Into the Impossible With Brian Keating - Leonard Susskind: What REALLY Happens Inside a Black Hole? (#364)

Episode Date: November 5, 2023

What's really going on in a black hole? Why are there so many theories of everything? And did Leonard Susskind, the father of string theory, ever feel like an impostor? Find out in this thrilling interview with none other than Susskind himself. Susskind is an American physicist and a professor of theoretical physics at Stanford University. He is also the founding director of the Stanford Institute for Theoretical Physics. In 1995, Susskind was the first to give a precise string-theoretic interpretation of the holographic principle and the first to introduce the idea of the string theory landscape in 2003.  In this interview, we discuss Susskind's popular science book, The Black Hole War, which covers the black hole information paradox and the related scientific dispute between Stephen Hawking and Susskind himself. We also talk about other developments in modern physics and more! Tune in! Key Takeaways:  Intro (00:00) The difference between writing for broad and small audiences (05:56) Impostor syndrome (08:58) The first image of a black hole (19:33) The horizon of a black hole and the existence of a singularity (22:05) Mathematician envy (36:51) Why are there so many theories of everything? (44:07) Three things that would push him to believe in the Multiverse (48:25) Audience questions (57:06) Who would Lenny have for coffee? (1:05:33) What would he put in his ethical will? (1:10:51) Outro (1:17:34) — Additional resources:  🥗 Thanks, HelloFresh! Go to HelloFresh.com/50impossible and use code 50impossible for 50% off plus 15% off the next 2 months. 📝 With a MasterClass annual membership, you can take one-on-one classes from the world’s best for $10 a month with your annual membership, get unlimited access to every class — and even better, right now, as an Into The Impossible listener, you can get 15% off when you go to MASTERCLASS.com/impossible. 🧑‍💻 Visit LinkedIn.com/IMPOSSIBLE to post your job for free! 📚 The Black Hole War by Leonard Susskind: https://a.co/d/a9WGKAc  ➡️ Follow me on your fav platforms: ✖️ Twitter: https://twitter.com/DrBrianKeating  🔔 YouTube: https://www.youtube.com/DrBrianKeating?sub_confirmation=1  📝 Join my mailing list: https://briankeating.com/mailing_list  ✍️ Check out my blog: https://briankeating.com/blog.php  🎙️ Follow my podcast: https://briankeating.com/podcast  — Into the Impossible with Brian Keating is a podcast dedicated to all those who want to explore the universe within and beyond the known. Make sure to follow so you never miss an episode! Learn more about your ad choices. Visit megaphone.fm/adchoices

Go where your curiosity leads you. Pay no attention to what people are saying is or is not good science. If you are curious and you want to understand something, follow your nose and go where your curiosity leads. That's the only thing I can say. All of the very, very good theoretical physicists that I know have done exactly that. Any sufficiently advanced technology is indistinguishable from magic. Open the pod bay doors, Hal.

Welcoming Lenny Suskin, who is a good friend, mentor to many of us. Just a reminder, we're going to have Kamran Vafa, Lenny's friends, Kamran Vafa, Barry Barish, Ray Weiss is also coming on in the next week or so. And we'll have on Shelley Glashow, who's a fellow alum of Bronx Science Lenny's alma mater. We're just remarking how much fun it is to do talks in your pajamas, but also missing out on the, missing out on the pleasures of interacting with colleagues, and especially Lenny's colleague, Stephen Hawking.

Lenny, I'm sorry, could you just say again, what did Stephen mean to you personally as a foil? He wasn't the easiest person to get along with. I remember hearing that for many people, but he had this magical captivating effect on all of science, so much so that if you asked any person, who's the most famous scientist, they would say someone like Stephen Hawking,

not me. Well, there were many aspects of Stephen Hawking. First of all, he was a great physicist. There's no question of that. Maybe it was a little bit of a stretch to say that he was Einstein or Newton, but he was a very, very, very important influence in physics. But, you know, there are other aspects to him that certainly caught people's imagination. His stubbornness against overwhelming odds, how he managed to,

to not just survive, but to flourish and to do great physics when he could barely move no more than his eyelash. This is an incredible story. So he was, in addition to being a great physicist and a hero to physicist because of his physics, he was a gigantic hero in a much bigger sense. That being said, he could frustrate me, he could annoy me, he could anger me, But not because of any personality glitch, but because I was very frustrated by, let me call it, his incredible stubbornness not to recognize the, to my mind, not to recognize the importance of his own work in a sense. He had asked an extremely deep question, a question that has dominated theoretical physics ever since the, for 30, 40 years now. But I felt he had taken the easy route and tried to find an easy answer when the answer was far more subtle and complex. His recognition of the question was monumental. His answer was probably not.

His answer was, information is lost in black holes. That seemed wrong, and I wanted Stephen very much to realize that his question would lead to something much deeper than what he had envisioned. So he was, that's right, he was a very complicated man, very complex and interesting, for sure. The problem was, it was hard to communicate with him just because of physically hard to communicate with him. I remember once seeing him speak at a Royal Society meeting that I had somehow, stolen someone's invitation to attend. And Stephen was there out of the guest and it was 1996 or so and someone asked him a question and this was when he could still move his finger. So he said, they asked him, why did you write a brief history of time? It's rumored that no one

understands the entirety of this book and no one's even read it. And Stephen answered in his inimitable synthesized voice, I wrote it because my daughter needed to go to college. and his sense of humor comes across. Of course, your books are known for their clarity, but not for their dumbing down. I actually learned quite a great deal, not that it's like some great encomium to hear from some nobody like Brian Keating

that he benefited and profited greatly from your book. But some of the topics that you talk about are more relevant than ever nine years after its publication. And I want to ask you, in the intervening nine years since you wrote the book, what has changed? What would you write differently if you were to write this book again,

other than lamenting the loss of your friend and rival in a friendly way, Stephen Hawking. Actually, I think I wouldn't write anything different. I think I would write almost exactly the same thing. But the difference would be that I would have written another book right afterward on the follow-up of what happened afterwards. The follow-up of what happened afterwards in the last... When did I write that book? 2005, something like that.

is now, let's see if I can do the arithmetic, 15 years later. The subject is the subject, and the subject means the subject of the quantum mechanics of gravity. That subject is not only expanded, but it's been clarified, not more than clarified, almost revolutionized by new ideas, ideas that I did write about in that book, but which have developed extraordinarily surprising, directions. So I don't think I would have changed what I wrote in that book. I would have another book afterwards. I don't know if I have the, I don't know if I have the endurance to do to do it. Yeah. I mean, when we think about books, so your most famous paper, I looked up, you know, citations. I forget what it is. It's several hundreds to a thousand citations. This book and your

other book, the Cosmic Landscape, I think, that book sold tens of tens and tens of thousands of copies. What's the difference when you write a popular, a book for a popular audience that has a a lot of red meat, sorry to my vegan fans, but versus writing, you know, a paper, which might be read by a few thousand nerds at most and maybe not even all the way through, versus your book writing for the popular audience that's consumed rabidly by hundreds of thousands of people. Well, first of all, I've always gotten a lot of not just pleasure, but I think more than pleasure out of explaining things. I like to explain things. And there are at least two reasons why I enjoy explaining things so much.

First of all, I'm a ham, and I really get a kick out of showing people how clever I am and how easily I can explain things which sound hard. So that's one aspect of it. But the other thing, which is very important, is the process of explaining for me teaches me a great deal about the subject I'm explaining, and the more I try to explain it to a less and less technical audience,

the more I learn new ways to think about things. So it's an important part of my own physics, the process in my own head, what goes on in my head when I try to explain things. On the other hand, the business of writing a book like the Black Hole War gave me an opportunity to try out something that I'd never tried out before.

That was to write about people, to write about myself. When I write a physics paper, I don't write about myself. And if the paper happens, to have reference to Stephen Hawking or somebody else, I don't write about them. I write about their equations. This was something I had always wanted to try my hand as a writer and see if I could both write a little bit about myself, about the people I knew,

the whole human aspect of theoretical physics. And I found surprisingly, much to my surprise that I had some ability to do it. I had a terrible time as a student, as a young student with my English classes. I was always considered a very poor English student. I don't know why that was. You talk about having a little bit of a, maybe it was a complex, but maybe it was more of a chip on your shoulder. And I see you as, you know, you're a brawler.

You're one of these tough, you know, New York Jews. I hate to keep bringing up our common background. But the point is, I think I characterize you as fearless. I don't think that you're infallible, but I feel like you're fearless. And I wonder if that modest upbringing you had with parents, your parents didn't go to college, right? No, no, no. My father got through the fifth grade. My mother, I think, got through the 10th grade.

And now you're a member of the National Academy of Sciences. What does that feel like? Did you ever have what we call imposter syndrome in academia? I don't think I felt that was an imposter because I felt I wasn't talented. But, you know, I came from this very working class background. My formative years up to the age of about 22, most of the people I knew were very working class. My father and his plumber friends, I was a plumber for a while. And CCNY was not a place where you got the Harvard, what should I call it, patina.

It was full of working class kids like myself. We didn't live on campus. We took the subway to school. So when I finally got to graduate school, I felt very out of place. People were extremely kind to me at the, like Cornell. They felt I had talent and they were extremely kind to me, but I felt out of place. I felt I was in a world that I didn't come from and felt awkward in it. And I don't know if I felt I was an imposter, but I did feel very much an outsider.

And I did wonder, do I really have as much talent as I hope I have and to justify how nice people work to me? So, yeah, and I think that lasted a long, long time. I felt like an outsider until I suddenly discovered I was the ultimate insider on the subject. How do you mean the ultimate insider? Well, I began to discover that half the population of theoretical physics had been my students. or my postdocs or my, all my close friends. And I also began to feel much more comfortable in the academic world, just probably because people listen to me.

People tended to accept what I said. I think I was probably 50 before I began to feel comfortable in the academic world. And that was long after you were at Stanford, right? I mean, this is... Long after I was at Stanford, yeah. went to Stanford when I was 37, 38. And to what do you, what would you recommend to somebody, younger person now, not quite 50, who still struggles with this, who has kind of this alternating view of himself or herself as

talented, as curious? What is the test? What's the metric that someone can use to keep encouraging them to go on? So maybe I won't give any advice about how to get out of that predicament, but maybe I will give some thoughts about how to do. to use that predicament. Yeah, very likely my own sense of, I won't say inadequacy, I didn't feel inadequate, my own sense of discomfort probably to some extent may have led me to be more independent, more, and to push harder on ideas. Maybe I just wanted to succeed because I did have this

feeling of outsideness. So I would say just whatever your, whatever your, what's the right word, whatever your sense of not belonging or whatever it is, use it. You probably can't get rid of it that easily. Find a way to use it. And you even had encounters on the sacred grounds of Cambridge and Oxford and Utrecht and all these places that you recount. The book is an adventure story.

I kind of think of you. It's a cliche, but, you know, the Indiana Jones of theoretical physics. I do feel like Sigmund Freud once said something to the effect that, you know, a man who is loved by his father and mother in some senses like destined for greatness. And it applies to women, too. Do your parents give you confidence? I mean, you weren't raised Jewish. What was your, you know, parents? I was raised Jewish.

I mean, you were raised Jewish, but you weren't, you're not believer now. So what was your, what was your? No, no way. I wasn't raised religious. Yeah. Be careful. I mean, yeah. I was raised quite Jewish out of a different tradition.

The tradition was Jewish leftism, leftism coming from before there was the Soviet Union. My parents and my parents came out of Eastern Europe at the time of the Tsar. And they were leftists. They were all leftists. They were not religious. I suspect my father's family were atheists, but they were. And that's what I grew up in, but it was very Jewish. What it wasn't was religious.

And when you meet people, as you talk about in the book, ranging from Feynman to, to, you know, obviously Stephen Hawking had the use of none of his, you know, real physical faculties, but he kind of depended as much on his mental acuity and so forth. You talk a little bit about being disappointed recently, you know, that maybe he didn't take it as seriously as he should have. I mean, he was known for these bets. I always found that, you know, There was a famous signed wager outside of, in Bridge Hall at Caltech, where I was a postdoc after getting fired from Stanford.

We'll talk about that some other day. But that, you know, poster of the bet with Kip Thorne, which Kip Thorne had to concede because, and I think it was over like a subscription to Playboy or something like that. But Stephen was this mercurial figure. And I wonder, you know, you talk about how, yeah, it was almost like a feeling of frustration. Like, you want that competition. You thrive on the kind of battling and the resistance. that we get from our colleagues. And I wonder, you know, if we've lost that. I mean, you're, you know, closer to, you know, to, you know, the, the, the, the, the, the interaction with Stephen than I ever was. I just meant him not one time. But when you think about, you know, physics today, is it, has it changed, you know, for the better or for the worse in terms of the conflict that we now see move to social media on Twitter? I know you're not on that, which is why you're so productive. So nowadays we see like these battles, like today there's a battle about life on Venus, you know, and it's being waged on Twitter. What do you make of that compared to your battles

in person? It's terrible. It's terrible. Okay, life on Venus. The war over, I don't mean the Black Hole War. I mean, was a much nasty a war over where the string theory is a contribution to science or a contribution to anti-science that takes place on the blogosphere. And I do from time to time read some of it, I think is very, very destructive. How is it destructive? It's foolish. It's silly. Largely the people don't know what the hell they're talking about.

And especially if you read the commentary that comes after the things that the bloggest says, they can be indecilic. They can truly be imbecilic. But what does it do? What does its net effect? I think it adds to the sense that you can't trust scientists. Now, scientists are not always right. But they do try.

There's very, very little, in my experience, there is very, very little dishonesty in the science that I think I am involved in. Maybe no dishonesty. They can't say none, but very, very little. And when you read these blogs, you would think that every string theorist is doing what he's doing only to be able to get more money from the NSF. This is utter BS.

And the counter. So I said, I think it's dangerous. I think it's dangerous. And I think it's counterproductive. And I damn well wish it would go away. Hello, students of the impossible. It's Professor Brian Keating here with just a tiny little home assignment to interrupt your podcast. And that's to make sure that you're subscribed to the podcast or following us on your podcast app of choice. Get some research and actually only about

50% of you are actually following or subscribing to the Into the Impossible podcast. And really mean a lot if you could subscribe and keep up to date with me and with all the greatest content. I'm putting out tremendous amounts. Podcast has grown in popularity, but it can be better and bigger with your help. Do that. Please do it now. Don't wait. You'll forget. If you're looking to really boost your position on the grade curve for some extra credit, make sure to leave a rating or review of the podcast. It really helps. Thanks a lot. Now back to the show. I know you sure, you know, Paul Steinhart, my friend at Princeton University, feels the same way. And he actually feels it's even more invidious than, as you recount, because as you know, sometimes you have

tentative ideas. I'm an experiment. I'm just a simple experimentalist, closer to a plumber than you nowadays. Well, okay, that's such a misconception. I'm just kidding. You know, Jim Simons once told me a joke about plumbers. He said he had to call a plumber once, and the plumber came to his house early in the morning to fix some leaky toilet,

and Jim asked him, how much do I owe you? And he said, $800. And the plumber, and Jim Simon said, what are he talking about? $800, you're only here for 15 minutes. You know, I don't make, even I am a hedge fund manager. I don't make $3,200 an hour. And yes, he does.

And then, but no, then the plumber says, you make $3,200 an hour? Hmm, that's what I used to make when I was a hedge fund manager. But getting back to it, Paul Steiner would say is that sometimes you have these tentative ideas as a theorist. Again, I'm relying in your experience, not mine. And they're not ready for fully being vetted because you need to ruminate, marinate them in your mind. But with social media, now this gets leaked out and you're giving a talk and someone takes a picture, posted online, and then you can be ridiculed. So I agree. I think it is very pernicious. And I wonder, you know, if it's if it's irreversible, is it like a ratchet? It's not going to go back. What do you think? Things come and go and I don't know. That's something I can't predict. And since I'm not particularly a social media person, I probably see less of it than most people. But I do see some of it. And it irritates me to no end. Yeah, it probably won't go away. Now, it has very little effect on the physicists themselves on what they do.

none whatever, I would say. But I think it has an effect on the public that people tend to trust science and scientists less because of it. Yeah, I know. I look at it. I'm always amused when someone says trust scientists. I don't know a scientist who just trust scientists without a reservation. Of course, subject matter experts should be listened to. But I think blindly obeying, you know, just because someone's a scientist, I mean, look, there's a lot of misinformation that masquerades

of science as well. That's absolutely true. How did you react to the, not only to the event horizon image of the event horizon of a black hole, but also the Nobel Prize to Andrea Gess and to Reinhard Gensel for the discovery of a compact object. They went another way not to say it was a black hole, but a compact object. What does that data feel like when you look at it? I don't look at it. Look, I'm not in the least bit amazed at this point, at this point in history, that there are black holes out there. Of course there are black holes out there. We've known that for a long time. That's not the point.

What I am amazed at is two things. First of all, the ability of the human mind to have even created the idea, not they didn't create the idea, absorbed the idea, understood the idea. The whole idea that a couple of pounds of gray flesh could have, could have conceived of, understood, and developed the ideas of general relativity and all that sort of stuff is amazing. It's more than amazing. It's otherworldly. And on top of that, the ability of observers and experimenters to be able to figure out how to actually observe and do those things and the subtle, subtle technology that went into it, which I don't know a great deal about, but I can conceive of it,

is really off-scale. So I would say this particular thing was a great triumph of observation and experimental physics, being able to see something which is extraordinarily difficult to have conceived and built the machines and the apparatuses, which was so subtle, and so fine that they were able to see something so hard that when I was a young physicist, we couldn't conceive of being able to observe a black hole. So it is a triumph. It's a triumph of theory, but it's even more so this particular thing that you're talking about, a triumph of experimental science.

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Google Fi Wireless is not subject to data traffic deprioritization during times of high network usage. I wonder this because I don't very often get a chance to talk to folks like you. Although I do have some great guests on the show. again, a reminder, Tamara, Shelley Glashow, Kamran Vafa, and John Preskills coming up. These are all characters in the Black Hole War, and they're very much real, non-fictional characters. I ask all of them, I asked Roger Penrose this, too. I said, you know, part of the citation or part of the recognition that you receive, this, you know,

golden, this is my guilt version of the Nobel Prize that I got when I was at the Nobel Museum 10 years ago. But the part of the, part of the, you know, motivation is your work on singularities. And I asked him, why should we think there's a singularity? I always have an issue with this. It's almost like these snakes that you talk about, the uroboros, the snake that eats its tail. We say that we need a singularity because quantum mechanics, you know,

is not well understood in the vicinity. Or sorry, gravity is not understood at the quantum mechanical scale. Everything in the forward direction heads towards a singularity. We talk about the big bang, and the big bang being a singularity, you know, hawking, Penrose, hawking, Hartle. we talk about these things, but it seems like you need to justify quantum gravity because there could be these two regimes that are in principle unobservable, namely the core of a black hole and the beginning of the universe.

To what extent would you bet your neighbor's pet ferret's life on the existence of a singularity? Do you think they really exist? About the cosmic singularity at the beginning of the universe, I don't know and I'm somewhat suspicious. I think a singularity in that sense, we simply don't know. And the singularity inside a black hole, what the singularity means is it doesn't necessarily mean a mathematical singularity. What it means is the place where things get so dense and so hot and so dense, I guess is the word, that the laws of physics as we know them break down, or at least where the classical laws that went into general relativity breakdown. And so we can't really, we don't really know

what happens there. But what I would say is this, up till now, far more interesting than the singularity has been the horizon of a black hole. The horizon of the black hole is as quantum mechanical in its own right as a singularity itself. And the horizon of the black hole is observable. That is what we observe when we see black hole. Well, I mean, technically we're seeing the light shadow in the event horizon telescope, right? It's a little different than the stretch. It's certainly not the stretched horizon, which is... No, we're not, we don't directly see radiation, hawking radio. The only thing that comes out of the horizon is hawking radiation. We don't see that. That's correct. What we see, though,

you see a black disc. The black disc, and around the black disc, you see these rings of light. Those are rings of light which have been focused by the gravity of the black hole. The black disc itself, the radius of the black disc, is not something that has to do with a singularity. It's something that has to do with the horizon. That black disc, if you like, is size, its properties, are the horizon.

Now, if you could see really clearly, and in a sense, the gravitational wave detectors do see fairly clearly, what happens to the horizon when it's perturbed? How is it perturbed? It's perturbed by another black hole

crashing into it. And when you hear the ringing noise and the sound that's produced by these two, not the sound, but the gravitational radiation coming from it, that is pretty much direct observation of the horizon. of the black hole. So at the same time that you were engaging when the first opening skirmish

between you and Stephen Hawking took place in 1981, Stephen remarkably, I think that was when he was at this Newfield symposium around the same time with Steinhart and others. And they were debating the nature of inflation. And I wonder, just before we leave the notion of the reality of singularities, I wonder if God, you know, I know who you don't believe in, if God handed you a letter and said, the Big Bang is actually like Roger Penrose thinks it was. It's this conformal cyclic cosmology that goes on eon after eon. We'll get into that later.

In other words, there was no Big Bang singularity. What would that do to your Bayesian priors about the physical existence of a singularity? I understand what you said about mathematics, but the physical existence of it. Would that decrease your credibility? Let's be very specific. We're talking about this oscillating version of, that both Paul Steinhardt and Roger Penrose have advocated. I would say, God, why did you violate your own laws of physics?

You have violated the second law of thermodynamics. Even you can't do that. If you did do it, if you did do it, I will never trust you again. The second law? The second law of thermodynamics is one of the most fundamental, logical laws of physics. I don't believe you. So it's sacred. Of course, that's what led Roger to his, you know, claim that the entropy is so improbably low. Yeah, yeah, that's fine. That was fine. Okay. But this idea of this universe,

which is pulsing, no, that's a perpetual motion machine. That violates the laws of thermodynamics. And boy, those are the ones that I don't, I don't like. I don't like it. Oh, actually, okay. So Paul's. I'm talking to God, no. I'm not talking to you. I know. Don't you do that, God. I'm his surrogate. I'm his surrogate. I'm his. prophet, the Navi, the Navi Brian Keating. I want to say, yes, so it is true that Paul has this special contrivance, and actually we have debated that, he and I, but Paul's model doesn't depend on perpetual motion. It depends on... No, Paul's model is a perpetual motion machine. I have explained that to an endless number of times. He agrees with me by the time that we're finished through the discussion,

and then he goes on to say it again. Now, let's go on to something else, because this will become a perpetual motion. Okay. Fair enough. I don't want to continue this. I know. Okay. All right. I'll move on.

So we talk about, you know, this notion of, of when we look at something, the black hole singularity gets all the media attention, but it's actually the stretched horizon that betwixes you. Talk more about why, what was that like? First of all, Lenny, because I'll never get to do this. What does it feel like to make a discovery like that? On a personal level, let's get personal. Don't, you know, I don't, I can understand the mathematics.

But what does it feel like to make a discovery like that? and why is it so much more important or as important as the singularity, which gets everybody's attention? I made a number of discoveries in my career. Probably the first one was the discovery of string theory. Okay. And it's probably the most famous one in the sense. Well, it's very exhilarating.

It's also nerve-wracking because you're hoping very much that nobody else out there has made the discovery and that you're alone, that you're the one who has discovered it first, and you don't know that for sure. Somebody might be right behind you or right in front of you. Very much that happened exactly with string theory with me. I discovered shortly afterwards after this enormous exhilarating feeling of having discovered something that nobody else knows,

that somebody else did know it. Nembu, the great physicist, Nembu, had written at just exactly the same time, maybe within a day, discovered exactly the same thing. And so that was a bit of a letdown. On the other hand, at the same time, I felt, wow, I had done something that the great Mambo had done. And so, yeah, it's nerve-wracking. It's exhilarating.

You want to get it out as fast as you can because you don't want to be late with it. You don't want to get scooped. And that's the way it feels. So maybe we will get you on Twitter, Lenny. No, you won't. You won't get scooped ever. No, you won't. Now, the stretched horizon is as fascinating as a singularity.

The idea that the, first of all, there was an old idea, a very nice idea, that was due. I'm trying to remember exactly. It was a French relativist. and I know him quite well and I can't remember his name off the name. Oh, Thibbe de Moor. Thibodomor and followed by Kip Thorne and other people who are general relativists

had put forward this idea of, they called it a stretched horizon. It wasn't me. But they had a slightly different meaning. They had, the stretched horizon was something that could sit outside the horizon, but it wasn't physical. It was just an arbitrary mathematical surface

that you put around the black hole, which was just there for mathematical bookkeeping reasons. And they had worked out a whole theory of the behavior of black holes based on this stretched horizon idea. What I think my contribution was to say, yes, if the stretched horizon is real, it's a real place just above the horizon of a black hole where quantum mechanics becomes truly important,

where the temperature of a thermometer that you would lower down into the black hole would become enormously large, that there is a genuine real place just above the horizon of the black hole in which all the information that falls onto the black hole resides, where it sits there, it boils and eventually boils off little bits that we call, Hawking radiation, that was, that in itself was not really a new, it really wasn't a new discovery. And what was, the new idea was that could coexist with the idea that somebody who falls

through the horizon will not see that. Somebody doing measurements from above the horizon, let's say in an orbit, an orbiting space station around the black hole, can send down. probes, long wires with thermometers attached to them, pull them back up and get records of what they saw, they would discover this stretched horizon, extremely hot, extremely complex degrees of freedom, and at the same time, somebody who just fell into the black hole would not see any such thing. This was called black hole complementarity, complementarity of two descriptions. And that was It was that which was really the revolutionary radical idea.

What would happen? One of my guests is, one of my members in the chat room subscribers is asking, what would happen if you performed a bell test of kind of Bell's inequality test near the horizon? What would change about violation of Bell's inequalities, if anything? Nothing. There's various things you could do. You could sit outside the horizon and do a Bell experiment on two electrons. outside the horizon, both of them outside the horizon.

And in that case, nothing. It would just be the same as doing it anywhere else. More interesting, the possibility is you drop one electron into the black hole and the other one you leave on the outside. And then you can ask, can you do a bell experiment in which the two things which are entangled are the electron on the outside and the entire black hole? And the answer is yes.

in principle, you could do a Bell experiment in which one of the subsystems was the electron, and the other subsystem was the black hole which had absorbed the electron. So, yeah, Bell inequality experiments in principle would work, whether they were done either way. So, however, I would have to say, I would have to say that Stephen Hawking, would have denied that. How so? Oh, he would have said that the electron, which fell into the black hole, all of its information, its quantum information was lost.

And so the one which remained outside would not remain entangled with anything. Ah, okay. So he would deny this, yeah, complementarity. In the end, he conceded. I love the story in the book that you're right. In the middle of this very serious, I mean, it's a popular song, book, Lenny's personality comes across, but all of a sudden there's a story of this medieval kingdom and the narrator, I listen to the audio version as well as reading it. He's got this

magical voice about these polywags and blah. I want to recommend it. It's not just for nerds like me. It's for geeks and dweeps everywhere. Getting a very technical question. I know you're still in your pajamas, Lenny. The very technical question. You might need your whiteboard for this one. What are your hobbies outside of physics? I don't have any anymore. You know, I can't run anymore. I ain't do athletics anymore. I'm too old for that. I read a lot. I read and I read for fun. What do you read? Whatever my wife tells me is good. So nonfiction, fiction, so she you're not going to be reading losing the Nobel Prize. Mostly fiction. Mostly fiction. But I do intend, I do intend the next thing

I will read or that my wife will have me read. A lot of my reading is to read to my wife, not because she can't read. She can read perfectly well, but we do enjoy reading together. Right now we're reading a sort of adventure book called The Eyes of Venice by an Italian author whose name I can't remember. It's quite good. But I suspect the next thing we'll probably read when we finish this thing is Barack Obama's new book. His fourth memoir. I hope to someday be worthy of writing at least three memoirs. He writes well.

He writes well enough. He writes well enough, and this is hard. He writes well enough that it's fun to read out loud to each other. I love the audiobook versions of his books. He's one non-science guest that I'm trying to book on The Into the Impossible Show after you, Lenny. So let's get back to some of the stuff you brought up. You are recognized because Wikipedia, the repository of all wisdom and knowledge of humanity, says that you are one of the fathers, if not the father of string theory.

Of course, we talked about the inaccessibility or lack thereof. of testing the existence of a singularity or maybe an alternative to the Big Bang. I want to ask you, on what grounds should a theory be apprised? Your friend, Murray Galman, used to say you should have a rubric, a metric that counts how many correct predictions a theory makes and subtract the number of incorrect predictions. And that should be on every theorist forehead should be a mark of this metric. What happens? I mean, I'm not a pauperist. I don't believe in this demarcation that A paparazzi. What's that?

A paparazzi. That's right. So the paparazzi theorem, just for those that may not know, is that only something that can be falsified counts as true science. And I wonder, in my opinion, that's always stemmed from, you know, Freud had penis envy, you know, that some people had penis envy. I think that physicists have mathematician envy because a mathematician can prove what is not provable or can show via girdle what are the limits of a computational system or a mathematical system.

But in the limit in math and physics, we don't have such a thing. So what should we use, and instead, to gauge whether or not I should send my, you know, my son, our daughter on an adventure and string theory, for example. Well, okay, so basically Murray was right. Of course, Murray was right. Murray was always right. If you didn't believe him, just ask him. It's funny you say that because Roger used to say, it doesn't matter if you disagree or agree with Hawking. You're on his side because he would take the same side, different sides of the same position.

Go on, sorry. So, Murray was right. You know, the business is to make predictions and to test them out. and see if they work, and if your theory agrees with the predictions, then it's good. If it doesn't, that's bad. The problem is that it's in the nature of the subject that the easy things get done first. The things which take the shortest amount of time to experimentally verify are the things which will be done first.

That's almost a tautology, that you do the things first that you can do. Things have gotten harder. Experiments get harder. Now, to test physics at the scale of 10 to the minus 17 centimeters, it takes basically a scientific lifetime to build a giant accelerator, to build the giant detectors and so forth. And that's just scratching the surface. The things that we're interested in are far more remote than that.

So I think it's sort of unfair to use the same criteria that we would use in the old days where Faraday could test his electromagnetic ideas on his bench in his laboratory in 1850 or whenever it was. You can't use the same for those kind of questions. However, as far as string theory goes, remember, string theory initially was a theory of protons and neutrons and mesons. There it has been tested, and it's been tested successfully. It's been tested successfully. There are no predictions of string theory which didn't conform to what we know about hadrons and we know that they behave like strings. There is no doubt about that at all. It's when it's translated into a theory of gravity and very, very distant physics that there are still some basic predictions. One of the basic predictions is the existence of gravity. But I would say that it's going to take a time. It's going to take a lot of effort.

And it is not something that's going to happen overnight. I don't know how long it's going to take. It may take 500 years before we have experimental direct proof. My guess is long before that, we will understand enough theory, enough theory to be quite convinced that is a likely description of elementary particles, that's a likely description of cosmology. But the actual value of it at the present time is different than that. The actual value of it is the precise version of string theory is highly consistent mathematical structure

that contains both gravitation and quantum mechanics, and is an existence proof that quantum mechanics and gravity can fit together consistently, that they can and do fit together consistently. That's not a small accomplishment. Right. It absolutely is. It's obviously tremendous accomplishment. And it's so successful that so many people have, I don't want to say, you know, attacked it,

but many people are now saying, you know, it's been 40, 50 years since an original idea L-I string theory came out. A whole two or three generations of theoretical physicists have spent time on it. There's no evidence for supersymmetry as yet found at the LHC. What do you do or what do you say? Because I never have seen you, I've seen you as the most optimistic pessimist that I know. I think you are optimistic in some ways,

but mostly you're a realist and you're thinking, you know, you're advising a young Lenny and going, going, you know, back to graduate school. Would it be in something like this or would it be in technology? What would you advise somebody before we turn to the question of the necessity of theories of everything in general? What would you advise young Leonard as the TV show?

First of all, I'm not in the business of giving advice. And I get at least 25 emails a week or more people asking me for advice, how to become a great physicist or how to convince my parents I ought to be a physicist or whatnot. And for the most part, I tend to try to answer some of them. all of it. Look, I can't give you advice. I don't know what to tell you. But if I, you know, what I would, what the advice I would have given myself, which would have been good advice for me, is just follow your curiosity. Go where your curiosity leads you. Pay no attention to what people are saying is or is not good science. Pay no attention to the poppers and the

and whoever else, I won't mention names, who tried to tell you what good science is. If you are curious and you want to understand something, follow your nose and go where your curiosity leads. That's the only thing I can say. I would say that to myself, and I think I would probably say it to my students. And more than that, I would think that all of the very, very good

theoretical physicists that I know have done exactly that. Your summer starts now with Memorial Day deals at the Home Depot. It's time to fire up summer cookouts with the next grill for burner gas grill on special buy for only $199. And entertain all season with the Hampton Bay West Grove seven-piece outdoor dining set for only $499. This Memorial Day get low prices guaranteed at the Home Depot. While supplies last, price invalid May 14th or May 27th, U.S. only exclusions apply. See Home Depot.com slash price match for details. And what do you make of this proliferation of new theories of everything that attempt to maybe reconcile different approaches to the issue of unification of gravity with the other three lower energetic forces?

We have geometric unity proposed by Eric Weinstein. We have this E8 Monster Group, exceptional group by Garrett Lisi. we have Stephen Wolfram, who's been on the show as well, discussing his physics project. Why are there so many theories of everything? Shouldn't there be only one? Well, I don't know that it should only be one. I mean, there is some reality out there, and there may be many, there may be more than one description of it.

Of course, those descriptions will have to be equivalent, but they may look different. You know, there are many versions of classical mechanics. They are all consistent with each other. There's F equals M.A. There's Lagrangians and Hamiltonians and Pason brackets, and they all look different. But they are all equivalent. So that there should only be one,

and one may find, one may find that these different things that are being proposed all do wind up being in some way identical descriptions. However, the particular ones that you've mentioned, either I don't know much about because I haven't read about them, or I think they are probably silly. Right.

Or both. Now, could it be that I'm wrong? Well, of course. Yeah, there's no limit to even great minds. Even Einstein was wrong reputedly, and I want to go there next. So regardless of what you feel about Stephen, about Roger Penrose's, conformal cyclic cosmology that violates the second law. thermodynamics. He's written a book about that. I have it over here. Cycles of time. In the end,

it seems destined that the universe in any case will be dying of a different type of entropic death, the heat death. What will be left in your mind? What is the most likely end game for the universe? Just an infinite, tenuous void of black holes, forever emitting hawking radio. What do you see as the ultimate long game? And please, everybody out there, keep paying your taxes, because this is going long into the future. The thing that I find most interesting, to say it's convincing, I think is too strong, but the thing that I find most interesting is this idea of eternal inflation of Andre Linday and other people who, their picture of what happens with the universe is it does tend to recycle itself, but not in the same way that, not in the deterministic way that,

Roger imagines, but that fluctuations take place. Flructuations take place. These fluctuations, one version of them are called Coleman de Lucha Instantons, which caused the universe to make transitions to other types of environments. And this just goes on endlessly forever and ever, and constantly renewing itself to some extent. And potentially that might be right. But I think the real, I think I probably should just say, I don't know. I asked you before we began, we began,

is it okay if you ask me a question and I say, I don't know? And you said, yes, it's okay. So, yes, I think I don't know. I don't think anybody knows. There are some things which are just plain inconsistent with the laws of physics as we know it. I think violating the second law of thermodynamics is not a good thing.

But there are a lot of ideas out there. Maybe all of them violate the laws of physics. That would be a good thing, not because I think the laws of physics are violated, but as we discover that they violate the laws of physics, well, we can throw them away. Yeah, so that helps us winnow down the field. Yeah, yeah.

You talk a lot in the cosmic landscape about the multiverse as sort of a really a polemic, all in a good way, argument against this anthropic or fine-tuning. Can you explain why does that bother you? Because I feel like the anthropic principle in some sense, your colleague, Andre Linday, who I know. Wait, I'm an advocate of the anthropic question. No, no, I'm sorry. But, right. So people like Andre Linday will use that and say, he's been quoted as saying things like, why should there be only one universe?

In other words, that it's almost more natural in his mind. And he says almost that he has faith that there should be other universes. What do you make of that? Andre is an incredibly brilliant physicist. He also has a bit of a spiritual side to it. It's not a religious. It's not a conventional religious side. But I don't know quite if the word is.

spiritual or idealistic and so forth. My interest in the anthropic idea in the multiverse is much more hard-nosed than that. There are three things which would push me in that direction. Let's see if I can remember them. The first is that the universe is known to be very, very much bigger than the part we can see. That's from the flatness of the universe. It's like the Earth. We know it's very, very big because it looks very flat.

If we're standing in the middle of a field someplace and we look out, all we can see is a mile in every direction. We could say, oh, the Earth may be no bigger than a mile in every direction. But no, no, no, that's not right. It's so damn flat that it must be much bigger than that. Same with the universe. So we know it's enormously big. We know this fact about the cosmological constant.

It's absurdly small and it appears to be very, very fine-tuned. Okay. And we know that these eternal, the inflationary idea works very well. We know those three things. And they tend to lead the equations themselves of trying to combine those things together. Oh, we know something else. We also know that this is a string theory fact. The string theory facts are not as reliable as other things. Why? Because it may not be the right physics. But it seems to produce a vast, vast, number of different solutions of its own equations, meaning a vast, vast number of different varieties of possibilities. If you take all those things together, the fine-tuning of the cosmological constant, the fact that inflation made the universe enormously big way, way beyond what we can see, and the large number of possibilities inherent in string theory, it's kind of natural to say maybe the universe is much bigger and more diverse than the region we can see.

It's natural, it fits with the equations. Once we accept that, that it's much, much bigger and more diverse than we can see, then it becomes natural to say, well, why is the universe like it is? It's like it is because we live in the kind of region that will support life. we don't ask that, why don't we ask the same question and get all exercised about the anthropic principle when it comes to living on the surface of the earth?

Why do we live on the surface of the earth? The earth is very fine-tuned. It happens to be in a very narrow range of temperatures and environment. What's going on there? Why is it so fine-tuned? Well, the stupid answer is that if it weren't so fine-tuned, we wouldn't be here to ask the question. So I find that more or less convincing of a convincingly logical line of reasoning. The people who dismiss it tend to dismiss it on what I think of as not scientific grounds.

One of my friends will tell you, and it's a good friend, will tell you that's a bad idea because it will encourage the young people not to ask for other solutions of the problem. Now, that's not a scientific answer. That's a cultural sort of political answer. And I don't know a good scientific argument against the multiverse entropic idea. I think Paul Steinhart would argue if you were on the call that it's sort of the end of the scientific method. Since I remember when we participated, I participated in the Bicep 2 announcement. See, that's not a scientific argument.

That's a political and a cultural argument. It's the end of them. Blasolony. How do we know how science is? Well, let me give you an example, Lenny. So what happened was with Bicep, we made the announcement. There was a video at Stanford with Andre and my friend Chowlin Quo is your colleague there. And then there was a press conference at Harvard.

And then the same day, I had reports of people from the Discovery Institute, which is not the Discovery Channel. This is a pro-religion, mostly Christian site, saying, this proves God exists because it's inexplicable otherwise. And then I had Lawrence Krause, on the other hand, saying also certain Nobel prizes await because this removes the need for supernatural shenanigans. So that you can have both sides. And furthermore, when we said, when we made the announcement, it wasn't clear exactly what the level of tensors to scalar ratio was. You know, there's always some uncertainty. But there was no single model that could predict it.

And this brings me back to the landscape that you've really popularized. And I think it's very healthy to discuss these things. So one thing that's always confused me, if I change the vacuum energy level, the vacuum VEV level in our region of the universe by 0.1 electron volts, that doesn't change the law of universal gravitation, it doesn't change the speed of light, et cetera. Why is it that just the mere existence of the landscape with 10 to the 500 different vacuum states? Why does that mean that we have different laws of physics? I could see different constants, but why would the laws of physics depend on the VE in a particular corner of the multiverse? That, of course, is an

of what you mean by the laws of physics. The laws of physics, as we know them, okay, what are the laws of physics on the surface of the earth? One of the laws of physics is if you drop something from a height, it will accelerate, what is it, the sixth of the acceleration? 9.8 meters per second square. Yeah, 9.8 meters per second. That's a constant of nature. At least it's a constant of nature. At least it's a constant of on the surface of the Earth. But it's also an environmentally conditioned. It's true for the Earth, but it's not true for other places.

So I don't think people would say that the laws of physics are different on the Earth than they are on the Moon because the acceleration of gravity is different. But until we learn what those laws of physics are, which are universal between the Earth and the Moon, We have no choice but to say things are different and the constants of nature on the earth are different than the constants of nature on a moon. It's more or less the same thing. Until we learn what those deeper and overriding rules are that govern everything, all we can say in this multiverse picture is that the constants of nature that we normally call the constants of nature, that we normally call the constants of nature.

are different in this region from that region. Nobody wants the laws of physics themselves, the full set of laws of physics, to depend on where you are. And in fact, I would say it differently. I would say, I think the vision is that it's not the laws of physics that are different in the different places. It's the solution to those laws of physics, not the equations themselves, but the solutions of those equations.

The solutions might consist of a collection of constants, or collection of numbers, there could be one thing, could be another thing, but happen to be this particular thing in our neighborhood. So if you mean by the laws of physics, the deep final laws of physics that we don't know yet, I think everybody would like Andre as well as everybody else who advocates this idea, is that those laws should be one set of law. You said this place was steps from the water. We just haven't found the steps yet. How much did we save? Enough. Enough to get lost.

Or you could book a stay with Hilton. Welcome to your oceanfront room. Just steps from the water. The Hilton sale is on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you stay.

Hilton, for the stay. Yeah, I would think that would be most elegant and parsimonious. Do you have a few more minutes, Lenny, for a few final questions? A few more. Yeah. So some questions from the audience that are wondering in the context of, this is, again, about younger generation. So I want to say, oh, somebody's asking about the fascination with life outside of the earth. Why is it that we spend billions of dollars to look for signatures of water on Mars or whatever? What do you think about the human curiosity? or what have you, impels us to spend so much more on that than, say, on fundamental particle physics.

Is it obvious? I mean, particles are very remote things. They're too tiny to see, too tiny to touch. It just, am I more curious about particles, which are, after all, very boring. Particles don't have very much associated with them. They have a mass and a spin. That's about it. And a charge. And a charge. And they have a few parameters. They're commodities.

You can't talk to them. You can't. Am I more curious about them than I are about whether there is life in the universe? I would say it's a different kind of curiosity. One, I as a physicist, am very interested in fundamental particles because, I think they may lead to something deeper than themselves. They may lead to an understanding which is much deeper than themselves, but it's very hard to get at.

But I, as a human being, as an ordinary human being, I'm terribly curious about whether there are, whether there's life out there, whether I could communicate with it, and so forth. So I find it very easy to understand why people as a whole would be more interested in life out there, than they would be in these exceedingly dull objects, which are truly stupid. They have no consciousness.

They're dull. They're only interesting in so far as they could ultimately lead to something much deeper than themselves. Someone's asking me your opinions about the simulation hypothesis. And again, it's okay if you don't know or want to comment on it. I don't know. The simulation hypothesis means what, that we live in a computer? Yeah, that you're basically you're being simulated,

I'm being simulated, because AI is going to increase so rapidly and according to Nick Bolstrom and others, that the overwhelming likelihood of life is that it's all artificial, as Max Tagmark wrote about in Life 3.0. Okay, I don't know what it means to say. We certainly live in a world

where there are laws of physics which predict how systems evolve. They have laws. The world has laws. Those laws could be thought of, is a computer program, if you like, or is analogous to a computer program. Computer program that tells you what happens next, a quantum computer that tells you if the state of the universe, if the state of the computer is such and such, in the next instance,

it will be such and such. But we do seem to live in a world with laws. The laws could be thought of as algorithms for updating what happens next. I think the real question is, not whether we live in such a world, or whether there's an algorithmic sense of what happens next, but whether it was put in place with a purpose. Is there an intelligence? Is there a computer programmer, an intelligence who created it for a purpose? That I haven't got the vaguest idea.

Was the world created by an agency, an intelligence, or something that was trying to do a computation? I personally think not, but but it seems to me could be. One of my subscribers is asking a question. I don't fully understand that Patrick is asking about the holodeck or holographic. I think he means a holographic universe principle. Was that

startling to discover or come upon or invent? First of all, do you believe that physics, theoretical physics, is invented or discovered? Just yes, one word answer. You don't have to go into a deep. Well, I think it's a combination of both. That's exactly what Jim Simon says. Yeah, it's a combination of both. The ways of describing and thinking about an objective fact might be somewhat variable from civilization to civilization. They may all be equivalent, and there may be some inventiveness in describing a way of thinking about things.

The way mathematics is described that the equal sign, for example, is two horizontal. dashes one over the other, that's an invention. In fact, even the whole idea of an equal sign on the left on a right is an invention. On the other hand, it's describing something which we think is more objective than just the pretty pictures that we use to describe it. So I think the same is true of physics. Ways of describing things are human inventions, the things that they're describing hopefully or not. So maybe he means that, you know, the holographic universe is connected to this.

Yeah. So, right, so coming to the end here, just a few more final questions from the audience. And then I have a couple of questions. I ask all my guests. And if you'll indulge me and have some forbearance, I will ask you them as well. So what about consciousness?

I had Noam Chomsky on the podcast recently. And I came away, as I have for my discussions with him answer, Roger, basically feeling they don't really know what consciousness is, and they're all kind of speculating this Thomas Nagel essay, you know, the hard problem. It's really harder than maybe string theory to verify or move past. What are your thoughts on consciousness, if any? And I realize you're still in your pajamas, so you may not be fully conscious. People like myself tend to make tremendous fools of themselves when they start to talk about things that they know nothing about thinking that their great expertise that something else qualifies them.

Okay, that being said, that being said, now speculate a way, use your non-subject matter expertise. Yeah. Okay. Of course, I don't know. I don't know how consciousness works. I don't know what it is. It seems to be a thing.

I feel conscious. And so I think it's a thing. But my guess is, this is just a guess. my guess is the way the root to understanding it probably lies in computer science, in building machines which get to be more and more conscious-like and eventually understanding what makes one machine behave conscious like and the other machine not behave conscious like. Of course, we could do that with a human brain, you know,

but we're not going to go into the human brain, dissect it, and pull apart its neurons and so forth. we can't do that. I guess I also think that consciousness is something that we probably can't, just the practicalities of it, we probably can't engineer. Engineering something means building an algorithm intentionally to do that. My guess would be it's so complex and so difficult that the only thing you can do is evolve it,

evolve it the way nature did, but evolve it in a computer. big enough computers, complex enough computers, computers which interact with each other, maybe eventually we will begin to understand through computer science, through AI, and its connection with neuroscience, and its connection with neuroscience, perhaps we will begin to see patterns emerge

in what kind of things exhibit consciousness. That, I would think, is the hope for eventually understanding it. Now that I've made a grand fool of myself, let's... We'll move on. Yeah, actually, none other than Galileo, Galilei, speculated on the nature of thoughts, and Noam Chomsky calls it the Galileo problem.

Speaking of Galileo, he is visiting right now here in La Jolla. Really? Yeah, here he is. I think we need a finger puppet of you, and here's one of Carl Sagan. We'll get one of you, and then we can really stick it to you, Lenny. I want to ask you, What heroes would you most like to meet from that are no longer with us?

Who would you like to have a physics conference with? As I said in the very beginning, one of the most touching and dearing parts of Black Hole War is that it made me nostalgic for the times I could get together with my colleagues and that my young students are missing out. I'm in the congealality of in-person gatherings. If you could have an in-person gathering, who would you invite from the great physicist of your...

Okay, so let me ask, who would I like to have coffee with? There are two particular figures, many, many, but there are two particular figures that have always intrigued me a great deal. One of them is the ancient Greek aristarchus. Aristarchus was way, way, he's not this famous as Aristotle, but he was far more of a greater scientist. He was the greatest scientist of the ancient world by far. He was the one who first figured out, for good reasons, that the heliocentric theory, Copernicus recognized that and quotes him, but he figured out so many brilliant things

that sort of was semi-losted history because his writings disappeared. I would love to talk to Aristarchus and see what he thinks about how things evolved after him. Okay, he might have been a very boring man, who knows. But there is one person that has always, not just fascinated me, but I sort of feel close to, and that's Michael Faraday.

Michael Faraday was, of course, he had this pictorial way of thinking that I find very close to my own way of thinking. Closing your eyes and visualizing, he visualized the lines of flux, magnetic fields, electric fields, but he also had something that I admire tremendously, an ability to explain and a desire to explain, explain to the general public what science was about. I don't know if you've ever read his Christmas lectures.

Yes. His Christmas lectures to the working man, basically, on how electricity and things work. A marvelous, marvelous, expository. And he knew very little formal math, right? Yes, he knew very little formal math. But he had this immense ability to visualize how nature worked. And so Michael Faradie was somebody who has been a hero for me. And maybe that is, Lenny, a segue that will get some resolution to your displeasure or propensity not to give advice.

Maybe the advice is to follow these people or at least learn about them. I feel like if I met a painter, I would say, you want to be a painter? Okay, paint Monet. Paint every piece that Monet and Picasso ever painted. And you'll be pretty good. And that's what you do in the theoretical minimum. which is a wonderful segue, thanks, thinking, I'm hurting myself on the back, by patting myself on the back. The theoretical minimum, I'm recommending that to a very brilliant, he's actually the son of

Eric Weinstein. I'll get into that some other time, but he's a brilliant 15-year-old kid. And my course of education for him and tutoring him someone is that I want him to go through the theoretical minimum and go through those books. I think he'll come out with this wonderful exposure to the foundations. And it's not pure mathematical. There's mathematics, but there's also your love of teaching comes through. And I'm going to to put links to all your great lectures online. I want to finish if you'll indulge me with a little more forbearance, Lenny, three more questions, and then I'll let you go back to bed. So Cumran Vafa is coming on the show next week, as I said. And I'll, I don't know, did you fix any of his faucets or toilets?

No, Cumberland is much younger than me. So he was a little older than me. Yeah, he has this wonderful book called Puzzles to Unlock the Universe. And in it, he talks about his favorite puzzles. And one of them being the icing model, he basically goes through what is the icing model and why it's so interesting and it brings up spontaneous symmetry breaking. I wonder what, do you have a favorite puzzle? Do you have a way of thinking about, you know, things that is purely for maybe amusement, but like solving a puzzle, once you solve it, you want to go back and do it again. The answer must be yes, but they caught me unaware. So go on through the next one because I can't think of a quick answer to that. I think Michelson, the great Michelson said something like

all experimentalists are puzzle solvers because they're just like little kids. They want to go back. and redo the puzzle. And I always point that the physicists are like kids because they love solving puzzles. They're very curious. They don't play well with others. They fight. They're jealous. They have all these petty emotions.

It's interesting. As a young person, I loved solving puzzles. I loved solving, you know, semi-mathematical, logical puzzles and things like that. As I got older, I sort of lost interest in it. And I think that's because everything I did was puzzle solving. And yeah, that's the same reason I don't read much science fiction because, yeah, even though I'm at the Arthur C. Clark Center for Human Imagination, I am a duty bound to do it. Okay, final three questions. I ask all my guests on the end to the Impossible podcast. So there's a concept of what's called an ethical will. And actually, Alfred Nobel, it's actually a Jewish concept.

You know that from your decades of Torah study as a young man. Yeah, right. So it's called a Zava-a. And it comes from Genesis. So we won't get into the, to the theology of it all. But the point is that people leave ethical wills. Actually, Barack Obama has an ethical will. You can find it online. And it's what you'd want to give away to the future, to your imposterity, not material will. So Alfred Nobel all wanted to recognize great inventions and discoveries, but he also did so, wanted to do so for the benefit of all mankind. Is there anything that you would want to leave as an ethical will to your, not only to your biological children, grandchildren, great-grandchildren, but to your ideological children, of which I count myself as a member.

That's a hard question. We're in a situation right now, which is so fraught with lack of ethical standards, and not among everybody, of course, but among some people, I don't have an answer to that. the only thing I can say is if you are if you care at all about the world you've got to speak out that's phenomenal you've got you've got you've got to speak out and you've got to say clearly what you stand for and what you believe in and I know I'm talking about political things and you know as well as I do how fraught things are and how dangerous the world is how And I would want my descendants, both intellectual and biological, to know that I did speak out and that I did oppose what I consider evil tendencies in our society. I think you know what I'm talking about.

I don't have to spell it out. Fair enough. But, you know, I don't think. I hate to break it to you, but you have many, many biblical notions because that's the actual question. quote is Zedek, Zedek, Tierdo, you shall pursue justice, justice with all your mind. Well, yes. That's really what you're saying. And you've spoken about that on many occasions.

And I, you know, I think one of the great traits that you exhibit will get to in the question after this one, and that's your courage. But before we get there, you've seen the movie 2001 of Space Odyssey, I hope. I did it. I could not figure it out, but I enjoyed it. So there's a lot of mysterious, baffling things in that movie, including these weird ominous monoliths, these black objects placed on the savannah. of Africa later on the surface of the moon. And I think of them as time capsules meant to be found

when humanity is mature enough to appreciate the lessons encapsulated within this billion-year-old time capsule. What would Leonard Susskin put on a time capsule guaranteed to last for a billion years? It's something easier. What would I think of? It's the last two questions. You can't say, I don't know until the final three questions. It's my only rule. Well, the answer is I haven't thought of it. And that's a big, big question. It's a big, big question and requires thought that I haven't thought about it. That's what I would answer. You don't have a favorite equation or discovery of yours, that you string theory, the foundational equations of string theory? Well, the foundational

equations of string theory won't mean anything to a civilization which has lost its knowledge of Newton's equations. So there'll be no point in that. If a thousand years or 10,000 or 20,000 years, a civilization goes through some upheavals and manages to lose a large amount of the knowledge that it now has, what would I want it to remember so they could get started again? Not necessarily as Feynman said, you know, he was asked a similar question. He said that the world is made of atoms, which are indivisible. You know, what fact of physics have you do you find most kind of worthy of preservation? Not to reboot society 2.0, but more most remarkable discovery that the human mind has,

come up with or discovered. I am very partial to the second law of thermodynamics. Very partial to it. Beyond that, quantum entanglement. How about that? Quantum entanglement. Fair enough. And actually, that dovetails nicely to your fascination with entropy. And the marriage of the two of them, surprisingly,

fascinatingly, at the surface of a black hole, the stretch to horizon a level. Exactly. Last question, Lenny, before I let you go out for your cup of coffee. with your wife. So we've gotten into the future, both in what you'd leave for humanity, kind of as an ethical will, and even discussed what would happen on a time capsule, what you'd put on a time capsule. I want to ask you now going backwards in time.

So Sir Arthur C. Clark had all these famous laws. The first one is any sufficiently advanced technology is indistinguishable from magic. His second law states that for every expert, there's an equal and opposite expert. And his third law is the only way of discovering the limits of the possible is to venture a little way past them into the impossible. And that's how I got the name for this podcast. It's called Into the Impossible for that very reason. What thing about your life mystified you or did you think was impossible? And then thanks to your courage was eminently doable because you had the vision and the intensity to go into the impossible.

Well, I'm not sure it quite answers the question. but there's a quotation that I've always liked and admired because I think it really does reflect things about the way I think. And it's a quotation of the famous detective. You know which detective. Mr. Holmes, I presume. Right. Now, how the hell did it go? When you have eliminated all that is impossible, whatever remains must be the truth. Do you know the precise?

Yes. Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth. So Arthur Conan Doyle. No, that was Sherlock Holmes. Yes. Yeah, I know. No, no, you can't give that to Arthur Conan Doyle. It's Sherlock Holmes.

I'll cite that. His age index is too low. I always felt a lot of my life went that way, that I, my life, I mean my scientific life. that I was up against puzzles, which I didn't understand, and I kept looking for solutions, looking for solutions, looking for solutions. Always in the back of my mind was that one crazy solution that I was afraid of because it was just too unlikely,

but eventually everything else failed and you realized it was all it was left. The holographic principle is a particular example of that. Now, of course, that was not only me. That was also Herodot Tuft, but that I had sensed that long before, but just kept thinking that's too crazy that the world is a kind of hologram.

And just pushing against the problem, in particular, the problem that Stephen Hawking had raised and looking for this solution and that solution. And eventually I realized that's got to be it. There's nothing else left. And so I always admired Sherlock's quote. Did that answer the question? Probably nothing to do with a question.

It did. In fact, it did me better because now I've got another question to ask my future guest. I'm going to ask Shelley that tomorrow, I'm going to say none other than Sir Leonard Suskin. So I want to remind folks that tomorrow I'll have on Shelley. Glashow, please send me questions for him. I've already gotten one from our esteemed guest, Professor Leonard Susskin. In your honor, Leonard, tomorrow is the Leonid Meteor Shower. So we've arranged for that. So when you look up from Northern California, know that I'm thinking about you. And I will send you some meteorites someday, as I do to some of my subscribers to my

newsletter. These are actual meteorites spaced us from 4.2 billion years old. Some collected from the Leonid Meteor Shower in honor of Leonard Susskine. I want to thank you, Leonard. Lenny so much. You've been a wonderful guest and you've been an inspiration and even though you can't remember meeting me, we did meet and I can now say I met a living Lenny legend and I want to thank you so much for going into the impossible and wish you all the best and I hope we'll stay in touch. Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals because we're built for what you're building. Fit for your ambition for Citizens Bank.