Transcription
There are no new particles that serve. Most people are again ringing their hands. "Oh, my model's ruled out." I take the opposite point of view. If nature is that simple, maybe the answer is nearer than we thought.
Hi. Uh, my name is Yang, and I'm one of the fellows here at the London Institute, uh, UK's only, uh, independent research institute for the mathematical sciences. Uh, it gives me tremendous pleasure to reintroduce our speaker because, uh, uh, if you were not here for the colloquium, it was brilliant, and you missed something wonderful, and it's your loss. And I'm here to introduce the second part, which is an extended Q&A, which is about Neil's, uh, life. So, we have, we're very honored to have Professor Neil Turac, who is the Hicks Chair of Theoretical Physics in Edinburgh, as our colloquium speaker and our Q&A, uh, speaker. Um, if you Google "Hicks Chair," the first thing that comes up is actually there's this company called "Hicks" that sells chairs in Edinburgh. [Laughter] And it's, it's Edinburgh, and it's in Edinburgh, and, and they sell very comfortable chairs. I think you absolutely should get them to buy your—
Yeah, definitely. In fact, this—
And, and in fact, we should have gotten one for you. And so, and it is also extremely appropriate that Professor Turk is the 1992 recipient of the Maxwell Medal from the IOP, and in this is the very room that Faraday and Maxwell would have worked on the Maxwell equations. So, it's double pleasure for us.
Um, I've been a stalker to Professor Torque all my life, um, inadvertently. I, when I was an undergraduate, uh, Neil was a professor at Princeton, and then he migrated to Cambridge University, where I did my masters. I just kind of followed him. And then when he was working on the episodic cyclic universe at the University of Pennsylvania, I happened to be a postdoc there. But I never had the honor of actually writing a paper with Neil. I hope that will change, uh, sometime soon. So, on, on, on my right, I'm just trying to get my directions wrong. On my right is our Chief Science Writer of the London Institute, Dr. um, Anono Batacharia, who will be conducting this very nice and personal view that you get, not of cosmology, but also of Professor Toro's life. So, I'll hand over to the guys. Thank you.
Thanks very much, Yang. [Applause]
Now, there's been a lot of hand-wringing, I think it's fair to say, in the theory community over the last decade or two over the lack of new results, um, new physics, hints of new physics at the Large Hadron Collider and elsewhere. But I got the feeling that you are not so worried about that, that you think this is telling us something quite different. Um, so could you, could you, uh, explain what that is? The message.
Absolutely. So, I think we've had incredible clues from observation, and the strange thing about all these clues is that the universe has turned out to be simpler than anyone expected. Uh, not more complicated, not random. Uh, it's highly ordered. Uh, you can describe everything about the universe on the largest scales we can see using, uh, the laws we already know plus five numbers. Maybe five sounds a lot, but the amount of data is enormous. And this data is very well fit by a model with just five numbers called the Lambda CDM model. It has the cosmological constant as the main component of the energy in the universe. This was conjectured by Einstein, um, around 1910 or '15, on the basis of no data at all. Okay. Uh, there was no cosmological data at that time, and Einstein said, "What would a simple universe be?" He had a theory of gravity, and he said, uh, "Well, let me introduce some kind of energy that is absolutely uniform, doesn't change in time, um, fits with relativity," and it's the cosmological constant. What do you know? This is 70% of stuff in the universe. So, surprise, surprise, 100 years later, uh, that's what we found. And it's a similar story with the rest of this model, that the universe has turned out to be the simplest model you could imagine.
Um, so most theorists are very disappointed by this. "Oh, I had a theory of all these extra particles and dimensions and forces and so on, and it's not there." Um, I take the opposite point of view. I think nature's turned out to be simpler than we expected. There are no new particles at CERN. Most people are again ringing their hands. "Oh, my model's ruled out," and so on. I take the opposite point of view. If nature is that simple, maybe the answer is nearer than we thought, because, you know, in simplicity, simplicity gives you hope that the solution is also simple. And, uh, so I think we've had huge clues from the observations about the cosmological constant, about the geometry of the universe. The universe is incredibly, has an incredibly simple geometry on the larger scales. It's what we call a flat space. It's not curved. On the larger scales, it seems to be exactly flat. Why is it so flat? Uh, when we look out and we see the radiation from the Big Bang, it's the simplest kind of radiation. It's called the thermal distribution of, you know, based on Planck's formula of quantum mechanics. Um, so, yeah, everything is turning out to be incredibly simple, and I think that's great because it actually means that there's that we may be able to get a unique, simple answer to what unifies the laws of physics. But in order for that to be true, so you, you've got to go back to the very basics. Um, why is space flat? Uh, again, that's a good example, because theorists like me have been postulating forms of energy which would cause the universe to blow up exponentially and flatten itself. Okay? As if you blew up a wrinkly balloon, and as you blew it up, it became flatter and smoother. So, people had invented stuff to add to the laws of physics which would have a consequence of blowing the universe up. Uh, that extra stuff, you know, there's no other evidence for it in the laboratory. It's something you're adding by hand. And I've taken it as my kind of philosophy of doing physics is that don't add anything by hand. Rather, try to see if the, the laws we know and the rules we know, uh, can be understood better, and maybe what we see is just a consequence of those laws when they are properly understood.
So, Neil, um, could you explain your model, right, that you have? As if, um, we were precocious school children. Right. Because that's about my level. Right. And, uh, you have about three minutes.
Okay. Explain everything in three minutes. Yeah. So, uh, the model is, the goal of the model is to build the simplest explanation for all the facts we see and know. Okay? And I'm going to allow myself to use all the laws of physics which have been established in experiments and observations: Einstein's theory of gravity, theory of heat and light and matter that we confirmed at the Large Hadron Collider. Uh, so I'm going to take the laws that we know from experiment as read, and then I'm going to try and come up with the simplest possible explanation for everything we see in cosmology and particle physics. Okay? So, basically, I'm tying my hands. I'm not letting myself have extra dimensions, extra forces, extra particles. I want to keep the bare minimum. Now, you might say that's totally obvious. Surely that's what physics should be doing. But it's not what people have been doing. That's the paradox. The field which I'm part of has gone into this mode of imagining all possible laws and all possible universes, called a multiverse, and being dazzled by the complexity of all these possibilities and not really making any progress on the fundamentals. So, the entire emphasis of my work is to rethink those fundamentals and try to understand how a correct understanding of the fundamentals will explain what we see.
Brilliant. Um, [Laughter] so I gather that your feeling is that there are some ideas in theoretical physics that it's time to retire them.
Yes.
All right. Yes. Could you talk us through what they—I guess inflation is one, right?
Inflation is one. Extra dimensions is another. Uh, these, I mean, I, I've worked on these ideas myself. We all did. Um, in many ways, I would say that when I started doing theoretical physics, it all went wrong. [Laughter] That was in the early '80s. Um, it wasn't my fault. Okay? But I participated in it, and it was very exciting. We had grand unified theories, we had supergravity, string theories, uh, M-theory, extra dimensions, you know. So, it was a great playground. It led to very important developments in mathematics, uh, because the tools which physicists develop, usually physicists don't prove anything. They just play around with mathematical machinery. But they can be very inspiring to mathematicians, uh, who then do actually prove things. Um, so that's been very fruitful, the engagement of physics and mathematics. But I never really cared about that. I wanted to describe nature. You know, for me, nature is everything. Uh, even mathematics is just a somehow a game. But nature is our guide. That's my philosophy. Okay. I'm not particularly religious, but in this belief, I am totally religious that the actual universe teaches us things. It always has done. It taught us Newton's laws of motion. Where did he learn it from? The solar system, right? By looking at the universe, we learn. And, uh, so I think that's what's really beautiful about theoretical physics. And I think I would say for the last, um, several decades, the community of so-called fundamental theoretical physicists have got themselves very confused and into a tangle. Uh, and the solution to that is to go back to the fundamentals, almost rewind history, go back to the '60s. Did we make some assumptions which were unjustified? And the answer, yeah, I would say is yes. Uh, very likely we assumed various things, um, uh, and, and then, uh, that led us down the wrong paths. So, for example, people give lectures, very brilliant people give lectures saying, "The only possible consistent laws of physics work in 10 dimensions." I won't name the people who—right, you know who it is, okay? They, they give a one-and-a-half-hour brilliant lecture proving that we live in 10 dimensions. And, yeah, it's all based on assumptions, and those assumptions don't hold up when you look at them carefully.
I think what's very important about your model is that it makes actual predictions, though. One which I think is going to be tested in the next few years.
Three or four years.
Yeah.
So, could you talk about that a little bit?
Yes. So, we started thinking about the Big Bang. It's the ultimate challenge in physics. How the entire universe came out of a point. You know, everything around us. According to Einstein's theory of gravity, the universe can expand, uh, and it is expanding into the future. But if I trace time backwards, it's shrinking. And so, in the past, 14 billion years ago, the theory says that every single thing in the universe was at the same point. All of space was shrunk to a single point. It's kind of ridiculous. That's the Big Bang singularity. It's the ultimate puzzle in physics. What, what the hell happened? And, uh, so, yeah, I think that's that's, um, that started us off thinking, you know, is there anything simple about the singularity which we've missed? And when you ask the question, you realize there is. And it turns out the Big Bang singularity is not very complicated at all. It's, it's a zero in an analytic function. Okay? Um, and you can extrapolate functions through zero, right? I mean, uh, and, and so that's what we did. Did this extrapolation, and then we said, "Well, can we predict anything using this?" The extrapolation told us that on the other side of the Big Bang was another universe just like ours. Okay? So, it's a mathematical extrapolation which says that the Big Bang is kind of a, you know, a transition point between a contracting universe and an expanding one. So, mathematically, you can describe it that way. So, we said, "Is there any prediction of that theory?" It's a pretty picture, pretty picture of a universe. Um, it means that, um, I mean, actually, I was very inspired by Stephen Hawking. See, Steven Hawking was trying to explain the beginning of the universe, right? And that's a very paradoxical notion: how do you begin something from nothing? Um, and so he had a very nice geometrical picture where you could think about the universe like an ice cream cone, where the slice of the cone is the, is a circle, right? That's the universe at any given time. And as you trace it back in time, it shrinks to a point at the tip. Now, the whole circle is at a point. What happens before? So, Steven's solution was to take this cone and round it. Okay? And so there was no real beginning. It was a, there's no special point. It all got rounded. And you do this in a mathematical way called going to imaginary time and so on. But he, he got rid of the beginning by smoothing it off. So, we instead said, "No, maybe the beginning is just should be thought of as a point of transition, you know, between a contracting, an ice cream cone going this way and one going that way." And mathematically, that makes perfect sense. Um, in fact, mathematicians have a way of resolving things like this called singularities. Um, and what we did is consistent with that. But we wanted a prediction. So, does this picture predict anything? So, the big unknown in cosmology is the dark matter. What is it? So, the cosmological constant is 90, is 70% of the stuff in the universe. That's great. But 25% of it is in the dark matter. Dark matter is funny. It, it clumps under gravity. It bends light due to its own gravity. So, you can see it literally through the way it bends the light. But, uh, it doesn't, uh, interact directly with the light. It's like water in this, you know. So, if I hold this up, so I can't see the water because it's transparent, but I can see it because it's bending the light. That's how we see the water. The dark matter is just the same. We can see it because it bends, uh, light, but we, it doesn't emit light or absorb light. So, 25% of stuff in the universe is like that. So, what's it made of? Made it's made of something which gravitates but doesn't interact with light. Um, and so when we thought about this, we asked ourselves, is there an obvious candidate for the dark matter, which is the minimal possibility according to the laws of physics we know? Now, every particle in nature has a left-handed version and a right-handed version, except for the neutrinos. Okay? So, electrons, um, can have left-handed. Left-handed means that if the spin is this way, uh, sorry, if the momentum is this way, if it's traveling this way, it's spinning that way, and electrons can be like this, or they can be like that. But neutrinos are only like that, okay? Uh, they only have a left-handed version. So, ever since the '90s, but neutrinos have a little mass. They're not massless. If they were truly massless, they, they would, uh, you would only have a left-handed guy. To get a mass, you actually need the left-handed guy to mix with the right-handed one briefly and then go back to be left-handed. That's how neutrino masses arise. So, this was realized in the 1970s, and people speculated maybe there are right-handed neutrinos, but they're very heavy. So, the left-handed guys only mix with them a tiny bit, and they acquire their small masses through that mixing. So, people have known about right-handed neutrinos since the '70s. They don't couple to the known forces except for gravity. Um, but, um, the question is whether our picture of the Big Bang could say anything about the abundance of these right-handed neutrinos. And the short answer is it can, and it can predict their abundance based on a certain symmetry called CPT symmetry. And, uh, so we predicted the abundance of a right-handed neutrino. Now, for this to be true, there's an indirect prediction, which is if one of the right-handed neutrinos is stable, then one of the light neutrinos, which are the ones we see in the lab, is exactly massless. Okay? So, that's the prediction of our model: that one, the lightest neutrino has zero mass. And then, amazingly, people are now measuring the mass of neutrinos by watching how matter clusters in the universe. You take a huge region called a cluster of galaxies. As it self-gravitates and clusters, how many neutrinos there are in space, you know, there are many neutrinos in that region of space. They came out of the Big Bang. If they're massive, they cluster a bit more strongly. And incredibly, astronomical surveys are now accurate enough that you can detect the mass of neutrinos through the strength of this gravitational cluster. And the observations are now just at the threshold of being able to tell if the lightest one is massless. Um, and so in the next three or four years, if they conclude that the lightest one is massless, we have to see a certain bump in a plot which I showed in my talk. And if the bump appears, this will confirm that the lightest one is massless, which indirectly confirms that the right-handed neutrino is the dark matter.
So, your hypothesis is falsifiable, which is a welcome change.
Yes.
For many people.
Yes. Very, very important. [Laughter]
So, anomalies.
Yeah.
At the LHC. Um, journalists, science journalists like me, we get very excited when there's an anomaly. Some physicists get excited too, and then they're frequently disappointed. But, uh, we haven't had one for many years. So, I don't know how long, 'cause I'm, I'm not, but it's been a while. And now, as you are aware, I'm sure, there is a B meson anomaly.
Yes.
How excited are you about that? [Laughter] And, and what happens if, if it is an anomaly, would, would your theory cope?
No theory would be wrong.
Right.
So, at any given time, there's always data which disagrees. Um, there's a gold standard in particle physics which is five sigma, and it's come about for a very good reason that there, there's always a two sigma or three sigma discrepancy between the standard model and the data. That's been a constant state of affairs, and then as experiments improve and improve, the deviation from the standard model decreases, and the anomaly goes away. So, we've gotten very used to, uh, you know, not getting excited because, because discrepancies have a habit of disappearing over time. Um, so, yeah, I, I mean, in a certain sense, I hope the anomaly survives. It would prove our theory wrong. That's great. I mean, I, I've worked on several theories which have been proven wrong, and I'm very happy about that. I would rather know that it's wrong than work on something and not know. Uh, in fact, I had a funny conversation with, it's a brilliant Indian astrophysicist called Chandrasekhar, and he came from an older generation, and he came to a talk I gave, and I was talking about a speculative theory called grand unified theories, which predicted structures called cosmic strings. And I found that very intriguing because if we saw one, we would see the evidence of this grand unified theory. So, I talked about this, and he came up to me afterwards, "Why do you work on these speculative theories? Very unlikely they're correct. Why waste your time?" So, I said, "Because they're testable. You know, if it's wrong, we'll know it's wrong." He said, "No, no, no. It's much better to work on a theory which you know is right, which is general relativity, and work on a problem of something which we cannot access as human beings." So, for example, we can't really go inside a black hole and survive. So, he was much more interested in taking a theory we know is correct and going to see what happens when you go into an unusual situation. Okay? And I said, "No, sorry." You know, I'm just, that doesn't interest me. I'd rather work on theories where we, there is a right and a wrong which we can know. Um, but, you know, his point of view is completely legitimate. He's a brilliant mathematical astrophysicist, but he was just interested in the, in the untestable domain.
So, on, on that note, actually, I, I did want to phrase your sort of intellectual journey into physics a little bit.
Yeah.
Starting from when you were very young. You were born in South Africa in apartheid South Africa. Yeah. And, uh, you moved to Britain when you were around seven, is that right?
Uh, no, I was, it was about, um, yeah, eight.
Seven. Right. Right.
No, nine. Nine. Nine.
And your, your parents were anti-apartheid.
Anti-apartheid. Yes. But as far as I'm aware, they were not physicists.
No. [Laughter]
And had no interest in physics.
No, I wouldn't say that. My, my father was a land surveyor. So, he taught me geometry, Pythagoras and all that. And he actually made maps, and so he had a calculator, a hand calculator at home. And, uh, so, no, he loved science. Um, but, um, the, the, the special thing about my parents is that they were convinced that apartheid was wrong, and they both went to prison for that. Um, and most people thought they were nuts. Most white people, most of our families thought they were nuts. Um, and they decided to give their lives for something they thought was right. And, you know, that was in the late '60s, and then, of course, in the early '90s, mid-'90s, uh, they were proven right. South Africa changed and became, you know, a multi-racial democracy. So, I was very fortunate. I learned from them that if you think something's right, you know, [Laughter] don't be afraid. Um, and I think that's given me an advantage because in theoretical physics, we spend all our time telling each other we're wrong. Okay? [Laughter] Uh, it's very common to give a seminar and somebody says, "That's wrong," you know, and sometimes they may be right. You should listen if they're right, but, um, yeah, you shouldn't be, um, afraid of challenging, uh, convention.
And so, you, you ended up in Britain. And at what point did you think, "I want to be a theoretical physicist?" Well, at what point were you drawn into physics, as a, when did you realize that physics existed even?
Well, it was strange because I actually wasn't interested in astronomy. Uh, the pattern of stars on the skies is pretty random. Uh, I was fascinated with life. Okay? So, when I was a teenager, I thought biology was much more interesting than physics. And, um, uh, I was actually a committee member of the British Entomological Society at age 13, and I collected beetles. Uh, and I thought nothing was more interesting than looking at beetles under a microscope. And, and I still am absolutely fascinated with, with insects and, and living things. Physics doesn't really explain life yet. It's very challenging to explain life. How did life emerge? You know, it's a, that's a very complicated thing, and that's a very deep mystery. So, I went to university to do biology. I took physics because it was easy. Uh, I found it relatively easy.
This was at Cambridge.
At Cambridge.
Uh, I mean, physics is easy. It's logical. There's a law, right? And you just work out the consequence of the law. It's relatively easy. Uh, biology is awfully complicated. [Laughter] And you have to remember to learn at a level.
There's a lot of facts. Yeah. A lot of facts.
But I loved biology. So, I took biology at Cambridge. The great thing about the Cambridge degree is you could take several sciences in the first year and then choose. So, I took biology. I wanted to study evolution. I had a very good advisor who gave me books to read about the theory of evolution, the mathematical theory of evolution. And very quickly, I decided this is, you're never going to be able to predict this. It's too much a set of accidents, um, and everything is a special case. And at the same time, I was doing physics, and people were telling me, "You can predict things to one part in a trillion, you know, using really simple mathematical laws." And so, at a certain point, uh, physics just— [Laughter]
I, I wanted to predict things.
Um, and in physics, you can do that. So, I was drawn over to physics. I abandoned biology. Um, and, but it wasn't really, uh, until after Cambridge that I got interested in cosmology. And that was because I went to Imperial, and my professor was Professor Kibble, who, um, was a brilliant theoretical physicist, and he sort of tempted me with a paper on how these grand unified theories predicted objects which we might see in the sky. Uh, and then I started working on cosmology. But, you know, then I worked on all these theories which I no longer have any confidence in, having spent decades proving them wrong. Um, and I've, I guess I've, you know, returned now to foundational. What I would say to anybody thinking of doing physics, and I didn't do this, but I would advise anyone, younger people, I would advise them: the more time you can spend on the foundations, the better. Don't accept the standard wisdom about quantum field theory or whatever. You know, spend a lot of time trying to think about, "What is quantum mechanics? What is spacetime?" Uh, the, the very basic concepts. The more time you spend on the foundations, the better equipped you will be to make a contribution.
And I didn't do that. Uh, and I regret that. That I, I went along too much with the current fashions. I think what was different about me, in some ways, was that I was always determined to test the assumptions and to look for how to, what observations will really tell you if this thing is there.
Yeah. So, you, you ended up at, cutting a, a longer story short, you ended up with a chair at Cambridge, prestigious chair. Uh, you're in the prime of your intellectual life. Um, I'm saying that because I'm about the same age that you were then. Um, and, um, then you get a call.
Dear. I'm on the way down now. [Laughter]
And then, um, and then, uh, you get a call from the Perimeter, and, and you say yes to running this relatively new institute. Now, many, >> theorists, many physicists, many researchers would say this was madness because suddenly, you know, you, you are drawn away from the thing that, that you love into, >> constant admin. So, what made you say, >> right, uh, yes?
Well, uh, that very simple thing. So, I'm South African, and as I said, my parents went to prison for fighting apartheid. And I, and they were absolutely right to do that. Um, and so I visited South Africa, and my parents said to me, "What use are you to the world, right? You're working with Stephen Hawking, worrying about the Big Bang. I mean, all this is irrelevant. We have a new country here that has people who need, you know, jobs, and the economy needs to work, and all that. What, what can you do?" So, I indeed, I was pretty useless. But the only thing I could think of was to start an institute for math at post-graduate level, because math feeds into everything. You can't really run an economy today without mathematical economists and planners and, and all of that. So, it's a big problem in Africa: lack of expertise in data analysis and, uh, providing good advice to government and so on. So, that was the only thing I could do of any value. And so, actually, I started an institute at their, uh, bidding, a small institute called the African Institute for Mathematical Sciences. And it decided that would be my contribution to South Africa. Uh, and it meant I had to learn how to plan institutes. Uh, so, um, I had a very good guide. My oldest brother is a business person, and I said, "How do I start something?" And he said, "Well, you need a business plan." I said, "What's a business plan?" [Laughter] "Oh," he said, "you start, explain, you know, calculate everything and see if it makes sense." And at some point, the, the ball dropped, the pin dropped, and I realized, "Oh, it's a theoretical exercise." [Laughter] Okay, I can do that. And so, indeed, I wrote a business plan, and we estimated everything and calculated what we would need and all the costs and space and everything, and thought it through very rigorously, and then raised the money for it. We started this institute, and it was just so exciting because it had, you know, the people who came were very bright, uh, and very, uh, excited to be in this institute. They came from all over Africa. We had lecturers from all over the world. So, I gained a lot of experience. It was really hard work. Um, starting something new is, is very, very tough work. So, I didn't sleep for a few years. I completely neglected my, uh, duties at Cambridge. Um, but Cambridge was great because we had relatively light duties, and they were willing to support me. Uh, so I started this institute, and that's why I got the call from Perimeter.
Right.
Is they knew I wasn't just, you know, head-in-the-clouds theorists. I actually had some experience with doing things. But it's totally different at Perimeter because Perimeter, they had lots of money, and in Africa, we had no money, okay? And we started this institute on a shoestring. And that's a very good discipline because then you have to do things correctly. Can't make mistakes. Physics. Uh, so when Perimeter calls me up, they say, "We've got $100 million. You know, uh, we want to start the best theoretical physics institute in the world." And I thought, "That's like falling off a log." [Laughter] Theoretical physics needs a bit of chalk and a blackboard, a few laptops, you know. You, you bring people are generally very willing to give their time. They love teaching. They love interacting. Uh, the best theoretical physics in the institute, physics institute in the world is just a space where people like to hang out. That's all it is. Really simple formula. So, I knew how to do this.
Um, but what was the situation when you took over? Because Howard Burton, who was the, >> founding director, right? He left. He'd written a book, >> right, which caused a degree of controversy, I think it's fair to say.
Yes, it did. And as a result of this book, he left under a bit of a cloud.
It's the other way around. He, he left under a cloud, and then he wrote the book. [Laughter]
Um, no, to be fair to Howard, Howard did a brilliant job. So, imagine you meet a tech entrepreneur, and the guy says, "I want to give $100 million, uh, to start the best theoretical physics institute in the world, institute in the world. You know, can you do it?" And Howard was a fairly recent physics PhD, but not a brilliant physicist. Um, yeah, not much experience. Howard said, "Well, this sounds exciting." And you can only imagine the ways in which it could have gone wrong. [Laughter] You know, somebody so young, it could have, the easiest thing in the world is just a waste of money. But he didn't. Uh, he had very good ideas. He started public lectures, um, and did them very professionally. Everything he did was very professional. The institute was a very professional space. Um, it had a gym. It had a nice bistro. You know, theoretical physicists come to visit. What? We're treated like, you know, royalty when we're here. So, they love to visit. And you give free coffee. Uh, you know, theoretical physicists are really cheap.
[Laughter]
Free coffee, good blackboard, you know, reasonable food, um, and, uh, and they think, they think they're in heaven. So, it was a very smart move because it did something which no university in the world was doing. And I, I worked in Princeton, I worked in Cambridge. Universities are organized incredibly badly in terms of encouraging truly original thinking. So, what you're, you know, all the original ideas come from young people because they come in and question everything. Okay? That's the real source of energy in the field. It's the young people. And so, how do you treat young people in university? Well, we put them through exams. Exams. Exams as undergrads. So, a lot of standardized testing that kills originality. Then they go into a PhD, and, uh, usually they're working under the wing of somebody more senior. So, they're following, following, following. They don't have the confidence to question the basics. Um, and then young faculty come in. What do you do? You give them a huge teaching load. They have to apply for grants. That takes up most of their time. They have to try and get tenure. If you're in the US, that means you do something that will make it highly cited, means you're going to be conventional. Uh, and, and so, kind of risk-taking, original thinking is absolutely discouraged. So, [clears throat] now, you do the alternative, which is what Perimeter did, and Howard did this. He said, "Bring some really creative, original people, you know, just make this space where people question the, the foundations." And, you know, things happened. Uh, so, the first few years, it was kind of sketchy, uh, and flaky, but a lot of fun. Um, and the problem they had is that they, Howard went a little bit crazy. I hope he won't mind my saying. [Laughter] That because, um, you know, expectations were very high. It's a high-pressure job, and he'd never really held a position in a, you know, major university. So, then I came in, but he'd laid really good groundwork. So, my job was to think, "How do we actually make this place a focal point internationally?" So, it's in a boring town, middle of nowhere in Canada. Absolutely nothing exciting about the natural environment. So, you have to make a beautiful building, which he had done the first part of. And, um, and then how do you kind of build up the buzz? So, that was my job.
Right.
So, I got Stephen Hawking to visit. Easy way to build up buzz. Uh, invited the top physicists. I mean, I did things quite differently than you would in a university. You're trying to make this place a focal point. So, what do you do? Well, you think of the top, you know, the most, um, original, important theorists in the world, and what would it take for them to come and visit regularly? Okay? So, they're really cheap. [Laughter] Okay. So, it doesn't cost much, because normally we're not paid anything in theoretical physics [Laughter] for giving a seminar. There's no fee, right? So, you just say, "Okay, I'll support you at X," that I won't say how much, but not much. I mean, if you think about the actual cost of peanuts, uh, and they feel so honored, and then you give them a title, you know, we say, "You're the Distinguished Visiting Research Chair." Everyone loves a title.
This is, this is our playbook, essentially.
Yeah. So, it's, when you do think about it, it's not difficult, >> because all you're doing is making a welcoming space where you recognize that the very hard thinking people do is valuable. Right? Because mostly, a theorist working in a university, you know, sits in a corner office somewhere. Nobody cares what they do. Um, uh, that, you know, they've gone off into some imaginary world, and, and who cares? So, they're not typically valued at all. Uh, you tell them they're really important, they love it. Um, and then, and [clears throat] then, you know, because of what I'd learned about students in Africa, actually, I developed this model for M.S. level training, which involves, um, uh, a curriculum which exposes you to many fields without giving you a systematic training. You see, what typical universities do is they say, "Okay, when you've graduated, you have to choose a specialty, and then you just go and study that specialty." But you're not ready as an undergraduate to make an informed choice what you do with your life. You know, you're going to choose some corner of, I don't know, two-dimensional conformal field theory or something, and then you're stuck for life. Much better to spend a year being exposed to all the cutting-edge areas in physics, and then you choose what you want to do. We just, we don't do that in any university. It's ridiculous. So, most people make a choice based on extremely limited information seen at undergraduate level, which is the old stuff, um, not, not cutting edge. So, I'd learned this in the Africa project, and so we implemented the same thing. So, we started a master's program called Perimeter Scholars International. We recruited the best master's graduate students in the world to come for one year, be lectured by the best theorists in the world who are also visiting, and just be exposed to the full range of theoretical physics, and then they decide what to do, and then they go off and do a PhD, master's, or specialized master's or PhD. So, rethinking how the discipline operates, and in particularly on training people and giving young people opportunities. You know, you don't have to think long to realize the current system is hopeless. Uh, and it's very, ex, you know, it's very inward-looking. There's, and especially in the developing world, it's just an ocean of talent out there, most of which doesn't have access to advanced training. And likewise, we don't have access to them because there isn't a good route for them to get to, you know, an excellent place. So, it's all about creating access to very talented, unique, sometimes strange individuals, okay, who are able to to do something really new.
So, Howard Burton's book explained why he chose particular areas, I guess, of science: quantum information, string theory, and so on. Were you happy with those choices?
By and large, yes. And there were some inspired choices he made. Uh, one was quantum information.
Yeah.
Which, at that time, wasn't a hot topic at all. And even more inspired was quantum foundations. So, Howard decided that he's going to actually have physicists working on the foundational principles of quantum mechanics.
Which was a branch of philosophy, basically.
And I think we'd all been to talks on this would be 10, um, 20 years earlier on, yeah, as you say, philosophy didn't go anywhere. But just at that time, when Perimeter was starting, quantum information was interacting with quantum foundations in a very interesting way. Um, and the idea of quantum computers and so on really made people rethink, "What is the difference between quantum mechanics and classical mechanics?" And, "What are the opportunities in quantum mechanics?" So, Perimeter went for these, this area, quantum information and quantum foundations. That was extremely, um, uh, in, was far in advance of anywhere else in the world. And if, if you were choosing now, you know, we're, we're a fairly young institute. What would be your choices for areas to develop?
Well, I think the foundations are key.
Um, and so, yeah, it's, it's hard. I don't think I've got a simple formula for it. Um, you know, obviously, I think what, what we're doing is, is a good [Laughter] direction. I think trying to get people to figure out, um, to, to push the boundaries of known physics, um, in original ways, uh, tackling problems like what's going on in black holes, what's going on at the Big Bang. Um, so, I always think, sort of, the problems have to be inspired by something real, some real phenomenon. Um, but then they've got to push the theoretical methods and techniques and concepts further than they have gone before. Um, but the short answer is that you just got to look really widely for unique people. The people define the interesting approaches. I don't think you should predefine the. I, I'll give you one example. So, one of the best hires I made at Perimeter was of a guy who did a pure math PhD in algebraic topology. Then he figured he wasn't going to be the best mathematician in the world. So, he went into, uh, computer company, software company, worked on software for three years. Got bored with that. Came back and did a PhD in cosmology because that seemed to be more kind of, uh, practical, dare I say it. And [Laughter] so he then wrote, because of his very strong background in pure math and algorithms, he then got involved in the Planck satellite, which made these beautiful maps of the cosmic microwave background and had the biggest database of any cosmology. And he managed to write a code which was doing the optimal statistical analysis of this data set. And before his work, no one thought that was possible. They thought that this is just too big and too messy and too complicated a data set. It cannot be optimized. Well, he optimized it. Okay? And the consequence was is they came out with much stronger results than anyone expected. In particular, they ruled out what's called non-Gaussian fluctuations. You know, what we see in the sky is the very simplest type of noise called Gaussian random noise, or the bell curve, bell, bell curve distribution. Um, he ruled out deviations from that simple distribution. Very impressive. So, he then, because, you know, and again, you, you feel something is in the wind, you know, software, big data, connected to somebody who's really good at math, knows a lot of physics, you know, something's going to happen. So, he comes to Perimeter, and he, I, so, first thing you tell, again, this is what you should do to young people: you don't have to work on anything, okay? You don't have to get a grant. You don't have to publish a paper. Okay? Find something you find really interesting and run with it. So, he says, "I want to work, uh, I want to join an experiment." Radio telescope. It's a very original, uh, radio telescope in Canada, very cheap radio telescope. The unique thing about it was it was attached to a huge supercomputer on the back end, and it was making the inter, the maps of the sky by interfering the signal from different receivers in software, which was a first. So, normally you do it by building a big dish. You focus the waves on your detector, and the dish is the focal. You focus the telescope with a mechanical, with a, you know, large structure. You don't need to do that because you just have lots of independent detectors, and you focus it in software. That can now be done with GPUs and storing on hard drives and so on. So, he did that. Then it turned out this telescope detected fast radio bursts on the sky, which are flashes of radio waves. And this telescope, which wasn't designed for this, became, thanks to his software, became a hundred times more powerful. It would cost $10 million. It was then 100 times more powerful than a $1 billion telescope built in China. Um, uh, and, and it became world-leading. So, you know, that's an example of something where you hire somebody who's obviously very smart, give them a ton of freedom, and just say, you know, "Find something interesting to work on." That's what we should be doing, young people. Um, that's rather an applied case, you know. In pure theory, it's more difficult.
So, actually, talking about young people, I'm going to, um, start wrapping up. But the question on many people's minds, yeah, is AI. It's artificial intelligence. The impact of that on, um, maths and theoretical physics in particular, loom large.
Right.
Um, I mean, the impact on, >> every creative human endeavor is, is beginning to loom large. What's your view on that? Have you ever used AI?
I use it all the time, but, but just to do references. [Laughter] [clears throat]
I mean, it's great. You could just type in, "What's the, you know, what, give me the citation of this reference," because my memory is [Laughter] it's really good for fairly mundane tasks. Um, yeah, I think basically, I would say that if AI can do it, I'm not interested in it. [Laughter] And I mean, the realm people are worried because the realm of AI, >> no, it's expanding. Yes. So, some very brilliant mathematical theorists, including people I hired at Perimeter, would say, "Oh, we've got 10 years. You know, 10 years' time, that AI is going to take over."
And just be much better than what we're doing.
And my answer to that is, "You can't be doing anything interesting." That's what's going to happen. So, I would just take that as a challenge that you should be doing something more interesting. Um, [Laughter] so I don't personally feel threatened by AI. I think in terms of getting stuck in, uh, current paradigms, which is exactly our problem, AI is not going to help with that. I, I don't believe, um, it's going to, because it tends, it's dominated by conventional interpretations, you know. Um, and that's exactly the opposite of what we need. We need to reexamine our foundational ideas and see how do we generalize them or go beyond them or simplify them. Uh, so I see AI being it.
was a very recent paper where AI was used to get a really simple formula for scattering, and yeah, it was very impressive. It could take this really messy, long algebraic expression and compact and and and many instances of it, and then see what, what is the simple formula. But, you know, it's not a very interesting problem. This is a big, messy calculation. Okay, there's some simplification. I don't think that gives you an insight.
Some people claim that huge complicated mathematical calculations are in fact a kind of data, and that if you understand that data, you will get to the underlying theory. And I don't believe that at all. I think that, uh, the best theories we have don't work like that at all. They, Einstein didn't get to GR by looking at a bunch of really complicated Newtonian calculations and saying, you know, this is too messy. You know, here's a simple formula. He didn't get there that way. He had an intuition. Um, so I don't see AI replacing that anytime soon. Um, and yeah, I would say to anyone who's worried about AI taking over their job, they're just saying you should be doing something else.
So, we have, we have people from Google DeepMind in the audience. Um, so I'm sure there'll be plenty, uh, plenty to say about that one. >> Um, >> Yeah, I mean, all these, um, AI people, DeepMind, I mean Demis and who I know reasonably well, you know, and, um, OpenAI and all these people say, you ask them why are you doing this? Say, oh, we want to solve physics. >> Why? I'm sorry, you're not going to do it. No chance. [laughter] >> So, on that note, >> that's my, that, that, that's my prediction. That's my prediction. It won't be them. >> We're going to wrap up because I'm sure there's going to be loads of questions. It, it'll be a young person who looks at things differently, and it's going to be somebody a little bit odd [laughter], most likely coming from an unusual background >> in theoretical physics. Odd. >> Yeah. [laughter] Even odder. We need these oddballs who look at things differently, and suddenly things will click, and they will realize where we should be going. So, that I will predict is what will happen. And I'm very optimistic about that because we've got so many clues from all these observations about how simple the universe is on very large and very small scales. And if we can't infer the laws of physics from that, you know, we should be shot because, you know, Einstein had very few clues. He had the equivalence principle, Galileo, I mean, almost nothing, and he got GR. You know, we've got so many more clues. Uh, we can see the Big Bang in, in the sky. I mean, we should be able to work out what happened. So, I'm really optimistic that a young person is going to come along and put it all together, and that will be the next leap forward in physics, and the AI is just going to confuse things. >> Wow. Um, so Neil, before we go to questions, >> Okay, >> I'm going to talk to you some more with what is fast becoming a tradition. Um, if you can call it a tradition after three examples. That's our rapid fire round. Okay. I know you've done this kind of thing before, so you're not going to be scared. Um, I'll do, uh, I'll, I'll just do a few because I, I think we should go to questions really soon. I'm going to turn that over, then I'll ask you a question. >> Please don't. This is actually quite a long time. >> Okay, [laughter] don't take the whole >> So, don't take the whole thing. I won't. Okay. Right. So, what is the most important quality in a great theorist? Humility. >> Very good. All right. That's [laughter] [gasps] um, you're talking about the mistakes and >> I'm talking about being willing to be wrong, to be proven wrong by >> Yeah. Real data, observations. >> Okay. Are we living through a golden age of theoretical physics or a stagnation? >> Golden age. >> Why do you say that? >> Because we can see the whole universe. And what more do you want? The universe is the large Hadron Collider writ large. I mean, I, I, me, we can now see black holes merging, emitting gravitational waves, right in perfect agreement with Einstein's theory. It's incredible. This, um, the guy mentioned that who wrote the code to make the software telescope work. Uh, we can now see neutron stars colliding. What is that? It's two giant atomic nuclei, right, kilometers across, atomic nucleus, that's a neutron star, and we see two of them colliding, very high energy phenomena, all kinds of amazing physics happening in front of our eyes. All we have to do is watch and and learn. So nature is doing these experiments all the time. By the way, these events are happening on the sky, um, millions, if not hundreds of millions of times per day. So, we just have to watch them. And we can do this using radio telescopes. I mean, that, that should be the LHC of the future. Radio telescopes watching the universe. We're going to see gravitational lensing, measuring the dark matter. You know, the universe is the most incredible laboratory, and we just have to look at it. Somebody else is doing the experiments. >> Okay. And somebody else did the Big Bang. We just have to watch it. >> So, I think we have a huge number of clues. >> You're about to run out. Well done. [laughter] Um, right. As a cosmologist, what do you think of the chances of there being intelligent life in the galaxy? [clears throat] >> Well, one instance is, does that include us? >> No, [laughter] >> I'm not sure we're that intelligent. >> Dolphins, you know, octopus, you know, all these, these are out outside. >> I, I, it seems to me the chances are very low in the galaxy. Uh, unfortunately, they're even low in the whole visible universe. Uh, the reason I say that is we do not see any evidence of anything in the universe being manipulated in a manner different than the basic physical laws. Right? The law, basic laws of physics seem to work everywhere, and they don't require anything. I mean, anyone intervening would have messed them up. So, the, the universe seems to be extraordinarily, you know, simple and operate according to these simple laws. Um, there may be, may well be life, but I, I, I don't believe there's going to be, uh, sort of hugely capable intelligent life out there. I mean, I wish there were, but I, I'm not optimistic. >> That's, uh, yeah, um, >> we may be alone. We may be alone. Uh, and if we're alone, that just emphasizes how precious, uh, we are, and I wish people would focus on that. We have to look after this planet. We have to look after each other. We can't, um, yeah, we should really, as I said, I'm not very religious, but I think we are absolutely blessed, and certainly we're failing to appreciate that at the moment. Uh, we're taking so many risks with our future. It's ridiculous. >> Right. Okay. Last question then. What question should I have asked you but didn't? >> Um, what's the, Okay, you could have asked, what is so special about being a theoretical physicist? >> What's so special about being a theoretical physicist? And I would say this, and particularly for young people, uh, through being a theoretical physicist, I have met the most incredible people. Um, it's because it's such a ridiculously ambitious field, you know, where we're trying to do something which is essentially impossible and way beyond. You know, we're trying to follow in the footsteps of Faraday and Maxwell and Einstein, who saw, had these amazing insights which really work, you know, and we're trying to follow it. It's very difficult, but because it's so difficult and it's so, uh, fundamentally beautiful, um, it brings amazing people together. So, through, through that, you know, I got to meet, you know, I introduced Stephen Hawking to Nelson Mandela. [laughter] That's pretty fun. >> They're actually rather similar personalities, as it turns out. >> Who's more starstruck? >> Uh, Hawking. [laughter] Yeah, Mandela was very confused by Hawking speaking through his computer because Mandela had gone to prison before, um, computers, PCs. So, he's not familiar with computers at all. He's a very bright guy, has a great sense of humor, very warm personality. That's why I say they're similar. They're actually very similar in their sense of humor and, uh, sharpness. But he doesn't know anything about computers. So, this guy rolls into his office, and the voice comes out of the computer, and Mandela, [laughter] what the hell is happening here? So, yeah, unfortunately, it wasn't really a great meeting of minds. [laughter] Um, but Mandela remembered my parents. He's got a phenomenal memory, who he, you know, had barely met after coming out of prison. They weren't. But your mother was elected to, uh, the government. Both mother and father. Mother and father. >> Yeah. So, you know, but he's dimly, dimly aware. But yeah, he met me. Here's the name. Oh, you're Benny and Mary's son. >> How the hell did he think of that? And he was like 80 at that time. So, phenomenal. Um, uh, yeah. Um, focus on people. Um, so, yeah, I, I've got to meet some incredible individuals through physics. And I would say, if you join this kind of ridiculously ambitious pursuit, that's the fun part of it. You only live once, right? You might as well try and do something impossible with your life. And if you do try, it doesn't have to be physics, but if you try and do something impossible, you are going to meet some extraordinary people. Um, and you'll probably learn something. I mean, if you do something ordinary and predictable, you, it's not going to happen. [applause] Okay. Um, we have some time for questions. So, uh, Yang will take the microphone around. Do we have any questions? As a 2D conformal field theorist, I suspect I'm slightly smarting from your your earlier remarks. >> Sorry. Sorry. Um, but I was just thinking in terms of, um, you know, you say that we shouldn't sort of naively or, you know, we shouldn't suppose anything written down almost, uh, and I'm just wondering, you know, does that not fly in the face of, you know, sort of the almost Diracian approach to theoretical physics where, you know, he came up with this, you know, he wrote down admittedly sort of quite reasonably justified equation, uh, which nonetheless predicted sort of negative energies in quantum mechanics, and then was only sort of experimentally vindicated a few years later. >> Yes. >> I mean, could you not sort of extend the same principle to extra dimensions and, you know, other concepts in high energy theory? >> I think his, he, his idea was, uh, much more radical because, as you say, at first sight, it was ridiculous. The predictions were totally ridiculous. So, he had to sort of rescue these negative energies by filling the Dirac sea and all kinds of, you know, so he did everything to make this work, and I think that's exactly the kind of adventurous thing we need. Uh, whereas just supposing an extra dimension, I don't find it adventurous at all. It's just saying, you know, there's more than three dimensions of space. Is not a particularly imaginative idea, and it's been around for a hundred years for Luttinger-Klein. So, you know, try something new, I would say. I mean, I met Dirac, uh, was very lucky. Uh, I met him twice. Uh, first in Erice, Italy, in a summer school. He, he's one of the incredible people I met. Um, and he spent an hour telling us that the only important problem in theoretical physics was the number 137 [laughter], which is the inverse of the fine structure constant. So, we had to explain that, and everything else was a waste of time. So, you know, we sat through it politely and then went on with our lives and ignored him. Um, and then I met him later in Edinburgh. Peter Higgs organized the summer school. Peter Higgs is another incredible person. Organized a summer school. The, the quietest, shiest person you could ever meet is Peter Higgs. Um, and I think he wrote five papers in his entire career. Okay. So, absolutely unproductive. He never won a grant. Okay. He struggled to get promoted. I mean, he, he, and he did the most important work of anyone in the university. So, um, anyway, so Peter invited Paul Dirac to come, and Paul Dirac was there, and then somebody working on supersymmetry, I think it was Peter West, said to Dirac, and I was there, you're always quoted as saying that, um, you know, you find beautiful mathematics, and then the, the way to find new physics is to look at beautiful mathematics. The Dirac said, "Yes, I did say that." He said, "But people don't quote the second part of what I said, which is that if it's not experimentally confirmed within five years, drop it." [laughter] And and and that shut Peter West up. [laughter] So, yeah, no, I mean, of course, Dirac was very dismissive, and and given what he had achieved in his early life, you could understand that he was very critical of everyone else, but, and he didn't really find new avenues after his early work. So, yeah, so I would say try and be radical, but cleverly radical. Um, you know, but it's hard to encourage anyone to follow Dirac. Virtually impossible standard. >> Do we have more questions? >> Yes. No, we need to do some >> I should say, uh, Frank, can you introduce yourself? >> Should I? [laughter] Well, Frank, I'm, I'm a a trustee of the RARI, so I'm here. >> Okay. >> Within that context, um, you ask for a lot of advice for younger people. So, I'm [laughter] um, I, uh, I left the field 30 years ago. I had to do something else for a living. So, I'm approaching sort of a time in my life where I have more time, and going back to physics is something I would have in mind. And, um, you cited 10 dimensions. You cited foundational questions. Would I be right in thinking that the whole idea that an anomaly means a degree of freedom that starts traveling in quantum theory that we haven't fully understood that as a point because that's the reason why we get to 10 dimensions to get rid of the, and I know in, in your theories, you're struggling with >> So, central. Yeah. >> No, exactly. So, I think, uh, looking at places where the theory seems to break down is our best clue. Um, and anomalies are situations where divergences, infinities, which we somehow know are wrong. I mean, we've got quantum field theory. It has infinities. We know they're wrong. By the way, Paul Dirac, again, from this summer school, said if you do any calculation and it involves an infinity, you shouldn't believe it. [laughter] So, he never believed renormalization. I mean, although he, you know, founded the, the QED, he, he wasn't in the fact that it got the right results in the end was not convincing to him at all. He still thought the logic is somehow wrong. So, these in divergences in some cases lead to a real violation of the principles you thought you had built the theory on. You know, you started with some theory and framework, had some principles, and and then these divergences come along and spoil them. So, indeed, I think anomalies are a, a very, very important guide. Maybe you change the principles, maybe you, uh, yeah, reinterpret things differently, and and anomaly cancellation is what got superstring going in the first place. So, I think that was a good reason. Um, but what I, what I don't like is just adding stuff. So, if you simply are adding things to cancel anomalies, uh, that's not a, a real theory. Um, and I think adding extra dimensions is part of that. There's no evidence for extra dimensions. It's, if you think, I mean, extra, when you add an extra dimension, there can be a whole universe in the extra dimension which we're not seeing. It's the most, um, it's the, it's the sort of most exuberant addition of stuff to add a whole dimension. I mean, is really overkill. Uh, and I think Roger Penrose argues this very, very compellingly that, you know, you're adding infinite degrees of freedom in with just one extra dimension, let alone seven or or whatever. So, yeah, I think, I think it's, it's overkill adding extra dimensions. Uh, I don't think it's that interesting an idea, extra dimension. Uh, it's, it's too straightforward a generalization. So, Neil, I'm sorry. Um, I'm out of wine. >> Okay. [laughter] >> And and you're nearly out of beer. And you're nearly out of beer. I think, um, if there is one more question that's non-technical, because you, you can, you can quiz Neil about his theory afterwards with when we have food. Um, but if there is a non-technical question, um, I'll pass you. >> Thank you. Go ahead. >> Do you believe in God? Uh, >> that was on my list, but I didn't get a chance to ask. [laughter] >> Okay. So, my answer to that is, I know a lot of people who do, um, and I see that it gives them something very important, and in some cases, very positive. So, I am not at all dismissive, and I think people who try to argue rationally, like Richard Dawkins or whatever, that religious people are stupid, uh, I think they are completely wrong. Um, we all, at some level, we all believe things which we can't fully justify [laughter], right? And God is a sort of label for something you, you believe in a purpose or, or, you know, an ethical principle. Um, and that, that's very important for many people, and often it's really helpful for many people, and it has positive outcomes for many people. So, I don't see a, I think the kind of physics or science we do does just doesn't provide a substitute for that, and we shouldn't pretend that it does. If you really ask me what I believe in my heart, you know, why am I working on such difficult theories and losing sleep night after night because it seems to be inconsistent or whatever? It's because I think this is the most profound, uh, privilege you can have is to wonder about how things actually work. Um, why they work is above my pay grade. [laughter] Okay. But just wondering how they work is, uh, is a very profound way to appreciate. So, I almost do theoretical physics. You know, I would compare that as somebody praying or worshiping or whatever. You, I go into a Zen state, and I view myself as kind of, if you like, praying in that by trying to understand or calculate or whatever. It's an, a way of appreciating the world. >> But the answer is not quite, uh, >> You know, I don't know what it means. I don't think anybody does, >> but I don't dismiss it. >> Okay, if we could, uh, give Neil a round of applause. [applause]