Neil Turok on the simplicity of nature

Hello Neil Turok. Thank you very much for joining us in the conversations on the perimeter. My pleasure. So I must say that I have always enjoyed when I have had the opportunity to speak with you over the years. And one thing I find particularly impressive about your work is that you have such a deep understanding of the big picture and goals of fundamental physics. I think this is particularly difficult for researchers like me, who can perhaps get a little lost in technical difficulties and calculations. So I want to start with a very broad question. Well. How would you describe the current state of research in theoretical physics?

It's very interesting. It has grown into a very large field. There are tens of thousands of researchers around the world. At the same time, I think it's enormously diversified. The part that fascinates me most is the fundamental understanding of the universe, whether at very small scales, as in particle physics, or at very large scales, as in cosmology. And that part, I must say, has benefited, on the one hand, from incredible observations. On a small scale, we have the Large Hadron Collider, the most powerful microscope ever built, which shows us what subatomic particles look like. And on a large scale, we have data that shows us the entire visible universe, with exquisite precision.

So it has definitely been a golden era, in that sense, and I, although from a more theoretical point of view, would say that the panorama is more varied. Since I started in theoretical physics in the early 1980s, there have been high hopes for a number of research programs, grand unified theories, supersymmetric theories, string theory, supergravity, m-theory, etc. And I have to say that they have not yet produced results. It is very surprising that there is still not a single prediction that has been verified from any of these frameworks. So from my own point of view, on the one hand, one can wring one's hands and say: why hasn't the theory been more successful?

Over the last 40 years, all the theories we have verified are essentially pretty old theories; Einstein's theory of gravity, the Higgs boson theory, and the Standard Model have been verified with increasing precision. But the new ideas have not worked. So you can say, you know, feel quite upset and disappointed about that. No. I think what is happening is that

nature

is speaking to us and telling us that he or she is simpler than we expected. Because what these observations reveal is a surprising minimalism. You know, we don't find any more particles than we haven't found when probing the universe at very high energies now, at the Large Hadron Collider.

And on a large scale in the universe, the universe appears to be about as simple as it could be, and yet it gives rise to galaxies and stars and the structures that we observe. So this is tremendously exciting because I think the

simplicity

indicated by observations points us to new principles, and those principles will be profound and universal, highly predictive and highly restrictive, and they will constrain the universe to look something like what we see. So, you know, while you might naively expect the universe to get more and more complicated as you go to larger scales, it seems to be quite the opposite.

And I find that extremely exciting because it means that maybe, in fact, the scales that we live on and that we operate on are perhaps, in some sense, the leading edge of complexity in the universe. The universe is much simpler on a small scale, much simpler on a large scale, and that helps put us in context. And maybe if we understand the big picture, the universe on very large scales, we will somehow understand where we are in the universe. And I'm particularly excited about our recent work on the big bang. You know, this is the deepest puzzle in all of physics: how everything arose from one point.

And I think in the last year or two, we've really started to make sense of that. And again, it indicates that our new understanding is that the Big Bang is actually quite simple. It is not an arbitrary, chaotic or random process. It is a very precise condition, I mean, if our theoretical ideas are correct, it is a very precise boundary condition for the universe and a principled boundary condition. And if so, then the universe becomes much more understandable as a whole. And as you said, many other researchers work on more complicated theories that do not embrace minimalism as observed.

Why do you think others tend to deviate from these simpler ideas? I think we are all trying to follow the example of Maxwell with Maxwell's equations or Dirac with Dirac's equation, Einstein with Einstein's equation. These are tremendously principled economic mathematical equations that govern a bewildering variety of phenomena and are extremely predictive. So we're all trying to emulate, you know, these highly successful theories that we base our current theories on. But I think what happened is that particle theory, over the last 50 years, maybe more, got into the habit of always postulating new particles. And to some extent, this was natural, because every time you built a new accelerator, you discovered new particles.

And this became the norm: you know, we expect to add some new particles from time to time. And the hope arose that by adding these new particles, we would eventually simplify the picture. So, in grand unified theories, for example, we try to make sense of the pattern of particles that surround us by adding a few more particles, and in such a way that the whole becomes unified. And that habit persisted, but it became widespread. So instead of adding particles, people added extra dimensions of space and extra objects. So there were strings in string theory and membranes and higher dimensional structures, which were added to these theories, all in the hope of unifying this in the first place.

However, some principles were missing in the country. So string theory, you know, doesn't really have a clear conceptual basis or principle in the same way that Einstein's theory of gravity did. You know, in Einstein's theory, the conception was that you have a curved spacetime and this curved spacetime tells matter how to move and, in turn, matter tells spacetime how to curve. This is how John Wheeler described it. And those words, you know, in addition to being very beautiful, they capture a concept of how the physical world works, which is very intuitive and very powerful, and when translated into mathematics, it becomes highly predictive.

But string theory has lacked such principles. And it's been more a matter of following your nose, and when you come across some phenomenon, you modify the theory or adjust your interpretation. And particularly in cosmology, a fairly popular effort in string theory has been to try to imagine the universe as being what's called an s-matrix. An s-matrix is ​​something used to the way the cosmos works seems very, very different than an s-matrix. You know, there was at least in the part of the universe where we can see that there was a starting point. And, you know, there's this end point that's dominated by the energy in empty space, the cosmological constant, sometimes called dark energy.

And so I think trying to shoehorn the universe into a preconceived picture, which was designed for particle physics experiments, seems to me to be, you know, a kind of search for a principle, but not one, that is particularly likely to work. MMM. So I think people have been trying to find principles that are economical and powerful and that explain a lot of things, but to a large extent those principles don't seem to be the right ones. MMM. And as I say, the enormous

simplicity

of

nature

is suggesting that there are principles to discover. And yes, I am hopeful that we are starting to go down the right path.

I have heard you say that a key ingredient to doing this work is having a lot of dialogue between theorists and experimentalists, but this is not always easy to do, and I think that is true. There is often some division between these areas of research. So how do you think we can improve this and have more effective collaborations between theorists and experimentalists? Well, I think it's difficult because both theory and experiment are very technical. When I started as a PhD student, it was very notable that the theorists where I was at Imperial College had their own seminars, and the experimentalists had their own seminars, and generally never attended each other's seminars.

So the high level of technical complications in both aspects of science means that people often don't have time to interact much with each other. And that's, yeah, that's very sad, because I think theoretical physics should be, you know, at its most exciting and most effective, it should be connected to observations. And there has been a sort of increasing divergence between so-called pure theory and observations. And even a kind of philosophical justification saying, well, you know, if we know our theories well, for mathematical reasons, we don't really need to pay attention to observations. And I'm very critical of that view, because I think it's very easy to get your mathematical assumptions wrong and, very quickly, just deviate from anything that has to do with reality.

It is necessary to be attentive to the observations. It may not be very detailed, you know, very detailed. You don't need to get involved in experiments or data analysis or anything like that, but you do need to pay close attention to the main observational results. If you are really going to build a successful theoretical physics framework. So I think the field needs a little reset. It is particularly important for students to appreciate the wonder, the kind of miracle that is theoretical physics, which when connected to reality, is quite magical. And I think that students who don't do it, pursue it, or aspire to it, are really missing out on a lot.

You know, I must never forget that the real magic of the subject is when it is connected with observations. And these observations are extremely fundamental. I mean the universe, you know, we know things about the universe and the fact that empty space seems to have an energy, the cosmological constant, that's very profound. Again there are ideas to interpret the meaning of that. You know, what is this in empty space? And then we have dark matter, very good observations that show us that most of the matter in galaxies does not interact with light. We have some very interesting candidates for dark matter, some of which are minimal, like neutrinos.

We know that neutrinos exist, and it is a very simple and natural idea that one of the so-called right-handed neutrinos is dark matter. And the exciting thing is that this hypothesis can be tested in the next five years or so. People project that, through observations of galaxy clusters, I can detect even very tiny, light neutrino masses. And, if one of the right-handed neutrinos is dark matter and is stable, then it follows that one of the light neutrinos has no mass. And that should be possible to confirm in the next five years. It's very, very challenging work, for people doing observations and modeling, a lot of computational modeling to understand how the masses of light neutrinos affect the accretion of matter.

But so far the predictions are that, with the expected precision of the measurements, we should be able to say fairly confidently within about five years whether light neutrinos are massless. And if that is confirmed, it will be a very strong indication that we are really on the path to understanding dark matter. MMM. And then there are other things like the fluctuations that arise from the big bang. You know, these take the form of quantum fluctuations in a vacuum, which is a very profound phenomenon. That the quantum fields that we observe, like the electron or the photon, all the other fields in the standard model have fluctuations in a vacuum.

And these are very paradoxical and strange, they have very strange properties. For example, if you add up all the energy in these fluctuations of the 0 point of the vacuum, it is infinite. And that doesn't make any sense because gravity couples to energy, and gravity would see that infinity. So, for decades, we've been sweeping this under the rug and pretending it's not really there, and we've called it renormalizing. And this is very, not a good state of affairs because it means that we don't have a physical image of what is happening in a vacuum. And again, these new developments, some of which I have been involved in, point to the resolution of these questions.

So by modifying the vacuum of the standard model in a very precise way, this energy divergence can be canceled. And, in fact, it protects some of the deep symmetries of the standard model. 1 of which is called local scale symmetry. So, you know, it is an amazing fact that a photon of light is practically the same as a photon of x-rays or radio waves, and they are all enlarged or reduced versions of exactly the same thing. That is a very deep symmetry of Maxwell's equations, which is called scale invariant, and even morethan that, local scale invariant. So you can change the scale differently in different parts of space and time, and the equations remain the same.

Is that why there is such deep symmetry? Well, to describe the big bang, where everything came from one point. If all the material in the universe were insensitive to the total size of the universe, as it is for Maxwell's theory or also for Dirac's theory, then things in the universe don't know about the size of the universe at all. So, although from our point of view everything was reduced to a point, the matter from which the matter is made does not see, the so-called singularity. And this makes the singularity possible to model mathematically and really understand this boundary condition that I mentioned in the Big Bang.

So I think these principles, in other words, trying to address the infinity or divergence of vacuum energy, trying to address the Big Bang singularity, are really pointing us to the right principles, which will explain the universe on a large scale. . And what I'm most excited about recently is that, using these same principles, we've been able to calculate the fluctuations that we now see in the cosmic microwave background. And surprisingly, the numbers come out correct. We get the correct size of the fluctuations. We obtain the correct spectrum, without any free parameters. And so, you know, this is early, but it's a very interesting framework, which may end up explaining the universe and connecting it to fundamental particle physics in a much more precise way than we ever thought. possible.

And is this something that you've been working on your entire career, trying to work on these very simple models with very few free parameters? Or would you say this is something you've been exploring more recently? Basically, I have worked with the same motivation throughout my career. I have always chosen to work on testable theories, even when most people don't. And so, when I was a student, I was very fascinated by my professor, Tom Kibble's, idea that there would be cosmic defects in the universe. This was actually a consequence of grand unified theories. And the exciting thing is that if these defects, if the grand unified theories were correct, and if these defects had formed as they predicted, we could see them.

And so I spent a lot of time trying to calculate what they would look like, what the observations would detect. And in the end we disproved the idea that these defects gave rise to galaxies, which was one of the popular theories of the 1980s. And I spent a lot of time trying to figure out precisely what the predictions were. And then when the experiments came to test it, they simply proved those theories wrong. So I was very lucky to work on theories that could be proven wrong. Then when string theory came out, like most people, I got really excited.

Perhaps this unified framework that will truly explain everything is a theory of everything. And I did my best to try to reconcile string theory with cosmology. So we made a model of colliding branes in extra dimensions. And I would say at that point I was starting to not really believe it. I didn't necessarily believe in this framework, but I thought it was an interesting exercise to create a rival, a competitor to the most popular theory, which was called inflation, and and and hopefully one that was less adjustable and more connected to very fundamental physics, you know, as was string theory, quantum gravity, etc.

But I think little by little we realized that this whole framework was too complex. And, above all, as observations have become increasingly simpler and the type of signals that would have been expected from inflation have progressively disappeared. So one of the predictions of inflation was that there should be very long wavelength gravitational waves, creating a sort of replica of this burst of expansion, at the beginning of the universe. And you could see these long-wavelength gravitational waves by observing the polarization of the background microsky. And the measurements eventually became precise enough to see this effect. Initially, they claimed they had seen it, so all the inflationists were very excited and thought, you know, this is a check, including Stephen Hawking, my friend Stephen Hawking, he publicly bet me that we had a bet. .

I had bet they wouldn't see it, and now they claim to see it. So he wanted me to pay the bet and I told him, you know, all experiments require verification and there were reasons to doubt this experiment. In the end, the experiment turned out to be wrong. And now what has happened is that the latest experiments don't see anything. And within five years or so, the upper limit of these gravitational waves will be so low that I think most people, most relatively unbiased people, will conclude that inflation is probably not the way to go. continue.

That's really exciting. The precision of experiments has reached the point where, you know, a large number of popular theoretical frameworks are now under severe pressure. Meanwhile, all these things influenced me a lot. But I think, especially when I was working at Perimeter and I had the responsibility as a director to decide which fields were worth investing in, that made me look very critically at the entire field of theoretical physics and try to evaluate, you know, where they were. the best perspectives. And, of course, that influenced my research. And so when I stepped down as director and went back to research full time, you know, I was very determined to focus on theories that I really think are promising and that have the potential to, you know, provide very large explanatory power.

And that's what I'm working on. MMM. And I know you've said that a lot of the work you're doing now relies heavily on some ideas introduced by Stephen Hawking, who you've already mentioned. Can you say a little more about that? Yes. I was very lucky, in many ways, to meet Stephen Hawking. As a student, I attended his inaugural lecture, titled, very provocatively, Is the End of Theoretical Physics in Sight? And it was a kind of conference full of jokes. And in the end, he concluded that he was already in sight and that I was worried that I had lost my way.

They had solved everything. Supergravity was the answer, and that was it. But it turned out to be too optimistic. And then I returned to Cambridge as a professor, became friends with Stephen and we wrote several articles together. But what's special about Stephen is that he had this: he was extremely adventurous. You know, at the time he started thinking about quantum gravity and black holes and how they radiate and the thermodynamics of black holes, you know, that was way ahead of his time. But his ideas were so profound that they have influenced the entire field for decades.

And from what I know, I think we're still struggling to understand what they mean, and so is he. We still don't know exactly what the entropy of a black hole means. We think it has to do with how many different ways there are to create a black hole, but we still can't identify what exactly it means and how it is compatible with the rest of physics. But in our very recent work, and this is with Latham Boyle at Perimeter, we have developed Stephen Hawking's concept of entropy, gravitational entropy, to apply it to the universe, the entire universe.

And that has been really surprising. And in the course of that study, I came to the conclusion that Stephen himself underestimated the power of his own ideas. Well? So he developed the idea of ​​entropy, of gravitational entropy, entropy of black holes, entropy of the universe. He never managed to calculate it for the universe, as we do now. And then he linked his ideas to inflation. You know, inflation, to put it bluntly, was kind of a rag bag of models, thousands of different inflation models, all of them modified and tweaked and with a lot of assumptions to fit what we see.

In the universe. And my current understanding is that you simply don't need it. It is not necessary to link Stevens' ideas about gravitational entropy with inflation. Just take them as they are, apply them to the real universe without extra particles or fields, inflation or anything, and they already explain why the universe is big, smooth and flat, in and of themselves. And that's been very exciting: I think we discovered that Stephen's ideas are more powerful than he suspected. And there are still questions about what exactly it all means, but it seems they can explain the structure of the universe without any additional input.

And then the other thing we're looking at is that Stephen's ideas were very paradoxical in many ways. He then said that, but a black hole, which only has mass, angular momentum and electric charge, only has certain numbers, a black and has no distinguishing features. A black hole is essentially a featureless object, like an elementary particle, but it can be huge. This black hole can be created in many ways. Now, the strange thing about that statement is that surely the number of ways a black hole can be created depends on how many different elementary particles there are.

You know, if you have a particles. If you only got one type of particle, you could create a certain black hole. But if I have 2 types of particles, surely there are more ways to make a black hole. So simply assigning an entropy to a black hole immediately creates a puzzle. Why are there so many different particles in the standard model? And does the entropy of a black hole depend on how many particles there are? So the answer is, in his calculation, it is just a result. You can't adjust it. If not you can change the number of particles.

You cannot change entropy by changing the number of particles. It's whatever. Actually, I think that implies that the number of particles in the Standard Model is fixed by gravity. Well? And we know that there are 3 generations of particles, 16 particles per generation. That number should be dictated by the fact that the standard model couples with gravity. If so, then everything is absolutely autonomous and you cannot separate these puzzles from each other. So for particle physicists trying to understand how many particles there are in nature, that question is meaningless unless they include gravity. And for gravitational theorists trying to understand the entropy of a black hole, that question doesn't make sense unless they actually use the actual number of particles in the world.

Well? So I think that again, the fact that Stephen's ideas of entropy seem to succeed in describing the universe indicates that physics is truly unified and not adjustable. Know? And if all this works, I'd say we'll be pretty sure this is all physics. Because if you add another particle, you'll ruin all these cancellations and agreements. So that's very exciting, that nature itself may be telling us how things come together, and that all these kinds of coherence arguments and arguments about the universe and the big bang and coherence with observations can, in fact, come together. very beautifully into a coherent mathematical image.

I want to go back to something you said a few minutes ago that I really liked. You said you feel lucky when you work on a theory that can be proven wrong. And I like that because I think it's very different from what many other researchers would feel in that situation. Many others would feel very scared when they think that they can be refuted at any moment with any new data that arrives. Why do you think the idea of ​​being proven wrong is so scary for some people? You know, it's funny, but the reality is scary.

I don't really know how to say it, but sometimes, for example, when you just go out into nature, you know, whether it's in a snowy field in the middle of the winter in Canada or you're looking at how you're walking. in some, you know, high mountain ranges or something, or you just look out into empty space from Earth, you know. And you think, wow, this is this, this is real. You know, that can be scary. And that's why reality is terrifying. And I think it's as simple as saying, you know, I want physics to be real.

And the reality is scary. So we have to face that. The way to deal with it is to enjoy this amazing fact that we can interact with nature and make sense of it. You know, we don't understand why. We have no idea why we can do that, except that perhaps, you know, we have involved evolved capabilities, which somehow allow us to do this, but then go far beyond what we ever need to survive. You know, so we have a terrifying capacity. Obviously that's true. We can do all kinds of scary things, you know? But I think it starts from essentially being a responsible citizen and living up to the opportunity of life, which we all, you know, all possess like a miracle.

We all have this wonderful thing called life, and I think just living up to that is facing these scary realities and trying to deal with them well. So, yes, I see this particularly among students, a kind of nervousness, particularly about the race. You know, people say that if I work in atheoretical framework that can be risky, perhaps mathematically proven to be incorrect. You know, that's probably the most immediate danger, because there's a lot more mathematics than physics. So there are many more physics models than actual, you know, correct physics models. So I think for students, sometimes it's more comfortable to work on a mathematical model or framework, which no one is actually going to prove wrong anytime soon.

But those frameworks are very unlikely, what I would say, to have much to do with reality. And then you can spend, you know, you'll be in a kind of relatively comfortable place, but you'll never experience the magic that the countryside is capable of. This type of search for security is now very common throughout society. You know, people don't necessarily want to deal with difficult problems. How do we take care of the planet? How do we make sure we don't destroy the environment? How do we reduce inequality? How do we create opportunities for more people to live dignified and fulfilling lives?

On the one hand, you can just stick your head in the sand and say, look. It's not my responsibility. But, you know, I think that's not again, not living up to what the world offers you and the privilege that you have to be part of the world, and you have to play a role in, you have to live up to these. challenges. So I think this all comes together. I try to encourage young people, yes. You know, when you work in physics, a very healthy attitude is often to say, look, I'm going to try something that sounds attractive and exciting.

It can be risky. You know, and I'll have a backup plan. If this doesn't work, if it is proven wrong, well, there are many other wonderful things to do in life. It is not necessary to follow the conventional path. And if you end up committing yourself to such a degree, you know, that it allows you to follow some conventional path, you know, I feel like you're really missing out on the possibilities that life offers. Have you always had a backup plan in mind throughout your career? I always had a backup plan. I think, in my own case, my parents went to prison for their political beliefs, and then they came out of prison, and a few decades later they were elected to parliament and they both, you know, had a complete change in which their beliefs led them to positions of responsibility in the government.

And that was very inspiring to me. So I learned from them that, you know, you really shouldn't compromise your beliefs, and yeah, I had a backup plan if I think even since I was a graduate student, I was a little worried about theoretical aspects. physicist who doubted that these models were really real. It was a kind of game that people played, an interesting game, but somehow it didn't seem true. Grand Unification theories or string theories never really seemed like a genuine view of reality to me. That's just a feeling, not necessarily one you should trust. But as a result of that, I basically said to myself, look, if I don't make it in theoretical physics, if I can't make a good contribution, you know, my dream was to go and be a Wild, a wildlife warden in a park. hunting in East Africa.

That's because I thought there is nothing more fun than caring for lions, antelopes and rhinos in the wild. So, yeah, I always had that as kind of a backup plan at least mentally. MMM. If no one wants me in physics, you know, I'll go and do something much more exciting. And, but I'm not really, you know, another thing that's so strange about me is that when I was a postdoc in California, I used to have this sort of recurring nightmare, which and the nightmare was that I actually got a teaching position at my original apartment in London.

That I was walking down the hallway and I saw these names on the doors. And I came to this door and my name was written on it, and I woke up, you know, in a cold sweat. Oh no. I am a faculty member. So the academic career, you know, is not the pinnacle of the human experience. Yes. I love my colleagues. I would like to be an academic. I think university is a wonderful place. It's for many reasons, but you should use them to enjoy it and have fun and, you know, not see it as a goal in itself.

MMM. As you said, many of the things you are raising are topics that I think students have a lot of difficulty with. And you spend a lot of your time mentoring and advising students, including meeting with a large group of PSIs and graduate students here yesterday. And some of them sent some questions. Alright. For you I would like to share. So let's start with 1 from Saba. I'm Saba and I'm a PSI student. And before coming to PSI, I was working mainly on cosmology and then after coming to PSI, I was introduced to completely new ways of doing quantum gravity and quantum fundamentals and I decided to somehow work in these directions while I'm at PI, fundamental.

Aspects of quantum gravity. And now I'm at the beginning of my PhD and I'm really trying to figure out whether I should continue working on cosmology like I did before or continue doing this kind of quantum gravity and fundamental aspects of quantum gravity from a quantum information point of view. At this point, I feel like I found my question and I think the question for me right now is to somehow figure out quantum gravity, the problem of quantum gravity. And I don't know what the most promising way is to somehow address the question of mission. In reviewing cosmology, it seems that at a very early point everything becomes classical, and we don't really know if, in studying cosmology, how can I directly address the interest in quantum gravity?

And yes, I just want to know your opinion on what you think about cosmology in the context of quantum gravity, what are the avenues that I can pursue within cosmology and what are the most promising ways to somehow do some kind of of mineralogical quantum gravity? Doctor. Well. Thanks for the wonderful question. I think you are asking the right question. You're recognizing that we're getting wonderful insights from observation in cosmology, and you want to apply them to learn something about quantum gravity, which is the big missing component of fundamental physics, the standard part. The model, if you will, that we understand the least is quantum gravity.

Then you are asking the right question. The problem is that we still don't know the answer. And I would say this: the safe bet over the next 10 to 20 years is that observations will continue to pay off. We will obtain increasingly precise measurements of the fluctuations that arise from the Big Bang. And, with that precision, we have much greater power to test the theory. So I think it's a very sensible path that anyone can take: getting into data analysis, interacting with observations, modeling observations, etc. Know? I think and hope that many people go in that direction. Now I sense from your question that you are more attracted to more fundamental questions.

That's great, but keep in mind that people haven't solved this problem for over 50 years. For probably 75 years, people have tried to solve these problems and failed repeatedly. So the chances of you actually achieving success are very, very small at best. So I think what you can do is pick problems that are instructive, where you have to deal with gravity and sort of refine them by classical composers and it's great practice, as well as very rewarding just to go through them and play them. . put your own spin on them and find better ways to explain them and so on.

And I think that kind of work is never wasted. So as long as you don't expect to really answer, you know, these very, very difficult questions, then I think you'll find the work very rewarding. I'm very optimistic about the chances of there being a solution to this puzzle, you know, in the next one. In the next 10 or 20 years there will be, at least, much better resolutions to these puzzles. But the chances are small, and who exactly will find it is a random question. It could be anyone and it will probably be someone unexpected. So, it could be, you know, a PhD student somewhere, at a very small institution, who comes up with the key idea.

That's one of the interesting things about fundamental research. It could be anyone. But if you are in a position where you are studying these questions carefully and rigorously, and you are very critical, critically aware of the different approaches and frameworks, then you will be in a good position to respond to any such breakdown. through which it happens. And if there is a breakthrough, whether by you or anyone else, obviously that will flourish in many, many other areas. I mean, if we understand quantum gravity and how it relates to the universe, there will be a wide variety of results, questions, predictions and interpretations.

And that's something that, you know, you could easily spend a lifetime working on. So, yes, I encourage you to go in that direction. Study it very carefully, very seriously. Don't place all your bets on one horse, because the horse you bet on is unlikely to be the right approach. MMM. And like you said, these breakthroughs can happen at any time and from anyone. Yes. And I know that one thing that he was well known for during his time as director of Perimeter was fostering an environment in this academic institution where those advances could take place. Yes.

From anyone, not necessarily just senior faculty members. Yes. What do you think are the most essential ingredients an academic institution needs to foster those advances? I think it's a recognition that it's most likely that community of young people. So I see the community of young people, that community of young people. That's why I see the youth community as the most important community in the institute. Those young people who see this don't get stubborn, but I do see it and I think that, furthermore, they must be very diverse. I think diversity is very often a source of strength and enthusiasm and, you know, difference doesn't just encourage new ways of thinking.

It's a commonplace, but very often in physics, the best new ideas arise when two different schools of thought collide and suddenly realize that the other has some idea they can benefit from. You know, the Higgs mechanism, the Higgs mechanism and the Higgs boson, is a classic example where Peter Higgs was aware of ideas that were happening in superconductivity, which were generally ignored by particle physicists, mainly because particle physicists were quite arrogant and couldn't I think someone who studies materials, you know, could give them any real insight. But Higgs took that idea and interpreted it in terms of particle physics and incorporated it into it.

And that was an extremely profound and important breakthrough. Although, you know, initially there was resistance. For several years people didn't believe what he was doing at all. So, yes, I think the diversity of different types of people from different countries, from different cultures, especially gender diversity, is really important among that young community of physicists. And it should be an environment. I think another very important thing is that people who tend to be more original tend to be strange in certain ways. They are unusual people and are not necessarily very good at dealing with the everyday rigors of life.

That is why it is very important that any community that fosters talent especially supports people who are unusual in any way. So I think that's essential. And again, supporting unusual, different people, that's probably the best way to ensure that the field is not a monoculture or going in the same direction, you know, which, as I've already expressed, the most popular directions. They have not worked in the last 40 years. And that's why we need to make sure we follow a real diversity of directions. Now I want to ask you more about these unusual people and how to find them.

But first, maybe let's go to one more question submitted by a student. This was submitted by Vatsalia, who is a PSI student. MMM. And he wrote asking: do you believe that, as theoretical physicists, it is our moral responsibility to conduct research that explains the real world? Or is it okay to just enjoy playing with mathematical structures? Yes. That's a tough question. I think, above all, I think theoretical physics is very, very difficult. And it's very difficult, it's a kind of torture. We make these very difficult and complicated calculations and they take days, weeks or months. And sometimes you end up with a paradox and confusion.

So it's not an easy life choice, but somehow we enjoy it. And so I think in order to understand why we enjoy it, it's pretty good to have at least some idea of ​​why, you know, some idea of ​​our motivation. I have met many theoretical physicists who love nothing more than to make diagrams. And they say, you know, they like writing articles because it's an opportunity to make a diagram that they can put on paper. But what they really like is making the diagram. So, you know, people do it for all kinds of reasons. I don't think there is much moral responsibility.

I see it more as a responsibility to yourself, you know? Do not fool yourself. I guess that would be my message.Paramount: If you like playing with mathematical frameworks and you are good at it, then do it because the work you do will be good and other people will draw, you know, you can draw some interesting physical conclusions even if your work is only mathematical. So I would never put anyone down for doing something they enjoy, especially when they do it well. Even if it's not directly related to physics, it's more like playing a game, a mathematical game.

I think it's okay to do it. But as I say, in a certain sense, I feel sorry for them because I believe that the true magic of physics is that these mathematical considerations end up connecting with reality. That is the deep mystery of the field. Someone told me this a few days ago. You know, mathematicians create their frameworks and do their calculations, but physicists somehow have a direct line to God. Well. Now I don't believe in God, I'm not religious, at least not in an organized sense, but I think there is a kind of element of truth.

In that, somehow physicists have discovered a fundamental characteristic of existence, which is this strange ability of our mind to really make sense of what surrounds us. It's a very profound puzzle, and I think that, if you will, the best way that we can appreciate that puzzle and deepen it and almost pay homage to it is to practice it, to make sure that, you know, what we do. does or tries to relate the mathematics we do with the real world. MMM. In many ways, you're talking about the idea that physics needs a lot of different people, including people who like to make diagrams or do.

Maybe people who could be considered unusual. Yes absolutely. Another way to say it is people who don't necessarily succeed in the traditional academic hierarchy that we've built. I guess as a director it must have been a big challenge to find the right people. Because you probably couldn't just look at the requests they submitted, which maybe try to show you other metrics than what you would like. So how did you go about finding the right people? Yes. So I think this was something that I'm particularly proud of as a director is that, you know, when I came to the perimeter, the faculty was very small, and they really weren't really structured at all, and it wasn't clear how it should be structured.

The government and its supporters had made huge investments in the perimeter, and it was very important that they paid off in the sense that the institute really did good work and was recognized as a place, you know, where excellent theoretical physics was done. So it was quite a challenge and I think I took the point of view that we needed very strange people here. There was nothing stopping us from recruiting people from all over the world, and we needed to look as widely as possible and keep our eyes and ears open for unusual people who had done something unexpected.

So it wasn't about reading requests or, you know, it was about being really proactive. I also learned that the experienced physicists who advised us were not always, or even often, the best source of ideas about who to hire. Because normally they had their own field and their own visibility, you know, the region that was visible to them was very limited. And secondly, if they saw someone really good, they thought they were really good, they tried to hire them themselves and they wouldn't recommend them to us. That was interesting. So I think the short answer was just to keep your eyes and ears open and look for very unusual people who maybe had unconventional career paths.

And then imagine what would happen if, when you hired them, you gave them a lot more freedom than is typically given to young teachers. So one of the rules we introduced is that, as a junior faculty member, you should not spend more than 20 percent of your time on administrative tasks. That includes teaching, mentoring and grant writing. And that's extremely unusual because at most universities, when a young faculty member comes in, they're immediately burdened with teaching and scholarship applications, and they and they, you know, very often judge by their success in getting of scholarships. And I think that is very contrary to original research that pursues originality.

That's why I would always tell young teachers to look for a problem that really fascinates them. If you don't post anything for, you know, 2, 3 years, no, you know, it's okay. You'll explain to us that, you know, I looked up this very difficult problem and we'll all respect you for that. You know, we're investing in you because we think you have the ability to do something unusual, so look for something unusual. And, of course, we will advise you and try to make sure you do enough to sustain your career. But it should be a much greater type of support framework than is usually offered to young professors in universities.

So I see the job of an institution as more to challenge people to be really adventurous and ambitious than to judge them all the time. And, you know, particularly on criteria like publications, citations, talks at conferences given and all that. You know, these are really the kind of physics symptoms. They are not the essence of what we are trying to do. So in many ways I'm trying to give an example where Perimeter used very different metrics to judge people. I think metrics like how creative they are, how stimulating they are to have on hand. Do you have original ideas?

Do they question things? Are they asking good questions? You know, those characteristics of people are actually much more important than more conventional measures of success. It seems like it really involves looking at the institute as a whole rather than simply assessing whether each individual person says Yes. One of the biggest ills of the academic model, particularly in North America, is the idea that every researcher has a grant and uses it to support their postdocs and students. So what you are doing is deliberately putting individual researchers in competition with each other and deliberately creating hierarchies. And I see this everywhere.

It's also become increasingly common in Europe and elsewhere, I'm sure. And I think this model of the single researcher at the top of a pyramid is actually very destructive of creativity and originality and questioning, you know, because younger people don't want to question the older person holding the cash. And I think that's the wrong way to do things. I prefer a much flatter structure, and in fact, conceptually, I think a much better image is an inverted pyramid, where the older people, if you will, are at the bottom, and their job is precisely to support the younger ones. .

And, you know, the flowers of the tree, they may be the root, but the flowers of the tree are the young ones and that's really where the emphasis should be. It seems like a lot of the things that you would ideally look for, like being creative, asking good questions, are things that are maybe harder to measure or predict in advance. So I guess another essential ingredient is being okay with taking risks. And so I wonder if that's true. Is it important to accept the fact that some of those decisions you make might not work out? A lot of it is like that.

As I say, when I talk to students today, I'm very often surprised that they say, you know, well, I'd like to do something more exciting and interesting, but it would be risky. And yes, I find it very disappointing that people understand that. You know, they need to, ultimately, make a living. And young people today are kind of in, as a generality, young people today are much less safe than in my time as a student, where I think we felt that kind of if for some reason things don't work, you know, there are many alternative options. And we weren't nervous about livelihood either.

There are very good economic reasons for this. You know, yes, the ability to find a job is certainly more difficult today than it was several decades ago. And even my generation was much more difficult than previous generations. Previously, universities were really or at least advanced research was the privilege of a very small number of people. And as a result, they had much greater job security and didn't really worry about getting academic positions. So my teachers never worried about this at all. I didn't have to get grants. Know? In the sixties the money was barely coming. So the country climate has changed.

Part of that has been allowing more people onto the field, which is good. Expanding access means a larger talent pool and, you know, things should move faster. But what this has brought about is a lot more standardization and, you know, prescription, telling young people that they have to do a, b, c to get a job. And I think that's very damaging. And what I see across higher education is that, in fact, the quality of degrees that are being awarded now, I don't think is what it should be. Even if you look at university majors, the curriculum has become very standardized and quite boring, and initiative is not rewarded.

So this is not something isolated. Know? It's everywhere. There is a kind of massification and then standardization and loss of creativity. So theoretical physics is very fortunate because it is a very cheap field. We just need a blackboard and chalk and occasionally a computer. It is really a very cheap course. So if anyone is going to recreate the organization of science more optimally, it has to be theoretical physics. Know? We have one of the most effective of all sciences, if not the most effective in terms of predictions. Theoretical physics, you know, has no rival. We have the cheapest, we have the easiest, the most universal, the easiest to access.

You don't need a lab, you know? You can come to a summer school and learn some ideas and, you know, they might let you write a really interesting paper. So theoretical physics should set the example for the rest of science. That's why it's very, very important that we strategize our field carefully and wisely. And I don't think that's happening across the board. MMM. You've also said in many ways that diversity is a very important ingredient and this reminds me of something I noted that you said yesterday when you met with students that I really like. You said that theoretical physics is special because it is cross-cultural and everyone has the same questions.

What do you think are those questions that everyone asks? Well, it caught my attention, for example, I'll tell you a little story. So I was in Senegal and I was teaching electromagnetism relativity, and there was a student who had studied mathematics at university, so not physics, and he was quite a lively student, you know. So I asked the whole class, you know, when I started the course, what would you like to be? And his answer was, I mean, a billionaire. Well? Which, actually, you know, you could say that's a little rude, but, compared to the other students who largely said "I want to be a teacher," you know, I found it more exciting to have someone who at least don't just say "I." I want to repeat, you know, exactly what the people who taught me and so on.

Anyway, he wanted to be a billionaire, so we started chatting and then he was very baffled by physics, you know. What is all this? You keep referring to reality and light and all that, and you're writing some equations and so on. So we had, at some point, an interaction over problem sheets, and at some point, it involved instabilities. And at some point, you know, I was trying to explain what this instability was. And at some point he said to me, oh, you mean physics is just logic? And I said, yeah, that's exactly what it is. It is logic applied to nature.

He said, now I understand. Good? And then he became very interested. And then in the next few days, and this is the wonderful thing about meeting someone from a completely different culture and academic background, as well as, you know, culturally and linguistically, everything. You know, he started saying, God, you know, you can apply logic to the real world. And then he, you know, naturally, what do you do? You point to the stars. And in Senegal, where we were, it was in a nature reserve. It was actually a wonderful place. And there's a huge open sky with the stars, and you immediately say, what are those?

Know? What is the logical basis of the stars? And then that was an excuse to have a conversation about how stars form and how they work, nuclear physics and so on. And yes, people ask the same questions very naturally. It is because we all live in the same universe and we are all baffled and amazed by the same natural phenomena. And that is the cultural unifier. Know? When do we realize that the phenomena that surround us all the time and that are miraculous in various ways, you know, can we share this? We all share it and can discuss it among ourselves and share our understanding of how it works.

And that somehow gives you control over the world you share. And I think it also makes you feel more responsible and more empowered. And if you understand the world, you will certainly have much more power than if you were simply at its mercy. ByI think that this understanding between different cultures, different peoples, this fundamental understanding of the world is very strengthening, it is very unifying. It makes us all feel, you know, like we're part of the same company. And that's really the most exciting thing of all. Definitely. Well, Neil, thank you so much for this amazing conversation.

It's been really fun talking to you. Thank you. Thank you. Thank you so much.