:03:28 Lex Fridman? Yeah, they're falling.
1:03:28 Speaker 01 And they're not that far up. There, there are certainly, people sometimes say, oh, they're so far away, they don't feel gravity. Oh, absolutely. If you stopped the space station, it's going like 17,500 miles an hour, something like that. If you were to stop that, it would drop like a stone, right to the earth. So they're in a state of constant free fall. And they're falling along a curved path. And that curved path is a result of curving spacetime.
1:03:56 Lex Fridman? And that particular curved path is calculated in such a way that it curves onto itself. So you're orbiting.
1:04:02 Speaker 01 Right. So it has to be cruising at a certain speed. So once you get it at that cruising speed, you turn off the engines.
1:04:10 Lex Fridman? But yeah, to be able to visualize at the beginning of the 20th century.
1:04:16 Lex Fridman? That not, you know, that free falling in curved spacetime.
1:04:24 Lex Fridman? Boy, the human mind is capable of things. I mean, some of that is constructing thought experiments that collide with our understanding of reality. Maybe in the collisions and the contradictions, you try to think of extreme thought experiments that that exacerbate that contradiction and see like, okay, what is actually, is there another model that can incorporate this? But to be able to do that, I mean, it's kind of inspiring because, you know, there's probably another general relativity out there.
1:04:58 Speaker 01 Yeah.
1:04:58 Lex Fridman? In all, not just in physics, in all lines of work, in all scientific pursuits. There's certain theories where you're like, okay, I just explained like a big elephant in the room here, that everybody just kind of didn't even think about. There could be,
1:05:19 Lex Fridman? for stuff we know about in physics, there could be stuff like that for the origin of life on Earth.
1:05:23 Speaker 01 Yeah.
1:05:24 Lex Fridman? Everyone's like, yeah, okay. Everyone's like in polite companies, like, yeah, yeah, yeah, yeah. Somehow it started.
1:05:33 Speaker 01 Right.
1:05:33 Lex Fridman? Nobody knows.
1:05:34 Speaker 01 I find it wild that that's so elusive.
1:05:36 Lex Fridman? Yeah, it's strange. In the lab, you can't replicate.
1:05:39 Speaker 01 It's strange that it's so elusive.
1:05:39 Lex Fridman? I think it's a general relativity thing. There's going to be something that's going to involve aliens and wormholes and dimensions that we don't quite understand, or some, some field that's bigger than like, it's possible, maybe not, it's possible that it has, it's a field that is different, that will feel fundamentally different from chemistry and biology. It'll be maybe through physics. Again, maybe the key to the origin of life is in physics. And the same there, it's like a weird neighbor is consciousness. It's like, all right.
1:06:14 Speaker 01 A weird neighbor, yeah.
1:06:15 Lex Fridman? It's like, okay, so we all know that life started on Earth somehow. Nobody knows how. We all know that we're conscious. We have a subjective experience of things. Nobody understands.
1:06:31 Lex Fridman? That people have ideas and so on.
1:06:32 Speaker 01 Right.
1:06:32 Lex Fridman? But it's such a dark sort of, we're entering a dark room where a bunch of people are whispering about like, hey, what's in this room? But nobody, nobody has a effing clue.
1:06:43 Speaker 01 Mm hmm.
1:06:44 Lex Fridman? So, and then somebody comes along with a general relativity kind of conception where like reconceives everything and you're like, ah.
1:06:52 Speaker 01 It's like a watershed moment.
1:06:54 Lex Fridman? Yeah.
1:06:54 Speaker 01 Yeah.
1:06:55 Lex Fridman? Yeah, it's there. And until
1:06:56 Speaker 01 It's there.
1:06:57 Lex Fridman? We're living in the, we're living in a time until that theory comes along. It would be obvious in retrospect, but right now, we're
1:07:04 Speaker 01 Right, well, this, it was obvious to no one. That spacetime was curved, but even Newton understood something wasn't right. So he knew there was something missing. And I think that's always fascinating when we're in a situation where we're pressure testing our own ideas. He did something remarkable, Newton did with his theory of gravity, just understanding that the same phenomenon was at work with the earth around the sun as the apple falling from the tree. That's insane. That's a huge leap. Understanding that mass, inertial mass, what makes something hard to push around, is the same thing that feels gravity, at least in the Newtonian picture in that simple way.
1:07:49 Speaker 01 Unbelievable leap, absolutely genius. But he didn't like that the apple fell from the tree even though the earth wasn't touching it.
1:07:59 Lex Fridman? Yeah, the action at a distance thing.
1:08:01 Speaker 01 The action at a distance thing.
1:08:02 Lex Fridman? That is weird, too.
1:08:03 Speaker 01 Well, but
1:08:04 Lex Fridman? That is a really weird one.
1:08:05 Speaker 01 It's really weird, but see Einstein solves that, relativity solves that. Because it says, the earth created the curve in space, the apple wants to fall freely along it. The problem is the trees in the way. The trees, the problem, the tree's actually accelerating the apple. It's keeping it away from its natural state of weightlessness in a gravitational field. And as soon as the tree lets go of it, the apple will simply fall along the curve that exists.
1:08:35 Lex Fridman? I would, I would love it if somebody went back to Newton's time.
1:08:39 Speaker 01 And told him all this?
1:08:40 Lex Fridman? Probably some, like some, like hippie would be like, it's a, gravity is just the curvature in spacetime, man. I wonder if he would be able to, I don't think, there's, you know, every idea has its time.
1:08:53 Lex Fridman? He might not, he might not even be able to load that in.
1:08:56 Speaker 01 Hmm.
1:08:57 Lex Fridman? I mean, sometimes even the greatest geniuses, I mean, you can't.
1:09:02 Speaker 01 Hmm.
1:09:02 Lex Fridman? Like you need.
1:09:03 Speaker 01 Too out of context.
1:09:04 Lex Fridman? You need to be standing on the shoulders of giants and on the shoulders of those giants and so on.
1:09:09 Speaker 01 I heard that Newton used that as an unkind remark to his competitor hook.
1:09:14 Lex Fridman? Oh, no. The people talk shit even back then.
1:09:18 Speaker 01 Yeah, trash talking.
1:09:22 Lex Fridman? It's one of the hilarious things about humans in general, but scientists too, like these huge minds. There's these moments in history where you'll see this in universities, but everywhere else too. Like you have gigantic minds, obviously also coupled with everybody has an ego. And like sometimes it's just the same soap opera that played out amongst humans everywhere else. And so you're thinking about the biggest cosmological objects and forces and ideas. And you're still like jealous and.
1:09:56 Speaker 01 Right. I know.
1:09:58 Lex Fridman? Your, your office is bigger than my office.
1:10:00 Speaker 01 I know.
1:10:00 Lex Fridman? This chair, this, or, or maybe you got married to this person that I was always in love with. That's a betrayal or something.
1:10:10 Speaker 01 The one woman in the department.
1:10:11 Lex Fridman? Yeah, the one woman in the department. Yeah. And it's just, I mean, but that is also the fuel of innovation, that jealousy, that tension, that's.
1:10:20 Speaker 01 Well, you know, the expression, I'm sure the battles are so bitter in academia because the stakes are so low.
1:10:26 Lex Fridman? That's a beautiful way to phrase it. But also like, we shouldn't forget, I mean, that I love seeing that even in academia because it's humanity. The silliness, it's, there is a degree to academia where the reason you're able to think about some of these grand ideas is because you still allow yourself to be childlike.
1:10:46 Speaker 01 Oh, yeah.
1:10:47 Lex Fridman? There's a childlike nature to be asked the good questions.
1:10:49 Speaker 01 Oh, yeah.
1:10:50 Lex Fridman? But children can also be like.
1:10:52 Speaker 01 Children.
1:10:53 Lex Fridman? Children. So like you don't, I think when, um, in, in, in a corporate context and maybe the world gets, forces you to behave. You're supposed to be a certain kind of way. There's some aspects and it's a really beautiful aspect to preserve and to celebrate in academia. Is like you're just allowed to be childlike in your curiosity and your exploration. You're just exploring, asking the biggest questions.
1:11:20 Speaker 01 The best scientists I know often ask the simplest questions. They're they're really, first of all, there's probably some confidence there. But also, they're never going to lie to themselves that they understand something that they don't understand. So even this idea that Newton didn't understand the apple falling from the tree. He had he lived another couple hundred of years, he would have invented relativity. Because he never would have lied to himself that he understood it. He would have kept asking this very simple question. And I think that there is this childlike beauty to that, absolutely.
1:12:00 Lex Fridman? Yeah, just some of the topics. I don't know why I'm stuck to those two topics of origin of life and consciousness.
1:12:05 Speaker 01 I'll talk about this.
1:12:06 Lex Fridman? Some of the most brilliant people I know are stuck, just like with Newton and Einstein. They're stuck on that this doesn't make sense. I know a bunch of brilliant biologists, physicists, chemists that are thinking about the origin of life. They're like, this doesn't. I know how evolution works. I know how the biological systems work, how genetic information propagates. But like this, this part, the singularity at the beginning doesn't make sense. We don't understand, we can't create in a lab. They're bothered, every single day, they're bothered by it. And that being bothered by that tension, by that gap in knowledge is, yeah, that's the catalyst. That's the fuel for the.
1:12:46 Speaker 01 Discovery.
1:12:47 Lex Fridman? For discovery.
1:12:48 Speaker 01 Yeah, absolutely. The discovery is going to come because somebody couldn't sleep at night and couldn't rest.
1:12:55 Lex Fridman? So in that way, I think black holes are a kind of portal into some of the biggest mysteries of our universe. So it is a, it's a good terrain I wish to explore these ideas. So can you speak about some of the mysteries that the black holes present us with?
1:13:10 Speaker 01 Yeah, I think it's important to separate the idea that there are these astrophysical states that become black holes from being synonymous with black holes, because black holes are kind of this this larger. Idea and they might have been made primordially when the Big Bang happened. And there, there's something flawless about black holes that makes them fundamental, unlike anything else. So they're flawless in the sense that you can completely understand a black hole by looking at just its charge, electric charge, its mass and its spin.
1:13:51 Speaker 01 And every black hole with that charge, mass and spin is identical to every other black hole. You can't be like, oh, that one's mine. I recognize it. It has this little feature and that's how I know it's mine. They're featureless. They, you, you try to put Mount Everest on a black hole and it will shake it off in these gravitational waves. It will radiate away this imperfection until it settles down to be a perfect black hole again. So there's something about them that is unlike, and another reason why I don't like to call them objects in a traditional sense, unlike anything else in the universe that's macroscopic. It's kind of a little bit more like a fundamental particle.
1:14:32 Speaker 01 So an electron is described by a certain short list of properties, charge, mass, spin, maybe some other quantum numbers. That's what it means to be an electron. There's no electron that's a little bit different. You can't recognize your electron. They're all identical in that sense. And, and so in some very abstract way, black holes share something in common with microscopic fundamental particles. And so what they tell us about the fundamental laws of physics can be very profound. And it's why even theoretical physicists, mathematical physicists, not just astronomers
1:15:17 Speaker 01 who use telescopes, they rely on the black hole as a terrain to perform their thought experiments.
1:15:25 Speaker 01 And and it's because there's something fundamental about them.
1:15:29 Lex Fridman? Yeah, general relativity means quantum mechanics.
1:15:32 Speaker 01 Means singularity.
1:15:34 Lex Fridman? And sadly, heartbreakingly so, it's out of reach for experiment at this moment. But but within reach for theoretical.
1:15:42 Speaker 01 It's in reach for for thought experiments.
1:15:44 Lex Fridman? For thought experiments.
1:15:45 Speaker 01 Which are quite beautiful.
1:15:47 Lex Fridman? Well, on that topic, I have to ask you about the paradox, the information paradox of black holes. What is it?
1:15:54 Speaker 01 So this is what catapulted Hawking's fame. When he was a young researcher, he was thinking about black holes and wanted to just add a little smidge of quantum mechanics. Just a little smidge, you know, wasn't going for full blown quantum gravity. But kind of just asking, well, what if I allowed this nothing, this vacuum, this empty space around the event horizon? Star's gone, there's nothing there. What if I allowed it to possess sort of ordinary quantum properties, just a little tiny bit, you know, nothing dramatic?
1:16:31 Speaker 01 Don't go crazy, you know? And one of the properties of the vacuum that is intriguing is this idea that you can never see the vacuum's actually completely empty. We talked about Heisenberg, you know, the Heisenberg uncertainty principle really kicked off a lot of quantum mechanical thinking. It says that you can never exactly know a particle's position simultaneously with its motion, with its momentum. You can know one or the other pretty precisely, but not both precisely. And the uncertainty isn't a lack of ability that will technologically overcome. It's foundational. So that there's, in some sense, when it's in a precise location, it is fundamentally no longer in a precise motion.
1:17:13 Speaker 01 And that uncertainty principle means I can't precisely say a particle is exactly here. But it also means I can't say it's not. Okay. And so it led to this idea that what do I mean by a vacuum? Because I can't 100% precisely know. In fact, there's not really meaningful to say that there's zero particles here. And so what you can say, however, is you can say, well, maybe particles kind of froth around in this seething quantum sea of the vacuum. Maybe two particles come into existence and they're entangled in such a way that they cancel out each other's properties. So they have the properties of the vacuum.
1:17:56 Speaker 01 They don't destroy the kind of properties of the vacuum because they cancel out each other's spin, maybe, each other's charge, maybe, things like that. But they kind of froth around. They come, they go, they come, they go. And that's what we really think is the best that empty space can do in a quantum mechanical universe. Now, if you add an event horizon, which, as we said, is really fundamentally what a black hole is. That's the most important feature of a black hole. The event horizon, if the particles are created slightly on either side of that event horizon, now you have a real problem. Okay. Now, the pair has been separated by this event horizon.
1:18:40 Speaker 01 Now, they can both fall in, that's okay. But if one falls in and the other doesn't, it's stuck. It can't go back into the vacuum because now it has a charge, or it has a spin, or it has something that is no longer the property of that vacuum it came from. It needs its pair to disappear. Now it's stuck. It exists. It's like you've made it real. So in a sense, the black hole steals one of these virtual particles and forces the other to live. And if it escapes, radiate out to infinity and look like, to an observer far away, that the black hole has actually radiated a particle. And the particle did not emanate from inside.
1:19:25 Speaker 01 It came from the vacuum. It stole it from empty space, from the nothingness that is the black hole. Now, the reason why this is very tricky is because in the process, because of the separation on the other side of the event horizon, the particle it absorbs, it has to do with the switching of space and time that we talked about, but the particle it absorbs, well, from the outside, you might say, oh, it had negative momentum. It was falling in. From the inside, you say, well, this is actually motion and time. This is energy. It is negative energy. And it absorbs negative energy, its mass goes down. The black hole gets a little lighter. And as it continues to do this, the black hole really begins to evaporate. It doesn't more than just radiate, it evaporates away.
1:20:10 Speaker 01 And it's intriguing because Hawking said, look, this is going to look thermal, meaning featureless. It's going to have no information in it. It's going to be the most informationless possibility you could possibly come up with when you're radiating particles. It's just going to look like a thermal distribution of particles, like a hot body. And the temperature is going to only tell you about the mass, which you could tell from outside the black hole anyway. You know, the mass of the black hole from the outside. So it's not telling you anything about the black hole. It's got no information about the black hole. Now you have a real problem. And when he first said it, a lot of people described that not everyone understood how really naughty he was being. He did.
1:20:55 Speaker 01 But some people who love quantum mechanics were really annoyed. Okay, people like Lenny Suskin, George Tsoft, Nobel Prize winner, they were mad because it suggested something was fundamentally wrong with quantum mechanics, if it was right. And the reason why it says there's something fundamentally wrong with quantum mechanics is because quantum mechanics does not allow this. It does not allow quantum information to simply evaporate away and poof out of the universe and cease to exist. It's a violation of something called unitarity. But really, the idea is it's the loss of quantum information that's intolerable. Quantum mechanics was built to preserve information. It's one of the sacred principles. As sacred as conservation of energy, in this example, more sacred.
1:21:39 Speaker 01 Because you can violate conservation of energy with Heisenberg's uncertainty principle a little tiny bit. But so sacred that it created what became coined as the black hole wars, where people were saying, look, general relativity is wrong. Something's wrong with our thinking about the event horizon. Or quantum mechanics isn't what we think it is. But the two are not getting along anymore. And just to tell you how dramatic it is. So the temperature goes down with the mass of the black hole. Heavier a black hole, the cooler it is. So we don't see black holes evaporate. They're way too big. But as they get smaller and smaller, they get hotter and hotter. So as a black hole nears the end of this cycle of evaporating away,
1:22:24 Speaker 01 it takes a very long time, much longer than the age of the universe. It will be as though the curtain, the event horizon is yanked up. Like it'll literally explode away. Just boom. And the event horizon, in principle, would be yanked up. Everything's gone. All that information that went into the black hole, all that sacred quantum stuff, gone, poof. Okay, because it's not in the radiation, because the radiation has no information. And so it was an incredibly productive debate. Because in it are the signs of what will make gravity and quantum mechanics play nice together, you know, some quantum theory of gravity.
1:23:07 Speaker 01 Whatever these clues are, and they're hard to assemble. If you want a quantum gravity theory, it has to correctly predict the temperature of a black hole, the entropy of a black hole. It has to have all of these correct features. The black hole is the place on which we can test quantum gravity.
1:23:23 Lex Fridman? But it still has not been resolved.
1:23:25 Speaker 01 It has not been fully resolved.
1:23:27 Lex Fridman? I looked up all the different ideas for the resolution. So there's the information loss, which is what you refer to.
1:23:33 Speaker 01 Right.
1:23:33 Lex Fridman? It's perhaps the simplest, yes, most radical resolution is that information is truly lost. This would mean quantum mechanics, as we currently understand it specifically, unitarity is incomplete or incorrect under these extreme gravitational conditions.
1:23:47 Speaker 01 I'm unhappy with that. I would not be happy with information loss. I love that it's telling us that there's this crisis, because I do think it's giving us the clues. And we have to take them seriously.
1:23:58 Lex Fridman? For you, the gut is like.
1:24:00 Speaker 01 Unitary is going to be preserved.
1:24:01 Lex Fridman? Preserved. So quantum mechanics is.
1:24:04 Speaker 01 We have to come to the rescue. As Lenny Suskind, in his book, Black Hole War, says, his subtitle is, My Battle with Stephen Hawking to Make the World Safe for Quantum Mechanics. Something to that effect.
1:24:17 Lex Fridman? So then, from string theory, one of the resolutions is called fuzzballs. I love physics so much. Originating from string theory, this proposal suggests that black holes aren't singularity surrounded by empty space and an event horizon. Instead, they are horizonless, complex, tangled objects, AKA fuzzballs, made of strings and brains roughly the size of the would be event horizon. There's no single point of infinite density and no true horizon to cross.
1:24:44 Speaker 01 In some sense, it says there's no interior to the black hole, nothing of a cross. So I gave you this very nice story that there's no drama. Sometimes that's how it's described at the event horizon and you fall through and there's nothing there. This other idea says, well, hold on a second. If it's really strings, as I get close to this magnifying quality and slowing time down near the event horizon, it is as though I put a magnifying glass on things and now the strings aren't so microscopic, they kind of schmear around. And then they get caught like a tangle around the event horizon and they just actually never fall through. I don't think that either, but it was interesting.
1:25:20 Lex Fridman? So it's just adding a very large number of extra complex.
1:25:25 Speaker 01 Degrees of freedom.
1:25:26 Lex Fridman? Yeah.
1:25:27 Speaker 01 There are no teeny tiny marbles to fall through.
1:25:29 Lex Fridman? But it's similar to what we already have with quantum mechanics. It's just giving a.
1:25:33 Speaker 01 But it's really saying the interior is just not there ever. Nothing falls in. So the information gets out because it never went in in the first place.
1:25:40 Lex Fridman? Oh, interesting. So there is a strong statement there.
1:25:42 Speaker 01 There's a strong statement there, yeah.
1:25:43 Lex Fridman? Okay, soft hair challenges the classical no hair theorem by suggesting that black holes do possess subtle quantum quote hair. This isn't classical hair like charge, but very low energy quantum excitations, soft gravitons or photons at the event horizon that can store information about what fell in.
1:26:05 Speaker 01 Worth trying, but I also don't think that that's the case. So the no hair theorems are formal.
1:26:14 Speaker 01 Proofs that the black hole is this featureless, perfect, fundamental particle that we talked about, that all you can ever tell about the black hole is its electrical charge, its mass, and its spin, and that it cannot possess other features. It has no hair is one way of describing it, and that those are proven mathematical proofs in the context of general relativity. So the idea is, well, therefore, I can know nothing about what goes into the black hole, so the information is lost. But if they could have hair, I could say that's my black hole, because it'd have features that I could distinguish, and it could encode the information that went in in this way. And the event horizon isn't so serious, isn't such a stark demarcation between events inside and outside, and where I can't know what happened inside or outside. And I don't think that's the resolution either,
1:26:59 Speaker 01 but it was worth a shot.
1:27:00 Lex Fridman? Okay, the pros and cons of that one. The pros, it works within the framework of quantum field theory in curved spacetime, potentially requiring less radical modifications than fuzzballs or information loss. Recent work by Hawking, Perry, Strominger revitalizes this idea. The cons is that the precise mechanism by which information is encoded and transferred to the radiation is still debated and technically challenging to work out fully, and indeed, it needs to store a vast amount of information. Okay, another one, this is a weird one, boy, is ER equals EPR.
1:27:33 Speaker 01 This is probably it, though.
1:27:35 Lex Fridman? Oh, boy. So ER equals EPR is Einstein-Rosen bridge equals Einstein-Podolsky-Rosen bridge posits a deep connection between quantum entanglement and spacetime geometry, specifically Einstein-Rosen bridge, commonly known as wormholes. It suggests that entangled particles are connected by a non-traversable wormhole, so tiny wormholes, connected. Okay.
1:28:01 Speaker 01 I can say that this is not A situation where we can follow the chalk. We can't start at the beginning and calculate to the end. So it's, it's still a conjecture. I think it's very profound, though. I kind of imagine Juan Maldacena, who's part of this with Lenny Suskin. They were kind of like, oh, it's like ER equals EPR. They couldn't even formulate it properly. It was like an intuition that they had kind of landed on. And now we're trying to formalize. But to take a step back, one way of thinking about ER equals EPR, you have to talk about holography first. And holography, both Juan Maldacena really formalized it, Lenny Suskin suggested it. The idea of a black hole hologram is that all of the information
1:28:45 Speaker 01 in the black hole, whatever it is, whatever, you know, entropy as a measure of information, whatever the entropy of the black hole is, which is telling you how much information is hidden in there, how much information you don't have direct access to, in some sense, is completely encoded in the area of the black hole. Meaning, as the area grows, the entropy grows. It does not grow as the volume. This actually turns out to be really, really important. If I tried to pack a lot of information into a volume, more information than I could pack, let's say, on the surface of a black hole, I would simply make a black hole. And I would find out, oh, I can't have more information than I can fit on the surface. So Lenny coined this a hologram.
1:29:29 Speaker 01 People who take it very seriously say, well, again, maybe the interior of the black hole just doesn't exist. It's a holographic projection of this two dimensional surface. In fact, maybe I should take it all the way and say, so are we. The whole universe is a holographic projection of a lower dimensional surface. Right? And so people have struggled, nobody's really landed it, to find a universe version of it. Oh, maybe there's a boundary to the universe where all the information is encoded. And this entire three dimensional reality is so compelling and so convincing is actually just a holographic projection. Juan Maldacena did something absolutely brilliant. It's the most highly cited paper in the history of physics. It was published in the late 90s.
1:30:11 Speaker 01 It has a very opaque title that would not lead you to believe it's as revelatory as it is. But he was able to show that a universe like in a box with gravity in it, it's not the same universe we observe, doesn't matter, it's just a hypothetical called an anti-decider space. This universe in a box, it has gravity, it has black holes, it has everything gravity can do in it. On its boundary is a theory with no gravity, a universe that can be described with no gravity at all, so no black holes and no information loss problem. And they're equivalent, that the interior universe in a box is a holographic projection
1:30:53 Speaker 01 of this quantum mechanics on the boundary. Pure quantum mechanics, purely unitary, no loss of information. None of this stuff could possibly be true. There can't be loss of information if this dictionary really works, if the interior is a hologram, a projection of the boundary. I know that's a lot.
1:31:14 Lex Fridman? Yeah. So there's some mathematics there, there's physics, and then there's trying to conceive what that actually means practically for us.
1:31:24 Speaker 01 Well, what it would mean for us is that information can't be lost, even if we don't know how to show it in the description in which there are black holes. It means it can't possibly be lost because it's equivalent to this description with no gravity in it at all, no event horizons, no black holes, just quantum mechanics. So it really strongly suggested that quantum mechanics was going to win in this battle, but it didn't show exactly how it was going to win. So then comes ER equals EPR, a visual way to imagine what this means. So ER has to do with little wormholes.
1:32:06 Speaker 01 EPR Einstein Podolsky Rosen has to do with quantum entanglement. The idea was, well, maybe the stuff that's interior to the black hole is quantum entangled, like EPR, quantum entangled with the Hawking radiation outside the black hole that's escaping. And that quantum entanglement is what allows you to extract the information because it's not actually physically moving from the interior to the exterior. It's it's just subtle quantum entanglement. And in fact, I can kind of think of the entire black hole. If I look at it, it looks like a solid shadow cast on the sky, some region of spacetime.
1:32:47 Speaker 01 If I look at it very closely, I will see, oh, no, it's actually sewn from these quantum wormholes, like embroidered. And so when I get up close, it's almost as though the event horizon isn't the fundamental feature on the spacetime. The fundamental feature is the quantum entanglement embroidering the event horizon.
1:33:11 Lex Fridman? The embroidering is just tiny wormholes. So the quantum entanglement is when two particles are connected at arbitrary distances.
1:33:22 Speaker 01 And they're connected by a wormhole.
1:33:23 Lex Fridman? And in this case, they would be connected by a wormhole.
1:33:26 Speaker 01 Hmm. So the reason why that's helpful, it helps you connect the interior to the exterior without trying to pass through the event horizon.
1:33:35 Lex Fridman? The cons of this theory is highly conceptual and abstract. The exact mechanism for information retrieval via these non-traversable wormholes is not fully understood, primarily explored in theoretical toy models. Whoa, Gemini going hard. Theoretical toy models like the anti-decider space spacetime rather than realistic black holes.
1:34:03 Speaker 01 True. We do what we can do. And baby steps.
1:34:07 Lex Fridman? So another idea to resolve the information paradox is firewalls, proposed by Amary Maroff, Polczynski, and Sully, Ams. This is a more drastic scenario arising from analyzing the entanglement requirements of Hawking radiation to preserve unitarity and avoid informational loss. They argued that the entanglement structure requires the event horizon not to be smooth, not to be the smooth and remarkable place predicted by general relativity, the equivalence principle. Instead, it must be a highly energetic region, a quote firewall, that incinerates anything attempting to cross it. Okay, so yeah, that's a nice solution. Just destroy everything that crosses this.
1:34:53 Lex Fridman? Do you find this at all a convincing resolution to the information?
1:34:56 Speaker 01 I would say the firewall papers were fascinating and were very provocative and very important in making progress. I don't even think the authors of those papers thought firewalls were real. I think they were saying, look, we've been brushing too much under the rug. And if you look at the evaporation process, it's even worse than what you thought previously. It's so bad that I can't get away with some of these prior solutions that I thought I could get away with. There was a kind of duality idea or a complementarity idea that, oh, well, maybe one person thinks they fell in and one person thinks they never fell in, and that's okay, you know, no big deal. They sort of exposed flaws in these kind of approaches,
1:35:38 Speaker 01 and it actually reinvigorated the campaign to find a solution. So it stopped it from stalling. I don't think anyone really believes that the event horizon, at the event horizon, you'll find a firewall. But it did lead to things like the entangled wormholes embroidering a black hole, which is, was born out of an attempt to address the concerns that Ams raised.
1:36:05 Speaker 01 So it did lead to progress.
1:36:07 Lex Fridman? So for you, the resolution would.
1:36:10 Speaker 01 I'm going back to the vacuum.
1:36:12 Lex Fridman? You go back to.
1:36:12 Speaker 01 The empty space, the beautiful event horizon.
1:36:14 Lex Fridman? Yep.
1:36:15 Speaker 01 I'll give up.
1:36:18 Speaker 01 I'll give up locality, meaning that I will allow things to be connected non-locally by a wormhole.
1:36:26 Lex Fridman? So that is the weirdest thing you're willing to allow for, which is arbitrary distance connection of particles through a wormhole. But quantum mechanics must be preserved.
1:36:36 Speaker 01 I'll entertain pretty weird things, but I think that's the one that sounds promising. The implications are so dramatic because this is why you start to hear things like, wait a minute, if the event horizon only exists when it's sewn out of these quantum threads, does that mean that gravity is fundamentally quantum mechanics? Not that gravity and quantum mechanics get along and I have a quantum gravity theory and I now know how to quantize gravity. Actually, something much more dramatic. Gravity is just kind of emerging from this quantum description, that gravity isn't fundamental. And what is the only thing that we have when we go rock bottom, when we go deeper and deeper, smaller and smaller, is quantum mechanics.
1:37:21 Speaker 01 So all of this, like spacetime looks nice and smooth and continuous, but if I look at the quantum realm, I'll see everything sewn together out of quantum threads. And that spacetime is not a smooth continuum all the way down. Now, people already thought that, but they thought it kind of came in chunks of spacetime. Instead, maybe it's just quantum mechanics all the way down.
1:37:43 Lex Fridman? Quantum threads, so these entangled particles connected by wormholes. So that's what, that's how you would, how would you even visualize a black hole in that way? So it's all.
1:37:58 Lex Fridman? I mean, it's all sort of from our perspective in terms of detecting things, the light goes going in. It's all still the same, but when you zoom in a lot.
1:38:07 Speaker 01 When you zoom in a lot to the quantum mechanical scale at which you're seeing the Hawking radiation, you would be noticing that there's there's some entanglement between the radiation that I could not explain before and the interior of the black hole. So it's now no longer a perfectly thermal spectrum with no features that only depends on the mass. It actually has a way to have an imprint of the information interior to the black hole in the particles that escape. And so now, in principle, I could sit there for a very long time. It might take longer than the age of the universe and collect all the Hawking radiation and see that it actually had details in it that are going to explain to me
1:38:51 Speaker 01 what was interior to the black hole. So the information is no longer lost.
1:38:55 Lex Fridman? So yeah, so information is not being destroyed. So in theory, you should be able to get information.
1:39:00 Speaker 01 Now, I can't do that any more than I can recover the words on that piece of paper once it's been burnt. But that's a practical limitation, not a fundamental one. It's just too hard. But when I burn a piece of paper, technically, the information is all there somewhere. It's in the smoke. It's in the currents. It's in the molecules. It's in the ink molecules. But in principle, if I had took the age of the universe, I could probably reconstruct. I should be able to, in principle, reconstruct the piece of paper and all the words on it.
1:39:29 Lex Fridman? Do you think a theory of everything that unifies general relativity and quantum mechanics is possible? So we're like skirting around it.
1:39:37 Speaker 01 Yeah, we're skirting around it. I think that this is the way to find that out. It's going to be on the train of black holes that we figure out if that's possible.
1:39:47 Speaker 01 I think that this is suggesting that there might not be a theory of quantum gravity, that gravity will emerge at a macroscopic level out of quantum phenomena. Now, we don't know how to do that yet. But these are all hints.
1:40:01 Lex Fridman? Emerge. So a lot of the mathematics of anything that emerges from complex systems is very difficult to.
1:40:08 Speaker 01 The transition's very difficult, right?
1:40:10 Lex Fridman? So if that's the case, there might not be a simple, clean equation. That connects everything.
1:40:16 Speaker 01 There are examples of emergent phenomena which are very simple and clean. Like, I can just take electromagnetic scattering, which is law of physics where particles scatter just electromagnetically, and I have a lot of them, and I have a lot of them in this room, and they come to some average, well, I call that temperature. Right? And that one number, the fact that there's one number describing all of these gazillions of particles, is an emergent quantity. It's, there's no particle that carries around this fundamental property called temperature. Right? It emerges from the collective behavior of tons and tons of particles. In some sense, temperature is not a fundamental quantity. It's not a fundamental law of nature. Right?
1:40:58 Speaker 01 It's just what happens from the collective behavior. And that's what we'd be saying. We'd be saying, oh, this emerges from the collective behavior of lots and lots and lots of quantum interactions.
1:41:14 Lex Fridman? So when do you think we would have some breakthroughs on the path towards theory of everything, showing that it's possible or impossible, all that kind of stuff? If you look at the 21st century, say, you move 100 years into the future and looking back, when do you think the breakthroughs will come? So I'll give you some hard problems. I guess my question is, how hard is this problem? Like, what does your gut say? Because, you know, finding the origin of life, figuring out consciousness, solving some of the major diseases, then there's the theory of everything, understanding this, resolving the information paradox.
1:41:51 Lex Fridman? So these puzzles that are before us as a human civilization, physics, this feels like really one of the big ones. Of course, there could be other breakthroughs in physics that don't solve this.
1:42:05 Speaker 01 Yeah, we could discover dark matter, dark energy, we could discover extra spatial dimensions, we could discover that those three things are linked, that there's like a dark sector to the universe that's hiding in these extra dimensions. And that's something that I love to work on, I think is really fascinating. All of those would also be clues about this question, but they wouldn't solve this problem.
1:42:29 Speaker 01 I think it's impossible to predict. There has been real progress. And the progress, as we've said, comes from the childlike curiosity of saying, "Well, I don't actually understand this. I'm going to keep leaning on it because I don't understand it." And then suddenly you realize, nobody really understood it. So I don't know. Do I think it's a harder problem than the problem of the origin of life? I think it's technically a harder problem. But I don't know. Maybe the breakthrough will come.
1:42:59 Lex Fridman? So when you mentioned discovering extra dimensions, what do you mean? What could that possibly mean?
1:43:10 Speaker 01 Well, we know that there are three spatial dimensions. We like to talk about time as a dimension. We can argue about whether that's the right thing to do. But we don't know why there are only three. It very well could be that there are extra spatial dimensions, that there's like a little origami of these tightly rolled up dimensions. Not all of them, not all the models require that they're small, but most do. String theory requires extra dimensions to make sense. But even if you feel very hostile towards string theory, there are lots of reasons to consider the viability of extra dimensions. And we think that they can trap little quantum energies
1:43:55 Speaker 01 in such a way that might align with the dark energy. The numerology is not perfect. It's a little bit subtle. It's hard to stabilize them. It's possible that there are these kind of quantum excitations that look a lot like dark matter. It's kind of an interesting idea that in the Big Bang, the universe was born with lots of these dimensions. They were all kind of wrapped up in the early universe. What we're really trying to understand is why did three get so big?
1:44:29 Speaker 01 And and why did the others stay so small?
1:44:31 Lex Fridman? Is it possible to have some kind of natural selection of dimensions kind of situation?
1:44:35 Speaker 01 Yeah, there is actually. And people have worked on that. Is there a reason why it's easier to unravel three? Some people think about strings and brains wrapping up in the extra dimensions, causing a kind of constriction, but preferentially loosening up in three. Sometimes we look at exactly models like that, which have to do with the origami being resistant to change in a certain way that only allows three to unravel and keeps the others really taut. But then there are other ideas that we're actually living on a three dimensional membrane that moves through these higher dimensions. And so the reason we don't notice them isn't because they're small.
1:45:17 Speaker 01 Maybe they're not small at all, but it's because we're stuck to this membrane. So we're unaware of these extra directions.
1:45:24 Lex Fridman? Is it possible that there's other intelligent alien civilizations out there that are operating on a different membrane? This is a bit of an out there question, but I ask it more kind of seriously. Like, is it possible, do you think, from a physics perspective, to exist on a slice of what the universe is capable of?
1:45:47 Speaker 01 I think it is certainly mathematically possible on paper to imagine a higher dimensional universe with more than one membrane. And if things are mathematically possible, I often wonder if nature will try it out.
1:46:04 Lex Fridman? Yeah.
1:46:05 Speaker 01 Just how people get into the strange territory of talking about a multiverse. Because if you start to say, one of the aspirations was, in the same way that we identified the law of electro weak theory of. Matter that it was a single description and exactly landed on the description that matched observations. People were hoping the same thing would happen for a kind of theory that also incorporated gravity. There would be this one beautiful law, but instead they got a proliferation, all of which did okay, or did equally badly. They suddenly had trouble finding, not only finding a single one, but sort of, that would just beg
1:46:48 Speaker 01 a new question, which is, well, why that one? And if, if nature can do something, won't she do anything she can try? And so maybe we really are just one example in an infinity of possible universes with slightly different laws of physics. So if I can do some of these things on paper, like imagine a higher dimensional space in which I'm confined to a brain and there's another brain, or maybe a whole array of them, maybe nature's tried that out somewhere. Maybe that's been tried out here. And then, yes, is it possible that there's life and civilizations on those other brains? Yeah, but we can't communicate with them. They'd be like in a shadow space.
1:47:31 Lex Fridman? Can you seriously say we can't communicate with them?
1:47:34 Speaker 01 Well, no, that's fair. I'm limited in my communication because I'm glued to the brain, but some things can move. We call the bulk, through the bulk, gravity, for instance, a gravitational wave. So I could design a gravitational communicator, communication system, and I could send gravitational waves through the bulk. And how SETI's doing with light into space, I could send signals into the bulk.
1:48:01 Lex Fridman? Nice.
1:48:01 Speaker 01 Telling them where we are and what we do and singing songs.
1:48:05 Lex Fridman? Sending gravitational waves is very expensive. We don't know how to.
1:48:08 Speaker 01 Very expensive, very hard to localize. They tend to be long wavelength and very hard to do. Lot of energy moving around.
1:48:16 Lex Fridman? So is it possible that the membranes are quote unquote hairy in other ways, like some kind of weird?
1:48:22 Speaker 01 It is possible that there's other things that live in the bulk. I mean, last night I was calculating away, looking at something that lives in the bulk.
1:48:31 Lex Fridman? Okay, this is fascinating. So, I mean, okay, can we take a little bit more seriously about the whole, when I look out there?
1:48:39 Lex Fridman? At the stars. I, from a basic intuition,
1:48:44 Lex Fridman? cannot possibly imagine. There's not just alien civilizations everywhere.
1:48:50 Speaker 01 Yeah.
1:48:50 Lex Fridman? Life is so damn good. Like you said, nature tries stuff out.
1:48:55 Speaker 01 Yeah. Nature's an experimenter.
1:48:57 Lex Fridman? And I just can't, just basic sort of
1:49:03 Lex Fridman? observation, life, you said somewhere that you like extremophiles. Life just figures shit out.
1:49:11 Speaker 01 Yeah.
1:49:11 Lex Fridman? It just finds a way to survive. Now, there could be something magical about the origin of life, the first spark, but like, I can't even see that. It's just over and over and over. I bet, actually, once, once the story is fully told and figured out, life originated on Earth almost right away and did that so like billions of times
1:49:31 Lex Fridman? in multiple places, just over and over and over and over. That seems to be the thing that just, whatever is the life force behind this whole thing, seems to, uh, seems to create life, seems to be a creator of different sorts.
1:49:48 Speaker 01 Hmm, yeah.
1:49:49 Lex Fridman? The, the very, from the very original primordial soup of things, it just creates stuff. I just can't imagine, but we don't see the aliens, so.
1:49:57 Speaker 01 Right, yeah. We don't even have to go to something as crazy as extra dimensions and brain worlds and all of that. What's happening right now in the past 30 years in astronomy, looking at real objects, is that the number of planets, exoplanets outside our solar system has absolutely proliferated. There are probably more planets in the Milky Way galaxy than there are stars. And now we have a real quandary. Not, I don't think it's quandary. I think it's really exciting. It becomes impossible. What you just said, I totally agree with. It becomes impossible to imagine that life was not sparked somewhere else in our Milky Way galaxy, and maybe even in our local neighborhood of the Milky Way galaxy, maybe within a few hundred light years of the Milky, of, of, of our solar system.
1:50:41 Lex Fridman? So my, my, my gut says, like, some crazy amount of, uh, solar systems have.
1:50:50 Lex Fridman? Life, bacterial life, somewhere at some point in their history had some bacterial type of life, something like bacterial, maybe it's totally different kinds of life. So then I'm just facing with the questions like, why have we not clearly seen?
1:51:07 Speaker 01 Yeah.
1:51:08 Lex Fridman? Alien civilizations and there the answer, I just, I don't find any great filter answer convincing. There's just no way I can imagine an advanced alien civilization not avoiding its own destruction. I could see a lot of them getting into trouble. I could see how we humans are really like 50 50 here.
1:51:29 Speaker 01 Well, isn't that kind of appalling? I mean, just take that statement. We've only been around for like, I mean, a couple hundred thousand years tops, you know? That is not very long and we're at a 50 50. I mean, that's unbelievable. I mean, it's indisputable that we have created the means, at least potentially for our own destruction. Will we learn from our mistakes? Will we avert course and save ourselves? One hopes so, right? But, but even the concept that it's conceivable whales have not invented a way to kill themselves, to wipe out all whales and earth and life on earth.
1:52:09 Lex Fridman? That's one way to see it, but I actually see it as a feature, not a bug, when you look at the entirety of the universe, because it does seem that the mechanism of evolution constantly creates, you want to operate on the verge of destruction, it seems like. I mean, the predator and prey dynamic is really effective at creating, at accelerating evolution and development. It seems like us being able to destroy ourselves is a really powerful way to give us a chance to really get our shit together and to flourish, to develop, to innovate, to, to go out amongst the stars or 50 50 destroy ourselves. But like, which I think me as a human is a horrible thing,
1:52:53 Lex Fridman? but if there's a lot of other alien civilizations, that's a pretty cool thing. You want to give everybody nuclear weapons. Uh, half of them will figure it out, half of them won't.
1:53:02 Speaker 01 You mean everyone, all these civilizations?
1:53:04 Lex Fridman? All these civilizations. And then the ones that figure it out will figure out some incredible technologies about how to expand, how to develop and all that kind of stuff.
1:53:11 Speaker 01 Right. You could use a kind of evolutionary Darwinian natural selection on that where in survival isn't just in a harsh, naturally induced climate change, but it's because of a nuclear holocaust. And so, but, and then, and then something will, will be created that is now impervious to that, that now knows how to survive.
1:53:31 Lex Fridman? Yep, exactly. So why haven't we seen them?
1:53:34 Speaker 01 Right. Well, because that's a pretty big bar. So if you look at the, just to say, for comparison, dinosaurs, you know, 250 million years. I mean, maybe not very bright.
1:53:49 Speaker 01 Didn't invent fire, didn't write sonnets.
1:53:52 Lex Fridman? Yeah.
1:53:52 Speaker 01 They didn't contemplate the origin of the universe, but they, they lived. And in a benign situation without confronting their own demise at their own hands. Paws, hooves. So it's just a sheer numbers game. That's a long time, 250 million years. I do think though, that life can flourish without wanting to manipulate its environment. And that we do see many examples of species on earth that are very long-lived, very, very long-lived, and have very different states of consciousness. They have, the jellyfish does not even have a localized brain. I don't think they have a heart or a blood. I mean,
1:54:36 Speaker 01 they're really different from us. Okay. And that's what I think we have to start thinking about when we think about aliens. Those species have lived for a very, very long time. They even show some evidence of immortality. You can wound one badly, and there are certain jellyfish that will go back into a kind of pre-state and start over. So I think we're very attached to imagining creatures like us that manipulate technology. And, and I think we have to be way more imaginative if we're going to really take seriously life in the universe.
1:55:11 Lex Fridman? Yeah, they might not prioritize conquest and expansion. They might not be violent.
1:55:18 Speaker 01 Mm-hmm. They might not be violent.
1:55:20 Lex Fridman? Like us humans.
1:55:22 Speaker 01 They might be solitary, they might not be social, they might not move in groups, they might not want to leave records.
1:55:29 Speaker 01 They might, again, not have a localized brain or have a completely different kind of nervous system. I think all we can say about life is it has something to do with moving electrons around. And like neurologically, we move electrons through our nervous system. Our brain has electrical configurations. We metabolize food and that has to do with getting energy, electrical energy in some sense, out of what we're eating. And we have organisms on the earth that can eat rocks. It's quite amazing. Minerals, I mean, talk about extremophiles. They can metabolize things that I would have thought were impossible to metabolize.
1:56:08 Speaker 01 And so, again, I think we have to kind of open our minds to how strange that could be and how different from us. And we are the only example, even here on earth, that does manipulate its environment in that extreme a way.
1:56:27 Lex Fridman? I mean, can you think of life as, as you said, electrons? Is there some degree of information processing required? So like, it does something interesting, in quotes, with information?
1:56:42 Speaker 01 I think there are arguments like that. How entropy is changing from the beginning of the universe to today, how life lowers entropy by organizing things, but it costs more as a whole system. So the whole entropy of the whole system goes up. But, but of course, I organized things today and reduced the entropy of certain things in order to get up and get here. And even having this conversation, organizing thoughts out of the cloud of information, but it comes at the cost of the entire system increasing entropy. So I do think there's probably a very interesting way to talk about life in this way. I'm sure somebody has.
1:57:24 Lex Fridman? Yeah, yeah. It creates local pockets of low entropy. And then the kind of mechanism, the kind of object, the kind of life form that could do that probably can take arbitrary forms. And you could think now, if you could reduce it all to information, now you could start to think about physics. And then the realm of physics was the multiverse and all this kind of stuff. You could start to think about, okay, how do I detect those pockets of low entropy?
1:57:52 Speaker 01 Yeah, I mean, people have tried to make arguments like that, like, can I look for entropic arguments that might suggest we've done this before? The Big Bang has happened before.
1:58:08 Lex Fridman? So is it possible that there's some kind of physics explanation why we haven't seen the aliens? Like we said, membranes?
1:58:15 Speaker 01 I don't think membranes is going to explain why we don't see them in the Milky Way. I think that is just a problem we're stuck with, whether or not there are extra dimensions, or whether or not there's life in another membrane. I think we know that even just in our galaxy, which is a very small part of the universe, 300 billion stars, something like that, a whole kind of variety of possibilities to be explored by nature, in the same way that we're describing it. And I think you're absolutely right, when when life was kicked off, first sparked here on Earth, it was voracious. And it took a really long time, though, to get to multicellularity. I think that's interesting.
1:58:54 Lex Fridman? That's weird.
1:58:55 Speaker 01 It's weird. It took a really, really long time to become multicellular. But it it did not take long just to start.
1:59:04 Lex Fridman? Yeah. What do you think is the hardest thing on the chain of leaps that got to humans?
1:59:12 Speaker 01 I would say multicellularity, which is strictly an energy problem, I think. Again, it's just like, can electrons flow the right way? And is it energetically favorable for multicellularity to exist? Because if it's energetically expensive, it's not going to succeed. And if it's energetically favorable, it's going to take off. It's really just, and that's why I also think that going from inanimate.
1:59:45 Speaker 01 To animate is probably gray. Like, the transition is gray. At what point we call something fully alive? Famously, it's hard to make a nice list of bullet points that need to be met in order to declare something alive. Is a virus alive? I mean, I don't know. Is a prion alive? Those are, they seem to do some things, but they kind of rely on stealing other DNA and replicating. And I don't know. I guess they're not alive. But I mean, the point is, is that it really, at the end of the day, I really think it's just, you asked if it's just physics. I mean, I think it's just this, these rules of energetics.
2:00:26 Lex Fridman? And the gray area between the nonliving and the living is way simpler just on Earth. And you said it's already complicated on Earth, but it's probably even more complicated elsewhere, where the chemistry could be anything.
2:00:37 Speaker 01 Carbon is really cool and really useful.
2:00:40 Lex Fridman? Yes.
2:00:40 Speaker 01 Because it finds a lot, it's nice. It finds a lot of ways to combine with other things. And that's complexity. And complexity is the kind of thing you need for life. You can't have a very simple linear chain and expect to get life. But I don't know, maybe sulfur would do okay.
2:00:56 Lex Fridman? Okay, as we get progressively towards crazier and crazier ideas. So we talked about these microscopic wormholes, which, you know, my mind is still blown away by that. But if we talk about a little bit more seriously about wormholes in general, also called Einstein Rosen bridges. To what degree do you think they're actually possible as a thing to study, creeping towards the possibility, maybe centuries from now, of engineering ways of using them, of creating wormholes and using them for transportation of human-like organisms?
2:01:36 Speaker 01 I think wormholes are a perfectly valid construction to consider.
2:01:41 Speaker 01 They're just, they're just a curve in spacetime. The topologically, which has to do with the connectedness of the space is a little tricky because we know that Einstein's description is completely in terms of local curves and distortions, expansion, contraction, but it doesn't say anything about the global connectedness of the space. Because he knew that it could be globally connected on the largest scales. This kind of origami that we're talking about, that you could travel in a straight line through the universe, leave our galaxy behind, watch the Virgo cluster drift behind us and travel in a straight line as possible and find ourselves coming back again to the Virgo cluster and eventually the Milky Way and eventually the Earth, that we could find ourselves on a connected, compact spacetime.
2:02:26 Speaker 01 And so, topologically, there's something, we know for sure, something beyond Einstein's theory that has to explain that to us. Now, wormholes are a little funky because they're topological. You know, they create these handles and holes and these sneaky, by topological, I mean these connected spaces and...
2:02:45 Lex Fridman? Yes, like Swiss cheese or something.
2:02:48 Speaker 01 Like Swiss cheese and they, right, and they, so I could have, you know, I could have two like flat sheets that are connected by a wormhole but then wrap around on the largest scale, you know, all this cool stuff. There's nothing wrong with it, as far as I can see, there's nothing abusive towards the laws about a wormhole, but we can reverse engineer. We were saying, oh, look, if I know how matter and energy are distributed, I can predict how spacetime is curved, I can reverse engineer. I can say, I want to build a curved spacetime like a wormhole. What matter and energy do I need to do that? It's a simple process and it's kind of thing Kip Thorne worked on, very imaginative, creative person.
2:03:29 Speaker 01 And the problem was that he said, oh, you know, here's the bummer. The matter and energy you need doesn't seem to be like anything we've ever seen before. It has to have like negative energy. That's, that's not great. There are some conjectures that we shouldn't allow things that have that kind of a property that have negative energies. Only things that have positive energies are going to be stable. And long-lived, but we actually know of quantum examples of negative energy. It's not that crazy. There's something called the Casimir effect. You have two metal plates and you put them really close together. You can see this kind of quantum fluctuation between the plates. It's called a Casimir energy. And, and that can have a negative energy.
2:04:14 Speaker 01 Can actually cause the place to attract or repel, depending on how they're configured. And, and so you could kind of imagine doing something like that, like having wormholes propped up by these kinds of quantum energies. And people have thought of imaginative configurations to try to keep them propped up. Is it, are we at the point of me saying, oh, this is an engineering problem? I'm not saying that quite yet, but it's certainly plausible.
2:04:43 Lex Fridman? Yeah, so you have to get a lot of this kind of weird matter.
2:04:48 Speaker 01 You need a lot of this weird matter to send a person through.
2:04:51 Lex Fridman? Right.
2:04:52 Speaker 01 That's going to be really telling. So I'm not saying it's simply an engineering problem, but it's all within the realm of plausible physics, I think.
2:05:01 Lex Fridman? I think that's super interesting. And I think it's obviously intricately and deeply connected to black holes. Is it fair to think of wormholes as just two black holes that are connected somehow?
2:05:11 Speaker 01 People have looked at that. They tend to be non-traversable wormholes. They're, they're not trying to prop them open. But yeah, I mean, some of this ER equals EPR quantum entanglement, they're, they're trying to connect black holes.
2:05:28 Speaker 01 You know, it's, it's really cool. It's not quite, again, it's not quite following the chalk. And by that, I mean, we can't exactly start at a concrete place, calculate all the way to the end yet.
2:05:39 Lex Fridman? So if I may read off some of the ideas that Kipdon has had about how to artificially construct wormholes. So the first method involves quantum mechanics and the concept of quantum foam. And this is the thing we've been talking about. Now, to create a wormhole, these tiny wormholes would need to be enlarged and stabilized to be useful for travel. But the exact method of doing this remains entirely theoretical. No shit, you think so? So this, these tiny wormholes that are basically for the quantum entanglement of the particles somehow enlarged.
2:06:13 Lex Fridman? Man, playing with the topology of the Swiss cheese would be so interesting. Even to get a hint.
2:06:21 Lex Fridman? That would be like top three, if not one of, maybe even number one question for me to ask. If I got a chance to ask.
2:06:28 Speaker 01 An omniscient.
2:06:29 Lex Fridman? Omniscient being of like a question that I can get answered to. Maybe with some visualization. Like the shape, the topology of the universe.
2:06:40 Speaker 01 Yeah.
2:06:41 Lex Fridman? But like, I need some details.
2:06:42 Speaker 01 Right.
2:06:43 Lex Fridman? Unfortunately, I'll get an answer that I can't possibly comprehend.
2:06:46 Speaker 01 Right. It's a hyperbolic manifold that's identified across.
2:06:50 Lex Fridman? Yeah.
2:06:51 Speaker 01 You need to be able to ask a follow up question.
2:06:53 Lex Fridman? Exactly. Yeah, that would be so interesting. Anyway. Classical quantum strategy, the second approach combines classical physics with quantum effects. This method, this method would require an advanced visualization to manipulate quantum gravity effects in ways we don't yet understand. There's a lot of.
2:07:09 Speaker 01 In ways we don't understand.
2:07:10 Lex Fridman? Yeah, there's a lot of, and then there's exotic matter requirements. There's a lot of.
2:07:14 Speaker 01 But I can tell you. I'm pretty sure all of them have in common the feature that they're saying, here's what I want my wormhole to look like first. So it's like saying, I want to build the building first. So they are, they construct, there's an architecture of the space time that they're after. And then they reverse the Einstein equations to say, what must matter and energy? What are the conditions that I impose on matter and energy to build this architecture?
2:07:43 Lex Fridman? Which is unfortunately a very early step of figuring out.
2:07:47 Speaker 01 Right, but it's important because it's how they realized, oh, wow, they have to have these negative energies. They have to violate certain energy conditions that we often assume are true. And then you either say, oh, well, then all bets are off, they'll never exist. Or you look a little harder and you say, well, I can violate that energy condition without it being that big a deal. And again, quantum mechanics often does violate those energy conditions.
2:08:14 Lex Fridman? So do you think the studying of black holes and some of the topics we've been talking about will allow us to travel faster than the speed of light, or travel close to the speed of light, or do some kind of really innovative breakthroughs on the propulsion technology we use for traveling in space?
2:08:29 Speaker 01 Yeah, I mean, sometimes I assign in an advanced general relativity class, the assignment of inventing a warp drive. And it's kind of similar. So the idea is, here's a place you want to get to. And can you contract the spacetime between you with some, so the kind of something antithetical to dark energy, the opposite, and skip across and then push it back out again? That's all, you can do that in the context of general relativity. Now, I can't find the energy that has these properties, but I also can't find dark energy. So we've already been confronted with something that we look at the spacetime, the spacetime
2:09:12 Speaker 01 is expanding ever faster. We say, what could possibly do that? We don't know what it is, but I can tell you about its pressure. I can tell you certain features about it. And I just call it dark energy, but I actually have no idea. It's just, that name's just a proxy for what this, it should be called invisible because it's not actually dark. It's in this room. It's not hard to see through. It's not dark. It's, it's literally invisible. So maybe that was a misnomer. But the point being, I still don't fundamentally know what it is. That's not so terrible. That's, that's the state of the world that we're actually in. So maybe warp drive is just kind of like a version of that. I, I don't know what form of matter can do that yet, but at least I can identify the features that are needed.
2:09:53 Lex Fridman? So figuring out what dark energy is might land some clues.
2:09:58 Speaker 01 Yeah, actually, it might. It is, it is positive energy and a negative pressure, which is kind of like a rubber band sort of quality. We think of pressure as pushing things outward. And dark energy has a very strange sort of quality that as things move outward, you feel more energy as opposed to less energy. The energy doesn't get lower, it gets more. But it, so it doesn't have the right features for the wormhole, but those are some pretty surprising features.
2:10:26 Speaker 01 We again can conjecture like, oh, hey, you know, the quantum energy of the vacuum kind of behaves that way. That would be a great resolution to the dark energy problem. It's just the energy of empty space. And it's the quantum energy of empty space. That's an excellent answer. The problem is, is by all our methods and all the understanding we have, that energy's either really, really huge, huge, way bigger than what we see today, or it's like zero. So that's a numbers problem. We can't naturally fine tune the energy of empty space to give us this really weird value so that we just happen to be seeing it today.
2:11:08 Speaker 01 But again, we can think of a kind of dark energy that exists. So the question is just, why is it, it becomes, why is it such, such a weird value? Not how is this conceivable? Because we can't conceive of it.
2:11:22 Lex Fridman? Yeah, but if it's a weird value, that means there is a phenomenon we don't understand.
2:11:26 Speaker 01 Yes, there's absolutely a phenomenon. Nobody's going to say they're happy with that. We're all going to say there's something we don't understand, which is why we look to the extra dimensions. Because then you can say, oh, maybe it has to do with the size of the extra dimensions or the way that they're wrapped up. Or, and so maybe there's, it's foisted on us because of the topology, the connectedness of the higher dimensional space. These are all things that we're exploring. Nobody's landed one that's so compelling that your friends like it as much as you do.
2:11:56 Lex Fridman? What, what, what do you think would lead to the breakthroughs on dark matter and dark energy?
2:12:01 Speaker 01 I think dark matter might be less peculiar than dark energy. My hope is that they're tied together. That's, that would be very gratifying. These aren't just separate problems coming from different sectors, but that they're actually connected. That the reason the dark matter is where it is in terms of how much it's contributing to the universe is, is connected with why the dark energy is showing up right now. I would love that. That would be a solution like no other. Right? And like I said, if it revealed something about dark dimensions, you know, that's. That would be a happy day.
2:12:42 Lex Fridman? Correct me if I'm wrong, so dark matter could be localized in space.
2:12:46 Speaker 01 Yeah, dark matter is localized in space, so it clumps. I mean, it doesn't, it doesn't clump a lot, you know, but, but I mean, it's around the galaxy. It's in a halo around the galaxy.
2:12:54 Lex Fridman? And so people get increasingly more confident that it does a thing.
2:12:57 Speaker 01 Oh, it's really compelling.
2:12:59 Lex Fridman? Yeah.
2:12:59 Speaker 01 I mean, you see these images of galaxies that clusters that pass through each other. And you can see where the light is, the luminous matter is distributed. And then by looking at the gravitational lensing, which shows you where the actual mass is distributed. So that light bends around the most massive parts in a particular way. So you can reconstruct where the mass is gravitationally, quite separate from looking at the luminous matter, which is not dark, and they are separate. Because the stuff, as they pass through each other, the interacting stuff, the luminous stuff collides and gets stuck in, you can see it colliding and lighting up.
2:13:43 Speaker 01 The dark stuff, which by definition, it's dark because it doesn't interact, passes right through, it's right through each other, right? And this is, I mean, it's so compelling. And there's lots of other observations, but, but that one is just, before you just look at it, you can see that the mass is distributed differently than the interacting luminous matter.
2:14:06 Lex Fridman? So dark energy is harder to get a hold of.
2:14:09 Speaker 01 Dark energy is much harder to get a hold of. But, you know, I mean, the Higgs field could have also explained dark energy.
2:14:16 Lex Fridman? Yeah.
2:14:16 Speaker 01 If you've heard of the God particle. I don't know if you know the, originally Leon Letterman co-authored a book and he wanted to call it the goddamn particle because they couldn't find it. And his, his publisher convinced him to call it the God particle. And he said, he said they managed to offend two groups, those that believed in God and those that didn't.
2:14:39 Lex Fridman? That's a good line, too.
2:14:41 Speaker 01 He was very funny. He was very witty.
2:14:43 Lex Fridman? So, you know, Higgs turned out to be...
2:14:45 Speaker 01 Higgs, great discovery. I mean, unbelievable. There it was. Build this massive collider in CERN in Switzerland, and there it is. Unbelievable. Kind of where you expect it to be. Now, the reason I say it could be dark energy is because the Higgs particle, like a particle of light, also has a field, like an electromagnetic field. So, light can have this field that's distributed through all space, electromagnetic field, and you shake it around and it creates little particles. So, the Higgs field is actually more important than the Higgs particle, the complement to the Higgs particle, because that's what you and I connect with to get mass in our atoms.
2:15:27 Speaker 01 So, the idea is that our atoms are interacting with this gooey field that's everywhere. And that's what's giving us this experience of inertial mass. But we don't actually... There's not a lot of quanta lying around. There's not a lot of Higgs particles lying around because they decay. So, it's the field that's really important. And that field could act like a dark energy. It's just not in the right place, meaning it's not at the right... The energy's too high to explain this tiny, tiny value today. And again, we're back to this mismatch. It's not that we can't conceive of forms of dark energy. It's that we can't make one where we're finding it.
2:16:08 Lex Fridman? So, I wonder if you can comment on something that I've heard recently. There's some people who say...
2:16:17 Lex Fridman? People outside of physics say that, you know, dark matter and dark energy is just something physicists made up. To put a label on the fact that they don't understand a very large fraction of the universe and how it operates. Is there some truth to that? What's your response to that?
2:16:33 Speaker 01 There is some truth to it, but it's really missing a huge point, which is that if we did not understand the universe as incredibly precisely as we do, it's stunning that there's... Modern precision cosmology. It's absolutely incredible. When COBE, which is an experiment that measured the light left over from the Big Bang in the eighties, first revealed its observations. I mean, there was applause, you know? People were cheering, right? It was unbelievable. We had predicted and measured the light left over from the Big Bang. And because of all the precision that's happened since then, that's how we're able to confront that there's things that we don't know.
2:17:16 Speaker 01 And that's how we're able to confront, wow, this is really, everything everybody has ever seen and ever will see, as far as we understand, makes up less than 5% of what's out there.
2:17:27 Lex Fridman? Yeah.
2:17:28 Speaker 01 And, and so I would say, yes, we're just giving proxy names to things we don't understand. But to dismiss that as some kind of, oh, they just don't know. It is actually quite the opposite. It is a stunning achievement to be able to stare that down. And to have that so precise and so compelling that we're able to, to, to know that there's dark energy and dark matter. I don't think those are disputed anymore. And they were up until, you know, recently, they were still disputed.
2:17:58 Lex Fridman? I think we're still at such early stages where we're not really even at a good explanation. Right? You've mentioned a few.
2:18:05 Speaker 01 Well, I can think of examples of dark matter that exist that we really know for sure, are real versions of dark matter, like neutrinos, right? Now they're radiating through us. That's very well confirmed. And they're technically dark. They don't interact with light. And so we can't see them. Right now, they're raining through us. If we could see the dark matter in this room, we absolutely know is coming from the sun, it would be wild, be a rainstorm, you know? But they're just invisible to us. Mostly, they pass through our bodies. Mostly, they pass through the earth. Occasionally, they get caught in some fancy detector experiment that somebody built specifically to catch solar neutrinos. So dark matter is known to exist. It's just, again.
2:18:51 Speaker 01 There's not enough of it. It's not the right mass to be the dark matter that makes up this missing component.
2:18:58 Lex Fridman? I wanted to say that I've been recently fascinated by the Flat Earth people. Because there's been a split in the community.
2:19:08 Lex Fridman? First of all, the community is fascinating study of human psychology, but they did
2:19:15 Lex Fridman? this experiment where I forgot who funded it, but they sent like physicists and flat earthers to Antarctica.
2:19:25 Speaker 01 Really?
2:19:26 Lex Fridman? And this split happened because half of them got converted into round earthers.
2:19:30 Speaker 01 Wow, well, good for them.
2:19:31 Lex Fridman? And but then the other half just went that it was all a psy out.
2:19:35 Speaker 01 Really? That's fascinating. Did somebody film that? That'd be a great documentary.
2:19:39 Lex Fridman? Yeah, it did. They did. They made a whole thing. This is just at the end of last year, there was a big, I mean, because I think that's such a clean study of conspiracy theories. Because like, there's so many conspiracy theories have some inkling of truth in them.
2:19:57 Lex Fridman? Like, there's some elements about the way governments operate or human psychology that there's, it's too messy. Flat Earth to me is just clean. It's like spaghetti moss or something like.
2:20:08 Speaker 01 Right.
2:20:08 Lex Fridman? It's just a cleanly wrong thing.
2:20:10 Speaker 01 Right.
2:20:11 Lex Fridman? Nice way to discuss.
2:20:12 Speaker 01 Understand the psychology.
2:20:13 Lex Fridman? How a large number of people can believe a thing.
2:20:16 Speaker 01 Yeah, and why do they want to believe a thing? What's very interesting is you trying to use rational arguments. So I, that makes it even more confounding to me. I would understand more somebody who just said, look, I have faith and I believe these things and it's not about reason and it's not about logic and, okay.
2:20:39 Speaker 01 I mean, I don't relate to it, but okay. But to say, I'm going to use reason and logic. And to prove to you this completely orthogonal conclusion, that I find really interesting. So there's some kind of romance.
2:20:54 Lex Fridman? There is.
2:20:55 Speaker 01 About reason and logic.
2:20:57 Lex Fridman? Yeah, but also there's a questioning of institutions that's really interesting and important to understand.
2:21:02 Speaker 01 Well, I mean, I, I actually appreciate the skeptics stance. I don't, scientists also have to be skeptics. We have to be childlike, naive and somewhat, in some sense, really open to anything. Right? Otherwise, you're not going to be a flexible. You're not going to be at the forefront, but, but also to be skeptical. So I have respect for it. I guess that's exactly what I'm saying is more confusing because to invoke skepticism and then to want to use rational argument. What is the other component that's, that's going into this? Because as you said, this is something that's easily verified. I mean, we have people in space.
2:21:45 Speaker 01 So you have to believe a lot more machinery.
2:21:50 Speaker 01 That's a lot more difficult to justify, explain as a wild conspiracy. So there's something about the conspiracy that stirs a positive emotion.
2:22:01 Lex Fridman? I think one of the most incredible things, I have to talk to you about this. One of the most incredible things that humans have ever accomplished is LIGO.
2:22:10 Lex Fridman? We have to talk about gravitational waves and the very fact that we're able to detect gravitational waves from the early universe is effing wild.
2:22:20 Speaker 01 It's crazy. Yeah.
2:22:21 Lex Fridman? Can you explain what gravitational waves are? And we should mention, you wrote a book about the humans, about the whole journey of detecting gravitational waves. And LIGO, Black Hole Blues is the book. But can you talk about gravitational waves and how the hell we're able to actually do it?
2:22:38 Speaker 01 Let's just start with the idea of gravitational waves. I have to move around a lot of mass to make anything interesting happening in gravity. I mean, if you think about it, gravity is incredibly weak. I mean, right now, the whole Earth is pulling on me, and I can still get out of this chair and walk around. That's insane. The whole Earth. Gravity is weak, right? So to get something going on in gravity, I need like, big objects, and things like black holes. So the idea is if black holes curve space and time around them in the way that we've been describing, things fall along the curves in space. If the black holes move around, the curves have to follow them, right? But they can't travel faster than the speed of light either. So what happens is as black holes, let's say, move around, maybe I've
2:23:23 Speaker 01 got two black holes in orbit around each other, that can happen. It takes a while. A wave is created in the actual shape of space, and that wave follows the black holes. Those black holes are undulating. Eventually, those two black holes will merge, and as we were talking about, it doesn't take an infinite time, even though there's time dilation, because they're both so big, they're really deforming spacetime a lot. I don't have a little tidy marble falling across an event horizon. I have two event horizons. And in the simulations, you can see it bobble, and they merge together, and they make one bigger black hole, and then it radiates in the gravitational waves. It radiates away all those imperfections, and it settles down to one quiescent, perfectly silent, black
2:24:06 Speaker 01 hole that's spinning. Beautiful stuff. And it emits E equals mc squared energy. So the mass of the final black hole will be less than the sum of the two starter black holes. And that energy is radiated away in this ringing of spacetime. It's really important to emphasize that it's not light. None of this has to do, literally, with light that we can detect with the normal things that detect light. X-rays form a light, gamma rays are a form of light, infrared, optical, all this whole electromagnetic spectrum, none of it is emitted as light. It's completely dark. It's only emitted in the rippling of the shape of space. A lot of times, it's likened closer to sound. Technically, we've kind of argued, I mean, I haven't done an anatomical calculation, but if you're near
2:24:50 Speaker 01 enough to two colliding black holes, they actually ring spacetime in the human auditory range, the frequency is actually in the human auditory range, that the shape of space could squeeze and stretch your eardrum, even in vacuum. And you could hear, literally hear these waves ringing.
2:25:20 Speaker 01 So the idea is that they're closer to something that you would want to map as a sound than it's something as a picture.
2:25:28 Lex Fridman? Sorry, so what do you think it would feel like to ride the gravitational waves? So like to be, to exist, to exist? Cause you mentioned eardrums.
2:25:38 Speaker 01 It would literally bob around, like your orbit would change, right? If you were orbiting these black holes, two black holes, you'd be on a kind of complicated orbit. But your orbit would get tossed about.
2:25:50 Lex Fridman? But how would the experience be? Cause you're inside spacetime.
2:25:54 Speaker 01 Yes, I see. So the, the, the, the black hole is experienced within spacetime as a squeezing and stretching. So you would feel it as a sort of squeezing and stretching and you would also find your location change. Where you're, where you would fall would be redirected. So it's literally like a squeezing and stretching. That's the way to think about it. And, and, and it's very detailed, the sort of nature of this. And, um, but for many years, people thought, well, these gravitational waves kind of have to exist for these intuitive reasons I've described. If spacetime's curved, I move the curve, the wave has to propagate through that curved spacetime. But people didn't know if they really carried energy.
2:26:35 Speaker 01 The arguments went on and back and forth and papers written and decades, right?
2:26:43 Speaker 01 But I like this sound more than an analogy because I liken the black holes as like mallets on the drum. The drum is spacetime. As they move, they bang on the drum of spacetime and it rings. Remarkably, those gravitational waves, things don't interfere with them very much. So they can travel for 2 billion years, light years, you know, in distance, 2 billion years in time, and get to us kind of as they were when they were emitted. Quieter, more diffuse. Maybe they've stretched out a little bit from the expansion of the universe, but they're pretty preserved. And so the idea of LIGO, this instrument, is to build a gigantic musical instrument. It's kind of like building an electric guitar,
2:27:28 Speaker 01 where the electric guitar is recording the shape of the string, and it plays it back to you through an amplifier. LIGO is trying to record the shape of the ringing drum. And they literally listen to it in the control room. Just sort of hums and wobbles. And they're like trying to play this recording drum back to you. As opposed to taking a snapshot, it's like in time.
2:27:51 Lex Fridman? Yeah, but to construct this guitar.
2:27:53 Speaker 01 Yes.
2:27:54 Lex Fridman? You have to.
2:27:54 Speaker 01 This gigantic instrument.
2:27:55 Lex Fridman? It has to be very large and extremely precise.
2:27:59 Speaker 01 It's unbelievable. I can't believe they succeeded. I honestly, I can't believe they succeeded. It was so insane. It was such a crazy thing to even attempt. It took them 50 years. Really, it's people who started in their 30s and 40s, who were in their 80s when it succeeded. I mean, imagine that tenacity, the unbelievable commitment. But the sensitivity that we're talking about is we have this musical instrument, the 4 kilometers, spanning 4 kilometers in a kind of L shape with these tunnels where there's this, the largest holes in the Earth's atmosphere, because they pulled a vacuum in these tunnels to build this instrument. And they're measuring, they're trying to record the wobbling of spacetime,
2:28:43 Speaker 01 right, as it passes, this sort of undulation, that amounts to less than 1 10,000th.
2:28:52 Speaker 01 The variation in a proton over the four kilometers. It's an insane, insane achievement.
2:29:00 Lex Fridman? I love great engineering.
2:29:02 Speaker 01 I don't know how they did it. I followed them around from so, just for fun. I'm very theoretical. I don't build things. I'm always super impressed that people can translate something on the page. And it looks like wires and I don't know how, I'm always surprised at what it looks like. And, but I walked the tunnels with Ray Weiss, who won the Nobel Prize along with Kip Thorne and Barry Barish, one of the project managers. And I walked the tunnels with Ray. It was a delight. I mean, Ray's one of the most delightful people. Kip is one of the most wonderful people I've ever known. And Ray said to me, you know, the reason why it was called Black Hole Blues is because about a month before they succeeded, he said to me, if we don't detect black holes,
2:29:47 Speaker 01 this whole thing's a failure. And we've led this country, you know, down this wrong path. And he really felt like this tremendous responsibility for this project to succeed. And it weighed on him, you know? It was, it was just quite tremendous what the integrity, right? The scientific integrity. And the first instruments he built, he was building outside of MIT and on a tabletop. And his colleagues said, you're not going to get tenure.
2:30:19 Speaker 01 You're never going to succeed.
2:30:22 Speaker 01 And they just kept going.
2:30:23 Lex Fridman? People like that, so huge teams, huge collaborations are just, is how the world moves forward because.
2:30:33 Speaker 01 It's an example.
2:30:34 Lex Fridman? It's, you know, there's a building cynicism about bureaucracies when a large number of people, especially connected to government, can be productive. You know, bureaucracy slows everything down. So it's nice to see an incredibly unlikely, exceptionally difficult engineering project like this succeed.
2:30:52 Speaker 01 Oh, yeah.
2:30:52 Lex Fridman? So I understand why there's this weight on the shoulders and I'm great. There's, I'm grateful that there's great leaders. Let's push it forward like that.
2:31:01 Speaker 01 Yeah, it really is. You see so many moments when they could have stumbled.
2:31:07 Lex Fridman? Yeah.
2:31:07 Speaker 01 And they built a first generation machine just after 2000. And it wasn't a surprise to them, but it detected nothing. Crickets. Crickets. And they just, you know, they have the wherewithal to keep going. Second generation, they're about to turn the machine on, quote unquote. It's a little bit of a simplification, but do their first science run. And they decide to postpone because they feel they're not ready yet. September 14th in 2015. And the experimentalists are out there, they're in the middle of the night. You know, they're working all night long and they're, they're banging on the thing. Literally driving trucks, slamming the brakes on to see the noise that it creates. And so they're really messing with the machine, really interfering with it just to kind of calibrate.
2:31:52 Speaker 01 How much noise can this thing tolerate? And I guess the story is, is they get tired. There's, there's an instrument in Louisiana and there's one in Washington State. And they go home, put their tools down, they go home. It's, they leave the instrument locked, though, mercifully. And it's something like within the span of an hour of them driving back to their humble abodes that they have in these remote regions where they built these instruments. This gravitational wave washes over, I think it hits Louisiana first. It travels across the US, brings the instrument in Washington State. It began, you know, over a billion and a half years ago, before multicellular organisms had emerged on the earth.
2:32:35 Speaker 01 Just imagine this from like a distant view, this collision course, right? And it's the centenary. It's, it's, it's the year Einstein published general relativity. So it was this, you know, the 100 years. And just think about where that, where that signal was when Einstein in, you know, 1915 wrote down the general theory of relativity. It was on its way here. It was almost here.
2:33:05 Lex Fridman? What do you think is cooler? Einstein's general relativity or LIGO?
2:33:13 Speaker 01 Well, I can't disparage my friends, but of course, relativity is just so all encompassing.
2:33:18 Lex Fridman? No, but so hold on a second. All encompassing, super powerful leap of a theory.
2:33:24 Speaker 01 Yeah.
2:33:25 Lex Fridman? And.
2:33:26 Speaker 01 They built it.
2:33:27 Lex Fridman? They built it.
2:33:28 Speaker 01 I don't know, man.
2:33:29 Lex Fridman? The greatest engineering in the, you know.
2:33:31 Speaker 01 Yeah.
2:33:32 Lex Fridman? Because I don't know, because, you know, yeah, humans getting together and building the thing, that's really ultimately what would impact the world, right?
2:33:43 Speaker 01 Yeah, I mean, I just, as I said, my admiration for Ray and Kip and the entire team is enormous. And just imagining Ray had been out there on site. He had just left to go back home, wakes up in the middle of the night and sees it. Can you imagine? And there's a signal, you know? There's something in the log. He's like, what the hell is that?
2:34:08 Lex Fridman? So, speaking of the human story, you also wrote the book Mad Men Dreams of Turing Machines. It connects two geniuses of the 20th century, Alan Turing and Gödel. What specific threads connect these two minds?
2:34:21 Speaker 01 Yeah, I was really mesmerized by these two characters. They, people know of Alan Turing for having ideated about the computer, being the person to really imagine that. But his work began with thinking about Gödel's work. That's where it began, and it began with this phenomenon of undecidable propositions or unprovable propositions. So there was something huge that happened in mathematics, which is people imagined that any problem in math could technically be proven to be true. Doesn't mean human beings are going to prove every fact about everything in mathematics,
2:35:05 Speaker 01 but you know, it should be provable, right? I mean, it seemed kind of, it's not that wild supposition. And everyone believed this, all the great mathematicians. Hilbert was a call of his to prove that. And Gödel, a very strange character.
2:35:21 Speaker 01 Very unusual. He was a Platonist. He literally believed that mathematical objects had a existential reality. He wasn't so sure about this reality, this reality he struggled with. He was distrustful of physical reality, but he absolutely took very seriously Platonic reality and often his own way of thinking, and he proved that there were facts, even among the numbers, that could never be proven to be true. To think about that, how wild that is, that even a fact about numbers, seems very simple, could be true and unprovable, could never exist as a theorem, for instance, in mathematics, unreachable.
2:36:07 Speaker 01 This incompleteness result was very disturbing. Essentially, it's equivalent to saying there's no theory of everything for mathematics. It was very disturbing to people, but it was very profound. And Alan Turing got involved in this because he was, you know, he was thinking about uncomputable numbers. So, and that led him, what's an uncomputable number? A number like 0.175, it just goes on forever with no pattern. And I can't, I can't even figure out how to generate it. There's no rule for making that number. And he was able to prove that there were such things as these uncomputable, effectively unknowable numbers. And that might not sound like a big deal, was actually, was actually really quite profound.
2:36:51 Speaker 01 He was relating to Gödel intellectually, right, in the space of ideas. But he goes a very different path, almost philosophically the opposite direction. He builds, he starts to think about machines. He starts to think about mechanizing thought, starts to think, what is a proof? How does a mathematician reason? What does it mean to reason at all? What does it mean to think? And he begins to imagine inventing a machine. That will execute certain orders, mechanized thought in a specific way. Well, maybe I can get a machine, I can imagine a machine that does this kind of thinking. And that he can prove that even a machine could not compute these uncomputable numbers.
2:37:34 Speaker 01 But where he ends up is the idea of a universal machine that computes, essentially can take different software and execute different jobs, right? We don't have a different computer to connect to the internet than we do to write papers. It's one machine and one piece of hardware, but it can do all of these, this huge variety of tasks. And so he really does invent the computer, essentially.
2:38:03 Speaker 01 And famously, he uses that thinking in a very primitive form in the war effort where he's recruited to help break the German Enigma code, which is heavily encrypted and largely believed to be uncrackable code. And, and, and people believe that Turing and his very small group actually turned the tide of the war in favor of the Allies precisely by using a combination of this thinking and just sheer ingenuity and some luck.
2:38:34 Speaker 01 But, but the other profound revelation that Turing has is that, well, maybe we're just machines, right? And just biological machines. And this is a huge shift for him. It feels very different from Gödel, who doesn't really believe in reality and thinks numbers are platonic realities. And Turing kind of thinking we're kind of like, we're actually machines and we could be replicated. So of course Turing's influence is still widely felt.
2:39:05 Lex Fridman? On many levels, so to the
2:39:07 Speaker 01 On many levels, yeah.
2:39:08 Lex Fridman? In complexity theories, in theoretical computer science and mathematics, but also in philosophy with his famous Turing test paper. So like you said, conceiving, like what is the connection that I guess Gödel never really made between mathematics and humanity? Turing did. But I think there's another connection to those two peoples, that they're both in their own way, kind of tormented
2:39:31 Speaker 01 Yeah.
2:39:31 Lex Fridman? Humans.
2:39:32 Speaker 01 And they were very tormented.
2:39:34 Lex Fridman? What aspects? Of that contributed to who they are and what ideas they developed.
2:39:41 Speaker 01 I mean, I think so much. I don't, I don't want to promote the kind of trite trope of the mad genius. You know, if you're brilliant, you are insane. I don't think that. I don't think if you're insane, you're brilliant. But I do think if somebody who's very brilliant, who also chooses not to go for regular gratification in life. They don't go for money. They don't necessarily value creature comforts. They're, they're not leveraging for fame. I mean, they're really after something different. I think that can lead to a kind of runaway instability, actually.
2:40:26 Speaker 01 Sometimes. So they're already outside of kind of social norms. They're already outside of normal connections with people. They've already made that break. And I think that makes them more vulnerable. So Gödel did have a wife and a strong relationship, as far as I understand, and had a, was a successful mathematician and ended up at the Institute for Advanced Study, where he walked with Einstein to the institute every day.
2:40:56 Speaker 01 And they talked about, and he proved certain really unusual things in relativity. He made reference to these rotating galaxies. We were talking and actually Gödel had a model of a rotating universe that you could travel backwards in time. It was mathematically correct. Showed Einstein that within relativity, you could time travel.
2:41:16 Speaker 01 Just an unbelievably influential and brilliant man, but he was probably a paranoid schizophrenic. He did have breaks with reality.
2:41:28 Speaker 01 He was, I think, quite distrustful and feared the government, feared his food was being poisoned and ultimately literally starved himself to death.
2:41:42 Speaker 01 And it's such an extreme outcome for such a facile mind, you know, for such a brilliant mind.
2:41:52 Lex Fridman? I think it's important to sort of not to glorify or romanticize madness or suffering. But to me, you flip that around and just be inspired by. The peculiar maladies of a, of a human mind, how they can be leveraged and channeled creatively.
2:42:10 Speaker 01 Oh, yeah.
2:42:11 Lex Fridman? I think a lot of us, obviously, probably every human has those peculiar qualities. You know, I talk to people sometimes about just my own psychology and I'm extremely self critical.
2:42:25 Lex Fridman? And I'm drawn to the beauty in people. But because I make myself vulnerable to the world, I can really be hurt by people. And that thing, okay, you can lay that out, this, this particular human, okay. And, you know, there's a bunch of people that would say, well, you, many of those things you don't want to do. Maybe don't be so self critical. Maybe don't be so open to the world. Maybe have a little bit more reason about how you interact with the outside world. It's like, yeah, maybe. Or maybe be that and be that fully and channel that into a productive life into, we're all gonna die.
2:43:07 Lex Fridman? In the time we have on this earth. Make the best of the particular weirdness that you have. And maybe you'll create something special in this world. And in the end, it might destroy you. And I think a lot of these stories are that. It's not that.
2:43:23 Speaker 01 Oh, yeah.
2:43:25 Lex Fridman? It's not like saying, oh, because in order to achieve anything great, you have to suffer. No, if you're already suffering. If you're already weird, if you're already somehow don't quite fit in your particular environment, in your particular part of society. Use that somehow, use the tension of that, the friction of that to create something. I mean, that's what I, you know, Nietzsche who suffered a lot. From even like stupid stuff like stomach issues, like.
2:43:55 Speaker 01 Oh, yeah.
2:43:56 Lex Fridman? That can be everything.
2:43:57 Speaker 01 Right.
2:43:57 Lex Fridman? Migraines is like.
2:43:59 Speaker 01 Psychosomatic or psychophysical, but.
2:44:02 Lex Fridman? And all those, that's the real, if they. That can somehow be channeled into a productive life. It should be inspiring. A lot of us suffer in different ways.
2:44:13 Speaker 01 Yeah, I'm a big believer in the tragic flaw, actually. I think the Greeks really had that right. You're describing it. What makes us great is ultimately our downfall. Maybe that's just inevitable. The choice could be not to be great.
2:44:30 Speaker 01 And I guess that's sort of what I mean by they had already broken from a traditional path because they decided to pursue something so elusive and that would isolate them to some extent inevitably and that could fail, right? And whose rewards were hard to predict even. And I do think that that, all the character traits that went into their accomplishments were the same traits that went into their demise. And I think you're right. You could say, well, you know, Lex, maybe you should not be so empathetic. Hold yourself, cut yourself off a little bit, protect yourself, right?
2:45:15 Speaker 01 But isn't that exactly what you're bringing? One of the elements that you're bringing that makes something extraordinary in a space that lots of people try to break through?
2:45:25 Lex Fridman? Yeah, but we should mention that for every girl on Turing, there's millions of people who have tried and who have destroyed themselves and without reason.
2:45:36 Speaker 01 I would find it impossible to not pursue a discovery that I could, I could imagine my way through if I can really see how to get there. I cannot imagine abandoning it for some other reason.
2:45:56 Speaker 01 Fear that it would be misused, which is a real fear, right? I mean, it's a real concern. I don't think in my work, since I'm doing extra vengeance in the early universe, or black holes, you know, I feel pretty safe. But, I mean, who knows, right? Bohr couldn't think of a way to use quantum mechanics to kill people.
2:46:18 Speaker 01 I cannot imagine pulling back and saying, nope, I'm not going to finish this.
2:46:22 Lex Fridman? You know, I'll give you a counter example of an exceptionally brilliant person. Terence Tao.
2:46:27 Speaker 01 Brilliant.
2:46:27 Lex Fridman? Brilliant mathematician.
2:46:28 Speaker 01 Brilliant.
2:46:29 Lex Fridman? He is better than, out of all the brilliant people I've ever met in the world. He's better than anybody else at working on a hard problem. And then realizing when it's, for now, a little too hard.
2:46:43 Speaker 01 Oh, that I can do.
2:46:44 Lex Fridman? It's stepping, stepping away.
2:46:47 Speaker 01 Yeah.
2:46:47 Lex Fridman? And he's like, okay, this is now a weekend problem.
2:46:50 Speaker 01 Uh huh.
2:46:51 Lex Fridman? Cause he has, he has seen too much for him. Everybody's different, but Gregory Perlman. Or Andrew Wiles, who, who give.
2:46:59 Speaker 01 Yes, that's a great story.
2:47:01 Lex Fridman? Completely for many years.
2:47:03 Speaker 01 Yes.
2:47:03 Lex Fridman? Or a problem.
2:47:04 Speaker 01 Yes.
2:47:04 Lex Fridman? And for every, every.
2:47:06 Speaker 01 And they might not have cracked it.
2:47:07 Lex Fridman? Yep. So you choose your life story.
2:47:11 Speaker 01 I totally agree. Now, I'm not going to say, sometimes I take too long.
2:47:15 Lex Fridman? Yeah.
2:47:15 Speaker 01 To come to that conclusion, but I will proudly say, as most theoretical physicists should, that I kill most my ideas myself.
2:47:23 Lex Fridman? Okay.
2:47:23 Speaker 01 And that's. I am absolutely able to say, ah, that's just not, I mean, I'm not gonna deny that sometimes I maybe take a while to come to that conclusion, longer than I should, but I will, I absolutely will, I will drop it. And that is, that is, any self-respecting physicist should be able to do that. The problem is with somebody like Andrew Wiles, you were describing, who, to prove Fermat's Last Theorem, it took him seven years. Was that the number? Something like that? He went up into his mother's attic or something and did not emerge for seven years. Is that maybe he did, he was on the right track, he wasn't wrong. And, and, but that's how, it could have been interminable. He still might not have gotten there in the
2:48:05 Speaker 01 end. And, and so that's the, the really difficult space to be in, where you're not wrong, you are on to something, but it's just asymptotically approaching that solution and you're never actually going to land it. That happens.
2:48:22 Lex Fridman? And he had a really, I, it would break me, straight up break me. He had, he had a proof.
2:48:27 Speaker 01 Yes.
2:48:28 Lex Fridman? He announced it and they, somebody found a mistake in it. That would just break me.
2:48:33 Speaker 01 Yeah.
2:48:33 Lex Fridman? Because you now, everybody gets excited.
2:48:36 Speaker 01 Right.
2:48:37 Lex Fridman? And now you, you, you realize that it's a failure and to go back.
2:48:40 Speaker 01 It was taking a year for people to check it. It's not the kind thing you look over in an afternoon.
2:48:45 Lex Fridman? And then to have the will, to have the confidence and the patience to go back.
2:48:49 Speaker 01 Unbelievable story.
2:48:50 Lex Fridman? Rigorously go through, work through.
2:48:51 Speaker 01 It's a great story.
2:48:52 Lex Fridman? But then there's another great story, Gauri Perman, who spent seven years and turned down the Fields Medal. He did it all alone. Now, after he turned down the Fields Medal and the Millennial Prize, proving the Poincaré conjecture, he just walked away.
2:49:07 Speaker 01 Yeah. Now, that's a very different psychology. That's wired differently.
2:49:11 Lex Fridman? Doesn't care about money, doesn't care about fame, doesn't care about anything else.
2:49:15 Speaker 01 Yep.
2:49:15 Lex Fridman? In fact.
2:49:16 Speaker 01 Where is he now?
2:49:17 Lex Fridman? Uh, in St. Petersburg, Russia, trying to, trying to get a conversation with him. It turns out, when you walk away and you're a recluse and you enjoy that, you also don't want to talk to some weird dude in a tie. So it turns out, I'm trying, I'm trying.
2:49:34 Speaker 01 Well, if you look at someone like Turing, his, his eccentricities were completely different, right? It's not as though there's some mold and I, I really don't like it when it's portrayed that way. These are really individuals who, um, who were still lost in their own minds, but in very different ways. And Turing was openly gay, really, um, during this time, you know, he was working during the war, World War II, so we understand the era, and it was illegal, um, in Britain, uh, at the time. And he kind of refused to conceal himself.
2:50:19 Speaker 01 There was a time when the kind of attitude was, well, we're just gonna ignore it. But he had been robbed by somebody that he had picked up somewhere, I think it was in Manchester. And it was such a small thing. I don't know what they took. It took like nothing, you know, it was nothing. But he, he couldn't tolerate, he goes to the police and he tells them. And then he's arrested. He's the criminal because it involved this homosexual act. Now, here you have somebody who made a major contribution to the Allies winning the war. I mean, it's just unbelievable, not to mention the genius, mathematical genius.
2:51:03 Speaker 01 I mean, he saved the lives of the people that were doing this to him. And they essentially chemically castrated him as a punishment. That was his sentence. And he became very depressed and suicidal. And the story is, he was obsessed with Snow White, which was recently released. And he used to chant one of the little, I don't know if you would call them poems, songs, dip the apple in the brew, let the sleeping death soup through. It was a chant from Snow White. And the belief is, is that he dipped an apple in cyanide and bit from the poisoned apple. Now, I don't know if this is apocryphal,
2:51:48 Speaker 01 but people think that the apple on the Macintosh with the bite out of it is a reference to Turing. Now, some people deny this.
2:51:54 Lex Fridman? That's nice.
2:51:56 Speaker 01 But some people say he did that so his mother could believe that maybe it was an accident. But yeah, quite a terrible end.
2:52:06 Lex Fridman? Yeah, but two of the greatest humans ever.
2:52:10 Speaker 01 I think the reason why I tie them together, not just because ultimately their work is so connected, but because there is this sort of impossibility of understanding them, there's this sort of impossibility of proving something about their lives, that even if you try to write factual biography, there's something that eludes you. And I felt like that's kind of fundamental to the mathematics, the incompleteness, the undecidable, the uncomputable.
2:52:40 Lex Fridman? Yeah.
2:52:41 Speaker 01 So structurally, it was about what we can kind of know and what we can believe to be true, but can't ever really know.
2:52:49 Lex Fridman? Yeah, limitations of formal systems, limitations of...
2:52:52 Speaker 01 Exactly. Biography, limitations of fiction and nonfiction.
2:52:57 Lex Fridman? Limitations. So there's so many layers to you. So one of which, there's this romantic notion of just understanding humans, exploring humans. And there's the exploring science, there's the exploring the very rigorous, detailed physics and cosmology of things. So there's the kind of artistry. So I saw that you're the chief science officer of Pioneer Works, which is mostly like an artist type of situation. It's a place in Brooklyn. Can you explain to me? What that is and what role does art play in your life?
2:53:30 Speaker 01 Yeah, I can start with Pioneer Works. Pioneer Works, in some sense, it was inevitable that I would land at Pioneer Works. It felt like I was marching there for many years and just it came together again, like this collision. It was founded by this artist Dustin Yellen, very utopian idea. He bought this building, this old iron works factory called Pioneer Iron Works in Brooklyn. It was in complete disrepair, but a beautiful old building from the late 1800s. And he wanted to make this kind of collage. Dustin's definitely a collage artist, works in glass, very big pieces, very imaginative and wild and narrative and into nature and consciousness. And I think he wanted to do that with people.
2:54:16 Speaker 01 He wanted a place of a collage, a living example of artists and scientists. And it was founded by Dustin and Gabriel Florentz was the founding artistic director. It was started just before Hurricane Sandy. I don't know if people feel as strongly about Hurricane Sandy as New Yorkers do, but it was a real moment around 2012, 2013. Sort of paused the project and you can even see the kind of water line on the brick of where Sandy was. I came in and collided with these two shortly after that. And it really was like a collision. I'm science, you know, their art, Gabe makes everything, builds everything with his bare hands. Dustin's a dreamer. They love science.
2:55:00 Speaker 01 They really wanted science, but science is hard to access.
2:55:04 Speaker 01 I have always loved the translation of science in literature, in art. I love fiction writers, like really literary fiction writers who dabble thinking about science. And I very firmly believe science is part of culture. I just, I know it to be true. I don't think of myself as doing outreach or education. I don't like those labels. I'm, I'm doing culture.
2:55:31 Speaker 01 An artist in their studio, working out problems, understanding materials, building a body of work. Nobody says to them when they exhibit, why are you doing outreach? Or are you doing education? You know, it's the logical extension. So I feel that if you've had the privilege of knowing some of these people, of seeing a little bit from the summit, if you've had a little glimpse yourself, that you bring it back to the world. So we boom, exploded. Pioneers became science and art. It's not artists who all do science or scientists who do art. It's real hardcore scientists talking about science on a lot of live events.
2:56:15 Speaker 01 We have a magazine called Broadcast where we feature all of the disciplines, rubbing together artists, working on all kinds of things. When I first started doing events there, my first guest, like you, I was talking to people. And this was like, I know how to talk to people because I know these guys. And I've been on the interviewee side so much. I know exactly, it was like fully formed for me, how to do those conversations.
2:56:38 Lex Fridman? Yeah, you're extremely good at that also.
2:56:40 Speaker 01 Yeah, thank you. I appreciate that. You learn how to do it too, though. I mean, I don't think the first one I did, I think I've learned, right? And you acquire, you get better, which is really interesting. And I love to study. I think you do too. I really look into the material. And I love science. I really do. I want to talk to a CRISPR biologist because I don't understand it and I want to understand it.
2:57:03 Lex Fridman? And I saw there's a bunch of cool events and a very fascinating variety of humans.
2:57:09 Speaker 01 Yes, we have a really fascinating variety of humans. That's a good way of putting it.
2:57:14 Lex Fridman? Yeah, so you put in my mental map of like, it's a cool place to go and visit in New York.
2:57:20 Speaker 01 Yes, you have to come see us. I think you would love it.
2:57:24 Lex Fridman? Also, I should mention fashion. I've seen you do a bunch of talks and there's a lot of fashion. Appreciation of fashion going on.
2:57:31 Speaker 01 I am so, you're giving me an opportunity to give a shout out to Andrea Lauer, who's a designer who makes these amazing jumpsuits that I often wear. And a lot of my events, she has a jumpsuit design line called Risen Division, and she just makes these incredible, they're fantastic. We also design patches for all of our events. So there are these string theory patches and consciousness patches.
2:57:57 Lex Fridman? We should show this as overlays.
2:57:58 Speaker 01 Right.
2:57:59 Lex Fridman? Hopefully, there'll be nice pictures floating about everywhere.
2:58:02 Speaker 01 So, you know, I think all of this is just, I just like to experiment with life. I think Making the Magazine was a big, wild experiment.
2:58:09 Lex Fridman? You said with life?
2:58:10 Speaker 01 With life.
2:58:11 Lex Fridman? Nice.
2:58:11 Speaker 01 Yeah. This kind of idea that we were just describing is I find it hard to stop the momentum if I think something can, I can make something. I have to try to make it. And to me, this is the closest I come to experimentation and collaboration, because even though I collaborate theoretically, I have great collaborators, Brian Greene, Massimo Pirati, Dan Cabot, these are my really close collaborators. A lot of theoretical physics is alone, and you're in your mind a lot. This is something that really was built, this triad of Dustin Gabe and I and all the amazing people who work there and our amazing board, we really are doing it together. You
2:58:56 Speaker 01 take one element out and it starts to, it starts to change shape. And that's a very interesting experience, I think. And making things is an interesting experience.
2:59:07 Lex Fridman? Since you mentioned literature, is there, is there books that had an impact in your life, whether it's literature, fiction, nonfiction?
2:59:15 Speaker 01 I love fiction, which I think people expect me to read a lot of sort of sci fi or nonfiction. I mostly read fiction. I had a syllabus of great fiction writers that had science in it. And I love that syllabus.
2:59:31 Lex Fridman? Can you ever make that public or no?
2:59:33 Speaker 01 Yeah, I suppose I could. But I can tell you some of them as they come to mind. Katsuo Ishiguru, who won the Nobel Prize, wrote Remains of the Day, probably most famously. His book, Never Let Me Go. It's unbelievable, totally devastating, stunning. I say I really love literature. So when when people can do that with these very abstract themes, it's sort of my favorite space for for literature. Martin Amis wrote a book that runs backwards, Times Era. I love some of his other books even more, but Times Era was pretty clever.
3:00:07 Lex Fridman? Do you like it when these non-traditional mechanisms are applied to tell a story that's fundamentally human? That there's some
3:00:16 Speaker 01 Yes.
3:00:16 Lex Fridman? Some dramatic tragic.
3:00:18 Speaker 01 And the beauty of the language, like, I really appreciate that. Even Orwell is amazing. You know, Hitchens writing on Orwell is amazing. There was, there were some plays on the syllabus. I have to think of what else was in there. But there was one book that I think was kind of surprising that I think is an absolute masterpiece, which is The Road. And you might say, in what sense is The Road a science? Well, first of all, Cormac McCarthy absolutely loves scientists and science. And you can feel this very subtle influence in that book is it's, it's a really remarkable, precise, stunning, ethereal, all of these things at once.
3:01:00 Speaker 01 And there's no who, what, where, when, or how. You might guess it's a nuclear event that kicks off the book. Or a lot of people know The Road, I think, from the movie, but really, the book is magnificent. And it's very, very abstract, but there's a sense to me in which it is, science is structuring.
3:01:19 Lex Fridman? And still fundamentally, that book is about human story.
3:01:22 Speaker 01 Yeah, absolutely. The boy.
3:01:24 Lex Fridman? Yeah. So the science plays a role in creating the world. And within it, there's still, really, it's a, it's a, it's a different way to explore human dynamics in a way that's maybe lands some clarity and depth that may be a more direct telling of the story will not. Yeah. And even surreal worlds that, I mean, to me, I don't know why, but I return to Orwell's Animal Farm a lot, and there's these kind of like
3:01:55 Lex Fridman? It's another art form to be able to tell a simple story with some surreal elements.
3:02:00 Speaker 01 Mm hmm.
3:02:01 Lex Fridman? Well, just simple language.
3:02:03 Speaker 01 Mm hmm. Oh, art form's incredible. In fact, some of the, I've kind of played with, you know, some animals are more equal than others. There are, in Gödel, Turing's work, there were some infinities that are bigger than others.
3:02:18 Lex Fridman? Yeah, there's certain books just kind of inject themselves into our culture in a way that just reverberates and, I don't know, has it creates culture, not just like influences, it's just like, it's quite incredible how writing and literature can do that.
3:02:36 Speaker 01 Yeah.
3:02:38 Lex Fridman? If you could have one definitive answer to one single question, this is the thing I mentioned to you.
3:02:42 Speaker 01 This is so hard.
3:02:42 Lex Fridman? Yeah. Well, there's a, there's an oracle and you get to talk to that oracle. You can ask multiple questions, but it has to be on that topic. So just clarify, what mystery of the universe would you want that oracle to help you with?
3:02:58 Speaker 01 You know, it's funny, I should say the obvious thing. And, but I feel like, I almost feel like it would be greedy. I think of a complicated response to this. The obvious thing for me to say would be, I want to understand quantum gravity, or if gravity's emergent. It's not even something I work on, day to day. You know, I mostly just look with interest at what others are doing. And if I think I can jump in, I would, but I'm not jumping into the fray. But obviously, that's the big, that's the big one. And, and there is a sort of sense that with that will come the answers to all these other things. My complicated relationship is that, well, you know, part of the scientific disposition isn't having stuff you don't know the answer to. I mean, we're not going to have all the answers, I
3:03:42 Speaker 01 hope, because then, sort of, then what? Right? It's sort of dystopian.
3:03:47 Lex Fridman? I totally agree with you. There's some, I like the mysteries we have.
3:03:51 Speaker 01 Yeah.
3:03:53 Lex Fridman? I kind of had this assumption that there will always be mysteries. So you want to keep solving them?
3:03:57 Speaker 01 They will lead to more. In the same way that relativity led to black holes, black holes led to the information loss paradox, or the big bang, or what happened before, or the multiverse. It's because we learned so much, we were able to escalate to the next level of abstraction.
3:04:13 Lex Fridman? Yeah, by the way, we should mention that if you're talking to this oracle, and even if you ask the obvious question about quantum gravity, I almost guarantee with 100% probability that even if all your questions are answered, it's impossible to get to the end of your questions.
3:04:30 Speaker 01 Right.
3:04:31 Lex Fridman? It says, you know, the oracle will say, no, you can't unify.
3:04:36 Speaker 01 Then you say, well, wait.
3:04:37 Lex Fridman? Yeah, and then you say emergent. And then the oracle will say, well, everything you think is fundamental is not, it's emergent. It's like, OK, well, this is, we need to, there's more questions.
3:04:50 Speaker 01 I mean, it's been 100 years more since relativity, and we're still picking it apart.
3:04:55 Lex Fridman? Yeah.
3:04:57 Lex Fridman? And there will be, there may be new ones. You write that eventually all our history in this universe will be erased. How does that make you feel?
3:05:08 Speaker 01 Yeah, it's a tough thought, but again, I think there's a way in which we can come to terms with that, that that's kind of poetic. You know, you build something in the sand and then you erase it.
3:05:23 Lex Fridman? Yeah.
3:05:24 Speaker 01 So I think it's just a reminder that we have to be concerned about our immediate experience too, right? How we are to those around us, how they are to us, what we leave behind in the near term, what we leave behind in the long term. Have we contributed and did we, you know, did we contribute overall net positive?
3:05:52 Speaker 01 Eventually, I think it's kind of hard to imagine, but yes, all of these Nobel prizes, all of these mathematical proofs, all of these conversations, all of these ideas, all the influence we have on each other, even the AI eventually will expire.
3:06:10 Lex Fridman? Well, at the very least, we can focus on drawing something beautiful in the sand.
3:06:16 Speaker 01 Yeah.
3:06:16 Lex Fridman? Before it's washed away.
3:06:19 Lex Fridman? Well, this was an incredible conversation. I'm truly grateful for the work you do.
3:06:22 Speaker 01 And me for your work. Thanks so much for having me.
3:06:25 Lex Fridman? Thank you for talking to me.
3:06:26 Speaker 01 Yeah, lots of fun.
3:06:28 Lex Fridman? Thanks for listening to this conversation with Jana Levin. To support this podcast, please check out our sponsors in the description. And now, let me leave you with some words from Albert Einstein on the topic of relativity. When you're courting a nice girl, an hour seems like a second. When you sit on a red hot cinder, a second seems like an hour. That's relativity. Thank you for listening and hope to see you next time.
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