Frank Wilczek: Physics of Quarks, Dark Matter, Complexity, Life & Aliens | Lex Fridman Podcast #187

The following is a conversation with Frank Wolczek, a theoretical physicist at MIT who won the Nobel Prize for the co discovery of asymptotic freedom in the theory of strong interaction. Quick mention of our sponsors, the Information, NetSuite, ExpressVPN, Blinkist and Asleep. Check them out in the description to support this podcast. As a side note, let me say a word about asymptotic freedom. Protons and neutrons make up the nucleus of an atom. Strong interaction is responsible for the strong nuclear force that binds them. But strong interaction also holds together the quarks that make up the protons and neutrons. Frank Wilczek, David Gross and David Pollitzer came up with a theory postulating that when quarks come really close to one another, the attraction abates and they behave like free particles. This is called asymptotic freedom. This happens at very, very high energies, which is also where all the fun is. This is the Lex Friedman podcast and here is my conversation with Frank Wilczek.

What is the most beautiful idea in physics?

The most beautiful idea in physics is that we can get a compact description of the world that's very precise and very full at the level of the operating system of the world. That's an extraordinary gift. And we get worried when we find discrepancies between our description of the world and what's actually observed at the level even of a part in a billion.

You actually have this quote from Einstein that the most incomprehensible thing about the universe is that it is comprehensible. Something like that, yes.

So that's the most beautiful surprise that I think that really was to me the most profound result of the scientific revolution of the 17th century, with the shining example of Newtonian physics that you could aspire to completeness, precision and a concise description of the world, of the operating system. And it's gotten better and better over the years and that's the continuing miracle. Now there are a lot of beautiful sub miracles too. The form of the equations is governed by high degrees of symmetry and they have very surprising kind of mind expanding structure, especially in quantum mechanics. But if I had to say, the single most beautiful revelation is that in fact the world is comprehensible.

Would you say that's a fact or a hope?

It's a fact. You can point to things like the rise of gross national products per capita around the world as a result of the scientific revolution. You can see it all around you in recent developments, with exponential production of wealth, control of nature at a very profound level, where we do things like sense tiny, tiny, tiny, tiny vibrations to tell that there are black holes colliding far away. Or we test laws, as I alluded to as a part in a billion. And do you know things in what appear on the surface to be entirely different conceptual universes? I mean, on the one hand pencil and paper or nowadays computers that calculate abstractions, and on the other hand, magnets and accelerators and detectors that look at the behavior of fundamental particles. And these different universes have to agree or else we get very upset. And that's an amazing thing if you think about it. So it's telling us that we do understand a lot about nature at a very profound level. And there are still things we don't understand, of course, but as we get better and better answers and better and better ability to address difficult questions, we can ask more and more ambitious questions.

Well, I guess the hope part of that is because we are surrounded by mystery. So one way to say it, if you look at the growth GDP over time, that we figure out quite a lot and we're able to improve the quality of life because of that, and we've figured out some fundamental things about this universe, but we still don't know how much mystery there is. And it's also possible that there's some things that are in fact incomprehensible to both our minds and the tools of science. The like we. The sad thing is we may not know it because in fact they are incomprehensible. And that's the open question is how much of the universe is comprehensible. If we figured out everything, what's inside the black hole and everything that happened at the moment of the Big Bang, does that still give us the key to understanding the human mind and the emergence of all the beautiful complexity we see around us? That's not like when I see these objects, like, I don't know if you've seen them, like cellular automata, all these kinds of objects, where the. From simple rules emerges complexity. Yes. It makes you wonder maybe it's not reducible to simple beautiful equations. The whole thing, only parts of it. That's the tension I was getting at with the hope.

Well, when we say the universe is comprehensible, we have to kind of draw careful distinctions about or definitions about what we mean by that.

Both the universe and the comprehensive.

Exactly right. So in certain areas of understanding reality, we've made extraordinary progress, I would say, in understanding fundamental physical processes and getting very precise, precise equations that really work and allow us to do profound sculpting of matter to make computers and iPhones and everything else. And they really work and they're extraordinary productions. And that's all based on the laws of quantum mechanics. And they really work and they give us tremendous control of nature. On the other hand, as we get better answers, we can also ask more ambitious questions. And there are certainly things that have been observed, even in what would be usually called the realm of physics, that aren't understood. For instance, there seems to be another source of mass in the universe, the so called dark matter, that we don't know what it is. And it's a very interesting question what it is then. But also, as you were alluding to, it's one thing to know the basic equations, it's another thing to be able to solve them in important cases. So we run up against the limits of that in things like chemistry, where we'd like to be able to design molecules and predict their behavior from the equations. We think the equations could do that in principle, but in practice it's very challenging to solve them in all but very simple cases. And then there's the other thing, which is that a lot of what we're interested in is historically conditioned. It's not a matter of the fundamental equations, but about what has evolved or come out of the early universe and formed into people and frogs and societies and things. And the laws of physics, the basic laws of physics only take you so far in that it kind of provides a foundation, but doesn't really. You need entirely different concepts to deal with those kind of systems. And all we. One thing I can say about that is that the laws themselves point out their limitations, that they, they kind of their laws for dynamical evolution. So they tell you what happens if you have a certain starting point, but they don't tell you what the starting point should be, at least. And the other thing that emerges from the equations themselves is the phenomena of chaos and sensitivity to initial conditions, which tells us that you have that there are intrinsic limitations on how well we can spell out the consequences of the laws if we try to apply them.

The old apple pie, if you want to, what is it? Make an apple pie from scratch, you have to build the universe or something like that.

Well, you're much better off starting with apples than starting with quarks, let's put it that way.

In your book, a beautiful question you ask, does the world embody beautiful ideas? So the book is centered around this very interesting question. It's like Shakespeare. You can dig in and read into all the different interpretations of this question. But at the high level, what to you is the connection between beauty of the world and physics of the world?

In a sense, we now have a lot of insight into what the laws are, the form they take, that allow us to understand matter in great depth and control it, as we've discussed. And it's an extraordinary thing how mathematically ideal those equations turn out to be. In the early days of Greek philosophy, Plato had this model of atoms built out of the five perfectly symmetrical Platonic solids. Or there was somehow the idea that mathematical symmetry should govern the world. And we've out Platoed Plato by far in modern physics because we have symmetries that are much more extensive, much more powerful, that turn out to be the ingredients out of which we construct our theory of the world. And it works. So that's certainly beautiful. So the idea of symmetry, which is a driving inspiration in much of human art, especially decorative art, like the Alhambra, or in wallpaper designs or things you see around you everywhere, also turns out to be the dominant theme in modern fundamental physics. Symmetry and its manifestations, the laws, turn out to be very. To have these tremendous amounts of symmetry. You can change the symbols and move them around in different ways and they still have the same consequen is. So that's beautiful. And. These things, these different, these concepts that humans find appealing also turn out to be the concepts that govern how the world actually works. I don't think that's an accident. I think humans were evolved to be able to interact with the world in ways that are advantageous and to learn from it. And so we are naturally evolved or designed to enjoy beauty and to symmetry. And the world has it, and that's why we resonate with it.

Well, it's interesting that the ideas of symmetry emerge at many levels of the hierarchy of the universe. So you're talking about particles, but it also is at the level of chemistry and biology. And the fact that our cognitive, sort of our perception system and whatever our cognition is, also finds it appealing. Or somehow our sense of what is beautiful is grounded in this idea of symmetry or the breaking of symmetry. Symmetry is at the core of our concept perception of beauty. Whether it's the breaking or the non breaking of the symmetry. It makes you wonder why. Why, like, so I come from Russia and the question of Dostoevsky, he has said that beauty will save the world. Maybe as a physicist, you can tell me, what do you think he meant by that?

I don't know if it saves the world, but it does turn out to Be a tremendous source of insight into the world when we investigate kind of the most fundamental interactions, things that are hard to access because they occur at very short distances between very special kinds of particles whose properties are only revealed at high energies. At. We don't have much to go on from everyday life. But so we have. When we guess what the. And the experiments are difficult to do. So you can't really follow a very wholly empirical procedure to sort of, in the Baconian style, figure out the laws kind of step by step, just by accumulating a lot of data. What we actually do is guess. And the guesses are kind of aesthetic, really. What would be a nice description that's consistent with what we know? And then you try it out and see if it works. And by gosh, it does in many profound cases. So there's that, but there's another source of symmetry, which I didn't talk so much about in a beautiful question, but does relate to your comments and I think very much relates to the source of symmetry that we find in biology and in our heads, in our brain, which is that. Well, it is discussed a bit in a beautiful question and also in fundamentals, is that when you have. Symmetry is also a very important means of construction. So when you have, for instance, simple viruses that need to construct their coat, their protein coat, the coats often take the form of Platonic solids. And the reason is that the viruses are really dumb and they only know how to do one thing. So they make a pentagon, then they make another pentagon, and they make another pentagon all glued together in the same way. And that makes a very symmetrical object, sort of. So the rules of development, when you have simple rules and they work again and again, you get symmetrical patterns. That's kind of. In fact, it's a recipe also for generating fractals, you know, like a kind of broccoli that has all this internal structure. And I wish I had a picture to show, but maybe people remember it from the. From the. From the supermarket. And you say, how does a vegetable get so intelligent to make such a beautiful object with all this fractal structure? And the secret is stupidity. You just do the same thing over and over again. And in our brains also, we start from single cells and they reproduce. And each one does basically roughly the same thing. The program evolves in time of different modules get turned on and off, different regions of the genetic code get turned on and off. But basically a lot of the same things are going on, and they're simple things. And so you produce the same patterns over and over again. And that's a recipe for producing symmetry because you're getting the same thing in many, many places. And if you look at, for instance, the beautiful drawings of Roman Ika hall, the great neuroanatomist who drew the structure of different organs like the hippocampus, you see, it's very regular and very intricate. And it's symmetry in that sense. It's because it's many repeated units that you can take from one place to the other and see that they look more or less the same.

But what you're describing, this kind of beauty that we're talking about now, is a very small sample in terms of space, time in a very big world, in a very short, brief moment in this long history. In your book 10 Keys to Reality, I'd really recommend people read it. You say that space and time are pretty big or very big. How big are we talking about? Can you tell a brief history of space and time?

It's easy to tell a brief history. The details get very involved, of course. But one thing I'd like to say is that if you take a broad enough view, the history of the universe is simpler than the history of Sweden, say, because your standards are lower for. But just to make it quantitative, I'll just give a few highlights and it's a little bit easier to talk about time. So let's start with that. The Big Bang occurred. We think the universe was much hotter and denser and more uniform about 13.8 billion years ago. That's what we call the Big Bang. And it's been expanding and cooling. The matter in it has been expanding and cooling ever since. So in a real sense, the universe is 13.8 billion years old. That's a big number. Kind of hard to think about. A nice way to think about it, though, is to map it onto one year. So let's say the universe just linearly map the time intervals from 13.8 billion years onto one year. So the big bang then is that on January 1st at. At 12am and you wait for quite a long time before the dinosaurs emerge. The dinosaurs emerge on Christmas, it turns.

Out 12 months, almost 12 months later.

Getting close to the end. And the extinction event that let mammals, and ultimately humans, inherit the earth from the dinosaurs occurred on December 30th. And all of human history is a small part of the last day. And so, yes, we're occupying only in a human lifetime is a very, very infinitesimal part of this interval of these gigantic cosmic reaches of time. And in space, we can tell a very similar story. In fact, it's convenient to think that the size of the universe is the distance that light can travel in 13.8 billion years. So it's 13.8 billion light years. That's how far you can see out. That's how far things can signals can reach us from. And that is a big distance because compared to that, the Earth is a fraction of a light second. So again, it's really, really big. And so if we want to think about the universe as a whole in space and time, we really need a different kind of imagination. It's not something you can grasp in terms of psychological time in a useful way. You have to think, you have to use exponential notation and abstract concepts to really get any hold on these vast times and spaces. On the other hand, let me hasten to add that that doesn't make us small or make the time that we have to us small. Because again, looking at those pictures of what our minds are in some sense of components of our minds, these beautiful drawings of the cellular patterns inside the brain, you see that there are many, many, many processing units. And if you analyze how fast they operate. I tried to estimate how many thoughts a person can have in a lifetime. That's kind of a fuzzy question, but I'm very proud that I was able to define it pretty precisely. And it turns out we have time for billions of meaningful thoughts in a lifetime. So it's a lot. We shouldn't think of ourselves as terribly small either in space or in time. Because although we're small in those dimensions compared to the universe, we're large compared to meaningful units of processing information and being able to conceptualize and understand things.

Yeah, but 99% of those thoughts are probably food, sex or Internet related.

But yeah, well, they're not. That's right.

Only like point one is Nobel prize winning ideas.

But that's true. But you know, there's more to life than winning Nobel prizes.

How did you do that? Calculate? Can you maybe break that apart a little bit? Just kind of for fun, Sort of an intuition of how we calculate the number of thoughts.

The number of thoughts. Right. It's necessarily imprecise because a lot of things are going on in different ways and what is a thought? But there are several things that point to more or less the same rate of being able to have meaningful thoughts. For instance, the one that I think is maybe the most penetrating is how fast we can process visual images. How do we do that? If you've ever watched old movies, you can see that. Well Any movie, in fact, a motion picture is really not a motion picture. It's a series of snapshots that are playing one after the other. And, and it's because our brains also work that way. We take snapshots of the world, integrate over a certain time, and then go on to the next one. And then by post processing, create the illusion of continuity and flow, we can deal with that. And if the flicker rate is too slow, then you start to see that it's a series of snapshots. And you can ask, what is the crossover? When does it change from being something that, that is matched to our processing speed versus too fast? And it turns out about 40 per second. And then if you take 40 per second as how fast we can process visual images, you get to several billions of thoughts. Similarly, if you ask what are some of the fastest things that people can do? Well, they can play video games, they can play the piano very fast if they're skilled at it. And again, you get to similar units, or how fast can people talk, you get to within a couple of orders of magnitude, you get more or less to the same idea. So that's how you can say that there's billions of meaningful, there's room for billions of meaningful thoughts. I won't argue for exactly 2 billion versus 1.8 billion. It's not that kind of question. But I think any estimate that's reasonable will come out within say 100 billion and 100 million. So it's a lot.

It would be interesting to map out for an individual human being the landscape of thoughts that they've sort of traveled. If you think of thoughts as a set of trajectories, what that landscape looks like. I mean, I've been recently really thinking about this Richard Dawkins idea of memes and just all this ideas and the evolution of ideas inside of one particular human mind and how they're then changed and evolved by interaction with other human beings. It's interesting to think about. So if you think the number is billions, you think, you think there's also social interaction. So these aren't.

Yes.

Like there's interaction in the same way you have interaction with particles. There's interaction between human thoughts that are. Perhaps that's. That interaction in itself is fundamental to the process of thinking. Like, without social interaction, we would be like stuck like walking in a circle. We need, we need the perturbation of other humans to create change.

In evolution, once you bring in concepts of interactions and correlations and relations, then you have what's called a combinatorial explosion that the number of possibilities expands exponentially technically with the number of things you're considering. And it can easily rapidly outstrip these billions of thoughts that we're talking about. So we definitely cannot, by brute force, master complex situations or think of all the possibilities in complex situations. I mean, even something as relatively simple as chess is still something that human beings can't comprehend completely. Even the best players still sometimes lose, and they consistently lose to computers these days. And in computer science, there's a concept of NP complete. So large classes of problems, when you scale them up beyond a few individuals, become intractable. And so that in that sense, the world is inexhaustible.

And that makes it beautiful that we can make any laws that generalize efficiently and well, can compress all of that combinatorial complexity, just like a simple rule that itself is beautiful.

It's a happy situation, I think, that we can find general principles of the operating system that are comprehensible, simple, extremely powerful, and let us control things very well and ask profound questions. And on the other hand, that the world is going to be inexhaustible once we start asking about relationships and how they evolve and social interactions. And we'll never have a theory of everything in any meaningful sense because of.

Everything, Everything, truly everything is. Can I ask you about the Big Bang? So we talked about the space and time are really big. But then. And we humans give a lot of meaning to the word space and time in our. In our, like, daily lives. But then can we talk about this moment of beginning and how we're supposed to think about it, that at the moment of the Big Bang, everything was, what, like infinitely small? And then it just blew up?

We have to be careful here because there's a. There's a common misconception that the Big Bang is like the explosion of a bomb in empty space, that it fills up the surrounding place.

It is space.

It is, yeah. As we understand, it's the fact or the hypothesis, but well supported up to a point that everywhere in the whole universe, early in the history, matter came together into a very hot, very dense. If you run it backwards in time, matter comes together into very hot, very dense and yet very homogeneous plasma. Of all the different kinds of elementary particles and quarks and antiquarks and gluons and photons and electrons and anti electrons, everything, you know, all of that stuff like really hot, really, really dependent, really hot. We're talking about way, way hotter than the surface of the sun, you know? Well, in fact, if you take the equations, as we, as they come, the. The prediction is that the temperature just goes to infinity, but then the equations break down. We don't, you know, we don't, don't really. There are various. The equations become infinity equals infinity. So they don't feel that it's called a singularity. We don't really know. This is running the equations backwards. So you can't really get a sensible idea of what happened before the Big Bang. We don't. And so we need different equations to address the very earliest moments. So things were hotter and denser. We don't really know why things started out that way. We have a lot of evidence that they did start out that way. But since most of the. We don't get to visit there and do controlled experiments, most of the record is very, very processed. And we have to use very subtle techniques and powerful instruments to get information that has survived, get closer and closer to the Big Bang, get closer and closer to the beginning of things. And what's revealed there is that, as I said, there undoubtedly was a period when everything in the universe that we have been able to look at and understand, and that's consistent with everything, Was in a condition where it was much, much hotter and much, much denser, but still obeying the laws of physics as we know them today. And then you start with that, so all the matter is in equilibrium, and then with small quantum fluctuations and run it forward, and then it produces, at least in broad strokes, the universe we see around us today.

Do you think we'll ever be able to, with the tools of physics, with the way sciences, with the way the human mind is, will ever be able to get to the moment of the Big Bang in our understanding or even the moment before the Big Bang? Can we understand what happened before the Big Bang?

I'm optimistic both that we'll be able to measure more, so observe more, and that we'll be able to figure out more. So they're very, very tangible prospects for observing the extremely early universe. So even much earlier than we can observe now through looking at gravitational waves. Gravitational waves, since they interact so weakly with ordinary matter, sort of send a minimally processed signal from the Big Bang. It's a very weak signal because it's traveled a long way and diffused over long spaces. But people are gearing up to try to detect gravitational waves that could have come from the early universe.

Yeah, LIGO's incredible engineering project. It's the most sensitive, precise devices on Earth. The fact that humans can build something like that is truly awe inspiring from.

An engineering perspective, but these gravitational waves from the early universe would probably be of a much longer wavelength than LEICA is capable of sensing. So there's a beautiful project that's contemplated to put lasers in different locations in the solar system. We really, really separated by solar system scale differences, like artificial planets or moons in different places, and see the tiny motions of those relative to one another as a signal of radiation from the Big Bang. We can also maybe indirectly see the imprint of gravitational waves from the early universe on the photons, the microwave background radiation. That is our present way of seeing into the earliest universe. But those photons interact much more strongly with matter. They're much more strongly processed. So they don't give us directly such an unprocessed view of the early universe, of the very early universe. But if gravitational waves leave some imprint on that as they move through, we could detect that too. And people are trying, are, as we speak, working very hard towards, towards that goal.

It's so exciting to think about a sensor the size of a solar system.

That would be a fantastic. I mean, that would be a pinnacle.