The following is a conversation with Peter White, a theoretical physicist at Columbia,

outspoken critical strength theory, and the author of the popular physics and mathematics

blog called Not Even Wrong.

This is the Lex Friedman podcast.

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And now, here's my conversation with Peter White.

You're both a physicist and a mathematician, so let me ask, what is the difference between

physics and mathematics?

Well, there's kind of a conventional understanding of the subject that there are two quite different

things.

So that mathematics is about making rigorous statements about these abstract things, things

of mathematics and proving them rigorously.

And physics is about doing experiments and testing various models and that.

But I think the more interesting thing is that there's a wide variety of what people

do as mathematics, what they do as physics, and there's a significant overlap, and that

I think is actually a much, much very, very interesting area.

And if you go back kind of far enough in history and look at figures like Newton or something,

I mean, at that point, you can't really tell, you know, was Newton a physicist or a mathematician.

Christians will tell you as a mathematician, the physicists will tell you as a physicist.

He will say he's a philosopher.

Yeah, that's interesting.

But anyway, there was kind of no such distinction then that's more of a modern thing.

But anyway, I think these days there's a very interesting space in between the two.

So in the story of the 20th century and the early 21st century, what is the overlap between

mathematics and physics, would you say?

Well, I think it's actually become very, very complicated.

I think it's really interesting to see a lot of what my colleagues in the math department

are doing.

Most of what they're doing, they're doing all sorts of different things, but most of

them have some kind of overlap with physics or other.

So I'm personally interested in one particular aspect of this overlap, which I think has

a lot to do with the most fundamental ideas about physics and about mathematics.

But you kind of see this really, really everywhere at this point.

Which particular overlap are you looking at, Goop theory?

Yeah.

So at least the way it seems to me that if you look at physics and look at our most

successful laws of fundamental physics, they have a certain kind of mathematical structure.

It's based upon certain kind of mathematical objects and geometry, connections and curvature,

the spinners, the Dirac equation.

And this very deep mathematics provides kind of a unifying set of ways of thinking that

allow you to make a unified theory of physics.

But the interesting thing is that if you go to mathematics and look at what's been going

on in mathematics the last 50 hundred years, and even especially recently, there's similarly

some kind of unifying ideas which bring together different areas of mathematics, which have

been especially powerful in number theory recently.

There's a book, for instance, by Edward Frankel about love and math.

Yeah, that book's great.

I recommend it highly.

It's partially accessible, but there's a nice audiobook that I listened to while running

an exceptionally long distance like across the San Francisco bridge.

And there's something magic about the way he writes about it, but some of the group

theory in there is a little bit difficult.

Yeah, that's the problem with any of these things, to kind of really say what's going

on and make it accessible is very hard.

He, in this book and elsewhere, I think takes the attitude that kinds of mathematics he's

interested in and that he's talking about are, provide kind of a grand unified theory

of mathematics.

They bring together geometry and number theory and representation theory, a lot of different

ideas in a really unexpected way.

But I think, to me, the most fascinating thing is if you look at the kind of grand unified

theory of mathematics he's talking about and you look at the physicists kind of ideas

about unification, it's more or less the same mathematical objects are appearing in both.

So it's this, I think there's a really, we're seeing a really strong indication that the

deepest ideas that we're discovering about physics and some of the deepest ideas that

mathematicians are learning about are really, are intimately connected.

Is there something, if I was five years old and you were trying to explain this to me,

is there ways to try to sneak up to what this unified world of mathematics looks like?

You said number theory, you said geometry, words like topology, what does this universe

begin to look like?

What should we imagine in our mind?

Is it a three dimensional surface and we're trying to say something about it?

Is it triangles and squares and cubes, like what are we supposed to imagine our minds?

Is this natural number?

What's a good thing to try to, for people that don't know any of these tools except

maybe some basic calculus and geometry from high school that they should keep in their

minds as to the unified world of mathematics that also allows us to explore the unified

world of physics?

I mean, what I find kind of remarkable about this is the way in which we've discovered

these ideas, but they're actually quite alien to our everyday understanding.

We grow up in this three spatial dimensional world and we have intimate understanding of

certain kinds of geometry and certain kinds of things, but these things that we've discovered

in both math and physics are, they're not at all close, have any obvious connection

to kind of human everyday experience.

They're really quite different.

And I can say some of my initial fascination with this when I was young and starting to

learn about it was actually exactly this kind of arcane nature of these things.

It was a little bit like being told, well, there are these kind of semi mystical experience

that you can acquire by a long study and whatever except that it was actually true and there's

actually evidence that this actually works.

So I'm a little bit wary of trying to give people that kind of thing because I think

it's mostly misleading.

But one thing to say is that geometry is a large part of it and maybe one interesting

thing to say very, that's about more recent, some of the most recent ideas is that when

we think about the geometry of our space and time, it's kind of three spatial and one time

dimension.

Let's say physics is in some sense about something that's kind of four dimensional in a way.

And a really interesting thing about some of the recent developments and number theory

have been to realize that these ideas that we were looking at naturally fit into a context

where your theory is kind of four dimensional.

So geometry is a big part of this and we know a lot and feel a lot about two, one, two,

three dimensional geometry.

So wait a minute.

So we can at least rely on the four dimensions of space and time and say they can get pretty

far by working in that in those four dimensions.

I thought you were going to scare me that we're going to have to go to many, many, many,

many more dimensions than that.

My point of view, which goes against a lot of these ideas about unification is that,

no, this is really, everything we know about really is about four dimensions that, and

that you can actually understand a lot of these structures that we've been seeing in

fundamental physics and in number theory just in terms of four dimensions that it's kind

of, it's in some sense I would claim has been a mistake that physicists have made for decades

and decades to try to go to higher dimensions, to try to formulate a theory in higher dimensions.

And then you're stuck with the problem of how do you get rid of all these extra dimensions

that you've created because we only ever see anything in four dimensions.

That kind of thing leaves us astray, you think.

So creating all these extra dimensions just to give yourself extra degrees of freedom.

I mean, isn't that the process of mathematics is to create all these trajectories for yourself,

but eventually have to end up at a final place.

And it's okay to sort of create abstract objects on your path to proving something.

Yeah, certainly.

And from a mathematician's point of view, I mean, the kinds of mathematicians also are

very different than physicists in that we like to develop very general theories.

If we have an idea, we want to see what's the greatest generality in which you can talk

about it.

So from the point of view of most of the ways geometry is formulated by mathematicians,

it really doesn't matter.

It works in any dimension.

We can do one, two, three, four, any number.

There's no particular, for most of geometry, there's no particular special thing but four.

But anyway, but what physicists have been trying to do over the years is try to understand

these fundamental theories in a geometrical way.

And it's very tempting to kind of just start bringing in extra dimensions and using them

to explain the structure.

But typically this attempt kind of founders because you just don't know, you end up not

being able to explain why we only see four.

It is nice in the space of physics that like if you look at Fermat's last theorem, it's

much easier to prove that there's no solution for n equals three than it is for the general

case.

And so I guess that's the nice benefit of being a physicist is you don't have to worry

about the general case because we live in a universe with n equals four in this case.

Yeah, physicists are very interested in saying something about specific examples.

And I find that interesting even when I'm trying to do things in mathematics and I'm

trying to even teaching courses into mathematics students, I find that I'm teaching them in

a different way than most mathematicians because I'm very often very focused on examples on

what's kind of the crucial example that shows how this powerful new mathematical technique,

how it works and why you would want to do it.

And I'm less interested in kind of proving a precise theorem about exactly when it's

going to work and when it's not going to work.

Do you usually think about really simple examples, like both for teaching and when you try to

solve a difficult problem, do you construct like the simplest possible examples that captures

the fundamentals of the problem and try to solve it?

Yeah, yeah, exactly.

That's often a really fruitful way to, if you've got some idea, just to kind of try

to boil it down to what's the simplest situation in which this kind of thing is going to happen

and then try to really understand that and understand that and that is almost always

a really good way to get insight into it.

Do you work with paper and pen or like, for example, for me, coming from the programming

side, if I look at a model, if I look at some kind of mathematical object, I like to mess

around with it sort of numerically.

I just visualize different parts of it, visualize however I can.

So most of the work is like when you're on networks, for example, is you try to play

with the simplest possible example and just to build up intuition by, you know, any kind

of object has a bunch of variables in it and you start to mess around with them in different

ways and visualize in different ways to start to build intuition.

Or do you go the Einstein route and just imagine like everything inside your mind and sort

of build like thought experiments and then work purely on paper and pen?

Well, the problem with this kind of stuff I'm interested in is you rarely can kind of,

it's rarely something that is really kind of, or even the simplest example, you can

kind of see what's going on by looking at something happening in three dimensions.

There's generally the structures involved are either they're more abstract or if you

try to kind of embed them in some kind of space and where you could manipulate them

in some kind of geometrical way, it's going to be a much higher dimensional space.

So even simple examples, embedding them into three dimensional space, you're losing a lot?

Yeah.

Or but to capture what you're trying to understand about them, you have to go to four or more

dimensions so it starts to get to be hard to, and you can train yourself to try it as

much as to kind of think about things in your mind and, you know, I often use pad and paper

and often if my office office is the blackboard, and you are kind of drawing things, but they're

really kind of more abstract representations of how things are supposed to fit together

and they're not really, unfortunately, not just kind of really living in three dimensions

where you cannot.

Are we supposed to be sad or excited by the fact that our human minds can't fully comprehend

the kind of mathematics you're talking about?

I mean, what do we make of that? I mean, to me, that makes me quite sad. It makes me,

it makes it seem like there's a giant mystery out there that will never truly get to experience

directly.

It is kind of sad, you know, how difficult this is. I mean, or I would put it a different

way that, you know, most questions that people have about this kind of thing, you know, you

can give them a really true answer and really understand it, but the problem is one more

of time. It's like, yes, you know, I could explain to you how this works, but you'd

have to be willing to sit down with me and, you know, work at this repeatedly for hours

and days and weeks. I mean, it's just going to take that long for your mind to really

wrap itself around what's going on.

And so that does make things inaccessible, which is sad. But I mean, it's just kind of

part of life that we all have a limited amount of time, and we have to decide what we're

going to, what we're going to spend our time doing.

Speaking of a limited amount of time, we only have a few hours, maybe a few days together

here on this podcast. Let me ask you the question of amongst many of the ideas that you work

on in mathematics and physics, what's used the most beautiful idea or one of the most

beautiful ideas, maybe a surprising idea. And once again, unfortunately, the way life

works, we only have a limited time together to try to convey such an idea.

Okay. Well, actually, let me just tell you something, which I'm tempted to kind of start

trying to explain what I think is this most powerful idea that brings together math and

physics ideas about groups and representations and how it fits quantum mechanics. But in

some sense, I wrote a whole textbook about that. And I don't think we really have time

to get very far into it.

Well, can I actually, on a small tangent, you did write a paper towards a grant unified

theory of mathematics and physics. Maybe you can step there first. What is the key idea

in that paper?

Well, I think we've kind of gone over that. I think the key idea is what we were talking

about earlier, that just kind of a claim that if you look and see what's that have been

successful idea as a unification in physics over the last 50 years or so, and what's been

happening in mathematics and the kind of thing that Frankel's book is about, that these

are very much the same kind of mathematics. And so it's kind of an argument that there

really is, you shouldn't be looking to unify just math or just fundamental physics, but

taking inspiration for looking for new ideas and fundamental physics, that they are going

to be in the same direction of getting deeper into mathematics and looking for more inspiration

in mathematics from these successful ideas about fundamental physics.

Could you put words to sort of the disciplines we're trying to unify? So you said number

theory. Are we literally talking about all the major fields of mathematics? So it's like

the number theory geometry, so like differential geometry, topology, like.

So the, I mean, one name for this, that this is acquired in mathematics is the so called

Langlands program. And so this started out in mathematics. It's that, you know, Robert

Langlands kind of realized that a lot of what people were doing in them, that was starting

to be really successful in number theory in the 60s. And so that this actually was, anyway,

that this could be, could be a thought of in terms of these ideas about symmetry in groups

and representations. And, and in a way that was also close to some ideas about geometry.

And then more later on in the 80s and 90s, there was something called geometric Langlands

that people realized that you could take what people have been doing in number theory in

Langlands and, and get rid, just forget about the number theory and ask, what is this telling

you about geometry? And you get a whole, some new insights into certain kinds of geometry

that way. So it's anyway, that's kind of the name for this area is Langlands and geometric

Langlands. And just recently in the last few months, there's been, there's kind of really

major paper that appeared by Peter Schultz and Laurel Farg, where they, you know, made,

you know, some serious advance and try to understand a very much kind of a local problem

of what happens in number theory near a certain prime number. And they turned this into a

problem of exactly the, the kind of geometric Langlands people had been doing these kind

of pure, a pure geometry problem. And they found by generalizing mathematics, they could

actually reformulate it in that way. And it worked perfectly well.

One of the things that makes me sad is, you know, I'm a pretty knowledgeable person. And

then what is it? At least I'm in the neighborhood of like theoretical computer science, right?

And it's still way out of my reach. And so many people talk about like Langlands, for

example, is one of the most brilliant people in mathematics and just really admire his

work. And I can't, it's like, almost I can't hear the music that he composed. And it makes

me sad.

Yeah. Well, I mean, I think unfortunately, it's not just you. It's I think even most

mathematicians have no, really don't actually understand what this is about. I mean, the

group of people who really understand all these ideas. And so for instance, this paper

of Shultz and Farg that I was talking about, the number of people who really actually understand

how that works is anyway, very, very small. And so it's a, so I think even you find if

you talk to mathematicians and physicists, even they will often feel that, you know,

there's this really interesting sounding stuff going on and which I should be able to understand.

It's kind of in my own field. I have a PhD in, but it still seems pretty clearly far

beyond me right now.

Well, if we can step into the back to the question of beauty, is there an idea that

maybe is a little bit smaller that you find beautiful in this pace of mathematics or physics?

There's an idea that, you know, I kind of went, got a physics PhD and spent a lot of

time learning about mathematics. And I guess it was embarrassing that I hadn't really actually

understood this very simple idea until I kind of learned it when I actually started teaching

math classes, which is maybe that there, there, maybe there's a simple way to explain kind

of fundamental way in which algebra and geometry are connected. So you normally think of geometry

is about these spaces and these points. And, and you think of algebra is this very abstract

thing about with these abstract objects that satisfy certain kinds of relations, you can

multiply them and add them and do stuff. But it's, it's completely abstract. It is nothing

geometric about it. But the kind of really fundamental idea is that unifies algebra and

geometry is to, is to realize, is to think whenever, whenever anybody gives you what

you call an algebra, some abstract thing of things that you can multiply and add that

you should ask yourself, is that algebra the space of functions on some geometry? So one

of the most surprising examples of this, for instance, is a standard kind of thing that

seems to have nothing to do with geometry is the, is the, the integers. So then there,

you can, you can multiply them and add them. It's, it's an algebra, but the, it has seems

to have nothing to do with geometry. But what you can, it turns out, but if you ask yourself

this question and ask, you know, is our integers, can you think if somebody gives you an integer,

can you think of it as a function on some space on some geometry? And it turns out that

yes, you can. And the space is the space of prime numbers. And so what you do is you just,

if somebody gives you an integer, you can make a function on the prime numbers by just,

you know, at each prime number, taking that, that integer modulo, that prime. So if, as

you say, I don't know, if you give, give in 10, you know, 10, and you ask, what is its

value at two? Well, it's, it's five times two. So mod two is zero. So it has zero one.

What is, what is its value at three? Well, it's nine plus one. So it's, it's one mod

three. So it's, it's zero at two. It's one at three. And you can kind of keep going.

And so this is really kind of a truly fundamental idea. It's at the basis of what's called algebraic

geometry. And it just links these two parts of mathematics that look completely different.

And it's just an incredibly powerful idea. And so much of mathematics emerges from this

kind of simple relation.

So you're talking about mapping from one discrete space to another, to another. So for a second,

I thought perhaps mapping like a continuous space to a discrete space, like functions

over a continuous space, because, yeah, well, you can, I mean, you can take, if somebody

gives you a space, you can ask, you can say, well, let's, let's, and this is also, this

is part of the same idea. The part of the same idea is that if you try and do geometry

and somebody tells you, here's a space, that what you should do is you should wait to say,

wait a minute, maybe I should be trying to solve this using algebra. And so if I do that,

the way to start is you give me the space, I start to think about the functions on the

space. Okay. So for each point in the space, I associate a number. I can take different

kinds of functions and different kinds of values, but, but basically functions on a

space. So what this insight is telling you is that if you're a geometer, often the way

to, to, to work is to trans change your problem into algebra by changing your space, stop

thinking about your space and the points in it and thinking about the functions on it.

And if you're, and if you're an algebraist and you've got these abstract algebraic gadgets

that you're multiplying and adding say, wait a minute, are those gadgets, can I think of

them in some way as a function on a space? What would that space be and what kind of

functions would they be? And that going back and forth really brings these two completely

different looking areas of mathematics together.

Do you have particular examples where it allowed to prove some difficult things by jumping

from one to the other? Is that something that's a part of modern mathematics where such jumps

are made? Oh yeah. So this is kind of all the time. A lot, much, much of modern number

theory is kind of based on this idea. But, and, and when you start doing this, you start

to realize that you need, you know, what simple things, simple things on one side of the algebra

is, you know, start to require you to think about the other side about geometry in a new

way. You have to kind of get a more sophisticated idea about geometry. Or if you start thinking

about the functions on a space, you may have, you may need a more sophisticated kind of

algebra. But, but in some sense, I mean, much or most of modern number theory is based

upon this move to geometry. And there's also a lot of geometry and topology is also based

upon, yeah, change. If you want to understand the topology of something, you look at the

functions, you do Dharam callmology, and you get the topology.

Anyway.

Well, let me ask you then the ridiculous question. You said that this idea is beautiful. Can

you formalize the definition of the word beautiful? And why is this beautiful? Like, well, first,

why is this beautiful? And second, what is beautiful?

Well, and I think there are many different things you can find beautiful for different

reasons. I mean, I think in this context, the notion of beauty, I think really is just

kind of an idea is beautiful if it's packages a huge amount of kind of power and information

into something very simple. So in some sense, you can almost kind of try and measure it

in the sense of, you know, what's the, what are the implications of this idea? What non

trivial things does it tell you versus, you know, how, how, how, how simply can you express

the idea?

So the level of compression, what does it correlates with beauty?

Yeah. That's one, one aspect of it. And so you can start to tell that an idea is becoming

uglier and uglier as you start kind of having to, you know, it doesn't quite do what you

want. So you throw in something else to the idea and you keep doing that until you get

what you want. But that's how you know you're doing something uglier and uglier when you

have to kind of keep adding in more, more, more into what was originally a fairly simple

idea and making it more and more complicated to get what you want.

Okay. So let's put some philosophical words on the table and trying to make some sense

of them. One word is beauty. Another one is simplicity, as you mentioned. Another one

is truth. So do you have a sense, if I give you two theories, one is simpler, one is more

complicated. Do you have a sense of which one is more likely to be true to capture deeply

the fabric of reality? The simple one or the more complicated one?

Yeah. I think all of our evidence and what we see in the history of the subject is the

simpler one. Though often it's a surprise. It's simpler in a surprising way, but yeah,

that we just don't, we just, anyway, the kind of best theories we've been coming up with

are ultimately when properly understood, relatively simple and much, much simpler than you would

expect them to be.

Do you have a good explanation why that is? Is it just because humans want it to be that

way? Or we're just like ultra biased and we just kind of convince ourselves that simple

is better because we find simplicity beautiful? Or is there something about our actual universe

that at the core is simple?

My own belief is that there is something about a universe that is that simple and I was trying

to say that there is some kind of fundamental thing about math, physics, and physics and

all this picture, which is in some sense simple. It's true that our minds are very limited

and can certainly do certain things and not others. So it's in principle possible that

there's some great insight. There are a lot of insights into the way the world works,

which is aren't accessible to us because that's not the way our minds work. We don't. And

at what we're seeing, this kind of simplicity is just because that's all we ever have any

hope of seeing.

So there's a brilliant physicist by the name of Sabine Hassanfelder who both agrees and

disagrees with you. I suppose agrees that the final answer will be simple. But simplicity

and beauty leads us astray in the local pockets of scientific progress. Do you agree with

her disagreement? Do you disagree with her agreement? And agree with the agreement and

so on?

Yes, I thought it was really fascinating reading her book. Anyway, I was finding disagreeing

with a lot. But then at the end, when she says, yes, when we find there, when we actually

figure this out, it will be simple. And okay, so we agree in the end.

But does beauty lead us astray, which is the core thesis of her work in that book?

Actually, I guess I do disagree with her on that so much. I don't think, and especially,

and I actually fairly strongly disagree with her about sometimes the way she'll refer

to math. So the problem is, physicists and people in general just refer to it as math,

and they're often meaning not what I would call math, which is the interesting ideas

of math, but just some complicated calculation. And so I guess my feeling about it is more

that the problem with talking about simplicity and using simplicity as a guide is that it's

very easy to fool yourself. And it's very easy to decide to fall in love with an idea.

You have an idea, you think, oh, this is great, and you fall in love with it. And like any

kind of love affair, it's very easy to believe that the object of your affections is much

more beautiful than others might think, and that they really are. And that's very, very

easy to do. So if you say, I'm just going to pursue ideas about beauty and mathematics

in this, it's extremely easy to just fool yourself, I think. And I think that's a lot

of what the story she was thinking of about where people have gone to stray that, I think

it's, I would argue that it's more people. It's not that there was some simple, powerful,

wonderful idea which they'd found, and it turned out not to be useful, but it was more

that they kind of fooled themselves that this was actually a better idea than it really

was, and that it was simpler and more beautiful than it really was, is a lot of the story.

I think so it's not that the simplicity would be Lisa's strays that just people are people

and they fall in love with whatever idea they have. And then they weave narratives around

that idea, or they present the institution that emphasizes the simplicity and the beauty.

Yeah, that's part of it. But the thing about physics that you have is that you, you know,

that really can tell, if you can do an experiment and check and see if nature is really doing

what your idea expects, that you do in principle have a way of really testing it. And it's

certainly true that if you, you know, if you thought you had a simple idea and that doesn't

work and you got into an experiment and what actually does work is somewhere, maybe some

more complicated version of it, that can certainly happen and that can be true. I think her emphasis

is more that I don't really disagree with is that people should be concentrating on when

they're trying to develop better theories on morons, on self consistency, not so much

on beauty, but, you know, not is this idea beautiful, but, you know, is there something

about the theory which is not quite consistent and that and use that as a guide that there's

something wrong there which needs fixing. And so I think that part of her argument,

I think I was, we're on the same page about what's, what is consistency and inconsistency?

Well, what, what exactly do you have examples in mind? Well, it can be just simple inconsistency

between theory and an experiment that if you, so we have this great fundamental theory,

but there are some things that we see out there which don't seem to fit in like, like

dark energy and dark matter, for instance. But if there's something which you can't test

experimentally, I think, you know, she would argue, and I would agree that, for instance,

if you're trying to think about gravity and how are you going to have a quantum theory

of gravity, you should kind of be, you know, test any of your ideas with kind of kind of

a thought experiment, you know, is, does this actually give a consistent picture of what's

going to happen, of what happens in this particular situation or not?

So this is a good example you've written about this. You know, since quantum gravitational

effects are really small, super small, arguably unobservably small, should we have hope to

arrive at a theory of quantum gravity somehow? What are the different ways we can get there?

You've mentioned that you're not as interested in that effort because basically, yes, you

cannot have ways to scientifically validate it given the tools of today.

You know, I've actually, you know, I've over the years certainly spent a lot of time learning

about gravity and about attempts to quantize it, but it hasn't been that much in the past,

the focus of what I've been thinking about. But I mean, my feeling was always, you know,

as I think speed would agree that the, you know, one way you can pursue this if you can't

do experiments is just this kind of search for consistency. You know, it can be remarkably

hard to come up with a completely consistent model of this in a way that brings together

a quantum mechanics and general relativity. And that's, I think, kind of been the traditional

way that people who have pursued quantum gravity have often pursued, you know, we have the

best route to finding a consistent theory of quantum gravity. And string theorists will

tell you this. Other people will tell you it's kind of what people argue about. But

the problem with all of that is that you end up, the danger is that you end up with that

everybody could be successful. Everybody, everybody's program for how to find a theory

of quantum gravity, you know, ends up with something that is consistent. And so, in some

sense, you could argue this is what happened to the strength there is they, they solve

their problem of finding a consistent theory of quantum gravity and then it, but they found

10 of the 500 solutions. So you, you know, if you believe that everything that they would

like to be true is true, well, okay, you've got a theory, but it's, it ends up being kind

of useless because it's just one of an infant, essentially infinite number of things which

you have no way to experimentally distinguish. And so this is just a depressing situation.

But I do think that there is a, so again, I think pursuing ideas about what more about

beauty and how can you integrate and unify these issues about gravity with other things

we know about physics and can you find a theory which were they, were these fit together

in a, in a way that makes sense and, and hopefully predict something that's much more promising.

Well, it makes sense and hopefully, I mean, we'll sneak up onto this question a bunch

of times because you kind of said a few slightly contradictory things, which is like it's nice

to have a theory that's consistent, but then if the theory is consistent, it doesn't necessarily

mean anything. So like, it's not enough. It's not enough. It's not enough. And that's a problem.

So it's like, it keeps coming back to, okay, there should be some experimental validation.

So okay, let's talk a little bit about strength theory. You've been a bit of an outspoken

critic of strength theory. Maybe one question first to ask is, what is strength theory?

And beyond that, why is it wrong? Or rather, as the title of your blog says, not even wrong.

Okay. Well, one interesting thing about the current state of strength theory is that I

think it, I'd argue it's actually very, very difficult to, at this point, to say what strength

theory means. If people say they're strength theorists, what they mean and what they're

doing is a, it's kind of hard, it's hard to pin down the meaning of the term. But the,

but the initial meaning I think goes back to, there was kind of a series of developments

starting in 1984 in which people felt that they had found a unified theory of, of our

so called standard model of all the standard well known kind of particle interactions and

gravity and it all fit together in a quantum theory. And that you could do this in a very

specific way by instead of thinking about having a quantum theory of particles moving

around in space time, think about quantum theory of kind of one dimensional loops moving

around in space time, so called strings. And so instead of one degree of freedom, these

have an infinite number of degrees of freedom. It's a much more complicated theory. But you

can imagine, okay, we're going to quantize this theory of loops moving around in space

time. And what they found is that they, is that you could make, you could do this and

you could fairly, relatively straightforwardly make sense of, of such a quantum theory, but

only if space and time together were 10 dimensional. And so then you had this problem again, the

problem I referred to at the beginning of, okay, now, once you make that move, you got

to get rid of six dimensions. And so the hope was that you could get rid of the six dimensions

by making them very small and that consistency of the theory would require these, that these

six dimensions satisfy a very specific condition called being a Kalabiow manifold and that we

knew very, very few examples of this. So what got a lot of people very excited back in 8485

was the hope that you could just take this 10 dimensional string theory and find one

of a limited number of possible ways of, of getting rid of six dimensions by making them

small and then you would end up with an effective four dimensional theory, which looked like

the real world. This was the hope. So then there's then a very long story about what

happened to that hope over the years. I mean, I would argue and part of the point of the

book and its title was that this ultimately was a failure that you ended up, that this idea just

didn't, there ended up being just too many ways of doing this and you didn't know how to do this

consistently. That it was kind of not even wrong in the sense that you couldn't even, you never

could pin it down well enough to actually get a real falsifiable prediction out of it that would

tell you it was wrong. But it was kind of in the, in the realm of ideas, which initially look good,

but the more you look at them, they just, they don't work out the way, the way you want. And

they don't actually end up carrying the power or the, that you originally had this vision of.

And yes, the book title is not even wrong. Your blog, your excellent blog title is not even wrong.

Okay. But there's nevertheless been a lot of excitement about string theory through the

decades as you mentioned. What are the different flavors of ideas that came, like the branched

out, you mentioned 10 dimensions, you mentioned loops with infinite degrees of freedom. What,

what are the interesting ideas to you that kind of emerged from this world?

Well, yeah, I mean, the problem in talking about the whole subject and part of the reason I wrote

the book is that, you know, it gets very, very complicated. I mean, there's a huge amount, you

know, a lot of people got very interested in this, a lot of people worked on it. And in some

sense, I think what happened is exactly because the idea didn't really work, that this caused

people to, you know, instead of focusing on this one idea and digging in and working on that,

they just kind of kept trying new things. And so people, I think, ended up wandering around in

a very, very rich space of ideas about mathematics and physics and discovering, you know, all sorts

of really interesting things. It's just the problem is there tended to be an inverse relationship

between how interesting and beautiful and fruitful this new idea that they were trying to pursue

was and how much it looked like the real world. So there's a lot of beautiful mathematics came

out of it. I think one of the most spectacular is what the physicists call two dimensional

conformal field theory. And so these are basically quantum field theories and kind of think of it

as one space and one time dimension, which, you know, have just this huge amount of symmetry and

a huge amount of structure, which does some totally fantastic mathematics behind it. And again,

and some of that mathematics is exactly also what appears in the Langland's program. So a lot of

the first interaction between math and physics around the Langland's program has been around

these two dimensional conformal field theories. Is there something you could say about what

the major problems are with string theory? So like, besides that there's no experimental

validation, you've written that a big hole in string theory has been its perturbative definition.

Yeah. Perhaps that's one. Can you explain what that means?

Well, maybe to begin with, I think the simplest thing to say is the initial idea really was that,

okay, we have this, instead of what's great is we have this thing that only works. It's very

structured and has to work in a certain way for it to make sense. But then you ended up in 10

space time dimensions. And so to get back to physics, you had to get rid of five of the

dimensions, six of the dimensions. And the bottom line, I would say in some sense is very simple,

that what people just discovered is just there's kind of no particularly nice way of doing this.

There's an infinite number of ways of doing it, and you can get whatever you want, depending on

how you do it. So you end up, the whole program of starting at 10 dimensions and getting to four,

just kind of collapses out of a lack of any way to kind of get to where you want, because you

can get anything. The hope around that problem has always been that the standard formulation that

we have of string theory, which is you can go in by the name perturbative, but it's kind of,

there's a standard way we know of given a classical theory of constructing a quantum theory and working

with it, which is the so called perturbation theory, that we know how to do. And that, that by

itself just doesn't give you any hint as to what to do about the six dimensions. So actual perturbed

with string theory by itself really only works in 10 dimensions. So you have to start making some

kinds of assumptions about how I'm going to go beyond this formulation that we really understand

of string theory and get rid of these six dimensions. So kind of the simplest one was the

clavial postulate. But when that didn't really work out, people have tried more and more different

things. And the hope has always been that the solution, this problem would be that you would

find a deeper and better understanding of what string theory is that would actually go beyond

this perturbative expansion, which would generalize this. And that once you had that,

it would solve this problem of, it would pick out what to do with the six dimensions.

How difficult is this problem? So if I could restate the problem, it seems like there's a

very consistent physical world operating in four dimensions. And how do you map a consistent

physical world in 10 dimensions to a consistent physical world in four dimensions? And how

difficult is this problem? Is that something you can even answer? Just in terms of physics

intuition, in terms of mathematics, mapping from 10 dimensions to four dimensions?

Well, basically, I mean, you have to get rid of the six of the dimensions. So there's kind

of two ways of doing it. One is what we call compactification. You say that there really

are 10 dimensions, but for whatever reason, six of them are really are so, so small, we

can't see them. So you basically start out with 10 dimensions. And what we call make

six of them not go out to infinity, but just kind of a finite extent, and then make that

size go down so small, it's unobservable. That's a math trick. So can you also help

me build an intuition about how rich and interesting the world in those six dimensions

is? So compactification seems to imply that it's not very interesting.

Well, no, but the problem is that what you learn if you start doing mathematics and looking

at geometry and topology and more and more dimensions is that, I mean, asking the question

like, what are all possible six dimensional spaces? It's just a, it's kind of an unanswerable

question. It's just, I mean, it's even kind of technically undecidable in some way. They're

just too, too, there are too many things you can do with all these. If you start trying

to make, if you start trying to make one dimensional spaces, it's like, well, you got a line, you

can make a circle, you can make graphs, you can kind of see what you can do. But as you

go to higher and higher dimensions, there's just so many ways you can put things together

of and get something of that dimensionality. And so it, unless you have some very, very

strong principle, which is going to pick out some very specific ones of these six dimensional

spaces, and there's just too many of them and you can get anything you want.

So if you have 10 dimensions, the kind of things that happen or say that's actually

the way that's actually the fabric of our realities, 10 dimensions, there's a limited

set of behaviors of objects, I don't know, even know what the right terminology to use

that can occur within those dimensions, like in reality. And so like what I'm getting at

is like, is there some consistent constraints? So if you have some constraints that map to

reality, then you could start saying like, dimension number seven is kind of boring.

All the excitement happens in the spatial dimensions one, two, three. And time is also

kind of boring. And like, some are more exciting than others, or we can use our metric of beauty.

Some dimensions are more beautiful than others. Once you have an actual understanding of what

actually happens in those dimensions in our physical world, as opposed to sort of all

the possible things that could happen.

In some sense, just the basic fact is you need to get rid of them. We don't see them.

So you need to somehow explain them. The main thing you're trying to do is to explain why

we're not seeing them. And so you have to come up with some theory of these extra dimensions

and how they're going to behave. And string theory gives you some ideas about how to do

that. But the bottom line is where you're trying to go with this whole theory you're

creating is to just make all of its effects essentially unobservable. So it's not a really,

it's an inherently kind of dubious and worrisome thing that you're trying to do there. Why are

you just adding in all the stuff and then trying to explain why we don't see it?

I mean, it just

This may be a dumb question, but is this an obvious thing to state that those six dimensions

are unobservable or anything beyond four dimensions is unobservable? Or do you leave a little door

open to saying the current tools of physics and obviously our brains aren't unable to

observe them. But we may need to come up with methodologies for observing them. So as opposed

to collapsing your mathematical theory into four dimensions, leaving the door open a little

bit too, maybe we need to come up with tools that actually allow us to directly measure

those dimensions.

Yes. I mean, you can certainly ask, you know, assume that we've got model, look at models

with more dimensions and ask, you know, what would be observable effects? How would we

know this? And then you go out and do experiments. So for instance, you have like gravitationally

you have an inverse square law forces. Okay, if you had more dimensions, that inverse square

law would change something else. So you can go and start measuring the inverse square

law and say, okay, inverse square law is working. But maybe if I get, it turns out to be actually

kind of very, very hard to measure gravitational effects at even kind of, you know, somewhat

macroscopic distances because they're so small. So you can start looking at the inverse square

law and say, start trying to measure it at shorter and shorter distances and see if there

were extra dimensions at those distance scales, you would start to see the inverse square

law fail. And so people look for that. And again, you don't see it. But you can, I mean,

there's all sorts of experiments of this kind, you can imagine which test for effects of

extra dimensions at different, at different distance scales, but none of them, I mean,

they all just don't work.

Nothing yet. But you can say, ah, but it's, it's just, it's just much, much smaller. You

can say that. Which by the way, makes LIGO and the detection of gravitational waves quite

an incredible project. Ed Whitten is often brought up as one of the most brilliant mathematicians

and physicists ever. What do you make of him and his work on string theory?

Well, I think he's a truly remarkable figure. I've, you know, had the pleasure of meeting

him first when he was a postdoc. And I mean, he's just completely amazing mathematician

and physicist. And, you know, he's quite a bit smarter than just about any of the rest

of us and also more hardworking. It's a, it's a kind of frightening combination to see how

much he's been able to do. And, but I would actually argue that, you know, his, his greatest

work, the things that he's done that have been of just this mind blowing significance

of giving us, I mean, he's completely revolutionized some areas of mathematics. He's totally revolutionized

the way we understand the relations between mathematics and physics. And most of those,

his greatest work is stuff that doesn't have as little or nothing to do with string theory.

I mean, for instance, he, you know, he, so he was actually one of fields. The very strange

thing about him in some sense is that he, he doesn't have a Nobel Prize. So there, there's

a very large number of people who are nowhere near as smart as he is and don't work anywhere

near as hard who have Nobel Prizes. I think he just had the misfortune of coming into

the field at a time when things had gotten much, much, much tougher and nobody really

had, no matter how smart you were, it was very hard to come up with a new idea that

it was going to work physically and get you a Nobel Prize. But he, but he, you know, he,

he had got a Fields Medal for a certain work he did in, in mathematics. And that's just

completely unheard of, you know, for mathematicians to give a Fields Medal to someone outside

their field and physics is really, you know, you wouldn't have before he came around. I

don't think anybody would have thought that was even conceivable.

So you're saying is he came into the field of theoretical physics at a time when, and

still to today is you can't get a Nobel Prize for purely theoretical work.

The specific problem of trying to do better than the standard, the standard model is just

this insanely successful thing. And it kind of came together in 1973 pretty much. And

post and so, and all of the people who kind of were involved in that coming together,

you know, many of them ended up with Nobel Prizes for that. But, but if you look post

1973 pretty much, it's a little bit more, there's some edge cases if you like, but the,

if you look post 1973 at what people have done to try to do better than the standard

model and to get a better, you know, idea, it really hasn't, it's been too hard a problem.

It hasn't worked. The theory is too good. And so it's not that other people went out

there and did it and not him and that they got Nobel Prizes for doing it. It's just that

no one really, the kind of thing he's been trying to do with string theory is not, um,

no one has been able to do since 1973.

Is there something you can say about the standard model? So the four laws of physics that seems

to work very well. And yet people are striving to do more talking about unification. So on

why, what's wrong, what's broken about the standard model? Why, why does it need to be

improved?

I mean, the thing that gets most attention is, um, is gravity that we have trouble. Um,

so you want to, you want to in some sense integrate, integrate what we know about the

gravitational force with it and have a unified quantum field theory that has gravitational

interactions also. So that's the big problem. Everybody talks about, um, I mean, but it,

but it's also true that if you look at the standard model, it has these very, very deep

beautiful ideas, but there's certain aspects of it that are very, that are, let's, let's

just say that they're not beautiful. They're not, um, you have to, to make the thing work,

you have to throw in lots and lots of extra parameters at various points. Um, and a lot

of this has to do with the so called, uh, you know, the so called Higgs mechanism in

the Higgs field that if you look at the theory, it's everything is, if you forget about the

Higgs field and what it needs to do, the rest of the theory is, um, is very, very constrained

and has very, very few free parameters, really a very small number. There's a very small

number of parameters and a few integers which tell you what the theory is to make this work

as a theory, the real world. You need a Higgs field and you need to, it needs to do, to

do something. And once you introduce that Higgs field, all sorts of parameters, um,

make it apparent. So now when we've got 20 or 30 or whatever, whatever parameters that

are going to tell you what all the masses of things are and what's going to happen.

So you've gone from a very tightly constrained thing with a couple of parameters to, uh,

this thing, which the minute you put it in, you had to add all this extra, all these extra

parameters to make things work. And so that, it may be one argument as well, that's just

the way the world is. And the fact that you don't find that aesthetically pleasing is

just your problem or maybe we live in a multiverse and those numbers are just different in every

universe. But, but, you know, another reasonable conjecture is just that, well, this is just

telling us that there's something we don't understand about what's going on in a deeper

way, which would explain those numbers. And there's some kind of deeper idea about where

the Higgs field comes from and what's going on, which we haven't figured out yet. And

that that's, that's what we should look for.

But to stick on string theory a little bit longer, could you play devil's advocate and

try to argue for string theory? Why it is something that deserve the effort that it

got and still can, like if you think of it as a flame, still should be a little flame

that keeps, keeps burning.

Well, I think the, I mean, the most positive argument for it is all the, you know, all

sorts of new ideas about mathematics and about parts of physics really emerge from it. So

it was very a fruitful source of ideas. And I think, you know, this is actually one argument

you'll definitely, which I kind of agree with all here from, from Whitton and from other

string theorists, you know, this is, this is just such a fruitful and inspiring idea.

And it's led to so many other different things coming out of it that, you know, there must

be something right about this. And that's, you know, okay, that anyway, I think that

that's probably the strong, the strongest thing that they, that they've got.

But you, you don't think there's aspects to it that could be neighboring to, to, to a

theory that does unify everything, to a theory of everything, like it could, it may not be

exactly, exactly the theory, but sticking on it longer might get us closer to the theory

of everything.

Well, the problem with it now really is that you really don't know what it is now. You've

never, nobody has ever kind of come up with this nonperturbative theory. So it's, it's

become more and more frustrating and an odd activity to try to argue with string theorists

about string theory, because it's become less and less well defined what it is. And it's

become actually more and more kind of a, whether you have this weird phenomenon of people calling

themselves string theorists when they've never actually worked on any theory, were there

any strings anywhere.

So what has actually happened kind of sociologically is that you started out with this fairly well

defined proposal. And then I would argue, because that didn't work, people and branched

out in all sorts of directions doing all sorts of things that became farther and farther

removed from that. And for sociological reasons, the ones who kind of started out or now are,

or were trained by the people who worked on that have now become this string, string theorists.

And, and, but, but it's becoming almost more kind of a tribal denominator than a, so it's

very hard to know what you're arguing about when you're arguing about string theory these

days.

Well, to push back on that a little bit, I mean, string theory, it's just a term, right?

It doesn't, like you could, like this is the way language evolves is it could start to represent

something more than just the theory that involves strings, it could represent the effort to unify

the laws of physics, right?

Yeah.

At, at high dimensions with these super tiny objects, right? Or something like that. I

mean, we can sort of put string theory aside. So for example, neural networks in the space

of machine learning, there was a time when they were extremely popular, they became much,

much less popular to a point where if you mentioned neural networks, you're getting

no funding and you're not going to be respected at conferences. And then once again, neural

networks became all the, all the rage about 10, 15 years ago, and as it goes up and down

and a lot of people would argue that using terminology like machine learning and deep

learning is, is, you know, often misused over general, you know, everything that works is

deep learning, everything that doesn't, isn't something like that. You know, that's just

the way, again, we're back to sociological things. But I guess what I'm trying to get

at is if we leave the sociological mess aside, do we throw out the baby with the bathwater?

Is there some, besides the side effects of nice ideas from the admittance of the world,

is there some core truths there that we should stick by in, in, in the full, beautiful mess

of a space that we call string theory, that people call string theory?

You're right. It is kind of a common problem that, you know, how what you're, what you

call some field changes and evolves and in interesting ways as, as the field changes.

But I mean, I guess what I would argue is the, you know, the initial understanding of

string theory that was quite specific, we're talking about a specific idea, 10 dimensional

super strings compactified as six dimensions. That, to my mind, the, the really bad thing

that's happened to the subject is that you, it's hard to get people to admit at least

publicly that that was a failure, that this really didn't work. And so de facto, what

people do is people will stop doing that and they start doing more interesting things.

But they keep talent talking to the public about, about string theory and referring

back to that idea and using that as kind of the starting point and as kind of the place

where the whole, where the whole tribe starts and everything else comes from. And so the

problem with this is that having as your, as your initial name and what everything points

back to something which, which really didn't work out, it kind of makes everybody makes

everything you've created this potentially very, very interesting field with interesting

things happening. But, you know, people in high, in graduate school take courses on string

theory and everything kind of, and this is what you tell the public in which you continually

pointing back. So you're continually pointing back to this idea which never worked out as

your guiding inspiration. And it really kind of deforms the whole, your whole way of your,

your hopes of making progress. And that's to me, I think, you know, the kind of worst

thing that's happened in this field.

Because sure. So there's a lack of transparency, sort of authenticity about communicating the

things that failed in the past. And so you don't have a clear picture of like firm ground

that you're standing on. But again, those are sociological things. And I, there's a

bunch of questions I want to ask you. So one, what's your intuition about why the original

idea failed? So what can you say about why you're pretty sure it has failed?

You know, and the initial idea was, as I try to explain it, it was quite seductive in

that, that you could see why Whitton and others got excited by it. It was, you know, at the

time it looked like there were only a few of these possible clobby hours that would work.

And it looked like, okay, we just have to understand this very specific model in these

very specific six dimensional spaces, and we're going to get everything. And so it was

a very seductive idea. But it just, you know, as people learn more and more about it, it

just didn't, they just kind of realized that there are just more and more things you can

do with these six dimensions and you can't, and this is just not going to work.

Meaning like it's, I mean, what was the failure mode here is you could just have an infinite

number of possibilities that you could do. So it's, you can come up with any theory you

want, you can fit quantum mechanics, you can, you can explain gravity, you can explain anything

you want with it. Is that the basic failure mode?

Yeah. So it's a failure mode of kind of that this idea ended up being kind of being essentially

empty that it just didn't, doesn't end up not telling you anything because it's consistent

with just about just about anything. And so I mean, there's a complex, if you try and

talk with string theorists about this now, I mean, there's a, there's an argument, there's

a long argument over this about whether, you know, oh no, no, no, maybe there's still our

constraints coming, coming out of this idea or not. And, or maybe we live in a multiverse

and, you know, every, everything is true anyway. So you can, there are various ways you can

kind of, the string theorists have kind of react, react to this kind of argument that

I'm making, try to hold on to it.

What about experimental validation? Is that, is that a fair standard to hold before a theory

of everything that's trying to unify quantum mechanics and gravity?

Yeah, I mean, ultimately to be really convinced that, you know, that on some new, you know,

idea about invocation really works, you need some kind of, you need to look at the real

world and see that this is telling you something, something true about it. I mean, you know,

either, either telling you that if you do some experiment and go out and do it, you'll

get some unexpected result and that's the kind of gold standard or it may be just like

all those numbers that are, we don't know how to explain it, it will show you how to

calculate them. I mean, you can, it can be various kinds of experimental validation,

but that, that's certainly ideally what you're looking for.

How tough is this, do you think? For theory of everything, not just string theory. So

for something that unifies gravity and quantum mechanics, so the very big and the very small,

is this a, let me ask it one way, is it a physics problem, a math problem, or an engineering

problem?

My guess is it's a combination of a physics and a math problem that you really need. It's,

it's not really engineering. It's not like there's some kind of well defined thing you

can write down and we just don't have enough computer power to do the calculation. That's

not the kind of problem it is at all. But the question is, you know, what mathematical

tools you need to properly formulate the problem is unclear. So one reasonable conjecture

is the way the reason that we haven't had any success yet is just that we're missing either

or missing certain physical ideas or missing certain mathematical tools, which are some

combination of them, which would, which we need to kind of properly formulate the problem

and see, and see that it, it has a solution that looks like the real world.

But those you need, I guess you don't, but there's a sense that you need both gravity,

all the laws of physics to be operating on the same level. So it feels like you need

an object like a black hole or something like that in order to make predictions about. Otherwise,

you're always making predictions about this joint phenomena. Or can you do that as long

as the theory is consistent and doesn't have special cases for each of the phenomena?

Well, your theory should, I mean, if your theory is going to include gravity, our current

understanding of gravity is that you should have, there should be black hole states in

it, you should be able to describe black holes in this theory. And, and just one aspect that

people have concentrated a lot on is just this kind of questions about if your theory

includes black holes like it's supposed to, and it includes quantum mechanics, then there's

certain kind of paradoxes which come up. And so that's, that's been a huge focus of

kind of quantum gravity work, work has been just those paradoxes.

So stepping outside of string theory, can you just say first at a high level, what is

the theory of everything? What is the theory of everything seek to accomplish?

Well, I mean, this is very much a kind of reductionist point of view in the sense that

so it's not a theory. This is not going to explain to you, you know, anything, it doesn't

really, this kind of theory, theory, this kind of theory of everything we're talking

about doesn't say anything interesting, particularly about like macroscopic objects about what

the weather is going to be tomorrow or, you know, things are happening at this scale.

But just what we've discovered is that as you look at the universe that kind of, you

know, if you kind of start, you can start breaking it apart into, and you end up with

some fairly simple pieces, quanta, if you like, and which are doing, which are interacting

in some fairly, in some fairly simple way. And it's some, it's good. So what we mean

by theory of everything is a theory that describes all, all the object, all the correct objects

you need to describe what's happening in the world and describes how they're interacting

with each other at a most fundamental level. How you get from that theory to describing

some macroscopic incredibly complicated thing is there that becomes, again, more of an engineering

problem and you may need machine learning or you made, you know, a lot of very different

things to do it.

But I don't even think it's just engineering. It's also science. One thing that I find kind

of interesting talking to physicists is a little bit, there's a little bit of hubris.

Some of the most brilliant people I know are physicists, both philosophy and just in terms

of mathematics in terms of understanding the world. But there's a kind of either a hubris

or what would I call it, like a confidence that if we have a theory of everything, we

will understand everything. Like this is the deepest thing to understand. And I would say

and like the rest is details, right? That's the old Rutherford thing. But to me, there's

like this is like a cake or something. There's layers to this thing and each one has a theory

of everything. Like at every level from biology, like how life originates, that itself like

complex systems. Like that in itself is like this gigantic thing that requires a theory

of everything. And then there's the what in the space of humans, psychology, like intelligence,

collective intelligence, the way it emerges among species, that feels like a complex system

that requires its own theory of everything. On top of that is things like in the computing

space, artificial intelligence systems, like that feels like a user theory of everything.

And it's almost like once we solve, once we come up with a theory of everything that explains

the basic laws of physics that gave us the universe, even stuff that's super complex,

like how like how the universe might be able to originate, even explaining something that

you're not a big fan of like multiverses or stuff that we don't have any evidence of yet.

So we won't be able to have a strong explanation of why food tastes delicious.

Oh yeah. No. Anyway, I agree completely. I mean, there is something kind of completely

wrong with this terminology of theory of everything. It's not, it's really in some

sense very bad term, very heuristic and bad terminology because it's not. This is explaining,

this is a purely kind of reductionist point of view that you're trying to understand certain

very specific kind of things, which in principle, other things emerge from. But to actually understand

how anything emerges from this, it can't be understood in terms of this underlying

fund wealth area is going to be hopeless in terms of kind of telling you what about this

various emergent behavior. And as you go to different levels of explanation, you're

going to need to develop different, completely different ideas, completely different ways

of thinking. And I guess there's a famous kind of Phil Andersen's slogan is that more

is different. And so it's just, even once you understand how what a couple of things,

if you have a collection of stuff and you understand perfectly well how each thing is

interacting with it, with the others, what the whole thing is going to do is just a completely

different problem than it's just not. And you need completely different ways of thinking

about it.

What do you think about this? I got to ask you at a few different attempts at a theory

of everything, especially recently. So I've been, for many years, a big fan of cellular

automata of complex systems. And obviously, because of that, a fan of Stephen Wolfram's

work on in that space, but he's recently been talking about a theory of everything through

his physics project, essentially. What do you think about this kind of discrete theory

of everything, like from simple rules and simple objects on the hypergraphs, emerges

all of our reality where time and space are emergent, basically everything we see around

us is emerging.

Yeah. I have to say, unfortunately, I've kind of pretty much zero sympathy for that. I mean,

I don't, I spent a little time looking at it and I just don't see, it doesn't seem to

me to get anywhere. And it really is just really, really doesn't agree at all with what

I'm seeing, this kind of unification of math and physics that I'm kind of talking about

around certain kinds of very deep ideas about geometry and stuff. This, if you want to believe

that your things are really coming out of cellular automata at the most fundamental level,

you have to believe that everything that I've seen my whole career and as beautiful, powerful

ideas that that's all just kind of a mirage, which just kind of randomly is emerging from

these more basic, very, very simple minded things. And you have to give me some serious

evidence for that and I'm saying nothing.

So mirage, you don't think there could be a consistency where things like quantum mechanics

could emerge from much, much, much smaller, discrete, like computational type systems?

Well, I think from the point of view of certain mathematical point of view, quantum mechanics

is already mathematically as simple as it gets. It really is a story about really the

fundamental objects that you work with and when you write down a quantum theory are in

some, in some form point of view, precisely the fundamental objects at the deepest levels

of mathematics that you're working with are exactly the same. And cellular automata are

something completely different, which don't fit into these structures. And so I just don't

see why. Anyway, I don't see it as a promising thing to do. And then just looking at it and

saying, does this go anywhere? Does this solve any problem that I've ever, that I didn't,

does this solve any problem of any kind? I just don't see it.

Yeah, to me, cellular automata and these hypergraphs, I'm not sure solving a problem is even the

standard to apply here at this moment. To me, the fascinating thing is that the question

it asks have no good answers. So there's not good math explaining, forget the physics

of it, math explaining the behavior of complex systems. And that to me is both exciting and

paralyzing. Like we're at the very early days of understanding, you know, how complicated

and fascinating things emerge from simple rules.

Yeah, you know, I agree. I think that is a truly a great problem. And depending where

it goes, it may be, you know, it may start to develop some kind of connections to the

things that I've kind of found more fruitful and hard to know. It just, I think a lot of

that area, I kind of strongly feel I best not say too much about it, because I just,

I don't know too much about it. And I mean, again, we're back to this original problem

that, you know, your time in life is limited. You have to figure out what you're going to

spend your time thinking about. And that's something I just never seen enough to convince

me to spend more time thinking about.

Well, also timing, it's not just that our time is limited, but the timing of the kind

of things you think about there. There's some aspect to cellular automata, these kinds

of objects that it feels like we're very many years away from having big breakthroughs

on. And so it's like, you have to pick the problems that are solvable today. In fact,

my intuition, again, not perhaps biased is it feels like the kind of systems that complex

systems that cellular automata are would not be solved by human brains. It feels like,

well, like it feels like something post human that will solve that problem, or like significantly

enhance humans, meaning like using computational tools, very powerful computational tools to

us to crack these problems open. That's, that's if our approach to science, our ability to

understand science, our ability to understand physics will become more and more computational,

or there'll be a whole field as computational nature, which currently is not the case. Currently,

computation is the thing that sort of assists us in understanding science the way we've

been doing it all along. But if there's a whole new, I mean, that we're from new kind

of science, right? It's a little bit dramatic. But, you know, this, if computers could do

science on their own computational systems, perhaps that's the way they would do the science.

They would try to understand the cellular automata. And that feels like we're decades

away. So perhaps it'll crack open some interesting facets of this physics problem, but it's very

far away. So timing is everything.

That's perfectly possible.

Well, let me ask you then in the space of geometry, I don't know how well, you know,

Erich Weinstein.

Oh, quite well.

What are your thoughts about his geometric community and the space of ideas that he's

playing with on, in his proposal for theory or everything?

Well, I think that he has, he fundamentally has, I think, the same problems that everybody

has had trying to do this. And, you know, there are various, there are really versions

of the same problem that you try to, you try to get unity by putting everything into some

bigger structure. So he has some other ones that are not so conventional that he's trying

to work with. But he has the same problem that even if he can, if he can get a lot farther

in terms of having a really well defined, well understood, clear picture of these things

he is working with, they're really kind of large geometrical structures with many dimensions,

many kinds. And I just don't see any way he's going to have the same problem the string

there has had. How do you get back down to the structures of the standard model? And

how do you, yeah, so I just, anyway, it's the same, and there's another interesting

example of a similar kind of thing is Garrett Luzi's theory of everything. Again, it's

a little bit more specific than Eric's, he's working with this E8. But again, I think all

these things founder at the same point that you don't, you know, you create this unity,

but then you have no, you don't actually have a good idea how you're going to get back to

the actual, to the objects we're seeing, how are you going to, you create these big symmetries,

how are you going to break them? And because we don't see those symmetries in the real

world. And so ultimately, there would need to be a simple process for collapsing it to

four dimensions. You'd have to explain, well, yeah, and I forget in his case, but it's not

just four dimensions. It's also these, these structures you see in the standard model, there's

a, you know, there's certain very small dimensional groups of symmetries called U1, SU2 and SU3.

And the problem with, and this has been the problem since the beginning, almost immediately

after 1973, about a year later, two years later, people started talking about grand unified

theories. So you take the U1, the SU2 and the SU3, and you put them in together into

this bigger structure called the SU5 or SO10. But then you're stuck with this problem that,

wait a minute, how, why does the world not look, why do I not see these SU5 symmetries

in real world? I only see these. And so, and, and, and I think, you know, those, the kind

of thing that, that, that Eric and all of a sudden Garrett and lots of people who try

to do it, they all kind of found her in that same, in that same way that they don't have,

they don't have a good answer to that.

Are there lessons, ideas to be learned from theories like that from Garrett Leases from

Eric's?

Um, I don't know. It depends. I have to confess, I haven't looked that closely at, at, at,

at, at Eric's. I mean, he explained to this to me personally a few times and I looked

a bit at his paper, but it's, um, again, we're, we're, we're back to the problem of a limited

amount of time in life.

Yeah. I mean, it's an interesting effect, right? Why don't more physicists look at it?

They're, I mean, I, I'm, I'm in this position that somehow, you know, uh, I've, I've, uh,

people write me emails for whatever reason. And I had worked in the space of AI and this

is, there's a lot of people, perhaps AI is even way more accessible than physics in a

certain sense. And so a lot of people write to me with different theories about what they

have for how to create general intelligence. And it's again, a little bit of an excuse I

say to myself, like, well, I only have a limited amount of time. So that's why I'm not investigating

it. But I wonder if, um, there's ideas out there that are still powerful. They're still

fascinating. And that I'm missing because I'm, because I'm dismissing them because they're

outside of the sort of the usual process of, uh, academic research.

Yeah. Well, I mean, I have the same thing and pretty much every day in my email, there's

a, somebody's got a theory or everything about why all of what physicists are doing, perhaps

the most disturbing thing I should say about my critique being a critic of string theory

is, is it when you realize who your fans are, um, that they, every day I hear from somebody

said, Oh, well, since you don't like string theory, you must of course agree with me that

this is the right way to think about everything. Oh no. Oh no. And you know, most of these

are, you know, you quickly can see this is person doesn't know very much and doesn't

know what they're doing. You know, but there's a whole continuum to, you know, people who

are quite serious physicists and mathematicians who are making a fairly serious attempt to

try to, to do something and like, like Eric and, uh, and Eric. And then, then your, your

problem is, you know, you spent, you, you do, so I want to try to spend more time looking

at it and try to figure out what they're really doing. And, but then at some point you just

realized, wait a minute, you know, for me to really, really understand exactly what's

going on here would just take time. I just don't have.

Yeah. It takes a long time, which is the nice thing about AI is unlike the kind of physics

we're talking about, if your idea is good, that should quite naturally lead to you being

able to build a system that's intelligent. So you don't need to get approval from say

somebody that's saying you have a good idea here. You can just utilize that idea and engineer

system like naturally leads to engineering with physics here. If you have a perfect theory

that explains everything that still doesn't obviously lead one to, um, to, to scientific

experiments that can validate that theory and two to like, uh, trinkets you can build

and sell at a store for $5.

I can't make money off of it.

So that, that makes it much, much more challenging. Um, well, let me also ask you about something

that you found especially recently appealing, which is Roger Penrose's Twister theory. Um,

what is it? What kind of questions might it allow us to answer? What will the answers

look like?

It's only in the last couple of years that I really, really kind of come to really, I

think, to appreciate it and to see how to really, I believe to see how to really do something

with it. And I've gotten very excited about that the last year or two. I mean, one way

of saying one idea of Twister theory is that what it's, it's, it's a different way of thinking

about what space and time are and about what points in space and time are, but, but which

only, which is very interesting that it only really works in four dimensions. So four dimensions

behaves very, very specially unlike other dimensions. And in four dimensions are certain,

there is a way of thinking about space and time geometry where, you know, as well as

just thinking about points in space and time, you can also think about different objects,

these so called twisters. And then when you do that, you end up with a kind of a really

interesting insight that the, that you can formulate a theory and you can formulate a

very, take a standard theory that we formulate in terms of points of space and time. And

you can reformulate in this Twister language. And in this Twister language, it's be the

fundamental objects are actually, are more kind of the, are actually spheres in some

sense kind of the light cone. So maybe one way to say it, which, which actually I think

is, is really, is quite amazing is if you ask yourself, you know, what do we know about,

about the world? We have this idea that the world out there is this, all these different

points and these points of time. Well, that's kind of a derived quantity. What really, really

know about the world is when we open our eyes, what do you see? You see a sphere. And you,

and that what you're looking at is you're looking at this, you know, a sphere is worth

a light rays coming into, into your eyes. And what Penrose says is that, well, what,

what a point in space time is, is that sphere, that sphere of all the light rays coming in.

And he says, and you should formulate your, instead of thinking about points, you should

think about the space of those spheres, if you like, and formulate the degrees of freedom

as physics as living on those spheres, living on, so you're kind of, you're kind of living

on your degrees of freedom or living on light rays, not on points. And it's a very different

way of thinking about, about, about physics. And you know, he and others working with him

developed a, you know, a beautiful mathematical, this beautiful mathematical formalism and

a way to go back from forth between our kind of some aspects of our standard way we write

these things down and work in the so called twister space. And, you know, they, certain

things worked out very well, but they ended up, you know, I think kind of stuck by the

80s or 90s that they weren't a little bit like string theory that they, they, by using

these ideas about twisters, they could develop them in different directions and find all

sorts of other interesting things. But they were, they were getting, they weren't finding

any way of doing that, that brought them back to kind of new insights into physics.

And my own, I mean, what's kind of gotten me excited really is what I think I have an,

an idea about that I think does actually, does actually work that goes more in that

direction. And I can, can go on about that endlessly or talk a little bit about it. But

that's the, I think that that's the one kind of easy to explain insight about twister theory.

There's some more technical ones. I should, I mean, I think it's also very convincing

what it tells you about spinners, for instance, but that's a more technical.

Well, first let's like linger on the spheres and the light cones. You're saying twisted

theory allows you to make that the fundamental object with which you're operating.

Yeah.

How that, I mean, first of all, like philosophically, that's weird and beautiful. Maybe because

it maps, it feels like it moves us so much closer to the way human brains perceive reality.

So it's almost like our perception is like the, the content of our perception is the

fundamental object of reality. That's very appealing.

Yeah.

Is it mathematically powerful? Is there something you can say, can you say a little bit more

about what the heck that even means for, because it's much easier to think about mathematically

like a point in space time. Like, what does it mean to be operating on the light cone?

It uses a kind of mathematics that's relative, that, you know, what was kind of goes back

to the 19th century and mathematicians. It's not, anyway, it's a bit of a long story.

The one problem is that you have to start, it's crucial that you think in terms of complex

numbers and not just real numbers. And this, for most people, that makes it harder to,

for mathematicians, that's fine. We love doing that. But for most people, that makes it harder

to think about.

But I think perhaps the most, the way that there is something you can say very specifically

about it, you know, in terms of spinners, which I don't know if you want to, I think

at some point, you want to talk.

Yeah.

What are spinners?

I'll start with spinner, because I think that if we can introduce that, then I can say...

By the way, twister is spelled with an O and spinner is spelled with an O as well.

Yes.

Okay.

So...

In case you want to Google it and look it up, there's very nice Wikipedia pages. That's

the starting point. I don't know what is a good starting point for twister 3.

Oh, what?

Well, let me just say about Penrose. I mean, Penrose is actually a very good writer and

also very good draftsman. He's on drafts. To the extent this is visualizable, he actually

has done some very nice drawings. So, I mean, almost anything kind of expository thing you

can find in handwriting is a very good place to start. He's a remarkable person.

But the... So, spinners are something that independently came out of mathematics and

out of physics. And to say where they came out of physics, I mean, what people realized

when they started looking at elementary particles like electrons or whatever, that there seemed

to be... There seemed to be some kind of doubling of the degrees of freedom going on. If you

counted what was there in some sense in the way you would expect it and when you started

doing quantum mechanics and started looking at elementary particles, there were seem to

be two degrees of freedom. They're not one. And one way of seeing it was that if you put

your electron in a strong magnetic field and ask what was the energy of it, instead of

having one energy, it would have two energies. It would be two energy levels. And as you

increased magnetic field, the splitting would increase. So, physicists kind of realized

that, wait a minute. So, we thought when we were doing... First, we're doing quantum mechanics

that the way to describe particles was in terms of wave functions and these wave functions

were complex values. Well, if we actually look at particles, that's not right. They're

pairs of complex numbers. They're pairs of complex numbers. So, one of the kind of fundamental...

From the physics point of view, the fundamental question is, why are all our kind of fundamental

particles described by pairs of complex numbers? It's just weird. And then you can ask, well,

what happens if you take an electron and rotate it? So, how do things move in this pair of

complex numbers? Well, now, if you go back to mathematics, what had been understood in

mathematics some years earlier, not that many years earlier, was that if you ask very,

very generally, think about geometry of three dimensions and ask... And if you think about

things that are happening in three dimensions in the standard way, everything... The standard

way of doing geometry, everything is about vectors. So, if you've taken any mathematics

classes, you probably see vectors at some point. They're just triplets of numbers tell

you what a direction is or how far you're going in three dimensional space. And everything

we teach in most standard courses in mathematics is about vectors and things you build out of

vectors. So, you express everything about geometry in terms of vectors or how they're

changing or how you put two of them together and get planes and whatever. But what I'd

been realized is that if you ask very, very generally, what are the things that you can

kind of consistently think about rotating? So, you ask a technical question, what are

the representations of the rotation group? Well, you find that one answer is they're

vectors and everything you build out of vectors. But then people found, wait a minute, there's

also these other things which you can't build out of vectors, but which you can consistently

rotate and they're described by pairs of complex numbers by two complex numbers. And they're

the spinners also. And you can think of spinners in some sense as more fundamental than vectors

because you can build vectors out of spinners. You can take two spinners and make a vector,

but if you only have vectors, you can't get spinners. So, there's some kind of lower level

of geometry beyond what we thought it was, which was kind of spinner geometry. And this

is something which even to this day when we teach graduate courses in geometry, we mostly

don't talk about this because it's a bit hard to do correctly. If you start with your whole

setup is in terms of vectors, describing things in terms of spinners is a whole different

ballgame. But anyway, it was just this amazing fact that this kind of more fundamental piece

of geometry spinners and what we were actually seeing, if you look at electron, are one and

the same. So, it's kind of a mind blowing thing, but it's very counterintuitive.

What are some weird properties of spinners that are counterintuitive?

There are some things that they do. For instance, if you rotate a spinner around 360 degrees,

it doesn't come back towards, it becomes minus what it was. So, the way rotations work, there's

a kind of a funny sign you have to keep track of in some sense. So, they're kind of too

valued in another weird way. But the fundamental problem is that it's just not, if you're used

to visualizing vectors, there's nothing you can do visualizing in terms of vectors that

will ever give you a spinner. It just is not going to ever work.

As you were saying that I was visualizing a vector walking along a mobius strip and it

ends up being upside down. But you're saying that doesn't really capture.

So, what really captures it, the problem is that it's really the simplest way to describe

it is in terms of two complex numbers. And your problem with two complex numbers is that's

four real numbers. So, your spinner kind of lies in a four dimensional space. So, that

makes it hard to visualize. And it's crucial that it's not just any four dimensions, it's

actually complex numbers. You're really going to use the fact that these are two complex

numbers. So, it's very hard to visualize. But to get back to what I think is mind blowing

about twisters is that another way of saying this idea about talking about spheres, another

way of saying the fundamental idea of twister theory is, in some sense, the fundamental

idea of twister theory is that a point is a two complex dimensional space. And that

it lives inside, the space that it lies inside is twister space. So, in the simplest case,

twister space is four dimensional. And a point in space time is a two complex dimensional

subspace of all the four complex dimensions. And as you move around in space time, you're

just moving, your planes are just moving around. Okay. And that, but then the

So, it's a plane in a four dimensional space.

It's a plane complex plane. So, it's two complex dimensions in four complex. But then to me,

the mind blowing thing about this, is this then kind of tautologically answers the question

is what is a spinner? Well, a spinner is a point. I mean, the space of spinners at a

point is the point. In twister theory, the points are the complex two planes. And you

want me to, and you're asking what a spinner is. Well, a spinner, the space of spinners is that

two plane. So, it's, you know, just your whole definition of what a pointed space time was,

just told you what a spinner was. It's they're just, it's the same thing.

Yeah, we're trying to project that into a three dimensional space and trying to into it.

Yeah. So, the intuition becomes very difficult. But from if you don't, you not using twister

theory, you have to kind of go through a certain fairly complicated rigmarole to even describe

spinners to describe electrons. Whereas using twister theory, it's just completely tautological.

They're just what you want to describe the electron is fundamentally the way that you're

describing the point in space time already. It's just there. So.

Do you have a hope you mentioned that you've been you found an appealing recently is it just

because of certain aspects of its mathematical beauty or do you actually have a hope that this

might lead to a theory of everything? Yeah, I mean, I certainly do have such a hope because

what I've found, I think the thing which I've done, which I don't think as far as I can tell,

no one had really looked at from this point of view before is has to do with it this question of

how do you treat time in your quantum theory? And so there's another long story about how we

do quantum theories and about how we treat time and quantum theories, which is a long story.

But to make this the short version of it is that what people have found when you try and

write down a quantum theory that it's often it's often a good idea to take your time coordinate,

whatever you're using your time coordinate and multiply it by the screw to minus one and to

make it purely imaginary. And so you all these formulas which you have in your standard theory,

if you do that to those, I mean, those formulas have some very strange, strange behavior and

they're kind of singular. If you ask even some simple questions, you have to very take very

delicate singular limits in order to get the correct answer. And you have to take them from

the right direction. Otherwise, it doesn't work. Whereas if you just take time, and if you just

put a factor of screw to minus one, wherever you see the time coordinate, you end up with much

simpler formulas, which are much better behaved mathematically. And what I what I hadn't really

appreciated until fairly recently is also how dramatically that changes the whole structure

of the theory, you end up with a consistent way of talking about these quantum theories. But it

has very some very different flavor and very different aspects that I hadn't really appreciated.

And in particular, the way the way symmetries act on it is not at all what I originally had

expected. And so that's the new thing that I have where I think I think gives you something is to

do this move, which people often think of as just kind of a kind of a mathematical trick that you're

doing to make some formulas work out nicely. But to take that mathematical trick as really

fundamental, and turns out in twister theory, allows you to simultaneously talk about your

usual time and the time times the square root of minus one, they both fit they both fit very

nicely into twister theory. And you end up with some structures which look a lot like the standard

models. Well, let me ask you about some Nobel Prizes. Okay. Do you think there will be? There

was a bet between me, Joe Kaku and somebody else about John, John Horgan, John Horgan about,

by the way, maybe discover a cool website long bets.com or that order. Yeah. Yeah. It's cool.

It's cool that you can make a bet with people and then check in 20 years later. That's I really

love it. There's a lot of interesting bets on there. Yeah, I would love to participate. But

it's interesting to see, you know, time flies. Yeah. And you make a bet about what's going to

happen 20 years, you don't realize 20 years just goes like this. Yeah. And then and then you get

to face and you get to wonder, like, what was that person? What was I thinking that person 20

years ago is almost like a different person. What was I thinking back then to think that is

interesting. But so let me ask you this on record, you know, 20 years from now or some number of

years from now, do you think there will be a Nobel Prize given for something directly connected

to a first broadly theory of everything? And second, of course, one of the possibilities,

one of them, strength theory. Strength theory is definitely not that things have gone. Yeah.

So if you were giving financial advice, you would say not to bet on it.

No, I do not. And even I actually suspect if you ask strength theory is that question,

these days you're going to get few of them saying, I mean, if you'd asked them that question 20

years ago, again, when Kaku was making this bet, whatever, I think some of them would have taken

you up on it. But and certainly back in 1984, a bunch of them would have said, oh, sure. Yeah.

But now I get the impression that they've even they realize that things are not looking good,

for that particular idea. Again, it depends what you mean by strength theory, whether maybe the

term will evolve to mean something else, which, which will work out. But yeah, I don't think

that's not going to like it to work out whether something else, I mean, I still think it's

relatively unlikely that you'll have any really successful theory of everything. And the main

problem is just the, it's become so difficult to do experiments that hire energy that we've

really lost this ability to kind of get unexpected input from, from experiment. And, and you can,

you know, while it's maybe hard to figure out what people's thinking is going to be 20 years

from now, looking at, you know, energy particle, energy colliders and their technology, it's

actually pretty easy to make a pretty accurate guess what it's going to let what, what you're

going to be doing 20 years from now. And I think actually, I would actually claim that it's pretty

clear what, where you're going to be 20 years from now. And what it's going to be is you're

going to have the, you're going to have the LHC, you're going to have a lot more data and order

of magnitude or more, or more data from the LHC, but at the same energy, you're not going to,

you're not going to see a higher energy accelerator operating successfully in the, in the next 20

years. And like maybe machine learning or great sort of data science methodologies that process

that data will not reveal any major like shifts in our understanding of the underlying physics,

do you think? I don't think so. I mean, I think that, that, that feel that my understanding is

that they, they're starting to make a great use of those techniques, but, but it seems to look

like it will help them solve certain technical problems and be able to do things somewhat

better, but not completely change the way they're looking at things. What do you think about the

potential quantum computer is simulating quantum mechanical systems and through that sneak up

to sort of sim, through simulation, sneak up to a deep understanding of the fundamental physics.

The problem there is that, that's promising more for this, for, you know, for Phil Anderson's

problem that, you know, if you want to, there, there's lots and lots of, if you take, you start

pointing together lots and lots of things and we think we know they're pair by pair interactions,

but what this thing is going to do, we don't have any good calculational techniques, you know,

quantum computers, it may, may very well give you those. And so they may, what we think of as

kind of strong coupling behavior, we have no good way to calculate, you know, even though we can

write down the theory, we don't know how to calculate anything with any accuracy in it,

the quantum computer that may solve that problem. But the problem is that they, I don't, I don't

think that they're going to solve the problem, that they help you with a problem of not having

their, of knowing what the right underlying theory is. As somebody who likes experimental

validation, let me ask you the perhaps ridiculous sounding, but I don't think it's actually a

ridiculous question of, do you think we live in a simulation? Do you find that thought experiment

at all useful or interesting? Not, not, not really. I don't, it just doesn't, yeah, anyway,

to me, it doesn't actually lead to any kind of interesting, lead anywhere interesting.

Yeah, to me, so maybe I'll throw a wrench into your thing. To me, it's super interesting from

an engineering perspective. So if you look at virtual reality systems, the, the actual

question is how much computation and how difficult is it to construct a world that, like, there

are several levels here. One is you won't know the different, our human perception systems

and maybe even the tools of physics won't know the difference between the simulated

world and the real world. That's sort of more of a physics question. The, the most interesting

question to me has more to do with why food tastes delicious, which is create how difficult

and how much computation is required to construct a simulation where you kind of know it's a

simulation at first, but you want to stay there anyway. And over time, you don't even

remember. Yeah. Well, anyway, I agree. These are kind of fascinating questions. And they

may be very, very relevant to our future as a species, but yeah, they're just very far

from anything.

But so from a physics perspective, it's not useful to you to think, taking a computational

perspective to our universe, thinking of as an information processing system, and then

they give it as doing computation. And then you think about the resources required to

do that kind of computation and all that kind of stuff. You could just look at the basic

physics and who cares what the, the computer that's running on us.

Yeah. It just, I mean, the kinds of, I mean, I'm willing to agree that you can get into

interesting kinds of questions going down that road, but they're just so different from

anything from what I found interesting. And I just, again, I just have to kind of go back

to life is too short. And I'm very glad other people are thinking about this, but I just

don't see anything I can do with it.

What about space itself? So I have to ask you about aliens. Again, something, since

you emphasize evidence, do you think there is how many, do you think there are and how

many intelligent alien civilizations are out there?

Yeah, I have no idea, but I've certainly, as far as I know, unless the government's

covering it up or something, we haven't heard from, we don't have any evidence for such

things yet, but there's no, there seems to be no, there's no particular obstruction,

why there shouldn't be. So I mean, do you, you work on some fundamental

questions about the physics of reality? When you look up to the stars, do you think about

whether somebody's looking back at us?

Yeah. Well, actually, I originally got interested in physics. I actually started out as a kid

interested in astronomy, exactly that and a telescope and whatever that. And certainly

read a lot of science fiction and thought about that. I find over the years, I find

myself kind of less, anyway, less and less interested in that. Well, just because I don't,

I kind of don't really know what to do with them. I'm also kind of at some point kind

of stopped reading science fiction that much, kind of feeling that there was just two, that

the actual science I was kind of learning about was perfectly kind of weird and fascinating

and unusual enough and better than any of the stuff that, you know, Isaac Asimov, so

why should I?

Yeah. And you can mess with the science much more than the, the distant science fiction,

the one that's exist in our imagination or the one that exists out there among the stars.

Yeah.

Well, you mentioned science fiction. You've written quite a few book reviews. I gotta

ask you about some books perhaps, if you don't mind, is there one or two books that you would

recommend to others and maybe if you can, what ideas you drew from them? Either negative

recommendations or positive recommendations.

Well,

Do not read this book for sure.

Well, I must say, I mean, unfortunately, yeah, you can go to my website and there's

a, you can click on book reviews and you can see I've written a lot of, a lot of, I mean,

as you can tell from my views about string theory, I'm not a fan of a lot of the kind

of popular books about, oh, isn't string theory great? And about, yes, I'm not a fan of a lot

of things of that kind.

Can I ask you a good question on this, a small tangent? Are you a fan? Can you explore the

pros and cons of, forget string theory, sort of science communication, sort of cosmos style,

communication of concepts to people that are outside of physics, outside of mathematics,

outside of even the sciences, and helping people to sort of dream and fill them with

awe about the full range of mysteries in our universe?

That's a complicated issue. I think, you know, I certainly go back and go back to like what

inspired me and maybe to connect a little bit to this question about books. I mean,

certainly when the books, some books that I remember reading when I was a kid were about

the early history of quantum mechanics like Heisenberg's books that he wrote about, you

know, kind of looking back at telling the history of what happened when he developed

quantum mechanics. It's just kind of a totally fascinating, romantic, great story. And those

were very inspirational to me. And I would think maybe that other people might also find

them that.

And that's almost like the human story of the development of the ideas.

Yeah, the human story. But yeah, just also how, you know, these very, very weird ideas

that didn't seem to make sense, how they were struggling with them and how, you know, they

actually, anyway, it's, I think it's the period of physics kind of beginning in 1905,

like in Einstein and ending up with the war when these things are, get used to, you know,

make passively destructive weapons. It's just that totally amazing.

So many, so many new ideas. Let me on another tangent on top of a tangent on top of a tangent

ask, if we didn't have Einstein, so how does science progress? Is it the lone geniuses?

Or is it some kind of weird network of ideas swimming in the air and just kind of the geniuses

pop up to catch them and others would anyway? Without Einstein, would we have special relativity,

general relativity?

I mean, it's an interesting case to case base. I mean, I mean, special special relativity,

I think we would have had, I mean, there are other people. Anyway, you could even argue

that it was already there in some form and some is, but I think special relativity would

have had without Einstein fairly, fairly quickly. General relativity, that was much, much harder

thing to do and required a much more effort, much more sophisticated. That, I think he

would have had sooner or later, but it would have taken, taken quite a bit longer.

That took a bunch of years to validate scientifically the general relativity.

But even for Einstein, from the point where he had kind of a general idea of what he was

trying to do to the point where he actually had a well defined theory that you could actually

compare to the real world, that was, I forget the number of the order of magnitude, ten

years of very serious work. And if he hadn't been around to do that, it would have taken

a while before anyone else got around to it.

On the other hand, there are things like, with quantum mechanics, you have Heisenberg

and Schrodinger came up with two, which ultimately equivalent, but two different approaches to

it within months of each other. And so if Heisenberg hadn't been there, he already would

have had Schrodinger or whatever. And if neither of them had been there, it would have been

somebody else a few months later. So there are times when the, just the, a lot often

is the combination of the right ideas are in place and the right experimental data is

in place to point in the right direction. And it's just waiting for somebody's going

to find it. Maybe, maybe to go back to your, to your aliens, I guess the one thing that

I often wonder about aliens is, would they have the same fundamental physics ideas as

we, if we have in mathematics, would their math, you know, would they, you know, how,

how much is this really intrinsic to our minds? If, if you start out with a different

kind of mind, wouldn't you end up with a different ideas of what fundamental physics

is or what, or what the structure of mathematics is?

So this is why, like if I was, you know, I like video games, the way I would do it as

a curious being, so first experiment I'd like to do is run earth over many thousands of

times and see if our particular, no, you know what, I wouldn't do the full evolution. I

would start at homo sapiens first and then see the evolution of homo sapiens millions

of times and see how the, the ideas of science would evolve. Like, would you get like, how

would physics evolve? How would math evolves? I would particularly just be curious about

the notation they come up with. Every once in a while, I would like throw miracles at

them to like, to mess with them and stuff. And then I would also like to run earth from

the very beginning to see if evolution will produce different kinds of brains that would

then produce different kinds of mathematics and physics. And then finally, I would probably

millions of times run the universe over to see what kind of, what kind of environments

and what kind of life would be created to then lead to intelligent life to then lead

to theories of mathematics and physics and to see the full range. And like sort of like

Darwin kind of mark. Okay. It took them, what is it, several hundred million years to come

up with calculus. I would just like keep noting how long it took and get an average and see,

see which ideas are difficult, which are not. And then, and then conclusively sort of figure

out if it's, if it's more collective intelligence or singular intelligence, that's responsible

for shifts and for big phase shifts and breakthroughs in science. If I was playing a video game

and I got a chance to run this whole thing. Yeah. But um, we're talking about books before

I distract. Yeah, go back books. And yeah. So, and then, yeah. So that's one thing I'd

recommend is the, is the books, books about the, from the original people, especially

Heisenberg about the, how that happened. And there's also a very, very good kind of history

of, of the kind of what happened during this 20th century in physics. And, you know, up

to the time of the standard model in 1973, it's called the, the second creation by Pop

Creuson and man, that's one of the best ones. I know that's, but the one thing that I can

say is that, so that book, I think, forget when it was late 80s, 90s. The problem is

that there just hasn't been much that's actually worked out since then. So most of the books

that are kind of trying to tell you about all the glorious things that have happened

since 1973 are, they're mostly telling you about how glorious things are, which actually

don't really work. And it's really the argument people sometimes make in terms, in favor of

these books as well. Oh, you know, they're really great because you want to do something

that will get kids excited. And then, you know, so they're getting excited about things,

something that's not really quite working. It's doesn't really matter. The main thing

is get them excited. The other argument is, you know, wait a minute, when you, if you're

getting people excited about ideas that are wrong, you're really kind of, you're actually

kind of discrediting the whole scientific enterprise in a, in a not really good way.

So there's just problems. So my general feeling about expository stuff is, yeah, it's to the

extent you can do it kind of honestly and, and, and well, that's great. There are a lot

of people doing that now. But to the extent that you're just trying to get people excited,

enthusiastic by kind of telling them stuff, which isn't really true. This is, you really

shouldn't be doing that.

You obviously have a much better intuition about physics. I tend to, in the space of

AI, for example, you could, you could use certain kinds of language, like calling things

intelligent, that could rub people the wrong way. But I never had a problem with that kind

of thing, you know, saying that a program can learn its way without any human supervision

as AlphaZero does to play chess. To me, that may not be intelligence, but I sure that as

HEC seems like a few steps down the path towards intelligence. And so like, I think that's

a very peculiar property of systems that can be engineered. So even if the idea is fuzzy,

even if you're not really sure what intelligence is, or like, if you don't have a deep fundamental

understanding, or even a model what intelligence is, if you build a system that sure as heck

is impressive, and showing some of the signs of what previously thought impossible for

a non intelligent system, then that's impressive. And that's inspiring. And that's okay to celebrate.

In physics, because you're not engineering anything, you're just now swimming in the

space directly when you do theoretical physics, that it could be more dangerous. You could

be out too far away from shore. I think physics is actually hard for people even to believe

or really understand how that this particular kind of physics has gotten itself into a really

unusual and strange and historically unusual state, which is not really, I mean, I spent

half my life among mathematicians, math and physics. And, you know, mathematics is kind

of doing fine. People are making progress. And it has all the usual problems, but also,

so you could have a, but, but you just, I just, I don't know, I've never seen anything

at all happening in mathematics, like what's happened in the specific area in physics. It's

just the kind of sociology of this, the way this field works, banging up against this

harder problem without anything from experiment to help it. It's really, it's led to some

really kind of problematic things. And those, so it's one thing to kind of, you know, oversimplify

or to slightly misrepresent to try to explain things in a way that's not quite right. But

it's another thing to start promoting to people as a success as ideas, which, which really

completely failed. And so, I mean, I'm, I've kind of a very, very specific. If you used

to have people, I won't name any names, for instance, coming on certain podcasts like

yours telling the world, you know, this is a huge success. And this is really wonderful.

And it's just not true. And, and this is, this, this is really problematic. And it carries

a serious danger of, you know, once when people realize that this is what's going on, you

know, they, you know, the loss of credibility of, of science is a real real problem for

our society. And, and you don't want, you don't want people to have an all too good

reason to think that what they're being, what they're being told by kind of some of the

best institutions or a country or authorities is not true, you know, is, is not true. It's

a problem.

That's, it's obviously characteristic of not just physics. It's a, it's sociology.

And it's, I mean, obviously in the space of politics, it's, that's the history of politics

is you, you sell ideas to people even when you don't have any proof that those ideas

actually work.

Yeah.

Because if they've, have worked in that, that seems to be the case throughout history.

And just like you said, it's human beings running up against a really hard problem.

I'm not sure if this is like a particular like trajectory through the progress of physics

that we're dealing with now, or is it just a natural progress of science? You run up against

a really difficult stage of a field and different people that behave differently in the face

of that. Some sell books and sort of tell narratives that are beautiful and so on. They're not

necessarily grounded in solutions that have proven themselves. Others kind of put their

head down quietly, keep doing the work. Others sort of pivot to different fields. And that's

kind of like, yeah, ants scattering. And then you have fields like machine learning, which

is there's a few folks mostly scattered away from machine learning in the, in the nineties

in the winter of AI, AI winter, as they call it. But a few people kept their head down

and now they're called the fathers of deep learning. And they didn't think of it that

way. And in fact, if there's another AI winter, they'll just probably keep working on it anyway,

sort of like a loyal ants, to a particular, so it's, it's interesting. But you're sort

of saying that we should be careful over hyping things that have not proven themselves, because

people will lose trust in the scientific process. But unfortunately, there's been other ways

in which people have lost trust in the scientific process that ultimately has to do actually

with all the same kind of behavior as you're highlighting, which is not being honest and

transparent about the flaws of mistakes of the past.

Yeah, I mean, that's always a problem. But this particular field is kind of, I'm always

a, it's always a strange one. I mean, I think in the sense that there's a lot of public

fascination with it, that it seems to speak to kind of our deepest questions about, you

know, what is this physical reality? Where do we come from? And what, and these kind

of deep issues. So there's, there's this unusual fascination with it. Mathematics is versus

very different. Nobody, nobody's that interested in mathematics. Nobody really kind of expects

to learn really great deep things about the world from mathematics that much. They don't

ask mathematicians that. So, so, so it's a very unusual, it draws this kind of unusual

amount of attention. And it really is historically in a really unusual state. It's kind of, it's

gotten itself way kind of down a, down a blind alley in a way which it's hard to find other

historical parallels.

But sort of to push back a little bit, there's power to inspiring people. And if I just empirically

look, physicists are really good at combining science and philosophy and communicating it.

Like there's something about physics often that forces you to build a strong intuition

about the way reality works, right? And that allows you to think through sort of and communicate

about all kinds of questions. Like if you see physicists, it's always fascinating to

take on problems that have nothing to do with their particular discipline. They think interest

in interesting ways and they're able to communicate their thinking in interesting ways. And so

in some sense, they have a responsibility not just to do science, but to inspire and

not responsibility, but the opportunity. And thereby, I would say a little bit of a responsibility.

Yeah. Yeah. And sometimes, but I don't know. Anyway, it's hard to say because, because different

there, there's many, many people doing this kind of thing with different degrees of success

and whatever. I guess one thing, but I mean, my, what's kind of front and center for me

is kind of a more parochial interest is just kind of what, what damage do you do to the

subject itself? Ignoring, misrepresenting, you know, what a high school students think

about string theory and not that doesn't matter much, but what the smartest undergraduates

or the smartest graduate students in the world think about it and what paths you're leading

them down and what story you're telling them and what textbooks you're making them read

and what they're hearing. And so a lot of what's motivated me is more to try to speak

to this kind of a specific population of people to make sure that look, you know, people,

it doesn't matter so much what the average person on the street thinks about string theory,

but you know, what the best students at Columbia or Harvard or Princeton or whatever who really

want to change, work in this field and want to work that way, what they know about it,

what they think about it and that they not be going to the field being misled and believing

that a certain story, this is where this is all going. This is what I got to do. It's

important to me.

In general, for graduate students, for people who seek to be experts in the field, diversity

of ideas is really powerful and is getting into this local pocket of ideas that people

hold on to for several decades is not good. No matter what the idea, I would say no matter

if the idea is right or wrong, because there's no such thing as right in the long term, like

it's right for now until somebody builds on something much bigger on top of it. It might

end up being right, but being a tiny subset of a much bigger thing. You always should

question the ways of the past.

Yeah. Yeah. So how to achieve that diversity of thought within the sociology of how we

organize scientific research. I know this is one thing that I think it's very interesting

that Sabina Hossenfelder is very interesting things to say about it. I think also at least

Moen and his book, which is also about very much in agreement with them that there's a

really important questions about how research in this field is organized and what can you

do to get more diversity of thought and get people thinking about a wider range of ideas.

At the bottom, I think humility always helps.

Well, but the problem is that it's also a combination of humility to know when you're

wrong and also, but also you have to have a certain very serious lack of humility to

believe that you're going to make progress on some of these problems.

I think you have to have both modes, which are between them when needed. Let me ask you

a question you're probably not going to want to answer because you're focused on the mathematics

of things and mathematics can't answer the why questions, but let me ask you anyway.

Do you think there's meaning to this whole thing? What do you think is the meaning of

life? Why are we here?

I don't know. Yeah, I was thinking about this. So the, and it did occur to me, what interesting

thing about that question is that you don't, yeah, so I have this life in mathematics and

this life in physics and I see some of my physicists colleagues, you know, kind of seem

to be people are often asking them, what's the meaning of life and they're writing books

about the meaning of life and teaching courses about the meaning of life. But then I realized

that no one ever asked my mathematician colleagues. Nobody ever asked mathematicians.

That's funny. Yeah. Everybody just kind of assumes, okay, well, you people are studying

about that. I see whatever you're doing, it's maybe very interesting, but it's clearly not

going to tell me anything useful about the meaning of my life. And I'm afraid a lot

of my point of view is that if people realize how little difference there was between what

the mathematicians are doing and what a lot of these theoretical physicists are doing,

they might understand that it's a bit misguided to look for deep insight into the meaning

of life from, from many theoretical physicists. It's not a, they, you know, they're, they're

people and they have, they may have interesting things to say about this. You're right. They

have, they know a lot about physical reality and about, about in some sense about metaphysics

about what is real of this kind. But you're also, to my mind, I think you're also making

a bit of a mistake that you're, you're looking to, I mean, I'm very, very aware that, you

know, I've led a very pleasant and fairly privileged existence of a fairly, without

many challenges of different kinds and of a certain kind. And I'm really not in no way

the kind of person that a lot of people who are looking for to try to understand in some

of the meaning of life and the sense of the challenges that they're facing in life, I

can't really, I'm really the wrong person for you to be asking about this.

Well, if struggle is somehow a thing that's core to meaning, perhaps mathematicians are

just quietly the ones who are most equipped to answer that question. If in fact, the creation

or at least experiencing beauty is, is, is at the core of the meaning of life, because

it seems like mathematics is the methodology by which you can most purely explore beautiful

things, right? So in some sense, maybe we should talk to mathematicians more.

Yeah, yeah, maybe, but, but the, unfortunately, I think, you know, people do have a somewhat

correct perception that what these people are doing every day is pretty far removed

from anything. Yeah, from what's kind of close to what I'm, what I do every day and what

my typical concerns are. So you may learn something very interesting by talking to mathematicians,

but it's, it's probably not going to be, you're probably not going to get what you were hoping.

So when you put the pen and paper down, you're not thinking about physics, and you're not

thinking about mathematics, and you just get to breathe in the air and look around you

and realize that you're going to die one day. Yeah, do you think about that? Your ideas

will live on, but you the human. Not, not, not especially much. It's certainly

I've been getting, getting older. I'm now 64 years old. You start to realize, well,

there's probably less ahead than there was behind. And so you start to, that starts

to become, you know, what do I think about that? Maybe I should actually get serious

about getting some things done, which I, which I may not have, which I may otherwise not

have time to do, which I didn't see. And this didn't seem to be a problem when I was younger,

but that's the main, I think the main way in which that thought occurred.

But it doesn't, you know, the Stoics are big on this, meditating on mortality helps you

more intensely appreciate the beauty when you do experience it.

I suppose that's true, but it's not, yeah, it's not, not something I spend a lot of,

a lot of time trying, but, but yeah.

Day to day, you just enjoy the positive, the mathematics.

Just enjoy our life in general. Life is, have a perfectly pleasant life and enjoy it. And

often think, wow, this is, things are, I'm really enjoying this. Things are going well.

And yeah, life is pretty amazing. I think you and I are pretty lucky. We get to live

on this nice little earth with a nice little comfortable climate and we get to have this

nice little podcast conversation. Thank you so much for spending your valuable time with

me today and having this conversation. Thank you.

Good. Thank you.

Thank you.

Thanks for listening to this conversation with Peter White. To support this podcast, please

check out our sponsors in the description. And now let me leave you some words from Richard

Feynman. The first principle is that you must not fool yourself and you are the easiest

person to fool. Thank you for listening and hope to see you next time.