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.