Peter Woit: Theories of Everything & Why String Theory is Not Even Wrong #246

Transcript

00:00:00 The following is a conversation with Peter White,

00:00:02 a theoretical physicist at Columbia,

00:00:04 outspoken critic of string theory,

00:00:06 and the author of the popular physics and mathematics blog

00:00:10 called Not Even Wrong.

00:00:13 This is the Lex Friedman podcast.

00:00:15 To support it, please check out our sponsors

00:00:17 in the description.

00:00:18 And now, here’s my conversation with Peter White.

00:00:23 You’re both a physicist and a mathematician.

00:00:27 So let me ask, what is the difference

00:00:29 between physics and mathematics?

00:00:31 Well, there’s kind of a conventional understanding

00:00:33 of the subject that they’re two quite different things.

00:00:37 So that mathematics is about making rigorous statements

00:00:41 about these abstract things,

00:00:45 things of mathematics, and proving them rigorously.

00:00:48 And physics is about doing experiments

00:00:51 and testing various models and that.

00:00:53 But I think the more interesting thing

00:00:55 is that there’s a wide variety of what people do

00:01:00 as mathematics, what they do as physics,

00:01:02 and there’s a significant overlap.

00:01:04 And that, I think, is actually a very interesting area.

00:01:09 And if you go back kind of far enough in history

00:01:12 and look at figures like Newton or something,

00:01:15 at that point, you can’t really tell,

00:01:17 was Newton a physicist or a mathematician?

00:01:19 Mathematicians will tell you he was a mathematician.

00:01:21 The physicists will tell you he was a physicist.

00:01:23 But he would say he’s a philosopher.

00:01:26 Yeah, that’s interesting.

00:01:28 But yeah, anyway, there was kind of no such distinction

00:01:32 then that’s more of a modern thing.

00:01:35 But anyway, I think these days,

00:01:36 there’s a very interesting space in between the two.

00:01:38 So in the story of the 20th century

00:01:40 and the early 21st century,

00:01:42 what is the overlap between mathematics and physics,

00:01:44 would you say?

00:01:45 Well, I think it’s actually become very, very complicated.

00:01:49 I think it’s really interesting to see

00:01:51 a lot of what my colleagues in the math department

00:01:54 are doing, most of what they’re doing,

00:01:56 they’re doing all sorts of different things,

00:01:58 but most of them have some kind of overlap

00:02:00 with physics or other.

00:02:02 So, I mean, I’m personally interested

00:02:03 in one particular aspect of this overlap,

00:02:06 which I think has a lot to do with the most fundamental ideas

00:02:09 about physics and about mathematics.

00:02:12 But you kind of see this really everywhere at this point.

00:02:17 Which particular overlap are you looking at, group theory?

00:02:20 Yeah, so at least the way it seems to me

00:02:24 that if you look at physics

00:02:25 and look at our most successful laws of fundamental physics,

00:02:29 they have a certain kind of mathematical structure,

00:02:33 it’s based upon certain kind of mathematical objects

00:02:36 and geometry, connections and curvature,

00:02:38 the spinners, the Dirac equation.

00:02:41 And this very deep mathematics provides kind of a unifying

00:02:47 set of ways of thinking that allow you

00:02:50 to make a unified theory of physics.

00:02:52 But the interesting thing is that if you go to mathematics

00:02:55 and look at what’s been going on in mathematics

00:02:58 the last 50, 100 years, and even especially recently,

00:03:02 there’s a similarly some kind of unifying ideas

00:03:06 which bring together different areas of mathematics

00:03:08 and which have been established in the last 50, 100 years.

00:03:11 Especially powerful in number theory recently.

00:03:13 And there’s a book, for instance, by Edward Frankel

00:03:17 about love and math.

00:03:19 Yeah, that book’s great, I recommend it highly.

00:03:21 It’s partially accessible.

00:03:24 But there’s a nice audio book that I listened to

00:03:27 while running an exceptionally long distance,

00:03:31 like across the San Francisco bridge.

00:03:35 And there’s something magic about the way he writes about it.

00:03:38 But some of the group theory in there

00:03:40 is a little bit difficult.

00:03:42 Yeah, that’s the problem with any of these things,

00:03:44 to kind of really say what’s going on

00:03:45 and make it accessible is very hard.

00:03:48 He, in this book and elsewhere, I think takes the attitude

00:03:52 that kinds of mathematics he’s interested in

00:03:54 and that he’s talking about provide

00:03:57 kind of a grand unified theory of mathematics.

00:03:59 They bring together geometry and number theory

00:04:03 and representation theory, a lot of different ideas

00:04:06 in a really unexpected way.

00:04:09 But I think, to me, the most fascinating thing

00:04:11 is if you look at the kind of grand unified theory

00:04:13 of mathematics he’s talking about

00:04:15 and you look at the physicist kind of ideas

00:04:17 about unification, it’s more or less

00:04:19 the same mathematical objects are appearing in both.

00:04:22 So it’s this, I think there’s a really,

00:04:24 we’re seeing a really strong indication

00:04:26 that the deepest ideas that we’re discovering about physics

00:04:30 and some of the deepest ideas that mathematicians

00:04:32 are learning about are really, are intimately connected.

00:04:36 Is there something, like if I was five years old

00:04:38 and you were trying to explain this to me,

00:04:40 is there ways to try to sneak up

00:04:43 to what this unified world of mathematics looks like?

00:04:47 You said number theory, you said geometry,

00:04:50 words like topology.

00:04:52 What does this universe begin to look like?

00:04:54 Are these, what should we imagine in our mind?

00:04:57 Is it a three dimensional surface?

00:05:00 And we’re trying to say something about it.

00:05:03 Is it triangles and squares and cubes?

00:05:07 Like what are we supposed to imagine in our minds?

00:05:09 Is this natural number?

00:05:10 What’s a good thing to try to,

00:05:13 for people that don’t know any of these tools

00:05:16 except maybe some basic calculus and geometry

00:05:19 from high school that they should keep in their minds

00:05:22 as to the unified world of mathematics

00:05:24 that also allows us to explore the unified world of physics.

00:05:30 I mean, what I find kind of remarkable about this

00:05:33 is the way in which these, we’ve discovered these ideas,

00:05:38 but they’re actually quite alien

00:05:40 to our everyday understanding.

00:05:42 We grow up in this three spatial dimensional world

00:05:45 and we have intimate understanding

00:05:47 of certain kinds of geometry and certain kinds of things.

00:05:50 But these things that we’ve discovered

00:05:53 in both math and physics are,

00:05:56 that they’re not at all close,

00:05:58 have any obvious connection

00:05:59 to kind of human everyday experience.

00:06:02 They’re really quite different.

00:06:03 And I can say some of my initial fascination with this

00:06:06 when I was young and starting to learn about it

00:06:08 was actually exactly this kind of arcane nature

00:06:14 of these things.

00:06:15 It was a little bit like being told,

00:06:17 well, there are these kind of semi mystical experience

00:06:21 that you can acquire by a long study and whatever,

00:06:24 except that it was actually true.

00:06:27 There’s actually evidence that this actually works.

00:06:29 So I’m a little bit wary of trying to give people

00:06:33 that kind of thing,

00:06:33 because I think it’s mostly misleading.

00:06:35 But one thing to say is that geometry is a large part of it.

00:06:39 And maybe one interesting thing to say very,

00:06:43 that’s about more recent, some of the most recent ideas

00:06:45 is that when we think about the geometry

00:06:48 of our space and time,

00:06:50 it’s kind of three spatial and one time dimension.

00:06:53 It’s a physics is in some sense

00:06:56 about something that’s kind of four dimensional in a way.

00:07:00 And a really interesting thing about

00:07:03 some of the recent developments and number theory

00:07:06 have been to realize that these ideas

00:07:09 that we were looking at naturally fit into a context

00:07:12 where your theory is kind of four dimensional.

00:07:15 So, geometry is a big part of this

00:07:19 and we know a lot and feel a lot about

00:07:22 two, one, two, three dimensional geometry.

00:07:24 So wait a minute, so we can at least rely

00:07:28 on the four dimensions of space and time

00:07:31 and say that we can get pretty far

00:07:32 by working in those four dimensions.

00:07:35 I thought you were gonna scare me

00:07:36 that we’re gonna have to go to many, many, many,

00:07:39 many more dimensions than that.

00:07:40 My point of view, which goes against

00:07:43 a lot of these ideas about unification

00:07:44 is that no, this is really,

00:07:47 everything we know about really is about four dimensions

00:07:50 and that you can actually understand a lot of these

00:07:54 structures that we’ve been seeing in fundamental physics

00:07:56 and in number theory, just in terms of four dimensions,

00:08:01 that it’s kind of, it’s in some sense I would claim

00:08:05 has been a really, has been kind of a mistake

00:08:09 that physicists have made for decades and decades

00:08:12 to try to go to higher dimensions,

00:08:16 to try to formulate a theory in higher dimensions

00:08:19 and then you’re stuck with the problem

00:08:21 of how do you get rid of all these extra dimensions

00:08:23 that you’ve created

00:08:25 because we only ever see anything in four dimensions.

00:08:27 That kind of thing leaves us astray, you think?

00:08:29 So creating all these extra dimensions

00:08:31 just to give yourself extra degrees of freedom.

00:08:35 Isn’t that the process of mathematics

00:08:38 is to create all of these trajectories for yourself

00:08:41 but eventually you have to end up at the final place

00:08:45 but it’s okay to sort of create abstract objects

00:08:52 on your path to proving something.

00:08:55 Yeah, certainly and from a mathematician’s point of view,

00:08:59 I mean, the kinds of,

00:09:01 mathematicians also are very different than physicists

00:09:03 in that we like to develop very general theories.

00:09:06 We like to, if we have an idea,

00:09:07 we want to see what’s the greatest generality

00:09:09 in which you can talk about it.

00:09:11 So from the point of view of most of the ways geometry

00:09:14 is formulated by mathematicians,

00:09:17 it really doesn’t matter, it works in any dimension.

00:09:19 We can do one, two, three, four, any number.

00:09:22 There’s no particular, for most of geometry,

00:09:24 there’s no particular special thing about four.

00:09:28 But anyway, but what physicists have been trying to do

00:09:33 over the years is try to understand

00:09:35 these fundamental theories in a geometrical way

00:09:38 and it’s very tempting to kind of just start bringing in

00:09:41 extra dimensions and using them to explain the structure.

00:09:46 But typically this attempt kind of founders

00:09:51 because you just don’t know,

00:09:53 you end up not being able to explain why we only see four.

00:09:59 It is nice in the space of physics

00:10:01 that like if you look at Fermat’s last theorem,

00:10:04 it’s much easier to prove that there’s no solution

00:10:06 for n equals three than it is for the general case.

00:10:12 And so I guess that’s the nice benefit of being a physicist

00:10:16 is you don’t have to worry about the general case

00:10:18 because we live in a universe with n equals four

00:10:22 in this case.

00:10:23 Yeah, physicists are very interested in saying something

00:10:27 about specific examples and I find that interesting

00:10:31 when I’m trying to do things in mathematics

00:10:33 and I’m even teaching courses into mathematics students,

00:10:36 I find that I’m teaching them in a different way

00:10:40 than most mathematicians because I’m very often

00:10:43 very focused on examples on what’s kind of the crucial

00:10:47 example that shows how this powerful new mathematical

00:10:52 technique, how it works and why you would want to do it.

00:10:55 And I’m less interested in kind of proving a precise theorem

00:11:00 about exactly when it’s gonna work

00:11:01 and when it’s not gonna work.

00:11:02 Do you usually think about really simple examples,

00:11:05 like both for teaching and when you try to solve

00:11:09 a difficult problem, do you construct the simplest

00:11:12 possible examples that captures the fundamentals

00:11:14 of the problem and try to solve it?

00:11:15 Yeah, exactly, that’s often a really fruitful way

00:11:19 to if you’ve got some idea to just kind of try

00:11:22 to boil it down to what’s the simplest situation

00:11:27 in which this kind of thing is gonna happen

00:11:28 and then try to really understand that and understand that

00:11:31 and that is almost always a really good way

00:11:33 to get insight into it.

00:11:34 Do you work with paper and pen or like, for example,

00:11:37 for me coming from the programming side,

00:11:41 if I look at a model, if I look at some kind

00:11:43 of mathematical object, I like to mess around

00:11:47 with it sort of numerically.

00:11:49 I just visualize different parts of it,

00:11:51 visualize however I can so most of the work

00:11:54 is like when you’re on networks, for example,

00:11:56 is you try to play with the simplest possible example

00:11:59 and just to build up intuition by any kind of object

00:12:04 has a bunch of variables in it and you start

00:12:07 to mess around with them in different ways

00:12:09 and visualize in different ways to start

00:12:10 to build intuition or do you go the Einstein route

00:12:14 and just imagine everything inside your mind

00:12:19 and sort of build thought experiments

00:12:21 and then work purely on paper and pen?

00:12:24 Well, the problem with this kind of stuff

00:12:28 I’m interested in is you rarely can kind of,

00:12:31 it’s rarely something that is really kind of,

00:12:34 or even the simplest example, you can kind of see

00:12:38 what’s going on by looking at something happening

00:12:40 in three dimensions.

00:12:42 There’s generally the structures involved

00:12:44 are either they’re more abstract

00:12:47 or if you try to kind of embed them in some kind of space

00:12:50 and where you could manipulate them

00:12:53 in some kind of geometrical way,

00:12:55 it’s gonna be a much higher dimensional space.

00:12:57 So even simple examples,

00:13:00 the embedding them into three dimensional space,

00:13:02 you’re losing a lot.

00:13:03 Yeah, but to capture what you’re trying to understand

00:13:06 about them, you have to go to four or more dimensions.

00:13:09 So it starts to get to be hard to,

00:13:12 I mean, you can train yourself to try it as much

00:13:14 as to kind of think about things in your mind

00:13:18 and I often use pad and paper

00:13:21 and often if I’m in my office, I have to use the blackboard

00:13:25 and you are kind of drawing things

00:13:26 but they’re really kind of more abstract representations

00:13:29 of how things are supposed to fit together

00:13:32 and they’re not really, unfortunately,

00:13:35 not just kind of really living in three dimensions

00:13:37 where you can.

00:13:39 Are we supposed to be sad or excited

00:13:41 by the fact that our human minds

00:13:43 can’t fully comprehend the kind of mathematics

00:13:45 you’re talking about?

00:13:46 I mean, what do we make of that?

00:13:48 I mean, to me, that makes you quite sad.

00:13:50 It makes it seem like there’s a giant mystery out there

00:13:53 that we’ll never truly get to experience directly.

00:13:58 It is kind of sad how difficult this is.

00:14:01 I mean, or I would put it a different way

00:14:03 that most questions that people have

00:14:06 about this kind of thing,

00:14:08 you can give them a really true answer

00:14:12 and really understand it

00:14:13 but the problem is one more of time.

00:14:16 It’s like, yes, I could explain to you how this works

00:14:20 but you’d have to be willing to sit down with me

00:14:23 and work at this repeatedly for hours and days and weeks

00:14:28 and it’s just gonna take that long for your mind

00:14:31 to really wrap itself around what’s going on

00:14:34 and so that does make things inaccessible which is sad

00:14:40 but it’s just kind of part of life

00:14:43 that we all have a limited amount of time

00:14:45 and we have to decide what we’re gonna spend our time doing.

00:14:49 Speaking of a limited amount of time,

00:14:52 we only have a few hours, maybe a few days together

00:14:55 here on this podcast.

00:14:57 Let me ask you the question of amongst many of the ideas

00:15:02 that you work on in mathematics and physics,

00:15:05 which is the most beautiful idea

00:15:07 or one of the most beautiful ideas, maybe a surprising idea

00:15:11 and once again, unfortunately, the way life works,

00:15:13 we only have a limited time together

00:15:15 to try to convey such an idea.

00:15:18 Okay, well, actually, let me just tell you something which

00:15:22 I’m tempted to kind of start trying to explain

00:15:25 what I think is this most powerful idea

00:15:26 that brings together math and physics,

00:15:28 ideas about groups and representations

00:15:31 and how it fits in quantum mechanics

00:15:33 but in some sense, I wrote a whole textbook about that

00:15:35 and I don’t think we really have time

00:15:37 to get very far into it so.

00:15:39 Well, can I actually, on a small tangent,

00:15:41 you did write a paper towards a grant unified theory

00:15:43 mathematics and physics, maybe you could step there first,

00:15:47 what is the key idea in that paper?

00:15:49 Well, I think we’ve kind of gone over that.

00:15:51 I think that the key idea is what we were talking about

00:15:53 earlier that just kind of a claim that if you look

00:15:58 and see what have been successful ideas in unification

00:16:01 in physics and over the last 50 years or so

00:16:05 and what’s been happening in mathematics

00:16:07 and the kind of thing that Frankel’s book is about

00:16:10 that these are very much the same kind of mathematics

00:16:13 and so it’s kind of an argument that there really is,

00:16:16 you shouldn’t be looking to unify just math

00:16:19 or just fundamental physics but taking inspiration

00:16:23 for looking for new ideas in fundamental physics

00:16:25 that they are gonna be in the same direction

00:16:27 of getting deeper into mathematics

00:16:30 and looking for more inspiration in mathematics

00:16:33 from these successful ideas about fundamental physics.

00:16:37 Could you put words to sort of the disciplines

00:16:39 we’re trying to unify?

00:16:40 So you said number theory, are we literally talking

00:16:42 about all the major fields of mathematics?

00:16:45 So it’s like the number theory, geometry,

00:16:48 so the differential geometry, topology.

00:16:51 Yeah, so the, I mean, one name for this

00:16:55 that this is acquired in mathematics

00:16:57 is the so called Langlands program

00:16:59 and so this started out in mathematics.

00:17:01 It’s that Robert Langlands kind of realized

00:17:05 that a lot of what people were doing

00:17:07 and that was starting to be really successful

00:17:11 in number theory in the 60s

00:17:13 and so that this actually was,

00:17:18 anyway, that this could be thought of

00:17:21 in terms of these ideas about symmetry

00:17:24 and groups and representations

00:17:26 and in a way that was also close

00:17:29 to some ideas about geometry

00:17:32 and then more later on in the 80s, 90s,

00:17:35 there was something called geometric Langlands

00:17:38 that people realize that you could take

00:17:40 what people have been doing in number theory in Langlands

00:17:43 and get rid, just forget about the number theory

00:17:45 and ask what is this telling you about geometry

00:17:48 and you get a whole, some new insights

00:17:49 into certain kinds of geometry that way.

00:17:52 So it’s, anyway, that’s kind of the name

00:17:54 for this area is Langlands and geometric Langlands

00:17:58 and just recently in the last few months,

00:17:59 there’s been, there’s kind of really major paper

00:18:02 that appeared by Peter Schultze and Laurent Farg

00:18:06 where they made some serious advance

00:18:11 to try to understand very much kind of a local problem

00:18:16 of what happens in number theory

00:18:17 near a certain prime number

00:18:19 and they turned this into a problem

00:18:22 of exactly the kind that geometric Langlands people

00:18:26 had been doing, this kind of pure geometry problem

00:18:28 and they found by generalizing mathematics,

00:18:32 they could actually reformulate it in that way

00:18:34 and it worked perfectly well.

00:18:36 One of the things that makes me sad is I’m a pretty

00:18:42 knowledgeable person and then, what is it?

00:18:46 At least I’m in the neighborhood

00:18:48 like theoretical computer science, right?

00:18:50 And it’s still way out of my reach

00:18:52 and so many people talk about like Langlands, for example,

00:18:54 is one of the most brilliant people in mathematics

00:18:57 and just really admire his work

00:18:59 and I can’t, it’s like almost I can’t hear the music

00:19:03 that he composed and it makes me sad.

00:19:05 Yeah, well, I mean, I think unfortunately,

00:19:09 it’s not just you, it’s I think even most mathematicians

00:19:13 have no, really don’t actually understand

00:19:15 what this is about.

00:19:15 I mean, the group of people who really understand

00:19:19 all these ideas and so for instance,

00:19:21 this paper of Schultz and Farg that I was talking about,

00:19:24 the number of people who really actually understand

00:19:26 how that works is anyway, very, very small

00:19:31 and so I think even you find if you talk to mathematicians

00:19:35 and physicists, even they will often feel that,

00:19:38 there’s this really interesting sounding stuff going on

00:19:40 and which I should be able to understand,

00:19:42 it’s kind of in my own field, I have a PhD in

00:19:44 but it still seems pretty clearly far beyond me right now.

00:19:49 Well, if we can step into the back to the question

00:19:52 of beauty, is there an idea that maybe

00:19:56 is a little bit smaller that you find beautiful

00:19:59 in the space of mathematics or physics?

00:20:02 There’s an idea that I kind of went, got a physics PhD

00:20:05 and spent a lot of time learning about mathematics

00:20:07 and I guess it was embarrassing

00:20:10 that I hadn’t really actually understand

00:20:11 this very simple idea until I kind of learned it

00:20:15 when I actually started teaching math classes,

00:20:18 which is maybe that there’s a simple way

00:20:23 to explain kind of the fundamental way

00:20:24 in which algebra and geometry are connected.

00:20:28 So you normally think of geometry as about these spaces

00:20:31 and these points and you think of algebra

00:20:35 as this very abstract thing about these abstract objects

00:20:38 that satisfy certain kinds of relations,

00:20:40 you can multiply them and add them and do stuff

00:20:44 but it’s completely abstract,

00:20:45 there’s nothing geometric about it

00:20:47 but the kind of really fundamental idea

00:20:51 is that unifies algebra and geometry

00:20:54 is to think whenever anybody gives you

00:20:58 what you call an algebra, some abstract thing

00:21:01 of things that you can multiply and add

00:21:04 that you should ask yourself,

00:21:06 is that algebra the space of functions on some geometry?

00:21:10 So one of the most surprising examples of this,

00:21:12 for instance, is a standard kind of thing

00:21:16 that seems to have nothing to do with geometry

00:21:18 is the integers.

00:21:21 So you can multiply them and add them, it’s an algebra

00:21:26 but it seems to have nothing to do with geometry

00:21:31 but what you can, it turns out,

00:21:32 but if you ask yourself this question

00:21:33 and ask, you know, are integers,

00:21:36 can you think, if somebody gives you an integer,

00:21:37 can you think of it as a function on some space,

00:21:40 on some geometry?

00:21:42 And it turns out that yes, you can

00:21:44 and the space is the space of prime numbers

00:21:47 and so what you do is you just,

00:21:48 if somebody gives you an integer,

00:21:50 you can make a function on the prime numbers

00:21:53 by just, you know, at each prime number taking that,

00:21:56 that integer modulo that prime.

00:21:58 So if you say, I don’t know, if you’re given 10,

00:22:02 you know, 10 and you ask, what is its value at two?

00:22:05 Well, it’s five times two, so mod two, it’s zero,

00:22:09 so it’s zero one.

00:22:10 What is its value at three?

00:22:13 Well, it’s nine plus one, so it’s one mod three.

00:22:17 So it’s zero at two, it’s one at three

00:22:19 and you can kind of keep going.

00:22:21 And so this is really kind of a truly fundamental idea.

00:22:26 It’s at the basis of what’s called algebraic geometry

00:22:29 and it just links these two parts of mathematics

00:22:31 that look completely different

00:22:32 and it’s just an incredibly powerful idea

00:22:35 and so much of mathematics emerges

00:22:37 from this kind of simple relation.

00:22:39 So you’re talking about mapping

00:22:41 from one discrete space to another.

00:22:44 So for a second, I thought perhaps mapping

00:22:49 like a continuous space to a discrete space,

00:22:51 like functions over a continuous space, because yeah.

00:22:56 Well, I mean, you can take, if somebody gives you a space,

00:23:00 you can ask, you can say, well, let’s,

00:23:03 and this is also, this is part of the same idea.

00:23:05 The part of the same idea is that if you try

00:23:07 and do geometry and somebody tells you, here’s a space,

00:23:10 that what you should do is you should wait,

00:23:11 so say, wait a minute,

00:23:12 maybe I should be trying to solve this using algebra.

00:23:15 And so if I do that, the way to start is,

00:23:18 you give me the space,

00:23:19 I start to think about the functions of the space, okay?

00:23:22 So for each point in the space, I associate a number.

00:23:26 I can take different kinds of functions

00:23:27 and different kinds of values,

00:23:29 but basically functions on a space.

00:23:31 So what this insight is telling you is that

00:23:36 if you’re a geometer, often the way to work

00:23:39 is to change your problem into algebra

00:23:41 by changing your space, stop thinking about your space

00:23:44 and the points in it and think about the functions on it.

00:23:47 And if you’re an algebraist

00:23:49 and you’ve got these abstract algebraic gadgets

00:23:52 that you’re multiplying and adding, say, wait a minute,

00:23:55 are those gadgets, can I think of them in some way

00:23:58 as a function on a space?

00:23:59 What would that space be

00:24:00 and what kind of functions would they be?

00:24:02 And that going back and forth really brings

00:24:05 these two completely different looking areas

00:24:08 of mathematics together.

00:24:09 Do you have particular examples where it allowed

00:24:13 to prove some difficult things

00:24:15 by jumping from one to the other?

00:24:16 Is that something that’s a part of modern mathematics

00:24:19 where such jumps are made?

00:24:21 Oh yeah, this is kind of all the time.

00:24:23 Much of modern number theory is kind of based on this idea.

00:24:27 But, and when you start doing this,

00:24:29 you start to realize that you need,

00:24:32 what simple things on one side of the algebra

00:24:37 start to require you to think about the other side,

00:24:40 about geometry in a new way.

00:24:42 You have to kind of get a more sophisticated idea

00:24:44 about geometry, or if you start thinking

00:24:46 about the functions on a space,

00:24:49 you may need a more sophisticated kind of algebra.

00:24:52 But in some sense, I mean,

00:24:53 much or most of modern number theory

00:24:55 is based upon this move to geometry.

00:24:58 And there’s also a lot of geometry

00:25:01 and topology is also based upon, yeah, change.

00:25:05 If you want to understand the topology of something,

00:25:06 you look at the functions, you do drum comology

00:25:09 and you get the topology.

00:25:12 Anyway.

00:25:13 Well, let me ask you then the ridiculous question.

00:25:16 You said that this idea is beautiful.

00:25:18 Can you formalize the definition of the word beautiful?

00:25:22 And why is this beautiful?

00:25:24 First, why is this beautiful?

00:25:26 And second, what is beautiful?

00:25:29 Yeah, well, and I think there are many different things

00:25:32 you can find beautiful for different reasons.

00:25:34 I mean, I think in this context, the notion of beauty,

00:25:37 I think really is just kind of an idea is beautiful

00:25:41 if it’s packages a huge amount of kind of power

00:25:45 and information into something very simple.

00:25:48 So in some sense, you can almost kind of try and measure it

00:25:54 in the sense of what are the implications of this idea?

00:25:58 What non trivial things does it tell you

00:26:00 versus how simply can you express the idea?

00:26:06 And so.

00:26:07 So the level of compression,

00:26:08 what is it correlates with beauty?

00:26:12 Yeah, that’s one aspect of it.

00:26:15 And so you can start to tell that an idea

00:26:16 is becoming uglier and uglier

00:26:18 as you start kind of having to,

00:26:21 it doesn’t quite do what you want.

00:26:22 So you throw in something else to the idea

00:26:24 and you keep doing that until you get what you want.

00:26:27 But that’s how you know you’re doing something uglier

00:26:29 and uglier when you have to kind of keep adding

00:26:31 and more into what was originally a fairly simple idea

00:26:36 and making it more and more complicated

00:26:40 to get what you want.

00:26:41 Okay, so let’s put some philosophical words on the table

00:26:45 and try to make some sense of them.

00:26:47 One word is beauty, another one is simplicity

00:26:49 as you mentioned, another one is truth.

00:26:53 So do you have a sense if I give you two theories,

00:26:57 one is simpler, one is more complicated.

00:27:02 Do you have a sense of which one is more likely to be true

00:27:05 to capture deeply the fabric of reality,

00:27:13 the simple one or the more complicated one?

00:27:15 Yeah, I think all of our evidence,

00:27:18 what we see in the history of the subject

00:27:20 is the simpler one though.

00:27:22 Often it’s a surprise, it’s simpler in a surprising way.

00:27:26 But yeah, that we just don’t, we just,

00:27:31 anyway, the kind of best theories

00:27:32 we’ve been coming up with are ultimately

00:27:35 when properly understood, relatively simple

00:27:38 and much, much simpler than you would expect them to be.

00:27:41 Do you have a good explanation why that is?

00:27:43 Is it just because humans want it to be that way?

00:27:46 Are we just like ultra biased

00:27:47 and we just kind of convince ourselves

00:27:51 that simple is better because we find simplicity beautiful?

00:27:53 Or is there something about our actual universe

00:27:57 that at the core is simple?

00:28:00 My own belief is that there is something about a universe

00:28:02 that’s simple and as I was trying to say that,

00:28:05 there is some kind of fundamental thing about math,

00:28:08 physics and all this picture, which is in some sense simple.

00:28:14 It’s true that, it’s of course true that our minds

00:28:18 have certain, are very limited

00:28:20 and can certainly do certain things and not others.

00:28:23 So it’s in principle possible

00:28:26 that there’s some great insight in,

00:28:29 there are a lot of insights into the way the world works,

00:28:31 which just aren’t accessible to us because

00:28:33 that’s not the way our minds work, we don’t.

00:28:35 And that what we’re seeing, this kind of simplicity

00:28:37 is just because that’s all we ever have any hope of seeing.

00:28:42 So there’s a brilliant physicist

00:28:46 by the name of Sabine Hassenfelder

00:28:49 who both agrees and disagrees with you.

00:28:51 I suppose agrees that the final answer will be simple.

00:28:57 Yeah.

00:28:58 But simplicity and beauty leads us astray

00:29:01 in the local pockets of scientific progress.

00:29:05 Do you agree with her disagreement

00:29:08 and do you disagree with her agreement?

00:29:11 And agree with the agreement and so on.

00:29:14 Anyway, yes, I found it was really fascinating

00:29:17 reading her book and anyway,

00:29:19 I was finding disagreeing with a lot,

00:29:21 but then at the end when she says yes,

00:29:23 when we find, when we actually figure this out,

00:29:26 it will be simple and okay, so we agree in the end.

00:29:31 But does beauty lead us astray,

00:29:32 which is the core thesis of her work in that book.

00:29:37 I actually, I guess I do disagree with her on that so much.

00:29:41 I don’t think, and especially,

00:29:42 and I actually fairly strongly disagree with her

00:29:44 about sometimes the way she’ll refer to math.

00:29:47 And so the problem is, physicists and people in general

00:29:51 just refer to it as math and they’re often meaning

00:29:56 not what I would call math,

00:29:57 which is the interesting ideas of math,

00:29:59 but just some complicated calculation.

00:30:03 And so I guess my feeling about it is more that it’s very,

00:30:09 the problem with talking about simplicity

00:30:11 and using simplicity as a guide is that it’s very,

00:30:16 it’s very easy to fool yourself

00:30:17 and it’s very easy to decide to fall in love with an idea.

00:30:23 You have an idea, you think, oh, this is great

00:30:26 and you fall in love with it.

00:30:26 And it’s like any kind of love affair,

00:30:29 it’s very easy to believe that the object of your affections

00:30:32 is much more beautiful than the others might think

00:30:35 and that they really are.

00:30:36 And that’s very, very easy to do.

00:30:39 So if you say, I’m just gonna pursue ideas about beauty

00:30:43 and this and mathematics and this,

00:30:46 it’s extremely easy to just fool yourself, I think.

00:30:50 And I think that’s a lot of what the story

00:30:54 she was thinking of about where people have gone astray,

00:30:56 that I think it’s, I would argue that it’s more people,

00:30:59 it’s not that there was some simple, powerful,

00:31:01 wonderful idea which they’d found

00:31:03 and it turned out not to be useful,

00:31:08 but it was more that they kind of fooled themselves

00:31:10 that this was actually a better idea than it really was

00:31:13 and that it was simpler and more beautiful

00:31:15 than it really was, is a lot of the story.

00:31:18 I see, so it’s not that the simplicity of beauty

00:31:20 leads us astray, it’s just people are people

00:31:22 and they fall in love with whatever idea they have

00:31:27 and then they weave narratives around that idea

00:31:30 or they present it in such a way

00:31:31 that emphasizes the simplicity and the beauty.

00:31:36 Yeah, that’s part of it.

00:31:37 But I mean, the thing about physics that you have

00:31:40 is that what really can tell,

00:31:44 if you can do an experiment and check

00:31:46 and see if nature is really doing what your idea expects,

00:31:50 you do in principle have a way of really testing it

00:31:54 and it’s certainly true that if you thought

00:31:58 you had a simple idea and that doesn’t work

00:32:00 and you go out and do an experiment

00:32:01 and what actually does work is some more,

00:32:04 maybe some more complicated version of it,

00:32:05 that can certainly happen and that can be true.

00:32:10 I think her emphasis is more,

00:32:13 that I don’t really disagree with,

00:32:14 is that people should be concentrating

00:32:18 on when they’re trying to develop better theories

00:32:21 on more on self consistency, not so much on beauty,

00:32:25 but not is this idea beautiful,

00:32:28 but is there something about the theory

00:32:30 which is not quite consistent and use that as a guide

00:32:35 that there’s something wrong there which needs fixing.

00:32:37 And so I think that part of her argument,

00:32:40 I think we’re on the same page about.

00:32:43 What is consistency and inconsistencies?

00:32:48 What exactly, do you have examples in mind?

00:32:53 Well, it can be just simple inconsistency

00:32:55 between theory and an experiment that if you,

00:32:58 so we have this great fundamental theory,

00:33:01 but there are some things that we see out there

00:33:02 which don’t seem to fit in it,

00:33:04 like dark energy and dark matter, for instance.

00:33:07 But if there’s something which you can’t test experimentally,

00:33:09 I think she would argue and I would agree

00:33:12 that, for instance, if you’re trying to think about gravity

00:33:15 and how are you gonna have a quantum theory of gravity,

00:33:17 you should kind of test any of your ideas

00:33:21 with kind of a thought experiment.

00:33:24 Does this actually give a consistent picture

00:33:26 of what’s gonna happen, of what happens

00:33:28 in this particular situation or not?

00:33:32 So this is a good example.

00:33:33 You’ve written about this.

00:33:36 Since quantum gravitational effects are really small,

00:33:40 super small, arguably unobservably small,

00:33:44 should we have hope to arrive

00:33:46 at a theory of quantum gravity somehow?

00:33:49 What are the different ways we can get there?

00:33:51 You’ve mentioned that you’re not as interested

00:33:53 in that effort because basically, yes,

00:33:56 you cannot have ways to scientifically validate it

00:34:02 given the tools of today.

00:34:04 Yeah, I’ve actually, you know, I’ve over the years

00:34:06 certainly spent a lot of time learning about gravity

00:34:08 and about attempts to quantize it, but it hasn’t been

00:34:11 that much in the past the focus

00:34:14 of what I’ve been thinking about.

00:34:16 But I mean, my feeling was always, you know,

00:34:18 as I think Sabina would agree that the, you know,

00:34:22 one way you can pursue this if you can’t do experiments

00:34:25 is just this kind of search for consistency.

00:34:29 You know, it can be remarkably hard to come up

00:34:31 with a completely consistent model of this

00:34:34 in a way that brings together quantum mechanics

00:34:37 and general relativity.

00:34:39 And that’s, I think, kind of been the traditional way

00:34:42 that people who have pursued quantum gravity

00:34:44 have often pursued, you know,

00:34:48 we have the best route to finding a consistent theory

00:34:52 of quantum gravity and string theorists will tell you this,

00:34:55 other people will tell you it,

00:34:57 it’s kind of what people argue about.

00:35:00 But the problem with all of that is that you end up,

00:35:03 you know, the danger is that you end up with,

00:35:08 that everybody could be successful.

00:35:10 Everybody’s program for how to find a theory

00:35:14 of quantum gravity, you know, ends up with something

00:35:16 that is consistent.

00:35:18 And so, and in some sense you could argue

00:35:20 this is what happened to the string theorists.

00:35:23 They solved their problem of finding a consistent theory

00:35:26 of quantum gravity and they ended up,

00:35:27 but they found 10 to the 500 solutions.

00:35:30 So you, you know, if you believe that everything

00:35:34 that they would like to be true is true,

00:35:35 well, okay, you’ve got a theory,

00:35:38 but it ends up being kind of useless

00:35:41 because it’s just one of an infinite,

00:35:43 essentially infinite number of things

00:35:46 which you have no way to experimentally distinguish.

00:35:48 And so this is just a depressing situation.

00:35:52 But I do think that there is a,

00:35:55 so again, I think pursuing ideas about what,

00:35:57 more about beauty and how can you integrate

00:36:01 and unify these issues about gravity

00:36:04 with other things we know about physics.

00:36:06 And can you find a theory where these fit together

00:36:08 in a way that makes sense and hopefully predict something.

00:36:12 That’s much more promising.

00:36:14 Well, it makes sense and hopefully,

00:36:15 I mean, we’ll sneak up onto this question a bunch of times

00:36:19 because you kind of said a few slightly contradictory things

00:36:23 which is like, it’s nice to have a theory that’s consistent,

00:36:27 but then if the theory is consistent,

00:36:29 it doesn’t necessarily mean anything.

00:36:32 So like.

00:36:33 It’s not enough, it’s not enough.

00:36:35 It’s not enough and that’s the problem.

00:36:36 So it’s like, it keeps coming back to,

00:36:39 okay, there should be some experimental validation.

00:36:43 So, okay, let’s talk a little bit about strength theory.

00:36:47 You’ve been a bit of an outspoken critic of strength theory.

00:36:52 Maybe one question first to ask is what is strength theory?

00:36:56 And beyond that, why is it wrong?

00:37:01 Or rather as the title of your blog says, not even wrong.

00:37:06 Okay.

00:37:07 Well, one interesting thing

00:37:08 about the current state of strength theory is that,

00:37:10 I think it, I’d argue it’s actually very, very difficult

00:37:13 to at this point to say what strength theory means.

00:37:15 If people say they’re a strength theorist,

00:37:17 what they mean and what they’re doing

00:37:19 is kind of hard to pin down the meaning of the term.

00:37:24 But the initial meaning I think goes back to,

00:37:28 there was kind of a series of developments starting in 1984

00:37:32 in which people felt that they had found a unified theory

00:37:36 of our so called standard model of all the standard,

00:37:41 well known kind of particle interactions and gravity

00:37:44 and it all fit together in a quantum theory.

00:37:46 And that you could do this in a very specific way

00:37:49 by instead of thinking about having a quantum theory

00:37:54 of particles moving around in space time,

00:37:57 think about a quantum theory of kind of one dimensional

00:38:00 loops moving around in space time, so called strings.

00:38:03 And so instead of one degree of freedom,

00:38:06 these have an infinite number of degrees of freedom.

00:38:08 It’s a much more complicated theory, but you can imagine,

00:38:12 okay, we’re gonna quantize this theory of loops

00:38:14 moving around in space time.

00:38:16 And what they found is that you could do this

00:38:21 and you could fairly, relatively straightforwardly

00:38:23 make sense of such a quantum theory,

00:38:26 but only if space and time together were 10 dimensional.

00:38:31 And so then you had this problem,

00:38:32 again, the problem I referred to at the beginning of,

00:38:34 okay, now once you make that move,

00:38:37 you gotta get rid of six dimensions.

00:38:39 And so the hope was that you could get rid

00:38:42 of the six dimensions by making them very small

00:38:44 and that consistency of the theory would require

00:38:48 that these six dimensions satisfy a very specific condition

00:38:52 called being a Calabi out manifold.

00:38:55 And that we knew very, very few examples of this.

00:38:58 So what got a lot of people very excited back in 84, 85

00:39:02 was the hope that you could just take

00:39:05 this 10 dimensional string theory

00:39:07 and find one of a limited number of possible ways

00:39:10 of getting rid of six dimensions by making them small

00:39:14 and then you would end up with an effective

00:39:16 four dimensional theory, which looked like the real world.

00:39:18 This was the hope.

00:39:20 So then there’s then a very long story

00:39:22 about what happened to that hope over the years.

00:39:25 I would argue and part of the point of the book

00:39:28 and its title was that this ultimately was a failure

00:39:33 that you ended up, that this idea just didn’t,

00:39:38 there ended up being just too many ways of doing this

00:39:41 and you didn’t know how to do this consistently,

00:39:44 that it was kind of not even wrong in the sense

00:39:46 that you couldn’t even, you never could pin it down

00:39:49 well enough to actually get a real falsifiable prediction

00:39:53 out of it that would tell you it was wrong.

00:39:55 But it was kind of in the realm of ideas

00:39:59 which initially looked good, but the more you look at them,

00:40:02 they just, they don’t work out the way you want

00:40:05 and they don’t actually end up carrying the power

00:40:07 or that you originally had this vision of.

00:40:10 And yes, the book title is not even wrong.

00:40:14 Your blog, your excellent blog title is not even wrong.

00:40:17 Okay, but there’s nevertheless been a lot of excitement

00:40:20 about string theory through the decades, as you mentioned.

00:40:24 What are the different flavors of ideas that came,

00:40:29 like that branched out?

00:40:31 You mentioned 10 dimensions.

00:40:32 You mentioned loops with infinite degrees of freedom.

00:40:36 What other interesting ideas to you

00:40:38 that kind of emerged from this world?

00:40:41 Well, yeah, I mean, the problem

00:40:42 with talking about the whole subject

00:40:43 and part of the reason I wrote the book

00:40:45 is that it gets very, very complicated.

00:40:48 I mean, there’s a huge amount,

00:40:52 a lot of people got very interested in this,

00:40:54 a lot of people worked on it.

00:40:55 And in some sense, I think what happened

00:40:57 is exactly because the idea didn’t really work

00:41:01 that this caused people to,

00:41:04 instead of focusing on this one idea

00:41:06 and digging in and working on that,

00:41:08 they just kind of kept trying new things.

00:41:11 And so people, I think, ended up wandering around

00:41:14 in a very, very rich space of ideas

00:41:15 about mathematics and physics

00:41:17 and discovering all sorts of really interesting things.

00:41:19 It’s just the problem is there tended

00:41:22 to be an inverse relationship

00:41:23 between how interesting and beautiful and fruitful

00:41:26 this new idea that they were trying to pursue was

00:41:28 and how much it looked like the real world.

00:41:31 So there’s a lot of beautiful mathematics came out of it.

00:41:34 I think one of the most spectacular

00:41:36 is what the physicists call

00:41:38 two dimensional conformal field theory.

00:41:40 And so these are basically quantum field theories

00:41:44 and kind of think of it as one space

00:41:46 and one time dimension,

00:41:47 which have just this huge amount of symmetry

00:41:51 and a huge amount of structure,

00:41:53 which there’s some totally fantastic mathematics behind it.

00:41:57 And again, and some of that mathematics

00:42:00 is exactly also what appears in the Langlands program.

00:42:03 So a lot of the first interaction between math and physics

00:42:07 around the Langlands program has been

00:42:09 around these two dimensional conformal field theories.

00:42:12 Is there something you could say

00:42:15 about what are the major problems are with string theory?

00:42:18 So like, besides that there’s no experimental validation,

00:42:25 you’ve written that a big hole in string theory

00:42:30 has been its perturbative definition.

00:42:34 Perhaps that’s one, can you explain what that means?

00:42:36 Well, maybe to begin with,

00:42:38 I think the simplest thing to say is,

00:42:42 the initial idea really was that,

00:42:45 okay, we have this, instead of what’s great

00:42:48 is we have this thing that only works,

00:42:50 it’s very structured and has to work in a certain way

00:42:54 for it to make sense.

00:42:55 But then you ended up in 10 space time dimensions.

00:43:01 And so to get back to physics,

00:43:03 you had to get rid of five of the dimensions,

00:43:05 six of the dimensions.

00:43:06 And the bottom line I would say in some sense is very simple

00:43:09 that what people just discovered is just,

00:43:12 there’s kind of no particularly nice way of doing this,

00:43:15 there’s an infinite number of ways of doing it

00:43:17 and you can get whatever you want

00:43:18 depending on how you do it.

00:43:20 So you end up the whole program of starting at 10 dimensions

00:43:24 and getting to four just kind of collapses

00:43:26 out of a lack of any way to kind of get to where you want

00:43:29 because you can get anything.

00:43:31 The hope around that problem has always been

00:43:34 that the standard formulation that we have of string theory,

00:43:38 which is, you can go by the name perturbative,

00:43:42 but it’s kind of, there’s a standard way we know

00:43:46 of given a classical theory of constructing a quantum theory

00:43:50 and working with it, which is the so called

00:43:56 perturbation theory that we know how to do.

00:43:59 And that by itself just doesn’t give you any hint

00:44:04 as to what to do about the six dimensions.

00:44:06 So actual perturbed string theory by itself

00:44:09 really only works in 10 dimensions.

00:44:11 So you have to start making some kinds of assumptions

00:44:14 about how I’m gonna go beyond this formulation

00:44:19 that we really understand of string theory

00:44:21 and get rid of these six dimensions.

00:44:24 So kind of the simplest one was the Klabiau postulate,

00:44:29 but when that didn’t really work out,

00:44:31 people have tried more and more different things.

00:44:33 And the hope has always been that the solution,

00:44:38 this problem would be that you would find a deeper

00:44:41 and better understanding of what string theory is

00:44:44 that would actually go beyond this perturbative expansion

00:44:47 and which would generalize this.

00:44:51 And that once you had that, it would solve this problem of,

00:44:57 it would pick out what to do with the six dimensions.

00:44:59 How difficult is this problem?

00:45:01 So if I could restate the problem,

00:45:05 it seems like there’s a very consistent physical world

00:45:09 operating in four dimensions.

00:45:13 And how do you map a consistent physical world

00:45:16 in 10 dimensions to a consistent physical world

00:45:19 in four dimensions?

00:45:21 And how difficult is this problem?

00:45:23 Is that something you can even answer?

00:45:27 Just in terms of physics intuition,

00:45:30 in terms of mathematics,

00:45:32 mapping from 10 dimensions to four dimensions.

00:45:35 Well, basically, I mean, you have to get rid

00:45:36 of the six of the dimensions.

00:45:38 So there’s kind of two ways of doing it.

00:45:41 One is what we called compactification.

00:45:44 You say that there really are 10 dimensions,

00:45:46 but for whatever reason,

00:45:48 six of them are so, so small, we can’t see them.

00:45:51 So you basically start out with 10 dimensions

00:45:54 and what we call, make six of them not go out to infinity,

00:45:58 but just kind of a finite extent

00:46:00 and then make that size go down so small, it’s unobservable.

00:46:05 But that’s like, that’s a math trick.

00:46:08 So can you also help me build an intuition

00:46:11 about how rich and interesting the world

00:46:15 in those six dimensions is?

00:46:17 So compactification seems to imply…

00:46:21 Well, it’s not very interesting.

00:46:22 Well, no, but the problem is that what you learn

00:46:24 if you start doing mathematics

00:46:26 and looking at geometry and topology

00:46:28 and more and more dimensions is that,

00:46:31 I mean, asking the question like,

00:46:34 what are all possible six dimensional spaces?

00:46:36 It’s just, it’s kind of an unnatural question.

00:46:38 It’s just, I mean,

00:46:39 it’s even kind of technically undecidable in some way.

00:46:42 There are too many things you can do with all these,

00:46:46 if you start trying to make,

00:46:47 if you start trying to make one dimensional spaces,

00:46:49 it’s like, well, you got a line, you can make a circle,

00:46:52 you can make graphs, you can kind of see what you can do.

00:46:55 But as you go to higher and higher dimensions,

00:46:58 there are just so many ways you can put things together

00:47:02 of and get something of that dimensionality.

00:47:05 And so unless you have some very, very strong principle,

00:47:09 we’re just gonna pick out some very specific ones

00:47:12 of these six dimensional spaces.

00:47:15 And there are just too many of them

00:47:17 and you can get anything you want.

00:47:19 So if you have 10 dimensions,

00:47:22 the kind of things that happen,

00:47:24 say that’s actually the way,

00:47:26 that’s actually the fabric of our reality is 10 dimensions.

00:47:29 There’s a limited set of behaviors of objects.

00:47:33 I don’t know even know what the right terminology

00:47:35 to use that can occur within those dimensions,

00:47:39 like in reality.

00:47:41 And so like what I’m getting at is like,

00:47:44 is there some consistent constraints?

00:47:47 So if you have some constraints that map to reality,

00:47:51 then you can start saying like,

00:47:53 dimension number seven is kind of boring.

00:47:56 All the excitement happens in the spatial dimensions,

00:47:58 one, two, three.

00:48:00 And time is also kind of boring.

00:48:02 And like some are more exciting than others,

00:48:05 or we can use our metric of beauty.

00:48:08 Some dimensions are more beautiful than others.

00:48:10 Once you have an actual understanding

00:48:12 of what actually happens in those dimensions

00:48:15 in our physical world,

00:48:16 as opposed to sort of all the possible things

00:48:18 that could happen.

00:48:19 In some sense, I mean,

00:48:20 just the basic fact is you need to get rid of them.

00:48:22 We don’t see them.

00:48:23 So you need to somehow explain them.

00:48:25 The main thing you’re trying to do

00:48:26 is to explain why we’re not seeing them.

00:48:28 And so you have to come up with some theory

00:48:32 of these extra dimensions and how they’re gonna behave.

00:48:35 And string theory gives you some ideas

00:48:38 about how to do that.

00:48:39 But the bottom line is where you’re trying to go

00:48:43 with this whole theory you’re creating

00:48:45 is to just make all of its effects essentially unobservable.

00:48:49 So it’s not a really,

00:48:54 it’s an inherently kind of dubious and worrisome thing

00:48:57 that you’re trying to do there.

00:48:58 Why are you just adding in all this stuff

00:49:00 and then trying to explain why we don’t see it?

00:49:02 Exactly.

00:49:03 This may be a dumb question,

00:49:04 but is this an obvious thing to state

00:49:07 that those six dimensions are unobservable

00:49:11 or anything beyond four dimensions is unobservable?

00:49:16 Or do you leave a little door open

00:49:19 to saying the current tools of physics,

00:49:23 and obviously our brains aren’t unable to observe them,

00:49:26 but we may need to come up with methodologies

00:49:29 for observing them.

00:49:30 So as opposed to collapsing your mathematical theory

00:49:33 into four dimensions,

00:49:35 leaving the door open a little bit too,

00:49:37 maybe we need to come up with tools

00:49:38 that actually allow us to directly measure those dimensions.

00:49:42 Yes, I mean, you can certainly ask,

00:49:45 assume that we’ve got model,

00:49:49 look at models with more dimensions and ask,

00:49:51 what would the observable effects, how would we know this?

00:49:54 And you go out and do experiments.

00:49:55 So for instance, you have a,

00:49:58 like gravitationally you have an inverse square law of forces.

00:50:02 If you had more dimensions,

00:50:04 that inverse square law would change to something else.

00:50:06 So you can go and start measuring the inverse square law

00:50:09 and say, okay, inverse square law is working,

00:50:12 but maybe if I get,

00:50:14 and it turns out to be actually kind of very, very hard

00:50:16 to measure gravitational effects

00:50:18 and even kind of somewhat macroscopic distances

00:50:21 because they’re so small.

00:50:23 So you can start looking at the inverse square law

00:50:26 and say, start trying to measure it

00:50:28 at shorter and shorter distances

00:50:29 and see if there were extra dimensions

00:50:33 at those distance scales,

00:50:34 you would start to see the inverse square law fail.

00:50:36 And so people look for that and again, you don’t see it,

00:50:40 but you can, I mean, there’s all sorts of experiments

00:50:43 of this kind you can imagine which test

00:50:46 for effects of extra dimensions

00:50:48 at different distance scales, but none of them,

00:50:53 I mean, they all just don’t work.

00:50:55 Nothing yet.

00:50:58 Nothing yet, but you could say, ah, but it’s just much,

00:51:01 much smaller, you can say that.

00:51:05 Which by the way makes LIGO

00:51:06 and the detection of gravitational waves

00:51:09 quite an incredible project.

00:51:13 Ed Witten is often brought up

00:51:15 as one of the most brilliant mathematicians

00:51:17 and physicists ever.

00:51:21 What do you make of him and his work on string theory?

00:51:24 Well, I think he’s a truly remarkable figure.

00:51:26 I’ve had the pleasure of meeting him first

00:51:30 when he was a postdoc.

00:51:31 And I mean, he’s just completely amazing

00:51:36 mathematician and physicist.

00:51:38 And he’s quite a bit smarter

00:51:41 than just about any of the rest of us

00:51:43 and also more hardworking.

00:51:44 It’s a kind of frightening combination

00:51:46 to see how much he’s been able to do.

00:51:50 But I would actually argue that his greatest work,

00:51:53 the things that he’s done that have been of

00:51:55 just this mind blowing significance of giving us,

00:51:58 I mean, he’s completely revolutionized

00:52:00 some areas of mathematics.

00:52:02 He’s totally revolutionized the way we understand

00:52:04 the relations between mathematics and physics.

00:52:07 And most of those, his greatest work

00:52:10 is stuff that has little or nothing

00:52:13 to do with string theory.

00:52:15 I mean, for instance, so he was actually one of Fields.

00:52:19 The very strange thing about him in some sense

00:52:20 is that he doesn’t have a Nobel Prize.

00:52:23 So there’s a very large number of people

00:52:25 who are nowhere near as smart as he is

00:52:28 and don’t work anywhere near as hard

00:52:30 who have Nobel Prizes.

00:52:31 I think he just had the misfortune

00:52:33 of coming into the field at a time

00:52:35 when things had gotten much, much, much tougher

00:52:37 and nobody really had, no matter how smart you were,

00:52:41 it was very hard to come up with a new idea

00:52:44 that was gonna work physically and get you a Nobel Prize.

00:52:47 But he got a Fields Medal for a certain work he did

00:52:52 in mathematics, and that’s just completely unheard of.

00:52:56 For mathematicians to give a Fields Medal

00:52:58 to someone outside their field in physics

00:53:00 is really, you wouldn’t have, before he came around,

00:53:05 I don’t think anybody would have thought

00:53:06 that was even conceivable.

00:53:08 So you’re saying he came into the field

00:53:11 of theoretical physics at a time when,

00:53:13 and still to today, is you can’t get a Nobel Prize

00:53:18 for purely theoretical work.

00:53:20 The specific problem of trying to do better

00:53:22 than the standard, the standard model

00:53:23 is just this insanely successful thing,

00:53:26 and it kind of came together in 1973, pretty much.

00:53:30 And all of the people who kind of were involved

00:53:34 in that coming together, many of them ended up

00:53:37 with Nobel Prizes for that.

00:53:38 But if you look post 1973, pretty much,

00:53:43 it’s a little bit more, there’s some edge cases,

00:53:47 if you like, but if you look post 1973

00:53:50 at what people have done to try to do better

00:53:53 than the standard model and to get a better idea,

00:53:56 it really hasn’t, it’s been too hard a problem.

00:53:58 It hasn’t worked.

00:53:59 The theory’s too good.

00:54:00 And so it’s not that other people went out there

00:54:03 and did it, and not him, and that they got Nobel Prizes

00:54:07 for doing it, it’s just that no one really,

00:54:08 the kind of thing he’s been trying to do

00:54:10 with string theory is not, no one has been able to do

00:54:13 since 1973.

00:54:15 Is there something you can say about the standard model,

00:54:17 so the four laws of physics that seems to work very well,

00:54:20 and yet people are striving to do more?

00:54:24 Talking about unification, so on, why?

00:54:27 What’s wrong, what’s broken about the standard model?

00:54:30 Why does it need to be improved?

00:54:33 I mean, the thing that’s gets most attention

00:54:34 is gravity, that we have trouble.

00:54:39 So you want to, in some sense, integrate what we know

00:54:44 about the gravitational force with it

00:54:46 and have a unified quantum field theory

00:54:48 that has gravitational interactions also.

00:54:50 So that’s the big problem everybody talks about.

00:54:53 I mean, but it’s also true that if you look

00:54:55 at the standard model, it has these very, very deep,

00:54:58 beautiful ideas, but there’s certain aspects of it

00:55:01 that are very, let’s just say that they’re not beautiful.

00:55:08 They’re not, you have to, to make the thing work,

00:55:11 you have to throw in lots and lots of extra parameters

00:55:14 at various points, and a lot of this has to do

00:55:17 with the so called Higgs mechanism and the Higgs field,

00:55:21 that if you look at the theory, it’s everything is,

00:55:25 if you forget about the Higgs field and what it needs to do,

00:55:28 the rest of the theory is very, very constrained

00:55:33 and has very, very few free parameters,

00:55:35 really a very small number.

00:55:36 There’s very small number of parameters

00:55:38 and a few integers which tell you what the theory is.

00:55:40 To make this work as a theory of the real world,

00:55:42 you need a Higgs field and you need to,

00:55:45 it needs to do something.

00:55:48 And once you introduce that Higgs field,

00:55:50 all sorts of parameters make an appearance.

00:55:54 So now we’ve got 20 or 30 or whatever parameters

00:55:58 that are gonna tell you what all the masses of things are

00:56:00 and what’s gonna happen.

00:56:02 So you’ve gone from a very tightly constrained thing

00:56:05 with a couple of parameters to this thing,

00:56:09 which the minute you put it in,

00:56:11 you had to add all this extra,

00:56:13 all these extra parameters to make things work.

00:56:15 And so that, it may be one argument as well,

00:56:19 that’s just the way the world is,

00:56:20 and the fact that you don’t find that aesthetically pleasing

00:56:24 is just your problem, or maybe we live in a multiverse

00:56:27 and those numbers are just different in every universe.

00:56:30 But another reasonable conjecture is just that,

00:56:33 well, this is just telling us that there’s something

00:56:36 we don’t understand about what’s going on in a deeper way,

00:56:40 which would explain those numbers.

00:56:41 And there’s some kind of deeper idea

00:56:44 about where the Higgs field comes from and what’s going on,

00:56:47 which we haven’t figured out yet.

00:56:49 And that’s what we should look for.

00:56:52 But to stick on string theory a little bit longer,

00:56:55 could you play devil’s advocate

00:56:58 and try to argue for string theory,

00:57:01 why it is something that deserved the effort that it got,

00:57:07 and still, like if you think of it as a flame,

00:57:10 still should be a little flame that keeps burning?

00:57:14 Well, I think the, I mean, the most positive argument

00:57:17 for it is all sorts of new ideas about mathematics

00:57:22 and about parts of physics really emerge from it.

00:57:24 That was very a fruitful source of ideas.

00:57:28 And I think this is actually one argument you’ll definitely,

00:57:30 which I kind of agree with,

00:57:31 I’ll hear from Whitten and from other string theorists,

00:57:34 say that this is just such a fruitful and inspiring idea

00:57:38 and it’s led to so many other different things

00:57:41 coming out of it that there must be something

00:57:43 right about this.

00:57:45 And that’s, okay, anyway, I think that’s probably

00:57:48 the strongest thing that they’ve got.

00:57:52 But you don’t think there’s aspects to it

00:57:55 that could be neighboring to a theory

00:58:00 that does unify everything, to a theory of everything.

00:58:03 Like it could, it may not be exactly,

00:58:08 exactly the theory, but sticking on it longer

00:58:11 might get us closer to the theory of everything.

00:58:14 Well, the problem with it now really

00:58:15 is that you really don’t know what it is now.

00:58:17 You’ve never, nobody has ever kind of come up

00:58:19 with this nonperturbative theory.

00:58:23 So it’s become more and more frustrating

00:58:27 and an odd activity to try to argue with a string theorist

00:58:30 about string theory because it’s become

00:58:34 less and less well defined what it is.

00:58:37 And it’s become actually more and more kind of a,

00:58:40 whether you have this weird phenomenon

00:58:42 of people calling themselves string theorists

00:58:44 when they’ve never actually worked on any theory

00:58:47 where there are any strings anywhere.

00:58:49 So what has actually happened kind of sociologically

00:58:52 is that you started out with this

00:58:54 fairly well defined proposal.

00:58:56 And then I would argue because that didn’t work,

00:58:59 people branched out in all sorts of directions

00:59:01 doing all sorts of things.

00:59:02 It became farther and farther removed from that.

00:59:05 And for sociological reasons,

00:59:07 the ones who kind of started out or now

00:59:12 or were trained by the people who worked on that

00:59:15 have now become this string theorists.

00:59:18 And, but it’s becoming almost more

00:59:23 kind of a tribal denominator than a,

00:59:26 I think so it’s very hard to know

00:59:28 what you’re arguing about

00:59:29 when you’re arguing about string theory these days.

00:59:30 Well, to push back on that a little bit,

00:59:32 I mean, string theory is just a term, right?

00:59:34 It doesn’t, like you could,

00:59:37 like this is the way language evolves

00:59:39 is it could start to represent something

00:59:41 more than just the theory that involves strings.

00:59:43 It could represent the effort to unify the laws of physics.

00:59:49 Right?

00:59:50 At high dimensions with these super tiny objects, right?

00:59:54 Or something like that.

00:59:56 I mean, we can sort of put string theory aside.

00:59:59 So for example, neural networks

01:00:00 in the space of machine learning,

01:00:02 there was a time when they were extremely popular.

01:00:05 They became much, much less popular

01:00:07 to a point where if you mentioned neural networks,

01:00:09 you’re getting no funding

01:00:10 and you’re not going to be respected at conferences.

01:00:13 And then once again,

01:00:15 neural networks became all the rage

01:00:18 about 10, 15 years ago.

01:00:20 And as it goes up and down

01:00:22 and a lot of people would argue

01:00:23 that using terminology like machine learning

01:00:26 and deep learning is often misused over general,

01:00:33 everything that works is deep learning,

01:00:35 everything that doesn’t, isn’t something like that.

01:00:38 That’s just the way,

01:00:40 again, we’re back to sociological things,

01:00:42 but I guess what I’m trying to get at is

01:00:45 if we leave the sociological mess aside,

01:00:50 do we throw out the baby with the bathwater?

01:00:53 Is there some, besides the side effects of nice ideas

01:00:57 from the Ed Wittons of the world,

01:00:59 is there some core truths there that we should stick by

01:01:04 in the full beautiful mess of a space

01:01:08 that we call string theory,

01:01:09 that people call string theory?

01:01:11 You’re right, it is kind of a common problem

01:01:14 that how what you call some field changes and evolves

01:01:19 and in interesting ways as the field changes.

01:01:22 But I mean, I guess what I would argue

01:01:27 is the initial understanding of string theory

01:01:30 that was quite specific,

01:01:31 we’re talking about a specific idea,

01:01:33 10 dimensional super strings

01:01:34 compactified to six dimensions.

01:01:36 That to my mind, the really bad thing has happened

01:01:41 to the subject is that it’s hard to get people to admit,

01:01:45 at least publicly, that that was a failure,

01:01:48 that this really didn’t work.

01:01:49 And so de facto, what people do is people stop doing that

01:01:53 and they start doing more interesting things,

01:01:55 but they keep talking to the public about string theory

01:02:00 and referring back to that idea

01:02:03 and using that as kind of the starting point

01:02:05 and as kind of the place where the whole tribe starts

01:02:11 and everything else comes from.

01:02:13 So the problem with this is that having as your initial name

01:02:17 and what everything points back to,

01:02:20 something which really didn’t work out,

01:02:25 it kind of makes everybody, it makes everything,

01:02:28 you’ve created this potentially very, very interesting field

01:02:31 with interesting things happening,

01:02:32 but people in graduate school take courses

01:02:37 on string theory and everything kind of,

01:02:38 and this is what you tell the public

01:02:40 in which you’re continually pointing back.

01:02:41 So you’re continually pointing back to this idea

01:02:43 which never worked out as your guiding inspiration.

01:02:48 And it really kind of deforms your whole way

01:02:51 of your hopes of making progress.

01:02:54 And that’s, to me, I think the kind of worst thing

01:02:57 that’s happened in this field.

01:02:59 Okay, sure, so there’s a lack of transparency, sort of authenticity

01:03:02 about communicating the things that failed in the past.

01:03:07 And so you don’t have a clear picture of like firm ground

01:03:10 that you’re standing on.

01:03:12 But again, those are sociological things.

01:03:13 And there’s a bunch of questions I want to ask you.

01:03:18 So one, what’s your intuition about why the original idea failed?

01:03:26 So what can you say about why you’re pretty sure it has failed?

01:03:32 I mean, the initial idea was, as I try to explain it,

01:03:35 it was quite seductive in that you could see why Whitten

01:03:39 and others got excited by it.

01:03:40 It was, you know, at the time it looked like there were only

01:03:45 a few of these possible clobby owls that would work.

01:03:47 And it looked like, okay, we just have to understand

01:03:50 this very specific model and these very specific

01:03:53 six dimensional spaces, and we’re going to get everything.

01:03:55 And so it was a very seductive idea, but it just, you know,

01:03:59 as people learned, worked more and more about it,

01:04:03 it just didn’t, they just kind of realized that there are just

01:04:07 more and more things you can do with these six dimensions

01:04:09 and you can’t, and this is just not going to work.

01:04:12 Meaning like, it’s, I mean, what was the failure mode here?

01:04:21 Is it, you could just have an infinite number of possibilities

01:04:24 that you could do so you can come up with any theory you want,

01:04:27 you can fit quantum mechanics, you can explain gravity,

01:04:30 you can explain anything you want with it.

01:04:32 Is that the basic failure mode?

01:04:34 Yeah, so it’s a failure mode of kind of that this idea

01:04:37 ended up being kind of being essentially empty,

01:04:39 that it just doesn’t, ends up not telling you anything

01:04:43 because it’s consistent with just about anything.

01:04:47 And so, I mean, there’s a complex, if you try and talk

01:04:50 with string theorists about this now, I mean,

01:04:52 there’s an argument, there’s a long argument over this

01:04:54 about whether, oh no, no, no, maybe there still are

01:04:58 constraints coming out of this idea or not.

01:05:01 Or maybe we live in a multiverse and everything is true

01:05:06 anyway, so you can, there are various ways you can kind of,

01:05:10 that string theorists have kind of react to this kind of

01:05:12 argument that I’m making, but I try to hold onto it.

01:05:17 What about experimental validation?

01:05:18 Is that a fair standard to hold before a theory

01:05:26 of everything that’s trying to unify

01:05:27 quantum mechanics and gravity?

01:05:28 Yeah, I mean, ultimately, to be really convinced

01:05:32 that some new idea about unification really works,

01:05:36 you need some kind of, you need to look at the real world

01:05:39 and see that this is telling you something true about it.

01:05:44 I mean, either telling you that if you do some experiment

01:05:49 and go out and do it, you’ll get some unexpected result

01:05:52 and that’s the kind of gold standard, or it may be just that

01:05:57 like all those numbers that are,

01:05:58 we don’t know how to explain,

01:06:00 it will show you how to calculate them.

01:06:02 I mean, it can be various kinds of experimental validation,

01:06:05 but that’s certainly ideally what you’re looking for.

01:06:08 How tough is this, do you think, for a theory of everything,

01:06:11 not just string theory, for something that unifies

01:06:13 gravity and quantum mechanics,

01:06:14 so the very big and the very small?

01:06:17 Is this, let me ask you one way,

01:06:20 is it a physics problem, a math problem,

01:06:25 or an engineering problem?

01:06:27 My guess is it’s a combination of a physics

01:06:30 and a math problem that you really need.

01:06:33 It’s not really engineering, it’s not like there’s some kind

01:06:36 of well defined thing you can write down

01:06:39 and we just don’t have enough computer power

01:06:41 to do the calculation.

01:06:43 That’s not the kind of problem it is at all.

01:06:46 But the question is, what mathematical tools you need

01:06:49 to properly formulate the problem is unclear.

01:06:53 So one reasonable conjecture is the way,

01:06:55 the reason that we haven’t had any success yet

01:06:58 is just that we’re missing,

01:07:01 either we’re missing certain physical ideas

01:07:04 or we’re missing certain mathematical tools,

01:07:06 which there are some combination of them,

01:07:08 which we need to kind of properly formulate the problem

01:07:12 and see that it has a solution

01:07:15 that looks like the real world.

01:07:17 But those you need, I guess you don’t,

01:07:19 but there’s a sense that you need both gravity,

01:07:24 like all the laws of physics to be operating

01:07:27 on the same level.

01:07:28 So it feels like you need an object like a black hole

01:07:31 or something like that in order to make predictions about.

01:07:38 Otherwise, you’re always making predictions

01:07:40 about this joint phenomena or can you do that

01:07:45 as long as the theory is consistent

01:07:46 and doesn’t have special cases for each of the phenomena?

01:07:48 Well, your theory should, I mean,

01:07:50 if your theory is gonna include gravity,

01:07:52 our current understanding of gravity

01:07:53 is that you should have,

01:07:56 there should be black hole states in it.

01:07:57 You should be able to describe black holes in this theory.

01:08:00 And just one aspect that people have concentrated a lot on

01:08:04 is just this kind of questions about

01:08:06 if your theory includes black holes like it’s supposed to

01:08:09 and it includes quantum mechanics,

01:08:11 then there’s certain kinds of paradoxes which come up.

01:08:13 And so that’s been a huge focus of kind of

01:08:16 quantum gravity work has been just those paradoxes.

01:08:20 So stepping outside of string theory,

01:08:23 can you just say first at a high level,

01:08:26 what is the theory of everything?

01:08:28 What is the theory of everything seek to accomplish?

01:08:32 Well, I mean, this is very much a kind of reductionist

01:08:34 point of view in the sense that, so it’s not a theory.

01:08:38 This is not gonna explain to you anything.

01:08:42 It doesn’t really, this kind of theory,

01:08:44 this kind of theory of everything we’re talking about

01:08:46 doesn’t say anything interesting,

01:08:48 particularly about like macroscopic objects,

01:08:50 about what the weather is gonna be tomorrow,

01:08:52 or things are happening at this scale.

01:08:54 But just what we’ve discovered is that

01:08:57 as you look at the universe that kind of,

01:09:02 if you kind of start, you can start breaking it apart

01:09:05 into, and you end up with some fairly simple pieces,

01:09:08 quanta, if you like, and which are doing,

01:09:11 which are interacting in some fairly simple way.

01:09:14 And it’s, so what we mean by theory of everything is

01:09:19 a theory that describes all the object,

01:09:24 all the correct objects you need to describe

01:09:26 what’s happening in the world and describes how

01:09:29 they’re interacting with each other

01:09:30 at our most fundamental level.

01:09:31 How you get from that theory to describing some macroscopic,

01:09:36 incredibly complicated thing is,

01:09:38 there that becomes, again, more of an engineering problem

01:09:41 and you may need machine learning,

01:09:42 or you may, you know, a lot of very different things

01:09:44 to do it, but.

01:09:45 Well, I don’t even think it’s just engineering.

01:09:48 It’s also science.

01:09:50 One thing that I find kind of interesting

01:09:55 talking to physicists is a little bit, there’s a,

01:10:05 a little bit of hubris.

01:10:07 Some of the most brilliant people I know are physicists,

01:10:09 both philosophy and just in terms of mathematics,

01:10:12 in terms of understanding the world.

01:10:14 But there’s a kind of either hubris or what would I call it?

01:10:19 Like a confidence that if we have a theory of everything,

01:10:22 we will understand everything.

01:10:24 Like this is the deepest thing to understand.

01:10:26 And I would say, and like the rest is details, right?

01:10:29 That’s the old Rutherford thing.

01:10:33 But to me, there’s like, this is like a cake or something.

01:10:37 There’s layers to this thing

01:10:39 and each one has a theory of everything.

01:10:42 Like at every level from biology,

01:10:46 like how life originates, that itself,

01:10:50 like complex systems.

01:10:52 Like that in itself is like this gigantic thing

01:10:56 that requires a theory of everything.

01:10:58 And then there’s the, in the space of humans,

01:11:01 psychology, like intelligence, collective intelligence,

01:11:04 the way it emerges among species,

01:11:07 that feels like a complex system

01:11:09 that requires its own theory of everything.

01:11:11 On top of that is things like in the computing space,

01:11:15 artificial intelligence systems,

01:11:16 like that feels like it needs a theory of everything.

01:11:19 And it’s almost like once we solve,

01:11:24 once we come up with a theory of everything

01:11:26 that explains the basic laws of physics

01:11:28 that gave us the universe,

01:11:30 even stuff that’s super complex,

01:11:32 like how the universe might be able to originate,

01:11:37 even explaining something that you’re not a big fan of,

01:11:39 like multiverses or stuff

01:11:40 that we don’t have any evidence of yet.

01:11:42 Still, we won’t be able to have a strong explanation

01:11:47 of why food tastes delicious.

01:11:52 Yeah, I know.

01:11:53 No, anyway, yeah, I agree completely.

01:11:55 I mean, there is something kind of completely wrong

01:11:58 with this terminology of theory of everything.

01:12:00 It’s not, it’s really in some sense a very bad term,

01:12:04 very hubristic and bad terminology,

01:12:06 because it’s not, this is explaining,

01:12:11 this is a purely kind of reductionist point of view

01:12:13 that you’re trying to understand

01:12:15 a certain very specific kind of things,

01:12:17 which in principle, other things emerge from,

01:12:23 but to actually understand how anything emerges from this

01:12:27 is, it can’t be understood in terms of

01:12:31 this underlying fundamental theory is gonna be hopeless

01:12:35 in terms of kind of telling you what about this,

01:12:39 this various emergent behavior.

01:12:40 And as you go to different levels of explanation,

01:12:43 you’re gonna need to develop new,

01:12:44 different, completely different ideas,

01:12:46 completely different ways of thinking.

01:12:47 And I guess there’s a famous kind of Phil Anderson’s slogan

01:12:52 is that, you know, more is different.

01:12:54 And so it’s just, even once you understand how,

01:12:59 what a couple of things,

01:13:00 if you have a collection of stuff

01:13:01 and you understand perfectly well

01:13:03 how each thing is interacting with the others,

01:13:07 what the whole thing is gonna do

01:13:08 is just a completely different problem.

01:13:10 It’s just not, and you need completely different ways

01:13:12 of thinking about it.

01:13:13 What do you think about this?

01:13:15 I got to ask you at a few different attempts

01:13:17 that a theory of everything, especially recently.

01:13:20 So I’ve been for many years,

01:13:23 a big fan of cellular automata of complex systems.

01:13:25 And obviously because of that,

01:13:28 a fan of Stephen Wolfram’s work in that space,

01:13:31 but he’s recently been talking about a theory of everything

01:13:35 through his physics project, essentially.

01:13:38 What do you think about this kind of discreet

01:13:40 theory of everything like from simple rules

01:13:45 and simple objects on the hypergraphs

01:13:47 emerges all of our reality where time and space are emergent.

01:13:51 Basically everything we see around us is emergent.

01:13:53 Yeah, I have to say, unfortunately,

01:13:55 I’ve kind of pretty much zero sympathy for that.

01:13:58 I mean, I don’t, I spent a little time looking at it

01:14:01 and I just don’t see, it doesn’t seem to me to get anywhere.

01:14:04 And it really is just really, really doesn’t agree at all

01:14:08 with what I’m seeing,

01:14:10 this kind of unification of math and physics

01:14:13 that I’m kind of talking about around certain kinds

01:14:15 of very deep ideas about geometry and stuff.

01:14:17 This, if you want to believe that your things

01:14:22 are really coming out of cellular automata

01:14:25 at the most fundamental level,

01:14:26 you have to believe that everything that I’ve seen

01:14:30 my whole career and as beautiful, powerful ideas,

01:14:34 that that’s all just kind of a mirage,

01:14:35 which just kind of randomly is emerging

01:14:38 from these more basic, very, very simple minded things.

01:14:41 And you have to give me some serious evidence for that

01:14:44 and I’m seeing nothing.

01:14:46 So Mirage, you don’t think there could be a consistency

01:14:50 where things like quantum mechanics could emerge

01:14:54 from much, much, much smaller, discreet,

01:14:58 like computational type systems.

01:15:00 I think from the point of view of certain mathematical

01:15:02 point of view, quantum mechanics is already mathematically

01:15:06 as simple as it gets.

01:15:07 It really is a story about really the fundamental objects

01:15:13 that you work within when you write down a quantum theory

01:15:16 are in some form point of view,

01:15:18 precisely the fundamental objects

01:15:21 at these deepest levels of mathematics

01:15:22 that you’re working with, they’re exactly the same.

01:15:25 So, and cellular automata are something completely different

01:15:28 which don’t fit into these structures.

01:15:30 And so I just don’t see why, anyway,

01:15:32 I don’t see it as a promising thing to do.

01:15:37 And then just looking at it and saying,

01:15:38 does this go anywhere?

01:15:39 Does this solve any problem that I’ve ever,

01:15:42 that I didn’t, does this solve any problem of any kind?

01:15:45 I just don’t see it.

01:15:46 Yeah, to me, cellular automata and these hypergraphs,

01:15:50 I’m not sure solving a problem is even the standard

01:15:55 to apply here at this moment.

01:15:57 To me, the fascinating thing is that the question it asks

01:16:00 have no good answers.

01:16:02 So there’s not good math explaining,

01:16:04 forget the physics of it,

01:16:06 math explaining the behavior of complex systems.

01:16:09 And that to me is both exciting and paralyzing.

01:16:12 Like we’re at the very early days of understanding

01:16:17 how complicated and fascinating things emerge

01:16:19 from simple rules.

01:16:21 Yeah, and I agree.

01:16:22 I think that is a truly great problem.

01:16:25 And depending where it goes, it may be,

01:16:30 it may start to develop some kind of connections

01:16:33 to the things that I’ve kind of found more fruitful

01:16:36 and hard to know.

01:16:38 It just, I think a lot of that area,

01:16:41 I kind of strongly feel I best not say too much about it

01:16:45 because I just, I don’t know too much about it.

01:16:48 And again, we’re back to this original problem

01:16:51 that your time in life is limited.

01:16:54 You have to figure out what you’re gonna spend

01:16:55 your time thinking about.

01:16:56 And that’s something I’ve just never seen enough

01:16:59 to convince me to spend more time thinking about.

01:17:01 Well, also timing, it’s not just that our time is limited,

01:17:03 but the timing of the kind of things you think about.

01:17:07 There’s some aspect to cellular automata,

01:17:09 these kinds of objects that it feels like

01:17:12 we’re very many years away from having big breakthroughs on.

01:17:18 And so it’s like, you have to pick the problems

01:17:20 that are solvable today.

01:17:21 In fact, my intuition, again, perhaps biased,

01:17:26 is it feels like the kind of systems that,

01:17:30 complex systems that cellular automata are,

01:17:32 would not be solved by human brains.

01:17:36 It feels like something post human

01:17:40 that will solve that problem.

01:17:41 Or like significantly enhanced humans,

01:17:45 meaning like using computational tools,

01:17:47 very powerful computational tools to crack

01:17:51 these problems open.

01:17:54 That’s if our approach to science,

01:17:58 our ability to understand science, our ability

01:18:00 to understand physics will become more and more

01:18:02 computational, or there’ll be a whole field

01:18:04 that’s computational in nature,

01:18:06 which currently is not the case.

01:18:07 Currently, computation is the thing that sort of assists us

01:18:12 in understanding science the way we’ve been doing it

01:18:15 all along, but if there’s a whole new,

01:18:17 I mean, we’re from a new kind of science, right?

01:18:20 It’s a little bit dramatic, but you know,

01:18:23 if computers could do science on their own,

01:18:28 computational systems, perhaps that’s the way

01:18:34 they would do the science.

01:18:35 They would try to understand the cellular automata,

01:18:37 and that feels like we’re decades away.

01:18:39 So perhaps it’ll crack open some interesting facets

01:18:43 of this physics problem, but it’s very far away.

01:18:46 So timing is everything.

01:18:48 That’s perfectly possible, yeah.

01:18:51 Well, let me ask you then, in the space of geometry,

01:18:55 I don’t know how well you know Eric Weinstein.

01:18:57 Oh, quite well, yeah.

01:19:00 What are your thoughts about his geometric community

01:19:03 and the space of ideas that he’s playing with

01:19:07 in his proposal for theory of everything?

01:19:09 Well, I think that he has, he fundamentally has,

01:19:14 I think, the same problems that everybody has had

01:19:17 trying to do this, and there are really versions

01:19:20 of the same problem that you try to get unity

01:19:26 by putting everything into some bigger structure.

01:19:28 So he has some other ones that are not so conventional

01:19:33 that he’s trying to work with,

01:19:35 but he has the same problem that even if he can,

01:19:41 if he can get a lot farther in terms of having

01:19:43 a really well defined, well understood,

01:19:45 clear picture of these things he’s working with,

01:19:50 they’re really kind of large geometrical structures

01:19:53 of many dimensions of many kinds,

01:19:55 and I just don’t see any way,

01:19:57 he’s gonna have the same problem the string theorists have,

01:19:59 how do you get back down to the structures

01:20:02 of the standard model, and how do you, yeah.

01:20:06 So I just, anyway, it’s the same,

01:20:10 and there’s another interesting example

01:20:13 of a similar kind of thing is Garrett Leasy’s

01:20:16 theory of everything.

01:20:17 Again, there, it’s a little bit more specific

01:20:20 than Eric’s, he’s working with this E8,

01:20:22 but it, again, I think all these things found

01:20:25 are at the same point, that you don’t,

01:20:29 you know, you create this unity,

01:20:30 but then you have no, you don’t actually have a good idea

01:20:34 how you’re gonna get back to the actual,

01:20:40 to the objects we’ve seen, how are you gonna,

01:20:42 you create these big symmetries,

01:20:43 how are you gonna break them?

01:20:45 And, because we don’t see those symmetries

01:20:47 in the real world, and so ultimately,

01:20:49 there would need to be a simple process

01:20:53 for collapsing it to four dimensions.

01:20:56 You’d have to explain, well, yeah,

01:20:58 I forget in his case, but it’s not just four dimensions,

01:21:01 it’s also these structures you see in the standard model,

01:21:05 there’s, you know, there’s certain very small

01:21:07 dimensional groups of symmetries,

01:21:09 so called U1, SU2, and SU3, and the problem with,

01:21:13 and this has been a problem since the beginning,

01:21:15 almost immediately after 1973, about a year later,

01:21:18 two years later, people started talking about

01:21:20 grand unified theories, so you take the U1,

01:21:24 the SU2, and the SU3, and you put them together

01:21:27 into this bigger structure called SU5 or SO10,

01:21:31 but then you’re stuck with this problem that,

01:21:33 wait a minute, now how, why does the world not look,

01:21:36 why do I not see these SU5 symmetries in the world,

01:21:40 I only see these, and so, and I think, you know,

01:21:45 the kind of thing that Eric, and all of a sudden Garrett,

01:21:49 and lots of people who try to do it,

01:21:51 they all kind of found her in that same way,

01:21:55 that they don’t have a good answer to that.

01:21:58 Are there lessons, ideas to be learned from theories

01:22:01 like that, from Garrett Leacy’s, from Eric’s?

01:22:05 I don’t know, it depends, I have to confess,

01:22:07 I haven’t looked that closely at Eric’s,

01:22:11 I mean, he explained this to me personally a few times,

01:22:14 and I’ve looked a bit at his paper, but it’s,

01:22:17 again, we’re back to the problem

01:22:19 of a limited amount of time in life.

01:22:22 Yeah, I mean, it’s an interesting effect, right?

01:22:26 Why don’t more physicists look at it?

01:22:33 I mean, I’m in this position that somehow,

01:22:37 you know,

01:22:38 I’ve, people write me emails, for whatever reason,

01:22:45 and I’ve worked in the space of AI,

01:22:47 and so there’s a lot of people,

01:22:49 perhaps AI is even way more accessible than physics,

01:22:52 in a certain sense, and so a lot of people write to me

01:22:54 with different theories about what they have

01:22:56 for how to create general intelligence,

01:23:00 and it’s, again, a little bit of an excuse, I say to myself,

01:23:03 like, well, I only have a limited amount of time,

01:23:05 so that’s why I’m not investigating it,

01:23:07 but I wonder if there’s ideas out there

01:23:11 that are still powerful, that are still fascinating,

01:23:14 and that I’m missing because I’m dismissing them

01:23:21 because they’re outside of the sort of the usual process

01:23:24 of academic research.

01:23:26 Yeah, well, I mean, the same thing,

01:23:28 and pretty much every day in my email,

01:23:29 there’s somebody who’s got a theory or everything

01:23:32 about why all of what physicists are doing,

01:23:35 and perhaps the most disturbing thing I should say

01:23:38 about being a critic of string theory

01:23:41 is that when you realize who your fans are,

01:23:45 every day I hear from somebody who says,

01:23:47 oh, well, since you don’t like string theory,

01:23:48 you must, of course, agree with me

01:23:49 that this is the right way to think about everything.

01:23:52 Oh, no, oh, no, and most of these are,

01:23:57 you quickly can see this person doesn’t know very much

01:24:00 and doesn’t know what they’re doing,

01:24:02 but there’s a whole continuum to,

01:24:05 people who are quite serious physicists and mathematicians

01:24:08 who are making a fairly serious attempt

01:24:10 to try to do something, like Eric and Eric,

01:24:14 and then your problem is you do try to spend more time

01:24:21 looking at it and trying to figure out

01:24:22 what they’re really doing,

01:24:23 but then at some point you just realize,

01:24:26 wait a minute, for me to really, really understand

01:24:28 exactly what’s going on here would just take time

01:24:32 I just don’t have.

01:24:33 Yeah, it takes a long time, which is the nice thing about AI

01:24:36 is unlike the kind of physics we’re talking about,

01:24:41 if your idea is good, that should quite naturally lead

01:24:46 to you being able to build a system that’s intelligent.

01:24:49 So you don’t need to get approval from somebody

01:24:52 that’s saying you have a good idea here.

01:24:54 You can just utilize that idea in an engineer system,

01:24:56 like naturally leads to engineering.

01:24:58 With physics here, if you have a perfect theory

01:25:01 that explains everything, that still doesn’t obviously lead

01:25:06 one, to scientific experiments that can validate

01:25:12 that theory, and two, to like trinkets you can build

01:25:15 and sell at a store for $5.

01:25:18 You can’t make money off of it.

01:25:21 So that makes it much more challenging.

01:25:25 Well, let me also ask you about something that you found,

01:25:28 especially recently appealing,

01:25:30 which is Roger Penrose’s Twister theory.

01:25:34 What is it?

01:25:35 What kind of questions might it allow us to answer?

01:25:37 What will the answers look like?

01:25:39 It’s only in the last couple of years

01:25:41 that I really, really kind of come to really,

01:25:43 I think, to appreciate it and to see how to really,

01:25:46 I believe to see how to really do something with it.

01:25:48 And I’ve gotten very excited about that

01:25:49 the last year or two.

01:25:51 I mean, one way of saying one idea of Twister theory

01:25:54 is that it’s a different way of thinking about

01:25:59 what space and time are and about what points

01:26:01 in space and time are, which is very interesting

01:26:05 that it only really works in four dimensions.

01:26:07 So four dimensions behaves very, very specially

01:26:09 unlike other dimensions.

01:26:11 And in four dimensions, there is a way of thinking

01:26:14 about space and time geometry,

01:26:17 as well as just thinking about points in space and time.

01:26:21 You can also think about different objects,

01:26:25 these so called twisters.

01:26:26 And then when you do that,

01:26:27 you end up with a kind of a really interesting insight

01:26:30 that you can formulate a theory,

01:26:35 and you can formulate a very,

01:26:37 take a standard theory that we formulate

01:26:39 in terms of points of space and time,

01:26:41 and you can reformulate in this Twister language.

01:26:44 And in this Twister language,

01:26:45 it’s the fundamental objects actually are more kind of the,

01:26:51 are actually spheres in some sense, kind of the light cone.

01:26:54 So maybe one way to say it,

01:26:56 which actually I think is really, is quite amazing.

01:27:02 If you ask yourself, what do we know about the world?

01:27:05 We have this idea that the world out there

01:27:07 is all these different points and these points of time.

01:27:11 Well, that’s kind of a derived quantity.

01:27:13 What we really know about the world is when we open our eyes,

01:27:16 what do you see?

01:27:17 You see a sphere.

01:27:19 And that what you’re looking at is you’re looking at,

01:27:23 a sphere is worth of light rays coming into your eyes.

01:27:26 And what Penrose says is that,

01:27:29 well, what a point in space time is, is that sphere,

01:27:33 that sphere of all the light rays coming in.

01:27:36 And he says, and you should formulate your,

01:27:39 instead of thinking about points,

01:27:40 you should think about the space of those spheres,

01:27:43 if you like, and formulate the degrees of freedom

01:27:46 as physics as living on those spheres, living on,

01:27:50 so you’re kind of living on,

01:27:51 your degrees of freedom are living on light rays,

01:27:53 not on points.

01:27:55 And it’s a very different way of thinking about physics.

01:28:00 And he and others working with him developed

01:28:03 a beautiful mathematical formulas

01:28:08 and a way to go back from forth between some aspects

01:28:11 of our standard way we write these things down

01:28:14 and work in the so called twister space.

01:28:17 And certain things worked out very well,

01:28:20 but they ended up, I think kind of stuck by the 80s or 90s

01:28:24 that they weren’t a little bit like string theory

01:28:27 that they, by using these ideas about twisters,

01:28:31 they could develop them in different directions

01:28:33 and find all sorts of other interesting things,

01:28:34 but they were getting,

01:28:36 they weren’t finding any way of doing that

01:28:38 that brought them back to kind of new insights into physics.

01:28:43 And my own, I mean, what’s kind of gotten me excited really

01:28:46 is what I think I have an idea about

01:28:49 that I think does actually work,

01:28:52 that goes more in that direction.

01:28:54 And I can go on about that endlessly

01:28:56 or talk a little bit about it,

01:28:57 but that’s the, I think that’s the one kind of easy

01:29:02 to explain insight about twister theory.

01:29:05 There are some more technical ones.

01:29:06 I should mean, I think it’s also very convincing

01:29:09 what it tells you about spinners, for instance,

01:29:11 but that’s a more technical.

01:29:12 Well, first let’s like linger on the spheres

01:29:14 and the light cones.

01:29:17 You’re saying twisted theory allows you to make

01:29:20 that the fundamental object with which you’re operating.

01:29:23 Yeah.

01:29:24 How that, I mean, first of all,

01:29:26 like philosophically that’s weird and beautiful,

01:29:32 maybe because it maps,

01:29:34 it feels like it moves us so much closer

01:29:37 to the way human brains perceive reality.

01:29:40 Yeah.

01:29:41 So it’s almost like our perception is like the content

01:29:46 of our perception is the fundamental object of reality.

01:29:54 That’s very appealing.

01:29:55 Yeah.

01:29:57 Is it mathematically powerful?

01:30:01 Is there something you can say,

01:30:04 can you say a little bit more about what the heck

01:30:06 that even means for,

01:30:08 because it’s much easier to think about mathematically

01:30:11 like a point in space time.

01:30:13 What does it mean to be operating on the light cone?

01:30:16 It uses a kind of mathematics that’s relative,

01:30:19 that kind of goes back to the 19th century

01:30:22 among mathematicians.

01:30:23 It’s not, anyway, it’s a bit of a long story,

01:30:26 but one problem is that you have to start,

01:30:28 it’s crucial that you think in terms of complex numbers

01:30:31 and not just real numbers.

01:30:32 And this, for most people, that makes it harder to,

01:30:36 for mathematicians, that’s fine.

01:30:37 We love doing that.

01:30:38 But for most people, that makes it harder to think about.

01:30:41 I think perhaps the most,

01:30:43 the way that there is something you can say

01:30:45 very specifically about it in terms of spinners,

01:30:49 which I don’t know if you want to,

01:30:50 I think at some point you want to talk, so maybe you can.

01:30:52 What are spinners?

01:30:53 Let’s start with spinners,

01:30:54 because I think that if we can introduce that,

01:30:55 then I can say it.

01:30:57 By the way, twister is spelled with an O

01:31:01 and spinner is spelled with an O as well.

01:31:03 Yes, okay.

01:31:05 In case you want to Google it and look it up,

01:31:07 there’s very nice Wikipedia pages as a starting point.

01:31:10 I don’t know what is a good starting point

01:31:12 for twister theory.

01:31:13 Well, one thing you say about Penrose,

01:31:16 I mean, Penrose is actually a very good writer

01:31:18 and also a very good draftsman.

01:31:19 He’s a draftsman, to the extent this is visualizable,

01:31:22 he actually has done some very nice drawings.

01:31:23 So, I mean, almost any kind of expository thing

01:31:26 you can find him writing is a very good place to start.

01:31:29 He’s a remarkable person.

01:31:32 But the, so spinners are something

01:31:36 that independently came out of mathematics

01:31:38 and out of physics.

01:31:40 And to say where they came out of physics,

01:31:42 I mean, what people realized when they started looking

01:31:44 at elementary particles like electrons or whatever,

01:31:47 that there seem to be some kind of doubling

01:31:51 of the degrees of freedom going on.

01:31:53 If you counted what was there in some sense

01:31:57 in the way you would expect it

01:31:58 and when you started doing quantum mechanics

01:32:00 and started looking at elementary particles,

01:32:01 there were seen to be two degrees of freedom,

01:32:03 they’re not one.

01:32:04 And one way of seeing it was that if you put your electron

01:32:09 in a strong magnetic field and asked what was the energy

01:32:13 of it, instead of it having one energy,

01:32:15 it would have two energies, there’d be two energy levels.

01:32:17 And as you increase magnetic field,

01:32:20 the splitting would increase.

01:32:22 So physicists kind of realized that, wait a minute.

01:32:24 So we thought when we were doing,

01:32:27 first started doing quantum mechanics,

01:32:28 that the way to describe particles was in terms

01:32:31 of wave functions and these wave functions

01:32:33 were complex to complex values.

01:32:35 Well, if we actually look at particles,

01:32:38 that that’s not right.

01:32:38 They’re pairs of complex numbers.

01:32:42 They’re pairs of complex numbers.

01:32:44 So one of the kind of fundamental,

01:32:46 from the physics point of view,

01:32:47 the fundamental question is why are all our kind

01:32:50 of fundamental particles described

01:32:53 by pairs of complex numbers?

01:32:55 Just weird.

01:32:56 And then you can ask, well, what happens

01:33:00 if you like take an electron and rotate it?

01:33:03 So how do things move in this pair of complex numbers?

01:33:08 Well, now, if you go back to mathematics,

01:33:10 what had been understood in mathematics,

01:33:13 some years earlier, not that many years earlier,

01:33:16 was that if you ask very, very generally,

01:33:20 think about geometry of three dimensions and ask,

01:33:24 and if you think about things that are happening

01:33:25 in three dimensions in the standard way,

01:33:28 everything, the standard way of doing geometry,

01:33:30 everything is about vectors, right?

01:33:32 So if you’ve taken any mathematics classes,

01:33:35 you probably see vectors at some point.

01:33:36 They’re just triplets of numbers tell you

01:33:39 what a direction is or how far you’re going

01:33:41 in three dimensional space.

01:33:42 And most of everything we teach in most standard courses

01:33:46 in mathematics is about vectors

01:33:49 and things you build out of vectors.

01:33:51 So you express everything about geometry

01:33:53 in terms of vectors or how they’re changing

01:33:55 or how you put two of them together

01:33:57 and get planes and whatever.

01:34:00 But what had been realized that,

01:34:03 Rianna, is that if you ask very, very generally,

01:34:05 what are the, if you have, what are the things

01:34:09 that you can kind of consistently think about rotating?

01:34:13 And so you ask a technical question,

01:34:16 what are the representations of the rotation group?

01:34:18 Well, you find that one answer is they’re vectors

01:34:22 and everything you build out of vectors,

01:34:24 but then people found, but wait a minute,

01:34:26 there’s also these other things,

01:34:29 which you can build out of vectors,

01:34:31 but which you can consistently rotate.

01:34:34 And they’re described by pairs of complex numbers,

01:34:37 by two complex numbers.

01:34:38 And they’re the spinners also.

01:34:40 And to make a lot, and to make,

01:34:43 and you can think of spinners in some sense

01:34:45 as more fundamental than vectors

01:34:46 because you can build vectors out of spinners.

01:34:48 You can take two spinners and make a vector,

01:34:51 but you can’t, if you only have vectors,

01:34:54 you can’t get spinners.

01:34:56 So they’re in some sense, there’s some kind of level

01:34:59 of lower level of geometry beyond what we thought it was,

01:35:02 which was kind of spinner geometry.

01:35:04 And this is something which even to this day,

01:35:07 when we teach graduate courses in geometry,

01:35:09 we mostly don’t talk about this

01:35:11 because it’s a bit hard to do correctly.

01:35:15 If you start with your whole setup is in terms of vectors,

01:35:20 describing things in terms of spinners

01:35:22 is a whole different ball game.

01:35:24 But anyway, it was just this amazing fact

01:35:28 that this kind of more fundamental piece of geometry,

01:35:33 spinners, and what we were actually seeing,

01:35:35 if you look at electron, are one and the same.

01:35:37 So it’s, I think it’s kind of a mind blowing thing,

01:35:41 but it’s very counterintuitive.

01:35:44 What are some weird properties of spinners

01:35:47 that are counterintuitive?

01:35:50 That there are some things that they do,

01:35:51 for instance, if you rotate a spinner around 360 degrees,

01:35:56 it doesn’t come back towards,

01:35:58 it becomes minus what it was.

01:36:00 Or, so it’s, anyway, so the way rotations work,

01:36:04 there’s a kind of a funny sign

01:36:05 you have to keep track of in some sense.

01:36:08 So they’re kind of too valued in another weird way.

01:36:11 But the fundamental problem is that it’s just not,

01:36:14 if you’re used to visualizing vectors,

01:36:17 you just, there’s nothing you can do

01:36:19 visualizing in terms of vectors

01:36:20 that will ever give you a spinner.

01:36:21 It just is not gonna ever work.

01:36:23 As you were saying that I was visualizing a vector

01:36:26 walking along a Mobius strip,

01:36:29 and it ends up being upside down.

01:36:32 But you’re saying that doesn’t really capture.

01:36:34 So, I mean, what really captures it?

01:36:36 The problem is that it’s really,

01:36:39 the simplest way to describe it

01:36:41 is in terms of two complex numbers.

01:36:43 And your problem with two complex numbers

01:36:45 is that’s four real numbers.

01:36:46 So your spinner kind of lies in a four dimensional space.

01:36:50 So you, that makes it hard to visualize.

01:36:53 And it’s crucial that it’s not just any four dimensions.

01:36:57 It’s just, it’s actually complex numbers.

01:36:59 You’re really gonna use the fact that

01:37:01 these are two complex numbers.

01:37:03 So it’s very hard to visualize.

01:37:06 But to get back to what I think is mind blowing

01:37:09 about twisters is that the,

01:37:11 another way of saying this idea about talking about spheres,

01:37:15 another way of saying the fundamental idea of twister theory

01:37:18 is in some sense, the fundamental idea of twister theory

01:37:21 is that a point is a two complex dimensional space.

01:37:28 So that every, and that it lives inside,

01:37:32 the space that it lies inside is twister space.

01:37:34 So in the simplest case, it’s four,

01:37:36 twister space is four dimensional

01:37:38 and a point in space time

01:37:40 is a two complex dimensional subspace

01:37:44 of all the four complex dimensions.

01:37:47 And as you move around in space time,

01:37:49 you’re just moving, your planes are just moving around.

01:37:51 Okay.

01:37:52 And that, but then the.

01:37:54 So it’s a plane in a four dimensional space.

01:37:56 It’s a plane.

01:37:58 Complex.

01:37:59 Complex plane.

01:38:00 So it’s two complex dimensions in four complex.

01:38:03 Got it.

01:38:03 But then to me, the mind blowing thing about this

01:38:05 is this then kind of tautologically answers the question

01:38:09 is what is a spinner?

01:38:10 Well, a spinner is a point.

01:38:14 I mean, the space of spinners at a point is the point.

01:38:17 In twister theory, the points are the complex two planes.

01:38:21 And you want me to, and you’re asking what a spinner is.

01:38:24 Well, a spinner, the space of spinners is that two plane.

01:38:28 So it’s, you know, just your whole definition

01:38:31 of what a point in space time was

01:38:33 just told you what a spinner was.

01:38:35 It’s, they’re just, it’s the same thing.

01:38:37 Yeah, but we’re trying to project that

01:38:38 into a three dimensional space

01:38:39 and trying to intuit, but you can’t.

01:38:42 Yeah, so the intuition becomes very difficult,

01:38:44 but from, if you don’t, not using twister theory,

01:38:49 you have to kind of go through a certain

01:38:51 fairly complicated rigmarole to even describe spinners

01:38:54 to describe electrons.

01:38:55 Whereas using twister theory,

01:38:57 it’s just completely tautological.

01:38:58 They’re just what you want to describe.

01:39:03 The electron is fundamentally the way

01:39:05 that you’re describing the point in space time already.

01:39:08 It’s just there, so.

01:39:10 Do you have a hope?

01:39:11 You mentioned that you found it appealing recently.

01:39:14 Is it just because of certain aspects

01:39:17 of its mathematical beauty,

01:39:18 or do you actually have a hope

01:39:19 that this might lead to a theory of everything?

01:39:22 Yeah, I mean, I certainly do have such a hope

01:39:25 because what I’ve found, I think the thing which I’ve done,

01:39:27 which I don’t think, as far as I can tell,

01:39:29 no one had really looked at from this point of view before

01:39:33 is, has to do with this question of how do you treat time

01:39:39 in your quantum theory?

01:39:40 And so there’s another long story

01:39:44 about how we do quantum theories

01:39:46 and about how we treat time in quantum theories,

01:39:48 which is a long story.

01:39:51 But the short version of it is that what people have found

01:39:55 when you try and write down a quantum theory,

01:39:58 that it’s often a good idea to take your time coordinate,

01:40:05 whatever you’re using to your time coordinate,

01:40:07 and multiply it by the square root of minus one

01:40:09 and to make it purely imaginary.

01:40:11 And so all these formulas,

01:40:13 which you have in your standard theory,

01:40:18 if you do that to those,

01:40:19 I mean, those formulas have some very strange behavior

01:40:23 and they’re kind of singular.

01:40:25 If you ask even some simple questions,

01:40:27 you have to take very delicate singular limits

01:40:31 in order to get the correct answer,

01:40:33 and you have to take them from the right direction,

01:40:35 otherwise it doesn’t work.

01:40:36 Whereas if you just take time,

01:40:39 and if you just put a factor of square root of minus one,

01:40:42 wherever you see the time coordinate,

01:40:44 you end up with much simpler formulas,

01:40:47 which are much better behaved mathematically.

01:40:49 And what I hadn’t really appreciated until fairly recently

01:40:52 is also how dramatically that changes

01:40:55 the whole structure of the theory.

01:40:57 You end up with a consistent way of talking

01:40:59 about these quantum theories,

01:41:01 but it has some very different flavor

01:41:04 and very different aspects that I hadn’t really appreciated.

01:41:07 And in particular, the way symmetries act on it

01:41:10 is not at all what I originally had expected.

01:41:15 And so that’s the new thing that I have,

01:41:17 or I think gives you something,

01:41:19 is to do this move,

01:41:21 which people often think of as just kind of a mathematical

01:41:26 trick that you’re doing

01:41:27 to make some formulas work out nicely,

01:41:29 but to take that mathematical trick as really fundamental.

01:41:33 And it turns out in Twister theory

01:41:35 allows you to simultaneously talk about your usual time

01:41:39 and the time times the square root of minus one,

01:41:41 they both fit very nicely into Twister theory.

01:41:45 And you end up with some structures

01:41:48 which look a lot like the standard models.

01:41:51 Well, let me ask you about some Nobel prizes.

01:41:54 Okay.

01:41:55 Do you think there will be,

01:41:56 there was a bet between Michio Kaku

01:42:01 and somebody else about.

01:42:04 John Horgan.

01:42:05 John Horgan about,

01:42:07 by the way, maybe discover a cool website,

01:42:09 longbets.com or.org.

01:42:11 Better, yeah, yeah.

01:42:11 Yeah, it’s cool.

01:42:12 It’s cool that you can make a bet with people

01:42:16 and then check in 20 years later.

01:42:18 I really love it.

01:42:19 There’s a lot of interesting bets on there.

01:42:21 I would love to participate,

01:42:22 but it’s interesting to see,

01:42:24 time flies and you make a bet about

01:42:27 what’s going to happen in 20 years.

01:42:28 You don’t realize 20 years just goes like this.

01:42:31 And then you get to face out

01:42:33 and you get to wonder what was that person?

01:42:39 What was I thinking?

01:42:41 That person 20 years ago

01:42:42 was almost like a different person.

01:42:43 What was I thinking back then to think that?

01:42:46 It’s interesting.

01:42:47 So let me ask you this on record,

01:42:49 20 years from now or some number of years from now,

01:42:54 do you think there will be a Nobel Prize given

01:42:55 for something directly connected

01:42:58 to a first broadly theory of everything?

01:43:01 And second, of course, one of the possibilities,

01:43:05 one of them, string theory?

01:43:10 String theory, definitely not.

01:43:13 Things have gone, yeah.

01:43:16 So if you were giving financial advice,

01:43:18 you would say not to bet on that?

01:43:19 No, do not.

01:43:20 And even, I actually suspect

01:43:22 if you ask string theorists that question,

01:43:24 you’re gonna get a few of them saying,

01:43:27 I mean, if you’d asked them that question 20 years ago,

01:43:29 again, when Kaku was making this bet or whatever,

01:43:32 I think some of them would have taken you up on it.

01:43:35 And certainly back in 1984,

01:43:37 a bunch of them would have said, oh, sure, yeah.

01:43:39 But now I get the impression that

01:43:43 even they realize that things are not looking good

01:43:45 for that particular idea.

01:43:46 Again, it depends what you mean by string theory,

01:43:48 whether maybe the term will evolve to mean something else,

01:43:51 which will work out.

01:43:53 But I don’t think that’s not gonna like it to work out,

01:43:57 whether something else.

01:43:59 I mean, I still think it’s relatively unlikely

01:44:01 that you’ll have any really successful theory of everything.

01:44:04 And the main problem is just the,

01:44:08 it’s become so difficult to do experiments at higher energy

01:44:11 that we’ve really lost this ability

01:44:13 to kind of get unexpected input from experiment.

01:44:19 And you can, while it’s maybe hard to figure out

01:44:22 what people’s thinking is gonna be 20 years from now,

01:44:24 looking at high energy particle,

01:44:28 high energy colliders and their technology,

01:44:30 it’s actually pretty easy to make a pretty accurate guess

01:44:33 what you’re gonna be doing 20 years from now.

01:44:37 And I think actually, I would actually claim that

01:44:42 it’s pretty clear where you’re gonna be 20 years from now.

01:44:44 And what it’s gonna be is you’re gonna have the LHC,

01:44:50 you’re gonna have a lot more data,

01:44:51 an order of magnitude or more data from the LHC,

01:44:56 but at the same energy.

01:44:57 You’re not gonna see a higher energy accelerator

01:45:01 operating successfully in the next 20 years.

01:45:05 And like maybe machine learning

01:45:08 or great sort of data science methodologies

01:45:10 that process that data will not reveal

01:45:12 any major shifts in our understanding

01:45:17 of the underlying physics, you think?

01:45:19 I don’t think so.

01:45:20 I mean, I think that field, my understanding

01:45:23 is they’re starting to make a great use of those techniques,

01:45:26 but it seems to look like it will help them

01:45:29 solve certain technical problems

01:45:30 and be able to do things somewhat better,

01:45:32 but not completely change the way they’re looking at things.

01:45:36 What do you think about the potential quantum computers

01:45:39 simulating quantum mechanical systems

01:45:41 and through that sneak up to sort of through simulation,

01:45:46 sneak up to a deep understanding of the fundamental physics?

01:45:51 The problem there is that that’s promising more

01:45:54 for this, for Phil Anderson’s problem,

01:45:59 that if you wanna, there’s lots and lots of,

01:46:06 you start putting together lots and lots of things

01:46:08 and we think we know they’re pair by pair interactions,

01:46:11 but what this thing is gonna do,

01:46:13 we don’t have any good calculational techniques.

01:46:16 Quantum computers may very well give you those.

01:46:19 And so they may, what we think of

01:46:21 is kind of a strong coupling behavior.

01:46:23 We have no good way to calculate.

01:46:26 Even though we can write down the theory,

01:46:28 we don’t know how to calculate anything with any accuracy

01:46:31 and the quantum computer may solve that problem.

01:46:34 But the problem is that I don’t think

01:46:36 that they’re gonna solve the problem

01:46:38 that they help you with the problem

01:46:39 of not having the, of knowing

01:46:41 what the right underlying theory is.

01:46:44 As somebody who likes experimental validation,

01:46:48 let me ask you the perhaps ridiculous sounding,

01:46:51 but I don’t think it’s actually a ridiculous question

01:46:53 of do you think we live in a simulation?

01:46:56 Do you find that thought experiment

01:46:58 at all useful or interesting?

01:47:00 Not really, I don’t, it just doesn’t.

01:47:03 Yeah, anyway, to me, it doesn’t actually lead

01:47:08 to any kind of interesting, lead anywhere interesting.

01:47:11 Yeah, to me, so maybe I’ll throw a wrench into your thing.

01:47:16 To me, it’s super interesting

01:47:17 from an engineering perspective.

01:47:19 So if you look at virtual reality systems,

01:47:23 the actual question is how much computation

01:47:28 and how difficult is it to construct a world

01:47:32 that like there are several levels here.

01:47:36 One is you won’t know the difference,

01:47:39 our human perception systems

01:47:41 and maybe even the tools of physics

01:47:42 won’t know the difference

01:47:43 between the simulated world and the real world.

01:47:47 That’s sort of more of a physics question.

01:47:51 The most interesting question to me

01:47:53 has more to do with why food tastes delicious,

01:47:55 which is create how difficult

01:47:58 and how much computation is required

01:48:00 to construct a simulation

01:48:02 where you kind of know it’s a simulation at first,

01:48:06 but you want to stay there anyway.

01:48:07 And over time, you don’t even remember.

01:48:13 Yeah, well, anyway, I agree,

01:48:15 these are kind of fascinating questions

01:48:18 and they may be very, very relevant

01:48:20 to our future as a species,

01:48:21 but yeah, they’re just very far from anything I think.

01:48:26 Well, so from a physics perspective,

01:48:27 it’s not useful to you to think,

01:48:29 taking a computational perspective to our universe,

01:48:32 thinking of it as an information processing system

01:48:35 and then they give it as doing computation

01:48:37 and then you think about the resources required

01:48:39 to do that kind of computation and all that kind of stuff.

01:48:42 You could just look at the basic physics

01:48:43 and who cares what the computer it’s running on is.

01:48:46 Yeah, it just, I mean, the kinds of,

01:48:48 I mean, I’m willing to agree

01:48:49 that you can get into interesting kinds of questions

01:48:51 going down that road,

01:48:52 but they’re just so different from anything

01:48:55 from what I’ve found interesting and I just,

01:48:57 again, I just have to kind of go back to life is too short

01:49:01 and I’m very glad other people are thinking about this,

01:49:03 but I just don’t see anything I can do with it.

01:49:08 What about space itself?

01:49:11 So I have to ask you about aliens.

01:49:14 Again, something, since you emphasize evidence,

01:49:18 do you think there is, how many,

01:49:20 do you think there are and how many

01:49:23 intelligent alien civilizations are out there?

01:49:25 Yeah, I have no idea, but I have certainly,

01:49:28 as far as I know, unless the government’s covering it up

01:49:30 or something, we haven’t heard from,

01:49:32 we don’t have any evidence for such things yet,

01:49:35 but there seems to be no,

01:49:38 there’s no particular obstruction why there shouldn’t be, so.

01:49:43 I mean, do you, you work on some fundamental questions

01:49:47 about the physics of reality.

01:49:49 When you look up to the stars,

01:49:51 do you think about whether somebody’s looking back at us?

01:49:55 Yes, yeah, well, actually,

01:49:56 I originally got interested in physics.

01:49:58 I actually started out as a kid interested in astronomy,

01:50:00 exactly that, and a telescope and whatever that,

01:50:02 and certainly read a lot of science fiction

01:50:05 and thought about that.

01:50:08 I find over the years, I find myself kind of less,

01:50:12 anyway, less and less interested in that one,

01:50:15 just because I don’t really know what to do with them.

01:50:19 I also kind of, at some point,

01:50:20 kind of stopped reading science fiction that much,

01:50:23 kind of feeling that there was just too,

01:50:25 that the actual science I was kind of learning about

01:50:27 was perfectly kind of weird and fascinating,

01:50:29 and unusual enough, and better than any of the stuff

01:50:33 that Isaac Asimov, so why should I?

01:50:36 Yeah, and you can mess with the science

01:50:39 much more than the distant science fiction,

01:50:43 the one that exists in our imagination

01:50:45 or the one that exists out there among the stars.

01:50:49 Well, you mentioned science fiction.

01:50:51 You’ve written quite a few book reviews.

01:50:54 I gotta ask you about some books, perhaps,

01:50:56 if you don’t mind.

01:50:57 Is there one or two books that you would recommend to others

01:51:03 and maybe if you can, what ideas you drew from them?

01:51:09 Either negative recommendations or positive recommendations.

01:51:12 Do not read this book for sure.

01:51:15 Well, I must say, I mean, unfortunately,

01:51:18 yeah, you can go to my website

01:51:19 and you can click on book reviews

01:51:21 and you can see I’ve written, read a lot of,

01:51:24 a lot of, I mean, as you can tell from my views

01:51:27 about string theory, I’m not a fan

01:51:28 of a lot of the kind of popular books

01:51:31 about, oh, isn’t string theory great?

01:51:32 And yes, I’m not a fan of a lot of things of that kind.

01:51:37 Can I ask you a quick question on this, a small tangent?

01:51:41 Are you a fan, can you explore the pros and cons

01:51:46 of, if I get string theory, sort of science communication,

01:51:51 sort of Cosmos style communication of concepts

01:51:56 to people that are outside of physics,

01:51:59 outside of mathematics, outside of even the sciences

01:52:02 and helping people to sort of dream

01:52:04 and fill them with awe about the full range

01:52:07 of mysteries in our universe?

01:52:10 That’s a complicated issue.

01:52:11 You know, I think, you know, I certainly go back

01:52:13 and go back to like what inspired me

01:52:15 and maybe to connect it a little bit

01:52:18 to this question about books.

01:52:19 I mean, certainly when the books,

01:52:21 some books that I remember reading when I was a kid

01:52:23 were about the early history of quantum mechanics,

01:52:26 like Heisenberg’s books that he wrote about, you know,

01:52:29 kind of looking back at telling the history

01:52:31 of what happened when he developed quantum mechanics.

01:52:32 It’s just kind of a totally fascinating, romantic,

01:52:36 great story, and those were very inspirational to me.

01:52:40 And I would think maybe other people

01:52:41 might also find them that, but the…

01:52:45 And that’s almost like the human story

01:52:47 of the development of the ideas.

01:52:49 Yeah, the human story, but yeah, just also how, you know,

01:52:51 there are these very, very weird ideas

01:52:53 that didn’t seem to make sense,

01:52:54 and how they were struggling with them

01:52:56 and how, you know, they actually…

01:52:58 Anyway, it’s, I think it’s the period of physics

01:53:01 kind of beginning, you know, 1905 with Planck and Einstein

01:53:06 and ending up with the war

01:53:08 when these things get used to, you know,

01:53:11 make massively destructive weapons.

01:53:14 It’s just the truly amazing…

01:53:15 And so many, so many new ideas.

01:53:17 Let me, on another, a tangent on top of a tangent

01:53:19 on top of a tangent, ask,

01:53:21 if we didn’t have Einstein, so how does science progress?

01:53:26 Is it the lone geniuses?

01:53:28 Or is it some kind of weird network of ideas

01:53:32 swimming in the air and just kind of the geniuses

01:53:36 pop up to catch them and others would anyway?

01:53:39 Without Einstein, would we have special relativity,

01:53:42 general relativity?

01:53:44 I mean, it’s an interesting case to case basis.

01:53:47 I mean, special relativity, I think we would have had,

01:53:51 I mean, there are other people.

01:53:53 Anyway, you could even argue that it was already there

01:53:56 in some form in some ways,

01:53:57 but I think special relativity you would have had

01:54:00 without Einstein fairly quickly.

01:54:03 General relativity, that was a much, much harder thing to do

01:54:07 and required a much more effort, much more sophisticated.

01:54:11 That I think you would have had sooner or later,

01:54:13 but it would have taken quite a bit longer.

01:54:16 That took a bunch of years to validate scientifically,

01:54:20 the general relativity.

01:54:21 But even for Einstein, from the point where he had

01:54:24 kind of a general idea of what he was trying to do

01:54:26 to the point where he actually had a well defined theory

01:54:29 that you could actually compare to the real world,

01:54:31 that was, I forget the number of the order of magnitude,

01:54:35 10 years of very serious work.

01:54:36 And if he hadn’t been around to do that,

01:54:39 it would have taken a while before anyone else

01:54:41 got around to it.

01:54:43 On the other hand, there are things like,

01:54:45 with quantum mechanics, you have Heisenberg and Schrodinger

01:54:51 came up with two, which ultimately equivalent,

01:54:55 but two different approaches to it

01:54:58 within months of each other.

01:54:59 And so if Heisenberg hadn’t been there,

01:55:02 you already would have had Schrodinger or whatever.

01:55:04 And if neither of them had been there,

01:55:05 it would have been somebody else a few months later.

01:55:07 So there are times when the, just the,

01:55:12 a lot often is the combination of the right ideas

01:55:16 are in place and the right experimental data is in place

01:55:19 to point in the right direction.

01:55:20 And it’s just waiting for somebody who’s gonna find it.

01:55:25 Maybe to go back to your aliens,

01:55:28 I guess the one thing that I often wonder about aliens is,

01:55:30 would they have the same fundamental physics ideas

01:55:33 as we have in mathematics?

01:55:35 Would their math, you know, would they, you know,

01:55:39 how much is this really intrinsic to our minds?

01:55:42 If you start out with a different kind of mind

01:55:43 when you end up with a different ideas

01:55:46 of what fundamental physics is

01:55:47 or what the structure of mathematics is.

01:55:49 So this is why, like if I was, you know,

01:55:54 I like video games, the way I would do it

01:55:56 as a curious being, so first experiment I’d like to do

01:55:59 is run Earth over many thousands of times

01:56:02 and see if our particular, no, you know what?

01:56:06 I wouldn’t do the full evolution.

01:56:08 I would start at Homo sapiens first

01:56:10 and then see the evolution of Homo sapiens

01:56:12 millions of times and see how the ideas

01:56:15 of science would evolve.

01:56:16 Like, would you get, like how would physics evolve?

01:56:19 How would math evolves?

01:56:21 I would particularly just be curious

01:56:22 about the notation they come up with.

01:56:25 Every once in a while I would like throw miracles

01:56:28 at them to like, to mess with them and stuff.

01:56:31 And then I would also like to run Earth

01:56:33 from the very beginning to see if evolution

01:56:35 will produce different kinds of brains

01:56:37 that would then produce different kinds

01:56:38 of mathematics and physics.

01:56:40 And then finally, I would probably millions of times

01:56:43 run the universe over to see what kind of,

01:56:48 what kind of environments and what kind of life

01:56:52 would be created to then lead to intelligent life,

01:56:55 to then lead to theories of mathematics and physics

01:56:59 and to see the full range.

01:57:00 And like, sort of like Darwin kind of mark, okay.

01:57:04 It took them, what is it, several hundred million years

01:57:10 to come up with calculus.

01:57:13 I would just like keep noting how long it took

01:57:16 and get an average and see which ideas are difficult,

01:57:19 which are not and then conclusively sort of figure out

01:57:23 if it’s more collective intelligence

01:57:27 or singular intelligence that’s responsible for shifts

01:57:30 and for big phase shifts and breakthroughs in science.

01:57:33 If I was playing a video game and ran,

01:57:36 I got a chance to run this whole thing.

01:57:38 Yeah, but we’re talking about books

01:57:41 before I distracted us horribly.

01:57:42 About books, okay, so books, yeah, go back, books.

01:57:44 Yeah, so and then, yeah, so that’s one thing I’d recommend

01:57:47 is the books about the, from the original people,

01:57:50 especially Heisenberg about the, how that happened.

01:57:53 And there’s also a very, very good kind of history

01:57:55 of the kind of what happened during this 20th century

01:58:00 in physics and up to the time of the Standard Model in 1973.

01:58:05 It’s called The Second Creation by Bob Kreis and Mann.

01:58:10 That’s one of the best ones.

01:58:11 I know that’s, but the one thing that I can say is that,

01:58:14 so that book, I think, I forget when it was, late 80s, 90s.

01:58:20 The problem is that there just hasn’t been much

01:58:22 that’s actually worked out since then.

01:58:24 So most of the books that are kind of trying to tell you

01:58:26 about all the glorious things that have happened

01:58:28 since 1973 are, they’re mostly telling you

01:58:32 about how glorious things are,

01:58:33 which actually don’t really work.

01:58:35 And it’s really, the argument people sometimes make

01:58:38 in favor of these books as well, oh, they’re really great

01:58:41 because you want to do something that will get kids excited.

01:58:43 And then, so they’re getting excited about things,

01:58:45 something that’s not really quite working.

01:58:47 It doesn’t really matter, the main thing is get them excited.

01:58:50 The other argument is, wait a minute,

01:58:53 if you’re getting people excited about ideas that are wrong,

01:58:56 you’re really kind of, you’re actually kind of discrediting

01:58:59 the whole scientific enterprise in a not really good way.

01:59:02 So there’s this problem.

01:59:04 So my general feeling about expository stuff is, yeah,

01:59:07 it’s to the extent you can do it kind of honestly

01:59:10 and, well, that’s great.

01:59:12 There are a lot of people doing that now,

01:59:14 but to the extent that you’re just trying to get people

01:59:20 excited and enthusiastic by kind of telling them stuff,

01:59:22 which isn’t really true,

01:59:24 you really shouldn’t be doing that.

01:59:26 You obviously have a much better intuition about physics.

01:59:28 I tend to, in the space of AI, for example,

01:59:32 you could use certain kinds of language,

01:59:37 like calling things intelligent

01:59:41 that could rub people the wrong way.

01:59:43 But I never had a problem with that kind of thing,

01:59:46 saying that a program can learn its way

01:59:48 without any human supervision as AlphaZero does

01:59:52 to play chess.

01:59:53 To me, that may not be intelligence,

01:59:57 but it sure as heck seems like a few steps

02:00:01 down the path towards intelligence.

02:00:04 And so I think that’s a very peculiar property

02:00:09 of systems that can be engineered.

02:00:10 So even if the idea is fuzzy,

02:00:12 even if you’re not really sure what intelligence is,

02:00:15 or if you don’t have a deep fundamental understanding

02:00:19 or even a model what intelligence is,

02:00:21 if you build a system that sure as heck is impressive

02:00:24 and showing some of the signs

02:00:26 of what previously thought impossible

02:00:29 for a nonintelligent system,

02:00:32 then that’s impressive and that’s inspiring

02:00:34 and that’s okay to celebrate.

02:00:36 In physics, because you’re not engineering anything,

02:00:39 you’re just now swimming in the space,

02:00:41 directly when you do theoretical physics,

02:00:43 that it could be more dangerous.

02:00:45 You could be out too far away from shore.

02:00:48 Yeah, well, the problem, I think physics is,

02:00:52 I think it’s actually hard for people even to believe

02:00:55 or really understand how that this particular kind

02:01:00 of physics has gotten itself into a really unusual

02:01:02 and strange and historically unusual state,

02:01:05 which is not really.

02:01:06 I mean, I spent half my life among mathematicians

02:01:09 and half of the physicists,

02:01:10 and mathematics is kind of doing fine.

02:01:12 People are making progress

02:01:14 and it has all the usual problems,

02:01:16 but also, so you could have a,

02:01:19 but I just, I don’t know,

02:01:21 I’ve never seen anything at all happening in mathematics

02:01:23 like what’s happened in this specific area in physics.

02:01:26 It’s just the kind of sociology of this,

02:01:29 the way this field works banging up

02:01:33 against this harder problem without anything

02:01:37 from experiment to help it.

02:01:38 It’s really, it’s led to some really kind

02:01:41 of problematic things.

02:01:43 And those, so it’s one thing to kind of oversimplify

02:01:48 or to slightly misrepresent,

02:01:49 to try to explain things in a way that’s not quite right,

02:01:52 but it’s another thing to start promoting to people

02:01:56 as a success as ideas, which really completely failed.

02:02:00 And so, I mean, I’ve kind of a very, very specific,

02:02:03 if you used to have people, I won’t name any names,

02:02:07 for instance, coming on certain podcasts like yours,

02:02:09 telling the world, this is a huge success

02:02:12 and this is really wonderful.

02:02:13 And it’s just not true.

02:02:16 And this is really problematic

02:02:19 and it carries a serious danger of once,

02:02:24 when people realize that this is what’s going on,

02:02:29 that the loss of credibility of science

02:02:32 is a real, real problem for our society.

02:02:34 And you don’t want people to have an all too good reason

02:02:39 to think that what they’re being told

02:02:44 by kind of some of the best institutions

02:02:46 or a country or authorities is not true.

02:02:49 You know, it’s not true, it’s a problem.

02:02:52 That’s obviously characteristic of not just physics,

02:02:55 it’s sociology.

02:03:00 And it’s, I mean, obviously in the space of politics,

02:03:02 it’s the history of politics is you sell ideas to people,

02:03:11 even when you don’t have any proof

02:03:14 that those ideas actually work in the US

02:03:16 because if they’ve worked in that,

02:03:17 that seems to be the case throughout history.

02:03:23 And just like you said, it’s human beings running up

02:03:26 against a really hard problem.

02:03:28 I’m not sure if this is like a particular like trajectory

02:03:35 through the progress of physics

02:03:37 that we’re dealing with now

02:03:38 or it’s just a natural progress of science.

02:03:40 You run up against a really difficult stage of a field

02:03:44 and different people behave differently in the face of that.

02:03:53 Some sell books and sort of tell narratives

02:03:56 that are beautiful and so on.

02:03:57 They’re not necessarily grounded in solutions

02:04:00 that have proven themselves.

02:04:02 Others kind of put their head down quietly,

02:04:05 keep doing the work.

02:04:06 Others sort of pivot to different fields

02:04:08 and that’s kind of like, yeah, ants scattering.

02:04:11 And then you have fields like machine learning,

02:04:14 which there was a few folks mostly scattered away

02:04:17 from machine learning in the 90s,

02:04:19 in the winter of AI, AI winter, as they call it.

02:04:22 But a few people kept their head down

02:04:24 and now they’re called the fathers of deep learning.

02:04:27 And they didn’t think of it that way.

02:04:31 And in fact, if there’s another AI winter,

02:04:33 they’ll just probably keep working on it anyway,

02:04:35 sort of like loyal ants sticking to a particular thing.

02:04:40 So it’s interesting, but you’re sort of saying

02:04:43 that we should be careful over hyping things

02:04:46 that have not proven themselves

02:04:48 because people will lose trust in the scientific process.

02:04:53 But unfortunately, there’s been other ways

02:04:56 in which people have lost trust in the scientific process.

02:04:59 That ultimately has to do actually

02:05:01 with all the same kind of behavior as you’re highlighting,

02:05:04 which is not being honest and transparent

02:05:07 about the flaws of mistakes of the past.

02:05:10 Yeah, I mean, that’s always a problem.

02:05:12 But this particular field is kind of fun.

02:05:14 It’s always a strange one.

02:05:17 I mean, I think in the sense that

02:05:20 there’s a lot of public fascination with it

02:05:22 that it seems to speak to kind of our deepest questions

02:05:24 about what is this physical reality?

02:05:27 Where do we come from?

02:05:28 And these kind of deep issues.

02:05:30 So there’s this unusual fascination with it.

02:05:33 Mathematics is very different.

02:05:34 Nobody’s that interested in mathematics.

02:05:36 Nobody really kind of expects to learn really great,

02:05:40 deep things about the world from mathematics that much.

02:05:42 They don’t ask mathematicians that.

02:05:44 So it’s a very unusual,

02:05:46 it draws this kind of unusual amount of attention.

02:05:50 And it really is historically in a really unusual state.

02:05:54 It’s gotten itself way kind of down a blind alley

02:06:01 in a way which it’s hard to find

02:06:04 other historical parallels to.

02:06:06 But sort of to push back a little bit,

02:06:08 there’s power to inspiring people.

02:06:10 And if I just empirically look,

02:06:13 physicists are really good at combining science

02:06:21 and philosophy and communicating it.

02:06:24 Like there’s something about physics often

02:06:26 that forces you to build a strong intuition

02:06:28 about the way reality works, right?

02:06:31 And that allows you to think through sort of

02:06:34 and communicate about all kinds of questions.

02:06:37 Like if you see physicists,

02:06:38 it’s always fascinating to take on problems

02:06:41 that have nothing to do with their particular discipline.

02:06:43 They think in interesting ways

02:06:45 and they’re able to communicate

02:06:47 their thinking in interesting ways.

02:06:48 And so in some sense, they have a responsibility

02:06:52 not just to do science, but to inspire.

02:06:55 And not responsibility, but the opportunity.

02:06:58 And thereby, I would say a little bit of a responsibility.

02:07:02 Yeah, yeah.

02:07:03 But I don’t know, anyway, it’s hard to say

02:07:06 because there’s many, many people doing this kind of thing

02:07:10 with different degrees of success and whatever.

02:07:15 I guess one thing, but I mean,

02:07:19 what’s kind of front and center for me

02:07:21 is kind of a more parochial interest

02:07:22 is just kind of what damage do you do

02:07:27 to the subject itself, ignoring,

02:07:30 okay, misrepresenting what high school students think

02:07:33 about string theory and that doesn’t matter much,

02:07:36 but what the smartest undergraduates

02:07:40 or the smartest graduate students in the world think about it

02:07:43 and what paths you’re leading them down

02:07:45 and what story you’re telling them

02:07:47 and what textbooks you’re making them read

02:07:49 and what they’re hearing.

02:07:51 And so a lot of what’s motivated me

02:07:53 is more to try to speak to this kind of a specific population

02:07:57 of people to make sure that, look, people,

02:08:01 it doesn’t matter so much what the average person

02:08:05 on the street thinks about string theory,

02:08:06 but what the best students at Columbia or Harvard

02:08:12 or Princeton or whatever who really wanna change,

02:08:14 work in this field and wanna work that way,

02:08:16 what they know about it, what they think about it

02:08:19 and that they not be going to the field being misled

02:08:22 and believing that a certain story,

02:08:23 this is where this is all going,

02:08:25 this is what I gotta do, that’s important to me.

02:08:29 Well, in general, for graduate students,

02:08:31 for people who seek to be experts in the field,

02:08:34 diversity of ideas is really powerful

02:08:36 and is getting into this local pocket of ideas

02:08:40 that people hold on to for several decades is not good,

02:08:43 no matter what the idea.

02:08:44 I would say no matter if the idea is right or wrong,

02:08:47 because there’s no such thing as right in the long term,

02:08:51 like it’s right for now until somebody builds on

02:08:56 something much bigger on top of it.

02:08:58 It might end up being right,

02:09:00 but being a tiny subset of a much bigger thing.

02:09:03 So you always should question sort of the ways of the past.

02:09:07 Yeah, so how to kind of achieve

02:09:10 that kind of diversity of thought

02:09:12 and within kind of the sociology

02:09:15 of how we organize scientific researches.

02:09:17 I know this is one thing that I think it’s very interesting

02:09:19 that Sabina Hassenfelder has very interesting things

02:09:22 to say about it.

02:09:23 And I think also Lee Smolin in his book,

02:09:25 which is also about that very much in agreement with them

02:09:29 that there’s a really kind of important questions

02:09:36 about how research in this field is organized

02:09:41 and what can you do to kind of get more diversity of thought

02:09:46 and get people thinking about a wider range of ideas.

02:09:53 At the bottom, I think humility always helps.

02:09:55 Well, the problem is that it’s also,

02:09:59 it’s a combination of humility to know when you’re wrong

02:10:02 and also, but also you have to have a certain

02:10:06 very serious lack of humility to believe

02:10:08 that you’re gonna make progress on some of these problems.

02:10:11 I think you have to have like both modes

02:10:13 and switch between them when needed.

02:10:18 Let me ask you a question

02:10:19 you’re probably not gonna wanna answer

02:10:21 because you’re focused on the mathematics of things

02:10:25 and mathematics can’t answer the why questions,

02:10:27 but let me ask you anyway.

02:10:30 Do you think there’s meaning to this whole thing?

02:10:33 What do you think is the meaning of life?

02:10:34 Why are we here?

02:10:36 I don’t know.

02:10:37 Yeah, I was thinking about this.

02:10:39 So the, and it did occur to me,

02:10:42 one interesting thing about that question

02:10:45 is that you don’t,

02:10:47 yeah, so I have this life in mathematics

02:10:51 and this life in physics

02:10:52 and I see some of my physicist colleagues,

02:10:55 kind of seem to be, people are often asking them,

02:10:59 what’s the meaning of life?

02:11:00 And they’re writing books about the meaning of life

02:11:02 and teaching courses about the meaning of life.

02:11:04 But then I realized that no one ever asked

02:11:06 my mathematician colleagues.

02:11:08 Nobody ever asked mathematicians.

02:11:10 Yeah, that’s funny.

02:11:11 So yeah, everybody just kind of assumes,

02:11:15 okay, well, you people are studying mathematics,

02:11:16 whatever you’re doing, it’s maybe very interesting,

02:11:19 but it’s clearly not gonna tell me anything useful

02:11:21 about the meaning of my life.

02:11:22 And I’m afraid a lot of my point of view is that

02:11:25 if people realized how little difference there was

02:11:28 between what the mathematicians are doing

02:11:29 and what a lot of these theoretical physicists are doing,

02:11:32 they might understand that it’s a bit misguided

02:11:35 to look for deep insight into the meaning of life

02:11:39 from many theoretical physicists.

02:11:42 It’s not, they’re people,

02:11:45 they may have interesting things to say about this.

02:11:47 You’re right, they know a lot about physical reality

02:11:50 and about, in some sense about metaphysics,

02:11:53 about what is real of this kind.

02:11:56 But you’re also, to my mind,

02:12:02 I think you’re also making a bit of a mistake

02:12:03 that you’re looking to, I mean, I’m very, very aware

02:12:07 that I’ve led a very pleasant

02:12:10 and fairly privileged existence

02:12:11 and fairly without many challenges of different kinds

02:12:15 and of a certain kind.

02:12:16 And I’m really not in no way the kind of person

02:12:21 that a lot of people who are looking for

02:12:24 to try to understand in some sense the meaning of life

02:12:27 in the sense of the challenges that they’re facing in life.

02:12:30 I can’t really, I’m really the wrong person

02:12:32 for you to be asking about this.

02:12:34 Well, if struggle is somehow a thing that’s core to meaning,

02:12:39 perhaps mathematicians are just quietly the ones

02:12:42 who are most equipped to answer that question

02:12:45 if, in fact, the creation or at least experiencing beauty

02:12:53 is at the core of the meaning of life.

02:12:55 Because it seems like mathematics is the methodology

02:12:59 by which you can most purely explore beautiful things, right?

02:13:04 Yeah, yeah.

02:13:05 So in some sense,

02:13:06 maybe we should talk to mathematicians more.

02:13:08 Yeah, yeah, maybe, but unfortunately,

02:13:12 people do have a somewhat correct perception

02:13:14 that what these people are doing every day

02:13:17 or whatever is pretty far removed from anything.

02:13:21 Yeah, from what’s kind of close to what I do every day

02:13:26 and what my typical concerns are.

02:13:28 So you may learn something very interesting

02:13:29 by talking to mathematicians,

02:13:31 but it’s probably not gonna be,

02:13:33 you’re probably not gonna get what you were hoping.

02:13:37 So when you put the pen and paper down,

02:13:39 you’re not thinking about physics

02:13:41 and you’re not thinking about mathematics

02:13:43 and you just get to breathe in the air and look around you

02:13:46 and realize that you’re going to die one day.

02:13:49 Yeah.

02:13:50 Do you think about that?

02:13:53 Your ideas will live on, but you, the human.

02:13:56 Not especially much.

02:13:58 Certainly, I’ve been getting older.

02:14:00 I’m now 64 years old.

02:14:01 You start to realize, well,

02:14:02 there’s probably less ahead than there was behind.

02:14:05 And so you start to, that starts to become,

02:14:09 what do I think about that?

02:14:10 Maybe I should actually get serious

02:14:13 about getting some things done,

02:14:14 which I may not have,

02:14:17 which I may otherwise not have time to do,

02:14:18 which I didn’t see.

02:14:20 And this didn’t seem to be a problem when I was younger,

02:14:22 but that’s the main,

02:14:24 I think the main way in which that thought occurred.

02:14:26 But it doesn’t, you know, the stoics are big on this.

02:14:30 Meditating on mortality helps you

02:14:33 more intensely appreciate the beauty

02:14:36 when you do experience it.

02:14:38 I suppose that’s true, but it’s not,

02:14:41 yeah, it’s not something I’ve spent a lot of time trying,

02:14:45 but yeah.

02:14:47 Day to day, you just enjoy the positives, the mathematics.

02:14:49 Just enjoy, yeah, our life in general.

02:14:52 Life is, I have a perfectly pleasant life and enjoy it.

02:14:57 And I often think, wow, this is,

02:15:00 things are, I’m really enjoying this.

02:15:02 Things are going well.

02:15:04 Yeah, life is pretty amazing.

02:15:06 I think you and I are pretty lucky.

02:15:08 We get to live on this nice little earth

02:15:11 with a nice little comfortable climate,

02:15:13 and we get to have this nice little podcast conversation.

02:15:17 Thank you so much for spending your valuable time

02:15:19 with me today and having this conversation.

02:15:21 Thank you.

02:15:22 Glad to, thank you, thank you.

02:15:25 Thanks for listening to this conversation with Peter White.

02:15:27 To support this podcast,

02:15:29 please check out our sponsors in the description.

02:15:32 And now, let me leave you with some words

02:15:34 from Richard Feynman.

02:15:36 The first principle is that you must not fool yourself,

02:15:40 and you are the easiest person to fool.

02:15:43 Thank you for listening and hope to see you next time.