#468 – Janna Levin: Black Holes, Wormholes, Aliens, Paradoxes & Extra Dimensions

The following is a conversation with Jana Levin, a theoretical physicist and cosmologist specializing in black holes, cosmology-vexed dimensions, topology of the universe, and gravitational waves in space-time. 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, and madman 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. This was a fun and fascinating conversation. Now a quick few second mention of your 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, and that's sweet for your business, Shopify for selling stuff, and the AG1 for your health. She's wise in my friends. I do these longer adries up in the beginning. I try to make them interesting, but I do also make it super easy to skip with time stamps on 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 lectsreadme.com/contact, and now onto the full ad reads. Let's go. This episode is brought to you by brain.fm, a platform that offers music, especially made for focus. And when I say music, I mean audio experience. If you ever see me out in the wild like a 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. Speaking of audio, did you know that the Roman Empire used synchronized wardrums to coordinate legions? Just imagine the sound of those drums. I need to do a lot more episodes, an ancient Rome, an ancient Greece, an ancient China. Anyway, now listening to wardrums. I'm listening to brain.fm, but 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. It's raining outside, thunderstorms, like somebody's knocking on the window. If that's not a metaphor for prodding 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 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. 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The more study war, of course, the more study business too, but war, the more I realize the importance of the organizational layer, of the supply chain, of the logistics, a stuff that nobody talks about, the stuff that most historians don't talk about, 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's 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 the business is not just the CEO of the 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. I have great tools to do so, download the CFO's guide to AI and machine learning at NetSuite.com/lux, that's NetSuite.com/lux. This episode was 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, JenkinsCon, very, very, very important. Of course, JenkinsCon was well known for protecting the merchants, and I think any empires, any civilizations, any state of the global affairs that protects 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 a nice one in the 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/lux. That's all lowercase, go to Shopify.com/lux to take your business to the next level today. This episode was also brought to you by AG1, and all in one daily drink to support better health and peak performance. Because I mentioned peak performance, I'm reminded of Nietzsche, and the book I read maybe freshman, maybe sophomore year in college, thus spoke Zora Thustra. It's been forever. I've been reading summaries of Nietzsche 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. It's 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, "What have you been there?" That never gets old. 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 call him Jung 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 up because in the thus Spokes are a thuescher, there's the pursuit of peak human potential. And we in the West, on the health front, have a time taking that to an almost ridiculous place. 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 to 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 drink AG1.com/lex. This is Alex Woodman podcast, to support it, please check out our sponsors in the description, and now I'll do friends. Here's Jenna. 11. 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 a.m. meeting, his reply was, I can't stay up that late. Sidney was beloved. I think all the best thoughts, honestly. Maybe the worst thoughts, too, are all coming at night. 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 can be with yourself and you can think deeply. I feel like they're 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 before in the morning. Okay, so in that way, many other ways were Kendra 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? 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 the nature thinks of a way. Nature thinks 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. 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 One. And he gets a message from the Eastern front, from a friend of his, Karl Schwarzschild, 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. 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. 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 curve space time tells matter and energy how to fall when it's a space time shape. So he finds this beautiful solution. And the most amazing thing about a 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 asked me today, all these decades over a hundred years later, I would say that is the black hole. 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 space time or a region at space time. It's actually in this case a surface in space time. And it marks a separation in events, which is why it's called an event horizon. Everything outside is causally separated from the inside in so far 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. 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. 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 space time. 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 Karl Schwarzschild did either. I think they thought they were solving theoretical mathematical problems, but not describing what turned out to be the end state of gravitational collapse. 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. Yeah. And it just so happens in this case that might actually predict these extreme kinds of objects. 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 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's something's gone wrong here, right? 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. So according to him, the closer you get to the singularity, the more quantum mechanics comes into play, and therefore there's no singularity, there's something else. 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's just inconsistent with the world as we understand it. 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, no space time, but even more so, just nothing. Yeah. That's nothing. That's the thing you seem to like to say. I do. I do like to say that black holes are nothing. There's nothing. Okay, so what, what does that mean? And 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 even when you try to form them in messy astrophysical systems, they're 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 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 sun radiant and hot and this amazing source of light? And it was people like Oppenheimer who began to ask a 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 black holes are these dense objects. That's often how it's described. But actually what happens, he's very massive stars. They're burning thermonuclear fuel. You know, they're earthfuls of thermonuclear fuel. They're burning. And emitting energy in 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, 30 times the mass per 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. 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, you know, heavier than twice the mass of the sun, it will become a black hole. And Oppenheimer was brought to 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 than Nazis advance on Poland. And so it does not get a lot of fanfare in the newspapers. 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 object that broke even Einstein's brain while one of the most evil, if not the most evil humans in history, starting the first steps of a global war. 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 and stars. You might know this play Copenhagen by Michael Frey, and there's this line that he attributes to Bohr. 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. 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 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, I'm pulling. That's the other remarkable thing about Oppenheimer is he's also a central figure in the construction of the bomb. Right. So it's theory and experiment clashing together with the geopolitics. 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 Lee's mightner, 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 equals MC squared energy, had escaped. And it was the first kind of concrete demonstration of this Einstein's most famous equation. So all of this comes together, but the story of, there 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, it's still maybe ten 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, ten times the mass 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 space time is so tremendous that not even light can escape. The event horizon forms, but the event horizon is almost imprinted on the space time, 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. 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. There was a place there, 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. 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. Two pages, it's like three pages. Oh yeah, it's gorgeous. The simplicity of some of these, this is so gangster, just revolutionized all of physics with the, you know, Einstein did that multiple times in a century year, when all thermonuclear sources of energy are exhausted, it's officially 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 reduced the star's mass to orders of that of the sun, this contraction will continue indefinitely, and it goes all that way. 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 there 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 computer is when he was also trying to understand nuclear weapons. And in peacetime, we found themselves returning again to these astrophysical questions, decided that actually Oppenheimer had been right. He thought it was too simplistic to idealize to set up that they had used and that if you, 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 and 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. Because you've written in many places about the human beings behind the science, I have to ask you about this, about nuclear weapons, whereas 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 homeless technology is part of the tools that is used perhaps implicitly on the chess board of geopolitics. What can you say as a person who's a physicist and who have studied the physicist 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? I think it's an excruciating moment in the history of science. 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 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. 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, and how different with the world. be the game theory of that. I think say it's 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. In the game theory version, this was the least harmful outcome. Yes. Yes. But there is no outcome with no bomb that any game theorist would, I think, would play. But I think if we just remove the geopolitics and the ideology and the evil dictators, all of those people are just scientists. I think they don't necessarily even think about the ideology. And it's a deep lesson about the connection between great science and the annoying, sometimes evil politicians that use that science for means they're either good or bad. And the scientists perhaps don't, boy, do they even have control of how that science has used its heart? They don't have control. Right. Once it's made, it's no longer scientific reasoning that dictates the use or it's restraint. But I will say that I do believe that it wasn't a 30 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 they were motivated by it's more than a patriotism. I mean, it was a patriotism, obviously, but it was sort of more than that. It was really understanding the threat of Europe, what was going on in Europe. And what that life's, 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. Yeah, there's something about the American system. The, you know, it's a cliche to say, but the freedom, all the different individual freedoms, that enable a very vibrant, at its best, the very vibrant scientific community. That's really exciting. Absolutely. The scientists and it's very valuable to maintain that. The vibrancy of the debate of the funding those mechanisms. Absolutely. The world flocked here. And that won't be the case if we no longer have intellectual freedom. Yeah, 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. I believe most Nobel prizes come from the United States, right? Oh, yeah, I don't have the number, but it's disproportionately so. It's disproportionately so in fact, a lot of them from particle physics came from the Bronx. And they were European immigrants. How did they explain this? Blood Europe, precisely because of the geopolitics we're describing. Yeah. And so instead of being Nobel Prize winners from Soviet Union or from the Eastern block, they were from the Bronx. And this is the thing you write about when we return to time and time again, 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 easy going, all this kind of stuff. And that's the beautiful thing about it. We forget sometimes is this humans and humans are messy and complicated and beautiful and all of that. Yeah. So what were we talking about? Oh, the stars collapse. So can we just return to the collapse of a star that forms a black hole? Which point does the super dense thing become nothing if we can just like linger on this concept? 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 space time 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, you know, swimming against the waterfall. 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 to speed of light, but it's sitting right there at the event horizon. So you're falling back across the event horizon right at that point. You shoot outwards a photon. Yes. And it's just stuck there. It just gets stuck there. Now it's very unstable. So the star can't sit there as the point. 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 and the energy of light won't matter to me because I can't know anything about what happened on the inside. 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 worth be careful about making is 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 space time inside the black hole? I don't mind being in cautious about thinking about what the math tells us. I'm not such an observer. I'm very theoretical in my work. It's really pen on paper a lot. These are thought experiments that I think 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 at 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. That's very, very close orbiting quite safely. No big deal. You know, hang it out. I don't bug the black hole. The black hole doesn't bug me. It won't suck me up like a vacuum or anything crazy. But some of 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 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. But from the perspective of the astronaut who falls in, it's actually a point in time. So, there are 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 an orbit around it. 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. Microseconds to get from the event horizon to the singularity. To the singularity. Oh, boy. So, that's describing from the your astronaut friend's perspective. Yes, from their perspective, the singularities in their future. But from your perspective, what do you see when your friend falls into the black hole and you're chilling outside and watching? So, one way to think about this is to think that as you're approaching the black hole, the astronaut's space time is rotating relative to your space time. 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. If I just want to draw a kind of compass diagram, not a compass diagram, but 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 space-time, there's one way of thinking about it. 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 face of their watch 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. They were both synchronized beautifully in their 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. Age faster, I've got gray hair, and they're falling in, and it's been minutes in their frame of reference. Flowers and 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, 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. So basically time almost comes to a standstill, but we still, they do fall in. Right, they do fall in eventually. Now that's because they have some mass of their own. So they're not a perfectly light particle. And so they deform the event horizon a little bit. You will actually see the horizon bubble and absorb the astronaut. So in some finite time, the astronaut will actually fall in. So it's like this weird space time bubble that we have around us. And then there's a very big space time curvature bubble thing from the black hole. And there's a nice swirly type situation going on. That's how you get sucked up. So if you're a perfect like infinitely small particle, you would just be. It takes longer and longer. And probably just be stuck there. But no, there's quantum mechanics. Eventually you'll fall in. There any perturbation will only go one way. It's unstable in one direction and one direction only. But 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 or you might not even realize you've come to the event horizon. You might not even realize you've crossed the event horizon because there's nothing there. This is an empty region of space time. 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. 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. You know, there's different size 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? Because as I understand, if the bigger it is, the less drastic the experience of falling into it. Yeah, that might surprise people. The bigger it is, the less noticeable it is that 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. 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 kind of feels like just flat. You don't really notice. I'll try to figure out how the physics, because if you don't notice. And there's nothing there. But the physics is weird. In your frame of reference. What's do another cool thing? So I'd like to dispel this. Yeah. Do you need a minute? You're holding your head. 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. 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. You know, 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. You could see the evolution of the entire galaxy in a one big bright flash of light. So it's like a near death experience, but it's definitely a total death experience. It goes pretty fast, but you looking out, you looking out, everything's going super fast. Yeah. The clocks 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. Obviously, the human sensor system are not able to process that information correctly. Right. It would be a microsecond in a, right, that would be too fast. Yeah, but it would be, while it would be so cool to get that information. But a big black hole, you could actually, you know, hang around for some months. So yeah, what's, how are small black holes? There's a super massive black holes formed. It's just so people can kind of load that in. Are they, are they all, is it always a star? 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, in a death state that is a black hole. But we now see, and this was really quite a surprise, that there are super massive black holes. There are billions or even hundreds of billions of times the mass of the sun. 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 hundred, a hundred, a 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. So like, in the very early universe, these are primordial black holes from the stars, not quite. Wait, how do you get from that soup, black holes right away? 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. I wonder if the chicken or the egg, is it how critical, how essential are the supermassive black holes of the formation of galaxies? Yeah, I mean, it's ongoing, right? It's ongoing, which came first. The black hole or the galaxy. Probably big early stars, which would just made out of hydrogen and helium from the big thing. 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. But there's probably a deep relationship between the black hole-powering jets, these jets blowing material out of the galaxy that shaped galaxies may be kind of curbed to their growth. And so I think the mechanisms are still ongoing attempts to understand exactly the ordering of these things. - 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 time is just another dimension in this 4-D space that combines space and time? Because we've been talking about morphing in all kinds of different ways, the curvature of space that how are we supposed to conceive of it? How do you think of it and times just another dimension? - 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. But we're limited because as three-dimensional beings, we can't really draw four dimensions, which is what I'd require, three-spatial, some 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. Euclidean spacetime is when all the dimensions are orthogonal and are treated equally. Time is not another Euclidean dimension. It's actually a minkow skin 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, 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, and the geometries, 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 from an Euclidean space time, and that will allow me to calculate how long 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. So then what does according to general relativity does objects with mass due to the spacetime? 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 Churchill did is he found this very elegant, simple solution within like a month 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 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, equally surprising solution, which is that the universe would expand? 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 came with revelations that were not at all obvious when he first wrote down the general theory. And he was afraid to take the consequences of that theory seriously, which is a theory itself in its scope and grandeur and power is scary, so I can understand. Then there's 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. 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 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, 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. Wow. He didn't, obviously. There's so much we think of now that he didn't think of. So there's no big bang, static universe. But these are all connected. Wow. Yeah. So he's operating on very little information. 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 through experiments trying to figure out 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. Yeah, it's really strange. And then so from theoretical perspective, he takes that seriously. 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. 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. 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. 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. How was he able to intuit a world of curve? Space time. Like, it is one of the most special leaps in human history, right? Because you're-- It's amazing. Like, it's very, very, very difficult to make that kind of leap. 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 account surf 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. [LAUGHS] The equivalents principle comes pretty early on in his thinking and and It starts with something like this like 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 and Light down in a bed and I feel heavy on the bed and I think of that as gravity and I said it has a 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 elevators Resisting your fall, but I want to remove the elevator. What is 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 elevator I might not know if I was an empty space just floating Or if I was falling around the earth there 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 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. So actually yeah, god He says to me profound. So one of them is really one of the ways to experience space-time is To be falling to be falling that is the purest experience of gravity the experience of gravity Unfettered uninterrupted by atoms is Weightlessness Yeah, that observation. No, it hasn't unhappy ending the elevator story Because of atoms again That's the fault of the atoms in your body interacting electromegnetically 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 gonna 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 in space-time 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 a fuel that thing at all times, right? They turn off the engines They're just falling. Yeah, they're falling and they're not that far up They're there 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 or 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 space-time And that particular curve paths calculate in such a way that it curves onto itself So you're orbiting 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 But yeah, to be able to visualize that the beginning of the 20th century That not you know that free falling in in curved space-time Boy the human mind is capable of things. I mean some of that is um Constructing thought experiments that collide with our understanding of reality Maybe in the collisions in the contradictions you tried 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 it's kind of inspiring because You know, there's probably another general relativity out there. Yeah, in all Not just in physics in all lines of work in all scientific pursuits If there's certain theories where you're like, okay, I just explained like a big Elven in the room here. Mm-hmm. That everybody just kind of didn't even think about man. There could be Mm-hmm for stuff we know about in physics that could be stuff like that for the origin of life on earth. Yeah, everyone's like yeah, okay Everyone's like in polite companies like yeah, yeah, yeah, yeah, somehow it started Right, no, he knows. I find it wild that that's so elusive. Yeah, it's strange in the lab I think it's a general relativity thing. There's going to be something It's going to involve aliens and warm holes 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 biology. It'll be maybe through physics again Maybe the key to the origin of life is in physics and the same there is like a weird neighbor is consciousness It's like all right, we're neighbor. Yeah, it's like every okay, so we all know That life started on earth somehow. Mm-hmm. Nobody knows how We all know there were conscious We have a subjective experience of things nobody understands Right the people have ideas and so on, but it's such a dark Sort of we're entering a dark room where a bunch of people whispering about like hey, what's in this room? But nobody nobody is a effing clue. Mm-hmm. So and then somebody comes along with a general relativity kind of conception Where like it reconceives everything and you're like ah, it's like a watershed moment. Yeah Yeah, it's there and until it's there. We're living in the we're living in a time until that theory comes along It'll be obvious in retrospect. Yeah, right now we're Right. Well, this it was obvious To know one that space time was curved but even Newton understood something wasn't right So he knew there is 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 phenomena was at work With the earth around the Sun as the apple falling from the tree. That's insane That's a hugely Understanding that mass inertial mass what makes something hard to push around Is the same thing that feels gravity in at least in the Newtonian picture in that simple way I'm unbelievable leap Absolutely genius, but he didn't like That the apple fell from the tree even though the earth wasn't touching it Yeah, the action distance thing the action at a distance that is weird too well, but that is a really weird 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 trees 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 I would love it if somebody went back to Newton's time And told him all this probably some like some like hippie would be like it's a Gravity is just the courage in space time, man. I wonder if he would be able to I don't think there's you know every idea has its time He might not he might not even be able to load that in I mean that Sometimes even the greatest geniuses. I mean you can't Like you need you out of context. You need to be standing on the shoulders of giants and on the shoulders of those giants and so on I heard that Newton used that as an unkind remark to his competitor hook. Oh The people talk shit even back then It's one of the hilarious things about humans in general but scientists to like these huge minds There's these moments in history where You'll see this in the scene 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 I know your office is bigger than my own office. I know. This chair, this for or maybe you got married to this person that I was always in love with. That's a portrayal of something. The one woman in the department. Yeah. It's just, I mean, but that is also the fuel of innovation that jealousy, that tension that's. Well, you know, the expression, I'm sure the battles are so bitter in academia because the stakes are so low. 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 of humanity. The silliness, there's 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. Oh, yeah. There's a child like hatred. There's no question. Oh, yeah. The children can also be like children. Children. So like, you don't, I think when 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. The best scientists I know often ask the simplest questions. 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, 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. Yeah, just some of the topics, I don't know why I'm stuck to those two topics, the origin of life and consciousness. I'll talk about this. Some of the most brilliant people I know are just like with Newton and Einstein, they're stuck on it. This doesn't make sense. I know a bunch of brilliant biologists, physicists, chemists, they're 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 an lab. They're bothered, they, 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 discovery. Yeah, absolutely. The discovery is going to come because somebody couldn't sleep at night and couldn't rest. 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? 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. Black holes are kind of 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. 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. 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. 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 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 who use telescopes, they rely on the black hole as a terrain to perform their thought experiments. And it's because there's something fundamental about them. Yeah. General relativity means quantum mechanics, means singularity, and sadly, hard-breakingly so. It's ought to reach for experiment at this moment, but we'll then reach for theoretical experiments. It's in reach for thought experiments, which are quite beautiful. Well, on that top, we have to ask you about the paradox, the information paradox of black holes. What is it? 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, quantum mechanics, just a little smidge, you know. I 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? Stars 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. 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 is actually completely empty. We talked about the horizon, 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 not foundational. So that there's, in some sense, when it's in a precise location, it is fundamentally no longer in a precise motion. And that uncertainty principle means I can't precisely say a particle's 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, 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, they have the properties of the vacuum, you know, they don't, 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 is been separated by this event horizon. 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 where it has something that is no longer the property of that vacuum it came from. It needs its power 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 is, it'll escape, radiate out to infinity and look like to an observer far away that the black hole is actually radiated a particle. And the particle did not emanate from inside. 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 this separation on 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 was falling in from the inside. You say, well, this is actually motion and time. This is energy. It has negative energy. And it absorbs negative energy. It's mass goes 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. 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 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 we first said it, a lot of people describe that not everyone understood how really naughty he was being. He did. But some people who love quantum mechanics were really annoyed, okay? People like Lenny Suskin, Jed Zuft, 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, a sacredest conservation of energy. In this example, more sacred because you can violate conservation of energy with Tizenberg'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 or way too big. But as they get smaller and smaller, they get hotter and hotter. So as a black hole, near the end of the cycle of evaporating away, 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, 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, some quantum theory of gravity. Whatever these clues are in their heart 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. But it still has not been resolved. It has not been fully resolved. I looked up all the different ideas for the resolution. So there's the information loss, which is what you refer to. 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. 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. For you, the gut is like, the interior is going to be preserved. Preserved. The quantum mechanics is as close to the rescue as Lenny Suskind in his book, Black Hole Wars, as his subtitle is my battle with Stephen Hawking to make the world safe for quantum mechanics. It's something to that effect. So then from string theory, one of the resolutions is called fuzz balls. I love physicists so much. Originating from string theory, this proposal suggests that black holes aren't singularities surrounded by empty space and then about horizon. Instead, they are horizonless, complex, tangled objects, aka fuzz balls, made of strings and brains, roughly the size of the would-be event horizon. There's no single point of infinite density in no true horizon to cross. In some sense, it says there's no interior to the black hole. Nothing up across it. 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 that kind of shmure 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. So it's just adding a very large number of extra complex degrees of freedom. Yeah. There are no teeny tiny marbles to fall through. But it's similar to what we already have with quantum mechanics. It's just giving a deeper more complicated. It's really saying the interior's just not there ever. Nothing falls in. So the information gets out because it never went in in the first place. Oh, interesting. So there is a strong statement there. There's a strong statement there. Okay. So 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, they can store information about what fell in. Worth trying, but I also don't think that that's the case. So the no-hair theorems are formal proofs that the black hole is this featureless perfect fundamental particle that we talked about. That all you can ever tell about the black holes. It's electrical charge. It's mass and it's spin. And that it cannot possess other features. It has no hair. It's one way of describing it. And 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 they'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. It isn't such a stark demarcation between events inside and outside. And where I can't know what happened inside or outside. I don't think that's the resolution either, but it was worth a try. The pros and cons of that one, the pros that works within the framework of quantum field theory incurred space-time, potentially requiring less radical modifications than fuzzballs or information loss. Recent work by Hawking Perry, Stronginger, revitalized 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 ER. This is probably it, though. Oh boy. So ER equals ER is a Einstein-Rosen bridge equals Einstein-Podalski-Rosen bridge posits a deep connection between quantum entanglement, the space-time geometry. Specifically, Einstein-Rosen bridge commonly known as wormholes. It suggests that entangled particles are connected by a non-traversible wormhole. So tiny wormholes connected. Okay. I can say that this is not a situation we can follow the chalk. We can't start at the beginning and calculate to the end. So it's still a conjecture. I think it's very profound, though. I kind of imagine Juan Maldicina, 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 are 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 Maldicina, really formalized at Lenny Suskin, suggested at the idea of a black hole hologram is that all of the information in the black hole, whatever it is, whatever 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. 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, was actually just a holographic projection. Juan Maldicina did something absolutely brilliant. It's the most highly cited paper in the history of physics. It was published in the late '90s. 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 observed, doesn't matter. It's just a hypothetical, called an anti-discider space. It's a universe in a box that has gravity, 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 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. Yeah. So there's some mathematics there. There's physics. And then there's trying to conceal what that actually means practically for us. 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. EPR, Einstein, Pedalski-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 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 space time. 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 space time. The fundamental feature is the quantum entanglement embroidering the event horizon. The embroidering is just tiny wormholes. So the quantum entanglement is when two particles are connected at arbitrary distances. And they're connected by a wormhole. And in this case, they would be connected by a wormhole. So the reason why that's helpful, it helps you connect the interior to the exterior without trying to pass through the horizon. The cons of the theory is highly conceptual and abstract. The exact mechanism for information retrieval, via these not traversable wormholes, is not fully understood. Primarily explored in theoretical toy models, whoa, Jim and I go in hard. Theoretical toy models like the anti-dissider space time, rather than realistic black holes. True. We do what we can do in baby steps. So another idea to resolve the information paradox is firewalls, proposed by Amari Muroff Polchinski and Sully Amps. This is a more drastic scenario arising from analyzing the entanglement requirements of hawking radiation to preserve unitarity and avoid information 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. OK, so yeah, that's a nice solution. Just destroy everything that crosses this. Do you find this at all a convincing resolution to the information? 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 OK. No big deal. They sort of exposed flaws and these kind of approaches, 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 was born out of an attempt to address the concerns that Amps raised. So it did lead to progress. So for you, the resolution would-- I'm going back to the vacuum, the empty space, the beautiful event horizon. I'll give up locality, meaning that I will allow things to be connected non-locally by a wormhole. 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. 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. So all of this, like, space time 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 space time is not a smooth continuum all the way down. Now, people already thought that, but they thought it kind of came in chunks of space time. Instead, maybe it's just quantum mechanics all the way down. Quantum threads, so these entangled particles connected by wormholes. So that's how you would-- how would you even visualize a black hole in that way? So it's all-- I mean, it's all sort of from our perspective in terms of detecting thing, the light goes going in. It's all still the same. But when you zoom in a lot-- 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 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 what was interior to the black hole. So the information isn't a longer lost. So yeah, so information is not being destroyed. So in theory, you should be able to get information. Now, I can't do that anymore 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. Do you think a theory of everything that unifies general relative and quantum mechanics is possible? So we're like scourting around it. Yeah, we're scourting 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. And 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. - Emerge. So a lot of the mathematics of anything that emerges from complex systems is very difficult to-- - The transition's very difficult, right? - And so if that's the case, there might not be a simple clean equation that connects everything. - There are examples of emergent phenomena which are very simple and clean. Like I can just take electromagnetic scattering, just law of physics, where particles scatter just by electromegnetically. And I have a lot of them, and I have a lot of them in this room, and they come to some average, will 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's not a fundamental quantity. It's not a fundamental law of nature, right? It's just what happens from the collective behavior. And that's what we'd be saying. We'd be saying, oh, this disemerges from the collective behavior of lots and lots and lots of quantum interactions. - So when do you think we would have some breakthroughs on the path towards theory of everything showing that it's impossible or impossible, or all that kind of stuff? If you look at the 21st century, say you're, move a hundred 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? You're 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. So these puzzles that are before us is 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. - 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 it's really fascinating. All of those would also be clues about this question, but they wouldn't solve this problem. 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 gonna keep leaning on it, 'cause 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. - So when you mentioned discovering extra dimensions, what do you mean, what could that possibly mean? - Well, we noted 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. Strength theory requires extra dimensions to make sense, but even if you feel very hostile towards strength theory, there are lots of reasons to consider the viability of extra dimensions. And we think that they can trap little quantum energies in such a way that might align with the dark energy. The numerology's 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, and what we're really trying to understand is why did three get so big? And why did the other stay so small? - Is it possible to have some kind of natural selection of dimensions kind of situation? - Yeah, there is actually, and people have worked on that. Is there a reason why it's easier to unravel three? If 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 taught. 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 'cause they're small, 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. - Is it possible that there's other intelligent alien civilizations out there that are operating on a different membrane? It's just a bit of an out there question, but I ask it more kind of seriously, "Is it possible to think from a physics perspective "to exist on a slice of what the universe is capable of?" - 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. - Yeah. - 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 electroweek 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 do okay or did equally badly. And they suddenly had trouble finding, not only finding a single one, but sort of that would just beg a new question, which is, "Well, why that one?" And if nature can do something, won't she do anything she can try? And so maybe we really are just one example in an infanity 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 has 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 a shadow space. - Can you seriously say we can't communicate with them? - Well, that's fair, I'm limited in my communication 'cause 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 said he's doing with light into space, I could send signals into the bulk, telling them where we are and what we do and singing songs. - Sending gravitational waves is very expensive. We don't know how to do that. - Very expensive, very hard to localize. They tend to be long wave length and very hard to do. A lot of energy move around. - A lot of energy. - So is it possible that the membranes are quote unquote "herry" in other ways? Like some kind of weird-- - It is possible that there's other things that live in the bulk. Yeah, I mean, last night it was calculating weight. Looking at something that lives in the bulk. Okay, this is fascinating. So I mean, okay, can we take a little bit more seriously about the whole one? When I look out there at the stars, I, from a basic intuition, cannot possibly imagine. There's not just alien civilizations everywhere. Life is so damn good. Like you said, nature tries stuff out. - Yeah, nature's an experimenter. And I just can't just basic sort of observation life. You said somewhere that you like extreme of files. Like just figures shit out. You just find a way to survive. Now there could be something magical about the origin of life, the first spark. But I can't even see that. It's over and over and over. I bet actually once the story is fully told and figured out, life, originally on Earth, almost right away. And did the, so like billions of times 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 create life, seems to be a creator of different sorts. The very, from the very original primordial soup of things, it just creates the, I just can't imagine. But we don't see the aliens. So 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 planet's 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 our solar system. So my gut says, like some crazy amount of solar systems have life, bacterial life somewhere. But at some point in their history had some bacterial type of life, something like bacterial maybe is totally different guys of life. So then I'm just facing with the question is like, why have we not clearly seen alien civilizations? And there the answer, 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 can see a lot of them getting into trouble. I can see how we humans are really like 50/50 here. 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. We learn from our mistakes, we'll be a very coarse and save ourselves one hope so, right? 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. That's one way to see it, but I actually see it as the 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 on 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 go out amongst the stars or 50/50 destroy ourselves. It's like, which I think me as a human is a horrible thing, but if there's a lot of other alien civilizations, that's a pretty cool thing. You want to give everybody nuclear weapons? Half of them will figure it out, half of them won't, I mean, everyone, all these civilizations, 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. Right. You could use a kind of evolutionary Darwinian natural selection on that where survival isn't just in a harsh, naturally induced climate change, but it's because of a nuclear Holocaust. And then something will be created that is now impervious to that, that now knows how to survive. Yep. Exactly. So why have we seen them? 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, you're not very bright, didn't invite fire, didn't write sonnets, 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, pause, 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 blood, I mean, 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 I think we have to be way more imaginative if we're going to really take seriously life in the universe. Yeah, they might not prioritize conquests and expansion. They might not be violent. Mm-hmm. Like us humans. They might be solitary, they might not be social, they might not move in groups, they might not want to leave records. 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 that 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, and some sense out of what we're eating, and we've organisms on the Earth that can eat rocks. It's quite amazing. Minerals. I mean, talk about extremophiles. They can metabolize things that we're impossible to metabolize. 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 way. I mean, can you think of life as, because you said electrons, is there some degree of information processing required? So it does something interesting in quotes with information. 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 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. Yeah, yeah. It creates local pockets of low entropy and then the kind of mechanism, the kind of object that kind of life form that could do that probably could take arbitrary forms. And you could think, now, if you could reduce it all to information, now you can start to think about physics and then the realm of physics was with the multiverse and all this kind of stuff. You could start to think about, okay, how do I detect those pockets of low entropy? Mm-hmm. Yeah. I mean, people have tried to make arguments like that. And I look for entropic arguments that might suggest we'd done this before. The big bang has happened before. So, is it possible that there's some kind of physics explanation why we haven't seen the aliens? Like we said, membranes. 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 Justin, 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. And I think you're absolutely right when life was kicked off first barked here on Earth, it was voracious. It took a really long time, though, to get to multicellularity. I think that's interesting. That's weird. It's weird. It took a really, really long time to become multicellular. But it did not take long just to start. Yeah. What do you think is the hardest thing on the chain of leaps that got to humans? 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 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. It's a pre-on alive. 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 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 these rules of energetics. And the gray area between the non-living and the living is way simpler just on earth than you said. It's already complicated on earth, but it's probably even more complicated elsewhere where the chemistry could be anything. Carbon is really cool and really useful 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. Okay, as we get progressively towards crazier and crazier idea, 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 the 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. I think wormholes are a perfectly valid construction to consider. They're just, they're just a curve in space time. 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 space time. 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. They create these handles and holes in these sneaky, by topological, I mean, these connected spaces. Yes, like, who's cheese or something? Like, who's cheese and they write and they, so I can have, you know, I can 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 engineering. We were saying, oh, look, if I know how matter and energy are distributed, I can predict how space time is curved. I can reverse engineer. I can say, I want to build a curved space time like a wormhole. What matter and energy do I need to do that? It's a simple process and it's kind of thinkipthorn worked on very imaginative creative person. 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. And 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 are 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 chasmere effect. You're two metal plates and put them really close together. You can see this kind of quantum fluctuation between the plates. It's called a chasmere energy. And that can have a negative energy can actually cause a place to attract a repel depending on how they're configured. 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. Yeah. So you have to get a lot of this kind of weird matter. You need a lot of this weird matter to send a person through. Right. That's going to be really telling him. So I'm not saying we're simply an engineering problem. But it's all within the realm of plausible physics, I think. 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? Some people have looked at that. They tend to be nontroversible wormholes. They're not trying to prop them open. But yeah, I mean, some of this ER equals EPR quantum entanglement, they're trying to connect black holes. 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. So if I may read off some of the ideas that Keptornis had about how to artificially construct wormholes. So the first method involves quantum mechanics and 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. Man, playing with the topology of the Swiss cheese would be so interesting. Even to get a hint, 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, and I'm not sure, I'm not sure, being of like a question that can get answer to, maybe with some visualization, like the shape, the topology of the universe. Yeah. But like, I need some details. I'll get an answer that I could possibly go ahead. Right. It's a hyperbolic manifold that's identified across. Yeah. You need to be able to ask a follow-up question. Yeah, exactly. Yeah, that would be so interesting. Anyway, classical quantum strategy. The second approach combines classical physics with quantum effects. This method would require an advanced utilization to manipulate quantum gravity effects in ways we don't get to understand. There's a lot of, in ways we don't understand. Yeah, there's a lot of, and then there's exotic matter requirements. There's a lot of, 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 a building first. So 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 in energy? What are the conditions that I impose on matter and energy to build this architecture? Which is unfortunately a very early step of figuring out thing. 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. So do you think the studying of black holes and some of the topics we've been talking about will allow us to travel fast in 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? 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 space time between you? With some sort of something antithetical to dark energy, the opposite. And skip across and then push it back out again. That's all can 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 so we've already been confronted with something that we look at the space time. The space time 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 is 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 don't know what form of matter can do that yet, but at least I kind of identify the features that are needed. So figuring out what dark energy is might I'll add some clues? Yeah, it actually it might. It is positive energy and a negative pressure, which is kind of like a rubber band sort of quality. We think pressure is 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 doesn't have the right features for the wormhole, but those are some pretty surprising features. We again can conjecture like, "Oh, hey, 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. 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. But again, we can think of a kind of dark energy that exists. The question is, "Why is it such a weird value? Not how is this conceivable, because we can't conceive of it." But if it's a weird value, that means there is a phenomenon we don't understand. 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 we can say, "Oh, maybe it has to do with the size of the extra dimensions or the way that they're wrapped up." And so maybe 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. What do you think would lead to the breakthrough as a dark matter and dark energy? I think dark matter might be less peculiar than dark energy. My hope is that they're all tied together because 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 connected with why the dark energy is showing up right now. I would love that. That would be a solution like no other, and like I said, if it revealed something about dark dimensions, that would be a happy day. Correct me if I'm wrong. So dark matter could be localized in space. Yeah. Dark matter is localized in space. So it clumps. I mean, it doesn't clump a lot, but it's around the galaxy. It's in a halo around the galaxy. So people get increasingly more confident that it doesn't clump. Oh, it's really compelling. Yeah. 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 and you can see it colliding and lighting up, the dark stuff, which by definition it's dark because it doesn't interact, passes right through it's right through each other. And this is, I mean, it's so compelling. There's lots of other observations, 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. So dark energy is harder to get a hold of. Dark energy is much harder to get a hold of. But, you know, I mean, the Higgs field could have also explained dark energy. Yeah. If you've heard of the God particle, I don't know if you know the originally on Letterman co-authored a book and he wanted to call it the God damn particle because I couldn't find it. And his publisher convinced him to call it the God particle. He said, he said they managed to offend two groups, those that believed in God and those that didn't. That's a good point too. Oh boy. He was very funny. Yeah. He was very witty. So, you know, Higgs turned out to be. Higgs, great discovery. Yeah. Unbelievable. 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. 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. It's not a lot of quanta lying around. There's not a lot of Higgs particles lying around because they decay. But 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. So I wonder if you can comment on something that I've heard recently. And some people say people outside of physics say that 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? There's 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 Kobe, which is an experiment that measured the light left over from the Big Bang in the 80s, 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 and that's how we're able to confront it. Well, 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. 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 that 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 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. 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. Well, I can think of examples of dark matter that exist that we're 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? 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 the origin of us. So dark matter is known to exist. It's just again, there's not enough of it. It's not the right mass to be the dark matter that makes up this missing component. I wanted to say that I've been recently fascinated by the flat earth people because it's been a split in the community, first of all, the community's fascinating study of human psychology, but they did this experiment where I forgot who funded it, but they sent like physicists and flat earthers to Antarctica. And this split happened because half of them got converted into round earthers. Wow. We'll get for them. But then the other half just went that it was all a sigh out. Really? That's fascinating. Somebody filmed that? That would be a great documentary. Yeah, they did. They made a whole thing. This was just at the end of last year, there was a big, I mean, because I think it's such a clean study of conspiracy theories, because like, there's so many conspiracy theories have some inkling of truth in them. Like, there's some elements about the world. a government's operator from a psychology that there's it's too messy. Flatter to me is just clean. It's like spaghetti monster or something. It's just a cleanly wrong thing. It's a nice way to discuss how a large number of people can believe a thing. Yeah, and why do they want to believe a thing? What's very interesting is trying to use rational arguments. 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." Okay. 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 about reason and logic. Yeah, but also there's questioning of institutions that's really interesting and important to understand. Well, I mean, I actually appreciate the skeptics stance. I don't scientists also have to be skeptics. We have to be childlike. Now, even somewhat, in some sense, really open to anything. Otherwise, you're not going to be a flexible. You're not going to be at the forefront, but also to be skeptical. So I have respect for 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 going into this? Because as you said, this is something that's easily verified. I mean, we have people in space. So you have to believe a lot more machinery. 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. 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. 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. That's crazy. Yeah. 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 and Black Hole Blues is a book. But can you talk about gravitational waves and how we're able to actually do it? Let's just start with the idea of gravitational waves, sir. I have to move around a lot of mass to make anything interesting happening in gravity. I mean, if you think about it, gravity's 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 like that's insane. The whole earth, you know, gravity's 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 and the way that we've been describing things fall along the curves and 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 this Black holes, let's say, move around. Maybe I've got two Black holes in orbit around each other. That can happen. It takes a while. Wave is created in the actual shape of space and that wave follows the Black holes. This Black holes are undulating. Eventually, this 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 space time 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 hole that's spinning, beautiful stuff. And it emits 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 space time. 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 normal things that detect light. X-rays, formal light, gamma rays are a formal 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, it haven't done an anatomical calculation. But if you're near enough to two colliding Black holes, they actually ring space time 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. So the ideas that they're closer to something that you would want to map as a sound, then it's something as a picture. Sorry. So what do you think it would feel like to ride the gravitational waves? Like to be, to exist, to exist. As you mentioned, hear your drums. When you could 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. How would the experience be because you're inside space time? Yes, I see. So the Black hole is experienced within space time 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 would fall would be redirected. So it's literally like a squeezing and stretching. That's the way to think about it. And it's very detailed, the sort of nature of this. But for many years, people thought, well, these gravitational waves kind of have to exist for these intuitive reasons. I've described space times curved. I moved the curve. Their wave has to propagate through that curved space time. But people didn't know if they really carried energy. The arguments went on and back and forth and papers written and decades. But I like this sound more than an analogy because I like in the Black holes is like mallets on the drum. The drum is space time. As they move, they bang on the drum is space time. And it rings. Remarkably, those gravitational waves things don't interfere with them very much. So they can travel for two billion years, light years, you know, in distance, two billion years in time. And get to us kind of as they were when they were admitted 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 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 homes and wobbles. And they're like trying to play this recording drum back to you is supposed to taking a snap shot. It's like a in time. Yeah, but to construct this guitar. Yes, you have to again, it has to be very large and extremely precise. 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? That'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 four kilometers, spanning four kilometers in a kind of L shape with these tunnels where this is 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 space time. As it passes, this sort of undulation, that amounts to less than one ten thousandth the variation in a proton over the four kilometers. It's an insane, insane achievement. A low grade engineering. I don't know how they did it. I followed them around from, so I 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. I don't know how, I'm always surprised at what it looks like. But I walked the tunnels with Ray Weiss, who won the Nobel Prize along with Kip Thorn and Barry Bearish, 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, a 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, this whole thing is 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. It weighed on him, you know, 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 colleague said, "You're not going to get tenure. You're never going to succeed." And they just kept going. I feel like that huge teams, huge collaborations are just, it's how the world moves forward because it's an example. 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, bureaucracies slow everything down. So it's nice to see an incredibly unlikely, exceptionally difficult engineer project like this succeed. Oh, yeah. I understand why there's this weight on his shoulders and I'm grateful that there's great leaders that push it forward like that. Yeah. It really is. You see so many moments when they could have stumbled. Yeah. And they built the 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, you know, 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 and 2015. And the experimentalists are out there in the middle of the night. You know, they're working all night long in there. They're banging on the thing, literally driving trucks slamming the brakes on to see the noise that it creates. So they're really messing with the machine, really interfering with it just to kind of calibrate how much noise can this thing tolerate. And I guess the story is as they get tired, there's an, 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 U.S. 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. 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, you know, the 100 years, I mean, 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. What do you think is cooler, Einstein's general relativity or LIGO? Well, I can't disparage my friends, but of course, relativity is just so all encompassing. No, but so, hold on a second, all encompassing super powerful leap of a theory. Yeah. And they built it. They built it. I don't know, man. The greatest engineering on the, you know, because I don't know, because, you know, yeah, humans getting together and building the thing. That's really ultimately what, what impacts the world, right? Yeah. I mean, I, I just, as I said, my admiration for, for Ray and Kip and the entire team is, is enormous. And, you know, just imagining Ray had been out there on site. He had just left to go back home, wakes up in the middle of night and sees it. You know, can you imagine? There's a signal, you know, there's something in the log. He's like, what the hell is that? So speaking of the human story, you also wrote the book of Mad Men Dreams of Turing Machines. It connects two geniuses of the 20th century, Alan Turing and Gurdle. What specific threads connect these two minds? Yeah. I was, um, 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 Gurdle's work. That's where it began, and it began with this phenomenon of undecidable propositions or unprovable propositions. So, um, there was something huge that happened in mathematics, which is people imagined that any problem and math could technically be proven to be true. It doesn't mean human beings are going to prove every fact about everything in mathematics, 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 go to a very strange character, very unusual. He was a platenist. He literally believed that mathematical objects had an existential reality. He wasn't so sure about this reality, this reality he struggled with. He was distrustful, um, a 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, but 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. This incompleteness result was very disturbing, and essentially it's equivalent to saying there's no theory of everything from mathematics. It was very disturbing to people, but it was very profound. And Alan Terring got involved in this, because he was, you know, he was thinking about uncomputable numbers, so, um, 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. That might not sound like a big deal, was actually, was actually really quite profound. He was relating to goadle intellectually, right, in the space of ideas, but he goes a very different path, almost philosophically the opposite direction, he, he builds, he starts to, 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 it begins to imagine inventing a machine that will execute certain orders, you know, mechanize 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, 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. 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 people believe that turning 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, 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 Godel who doesn't really believe in reality and thinks numbers are platonic realities and Turing kind of thinking of, we're kind of like, we're actually machines and we could be replicated. So of course, Turing's influence is still widely felt. A many levels, so to the many levels in complexity, there's the theoretical computer science and mathematics, but also philosophy with his famous Turing test paper. So like you said, conceiving, like, what is the connection that I guess girdled and 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 humans. And they were very tormented. What aspects of that contributed to who they are and what ideas they developed? 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 of your insane, your brilliant, but I do think think if somebody who's very brilliant, who also chooses not to go for regular gratification of life, they don't go for money, they don't necessarily value creature comforts, 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. Yeah. 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 God, all you did have a wife and a strong relationship, as far as I understand it, was a successful mathematician and ended up at the Institute for Advanced Study, where he walked with Einstein to the Institute every day. And they talked about, and he proved certain really unusual things in relativity. You made reference to these rotating galaxies. We were talking and actually go to how to model the rotating universe that you could travel backwards in time. It was mathematically correct. Showed Einstein that within relativity, you could time travel just an unbelievably influential and brilliant man. But he was probably a paranoid schizophrenic. He did have breaks with reality. He was, I think, quite distrustful. The government feared his food was being poisoned. And ultimately, literally starved himself to death. And it's such an extreme outcome for such a facile mind, for such a brilliant mind. I think it's important not to glorify a romanticized madness or suffering. But to me, you flip that around and just be inspired by the peculiar maladies of a human mind, how they could be leveraged and channeled creatively. Oh, yeah. I think a lot of us, obviously, probably every human has those peculiar qualities. You know, I talk to people sometimes about just my almost like collagen. I'm extremely self-critical and drawn to the beauty in people, but because I make myself vulnerable to the world that can really be hurt by people. And that thing, okay, you can lay that out. That's this particular human. And, you know, there's a bunch of people that would say, well, 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 going to die 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, I might destroy you. And I think a lot of these stories are that it's not that, oh, yeah. 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, your particular part of society, use that somehow. Use the tension or that, the friction or 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, oh, yeah, that could be everything. My grains is like psychostomatic or psychophysical. And all of that, that's the real, that can somehow be channeled into a productive life. It should be inspiring. A lot of us suffer in different ways. 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. And I guess I, 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 protect yourself, right? But isn't that exactly what you're bringing? One of the elements that you're bringing that make something extraordinary in a space that lots of people try to break through? Yeah. And we should mention that for every girl in touring, there's millions of people who have tried and who have destroyed themselves and without without reason. I would find it impossible. To not pursue a discovery that I could, I could imagine my way through or if I can really see how to get there, I cannot imagine abandoning it for some other reason, fear that would be misused, which is real fear. Right? I mean, it's a real concern. I don't think it might work since I'm doing extra vengeance in the early universe, but or black holes, you know, I feel pretty safe. But I mean, who knows, right? Bore couldn't think of a way to use quantum mechanics to cope people. I cannot imagine pulling back and saying, nope, I'm not going to finish this. You know, I'll give you a counter example of an exceptionally brilliant person, Terence Tao. Brilliant. Brilliant mathematician. Brilliant. 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. Oh, that I can do. It's stepping away. Yeah. He's like, okay, this is now a weekend problem. Uh-huh. Because he has seen too much for him. Every is different, but Gugory Proman, or Angiwiles, who give them so full, completely, many years or so problem. Yes. And for every Gugory Proman. And they might not have cracked it. Yep. So you choose your life story. I totally agree. Now, I'm not going to say sometimes I take too long to come to that conclusion, but I will proudly say as most theoretical physicists should that I kill most my ideas myself. Okay, and that's I am absolutely able to say, oh, that's just not I mean, I'm not going to deny that sometimes I maybe take a while to come to that conclusion longer than I should, but I will 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 Angiwiles, you're describing who to prove from that'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 but that's so it could have been interminable. He still might not have gotten there in the end. And so that's 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. And he had a really I would break me straight up break me. He had he had a proof. Yes. He announced it and they somebody found a mistake in it. That would just break me. Yeah. Because you now everybody gets excited. Right. And now you you realize that it's a failure and to go back taking a year for people to check it. It's not the kind thing you look over in an afternoon. And then to to have the will to have the confidence and the patience to go back unbelievable, to rigorously go through work through it. Great story. But then there's another great story. You're a pro man who spent seven years you can turn down the field metal. He did it all alone. Not after he turned down the field metal and the millennial prize proving the pancake injection. He just walked away. Yeah. Now that's a very different psychology. That's why you're differently. Doesn't care about money. Doesn't care about fame. Doesn't care about anything else. Yep. In fact, where is he now? In St. Petersburg, where I should trying to try and 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 take and we're dude in the tight. So it turns out I'm trying. I'm trying. 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 really don't like it when it's portrayed that way. These are really individuals who who were still lost in their own minds, but in very different ways. And Turing was openly gay, really during this time you're going to use working during the war, World War II, we understand the era and it was illegal in Britain at the time and he kind of refused to conceal himself. There was a time when the kind of attitude was won, we're just going to 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 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. 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 poem songs, dip the apple in the brew, let the sleeping death seep through, it was a chant from Snow White and the belief is that he dipped an apple in cyanide and bit from the poison apple. Now, I don't know if this is apocryphal, but people think that the apple on the mackintosh with the bite out of it is a reference to tearing. Now, some people deny this. But some people say he did that so his mother could believe that maybe it was an accident. But yeah, quite a terrible end. Yeah, but to the greatest humans ever. I think the reason why I tie them together, not just because ultimately their work is so connected, but because there's 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 right-factual biography, there's something that eludes you and I felt like that's kind of fundamental to the mathematics, the incompleteness, the undecidable, yeah, computable. 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. Yeah, limitations of formal systems, limitations of biography, limitations of fiction and nonfiction. 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, the exploring the very rigorous detailed physics and cosmology of things. So there's the kind of artistry. So I saw the year the chief science officer of Pioneer Works, which is mostly like an artist type of situation. It's a place in Brooklyn. He explained to me what that is and what role does art play in your life. 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 at this collision. It was founded by this artist Dustin Yellen, very utopian idea. He bought this building's old iron works factory called Pioneer Iron Works and 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. He wanted a place of a collage, a living example of artists and scientists and it was founded by Dustin and Gabriel Florence 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 waterline 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, there art, gave makes everything, build everything with his bare hands, Dustin's a dreamer, they love science, they really wanted science, but science is hard to access. 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 doing culture and artists 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 or seeing a little bit from the summit, if you've had a little glimpse yourself that you bring it back to to the world. So we plume, exploded, Pinerics 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 and a lot of live events. 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, my first guest, like you, I was talking to people. And this was like, I don't have to talk to people because I know these guys. And I've been on the interview east side so much. I know exactly. It was like fully formed for me how to do those conversations. Yeah, you're extremely good at that also. 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. It's really interesting. And I love to say, 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. And I saw there's a bunch of cool events and very, very fascinating variety of humans. Yes. We have a really fascinating variety of humans. That's a good way of putting it. So it made me put in my mental map of like, it's a cool place to go and visit when in New York. Yes, you have to come see us. I think you would love it. Also, I should mention fashion. I've seen you do a bunch of talks and this is a lot of fashion. Oh, yeah. Oh, my God. Appreciation of fashion going on. 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 Rizn 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. We should show this as overlays. Hopefully there'll be nice pictures about everywhere. 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. You said with life. With life. Nice. 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 could 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 Green, Massimo Pirati, Dan Kabat, 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 are amazing. But we really are doing it together. You take one element out and it starts to change shape. And that's a very interesting experience, I think, and making things is an interesting experience. So, as you mentioned, literature, is there books that had an impact in your life, whether it's literature, fiction, nonfiction? 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. Can you ever make that public or no? Yeah, I suppose I can. I can tell you some of them as they come to mind. Katsu Ishiguru, who won the Nobel Prize, 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 people can do that with these very abstract themes, it's sort of my favorite space for literature. Martin Amos wrote a book that runs backwards time's arrow. I love some of his other books even more, but time's arrow is pretty clever." So you like it when these non-traditional mechanisms are applied to tell a story that's fundamentally human, that there's some sort of magic tragic. 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 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 of Science? Well, first of all, Chronic McCarthy absolutely loves scientists and science. And you can feel this very subtle influence in that book is it's a really remarkable, precise, stunning, ethereal, all of these things at once. 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. And still fundamentally that book is about human story. Yeah, absolutely boy. Yeah. So the science plays a role in creating the world. And within it, there's still really it's a different way to explore human dynamics in a way that's maybe land 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, it's another art form to be able to tell a simple story with some surreal elements. Yeah. Well, just simple language. Oh, and the farm's incredible. And fact, some of the, I've kind of played with, you know, some animals are more equal than others. There are ingotal turings work. There were some infinities that are bigger than others. Yeah, there's certain books just kind of inject themselves into our culture in a way that just reverberates. And I don't know, hasn't creates culture, not just like influences, it's just like, it's quite incredible how writing and literature can do that. Yeah. If you could have one definitive answer to one single question, this is the thing I mentioned to you. Yeah. 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 it's just clarify what mystery of the universe would you want that oracle to help you? No, it's funny. I should say the obvious thing. And but I feel like I almost think 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 is 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 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. I mean, we're not going to have all the answers. I hope because then sort of and what? Right? It's sort of dystopian. I totally agree with you. There's some, I like the mysteries we have. I kind of had this assumption that there will always be a mystery. So you want to keep solving them. They will lead to more. And 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. Yeah, by the way, we should mention that if you're talking about the Oracle and even if you ask the obvious question about quantum gravity, I almost guarantee you with a hundred percent probability that even if all your questions are answered, it's impossible to get to the end of your questions. It says, you know, the Oracle will say, no, you can't unify. And then you say, well, yeah, and then you say emergent. And then the Oracle, you know, Oracle say, well, everything you think is fundamental is not. It's emergent. It's like, okay, well, this is, this is, we need to have more questions. I mean, it's been a hundred years more since relativity and we're still picking it apart. Yeah. 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? Yeah, that'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. Yeah. We're too sorry. 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, how we contribute it and did we, you know, did we contribute overall net positive? 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. Well, at the very least, we can focus on drawing something beautiful in the sand before it's washed away. Well, this was an incredible conversation. I'm truly grateful for the work you do. And me for your work. Thanks so much for having me. Thank you for talking to me. Yeah, lots of fun. Thanks for listening to this conversation for Channel 11. 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 the red hot cinder, a second seems like an hour. That's relativity. Thank you for listening and hope to see you next time.