The Origins Podcast with Lawrence Krauss - Andrei Linde: Inflation, Multiverses, and all that, from Mr. Eternal Inflation

Episode Date: May 14, 2023

Andrei Linde is one of the world’s leading cosmological theorists, and is the father of much of Inflationary Cosmology. After Alan Guth developed the original idea of Inflation, Linde, who had been active in this area while working in Moscow, realized a way to make a workable theory out of it, resolving a major problem, called the ‘Graceful Exit’ problem. After that, he made the striking realization that Inflation is inevitable, even in relatively simple theoretical models, and moreover that Inflation will in general be eternal, spawning an infinite number of ‘pocket universes’, as Guth calls them, over an infinite amount of time. While there is much talk about multiverses in the context of string theory, it is the Inflationary Multiverse that is most well motivated, and is currently the most widely accepted picture of the global structure of space and time at the present moment. Andrei is not only an incredible creative scientist, he is a charming fellow. I have enjoyed my interactions with him since I first met him, about 40 years ago. He is one of a handful of leading Russian scientists who were snapped up by the US after the fall of the Soviet Union. Since arriving in the US he has helped lead a vibrant program in Cosmology and String Theory at Stanford University. I was very excited to finally be able to have a dialogue with Andrei for The Origins Podcast. His teaching schedule precluded doing something each time I had reached out to him in the past, so I felt very fortunate when the stars aligned, or at least his teaching schedule and my recording schedule aligned. What resulted is a fascinating conversation with a remarkable scientist, and a lovely conversationalist. We discussed his own experiences in Russia and then again after emigrating, as well as Inflation, Multiverses, and the state of modern cosmology. I hope you enjoy it as much as I did. As always, an ad-free video version of this podcast is also available to paid Critical Mass subscribers. Your subscriptions support the non-profit Origins Project Foundation, which produces the podcast. The audio version is available free on the Critical Mass site and on all podcast sites, and the video version will also be available on the Origins Project Youtube channel as well. Get full access to Critical Mass at lawrencekrauss.substack.com/subscribe

Hello and welcome to The Origins Podcast. I'm your host, Lawrence Krause. This episode of the podcast is with the groundbreaking and entertaining and charming cosmologist and particle physicist Andre Linday in Stanford University. Andre is one of the leaders and founders or developers of the modern theory of inflation, the best theory for our understanding the beginning of the universe. And we had a comprehensive and delightful discussion of his own background, which is fascinating. Andre grew up in Moscow. His parents were both professors at Moscow State University.

We talked about those experiences growing up from just after the war. He was born in 1948 through the period of the Cold War and through the period of the 80s when he was in the Soviet Union about his experiences developing the theory of inflation, both internally within Russia and interacting with the outside of the world. interacting with the outside world and then and then his experiences since. All of that was woven into a discussion of the theory of inflation and particularly the theory of eternal chaotic inflation and the multiverse. So the podcast and the discussion provides a wealth of information both on the sociology of science and an understanding of modern cosmology. I really hope you'll enjoy it as much as I did and I really thank Andre for taking the time out to to devote such a

comprehensive discussion on his ideas with me. You can watch the whole thing of course without advertisements on our substack site Critical Mass or you can watch it later on on our YouTube channel or you can listen to it anywhere bothered podcast can be listened to. Either way, no matter how you listen to it or watch it, I think you'll find this a fascinating dialogue and I hope you enjoy it with Andre Linde. Thanks. I can't tell you how happy I am that you're here. It's been a long time that I wanted to talk to on the podcast. I've enjoyed talking to you for at least 30 years.

And every time it's fun and I learned something. And I also usually tell me I'm wrong one way or another. So I'm sure that'll happen today. Well, I'm not so sure. And I'm not so done, how do I say, criticizing. I'm little. Oh, maybe you're mellowing as you get older. And I understand it was your seven.

25th birthday recently. Happy birthday. Thank you. You look great. And soon, as I told you when we emailed, I'll soon I'll be in that same decade. And we'll share that. Don't rush. Okay, I'll try and delay it as long as possible.

As should be clear to anyone who knows anything about you. And if not, the people who listen to this, what I've always enjoyed from you is that you are in my mind one of the most imaginative and fun cosmologists I've known in the entire time I've known cosmologists and and and constantly kind of reinventing new ideas which is which is just remarkable often ideas that it takes a lot of other I know in my own case ideas that when I first heard them I went ah and then and then when you think about them they get more and more convincing it's really kind of interesting how the things you have suggested at first because it took a number of cases it took a long time for people to to think they weren't crazy and and what well thanks but that's true for you as well well look I want to as you know this this is an origins podcast and I like to learn about the origins of people and people that I'm interested in and it gives me a chance to ask you questions

which I've never gotten to ask you in all the time I've known you, which is really about your life. So I want to talk about that. And weaving your life history will allow us, I think, to weave in the science, which will be, so I think the two will work together. In many people's cases, I don't think that's the case, but in yours, they go hand in hand. You were born in Moscow in 1948. And I first thought about that. That was just after World War II. And Russia must have been then the Soviet Union in incredible straits after having suffered during the World War II because of the Nazi invasion. Do you remember when you were younger? Did any sense that there were scarcity or do you remember anything?

Or was it just life was normal because as a kid, whatever you grow up with, it seems normal? Well, I do not remember richness, but I also do not remember scarcity. Maybe, you know, kids are less sensitive to it because they don't know what to compare it with. Exactly, yeah. You have fun, even if you're finding sticks or stones in the backyard. You can always make games. But what I hadn't known, and I should have, was that both of your parents were professors of physics. Yeah. My mom studied a cosmic race, and my father was in a radio physicist.

Yeah, radiation physics. They were both at Moscow State University as professors. No, my father was a professor in a different place. Oh. Yeah, a radio technical institute. But my mother was a professor at Moscow State University. We'll get there. Was she a professor when you were a student? Well, yeah, I think that, but I never attended. Never took any courses from her? No. Okay. It was not something which, well, I was eager to know much, except for, I read her book on nuclear physics.

So it was certainly contact, but mostly it was just, intellectual environment, I would say, their friends were coming to our house. Yeah, no, we'll get there. I want to talk about it. I find this fascinating for so many reasons. Not least, so they must have been, if they were professors, were they professors throughout the war? I mean, have you talked to them throughout the war? No. There were students at the beginning of the war. And my father was just taken from Moscow State University and, well, sent somewhere to learn radio physics as an application, whatever. And my mother decided to go fight. So she was actually a military pilot.

She was the chief of staff of the division of night bombers. She was a pilot. Imagine this. Now tell me about me being so scary. No. Okay. Now, it was just a division of women who wanted to prove that they also can fight with Germans. And they decided to do it somehow.

And they organized a division, which was purely women. Okay. So only once during the war, some men. who was supposed to help them with radio or whatever became a part of this division. But a few days later, when they gave him, well, his bra, he disappears. He could have identified as a woman, but we won't get there right now. I don't want to get to that. But they were pretty successful in what they were doing. They were flying only on night, on

very light airplanes. But she was actually a pilot. She was, well, her main, she was flying, but not often. She was the chief of staff of the division. Because she was from the university, they decided that we must use her

like an intellectual force, and that's how it was. And after the war, she had written a book about this, and whatever, yeah. But did she have, a pilot's license? Did she ever fly afterwards or no? I don't know whether they had a license for that, but surely she was flying years. Wow. But she never took you up in the air in the air afterwards when you were younger.

Well, no, she didn't. Now, but still, this begs a whole bunch of questions, not only that just that she was in this amazing regiment, but she must to study physics. How, maybe was it in, in the Soviet Union, it wasn't that unusual for women, to study science back then or was she very unique? Well, I do not know statistics of that time, but I know lots of her women friends who studied with her. Only one or two, which were not her friends at that time, left Moscow University at the beginning of the war and went to front. But there are quite a few people whom I've seen later. In fact, they were studying physics in Moscow University in the same year in the similar groups with Andrei Sakharov,

who now you know. So usually when she would say, oh, Andre said so, and sometimes she meant me, sometimes she meant Sachero. Wow, okay. So she went back to school after the world. war but but she was a professor by 19 when you were already born right so she must have no no she became a professor much later because she was a student at the beginning of the war and she was a student when you were born yeah and after that she will uh go to phd and stuff and long story did you yeah there's lots of anyway well well i might ask

some more things but i find this fascinating did you so she was a student same time as Sakharov. Did you ever meet Sakharov? I was visiting him in Gorki when he was in exile. He was part of our Liberty Physical Institute theory in group. Okay. When you were there. Second name, you know, my name is Andrei Dmitrivich, Linda. Dmitrivich, the name of my father, Dimitri. Okay. And he was also Andrea Dmitrivich. Oh. Well, this funny story among, well, somebody from O'Levelino Institute saying that if you go along the corridor of our institute and you see to Andrei Dmitrivich, this means you're drunk. But the reality is that, well, yeah, for authorities of our institute, one, Andre Dmitrich, and I mean, Sakharov was already.

too much. We are trying to help him to survive during this time. Because he was under the pressure and our group, because of that, was under the pressure because we were supposed to, like, for example, if you want to go abroad, okay, you must admit that Sakharov is anti-Sovychic. And okay, what does it mean? This means that the enemy of Soviet Union. And in simple terms, that he isn't enemy of people. And so if you want to go abroad,

oh, okay, so these, I even remember how it was in my case, and that was really ridiculous, but okay, it's a long story. If I wish, if I can tell you about this, eventually

I did not say that. Okay, but it was you know one of the reasons why I decided to go to the US well we'll get there we get I was going to ask about the reasons he decided to go to the US and I mean they were presumably law but I want to I want to get there that's a while away from where we'll start but it must have that's one of the in retrospect you know I actually by the way the first time I visited the Soviet Union believe it or not was 1967 oh in the 50th anniversary of the revolution I was there when I was 13 years old It was like a different world for me. But one thing I learned at the time, and I also learned it even when I was a student and Soviet scientists periodically would come visit when I was at MIT. There were some well-known Soviet scientists who were sufficiently well integrated into the Communist Party that they were allowed to travel frequently,

Fideyev, I think, for example. But I learned then that that, that, the ability of Russians to say whatever was necessary, knowing they didn't believe it. But, you know, knowing that the official line that they were required to adhere to was nonsense, and they just did it, but everyone realized it was nonsense. And I think it depends. Among my friends, nobody did it. Well, you know, the reason I'm thinking about that is that there's a, there are, there's a trend. in universities now, which I've criticized, to require people, to require young faculty and students

to make claims about things like diversity and their adherence to these certain principles that they may or may not agree to, but everyone has to do it to become a member of the faculty. And it reminded me of Russia when it was younger that everyone had to make these claims that Sakharov was an enemy of the state, even though they didn't believe it. But in order to get a position, they had to. Well, I would not compare it yet. Okay, you wouldn't? Okay, it's funny because I have some friends. One of mine is a, she's a Russian, a chemist at USC who was educated in Russia, and she said there's,

she often talks to me about in her mind the similarities, but maybe you don't feel them so much. Well, I mean, I was at the Slavery Physical Institute. It was like a small island. were surrounded by a big institute. So the big institute had a party, committee, whatever. And we were more as a small, well, small. We were quite a large organization, theory division. There was about maybe 30 professors.

But we were able to, okay, I can tell you what Ginsburg said. about that time. And you know, Academic Ginsburg? Of course. Nobel laureate later, he was one of the inventors of theory of superconductivity, and he did not mince words. So when he said, and a long time, well, after already all these times, when Sakharov was left go back to Moscow, et cetera,

he was talking at our, well, professor's meeting, saying something like that. And we went through a difficult time. And during this time, we had a success so that there is no, and then he said something in the Russian, well, swelage, no swelage in our theory division during this time,

which was quite an achievement. Oh, okay. That is. Okay, well, that's great. But before we get to your own time in the Institute, I want to go back in time for you still. With both your parents being scientists, was it assumed that you would be, or what that you'd go into science? I know you were interested in geology. We'll get to there.

But what got you, was it assumed you would be interested in science or did you get interested just simply because of the atmosphere in which you grew up in? Or your reading? Did you ever think of doing anything other than science? or did your parents encourage anything, or did they just encourage you to do whatever you want? I did not think about becoming a scientist. It all started for me quite spontaneous when I was in the fifth grade. I suddenly got interested in geology, and that was it.

What got you interested in geology, though? Oh, well, these precious minerals, travel and everything. I was, well, walking in the wilderness with a big back sack, and to make this more difficult, I put the stones in my backstacks, be stronger, whatever. Oh, interesting. Yeah, so that explains, right? Oh, that's interesting. And so your parents didn't say, oh, don't be a geologist, be a physicist.

They were happy with whatever you did. They never did. Well, they did something which was much more clever. they brought because they were two of them professors they managed to buy a car

and they traveled on this car with me on the backseat from Moscow to of all places to Crimea which was at that time yeah

you can do that okay and this was a very very very long drive so I was in the backseat and they gave me two books. I was at that time just graduated from seventh grade school. And they gave me two books to read.

The first one was about astrophysics. And the second one was special theory of religion. It's a last time. Someone in seventh grade. I kind of isolated, cannot do anything. at all. Yeah. And this is an entertainment.

And when I finished, when we arrived, and it was like a week, when we arrived in Crimea, I felt horrible because, you know, my only climb to fame in my school was already in the fifth grade. I already know my future professional geologist. And now I am not a geologist anymore because this is. so much more interesting, but now I must come to school and say, boys, I'm a traitor. Okay, and so I did. That explains it because I was reading a biography of you, and you said you felt like a traitor

when you decided not to do geology, and I thought, why would you feel like a traitor? Your parents were physicists. Because it's the love of my life, geology. You just, well, yeah, now I understand it. Now, let me, you have a brother. Do you have any, you have a brother as a psychologist? Is that right? Yeah. Is it just the two of you? Yeah. Okay. Was he in the backseat too? No. He was older than you? Or? He was three years younger. He didn't come. Yeah. No, he didn't come. So he might have been a kind of physicist. If he'd been able to read those books too, then maybe. No, it's just, you know, it's selective enjoyment.

Yes, yeah. Now, they kind of knew you would probably enjoy the books. But one thing I was going to ask you, they were probably Russian books, but were any of them books by any scientist, I would know or not? The short book was by Landau and somebody. Oh, by Landau, of course. This was a popular book. Yeah, I didn't realize Landau wrote popular books. That's wonderful. Well, and another one, it was just a popular book. Yeah, yeah. Don't say just a popular book. As you know, I like popular books. I write them. Yeah. No, I think... Because it changes youth. Well, it does what it did for you. I mean, for me, the great joy, the greatest, one of the greatest joys, well, first of all, for me as a young person, it was reading those books that made me want to do science, just like yourself.

But the greatest shrill now is just me grown-up men and women who are a physicist who say they'd read a book of mine when they were, you know, younger, because I'm old enough now like you, that they've tried to become a physicist. Just wait until there you come. Oh, you are still alive. Okay, but anyway, so that's great. And you read a book by Landau. That's wonderful. So that joy of, did they encourage you to read a lot? By the way, I'm often interested. Did you read a lot of books when you were younger or was just a few? I think I was just swallowing the books because I loved it. it was not necessary to encourage me.

I don't know. I don't remember anybody pressing me doing anything, in fact. Well, that's great. Interesting environment because they kind of created an environment where if, well, I maybe, you know, softly doing something which was somewhere in the background. But it was, I never was under the pressure that I must, well, perform, whatever. Well, that's good.

But also, everything I know about me tells you that even if you were under pressure, it would have had no difference whatsoever. That you do what you want to do regardless of the pressure. As far as I can tell, that's one of your characteristics. Maybe I would do otherwise, you know. Yeah. In fact, pressure. In fact, yeah, if you were pressed to do one thing, you might do the other just out of,

just out of obstinacy. if I know you well enough. Now, but you never thought of doing something other than science, like literature or history or anything like that. That was not an interest. Well, there was a period in my life when I enjoyed to paint slightly, okay, but it was not serious. At the moment, I took some lessons for a while from one really good painter.

And when somebody told my parents, oh, your son is going to be a painter, this was the last time I went to this person for a class. So they did have a subtle influence one way or another. Well, it's true. Painters, it's hard to make a living as a painter. Now, when you were young, the last thing I want to talk about that period before he became a geologist, is Stalin was still in power, right? And so do you remember that? At that time, I did not imprint on my memory because it was, well, in the beginning of 50s, he was already out. And at that time, I was not caring who lives outside of my house.

Okay. Okay, I just wondered about that. You were no longer interested in geology and decided to, you wanted to do physics as a traitor. But did you, so you continue to high school. I wonder what high school was like there. Were you allowed to specialize already? I mean, like in England, you can specialize. The United States, you have to take all these courses.

But in high school, did you just focus on physics and science? When I was in the eighth grade, it was not specialized, and it was pretty mediocre. In a ninth grade, there was already like an exam before. before you go to this, it was math-oriented school. Actually, it consists of three different classes, two of them, math and computing. And the third one was mostly girls studying music and art, et cetera. It was really strange combination.

But yeah. So it was excellent. It was an excellent, it was a specialized high school. It was an excellent high school. Yeah. And then so that was your experience and you went to an excellent high school. And you knew already your ability in mathematics. Did you have colleagues? Did you have friends who were interested in science that later became scientists or were you?

In the school I had my friend who later together with me entered Moscow State University, we were studying together with him. But then it's just different people have different, well, I did how exactly what they should follow, and for how long. Okay, yeah. Now you, okay, so you graduated from high school, and you, I was wondering, I don't know about the, I knew about enough in my area about the the different institutes in Russia. But you went to Moscow State University. Was there any choice? Did you decide that was going to where you go because your parents were there or was it the best school or was it just a matter of being nearby or what?

It was the best school. There was a comparable school far away from, well, not far but new Moscow. It was physical technical institute, which was and continued being very, very good. But for me, Moscow University seemed natural. When I was a geologist, I attended some groups of people in geological department coming there. So it was natural for me to go there. Sure, sure, sure. And you're able, at university, you're able to focus right away on physics. You didn't have to take abroad.

Mostly they emphasize of mathematics and everything else to do whatever you want. Yeah, just, okay. so that yeah more like england in that sense that you could focus early on on your interests rather than spread out now this was during i was working out the ages so you've born in nineteen forty eight so you must have entered university around you know probably nineteen sixty four or so or if it's 65 or something like that yeah that was sort of still the height of the cold war and do you remember for example i will i'm just asking because i i don't think i've ever asked anyone I've known from Soviet Union at that time. Do you remember, for example, the Cuban

missile crisis when you're in high school? Was that a big deal? Well, for me, it was my life around, okay, I did not understand what is going on. But what I do remember when I was in Moscow University in 68, when Russians will put the army to Czechoslovakia, this is something which I remembered very well. And it was not very pleasant. Okay. Were you already a sort of a dissident in your mind at that time? Some officer came to give a lecture in our group explaining how necessary it was. Because you know, well, comrades, they have army there, they have tanks, two tanks comrades. So when you hear it once, that is for all your life, you remember it.

Yeah. That was a reason for invasion. They have two tanks. Two tanks. Yeah, no. Well, okay. So already you had that, you already have begun to recognize you're sort of not quite a dissident in that, not a vocal dissident perhaps, but already that you were not buying into the sort of Russian Empire. What happened when I was in school? Because I also liked poetry. I know I was reading about that I used to learn it by heart and well I learned by heart quite a lot

and part of it because a substantial part of it was forbidden okay where did you get it if it was forbidden where did you find it this secret you can tell me now I think you're safe some is that

some is that some means myself Okay, is that means a publishing company. So you just type it on a typewriter and give it to your friend. No, no, but where did you get it so you could type it? Who did you learn it from? Maybe you're afraid to tell me. I typed it on my typewriter and it helped me to memorize it.

No, no, but hold on. What I'm asking you is you had to see it somewhere in order to type it on your typewriter. So if it was forbidden, how did you get it in the first place? but you have a culture of friends. Yeah, so you had other friends who gave it to you, and it was your schoolmates. Yeah, kids will, whatever's forbidden kids will learn how to do. I just wonder. Also, my parents, whatever, as I say, they called Andrei Sakhar of Andrei, okay?

So let's tell you a little, okay. Yeah, okay, well, okay, that's good. But as we'll get to later, that memorizing that poetry turned out to be very useful to you later in life, but we'll get there. I know that fact. But the reason I was interested in your in, in, in, in, in, in, in, in, in, in, in high school, the invasion of Czechoslovakia is, um, it is true that you, I didn't know this till recently that you'd that you were one of a number of Russian, um, sort of expatriates, scientists and other people who, who, who wrote, uh, a public letter, uh, condemning the Russian invasion of, uh, of Ukraine recently, right? Yeah, that's true. Yeah. We don't have to go into that much, but it's interesting to know that.

But presumably, of course, you had to keep all that, as you say, secret because if you, let me ask you another question. If that hadn't been secret, would have it affected your ability to go to Moscow State University? Would have they have kept you out or no? Well, let's express it differently. There were some dissidents who were actually fighting, okay? and there are some people who were just thinking differently, but they were not active like warriors. And for me, at that stage of my career,

doing physics learning, who I am, et cetera, it was the most important thing. Yeah, sure. And also, I had a, well, maybe many of us had this feeling that it is practically impossible to change anything. And then one or two people like Andrei Sakharov come and they would be actively, well, fighting for freedom

and helping other people, et cetera. So the best we could do really not being academicians and three times heroes of Soviet Union, we were able to just help them leave. Like, for example, as I said, when Supper was in exile, people from our Liberty Physical Institute were the only one who officially were allowed to come there.

So each time it was a very, very sad journey. And sometimes with unpredictable consequences, but somehow probably one hand did not know what the other hand was doing, so we did not pay the price, but it was not pleasant. Okay, no. Some people decided not to go. Okay, no, I understand. And, you know, being a distance in your mind, but focusing on physics at the time was the number one thing to do.

I think it's probably true for many, say, at the same time in America, There were many people who were, say, against the Vietnam War, but who were, instead of spending their time protesting, while they were against it, they focused on their studies. And that's not an unusual experience in the late 60s or early 70s. I know one of my friends from England who at that time also, instead of protesting, he had one choice instead of being mobilized, actually. Yeah. He spent one or two years on the South Pole.

Oh, so he could really? So he wouldn't have to go. So now you go there. Pleasure. Yeah. Yeah. Yeah. Okay.

But last bit of Sovietology, maybe. This occurred to me. When I was young, my experience of sort of Soviet dissonance was reading Alexander Solzhenits. Yeah. Did you know of him when you were there? Of course. Yeah. Some is that.

Okay. Okay. The same agency, publishing agency. Okay, now, so people knew of his work and... Yeah, I remember reading it. Yeah, I mean, I remember reading it and impacting my impression of what was going on. Okay, you graduated just in physics or physics and mathematics, or was there that distinction from university? It was physics, yeah.

Okay, and then you went to Lebedev as for a graduate student, right? Again, because that was the best place or why? Because my advisor, while I was in Moscow University, my advisor was David Kierzhniz, who was a professor of physics at Leibald. I see. So he was a professor at Physics at Leibout, but he was your advisor at Moscow State? Yeah. That was possible. Yeah. Well, it was kind of... Moscow University was mainly focused on teaching. There were some decent professors there. But the best ones were in academia.

Okay, so that's right. So there were teachers at university and there were academic had academicians and they were at institutes. That's the way the Soviet institutions is the top. Is the top and they're always at private institute, not private, but separate institutes of research. So they were at research institutes and every now and then they would go and teach at the university. Is that right? Well, Lebelief Institute was a research institute. In our institute there were some admissions. for members of Academy of Sciences. Yes. And some mere mortals, and most of us were in this category. Yeah, but it was active research and almost no, unless you really want to, then you don't teach. You don't have to teach.

It's a nice system. Because it means, first of all, it means the people who are at the university are actually interested in teaching, which is not always the case at universities here. And so it was that, it's a nice separation. if you can afford to do it. It's a lovely life to be in a research institute like there or the Institute for Vance Study in the U.S. where you can focus on research and only teach if you want. But Kershenitz did take students on.

I guess he spent time at, you said, he was your advisor as an undergraduate as well. How did that come about? Well, my mom knew somebody, this somebody knew me. I knew all of them and they told me, well, you know, this other somebody, his name was Eugene Feinberg. He gave a lecture in Polytechnical Institute in Moscow discussing non-local theories like a violation of Florence invariants, which nevertheless happened on micro scale, so maybe you can do something. And I was so excited.

And there was one person in Lebedo Institute who did just exactly that. And I came to him and he was also recommended. And I thought that this is what I'm going to do, some fancy physics. And I learned some also fancy mathematics. So I came with the ideas of my own. And he told me, okay, to start with, let's calculate the cross-section of neutrino on anti-neumatic. neutrino. And I was so disappointed. But, okay, so I calculated it. It was okay, doable. And then he says, now let's calculate it with electromagnetic corrections. So why do I need to do it? Well, in a year

from that, I was already excited because I invented my own method to some diagrams, which was not published at that time. My diploma in Moscow University got some first prize. And, and And after that, when I graduated, I came to Kirjniz. This was January 72. And I expected him to tell me, okay, so now let's publish because this is already good work. I knew that he liked it. And the first thing that he told me when he had seen me was, okay, forget about everything which you just did.

I say, how, okay, let's just publish this first. No, no, forget about this. Here is a peripheral, which describes the paper by Herod Hooft. So now we know how really to calculate this radiative corrections. World is changing. The physics is completely different. So just learn it. And I learned it.

And I am so happy that I bake because, okay, otherwise I would do this stupid thing. All along, that was Kirshnitz who was telling you all this. all you didn't say. So the original one who made you calculate the neutrino anti-nutrino cross-section was Kirshnitz as well? Yeah, but because he knew the difference in quality. And also, he recognized that this theory of electrophic interactions is similar to superconductivity. Yeah, well, let's hold that thought. I know that. And by the way, I should say the first time I heard your name was knowing about the paper of Kirshnitz and Lindays. That's when I first before that was my first introduction to you i should say and i didn't know at the time of course not

too much later and that he was your supervisor but you also wrote somewhere that in 1971 some professor told you not to go into particle physics because it was a dead field that was a kershenits i assume that was someone else i would not name him okay but but he was pretty convincing because he was studying axiomatic quantum field theory Axiomatic field theory. Which was just a sterile, dead end field. But I was learning it was the best at that time. And when we were graduating, this person gave our class of theorists

and advised that we should not go to theoretical physics because the theoretical physics is a dead field. I trust me, I know I study oxymatic field theory, and Hamiltonian is already dead. the best accelerator in the world which we have right now in Dubna. Okay. It is not going to produce much. So it is just a dry field. Don't do something else. But it was already too late for me. I was already in love with it. And I mean, as you say, at 1971, it wasn't such a crazy thing to say because the 1960s had been a very confusing time

and looked like each accelerator produced more particles. It seemed like a complete mess. You can repeat it now. You can repeat it now. It looked smart. Yeah, there wasn't that, well, except the difference between now and then was then there was a lot of data coming out, a lot of data, but none of it was understandable. Now there's less, now all the data is understandable, which is unfortunate because we want some data that we don't understand. But at the difference, but at the time it seemed like no theory was going to work, and it was all just chaos. And it was right before the revolution in particle physics were in a period of three or four years. from you know 1971 and 1975 what is now the standard model a particle physics suddenly

blossomed and from knowing not from understanding nothing we essentially understood almost everything it was kind of an amazing time you remember that when you were that was during your grad during your graduate time i guess right yeah i guess this is one of the reasons why i think my generation was just like this year's was very very lucky because we were coming fresh to the new field which was just emerging and that was magnificent. Yeah, no, yeah, it's the right place at the right time. So you're lucky and it was now, I want to talk later about the difficulty which you experienced of being a Russian, we'll call you Russian rather than Soviet,

being a Russian scientist at a time when it was difficult to publish outside. And therefore, I remember, I mean, we used to say that everything we knew of it also been done in Russia, the Russians would say, We all did it first, but no one knows about it. And it was the standard line we hear from Russian physicists. But it wasn't often true that things had been done first in Russia. We just never learned about it because it was difficult. They couldn't publish, and it would take years before the Russian physics journals were translated into English.

And sometimes this translation was this was the reason, for example, one one of my papers was never known to anybody except for Welkman. I've in 74 I've written a paper explaining that vacuum energy, which is cosmological constant. Yeah. Well, it can be associated with scalar field and the scalar field changes its value if you heat it up. Okay. So then I've written a paper explaining all of this. and Kirjnyi decided not to collaborate, he was very, very honest, and at this time he said, no, it's only yours. I've written a paper, and I gave it a name, which in English translation should be, is the cosmological constant really constant.

But in Russian, it is Postehanoingale, cosmological, Postearnia. And Li means if, okay? It was translated as whether the Lee constant is a constant. Oh. Oh, so the Lee-Con. No one knew what that was. No one read it. Yeah.

Okay. Thanks, I got. We'll talk about it because that affected your life a few times. But I wondered to the other direction. So obviously, you'd heard about this paper by a tuft. So while it was hard to get information out, how did the information come in? Did everyone read in English? And you had access to the English journals or no?

Everybody read English. And you had access to the regular scientific journals like physical reports or physical review. And we have preprints which were arriving with a delay of two months, whatever, but they were arriving. I remember we used to send things to the Lebedavid. So even when I, in the 1980s when I was at Harvard in before that in MIT, yeah, we'd send our preprints to Russia. So you got them and physics letters. So you got the journals when they came out? Yeah.

Okay. But we got them. Now, to move slowly and more into the physics, Kirshnitz was your advisor. You went there in 72, I guess, right, into the Lebedev Institute, which is a great time in physics, as you say. And already, what was then, I mean, even though it had been developed in 1967,

It was only after Herodotouf demonstrated that the theory made sense, in a quantum sense, what we would call were normalizable, that people began to take it seriously. And, well, you looked like you want to say something. So go ahead. Yeah, it's just another interesting thing. When I started paying attention and other people start paying attention, we have found that in our own, institute, there are three persons who studied the same thing like who studied and who obtained a similar result sometimes almost simultaneously, sometimes

earlier. And one of these people was Renata College. Yes, yes. So I decided to learn and I asked their permission when they discussed it. It's College, Fratkin and Tutin. And when they were discussing it, well, in my... idiotic mind because it was above my pay grade, but I wanted to learn. It was very painful. So I was following them like that when they were discussing. And yeah, this was educational.

But tell me the truth. Was it only the physics you were following? Well. I mean, were you motivated as well by, I mean. You know, she was so out of my league. It was just impossible to say. That's lovely to hear. That's a lovely thing to say. And I just remember that when Kyrgyznyz tried to discuss something which we did with him,

and I was in this auditorium when he was there. And Renato was sitting just near me in front. And he said something that, Who is Linda did this? And she asked somebody, and who is Linda? And I guess at this time, I thought, or at least this is how I remember it now. And you know, your memory sometimes cheap you. I thought, oh, maybe your children will be Linda.

Oh, isn't that wonderful? And they were. And then you, and for the public, we not know that you and were not to get married. But I didn't, I have to admit, because I got to know her more from her work later on and related to string theory. But I didn't know that they had basically sort of continued the proof of that a normalizability that the Tuft had done. I didn't realize that she'd done that.

Was she still a student at that time? No, she was like, I don't know how it is in translations. She was like a postdoc. Associated, whatever. Yeah. She and Tutin were actually the first to relate proof of unitality with proof of renormalizability in this theory. And after that, Hooft and Welkman did it in a different way. So there is even a reference to the paper in the paper by Hootten-Welten.

So sometimes there was a contact between us. But we at Lebedev, we didn't know what this guys are doing. doing, they study some crazy young mills fields. Okay. So we were doing real physics, neutrino, anti-neutrinos. Oh, I see. Oh, wow, that's okay. And of course, you know, a Tufton development later won the Nobel Prize for the work they did.

Yeah. And for people who don't know. But you were at the right place at the right time because your supervisor tuned in early on to the ElectraWeak theory, which had been developed by Weinberg and Salam and Glashow and others. this theory that later became a central part of the standard model. And I didn't realize, so he was the first, well, at least, I don't know if he was the first one, but to kind of appreciate this connection between the electro-week theory and superconductivity. Was he the first one to sort of really appreciate that connection?

I think that he was the first, because usually when we were even later, when we were trying to explain what is going on to our, high energy colleagues, they were saying, but where is the temperature in Lagrangean? Yeah. What they are talking about? There is no temperature in Lagrangian. Okay. So that was very hard. Zildewicz, two years later, after we already did it, he was the first from these other group of people who were suddenly very much interested. Zildović, Kozirv, Okun.

So they took it very, very seriously. This is Zeldovich, you say? Zerdovich, yes. Yeah, I guess you pronounce it differently. I mean, for me, Zeldovich seems like a major. I never got to hear him or see him, but he was a major figure. Yeah, he was a major figure. He at some moment, well, suggested me to work on cosmic strings.

At the time when it didn't exist, I calculated something about cosmic strings. And it did not seem interesting for me. And I told him so. And so he had written a paper about it himself. And a lady, it was followed and strongly developed by Alex Wilentkin, who became a champion in that. So it became a big deal later. But, well, instead of that, I was... You did okay.

I think you did okay. Alex did fine too. But this finite, the fact, so let's just for the, for people who aren't aware of this. So the point about the relationship between superconductivity and elect weak week theory is that in superconductivity, in a in a in a in a in a superconductor, electromagnetism is short range. The existence of these things called cooper pairs means that that the electromagnetic field instead of being one over our square just falls off. And it acts like the photon has a mass. And here we have in the Electro-Weak theory, you have electromagnetism, which is long range,

but there's another force where the particles that convey the force have a mass and that force is very short range. So it's only over the size of the nucleus. And so in retrospect, that relation, that analogy seems obvious. But at the time, and the point of superconductivity is superconductivity only happens below a certain temperature. Above a certain temperature, these cooper pairs no form, and electromagnetism is long range. So that phase transition as a function of temperature is natural in condensed matter. But as you say, in field theory, normally, everything's at zero temperature and you don't

think about that. It took a while for people, I imagine including Kershenit's in you and then other people to develop the idea of what's called finite temperature field theory. You want to explain that a little bit? Well, it just quantum field here at final temperature, it was not our invention. We just applied it to the most interesting field to study. Yeah. In fact, it happened to be easier sometimes, or at least for me, because superconductivity is, well, three-dimensional something. It was not Lawrence invariant. Yeah. But I found that sometimes this phase transition,

evaporation, if you wish, over the Higgs field, happens by the first order phase transition. So abruptly, I found it somewhere in 75, whatever. And when I told about this to Kyrnitz, he said, but I think that people do not know that this is possible in superconductivity. And then we learned later that later with some delay, they found also some way of describing first of the phase transitions

while heating in superconductivity using similar methods. But we did it. First, you did a first. Because it's easier. It is, you have a religious theory where, And maybe just, how to say, people use this language already quite a lot. So we have power of the methods which we were able to apply. And for solid state physics, it was not necessary.

It's like quantum mechanics. Yeah, yeah, yeah. No, and okay, so that's interesting that they found that afterwards in superconductivity. But the idea is quite clear that if, look, it makes sense. If you heat up a superconductor and the superconductivity goes away, if you heat up the universe, then maybe the distinction between the weak interaction, which is mediated by heavy particles and the electromagnetism will go away, and the particles will all behave the same, and they won't, and they'll all be long-range forces. That makes sense, but that's the work that Hirschnitz

and you sort of focused on, the fact that at high enough temperature, which meant automatically one is thinking about the early universe without even necessarily calling it the early universe, that at high enough temperature, the electro-week symmetry is restored. And I assume that you guys were the first people to show that. Is that right? Yeah.

And what was interesting for us, there was also later Weinberg and and all of us were thinking that this is at first, that this is the second order phase transition, which means it happens smoothly. So scale field just gradually disappears. And that is what we found with Kyrnitz in summer 75 and tried to publish, but I made a mistake

sending it to a wrong person, criticizing him at that same time. Okay. So it appeared a year later in 76. We found that the phase transition can be first order. And when it happens, the energy of the cosmological conference. constant heats the universe, which is, you understand, this is the basics of inflation. Yeah, absolutely. Well, yeah, in fact, we'll get to that.

But I want to talk for people a little bit who may not understand the difference in first and second order. But before we do that, I was interested that Weinberg was part of the group that had sort of refined, if you want to call it refined and developed a comprehensive picture of doing this finite temperature, field theory calculation and what happens. I mean, I was influenced by Weinberg because what, you know, I learned most, almost all my, I took almost all my courses from Weinberg, even though I was at Harvard. He must have been, he was, he was unlike many people scholarly in his understanding of physics and must have, and knew the connections I would have thought early on to Kinnets matter.

But he, he didn't, early on, he didn't, when he was developing this, he didn't ever discuss the restoration of symmetry? It was only after your work that he did that, is that right? It was after, but nevertheless, he was early. It was 74. His people. Yeah, yeah. Well, he's, I mean, you would imagine he would be one of the people that understand that. But now let's talk about, because this is important for later on, the physics that we want to talk about. So a first order, when you have a, when things change, like in a superconductor, it becomes a superconductor and then and then a and it's not superconducting or a magnet. When you heat up a magnet, it's no longer magnetized.

That's what we call a phase transition to condensed matter physics and now in in all of physics. But so that means something changes. And and the question is, is the change smooth? In which case we call it a second order phase transition, namely does it go from one stage to another very smoothly without a lot of weird things happening? Or is it or something else? happen if it's a first order phase transition can you describe just so people understand what happens during a first order phase transition oh it's very easy you you take your teapot and boil it so this is what happens you have bubbles appearing in water and these bubbles expand expand and eventually all water evaporates so that was the simplest example of the second or the first

of the phase transition it's a formation of bubbles There's two different phases existing at the same time. Very different properties. A bubble and water are very different. Especially if your water is very, very clean. So then it can be superheated. Yeah. Then for a while, you increase temperatures even above 100 Celsius,

and it still does not boil. And then you just drove a little bit of coffee and psh. And it suddenly exactly, boom, yeah. And also, I like to use. the analogy often of not heating but cooling. If you have water on as you would have had in Moscow and I had growing up in Canada, if you have a street and it's well below zero Celsius, if the cars are going, the water gets slashed around and it's still liquid even though it should be frozen. And then when later on at night, when the cars aren't there, it suddenly goes boom and it freezes

and releases some heat at the same time when it, when it freezes because the state it wants to be in is frozen and it's not. And I and and and so there is a part of possibility in the case of these phase transitions to have it super cooled or superheeded where the transition should happen, but because of the, it doesn't, it takes something to make it happen. And of course, we'll get there. And that whole idea is central to inflation. So the first, so the important point is that the theory that we know and love, the theory that we know exists, the Electro Week theory, as you showed, and as we now understand, unless you do something strange to it, when it goes from the state that we live in, to the state

that at early times in the early history of the universe when it was hot, that that transition, or if you want to say it the other way around, the transition from when it's hot to cold is first order in the theory that we know and love. In most cases. It's a bit tricky. In real life, when you come to the point close to the phase transition, then physics sometimes become more complicated than a textbook. So we thought that it is really first-order phase transition, and sometimes it might, but in some other ways, in some other cases, there are some special name for that also coming.

So things may be more complicated. It's dirty science. You need to make not quantum field theory calculation, but do them on lattice or whatever to get the final truth. Yeah, it's very complicated. I mean, that's understanding physics here, the face transition is quite complicated. In Grand Unified theories, you would naturally mostly expect first of the phase transition. Yeah, and that's one of the reasons that to preempt ourselves that the universe didn't inflate when the, when the universe, when the phase transition happened, when the universe was about a millionth of a millionth of a second old, I think is when the electorate week phase transition happened.

when it was pretty old. It was already a millionth of a millionth of a second old. That's pretty old. And it didn't, it didn't accelerate. But there was a phase or I can't resist before we get on. There was a phase transition in your life at the same time as this, because as you pointed out in the seminar, when not to ask who's Lindy, you tried to follow her around and learn what she was doing. But it was two years later and my understanding, and I could because I mentioned it earlier, I think, it's important that I bring it up now, that that ability of yours to learn the Russian poets

by heart when you were a high school student paid off. Do you want to explain how? Well, it just we happened to be, and this was really a coincidence, we happened to be at the same lake at the same time. And then what to do? We were on the boat. And we were on the boat. And I was reading, I came, we came there in my, again, a car of my parents just to come to this place. And I was reading poetry like maybe three days, nonstop by heart, and singing songs. Don't ask me to sing songs now. I'm not going to mind. Okay. So somehow it worked.

It worked. Somehow you convinced her. Somehow you won her heart and she had already won yours. And the rest is history. And you've been happily married ever since. And it's a lovely story. I thought that story of the poetry was worth mentioning in the midst of this physics. Because, well, it not only actually formed a love collaboration and a family collaboration, but later on led to physics collaborations, which is also a nice.

thing and affected your work later on, which we'll get to. But to get to this first-order phase transition, one of the characteristics that happens clearly in boiling water that you notice is that the system is very, as we say, in homogeneous. If you look at it, that's very different in different places where it's where it's vapor and water. I mean, you couldn't imagine a more, forgive me for the word, chaotic situation where, where you have great inhomogeneities. And you would imagine, in fact,

that would not reflect our universe, which seems to be uniform as far as you can see everywhere. And that in homogeneity of a first-order phase transition, in fact, it's surprising. It's recognized immediately in Guinness Matter systems, But very shortly thereafter, a proposal was made to describe our universe by our good friend Alan Gooth, which he called inflation, which relied on a first order phase transition. And one might say in retrospect, one could say, how could that describe our universe

because our universe is smooth and a first order phase transition isn't? And it's kind of remarkable that it persisted. And we'll explain, well, I'll take your take on it in a second. But before we get there, I was there in the United States when Alan was there. In fact, Alan was on my thesis committee when I was at MIT. He was one of the few nice people and encouraged me. But there was a hero or at least a star in Russia that I never heard of named Starabinsky. And what I learned from reading your story,

is that Strabinski had proposed a model that was essentially similar to Al-Agoose, although he didn't emphasize the important physics that made inflation suddenly capture the world. But he was already well-known and his ideas were lauded in the Soviet Union in 1979, which is a year before Goose. So you want to explain that a little bit? We were actually in the same group in Moscow State University learning physics. But he was working with Zildovich and he was very good in studying quantum effects in gravitational field. So at some moment, he issued a paper saying that if you consider many, many, many, many particles giving contribution to vacuum energy or gravitational field, then it's equivalent to changing Einstein, a little bit. And if you take these extra terms into account, you may find the regime of

the disinter expansion of the universe, exponential expansion. And he wanted to use it for solving singularity problems. He actually read, has written in this paper something like we assume that our universe initially is absolutely homogeneous. Okay. And he used it to address the singularity problem. There was a problem with this addressing because it was also clear from this paper and from subsequent paper by Mukhanov and Chibisov that this vacuum state, due to the quantum corrections, is unstable and decays quickly. So you cannot really have the universe living infinitely long until this time because you would die first, okay? So it cannot be an initial state. unless the universe was spontaneously created from nothing.

Okay? Yes, okay. But we both like a universe for nothing. It's been very good to me and it's been very good to you too. Yeah. Okay, but with Stravinsky, this was a gap. And also whether it works or not, and Sakharov loved this work.

It became pretty famous among Russian cosmologists. I did not like it for two reasons. First, it is this fact that what was the initial point? Okay. Okay. And the second is that really to make it work, you need to have like billions of different types of particles to give a contribution of a very special type, etc., etc. Okay.

So, but later he just will gradually change this story, and he just forget about this initial suggestion to do it all by this quantum fluctuations, and instead just left one additional terms in the R-square term in the Einstein equation, and this was sufficient if the coefficient in front of it was a normal zero large. Okay. So it worked, and what we learned right now, that these idea which was more than 40 years ago it was in 1980 right now it is still one of the most successful models of inflationary cosmology at that time it was not even considered inflation

because he did not pretend solving all these problems yeah that was a difference i mean i think that there's a difference in it's interesting there's definitely people who do the work and people who do the work and convince the world that it's interesting and the the key thing that alan gooth did that was Well, many things. We're both friends with Alan and he's a good friend and I admire him tremendously, but is that Alan realized suddenly that not only if you had this period when the universe was in this super cool state, if you want to call it that, where it was dominated by what we now call vacuum energy, and then the phase transition happened, if that phase was long enough, the universe could expand exponentially for a very long time,

and at least on the time scales of interest, which is not something that Sterabinsky had emphasized. And that could solve all, at least all at the time, the three fundamental problems in cosmology that were otherwise inexplicable, why the universe should be so flat, why it should be so uniform, and why it should be hot if you want.

And also, as people don't realize now, solve another big problem, which was really bothering us particle physicists at the time. I remember vividly, why there should not be so many things called monopoles. That's a more sophisticated problem. But I think I remember in the United States at least, because I was there at the time as a student and then at Harvard,

that was the thing that made inflation so impressive. This grand unified theory, this theory that unified the forces would automatically produce these particle called monopoles. They'd be super heavy and the universe should be full of them. And there seemed no way to get rid of them. And it's funny, now you never hear that talked about. But at the time, I think that was the thing that got most of the particle physics community interested in the East United States. I'm wondering, I want to know in Russia at the time, first of all, how did you learn about the Goose result?

And what impressed people about Goose work? Was it the Bonapoles or was it the other stuff? Okay, I can tell you my part of the story. So I actually, together with Chibisov, who later Chibisov and Mukhanov, a very important paper. So we studied with him what happened when you have a strong, strong, strong super cooling. And we realized, of course, that the universe, because it is cosmological constant there, that it should be exponentially expanding. And then it produced bubbles and these bubbles collide and the universe becomes immensely

inhomogeneous. And then therefore it is not our universe. Okay, yeah. And so I've written about this something very, very short in one of my own. my reviews in 78. And after that, I remember how Chibisov told me, and you know what? He was kind of melancholic person, said,

maybe it is also possible to use this for solving entropy problem. And I told him what problem? So that was how it was, okay? So we knew everything and we did not do nothing about that. at this time. Then I was at the seminar, which was organized by Rubakov, one famous person who just... Yeah, I'm personally I learned a lot from him. I again, admire him tremendously. Yeah, but I'm not really Rubikov. So they discussed the possibility of solving a flatness problem due to cosmological before Goose. Before Goose.

Before Goose. Before Goof. due to before Goose became known in Russia. We did not get instant information so I cannot right now tell you exactly who said something first. Okay, but before we learned anything about Goose,

this was a seminar and they discussed this flatness problem, which maybe can be solved due to face transitions in the Coleman Weinberg model. And I was there and they explained why it cannot be solved because you know this phase transition goes down and it does not and I said what flatness problem

and then they explained this to me and then I knew was all over the sides that well it does not work anyway and then there was a call one call to me a couple of months later by Lev Okwin he was a well famous physicist in Russia studying elective weak theory, whatever.

And he asked me, Andrea, did you hear anything about this Alan Goose paper, how you can solve the flatness problem? I told him, no, I don't know anything about that. But let me explain you why it does not work. And it's a half an hour I was explaining him why it does not work and stuff. and then and then I received the preprint and indeed

it did not work but the idea was so exciting okay because he emphasized not why the problem but the solutions if you wish so that was why I got an ulcer I believe

ulcer of duodenum I got it because I was stressed this is such a beautiful idea and I need just a little bit maybe to make it work. Okay. I see so. And I didn't know how to do it.

I didn't know how to do it. And then eventually in summer of 81, I realized something very simple. I was actually using a very bad computer in somewhere in the basement of Leibre Physical Institute, studying tunneling. And I've noticed that sometimes tunneling does not go from the minimum to another minimum. Sometimes it goes some strange way. And I studied the condition for the strange way and realized that actually quite often a possibility. And somehow nobody studied it. Everybody assumed that you go from one vacuum to another vacuum.

But the powerful computer was... Okay. And then I still did not put one and one together. And then at some night I realized that actually this solves a problem because the tunneling, if it is there, goes almost horizontally. So vacuum energy almost preserved. And after that, you're all down, but you still have for a while large vacuum energy and then interior of the bubble explodes. and I decided

that must be everybody must know it because it's so simple so I decided to call Valeri Rubacov. He was the first and they hide somewhere with the telephone

not to wake up my family and they called him and asked whatever did you think about this and he said no no I don't know and then I got really excited I'm excited and I wake my wife and I told her enough it seems that I know how the universe was born. But this was...

She said go back to sleep or did what it? Well, we had a discussion. Oh, she woke up. Good. That was very good of her. Okay. I want to step back because obviously you and I can talk in the language we understand, but for the people hearing they may not, let me, I want to parse a few of these things more carefully before we go on. First of all, this flatness problem, just to make it clear, once again, is that the universe is, is, is, is, is very, looks like it's flat in the sense that it, it, it, it, you, the curvature of

the universe is not really observable on any, on any scales and that like like earth is flat. Like the earth is like if I look out, um, here, I can see a little curvature, but if I'm in Kansas, I don't see any, and the earth seems flat. And it's and it's so the curvature of the earth is is so small on human scales that it looks like it's flat. And and and and that was a problem because it seems to be very, in order to have a universe that looks flat after 14 billion years, the mathematics has to be incredibly fine-tuned. But the reason this that this idea of inflation solves that, that even the original Gooth idea of inflation is that like blowing up a balloon, if the universe expands exponentially, any flat, any curvature gets pushed very, very far away if you want, it becomes very small.

And so it's just like blowing up a balloon and it automatically, a period of exponential expansion will solve. If it even has, as we say, even if the exponential expansion is only 50 times the original time scale, 50 E-foldings, as we say, already you've basically made a universe that's flat to any measurable value. And that was a huge result. And that's one of the things that Goose emphasized that, that, and one of the otherwise inexplicable problems that he solved. But the problem that you recognized early on and the problem that Goose alluded to at the end of the paper is, well, it solves that problem and it solves the other problems we

briefly mentioned. But if it's, if there's a, if the face transition is first order, then these bubbles form of new phase, just like water, and in principle, you're going to end up with a universe that's totally in homogeneous, and that doesn't look like our universe at all, which is very smooth, and uniform. That's actually an interesting interpretation.

But if you want to go ahead. No, no, no, no. If you want, I told you, you always correct me, so go ahead and that now. The idea was that we live for a while in some state which is called false vacuum. Yes, a false vacuum. Real like vacuum, which means that the state where all envirances are present, you move, you walk with respect to anything, but there is nothing with respect to move. It is totally, absolutely homogeneous and uniform, whatever.

So there is no preferable coordinate system. there is no preferable choice of time because in deceter space, the same exponential expansion universe described the Cedar space, which was the point of so many confusions from 1917 when it was first discovered.

It in some coordinates looks like collapsing, in some others look like expanding, and in some other coordinates look like static. Yeah. So if you do not have any orientures, anything with respect to which it expands, does it actually make sense to say that it is expanding at all? And if there is no preferable choice of hyper, and this is most important, preferable choice of time, then you do not have any preferable time for the universe to start decaying. tools are decaying.

And that is why decay over this vacuum-like state happens completely chaotic. And that destroys the homogeneity. Okay, that's a wonderful way of thinking about it. Yes, in fact, I've heard you say that. So that's great. But the solution that you came up with that night in the summer of 1981 when you woke up your wife

and she was very kind to you and didn't yell at you for doing that was the fact that, well, when these i mean physically the way this is manifested you you talked about mathematically how we know this but physically it's manifested by the collision of bubbles and this and reminding yourself of water that and goose universe had lots of by at the end of inflation there'd be lots of bubbles forming and that would screw everything up but your realization was it's possible to have inflation inside of a single bubble and so the whole universe can be not many bubbles but one bubble and and because as you point

out in the language you said it that if by tunneling the universe can go from one state to another, even inside the bubble, when naively you'd think there's no energy stored, it can happen that there's energy stored inside a single bubble so the single bubble can expand exponentially. And that was the birth of what then I guess quickly became called new inflation. And that suddenly avoided the what I guess Alan called the exit problem. I think I remember the, the, the graceful exit. There was no graceful exit from the old inflation because it was a mess. But in this new inflation, if the field, if the, if the field, if you want to call

whatever was governing this system at the time cause the university. That field could gracefully go away slowly and uniformly everywhere throughout that bubble and turn into, as you were one of the people to calculate, and turn into the energy of normal stuff and end up with a hot, what we would now call a hot, hot big bang and then suddenly you solved the last remaining problem of inflation. Well, it looked like it solved the last remaining problem of inflation. It didn't. No, he didn't.

Because and as Stephen Hawking, and you and I both know Stephen and admire him, but we also knew that Stephen was not a fan because he didn't invent it partly. And he realized and I think he learned from you that there was a problem, right? was in 1980, at a conference in the Soviet Union. No, he, the story was like that. There was a conference and they gave a talk. Yeah.

And at that time, this was like almost, well, four months after I actually written the paper and I finally got the permission. It was in October 81. And everybody started suggesting me that we can smuggle the paper abroad, but I- That's important. You were still at a time when a Russian scientist, so you could do stuff, but you weren't allowed to publish it abroad and people like us didn't hear about it. So go on. Yeah, well, so, but the day after my talk, Hoking gave a talk of Sternberg Institute of Astronomy in Moscow State University.

And I have heard about it, and I came there, and then of a sudden they asked me to translate what he said. And that was one of the experiences of my life because at first, usually, Steve at that time, he would just ask his student to give a talk. And then if he was unhappy, he would say, la-va, and his student will change something. But this time, they came completely unprepared. So Steve would say one word, student would say one word,

and then I would translate this word. But fortunately, they were discussing exactly this old inflation. And Steve Hawking had another way of proving that it's impossible to improve it. That was the origin of my culture, you know. And Alan have written a paper with Eric Weinberg proving that it's impossible to improve it. So I was translating what Steve said. At some moment, it became intolerable that it just will. So slow, so after Steve say one word and students say one word, then I will speak for five minutes.

And so it will continue. I explained why it cannot be improved. And then Steve said something which was translated by his student, something like that. But recently, Andrea Eindez suggested the way how to improve it and I have it translated. And then the next word was, but unfortunately, it's wrong. And he started explaining why my paper is wrong, and I was translating it. And, you know, me, a young person who is not yet will have a clear guaranteed future. And here are the best people of Russia watching how he explains why stupid things.

Okay. So I translated and I say I translated by disagree. And they explained why. And I asked Steve, do you want me to tell you more about that? And he said, voila. And we disappeared in one room of this institute. And for about two hours, all institute was in panic because they did not notice where Stephen disappeared. They thought that the famous British scientist disappeared.

Tomorrow, it will be in newspapers. And meanwhile, I was at the blackboard telling him something. And he, from time, thought I say, wawa. and his student would say, oh, but you did not tell that before. And we continue this manner. And then he invited me to his hotel. And then he starts showing photographs of his family and we became friends, you know. Yes, I remember the period.

I was, shortly thereafter, he and I had adjoining offices. He was visiting Harvard. So I got to know him. And what people don't realize, because they know the Stephen of the computer now. But at that stage, he could still talk. And if you knew him well enough, which his students did, they could understand what he was saying. To most people, it would sound like a mumble. I remember I was able to sort of understand a little bit, but whenever he gave a talk, he would say,

and then a student would repeat what he'd said. It was before the computer, and that was what was happening when you were doing that. And yeah, it must have been very weird to be repeating Stephen Hawking saying that you were wrong when you knew you weren't. And it took some... New inflation have died its own death, not for this reason. Yeah. It just, well, when people calculated amplitude of density perforations, it appeared to be way to high. And that was clear.

Yeah, let me, let me parse that because in fact, this whole idea, which is beautiful, did appear to suffer a fatal problem, and it's due to quantum mechanics. And that actually, I believe my first understanding of how it happened, Well, my best understanding of it's happened, I think I learned from you from one of your books early on. I learned it a different way, but it really made it intuitive sense. And that basically is, and again, you'll correct me, I'm sure, but that is that so everything's smooth, but while the universe expanding, quantum fields are fluctuating. And if it expands long enough, the fields, the quantum fluctuations continue to grow and grow and grow.

And so if you have this perfect desider expansion, by the time it ends, there'll be huge quantum fluctuations and those will produce huge in homogeneity. So a field which is an inflation which is almost exactly as we call the sitter, which doesn't depart at all from where the field doesn't change at all during that time, will allow the quantum fluctuations to grow. I think it's linearly with time. I forget whether it's linearly or quadratically. The square goes linearly. Yeah, okay. The square goes linearly with time. And that would produce two large fluctuations.

And that was the fatal flaw in this perfect idea of new inflation where the field didn't change very radically. So now you can change. You can improve my discussion. It was actually, well, once manned flaw in a, another man, great discovery. It was first discovered in Staravinsky model by Mujano and Chibisov in 81. And Mujano, I remember, he was sitting in a nearby office,

and he was trying to explain what is going on. And I told him, but it's nonsense because it's quantum fluctuations. And the galaxies, how can you get galaxies from? And it took me some time to understand, okay, because these fluctuations which are produced during inflation, they stretch. So their wavelengths, they become exponentially large. And during stretching also, they do not oscillate. There are some terms and equation of motion and freeze them.

So they were freezing and stretching. And then others freeze on their top. And there are others, just like you said. Okay. So in Starabinsky model, it actually works great. In new inflation, the amplitude of fluctuations is too large, and I first learned about it from Starabinsky. I attended some conference, which was, well, somewhere in the, like close to Karelia in Russia. And it was, it was very, very disappointing for me. I'm learning, oh, maybe he is wrong, or maybe he's wrong. He said that an amplitude of fluctuations are too large.

Okay. So a couple of months after that, there was a conference in Nathel. And Straubinsky came there with his already paper. And at that time, Hawking already issued his paper saying that fluctuations are small. No, they're just right. And then there was a goose sitting here and saying that, well, let's calculate them. And then calculated they happen to be too large. And then a group of three other people who will a year later publish their paper.

One way or another, it was Tarabinsky who I know that he did it, because the memory you cannot erase from this disappointed. appointment. Okay, so it was Tartu, a conference in TARP. So what can I do? So essentially, when we left Nuffield conference in Cambridge, which was the first conference on inflationary cosmology. Yeah, it was 1982. I remember that. I was invited to it and Harvard wouldn't give me money to go. And I really felt badly after us. But that was the conference where all these independent groups were calculating supposedly the same thing, which is, could you make galaxies and the coming up with the fact that, and let me put it a slightly different way,

the fact that in order for the fluctuations to be small enough to be the seeds of galaxies and not too large to destroy the isotropy, the microwave background, then there'd have to be some parameters in this theory that had to be so fine-tuned to be like one part in a million or one part in a million million, that's the, that's the lesson I learned. And it hurt me very much because I knew that if I'd been there, I would have been part of one of those groups. And I felt like I missed out. Trust me, it hurt me more. Yeah, I got it hurt you more.

Okay. But I think that the consequences of that were not quite understood for quite a while. And one of the consequences is that if you need to change the theory to make it work, how you do it. And so what are ingredients? First ingredient is high temperature. sufficiently large coupling constants to have these phase transitions and to have thermalization in the early universe. And then this matter. Heat the universe up afterwards.

Yeah. Yeah. Well, okay. So several different assumptions. And what happened later, and that was for me, like one of these few shocking experiences. because, you know, when you know that something is impossible and then something becomes easy, that is, oh, how would it be? Well, so what I found is that if you just have the simplest, simplest scale of you,

without any maximum or, well, this minimum or whatever, and without any high-temperature phase transitions to get rid of it was the main pain for me, because this is my theory, okay? High-temperature phase transition. There was what, but I remember what Kiersnitz told me once. Just forget about it. Yeah.

You know, in fact, I think that's really, I mean, your life has been an example of that, but that's one of the greatest beauty of science that I wish the public would not only appreciate, but I wish you could disseminate it. Is that in science you learn, to forget, you know, that something you're willing to be wrong and also learn to throw out ideas, bad ideas like yesterday's newspaper, regardless of how precious they are to you.

It's an experience you have. And so many ideas in the real world are dogmatically held, even when they're obviously wrong. It happens in science too. But what makes science great and what makes some scientists great is that they can learn to throw out the bad ideas and accept the new ones. And your life throughout your career has been an example of taking your own ideas in some sense and we're willing to throw them out. But the problem is this mostly psychological. Well, I do not consider myself like a great physicist in the sense that there are quite a lot of people who do math way, way better than me. I have something like intuition maybe.

And another thing is, yes, indeed, if I see something clearly, then I don't care what other thing. Okay. And this, like having a theory with a potential like a harmonic oscillator or something like that. And having it lead to inflation, then, oh, wow. And then you do not need the universe to be hot? I mean, this is like you have this snake which hypnotize you. You know that there was a hot big bang. You know that there was a hot big bank.

You know, right now I'm opening every text book on cosmology. They all start with describing the hot big bang. and it is not necessary. In fact, it is much more difficult to make a universe inflate if it starts with hot big bank. So I wonder what is going on. I'm sending this people message. Let me help you to write it properly because your theory was actually ruled out 40 years ago and you are still teaching your students this and they say, yeah, but what can we do?

We copied it from one particular place, and now we have a copyright, and we cannot change what all these guys. So it's amazing. But, well, you take what is good, and you just go forward. Well, this idea was revolutionary, and it's surprising. Again, it's simple, like many things in physics, it's simple in retrospect. but the notion that you realize when you went from this new inflation which required, just to remind,

I want to, people may be confused, it still required a phase transition, but it was a phase transition that was different that had a bubble, and our universe existed within one bubble, but what you realized is that this part was, this part was, you see, I did,

I will not allow you, okay, no purity of thought. In new inflation, this was the universe, inside the bubble. In chaotic inflation, you do not need the bubbles. Exactly. That's the whole point. I was just going to get there. Suddenly, new inflation had a bubble and suddenly you realize you don't need a bubble at all. You don't even need a phase transition. That if you have a universe with the simplest

possible example of what we call a harmonic oscillator, but that may not mean anything anyone, but you don't have to do have anything weird kind of special initial conditions. and then can you explain what happens? Actually, one of the things which brought me to it also about this initial conditions, you may consider a smallest, smallest possible universes, like for example, a closet universe of a plankian mass, of a plankton density,

but it is 10 to the minus 5 grams. Yeah. It's nothing, okay? That's nothing. And if it is filled with a scalar field with maximal energy, which is plankton energy, okay, if a potential energy of the field is greater than gradient and kinetic energy, then this thing becomes expanding. And within not 10 to the minus 20 seconds, it is within 10 to the minus 40 seconds, it becomes much greater than our universe. So you get energy from nothing. This looks like a more sophisticated, no, it's stupid.

It is incredible way of cheating because you start from nothing. If you got used to the idea that energy is concerned, how you get, well, these 10 to the 90 almost particles surrounding us in a visible part of the universe, starting from no single particle at all. Yeah. So this is, well, and no violation of loss of physics. This is what is strange, no violation of loss of physics. And that's the hardest thing to get to people to understand is that you can do it without any, as I like to say in my book, any supernatural shenanigans.

Yeah, right. And then I got in trouble. Well, I haven't got in trouble. Some people don't like it. Although the way I heard it, I still think Allen's description, because it uses in a phrase that's used, that Americans are used to, is what the one that can meet me, calling it the ultimate free lunch. You know, people say there's no such thing as a free lunch, and he would say the universe is the ultimate free lunch. Because apparently from nothing, you can get everything and it doesn't violate any laws of physics. It's really kind of remarkable.

Now, in fact, we understand how that happens. it turns out the way general relativity works is that as the universe is expanding, the universe is doing work on the stuff inside. So it's not as if energy is violated. It's that universe is doing work on the expansion and dumping energy into that system because of what we call negative pressure. But since you mentioned the sentence of Alan Goose, you know, I first time made an extension of what he did. And now in 82, when there was this Nafel symposium, I actually issued a preprint about eternal inflation and new inflation scenario. And this was also after Stanford gave a talk there about that. And I still have a copy of the preprint.

What was important there, that once you have this bubble or novel, whatever happens. In different parts of the universe, you may have this transition. At that time, it was transition, but later it was different, happening independently. So if that is the way,

I know, for example, that in SU5, especially in supersymmetric ASU5, a dozen of different minimum. So you can fall to the right, to the left, straightforward, whatever. You fall into red minimum, blue minimum, green minimum, with different physics. And they said, look, this is what you do.

In the same universe, you have these different bubbles and symmetry is broken differently there. So you have all possible laws of physics compatible with your theory realized in different parts of the universe. Each of them is exponentially large. So I said this was in my concluding sentences, of my proceedings of Nafel Symposium, that the universe is not only a free lunch, it is like an eternal feast, where it produces all possible universes on all dishes are served.

Well, okay, now that's jumping way ahead, because initially, when you realize that you could just not have a transition, you could perhaps by a quantum fluctuation, enter into that state, which is what I talked about in my book. And then that state could inflate. But then you realize that it's even better than that. So you call that chaotic inflation, but that the inflation could be eternal. And that was what's surprising,

because you think you'd have, if you have a field that's not at the bottom of its potential, you'd think it would fall down. That would be the sensible thing. But of course, you do anything but that. You realize that quantum fluctuations could change things. Maybe you could describe for a moment how it can become eternal for people. I first then may tell you what is the advantage sometimes of leading in how you say totalitarian regime.

It was in 85. I live in a strange state. time Gorbachev came to power and decided to make perestroika. Perestroika means you do everything as it should be, kind of freedom gradually destroy previously existing bureaucratic machine and whatever. And one of the first things he did, he decided to simplify our way of getting permissions for publication. But the first thing which was done he destroyed

previously existing system without replacing it by anything. And for about a year we were living with our mouth shut. So we could not send anything God forbid abroad. So this was depressing.

It's one of my friends actually Renata's brother, used to say that a cow need to be milked. You know, otherwise it's painful. So you say and I cannot publish whatever I'm thinking about. It is, God knows for how long. So then I start writing my book. Book about inflation, I decided, okay, I know already chaotic inflation. Everything is done, nothing new.

So let me just write it. I started writing it. I hated it because I hate second time saying the same thing and whatever and writing it. And then using scissors and glue because there was no computer. So it was terrible. And finally, we finally got some money to buy maybe in the future a car. And they start learning how to drive the car. And I attending the school.

And at my age it was already not so interesting. But on Moscow ice, when my instructor explained me in pure Russian, not in the textbook language, what he thinks about me when I was driving. So it all did not contribute well to my mental status. So I started feeling really bad. You went into a depression, in fact, didn't you? I don't know what it was, because all doctors told me that I am perfectly. healthy. But I was laying in the bed and I was able only to read detective stories. I could not do much. And I felt really physically awful. And then suddenly there was a phone call from Academy of Sciences

saying that you need to go to Italy to give lectures on, well, astronomy, not inflation, astronomy to citizen of Rome and Turin or whatever and the status at that time was like that. You do not go abroad more than once. So if you go

once, you're lucky. But then you choose these ones. And choosing these ones to teach astronomy to people in Rome, I said, no, I can't go. I am ill. Well, give us a certificate that you're ill. So I was out of my strengths. I asked Renata, can you please go to the institute? She came to

Ginsburg, our head of the department, asked, can you sign a letter that Linda's ill and cannot go abroad? He started laughing. It's so easy if he doesn't want to go abroad, just doesn't go. But he signed it anyway. A few days later, there was a call from another part of academic science saying, well, we received your letter. I understand that you are ill, but today you are ill and tomorrow you are healthy. If you cannot go abroad, just say a soul. And apparently there was something about Russian-Italian friendship, so it was completely different line. So they decided that somebody must go. And if I say that I cannot go, then this may be for life. So it was really worrisome and stood from my bed. I went to the hospital for Academy of Sciences,

paid for a taxi, which was at that time a financial decision for me. And I, within one day, I got signatures of all doctors certifying that I am absolutely healthy. Usually it would take me like a week and a half to do it. Then I returned back home. I was lying in a bad, really in a bad state, and writing some papers which are necessary to get permission for going abroad. In Monday, I paid a taxi game to bring my body there, and then I paid our secretaries to immediately type it, and they typed it to me, and I went to all places in our institute to get all required signatures so that I can go abroad, okay? And usually it took me a normal way about the mountain behalf. I did it within that day, okay, because I was really scared. And then,

seriously, because this is not a joke. Yeah. And then I gave these documents there. And I was recovering at home. And three days later, there was a poll from a different place. from academic science, saying, okay, we'll receive your documents, you're going to Italy. But our Italian friends asked that you please provide your, well, text of your talk beforehand so that we can distribute it to our Italian friends and they would read it before you give a talk. And I was really out of my wits, and I asked them, what, when should I give you? it to you. And I said, better tomorrow. And I thought, that's just impossible to write a new paper,

which is nowhere, and to give them all of this tomorrow. But then on the other hand, if I don't do it, I use my once opportunity, because for almost a year, I am leaving with my mouth shut. And now I can send it without any permission. I just give them. They will send it by diplomatic mail. Tomorrow it will be in Italy. So I just took my head like that and I stopped moving. It's like that. Oh. And what can I do? What I can invent within half an hour so that I will print it today, type it today and they send it tomorrow. And within half an hour, I found this eternal chaotic inflation. I just, well, I don't know where it came from. I just checked how these quantum fluctuations

may occasionally throw the field higher, higher with the potential. And then it rolls down as it should, but sometimes the quantum fluctuations push it back again. And in this part of the universe, where you jumped again against all normal laws, like, well, like, which jumps again the river, the water.

So sometimes when you jump there, then you are rewarded by exponential expansion of volume. And then you jump again, and in some rear parts of it, you are rewarded again. And it's just like in economy, some very rich people become more rich laser. The universe which is able to jump, it is rewarded by, okay?

So I was unable to write it this, evening but I just gave them some crop which was in my of some previous lectures whatever and months later when I was in Italy I smuggled with me three new papers which I've written during this time and I published them when I came to Trieste and that was it okay so it's a perfect example of necessity is the mother of invention you had to I would not recommend you try and get a problem because it's a very damaging experience. It must have been tremendous, as you say, it was damaging but wonderful at the same time. The stress of that caused you to come up with this idea.

And just to clarify it for people once more, the point is that if you start with the universe that inflates and that inflation ends, that's fine, that works. and it's finite and you solve the problems, and that's chaotic inflation in the sense of that you just, you can start out with a universe which is sufficiently energetic and has enough energy stored in empty space. Most universes may not, but some do, and those will inflate, and boom, and if you're in one of those universes, you're fine.

But then the next stage is to realize that even in that universe, which inflates, eventually that will end, but in some places in that universe, it won't end. It'll get bigger. And that'll be very rare, but you're rewarded. So the probability of that happening is very small, but if that region grows exponentially, then you have a small probability times a big volume,

and most of the volume will be those things that have had that very rare thing happen. And then it'll happen again and again and again. And so something which intrinsically seems to be very improbable can become very probable because it's rewarded, as you say, by most of space is still inflating. And in that picture, in what we now call the multiverse, most of space is still inflating.

We happen to have live in a region that stopped so that you and I could have this conversation. But in most of the space in the universe, it's empty space that's cold and expanding exponentially. And that's what we now call internal inflation. And that was the idea that you have. I should say just to be fair, that very similar ideas about,

that was indeed in these papers of 82 on new inflation and also especially in the paper by Williamkin in 83 on new inflation but it was near the top and this was what I did was totally illegitimate okay but it just happened to happen and also what was important for me especially just because if you do something then try to well to do it to the possible limit. So this process is especially active when you jump higher and high and higher to the highest heights. And that is like plankton density. And when you jump there at plank and density, you induce quantum fluctuations in every other field which was lazily laying around. You push them over any barrier which separated the possible states. So if the

has any many different possibilities, then this quantum fluctuations push the universe in its different parts and continue pushing it forever in different realizations. So if the universe potentially could be red, white, yellow, whatever, then they're always producing yellow, red, exponentially, large part of the universe. So laws of physics, it's maybe a wrong language. You may have one unifying law of physics, but realization of laws of physics can be different in different parts of the universe. And that is something which will just completely blow in my mind after I realized this at that time. So that was everything else. Eternal inflation was interesting. But the possibility that you also have this total freedom, you know, it's opposite to what many people here may want to have.

You want to have some structure and the law or whatever. But when Russians first came to Safeway, they were just, well, they see too much coffee and they leave Safeway without buying anything. because freedom is too large. But for some of us, these unlimited freedom or possibility of unlimited freedom, once you realize that this possibility in some theories is possible, it is not forbidden. It is a consequence of simple calculations. then you cannot just get rid of this dream later. You know, and it's something that flies in the face of everything that one learned to love about physics. I mean, I became a physicist, as you did, I'm sure, a particle physicist especially and a theoretical physicist,

because I wanted to discover why the universe had to be the way it is. And the net result of this is, the universe doesn't have to be the way it is at all. In fact, most of the time, it isn't the way it is. And that's such a revolutionary. And I have to say initially disgusting notion for someone who is brought up saying, I want to discover, like Einstein, I want to discover the ultimate laws of physics, why the universe must cannot be different to suddenly give up that notion, to think that the universe can be quite different and still be okay.

We just wouldn't be here necessarily to talk about it. Is a revolutionary and a very, a very unpleasant notion. initially, certainly. For some. Well, for anyone who'd grown up wanting to discover the ultimate laws. And when they're going to vote, every year you're supposed to go to what, there is one person in the ballot. Yeah, yeah.

So when you have diversity of whom you can elect, that is something fresh. So I don't say that this is very encouraging. So you liked it early? Well, as always, of course, one loves one's own ideas, generally before other people do anyway. But you certainly liked it before anyone else. And I, and the notion of eternal inflation did seem initially interesting, but disgusting initially for many people because of this notion of what we now call a multiverse. But let me say one thing. It's very important. And I have to say, I have to tell you not that it matters, but I was reading your descriptions in a few recent, Summaries. And you talk about the fact that we get a multiverse because the field can start out in different places and different regimes and the law and and and and and make it sound like that's why we get a multiverse, but that's not the case at all. That would just cause the transition to be different from place to place. What you need and you don't say that in your papers. You can rewrite them. What you need is not just that it starts at different places, but it ends at different places. And I, and I found that a little confusing in, in when you wrote because. You have to, because that's the key point, is that the final state is different, not that the initial state is different, but the final state.

So your theory must allow you this. Because if it always, if there's one single state it can end up, it doesn't matter where you start from, you always end up at the same place. There is a trick about that. There is a trick. The trick is that when you are talking about the multiverse, of course, when you just go to this everything, everywhere all at once, they have their own idea what multiverse is. Okay, so everyone has its own understanding. There is one which is less revolutionary. And this one, probably everybody would buy,

and after you buy it, then you already attract. Okay, so here it is. Yes, we know that now that after Planck, after the theory of, well, galaxy formation from quantum fluctuations. We know that we have right now this mechanism of production of large-scale structure of the universe, and for a while it was one of the many mechanisms. Like, for example, there was a cosmic strings, textures, etc. After so many years, none of this mechanism alone was able to explain the observable structure of the universe. So either you are in inflationary theory, or you are now with.

with any of its competitors, cyclic, pirotic, whatever. We'll talk about some of those later. Yeah, whatever. In all of these models, you always use the principle that large-scale structure was produced by quantum mutations. Once you say so, you sold your, well, sold to a devil. Because what does it mean, really? it mean really and I formulated it in a tricky way you know starting from well the origin of quantum mechanics you have this famous Schrodinger cat paradox so cat end up either

dead or alive but probabilistically so yeah so people even now debate and hate each other in debating whether the cat is really dead or really alive before the way functional the cat is reduced by an external observer, or maybe it's a multiverse interpretation saying that one cat is dead in this universe and it's a twin cat originally is right now in another parallel universe, whatever. So all of this was about the cat which existed there, and the whole debate is about whether the cat can what's real?

Who is the killer? Who opened the cage? Maybe because before you observe it, the cat is not registered dead. So all of this was interpretation of quantum mechanics. So what happened with galaxies,

it's like the cat which was not there. Because in the beginning there was no cat. There was no galaxies. It's not that the galaxies is here and galaxy can be different, okay? It's a no galaxy

because it's quantum field theory. In quantum field theory, you may start with a state without any particles we go to state with many particles. So we start with a state with no cat. We get a state with a cat. And after that, cat is either

dead or alive. We start with a state without any galaxies and you get the galaxies. But because galaxies right now as children of of populations, galaxy can stay another galaxy to the right of you or to the left of you, or in this part of the sky, on this part of the sky. It's quantum mechanical chances. Yes.

So then when you produce the universe and the universe continues self-reproducing, then you produce all possible combinations of galaxies in the sky. This is already a multiverse. So if you're born in a different part of the universe, you have completely different sets on the galaxies on the sky. And if you travel all across the multiverse, if it were possible, which is practically not. But if you would just imagine the traveling, then you see inside the same thing, produce it from one speck of space, well, 10 to the minus 33 centimeters long. you produce all distributions of galaxies of all possible type, taking all possible states in the sky, every possibility exists somewhere, okay?

So that's a multiverse, like it or not. This is a property of every theory. I mean, when people from community who hates inflation say something hateful about multiverse, they ignore the fact that they have the same story. And if in their models, they have many Vakua, string theory Vakua, they have multiverse in their own room. Okay, so what happens is that people do not understand that when a genie is out of the bottle, it is very difficult to put it back. You cannot just say because you don't like the idea. You may hate it.

And I absolutely understand the haters, because it would be good. great to have one unique explanation. But you know what? I like what Gellman said about that. He said in a reply, maybe, maybe he said it in a different context. But I read it like a consequence sequence from Einstein to Gellman. Einstein wanted to find why only these coupling constants are possible. And Gellman said, Gellman Hartle, they said that some things

are fundamental and some things are environmental. So if you have the same fundamental theory with a set of fundamental constants, but realizations is just like water can be frozen, liquid and vapor, the same water. So you have the same fundamental truth. But it has different realization than in different environments, it is realized differently

and there was something, some things which we previously realized, assumed to be constant, fundamental constant. They're just environmental. In this environment, this is what you see. In some environment, fish can flow, but it cannot flow and cannot live in ice. So that is something on cosmic scale. That is pretty interesting. Yeah, no, in fact, I think I've, I don't know, I didn't hear it from Gelman, but I first heard, indeed, if the multiverse is true,

then physics becomes an environmental science, not a fundamental science. Some people don't like that we do fundamental physics. They don't think of it as fundamental. And fundamental physics becomes environmental science, as you say. It's just we're here because of an environmental accident. If there's a multiverse and if the laws of physics are different in the different regions, and I should say, before I want to get to the multivers as we get near the end here,

but I want to, I should say that, that, what was I going to say? That, there's only things I want to get to. That if there is a multiverse, then that the, oh, I now remember what I was going to say, that many people talk about different kinds of multiverses and the public gets confused. Because in string theory, there's many dimensions,

and there could be a multiverse in the sense that our mere four dimensional universe can be one part of a highly much bigger dimensional space and there could be another universe a millimeter away or less than that in some extra dimension and blah blah blah blah, blah. But let me say this and maybe we, I assume you'll agree.

When people ask me about a multiverse, I say there's only one well motivated multiverse. And for me, that's the multiverse from inflation. No extra dimensions, no physics that we don't know about. It's the physics that we can understand in a four dimensional universe. universe that if there's inflation, you almost inevitably end up with a multiverse. So I don't bother talking about extra dimensions because it's too confusing and also very speculative. If inflation

happened, there's a well-motiv then that's the one well-motivated multiverse. And that's the one multiverse that gives us this possibility, weird possibility that the laws of physics could be different in each possible universe, which I want to get to because that leads to a whole bunch of, well, it leads to a different world, but in a different way of thinking. I was going to say that the perestroika that also allowed you to get to Italy, there's two things I want to get to before that. One is it allowed you to get to Italy, but eventually it allowed you to get to the United States. In 1989, you spent a year at CERN, and I wanted to ask you, you decided not to go. Look, I was around at the time, and it was clear to me that many of the best Russian

scientists were leaving the moment they had an opportunity to do so. Princeton snapped up whole bunch and and and and and some stayed um valerubikov stayed i let me say but but what was the decision that caused you and and renata to decide in 1990 to not go back to so to russia but to but to move to stanford if you want to talk about it if you don't it's fine um i think uh things happen sometimes unexpectedly um for each of us I was absolutely sure that I'm going to return back. I had a very bad but still running car. So I oiled it and I put it to my father's garage so that I was able that when I return,

it will be still in existence. Okay. We had an apartment. I had my mother and father living there at that time. But another's mother, unfortunately, passed away at that time. So when we appear at CERN, you know, you usually, in our practice, we previously would come like only one of us. Without children, you do not have any real option to stay there unless you want to get rid of your family and ever. But so this was the first time when they allowed us to come for a year with the family.

And then when we came there, they suddenly at CERN start talking with me about staying there maybe forever. Then some people from US came up to CERN suggesting me and Renaud to get professor positions in Minnesota University. I was flying there. And they explained me how life is good there, etc., etc., etc., and they explained me how life is good there, etc., etc., and they explain me what will be my salary there in Renata's, and I looked at them and said, no. First of all salary above $2,500, I must return back to Academy of Sciences. It was still not real. And second, well, just imagine what I'm going to do with the money like that.

And they told me, yes, but it is still a position in society. And I did not tell them, but I thought, what I'm going to do with whatever. So it was not real, but gradually these things start accumulating. And when you start understanding that this is now maybe real, and my children attending international school in Geneva and they're doing well and they're doing well in English and my older one is all the time at a certain theory division explaining me how to use Apple Macintosh computer

because he knew it instantly and he was so agitated and he says so beautiful I said, why? And then it took me some time to understand, and I'm still using apples only. I remember you were used it early on, Apple too, and then, yeah, we both did. So things like that, they happen gradually, and then you see that what you previously consider, like, a barrier. It may be a soft transition, and you may not make any final decisions, and, well, So that's how it is.

So you know, you had a smooth transition that could have been chaotic and you could have gone back. Yeah. Like inflation. It could be. But also because our previous life, as I said, with these visits to Sakharov, et cetera, and everything made us not very well against the possibility. to stay around here. So that was like that.

Okay, so it was no big, it was sort of an evolving realization that a different life could be quite good, just like an evolving realization that a multiple universes could be quite good. Yeah. And then you were in Stanford instead of in a different university

could have been in Russia. And Lenny Saske. Lenny Saskin was totally great. Now, I want to go back to this multiple universe, but I wanted to get to the point, you're now at Stanford and how you got there. And I always wondered about that, whether it was an obvious decision or whether it came out.

You did say something, which I do wanna go back to, before we get to the multiverse, because one of the important things about inflation is it's not just a great idea in different ways, but it actually can be tested in other ways, maybe not unambiguously tested, and that's been a big debate. But one of the points you mentioned

was that if you have enough energy, you get excitations in all fields. And I first learned this not only just in the regular stuff, but you get excitations in gravity. And I think the first person to realize that, at least I learned it was from Rubikov, from a paper. From Rubikov, I learned in 1982 when I was at Harvard. And I remember no one else seemed to have read that paper,

or at least, and I remember telling my friends at that time, my colleague Mark Wise and Larry Abbott, who was nearby, they were working on things. I said, no, you're doing it wrong. This paper by Rubikov shows that you'd get fluctuations in gravity and you'd get gravitational waves as well as all the other stuff. What was that? Staraviansky did it than 70.

Okay, Sierra Dutzy maybe did it first, but I learned it from Rubikov. And it imprinted on me, and I will say that if one area where I think that important fact that gravitational waves that come from inflation did not seem to be something that was on that was percolating in the community and I will give I remember when in when the when the caught when the Colby when the causing microwave background fluctuations were first discovered in 1992 and everyone already said oh look these are quantum fluctuations from in matter fields that could be due to inflation and yes I I said well what about gravity waves and I

worked with then my student then Martin White White, who's now at Berkeley. And I said, you know what? If the scale of inflation is high enough, you could produce gravitational waves and this, and all that Colby ever discovered was this thing called a quadrupole anisotropy. Said, maybe that's just gravity waves,

and we wrote a paper. And then, but what's really been important is to realize that while many theories may predict different fluctuations, one of the things that inflation inevitably does, predict gravity waves. And if you could see them, that would kind of be an unambiguous test of inflation. And people started to seek out and look for them. And it was realized that one way to get them would be looking at something called a polarization in the microwave background. And you know

and I know this wonderful day when it looked like it was accidentally discovered. I remember video of seeing you being at the door with a bottle of champagne and all the rest. But But this could be a smoking gun that would be sort of an unambiguous demonstration that inflation happened. But nevertheless, the other predictions of inflation, a spectrum of fluctuations, which seems to match beautifully with the causing microwave background, super horizon size correlations because inflation stretches things. All of these things have been observed already. Yeah. And I wanted to ask you, do you kind of feel like inflation, even in the absence of gravitational waves, is sort of unambiguously been shown to exist or what do we need to do before we convince the world other than you and maybe me and others that inflation happened? Well, just like with this transition from one country to another,

transitions happen gradually and you become more convinced on the way. So for me, there were several moments in this 40 years of my life with inflation, which were like near-death experience. The first one actually was very early. So in 83 or 84, Igornauioch came to us and said that we expect to have fluctuations of density necessary for producing galaxies at the level 10 to the minus 3. And we do not see them. And idebatic perturbations or these type would be, well, just observable. And so inflation cannot work.

But then later, many years later, we realized that actually if you take into account dark matter, you don't need 10 to the minus 3. Okay, so that was one thing. But for me, at that time, I did not realize that this is near-death experience, but nevertheless. So we were saved by dark matter. Who ordered it? Okay. Then in 95, 90, whatever these years, everybody knew that the universe is not flat because omega is 0.3.

And then I'm coming to a conference in UCLA in 98, and they announced that you have right now a cosmological constant or dark energy which just feeds the bill. Some of us argued that had to be the case beforehand, as you know in 95. Right, right. But nevertheless, when it is answered, and I called Renata to tell her about that. And she's at that time in, oh, my God, this is 75 years old. My God. What is it wrong with me? The place between Stanford and Los Angeles where this institute. Oh, Santa Barbara.

Santa Barbara? Yes. The KITP and Santa Barbara. Yes. I still remember what the eternal inflation is about. I don't remember Well, you remember the important things.

Okay, right. That's how Einstein tried to force himself to forget this speed of sound. Yeah. Well, anyway, so I'm calling, she was just exactly at the conference there. I explained, told her about that,

she was excited. Next day, I calling her again, and she said, you know what? I had a discussion with David Gross. And David Gross told her, oh, Renato, I'm so sorry that inflation right now is finally ruled out. And you know what I say, why? Or because I just returned from the conference in Princeton where they finally all insist that omega is equal to 0.3. and this is not what inflation predicts, and therefore inflation, sorry to say it's finally ruled out.

And I told him, yeah, but Andre just pulled from UCLA and told that they found this dark energy. So right now, everything is no. I came from a real conference in Princeton, not UCLA. And they said that omega is equal to 0.3. Then they all walls in his institute were covered by newspapers announcing it. So this was another near-death experience. It was possible to have I myself invent some models of inflation with omega not people. I remember you didn't.

Yeah. But they were all admittedly extremely ugly and only some other. some ugliest or ugliest of them still exist. I mean, still possible. And I'm telling it without affing anybody because the ugliest was mine. It worked. Okay, but it was absolutely ugliest. It was unbelievably ugly. Okay. And well, so we now there was another experience in 2012, approximately, when everybody starts spreading the rumors that, uh, quite, of the fluctuations produced at inflation. WMAP is going to announce soon there will be a conference in summer, maybe 2012.

The WMAP is going to announce finding this large FNL. All postdoc and students, everyone, it was inventing a new beta theory with large non-gaussianity because they learned, everybody started learning that if some specific type of non-gaussianity, which for the listeners is that normal situation would be that you have normal coins, okay, not bent coins. If somebody is bending coins in inflationary cosmology, you would not like this, okay? So we expected that it was announced. Paul Stinghardt in his talk lecture given the Perimeter Institute said that inflation cannot predict anything, but one thing that it really predicts is that there will be no very small fnl.

And our periodic theory predicts unlike inflation that is about maybe 30. And then finally there was this data from Planck. And I at that time was in Europe boarding the airplane, returning back to Stanford. I was standing near the airplane with Renata's iPhone because at that time I didn't have mine. And she called me from some other not iPhone source and told me, Plunk just made an announcement, made announcement in no non-gaussianity. This was the one thing which he told me, okay? So I downloaded everything on my iPhone.

I was reading in flight. That was it, okay? No, no non-go-no observable non-galcionity. Another near-death experience, because it would rule out practically all single-field inflation immodels. So this will be not a kill. okay, but it would kill like almost every other model which we paid our attention to.

So these kind of stories they were repeated and repeated when you have more 10 of them and I have a list of 10. Yeah. And so you say, do you need to hear a 11th one? Okay.

But I would say that of course if you can get crevitation waves, it would be great. It would be, I mean, it would be, yeah, obviously not just because I've written about them, but it would be really, actually, it'd be great for another reason, which I think you know of. Well, not for me, there's two things. I think you're in one of your things I was reading recently, you say, and a lot of people point out if there's a multiverse, we'll never know about it. But if we could detect gravitational waves, and if that would tell us in detail about the inflationary model, and then you could look at the model and say, does it imply a multiverse? And then you'd have an excellent indirect evidence of other universes. And I argued, in fact, in my new book, that's not that different than atoms. You know, people believed in atoms long before you could ever see one. And happily, you could see one.

But they used to say we'd never be able to see an individual atom, but it didn't stop us from realizing that all the indirect arguments told us that atoms existed. This may not be as strong. But if you could measure gravitational waves, and therefore measure the parameter, the parameters of inflation, you'd be able to indirectly say other universes must exist, even though we'll never see them. For me, I find that heartening. I think it's unlike, you know, even if it's unlikely we'll ever see them, the possibility is a beautiful one, I think.

Yeah. My own attitude to that was changing in time. Definitely when there was a splash with bicep. Yeah. It was very exciting and it was nice to believe it for a while. well when this team came to my house with champagne and whatever I asked them first but how did you do it like you are looking at this part of the sky are you sure that this is not astrophysics because this is like this is small part of it and they don't know we studied everything which okay so what I respect them enormously. They are right now still the champions in this area.

The latest well papers give the greatest constraint on art available at the moment. Sure, I mean, they were just bad luck. I mean, if you did everything right? Physical review asked me to write the companion paper to explain it. And it just happened to be they were looking at the wrong part of the sky. If they'd looked at another part, they wouldn't have seen that signal. signal and who knew at the time that the signal they thought was gravitational waves was actually astrophysical there was no really good reason to do that and so yeah they got in a bad rap i i think they did it

they did everything right but unfortunately just an accident of uh it was environmental science they picked the wrong environment to look for that signal but the other thing by the way that that i think we've talked about but i that i fascinates me the wonderful thing if we could detect gravitational waves from inflation. As you know, my colleague, Frank Bolshek and I produced a paper showing that one of the big questions in modern physics is gravity a quantum theory. And if you could see gravitational waves from inflation, you'd be able to prove it, which to me is a remarkable thing. You'd be able to prove that gravity is a quantum theory. All of us expect it is. But some people say maybe it isn't. Maybe it's quantum mechanics that you have to give up at some fundamental scale.

And so this would resolve that. So it would be a triple score if you could ever detect gravitational waste from inflation, although it's a long shot. I remember that when we discussed this thing with Mujanov, this argument, he insisted that if you do really consistent detailed theory of Adiabatic perturbations, and he knows because he was the author of. author of that but also later on he was the first person who really did

the theory, well, developed the theory of perturbations in chaotic inflation in general. So he said that if you do it very carefully then you will see that there are variables in which you express your answer and this variable simultaneously involve

so that you cannot unpack scale field and gravitational field. So evidence of quantum gravity already is there. But I totally agree that

if you have gravitational waves, that would be cleaner thing. Yeah, it would be cleaner. On dimensional analysis grounds, it shocked me when you could show it. So it would be lovely and we'll hope. And if they're discovered, I'll come to your house with Champagne.

But I want to conclude with the multiverse, well, two-thip aspects of the multiverse. You know, the multiverse gets a bad rap from creationists because they say it's like God. We're just saying, well, you know, we can't explain why the world is except that if we were different, we wouldn't be able to be here to explain it. And this anthropic argument is kind of slimy, but may be true. And I think Stephen Weinberg was the first one to really, in my mind, make it clear that that it was, whether we like it or not, it may be true. And inflation gives a landscape with string theory,

but even without string theory, inflation gives a potential landscape to explain that what we see, our universe we live in, may just be an accident. And certain properties like this very small value for the vacuum energy, which we call a cosmological constant, which seems none of us can explain from fundamental principles, even though we've tried,

could just, be an accident of our circumstances. And, but, but I want to push back because we've had this discussion. I remember at a conference in, in, in, in, in, in, in, in, in, in, I like to be a devil's advocate, if I can be. And, and, and, and, and, and, and, and, and, and, and, and, and, and, and, and, and, and, and, I, I, I still think it's it's it's the argument is that the only way to understand a cosmological constant this weird value of of the vacuum energy of the universe is with a multiverse and it certainly is the best argument but but this argument that that that you can't could only have life

in a universe that has a small that we'd only be here in a universe that has a small Cosmole. That argument I don't think holds water. And you agree with me now? I mean, because we don't know. It all depends. It all assumes that we are typical. But I like Star Trek. And I've already seen that we may not be typical. Define the we. Okay. Let me explain what I mean. There is a, there are several different ways of understanding anthropic principle. And I may tell you that until I've seen how it is realizable in chaotic inflation, I myself would just say that this is garbage, this is just like that. Well, but one possible interpretation which I like is a correlation, okay, correlation between you and the part of the universe where you can be.

but if you have, for example, artificial intelligence based on a completely different type of machines, whatever, and you call it life, and this life does not require your oxygen and carbon, whatever. You can live without stars producing oxygen and carbon. So many, many constraints, anthropic constraints appearing there would be totally invalid. Yes. And then the issue will be then. between this kind of intelligence and its environment, the correlation allows for them to live in a different environment. And at the moment when you say that parts of physics, at least, are environmental,

then you say, what I'm studying is my environment. And my environment must be consistent with me being possible to observe it. And there is nothing chivalistic about this, like, we are the best and they only. Okay, so it's usually, anthropic was unlike these animals. Okay, no. Unlike bacteria. Oh, no, but there are so much more bacteria than men. Well, so that's how it is.

So as long as you have some sense of humor and understand limitations of language. in this and be careful in not saying nonsense but really talking about correlations, then you are not offending any sensibilities, I hope. There is a correlation between me and not being able to live inside the ocean. Okay, I cannot. Yeah, exactly. But I think that's fine. But the question is, yeah, the bottom line, I guess, is,

I don't, I think it allows the possibility, but not the proof, I guess is what I'm saying, is that it certainly makes it possible. But it could be that most universes have life that's quite different than us. It still makes us small probability. It doesn't mean it's most likely that we're here. We're here. And if there are an infinite number of universes, then the universe that allows us to be here, we'll be here and we'll find ourselves in that universe. And it's not too surprising. But the big problem, I think you'll agree with. me is we don't understand the possibilities for life. We don't understand the underlying, if you want to call it, phase space. And when you have infinities, talking about probability

tends to be often a matter of beauty in the eye of the beholder rather than good mathematics. When you have infinities, you can come up with all sorts of arguments. This is correct. Okay. And it is correct. mathematically and it is correct also with respect to our own position in the universe because we may be conditioned to think that we are well here we are and we are the most intelligent people so far until this chat GPT for a period in the existence therefore must be very special and therefore we must understand the property of the space where such a grandiose, well, thinkers like we are, may exist.

Okay, but that's an arrogant attitude. If you, however, make it more modest and say that I just want to study, given that I first know something about myself, given that I know that I need carbon and oxygen, and I need, well, the planetary systems which are relatively stable, all of these things, then what kind of other properties of our universe are necessary for that? And if I find that some of the properties can be different and some fit to our existence, I say, okay, at least I do not have a headache with this aspect.

I will try to solve other problems. because there are many problems which cannot be solved this way. Yeah, that's why. So I will nevertheless sometimes start thinking, what if I do it differently? Okay. And that's what we're doing. So you cannot forbid us to find a better, easier, more universal solution, which may eventually occur to us, just like, well, all of these years of strange discoveries teach us

that sometimes you do not expect it and something which is believed to be forbidden actually is okay. So I would not make any strong bets. I'm just saying that one thing about this, that if we do not say that we must understand what is the best universally for everyone, the best place in the universe to live

and why it is most probable for everyone to live there, I think that this is stupid. Okay. But if we say for us, then we can use this as a part of our data, okay, taking ourselves as part of data. Another thing about probability, in general, if I have infinite box of oranges and infinite box of apples, then who I am to say which one is bigger. So I would say that there is.

two parts of it. The first is about eternal inflation. Honestly, there could be some hidden problem in calculations which we do not recognize because, well, we just started doing it. We do not see anything stupid in it. Calculations seem to be right, but maybe there are some conceptually incorrect. Second, there may be no string lands K, but it's one plan. Oh, sorry, there is no consistent theory of dark energy so far with this one one. Or if you have one, then probably in string theory you have many different theories. Okay, everything again. So we do not know what happens really there.

And can we really have this multiplicity? It's just all string theory is like that, but who knows what will be the real theory is. It's interesting nevertheless to explore this. possibility that you have this landscape. But if you are trying, if you just say that this is possible. Like in 93, we developed some special, with two different measures of probability in the landscape.

But we were careful playing with this because we simultaneously was played with boss and explaining, look here, we clearly see that it is not sufficient for us to predict anything. One of them, we cut the universe, in the slices of a given time, commune in time with us. In another, we use time like a degree of expansion of the universe. And these two different times, so they're all legitimate in general theory of

reveregrieved, they give two different answers. So clearly we are doing something wrong. Okay. Now people who you want to say something bad about inflation, they're welcome to use one. of these two measures because we invented two. One of these measures lead to completely idiotic predictions and Tegmark founded in 2004, that we must be then, most probably there's

a strong youngness paradox, showing that we must live in the hot universe now around us, the hotter the better. Yeah. And with the second measure, it will not be that, but maybe there will be some problems, some people love it. In 2007, though, I realized that maybe there is a way of making peace with both of them. If instead of cutting them like that, you sort them by processes.

Because the way how we sorted, sorry if I am going too much in the garb or whatever for everyone, but we are trying to order these infinities. We are trying to sort them by cutting the different times. And we found that the probability distribution becomes stationary with respect to time. So if we say that in this section, red and green universes like 1 to 10, then the next section it will be also 1 to 10. And this was very convincing for us that we are talking something clever. But then I understood that it is slightly dishonest. And dishonesty was hidden, so it took me like 15 years to realize it.

And what happens is that when we're talking, just like with simultaneously in special theory of relativity, we learned in my car. Okay. So it looks like an obvious concept, but one should be careful sometimes, okay? And so the same thing with this cutting. It's like, you know, the tree is growing and produce you apples. And another tree grows and produce you oranges. But the orange tree takes more years to start producing oranges. So you do not cut the trees at 10 years after they grown and compare how many oranges.

Okay, because when they approach the stationary. regime. Then they will continue starting producing the same amount of but you must start counting time from the moment when each of them approached maturity when the trees start producing oranges. What we were doing we were cutting trees

without any fruits and we're cutting fruits later. So it was okay so what I found that if you start measuring it at the time corresponding for each process at the beginning of the moment when this process becomes stationary, then suddenly the results don't depend on cutting, don't depend on the time which I'm using, and all of this youngness paradox and Wolframed brains, they just disappear. But not many people know about this.

Well, look, I think, I think, I think as you point out, The subtleties of this discussion are probably beyond people. But what I think they point out is at the edge of knowledge, which I have to say is the tale of my new book. There's lots of things we don't fully understand. And the multiverse opens up a lot of things which we're trying to understand. And sometimes statements are made that are a little too strong. And I think I'm happy that you and I both agree that it allows something to be possible,

but proofs of things are very difficult when you don't have an underlying theory. You can look for plausibility. You can look for possibility, and there's a difference between possibility and plausibility, and there are still big arguments between different people, sometimes between me and me and you on what's plausible and what's possible. But this possibility that there's many universes opens up

a vast new way of thinking about nature that is still uncertain, and the principle called the anthropic principle is largely a principle of ignorance rather than knowledge. And hopefully when we learn more about the underlying theories, we'll be able to we'll be able to see which of these arguments are really worth trusting and which aren't. And it's exciting. And I think, as I say, what's really for me, the most fascinating thing is inflation gives you a physical reason why we should have these discussions. When people say, and I've often debated religious people who say, well, the multiverse is just your way of replacing God. And I say, no, the reason the difference is that we didn't invent the multiverse to solve the problem. We were

driven to it. Most of us didn't want it. And it happens to be a way that we may, like it or not, it may be the way nature is. And we weren't, we didn't invent it because we loved it. We were driven to it and inflation drove us to it and i don't think anyone you as much as anyone would have liked a multiverse 40 years ago it came out of the equations rather than being put in i know that um you said that when you grew up in in the soviet union that religion was suppressed and it was kind of depressing for you to go back and see how religion has taken over so much of the of russia Maybe you want to comment on that briefly. Well, it just seems to me that there are so many great ideas in culture of every religion.

But then there were also lots of evil associated with, well, making some statements. of associated with this religion to close to the heart. So it's a dangerous game. And if we were previously, at least in Russia, we were all conditioned that you shouldn't talk about nonsense. And then the pendulum swings, and then suddenly you feel yourself in a completely different environment, the bad thing about it is to depend on pendulum swinging. The best thing you can do is kind of dissociate yourself

from the pendulum and think yourself and then whoever comes with better conclusion, maybe it will be like that. I remember how I came with this whole city with the name Santa Barbara, which I cannot remember. At the conference, where several really brilliant people would gather it soon after the discovery of string theory landscape and Kikilk and

some of them asked me so what do you think about this string theory landscape and I say it's just great and I start explaining and how I like this and how I like this and one of them well-meaning person

looked at me and said what a point like that is and you are the worst. And I said, oh, then this means that I'm telling something interesting. Okay, so who knows? Who knows? I think your idea of not depending on the pendulum, whether it's religion or fads in physics.

But think for yourself is a good motto. And it would be a wonderful way to end, except I'm going to ask you one other question. Because I want to give you a chance to respond. you know I talked to, we went, Alan Gooth, right after I talked to Roger Penrose, and you know, the biggest critic of inflation is Roger Penrose. And, and I will say, I reminded, let me, let me, let me phrase this. One of the things you point out, besides the fact, at the same time as you talk about, I know you've talked about the fact that the universe can come from nothing,

something we both agree with, and, and as I say, has been good for both of us. But you point out that the interesting thing is that normally order in, in, in, in, it when we normally think of physics, order turns into chaos, it's called thermodynamics. And what inflation does is starts with chaos and turns it into order, in a sense. And that sounds very suspicious. It sounds like it violates the laws of thermodynamics. And I think it's what has driven Roger Penrose to argue there's something fishy here. So what I'd like to give you the final chance is to say,

why his objections, in some sense he would say that embedded in your equations, even though improbable regions grow exponentially fast, somehow there's an inherent improbability and the end result that we're assuming is incredibly improbable. And it has to do with thermodynamics. And he would argue this. And I want you to give you your car. I want to give you a chance.

I've given Alan a chance. but I'd like to give you a chance to counter Rogers' argument here, if you want. Maybe I should say first a general thing. I am very much afraid that when I will grow older and I already did, I will make judgment on different fields in which I cannot work because it takes so much time for me to learn new things already and when you're getting older, you still remember some names, stuff, but learning new things, participating in new developments, becoming increasingly more complicated, and therefore there is an easy way out, and that is

to assume that these other fields somehow are wrong and not in interesting. And I remember discussing it with Roger a long time ago, well, when I was still in Moscow. And already at this time, he was at this stage. He is absolutely brilliant. His works on mathematics and on cosmology, they're fabulous. When I was a student, I was learning about that. But at some moment he will start making statements concerning everything. And it is really necessary to jump inside, work there, and then maybe learn the new way of thinking. So I'm afraid right now, already I'm close to this state, then I'm looking at what others are doing and say, no, physics is in crisis, whatever. So I'm very, very much afraid

of myself to go to the state prematurely. But returning to that, one of the things which come natural to, well, people of generation, which came before inflation and did not learn the new set of ideas, is that you have these particles existing in the universe like protons, okay? And they probably something like that maybe exist before the singularity and then it came out of the singularity maybe or whatever it is but you already have them you have them turn to the 88 protons in the part of no no no no much much less okay now you see it's photons 10 to the 88 right yeah okay and so we did not learn not about

inflation, but we didn't learn, or some didn't learn. The proteins could not maybe even exist when the universe was just born because their number is not concerned. So our preconceptions of what is most natural for the universe, there was something there which existed. So this idea that there was something there, it is possible, but then write your theory. Okay. And then write your theory and show how this something went through the singularity and appeared there. We cannot do it even with a black hole. You throw the chair in the black hole. We do not expect that the chair will appear from the black hole.

You get some noise. We go to the cosmological singularity. The universe crashed through the singularity and you accept, well, expect the same universe to emerge there with all the same entropy. everything, that's kind of interesting, but you come with a theory. But if you do not have this description, then let's just limit ourselves to something simpler. Even just reduce the level of being pretentious that we are close to God who tell us the last piece of knowledge. Forget even about eternal inflation and stuff. You want to explain what happened. later, like already long after eternal inflation is ended, etc.

Let's make a minor, minor tiny assumption that for whatever reason, scale a field in this part of the universe, well, it was still more than 60 foldings for the universe to grow. Was in this state. Can we make a reliable prediction? Yeah, I can. Does this reliable prediction really depend on what happened in than previous foldings? No, not much

so. Can you studying the present state of the universe? Really go back to the singularity. Well, I can prove that you cannot. Okay? Because, and then you go back to the universe,

taking our part of the universe and smashing it back 60 foldings and smashing it back another 20 following the soul. And then all structures which exist right now become subplankan. There is no memory of what is happening there. You cannot see the singularity because our measuring tools do not allow us. So suppose you do not know anything about the singularity.

What we know, however, if we make some assumptions about what happened later in a peaceful part of this evolution, you can make unambiguous predictions in our part of the universe. If we fit the data, great. Does not disallow us to speculate about the origin of everything. Because if you have the picture of everything, so the greater. So we are going to continue doing this because it's the most exciting. You don't want to die without knowing everything. Well, what can I say?

Probably this dream will not be. satisfied, at least in this life. I would say to, I would say amend to that in a different way. As I've often said, as Feynman would say, if the universe is like an onion and you keep peeling back and each time they're in infinite layers, it's not bad because what it does is it gives us cosmic job security. Because if we knew everything, then we could just, then we wouldn't need to, then we'd have to pack up our books and go home. And I think as long as we realize there's probably more to learn. it's exciting and it gives something for young people some motivation and that's why in fact

I would argue that not knowing which is one of the properties that drives us all as scientists is the joy of not knowing and the whole time to discover something we knew that we didn't know before these artificial intelligence with this goal of requiring more and more intelligence that's so interesting look look all I can say is I think there's some wonderful morals to end this with. Morals, as in the morals of a story, not the morals of what we should do and what we shouldn't do. The one is that near-death experiences, things that make us very uncomfortable are not always so bad. And sometimes they can lead to really good things.

The other is not to be governed by the swing of a pendulum, but to think for yourself. And the third is to be humble about what we do and to accept that the things we don't know and just try and work with what we have and then discover something new. And I think the story of your scientific career is a great demonstration of how all those three things can not only lead to great scientific progress, but to a happy and jovial existence, which is very clear for many discussions we have. And that's one of the great things of the joy that I have. always talking to you is the fact that we both end up smiling and to me that's the wonderful

wonderful thing so i thank you very very much for taking the time and patience and i i have enjoyed as always enjoy this tremendously and i think i think everyone i hope everyone who listens to it will enjoy it as much as i have so i thank you very much and thank you very much i enjoy it too i hope you enjoyed today's conversation this podcast is produced by the origins project foundation a nonprofit organization whose goal is to enrich your perspective of your place in the cosmos by providing access to the people who are driving the future of society in the 21st century and to the ideas that are changing our understanding of ourselves and our world. To learn more, please visit Originsprojectfoundation.org.