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.
What did Steven mean to you personally As a foil, he wasn’t the easiest person to get along with. I I remember hearing that from many people, but, 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. Yeah.
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 say that he was Einstein or Newton, but he was a very, very, very important influence in physics. But, you know, there were other aspects to him that, that certainly caught people’s imagination. His stubbornness against, against over 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 physicists because of his physics. He was a gigantic hero, in a 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, by let me call it his Incredible stubbornness not to recognize the to to my mind, not to recognize the importance of his own work in a sense. It asked an extremely deep question, Really deep question. A question that, that has dominated theoretical physics ever since the, for, you know, 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 Steven very much to realize that His question would lead to something much deeper than what he, 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 is it was hard to communicate with him just because of physically hard to communicate
I remember once seeing him speak at a Royal Society meeting that I had somehow, stolen someone’s invitation to attend. And Steven was there, the guest, and it was, 1996 or so. And someone asked him a question, and this was when he could still move his finger. Yeah. 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 Steven 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, 9 years after its publication. And I wanna ask you. In the intervening 9 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 of your friend and and rival in a 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 well, when did I write that book? 2005, something like that. It is now let’s see if I can do the arithmetic. 15 years later. Mhmm. 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 run another book afterwards. Mhmm. So 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 100 to 1000 citations. This book and your other book, The Cosmic Landscape, I think, that book sold tens of tens and tens of thousands of of copies. What’s the difference when you write a popular a book for a popular audience that has 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.
First of all, I have always gotten a lot of, not just pleasure, but I think more pleasure out of explaining things. I like to explain And there are at least 2 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, 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 know, the, the whole human aspect of, theoretical physics. And I found I found surprisingly to much to my surprise that I had some ability to do it. Yeah.
That’s terrible. 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, you know, having a little bit of a of a maybe it was a, a complex, but maybe it was more of a chip on your shoulder. And I see you as, You know, one of you’re a brawler. You’re you’re one of these tough, you know, New York Jews. I I hate to keep bringing up our our common background, but but the point is, I think you I I characterize you as fearless. I don’t think that you’re, you know, infallible, but I feel like you’re fearless. And I wonder if that modest Upbringing you had with with parent your parents didn’t go to college. Right?
No. No. No. My father got through the 5th 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 thought I was an imposter because I felt I wasn’t Talented. But, you know, I came from this very working class background. My 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 the Harvard, what should I call it, patina. It was full of working class kids like myself. We didn’t live on campus. We, we took the subway to school.
So so When I finally got to graduate school, I felt very out of place. People were extremely kind to me at the at 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, that I didn’t come from and, felt awkward in it. And I I 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 were to me. So yeah. And I think that lasted a long, long time.
And I felt like an outsider until I suddenly discovered I was the ultimate insider on the subject.
How do you mean the ultimate insider? I mean
Well, I began to discover It’s gathered at half the population of theoretical physics have 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
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 use that predicament. Yeah. Very likely, my own sense of I won’t say inadequacy. I I didn’t feel inadequate. My own sense of, discomfort, probably, to some extent, May have led me to to be more independent, more, and to push harder on Ideas, maybe I just wanted to succeed because, because I did have this feeling of, outsideness. So I I would say just whatever your whatever your, What’s the right word? Whatever your sense of not belonging, whatever it is, use it. You probably can’t get rid of it that easily. Find a way to use it.
And, to what do you what do you trip 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 as talented, as curious? What what is the test? What’s the metric that someone can use to keep encouraging them to go on?
Big big cosmology.
Raised Jewish.
I mean, are you were raised Jewish, but you weren’t, you’re not a believer now. So what was your Well, no.
No. Wait. I wasn’t raised religious.
Yeah.
Be be be careful. I mean, you know, I was I was raised quite Jewish out of a Different tradition. The tradition was Jewish leftism. Leftism, coming, from before before there was the Soviet Union. My Parent my parents my my parents my grandparents came out of Eastern Europe at the time of the czar, 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 the that’s what I grew up in, but it was very Jewish.
What it wasn’t was religious.
Mhmm. And when you meet people, As you talk about in the book ranging from Feynman to, 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, and so forth. You talk a little bit about being disappointed recently, you know, that maybe he didn’t Taken 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. Mhmm. But, but that, you know, poster, 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 Steven was this mercurial figure, and and I I wonder you know, you 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 Yeah. From our colleagues. And I wonder, you know, if we’ve lost that. I mean, you’re you’re, you know, closer to to, you know, to, you know, the the the The interaction with Steven than I ever was. I just met 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 Battle is 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 the war over not only I don’t mean the black hole war. I mean, was around much nastier war Over whether string theory is, is a contribution to science or a, or a contribution to anti science that takes based on the blogosphere. And I I do, from time to time, read some of it, I think is very, very destructive. How is it disrupt it it’s foolish.
It’s silly. Largely, the people don’t know what the hell we’re talking about. And especially if you read the commentary that comes after the, the things that the blogist says, they can be in basilic. They can truly be imbecilic, but what does it do? What is its net effect? I think it adds to the, to the sense that you can’t trust scientists. Now scientists are not always right. They’re but they do try. There’s very, very little in in my experience, there is very, very little dishonesty in the science that I think I, am involved in. Maybe no dishonesty or no.
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.
He could manage the baseball team, and so I think science requires a whole bunch of of different skill sets on the theory side. But I guess all of them involve, you know, being able to, work abstractly and having command of the mathematics Today, I like to tell classes that the history in the history of science, was you may push back on this, Mathematics has always been the pacing item pacing item, and I can make a pretty good case about that that, you know, we had the Greeks And, oh my god, nothing happened, and then Euclid invented geometry. And, algebra helped. The Arabs invented algebra, and then Newton came along and invented calculus. And you can you can see where our understanding of the universe Jumped non Euclidean geometry. Einstein came along. It was so abstract that, people have a hard time believing this. Einstein was not a very good mathematician and he had his hired hand, Marcel
And, the
the calculus 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.
My thumb is very busy right now holding up good old Albert, but if yours is free, please go ahead and hit that like button, And don’t forget to subscribe. It really helps us with the algorithm. I know you share you know, Paul Steinhardt, my friend at, Princeton University, feels the same way, and he actually feels it’s even more invidious Then as you recount because as you know, sometimes you have tentative ideas as I’m an experiment I’m just a simple experimentalist closer to a plumber, than you ever are nowadays.
Well, okay. That’s such a misconception. But
I’m just kidding. You know, Jim Simons once told me a joke about plumbers. He said he had a 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 and the plumber and Jim Simon said, what are you talking about? $800. You’re only here for 15 minutes. You know, I I don’t make even I am a hedge fund manager. I don’t make $32100 an hour.
He does.
And then the but, no, then the plumber says, you make $32100 an hour? That’s what I used to make when I was a hedge fund manager. But getting back to it, what Paul Steiner would say is that sometimes you have these tentative ideas as a theorist. Again, I’m relying on 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 assume you’re giving a talk and someone takes a picture, post it online, and and then you can be ridiculed. So I agree. I think it is very pernicious. And I wonder, you know, if if it’s if it’s irreversible, is it like a ratchet? It’s not gonna go back.
What do you think?
Things come and go, and I don’t know that that’s something I can’t predict. And since I’m not particularly a social media person, I I probably see less of it than most people. But I do see some of it, and it it irritates me to no end. Yeah. It probably won’t go away. Now it has very little effect on the physicists themselves and 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 I I look at it. I’m always amused when someone says trust scientist. I don’t know a scientist who just trust scientists without Yeah. 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 the science as well.
That’s 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, the Nobel Prize to Andreas Ghez and to, Reinhard Genzel for the discovery of a compact object. They one other way not to say it was a black hole, but a 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 2 things. First of all, the ability of the human mind to have even created the I not they didn’t create the idea, absorbed the idea, understood the idea.
The whole idea that, 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, and 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 in it. 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, Have conceived and, built the machines and the, the apparatuses, which was so subtle and so fine that they were able to see something so hard that we 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 triumphal experimental science.
Yeah. 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, reminder, tomorrow, Shelley Glashow, Cameron Vafa, And John Preskill is coming up. These are all characters in the black hole war, and they’re very much real nonfictional characters.
Please.
I asked all of them. I asked Roger Penrose this I said, you know, part of the citation or part of the recognition that you received is, 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, The snake that eats its tail. Mhmm. We say that we need a singularity because quantum mechanics, you know, is not well understood in the vicinity. Oh, sorry.
Gravity is not understood at the quantum mechanical scale. Everything in the forward direction heads towards the 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 because there could be these 2 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 Ferrett’s life, the existence of a singularity. Do you think they really exist?
About the cosmic singularity at the beginning of of the universe, I don’t know, and I’m somewhat suspicious. I think a singularity in the sense, that in that sense, We simply don’t know. The and the, the singularity inside a black hole, What the what the singularity means is it doesn’t necessarily mean a mathematical singularity. What it means is the place where things get so dense It’s 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 than the it’s certainly not the stretched horizon, which is No.
It’s something that has to do with the horizon. That, that black disc, if you like, is, its size, its properties are the horizon. Now if you could see really clearly, And in in a sense, the, 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 the sound that’s produced by these 2 not the sound, but the, 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 1st opening skirmish between you and Stephen Hawking took place in 1981, Steven, remarkably, I think that was when he was at this Newfield, symposium around the same time with Steinhardt and And, 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, You know, 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. There 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 I understand what you said about mathematics, but the physical existence of it, Would that decrease your credibility? Or
Let’s be very specific. We’re talking about about this oscillating version of, That both Paul Steinhardt and Roger Penrose have advocated. Then there’s god. Why did you violate your own laws of physics? You have violated the 2nd 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 is so improbably low. And 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 I don’t like it. I don’t
like it. Okay. So call God. No.
I’m not talking about it.
Well,
yeah. Don’t you do that, God.
I’m his, Arrogant. I’m his prophet. The Navi the Navi Brian Keating. I wanna say, yes. So it is true that that Paul has this, this Special contrivance. And and, actually, we have debated that, he and I. But Paul’s model, doesn’t depend on, perpetual motion. It depends on
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 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 emotion.
Okay. Fair enough.
I don’t wanna I don’t wanna continue this.
I know. Okay. Alright. I’ll move on. So we talk about, you know, this this notion of, 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 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 on a personal level? Let’s get personal. Don’t you know, I don’t I I I can understand the mathematics, but 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. The, and it’s probably the most famous one in a sense. Well, it’s very exhilarating. It’s also nerve racking, 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.