Into the Impossible With Brian Keating - Neil Turok: Most Theorists are WRONG! (#262)

Episode Date: October 2, 2022

Renowned physicist Neil Turok, Holder of the Higgs Chair of Theoretical Physics at the University of Edinburgh, joins me to discuss the state of science and the universe. Neil Turok has been director emeritus of the Perimeter Institute for Theoretical Physics since 2019. He specializes in mathematical physics and early-universe physics, including the cosmological constant and a cyclic model for the universe. He has written several books including Endless Universe: Beyond the Big Bang and The Universe Within: From Quantum to Cosmos. Topics Include: Discussion of Niels Books The life and discoveries of James Clerk Maxwell and Michael Faraday What's wrong with physics today? Fundamental laws of the Universe in equations. Existential Questions on the meaning of life, advice to his former self, and things he's changed his mind on.  Make sure to watch the video for Neil’s PowerPoint slides here:  Connect with Brian Keating: 🏄‍♂️ Twitter: https://twitter.com/DrBrianKeating 📸 Instagram: https://instagram.com/DrBrianKeating  🔔 Subscribe https://www.youtube.com/DrBrianKeating?sub_confirmation=1 📝 Join my mailing list; just click here http://briankeating.com/list ✍️ Detailed Blog posts here: https://briankeating.com/blog.php 🎙️ Listen on audio-only platforms: https://briankeating.com/podcast  Subscribe to the Jordan Harbinger Show for amazing content from Apple’s best podcast of 2018! Can you do me a favor? Please leave a rating and review of my Podcast:  🎧 On Apple devices, click here, scroll down to the ratings and leave a 5 star rating and review The INTO THE IMPOSSIBLE Podcast. 🎙️On Spotify it’s here   🎧 On Audible it’s here Other ways to rate here: https://briankeating.com/podcast  Support the podcast on Patreon or become a Member on YouTube Learn more about your ad choices. Visit megaphone.fm/adchoices

I want to emphasize that most of what theorists do is wrong. And one of the main sort of, in my view, most important things about a theorist is they should be willing to recognize when they've gone wrong. Thank you, everybody, for joining me today on what is going to be a mind-blowing, a mind-expanding conversation with the inimitable, the redoubtable, the incomparable, Neil Turak, well, I've known for decades now, although I can't believe it. He doesn't seem to age. And we discussed so many fascinating topics that we actually had to agree, as you'll hear, to a part two episode and maybe even more. And I hope to visit him in Edinburgh at the end of, or maybe beginning of the next year or so. Maybe I'll do it in person. That'll be super fun, right? But this conversation incorporated our description of the early universe in an alternative paradigm to the dominant inflationary universe paradigm that listeners to this podcast know him love.

We talked about arguments why his friend Sir Roger Penrose, past guest on the podcast, could have been spectacularly right from the beginning, but abandoned his quest to understand the low entropy conditions of the early universe in favor of what Roger calls the conformal. cyclic cosmology and why Neil thinks that's wrong. It's pretty fascinating to hear him kind of not anything other than respectfully criticize his former mentor and our current mentor and friend of the show. We talk about quantum mechanics, consciousness. We even got into alien life in the cosmos and how tectonic plate movements lubricated by life itself are really crucial to the origin of technological life on Earth. But that had to be relegated to part two to get into more detail. For now, I want you to really sit back and enjoy this. This will be a two-part episode. In part one, we get into the fundamental parsimony, the economy of the physical

laws of nature, and why Neil and his colleagues think the universe may, instead of being complex, baroque and overburdened by parameters, might actually be incredibly simple. And you'll want to stay tuned to part two as well. So for now, I bid you entry into part one of this thrilling two-part episode with the Higgs inaugural chair professor of theoretical physics. That's right, that Higgs that we spoke about with Frank Close, Peter Higgs, who's a friend of Neal's. And we talked a little bit offline. I got some dirt from Neil about Peter Higgs and all of his ongoing activities. Such a delight to learn about Higgs and really talk to my friend, Neil. So sit back, relax, enjoy this voyage into the impossible.

My friend, Neil Turak. Any sufficiently advanced technology is indistinguishable from magic. Welcome everybody to an episode that is coming to you, courtesy of audience demand, as well as host demand. And it is with a renowned theoretical physicist, cosmologist named Neil Turak, who I've known for decades, since he's been so kind as his want to mentor thousands, maybe millions of people around the world. And as a young grad student, I met him when he first came up with some of the ideas that would later encourage experimental cosmologists, such as myself, to pursue a unique signal in the cosmic microwave background that we'll get to called B-Mode polarization.

And Neil did some of the definitive work on that. He's also collaborated with good friends and friends of the show like Paul Steinhart and Aegis. and others. And today he is joining us all the way from Edinburgh, Scotland, and that is Neil Turrock, renowned scientist. His official bio is sometimes out of date, but it is reading as follows. He is the director emeritus of the Perimeter Institute for theoretical physics, and that he became emeritus in 2019. He was there much longer than that, or I spent many weeks visiting with him and his colleagues and he originally originates his personal big bang came in south africa and johannesburg and we'll maybe get to some of that how that his early childhood influenced him in san diego

and neal you may not know this but i have to get you here we have a huge south african population i don't know if you've ever been to lojoya but it's it's quite a stabing i have and i'm very jealous yes actually yeah they say cape town is more similar than johannesburg but but But at any rate, he is also the holder of the inaugural Higgs chair of theoretical physics at the University of Edinburgh. And he has been there since 2020. He obtained his PhD way back when in 1992 was it. He was a postdoc at Fermilab and Santa Barbara. He's one of the Maxwell Medal.

He's written many books. He's worked with the only one of the few guests I never got, besides your fellow South African, Elon Musk, I hope to get him someday, Neil, if you can put in a good word. But Stephen Hawking, who I barely missed getting maybe a few years back. But that's for the ages. At any rate, I want to ask you, first of all, I want to thank you so much for joining us. And you are seriously here in part because of my strong desire, but also because the audience was basically begging for it. And we'll take audience questions in just a bit.

Okay. So, Neil, we always start off by asking authors of phenomenal books such as yourself, along with your co-author and past guest Paul Steinhart, we always ask you if you're willing to play a game that we call judging books by their covers. So you're never supposed to do. But you wrote, along with Paul, a phenomenal book called Endless Universe. And in fact, that's the title of this episode. And I want to ask you, we'll get into all your incredible, delightful work, but that book is a popular book. And I want to ask you, what is the meaning of the title of the book and what is the cover meant to evoke in the minds of readers?

And we'll show a cover over this. So can we please judge your book by its cover? Okay. Well, the book was really trying to convey how exciting it is to be able to make models. of the entire universe and its entire history, and then test those models against real data. And so I'm always very clear to differentiate between theorists, which I call imaginary people,

and experimentalists who I call real people. Thank you. That's a little bit of a joke on complex mathematics, where you have real and imaginary numbers. But that's really the way I see things, is that the theorist's job is, of course, to benefit from the incredible observations which are made by people like you. Think a lot about them. Try to make mathematical models which fit them. And ideally, which make more predictions, which then people like you can check.

I want to emphasize that most of what theorists do is wrong. And one of the main sort of, in my view, most important things about a theorist is they should be willing to recognize when they've gone wrong. Put themselves up to scrutiny to test both mathematical and observational. and if either fail, move on to a better theory. So although that book, I was very excited at the time, we had a theory which was connecting the Big Bang with string theory and a development of string theory called M theory. I was excited about it at the time,

but I have to say the more I thought about it, the more I doubted its foundations. And so although I was excited about Endless Universe, I've written another book since called The Universe Within, that is actually also a popular book, which again tries to give a picture of what it's like to think about the universe. But what I'm really excited about now is almost the opposite of what's in the endless universe, which is that the point, the main point, is that observations of the universe,

made by people like you, have revealed something incredible, which is that the universe is unbelievably simple. And by simple, I mean very economical in what it takes to describe it. You just need five numbers. And so far, there's no evidence for anything more than those five numbers. Whereas when we look at our theories, they have become unbelievably complex, arcane, a million assumptions and fixes.

And starting about five years ago, I basically decided this has all become a bit of a joke, to be honest. What we should be doing is being strongly guided by the data to constructing much simpler models of the universe. And by simply, I don't mean less precise or vague. or anything like that, I mean that basically the evidence is we've been missing something. And I'll go into detail about what that something is.

And once I made this switch, as I said about five years ago, I said, look, I'm just not willing to build these arcane models anymore. I'm going to be ruthlessly self-critical, meaning that I'm not willing to introduce even one extra field into the standard model. Standard model is basically a well-verified picture of what we know about physics. I'm going to be extremely reluctant even to introduce one new ingredient. By that assumption, I'm just ruling out all the models that have been developed in the last 40 years. Everybody's been introducing extra fields, extra particles, extra dimensions. You know, and what did we end up with?

We ended up with the multiverse, which is, is the least predictive theory ever. Okay. Most predictive. Well, it predicts, yeah, it predicts the most, but it's the least testable, let's say. Whereas the evidence, both on the very large scale and on the very small scale,

has gone in the opposite direction. So the large Hadron Collider, you know, the greatest experiment ever built, discovered the Higgs boson, and absolutely nothing else. Okay. So most theorists like me, 99% of theorists, are extremely disappointed at that result.

Oh my God, everything we've done for the last 40 years has led to nothing. There's just no extra particle to be found. And I'm exactly the opposite. What my interpretation is that nature has been smarter than we have been. And nature figured out how to get away, with just having the bare minimum,

the Higgs boson, which is necessary to make standard physics work, and no more. So on the tiniest scale, we have this surprising economy in the laws of physics. On the larger scale, it's the same thing, with plank satellite,

subsequent experiments, your forthcoming, very exciting experiment with the Simon's Observatory. You know, so far, these have revealed nothing new. That's not bad. That's a huge challenge for fundamental physics. It says to us, maybe we're working on, you know, a questionable set of assumptions.

Maybe there are principles, very economical, very powerful principles, which we haven't yet figured out, which will resolve the paradoxes we have. such as the dark matter, the dark energy, the Big Bang itself, what goes on in black holes. They're very, very basic paradoxes. And maybe we just need to think a little harder. So after I've started following this line of research about five years ago, it's very difficult because you've essentially tied your hands together.

I'm not allowed to introduce a new particle, okay? But we've made amazing progress. At least I find it amazing. We've realized what the dark matter is. It's probably a right-handed neutrino, which is already there in the standard model. It's extremely economical explanation. We've found, this is something I'm most excited about recently,

a new explanation for why the universe is so simple on large scales. You know, the geometry of the universe. What is the universe like on large scale? Well, in first approximation, it's flat space. It's the thing you learn about in geometry in primary school. You know, there's X, Y, and Z. There's no curvature at all. Why is it the simplest possible geometry?

It's a huge puzzle, which motivated the theory of inflation. So now we have a new explanation. And the explanation is extremely economical. It doesn't make it easy to understand. but it basically developed Stephen Hawking's ideas about black holes. And we literally do a calculation of the thermodynamics of the universe, which I'll say very briefly, shows that just like the gas in a room

will distribute itself evenly in space, because that is the most probable configuration of the atoms. If you chuck them in with some energy, allow them to randomize, they will spread themselves out uniformly in a smooth distribution. You don't have to introduce somebody to smooth that or do something active, another field or particle. It just does it itself. That's thermodynamics.

And so we figured out the thermodynamics of the cosmos, using Hawking's insights and with no finagling, with new particles or whatever, with some very simple mathematical assumptions, we find the most probable universe is flat, exactly the geometry we see, and it's the simplest geometry. And so that's an entirely new explanation. It doesn't require any new ingredients. It will take people a long time to accept this, well aware of that, because people have built their careers for 40 years on differing different assumptions.

But I'm personally very excited about it. I think what we're seeing is a way through to explain all the puzzles, all the major puzzles in theoretical physics with absolutely minimal additions to what we already know. Well, there was a man who is an alumnus of Your Fine University, who had had a fair bit of experience with simplification, with unification, and with really constructing a strict mathematical model of the universe. And it worked pretty well, except for the fact that it was also based on very simple principles involving gears and vortices and whirlpools. And of course, we're speaking about the late great James Clerk Maxwell,

who's Italian and all of science. And maybe in the spirit of a Higgs or a Yang Mills or in the same way, what do you make of his ultimate? What he did, Neil, is so interesting because he was absolutely correct for all the wrong reasons. And we see that again and again in science. You see that with Galileo, he was right about universal gravitation, or Newton was right about how it propagated. Galileo was completely right about the orbit of the Earth around the sun, thought it was responsible for the tides. That proved it had nothing to do with the tides.

But tell me, Neil, is it possible sometimes that brilliant theorists can have the right idea for the wrong reason? And in that way, give us a glimpse of truth. And maybe could that be happening with inflation in the multiverse? just to be a little bit of a steel man. Yes. Yeah. No, it's a good question, and it's a big puzzle, why inflation in the multiverse have become so popular? Because objectively, this is a theory with an infinite variety of models, of lots of parameters,

lots of freedom, extremely hard to prove wrong. So on the face of it, it's a theory which isn't particularly scientific. Traditionally, it would be regarded as unfalsifiable and therefore not part of science. But what's happened is the field of theoretical physics has kind of been pushed into a corner where many of the luminaries, I mean, very great theorists like Stephen Weinberg, who, you know, was more or less a founder of our modern picture of physics and the standard model, came around to this point of view of the multiverse and inflation. And I always found that sort of surprising that they did.

But they did for, you know, what you could say were good reasons. I mean, there's a certain logic behind the steps people followed. But it's just a case of, you know, when you make a few, one false turn, and there's no kind of experimental check or insufficient experimental checks, you can very easily go wrong. And so I think that's what's happened. I think, in fact, around the time I entered theoretical physics, you know, in the 1980s, that's when the field went wrong. Okay. I'm not saying it was my fault. Your summer starts now with Memorial Day deals at the Home Depot. It's time to fire up summer cookouts with the next grill,

four-burner gas grill, on special buy for only $199. And entertain all season with the Hampton Bay West Grove seven-piece outdoor dining set for only $499. This Memorial Day get low prices guaranteed at the Home Depot. While supplies last, price invalid May 14th or May 27th, US only exclusions apply. See Home Depot.com slash price match for details. Stephen had something to do with it, I think.

Stephen Hawking had a little bit to do with it. He actually, in a brief history of time, which I went back and read after his death, he made a big deal about not only is there no boundary, is there no beginning, but that the CMB basically proves that there is inflation, there is a multiverse, and he really went quite, quite, and he's so influential. Although my first guest, my first ever guest on the podcast, was Freeman Dyson, who I loved and was incredibly influential. I'm sure you knew him when you were a professor of Princeton as well. And many interactions with.

He said the safest thing in life to do, Neil, is to make a bet with Stephen Hawking because either he was wrong, or he would eventually switch positions. So you'd win no matter what. But I think in this case, he really did. And then he went even deeper in his final book with Leonard Maloney. lot now who is a guest on the show. And he said M theory is basically accepted, which even as an experimentalist, I know that's not correct. So what do you make of this influential, you know, kind of these towering figures that really suck up all the oxygen and kind of mandate the direction

of the field like the Weinbergs, like the, you know, nowadays there's many of them, many young ones, and I don't want to criticize any of them. But there are very few working on what I would say are the flaws. Right. Also I hear, I hear this, Neil. I hear, well, inflation is not a theory. and the multiverse isn't a theory. It's a consequence of a paradigm. And I'm like, well, where do we go to hear about, you know, like, these are excuses. Honestly, they're just excuses.

And it takes some courage to say that out loud. I could really only do it because I was, you know, academically secure. I had a position. In fact, the reason I really came to my view that the field has gone, wrong is that I was director of Perimeter Institute, which was the fastest growing, best-supported institute dedicated to theoretical physics in the world. And so my responsibility was to hire young people who were actually going to make discoveries, you know, and I was committed to doing

that. And so I had to look very carefully at all the different fields of theoretical physics and weigh up the real prospects of progress. And during that, it put me in a very unique position where I sort of had to have an overview of the whole field. And based on that, I had to be objective because, you know, we were essentially investing, you know, in a place which had opportunities to invest like no other. And so what I decided,

is that going with the flow was absolutely not the way forward. And so I made that decision in my capacity as director. I also made it personally in my own research. And because I had the freedom with my own research to go down whatever path I wanted, this really made me rethink everything. So now you asked about Maxwell. Maxwell is an amazing example. What happened historically was, you know, he was a product of his environment.

Edinburgh and Scotland at that point, it was the age of Scottish Enlightenment in the 18th century. And they questioned everything. They questioned, you know, Big Brother in England. England had two universities, Oxford and Cambridge, and Scotland had three. Okay. And the Scottish ones had a totally different philosophy, which was public access. So no matter which background you came from, bright kids were very strongly encouraged to go to university. And so in this environment, people, essentially the mentors of Maxwell were trained and, you know, blossomed. So people like David Hughes, Adam Smith in economics. These people rethought everything from scratch. Okay.

And so that was the culture Maxwell was raised in. And being very bright, he then went to Cambridge. I mean, he went to Cambridge after he made his discovery about light and electromagnetism. But he was absolutely unafraid to challenge the orthodoxy. And you're quite right to say that his way of picturing the world turned out not to be, you know, what we use now. We take the mathematics much more seriously than we take the machines that he used to build the mathematics. But that

doesn't matter at all. I mean, the equations are valid. And I would say Maxwell's equations are actually guiding us to what happened at the Big Bang. Because they guided Einstein to his theory of gravity. Einstein said that. He's basically developing a version, a theory. for gravity modeled on Maxwell's theory of electromagnetism. Maxwell's equations tell you about relativity, the speed of light, ultimately told you about photons and quantum mechanics. And so, you know, Maxwell is sort of the inspiration

for modern theoretical physics. And part of my reason, in fact, of coming to Edinburgh is I feel it's a place with this amazing history of sort of breakthrough thinkers. And it's not too hidebound. Okay. Having spent time in Princeton, in Cambridge, you know, dot, dot, dot. I wanted to come somewhere where I felt there was an openness to rethinking the foundations,

because that is what I think is needed. If I could show a slide, I'll illustrate this. Let's do that. Let me cue you up. Okay, yeah, you should have your screen sharing permissions. There you go. All right. So let me just show you. Can you see my screen? Yeah, I see it. You want to push. Perfect. Yeah, perfect. Right. So this is all of physics in one line. It's an amazing achievement. We have gravity, which is sort of Newton in Newton's constant is here and Einstein and curvature of space. Now describes, black holes, which we see. Then we have Maxwell, that's this term, and the photons, all the forces which keep the particles together. Then we have the description of particles due to Dirac.

That's this Psi quantity here, and this is Dirac's formula. And then we have the Higgs. Okay. Now, it's quite funny that the Higgs, although it's a relatively simple thing, has three terms, in this equation. That's actually a minus because we always look for economy. And when you have, you know, long equations, it's usually a sign you don't really know what's going on. But anyway, there are three terms involving the Higgs. These are particle masses and these are the electro-week gauge boson masses originate here. And then the Higgs boson, which Higgs predicted. You can think about the Higgs boson really is the water which the particles travel through. And because the water provides some resistance to the particles, it gives them mass and stops them moving at speed of light.

So here is everything. Now in this formula, you'll see it's mathematical. There's E, E, oilers number, 2.718 dot dot dot. That's just because exponentials, are right in the heart of physics. You know, exponential growth is what we use in inflation, describing economic inflation, for example, exponential growth of populations. In physics, you get an exponential, but it's of a strange number whose square is minus one.

And, you know, non-physicists always find this extremely worrying. It's called the imaginary number. But this was discovered in the 1500. hundreds by some Italians that if you introduce this imaginary number, somehow you can solve an infinite number of equations much more easily. And so this imaginary number lies at the heart of physics, quantum physics. In sort of physical terms, you can say that all of physics is just interference. These are called phases, and you add up the phases and they interfere.

And that's everything. So here are all the laws of physics. Now, why do I say we have to rethink this? The reason is that we actually don't know if this integral, it's a very beautiful thing. It's saying that you allow, so if a particle goes from A to B, you actually allow it to go anywhere on route so it can go to the moon and come back.

And then what you do is you add up all the phases for all of the paths, and they interfere, typically they interfere destructively so the particle doesn't go there, but you have to add them all up anyway, and that gives you the amplitude to go from A to B, and then you square it and you get the probability. So this is a beautiful formula due to Richard Feynman.

All the known laws of physics are compatible with it, but a very long-standing puzzle is whether this formula actually makes any sense. The reason is, is it's very infinite this formula. You know, the number of ways of going from A to B is infinite, and you have to very carefully deal with that infinity. And so actually that's a puzzle which I've been working very hard on

in the last couple of years. We think we have a nice way of dealing with it. But I have to say that this formula, although used everywhere in quantum physics, is without solid mathematical foundations. And so I've come to the point of view that making sure we understand those foundations is actually critical. So what is that, though, Neil? Is it an interpretation? I've heard things like Einstein. I mean, Einstein would say so many different things, of course.

Yeah. Sometimes they're mutually inconsistent. I mean, he would talk about time. And then he said, you know, time is doomed as an illusion to fade away. And I've never really understood what that meant. But I guess the question for you is, is this, is this, you know, kind of a totology, this equation, that basically you're using math, but essentially you're saying it's inconsistent. We don't understand it. And it's not just because as past guest, you know, Michi Okaku says, well, you know, string theory is just the same as Maxwell's equations, both have an infinite number of terms. And you have to tell me what the vacuum stand is. I said, that's not my job. My job is to prove you wrong, not to prove you right. Right. So what do you mean that it's inconsistent or that it's, you know, is it philosophical?

Cole, where are we going? No, no. No, it's a very, so if you ask, if you ask any sort of honest theoretical physicist, how do you justify using this formula? The first thing they will tell you is, if they're honest and sort of rigorous, is that you've got to get rid of this imaginary number by rotating time to imaginary values. Right. As Hawkins, this is a great.

That's what Hawkins said. The wick rotation. Very powerful trick. Okay. And it's actually used. And the reason you need to do it is because it removes the oscillations. You see, what this formula tells you is you've got to add up all these phases. The way physics works is these phases interfere.

This is like, you know, two water waves, like a water wave, encountering a barrier with two slits in. and the water wave continues through the slits, and then these waves interfere. And you get basically beautiful pattern, what we call interference pattern, but you've got to keep track of these phases properly, and that's very difficult. So usually people just remove them by changing time,

making time imaginary. And I, Stephen, you know, taught me this method. I used it to study gravity, and we discovered it fails. It fails miserably. But in this book, Neil, of course, he says, I'm going to introduce it. It's just a trick. And we shouldn't take it seriously. And then later on, he bases the whole no boundary, you know, hawking harness on this trick.

So what is it? Is it a trick? Well, it is a trick. It is a trick. And hawking, to his credit, was always looking for the very simplest way to explain. to explain anything. And his no-boundary proposal is an extremely beautiful idea.

It basically says, why is the universe the way it is today? Well, we don't prejudice that in any way by assuming anything about the beginning. We allow it to do whatever it likes to do in the past. And his no-boundary proposal was that there was no boundary

in the, quote, beginning of the universe. So you sum over geometries which are smooth and sort of round off nicely in the past. The virtue of it was that it was mathematically precise and principled and very appealing, very economical. The problem was that when you calculate it in detail as we did, this would be three or four years ago, we found it is mathematically inconsistent. So now, Hawking, to his great credit, was open to the criticism. I invited me to a private retreat.

I went with a whole bunch of with him and a whole bunch of his collaborators. We discussed it in detail. And I wouldn't say, I can't say Hawking accepted it, but he didn't argue against it. And then when his collaborator, sorry, you just mentioned his name. James Harle. No, the one who wrote the popular books with him. Oh, Leonard Malad now. Yeah, Leonard not enough. He's written a recent book about basically what it was like to work with Hawking. And in that book, he explains how he asked Hawking, what do you say about Neil's work? Because it directly contradicts your No Boundary proposal, and Neil is claiming it's wrong. And Hawking was unbelievable.

generous. Hawking said when you're a theorist, most of the time you're wrong, and when somebody shows that, points out a flaw in your assumptions, you have to be grateful because what they're doing is actually saving you time. You don't want to waste your time on a thing that's wrong. I mean, if you read the quote in Lodinoff's book about our work on No Boundary, you have to come away saying Hawking was amazingly scientific and generous. Generous, gracious. Yeah. Gracious.

So the way I would describe what I'm doing now is trying to implement Hawking's idea because I think it's the most beautiful idea for the beginning of the universe, whatever that means. I'm trying to implement it in a way which is consistent. And if I have time, I'll show you some pictures of how. we think it it yeah let's go there now because you have the screen okay yeah so so main picture from main uh take home from this slide i mean it looks like a horrible mathematical equation but it's describing everything all the laws of physics in one formula as i say that our task is

there is really to make sure this equation is meaningful yeah um and uh and and that's what i'm i'm i'm done. I should say my listeners, so about half the audience, we have 100,000 people into the impossible family, about half of them are probably listening on audio only. So please make sure to visit Dr. Brian Keating. To see the slides, but also look up a video by Neil Turah called the astonishing simplicity of the universe. It has several million views. And it is really a renowned kind of introduction to some of these ideas that Neil's exploring from a few years ago when he was first grappling with them. So I want to point that out. But we'll endeavor to discuss these topics in more detail. Now you're showing Peter Higgs's paper. I think this is his first paper

these so-called gauge boson. So yeah, let's explore this equation. Thanks, Brian. Yeah, the lecture is called the astonishing simplicity of everything. Yes. And as you say, that's really when I was first beginning to explore these ideas. Hopefully today I'm going to tell you a lot more detail about where we've been led. Now, I want to point out Peter Higgs paper. This is the entire thing, right? This is the paper that won in the Nobel Prize. It's one and a half pages. And the funny thing is I gave a talk at Princeton. I don't want a badmouthed Princeton too much. But, you know, they can take it. I gave a talk at Princeton a few years ago. And I had, when this Higgs boson was just discovered.

And I was celebrating this. You know, somebody comes from left field with a new idea about this, the way of how you break symmetry. And then 50 years later, right, it was almost 50 years to the day, what they predict, you know, was discovered in nature in a 10 billion euro machine. You know, it's just an amazing story. And in fact, what won him the Nobel Prize is this one line in the paper. This is the Higgs boson.

This is its mass. Okay. And so now here is Peter Higgs. Okay. He's still around. I see him regularly. He's quite ancient and housebound now. But very gracious individual.

Here he is in the biggest experiment ever. conducted, the large Hadron Collider, and he looks like he knows what's happening. And I can assure you he has absolutely no idea how this thing works. We only let theorists into the experiment for publicity shots, Neil. You know that. Exactly. Exactly. So, and that doesn't matter at all. You know, his job is to think through, you know, what makes sense. And that sounds easier than it is. It's a tough job because these things which are going on are extremely remote from any of us, you know, very hard for us to picture in our minds. We have to use mathematics as a guide because it's our only sure way of checking that the logic is correct.

And that's what he did in 1960. You mentioned Princeton and I'm waiting for the, you know, for the clause to come out. But Frank Close, it was past guest, first guest on the, podcast, Freeman Dyson, who invited Peter to come to the Institute for Advanced Study in the summer when he was on sabbatical after this paper that really gave him the courage. So I'm curious to hear what was the what's the essence of the of the gentle kind of prince? We ought to have a little bit of spice on the podcast. Yeah, two things. So actually when Peter was a young lecturer in Edinburgh, he had a PhD student who got an offer from North Carolina at Chapel Hill to go for a postdoc.

And at that time, Bryce DeWitt was the head and it was a famous place, you know, nuclear physics lab, one of the most prominent places. There was a gravity. Exactly, huge guru at the time. So the student decided to leave physics. And so Peter wrote to Bryce DeWitt and said, can I come instead? So he went to Chapel Hill as a postdoc. He offered, a very shy person, by the way, Peter Higgs, very shy, very modest, went to Bryce DeWitt and said,

could I give a seminar about this idea about symmetry breaking? And Bryce DeWitt said, well, explain it to me first. And so he did. and Bryce DeWitt, who was like the world expert on quantum field theory and everything related to this, said, no, it's nonsense. You can't give a seminar. You'd be wasting our time. And so Peter never gave a seminar there. And then, as you say, Freeman Dyson invited Peter to Princeton and then the rest is history. But the reason I mentioned Princeton is actually I showed this slide.

And to my great surprise, at the end of my seminar, a number of the prominent gurus in the field who were there came up to me and said, oh, you're giving him too much credit. You're giving him too much credit. What he did we now see is kind of trivial. Goldstone was there first. They had a whole number of arguments. but basically it was, you know, so which I was just shocked at,

because to not recognize that us, to refuse to recognize that an extraordinarily simple idea, which everyone else had missed, by the way, suddenly brought things into consistency, you know, and to be grudging about that, I just found extraordinary. But anyway, that's their choice. And Princeton is now the hub for string theory, the multiverse, you know, all supersymmetry, all kinds of complicated ideas which so far have no experimental evidence at all. And so it's quite clear who won that particular debate. You know, the Higgs boson was found.

nothing else what has been found. None of these other theoretical constructions have been found. Now, I sound a bit like a commodging, but I'm not. No, I know. Here's the wonderful story. 50 years and 10 billion euros later,

they built the biggest experiment of all time, and they found the Higgs boson, and there's Peter Higgs chatting to the other Nobel Prize winner, Francois Angler, also an extremely unusual and creative personality. So I think what I wanted to...

Just before we go to the next, which I assume is going to be on cosmology, you know, back in the 80s and 90s, when I started grad school in the 90s and met you for the first time. As a dapper young professor, I remember you visiting Brown University at one point, and then we visited you in Toronto.

But the, but back then, there was a pejorative coined first by Alan Sandidge, who called cosmology the search for two numbers. And I kind of poked and prodded at Frank Close in our interview about Peter Higgs. I said, isn't the LHC worse because it's the search for one number? Right. And it's done since. And then it's, oh, there's hints of new physics.

And oh, we have to believe me, Neil, you romanticize experimentalist a little too much because you think that we're all just. No, these guys are now talking about building a collider on the moon. and building the size of the solar system. And that's the question that I have for you before we turn to cosmology, which is another area of redoubt and expertise that you uniquely have in the world.

And that is, you know, are we kind of in an ambiguity? The human brain hates ambiguity. They hate, we love to make decisions. Pro-life, pro-choice. We love no guns, guns, at least here in America. I don't know. Back in the UK of Brexit. Or how about this, Brexit or no Brexit.

That'll get you agitated, I'm sure. But at the heart, we kind of fix it on targets. And then when there is no target, now we're in this desert between in cosmology, where inflation, you would freely admit. And I know that you would that inflation could be right. I mean, it could be. Sure. But it could be true, but we'll never be able to detect it because the energy scale are going to produce negligible demotes. Now, when we're in the state with particle physics and cosmology, then other things like string theory, M theory,

super symmetry, all these things will bloom. But is it ultimately hopeless without a tool, an instrument to feel? What can the mind by itself, the Godunken experiment that Einstein pioneered, you know, thought about so much can we really do without experiment and without hope of building a 10 to the 16th, you know, GEV collider to replicate the primordial universe? Are we doomed? No, far from it. I believe that we need new insights into very fundamental questions. So let's go to one question. So this is slightly technical.

It is a technical field. I apologize for that. The audience is very technical, too. I mean, we have 12 Nobel Prize winners on so far. So they're very technical. Good. So I've emphasized we have to make sense of this formula. Yes.

Now, the way we use this formula, in physics so far is very restricted. So we use certain aspects of it, which work unbelievably well. One aspect is to calculate what are called scattering amplitudes, how particles scatter off each other, and those things are measured in laboratories like the Large Hadron Collider.

Now, most of those, in fact, all of those calculations, almost all of those calculations, are done using what we call perturbation theory. Okay. Now, perturbation theory says, if some parameter is small in your formula, then you can hope to calculate it by an expansion, a mathematical expansion,

in that parameter. Okay? So scattering amplitudes, most of what we know about them, is perturbative. And so this form, has only ever been checked as an example. Now, the small parameter may be really small,

like the fine structure constant, which is one over 137. That's a fairly small number. And if you calculate, you know, to whatever fifth order in one over 100, you know, then you're going to get 10 to the minus 10 as a correction. And you may be happy with that.

So physicists have become used to sort of only, using this formula in perturbation theory. What you discover in perturbation theory, so basically this is a poor man's approach. The rich man's approach to this formula would be to say, I want the answer, okay? Don't give me some approximation to it. I want to know this formula actually makes sense as it is

for all quantities, whether I calculate them perturbatively, non-perturbatively, et cetera. We don't know if this formula makes sense. non-perturbatively, in fact, for gravity, nobody has even tried. This rotation to Euclidean time definitely does not make sense, but that's not what this formula says either. This formula says, do it in real time. Calculate the interference of different space times all at once.

You know, it's very ambitious, but that's what the formula tells you, you have to do. And we haven't been able to do that. Now, the reason people went for string theory is that in perturbation theory, it's very hard to get rid of the infinities in gravity without adding extra ingredients like extra dimensions of space and more particles like supersymmetry. But that's only perturbation theory. There's a physical mechanism which may of itself get rid of all those infinities. And that is that when you consider very high energy processes, which is where these infinities come from, gravity makes them into black holes.

That's what gravity does. And so if you fire two particles together with high energy, you're going to make a black hole. And so gravity itself eats up high energy regions, and then we believe recycles them into hawking radiation. Now, that is a very natural mechanism whereby in this formula all the infinities may be removed without adding anything extra at all. The problem is the calculations which would show that are currently too difficult to do.

Nobody's ever tried. They're so hard to calculate what happens when I fire two particles together, include the effect of gravities, allow gravity to eat up the high-energy reason, regions and see if that removes the infinities. Maybe it does. In fact, this is more or less how string theory works. String theory is sort of toy model of gravity, I would say. So we don't know that we have to add all this extra junk.

We don't know that at all. That's an assumption based on an approximation of what we call perturbation theory. So nevertheless, you know, vast majority of great physicists like Stephen Weinberg and many others accepted that we have to try out string theory because perturbation theory and string theory looks better than perturbation theory in plain old Einstein gravity. So there are ways to resolve the infinities without adding extra stuff. And that's what I find much more interesting currently, is does nature, do these laws suffice to describe nature.

As I said, we don't actually know that they don't. And the only way we'll decide that is by developing our capability to calculate exactly what this formula means. And so I'm busy just trying to take this formula more seriously and see if maybe it resolves all of these problems without any need for extra dimensions or strings or other particles or anything. Now, before I rudely interrupted you, you were about to... Oh, please, go ahead.

You were showing something from the Great Bard, and it is not, as the actors would say, from the Scottish play. Oh, that's right. Would you like to show the Cosmo? Yes. So on the very smallest scale, we've discovered that nature is more economical

than 99% of theorists expected, right? The LHC has come up with a blank. still worth every penny, I would say. Knowing there's nothing, in my view, is in a way more inspiring than finding a particle because it forces you back to the drawing board. That's always a good thing. You have to figure out how the hell does nature work? If it doesn't use all these tricks and models which we invented to make it work,

how does it work? Those paradoxes which motivated strings and supersymmetry and all the other additions, the paradoxes are still there. How it might work is that nature is more subtle, and we have to understand that formula, the first formula, you know, in more depth than we currently do. So now, that's on small scales. On large scales, the same story.

This is the picture. I'm showing the picture from the Planck satellite of the visible universe. It's the whole sky. And what you see is the pattern of irregularities in the, or density variations in the early universe as it came out of the Big Bang. And these variations gave rise to galaxies and stars

and ultimately us. So it's a marvelous picture. we're very lucky generation to see it. It literally is the vast shore washed with the farthest sea. That's in Shakespeare's words from Romeo and Juliet, because we're seeing waves, and we're seeing the waves in the distribution of matter and radiation as it emerged from the Big Bang.

And it's really like an ocean. We live in the middle of this ocean, and now we can see it. So wonderful picture. What is unbelievably, what is astonishing about it is how simple it is. You know, a priori, if the universe was built out of Lego,

as you went to larger and larger scales, it would get more and more random and complicated, or if it was a multiverse. Surely we would expect that as we went to larger scales, it would get more complicated. What we see is, is the opposite. You said this place was steps from the water. We just haven't found the steps yet.

How much did we save? Enough. Enough to get lost. Or you could book a stay with Hilton. Welcome to your ocean front room. Just steps from the water. The Hilton sale is on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you Stay, Hilton, for the stay. The universe is extremely simple on the larger scales. You just need five numbers to describe everything we see so far, and there's a ton of data. It's all consistent with essentially models that were proposed in the 1970s by Jim Peoples and others, which require five numbers.

So again, most theorists, very upset. Oh, no, there's no clue for. from the data, there's no new physics. I'm the opposite. I say, wow, the universe is unbelievably simple. What we need is a principle to explain how nature got away with being so simple. So the five numbers, I won't go through them in detail.

Three are for the different kinds of energy in the universe, the barons like us, the neutrons and protons we're made of. And then the dark matter, And as I'll explain, based on this philosophy of economy, we have a new explanation for the dark matter, which is now going to be testable within the next five to ten years. And what I'm going to convey is this was staring us in the face since the 70s. There has been an obvious candidate for the dark matter, but due to theoretical preconceptions, we sort of refuse to see it. So I'll explain that in a moment. The huge thing is the dark energy.

What is this? So most of the energy in the universe, 70% of it, is in this form of this weird energy, which is absolutely uniform in space. The same with time. It doesn't change in time. It's constant, despite people searching for variations. It seems to be absolutely constant in time. And it is the same.

simplest form of energy you could imagine. In fact, that's why Einstein did imagine it in 1917. He thought, you know, he wrote down these equations for gravity and then he said, well, let me try and make a universe. So I'll throw in some form of matter or energy. He showed energy and matter are equivalent. So he threw in a form of energy, which is the simplest possible form. And that is what dark energy is. So he made a model cosmology. It wasn't. correct, but now it turns out that the dark energy introduced is there, and it's the most important energy in the universe. So, you know, talk about seeing things in advance. You know, when your blunders are Nobel. Yes. That's pretty great. But his, you know, it was no blunder.

It was the simplest assumption. What we learn from this is that nature does in many cases, use the simplest available option. And in the case of dark, you know, the simplest universe, full stop would be one which only contained dark energy. And that's what Einstein imagined. So he was close. He was 70% right. Oh, yeah.

And it's too bad because he could have had a good career, Neil. If he hadn't made that one, he would go down to history. But I want to just gently push back the respect and love that, you know, I have for you. But recently I did a video on my channel about some work that you and Nathan Boyle had done on a so-called anti-universe, where we travel back a time. And I had on one of the experimentalists, Abby Viroreg, Professor at University of Chicago, old friend of mine. She's young, but we've known each other for a long time. And about the Anita experiment in Antarctica.

How does an anti-universe simplify things? Let's go right there. There's a paper. Yeah. So I'll put a link in the video above. I'll put to link to what I did about your wonderful work with Nathan. But still, it's bemusing. But how is it simpler?

Right. So as I said, I've been following the same philosophy that maybe the answers are really staring us in the face, but we've got to, you know, we've got to see them and understand them. And that's where this idea of a universe, which where the Big Bang is precise. seeded by an anti-universe actually came from. So how did we get to that crazy idea? Okay. And actually this crazy idea underlies a lot of recent progress,

not all of which is written up, but part of which is going to be if it works, an explanation for those density variations, which we now see, an explanation in which we predict the amplitude from first principle. Okay, that's our goal. I told you we're not allowed to introduce any new particles. We want to try to explain the university as it is on the basis of the laws we already know.

And what's in prospect, and that's why I am very busy this summer, it's a hard and complicated calculation. If it works, we will explain that the density variations in the sky, they're about one part in 10,000. And the reason for that is that's the square of the fine structure constant. Okay, I've mentioned one over 137. If you square it, you get 10 to minus four. Roughly speaking, that's how our new picture of the universe works. And the origin of that number is something extremely, extremely fundamental, which is that when you couple the matter in the standard model to gravity, there's something weird called the trace anomaly. Okay, Sounds very technical.

What it means is that a symmetry of the matter gets broken due to the curvature of space time. And this is called a trace anomaly. And what goes along with it is that, you know, when you have all this, these quantum fields which are describing the matter, so photons, electrons, all of them are associated with a quantum field. the field is unable to stand still. The vacuum, so the vacuum is not empty. The vacuum consists of all the vibrations of all the fields that you add in the standard model.

And the problem is those vacuum vibrations gravitate. Gravity detects their energy. And so for it must be nearly 100 years now, physicists have essentially been cheating, taken that vacuum energy of all the fields that we know about, and we've just subtracted it, okay? But that is not really consistent. That is not consistent. And if you ask somebody in their bones,

I mean, Feynman acknowledged this, all the great physicists acknowledge this, that what we do is essentially, when we do quantum field theory, and couple it to gravity is essentially to cheat. So we've found a way around, that sheet, we found a way to cancel the trace anomaly and to cancel the vacuum energy without adding even one particle to the standard model. So that's very exciting. And that mechanism turns out to

give fluctuations as a side effect. And those fluctuations may match the observations we see. So that would be the best of all possible worlds. If it does work out, as I hope, I think all rival theories will just fall by the wayside, because we'll be able to actually calculate from a theory we know makes sense what the fluctuations were at the Big Bang. So, of course, that's extremely ambitious. It'll probably fail, but that's what I'm after. I'm after an absolutely minimal and compelling explanation for what we see. If we don't find one, fine. We might decide, either we weren't smart enough or there isn't one. But I don't see any way of resolving that apart from trying.

Do you think you could get information about this, not from the particulate content of the universe, but from the electromagnetic sector. In other words, we're looking for what we call turn-simon's or cosmic biofringent signals that would be indicative of CP violation, not necessarily CPP. But if you could ask God, you know, one question or Mother Nature, I feel like I would ask about, you know, are the laws of the universe Lorentz invariant?

You know, because we assume that they are, but could that be the most, you know, kind of preposterous assumption? And we'd only have access to energy scales on Earth where, yes, their photons obey, you know, parity inversion. Right. But time is another matter. And so I wonder, could we use the laboratory that the CMB photons, which have provided so much richness in my life and made me a wealthy? They haven't made me that wealthy. But the point being, it's my industry, right? Intellectually, they have.

So is that a more promising than looking for, you know, neutrinos? Or are you trying to solve, you know? They're both extremely promising. Let me just say a little more because you, you, about why we. came up with this crazy antiverse idea, you know, that before the Big Bang, there was an image of our universe. So that actually is motivated by something we know very well in electromagnetism, which is that, which is a mirror. If you, when you look at a mirror, you see yourself, right? But you're inverted. Left is right and right is left. So you look a little bit different in the

mirror than if somebody else sees you. But when you try to, to understand a mirror, you know, there are two ways to do it. Either you deal in detail with the way the light interacts with the material of the mirror. And the way we say it is you impose boundary conditions on Maxwell's equations, which essentially tell you that the electric field has to vanish and the magnetic field is allowed to oscillate on the mirror. But a much more beautiful way of dealing with it is to say, put an image of yourself behind the mirror, okay, where you've reflected left to right and right to left, and then throw the mirror away. Then the light which travels from the image to you will be exactly what you see.

And in physics, we call this method, it sounds like a cheap trick, and it kind of is, but we call it the method of images. Namely, instead of solving a problem with boundary conditions, you instead reflect your side of the boundary, through the boundary to the other side, and then solve the equations as if there were no boundary. And so that was our idea a couple of years ago, that there was a pre, in a sense, a pre-bang, but it's a perfect mirror image of us. It's not only left and right that get inverted.

It is time itself, it's CPT. On the other side of the Big Bang, time appears to go in the other direction. You know, the universe is growing and galaxies are forming, but in the opposite direction of time and so on. So it's really a mirror image of us. You might say this is a sort of empty notion. Why am I just sticking it there?

The reason I stick this universe there going away from us is that it allows us to solve, if you like, the boundary conditions of what happened at the Big Bang in a very natural way. Without just starting it by hand, we are actually able to give a consistent description of what happened at the Big Bang without putting it in by hand. Namely, we just mirror ourselves using CPT, which is believed to be absolutely fundamental symmetry of nature. No theory has ever violated it, that any, no sensible theory consistent with Lorentzian variance,

I should say, has ever violated it. And so we make the CPT image. And then we use the regular Einstein equations to show it, you know, to evolve the universe from one. side to the other. So it's a very, very minimal assumption. And over the last couple of years, we've been thinking very carefully, is this mirror image universe actually identical to ours? You know, mathematically identical. You know, is there Brian Keating on the other side interviewing?

I'm left-handed. I'm sinister in that universe. And we've come to the conclusion through a range of sort of mathematical arguments that indeed it is. So the antiverse is simply a mathematical copy of our universe. It's there for convenience, for mathematical ease of discussion. It doesn't add anything new in a sense of, you know, another place where things could happen. So it's actually extremely economical. It's an absolutely minimal theory. If you like, our answer to what came before the Big Bang,

is it was us. It's just the same as us. So maybe we could just pause for one second and talk about interpretation. By the way, I want to remind folks, I'm talking with a renowned theoretical physicist, the inaugural Higgs chair at Edinburgh University, University of Edinburgh, and that's Neil Turrock, who I've known for a very long time. And his influence cosmology, me, by his writings and his work, and I've done videos based on his work. And you should check out.

his just phenomenally popular videos online is currently in Scotland, but before that was the director of Perimeter Institute. But prior, you know, to getting into this, we talked about, you know, we did talk about matter and dark matter, but there's another form of matter, anti-matter, which, as I understand it, Wheeler and Feynman at all, had a notion that antimatter could be viewed as ordinary matter traveling backwards in time. And I wonder if, you know, I had wanted to ask you, what are the biggest misconceptions that lay people have, that undergraduates have, and then what your fellow theoretical, you know, physicists have. But I don't know if we'll have time for that. But is that really a misconception?

I mean, is it really the case that we can, we really think that there is a part, there is a negative direction of time? Or is that like Hawking's, WIC rotations? It's a simple trick. No, I don't think it's a simple trick. I think it's an extremely deep insight that Feynman and Wheeler both had, and before them actually a guy called Stuckelberg, who's little known and not so popular, was a very shy person, a bit like Peter Higgs,

but he was the true genius in quantum field theory in the 1930s, but apparently he wasn't recognized and basically ended up going to chemistry where people were more receptive. But he wrote papers where this idea of a particle going backwards, particle going backwards in time was an antiparticle. Very, very beautiful idea. It's absolutely consistent with everything we know. And in fact, Feynman himself made the following statement that,

and Feynman, you know, as you know, won the Nobel Prize for, quantum field theory and was one of the most accomplished practitioners. Feynman said the whole of quantum field theory is nothing but a clever attempt to hide the fact that particles go backwards in time. Particles can go backwards in time and when they do their antiparticles. So he viewed, you see, nobody has ever seen a quantum field. If anybody tells you, you know, quantum field theory is the answer to life, the universe and everything. Just ask them, has anyone ever seen one? No. Because the only way we see quantum fields

is through particles. We do observe particles in experiments. And so what you, you know, these fields may somehow represent that they do seem to represent the particles at some level of accuracy, very high level of accuracy. But what is actually going on, you know, maybe, Maybe particles indeed going backwards in time. It may be, but as my brother, older brother would say, you know, have you ever seen your brain? I say no. And he says, well, how do you know it exists? We haven't seen quarks either.

And quarks are, you know, thought to be part of it. So what do you say? Yeah. Push back and say, look, you know, we. No, absolutely. Absolutely. I think we don't know. And it's true.

People are very suspicious about quarks because they don't exist at free particles. But, you know, on the other hand, why should they? You can imagine particles being, you know, tied together with a little piece of string in such a way that if you try to pull them apart, all that happens is you break the string and a new particle appears on each end of the free end of the string. Frank Wilczek is discussed on the podcast, yeah. Yeah, so, no, I think the, what I would say is that you see the, why do I prefer one image, mental image over another? the first thing to say about quantum field theory is it's basically a gigantic algebraic machine, right? That's actually what Dyson's contribution was to turn it into a machine. It's a calculational machine.

And basically the philosophy was, shut up and calculate. Don't worry what's really going on. Calculate the scattering matrix. And don't worry about what actually happened. Okay. The kind of work I'm doing now to understand this path integral, we don't accept that. We want to know exactly what went on

during these inside the path integral. And people who study quantum mechanics on its own, you know, to the foundations of quantum mechanics and who do experiments to understand the weirdness of quantum mechanics, increasingly they are asking exactly that question. What is actually going on in the middle? It's called the theory of weak measurement. You know, if you measure something precisely, you notoriously collapse the wave function.

Yes, let's do a concrete example, the double slit experiment. Walk us through that. Double-sit experiment, exactly. So if you observe an electron as it goes through the slits, you will destroy the interference pattern. Okay, so we know that a strong measurement, the classic measurement in quantum mechanics, spoils your ability to see what is happening, what is actually happening. But a weak measurement, this is a very clever idea, that if you couple the quantum system to another system,

and you only perform a strong measurement on the other system, and the two systems are coupled very weakly, then what you can do is repeat the quantum experiment, in which the coupling to the other system is so weak, it doesn't spoil that at all. Non-destructive. Non-destructive. So the quantum system is happily doing all its interference and everything.

But then by repeating the experiment thousands or millions of times and performing real observations on the weekly couple system, you can make predictions based on what the quantum particle was doing in the interim, you know, as it was going through the two slits or as it was doing something very quantum mechanical, tunneling, quantum tunneling or whatever. So that's a very beautiful idea. And part of the reason I like it is it's exactly what we have to do in cosmology. We live in the universe.

We're not in a scattering matrix. We're in the middle of the thing. You know, we're after the Big Bang, but we're before the end. We're coupled to it. Right. We're coupled to it. We're coupled very weakly. I mean, whatever we measure the Hubble constant to be does not, the universe doesn't give a damn.

It's much bigger than us. Okay. So there are all kinds of. parallels. And I firmly believe that understanding how to reconcile quantum physics with the universe requires us actually to understand quantum physics in these intermediate regimes. And literally to ask, you know, what happens when a quantum particle tunnels? Where is it? How would somebody trying to measure the particle as it is tunneling and measure it very weakly, what would they tend to see?

So what's fascinating to me is that sort of these, the work on quantum foundations, which until about 20 years ago was really philosophy in the worst sense, it was going around in circles about rather academic points without test. That field has changed because now we can do experiments, we can attempt to build quantum computers. You know, technologies reach the point where these sort of academic questions about what's really going. on in quantum mechanics are becoming testable in experiment. And I think we can learn a lot from them about how we deal with cosmology. See, almost all the quantum physicists, and I would say almost without exception, all the string theorists, for example, who do cosmology, do it in the following way. You say, given a classical universe, namely a space-time arena,

Right? Just given that, how do I propagate particles or quantum fields or whatever on top of that arena and then see what happens? Okay. Now that is not, that doesn't make any sense at all. In quantum mechanics, you cannot couple consistently a classical object with a quantum one. That makes no sense. People have understood that from the beginning of quantum mechanics. Either you're all classical or you're all quantum. You can't, makes the two. Now, you know, there's some approximations in which it looks very classical in some respects, but if you want to do it properly, you've got to quantize everything. And that means space time itself must be quantum. And that path integral formula, I showed you, tells you how to do that, actually. So John Wheeler knew how to do it, which is that you've got to sum over all possible space times that connect, you know, a given the universe at one moment of time, let's say to the universe at a later moment of time. It's a very difficult calculation,

not just practically, but conceptually. If somebody gave us the most powerful computer of all time, we still wouldn't know how to do the calculation because we don't know exactly how to implement that interference formula. And that's what I'm busy trying to figure out. And I think it's possible, but it needs more mathematical insights. What I love about this is that the ingredients which go in are actually very well established. Einstein's theory of gravity, quantum mechanics, this notion of a path integral. These are all kind of very solid notions, even if they aren't mathematically rigorous yet, especially the path integral.

And so by making them more rigorous, it's very tough work. It's very mathematical work. But I'm really hopeful that we will gain insights. And what I'm hoping in particular is we'll see how to resolve the big challenges in physics without adding more junk. Nature is telling us very clearly, don't add junk. Okay. And if we add junk, we are falling into the oldest trap in science, which is when the data don't fit the model, add a new parameter, right?

It's what everyone does in financial mathematics, economics, you know, modeling of all sorts. And people have learned the lesson that a forecast made using a model where you just added something to fit the prior data, you know, very often fails. The model is only useful if it's predictive, you know, and those predictions are based on assumptions which are minimal. Don't keep adding parameters and extra stuff. So we've got to stop doing it. It's an addiction.

It's an addiction in the field. There's vast numbers of papers which are doing that. So it's quite hard to resist this, right? Because what I'm doing implicitly is criticizing all my colleagues have written tens of thousands of papers with tens of thousands of new particles and parameters. And I'm saying we've got to stop. This is not leading us to new understanding. And I'm afraid, you know, as wonderful as inflation is, and I'm a big, I fully acknowledge that inflation theory drove, help to drive the observational. efforts. You know, it was what whatever inflation model was being advocated, you know,

was an inspiration in the sense that you could then try to shoot it down as an experimentalist. And that's really, really important. So I think inflation was extremely important to the field, was an inspiration, but doesn't need to be correct. What do you say to those people like I've had on David Spurgel. I've had on conversations with Will Kinney about his new book on the multiverse effectively. And they push back, you know, with all due respect. And they'll say, well, how do you explain the large angular scale T.E. correlation without inflation. How do you explain the not quite scale invariant, you know, spectral index?

How do you explain the successes of inflation? Forget about the multiverse, which Paul and I have talked about. And Aegis and I have talked about links to those videos. But let's just focus on the successes of inflation. So can you. Thank you. Thank you. Yeah. So I can.

I can. And this is our new work. So it's a great question. Now let me just tell you how it works. Okay. So the first, the puzzle, which everybody believes, and, you know, Dave Sergal is a good friend and Wilkini, too. they have bought the inflationary explanation, okay, but the inflationary explanation comes with a bit of baggage.

You've got to assume an extra-scaler field for which there is no observational evidence. You've got to assume that field was displaced from its minimum and that it rolled very slowly downhill. Okay, so you put in the initial conditions by hand. You have to assume all kinds of things about the quantum state of that field and so on. It comes with a lot of baggage. And essentially, it's a model contrived to fit the data. I'm sorry, Neil, but it's just, again, just for the listeners that may not be watching, we're all talking about some technical matter now that will show video on the YouTube channel.

But in particular, couldn't one say the same thing about the Higgs? It comes to some initial value. It is. The job of the theory is not to explain, you know, I always say, when I took a biology class, they don't start with, you know, how did life form in the universe? They start with, here's DNA, here's microbiology. In other words, is it a problem for the theory that it has to come up with the initial condition? Like, it has to instantiate itself?

Is it have to be it from bit, as Wheeler would say? I mean, isn't that asking to, like, I mean, you could say the same thing about, about the Higgs case? No, no, there's a, there's a huge difference between the Higgs and inflation. the Higgs was a mechanism to explain a known fact, the weak interactions. And so that it's not just one fact. There was an abundance of data. And what Higgs did with one hypothesis,

admittedly introducing a new particle, was to explain a vast array of data. Whereas with the inflation field, you're introducing, well, as I think you said earlier, inflation isn't really a theory. It's a collection of models. So you're opening the door, whereas the Higgs mechanism is really quite unique.

I mean, it's tied down by the standard model and its symmetries, that when you introduce this Higgs field, you're extremely constrained in how you introduce it. And essentially, there's only one free parameter. and that parameter turns into the particle mass. And as all the other observations of all the kind of side effects of the Higgs mechanism, as they became more and more precise, the prediction for the Higgs particle mass became extremely narrow.

And so people are very nervous. Oh, my God, is it going to be ruled out? And as late as 2012, people were still worried it's going to be ruled out. That seemed to me the most likely thing. and then very last minute when their window was finally narrowed, a little bump appeared, and there it was. So now, inflation absolutely different. You see, inflation, so the Higgs mechanism is explaining a wealth of complex processes, okay, involving particle physics, all of which are measurable in accelerators and experiment.

The inflotone and inflation is explaining one, actually two numbers. One is the amplitude of these density variations as they came out of the Big Bang. There's roughly one part in 10,000. That number is being explained, except the number isn't explained. It's a free parameter. And then secondly, what is called a slight tilt, that the fluctuations on the sky are ever so slightly larger on large scales than they are on small scales. It's only a 1% effect. but, you know, it does seem to be there in the data.

So basically we've got two numbers to explain, and the minimal inflation models essentially introduce two parameters to fit those two numbers. They don't predict anything, but they do fit. They are able to fit the data. The problem is they also predict something else, which are gravitational waves, which you know very well. And on that basis, they're under severe pressure now.

And so the inflation models, you know, are way less constrained, theoretically, than the Higgs model ever was. And so then you're forced to say, well, why do I favor one inflation model over another? You know, there's some notion of what simpler. But the simpler models are now wrong. And so now inflation modelers are in the position of adjusting their model. You know, with every new piece of data, you know, if you have to adjust the model by adding a new parameter, you know you're going in the wrong direction. So I would say inflation is, you know, at best, a fitting model. It's because it's basically trying to fit these two numbers.

You know, the Higgs mechanism is fitting. a million numbers measured in laboratory experiments. It's just totally different. Much more principled theory and is fitting a vastly greater array of data. So that encourages me to believe that instead of inflation, there might be a much simpler explanation, a much more principled explanation. So let me try and give you a flavor of what I think it is. And this is our recent paper, which explains the flatness of the universe on large scales, just using thermodynamics, gravity, and quantum mechanics. That's all, okay?

So, and I'll tell you how we did it. I'm very excited about this. And I think, again, you know, the mathematics is crystal clear. The assumptions are crystal clear. If it may be right or wrong, because there are assumptions, but the explanation is absolutely unique. So there are still some puzzles about it. There always are.

But this could be the definitive explanation without any sort of bells and whistles. So let me explain our new explanation with an analogy. Because it is rather technical. It's using Stephen Hawking's work on black holes, which is very famous. Stephen Hawking figured out what's called the entropy of a black hole. And all we've done is import his method of calculation of entropy, of gravitating systems. We've taken that calculation and applied it to the real cosmos.

So we have calculated for the first time the entropy of a realistic cosmos with dark energy, with radiation and with spatial curvature. And we find that provided the universe is sufficiently big, and I'll explain what I mean by big in a moment, the most probable universe is flat. And the answer is crystal clear. So if this explanation is correct, no extra theoretical ingredients are needed.

It stands on its own. It relies on gravity and quantum mechanics. Quantum mechanics is important in thermodynamics because it allows you to, it quantizes the states and it allows you to count how many states there are. And our explanation is simply that the flat universe is the most probable. If you allow the universe to take all of its possible states, it's most likely going to turn out to be flat. So what's the analogy? Well, why is the earth flat?

and I'm showing here a picture of the Earth from space made by NASA. And what you notice when you look at these pictures is the Earth is just this perfectly round marble, okay, smooth as anything, perfectly round and smooth. And what this means is that if we, I've got a little circle showing Edinburgh, if we live in Edinburgh and if we only travel, you know, 10 kilometers or 100 kilometers, We don't need to worry about the curvature of the Earth because locally the universe, the Earth is very flat. Okay, so the flatness of the Earth is a consequence of several things. One is the Earth is very big.

Earth is made of about 10 to the 50 atoms. Okay. If the Earth was any smaller, you know, and it were round, we would see the curvature of the Earth. So the 10, first of all, you need to know that the Earth. Earth is a big object. Secondly, you need gravity. Gravity pulls all those atoms inwards, and when it does so, it makes the Earth round, but you have to have dissipation. You know, if a mountain collapses, it doesn't rebound. And, you know, whereas an elastic ball will vibrate, the Earth doesn't do that. You know, once it falls inwards, it stays inwards. And the

dissipation redistributes the energy, the potential energy, let's say in the mountain or in a ball, that energy is redistributed into heat. So there are vastly more ways of arranging the earth and a given amount of energy where I put all that energy in just the vibrations of the atoms and molecules into heat. There's so much heat capacity in the earth that if things fall on the earth and they make, for example, a sound wave, that sound wave will just go into heat and all the energy that was in the object as it fell will be redistributed into heat in the earth. So once you understand, and essentially this is entropy, that while it may seem sort of surprising at first sight, that the most probable earth is round, whereas a most random earth would be very

jagged and spiky. If I took 10 to the 50 atoms and treated them like Lego, I'd get a very crazy geometry. But in reality, what happens is when you include gravity and dissipation, then the most probable geometry for the Earth is actually spherical. Because we don't see it looking random, because we're not looking at the vibrations of the molecules, but all the vibrations of random. There's a ton of entropy there. And so entropy favors a round, smooth earth. So it's a wonderful explanation, it doesn't require any new physics. You don't require somebody to come and polish the earth and make it round and smooth. You know, physics does that for you. And I think Einstein said that any time you use thermodynamics to explain something, you know, that explanation may

last forever because the laws of probability are not about to change anytime soon. And if there are just many more ways to make a round earth than there are to make a jagged earth, you know, it's very likely. And whatever your laws of physics, the earth is going to be round. So I take inspiration, by the way, there's some new evidence in favor of this explanation involving plankton in the oceans, which is very beautiful. So life actually had a role. You know, there are mountain ranges on the earth. After all, there's the Himalayas and the Andes and the Rockies. Turns out all these mountain ranges arose about two billion years ago. And the reason they rose

was precisely because the friction of content between continental plates was reduced about two billion years ago. So when two continental plates collided, instead of just sort of grinding each other into dust and making something smooth, they slid one above the other due to the lubrication. And the lubrication was the carbon in the form of graphite created by the plankton when life formed about two billion years ago. So the origin of life preceded the formation of mountains. Doesn't I mean? Sorry, just aside, there's no life elsewhere in the universe. I always say to get a solar panel, you don't make a solar panel from a solar panel. You don't make a transistor from a trans.

You had to have pre-existing raw materials. And we got to communicate using Zoom today because at one point, we were using whale oil to light lamps that then wrote down equations that build factory. In other words, the improbability of what you just described. And by the way, that plankton only survived because the dinosaurs were too large to notice them. And then the dinosaurs only got wiped out because of the... I have to ask you just yes or no. Do you think there's intelligent life elsewhere in our galaxy? I don't know.

I don't know. But I don't want to dwell on it because I want to keep... No, no. I, you know, it's a wonderful question. I don't know, but I think the case is getting more and more interesting. We've just discovered that Pluto is a... lot more intricate than we expected. There's a lot of ice, and the ice is active.

There are volcanoes, ice volcanoes on Pluto, indicating that perhaps under the ice there's an ocean. And, you know, having water is certainly very helpful for formation of life. So perhaps there's some primitive life on Pluto. I think it's absolutely fascinating. Oh, it is. It's really fascinating. Yeah, I really don't know. I mean, I guess my, you know, philosophically, our human egos tend to encourage us to think we're alone.

And that makes us feel very important. On the other hand, the people that believe in alien life feel like they're not unimportant, but that aliens would want to visit us just the same. but also that there's something privileged about us and that on the one hand, on the other hand, we shouldn't take ourselves so seriously because life is teeming throughout the galaxy, even though there's no evidence. Anyway, I don't want to distract. Let's get on.

No, no. We'll solve the origin of life another time, my friend. Yeah. You know, actually, it brings me on to something else. I'll come back to this, but it's a very important point. How does life fit into the cosmos? And I have a slide about that, which won't answer the course. question of whether there is

maybe we'll do a part two Neil because actually you brought up so much interesting stuff and I know your your time is limited and I want to complete but the other thing I want to talk about is we're just forgive me if this is loony sounding but consciousness in the wheelerian sense of it from the universe how does it fit into the anti-universe paradigm I but I don't want to talk about that now because I really want you to keep going with what you're just talking about I'm very too later this summer and I also want to read your book your second. Sorry.

I'd be happy to do that. In fact, I was lucky enough to work at Princeton when Wheeler was retired. And John Wheeler used to come to all the physics department colloquia, but he wasn't allowed to drive at that point because he was too old. And so I used to drive him home. Wow. And so John Wheeler, I had a very young daughter at the time. It was, I think, two or three.

and I brought John Wheeler home. And so I was trying to explain to her who John Wheeler was. I had a similar experience with Freeman Dyson when he met my four-year-old son over dinner here. These were incredible people. And I think one of the joys of being in theoretical physics is to spend some time with them. I think it's a good job in the world, Neil, not just theoretical physics, but also to be a scientist exposed, as you've been exposed on every continent,

except Antarctica and your work, you know, South Africa where I have yet to visit. I've lectured on all six continents, except for Africa, I hope to go there. But that you've met so many interesting people. You've been involved with young people,

with science in Africa, and the anti-apartheid movement. I'd love to talk to you about that. So let's do a part two, but later this summer, I know, that's fine. Let's keep going with your, with your, anything else you want to talk about, but, but I know you have to go at about 15, 20 minutes.

I got to go babysit myself. No problem. I just want to tell you one thing about Wheeler. So he, I said, my daughter says to me, you know, who's John Wheeler? And I said, oh, he's the person who believes that there are wormholes in the sky. And so my daughter's answer was, oh, everybody knows that's wrong. Wormholes are in the ground. But it's true.

John Wheeler invented black hole, the word black hole, and he also invented the word wormhole, and he was the first to think about such kind of mind-boggling effects, which people like me are trying to now kind of implement mathematically and see if those ideas hold water. But, yeah, amazing person. So, yeah, I want to come to this explanation for flatness. we have an explanation for the flatness of the universe which exactly parallels this explanation for the flatness of the earth.

It's not atoms that you need to count. It's how many possible states are there for the entire material that makes up the universe. Because if you like gravitational atoms, so imagine you're building a space time out of something. how many of those atoms are there? Okay. And what I claim is that if there are many, and by many, I only mean, let's say, a thousand times more than we already know about,

because we already have seen, you know, a vast region of the universe. So if there are only a thousand times more than what we've ever seen, well, I should say precisely, I mean that the entropy is a thousand times more than what we've already seen. seen, then the most probable universe is flat. That's all it takes.

Just as more atoms of the universe in the earth make it flatter, more degrees of freedom, we say technically, in dealing with gravity, make it flatter. So this is my audience that may not be familiar, the astonishing thing in Neil's famous, you know, kind of lingo about the curvature of the universe. that's flat, wherein there are an infinite number of real numbers that could be corresponding to the curvature being positive of the universe, being a spherical positive curvature. Identically, there's an infinite number of negative curvature universes where the curvature is negative, but there's only one, you know, zero is a very...

Exactly. And to explain it requires either an astonishing coincidence or a mechanism. And what Neil is describing here is a mechanism forcing the universe, no other two. choice to be flat. Exactly. Exactly right. In the same sense as the earth is locally flat, that in a small neighborhood of the earth, you see something locally flat. I mean, this work has convinced me that, by the way, I have to say that our calculations assume the universe is finite, not infinite. It can be positively curved. It can be negatively curved. It can be an arbitrary size, but it has to be finite to even talk about the number of states.

you have to assume it's finite. And the result of this calculation convinces me, whereas I didn't take the possibility seriously before, it convinces me that the universe could very well be finite, after all. Certainly if it's positively curved, it would be a sphere of finite radius, but if it's negatively curved,

it can also be finite. It requires various arrangements like mirrors in it to make it finite. And such a universe proposes. it's larger than, you know, the region we see, the most probable states will be flat. So I'll just show a little graph. There's a graph from our new paper. It's about the gravitational entropy of the universe. And so Hawking, I won't describe the graph in detail, just to say it exists. It's a mathematically precise calculation. The only assumptions are gravity and quantum mechanics and Hawking's way of calculating entropy.

And personally, I think Hawking would have loved this calculation. Now, what happened is, so people before us studied the Lambda universe, the empty universe which only has dark energy. That's what they could do mathematically. And they call that de sitter space, decider space time. It's an empty universe apart from the dark energy, right? And mathematically, it's rather easy to handle, and you can calculate its entropy. So there was this desider entropy.

And then various people asked, well, what happens if I add some stuff inside this dark energy universe, like matter, radiation? What happens to the entropy? And what they discovered is it goes down. Okay? The more stuff you put in it, the smaller the entropy gets. and eventually it hits zero. And the reason it hits zero is that it's possible to have a static universe. You see, the dark energy is repulsive, drives the universe apart.

As you add more and more radiation, the radiation is gravitationally attractive, and you can balance the two to make a static universe. And in fact, this is Einstein's static universe model. That has zero entropy in gravity. And technically the reason for that is it has no horizons. It's just a static space. It has no entropy. That's not the universe we live in.

In fact, none of the universes I've just described are the ones we live in. We live in a universe which has more radiation than the Einstein static universe, which came out of a big bang, which is dominated by radiation. So we succeeded recently in extending this calculation of gravitational entropy into the realistic regime where you've got lots of radiation and that radiation dominates. You know, decider space is like a sort of hyperboleid. It bounces. As you go back in the past, it bounces and re-expans.

The universe we live in didn't do that. There was so much radiation that it just collapsed. As you go back in time, it collapses into a big bang singularity. So, sorry, they're dogs. Don't like singularities. So we succeeded in doing this calculation for a realistic universe, including lots of radiation. And when we do that, we find that, you see, one is the magic number. If the gravitational entropy equals decider entropy, so we know what the dark energy is today.

And so we know what the corresponding entropy is of a decider. universe. If our universe has more than a thousand times the entropy of that, the sitter universe, then it turns, and because entropy goes like volume, it essentially means it's 10 times bigger than what we see. The radius has to be 10 times bigger than what we see. Then it turns out that the curvature, the most probable universe, has curvature nearly zero. And that's what the blue line on this curve shows. So I claim that, you know, this calculation of gravitational entropy indicates that the vastly most probable universe is actually spatially flat. If that, if this is the case, then all of us have been on the wrong track for the last 40 years. And in fact, you know,

a very simple explanation along the same lines of why the earth is flat was staring us in the face. It's due to gravity and how gravity is reconciled with thermodynamics. And also it would reconcile this great puzzle that was at least brought to my attention by Sir Roger Penrose of why the entropy was so low in the early universe. And yeah, there's this famous diagram. Yeah, you want to explain what this paradise is all about? Let me tell you a little bit about Roger Penrose. Roger Penrose is an absolutely inspiring figure in the field of gravity.

He's the one who discovered the mathematical properties of black holes and who inspired Hawking to do the same for cosmology and prove that classically the universe began in a Big Bang singularity. So Roger Penner is just a legend. He's also one of the nicest people you could meet. I was interviewed by him. He's a four-time guest on this podcast. So I know he features that very,

it's the top of his CV. There's, you know, Nobel Prize. Right. So, yeah, Roger interviewed me for a PhD place. And I unfortunately only did physics as an undergrad. I didn't do mathematics. And so he interviewed me in Oxford and he said, he kind of looked down his nose at me and said,

what problem do you want to work on? I mean, you're just a bloody physicist. You don't know anything about mathematics. And so I rather arrogantly or forthrightly said, what's the hardest problem in the subject? And he said, oh, it's describing massive particles. And so I said, oh, great, that's what I want to work on. And he sort of looked at me like,

I've worked on this for 20 years and haven't gotten anywhere. So who the hell are you? So he didn't offer me a place. But actually it was a good thing because the problems he was working on were actually very, very hard and wouldn't be good for a PhD student anyway. But he's an amazing person. He's a very outspoken critic of inflation. And his argument is shown in this picture.

He draws the most beautiful pictures, too, of, mathematical ideas and also just... His father was an artist. His father was a great artist. Oh, I didn't know that. Uh-huh. Didn't know that. So, well, he is many talents.

And so this shows the puzzling large-scale geometry of the universe. So, you know, Einstein's theory, as you said, allows space to be curved and wiggled and to take any shape. And yet it doesn't. You know, the geometry of the universe on large scales today is just what people taught in ancient Greece. You know, Euclid taught geometry, the axioms of geometry, and three-dimensional geometry. You've got X, Y, and Z, and it's exactly what you learn in primary school. That is the geometry of space in the universe.

Why? Well, what a mystery. I mean, why did we need Einstein if the universe, you know, chose this ridiculously, ridiculous Euclidean geometry, such a trivial and simple thing with no curvature or anything. So Roger puts it in this beautiful picture. He has the creator, you know, deciding to start the universe in this ridiculously special geometry, which doesn't need Einstein at all to understand. Why is the universe so peculiar? And so Penrose made the argument that, But if you do the calculation of thermodynamics,

a la Hawking, he again used Hawking's idea of gravitational entropy, he guesstimated, you know, what was the probability of a universe so special and flat as ours. Now, what he had done in that guesstimate is not say anything about the Big Bang. Okay, basically his argument that was that the most probable universe would be a giant black hole, which just contained everything that we see. And he used Hawking's formula for the black hole, and he basically argued on general grounds, why didn't the universe just form a giant black hole that has so many possible states,

such high entropy, that's what it would be, but we're clearly not living in a black hole. So that was his paradox. What we've done is we actually implement very precise mathematical condition at the Big Bang, this perfect mirror. As I said, it's this reflecting boundary condition at the Big Bang that we see ourselves, in a sense, through the Big Bang. And we implemented that, and then we used that to calculate the entropy. And it turns out that our reflection symmetry, the CPP symmetry, is what excludes.

there being a one huge black hole. That doesn't satisfy this reflection symmetry. Could you have multiple, like his primary, his error bonds or his hawking points? Could you have multiple tiny black holes or is it precluding black holes in general from permeating the boundary? This boundary condition precludes any black holes at the big battle. There's a mathematical statement that it's what's called a conformal zero. The Big Bang is a conformal zero. It means that space has shrunk to a point, and the size, if you like, of the universe,

the scale factor has a zero, which is analytic, and that means mathematically nice. So the scale factor shrinks to zero, but the geometry, which the scale factor is multiplying, is what we call regular. namely it doesn't have any divergences at the Big Bang itself. And that alone is enough to rule out Big Bang. Rule out black holes at the Big Bang.

So the black holes that formed later, they formed subsequently. And for that reason, there are no very big black holes because they formed from sort of small sizes upwards. our initial condition excludes there being a big black hole. And then when we calculate the gravitational entropy, we're not calculating the entropy of a big black hole. We're calculating it of a cosmos. And so, yeah, it's interesting. I gave a talk to Roger recently.

And halfway through the talk, he said, oh, but you're not talking about a cyclic universe anymore. And I said, no, I'm not. What I'm doing is actually implementing your old ideas from the 1970s and 80s, because he had this idea called the vile curvature hypothesis, which is basically what I just said, this conformal zero. He was trying to explain why the cosmos was simple. He didn't explain why it was flat,

but he was trying to explain why it wasn't crazier in the Big Bang. And he made this hypothesis. And I said, no, I'm implementing your old idea, which, you know, you gave up on some time ago. And he switched to cyclic. Yes. Okay. But now I'm switching to his previous idea. And we'll see.

Yeah, very interesting. Yeah, we'll have to. That's the luxury of theorists. We can switch sides. And as Hawking did, according to Sir Roger. So, Neil, we're coming up on two hours now. I'd love to indulge your forbearance to ask you three questions that I ask all my guests. And then I would like to further solicit forbearance and ask you to come back on the show forthwith after I digest your second book or the book I haven't yet read of yours. So would you feel comfortable answering my existential questions courtesy of someone? Okay, great. The first question, these are my so-called thrilling three questions, but the first one has to do with your own personal horizon. So if you want to stop sharing the screen, we'll take off Sir Roger. Actually, I can shrink Sir Roger to a conformist. Okay. I shrunk him to a singularity anyway. So the very first question I like to ask involves your legacy, both ideologically and sort of wisdom. And that has to do with this concept of what's called an ethical will.

Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals because we're built for what you're building. Fit for your ambition for Citizens Bank. What sorts of wisdom, not monetary, not material bequeathment. Would you like to leave the world with when you spring forth the mortal coil, as the Bard said, at age 120 in the biblical tradition. What wisdom, one piece of wisdom would you like to leave the universe with? Gosh, that's a tough question. Yeah, I think it's an appreciation, and this is what I like to share with everyone. It's an appreciate, it's a feeling I've had, it's just a

feeling, which I've had ever since I was a child, that the universe is just extraordinary. And our appreciation of it gives us more riches than anything else. And that's the wisdom that actually the wisdom is in nature. That's my guiding philosophy. I think nature keeps us, you know, keeps us on the right path. And by, so take what the recent discoveries, right? The universe has turned out to be surprisingly simple. The Higgs was found, nothing else was found.

No multiverse in the sky, right? It's simplicity itself. And are we able to learn from me? that. I literally feel that the universe is our guide. That's the role it plays for humankind. And it has, if you think about it, when people, you know, in the Stone Age, you know, looked up at the sky and they thought, wow, you know, that's amazing. And so it lifts you beyond yourself. It has an unimaginable sort of beauty, grandeur. That comes from symmetry. It's not chaos. The universe is the furthest thing you can imagine from chaos.

That's in a sense why, and this matters not a single thing scientifically, but this is why I don't really like the idea of a chaotic multiverse. You know, I can see why some people find it appealing. But for me, it's the opposite, that the universe is a guide. It shows us. I mean, think about the history of physics. You know, how did Newton learn the laws of motion? It wasn't on Earth.

It was by watching the planet, by taking data from the planets. He did the easy work. He just did the math. Other people took the observation. So, you know, time and again, and likewise with Maxwell, you know, Maxwell always gave credit to Faraday. Faraday discovered the laws of electricity and magnetism, plus some other people, but Faraday probably most coherently.

Experimentally. And Maxwell just had to write down the math, which described those laws. And Maxwell gave all the credit to Faraday. Now, what he was doing is not so much being kind to experimentalists. He was saying, nature tells us how it works. We just have to listen. And that is the job of a theorist to listen. And I don't, the criticism I have of my own.

field and my own earlier work is we weren't listening. We were so full of ourselves. We said, oh, we'll come along and introduce an extra dimension and brains and all kinds of imaginary phenomena. And to be fair to us, we didn't have that much data. Now we have tons of data. And it's all going in this direction of extreme simplicity and economy. And so I think any theorist worth their salt, should be forced now to reconsider and say, you know, maybe my model was just too complicated. Very good. Very good.

Okay. So the next question on my topic now goes maybe further into the future. Sir Arthur Clark said any sufficiently advanced technology is indistinguishable from magic. In his movie 2001, a space odyssey. We see these apes and they come upon this monolith. And we don't know what it is. It could be a time capsule. it could be a, it could be a warning, who knows, it could be some technology, some magical

technology. I want to ask you kind of, you know, taking off from where Feynman said the most, the most important information-filled statement in the fewest words is the so-called atomic hypothesis. I want to ask you if you could update Feynman or give your own spin on Feynman, what kind of magical statement could we use to brag about what physicist or humanity has learned? It could be human. It could be something not related to your job. But what contains the most information that human beings should rightfully put into a billion-year-long time capsule and let aliens know how proud we were of it some billion years hence? Well, okay, so we haven't yet done it.

but I think I honestly feel that reconciling quantum mechanics with gravity will be that something. The reason why it's so interesting, and it actually relates to particles going backwards in time, because particles, what are particles after all? We think they are what we call world lines. A world line tells you where a particle is in space and time, But if you think, you take the big picture and just look at kind of all of space and all of time, what's a particle?

Well, it's just a curve in space time. And that immediately is telling you that geometry is somehow gets reconciled with quantum mechanics. So quantum mechanics is making things spread everywhere, explore everything. That's all these phases I was talking about. You know, the quantum mechanics is incredibly exploratory and indefinitely. Geometry is the opposite. It's extremely definite. I know exactly where the particle is at every moment of time. So these are opposites. And when we try to link gravity to quantum mechanics, we've got to understand how are these things reconciled. I think they can be. It's extraordinarily difficult when it is. We will truly be sort of uniting opposites. Quantum mechanics, there's the uncertainty principle. So if you say where something is now

or what geometry does the universe have now, inevitably there's something you know nothing about, which is, in the case of the universe, how fast is it expanding? If I know exactly what the geometry is now, then I cannot know anything about how fast it's expanding according to quantum mechanics. So the only way to know anything is you say,

well, I know approximately this and approximately that. So you can see there's a huge tension between even the notion of geometry and the notion of the uncertainty principle in quantum mechanics. So that I think is, we've got so many clues.

You see, this is not pie in the sky. We know how particles work. We know what they do in colliders. We know quantum field theory works to very high precision. What we don't yet have is a sort of geometrical picture of exactly what the particles are doing and what that even means

during one of these processes. And if we gain such a understanding, mathematical understanding, precise understanding, we're going to have to do the same thing for the universe and our place in the universe. So yeah, even though quantum gravity may sound a very arcane and, you know, just the kind of last dot of the eye

in theoretical physics, It isn't. It's much more than that. It's actually understanding the whole thing. It's reconciling these two opposites. And that makes it, you know, very, very challenging. But I think if we do succeed in reconciling these opposites, you know, that will be the grounding achievement of physics. Wow. Great. Okay. Third question. I'm actually going to ask you four. Again, you've been so generous. I hope you'll continue and won't slam shut the laptop on maybe. But the third statement of Sir Arthur was when a distinguished but elderly scientist, I'm not calling either one of us elderly, but when a distinguished but elderly scientist says something is possible, they are most certainly right. When they say something is impossible, they are very probably wrong.

I want to ask you, Neil, have you changed your mind on anything recently? Have you been wrong about anything? Absolutely. I've been wrong multiple times, and I think it's been very good for me. I was, I've always been a skeptic about inflation. It always looked to me too many artificial ingredients in the models. But so what I did, I'm trying to be constructive, is to develop alternative mechanisms, which would explain structure in the universe.

So I worked on what seemed to be a very appealing idea at the time, which was based on grand unified theories, which is an attempt to go beyond the standard, model that has now kind of fallen out of fashion. And these theories predicted structures called cosmic defects, cosmic strings. And what fascinated me about that idea is it was very predictive. It explained that there were these objects swishing around in the early universe, explained how they formed out of fundamental physics, and then they switched around and they stirred up the matter and that would end up making galaxies. So it was a very principle. and very predictive theory, and I decided to devote more time than I should have to working

out all of its predictions, which I did. And then the experiments came along, and they proved me and the theory utterly wrong. And yes, it was disappointing. I think for about six months afterwards, I felt, oh, God, I wish it had been right. But actually, with hindsight, it was a really good thing that happened to me because it made me even more of a natural skeptic. And even more, I believe that a theorist job is to come up with testable, you know, precise ideas which challenge experimentalists to go after them. And ideally to try to prove them wrong. Right.

Your theory only succeeds to the extent the experimentists have failed so far to prove you wrong. And so a theorist job is really a provocateur. I mean, that's what we should be. And if our ideas are any good at all, they serve a purpose of getting people to test them against nature. And so, yeah, I have been proven wrong. I think it was great that I have. I really pity other theorists who work on frameworks and paradigms, which are not provable wrong,

because they're just condemned to spend the rest of their days recycling the same old ideas and never really knowing if they're true. Right. One of my mentors, a theoretician named Alexander Polnerov, you probably remember the name. I know him, yes. Yeah, and he, he's at Queen Mary at college. He used to say Zeldovich would tell him when he was doing something trite or repetitive. He said, and I guess it's more poetic in Russian, but he would say,

you are like somebody who eats food. Someone else has already eaten. That wasn't my favorite. My favorite Zeldovich quote was when I would try to do too much, Alex would say, Zildovich would tell you nine women cannot have baby in one month. So that was my last question for you today, Neil. You've been so generous, so gracious. Speaking of impossible, Sir Arthur C. Clark's third law says the only way of discovering discovering the limits of the possible is to venture a little way past them into the impossible. And that's the origin of the podcast name, as I am the associate director of the Arthur C. Clark Center for Human Imagination at UC San Diego, among other things that I'm involved with.

But accordingly, I want to ask you, what mysterious aspect of life? It doesn't have to be science. Of life perplexed you as a 20-year-old, a 30-year-old. And what advice would you give to that young man to give him the courage? to do as you've done to go into the impossible. Right. I think, and it may sound strange from a physicist, but I think the most fascinating thing in the universe is life

and the way it's organized. When I was young in my late teens, undergraduates, I wanted to go into biology and do mathematical biology and understand what is the law that governs life. that tells you that life will emerge. We still are none the wiser. I mean, but it's still the most fascinating question. So I think what I think what seems impossible now

is to make a predictive theory of life. Now, maybe even predictions aren't the right language for dealing with life, but somehow to gain an insight into what life is. You know, we know kind of the constraints life operates under, but we don't have any idea of, we have some glimpses maybe of how decisions are made. But, you know, there's a very sort of fundamental,

I've talked about entropy. You know, life violates the second law of physics, which is never going to change. that only things that happen are ones which increase entropy. And life sort of violates that by using energy to deliberate, to actively counteract the growth of entropy and to build ordered structures. And so I think it's absolutely this dilemma of what's driving life,

and where is it taking it? And can we understand that in any way? I think that that's the impossible. So just as an example, I have an undergraduate with me who in Edinburgh. He came to me six months ago and he's been reading all kinds of crazy books. He's actually doing engineering physics, but he'd read David Deutsch's book on something about impossibility. Yeah, something like that. It's an absolutely beautiful.

book, which I highly recommend. And we've been discussing, you know, the general question of the emergence of complexity in the universe. Universe is extremely simple on small scales, right? There's the Higgs and their laws of particle physics and that's it, no evidence for anything else. And then on large scales, utterly simple too. But in between, it's this horrible, complicated mess. And if we think in a bigger picture, where are we going? Where is AI? going to go, where is humankind going to travel into space, explore the universe, change the universe. So there's this enormous scope for complexity in the middle, while there's extreme simplicity at both ends of the spectrum. How do you describe or how do you attempt to model a system

like that, which is complex in the middle and extremely simple at the two ends, small scales and very large scales. And anyway, so he's an undergrad. And, you know, if, and I am telling him, I'm encouraging him to approach these impossibly difficult questions. I'm honest with him. You know, your chances of actually making progress a tiny, but it's incredible fun. As it is. And this has been incredible fun for me. And I hope we will be able to do a part two, Neil. This has been so great. Talking with Neil Turok, I've known and been inspired by for decades now. He's still so young and exuberant.

I can't believe you're an emeritus professor of Primiter Institute, that's at least director there, but you're now the inaugural Higgs Professor Chair at the University of Edinburgh. Neil, it's been such a delight. I thank you for staying up late or into the afternoon. I thank your dog for being very well-behaved. And I hope we will come apart two where we can get into consciousness, the brain, origin of life.

and a little bit maybe of commentary on your friends, Roger Penrose, Anna EGas, Paul Steinhart, on their bouncing models and contradistinction with your CPT and very happy with your CPT and very. For now, I want to thank you and bid you a good night over there. Thanks for the lovely questions. Thanks a lot. Thank you. Any sufficiently advanced technology is indistinguishable from magic.

Well, that's a wrap on part one. And you'll really want to stay tuned in part two, we get into the details of the low entropy conditions in the early universe, how the universe may be finely tuned in a certain sense to life. And of course, the answers to Neil by Neil to my thrilling three questions, which have now morphed into a fantastic four questions where I've added a question, see if you can guess what it is. But you'll have to tune in next time for Part 2 with Neil Turak. And before you do, I hope you will subscribe to this podcast wherever you're listening to it and leave a starish, highly constellation, rich-packed, star-filled

review, rating, rather, on any podcast player that supports it, Apple, Spotify, Audible, you can leave a celestial asterism. And on Apple, of course, you can leave a review, a written review, and I hope you will, because these are the things that guests look to, that other podcasters look to when they want to see if their guest or their author will come on to, I should say publishers look to when they want to come on the show. And I really get such delight from reading every single one. We have over 535 of them around the world. We have over 403 in America. And I hope wherever you are, you'll leave a review, including I'll read one of them that I just got recently from Harry 122.95. Fascinating. I love this podcast. It features

wide-reating conversation with some of the most interesting figures in modern science. Brian is an interviewer par excellence. Highly recommended. And you'll want to also, after you leave a review, as I hope, are a rating at least, go to my YouTube channel, Dr. Brian Keating, where the slides that Neil discuss the images are shown. Try to describe them in words, but it really bears importance and attention to, actually look at the slides if you can, uh, on my YouTube channel,

Dr. Brian Keating. So you can find it there. So for now, sit back, enjoy this voyage into the impossible that will continue in part two, that is, uh,

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