Peter Woit: Theories of Everything and Why String Theory is Not Even Wrong

Lex Fridman (01:23.380)

But he would say he's a philosopher.

Peter Woit (01:26.040)

Yeah, that's interesting.

Lex Fridman (01:28.880)

But yeah, anyway, there was kind of no such distinction

Peter Woit (01:32.400)

then that's more of a modern thing.

Lex Fridman (01:35.000)

But anyway, I think these days,

Peter Woit (01:36.100)

there's a very interesting space in between the two.

Lex Fridman (01:38.080)

So in the story of the 20th century

Lex Fridman (01:40.820)

and the early 21st century,

Lex Fridman (01:42.360)

what is the overlap between mathematics and physics,

Lex Fridman (01:44.640)

would you say?

Lex Fridman (01:45.960)

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

Peter Woit (01:49.800)

I think it's really interesting to see

Lex Fridman (01:51.520)

a lot of what my colleagues in the math department

Peter Woit (01:54.280)

are doing, most of what they're doing,

Lex Fridman (01:56.880)

they're doing all sorts of different things,

Lex Fridman (01:58.140)

but most of them have some kind of overlap

Lex Fridman (02:00.360)

with physics or other.

Peter Woit (02:02.360)

So, I mean, I'm personally interested

Lex Fridman (02:03.840)

in one particular aspect of this overlap,

Peter Woit (02:06.640)

which I think has a lot to do with the most fundamental ideas

Lex Fridman (02:09.680)

about physics and about mathematics.

Lex Fridman (02:12.040)

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

Lex Fridman (02:17.040)

Which particular overlap are you looking at, group theory?

Peter Woit (02:20.480)

Yeah, so at least the way it seems to me

Lex Fridman (02:24.440)

that if you look at physics

Lex Fridman (02:25.520)

and look at our most successful laws of fundamental physics,

Lex Fridman (02:29.960)

they have a certain kind of mathematical structure,

Peter Woit (02:33.480)

it's based upon certain kind of mathematical objects

Lex Fridman (02:36.240)

and geometry, connections and curvature,

Peter Woit (02:38.800)

the spinners, the Dirac equation.

Lex Fridman (02:41.720)

And this very deep mathematics provides kind of a unifying

Peter Woit (02:47.720)

set of ways of thinking that allow you

Lex Fridman (02:50.480)

to make a unified theory of physics.

Lex Fridman (02:52.720)

But the interesting thing is that if you go to mathematics

Lex Fridman (02:55.480)

and look at what's been going on in mathematics

Peter Woit (02:58.440)

the last 50, 100 years, and even especially recently,

Lex Fridman (03:02.640)

there's a similarly some kind of unifying ideas

Peter Woit (03:06.720)

which bring together different areas of mathematics

Lex Fridman (03:08.840)

and which have been established in the last 50, 100 years.

Peter Woit (03:11.680)

Especially powerful in number theory recently.

Lex Fridman (03:13.680)

And there's a book, for instance, by Edward Frankel

Peter Woit (03:17.720)

about love and math.

Lex Fridman (03:19.240)

Yeah, that book's great, I recommend it highly.

Peter Woit (03:21.320)

It's partially accessible.

Lex Fridman (03:24.160)

But there's a nice audio book that I listened to

Peter Woit (03:27.800)

while running an exceptionally long distance,

Lex Fridman (03:31.920)

like across the San Francisco bridge.

Lex Fridman (03:35.500)

And there's something magic about the way he writes about it.

Lex Fridman (03:38.940)

But some of the group theory in there

Peter Woit (03:40.520)

is a little bit difficult.

Lex Fridman (03:42.240)

Yeah, that's the problem with any of these things,

Peter Woit (03:44.000)

to kind of really say what's going on

Lex Fridman (03:45.960)

and make it accessible is very hard.

Peter Woit (03:48.880)

He, in this book and elsewhere, I think takes the attitude

Lex Fridman (03:52.360)

that kinds of mathematics he's interested in

Lex Fridman (03:54.440)

and that he's talking about provide

Lex Fridman (03:57.080)

kind of a grand unified theory of mathematics.

Peter Woit (03:59.240)

They bring together geometry and number theory

Lex Fridman (04:03.160)

and representation theory, a lot of different ideas

Peter Woit (04:06.840)

in a really unexpected way.

Lex Fridman (04:09.700)

But I think, to me, the most fascinating thing

Peter Woit (04:11.440)

is if you look at the kind of grand unified theory

Lex Fridman (04:13.840)

of mathematics he's talking about

Lex Fridman (04:15.440)

and you look at the physicist kind of ideas

Lex Fridman (04:17.520)

about unification, it's more or less

Peter Woit (04:19.800)

the same mathematical objects are appearing in both.

Lex Fridman (04:22.600)

So it's this, I think there's a really,

Peter Woit (04:24.880)

we're seeing a really strong indication

Lex Fridman (04:26.440)

that the deepest ideas that we're discovering about physics

Lex Fridman (04:30.240)

and some of the deepest ideas that mathematicians

Lex Fridman (04:32.400)

are learning about are really, are intimately connected.

Peter Woit (04:36.120)

Is there something, like if I was five years old

Lex Fridman (04:38.840)

and you were trying to explain this to me,

Peter Woit (04:40.640)

is there ways to try to sneak up

Lex Fridman (04:43.720)

to what this unified world of mathematics looks like?

Peter Woit (04:47.400)

You said number theory, you said geometry,

Lex Fridman (04:50.200)

words like topology.

Lex Fridman (04:52.520)

What does this universe begin to look like?

Lex Fridman (04:54.520)

Are these, what should we imagine in our mind?

Lex Fridman (04:57.500)

Is it a three dimensional surface?

Lex Fridman (05:00.840)

And we're trying to say something about it.

Lex Fridman (05:03.240)

Is it triangles and squares and cubes?

Lex Fridman (05:07.320)

Like what are we supposed to imagine in our minds?

Lex Fridman (05:09.460)

Is this natural number?

Lex Fridman (05:10.560)

What's a good thing to try to,

Peter Woit (05:13.880)

for people that don't know any of these tools

Lex Fridman (05:16.800)

except maybe some basic calculus and geometry

Peter Woit (05:19.000)

from high school that they should keep in their minds

Lex Fridman (05:22.240)

as to the unified world of mathematics

Peter Woit (05:24.860)

that also allows us to explore the unified world of physics.

Lex Fridman (05:30.480)

I mean, what I find kind of remarkable about this

Peter Woit (05:33.120)

is the way in which these, we've discovered these ideas,

Lex Fridman (05:38.200)

but they're actually quite alien

Peter Woit (05:40.240)

to our everyday understanding.

Lex Fridman (05:42.440)

We grow up in this three spatial dimensional world

Lex Fridman (05:45.640)

and we have intimate understanding

Lex Fridman (05:47.480)

of certain kinds of geometry and certain kinds of things.

Lex Fridman (05:50.440)

But these things that we've discovered

Lex Fridman (05:53.520)

in both math and physics are,

Peter Woit (05:56.060)

that they're not at all close,

Lex Fridman (05:58.300)

have any obvious connection

Peter Woit (05:59.800)

to kind of human everyday experience.

Lex Fridman (06:02.040)

They're really quite different.

Lex Fridman (06:03.160)

And I can say some of my initial fascination with this

Lex Fridman (06:06.040)

when I was young and starting to learn about it

Peter Woit (06:08.400)

was actually exactly this kind of arcane nature

Lex Fridman (06:14.160)

of these things.

Peter Woit (06:15.000)

It was a little bit like being told,

Lex Fridman (06:17.420)

well, there are these kind of semi mystical experience

Peter Woit (06:21.040)

that you can acquire by a long study and whatever,

Lex Fridman (06:24.340)

except that it was actually true.

Peter Woit (06:27.000)

There's actually evidence that this actually works.

Lex Fridman (06:29.560)

So I'm a little bit wary of trying to give people

Peter Woit (06:33.000)

that kind of thing,

Lex Fridman (06:33.840)

because I think it's mostly misleading.

Lex Fridman (06:35.200)

But one thing to say is that geometry is a large part of it.

Lex Fridman (06:39.880)

And maybe one interesting thing to say very,

Peter Woit (06:43.280)

that's about more recent, some of the most recent ideas

Lex Fridman (06:45.800)

is that when we think about the geometry

Peter Woit (06:48.440)

of our space and time,

Lex Fridman (06:50.040)

it's kind of three spatial and one time dimension.

Peter Woit (06:53.640)

It's a physics is in some sense

Lex Fridman (06:56.760)

about something that's kind of four dimensional in a way.

Lex Fridman (07:00.760)

And a really interesting thing about

Lex Fridman (07:03.720)

some of the recent developments and number theory

Peter Woit (07:06.160)

have been to realize that these ideas

Lex Fridman (07:09.960)

that we were looking at naturally fit into a context

Peter Woit (07:12.760)

where your theory is kind of four dimensional.

Lex Fridman (07:15.860)

So, geometry is a big part of this

Lex Fridman (07:19.840)

and we know a lot and feel a lot about

Lex Fridman (07:22.160)

two, one, two, three dimensional geometry.

Lex Fridman (07:24.600)

So wait a minute, so we can at least rely

Lex Fridman (07:28.100)

on the four dimensions of space and time

Lex Fridman (07:31.520)

and say that we can get pretty far

Lex Fridman (07:32.920)

by working in those four dimensions.

Peter Woit (07:35.640)

I thought you were gonna scare me

Lex Fridman (07:36.700)

that we're gonna have to go to many, many, many,

Peter Woit (07:39.000)

many more dimensions than that.

Lex Fridman (07:40.640)

My point of view, which goes against

Peter Woit (07:43.360)

a lot of these ideas about unification

Lex Fridman (07:44.800)

is that no, this is really,

Peter Woit (07:47.320)

everything we know about really is about four dimensions

Lex Fridman (07:50.560)

and that you can actually understand a lot of these

Peter Woit (07:54.800)

structures that we've been seeing in fundamental physics

Lex Fridman (07:56.840)

and in number theory, just in terms of four dimensions,

Peter Woit (08:01.480)

that it's kind of, it's in some sense I would claim

Lex Fridman (08:05.400)

has been a really, has been kind of a mistake

Peter Woit (08:09.040)

that physicists have made for decades and decades

Lex Fridman (08:12.880)

to try to go to higher dimensions,

Peter Woit (08:16.560)

to try to formulate a theory in higher dimensions

Lex Fridman (08:19.040)

and then you're stuck with the problem

Peter Woit (08:21.600)

of how do you get rid of all these extra dimensions

Lex Fridman (08:23.400)

that you've created

Peter Woit (08:25.080)

because we only ever see anything in four dimensions.

Lex Fridman (08:27.440)

That kind of thing leaves us astray, you think?

Lex Fridman (08:29.920)

So creating all these extra dimensions

Lex Fridman (08:31.960)

just to give yourself extra degrees of freedom.

Peter Woit (08:35.800)

Isn't that the process of mathematics

Lex Fridman (08:38.360)

is to create all of these trajectories for yourself

Lex Fridman (08:41.280)

but eventually you have to end up at the final place

Lex Fridman (08:45.920)

but it's okay to sort of create abstract objects

Peter Woit (08:52.600)

on your path to proving something.

Lex Fridman (08:55.880)

Yeah, certainly and from a mathematician's point of view,

Peter Woit (08:59.640)

I mean, the kinds of,

Lex Fridman (09:01.360)

mathematicians also are very different than physicists

Peter Woit (09:03.440)

in that we like to develop very general theories.

Lex Fridman (09:06.040)

We like to, if we have an idea,

Peter Woit (09:07.200)

we want to see what's the greatest generality

Lex Fridman (09:09.680)

in which you can talk about it.

Lex Fridman (09:11.140)

So from the point of view of most of the ways geometry

Lex Fridman (09:14.200)

is formulated by mathematicians,

Peter Woit (09:17.040)

it really doesn't matter, it works in any dimension.

Lex Fridman (09:19.080)

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

Peter Woit (09:22.120)

There's no particular, for most of geometry,

Lex Fridman (09:24.860)

there's no particular special thing about four.

Lex Fridman (09:28.240)

But anyway, but what physicists have been trying to do

Lex Fridman (09:33.240)

over the years is try to understand

Peter Woit (09:35.800)

these fundamental theories in a geometrical way

Lex Fridman (09:38.320)

and it's very tempting to kind of just start bringing in

Peter Woit (09:41.960)

extra dimensions and using them to explain the structure.

Lex Fridman (09:46.200)

But typically this attempt kind of founders

Peter Woit (09:51.320)

because you just don't know,

Lex Fridman (09:53.340)

you end up not being able to explain why we only see four.

Peter Woit (09:59.320)

It is nice in the space of physics

Lex Fridman (10:01.800)

that like if you look at Fermat's last theorem,

Peter Woit (10:04.520)

it's much easier to prove that there's no solution

Lex Fridman (10:06.680)

for n equals three than it is for the general case.

Lex Fridman (10:12.120)

And so I guess that's the nice benefit of being a physicist

Lex Fridman (10:16.360)

is you don't have to worry about the general case

Peter Woit (10:18.640)

because we live in a universe with n equals four

Lex Fridman (10:22.160)

in this case.

Peter Woit (10:23.440)

Yeah, physicists are very interested in saying something

Lex Fridman (10:27.880)

about specific examples and I find that interesting

Peter Woit (10:31.440)

when I'm trying to do things in mathematics

Lex Fridman (10:33.760)

and I'm even teaching courses into mathematics students,

Peter Woit (10:36.920)

I find that I'm teaching them in a different way

Lex Fridman (10:40.200)

than most mathematicians because I'm very often

Peter Woit (10:43.880)

very focused on examples on what's kind of the crucial

Lex Fridman (10:47.800)

example that shows how this powerful new mathematical

Peter Woit (10:52.480)

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

Lex Fridman (10:55.680)

And I'm less interested in kind of proving a precise theorem

Peter Woit (11:00.040)

about exactly when it's gonna work

Lex Fridman (11:01.400)

and when it's not gonna work.

Lex Fridman (11:02.440)

Do you usually think about really simple examples,

Lex Fridman (11:05.160)

like both for teaching and when you try to solve

Peter Woit (11:09.080)

a difficult problem, do you construct the simplest

Lex Fridman (11:12.160)

possible examples that captures the fundamentals

Lex Fridman (11:14.360)

of the problem and try to solve it?

Lex Fridman (11:15.720)

Yeah, exactly, that's often a really fruitful way

Peter Woit (11:19.640)

to if you've got some idea to just kind of try

Lex Fridman (11:22.520)

to boil it down to what's the simplest situation

Peter Woit (11:27.000)

in which this kind of thing is gonna happen

Lex Fridman (11:28.680)

and then try to really understand that and understand that

Lex Fridman (11:31.320)

and that is almost always a really good way

Lex Fridman (11:33.520)

to get insight into it.

Lex Fridman (11:34.480)

Do you work with paper and pen or like, for example,

Lex Fridman (11:37.720)

for me coming from the programming side,

Peter Woit (11:41.560)

if I look at a model, if I look at some kind

Lex Fridman (11:43.880)

of mathematical object, I like to mess around

Peter Woit (11:47.360)

with it sort of numerically.

Lex Fridman (11:49.600)

I just visualize different parts of it,

Peter Woit (11:51.600)

visualize however I can so most of the work

Lex Fridman (11:54.160)

is like when you're on networks, for example,

Peter Woit (11:56.160)

is you try to play with the simplest possible example

Lex Fridman (11:59.360)

and just to build up intuition by any kind of object

Peter Woit (12:04.440)

has a bunch of variables in it and you start

Lex Fridman (12:07.280)

to mess around with them in different ways

Lex Fridman (12:09.040)

and visualize in different ways to start

Lex Fridman (12:10.480)

to build intuition or do you go the Einstein route

Lex Fridman (12:14.720)

and just imagine everything inside your mind

Lex Fridman (12:19.160)

and sort of build thought experiments

Lex Fridman (12:21.200)

and then work purely on paper and pen?

Lex Fridman (12:24.840)

Well, the problem with this kind of stuff

Peter Woit (12:28.120)

I'm interested in is you rarely can kind of,

Lex Fridman (12:31.880)

it's rarely something that is really kind of,

Peter Woit (12:34.780)

or even the simplest example, you can kind of see

Lex Fridman (12:38.600)

what's going on by looking at something happening

Peter Woit (12:40.800)

in three dimensions.

Lex Fridman (12:42.240)

There's generally the structures involved

Peter Woit (12:44.600)

are either they're more abstract

Lex Fridman (12:47.960)

or if you try to kind of embed them in some kind of space

Lex Fridman (12:50.720)

and where you could manipulate them

Lex Fridman (12:53.800)

in some kind of geometrical way,

Peter Woit (12:55.200)

it's gonna be a much higher dimensional space.

Lex Fridman (12:57.320)

So even simple examples,

Peter Woit (13:00.080)

the embedding them into three dimensional space,

Lex Fridman (13:02.080)

you're losing a lot.

Peter Woit (13:03.040)

Yeah, but to capture what you're trying to understand

Lex Fridman (13:06.960)

about them, you have to go to four or more dimensions.

Lex Fridman (13:09.720)

So it starts to get to be hard to,

Lex Fridman (13:12.000)

I mean, you can train yourself to try it as much

Peter Woit (13:14.680)

as to kind of think about things in your mind

Lex Fridman (13:18.200)

and I often use pad and paper

Lex Fridman (13:21.000)

and often if I'm in my office, I have to use the blackboard

Lex Fridman (13:25.480)

and you are kind of drawing things

Lex Fridman (13:26.920)

but they're really kind of more abstract representations

Lex Fridman (13:29.600)

of how things are supposed to fit together

Lex Fridman (13:32.560)

and they're not really, unfortunately,

Lex Fridman (13:35.240)

not just kind of really living in three dimensions

Peter Woit (13:37.640)

where you can.

Lex Fridman (13:39.200)

Are we supposed to be sad or excited

Peter Woit (13:41.620)

by the fact that our human minds

Lex Fridman (13:43.160)

can't fully comprehend the kind of mathematics

Lex Fridman (13:45.040)

you're talking about?

Lex Fridman (13:46.000)

I mean, what do we make of that?

Peter Woit (13:48.760)

I mean, to me, that makes you quite sad.

Lex Fridman (13:50.740)

It makes it seem like there's a giant mystery out there

Peter Woit (13:53.960)

that we'll never truly get to experience directly.

Lex Fridman (13:58.320)

It is kind of sad how difficult this is.

Peter Woit (14:01.720)

I mean, or I would put it a different way

Lex Fridman (14:03.680)

that most questions that people have

Peter Woit (14:06.600)

about this kind of thing,

Lex Fridman (14:08.640)

you can give them a really true answer

Lex Fridman (14:12.240)

and really understand it

Lex Fridman (14:13.080)

but the problem is one more of time.

Peter Woit (14:16.580)

It's like, yes, I could explain to you how this works

Lex Fridman (14:20.360)

but you'd have to be willing to sit down with me

Lex Fridman (14:23.040)

and work at this repeatedly for hours and days and weeks

Lex Fridman (14:28.000)

and it's just gonna take that long for your mind

Peter Woit (14:31.540)

to really wrap itself around what's going on

Lex Fridman (14:34.360)

and so that does make things inaccessible which is sad

Lex Fridman (14:40.560)

but it's just kind of part of life

Lex Fridman (14:43.000)

that we all have a limited amount of time

Lex Fridman (14:45.000)

and we have to decide what we're gonna spend our time doing.

Lex Fridman (14:49.760)

Speaking of a limited amount of time,

Peter Woit (14:52.280)

we only have a few hours, maybe a few days together

Lex Fridman (14:55.640)

here on this podcast.

Peter Woit (14:57.760)

Let me ask you the question of amongst many of the ideas

Lex Fridman (15:02.320)

that you work on in mathematics and physics,

Peter Woit (15:05.280)

which is the most beautiful idea

Lex Fridman (15:07.560)

or one of the most beautiful ideas, maybe a surprising idea

Lex Fridman (15:11.200)

and once again, unfortunately, the way life works,

Lex Fridman (15:13.960)

we only have a limited time together

Peter Woit (15:15.680)

to try to convey such an idea.

Lex Fridman (15:18.440)

Okay, well, actually, let me just tell you something which

Peter Woit (15:22.520)

I'm tempted to kind of start trying to explain

Lex Fridman (15:25.260)

what I think is this most powerful idea

Peter Woit (15:26.980)

that brings together math and physics,

Lex Fridman (15:28.600)

ideas about groups and representations

Lex Fridman (15:31.060)

and how it fits in quantum mechanics

Lex Fridman (15:33.200)

but in some sense, I wrote a whole textbook about that

Lex Fridman (15:35.560)

and I don't think we really have time

Lex Fridman (15:37.440)

to get very far into it so.

Peter Woit (15:39.080)

Well, can I actually, on a small tangent,

Lex Fridman (15:41.320)

you did write a paper towards a grant unified theory

Peter Woit (15:43.600)

mathematics and physics, maybe you could step there first,

Lex Fridman (15:47.840)

what is the key idea in that paper?

Peter Woit (15:49.520)

Well, I think we've kind of gone over that.

Lex Fridman (15:51.480)

I think that the key idea is what we were talking about

Peter Woit (15:53.560)

earlier that just kind of a claim that if you look

Lex Fridman (15:58.360)

and see what have been successful ideas in unification

Peter Woit (16:01.400)

in physics and over the last 50 years or so

Lex Fridman (16:05.160)

and what's been happening in mathematics

Lex Fridman (16:07.760)

and the kind of thing that Frankel's book is about

Lex Fridman (16:10.800)

that these are very much the same kind of mathematics

Lex Fridman (16:13.000)

and so it's kind of an argument that there really is,

Lex Fridman (16:16.420)

you shouldn't be looking to unify just math

Peter Woit (16:19.720)

or just fundamental physics but taking inspiration

Lex Fridman (16:23.140)

for looking for new ideas in fundamental physics

Peter Woit (16:25.560)

that they are gonna be in the same direction

Lex Fridman (16:27.380)

of getting deeper into mathematics

Lex Fridman (16:30.200)

and looking for more inspiration in mathematics

Lex Fridman (16:33.280)

from these successful ideas about fundamental physics.

Peter Woit (16:37.320)

Could you put words to sort of the disciplines

Lex Fridman (16:39.480)

we're trying to unify?

Lex Fridman (16:40.400)

So you said number theory, are we literally talking

Lex Fridman (16:42.920)

about all the major fields of mathematics?

Lex Fridman (16:45.040)

So it's like the number theory, geometry,

Lex Fridman (16:48.280)

so the differential geometry, topology.

Peter Woit (16:51.040)

Yeah, so the, I mean, one name for this

Lex Fridman (16:55.400)

that this is acquired in mathematics

Peter Woit (16:57.600)

is the so called Langlands program

Lex Fridman (16:59.760)

and so this started out in mathematics.

Peter Woit (17:01.960)

It's that Robert Langlands kind of realized

Lex Fridman (17:05.120)

that a lot of what people were doing

Lex Fridman (17:07.480)

and that was starting to be really successful

Lex Fridman (17:11.080)

in number theory in the 60s

Lex Fridman (17:13.600)

and so that this actually was,

Lex Fridman (17:18.960)

anyway, that this could be thought of

Peter Woit (17:21.160)

in terms of these ideas about symmetry

Lex Fridman (17:24.120)

and groups and representations

Lex Fridman (17:26.100)

and in a way that was also close

Lex Fridman (17:29.600)

to some ideas about geometry

Lex Fridman (17:32.020)

and then more later on in the 80s, 90s,

Lex Fridman (17:35.200)

there was something called geometric Langlands

Peter Woit (17:38.120)

that people realize that you could take

Lex Fridman (17:40.500)

what people have been doing in number theory in Langlands

Lex Fridman (17:43.120)

and get rid, just forget about the number theory

Lex Fridman (17:45.560)

and ask what is this telling you about geometry

Lex Fridman (17:48.000)

and you get a whole, some new insights

Lex Fridman (17:49.960)

into certain kinds of geometry that way.

Lex Fridman (17:52.360)

So it's, anyway, that's kind of the name

Lex Fridman (17:54.860)

for this area is Langlands and geometric Langlands

Lex Fridman (17:58.080)

and just recently in the last few months,

Lex Fridman (17:59.680)

there's been, there's kind of really major paper

Peter Woit (18:02.760)

that appeared by Peter Schultze and Laurent Farg

Lex Fridman (18:06.660)

where they made some serious advance

Peter Woit (18:11.040)

to try to understand very much kind of a local problem

Lex Fridman (18:16.000)

of what happens in number theory

Peter Woit (18:17.960)

near a certain prime number

Lex Fridman (18:19.760)

and they turned this into a problem

Peter Woit (18:22.060)

of exactly the kind that geometric Langlands people

Lex Fridman (18:26.040)

had been doing, this kind of pure geometry problem

Lex Fridman (18:28.880)

and they found by generalizing mathematics,

Lex Fridman (18:32.360)

they could actually reformulate it in that way

Lex Fridman (18:34.280)

and it worked perfectly well.

Lex Fridman (18:36.680)

One of the things that makes me sad is I'm a pretty

Lex Fridman (18:42.760)

knowledgeable person and then, what is it?

Lex Fridman (18:46.440)

At least I'm in the neighborhood

Lex Fridman (18:48.280)

like theoretical computer science, right?

Lex Fridman (18:50.480)

And it's still way out of my reach

Lex Fridman (18:52.320)

and so many people talk about like Langlands, for example,

Lex Fridman (18:54.960)

is one of the most brilliant people in mathematics

Lex Fridman (18:57.640)

and just really admire his work

Lex Fridman (18:59.960)

and I can't, it's like almost I can't hear the music

Peter Woit (19:03.720)

that he composed and it makes me sad.

Lex Fridman (19:05.820)

Yeah, well, I mean, I think unfortunately,

Peter Woit (19:09.000)

it's not just you, it's I think even most mathematicians

Lex Fridman (19:13.200)

have no, really don't actually understand

Lex Fridman (19:15.080)

what this is about.

Lex Fridman (19:15.920)

I mean, the group of people who really understand

Peter Woit (19:19.400)

all these ideas and so for instance,

Lex Fridman (19:21.040)

this paper of Schultz and Farg that I was talking about,

Peter Woit (19:24.040)

the number of people who really actually understand

Lex Fridman (19:26.320)

how that works is anyway, very, very small

Lex Fridman (19:31.000)

and so I think even you find if you talk to mathematicians

Lex Fridman (19:35.200)

and physicists, even they will often feel that,

Peter Woit (19:38.000)

there's this really interesting sounding stuff going on

Lex Fridman (19:40.320)

and which I should be able to understand,

Peter Woit (19:42.840)

it's kind of in my own field, I have a PhD in

Lex Fridman (19:44.960)

but it still seems pretty clearly far beyond me right now.

Peter Woit (19:49.780)

Well, if we can step into the back to the question

Lex Fridman (19:52.640)

of beauty, is there an idea that maybe

Peter Woit (19:56.320)

is a little bit smaller that you find beautiful

Lex Fridman (19:59.560)

in the space of mathematics or physics?

Peter Woit (1:00:00.840)

in the space of machine learning,

Lex Fridman (1:00:02.680)

there was a time when they were extremely popular.

Peter Woit (1:00:05.480)

They became much, much less popular

Lex Fridman (1:00:07.160)

to a point where if you mentioned neural networks,

Peter Woit (1:00:09.000)

you're getting no funding

Lex Fridman (1:00:10.440)

and you're not going to be respected at conferences.

Lex Fridman (1:00:13.300)

And then once again,

Lex Fridman (1:00:15.440)

neural networks became all the rage

Peter Woit (1:00:18.480)

about 10, 15 years ago.

Lex Fridman (1:00:20.720)

And as it goes up and down

Lex Fridman (1:00:22.040)

and a lot of people would argue

Lex Fridman (1:00:23.640)

that using terminology like machine learning

Lex Fridman (1:00:26.700)

and deep learning is often misused over general,

Lex Fridman (1:00:33.760)

everything that works is deep learning,

Peter Woit (1:00:35.200)

everything that doesn't, isn't something like that.

Lex Fridman (1:00:38.280)

That's just the way,

Peter Woit (1:00:40.080)

again, we're back to sociological things,

Lex Fridman (1:00:42.960)

but I guess what I'm trying to get at is

Peter Woit (1:00:45.320)

if we leave the sociological mess aside,

Lex Fridman (1:00:50.540)

do we throw out the baby with the bathwater?

Peter Woit (1:00:53.140)

Is there some, besides the side effects of nice ideas

Lex Fridman (1:00:57.160)

from the Ed Wittons of the world,

Peter Woit (1:00:59.220)

is there some core truths there that we should stick by

Lex Fridman (1:01:04.300)

in the full beautiful mess of a space

Peter Woit (1:01:08.260)

that we call string theory,

Lex Fridman (1:01:09.640)

that people call string theory?

Peter Woit (1:01:11.440)

You're right, it is kind of a common problem

Lex Fridman (1:01:14.360)

that how what you call some field changes and evolves

Lex Fridman (1:01:19.520)

and in interesting ways as the field changes.

Lex Fridman (1:01:22.760)

But I mean, I guess what I would argue

Peter Woit (1:01:27.760)

is the initial understanding of string theory

Lex Fridman (1:01:30.480)

that was quite specific,

Peter Woit (1:01:31.640)

we're talking about a specific idea,

Lex Fridman (1:01:33.200)

10 dimensional super strings

Peter Woit (1:01:34.920)

compactified to six dimensions.

Lex Fridman (1:01:36.880)

That to my mind, the really bad thing has happened

Peter Woit (1:01:41.280)

to the subject is that it's hard to get people to admit,

Lex Fridman (1:01:45.840)

at least publicly, that that was a failure,

Peter Woit (1:01:48.160)

that this really didn't work.

Lex Fridman (1:01:49.800)

And so de facto, what people do is people stop doing that

Lex Fridman (1:01:53.280)

and they start doing more interesting things,

Lex Fridman (1:01:55.440)

but they keep talking to the public about string theory

Lex Fridman (1:02:00.960)

and referring back to that idea

Lex Fridman (1:02:03.280)

and using that as kind of the starting point

Lex Fridman (1:02:05.360)

and as kind of the place where the whole tribe starts

Lex Fridman (1:02:11.760)

and everything else comes from.

Lex Fridman (1:02:13.320)

So the problem with this is that having as your initial name

Lex Fridman (1:02:17.960)

and what everything points back to,

Peter Woit (1:02:20.480)

something which really didn't work out,

Lex Fridman (1:02:25.560)

it kind of makes everybody, it makes everything,

Peter Woit (1:02:28.280)

you've created this potentially very, very interesting field

Lex Fridman (1:02:31.040)

with interesting things happening,

Lex Fridman (1:02:32.080)

but people in graduate school take courses

Lex Fridman (1:02:37.040)

on string theory and everything kind of,

Lex Fridman (1:02:38.840)

and this is what you tell the public

Lex Fridman (1:02:40.160)

in which you're continually pointing back.

Lex Fridman (1:02:41.680)

So you're continually pointing back to this idea

Lex Fridman (1:02:43.520)

which never worked out as your guiding inspiration.

Lex Fridman (1:02:48.560)

And it really kind of deforms your whole way

Lex Fridman (1:02:51.600)

of your hopes of making progress.

Lex Fridman (1:02:54.120)

And that's, to me, I think the kind of worst thing

Lex Fridman (1:02:57.640)

that's happened in this field.

Peter Woit (1:02:59.200)

Okay, sure, so there's a lack of transparency, sort of authenticity

Lex Fridman (1:03:02.560)

about communicating the things that failed in the past.

Lex Fridman (1:03:07.120)

And so you don't have a clear picture of like firm ground

Lex Fridman (1:03:10.920)

that you're standing on.

Lex Fridman (1:03:12.080)

But again, those are sociological things.

Lex Fridman (1:03:13.840)

And there's a bunch of questions I want to ask you.

Lex Fridman (1:03:18.720)

So one, what's your intuition about why the original idea failed?

Lex Fridman (1:03:26.720)

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

Peter Woit (1:03:32.480)

I mean, the initial idea was, as I try to explain it,

Lex Fridman (1:03:35.400)

it was quite seductive in that you could see why Whitten

Lex Fridman (1:03:39.000)

and others got excited by it.

Lex Fridman (1:03:40.440)

It was, you know, at the time it looked like there were only

Peter Woit (1:03:45.000)

a few of these possible clobby owls that would work.

Lex Fridman (1:03:47.600)

And it looked like, okay, we just have to understand

Peter Woit (1:03:50.000)

this very specific model and these very specific

Lex Fridman (1:03:53.160)

six dimensional spaces, and we're going to get everything.

Lex Fridman (1:03:55.760)

And so it was a very seductive idea, but it just, you know,

Lex Fridman (1:03:59.240)

as people learned, worked more and more about it,

Peter Woit (1:04:03.120)

it just didn't, they just kind of realized that there are just

Lex Fridman (1:04:07.280)

more and more things you can do with these six dimensions

Lex Fridman (1:04:09.240)

and you can't, and this is just not going to work.

Lex Fridman (1:04:12.720)

Meaning like, it's, I mean, what was the failure mode here?

Peter Woit (1:04:21.240)

Is it, you could just have an infinite number of possibilities

Lex Fridman (1:04:24.200)

that you could do so you can come up with any theory you want,

Peter Woit (1:04:27.160)

you can fit quantum mechanics, you can explain gravity,

Lex Fridman (1:04:30.720)

you can explain anything you want with it.

Lex Fridman (1:04:32.880)

Is that the basic failure mode?

Lex Fridman (1:04:34.280)

Yeah, so it's a failure mode of kind of that this idea

Peter Woit (1:04:37.120)

ended up being kind of being essentially empty,

Lex Fridman (1:04:39.920)

that it just doesn't, ends up not telling you anything

Peter Woit (1:04:43.240)

because it's consistent with just about anything.

Lex Fridman (1:04:47.280)

And so, I mean, there's a complex, if you try and talk

Peter Woit (1:04:50.760)

with string theorists about this now, I mean,

Lex Fridman (1:04:52.280)

there's an argument, there's a long argument over this

Peter Woit (1:04:54.720)

about whether, oh no, no, no, maybe there still are

Lex Fridman (1:04:58.960)

constraints coming out of this idea or not.

Peter Woit (1:05:01.680)

Or maybe we live in a multiverse and everything is true

Lex Fridman (1:05:06.160)

anyway, so you can, there are various ways you can kind of,

Peter Woit (1:05:10.200)

that string theorists have kind of react to this kind of

Lex Fridman (1:05:12.520)

argument that I'm making, but I try to hold onto it.

Lex Fridman (1:05:17.080)

What about experimental validation?

Lex Fridman (1:05:18.880)

Is that a fair standard to hold before a theory

Peter Woit (1:05:26.040)

of everything that's trying to unify

Lex Fridman (1:05:27.360)

quantum mechanics and gravity?

Peter Woit (1:05:28.960)

Yeah, I mean, ultimately, to be really convinced

Lex Fridman (1:05:32.520)

that some new idea about unification really works,

Peter Woit (1:05:36.680)

you need some kind of, you need to look at the real world

Lex Fridman (1:05:39.720)

and see that this is telling you something true about it.

Peter Woit (1:05:44.200)

I mean, either telling you that if you do some experiment

Lex Fridman (1:05:49.840)

and go out and do it, you'll get some unexpected result

Lex Fridman (1:05:52.440)

and that's the kind of gold standard, or it may be just that

Lex Fridman (1:05:57.240)

like all those numbers that are,

Peter Woit (1:05:58.840)

we don't know how to explain,

Lex Fridman (1:06:00.060)

it will show you how to calculate them.

Peter Woit (1:06:02.200)

I mean, it can be various kinds of experimental validation,

Lex Fridman (1:06:05.260)

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

Lex Fridman (1:06:08.640)

How tough is this, do you think, for a theory of everything,

Lex Fridman (1:06:11.240)

not just string theory, for something that unifies

Peter Woit (1:06:13.880)

gravity and quantum mechanics,

Lex Fridman (1:06:14.960)

so the very big and the very small?

Peter Woit (1:06:17.520)

Is this, let me ask you one way,

Lex Fridman (1:06:20.200)

is it a physics problem, a math problem,

Lex Fridman (1:06:25.520)

or an engineering problem?

Lex Fridman (1:06:27.920)

My guess is it's a combination of a physics

Lex Fridman (1:06:30.420)

and a math problem that you really need.

Lex Fridman (1:06:33.820)

It's not really engineering, it's not like there's some kind

Peter Woit (1:06:36.520)

of well defined thing you can write down

Lex Fridman (1:06:39.400)

and we just don't have enough computer power

Peter Woit (1:06:41.540)

to do the calculation.

Lex Fridman (1:06:43.240)

That's not the kind of problem it is at all.

Lex Fridman (1:06:46.320)

But the question is, what mathematical tools you need

Lex Fridman (1:06:49.400)

to properly formulate the problem is unclear.

Lex Fridman (1:06:53.440)

So one reasonable conjecture is the way,

Lex Fridman (1:06:55.960)

the reason that we haven't had any success yet

Peter Woit (1:06:58.760)

is just that we're missing,

Lex Fridman (1:07:01.600)

either we're missing certain physical ideas

Peter Woit (1:07:04.240)

or we're missing certain mathematical tools,

Lex Fridman (1:07:06.260)

which there are some combination of them,

Peter Woit (1:07:08.440)

which we need to kind of properly formulate the problem

Lex Fridman (1:07:12.740)

and see that it has a solution

Peter Woit (1:07:15.760)

that looks like the real world.

Lex Fridman (1:07:17.280)

But those you need, I guess you don't,

Lex Fridman (1:07:19.400)

but there's a sense that you need both gravity,

Lex Fridman (1:07:24.600)

like all the laws of physics to be operating

Peter Woit (1:07:27.360)

on the same level.

Lex Fridman (1:07:28.440)

So it feels like you need an object like a black hole

Peter Woit (1:07:31.580)

or something like that in order to make predictions about.

Lex Fridman (1:07:38.100)

Otherwise, you're always making predictions

Peter Woit (1:07:40.360)

about this joint phenomena or can you do that

Lex Fridman (1:07:45.280)

as long as the theory is consistent

Lex Fridman (1:07:46.960)

and doesn't have special cases for each of the phenomena?

Lex Fridman (1:07:48.840)

Well, your theory should, I mean,

Peter Woit (1:07:50.600)

if your theory is gonna include gravity,

Lex Fridman (1:07:52.160)

our current understanding of gravity

Peter Woit (1:07:53.520)

is that you should have,

Lex Fridman (1:07:56.340)

there should be black hole states in it.

Peter Woit (1:07:57.840)

You should be able to describe black holes in this theory.

Lex Fridman (1:08:00.040)

And just one aspect that people have concentrated a lot on

Peter Woit (1:08:04.320)

is just this kind of questions about

Lex Fridman (1:08:06.640)

if your theory includes black holes like it's supposed to

Lex Fridman (1:08:09.880)

and it includes quantum mechanics,

Lex Fridman (1:08:11.840)

then there's certain kinds of paradoxes which come up.

Lex Fridman (1:08:13.880)

And so that's been a huge focus of kind of

Lex Fridman (1:08:16.120)

quantum gravity work has been just those paradoxes.

Lex Fridman (1:08:20.240)

So stepping outside of string theory,

Lex Fridman (1:08:23.240)

can you just say first at a high level,

Lex Fridman (1:08:26.520)

what is the theory of everything?

Lex Fridman (1:08:28.560)

What is the theory of everything seek to accomplish?

Peter Woit (1:08:32.200)

Well, I mean, this is very much a kind of reductionist

Lex Fridman (1:08:34.760)

point of view in the sense that, so it's not a theory.

Peter Woit (1:08:38.080)

This is not gonna explain to you anything.

Lex Fridman (1:08:42.320)

It doesn't really, this kind of theory,

Peter Woit (1:08:44.520)

this kind of theory of everything we're talking about

Lex Fridman (1:08:46.260)

doesn't say anything interesting,

Peter Woit (1:08:48.320)

particularly about like macroscopic objects,

Lex Fridman (1:08:50.240)

about what the weather is gonna be tomorrow,

Peter Woit (1:08:52.320)

or things are happening at this scale.

Lex Fridman (1:08:54.800)

But just what we've discovered is that

Peter Woit (1:08:57.240)

as you look at the universe that kind of,

Lex Fridman (1:09:02.000)

if you kind of start, you can start breaking it apart

Peter Woit (1:09:05.640)

into, and you end up with some fairly simple pieces,

Lex Fridman (1:09:08.440)

quanta, if you like, and which are doing,

Peter Woit (1:09:11.160)

which are interacting in some fairly simple way.

Lex Fridman (1:09:14.480)

And it's, so what we mean by theory of everything is

Peter Woit (1:09:19.800)

a theory that describes all the object,

Lex Fridman (1:09:24.160)

all the correct objects you need to describe

Peter Woit (1:09:26.840)

what's happening in the world and describes how

Lex Fridman (1:09:29.080)

they're interacting with each other

Peter Woit (1:09:30.160)

at our most fundamental level.

Lex Fridman (1:09:31.880)

How you get from that theory to describing some macroscopic,

Peter Woit (1:09:36.800)

incredibly complicated thing is,

Lex Fridman (1:09:38.840)

there that becomes, again, more of an engineering problem

Lex Fridman (1:09:41.160)

and you may need machine learning,

Lex Fridman (1:09:42.640)

or you may, you know, a lot of very different things

Peter Woit (1:09:44.740)

to do it, but.

Lex Fridman (1:09:45.580)

Well, I don't even think it's just engineering.

Peter Woit (1:09:48.760)

It's also science.

Lex Fridman (1:09:50.400)

One thing that I find kind of interesting

Peter Woit (1:09:55.200)

talking to physicists is a little bit, there's a,

Lex Fridman (1:10:05.300)

a little bit of hubris.

Peter Woit (1:10:07.220)

Some of the most brilliant people I know are physicists,

Lex Fridman (1:10:09.740)

both philosophy and just in terms of mathematics,

Peter Woit (1:10:12.340)

in terms of understanding the world.

Lex Fridman (1:10:14.300)

But there's a kind of either hubris or what would I call it?

Peter Woit (1:10:19.500)

Like a confidence that if we have a theory of everything,

Lex Fridman (1:10:22.740)

we will understand everything.

Peter Woit (1:10:24.500)

Like this is the deepest thing to understand.

Lex Fridman (1:10:26.740)

And I would say, and like the rest is details, right?

Peter Woit (1:10:29.820)

That's the old Rutherford thing.

Lex Fridman (1:10:33.140)

But to me, there's like, this is like a cake or something.

Peter Woit (1:10:37.940)

There's layers to this thing

Lex Fridman (1:10:39.140)

and each one has a theory of everything.

Peter Woit (1:10:42.020)

Like at every level from biology,

Lex Fridman (1:10:46.580)

like how life originates, that itself,

Peter Woit (1:10:50.860)

like complex systems.

Lex Fridman (1:10:52.700)

Like that in itself is like this gigantic thing

Peter Woit (1:10:56.860)

that requires a theory of everything.

Lex Fridman (1:10:58.860)

And then there's the, in the space of humans,

Peter Woit (1:11:01.680)

psychology, like intelligence, collective intelligence,

Lex Fridman (1:11:04.700)

the way it emerges among species,

Peter Woit (1:11:07.180)

that feels like a complex system

Lex Fridman (1:11:09.260)

that requires its own theory of everything.

Peter Woit (1:11:11.580)

On top of that is things like in the computing space,

Lex Fridman (1:11:15.460)

artificial intelligence systems,

Peter Woit (1:11:16.820)

like that feels like it needs a theory of everything.

Lex Fridman (1:11:19.460)

And it's almost like once we solve,

Peter Woit (1:11:24.780)

once we come up with a theory of everything

Lex Fridman (1:11:26.660)

that explains the basic laws of physics

Peter Woit (1:11:28.500)

that gave us the universe,

Lex Fridman (1:11:30.320)

even stuff that's super complex,

Peter Woit (1:11:32.620)

like how the universe might be able to originate,

Lex Fridman (1:11:37.120)

even explaining something that you're not a big fan of,

Peter Woit (1:11:39.460)

like multiverses or stuff

Lex Fridman (1:11:40.940)

that we don't have any evidence of yet.

Peter Woit (1:11:42.900)

Still, we won't be able to have a strong explanation

Lex Fridman (1:11:47.580)

of why food tastes delicious.

Peter Woit (1:11:52.700)

Yeah, I know.

Lex Fridman (1:11:53.660)

No, anyway, yeah, I agree completely.

Peter Woit (1:11:55.620)

I mean, there is something kind of completely wrong

Lex Fridman (1:11:58.700)

with this terminology of theory of everything.

Peter Woit (1:12:00.860)

It's not, it's really in some sense a very bad term,

Lex Fridman (1:12:04.100)

very hubristic and bad terminology,

Peter Woit (1:12:06.420)

because it's not, this is explaining,

Lex Fridman (1:12:11.020)

this is a purely kind of reductionist point of view

Peter Woit (1:12:13.160)

that you're trying to understand

Lex Fridman (1:12:15.260)

a certain very specific kind of things,

Peter Woit (1:12:17.900)

which in principle, other things emerge from,

Lex Fridman (1:12:23.560)

but to actually understand how anything emerges from this

Peter Woit (1:12:27.660)

is, it can't be understood in terms of

Lex Fridman (1:12:31.740)

this underlying fundamental theory is gonna be hopeless

Peter Woit (1:12:35.740)

in terms of kind of telling you what about this,

Lex Fridman (1:12:39.620)

this various emergent behavior.

Lex Fridman (1:12:40.980)

And as you go to different levels of explanation,

Lex Fridman (1:12:43.060)

you're gonna need to develop new,

Peter Woit (1:12:44.660)

different, completely different ideas,

Lex Fridman (1:12:46.100)

completely different ways of thinking.

Lex Fridman (1:12:47.380)

And I guess there's a famous kind of Phil Anderson's slogan

Lex Fridman (1:12:52.500)

is that, you know, more is different.

Lex Fridman (1:12:54.380)

And so it's just, even once you understand how,

Lex Fridman (1:12:59.300)

what a couple of things,

Peter Woit (1:13:00.580)

if you have a collection of stuff

Lex Fridman (1:13:01.940)

and you understand perfectly well

Lex Fridman (1:13:03.220)

how each thing is interacting with the others,

Lex Fridman (1:13:07.320)

what the whole thing is gonna do

Peter Woit (1:13:08.600)

is just a completely different problem.

Lex Fridman (1:13:10.160)

It's just not, and you need completely different ways

Peter Woit (1:13:12.260)

of thinking about it.

Lex Fridman (1:13:13.520)

What do you think about this?

Peter Woit (1:13:15.100)

I got to ask you at a few different attempts

Lex Fridman (1:13:17.420)

that a theory of everything, especially recently.

Lex Fridman (1:13:20.060)

So I've been for many years,

Lex Fridman (1:13:23.240)

a big fan of cellular automata of complex systems.

Lex Fridman (1:13:25.620)

And obviously because of that,

Lex Fridman (1:13:28.140)

a fan of Stephen Wolfram's work in that space,

Lex Fridman (1:13:31.500)

but he's recently been talking about a theory of everything

Lex Fridman (1:13:35.180)

through his physics project, essentially.

Lex Fridman (1:13:38.100)

What do you think about this kind of discreet

Lex Fridman (1:13:40.340)

theory of everything like from simple rules

Lex Fridman (1:13:45.140)

and simple objects on the hypergraphs

Lex Fridman (1:13:47.660)

emerges all of our reality where time and space are emergent.

Peter Woit (1:13:51.500)

Basically everything we see around us is emergent.

Lex Fridman (1:13:53.980)

Yeah, I have to say, unfortunately,

Peter Woit (1:13:55.420)

I've kind of pretty much zero sympathy for that.

Lex Fridman (1:13:58.440)

I mean, I don't, I spent a little time looking at it

Lex Fridman (1:14:01.660)

and I just don't see, it doesn't seem to me to get anywhere.

Lex Fridman (1:14:04.940)

And it really is just really, really doesn't agree at all

Peter Woit (1:14:08.780)

with what I'm seeing,

Lex Fridman (1:14:10.900)

this kind of unification of math and physics

Peter Woit (1:14:13.180)

that I'm kind of talking about around certain kinds

Lex Fridman (1:14:15.440)

of very deep ideas about geometry and stuff.

Peter Woit (1:14:17.860)

This, if you want to believe that your things

Lex Fridman (1:14:22.400)

are really coming out of cellular automata

Peter Woit (1:14:25.140)

at the most fundamental level,

Lex Fridman (1:14:26.780)

you have to believe that everything that I've seen

Peter Woit (1:14:30.480)

my whole career and as beautiful, powerful ideas,

Lex Fridman (1:14:34.340)

that that's all just kind of a mirage,

Peter Woit (1:14:35.740)

which just kind of randomly is emerging

Lex Fridman (1:14:38.200)

from these more basic, very, very simple minded things.

Lex Fridman (1:14:41.480)

And you have to give me some serious evidence for that

Lex Fridman (1:14:44.980)

and I'm seeing nothing.

Lex Fridman (1:14:46.240)

So Mirage, you don't think there could be a consistency

Lex Fridman (1:14:50.420)

where things like quantum mechanics could emerge

Peter Woit (1:14:54.500)

from much, much, much smaller, discreet,

Lex Fridman (1:14:58.480)

like computational type systems.

Peter Woit (1:15:00.100)

I think from the point of view of certain mathematical

Lex Fridman (1:15:02.540)

point of view, quantum mechanics is already mathematically

Peter Woit (1:15:06.400)

as simple as it gets.

Lex Fridman (1:15:07.420)

It really is a story about really the fundamental objects

Peter Woit (1:15:13.620)

that you work within when you write down a quantum theory

Lex Fridman (1:15:16.420)

are in some form point of view,

Peter Woit (1:15:18.500)

precisely the fundamental objects

Lex Fridman (1:15:21.220)

at these deepest levels of mathematics

Peter Woit (1:15:22.900)

that you're working with, they're exactly the same.

Lex Fridman (1:15:25.060)

So, and cellular automata are something completely different

Peter Woit (1:15:28.460)

which don't fit into these structures.

Lex Fridman (1:15:30.000)

And so I just don't see why, anyway,

Peter Woit (1:15:32.540)

I don't see it as a promising thing to do.

Lex Fridman (1:15:37.340)

And then just looking at it and saying,

Lex Fridman (1:15:38.580)

does this go anywhere?

Lex Fridman (1:15:39.480)

Does this solve any problem that I've ever,

Lex Fridman (1:15:42.440)

that I didn't, does this solve any problem of any kind?

Lex Fridman (1:15:45.300)

I just don't see it.

Peter Woit (1:15:46.740)

Yeah, to me, cellular automata and these hypergraphs,

Lex Fridman (1:15:50.580)

I'm not sure solving a problem is even the standard

Peter Woit (1:15:55.280)

to apply here at this moment.

Lex Fridman (1:15:57.700)

To me, the fascinating thing is that the question it asks

Peter Woit (1:16:00.580)

have no good answers.

Lex Fridman (1:16:02.020)

So there's not good math explaining,

Peter Woit (1:16:04.580)

forget the physics of it,

Lex Fridman (1:16:06.020)

math explaining the behavior of complex systems.

Lex Fridman (1:16:09.180)

And that to me is both exciting and paralyzing.

Lex Fridman (1:16:12.340)

Like we're at the very early days of understanding

Lex Fridman (1:16:17.100)

how complicated and fascinating things emerge

Lex Fridman (1:16:19.980)

from simple rules.

Peter Woit (1:16:21.300)

Yeah, and I agree.

Lex Fridman (1:16:22.740)

I think that is a truly great problem.

Lex Fridman (1:16:25.460)

And depending where it goes, it may be,

Lex Fridman (1:16:30.940)

it may start to develop some kind of connections

Peter Woit (1:16:33.600)

to the things that I've kind of found more fruitful

Lex Fridman (1:16:36.740)

and hard to know.

Peter Woit (1:16:38.740)

It just, I think a lot of that area,

Lex Fridman (1:16:41.380)

I kind of strongly feel I best not say too much about it

Peter Woit (1:16:45.740)

because I just, I don't know too much about it.

Lex Fridman (1:16:48.220)

And again, we're back to this original problem

Peter Woit (1:16:51.580)

that your time in life is limited.

Lex Fridman (1:16:54.340)

You have to figure out what you're gonna spend

Peter Woit (1:16:55.780)

your time thinking about.

Lex Fridman (1:16:56.820)

And that's something I've just never seen enough

Peter Woit (1:16:59.060)

to convince me to spend more time thinking about.

Lex Fridman (1:17:01.460)

Well, also timing, it's not just that our time is limited,

Lex Fridman (1:17:03.940)

but the timing of the kind of things you think about.

Lex Fridman (1:17:07.180)

There's some aspect to cellular automata,

Peter Woit (1:17:09.740)

these kinds of objects that it feels like

Lex Fridman (1:17:12.820)

we're very many years away from having big breakthroughs on.

Lex Fridman (1:17:18.260)

And so it's like, you have to pick the problems

Lex Fridman (1:17:20.420)

that are solvable today.

Peter Woit (1:17:21.780)

In fact, my intuition, again, perhaps biased,

Lex Fridman (1:17:26.400)

is it feels like the kind of systems that,

Peter Woit (1:17:30.180)

complex systems that cellular automata are,

Lex Fridman (1:17:32.840)

would not be solved by human brains.

Peter Woit (1:17:36.260)

It feels like something post human

Lex Fridman (1:17:40.300)

that will solve that problem.

Peter Woit (1:17:41.840)

Or like significantly enhanced humans,

Lex Fridman (1:17:45.020)

meaning like using computational tools,

Peter Woit (1:17:47.700)

very powerful computational tools to crack

Lex Fridman (1:17:51.740)

these problems open.

Peter Woit (1:17:54.420)

That's if our approach to science,

Lex Fridman (1:17:58.140)

our ability to understand science, our ability

Peter Woit (1:18:00.420)

to understand physics will become more and more

Lex Fridman (1:18:02.500)

computational, or there'll be a whole field

Peter Woit (1:18:04.660)

that's computational in nature,

Lex Fridman (1:18:06.300)

which currently is not the case.

Peter Woit (1:18:07.740)

Currently, computation is the thing that sort of assists us

Lex Fridman (1:18:12.460)

in understanding science the way we've been doing it

Peter Woit (1:18:15.640)

all along, but if there's a whole new,

Lex Fridman (1:18:17.980)

I mean, we're from a new kind of science, right?

Peter Woit (1:18:20.540)

It's a little bit dramatic, but you know,

Lex Fridman (1:18:23.360)

if computers could do science on their own,

Peter Woit (1:18:28.680)

computational systems, perhaps that's the way

Lex Fridman (1:18:34.600)

they would do the science.

Peter Woit (1:18:35.600)

They would try to understand the cellular automata,

Lex Fridman (1:18:37.760)

and that feels like we're decades away.

Lex Fridman (1:18:39.980)

So perhaps it'll crack open some interesting facets

Lex Fridman (1:18:43.980)

of this physics problem, but it's very far away.

Lex Fridman (1:18:46.320)

So timing is everything.

Lex Fridman (1:18:48.680)

That's perfectly possible, yeah.

Peter Woit (1:18:51.040)

Well, let me ask you then, in the space of geometry,

Lex Fridman (1:18:55.280)

I don't know how well you know Eric Weinstein.

Peter Woit (1:18:57.280)

Oh, quite well, yeah.

Lex Fridman (1:19:00.000)

What are your thoughts about his geometric community

Lex Fridman (1:19:03.600)

and the space of ideas that he's playing with

Lex Fridman (1:19:07.660)

in his proposal for theory of everything?

Peter Woit (1:19:09.800)

Well, I think that he has, he fundamentally has,

Lex Fridman (1:19:14.140)

I think, the same problems that everybody has had

Peter Woit (1:19:17.800)

trying to do this, and there are really versions

Lex Fridman (1:19:20.960)

of the same problem that you try to get unity

Peter Woit (1:19:26.160)

by putting everything into some bigger structure.

Lex Fridman (1:19:28.840)

So he has some other ones that are not so conventional

Peter Woit (1:19:33.460)

that he's trying to work with,

Lex Fridman (1:19:35.040)

but he has the same problem that even if he can,

Peter Woit (1:19:41.480)

if he can get a lot farther in terms of having

Lex Fridman (1:19:43.640)

a really well defined, well understood,

Peter Woit (1:19:45.860)

clear picture of these things he's working with,

Lex Fridman (1:19:50.300)

they're really kind of large geometrical structures

Peter Woit (1:19:53.240)

of many dimensions of many kinds,

Lex Fridman (1:19:55.160)

and I just don't see any way,

Peter Woit (1:19:57.400)

he's gonna have the same problem the string theorists have,

Lex Fridman (1:19:59.520)

how do you get back down to the structures

Peter Woit (1:20:02.680)

of the standard model, and how do you, yeah.

Lex Fridman (1:20:06.860)

So I just, anyway, it's the same,

Lex Fridman (1:20:10.760)

and there's another interesting example

Lex Fridman (1:20:13.320)

of a similar kind of thing is Garrett Leasy's

Peter Woit (1:20:16.040)

theory of everything.

Lex Fridman (1:20:17.400)

Again, there, it's a little bit more specific

Peter Woit (1:20:20.040)

than Eric's, he's working with this E8,

Lex Fridman (1:20:22.520)

but it, again, I think all these things found

Peter Woit (1:20:25.980)

are at the same point, that you don't,

Lex Fridman (1:20:29.480)

you know, you create this unity,

Lex Fridman (1:20:30.760)

but then you have no, you don't actually have a good idea

Lex Fridman (1:20:34.920)

how you're gonna get back to the actual,

Peter Woit (1:20:40.880)

to the objects we've seen, how are you gonna,

Lex Fridman (1:20:42.680)

you create these big symmetries,

Lex Fridman (1:20:43.920)

how are you gonna break them?

Lex Fridman (1:20:45.340)

And, because we don't see those symmetries

Peter Woit (1:20:47.480)

in the real world, and so ultimately,

Lex Fridman (1:20:49.720)

there would need to be a simple process

Peter Woit (1:20:53.840)

for collapsing it to four dimensions.

Lex Fridman (1:20:56.280)

You'd have to explain, well, yeah,

Peter Woit (1:20:58.480)

I forget in his case, but it's not just four dimensions,

Lex Fridman (1:21:01.000)

it's also these structures you see in the standard model,

Peter Woit (1:21:05.400)

there's, you know, there's certain very small

Lex Fridman (1:21:07.600)

dimensional groups of symmetries,

Lex Fridman (1:21:09.160)

so called U1, SU2, and SU3, and the problem with,

Lex Fridman (1:21:13.800)

and this has been a problem since the beginning,

Peter Woit (1:21:15.240)

almost immediately after 1973, about a year later,

Lex Fridman (1:21:18.880)

two years later, people started talking about

Peter Woit (1:21:20.600)

grand unified theories, so you take the U1,

Lex Fridman (1:21:24.280)

the SU2, and the SU3, and you put them together

Peter Woit (1:21:27.120)

into this bigger structure called SU5 or SO10,

Lex Fridman (1:21:31.520)

but then you're stuck with this problem that,

Peter Woit (1:21:33.560)

wait a minute, now how, why does the world not look,

Lex Fridman (1:21:36.440)

why do I not see these SU5 symmetries in the world,

Peter Woit (1:21:40.960)

I only see these, and so, and I think, you know,

Lex Fridman (1:21:45.960)

the kind of thing that Eric, and all of a sudden Garrett,

Lex Fridman (1:21:49.880)

and lots of people who try to do it,

Lex Fridman (1:21:51.000)

they all kind of found her in that same way,

Peter Woit (1:21:55.160)

that they don't have a good answer to that.

Lex Fridman (1:21:58.560)

Are there lessons, ideas to be learned from theories

Lex Fridman (1:22:01.800)

like that, from Garrett Leacy's, from Eric's?

Lex Fridman (1:22:05.360)

I don't know, it depends, I have to confess,

Peter Woit (1:22:07.080)

I haven't looked that closely at Eric's,

Lex Fridman (1:22:11.020)

I mean, he explained this to me personally a few times,

Lex Fridman (1:22:14.240)

and I've looked a bit at his paper, but it's,

Lex Fridman (1:22:17.560)

again, we're back to the problem

Peter Woit (1:22:19.280)

of a limited amount of time in life.

Lex Fridman (1:22:22.360)

Yeah, I mean, it's an interesting effect, right?

Lex Fridman (1:22:26.680)

Why don't more physicists look at it?

Lex Fridman (1:22:33.080)

I mean, I'm in this position that somehow,

Peter Woit (1:22:37.560)

you know,

Lex Fridman (1:22:38.400)

I've, people write me emails, for whatever reason,

Lex Fridman (1:22:45.700)

and I've worked in the space of AI,

Lex Fridman (1:22:47.460)

and so there's a lot of people,

Peter Woit (1:22:49.180)

perhaps AI is even way more accessible than physics,

Lex Fridman (1:22:52.300)

in a certain sense, and so a lot of people write to me

Peter Woit (1:22:54.980)

with different theories about what they have

Lex Fridman (1:22:56.720)

for how to create general intelligence,

Lex Fridman (1:23:00.000)

and it's, again, a little bit of an excuse, I say to myself,

Lex Fridman (1:23:03.380)

like, well, I only have a limited amount of time,

Lex Fridman (1:23:05.420)

so that's why I'm not investigating it,

Lex Fridman (1:23:07.940)

but I wonder if there's ideas out there

Peter Woit (1:23:11.620)

that are still powerful, that are still fascinating,

Lex Fridman (1:23:14.700)

and that I'm missing because I'm dismissing them

Peter Woit (1:23:21.360)

because they're outside of the sort of the usual process

Lex Fridman (1:23:24.740)

of academic research.

Peter Woit (1:23:26.780)

Yeah, well, I mean, the same thing,

Lex Fridman (1:23:28.340)

and pretty much every day in my email,

Peter Woit (1:23:29.940)

there's somebody who's got a theory or everything

Lex Fridman (1:23:32.980)

about why all of what physicists are doing,

Lex Fridman (1:23:35.180)

and perhaps the most disturbing thing I should say

Lex Fridman (1:23:38.940)

about being a critic of string theory

Peter Woit (1:23:41.740)

is that when you realize who your fans are,

Lex Fridman (1:23:45.700)

every day I hear from somebody who says,

Peter Woit (1:23:47.060)

oh, well, since you don't like string theory,

Lex Fridman (1:23:48.620)

you must, of course, agree with me

Peter Woit (1:23:49.980)

that this is the right way to think about everything.

Lex Fridman (1:23:52.260)

Oh, no, oh, no, and most of these are,

Peter Woit (1:23:57.620)

you quickly can see this person doesn't know very much

Lex Fridman (1:24:00.800)

and doesn't know what they're doing,

Lex Fridman (1:24:02.500)

but there's a whole continuum to,

Lex Fridman (1:24:05.100)

people who are quite serious physicists and mathematicians

Peter Woit (1:24:08.060)

who are making a fairly serious attempt

Lex Fridman (1:24:10.380)

to try to do something, like Eric and Eric,

Lex Fridman (1:24:14.620)

and then your problem is you do try to spend more time

Lex Fridman (1:24:21.380)

looking at it and trying to figure out

Lex Fridman (1:24:22.600)

what they're really doing,

Lex Fridman (1:24:23.700)

but then at some point you just realize,

Peter Woit (1:24:26.220)

wait a minute, for me to really, really understand

Lex Fridman (1:24:28.220)

exactly what's going on here would just take time

Peter Woit (1:24:32.340)

I just don't have.

Lex Fridman (1:24:33.620)

Yeah, it takes a long time, which is the nice thing about AI

Peter Woit (1:24:36.940)

is unlike the kind of physics we're talking about,

Lex Fridman (1:24:41.140)

if your idea is good, that should quite naturally lead

Peter Woit (1:24:46.660)

to you being able to build a system that's intelligent.

Lex Fridman (1:24:49.820)

So you don't need to get approval from somebody

Peter Woit (1:24:52.280)

that's saying you have a good idea here.

Lex Fridman (1:24:54.460)

You can just utilize that idea in an engineer system,

Peter Woit (1:24:56.940)

like naturally leads to engineering.

Lex Fridman (1:24:58.860)

With physics here, if you have a perfect theory

Peter Woit (1:25:01.940)

that explains everything, that still doesn't obviously lead

Lex Fridman (1:25:06.060)

one, to scientific experiments that can validate

Peter Woit (1:25:12.020)

that theory, and two, to like trinkets you can build

Lex Fridman (1:25:15.700)

and sell at a store for $5.

Peter Woit (1:25:18.580)

You can't make money off of it.

Lex Fridman (1:25:21.220)

So that makes it much more challenging.

Peter Woit (1:25:25.820)

Well, let me also ask you about something that you found,

Lex Fridman (1:25:28.580)

especially recently appealing,

Peter Woit (1:25:30.540)

which is Roger Penrose's Twister theory.

Lex Fridman (1:25:34.340)

What is it?

Lex Fridman (1:25:35.180)

What kind of questions might it allow us to answer?

Lex Fridman (1:25:37.820)

What will the answers look like?

Peter Woit (1:25:39.900)

It's only in the last couple of years

Lex Fridman (1:25:41.620)

that I really, really kind of come to really,

Peter Woit (1:25:43.380)

I think, to appreciate it and to see how to really,

Lex Fridman (1:25:46.060)

I believe to see how to really do something with it.

Lex Fridman (1:25:48.500)

And I've gotten very excited about that

Lex Fridman (1:25:49.980)

the last year or two.

Peter Woit (1:25:51.220)

I mean, one way of saying one idea of Twister theory

Lex Fridman (1:25:54.820)

is that it's a different way of thinking about

Lex Fridman (1:25:59.080)

what space and time are and about what points

Lex Fridman (1:26:01.660)

in space and time are, which is very interesting

Peter Woit (1:26:05.100)

that it only really works in four dimensions.

Lex Fridman (1:26:07.420)

So four dimensions behaves very, very specially

Peter Woit (1:26:09.700)

unlike other dimensions.

Lex Fridman (1:26:11.180)

And in four dimensions, there is a way of thinking

Peter Woit (1:26:14.500)

about space and time geometry,

Lex Fridman (1:26:17.580)

as well as just thinking about points in space and time.

Peter Woit (1:26:21.280)

You can also think about different objects,

Lex Fridman (1:26:25.140)

these so called twisters.

Lex Fridman (1:26:26.240)

And then when you do that,

Lex Fridman (1:26:27.860)

you end up with a kind of a really interesting insight

Peter Woit (1:26:30.900)

that you can formulate a theory,

Lex Fridman (1:26:35.340)

and you can formulate a very,

Peter Woit (1:26:37.100)

take a standard theory that we formulate

Lex Fridman (1:26:39.420)

in terms of points of space and time,

Lex Fridman (1:26:41.660)

and you can reformulate in this Twister language.

Lex Fridman (1:26:44.460)

And in this Twister language,

Peter Woit (1:26:45.820)

it's the fundamental objects actually are more kind of the,

Lex Fridman (1:26:51.340)

are actually spheres in some sense, kind of the light cone.

Lex Fridman (1:26:54.140)

So maybe one way to say it,

Lex Fridman (1:26:56.900)

which actually I think is really, is quite amazing.

Lex Fridman (1:27:02.100)

If you ask yourself, what do we know about the world?

Lex Fridman (1:27:05.140)

We have this idea that the world out there

Peter Woit (1:27:07.900)

is all these different points and these points of time.

Lex Fridman (1:27:11.340)

Well, that's kind of a derived quantity.

Lex Fridman (1:27:13.220)

What we really know about the world is when we open our eyes,

Lex Fridman (1:27:16.300)

what do you see?

Peter Woit (1:27:17.460)

You see a sphere.

Lex Fridman (1:27:19.580)

And that what you're looking at is you're looking at,

Peter Woit (1:27:23.100)

a sphere is worth of light rays coming into your eyes.

Lex Fridman (1:27:26.420)

And what Penrose says is that,

Peter Woit (1:27:29.140)

well, what a point in space time is, is that sphere,

Lex Fridman (1:27:33.820)

that sphere of all the light rays coming in.

Lex Fridman (1:27:36.620)

And he says, and you should formulate your,

Lex Fridman (1:27:39.180)

instead of thinking about points,

Peter Woit (1:27:40.700)

you should think about the space of those spheres,

Lex Fridman (1:27:43.100)

if you like, and formulate the degrees of freedom

Peter Woit (1:27:46.860)

as physics as living on those spheres, living on,

Lex Fridman (1:27:50.020)

so you're kind of living on,

Peter Woit (1:27:51.940)

your degrees of freedom are living on light rays,

Lex Fridman (1:27:53.660)

not on points.

Lex Fridman (1:27:55.180)

And it's a very different way of thinking about physics.

Lex Fridman (1:28:00.660)

And he and others working with him developed

Peter Woit (1:28:03.260)

a beautiful mathematical formulas

Lex Fridman (1:28:08.420)

and a way to go back from forth between some aspects

Peter Woit (1:28:11.540)

of our standard way we write these things down

Lex Fridman (1:28:14.180)

and work in the so called twister space.

Lex Fridman (1:28:17.380)

And certain things worked out very well,

Lex Fridman (1:28:20.380)

but they ended up, I think kind of stuck by the 80s or 90s

Peter Woit (1:28:24.940)

that they weren't a little bit like string theory

Lex Fridman (1:28:27.980)

that they, by using these ideas about twisters,

Peter Woit (1:28:31.220)

they could develop them in different directions

Lex Fridman (1:28:33.100)

and find all sorts of other interesting things,

Lex Fridman (1:28:34.780)

but they were getting,

Lex Fridman (1:28:36.900)

they weren't finding any way of doing that

Peter Woit (1:28:38.580)

that brought them back to kind of new insights into physics.

Lex Fridman (1:28:43.140)

And my own, I mean, what's kind of gotten me excited really

Peter Woit (1:28:46.420)

is what I think I have an idea about

Lex Fridman (1:28:49.700)

that I think does actually work,

Peter Woit (1:28:52.580)

that goes more in that direction.

Lex Fridman (1:28:54.180)

And I can go on about that endlessly

Peter Woit (1:28:56.780)

or talk a little bit about it,

Lex Fridman (1:28:57.820)

but that's the, I think that's the one kind of easy

Peter Woit (1:29:02.620)

to explain insight about twister theory.

Lex Fridman (1:29:05.260)

There are some more technical ones.

Peter Woit (1:29:06.860)

I should mean, I think it's also very convincing

Lex Fridman (1:29:09.340)

what it tells you about spinners, for instance,

Lex Fridman (1:29:11.260)

but that's a more technical.

Lex Fridman (1:29:12.980)

Well, first let's like linger on the spheres

Lex Fridman (1:29:14.980)

and the light cones.

Lex Fridman (1:29:17.460)

You're saying twisted theory allows you to make

Peter Woit (1:29:20.780)

that the fundamental object with which you're operating.

Lex Fridman (1:29:23.740)

Yeah.

Lex Fridman (1:29:24.660)

How that, I mean, first of all,

Lex Fridman (1:29:26.340)

like philosophically that's weird and beautiful,

Peter Woit (1:29:32.260)

maybe because it maps,

Lex Fridman (1:29:34.500)

it feels like it moves us so much closer

Peter Woit (1:29:37.020)

to the way human brains perceive reality.

Lex Fridman (1:29:40.500)

Yeah.

Lex Fridman (1:29:41.340)

So it's almost like our perception is like the content

Lex Fridman (1:29:46.340)

of our perception is the fundamental object of reality.

Peter Woit (1:29:54.580)

That's very appealing.

Lex Fridman (1:29:55.900)

Yeah.

Lex Fridman (1:29:57.260)

Is it mathematically powerful?

Lex Fridman (1:30:01.860)

Is there something you can say,

Lex Fridman (1:30:04.740)

can you say a little bit more about what the heck

Lex Fridman (1:30:06.540)

that even means for,

Peter Woit (1:30:08.380)

because it's much easier to think about mathematically

Lex Fridman (1:30:11.260)

like a point in space time.

Lex Fridman (1:30:13.740)

What does it mean to be operating on the light cone?

Lex Fridman (1:30:16.900)

It uses a kind of mathematics that's relative,

Peter Woit (1:30:19.380)

that kind of goes back to the 19th century

Lex Fridman (1:30:22.060)

among mathematicians.

Peter Woit (1:30:23.020)

It's not, anyway, it's a bit of a long story,

Lex Fridman (1:30:26.420)

but one problem is that you have to start,

Peter Woit (1:30:28.860)

it's crucial that you think in terms of complex numbers

Lex Fridman (1:30:31.700)

and not just real numbers.

Lex Fridman (1:30:32.900)

And this, for most people, that makes it harder to,

Lex Fridman (1:30:36.340)

for mathematicians, that's fine.

Peter Woit (1:30:37.620)

We love doing that.

Lex Fridman (1:30:38.460)

But for most people, that makes it harder to think about.

Peter Woit (1:30:41.380)

I think perhaps the most,

Lex Fridman (1:30:43.100)

the way that there is something you can say

Peter Woit (1:30:45.540)

very specifically about it in terms of spinners,

Lex Fridman (1:30:49.060)

which I don't know if you want to,

Peter Woit (1:30:50.060)

I think at some point you want to talk, so maybe you can.

Lex Fridman (1:30:52.340)

What are spinners?

Peter Woit (1:30:53.340)

Let's start with spinners,

Lex Fridman (1:30:54.180)

because I think that if we can introduce that,

Peter Woit (1:30:55.980)

then I can say it.

Lex Fridman (1:30:57.300)

By the way, twister is spelled with an O

Lex Fridman (1:31:01.020)

and spinner is spelled with an O as well.

Lex Fridman (1:31:03.700)

Yes, okay.

Peter Woit (1:31:05.260)

In case you want to Google it and look it up,

Lex Fridman (1:31:07.660)

there's very nice Wikipedia pages as a starting point.

Peter Woit (1:31:10.940)

I don't know what is a good starting point

Lex Fridman (1:31:12.380)

for twister theory.

Peter Woit (1:31:13.540)

Well, one thing you say about Penrose,

Lex Fridman (1:31:16.060)

I mean, Penrose is actually a very good writer

Lex Fridman (1:31:18.100)

and also a very good draftsman.

Lex Fridman (1:31:19.380)

He's a draftsman, to the extent this is visualizable,

Peter Woit (1:31:22.020)

he actually has done some very nice drawings.

Lex Fridman (1:31:23.700)

So, I mean, almost any kind of expository thing

Peter Woit (1:31:26.460)

you can find him writing is a very good place to start.

Lex Fridman (1:31:29.820)

He's a remarkable person.

Lex Fridman (1:31:32.540)

But the, so spinners are something

Lex Fridman (1:31:36.060)

that independently came out of mathematics

Lex Fridman (1:31:38.380)

and out of physics.

Lex Fridman (1:31:40.060)

And to say where they came out of physics,

Peter Woit (1:31:42.620)

I mean, what people realized when they started looking

Lex Fridman (1:31:44.620)

at elementary particles like electrons or whatever,

Peter Woit (1:31:47.580)

that there seem to be some kind of doubling

Lex Fridman (1:31:51.660)

of the degrees of freedom going on.

Peter Woit (1:31:53.140)

If you counted what was there in some sense

Lex Fridman (1:31:57.060)

in the way you would expect it

Lex Fridman (1:31:58.180)

and when you started doing quantum mechanics

Lex Fridman (1:32:00.020)

and started looking at elementary particles,

Peter Woit (1:32:01.780)

there were seen to be two degrees of freedom,

Lex Fridman (1:32:03.700)

they're not one.

Lex Fridman (1:32:04.900)

And one way of seeing it was that if you put your electron

Lex Fridman (1:32:09.860)

in a strong magnetic field and asked what was the energy

Peter Woit (1:32:13.860)

of it, instead of it having one energy,

Lex Fridman (1:32:15.540)

it would have two energies, there'd be two energy levels.

Lex Fridman (1:32:17.940)

And as you increase magnetic field,

Lex Fridman (1:32:20.500)

the splitting would increase.

Lex Fridman (1:32:22.100)

So physicists kind of realized that, wait a minute.

Lex Fridman (1:32:24.980)

So we thought when we were doing,

Peter Woit (1:32:27.020)

first started doing quantum mechanics,

Lex Fridman (1:32:28.260)

that the way to describe particles was in terms

Peter Woit (1:32:31.660)

of wave functions and these wave functions

Lex Fridman (1:32:33.540)

were complex to complex values.

Peter Woit (1:32:35.860)

Well, if we actually look at particles,

Lex Fridman (1:32:38.020)

that that's not right.

Peter Woit (1:32:38.860)

They're pairs of complex numbers.

Lex Fridman (1:32:42.060)

They're pairs of complex numbers.

Lex Fridman (1:32:44.100)

So one of the kind of fundamental,

Lex Fridman (1:32:46.900)

from the physics point of view,

Peter Woit (1:32:47.820)

the fundamental question is why are all our kind

Lex Fridman (1:32:50.220)

of fundamental particles described

Lex Fridman (1:32:53.900)

by pairs of complex numbers?

Lex Fridman (1:32:55.740)

Just weird.

Lex Fridman (1:32:56.740)

And then you can ask, well, what happens

Lex Fridman (1:33:00.220)

if you like take an electron and rotate it?

Lex Fridman (1:33:03.140)

So how do things move in this pair of complex numbers?

Lex Fridman (1:33:08.140)

Well, now, if you go back to mathematics,

Lex Fridman (1:33:10.940)

what had been understood in mathematics,

Lex Fridman (1:33:13.860)

some years earlier, not that many years earlier,

Peter Woit (1:33:16.380)

was that if you ask very, very generally,

Lex Fridman (1:33:20.500)

think about geometry of three dimensions and ask,

Lex Fridman (1:33:24.260)

and if you think about things that are happening

Lex Fridman (1:33:25.820)

in three dimensions in the standard way,

Peter Woit (1:33:28.260)

everything, the standard way of doing geometry,

Lex Fridman (1:33:30.500)

everything is about vectors, right?

Lex Fridman (1:33:32.540)

So if you've taken any mathematics classes,

Lex Fridman (1:33:35.220)

you probably see vectors at some point.

Peter Woit (1:33:36.700)

They're just triplets of numbers tell you

Lex Fridman (1:33:39.420)

what a direction is or how far you're going

Peter Woit (1:33:41.620)

in three dimensional space.

Lex Fridman (1:33:42.980)

And most of everything we teach in most standard courses

Peter Woit (1:33:46.260)

in mathematics is about vectors

Lex Fridman (1:33:49.700)

and things you build out of vectors.

Lex Fridman (1:33:51.420)

So you express everything about geometry

Lex Fridman (1:33:53.060)

in terms of vectors or how they're changing

Peter Woit (1:33:55.420)

or how you put two of them together

Lex Fridman (1:33:57.620)

and get planes and whatever.

Lex Fridman (1:34:00.940)

But what had been realized that,

Lex Fridman (1:34:03.660)

Rianna, is that if you ask very, very generally,

Lex Fridman (1:34:05.820)

what are the, if you have, what are the things

Lex Fridman (1:34:09.140)

that you can kind of consistently think about rotating?

Lex Fridman (1:34:13.020)

And so you ask a technical question,

Lex Fridman (1:34:16.340)

what are the representations of the rotation group?

Peter Woit (1:34:18.620)

Well, you find that one answer is they're vectors

Lex Fridman (1:34:22.220)

and everything you build out of vectors,

Lex Fridman (1:34:24.660)

but then people found, but wait a minute,

Lex Fridman (1:34:26.420)

there's also these other things,

Peter Woit (1:34:29.220)

which you can build out of vectors,

Lex Fridman (1:34:31.820)

but which you can consistently rotate.

Lex Fridman (1:34:34.420)

And they're described by pairs of complex numbers,

Lex Fridman (1:34:37.020)

by two complex numbers.

Lex Fridman (1:34:38.420)

And they're the spinners also.

Lex Fridman (1:34:40.580)

And to make a lot, and to make,

Lex Fridman (1:34:43.020)

and you can think of spinners in some sense

Lex Fridman (1:34:45.060)

as more fundamental than vectors

Peter Woit (1:34:46.660)

because you can build vectors out of spinners.

Lex Fridman (1:34:48.860)

You can take two spinners and make a vector,

Lex Fridman (1:34:51.180)

but you can't, if you only have vectors,

Lex Fridman (1:34:54.940)

you can't get spinners.

Lex Fridman (1:34:56.620)

So they're in some sense, there's some kind of level

Lex Fridman (1:34:59.220)

of lower level of geometry beyond what we thought it was,

Peter Woit (1:35:02.140)

which was kind of spinner geometry.

Lex Fridman (1:35:04.260)

And this is something which even to this day,

Peter Woit (1:35:07.340)

when we teach graduate courses in geometry,

Lex Fridman (1:35:09.460)

we mostly don't talk about this

Peter Woit (1:35:11.700)

because it's a bit hard to do correctly.

Lex Fridman (1:35:15.380)

If you start with your whole setup is in terms of vectors,

Peter Woit (1:35:20.420)

describing things in terms of spinners

Lex Fridman (1:35:22.020)

is a whole different ball game.

Lex Fridman (1:35:24.860)

But anyway, it was just this amazing fact

Lex Fridman (1:35:28.780)

that this kind of more fundamental piece of geometry,

Peter Woit (1:35:33.020)

spinners, and what we were actually seeing,

Lex Fridman (1:35:35.500)

if you look at electron, are one and the same.

Lex Fridman (1:35:37.900)

So it's, I think it's kind of a mind blowing thing,

Lex Fridman (1:35:41.300)

but it's very counterintuitive.

Lex Fridman (1:35:44.860)

What are some weird properties of spinners

Lex Fridman (1:35:47.020)

that are counterintuitive?

Peter Woit (1:35:50.220)

That there are some things that they do,

Lex Fridman (1:35:51.540)

for instance, if you rotate a spinner around 360 degrees,

Peter Woit (1:35:56.300)

it doesn't come back towards,

Lex Fridman (1:35:58.260)

it becomes minus what it was.

Peter Woit (1:36:00.020)

Or, so it's, anyway, so the way rotations work,

Lex Fridman (1:36:04.660)

there's a kind of a funny sign

Peter Woit (1:36:05.900)

you have to keep track of in some sense.

Lex Fridman (1:36:08.180)

So they're kind of too valued in another weird way.

Lex Fridman (1:36:11.020)

But the fundamental problem is that it's just not,

Lex Fridman (1:36:14.700)

if you're used to visualizing vectors,

Peter Woit (1:36:17.540)

you just, there's nothing you can do

Lex Fridman (1:36:19.600)

visualizing in terms of vectors

Peter Woit (1:36:20.560)

that will ever give you a spinner.

Lex Fridman (1:36:21.860)

It just is not gonna ever work.

Peter Woit (1:36:23.820)

As you were saying that I was visualizing a vector

Lex Fridman (1:36:26.600)

walking along a Mobius strip,

Lex Fridman (1:36:29.100)

and it ends up being upside down.

Lex Fridman (1:36:32.460)

But you're saying that doesn't really capture.

Lex Fridman (1:36:34.820)

So, I mean, what really captures it?

Lex Fridman (1:36:36.860)

The problem is that it's really,

Peter Woit (1:36:39.460)

the simplest way to describe it

Lex Fridman (1:36:41.020)

is in terms of two complex numbers.

Lex Fridman (1:36:43.420)

And your problem with two complex numbers

Lex Fridman (1:36:45.060)

is that's four real numbers.

Lex Fridman (1:36:46.820)

So your spinner kind of lies in a four dimensional space.

Lex Fridman (1:36:50.540)

So you, that makes it hard to visualize.

Lex Fridman (1:36:53.820)

And it's crucial that it's not just any four dimensions.

Lex Fridman (1:36:57.540)

It's just, it's actually complex numbers.

Peter Woit (1:36:59.340)

You're really gonna use the fact that

Lex Fridman (1:37:01.740)

these are two complex numbers.

Lex Fridman (1:37:03.180)

So it's very hard to visualize.

Lex Fridman (1:37:06.140)

But to get back to what I think is mind blowing

Peter Woit (1:37:09.300)

about twisters is that the,

Lex Fridman (1:37:11.980)

another way of saying this idea about talking about spheres,

Peter Woit (1:37:15.780)

another way of saying the fundamental idea of twister theory

Lex Fridman (1:37:18.640)

is in some sense, the fundamental idea of twister theory

Peter Woit (1:37:21.540)

is that a point is a two complex dimensional space.

Lex Fridman (1:37:28.700)

So that every, and that it lives inside,

Peter Woit (1:37:32.020)

the space that it lies inside is twister space.

Lex Fridman (1:37:34.540)

So in the simplest case, it's four,

Peter Woit (1:37:36.700)

twister space is four dimensional

Lex Fridman (1:37:38.480)

and a point in space time

Peter Woit (1:37:40.820)

is a two complex dimensional subspace

Lex Fridman (1:37:44.900)

of all the four complex dimensions.

Lex Fridman (1:37:47.500)

And as you move around in space time,

Lex Fridman (1:37:49.000)

you're just moving, your planes are just moving around.

Peter Woit (1:37:51.620)

Okay.

Lex Fridman (1:37:52.460)

And that, but then the.

Lex Fridman (1:37:54.540)

So it's a plane in a four dimensional space.

Lex Fridman (1:37:56.980)

It's a plane.

Peter Woit (1:37:58.660)

Complex.

Lex Fridman (1:37:59.480)

Complex plane.

Lex Fridman (1:38:00.320)

So it's two complex dimensions in four complex.

Lex Fridman (1:38:03.060)

Got it.

Lex Fridman (1:38:03.900)

But then to me, the mind blowing thing about this

Lex Fridman (1:38:05.780)

is this then kind of tautologically answers the question

Lex Fridman (1:38:09.380)

is what is a spinner?

Lex Fridman (1:38:10.380)

Well, a spinner is a point.

Peter Woit (1:38:14.100)

I mean, the space of spinners at a point is the point.

Lex Fridman (1:38:17.920)

In twister theory, the points are the complex two planes.

Lex Fridman (1:38:21.520)

And you want me to, and you're asking what a spinner is.

Lex Fridman (1:38:24.620)

Well, a spinner, the space of spinners is that two plane.

Lex Fridman (1:38:28.260)

So it's, you know, just your whole definition

Lex Fridman (1:38:31.820)

of what a point in space time was

Peter Woit (1:38:33.380)

just told you what a spinner was.

Lex Fridman (1:38:35.180)

It's, they're just, it's the same thing.

Peter Woit (1:38:37.220)

Yeah, but we're trying to project that

Lex Fridman (1:38:38.500)

into a three dimensional space

Lex Fridman (1:38:39.760)

and trying to intuit, but you can't.

Lex Fridman (1:38:42.300)

Yeah, so the intuition becomes very difficult,

Lex Fridman (1:38:44.140)

but from, if you don't, not using twister theory,

Lex Fridman (1:38:49.740)

you have to kind of go through a certain

Peter Woit (1:38:51.300)

fairly complicated rigmarole to even describe spinners

Lex Fridman (1:38:54.600)

to describe electrons.

Peter Woit (1:38:55.980)

Whereas using twister theory,

Lex Fridman (1:38:57.220)

it's just completely tautological.

Peter Woit (1:38:58.820)

They're just what you want to describe.

Lex Fridman (1:39:03.100)

The electron is fundamentally the way

Peter Woit (1:39:05.980)

that you're describing the point in space time already.

Lex Fridman (1:39:08.180)

It's just there, so.

Lex Fridman (1:39:10.740)

Do you have a hope?

Lex Fridman (1:39:11.580)

You mentioned that you found it appealing recently.

Peter Woit (1:39:14.940)

Is it just because of certain aspects

Lex Fridman (1:39:17.260)

of its mathematical beauty,

Peter Woit (1:39:18.500)

or do you actually have a hope

Lex Fridman (1:39:19.660)

that this might lead to a theory of everything?

Peter Woit (1:39:22.580)

Yeah, I mean, I certainly do have such a hope

Lex Fridman (1:39:25.120)

because what I've found, I think the thing which I've done,

Peter Woit (1:39:27.980)

which I don't think, as far as I can tell,

Lex Fridman (1:39:29.740)

no one had really looked at from this point of view before

Peter Woit (1:39:33.380)

is, has to do with this question of how do you treat time

Lex Fridman (1:39:39.000)

in your quantum theory?

Lex Fridman (1:39:40.840)

And so there's another long story

Lex Fridman (1:39:44.440)

about how we do quantum theories

Lex Fridman (1:39:46.700)

and about how we treat time in quantum theories,

Lex Fridman (1:39:48.700)

which is a long story.

Lex Fridman (1:39:51.780)

But the short version of it is that what people have found

Lex Fridman (1:39:55.580)

when you try and write down a quantum theory,

Peter Woit (1:39:58.460)

that it's often a good idea to take your time coordinate,

Lex Fridman (1:40:05.220)

whatever you're using to your time coordinate,

Lex Fridman (1:40:07.100)

and multiply it by the square root of minus one

Lex Fridman (1:40:09.920)

and to make it purely imaginary.

Lex Fridman (1:40:11.980)

And so all these formulas,

Lex Fridman (1:40:13.580)

which you have in your standard theory,

Peter Woit (1:40:18.460)

if you do that to those,

Lex Fridman (1:40:19.900)

I mean, those formulas have some very strange behavior

Lex Fridman (1:40:23.660)

and they're kind of singular.

Lex Fridman (1:40:25.380)

If you ask even some simple questions,

Peter Woit (1:40:27.800)

you have to take very delicate singular limits

Lex Fridman (1:40:31.020)

in order to get the correct answer,

Lex Fridman (1:40:33.260)

and you have to take them from the right direction,

Lex Fridman (1:40:35.060)

otherwise it doesn't work.

Peter Woit (1:40:36.980)

Whereas if you just take time,

Lex Fridman (1:40:39.980)

and if you just put a factor of square root of minus one,

Peter Woit (1:40:42.120)

wherever you see the time coordinate,

Lex Fridman (1:40:44.240)

you end up with much simpler formulas,

Peter Woit (1:40:47.340)

which are much better behaved mathematically.

Lex Fridman (1:40:49.900)

And what I hadn't really appreciated until fairly recently

Peter Woit (1:40:52.900)

is also how dramatically that changes

Lex Fridman (1:40:55.500)

the whole structure of the theory.

Peter Woit (1:40:57.260)

You end up with a consistent way of talking

Lex Fridman (1:40:59.800)

about these quantum theories,

Lex Fridman (1:41:01.600)

but it has some very different flavor

Lex Fridman (1:41:04.280)

and very different aspects that I hadn't really appreciated.

Lex Fridman (1:41:07.380)

And in particular, the way symmetries act on it

Lex Fridman (1:41:10.900)

is not at all what I originally had expected.

Lex Fridman (1:41:15.060)

And so that's the new thing that I have,

Lex Fridman (1:41:17.660)

or I think gives you something,

Peter Woit (1:41:19.580)

is to do this move,

Lex Fridman (1:41:21.820)

which people often think of as just kind of a mathematical

Peter Woit (1:41:26.340)

trick that you're doing

Lex Fridman (1:41:27.380)

to make some formulas work out nicely,

Lex Fridman (1:41:29.780)

but to take that mathematical trick as really fundamental.

Lex Fridman (1:41:33.180)

And it turns out in Twister theory

Peter Woit (1:41:35.940)

allows you to simultaneously talk about your usual time

Lex Fridman (1:41:39.540)

and the time times the square root of minus one,

Peter Woit (1:41:41.900)

they both fit very nicely into Twister theory.

Lex Fridman (1:41:45.500)

And you end up with some structures

Peter Woit (1:41:48.380)

which look a lot like the standard models.

Lex Fridman (1:41:51.980)

Well, let me ask you about some Nobel prizes.

Peter Woit (1:41:54.140)

Okay.

Lex Fridman (1:41:55.300)

Do you think there will be,

Peter Woit (1:41:56.660)

there was a bet between Michio Kaku

Lex Fridman (1:42:01.780)

and somebody else about.

Peter Woit (1:42:04.100)

John Horgan.

Lex Fridman (1:42:05.020)

John Horgan about,

Peter Woit (1:42:07.380)

by the way, maybe discover a cool website,

Lex Fridman (1:42:09.140)

longbets.com or.org.

Peter Woit (1:42:11.140)

Better, yeah, yeah.

Lex Fridman (1:42:11.980)

Yeah, it's cool.

Peter Woit (1:42:12.980)

It's cool that you can make a bet with people

Lex Fridman (1:42:16.380)

and then check in 20 years later.

Peter Woit (1:42:18.860)

I really love it.

Lex Fridman (1:42:19.700)

There's a lot of interesting bets on there.

Peter Woit (1:42:21.300)

I would love to participate,

Lex Fridman (1:42:22.460)

but it's interesting to see,

Peter Woit (1:42:24.020)

time flies and you make a bet about

Lex Fridman (1:42:27.460)

what's going to happen in 20 years.

Peter Woit (1:42:28.900)

You don't realize 20 years just goes like this.

Lex Fridman (1:42:31.900)

And then you get to face out

Lex Fridman (1:42:33.700)

and you get to wonder what was that person?

Lex Fridman (1:42:39.620)

What was I thinking?

Peter Woit (1:42:41.060)

That person 20 years ago

Lex Fridman (1:42:42.780)

was almost like a different person.

Lex Fridman (1:42:43.900)

What was I thinking back then to think that?

Lex Fridman (1:42:46.340)

It's interesting.

Lex Fridman (1:42:47.500)

So let me ask you this on record,

Lex Fridman (1:42:49.620)

20 years from now or some number of years from now,

Lex Fridman (1:42:54.020)

do you think there will be a Nobel Prize given

Lex Fridman (1:42:55.780)

for something directly connected

Lex Fridman (1:42:58.300)

to a first broadly theory of everything?

Lex Fridman (1:43:01.740)

And second, of course, one of the possibilities,

Lex Fridman (1:43:05.980)

one of them, string theory?

Lex Fridman (1:43:10.940)

String theory, definitely not.

Peter Woit (1:43:13.420)

Things have gone, yeah.

Lex Fridman (1:43:16.180)

So if you were giving financial advice,

Lex Fridman (1:43:18.140)

you would say not to bet on that?

Lex Fridman (1:43:19.140)

No, do not.

Lex Fridman (1:43:20.380)

And even, I actually suspect

Lex Fridman (1:43:22.660)

if you ask string theorists that question,

Peter Woit (1:43:24.260)

you're gonna get a few of them saying,

Lex Fridman (1:43:27.500)

I mean, if you'd asked them that question 20 years ago,

Peter Woit (1:43:29.620)

again, when Kaku was making this bet or whatever,

Lex Fridman (1:43:32.140)

I think some of them would have taken you up on it.

Lex Fridman (1:43:35.460)

And certainly back in 1984,

Lex Fridman (1:43:37.020)

a bunch of them would have said, oh, sure, yeah.

Lex Fridman (1:43:39.020)

But now I get the impression that

Lex Fridman (1:43:43.060)

even they realize that things are not looking good

Peter Woit (1:43:45.700)

for that particular idea.

Lex Fridman (1:43:46.900)

Again, it depends what you mean by string theory,

Peter Woit (1:43:48.620)

whether maybe the term will evolve to mean something else,

Lex Fridman (1:43:51.940)

which will work out.

Lex Fridman (1:43:53.800)

But I don't think that's not gonna like it to work out,

Lex Fridman (1:43:57.400)

whether something else.

Peter Woit (1:43:59.060)

I mean, I still think it's relatively unlikely

Lex Fridman (1:44:01.220)

that you'll have any really successful theory of everything.

Lex Fridman (1:44:04.940)

And the main problem is just the,

Lex Fridman (1:44:08.900)

it's become so difficult to do experiments at higher energy

Peter Woit (1:44:11.980)

that we've really lost this ability

Lex Fridman (1:44:13.620)

to kind of get unexpected input from experiment.

Lex Fridman (1:44:19.140)

And you can, while it's maybe hard to figure out

Lex Fridman (1:44:22.260)

what people's thinking is gonna be 20 years from now,

Peter Woit (1:44:24.900)

looking at high energy particle,

Lex Fridman (1:44:28.780)

high energy colliders and their technology,

Peter Woit (1:44:30.940)

it's actually pretty easy to make a pretty accurate guess

Lex Fridman (1:44:33.580)

what you're gonna be doing 20 years from now.

Lex Fridman (1:44:37.300)

And I think actually, I would actually claim that

Lex Fridman (1:44:42.300)

it's pretty clear where you're gonna be 20 years from now.

Lex Fridman (1:44:44.540)

And what it's gonna be is you're gonna have the LHC,

Lex Fridman (1:44:50.020)

you're gonna have a lot more data,

Peter Woit (1:44:51.500)

an order of magnitude or more data from the LHC,

Lex Fridman (1:44:56.100)

but at the same energy.

Peter Woit (1:44:57.580)

You're not gonna see a higher energy accelerator

Lex Fridman (1:45:01.940)

operating successfully in the next 20 years.

Lex Fridman (1:45:05.340)

And like maybe machine learning

Lex Fridman (1:45:08.140)

or great sort of data science methodologies

Peter Woit (1:45:10.240)

that process that data will not reveal

Lex Fridman (1:45:12.580)

any major shifts in our understanding

Lex Fridman (1:45:17.380)

of the underlying physics, you think?

Lex Fridman (1:45:19.180)

I don't think so.

Peter Woit (1:45:20.020)

I mean, I think that field, my understanding

Lex Fridman (1:45:23.060)

is they're starting to make a great use of those techniques,

Lex Fridman (1:45:26.940)

but it seems to look like it will help them

Lex Fridman (1:45:29.540)

solve certain technical problems

Lex Fridman (1:45:30.980)

and be able to do things somewhat better,

Lex Fridman (1:45:32.500)

but not completely change the way they're looking at things.

Lex Fridman (1:45:36.600)

What do you think about the potential quantum computers

Lex Fridman (1:45:39.580)

simulating quantum mechanical systems

Lex Fridman (1:45:41.300)

and through that sneak up to sort of through simulation,

Lex Fridman (1:45:46.600)

sneak up to a deep understanding of the fundamental physics?

Peter Woit (1:45:51.540)

The problem there is that that's promising more

Lex Fridman (1:45:54.780)

for this, for Phil Anderson's problem,

Peter Woit (1:45:59.420)

that if you wanna, there's lots and lots of,

Lex Fridman (1:46:06.060)

you start putting together lots and lots of things

Lex Fridman (1:46:08.580)

and we think we know they're pair by pair interactions,

Lex Fridman (1:46:11.060)

but what this thing is gonna do,

Peter Woit (1:46:13.380)

we don't have any good calculational techniques.

Lex Fridman (1:46:16.540)

Quantum computers may very well give you those.

Lex Fridman (1:46:19.540)

And so they may, what we think of

Lex Fridman (1:46:21.660)

is kind of a strong coupling behavior.

Peter Woit (1:46:23.260)

We have no good way to calculate.

Lex Fridman (1:46:26.780)

Even though we can write down the theory,

Peter Woit (1:46:28.300)

we don't know how to calculate anything with any accuracy

Lex Fridman (1:46:31.580)

and the quantum computer may solve that problem.

Lex Fridman (1:46:34.620)

But the problem is that I don't think

Lex Fridman (1:46:36.660)

that they're gonna solve the problem

Peter Woit (1:46:38.140)

that they help you with the problem

Lex Fridman (1:46:39.220)

of not having the, of knowing

Lex Fridman (1:46:41.860)

what the right underlying theory is.

Lex Fridman (1:46:44.220)

As somebody who likes experimental validation,

Peter Woit (1:46:48.580)

let me ask you the perhaps ridiculous sounding,

Lex Fridman (1:46:51.300)

but I don't think it's actually a ridiculous question

Lex Fridman (1:46:53.300)

of do you think we live in a simulation?

Lex Fridman (1:46:56.700)

Do you find that thought experiment

Lex Fridman (1:46:58.340)

at all useful or interesting?

Lex Fridman (1:47:00.220)

Not really, I don't, it just doesn't.

Peter Woit (1:47:03.680)

Yeah, anyway, to me, it doesn't actually lead

Lex Fridman (1:47:08.700)

to any kind of interesting, lead anywhere interesting.

Peter Woit (1:47:11.980)

Yeah, to me, so maybe I'll throw a wrench into your thing.

Lex Fridman (1:47:16.700)

To me, it's super interesting

Peter Woit (1:47:17.860)

from an engineering perspective.

Lex Fridman (1:47:19.620)

So if you look at virtual reality systems,

Peter Woit (1:47:23.140)

the actual question is how much computation

Lex Fridman (1:47:28.220)

and how difficult is it to construct a world

Peter Woit (1:47:32.980)

that like there are several levels here.

Lex Fridman (1:47:36.680)

One is you won't know the difference,

Peter Woit (1:47:39.700)

our human perception systems

Lex Fridman (1:47:41.340)

and maybe even the tools of physics

Peter Woit (1:47:42.720)

won't know the difference

Lex Fridman (1:47:43.820)

between the simulated world and the real world.

Peter Woit (1:47:47.160)

That's sort of more of a physics question.

Lex Fridman (1:47:51.020)

The most interesting question to me

Peter Woit (1:47:53.060)

has more to do with why food tastes delicious,

Lex Fridman (1:47:55.740)

which is create how difficult

Lex Fridman (1:47:58.700)

and how much computation is required

Lex Fridman (1:48:00.380)

to construct a simulation

Peter Woit (1:48:02.860)

where you kind of know it's a simulation at first,

Lex Fridman (1:48:06.100)

but you want to stay there anyway.

Lex Fridman (1:48:07.860)

And over time, you don't even remember.

Lex Fridman (1:48:13.340)

Yeah, well, anyway, I agree,

Peter Woit (1:48:15.860)

these are kind of fascinating questions

Lex Fridman (1:48:18.340)

and they may be very, very relevant

Peter Woit (1:48:20.020)

to our future as a species,

Lex Fridman (1:48:21.900)

but yeah, they're just very far from anything I think.

Peter Woit (1:48:26.060)

Well, so from a physics perspective,

Lex Fridman (1:48:27.580)

it's not useful to you to think,

Peter Woit (1:48:29.420)

taking a computational perspective to our universe,

Lex Fridman (1:48:32.380)

thinking of it as an information processing system

Lex Fridman (1:48:35.140)

and then they give it as doing computation

Lex Fridman (1:48:37.420)

and then you think about the resources required

Peter Woit (1:48:39.440)

to do that kind of computation and all that kind of stuff.

Lex Fridman (1:48:42.260)

You could just look at the basic physics

Lex Fridman (1:48:43.820)

and who cares what the computer it's running on is.

Lex Fridman (1:48:46.700)

Yeah, it just, I mean, the kinds of,

Peter Woit (1:48:48.020)

I mean, I'm willing to agree

Lex Fridman (1:48:49.940)

that you can get into interesting kinds of questions

Peter Woit (1:48:51.860)

going down that road,

Lex Fridman (1:48:52.820)

but they're just so different from anything

Peter Woit (1:48:55.220)

from what I've found interesting and I just,

Lex Fridman (1:48:57.420)

again, I just have to kind of go back to life is too short

Lex Fridman (1:49:01.280)

and I'm very glad other people are thinking about this,

Lex Fridman (1:49:03.700)

but I just don't see anything I can do with it.

Lex Fridman (1:49:08.500)

What about space itself?

Lex Fridman (1:49:11.480)

So I have to ask you about aliens.

Peter Woit (1:49:14.300)

Again, something, since you emphasize evidence,

Lex Fridman (1:49:18.740)

do you think there is, how many,

Lex Fridman (1:49:20.820)

do you think there are and how many

Lex Fridman (1:49:23.000)

intelligent alien civilizations are out there?

Peter Woit (1:49:25.900)

Yeah, I have no idea, but I have certainly,

Lex Fridman (1:49:28.540)

as far as I know, unless the government's covering it up

Peter Woit (1:49:30.700)

or something, we haven't heard from,

Lex Fridman (1:49:32.980)

we don't have any evidence for such things yet,

Lex Fridman (1:49:35.780)

but there seems to be no,

Lex Fridman (1:49:38.720)

there's no particular obstruction why there shouldn't be, so.

Peter Woit (1:49:43.220)

I mean, do you, you work on some fundamental questions

Lex Fridman (1:49:47.460)

about the physics of reality.

Peter Woit (1:49:49.140)

When you look up to the stars,

Lex Fridman (1:49:51.620)

do you think about whether somebody's looking back at us?

Peter Woit (1:49:55.260)

Yes, yeah, well, actually,

Lex Fridman (1:49:56.100)

I originally got interested in physics.

Peter Woit (1:49:58.140)

I actually started out as a kid interested in astronomy,

Lex Fridman (1:50:00.180)

exactly that, and a telescope and whatever that,

Lex Fridman (1:50:02.300)

and certainly read a lot of science fiction

Lex Fridman (1:50:05.620)

and thought about that.

Peter Woit (1:50:08.340)

I find over the years, I find myself kind of less,

Lex Fridman (1:50:12.020)

anyway, less and less interested in that one,

Peter Woit (1:50:15.100)

just because I don't really know what to do with them.

Lex Fridman (1:50:19.120)

I also kind of, at some point,

Peter Woit (1:50:20.420)

kind of stopped reading science fiction that much,

Lex Fridman (1:50:23.060)

kind of feeling that there was just too,

Peter Woit (1:50:25.140)

that the actual science I was kind of learning about

Lex Fridman (1:50:27.100)

was perfectly kind of weird and fascinating,

Lex Fridman (1:50:29.920)

and unusual enough, and better than any of the stuff

Lex Fridman (1:50:33.140)

that Isaac Asimov, so why should I?

Peter Woit (1:50:36.620)

Yeah, and you can mess with the science

Lex Fridman (1:50:39.740)

much more than the distant science fiction,

Peter Woit (1:50:43.180)

the one that exists in our imagination

Lex Fridman (1:50:45.400)

or the one that exists out there among the stars.

Peter Woit (1:50:49.500)

Well, you mentioned science fiction.

Lex Fridman (1:50:51.180)

You've written quite a few book reviews.

Peter Woit (1:50:54.060)

I gotta ask you about some books, perhaps,

Lex Fridman (1:50:56.420)

if you don't mind.

Peter Woit (1:50:57.580)

Is there one or two books that you would recommend to others

Lex Fridman (1:51:03.500)

and maybe if you can, what ideas you drew from them?

Peter Woit (1:51:09.300)

Either negative recommendations or positive recommendations.

Lex Fridman (1:51:12.660)

Do not read this book for sure.

Peter Woit (1:51:15.220)

Well, I must say, I mean, unfortunately,

Lex Fridman (1:51:18.260)

yeah, you can go to my website

Lex Fridman (1:51:19.860)

and you can click on book reviews

Lex Fridman (1:51:21.700)

and you can see I've written, read a lot of,

Peter Woit (1:51:24.060)

a lot of, I mean, as you can tell from my views

Lex Fridman (1:51:27.180)

about string theory, I'm not a fan

Peter Woit (1:51:28.780)

of a lot of the kind of popular books

Lex Fridman (1:51:31.020)

about, oh, isn't string theory great?

Lex Fridman (1:51:32.740)

And yes, I'm not a fan of a lot of things of that kind.

Lex Fridman (1:51:37.660)

Can I ask you a quick question on this, a small tangent?

Peter Woit (1:51:41.420)

Are you a fan, can you explore the pros and cons

Lex Fridman (1:51:46.540)

of, if I get string theory, sort of science communication,

Peter Woit (1:51:51.620)

sort of Cosmos style communication of concepts

Lex Fridman (1:51:56.620)

to people that are outside of physics,

Peter Woit (1:51:59.040)

outside of mathematics, outside of even the sciences

Lex Fridman (1:52:02.240)

and helping people to sort of dream

Lex Fridman (1:52:04.780)

and fill them with awe about the full range

Lex Fridman (1:52:07.560)

of mysteries in our universe?

Peter Woit (1:52:10.420)

That's a complicated issue.

Lex Fridman (1:52:11.260)

You know, I think, you know, I certainly go back

Lex Fridman (1:52:13.680)

and go back to like what inspired me

Lex Fridman (1:52:15.680)

and maybe to connect it a little bit

Peter Woit (1:52:18.440)

to this question about books.

Lex Fridman (1:52:19.320)

I mean, certainly when the books,

Peter Woit (1:52:21.540)

some books that I remember reading when I was a kid

Lex Fridman (1:52:23.980)

were about the early history of quantum mechanics,

Peter Woit (1:52:26.280)

like Heisenberg's books that he wrote about, you know,

Lex Fridman (1:52:29.080)

kind of looking back at telling the history

Peter Woit (1:52:31.120)

of what happened when he developed quantum mechanics.

Lex Fridman (1:52:32.960)

It's just kind of a totally fascinating, romantic,

Peter Woit (1:52:36.640)

great story, and those were very inspirational to me.

Lex Fridman (1:52:40.040)

And I would think maybe other people

Peter Woit (1:52:41.840)

might also find them that, but the...

Lex Fridman (1:52:45.160)

And that's almost like the human story

Peter Woit (1:52:47.240)

of the development of the ideas.

Lex Fridman (1:52:49.120)

Yeah, the human story, but yeah, just also how, you know,

Peter Woit (1:52:51.800)

there are these very, very weird ideas

Lex Fridman (1:52:53.760)

that didn't seem to make sense,

Lex Fridman (1:52:54.800)

and how they were struggling with them

Lex Fridman (1:52:56.280)

and how, you know, they actually...

Peter Woit (1:52:58.320)

Anyway, it's, I think it's the period of physics

Lex Fridman (1:53:01.840)

kind of beginning, you know, 1905 with Planck and Einstein

Lex Fridman (1:53:06.080)

and ending up with the war

Lex Fridman (1:53:08.400)

when these things get used to, you know,

Peter Woit (1:53:11.280)

make massively destructive weapons.

Lex Fridman (1:53:14.060)

It's just the truly amazing...

Lex Fridman (1:53:15.720)

And so many, so many new ideas.

Lex Fridman (1:53:17.580)

Let me, on another, a tangent on top of a tangent

Peter Woit (1:53:19.800)

on top of a tangent, ask,

Lex Fridman (1:53:21.500)

if we didn't have Einstein, so how does science progress?

Lex Fridman (1:53:26.740)

Is it the lone geniuses?

Lex Fridman (1:53:28.980)

Or is it some kind of weird network of ideas

Peter Woit (1:53:32.980)

swimming in the air and just kind of the geniuses

Lex Fridman (1:53:36.620)

pop up to catch them and others would anyway?

Peter Woit (1:53:39.260)

Without Einstein, would we have special relativity,

Lex Fridman (1:53:42.580)

general relativity?

Peter Woit (1:53:44.740)

I mean, it's an interesting case to case basis.

Lex Fridman (1:53:47.260)

I mean, special relativity, I think we would have had,

Peter Woit (1:53:51.820)

I mean, there are other people.

Lex Fridman (1:53:53.940)

Anyway, you could even argue that it was already there

Peter Woit (1:53:56.700)

in some form in some ways,

Lex Fridman (1:53:57.900)

but I think special relativity you would have had

Peter Woit (1:54:00.340)

without Einstein fairly quickly.

Lex Fridman (1:54:03.300)

General relativity, that was a much, much harder thing to do

Lex Fridman (1:54:07.580)

and required a much more effort, much more sophisticated.

Lex Fridman (1:54:11.700)

That I think you would have had sooner or later,

Lex Fridman (1:54:13.960)

but it would have taken quite a bit longer.

Lex Fridman (1:54:16.820)

That took a bunch of years to validate scientifically,

Peter Woit (1:54:20.500)

the general relativity.

Lex Fridman (1:54:21.700)

But even for Einstein, from the point where he had

Peter Woit (1:54:24.540)

kind of a general idea of what he was trying to do

Lex Fridman (1:54:26.820)

to the point where he actually had a well defined theory

Peter Woit (1:54:29.900)

that you could actually compare to the real world,

Lex Fridman (1:54:31.840)

that was, I forget the number of the order of magnitude,

Peter Woit (1:54:35.340)

10 years of very serious work.

Lex Fridman (1:54:36.720)

And if he hadn't been around to do that,

Peter Woit (1:54:39.740)

it would have taken a while before anyone else

Lex Fridman (1:54:41.900)

got around to it.

Peter Woit (1:54:43.060)

On the other hand, there are things like,

Lex Fridman (1:54:45.020)

with quantum mechanics, you have Heisenberg and Schrodinger

Peter Woit (1:54:51.260)

came up with two, which ultimately equivalent,

Lex Fridman (1:54:55.140)

but two different approaches to it

Peter Woit (1:54:58.180)

within months of each other.

Lex Fridman (1:54:59.620)

And so if Heisenberg hadn't been there,

Peter Woit (1:55:02.380)

you already would have had Schrodinger or whatever.

Lex Fridman (1:55:04.020)

And if neither of them had been there,

Peter Woit (1:55:05.180)

it would have been somebody else a few months later.

Lex Fridman (1:55:07.580)

So there are times when the, just the,

Peter Woit (1:55:12.420)

a lot often is the combination of the right ideas

Lex Fridman (1:55:16.540)

are in place and the right experimental data is in place

Peter Woit (1:55:19.600)

to point in the right direction.

Lex Fridman (1:55:20.780)

And it's just waiting for somebody who's gonna find it.

Peter Woit (1:55:25.620)

Maybe to go back to your aliens,

Lex Fridman (1:55:28.380)

I guess the one thing that I often wonder about aliens is,

Peter Woit (1:55:30.780)

would they have the same fundamental physics ideas

Lex Fridman (1:55:33.940)

as we have in mathematics?

Peter Woit (1:55:35.600)

Would their math, you know, would they, you know,

Lex Fridman (1:55:39.660)

how much is this really intrinsic to our minds?

Peter Woit (1:55:42.140)

If you start out with a different kind of mind

Lex Fridman (1:55:43.780)

when you end up with a different ideas

Peter Woit (1:55:46.140)

of what fundamental physics is

Lex Fridman (1:55:47.340)

or what the structure of mathematics is.

Lex Fridman (1:55:49.820)

So this is why, like if I was, you know,

Lex Fridman (1:55:54.160)

I like video games, the way I would do it

Peter Woit (1:55:56.460)

as a curious being, so first experiment I'd like to do

Lex Fridman (1:55:59.560)

is run Earth over many thousands of times

Lex Fridman (1:56:02.560)

and see if our particular, no, you know what?

Lex Fridman (1:56:06.700)

I wouldn't do the full evolution.

Peter Woit (1:56:08.140)

I would start at Homo sapiens first

Lex Fridman (1:56:10.180)

and then see the evolution of Homo sapiens

Peter Woit (1:56:12.620)

millions of times and see how the ideas

Lex Fridman (1:56:15.620)

of science would evolve.

Lex Fridman (1:56:16.500)

Like, would you get, like how would physics evolve?

Lex Fridman (1:56:19.700)

How would math evolves?

Peter Woit (1:56:21.340)

I would particularly just be curious

Lex Fridman (1:56:22.720)

about the notation they come up with.

Peter Woit (1:56:25.920)

Every once in a while I would like throw miracles

Lex Fridman (1:56:28.420)

at them to like, to mess with them and stuff.

Lex Fridman (1:56:31.180)

And then I would also like to run Earth

Lex Fridman (1:56:33.260)

from the very beginning to see if evolution

Peter Woit (1:56:35.460)

will produce different kinds of brains

Lex Fridman (1:56:37.220)

that would then produce different kinds

Peter Woit (1:56:38.820)

of mathematics and physics.

Lex Fridman (1:56:40.220)

And then finally, I would probably millions of times

Peter Woit (1:56:43.460)

run the universe over to see what kind of,

Lex Fridman (1:56:48.460)

what kind of environments and what kind of life

Peter Woit (1:56:52.260)

would be created to then lead to intelligent life,

Lex Fridman (1:56:55.400)

to then lead to theories of mathematics and physics

Lex Fridman (1:56:59.100)

and to see the full range.

Lex Fridman (1:57:00.840)

And like, sort of like Darwin kind of mark, okay.

Peter Woit (1:57:04.940)

It took them, what is it, several hundred million years

Lex Fridman (1:57:10.260)

to come up with calculus.

Peter Woit (1:57:13.780)

I would just like keep noting how long it took

Lex Fridman (1:57:16.020)

and get an average and see which ideas are difficult,

Peter Woit (1:57:19.020)

which are not and then conclusively sort of figure out

Lex Fridman (1:57:23.420)

if it's more collective intelligence

Peter Woit (1:57:27.340)

or singular intelligence that's responsible for shifts

Lex Fridman (1:57:30.180)

and for big phase shifts and breakthroughs in science.

Peter Woit (1:57:33.820)

If I was playing a video game and ran,

Lex Fridman (1:57:36.380)

I got a chance to run this whole thing.

Peter Woit (1:57:38.260)

Yeah, but we're talking about books

Lex Fridman (1:57:41.620)

before I distracted us horribly.

Peter Woit (1:57:42.460)

About books, okay, so books, yeah, go back, books.

Lex Fridman (1:57:44.420)

Yeah, so and then, yeah, so that's one thing I'd recommend

Peter Woit (1:57:47.180)

is the books about the, from the original people,

Lex Fridman (1:57:50.660)

especially Heisenberg about the, how that happened.

Lex Fridman (1:57:53.640)

And there's also a very, very good kind of history

Lex Fridman (1:57:55.740)

of the kind of what happened during this 20th century

Peter Woit (1:58:00.460)

in physics and up to the time of the Standard Model in 1973.

Lex Fridman (1:58:05.300)

It's called The Second Creation by Bob Kreis and Mann.

Peter Woit (1:58:10.380)

That's one of the best ones.

Lex Fridman (1:58:11.500)

I know that's, but the one thing that I can say is that,

Lex Fridman (1:58:14.780)

so that book, I think, I forget when it was, late 80s, 90s.

Lex Fridman (1:58:20.320)

The problem is that there just hasn't been much

Peter Woit (1:58:22.200)

that's actually worked out since then.

Lex Fridman (1:58:24.060)

So most of the books that are kind of trying to tell you

Peter Woit (1:58:26.660)

about all the glorious things that have happened

Lex Fridman (1:58:28.400)

since 1973 are, they're mostly telling you

Peter Woit (1:58:32.660)

about how glorious things are,

Lex Fridman (1:58:33.900)

which actually don't really work.

Lex Fridman (1:58:35.260)

And it's really, the argument people sometimes make

Lex Fridman (1:58:38.580)

in favor of these books as well, oh, they're really great

Peter Woit (1:58:41.540)

because you want to do something that will get kids excited.

Lex Fridman (1:58:43.780)

And then, so they're getting excited about things,

Peter Woit (1:58:45.780)

something that's not really quite working.

Lex Fridman (1:58:47.700)

It doesn't really matter, the main thing is get them excited.

Peter Woit (1:58:50.720)

The other argument is, wait a minute,

Lex Fridman (1:58:53.580)

if you're getting people excited about ideas that are wrong,

Peter Woit (1:58:56.720)

you're really kind of, you're actually kind of discrediting

Lex Fridman (1:58:59.000)

the whole scientific enterprise in a not really good way.

Lex Fridman (1:59:02.220)

So there's this problem.

Lex Fridman (1:59:04.620)

So my general feeling about expository stuff is, yeah,

Peter Woit (1:59:07.940)

it's to the extent you can do it kind of honestly

Lex Fridman (1:59:10.660)

and, well, that's great.

Peter Woit (1:59:12.780)

There are a lot of people doing that now,

Lex Fridman (1:59:14.760)

but to the extent that you're just trying to get people

Peter Woit (1:59:20.180)

excited and enthusiastic by kind of telling them stuff,

Lex Fridman (1:59:22.940)

which isn't really true,

Peter Woit (1:59:24.420)

you really shouldn't be doing that.

Lex Fridman (1:59:26.540)

You obviously have a much better intuition about physics.

Peter Woit (1:59:28.980)

I tend to, in the space of AI, for example,

Lex Fridman (1:59:32.660)

you could use certain kinds of language,

Peter Woit (1:59:37.620)

like calling things intelligent

Lex Fridman (1:59:41.300)

that could rub people the wrong way.

Lex Fridman (1:59:43.340)

But I never had a problem with that kind of thing,

Lex Fridman (1:59:46.060)

saying that a program can learn its way

Peter Woit (1:59:48.340)

without any human supervision as AlphaZero does

Lex Fridman (1:59:52.180)

to play chess.

Peter Woit (1:59:53.720)

To me, that may not be intelligence,

Lex Fridman (1:59:57.820)

but it sure as heck seems like a few steps

Peter Woit (20:02.040)

There's an idea that I kind of went, got a physics PhD

Lex Fridman (20:05.320)

and spent a lot of time learning about mathematics

Lex Fridman (20:07.120)

and I guess it was embarrassing

Lex Fridman (20:10.000)

that I hadn't really actually understand

Peter Woit (20:11.720)

this very simple idea until I kind of learned it

Lex Fridman (20:15.560)

when I actually started teaching math classes,

Peter Woit (20:18.160)

which is maybe that there's a simple way

Lex Fridman (20:23.320)

to explain kind of the fundamental way

Peter Woit (20:24.840)

in which algebra and geometry are connected.

Lex Fridman (20:28.080)

So you normally think of geometry as about these spaces

Lex Fridman (20:31.680)

and these points and you think of algebra

Lex Fridman (20:35.000)

as this very abstract thing about these abstract objects

Peter Woit (20:38.800)

that satisfy certain kinds of relations,

Lex Fridman (20:40.680)

you can multiply them and add them and do stuff

Lex Fridman (20:44.360)

but it's completely abstract,

Lex Fridman (20:45.960)

there's nothing geometric about it

Lex Fridman (20:47.720)

but the kind of really fundamental idea

Lex Fridman (20:51.680)

is that unifies algebra and geometry

Peter Woit (20:54.680)

is to think whenever anybody gives you

Lex Fridman (20:58.800)

what you call an algebra, some abstract thing

Peter Woit (21:01.920)

of things that you can multiply and add

Lex Fridman (21:04.280)

that you should ask yourself,

Lex Fridman (21:06.400)

is that algebra the space of functions on some geometry?

Lex Fridman (21:10.640)

So one of the most surprising examples of this,

Peter Woit (21:12.560)

for instance, is a standard kind of thing

Lex Fridman (21:16.840)

that seems to have nothing to do with geometry

Peter Woit (21:18.640)

is the integers.

Lex Fridman (21:21.920)

So you can multiply them and add them, it's an algebra

Lex Fridman (21:26.920)

but it seems to have nothing to do with geometry

Lex Fridman (21:31.000)

but what you can, it turns out,

Lex Fridman (21:32.160)

but if you ask yourself this question

Lex Fridman (21:33.720)

and ask, you know, are integers,

Lex Fridman (21:36.240)

can you think, if somebody gives you an integer,

Lex Fridman (21:37.760)

can you think of it as a function on some space,

Lex Fridman (21:40.800)

on some geometry?

Lex Fridman (21:42.200)

And it turns out that yes, you can

Lex Fridman (21:44.280)

and the space is the space of prime numbers

Lex Fridman (21:47.240)

and so what you do is you just,

Peter Woit (21:48.600)

if somebody gives you an integer,

Lex Fridman (21:50.400)

you can make a function on the prime numbers

Peter Woit (21:53.120)

by just, you know, at each prime number taking that,

Lex Fridman (21:56.960)

that integer modulo that prime.

Lex Fridman (21:58.880)

So if you say, I don't know, if you're given 10,

Lex Fridman (22:02.480)

you know, 10 and you ask, what is its value at two?

Peter Woit (22:05.560)

Well, it's five times two, so mod two, it's zero,

Lex Fridman (22:09.600)

so it's zero one.

Lex Fridman (22:10.640)

What is its value at three?

Lex Fridman (22:13.640)

Well, it's nine plus one, so it's one mod three.

Lex Fridman (22:17.400)

So it's zero at two, it's one at three

Lex Fridman (22:19.920)

and you can kind of keep going.

Lex Fridman (22:21.880)

And so this is really kind of a truly fundamental idea.

Lex Fridman (22:26.960)

It's at the basis of what's called algebraic geometry

Lex Fridman (22:29.240)

and it just links these two parts of mathematics

Lex Fridman (22:31.400)

that look completely different

Lex Fridman (22:32.920)

and it's just an incredibly powerful idea

Lex Fridman (22:35.120)

and so much of mathematics emerges

Peter Woit (22:37.240)

from this kind of simple relation.

Lex Fridman (22:39.760)

So you're talking about mapping

Peter Woit (22:41.760)

from one discrete space to another.

Lex Fridman (22:44.720)

So for a second, I thought perhaps mapping

Peter Woit (22:49.600)

like a continuous space to a discrete space,

Lex Fridman (22:51.600)

like functions over a continuous space, because yeah.

Peter Woit (22:56.320)

Well, I mean, you can take, if somebody gives you a space,

Lex Fridman (23:00.000)

you can ask, you can say, well, let's,

Lex Fridman (23:03.200)

and this is also, this is part of the same idea.

Lex Fridman (23:05.240)

The part of the same idea is that if you try

Lex Fridman (23:07.000)

and do geometry and somebody tells you, here's a space,

Lex Fridman (23:10.560)

that what you should do is you should wait,

Lex Fridman (23:11.920)

so say, wait a minute,

Lex Fridman (23:12.760)

maybe I should be trying to solve this using algebra.

Lex Fridman (23:15.760)

And so if I do that, the way to start is,

Lex Fridman (23:18.280)

you give me the space,

Lex Fridman (23:19.680)

I start to think about the functions of the space, okay?

Lex Fridman (23:22.800)

So for each point in the space, I associate a number.

Peter Woit (23:26.160)

I can take different kinds of functions

Lex Fridman (23:27.600)

and different kinds of values,

Lex Fridman (23:29.080)

but basically functions on a space.

Lex Fridman (23:31.560)

So what this insight is telling you is that

Peter Woit (23:36.280)

if you're a geometer, often the way to work

Lex Fridman (23:39.640)

is to change your problem into algebra

Peter Woit (23:41.920)

by changing your space, stop thinking about your space

Lex Fridman (23:44.840)

and the points in it and think about the functions on it.

Lex Fridman (23:47.640)

And if you're an algebraist

Lex Fridman (23:49.760)

and you've got these abstract algebraic gadgets

Peter Woit (23:52.240)

that you're multiplying and adding, say, wait a minute,

Lex Fridman (23:55.080)

are those gadgets, can I think of them in some way

Lex Fridman (23:58.520)

as a function on a space?

Lex Fridman (23:59.680)

What would that space be

Lex Fridman (24:00.760)

and what kind of functions would they be?

Lex Fridman (24:02.880)

And that going back and forth really brings

Peter Woit (24:05.720)

these two completely different looking areas

Lex Fridman (24:08.200)

of mathematics together.

Lex Fridman (24:09.600)

Do you have particular examples where it allowed

Lex Fridman (24:13.400)

to prove some difficult things

Lex Fridman (24:15.000)

by jumping from one to the other?

Lex Fridman (24:16.760)

Is that something that's a part of modern mathematics

Lex Fridman (24:19.680)

where such jumps are made?

Lex Fridman (24:21.680)

Oh yeah, this is kind of all the time.

Peter Woit (24:23.720)

Much of modern number theory is kind of based on this idea.

Lex Fridman (24:27.160)

But, and when you start doing this,

Peter Woit (24:29.880)

you start to realize that you need,

Lex Fridman (24:32.880)

what simple things on one side of the algebra

Peter Woit (24:37.520)

start to require you to think about the other side,

Lex Fridman (24:40.920)

about geometry in a new way.

Peter Woit (24:42.360)

You have to kind of get a more sophisticated idea

Lex Fridman (24:44.120)

about geometry, or if you start thinking

Peter Woit (24:46.960)

about the functions on a space,

Lex Fridman (24:49.120)

you may need a more sophisticated kind of algebra.

Lex Fridman (24:52.040)

But in some sense, I mean,

Lex Fridman (24:53.960)

much or most of modern number theory

Peter Woit (24:55.560)

is based upon this move to geometry.

Lex Fridman (24:58.920)

And there's also a lot of geometry

Lex Fridman (25:01.240)

and topology is also based upon, yeah, change.

Lex Fridman (25:05.040)

If you want to understand the topology of something,

Peter Woit (25:06.800)

you look at the functions, you do drum comology

Lex Fridman (25:09.480)

and you get the topology.

Peter Woit (25:12.400)

Anyway.

Lex Fridman (25:13.640)

Well, let me ask you then the ridiculous question.

Peter Woit (25:16.200)

You said that this idea is beautiful.

Lex Fridman (25:18.960)

Can you formalize the definition of the word beautiful?

Lex Fridman (25:22.680)

And why is this beautiful?

Lex Fridman (25:24.880)

First, why is this beautiful?

Lex Fridman (25:26.240)

And second, what is beautiful?

Lex Fridman (25:29.720)

Yeah, well, and I think there are many different things

Peter Woit (25:32.320)

you can find beautiful for different reasons.

Lex Fridman (25:34.120)

I mean, I think in this context, the notion of beauty,

Peter Woit (25:37.900)

I think really is just kind of an idea is beautiful

Lex Fridman (25:41.280)

if it's packages a huge amount of kind of power

Lex Fridman (25:45.720)

and information into something very simple.

Lex Fridman (25:48.800)

So in some sense, you can almost kind of try and measure it

Lex Fridman (25:54.640)

in the sense of what are the implications of this idea?

Lex Fridman (25:58.320)

What non trivial things does it tell you

Lex Fridman (26:00.880)

versus how simply can you express the idea?

Lex Fridman (26:06.320)

And so.

Lex Fridman (26:07.160)

So the level of compression,

Lex Fridman (26:08.520)

what is it correlates with beauty?

Peter Woit (26:12.400)

Yeah, that's one aspect of it.

Lex Fridman (26:15.000)

And so you can start to tell that an idea

Peter Woit (26:16.800)

is becoming uglier and uglier

Lex Fridman (26:18.840)

as you start kind of having to,

Peter Woit (26:21.280)

it doesn't quite do what you want.

Lex Fridman (26:22.360)

So you throw in something else to the idea

Lex Fridman (26:24.560)

and you keep doing that until you get what you want.

Lex Fridman (26:27.360)

But that's how you know you're doing something uglier

Lex Fridman (26:29.560)

and uglier when you have to kind of keep adding

Lex Fridman (26:31.960)

and more into what was originally a fairly simple idea

Lex Fridman (26:36.960)

and making it more and more complicated

Lex Fridman (26:40.380)

to get what you want.

Peter Woit (26:41.820)

Okay, so let's put some philosophical words on the table

Lex Fridman (26:45.340)

and try to make some sense of them.

Peter Woit (26:47.100)

One word is beauty, another one is simplicity

Lex Fridman (26:49.780)

as you mentioned, another one is truth.

Lex Fridman (26:53.300)

So do you have a sense if I give you two theories,

Lex Fridman (26:57.060)

one is simpler, one is more complicated.

Lex Fridman (27:02.480)

Do you have a sense of which one is more likely to be true

Lex Fridman (27:05.820)

to capture deeply the fabric of reality,

Lex Fridman (27:13.240)

the simple one or the more complicated one?

Lex Fridman (27:15.340)

Yeah, I think all of our evidence,

Lex Fridman (27:18.540)

what we see in the history of the subject

Lex Fridman (27:20.100)

is the simpler one though.

Peter Woit (27:22.380)

Often it's a surprise, it's simpler in a surprising way.

Lex Fridman (27:26.300)

But yeah, that we just don't, we just,

Peter Woit (27:31.100)

anyway, the kind of best theories

Lex Fridman (27:32.980)

we've been coming up with are ultimately

Peter Woit (27:35.460)

when properly understood, relatively simple

Lex Fridman (27:38.740)

and much, much simpler than you would expect them to be.

Lex Fridman (27:41.860)

Do you have a good explanation why that is?

Lex Fridman (27:43.500)

Is it just because humans want it to be that way?

Peter Woit (27:46.020)

Are we just like ultra biased

Lex Fridman (27:47.540)

and we just kind of convince ourselves

Lex Fridman (27:51.080)

that simple is better because we find simplicity beautiful?

Lex Fridman (27:53.720)

Or is there something about our actual universe

Lex Fridman (27:57.340)

that at the core is simple?

Lex Fridman (28:00.060)

My own belief is that there is something about a universe

Peter Woit (28:02.980)

that's simple and as I was trying to say that,

Lex Fridman (28:05.580)

there is some kind of fundamental thing about math,

Peter Woit (28:08.020)

physics and all this picture, which is in some sense simple.

Lex Fridman (28:14.500)

It's true that, it's of course true that our minds

Peter Woit (28:18.580)

have certain, are very limited

Lex Fridman (28:20.840)

and can certainly do certain things and not others.

Lex Fridman (28:23.680)

So it's in principle possible

Lex Fridman (28:26.500)

that there's some great insight in,

Peter Woit (28:29.380)

there are a lot of insights into the way the world works,

Lex Fridman (28:31.300)

which just aren't accessible to us because

Peter Woit (28:33.460)

that's not the way our minds work, we don't.

Lex Fridman (28:35.500)

And that what we're seeing, this kind of simplicity

Peter Woit (28:37.340)

is just because that's all we ever have any hope of seeing.

Lex Fridman (28:42.540)

So there's a brilliant physicist

Peter Woit (28:46.120)

by the name of Sabine Hassenfelder

Lex Fridman (28:49.060)

who both agrees and disagrees with you.

Peter Woit (28:51.060)

I suppose agrees that the final answer will be simple.

Lex Fridman (28:57.260)

Yeah.

Lex Fridman (28:58.420)

But simplicity and beauty leads us astray

Lex Fridman (29:01.580)

in the local pockets of scientific progress.

Lex Fridman (29:05.900)

Do you agree with her disagreement

Lex Fridman (29:08.660)

and do you disagree with her agreement?

Lex Fridman (29:11.140)

And agree with the agreement and so on.

Lex Fridman (29:14.060)

Anyway, yes, I found it was really fascinating

Peter Woit (29:17.100)

reading her book and anyway,

Lex Fridman (29:19.420)

I was finding disagreeing with a lot,

Lex Fridman (29:21.420)

but then at the end when she says yes,

Lex Fridman (29:23.340)

when we find, when we actually figure this out,

Peter Woit (29:26.580)

it will be simple and okay, so we agree in the end.

Lex Fridman (29:31.220)

But does beauty lead us astray,

Peter Woit (29:32.860)

which is the core thesis of her work in that book.

Lex Fridman (29:37.620)

I actually, I guess I do disagree with her on that so much.

Peter Woit (29:41.160)

I don't think, and especially,

Lex Fridman (29:42.660)

and I actually fairly strongly disagree with her

Peter Woit (29:44.580)

about sometimes the way she'll refer to math.

Lex Fridman (29:47.180)

And so the problem is, physicists and people in general

Peter Woit (29:51.460)

just refer to it as math and they're often meaning

Lex Fridman (29:56.140)

not what I would call math,

Peter Woit (29:57.220)

which is the interesting ideas of math,

Lex Fridman (29:59.160)

but just some complicated calculation.

Peter Woit (2:00:01.660)

down the path towards intelligence.

Lex Fridman (2:00:04.500)

And so I think that's a very peculiar property

Peter Woit (2:00:09.060)

of systems that can be engineered.

Lex Fridman (2:00:10.860)

So even if the idea is fuzzy,

Peter Woit (2:00:12.460)

even if you're not really sure what intelligence is,

Lex Fridman (2:00:15.180)

or if you don't have a deep fundamental understanding

Peter Woit (2:00:19.500)

or even a model what intelligence is,

Lex Fridman (2:00:21.620)

if you build a system that sure as heck is impressive

Lex Fridman (2:00:24.500)

and showing some of the signs

Lex Fridman (2:00:26.740)

of what previously thought impossible

Peter Woit (2:00:29.740)

for a nonintelligent system,

Lex Fridman (2:00:32.940)

then that's impressive and that's inspiring

Lex Fridman (2:00:34.900)

and that's okay to celebrate.

Lex Fridman (2:00:36.660)

In physics, because you're not engineering anything,

Peter Woit (2:00:39.860)

you're just now swimming in the space,

Lex Fridman (2:00:41.820)

directly when you do theoretical physics,

Peter Woit (2:00:43.940)

that it could be more dangerous.

Lex Fridman (2:00:45.440)

You could be out too far away from shore.

Peter Woit (2:00:48.740)

Yeah, well, the problem, I think physics is,

Lex Fridman (2:00:52.820)

I think it's actually hard for people even to believe

Peter Woit (2:00:55.180)

or really understand how that this particular kind

Lex Fridman (2:01:00.140)

of physics has gotten itself into a really unusual

Lex Fridman (2:01:02.900)

and strange and historically unusual state,

Lex Fridman (2:01:05.300)

which is not really.

Peter Woit (2:01:06.660)

I mean, I spent half my life among mathematicians

Lex Fridman (2:01:09.500)

and half of the physicists,

Lex Fridman (2:01:10.620)

and mathematics is kind of doing fine.

Lex Fridman (2:01:12.860)

People are making progress

Lex Fridman (2:01:14.180)

and it has all the usual problems,

Lex Fridman (2:01:16.100)

but also, so you could have a,

Lex Fridman (2:01:19.340)

but I just, I don't know,

Lex Fridman (2:01:21.100)

I've never seen anything at all happening in mathematics

Peter Woit (2:01:23.780)

like what's happened in this specific area in physics.

Lex Fridman (2:01:26.340)

It's just the kind of sociology of this,

Peter Woit (2:01:29.820)

the way this field works banging up

Lex Fridman (2:01:33.580)

against this harder problem without anything

Peter Woit (2:01:37.080)

from experiment to help it.

Lex Fridman (2:01:38.560)

It's really, it's led to some really kind

Peter Woit (2:01:41.780)

of problematic things.

Lex Fridman (2:01:43.300)

And those, so it's one thing to kind of oversimplify

Peter Woit (2:01:48.020)

or to slightly misrepresent,

Lex Fridman (2:01:49.740)

to try to explain things in a way that's not quite right,

Lex Fridman (2:01:52.380)

but it's another thing to start promoting to people

Lex Fridman (2:01:56.740)

as a success as ideas, which really completely failed.

Lex Fridman (2:02:00.300)

And so, I mean, I've kind of a very, very specific,

Lex Fridman (2:02:03.600)

if you used to have people, I won't name any names,

Peter Woit (2:02:07.500)

for instance, coming on certain podcasts like yours,

Lex Fridman (2:02:09.500)

telling the world, this is a huge success

Lex Fridman (2:02:12.560)

and this is really wonderful.

Lex Fridman (2:02:13.740)

And it's just not true.

Lex Fridman (2:02:16.520)

And this is really problematic

Lex Fridman (2:02:19.620)

and it carries a serious danger of once,

Peter Woit (2:02:24.460)

when people realize that this is what's going on,

Lex Fridman (2:02:29.020)

that the loss of credibility of science

Peter Woit (2:02:32.380)

is a real, real problem for our society.

Lex Fridman (2:02:34.700)

And you don't want people to have an all too good reason

Peter Woit (2:02:39.700)

to think that what they're being told

Lex Fridman (2:02:44.420)

by kind of some of the best institutions

Peter Woit (2:02:46.860)

or a country or authorities is not true.

Lex Fridman (2:02:49.140)

You know, it's not true, it's a problem.

Peter Woit (2:02:52.300)

That's obviously characteristic of not just physics,

Lex Fridman (2:02:55.860)

it's sociology.

Lex Fridman (2:03:00.500)

And it's, I mean, obviously in the space of politics,

Lex Fridman (2:03:02.940)

it's the history of politics is you sell ideas to people,

Peter Woit (2:03:11.940)

even when you don't have any proof

Lex Fridman (2:03:14.020)

that those ideas actually work in the US

Peter Woit (2:03:16.060)

because if they've worked in that,

Lex Fridman (2:03:17.980)

that seems to be the case throughout history.

Lex Fridman (2:03:23.700)

And just like you said, it's human beings running up

Lex Fridman (2:03:26.500)

against a really hard problem.

Peter Woit (2:03:28.500)

I'm not sure if this is like a particular like trajectory

Lex Fridman (2:03:35.420)

through the progress of physics

Peter Woit (2:03:37.060)

that we're dealing with now

Lex Fridman (2:03:38.380)

or it's just a natural progress of science.

Peter Woit (2:03:40.240)

You run up against a really difficult stage of a field

Lex Fridman (2:03:44.800)

and different people behave differently in the face of that.

Peter Woit (2:03:53.100)

Some sell books and sort of tell narratives

Lex Fridman (2:03:56.140)

that are beautiful and so on.

Peter Woit (2:03:57.820)

They're not necessarily grounded in solutions

Lex Fridman (2:04:00.980)

that have proven themselves.

Peter Woit (2:04:02.740)

Others kind of put their head down quietly,

Lex Fridman (2:04:05.460)

keep doing the work.

Peter Woit (2:04:06.340)

Others sort of pivot to different fields

Lex Fridman (2:04:08.180)

and that's kind of like, yeah, ants scattering.

Lex Fridman (2:04:11.420)

And then you have fields like machine learning,

Lex Fridman (2:04:14.500)

which there was a few folks mostly scattered away

Peter Woit (2:04:17.100)

from machine learning in the 90s,

Lex Fridman (2:04:19.580)

in the winter of AI, AI winter, as they call it.

Lex Fridman (2:04:22.980)

But a few people kept their head down

Lex Fridman (2:04:24.740)

and now they're called the fathers of deep learning.

Lex Fridman (2:04:27.140)

And they didn't think of it that way.

Lex Fridman (2:04:31.380)

And in fact, if there's another AI winter,

Peter Woit (2:04:33.300)

they'll just probably keep working on it anyway,

Lex Fridman (2:04:35.560)

sort of like loyal ants sticking to a particular thing.

Lex Fridman (2:04:40.380)

So it's interesting, but you're sort of saying

Lex Fridman (2:04:43.140)

that we should be careful over hyping things

Peter Woit (2:04:46.660)

that have not proven themselves

Lex Fridman (2:04:48.380)

because people will lose trust in the scientific process.

Lex Fridman (2:04:53.380)

But unfortunately, there's been other ways

Lex Fridman (2:04:56.780)

in which people have lost trust in the scientific process.

Peter Woit (2:04:59.740)

That ultimately has to do actually

Lex Fridman (2:05:01.140)

with all the same kind of behavior as you're highlighting,

Peter Woit (2:05:04.020)

which is not being honest and transparent

Lex Fridman (2:05:07.260)

about the flaws of mistakes of the past.

Peter Woit (2:05:10.620)

Yeah, I mean, that's always a problem.

Lex Fridman (2:05:12.140)

But this particular field is kind of fun.

Peter Woit (2:05:14.700)

It's always a strange one.

Lex Fridman (2:05:17.780)

I mean, I think in the sense that

Peter Woit (2:05:20.500)

there's a lot of public fascination with it

Lex Fridman (2:05:22.140)

that it seems to speak to kind of our deepest questions

Lex Fridman (2:05:24.780)

about what is this physical reality?

Lex Fridman (2:05:27.540)

Where do we come from?

Lex Fridman (2:05:28.380)

And these kind of deep issues.

Lex Fridman (2:05:30.300)

So there's this unusual fascination with it.

Peter Woit (2:05:33.060)

Mathematics is very different.

Lex Fridman (2:05:34.540)

Nobody's that interested in mathematics.

Peter Woit (2:05:36.620)

Nobody really kind of expects to learn really great,

Lex Fridman (2:05:40.580)

deep things about the world from mathematics that much.

Peter Woit (2:05:42.580)

They don't ask mathematicians that.

Lex Fridman (2:05:44.180)

So it's a very unusual,

Peter Woit (2:05:46.660)

it draws this kind of unusual amount of attention.

Lex Fridman (2:05:50.140)

And it really is historically in a really unusual state.

Peter Woit (2:05:54.860)

It's gotten itself way kind of down a blind alley

Lex Fridman (2:06:01.220)

in a way which it's hard to find

Peter Woit (2:06:04.700)

other historical parallels to.

Lex Fridman (2:06:06.500)

But sort of to push back a little bit,

Peter Woit (2:06:08.380)

there's power to inspiring people.

Lex Fridman (2:06:10.660)

And if I just empirically look,

Peter Woit (2:06:13.140)

physicists are really good at combining science

Lex Fridman (2:06:21.740)

and philosophy and communicating it.

Peter Woit (2:06:24.420)

Like there's something about physics often

Lex Fridman (2:06:26.220)

that forces you to build a strong intuition

Lex Fridman (2:06:28.900)

about the way reality works, right?

Lex Fridman (2:06:31.300)

And that allows you to think through sort of

Lex Fridman (2:06:34.260)

and communicate about all kinds of questions.

Lex Fridman (2:06:37.340)

Like if you see physicists,

Peter Woit (2:06:38.780)

it's always fascinating to take on problems

Lex Fridman (2:06:41.140)

that have nothing to do with their particular discipline.

Peter Woit (2:06:43.500)

They think in interesting ways

Lex Fridman (2:06:45.900)

and they're able to communicate

Peter Woit (2:06:47.180)

their thinking in interesting ways.

Lex Fridman (2:06:48.660)

And so in some sense, they have a responsibility

Peter Woit (2:06:52.180)

not just to do science, but to inspire.

Lex Fridman (2:06:55.580)

And not responsibility, but the opportunity.

Lex Fridman (2:06:58.060)

And thereby, I would say a little bit of a responsibility.

Lex Fridman (2:07:02.660)

Yeah, yeah.

Lex Fridman (2:07:03.820)

But I don't know, anyway, it's hard to say

Lex Fridman (2:07:06.340)

because there's many, many people doing this kind of thing

Peter Woit (2:07:10.620)

with different degrees of success and whatever.

Lex Fridman (2:07:15.580)

I guess one thing, but I mean,

Peter Woit (2:07:19.740)

what's kind of front and center for me

Lex Fridman (2:07:21.140)

is kind of a more parochial interest

Peter Woit (2:07:22.860)

is just kind of what damage do you do

Lex Fridman (2:07:27.100)

to the subject itself, ignoring,

Peter Woit (2:07:30.100)

okay, misrepresenting what high school students think

Lex Fridman (2:07:33.460)

about string theory and that doesn't matter much,

Lex Fridman (2:07:36.540)

but what the smartest undergraduates

Lex Fridman (2:07:40.220)

or the smartest graduate students in the world think about it

Lex Fridman (2:07:43.140)

and what paths you're leading them down

Lex Fridman (2:07:45.140)

and what story you're telling them

Lex Fridman (2:07:47.060)

and what textbooks you're making them read

Lex Fridman (2:07:49.580)

and what they're hearing.

Lex Fridman (2:07:51.380)

And so a lot of what's motivated me

Lex Fridman (2:07:53.020)

is more to try to speak to this kind of a specific population

Peter Woit (2:07:57.340)

of people to make sure that, look, people,

Lex Fridman (2:08:01.660)

it doesn't matter so much what the average person

Peter Woit (2:08:05.500)

on the street thinks about string theory,

Lex Fridman (2:08:06.980)

but what the best students at Columbia or Harvard

Peter Woit (2:08:12.060)

or Princeton or whatever who really wanna change,

Lex Fridman (2:08:14.860)

work in this field and wanna work that way,

Lex Fridman (2:08:16.620)

what they know about it, what they think about it

Lex Fridman (2:08:19.300)

and that they not be going to the field being misled

Lex Fridman (2:08:22.020)

and believing that a certain story,

Lex Fridman (2:08:23.820)

this is where this is all going,

Peter Woit (2:08:25.060)

this is what I gotta do, that's important to me.

Lex Fridman (2:08:29.020)

Well, in general, for graduate students,

Peter Woit (2:08:31.380)

for people who seek to be experts in the field,

Lex Fridman (2:08:34.220)

diversity of ideas is really powerful

Lex Fridman (2:08:36.460)

and is getting into this local pocket of ideas

Lex Fridman (2:08:40.700)

that people hold on to for several decades is not good,

Peter Woit (2:08:43.820)

no matter what the idea.

Lex Fridman (2:08:44.860)

I would say no matter if the idea is right or wrong,

Peter Woit (2:08:47.860)

because there's no such thing as right in the long term,

Lex Fridman (2:08:51.540)

like it's right for now until somebody builds on

Peter Woit (2:08:56.380)

something much bigger on top of it.

Lex Fridman (2:08:58.100)

It might end up being right,

Lex Fridman (2:09:00.060)

but being a tiny subset of a much bigger thing.

Lex Fridman (2:09:03.500)

So you always should question sort of the ways of the past.

Peter Woit (2:09:07.460)

Yeah, so how to kind of achieve

Lex Fridman (2:09:10.260)

that kind of diversity of thought

Lex Fridman (2:09:12.700)

and within kind of the sociology

Lex Fridman (2:09:15.060)

of how we organize scientific researches.

Peter Woit (2:09:17.660)

I know this is one thing that I think it's very interesting

Lex Fridman (2:09:19.500)

that Sabina Hassenfelder has very interesting things

Peter Woit (2:09:22.700)

to say about it.

Lex Fridman (2:09:23.540)

And I think also Lee Smolin in his book,

Peter Woit (2:09:25.540)

which is also about that very much in agreement with them

Lex Fridman (2:09:29.900)

that there's a really kind of important questions

Peter Woit (2:09:36.780)

about how research in this field is organized

Lex Fridman (2:09:41.460)

and what can you do to kind of get more diversity of thought

Lex Fridman (2:09:46.580)

and get people thinking about a wider range of ideas.

Lex Fridman (2:09:53.100)

At the bottom, I think humility always helps.

Peter Woit (2:09:55.980)

Well, the problem is that it's also,

Lex Fridman (2:09:59.900)

it's a combination of humility to know when you're wrong

Lex Fridman (2:10:02.780)

and also, but also you have to have a certain

Lex Fridman (2:10:06.700)

very serious lack of humility to believe

Peter Woit (2:10:08.620)

that you're gonna make progress on some of these problems.

Lex Fridman (2:10:11.180)

I think you have to have like both modes

Lex Fridman (2:10:13.260)

and switch between them when needed.

Lex Fridman (2:10:18.420)

Let me ask you a question

Peter Woit (2:10:19.460)

you're probably not gonna wanna answer

Lex Fridman (2:10:21.220)

because you're focused on the mathematics of things

Lex Fridman (2:10:25.460)

and mathematics can't answer the why questions,

Lex Fridman (2:10:27.720)

but let me ask you anyway.

Lex Fridman (2:10:30.620)

Do you think there's meaning to this whole thing?

Lex Fridman (2:10:33.420)

What do you think is the meaning of life?

Lex Fridman (2:10:34.980)

Why are we here?

Lex Fridman (2:10:36.860)

I don't know.

Peter Woit (2:10:37.700)

Yeah, I was thinking about this.

Lex Fridman (2:10:39.580)

So the, and it did occur to me,

Peter Woit (2:10:42.300)

one interesting thing about that question

Lex Fridman (2:10:45.660)

is that you don't,

Peter Woit (2:10:47.180)

yeah, so I have this life in mathematics

Lex Fridman (2:10:51.060)

and this life in physics

Lex Fridman (2:10:52.020)

and I see some of my physicist colleagues,

Lex Fridman (2:10:55.900)

kind of seem to be, people are often asking them,

Lex Fridman (2:10:59.740)

what's the meaning of life?

Lex Fridman (2:11:00.580)

And they're writing books about the meaning of life

Lex Fridman (2:11:02.300)

and teaching courses about the meaning of life.

Lex Fridman (2:11:04.580)

But then I realized that no one ever asked

Peter Woit (2:11:06.460)

my mathematician colleagues.

Lex Fridman (2:11:08.980)

Nobody ever asked mathematicians.

Peter Woit (2:11:10.660)

Yeah, that's funny.

Lex Fridman (2:11:11.500)

So yeah, everybody just kind of assumes,

Peter Woit (2:11:15.020)

okay, well, you people are studying mathematics,

Lex Fridman (2:11:16.620)

whatever you're doing, it's maybe very interesting,

Lex Fridman (2:11:19.380)

but it's clearly not gonna tell me anything useful

Lex Fridman (2:11:21.180)

about the meaning of my life.

Lex Fridman (2:11:22.300)

And I'm afraid a lot of my point of view is that

Lex Fridman (2:11:25.820)

if people realized how little difference there was

Peter Woit (2:11:28.180)

between what the mathematicians are doing

Lex Fridman (2:11:29.700)

and what a lot of these theoretical physicists are doing,

Peter Woit (2:11:32.260)

they might understand that it's a bit misguided

Lex Fridman (2:11:35.740)

to look for deep insight into the meaning of life

Peter Woit (2:11:39.020)

from many theoretical physicists.

Lex Fridman (2:11:42.540)

It's not, they're people,

Peter Woit (2:11:45.580)

they may have interesting things to say about this.

Lex Fridman (2:11:47.220)

You're right, they know a lot about physical reality

Lex Fridman (2:11:50.220)

and about, in some sense about metaphysics,

Lex Fridman (2:11:53.900)

about what is real of this kind.

Lex Fridman (2:11:56.740)

But you're also, to my mind,

Lex Fridman (2:12:02.260)

I think you're also making a bit of a mistake

Peter Woit (2:12:03.740)

that you're looking to, I mean, I'm very, very aware

Lex Fridman (2:12:07.940)

that I've led a very pleasant

Lex Fridman (2:12:10.620)

and fairly privileged existence

Lex Fridman (2:12:11.980)

and fairly without many challenges of different kinds

Lex Fridman (2:12:15.220)

and of a certain kind.

Lex Fridman (2:12:16.700)

And I'm really not in no way the kind of person

Peter Woit (2:12:21.460)

that a lot of people who are looking for

Lex Fridman (2:12:24.260)

to try to understand in some sense the meaning of life

Peter Woit (2:12:27.460)

in the sense of the challenges that they're facing in life.

Lex Fridman (2:12:30.300)

I can't really, I'm really the wrong person

Peter Woit (2:12:32.660)

for you to be asking about this.

Lex Fridman (2:12:34.020)

Well, if struggle is somehow a thing that's core to meaning,

Peter Woit (2:12:39.660)

perhaps mathematicians are just quietly the ones

Lex Fridman (2:12:42.460)

who are most equipped to answer that question

Peter Woit (2:12:45.140)

if, in fact, the creation or at least experiencing beauty

Lex Fridman (2:12:53.660)

is at the core of the meaning of life.

Peter Woit (2:12:55.860)

Because it seems like mathematics is the methodology

Lex Fridman (2:12:59.420)

by which you can most purely explore beautiful things, right?

Peter Woit (2:13:04.060)

Yeah, yeah.

Lex Fridman (2:13:05.280)

So in some sense,

Peter Woit (2:13:06.220)

maybe we should talk to mathematicians more.

Lex Fridman (2:13:08.900)

Yeah, yeah, maybe, but unfortunately,

Peter Woit (2:13:12.620)

people do have a somewhat correct perception

Lex Fridman (2:13:14.900)

that what these people are doing every day

Peter Woit (2:13:17.100)

or whatever is pretty far removed from anything.

Lex Fridman (2:13:21.940)

Yeah, from what's kind of close to what I do every day

Lex Fridman (2:13:26.140)

and what my typical concerns are.

Lex Fridman (2:13:28.060)

So you may learn something very interesting

Peter Woit (2:13:29.740)

by talking to mathematicians,

Lex Fridman (2:13:31.060)

but it's probably not gonna be,

Peter Woit (2:13:33.940)

you're probably not gonna get what you were hoping.

Lex Fridman (2:13:37.120)

So when you put the pen and paper down,

Peter Woit (2:13:39.540)

you're not thinking about physics

Lex Fridman (2:13:41.460)

and you're not thinking about mathematics

Lex Fridman (2:13:43.380)

and you just get to breathe in the air and look around you

Lex Fridman (2:13:46.820)

and realize that you're going to die one day.

Peter Woit (2:13:49.220)

Yeah.

Lex Fridman (2:13:50.060)

Do you think about that?

Peter Woit (2:13:53.300)

Your ideas will live on, but you, the human.

Lex Fridman (2:13:56.940)

Not especially much.

Peter Woit (2:13:58.460)

Certainly, I've been getting older.

Lex Fridman (2:14:00.180)

I'm now 64 years old.

Peter Woit (2:14:01.900)

You start to realize, well,

Lex Fridman (2:14:02.740)

there's probably less ahead than there was behind.

Lex Fridman (2:14:05.700)

And so you start to, that starts to become,

Lex Fridman (2:14:09.580)

what do I think about that?

Peter Woit (2:14:10.420)

Maybe I should actually get serious

Lex Fridman (2:14:13.420)

about getting some things done,

Peter Woit (2:14:14.740)

which I may not have,

Lex Fridman (2:14:17.020)

which I may otherwise not have time to do,

Peter Woit (2:14:18.740)

which I didn't see.

Lex Fridman (2:14:20.300)

And this didn't seem to be a problem when I was younger,

Lex Fridman (2:14:22.220)

but that's the main,

Lex Fridman (2:14:24.060)

I think the main way in which that thought occurred.

Lex Fridman (2:14:26.860)

But it doesn't, you know, the stoics are big on this.

Lex Fridman (2:14:30.040)

Meditating on mortality helps you

Peter Woit (2:14:33.460)

more intensely appreciate the beauty

Lex Fridman (2:14:36.580)

when you do experience it.

Peter Woit (2:14:38.020)

I suppose that's true, but it's not,

Lex Fridman (2:14:41.140)

yeah, it's not something I've spent a lot of time trying,

Lex Fridman (2:14:45.880)

but yeah.

Lex Fridman (2:14:47.180)

Day to day, you just enjoy the positives, the mathematics.

Peter Woit (2:14:49.780)

Just enjoy, yeah, our life in general.

Lex Fridman (2:14:52.460)

Life is, I have a perfectly pleasant life and enjoy it.

Lex Fridman (2:14:57.120)

And I often think, wow, this is,

Lex Fridman (2:15:00.220)

things are, I'm really enjoying this.

Peter Woit (2:15:02.600)

Things are going well.

Lex Fridman (2:15:04.300)

Yeah, life is pretty amazing.

Peter Woit (2:15:06.540)

I think you and I are pretty lucky.

Lex Fridman (2:15:08.180)

We get to live on this nice little earth

Peter Woit (2:15:11.300)

with a nice little comfortable climate,

Lex Fridman (2:15:13.380)

and we get to have this nice little podcast conversation.

Peter Woit (2:15:17.160)

Thank you so much for spending your valuable time

Lex Fridman (2:15:19.100)

with me today and having this conversation.

Peter Woit (2:15:21.180)

Thank you.

Lex Fridman (2:15:22.020)

Glad to, thank you, thank you.

Peter Woit (2:15:25.220)

Thanks for listening to this conversation with Peter White.

Lex Fridman (2:15:27.960)

To support this podcast,

Peter Woit (2:15:29.260)

please check out our sponsors in the description.

Lex Fridman (2:15:32.060)

And now, let me leave you with some words

Peter Woit (2:15:34.100)

from Richard Feynman.

Lex Fridman (2:15:36.180)

The first principle is that you must not fool yourself,

Lex Fridman (2:15:40.220)

and you are the easiest person to fool.

Lex Fridman (2:15:43.120)

Thank you for listening and hope to see you next time.

Lex Fridman (30:03.260)

And so I guess my feeling about it is more that it's very,

Lex Fridman (30:09.180)

the problem with talking about simplicity

Lex Fridman (30:11.120)

and using simplicity as a guide is that it's very,

Lex Fridman (30:16.140)

it's very easy to fool yourself

Lex Fridman (30:17.620)

and it's very easy to decide to fall in love with an idea.

Lex Fridman (30:23.340)

You have an idea, you think, oh, this is great

Lex Fridman (30:26.000)

and you fall in love with it.

Lex Fridman (30:26.980)

And it's like any kind of love affair,

Peter Woit (30:29.500)

it's very easy to believe that the object of your affections

Lex Fridman (30:32.820)

is much more beautiful than the others might think

Lex Fridman (30:35.300)

and that they really are.

Lex Fridman (30:36.660)

And that's very, very easy to do.

Lex Fridman (30:39.380)

So if you say, I'm just gonna pursue ideas about beauty

Lex Fridman (30:43.980)

and this and mathematics and this,

Peter Woit (30:46.460)

it's extremely easy to just fool yourself, I think.

Lex Fridman (30:50.740)

And I think that's a lot of what the story

Peter Woit (30:54.060)

she was thinking of about where people have gone astray,

Lex Fridman (30:56.260)

that I think it's, I would argue that it's more people,

Peter Woit (30:59.100)

it's not that there was some simple, powerful,

Lex Fridman (31:01.960)

wonderful idea which they'd found

Lex Fridman (31:03.660)

and it turned out not to be useful,

Lex Fridman (31:08.340)

but it was more that they kind of fooled themselves

Peter Woit (31:10.340)

that this was actually a better idea than it really was

Lex Fridman (31:13.080)

and that it was simpler and more beautiful

Peter Woit (31:15.180)

than it really was, is a lot of the story.

Lex Fridman (31:18.860)

I see, so it's not that the simplicity of beauty

Peter Woit (31:20.700)

leads us astray, it's just people are people

Lex Fridman (31:22.900)

and they fall in love with whatever idea they have

Lex Fridman (31:27.180)

and then they weave narratives around that idea

Lex Fridman (31:30.260)

or they present it in such a way

Peter Woit (31:31.540)

that emphasizes the simplicity and the beauty.

Lex Fridman (31:36.740)

Yeah, that's part of it.

Lex Fridman (31:37.960)

But I mean, the thing about physics that you have

Lex Fridman (31:40.840)

is that what really can tell,

Peter Woit (31:44.160)

if you can do an experiment and check

Lex Fridman (31:46.140)

and see if nature is really doing what your idea expects,

Peter Woit (31:50.840)

you do in principle have a way of really testing it

Lex Fridman (31:54.020)

and it's certainly true that if you thought

Peter Woit (31:58.380)

you had a simple idea and that doesn't work

Lex Fridman (32:00.160)

and you go out and do an experiment

Lex Fridman (32:01.900)

and what actually does work is some more,

Lex Fridman (32:04.120)

maybe some more complicated version of it,

Peter Woit (32:05.900)

that can certainly happen and that can be true.

Lex Fridman (32:10.780)

I think her emphasis is more,

Peter Woit (32:13.140)

that I don't really disagree with,

Lex Fridman (32:14.580)

is that people should be concentrating

Peter Woit (32:18.820)

on when they're trying to develop better theories

Lex Fridman (32:21.980)

on more on self consistency, not so much on beauty,

Lex Fridman (32:25.740)

but not is this idea beautiful,

Lex Fridman (32:28.300)

but is there something about the theory

Peter Woit (32:30.400)

which is not quite consistent and use that as a guide

Lex Fridman (32:35.340)

that there's something wrong there which needs fixing.

Lex Fridman (32:37.980)

And so I think that part of her argument,

Lex Fridman (32:40.700)

I think we're on the same page about.

Lex Fridman (32:43.220)

What is consistency and inconsistencies?

Lex Fridman (32:48.300)

What exactly, do you have examples in mind?

Peter Woit (32:53.000)

Well, it can be just simple inconsistency

Lex Fridman (32:55.700)

between theory and an experiment that if you,

Lex Fridman (32:58.700)

so we have this great fundamental theory,

Lex Fridman (33:01.000)

but there are some things that we see out there

Peter Woit (33:02.980)

which don't seem to fit in it,

Lex Fridman (33:04.260)

like dark energy and dark matter, for instance.

Lex Fridman (33:07.500)

But if there's something which you can't test experimentally,

Lex Fridman (33:09.600)

I think she would argue and I would agree

Peter Woit (33:12.020)

that, for instance, if you're trying to think about gravity

Lex Fridman (33:15.100)

and how are you gonna have a quantum theory of gravity,

Peter Woit (33:17.380)

you should kind of test any of your ideas

Lex Fridman (33:21.540)

with kind of a thought experiment.

Peter Woit (33:24.980)

Does this actually give a consistent picture

Lex Fridman (33:26.780)

of what's gonna happen, of what happens

Lex Fridman (33:28.740)

in this particular situation or not?

Lex Fridman (33:32.300)

So this is a good example.

Peter Woit (33:33.460)

You've written about this.

Lex Fridman (33:36.460)

Since quantum gravitational effects are really small,

Peter Woit (33:40.600)

super small, arguably unobservably small,

Lex Fridman (33:44.260)

should we have hope to arrive

Lex Fridman (33:46.480)

at a theory of quantum gravity somehow?

Lex Fridman (33:49.580)

What are the different ways we can get there?

Peter Woit (33:51.540)

You've mentioned that you're not as interested

Lex Fridman (33:53.340)

in that effort because basically, yes,

Peter Woit (33:56.940)

you cannot have ways to scientifically validate it

Lex Fridman (34:02.500)

given the tools of today.

Peter Woit (34:04.160)

Yeah, I've actually, you know, I've over the years

Lex Fridman (34:06.460)

certainly spent a lot of time learning about gravity

Lex Fridman (34:08.900)

and about attempts to quantize it, but it hasn't been

Lex Fridman (34:11.940)

that much in the past the focus

Peter Woit (34:14.060)

of what I've been thinking about.

Lex Fridman (34:16.000)

But I mean, my feeling was always, you know,

Peter Woit (34:18.720)

as I think Sabina would agree that the, you know,

Lex Fridman (34:22.880)

one way you can pursue this if you can't do experiments

Peter Woit (34:25.800)

is just this kind of search for consistency.

Lex Fridman (34:29.140)

You know, it can be remarkably hard to come up

Peter Woit (34:31.840)

with a completely consistent model of this

Lex Fridman (34:34.980)

in a way that brings together quantum mechanics

Lex Fridman (34:37.420)

and general relativity.

Lex Fridman (34:39.420)

And that's, I think, kind of been the traditional way

Peter Woit (34:42.700)

that people who have pursued quantum gravity

Lex Fridman (34:44.440)

have often pursued, you know,

Peter Woit (34:48.340)

we have the best route to finding a consistent theory

Lex Fridman (34:52.420)

of quantum gravity and string theorists will tell you this,

Peter Woit (34:55.740)

other people will tell you it,

Lex Fridman (34:57.120)

it's kind of what people argue about.

Lex Fridman (35:00.060)

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

Lex Fridman (35:03.340)

you know, the danger is that you end up with,

Peter Woit (35:08.620)

that everybody could be successful.

Lex Fridman (35:10.140)

Everybody's program for how to find a theory

Peter Woit (35:14.620)

of quantum gravity, you know, ends up with something

Lex Fridman (35:16.540)

that is consistent.

Lex Fridman (35:18.500)

And so, and in some sense you could argue

Lex Fridman (35:20.780)

this is what happened to the string theorists.

Peter Woit (35:23.860)

They solved their problem of finding a consistent theory

Lex Fridman (35:26.300)

of quantum gravity and they ended up,

Lex Fridman (35:27.800)

but they found 10 to the 500 solutions.

Lex Fridman (35:30.300)

So you, you know, if you believe that everything

Peter Woit (35:34.620)

that they would like to be true is true,

Lex Fridman (35:35.980)

well, okay, you've got a theory,

Lex Fridman (35:38.380)

but it ends up being kind of useless

Lex Fridman (35:41.100)

because it's just one of an infinite,

Peter Woit (35:43.860)

essentially infinite number of things

Lex Fridman (35:46.060)

which you have no way to experimentally distinguish.

Lex Fridman (35:48.340)

And so this is just a depressing situation.

Lex Fridman (35:52.220)

But I do think that there is a,

Lex Fridman (35:55.260)

so again, I think pursuing ideas about what,

Lex Fridman (35:57.780)

more about beauty and how can you integrate

Lex Fridman (36:01.380)

and unify these issues about gravity

Lex Fridman (36:04.340)

with other things we know about physics.

Lex Fridman (36:06.020)

And can you find a theory where these fit together

Lex Fridman (36:08.860)

in a way that makes sense and hopefully predict something.

Peter Woit (36:12.340)

That's much more promising.

Lex Fridman (36:14.020)

Well, it makes sense and hopefully,

Peter Woit (36:15.620)

I mean, we'll sneak up onto this question a bunch of times

Lex Fridman (36:19.620)

because you kind of said a few slightly contradictory things

Peter Woit (36:23.540)

which is like, it's nice to have a theory that's consistent,

Lex Fridman (36:27.220)

but then if the theory is consistent,

Peter Woit (36:29.940)

it doesn't necessarily mean anything.

Lex Fridman (36:32.860)

So like.

Peter Woit (36:33.700)

It's not enough, it's not enough.

Lex Fridman (36:35.220)

It's not enough and that's the problem.

Lex Fridman (36:36.780)

So it's like, it keeps coming back to,

Lex Fridman (36:39.460)

okay, there should be some experimental validation.

Peter Woit (36:43.380)

So, okay, let's talk a little bit about strength theory.

Lex Fridman (36:47.020)

You've been a bit of an outspoken critic of strength theory.

Lex Fridman (36:52.420)

Maybe one question first to ask is what is strength theory?

Lex Fridman (36:56.680)

And beyond that, why is it wrong?

Peter Woit (37:01.900)

Or rather as the title of your blog says, not even wrong.

Lex Fridman (37:06.540)

Okay.

Peter Woit (37:07.900)

Well, one interesting thing

Lex Fridman (37:08.740)

about the current state of strength theory is that,

Peter Woit (37:10.380)

I think it, I'd argue it's actually very, very difficult

Lex Fridman (37:13.340)

to at this point to say what strength theory means.

Peter Woit (37:15.880)

If people say they're a strength theorist,

Lex Fridman (37:17.380)

what they mean and what they're doing

Peter Woit (37:19.820)

is kind of hard to pin down the meaning of the term.

Lex Fridman (37:24.140)

But the initial meaning I think goes back to,

Peter Woit (37:28.380)

there was kind of a series of developments starting in 1984

Lex Fridman (37:32.100)

in which people felt that they had found a unified theory

Peter Woit (37:36.420)

of our so called standard model of all the standard,

Lex Fridman (37:41.300)

well known kind of particle interactions and gravity

Lex Fridman (37:44.620)

and it all fit together in a quantum theory.

Lex Fridman (37:46.620)

And that you could do this in a very specific way

Peter Woit (37:49.940)

by instead of thinking about having a quantum theory

Lex Fridman (37:54.900)

of particles moving around in space time,

Peter Woit (37:57.200)

think about a quantum theory of kind of one dimensional

Lex Fridman (38:00.380)

loops moving around in space time, so called strings.

Lex Fridman (38:03.420)

And so instead of one degree of freedom,

Lex Fridman (38:06.580)

these have an infinite number of degrees of freedom.

Peter Woit (38:08.220)

It's a much more complicated theory, but you can imagine,

Lex Fridman (38:12.300)

okay, we're gonna quantize this theory of loops

Peter Woit (38:14.780)

moving around in space time.

Lex Fridman (38:16.780)

And what they found is that you could do this

Lex Fridman (38:21.160)

and you could fairly, relatively straightforwardly

Lex Fridman (38:23.420)

make sense of such a quantum theory,

Lex Fridman (38:26.900)

but only if space and time together were 10 dimensional.

Lex Fridman (38:31.580)

And so then you had this problem,

Peter Woit (38:32.980)

again, the problem I referred to at the beginning of,

Lex Fridman (38:34.820)

okay, now once you make that move,

Peter Woit (38:37.260)

you gotta get rid of six dimensions.

Lex Fridman (38:39.620)

And so the hope was that you could get rid

Peter Woit (38:42.300)

of the six dimensions by making them very small

Lex Fridman (38:44.820)

and that consistency of the theory would require

Peter Woit (38:48.740)

that these six dimensions satisfy a very specific condition

Lex Fridman (38:52.860)

called being a Calabi out manifold.

Lex Fridman (38:55.180)

And that we knew very, very few examples of this.

Lex Fridman (38:58.300)

So what got a lot of people very excited back in 84, 85

Peter Woit (39:02.340)

was the hope that you could just take

Lex Fridman (39:05.180)

this 10 dimensional string theory

Lex Fridman (39:07.060)

and find one of a limited number of possible ways

Lex Fridman (39:10.900)

of getting rid of six dimensions by making them small

Lex Fridman (39:14.620)

and then you would end up with an effective

Lex Fridman (39:16.700)

four dimensional theory, which looked like the real world.

Peter Woit (39:18.820)

This was the hope.

Lex Fridman (39:20.020)

So then there's then a very long story

Peter Woit (39:22.580)

about what happened to that hope over the years.

Lex Fridman (39:25.900)

I would argue and part of the point of the book

Lex Fridman (39:28.780)

and its title was that this ultimately was a failure

Lex Fridman (39:33.900)

that you ended up, that this idea just didn't,

Peter Woit (39:38.940)

there ended up being just too many ways of doing this

Lex Fridman (39:41.060)

and you didn't know how to do this consistently,

Peter Woit (39:44.100)

that it was kind of not even wrong in the sense

Lex Fridman (39:46.740)

that you couldn't even, you never could pin it down

Peter Woit (39:49.140)

well enough to actually get a real falsifiable prediction

Lex Fridman (39:53.580)

out of it that would tell you it was wrong.

Lex Fridman (39:55.220)

But it was kind of in the realm of ideas

Lex Fridman (39:59.340)

which initially looked good, but the more you look at them,

Peter Woit (40:02.100)

they just, they don't work out the way you want

Lex Fridman (40:05.460)

and they don't actually end up carrying the power

Peter Woit (40:07.740)

or that you originally had this vision of.

Lex Fridman (40:10.220)

And yes, the book title is not even wrong.

Peter Woit (40:14.180)

Your blog, your excellent blog title is not even wrong.

Lex Fridman (40:17.780)

Okay, but there's nevertheless been a lot of excitement

Peter Woit (40:20.900)

about string theory through the decades, as you mentioned.

Lex Fridman (40:24.180)

What are the different flavors of ideas that came,

Lex Fridman (40:29.420)

like that branched out?

Lex Fridman (40:31.340)

You mentioned 10 dimensions.

Peter Woit (40:32.700)

You mentioned loops with infinite degrees of freedom.

Lex Fridman (40:36.540)

What other interesting ideas to you

Lex Fridman (40:38.780)

that kind of emerged from this world?

Lex Fridman (40:41.020)

Well, yeah, I mean, the problem

Peter Woit (40:42.020)

with talking about the whole subject

Lex Fridman (40:43.260)

and part of the reason I wrote the book

Peter Woit (40:45.740)

is that it gets very, very complicated.

Lex Fridman (40:48.740)

I mean, there's a huge amount,

Peter Woit (40:52.100)

a lot of people got very interested in this,

Lex Fridman (40:54.460)

a lot of people worked on it.

Lex Fridman (40:55.580)

And in some sense, I think what happened

Lex Fridman (40:57.900)

is exactly because the idea didn't really work

Peter Woit (41:01.340)

that this caused people to,

Lex Fridman (41:04.540)

instead of focusing on this one idea

Lex Fridman (41:06.220)

and digging in and working on that,

Lex Fridman (41:08.220)

they just kind of kept trying new things.

Lex Fridman (41:11.020)

And so people, I think, ended up wandering around

Lex Fridman (41:14.020)

in a very, very rich space of ideas

Peter Woit (41:15.860)

about mathematics and physics

Lex Fridman (41:17.660)

and discovering all sorts of really interesting things.

Peter Woit (41:19.980)

It's just the problem is there tended

Lex Fridman (41:22.020)

to be an inverse relationship

Peter Woit (41:23.380)

between how interesting and beautiful and fruitful

Lex Fridman (41:26.100)

this new idea that they were trying to pursue was

Lex Fridman (41:28.820)

and how much it looked like the real world.

Lex Fridman (41:31.820)

So there's a lot of beautiful mathematics came out of it.

Peter Woit (41:34.500)

I think one of the most spectacular

Lex Fridman (41:36.020)

is what the physicists call

Peter Woit (41:38.340)

two dimensional conformal field theory.

Lex Fridman (41:40.620)

And so these are basically quantum field theories

Lex Fridman (41:44.620)

and kind of think of it as one space

Lex Fridman (41:46.300)

and one time dimension,

Peter Woit (41:47.780)

which have just this huge amount of symmetry

Lex Fridman (41:51.220)

and a huge amount of structure,

Peter Woit (41:53.620)

which there's some totally fantastic mathematics behind it.

Lex Fridman (41:57.420)

And again, and some of that mathematics

Peter Woit (42:00.340)

is exactly also what appears in the Langlands program.

Lex Fridman (42:03.260)

So a lot of the first interaction between math and physics

Peter Woit (42:07.780)

around the Langlands program has been

Lex Fridman (42:09.140)

around these two dimensional conformal field theories.

Peter Woit (42:12.580)

Is there something you could say

Lex Fridman (42:15.220)

about what are the major problems are with string theory?

Lex Fridman (42:18.980)

So like, besides that there's no experimental validation,

Lex Fridman (42:25.820)

you've written that a big hole in string theory

Peter Woit (42:30.420)

has been its perturbative definition.

Lex Fridman (42:34.500)

Perhaps that's one, can you explain what that means?

Peter Woit (42:36.940)

Well, maybe to begin with,

Lex Fridman (42:38.140)

I think the simplest thing to say is,

Peter Woit (42:42.580)

the initial idea really was that,

Lex Fridman (42:45.220)

okay, we have this, instead of what's great

Peter Woit (42:48.380)

is we have this thing that only works,

Lex Fridman (42:50.740)

it's very structured and has to work in a certain way

Peter Woit (42:54.180)

for it to make sense.

Lex Fridman (42:55.540)

But then you ended up in 10 space time dimensions.

Lex Fridman (43:01.700)

And so to get back to physics,

Lex Fridman (43:03.620)

you had to get rid of five of the dimensions,

Peter Woit (43:05.380)

six of the dimensions.

Lex Fridman (43:06.860)

And the bottom line I would say in some sense is very simple

Peter Woit (43:09.620)

that what people just discovered is just,

Lex Fridman (43:12.780)

there's kind of no particularly nice way of doing this,

Peter Woit (43:15.660)

there's an infinite number of ways of doing it

Lex Fridman (43:17.460)

and you can get whatever you want

Peter Woit (43:18.740)

depending on how you do it.

Lex Fridman (43:20.140)

So you end up the whole program of starting at 10 dimensions

Lex Fridman (43:24.020)

and getting to four just kind of collapses

Lex Fridman (43:26.780)

out of a lack of any way to kind of get to where you want

Peter Woit (43:29.740)

because you can get anything.

Lex Fridman (43:31.540)

The hope around that problem has always been

Peter Woit (43:34.380)

that the standard formulation that we have of string theory,

Lex Fridman (43:38.940)

which is, you can go by the name perturbative,

Lex Fridman (43:42.540)

but it's kind of, there's a standard way we know

Lex Fridman (43:46.300)

of given a classical theory of constructing a quantum theory

Lex Fridman (43:50.700)

and working with it, which is the so called

Lex Fridman (43:56.100)

perturbation theory that we know how to do.

Lex Fridman (43:59.260)

And that by itself just doesn't give you any hint

Lex Fridman (44:04.460)

as to what to do about the six dimensions.

Lex Fridman (44:06.660)

So actual perturbed string theory by itself

Lex Fridman (44:09.180)

really only works in 10 dimensions.

Lex Fridman (44:11.340)

So you have to start making some kinds of assumptions

Lex Fridman (44:14.380)

about how I'm gonna go beyond this formulation

Peter Woit (44:19.380)

that we really understand of string theory

Lex Fridman (44:21.700)

and get rid of these six dimensions.

Lex Fridman (44:24.060)

So kind of the simplest one was the Klabiau postulate,

Lex Fridman (44:29.380)

but when that didn't really work out,

Peter Woit (44:31.820)

people have tried more and more different things.

Lex Fridman (44:33.940)

And the hope has always been that the solution,

Peter Woit (44:38.500)

this problem would be that you would find a deeper

Lex Fridman (44:41.540)

and better understanding of what string theory is

Peter Woit (44:44.220)

that would actually go beyond this perturbative expansion

Lex Fridman (44:47.860)

and which would generalize this.

Lex Fridman (44:51.820)

And that once you had that, it would solve this problem of,

Lex Fridman (44:57.220)

it would pick out what to do with the six dimensions.

Lex Fridman (44:59.580)

How difficult is this problem?

Lex Fridman (45:01.140)

So if I could restate the problem,

Peter Woit (45:05.100)

it seems like there's a very consistent physical world

Lex Fridman (45:09.860)

operating in four dimensions.

Lex Fridman (45:13.340)

And how do you map a consistent physical world

Lex Fridman (45:16.700)

in 10 dimensions to a consistent physical world

Lex Fridman (45:19.260)

in four dimensions?

Lex Fridman (45:21.180)

And how difficult is this problem?

Lex Fridman (45:23.100)

Is that something you can even answer?

Lex Fridman (45:27.720)

Just in terms of physics intuition,

Peter Woit (45:30.340)

in terms of mathematics,

Lex Fridman (45:32.280)

mapping from 10 dimensions to four dimensions.

Peter Woit (45:35.060)

Well, basically, I mean, you have to get rid

Lex Fridman (45:36.580)

of the six of the dimensions.

Lex Fridman (45:38.140)

So there's kind of two ways of doing it.

Lex Fridman (45:41.620)

One is what we called compactification.

Peter Woit (45:44.020)

You say that there really are 10 dimensions,

Lex Fridman (45:46.860)

but for whatever reason,

Peter Woit (45:48.220)

six of them are so, so small, we can't see them.

Lex Fridman (45:51.860)

So you basically start out with 10 dimensions

Lex Fridman (45:54.660)

and what we call, make six of them not go out to infinity,

Lex Fridman (45:58.980)

but just kind of a finite extent

Lex Fridman (46:00.780)

and then make that size go down so small, it's unobservable.

Lex Fridman (46:05.460)

But that's like, that's a math trick.

Lex Fridman (46:08.300)

So can you also help me build an intuition

Lex Fridman (46:11.420)

about how rich and interesting the world

Lex Fridman (46:15.580)

in those six dimensions is?

Lex Fridman (46:17.900)

So compactification seems to imply...

Peter Woit (46:21.020)

Well, it's not very interesting.

Lex Fridman (46:22.660)

Well, no, but the problem is that what you learn

Peter Woit (46:24.700)

if you start doing mathematics

Lex Fridman (46:26.780)

and looking at geometry and topology

Lex Fridman (46:28.900)

and more and more dimensions is that,

Lex Fridman (46:31.600)

I mean, asking the question like,

Lex Fridman (46:34.180)

what are all possible six dimensional spaces?

Lex Fridman (46:36.540)

It's just, it's kind of an unnatural question.

Peter Woit (46:38.580)

It's just, I mean,

Lex Fridman (46:39.620)

it's even kind of technically undecidable in some way.

Peter Woit (46:42.020)

There are too many things you can do with all these,

Lex Fridman (46:46.180)

if you start trying to make,

Peter Woit (46:47.500)

if you start trying to make one dimensional spaces,

Lex Fridman (46:49.540)

it's like, well, you got a line, you can make a circle,

Peter Woit (46:52.140)

you can make graphs, you can kind of see what you can do.

Lex Fridman (46:55.180)

But as you go to higher and higher dimensions,

Peter Woit (46:58.260)

there are just so many ways you can put things together

Lex Fridman (47:02.140)

of and get something of that dimensionality.

Lex Fridman (47:05.460)

And so unless you have some very, very strong principle,

Lex Fridman (47:09.820)

we're just gonna pick out some very specific ones

Peter Woit (47:12.920)

of these six dimensional spaces.

Lex Fridman (47:15.400)

And there are just too many of them

Lex Fridman (47:17.340)

and you can get anything you want.

Lex Fridman (47:19.500)

So if you have 10 dimensions,

Peter Woit (47:22.540)

the kind of things that happen,

Lex Fridman (47:24.460)

say that's actually the way,

Peter Woit (47:26.700)

that's actually the fabric of our reality is 10 dimensions.

Lex Fridman (47:29.740)

There's a limited set of behaviors of objects.

Peter Woit (47:33.100)

I don't know even know what the right terminology

Lex Fridman (47:35.180)

to use that can occur within those dimensions,

Peter Woit (47:39.380)

like in reality.

Lex Fridman (47:41.500)

And so like what I'm getting at is like,

Lex Fridman (47:44.540)

is there some consistent constraints?

Lex Fridman (47:47.280)

So if you have some constraints that map to reality,

Peter Woit (47:51.080)

then you can start saying like,

Lex Fridman (47:53.460)

dimension number seven is kind of boring.

Peter Woit (47:56.260)

All the excitement happens in the spatial dimensions,

Lex Fridman (47:58.900)

one, two, three.

Lex Fridman (48:00.380)

And time is also kind of boring.

Lex Fridman (48:02.740)

And like some are more exciting than others,

Peter Woit (48:05.380)

or we can use our metric of beauty.

Lex Fridman (48:08.100)

Some dimensions are more beautiful than others.

Peter Woit (48:10.260)

Once you have an actual understanding

Lex Fridman (48:12.260)

of what actually happens in those dimensions

Peter Woit (48:15.280)

in our physical world,

Lex Fridman (48:16.500)

as opposed to sort of all the possible things

Peter Woit (48:18.620)

that could happen.

Lex Fridman (48:19.600)

In some sense, I mean,

Peter Woit (48:20.660)

just the basic fact is you need to get rid of them.

Lex Fridman (48:22.240)

We don't see them.

Lex Fridman (48:23.080)

So you need to somehow explain them.

Lex Fridman (48:25.580)

The main thing you're trying to do

Peter Woit (48:26.580)

is to explain why we're not seeing them.

Lex Fridman (48:28.820)

And so you have to come up with some theory

Peter Woit (48:32.540)

of these extra dimensions and how they're gonna behave.

Lex Fridman (48:35.420)

And string theory gives you some ideas

Peter Woit (48:38.180)

about how to do that.

Lex Fridman (48:39.020)

But the bottom line is where you're trying to go

Peter Woit (48:43.580)

with this whole theory you're creating

Lex Fridman (48:45.660)

is to just make all of its effects essentially unobservable.

Lex Fridman (48:49.540)

So it's not a really,

Lex Fridman (48:54.780)

it's an inherently kind of dubious and worrisome thing

Peter Woit (48:57.300)

that you're trying to do there.

Lex Fridman (48:58.300)

Why are you just adding in all this stuff

Lex Fridman (49:00.600)

and then trying to explain why we don't see it?

Lex Fridman (49:02.220)

Exactly.

Peter Woit (49:03.060)

This may be a dumb question,

Lex Fridman (49:04.260)

but is this an obvious thing to state

Peter Woit (49:07.780)

that those six dimensions are unobservable

Lex Fridman (49:11.580)

or anything beyond four dimensions is unobservable?

Peter Woit (49:16.180)

Or do you leave a little door open

Lex Fridman (49:19.540)

to saying the current tools of physics,

Lex Fridman (49:23.180)

and obviously our brains aren't unable to observe them,

Lex Fridman (49:26.980)

but we may need to come up with methodologies

Peter Woit (49:29.940)

for observing them.

Lex Fridman (49:30.780)

So as opposed to collapsing your mathematical theory

Peter Woit (49:33.140)

into four dimensions,

Lex Fridman (49:35.020)

leaving the door open a little bit too,

Peter Woit (49:37.140)

maybe we need to come up with tools

Lex Fridman (49:38.760)

that actually allow us to directly measure those dimensions.

Peter Woit (49:42.700)

Yes, I mean, you can certainly ask,

Lex Fridman (49:45.260)

assume that we've got model,

Peter Woit (49:49.200)

look at models with more dimensions and ask,

Lex Fridman (49:51.340)

what would the observable effects, how would we know this?

Lex Fridman (49:54.180)

And you go out and do experiments.

Lex Fridman (49:55.500)

So for instance, you have a,

Peter Woit (49:58.780)

like gravitationally you have an inverse square law of forces.

Lex Fridman (50:02.660)

If you had more dimensions,

Peter Woit (50:04.100)

that inverse square law would change to something else.

Lex Fridman (50:06.620)

So you can go and start measuring the inverse square law

Lex Fridman (50:09.540)

and say, okay, inverse square law is working,

Lex Fridman (50:12.060)

but maybe if I get,

Lex Fridman (50:14.660)

and it turns out to be actually kind of very, very hard

Lex Fridman (50:16.540)

to measure gravitational effects

Lex Fridman (50:18.140)

and even kind of somewhat macroscopic distances

Lex Fridman (50:21.940)

because they're so small.

Lex Fridman (50:23.300)

So you can start looking at the inverse square law

Lex Fridman (50:26.220)

and say, start trying to measure it

Peter Woit (50:28.020)

at shorter and shorter distances

Lex Fridman (50:29.380)

and see if there were extra dimensions

Peter Woit (50:33.180)

at those distance scales,

Lex Fridman (50:34.440)

you would start to see the inverse square law fail.

Lex Fridman (50:36.780)

And so people look for that and again, you don't see it,

Lex Fridman (50:40.520)

but you can, I mean, there's all sorts of experiments

Peter Woit (50:43.220)

of this kind you can imagine which test

Lex Fridman (50:46.580)

for effects of extra dimensions

Peter Woit (50:48.420)

at different distance scales, but none of them,

Lex Fridman (50:53.860)

I mean, they all just don't work.

Peter Woit (50:55.940)

Nothing yet.

Lex Fridman (50:58.220)

Nothing yet, but you could say, ah, but it's just much,

Peter Woit (51:01.860)

much smaller, you can say that.

Lex Fridman (51:05.180)

Which by the way makes LIGO

Lex Fridman (51:06.900)

and the detection of gravitational waves

Lex Fridman (51:09.980)

quite an incredible project.

Peter Woit (51:13.300)

Ed Witten is often brought up

Lex Fridman (51:15.680)

as one of the most brilliant mathematicians

Lex Fridman (51:17.420)

and physicists ever.

Lex Fridman (51:21.060)

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

Peter Woit (51:24.460)

Well, I think he's a truly remarkable figure.

Lex Fridman (51:26.820)

I've had the pleasure of meeting him first

Peter Woit (51:30.140)

when he was a postdoc.

Lex Fridman (51:31.100)

And I mean, he's just completely amazing

Peter Woit (51:36.060)

mathematician and physicist.

Lex Fridman (51:38.020)

And he's quite a bit smarter

Peter Woit (51:41.460)

than just about any of the rest of us

Lex Fridman (51:43.380)

and also more hardworking.

Peter Woit (51:44.580)

It's a kind of frightening combination

Lex Fridman (51:46.780)

to see how much he's been able to do.

Lex Fridman (51:50.540)

But I would actually argue that his greatest work,

Lex Fridman (51:53.540)

the things that he's done that have been of

Peter Woit (51:55.820)

just this mind blowing significance of giving us,

Lex Fridman (51:58.660)

I mean, he's completely revolutionized

Peter Woit (52:00.100)

some areas of mathematics.

Lex Fridman (52:02.180)

He's totally revolutionized the way we understand

Peter Woit (52:04.220)

the relations between mathematics and physics.

Lex Fridman (52:07.160)

And most of those, his greatest work

Peter Woit (52:10.660)

is stuff that has little or nothing

Lex Fridman (52:13.700)

to do with string theory.

Peter Woit (52:15.140)

I mean, for instance, so he was actually one of Fields.

Lex Fridman (52:19.180)

The very strange thing about him in some sense

Peter Woit (52:20.920)

is that he doesn't have a Nobel Prize.

Lex Fridman (52:23.660)

So there's a very large number of people

Peter Woit (52:25.940)

who are nowhere near as smart as he is

Lex Fridman (52:28.300)

and don't work anywhere near as hard

Peter Woit (52:30.140)

who have Nobel Prizes.

Lex Fridman (52:31.740)

I think he just had the misfortune

Peter Woit (52:33.180)

of coming into the field at a time

Lex Fridman (52:35.820)

when things had gotten much, much, much tougher

Lex Fridman (52:37.740)

and nobody really had, no matter how smart you were,

Lex Fridman (52:41.380)

it was very hard to come up with a new idea

Peter Woit (52:44.020)

that was gonna work physically and get you a Nobel Prize.

Lex Fridman (52:47.740)

But he got a Fields Medal for a certain work he did

Peter Woit (52:52.980)

in mathematics, and that's just completely unheard of.

Lex Fridman (52:56.540)

For mathematicians to give a Fields Medal

Peter Woit (52:58.380)

to someone outside their field in physics

Lex Fridman (53:00.860)

is really, you wouldn't have, before he came around,

Peter Woit (53:05.620)

I don't think anybody would have thought

Lex Fridman (53:06.680)

that was even conceivable.

Lex Fridman (53:08.040)

So you're saying he came into the field

Lex Fridman (53:11.020)

of theoretical physics at a time when,

Lex Fridman (53:13.700)

and still to today, is you can't get a Nobel Prize

Lex Fridman (53:18.240)

for purely theoretical work.

Peter Woit (53:20.200)

The specific problem of trying to do better

Lex Fridman (53:22.320)

than the standard, the standard model

Peter Woit (53:23.880)

is just this insanely successful thing,

Lex Fridman (53:26.680)

and it kind of came together in 1973, pretty much.

Lex Fridman (53:30.600)

And all of the people who kind of were involved

Lex Fridman (53:34.320)

in that coming together, many of them ended up

Peter Woit (53:37.200)

with Nobel Prizes for that.

Lex Fridman (53:38.600)

But if you look post 1973, pretty much,

Peter Woit (53:43.720)

it's a little bit more, there's some edge cases,

Lex Fridman (53:47.160)

if you like, but if you look post 1973

Peter Woit (53:50.200)

at what people have done to try to do better

Lex Fridman (53:53.240)

than the standard model and to get a better idea,

Peter Woit (53:56.160)

it really hasn't, it's been too hard a problem.

Lex Fridman (53:58.440)

It hasn't worked.

Peter Woit (53:59.280)

The theory's too good.

Lex Fridman (54:00.100)

And so it's not that other people went out there

Lex Fridman (54:03.320)

and did it, and not him, and that they got Nobel Prizes

Lex Fridman (54:07.340)

for doing it, it's just that no one really,

Peter Woit (54:08.960)

the kind of thing he's been trying to do

Lex Fridman (54:10.480)

with string theory is not, no one has been able to do

Peter Woit (54:13.360)

since 1973.

Lex Fridman (54:15.540)

Is there something you can say about the standard model,

Lex Fridman (54:17.380)

so the four laws of physics that seems to work very well,

Lex Fridman (54:20.720)

and yet people are striving to do more?

Lex Fridman (54:24.980)

Talking about unification, so on, why?

Lex Fridman (54:27.580)

What's wrong, what's broken about the standard model?

Lex Fridman (54:30.900)

Why does it need to be improved?

Lex Fridman (54:33.080)

I mean, the thing that's gets most attention

Peter Woit (54:34.880)

is gravity, that we have trouble.

Lex Fridman (54:39.160)

So you want to, in some sense, integrate what we know

Peter Woit (54:44.120)

about the gravitational force with it

Lex Fridman (54:46.320)

and have a unified quantum field theory

Peter Woit (54:48.640)

that has gravitational interactions also.

Lex Fridman (54:50.340)

So that's the big problem everybody talks about.

Peter Woit (54:53.640)

I mean, but it's also true that if you look

Lex Fridman (54:55.940)

at the standard model, it has these very, very deep,

Peter Woit (54:58.380)

beautiful ideas, but there's certain aspects of it

Lex Fridman (55:01.600)

that are very, let's just say that they're not beautiful.

Peter Woit (55:08.240)

They're not, you have to, to make the thing work,

Lex Fridman (55:11.440)

you have to throw in lots and lots of extra parameters

Peter Woit (55:14.240)

at various points, and a lot of this has to do

Lex Fridman (55:17.480)

with the so called Higgs mechanism and the Higgs field,

Peter Woit (55:21.960)

that if you look at the theory, it's everything is,

Lex Fridman (55:25.960)

if you forget about the Higgs field and what it needs to do,

Peter Woit (55:28.940)

the rest of the theory is very, very constrained

Lex Fridman (55:33.520)

and has very, very few free parameters,

Peter Woit (55:35.320)

really a very small number.

Lex Fridman (55:36.400)

There's very small number of parameters

Lex Fridman (55:38.060)

and a few integers which tell you what the theory is.

Lex Fridman (55:40.900)

To make this work as a theory of the real world,

Peter Woit (55:42.960)

you need a Higgs field and you need to,

Lex Fridman (55:45.480)

it needs to do something.

Lex Fridman (55:48.080)

And once you introduce that Higgs field,

Lex Fridman (55:50.840)

all sorts of parameters make an appearance.

Lex Fridman (55:54.440)

So now we've got 20 or 30 or whatever parameters

Lex Fridman (55:58.760)

that are gonna tell you what all the masses of things are

Lex Fridman (56:00.880)

and what's gonna happen.

Lex Fridman (56:02.160)

So you've gone from a very tightly constrained thing

Peter Woit (56:05.500)

with a couple of parameters to this thing,

Lex Fridman (56:09.000)

which the minute you put it in,

Peter Woit (56:11.120)

you had to add all this extra,

Lex Fridman (56:13.200)

all these extra parameters to make things work.

Lex Fridman (56:15.320)

And so that, it may be one argument as well,

Lex Fridman (56:19.120)

that's just the way the world is,

Lex Fridman (56:20.480)

and the fact that you don't find that aesthetically pleasing

Lex Fridman (56:24.160)

is just your problem, or maybe we live in a multiverse

Lex Fridman (56:27.320)

and those numbers are just different in every universe.

Lex Fridman (56:30.080)

But another reasonable conjecture is just that,

Peter Woit (56:33.620)

well, this is just telling us that there's something

Lex Fridman (56:36.020)

we don't understand about what's going on in a deeper way,

Peter Woit (56:40.200)

which would explain those numbers.

Lex Fridman (56:41.680)

And there's some kind of deeper idea

Peter Woit (56:44.240)

about where the Higgs field comes from and what's going on,

Lex Fridman (56:47.240)

which we haven't figured out yet.

Lex Fridman (56:49.040)

And that's what we should look for.

Lex Fridman (56:52.820)

But to stick on string theory a little bit longer,

Peter Woit (56:55.960)

could you play devil's advocate

Lex Fridman (56:58.580)

and try to argue for string theory,

Lex Fridman (57:01.880)

why it is something that deserved the effort that it got,

Lex Fridman (57:07.000)

and still, like if you think of it as a flame,

Lex Fridman (57:10.400)

still should be a little flame that keeps burning?

Lex Fridman (57:14.160)

Well, I think the, I mean, the most positive argument

Peter Woit (57:17.600)

for it is all sorts of new ideas about mathematics

Lex Fridman (57:22.120)

and about parts of physics really emerge from it.

Peter Woit (57:24.800)

That was very a fruitful source of ideas.

Lex Fridman (57:28.420)

And I think this is actually one argument you'll definitely,

Peter Woit (57:30.720)

which I kind of agree with,

Lex Fridman (57:31.600)

I'll hear from Whitten and from other string theorists,

Peter Woit (57:34.280)

say that this is just such a fruitful and inspiring idea

Lex Fridman (57:38.960)

and it's led to so many other different things

Peter Woit (57:41.320)

coming out of it that there must be something

Lex Fridman (57:43.680)

right about this.

Lex Fridman (57:45.160)

And that's, okay, anyway, I think that's probably

Lex Fridman (57:48.880)

the strongest thing that they've got.

Lex Fridman (57:52.760)

But you don't think there's aspects to it

Lex Fridman (57:55.800)

that could be neighboring to a theory

Peter Woit (58:00.440)

that does unify everything, to a theory of everything.

Lex Fridman (58:03.160)

Like it could, it may not be exactly,

Peter Woit (58:08.080)

exactly the theory, but sticking on it longer

Lex Fridman (58:11.240)

might get us closer to the theory of everything.

Peter Woit (58:14.360)

Well, the problem with it now really

Lex Fridman (58:15.400)

is that you really don't know what it is now.

Peter Woit (58:17.280)

You've never, nobody has ever kind of come up

Lex Fridman (58:19.880)

with this nonperturbative theory.

Lex Fridman (58:23.360)

So it's become more and more frustrating

Lex Fridman (58:27.400)

and an odd activity to try to argue with a string theorist

Peter Woit (58:30.320)

about string theory because it's become

Lex Fridman (58:34.080)

less and less well defined what it is.

Lex Fridman (58:37.200)

And it's become actually more and more kind of a,

Lex Fridman (58:40.080)

whether you have this weird phenomenon

Peter Woit (58:42.280)

of people calling themselves string theorists

Lex Fridman (58:44.780)

when they've never actually worked on any theory

Peter Woit (58:47.480)

where there are any strings anywhere.

Lex Fridman (58:49.520)

So what has actually happened kind of sociologically

Peter Woit (58:52.560)

is that you started out with this

Lex Fridman (58:54.760)

fairly well defined proposal.

Lex Fridman (58:56.480)

And then I would argue because that didn't work,

Lex Fridman (58:59.120)

people branched out in all sorts of directions

Peter Woit (59:01.720)

doing all sorts of things.

Lex Fridman (59:02.800)

It became farther and farther removed from that.

Lex Fridman (59:05.520)

And for sociological reasons,

Lex Fridman (59:07.880)

the ones who kind of started out or now

Peter Woit (59:12.400)

or were trained by the people who worked on that

Lex Fridman (59:15.360)

have now become this string theorists.

Peter Woit (59:18.880)

And, but it's becoming almost more

Lex Fridman (59:23.640)

kind of a tribal denominator than a,

Peter Woit (59:26.640)

I think so it's very hard to know

Lex Fridman (59:28.120)

what you're arguing about

Peter Woit (59:29.040)

when you're arguing about string theory these days.

Lex Fridman (59:30.680)

Well, to push back on that a little bit,

Lex Fridman (59:32.120)

I mean, string theory is just a term, right?

Lex Fridman (59:34.560)

It doesn't, like you could,

Peter Woit (59:37.040)

like this is the way language evolves

Lex Fridman (59:39.780)

is it could start to represent something

Peter Woit (59:41.360)

more than just the theory that involves strings.

Lex Fridman (59:43.440)

It could represent the effort to unify the laws of physics.

Lex Fridman (59:49.160)

Right?

Lex Fridman (59:50.000)

At high dimensions with these super tiny objects, right?

Peter Woit (59:54.680)

Or something like that.

Lex Fridman (59:56.120)

I mean, we can sort of put string theory aside.

Lex Fridman (59:59.320)

So for example, neural networks