back to index## Peter Woit: Theories of Everything & Why String Theory is Not Even Wrong | Lex Fridman Podcast #246

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The following is a conversation with Peter White,

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a theoretical physicist at Columbia,

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outspoken critic of string theory,

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and the author of the popular physics and mathematics blog

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called Not Even Wrong.

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This is the Lex Friedman podcast.

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To support it, please check out our sponsors

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in the description.

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

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You're both a physicist and a mathematician.

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So let me ask, what is the difference

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between physics and mathematics?

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Well, there's kind of a conventional understanding

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of the subject that they're two quite different things.

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So that mathematics is about making rigorous statements

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about these abstract things,

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things of mathematics, and proving them rigorously.

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And physics is about doing experiments

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and testing various models and that.

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But I think the more interesting thing

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is that there's a wide variety of what people do

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as mathematics, what they do as physics,

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and there's a significant overlap.

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And that, I think, is actually a very interesting area.

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And if you go back kind of far enough in history

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and look at figures like Newton or something,

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at that point, you can't really tell,

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was Newton a physicist or a mathematician?

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Mathematicians will tell you he was a mathematician.

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The physicists will tell you he was a physicist.

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But he would say he's a philosopher.

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Yeah, that's interesting.

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

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then that's more of a modern thing.

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But anyway, I think these days,

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

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So in the story of the 20th century

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and the early 21st century,

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what is the overlap between mathematics and physics,

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

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I think it's really interesting to see

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a lot of what my colleagues in the math department

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are doing, most of what they're doing,

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they're doing all sorts of different things,

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but most of them have some kind of overlap

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with physics or other.

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So, I mean, I'm personally interested

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in one particular aspect of this overlap,

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

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about physics and about mathematics.

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

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Which particular overlap are you looking at, group theory?

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Yeah, so at least the way it seems to me

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that if you look at physics

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and look at our most successful laws of fundamental physics,

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they have a certain kind of mathematical structure,

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it's based upon certain kind of mathematical objects

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and geometry, connections and curvature,

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the spinners, the Dirac equation.

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And this very deep mathematics provides kind of a unifying

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set of ways of thinking that allow you

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to make a unified theory of physics.

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But the interesting thing is that if you go to mathematics

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and look at what's been going on in mathematics

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

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there's a similarly some kind of unifying ideas

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which bring together different areas of mathematics

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

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Especially powerful in number theory recently.

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

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about love and math.

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

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It's partially accessible.

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

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while running an exceptionally long distance,

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like across the San Francisco bridge.

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

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But some of the group theory in there

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is a little bit difficult.

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

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to kind of really say what's going on

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and make it accessible is very hard.

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

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that kinds of mathematics he's interested in

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and that he's talking about provide

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kind of a grand unified theory of mathematics.

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They bring together geometry and number theory

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and representation theory, a lot of different ideas

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in a really unexpected way.

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But I think, to me, the most fascinating thing

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is if you look at the kind of grand unified theory

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of mathematics he's talking about

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and you look at the physicist kind of ideas

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about unification, it's more or less

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the same mathematical objects are appearing in both.

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

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we're seeing a really strong indication

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that the deepest ideas that we're discovering about physics

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and some of the deepest ideas that mathematicians

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are learning about are really, are intimately connected.

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Is there something, like if I was five years old

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and you were trying to explain this to me,

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is there ways to try to sneak up

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to what this unified world of mathematics looks like?

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You said number theory, you said geometry,

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words like topology.

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What does this universe begin to look like?

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Are these, what should we imagine in our mind?

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Is it a three dimensional surface?

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And we're trying to say something about it.

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Is it triangles and squares and cubes?

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Like what are we supposed to imagine in our minds?

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Is this natural number?

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What's a good thing to try to,

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for people that don't know any of these tools

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except maybe some basic calculus and geometry

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from high school that they should keep in their minds

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as to the unified world of mathematics

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

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I mean, what I find kind of remarkable about this

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

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but they're actually quite alien

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to our everyday understanding.

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We grow up in this three spatial dimensional world

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and we have intimate understanding

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of certain kinds of geometry and certain kinds of things.

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But these things that we've discovered

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in both math and physics are,

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that they're not at all close,

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have any obvious connection

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to kind of human everyday experience.

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They're really quite different.

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And I can say some of my initial fascination with this

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when I was young and starting to learn about it

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was actually exactly this kind of arcane nature

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It was a little bit like being told,

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well, there are these kind of semi mystical experience

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that you can acquire by a long study and whatever,

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except that it was actually true.

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There's actually evidence that this actually works.

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

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that kind of thing,

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because I think it's mostly misleading.

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

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And maybe one interesting thing to say very,

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

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is that when we think about the geometry

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of our space and time,

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

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It's a physics is in some sense

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

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And a really interesting thing about

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some of the recent developments and number theory

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have been to realize that these ideas

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that we were looking at naturally fit into a context

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where your theory is kind of four dimensional.

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So, geometry is a big part of this

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and we know a lot and feel a lot about

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two, one, two, three dimensional geometry.

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So wait a minute, so we can at least rely

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on the four dimensions of space and time

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and say that we can get pretty far

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by working in those four dimensions.

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I thought you were gonna scare me

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

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many more dimensions than that.

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My point of view, which goes against

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a lot of these ideas about unification

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is that no, this is really,

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everything we know about really is about four dimensions

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and that you can actually understand a lot of these

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structures that we've been seeing in fundamental physics

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

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

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has been a really, has been kind of a mistake

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that physicists have made for decades and decades

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to try to go to higher dimensions,

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to try to formulate a theory in higher dimensions

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and then you're stuck with the problem

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of how do you get rid of all these extra dimensions

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that you've created

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because we only ever see anything in four dimensions.

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That kind of thing leaves us astray, you think?

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So creating all these extra dimensions

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just to give yourself extra degrees of freedom.

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Isn't that the process of mathematics

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is to create all of these trajectories for yourself

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but eventually you have to end up at the final place

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but it's okay to sort of create abstract objects

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on your path to proving something.

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

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I mean, the kinds of,

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mathematicians also are very different than physicists

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in that we like to develop very general theories.

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We like to, if we have an idea,

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we want to see what's the greatest generality

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in which you can talk about it.

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

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is formulated by mathematicians,

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

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

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There's no particular, for most of geometry,

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there's no particular special thing about four.

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But anyway, but what physicists have been trying to do

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over the years is try to understand

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these fundamental theories in a geometrical way

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

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extra dimensions and using them to explain the structure.

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But typically this attempt kind of founders

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because you just don't know,

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

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It is nice in the space of physics

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

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

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

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

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

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because we live in a universe with n equals four

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Yeah, physicists are very interested in saying something

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about specific examples and I find that interesting

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when I'm trying to do things in mathematics

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and I'm even teaching courses into mathematics students,

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

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than most mathematicians because I'm very often

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

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example that shows how this powerful new mathematical

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

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

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about exactly when it's gonna work

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and when it's not gonna work.

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Do you usually think about really simple examples,

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like both for teaching and when you try to solve

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a difficult problem, do you construct the simplest

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possible examples that captures the fundamentals

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of the problem and try to solve it?

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

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

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to boil it down to what's the simplest situation

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in which this kind of thing is gonna happen

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and then try to really understand that and understand that

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and that is almost always a really good way

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to get insight into it.

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

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for me coming from the programming side,

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

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of mathematical object, I like to mess around

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with it sort of numerically.

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I just visualize different parts of it,

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visualize however I can so most of the work

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

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is you try to play with the simplest possible example

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and just to build up intuition by any kind of object

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has a bunch of variables in it and you start

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to mess around with them in different ways

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and visualize in different ways to start

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to build intuition or do you go the Einstein route

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and just imagine everything inside your mind

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and sort of build thought experiments

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and then work purely on paper and pen?

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Well, the problem with this kind of stuff

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

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it's rarely something that is really kind of,

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or even the simplest example, you can kind of see

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what's going on by looking at something happening

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in three dimensions.

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There's generally the structures involved

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are either they're more abstract

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

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and where you could manipulate them

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in some kind of geometrical way,

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it's gonna be a much higher dimensional space.

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So even simple examples,

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the embedding them into three dimensional space,

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you're losing a lot.

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

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

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So it starts to get to be hard to,

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

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as to kind of think about things in your mind

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and I often use pad and paper

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

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and you are kind of drawing things

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but they're really kind of more abstract representations

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of how things are supposed to fit together

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and they're not really, unfortunately,

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not just kind of really living in three dimensions

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Are we supposed to be sad or excited

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by the fact that our human minds

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can't fully comprehend the kind of mathematics

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you're talking about?

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I mean, what do we make of that?

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

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

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that we'll never truly get to experience directly.

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It is kind of sad how difficult this is.

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I mean, or I would put it a different way

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that most questions that people have

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about this kind of thing,

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you can give them a really true answer

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and really understand it

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but the problem is one more of time.

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

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

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and work at this repeatedly for hours and days and weeks

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

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to really wrap itself around what's going on

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and so that does make things inaccessible which is sad

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but it's just kind of part of life

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that we all have a limited amount of time

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

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Speaking of a limited amount of time,

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

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here on this podcast.

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

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that you work on in mathematics and physics,

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which is the most beautiful idea

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

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and once again, unfortunately, the way life works,

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we only have a limited time together

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to try to convey such an idea.

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

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I'm tempted to kind of start trying to explain

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what I think is this most powerful idea

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that brings together math and physics,

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ideas about groups and representations

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and how it fits in quantum mechanics

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

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and I don't think we really have time

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to get very far into it so.

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Well, can I actually, on a small tangent,

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you did write a paper towards a grant unified theory

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mathematics and physics, maybe you could step there first,

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what is the key idea in that paper?

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

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

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earlier that just kind of a claim that if you look

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and see what have been successful ideas in unification

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in physics and over the last 50 years or so

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and what's been happening in mathematics

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

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that these are very much the same kind of mathematics

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

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you shouldn't be looking to unify just math

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or just fundamental physics but taking inspiration

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for looking for new ideas in fundamental physics

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that they are gonna be in the same direction

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of getting deeper into mathematics

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and looking for more inspiration in mathematics

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from these successful ideas about fundamental physics.

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Could you put words to sort of the disciplines

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we're trying to unify?

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So you said number theory, are we literally talking

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about all the major fields of mathematics?

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So it's like the number theory, geometry,

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so the differential geometry, topology.

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

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that this is acquired in mathematics

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is the so called Langlands program

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and so this started out in mathematics.

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It's that Robert Langlands kind of realized

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that a lot of what people were doing

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and that was starting to be really successful

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in number theory in the 60s

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and so that this actually was,

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anyway, that this could be thought of

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in terms of these ideas about symmetry

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and groups and representations

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and in a way that was also close

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to some ideas about geometry

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

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there was something called geometric Langlands

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that people realize that you could take

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what people have been doing in number theory in Langlands

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and get rid, just forget about the number theory

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and ask what is this telling you about geometry

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and you get a whole, some new insights

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into certain kinds of geometry that way.

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

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for this area is Langlands and geometric Langlands

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and just recently in the last few months,

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

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that appeared by Peter Schultze and Laurent Farg

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where they made some serious advance

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to try to understand very much kind of a local problem

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of what happens in number theory

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near a certain prime number

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and they turned this into a problem

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of exactly the kind that geometric Langlands people

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had been doing, this kind of pure geometry problem

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and they found by generalizing mathematics,

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they could actually reformulate it in that way

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and it worked perfectly well.

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

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knowledgeable person and then, what is it?

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At least I'm in the neighborhood

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like theoretical computer science, right?

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And it's still way out of my reach

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

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is one of the most brilliant people in mathematics

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and just really admire his work

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

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that he composed and it makes me sad.

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Yeah, well, I mean, I think unfortunately,

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

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have no, really don't actually understand

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what this is about.

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I mean, the group of people who really understand

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all these ideas and so for instance,

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

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the number of people who really actually understand

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how that works is anyway, very, very small

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

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and physicists, even they will often feel that,

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there's this really interesting sounding stuff going on

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and which I should be able to understand,

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

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

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

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of beauty, is there an idea that maybe

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is a little bit smaller that you find beautiful

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in the space of mathematics or physics?

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

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and spent a lot of time learning about mathematics

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and I guess it was embarrassing

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that I hadn't really actually understand

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this very simple idea until I kind of learned it

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when I actually started teaching math classes,

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which is maybe that there's a simple way

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to explain kind of the fundamental way

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in which algebra and geometry are connected.

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So you normally think of geometry as about these spaces

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and these points and you think of algebra

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as this very abstract thing about these abstract objects

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that satisfy certain kinds of relations,

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you can multiply them and add them and do stuff

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but it's completely abstract,

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there's nothing geometric about it

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but the kind of really fundamental idea

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is that unifies algebra and geometry

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is to think whenever anybody gives you

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what you call an algebra, some abstract thing

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of things that you can multiply and add

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that you should ask yourself,

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is that algebra the space of functions on some geometry?

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So one of the most surprising examples of this,

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for instance, is a standard kind of thing

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that seems to have nothing to do with geometry

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

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but it seems to have nothing to do with geometry

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but what you can, it turns out,

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but if you ask yourself this question

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and ask, you know, are integers,

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can you think, if somebody gives you an integer,

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

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And it turns out that yes, you can

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and the space is the space of prime numbers

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and so what you do is you just,

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if somebody gives you an integer,

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you can make a function on the prime numbers

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

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that integer modulo that prime.

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

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

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

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What is its value at three?

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

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

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and you can kind of keep going.

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

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

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and it just links these two parts of mathematics

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that look completely different

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and it's just an incredibly powerful idea

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and so much of mathematics emerges

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from this kind of simple relation.

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So you're talking about mapping

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from one discrete space to another.

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So for a second, I thought perhaps mapping

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like a continuous space to a discrete space,

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like functions over a continuous space, because yeah.

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

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

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

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The part of the same idea is that if you try

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

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that what you should do is you should wait,

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so say, wait a minute,

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maybe I should be trying to solve this using algebra.

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

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you give me the space,

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

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

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I can take different kinds of functions

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and different kinds of values,

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but basically functions on a space.

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So what this insight is telling you is that

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

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is to change your problem into algebra

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by changing your space, stop thinking about your space

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

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And if you're an algebraist

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and you've got these abstract algebraic gadgets

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

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

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as a function on a space?

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What would that space be

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and what kind of functions would they be?

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And that going back and forth really brings

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these two completely different looking areas

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of mathematics together.

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Do you have particular examples where it allowed

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to prove some difficult things

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by jumping from one to the other?

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Is that something that's a part of modern mathematics

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where such jumps are made?

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Oh yeah, this is kind of all the time.

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

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But, and when you start doing this,

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you start to realize that you need,

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what simple things on one side of the algebra

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start to require you to think about the other side,

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about geometry in a new way.

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You have to kind of get a more sophisticated idea

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about geometry, or if you start thinking

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about the functions on a space,

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you may need a more sophisticated kind of algebra.

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But in some sense, I mean,

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much or most of modern number theory

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is based upon this move to geometry.

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And there's also a lot of geometry

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and topology is also based upon, yeah, change.

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If you want to understand the topology of something,

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you look at the functions, you do drum comology

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and you get the topology.

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Well, let me ask you then the ridiculous question.

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You said that this idea is beautiful.

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Can you formalize the definition of the word beautiful?

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And why is this beautiful?

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First, why is this beautiful?

link |

And second, what is beautiful?

link |

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

link |

you can find beautiful for different reasons.

link |

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

link |

I think really is just kind of an idea is beautiful

link |

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

link |

and information into something very simple.

link |

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

link |

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

link |

What non trivial things does it tell you

link |

versus how simply can you express the idea?

link |

So the level of compression,

link |

what is it correlates with beauty?

link |

Yeah, that's one aspect of it.

link |

And so you can start to tell that an idea

link |

is becoming uglier and uglier

link |

as you start kind of having to,

link |

it doesn't quite do what you want.

link |

So you throw in something else to the idea

link |

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

link |

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

link |

and uglier when you have to kind of keep adding

link |

and more into what was originally a fairly simple idea

link |

and making it more and more complicated

link |

to get what you want.

link |

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

link |

and try to make some sense of them.

link |

One word is beauty, another one is simplicity

link |

as you mentioned, another one is truth.

link |

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

link |

one is simpler, one is more complicated.

link |

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

link |

to capture deeply the fabric of reality,

link |

the simple one or the more complicated one?

link |

Yeah, I think all of our evidence,

link |

what we see in the history of the subject

link |

is the simpler one though.

link |

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

link |

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

link |

anyway, the kind of best theories

link |

we've been coming up with are ultimately

link |

when properly understood, relatively simple

link |

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

link |

Do you have a good explanation why that is?

link |

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

link |

Are we just like ultra biased

link |

and we just kind of convince ourselves

link |

that simple is better because we find simplicity beautiful?

link |

Or is there something about our actual universe

link |

that at the core is simple?

link |

My own belief is that there is something about a universe

link |

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

link |

there is some kind of fundamental thing about math,

link |

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

link |

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

link |

have certain, are very limited

link |

and can certainly do certain things and not others.

link |

So it's in principle possible

link |

that there's some great insight in,

link |

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

link |

which just aren't accessible to us because

link |

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

link |

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

link |

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

link |

So there's a brilliant physicist

link |

by the name of Sabine Hassenfelder

link |

who both agrees and disagrees with you.

link |

I suppose agrees that the final answer will be simple.

link |

But simplicity and beauty leads us astray

link |

in the local pockets of scientific progress.

link |

Do you agree with her disagreement

link |

and do you disagree with her agreement?

link |

And agree with the agreement and so on.

link |

Anyway, yes, I found it was really fascinating

link |

reading her book and anyway,

link |

I was finding disagreeing with a lot,

link |

but then at the end when she says yes,

link |

when we find, when we actually figure this out,

link |

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

link |

But does beauty lead us astray,

link |

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

link |

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

link |

I don't think, and especially,

link |

and I actually fairly strongly disagree with her

link |

about sometimes the way she'll refer to math.

link |

And so the problem is, physicists and people in general

link |

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

link |

not what I would call math,

link |

which is the interesting ideas of math,

link |

but just some complicated calculation.

link |

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

link |

the problem with talking about simplicity

link |

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

link |

it's very easy to fool yourself

link |

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

link |

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

link |

and you fall in love with it.

link |

And it's like any kind of love affair,

link |

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

link |

is much more beautiful than the others might think

link |

and that they really are.

link |

And that's very, very easy to do.

link |

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

link |

and this and mathematics and this,

link |

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

link |

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

link |

she was thinking of about where people have gone astray,

link |

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

link |

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

link |

wonderful idea which they'd found

link |

and it turned out not to be useful,

link |

but it was more that they kind of fooled themselves

link |

that this was actually a better idea than it really was

link |

and that it was simpler and more beautiful

link |

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

link |

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

link |

leads us astray, it's just people are people

link |

and they fall in love with whatever idea they have

link |

and then they weave narratives around that idea

link |

or they present it in such a way

link |

that emphasizes the simplicity and the beauty.

link |

Yeah, that's part of it.

link |

But I mean, the thing about physics that you have

link |

is that what really can tell,

link |

if you can do an experiment and check

link |

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

link |

you do in principle have a way of really testing it

link |

and it's certainly true that if you thought

link |

you had a simple idea and that doesn't work

link |

and you go out and do an experiment

link |

and what actually does work is some more,

link |

maybe some more complicated version of it,

link |

that can certainly happen and that can be true.

link |

I think her emphasis is more,

link |

that I don't really disagree with,

link |

is that people should be concentrating

link |

on when they're trying to develop better theories

link |

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

link |

but not is this idea beautiful,

link |

but is there something about the theory

link |

which is not quite consistent and use that as a guide

link |

that there's something wrong there which needs fixing.

link |

And so I think that part of her argument,

link |

I think we're on the same page about.

link |

What is consistency and inconsistencies?

link |

What exactly, do you have examples in mind?

link |

Well, it can be just simple inconsistency

link |

between theory and an experiment that if you,

link |

so we have this great fundamental theory,

link |

but there are some things that we see out there

link |

which don't seem to fit in it,

link |

like dark energy and dark matter, for instance.

link |

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

link |

I think she would argue and I would agree

link |

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

link |

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

link |

you should kind of test any of your ideas

link |

with kind of a thought experiment.

link |

Does this actually give a consistent picture

link |

of what's gonna happen, of what happens

link |

in this particular situation or not?

link |

So this is a good example.

link |

You've written about this.

link |

Since quantum gravitational effects are really small,

link |

super small, arguably unobservably small,

link |

should we have hope to arrive

link |

at a theory of quantum gravity somehow?

link |

What are the different ways we can get there?

link |

You've mentioned that you're not as interested

link |

in that effort because basically, yes,

link |

you cannot have ways to scientifically validate it

link |

given the tools of today.

link |

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

link |

certainly spent a lot of time learning about gravity

link |

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

link |

that much in the past the focus

link |

of what I've been thinking about.

link |

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

link |

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

link |

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

link |

is just this kind of search for consistency.

link |

You know, it can be remarkably hard to come up

link |

with a completely consistent model of this

link |

in a way that brings together quantum mechanics

link |

and general relativity.

link |

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

link |

that people who have pursued quantum gravity

link |

have often pursued, you know,

link |

we have the best route to finding a consistent theory

link |

of quantum gravity and string theorists will tell you this,

link |

other people will tell you it,

link |

it's kind of what people argue about.

link |

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

link |

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

link |

that everybody could be successful.

link |

Everybody's program for how to find a theory

link |

of quantum gravity, you know, ends up with something

link |

that is consistent.

link |

And so, and in some sense you could argue

link |

this is what happened to the string theorists.

link |

They solved their problem of finding a consistent theory

link |

of quantum gravity and they ended up,

link |

but they found 10 to the 500 solutions.

link |

So you, you know, if you believe that everything

link |

that they would like to be true is true,

link |

well, okay, you've got a theory,

link |

but it ends up being kind of useless

link |

because it's just one of an infinite,

link |

essentially infinite number of things

link |

which you have no way to experimentally distinguish.

link |

And so this is just a depressing situation.

link |

But I do think that there is a,

link |

so again, I think pursuing ideas about what,

link |

more about beauty and how can you integrate

link |

and unify these issues about gravity

link |

with other things we know about physics.

link |

And can you find a theory where these fit together

link |

in a way that makes sense and hopefully predict something.

link |

That's much more promising.

link |

Well, it makes sense and hopefully,

link |

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

link |

because you kind of said a few slightly contradictory things

link |

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

link |

but then if the theory is consistent,

link |

it doesn't necessarily mean anything.

link |

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

link |

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

link |

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

link |

okay, there should be some experimental validation.

link |

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

link |

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

link |

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

link |

And beyond that, why is it wrong?

link |

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

link |

Well, one interesting thing

link |

about the current state of strength theory is that,

link |

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

link |

to at this point to say what strength theory means.

link |

If people say they're a strength theorist,

link |

what they mean and what they're doing

link |

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

link |

But the initial meaning I think goes back to,

link |

there was kind of a series of developments starting in 1984

link |

in which people felt that they had found a unified theory

link |

of our so called standard model of all the standard,

link |

well known kind of particle interactions and gravity

link |

and it all fit together in a quantum theory.

link |

And that you could do this in a very specific way

link |

by instead of thinking about having a quantum theory

link |

of particles moving around in space time,

link |

think about a quantum theory of kind of one dimensional

link |

loops moving around in space time, so called strings.

link |

And so instead of one degree of freedom,

link |

these have an infinite number of degrees of freedom.

link |

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

link |

okay, we're gonna quantize this theory of loops

link |

moving around in space time.

link |

And what they found is that you could do this

link |

and you could fairly, relatively straightforwardly

link |

make sense of such a quantum theory,

link |

but only if space and time together were 10 dimensional.

link |

And so then you had this problem,

link |

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

link |

okay, now once you make that move,

link |

you gotta get rid of six dimensions.

link |

And so the hope was that you could get rid

link |

of the six dimensions by making them very small

link |

and that consistency of the theory would require

link |

that these six dimensions satisfy a very specific condition

link |

called being a Calabi out manifold.

link |

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

link |

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

link |

was the hope that you could just take

link |

this 10 dimensional string theory

link |

and find one of a limited number of possible ways

link |

of getting rid of six dimensions by making them small

link |

and then you would end up with an effective

link |

four dimensional theory, which looked like the real world.

link |

This was the hope.

link |

So then there's then a very long story

link |

about what happened to that hope over the years.

link |

I would argue and part of the point of the book

link |

and its title was that this ultimately was a failure

link |

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

link |

there ended up being just too many ways of doing this

link |

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

link |

that it was kind of not even wrong in the sense

link |

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

link |

well enough to actually get a real falsifiable prediction

link |

out of it that would tell you it was wrong.

link |

But it was kind of in the realm of ideas

link |

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

link |

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

link |

and they don't actually end up carrying the power

link |

or that you originally had this vision of.

link |

And yes, the book title is not even wrong.

link |

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

link |

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

link |

about string theory through the decades, as you mentioned.

link |

What are the different flavors of ideas that came,

link |

like that branched out?

link |

You mentioned 10 dimensions.

link |

You mentioned loops with infinite degrees of freedom.

link |

What other interesting ideas to you

link |

that kind of emerged from this world?

link |

Well, yeah, I mean, the problem

link |

with talking about the whole subject

link |

and part of the reason I wrote the book

link |

is that it gets very, very complicated.

link |

I mean, there's a huge amount,

link |

a lot of people got very interested in this,

link |

a lot of people worked on it.

link |

And in some sense, I think what happened

link |

is exactly because the idea didn't really work

link |

that this caused people to,

link |

instead of focusing on this one idea

link |

and digging in and working on that,

link |

they just kind of kept trying new things.

link |

And so people, I think, ended up wandering around

link |

in a very, very rich space of ideas

link |

about mathematics and physics

link |

and discovering all sorts of really interesting things.

link |

It's just the problem is there tended

link |

to be an inverse relationship

link |

between how interesting and beautiful and fruitful

link |

this new idea that they were trying to pursue was

link |

and how much it looked like the real world.

link |

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

link |

I think one of the most spectacular

link |

is what the physicists call

link |

two dimensional conformal field theory.

link |

And so these are basically quantum field theories

link |

and kind of think of it as one space

link |

and one time dimension,

link |

which have just this huge amount of symmetry

link |

and a huge amount of structure,

link |

which there's some totally fantastic mathematics behind it.

link |

And again, and some of that mathematics

link |

is exactly also what appears in the Langlands program.

link |

So a lot of the first interaction between math and physics

link |

around the Langlands program has been

link |

around these two dimensional conformal field theories.

link |

Is there something you could say

link |

about what are the major problems are with string theory?

link |

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

link |

you've written that a big hole in string theory

link |

has been its perturbative definition.

link |

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

link |

Well, maybe to begin with,

link |

I think the simplest thing to say is,

link |

the initial idea really was that,

link |

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

link |

is we have this thing that only works,

link |

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

link |

for it to make sense.

link |

But then you ended up in 10 space time dimensions.

link |

And so to get back to physics,

link |

you had to get rid of five of the dimensions,

link |

six of the dimensions.

link |

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

link |

that what people just discovered is just,

link |

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

link |

there's an infinite number of ways of doing it

link |

and you can get whatever you want

link |

depending on how you do it.

link |

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

link |

and getting to four just kind of collapses

link |

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

link |

because you can get anything.

link |

The hope around that problem has always been

link |

that the standard formulation that we have of string theory,

link |

which is, you can go by the name perturbative,

link |

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

link |

of given a classical theory of constructing a quantum theory

link |

and working with it, which is the so called

link |

perturbation theory that we know how to do.

link |

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

link |

as to what to do about the six dimensions.

link |

So actual perturbed string theory by itself

link |

really only works in 10 dimensions.

link |

So you have to start making some kinds of assumptions

link |

about how I'm gonna go beyond this formulation

link |

that we really understand of string theory

link |

and get rid of these six dimensions.

link |

So kind of the simplest one was the Klabiau postulate,

link |

but when that didn't really work out,

link |

people have tried more and more different things.

link |

And the hope has always been that the solution,

link |

this problem would be that you would find a deeper

link |

and better understanding of what string theory is

link |

that would actually go beyond this perturbative expansion

link |

and which would generalize this.

link |

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

link |

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

link |

How difficult is this problem?

link |

So if I could restate the problem,

link |

it seems like there's a very consistent physical world

link |

operating in four dimensions.

link |

And how do you map a consistent physical world

link |

in 10 dimensions to a consistent physical world

link |

in four dimensions?

link |

And how difficult is this problem?

link |

Is that something you can even answer?

link |

Just in terms of physics intuition,

link |

in terms of mathematics,

link |

mapping from 10 dimensions to four dimensions.

link |

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

link |

of the six of the dimensions.

link |

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

link |

One is what we called compactification.

link |

You say that there really are 10 dimensions,

link |

but for whatever reason,

link |

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

link |

So you basically start out with 10 dimensions

link |

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

link |

but just kind of a finite extent

link |

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

link |

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

link |

So can you also help me build an intuition

link |

about how rich and interesting the world

link |

in those six dimensions is?

link |

So compactification seems to imply...

link |

Well, it's not very interesting.

link |

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

link |

if you start doing mathematics

link |

and looking at geometry and topology

link |

and more and more dimensions is that,

link |

I mean, asking the question like,

link |

what are all possible six dimensional spaces?

link |

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

link |

It's just, I mean,

link |

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

link |

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

link |

if you start trying to make,

link |

if you start trying to make one dimensional spaces,

link |

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

link |

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

link |

But as you go to higher and higher dimensions,

link |

there are just so many ways you can put things together

link |

of and get something of that dimensionality.

link |

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

link |

we're just gonna pick out some very specific ones

link |

of these six dimensional spaces.

link |

And there are just too many of them

link |

and you can get anything you want.

link |

So if you have 10 dimensions,

link |

the kind of things that happen,

link |

say that's actually the way,

link |

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

link |

There's a limited set of behaviors of objects.

link |

I don't know even know what the right terminology

link |

to use that can occur within those dimensions,

link |

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

link |

is there some consistent constraints?

link |

So if you have some constraints that map to reality,

link |

then you can start saying like,

link |

dimension number seven is kind of boring.

link |

All the excitement happens in the spatial dimensions,

link |

And time is also kind of boring.

link |

And like some are more exciting than others,

link |

or we can use our metric of beauty.

link |

Some dimensions are more beautiful than others.

link |

Once you have an actual understanding

link |

of what actually happens in those dimensions

link |

in our physical world,

link |

as opposed to sort of all the possible things

link |

that could happen.

link |

In some sense, I mean,

link |

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

link |

We don't see them.

link |

So you need to somehow explain them.

link |

The main thing you're trying to do

link |

is to explain why we're not seeing them.

link |

And so you have to come up with some theory

link |

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

link |

And string theory gives you some ideas

link |

about how to do that.

link |

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

link |

with this whole theory you're creating

link |

is to just make all of its effects essentially unobservable.

link |

So it's not a really,

link |

it's an inherently kind of dubious and worrisome thing

link |

that you're trying to do there.

link |

Why are you just adding in all this stuff

link |

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

link |

This may be a dumb question,

link |

but is this an obvious thing to state

link |

that those six dimensions are unobservable

link |

or anything beyond four dimensions is unobservable?

link |

Or do you leave a little door open

link |

to saying the current tools of physics,

link |

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

link |

but we may need to come up with methodologies

link |

for observing them.

link |

So as opposed to collapsing your mathematical theory

link |

into four dimensions,

link |

leaving the door open a little bit too,

link |

maybe we need to come up with tools

link |

that actually allow us to directly measure those dimensions.

link |

Yes, I mean, you can certainly ask,

link |

assume that we've got model,

link |

look at models with more dimensions and ask,

link |

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

link |

And you go out and do experiments.

link |

So for instance, you have a,

link |

like gravitationally you have an inverse square law of forces.

link |

If you had more dimensions,

link |

that inverse square law would change to something else.

link |

So you can go and start measuring the inverse square law

link |

and say, okay, inverse square law is working,

link |

but maybe if I get,

link |

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

link |

to measure gravitational effects

link |

and even kind of somewhat macroscopic distances

link |

because they're so small.

link |

So you can start looking at the inverse square law

link |

and say, start trying to measure it

link |

at shorter and shorter distances

link |

and see if there were extra dimensions

link |

at those distance scales,

link |

you would start to see the inverse square law fail.

link |

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

link |

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

link |

of this kind you can imagine which test

link |

for effects of extra dimensions

link |

at different distance scales, but none of them,

link |

I mean, they all just don't work.

link |

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

link |

much smaller, you can say that.

link |

Which by the way makes LIGO

link |

and the detection of gravitational waves

link |

quite an incredible project.

link |

Ed Witten is often brought up

link |

as one of the most brilliant mathematicians

link |

and physicists ever.

link |

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

link |

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

link |

I've had the pleasure of meeting him first

link |

when he was a postdoc.

link |

And I mean, he's just completely amazing

link |

mathematician and physicist.

link |

And he's quite a bit smarter

link |

than just about any of the rest of us

link |

and also more hardworking.

link |

It's a kind of frightening combination

link |

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

link |

But I would actually argue that his greatest work,

link |

the things that he's done that have been of

link |

just this mind blowing significance of giving us,

link |

I mean, he's completely revolutionized

link |

some areas of mathematics.

link |

He's totally revolutionized the way we understand

link |

the relations between mathematics and physics.

link |

And most of those, his greatest work

link |

is stuff that has little or nothing

link |

to do with string theory.

link |

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

link |

The very strange thing about him in some sense

link |

is that he doesn't have a Nobel Prize.

link |

So there's a very large number of people

link |

who are nowhere near as smart as he is

link |

and don't work anywhere near as hard

link |

who have Nobel Prizes.

link |

I think he just had the misfortune

link |

of coming into the field at a time

link |

when things had gotten much, much, much tougher

link |

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

link |

it was very hard to come up with a new idea

link |

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

link |

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

link |

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

link |

For mathematicians to give a Fields Medal

link |

to someone outside their field in physics

link |

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

link |

I don't think anybody would have thought

link |

that was even conceivable.

link |

So you're saying he came into the field

link |

of theoretical physics at a time when,

link |

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

link |

for purely theoretical work.

link |

The specific problem of trying to do better

link |

than the standard, the standard model

link |

is just this insanely successful thing,

link |

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

link |

And all of the people who kind of were involved

link |

in that coming together, many of them ended up

link |

with Nobel Prizes for that.

link |

But if you look post 1973, pretty much,

link |

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

link |

if you like, but if you look post 1973

link |

at what people have done to try to do better

link |

than the standard model and to get a better idea,

link |

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

link |

The theory's too good.

link |

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

link |

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

link |

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

link |

the kind of thing he's been trying to do

link |

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

link |

Is there something you can say about the standard model,

link |

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

link |

and yet people are striving to do more?

link |

Talking about unification, so on, why?

link |

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

link |

Why does it need to be improved?

link |

I mean, the thing that's gets most attention

link |

is gravity, that we have trouble.

link |

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

link |

about the gravitational force with it

link |

and have a unified quantum field theory

link |

that has gravitational interactions also.

link |

So that's the big problem everybody talks about.

link |

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

link |

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

link |

beautiful ideas, but there's certain aspects of it

link |

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

link |

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

link |

you have to throw in lots and lots of extra parameters

link |

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

link |

with the so called Higgs mechanism and the Higgs field,

link |

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

link |

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

link |

the rest of the theory is very, very constrained

link |

and has very, very few free parameters,

link |

really a very small number.

link |

There's very small number of parameters

link |

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

link |

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

link |

you need a Higgs field and you need to,

link |

it needs to do something.

link |

And once you introduce that Higgs field,

link |

all sorts of parameters make an appearance.

link |

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

link |

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

link |

and what's gonna happen.

link |

So you've gone from a very tightly constrained thing

link |

with a couple of parameters to this thing,

link |

which the minute you put it in,

link |

you had to add all this extra,

link |

all these extra parameters to make things work.

link |

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

link |

that's just the way the world is,

link |

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

link |

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

link |

and those numbers are just different in every universe.

link |

But another reasonable conjecture is just that,

link |

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

link |

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

link |

which would explain those numbers.

link |

And there's some kind of deeper idea

link |

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

link |

which we haven't figured out yet.

link |

And that's what we should look for.

link |

But to stick on string theory a little bit longer,

link |

could you play devil's advocate

link |

and try to argue for string theory,

link |

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

link |

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

link |

still should be a little flame that keeps burning?

link |

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

link |

for it is all sorts of new ideas about mathematics

link |

and about parts of physics really emerge from it.

link |

That was very a fruitful source of ideas.

link |

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

link |

which I kind of agree with,

link |

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

link |

say that this is just such a fruitful and inspiring idea

link |

and it's led to so many other different things

link |

coming out of it that there must be something

link |

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

link |

the strongest thing that they've got.

link |

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

link |

that could be neighboring to a theory

link |

that does unify everything, to a theory of everything.

link |

Like it could, it may not be exactly,

link |

exactly the theory, but sticking on it longer

link |

might get us closer to the theory of everything.

link |

Well, the problem with it now really

link |

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

link |

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

link |

with this nonperturbative theory.

link |

So it's become more and more frustrating

link |

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

link |

about string theory because it's become

link |

less and less well defined what it is.

link |

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

link |

whether you have this weird phenomenon

link |

of people calling themselves string theorists

link |

when they've never actually worked on any theory

link |

where there are any strings anywhere.

link |

So what has actually happened kind of sociologically

link |

is that you started out with this

link |

fairly well defined proposal.

link |

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

link |

people branched out in all sorts of directions

link |

doing all sorts of things.

link |

It became farther and farther removed from that.

link |

And for sociological reasons,

link |

the ones who kind of started out or now

link |

or were trained by the people who worked on that

link |

have now become this string theorists.

link |

And, but it's becoming almost more

link |

kind of a tribal denominator than a,

link |

I think so it's very hard to know

link |

what you're arguing about

link |

when you're arguing about string theory these days.

link |

Well, to push back on that a little bit,

link |

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

link |

It doesn't, like you could,

link |

like this is the way language evolves

link |

is it could start to represent something

link |

more than just the theory that involves strings.

link |

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

link |

At high dimensions with these super tiny objects, right?

link |

Or something like that.

link |

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

link |

So for example, neural networks

link |

in the space of machine learning,

link |

there was a time when they were extremely popular.

link |

They became much, much less popular

link |

to a point where if you mentioned neural networks,

link |

you're getting no funding

link |

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

link |

And then once again,

link |

neural networks became all the rage

link |

about 10, 15 years ago.

link |

And as it goes up and down

link |

and a lot of people would argue

link |

that using terminology like machine learning

link |

and deep learning is often misused over general,

link |

everything that works is deep learning,

link |

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

link |

That's just the way,

link |

again, we're back to sociological things,

link |

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

link |

if we leave the sociological mess aside,

link |

do we throw out the baby with the bathwater?

link |

Is there some, besides the side effects of nice ideas

link |

from the Ed Wittons of the world,

link |

is there some core truths there that we should stick by

link |

in the full beautiful mess of a space

link |

that we call string theory,

link |

that people call string theory?

link |

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

link |

that how what you call some field changes and evolves

link |

and in interesting ways as the field changes.

link |

But I mean, I guess what I would argue

link |

is the initial understanding of string theory

link |

that was quite specific,

link |

we're talking about a specific idea,

link |

10 dimensional super strings

link |

compactified to six dimensions.

link |

That to my mind, the really bad thing has happened

link |

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

link |

at least publicly, that that was a failure,

link |

that this really didn't work.

link |

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

link |

and they start doing more interesting things,

link |

but they keep talking to the public about string theory

link |

and referring back to that idea

link |

and using that as kind of the starting point

link |

and as kind of the place where the whole tribe starts

link |

and everything else comes from.

link |

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

link |

and what everything points back to,

link |

something which really didn't work out,

link |

it kind of makes everybody, it makes everything,

link |

you've created this potentially very, very interesting field

link |

with interesting things happening,

link |

but people in graduate school take courses

link |

on string theory and everything kind of,

link |

and this is what you tell the public

link |

in which you're continually pointing back.

link |

So you're continually pointing back to this idea

link |

which never worked out as your guiding inspiration.

link |

And it really kind of deforms your whole way

link |

of your hopes of making progress.

link |

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

link |

that's happened in this field.

link |

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

link |

about communicating the things that failed in the past.

link |

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

link |

that you're standing on.

link |

But again, those are sociological things.

link |

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

link |

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

link |

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

link |

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

link |

it was quite seductive in that you could see why Whitten

link |

and others got excited by it.

link |

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

link |

a few of these possible clobby owls that would work.

link |

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

link |

this very specific model and these very specific

link |

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

link |

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

link |

as people learned, worked more and more about it,

link |

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

link |

more and more things you can do with these six dimensions

link |

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

link |

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

link |

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

link |

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

link |

you can fit quantum mechanics, you can explain gravity,

link |

you can explain anything you want with it.

link |

Is that the basic failure mode?

link |

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

link |

ended up being kind of being essentially empty,

link |

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

link |

because it's consistent with just about anything.

link |

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

link |

with string theorists about this now, I mean,

link |

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

link |

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

link |

constraints coming out of this idea or not.

link |

Or maybe we live in a multiverse and everything is true

link |

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

link |

that string theorists have kind of react to this kind of

link |

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

link |

What about experimental validation?

link |

Is that a fair standard to hold before a theory

link |

of everything that's trying to unify

link |

quantum mechanics and gravity?

link |

Yeah, I mean, ultimately, to be really convinced

link |

that some new idea about unification really works,

link |

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

link |

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

link |

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

link |

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

link |

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

link |

like all those numbers that are,

link |

we don't know how to explain,

link |

it will show you how to calculate them.

link |

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

link |

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

link |

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

link |

not just string theory, for something that unifies

link |

gravity and quantum mechanics,

link |

so the very big and the very small?

link |

Is this, let me ask you one way,

link |

is it a physics problem, a math problem,

link |

or an engineering problem?

link |

My guess is it's a combination of a physics

link |

and a math problem that you really need.

link |

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

link |

of well defined thing you can write down

link |

and we just don't have enough computer power

link |

to do the calculation.

link |

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

link |

But the question is, what mathematical tools you need

link |

to properly formulate the problem is unclear.

link |

So one reasonable conjecture is the way,

link |

the reason that we haven't had any success yet

link |

is just that we're missing,

link |

either we're missing certain physical ideas

link |

or we're missing certain mathematical tools,

link |

which there are some combination of them,

link |

which we need to kind of properly formulate the problem

link |

and see that it has a solution

link |

that looks like the real world.

link |

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

link |

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

link |

like all the laws of physics to be operating

link |

on the same level.

link |

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

link |

or something like that in order to make predictions about.

link |

Otherwise, you're always making predictions

link |

about this joint phenomena or can you do that

link |

as long as the theory is consistent

link |

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

link |

Well, your theory should, I mean,

link |

if your theory is gonna include gravity,

link |

our current understanding of gravity

link |

is that you should have,

link |

there should be black hole states in it.

link |

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

link |

And just one aspect that people have concentrated a lot on

link |

is just this kind of questions about

link |

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

link |

and it includes quantum mechanics,

link |

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

link |

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

link |

quantum gravity work has been just those paradoxes.

link |

So stepping outside of string theory,

link |

can you just say first at a high level,

link |

what is the theory of everything?

link |

What is the theory of everything seek to accomplish?

link |

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

link |

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

link |

This is not gonna explain to you anything.

link |

It doesn't really, this kind of theory,

link |

this kind of theory of everything we're talking about

link |

doesn't say anything interesting,

link |

particularly about like macroscopic objects,

link |

about what the weather is gonna be tomorrow,

link |

or things are happening at this scale.

link |

But just what we've discovered is that

link |

as you look at the universe that kind of,

link |

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

link |

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

link |

quanta, if you like, and which are doing,

link |

which are interacting in some fairly simple way.

link |

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

link |

a theory that describes all the object,

link |

all the correct objects you need to describe

link |

what's happening in the world and describes how

link |

they're interacting with each other

link |

at our most fundamental level.

link |

How you get from that theory to describing some macroscopic,

link |

incredibly complicated thing is,

link |

there that becomes, again, more of an engineering problem

link |

and you may need machine learning,

link |

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

link |

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

link |

It's also science.

link |

One thing that I find kind of interesting

link |

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

link |

a little bit of hubris.

link |

Some of the most brilliant people I know are physicists,

link |

both philosophy and just in terms of mathematics,

link |

in terms of understanding the world.

link |

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

link |

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

link |

we will understand everything.

link |

Like this is the deepest thing to understand.

link |

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

link |

That's the old Rutherford thing.

link |

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

link |

There's layers to this thing

link |

and each one has a theory of everything.

link |

Like at every level from biology,

link |

like how life originates, that itself,

link |

like complex systems.

link |

Like that in itself is like this gigantic thing

link |

that requires a theory of everything.

link |

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

link |

psychology, like intelligence, collective intelligence,

link |

the way it emerges among species,

link |

that feels like a complex system

link |

that requires its own theory of everything.

link |

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

link |

artificial intelligence systems,

link |

like that feels like it needs a theory of everything.

link |

And it's almost like once we solve,

link |

once we come up with a theory of everything

link |

that explains the basic laws of physics

link |

that gave us the universe,

link |

even stuff that's super complex,

link |

like how the universe might be able to originate,

link |

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

link |

like multiverses or stuff

link |

that we don't have any evidence of yet.

link |

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

link |

of why food tastes delicious.

link |

No, anyway, yeah, I agree completely.

link |

I mean, there is something kind of completely wrong

link |

with this terminology of theory of everything.

link |

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

link |

very hubristic and bad terminology,

link |

because it's not, this is explaining,

link |

this is a purely kind of reductionist point of view

link |

that you're trying to understand

link |

a certain very specific kind of things,

link |

which in principle, other things emerge from,

link |

but to actually understand how anything emerges from this

link |

is, it can't be understood in terms of

link |

this underlying fundamental theory is gonna be hopeless

link |

in terms of kind of telling you what about this,

link |

this various emergent behavior.

link |

And as you go to different levels of explanation,

link |

you're gonna need to develop new,

link |

different, completely different ideas,

link |

completely different ways of thinking.

link |

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

link |

is that, you know, more is different.

link |

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

link |

what a couple of things,

link |

if you have a collection of stuff

link |

and you understand perfectly well

link |

how each thing is interacting with the others,

link |

what the whole thing is gonna do

link |

is just a completely different problem.

link |

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

link |

of thinking about it.

link |

What do you think about this?

link |

I got to ask you at a few different attempts

link |

that a theory of everything, especially recently.

link |

So I've been for many years,

link |

a big fan of cellular automata of complex systems.

link |

And obviously because of that,

link |

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

link |

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

link |

through his physics project, essentially.

link |

What do you think about this kind of discreet

link |

theory of everything like from simple rules

link |

and simple objects on the hypergraphs

link |

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

link |

Basically everything we see around us is emergent.

link |

Yeah, I have to say, unfortunately,

link |

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

link |

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

link |

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

link |

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

link |

with what I'm seeing,

link |

this kind of unification of math and physics

link |

that I'm kind of talking about around certain kinds

link |

of very deep ideas about geometry and stuff.

link |

This, if you want to believe that your things

link |

are really coming out of cellular automata

link |

at the most fundamental level,

link |

you have to believe that everything that I've seen

link |

my whole career and as beautiful, powerful ideas,

link |

that that's all just kind of a mirage,

link |

which just kind of randomly is emerging

link |

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

link |

And you have to give me some serious evidence for that

link |

and I'm seeing nothing.

link |

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

link |

where things like quantum mechanics could emerge

link |

from much, much, much smaller, discreet,

link |

like computational type systems.

link |

I think from the point of view of certain mathematical

link |

point of view, quantum mechanics is already mathematically

link |

as simple as it gets.

link |

It really is a story about really the fundamental objects

link |

that you work within when you write down a quantum theory

link |

are in some form point of view,

link |

precisely the fundamental objects

link |

at these deepest levels of mathematics

link |

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

link |

So, and cellular automata are something completely different

link |

which don't fit into these structures.

link |

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

link |

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

link |

And then just looking at it and saying,

link |

does this go anywhere?

link |

Does this solve any problem that I've ever,

link |

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

link |

I just don't see it.

link |

Yeah, to me, cellular automata and these hypergraphs,

link |

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

link |

to apply here at this moment.

link |

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

link |

have no good answers.

link |

So there's not good math explaining,

link |

forget the physics of it,

link |

math explaining the behavior of complex systems.

link |

And that to me is both exciting and paralyzing.

link |

Like we're at the very early days of understanding

link |

how complicated and fascinating things emerge

link |

from simple rules.

link |

Yeah, and I agree.

link |

I think that is a truly great problem.

link |

And depending where it goes, it may be,

link |

it may start to develop some kind of connections

link |

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

link |

It just, I think a lot of that area,

link |

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

link |

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

link |

And again, we're back to this original problem

link |

that your time in life is limited.

link |

You have to figure out what you're gonna spend

link |

your time thinking about.

link |

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

link |

to convince me to spend more time thinking about.

link |

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

link |

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

link |

There's some aspect to cellular automata,

link |

these kinds of objects that it feels like

link |

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

link |

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

link |

that are solvable today.

link |

In fact, my intuition, again, perhaps biased,

link |

is it feels like the kind of systems that,

link |

complex systems that cellular automata are,

link |

would not be solved by human brains.

link |

It feels like something post human

link |

that will solve that problem.

link |

Or like significantly enhanced humans,

link |

meaning like using computational tools,

link |

very powerful computational tools to crack

link |

these problems open.

link |

That's if our approach to science,

link |

our ability to understand science, our ability

link |

to understand physics will become more and more

link |

computational, or there'll be a whole field

link |

that's computational in nature,

link |

which currently is not the case.

link |

Currently, computation is the thing that sort of assists us

link |

in understanding science the way we've been doing it

link |

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

link |

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

link |

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

link |

if computers could do science on their own,

link |

computational systems, perhaps that's the way

link |

they would do the science.

link |

They would try to understand the cellular automata,

link |

and that feels like we're decades away.

link |

So perhaps it'll crack open some interesting facets

link |

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

link |

So timing is everything.

link |

That's perfectly possible, yeah.

link |

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

link |

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

link |

Oh, quite well, yeah.

link |

What are your thoughts about his geometric community

link |

and the space of ideas that he's playing with

link |

in his proposal for theory of everything?

link |

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

link |

I think, the same problems that everybody has had

link |

trying to do this, and there are really versions

link |

of the same problem that you try to get unity

link |

by putting everything into some bigger structure.

link |

So he has some other ones that are not so conventional

link |

that he's trying to work with,

link |

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

link |

if he can get a lot farther in terms of having

link |

a really well defined, well understood,

link |

clear picture of these things he's working with,

link |

they're really kind of large geometrical structures

link |

of many dimensions of many kinds,

link |

and I just don't see any way,

link |

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

link |

how do you get back down to the structures

link |

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

link |

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

link |

and there's another interesting example

link |

of a similar kind of thing is Garrett Leasy's

link |

theory of everything.

link |

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

link |

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

link |

but it, again, I think all these things found

link |

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

link |

you know, you create this unity,

link |

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

link |

how you're gonna get back to the actual,

link |

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

link |

you create these big symmetries,

link |

how are you gonna break them?

link |

And, because we don't see those symmetries

link |

in the real world, and so ultimately,

link |

there would need to be a simple process

link |

for collapsing it to four dimensions.

link |

You'd have to explain, well, yeah,

link |

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

link |

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

link |

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

link |

dimensional groups of symmetries,

link |

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

link |

and this has been a problem since the beginning,

link |

almost immediately after 1973, about a year later,

link |

two years later, people started talking about

link |

grand unified theories, so you take the U1,

link |

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

link |

into this bigger structure called SU5 or SO10,

link |

but then you're stuck with this problem that,

link |

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

link |

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

link |

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

link |

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

link |

and lots of people who try to do it,

link |

they all kind of found her in that same way,

link |

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

link |

Are there lessons, ideas to be learned from theories

link |

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

link |

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

link |

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

link |

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

link |

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

link |

again, we're back to the problem

link |

of a limited amount of time in life.

link |

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

link |

Why don't more physicists look at it?

link |

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

link |

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

link |

and I've worked in the space of AI,

link |

and so there's a lot of people,

link |

perhaps AI is even way more accessible than physics,

link |

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

link |

with different theories about what they have

link |

for how to create general intelligence,

link |

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

link |

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

link |

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

link |

but I wonder if there's ideas out there

link |

that are still powerful, that are still fascinating,

link |

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

link |

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

link |

of academic research.

link |

Yeah, well, I mean, the same thing,

link |

and pretty much every day in my email,

link |

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

link |

about why all of what physicists are doing,

link |

and perhaps the most disturbing thing I should say

link |

about being a critic of string theory

link |

is that when you realize who your fans are,

link |

every day I hear from somebody who says,

link |

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

link |

you must, of course, agree with me

link |

that this is the right way to think about everything.

link |

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

link |

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

link |

and doesn't know what they're doing,

link |

but there's a whole continuum to,

link |

people who are quite serious physicists and mathematicians

link |

who are making a fairly serious attempt

link |

to try to do something, like Eric and Eric,

link |

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

link |

looking at it and trying to figure out

link |

what they're really doing,

link |

but then at some point you just realize,

link |

wait a minute, for me to really, really understand

link |

exactly what's going on here would just take time

link |

I just don't have.

link |

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

link |

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

link |

if your idea is good, that should quite naturally lead

link |

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

link |

So you don't need to get approval from somebody

link |

that's saying you have a good idea here.

link |

You can just utilize that idea in an engineer system,

link |

like naturally leads to engineering.

link |

With physics here, if you have a perfect theory

link |

that explains everything, that still doesn't obviously lead

link |

one, to scientific experiments that can validate

link |

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

link |

and sell at a store for $5.

link |

You can't make money off of it.

link |

So that makes it much more challenging.

link |

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

link |

especially recently appealing,

link |

which is Roger Penrose's Twister theory.

link |

What kind of questions might it allow us to answer?

link |

What will the answers look like?

link |

It's only in the last couple of years

link |

that I really, really kind of come to really,

link |

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

link |

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

link |

And I've gotten very excited about that

link |

the last year or two.

link |

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

link |

is that it's a different way of thinking about

link |

what space and time are and about what points

link |

in space and time are, which is very interesting

link |

that it only really works in four dimensions.

link |

So four dimensions behaves very, very specially

link |

unlike other dimensions.

link |

And in four dimensions, there is a way of thinking

link |

about space and time geometry,

link |

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

link |

You can also think about different objects,

link |

these so called twisters.

link |

And then when you do that,

link |

you end up with a kind of a really interesting insight

link |

that you can formulate a theory,

link |

and you can formulate a very,

link |

take a standard theory that we formulate

link |

in terms of points of space and time,

link |

and you can reformulate in this Twister language.

link |

And in this Twister language,

link |

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

link |

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

link |

So maybe one way to say it,

link |

which actually I think is really, is quite amazing.

link |

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

link |

We have this idea that the world out there

link |

is all these different points and these points of time.

link |

Well, that's kind of a derived quantity.

link |

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

link |

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

link |

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

link |

And what Penrose says is that,

link |

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

link |

that sphere of all the light rays coming in.

link |

And he says, and you should formulate your,

link |

instead of thinking about points,

link |

you should think about the space of those spheres,

link |

if you like, and formulate the degrees of freedom

link |

as physics as living on those spheres, living on,

link |

so you're kind of living on,

link |

your degrees of freedom are living on light rays,

link |

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

link |

And he and others working with him developed

link |

a beautiful mathematical formulas

link |

and a way to go back from forth between some aspects

link |

of our standard way we write these things down

link |

and work in the so called twister space.

link |

And certain things worked out very well,

link |

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

link |

that they weren't a little bit like string theory

link |

that they, by using these ideas about twisters,

link |

they could develop them in different directions

link |

and find all sorts of other interesting things,

link |

but they were getting,

link |

they weren't finding any way of doing that

link |

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

link |

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

link |

is what I think I have an idea about

link |

that I think does actually work,

link |

that goes more in that direction.

link |

And I can go on about that endlessly

link |

or talk a little bit about it,

link |

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

link |

to explain insight about twister theory.

link |

There are some more technical ones.

link |

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

link |

what it tells you about spinners, for instance,

link |

but that's a more technical.

link |

Well, first let's like linger on the spheres

link |

and the light cones.

link |

You're saying twisted theory allows you to make

link |

that the fundamental object with which you're operating.

link |

How that, I mean, first of all,

link |

like philosophically that's weird and beautiful,

link |

maybe because it maps,

link |

it feels like it moves us so much closer

link |

to the way human brains perceive reality.

link |

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

link |

of our perception is the fundamental object of reality.

link |

That's very appealing.

link |

Is it mathematically powerful?

link |

Is there something you can say,

link |

can you say a little bit more about what the heck

link |

that even means for,

link |

because it's much easier to think about mathematically

link |

like a point in space time.

link |

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

link |

It uses a kind of mathematics that's relative,

link |

that kind of goes back to the 19th century

link |

among mathematicians.

link |

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

link |

but one problem is that you have to start,

link |

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

link |

and not just real numbers.

link |

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

link |

for mathematicians, that's fine.

link |

We love doing that.

link |

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

link |

I think perhaps the most,

link |

the way that there is something you can say

link |

very specifically about it in terms of spinners,

link |

which I don't know if you want to,

link |

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

link |

What are spinners?

link |

Let's start with spinners,

link |

because I think that if we can introduce that,

link |

then I can say it.

link |

By the way, twister is spelled with an O

link |

and spinner is spelled with an O as well.

link |

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

link |

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

link |

I don't know what is a good starting point

link |

for twister theory.

link |

Well, one thing you say about Penrose,

link |

I mean, Penrose is actually a very good writer

link |

and also a very good draftsman.

link |

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

link |

he actually has done some very nice drawings.

link |

So, I mean, almost any kind of expository thing

link |

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

link |

He's a remarkable person.

link |

But the, so spinners are something

link |

that independently came out of mathematics

link |

and out of physics.

link |

And to say where they came out of physics,

link |

I mean, what people realized when they started looking

link |

at elementary particles like electrons or whatever,

link |

that there seem to be some kind of doubling

link |

of the degrees of freedom going on.

link |

If you counted what was there in some sense

link |

in the way you would expect it

link |

and when you started doing quantum mechanics

link |

and started looking at elementary particles,

link |

there were seen to be two degrees of freedom,

link |

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

link |

in a strong magnetic field and asked what was the energy

link |

of it, instead of it having one energy,

link |

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

link |

And as you increase magnetic field,

link |

the splitting would increase.

link |

So physicists kind of realized that, wait a minute.

link |

So we thought when we were doing,

link |

first started doing quantum mechanics,

link |

that the way to describe particles was in terms

link |

of wave functions and these wave functions

link |

were complex to complex values.

link |

Well, if we actually look at particles,

link |

that that's not right.

link |

They're pairs of complex numbers.

link |

They're pairs of complex numbers.

link |

So one of the kind of fundamental,

link |

from the physics point of view,

link |

the fundamental question is why are all our kind

link |

of fundamental particles described

link |

by pairs of complex numbers?

link |

And then you can ask, well, what happens

link |

if you like take an electron and rotate it?

link |

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

link |

Well, now, if you go back to mathematics,

link |

what had been understood in mathematics,

link |

some years earlier, not that many years earlier,

link |

was that if you ask very, very generally,

link |

think about geometry of three dimensions and ask,

link |

and if you think about things that are happening

link |

in three dimensions in the standard way,

link |

everything, the standard way of doing geometry,

link |

everything is about vectors, right?

link |

So if you've taken any mathematics classes,

link |

you probably see vectors at some point.

link |

They're just triplets of numbers tell you

link |

what a direction is or how far you're going

link |

in three dimensional space.

link |

And most of everything we teach in most standard courses

link |

in mathematics is about vectors

link |

and things you build out of vectors.

link |

So you express everything about geometry

link |

in terms of vectors or how they're changing

link |

or how you put two of them together

link |

and get planes and whatever.

link |

But what had been realized that,

link |

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

link |

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

link |

that you can kind of consistently think about rotating?

link |

And so you ask a technical question,

link |

what are the representations of the rotation group?

link |

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

link |

and everything you build out of vectors,

link |

but then people found, but wait a minute,

link |

there's also these other things,

link |

which you can build out of vectors,

link |

but which you can consistently rotate.

link |

And they're described by pairs of complex numbers,

link |

by two complex numbers.

link |

And they're the spinners also.

link |

And to make a lot, and to make,

link |

and you can think of spinners in some sense

link |

as more fundamental than vectors

link |

because you can build vectors out of spinners.

link |

You can take two spinners and make a vector,

link |

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

link |

you can't get spinners.

link |

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

link |

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

link |

which was kind of spinner geometry.

link |

And this is something which even to this day,

link |

when we teach graduate courses in geometry,

link |

we mostly don't talk about this

link |

because it's a bit hard to do correctly.

link |

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

link |

describing things in terms of spinners

link |

is a whole different ball game.

link |

But anyway, it was just this amazing fact

link |

that this kind of more fundamental piece of geometry,

link |

spinners, and what we were actually seeing,

link |

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

link |

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

link |

but it's very counterintuitive.

link |

What are some weird properties of spinners

link |

that are counterintuitive?

link |

That there are some things that they do,

link |

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

link |

it doesn't come back towards,

link |

it becomes minus what it was.

link |

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

link |

there's a kind of a funny sign

link |

you have to keep track of in some sense.

link |

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

link |

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

link |

if you're used to visualizing vectors,

link |

you just, there's nothing you can do

link |

visualizing in terms of vectors

link |

that will ever give you a spinner.

link |

It just is not gonna ever work.

link |

As you were saying that I was visualizing a vector

link |

walking along a Mobius strip,

link |

and it ends up being upside down.

link |

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

link |

So, I mean, what really captures it?

link |

The problem is that it's really,

link |

the simplest way to describe it

link |

is in terms of two complex numbers.

link |

And your problem with two complex numbers

link |

is that's four real numbers.

link |

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

link |

So you, that makes it hard to visualize.

link |

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

link |

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

link |

You're really gonna use the fact that

link |

these are two complex numbers.

link |

So it's very hard to visualize.

link |

But to get back to what I think is mind blowing

link |

about twisters is that the,

link |

another way of saying this idea about talking about spheres,

link |

another way of saying the fundamental idea of twister theory

link |

is in some sense, the fundamental idea of twister theory

link |

is that a point is a two complex dimensional space.

link |

So that every, and that it lives inside,

link |

the space that it lies inside is twister space.

link |

So in the simplest case, it's four,

link |

twister space is four dimensional

link |

and a point in space time

link |

is a two complex dimensional subspace

link |

of all the four complex dimensions.

link |

And as you move around in space time,

link |

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

link |

And that, but then the.

link |

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

link |

So it's two complex dimensions in four complex.

link |

But then to me, the mind blowing thing about this

link |

is this then kind of tautologically answers the question

link |

is what is a spinner?

link |

Well, a spinner is a point.

link |

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

link |

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

link |

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

link |

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

link |

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

link |

of what a point in space time was

link |

just told you what a spinner was.

link |

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

link |

Yeah, but we're trying to project that

link |

into a three dimensional space

link |

and trying to intuit, but you can't.

link |

Yeah, so the intuition becomes very difficult,

link |

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

link |

you have to kind of go through a certain

link |

fairly complicated rigmarole to even describe spinners

link |

to describe electrons.

link |

Whereas using twister theory,

link |

it's just completely tautological.

link |

They're just what you want to describe.

link |

The electron is fundamentally the way

link |

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

link |

It's just there, so.

link |

Do you have a hope?

link |

You mentioned that you found it appealing recently.

link |

Is it just because of certain aspects

link |

of its mathematical beauty,

link |

or do you actually have a hope

link |

that this might lead to a theory of everything?

link |

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

link |

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

link |

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

link |

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

link |

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

link |

in your quantum theory?

link |

And so there's another long story

link |

about how we do quantum theories

link |

and about how we treat time in quantum theories,

link |

which is a long story.

link |

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

link |

when you try and write down a quantum theory,

link |

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

link |

whatever you're using to your time coordinate,

link |

and multiply it by the square root of minus one

link |

and to make it purely imaginary.

link |

And so all these formulas,

link |

which you have in your standard theory,

link |

if you do that to those,

link |

I mean, those formulas have some very strange behavior

link |

and they're kind of singular.

link |

If you ask even some simple questions,

link |

you have to take very delicate singular limits

link |

in order to get the correct answer,

link |

and you have to take them from the right direction,

link |

otherwise it doesn't work.

link |

Whereas if you just take time,

link |

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

link |

wherever you see the time coordinate,

link |

you end up with much simpler formulas,

link |

which are much better behaved mathematically.

link |

And what I hadn't really appreciated until fairly recently

link |

is also how dramatically that changes

link |

the whole structure of the theory.

link |

You end up with a consistent way of talking

link |

about these quantum theories,

link |

but it has some very different flavor

link |

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

link |

And in particular, the way symmetries act on it

link |

is not at all what I originally had expected.

link |

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

link |

or I think gives you something,

link |

is to do this move,

link |

which people often think of as just kind of a mathematical

link |

trick that you're doing

link |

to make some formulas work out nicely,

link |

but to take that mathematical trick as really fundamental.

link |

And it turns out in Twister theory

link |

allows you to simultaneously talk about your usual time

link |

and the time times the square root of minus one,

link |

they both fit very nicely into Twister theory.

link |

And you end up with some structures

link |

which look a lot like the standard models.

link |

Well, let me ask you about some Nobel prizes.

link |

Do you think there will be,

link |

there was a bet between Michio Kaku

link |

and somebody else about.

link |

John Horgan about,

link |

by the way, maybe discover a cool website,

link |

longbets.com or.org.

link |

Better, yeah, yeah.

link |

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

link |

and then check in 20 years later.

link |

There's a lot of interesting bets on there.

link |

I would love to participate,

link |

but it's interesting to see,

link |

time flies and you make a bet about

link |

what's going to happen in 20 years.

link |

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

link |

And then you get to face out

link |

and you get to wonder what was that person?

link |

What was I thinking?

link |

That person 20 years ago

link |

was almost like a different person.

link |

What was I thinking back then to think that?

link |

So let me ask you this on record,

link |

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

link |

do you think there will be a Nobel Prize given

link |

for something directly connected

link |

to a first broadly theory of everything?

link |

And second, of course, one of the possibilities,

link |

one of them, string theory?

link |

String theory, definitely not.

link |

Things have gone, yeah.

link |

So if you were giving financial advice,

link |

you would say not to bet on that?

link |

And even, I actually suspect

link |

if you ask string theorists that question,

link |

you're gonna get a few of them saying,

link |

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

link |

again, when Kaku was making this bet or whatever,

link |

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

link |

And certainly back in 1984,

link |

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

link |

But now I get the impression that

link |

even they realize that things are not looking good

link |

for that particular idea.

link |

Again, it depends what you mean by string theory,

link |

whether maybe the term will evolve to mean something else,

link |

which will work out.

link |

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

link |

whether something else.

link |

I mean, I still think it's relatively unlikely

link |

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

link |

And the main problem is just the,

link |

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

link |

that we've really lost this ability

link |

to kind of get unexpected input from experiment.

link |

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

link |

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

link |

looking at high energy particle,

link |

high energy colliders and their technology,

link |

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

link |

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

link |

And I think actually, I would actually claim that

link |

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

link |

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

link |

you're gonna have a lot more data,

link |

an order of magnitude or more data from the LHC,

link |

but at the same energy.

link |

You're not gonna see a higher energy accelerator

link |

operating successfully in the next 20 years.

link |

And like maybe machine learning

link |

or great sort of data science methodologies

link |

that process that data will not reveal

link |

any major shifts in our understanding

link |

of the underlying physics, you think?

link |

I mean, I think that field, my understanding

link |

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

link |

but it seems to look like it will help them

link |

solve certain technical problems

link |

and be able to do things somewhat better,

link |

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

link |

What do you think about the potential quantum computers

link |

simulating quantum mechanical systems

link |

and through that sneak up to sort of through simulation,

link |

sneak up to a deep understanding of the fundamental physics?

link |

The problem there is that that's promising more

link |

for this, for Phil Anderson's problem,

link |

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

link |

you start putting together lots and lots of things

link |

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

link |

but what this thing is gonna do,

link |

we don't have any good calculational techniques.

link |

Quantum computers may very well give you those.

link |

And so they may, what we think of

link |

is kind of a strong coupling behavior.

link |

We have no good way to calculate.

link |

Even though we can write down the theory,

link |

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

link |

and the quantum computer may solve that problem.

link |

But the problem is that I don't think

link |

that they're gonna solve the problem

link |

that they help you with the problem

link |

of not having the, of knowing

link |

what the right underlying theory is.

link |

As somebody who likes experimental validation,

link |

let me ask you the perhaps ridiculous sounding,

link |

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

link |

of do you think we live in a simulation?

link |

Do you find that thought experiment

link |

at all useful or interesting?

link |

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

link |

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

link |

to any kind of interesting, lead anywhere interesting.

link |

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

link |

To me, it's super interesting

link |

from an engineering perspective.

link |

So if you look at virtual reality systems,

link |

the actual question is how much computation

link |

and how difficult is it to construct a world

link |

that like there are several levels here.

link |

One is you won't know the difference,

link |

our human perception systems

link |

and maybe even the tools of physics

link |

won't know the difference

link |

between the simulated world and the real world.

link |

That's sort of more of a physics question.

link |

The most interesting question to me

link |

has more to do with why food tastes delicious,

link |

which is create how difficult

link |

and how much computation is required

link |

to construct a simulation

link |

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

link |

but you want to stay there anyway.

link |

And over time, you don't even remember.

link |

Yeah, well, anyway, I agree,

link |

these are kind of fascinating questions

link |

and they may be very, very relevant

link |

to our future as a species,

link |

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

link |

Well, so from a physics perspective,

link |

it's not useful to you to think,

link |

taking a computational perspective to our universe,

link |

thinking of it as an information processing system

link |

and then they give it as doing computation

link |

and then you think about the resources required

link |

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

link |

You could just look at the basic physics

link |

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

link |

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

link |

I mean, I'm willing to agree

link |

that you can get into interesting kinds of questions

link |

going down that road,

link |

but they're just so different from anything

link |

from what I've found interesting and I just,

link |

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

link |

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

link |

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

link |

What about space itself?

link |

So I have to ask you about aliens.

link |

Again, something, since you emphasize evidence,

link |

do you think there is, how many,

link |

do you think there are and how many

link |

intelligent alien civilizations are out there?

link |

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

link |

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

link |

or something, we haven't heard from,

link |

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

link |

but there seems to be no,

link |

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

link |

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

link |

about the physics of reality.

link |

When you look up to the stars,

link |

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

link |

Yes, yeah, well, actually,

link |

I originally got interested in physics.

link |

I actually started out as a kid interested in astronomy,

link |

exactly that, and a telescope and whatever that,

link |

and certainly read a lot of science fiction

link |

and thought about that.

link |

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

link |

anyway, less and less interested in that one,

link |

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

link |

I also kind of, at some point,

link |

kind of stopped reading science fiction that much,

link |

kind of feeling that there was just too,

link |

that the actual science I was kind of learning about

link |

was perfectly kind of weird and fascinating,

link |

and unusual enough, and better than any of the stuff

link |

that Isaac Asimov, so why should I?

link |

Yeah, and you can mess with the science

link |

much more than the distant science fiction,

link |

the one that exists in our imagination

link |

or the one that exists out there among the stars.

link |

Well, you mentioned science fiction.

link |

You've written quite a few book reviews.

link |

I gotta ask you about some books, perhaps,

link |

if you don't mind.

link |

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

link |

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

link |

Either negative recommendations or positive recommendations.

link |

Do not read this book for sure.

link |

Well, I must say, I mean, unfortunately,

link |

yeah, you can go to my website

link |

and you can click on book reviews

link |

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

link |

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

link |

about string theory, I'm not a fan

link |

of a lot of the kind of popular books

link |

about, oh, isn't string theory great?

link |

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

link |

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

link |

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

link |

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

link |

sort of Cosmos style communication of concepts

link |

to people that are outside of physics,

link |

outside of mathematics, outside of even the sciences

link |

and helping people to sort of dream

link |

and fill them with awe about the full range

link |

of mysteries in our universe?

link |

That's a complicated issue.

link |

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

link |

and go back to like what inspired me

link |

and maybe to connect it a little bit

link |

to this question about books.

link |

I mean, certainly when the books,

link |

some books that I remember reading when I was a kid

link |

were about the early history of quantum mechanics,

link |

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

link |

kind of looking back at telling the history

link |

of what happened when he developed quantum mechanics.

link |

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

link |

great story, and those were very inspirational to me.

link |

And I would think maybe other people

link |

might also find them that, but the...

link |

And that's almost like the human story

link |

of the development of the ideas.

link |

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

link |

there are these very, very weird ideas

link |

that didn't seem to make sense,

link |

and how they were struggling with them

link |

and how, you know, they actually...

link |

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

link |

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

link |

and ending up with the war

link |

when these things get used to, you know,

link |

make massively destructive weapons.

link |

It's just the truly amazing...

link |

And so many, so many new ideas.

link |

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

link |

on top of a tangent, ask,

link |

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

link |

Is it the lone geniuses?

link |

Or is it some kind of weird network of ideas

link |

swimming in the air and just kind of the geniuses

link |

pop up to catch them and others would anyway?

link |

Without Einstein, would we have special relativity,

link |

general relativity?

link |

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

link |

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

link |

I mean, there are other people.

link |

Anyway, you could even argue that it was already there

link |

in some form in some ways,

link |

but I think special relativity you would have had

link |

without Einstein fairly quickly.

link |

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

link |

and required a much more effort, much more sophisticated.

link |

That I think you would have had sooner or later,

link |

but it would have taken quite a bit longer.

link |

That took a bunch of years to validate scientifically,

link |

the general relativity.

link |

But even for Einstein, from the point where he had

link |

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

link |

to the point where he actually had a well defined theory

link |

that you could actually compare to the real world,

link |

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

link |

10 years of very serious work.

link |

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

link |

it would have taken a while before anyone else

link |

On the other hand, there are things like,

link |

with quantum mechanics, you have Heisenberg and Schrodinger

link |

came up with two, which ultimately equivalent,

link |

but two different approaches to it

link |

within months of each other.

link |

And so if Heisenberg hadn't been there,

link |

you already would have had Schrodinger or whatever.

link |

And if neither of them had been there,

link |

it would have been somebody else a few months later.

link |

So there are times when the, just the,

link |

a lot often is the combination of the right ideas

link |

are in place and the right experimental data is in place

link |

to point in the right direction.

link |

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

link |

Maybe to go back to your aliens,

link |

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

link |

would they have the same fundamental physics ideas

link |

as we have in mathematics?

link |

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

link |

how much is this really intrinsic to our minds?

link |

If you start out with a different kind of mind

link |

when you end up with a different ideas

link |

of what fundamental physics is

link |

or what the structure of mathematics is.

link |

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

link |

I like video games, the way I would do it

link |

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

link |

is run Earth over many thousands of times

link |

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

link |

I wouldn't do the full evolution.

link |

I would start at Homo sapiens first

link |

and then see the evolution of Homo sapiens

link |

millions of times and see how the ideas

link |

of science would evolve.

link |

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

link |

How would math evolves?

link |

I would particularly just be curious

link |

about the notation they come up with.

link |

Every once in a while I would like throw miracles

link |

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

link |

And then I would also like to run Earth

link |

from the very beginning to see if evolution

link |

will produce different kinds of brains

link |

that would then produce different kinds

link |

of mathematics and physics.

link |

And then finally, I would probably millions of times

link |

run the universe over to see what kind of,

link |

what kind of environments and what kind of life

link |

would be created to then lead to intelligent life,

link |

to then lead to theories of mathematics and physics

link |

and to see the full range.

link |

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

link |

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

link |

to come up with calculus.

link |

I would just like keep noting how long it took

link |

and get an average and see which ideas are difficult,

link |

which are not and then conclusively sort of figure out

link |

if it's more collective intelligence

link |

or singular intelligence that's responsible for shifts

link |

and for big phase shifts and breakthroughs in science.

link |

If I was playing a video game and ran,

link |

I got a chance to run this whole thing.

link |

Yeah, but we're talking about books

link |

before I distracted us horribly.

link |

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

link |

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

link |

is the books about the, from the original people,

link |

especially Heisenberg about the, how that happened.

link |

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

link |

of the kind of what happened during this 20th century

link |

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

link |

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

link |

That's one of the best ones.

link |

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

link |

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

link |

The problem is that there just hasn't been much

link |

that's actually worked out since then.

link |

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

link |

about all the glorious things that have happened

link |

since 1973 are, they're mostly telling you

link |

about how glorious things are,

link |

which actually don't really work.

link |

And it's really, the argument people sometimes make

link |

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

link |

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

link |

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

link |

something that's not really quite working.

link |

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

link |

The other argument is, wait a minute,

link |

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

link |

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

link |

the whole scientific enterprise in a not really good way.

link |

So there's this problem.

link |

So my general feeling about expository stuff is, yeah,

link |

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

link |

and, well, that's great.

link |

There are a lot of people doing that now,

link |

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

link |

excited and enthusiastic by kind of telling them stuff,

link |

which isn't really true,

link |

you really shouldn't be doing that.

link |

You obviously have a much better intuition about physics.

link |

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

link |

you could use certain kinds of language,

link |

like calling things intelligent

link |

that could rub people the wrong way.

link |

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

link |

saying that a program can learn its way

link |

without any human supervision as AlphaZero does

link |

To me, that may not be intelligence,

link |

but it sure as heck seems like a few steps

link |

down the path towards intelligence.

link |

And so I think that's a very peculiar property

link |

of systems that can be engineered.

link |

So even if the idea is fuzzy,

link |

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

link |

or if you don't have a deep fundamental understanding

link |

or even a model what intelligence is,

link |

if you build a system that sure as heck is impressive

link |

and showing some of the signs

link |

of what previously thought impossible

link |

for a nonintelligent system,

link |

then that's impressive and that's inspiring

link |

and that's okay to celebrate.

link |

In physics, because you're not engineering anything,

link |

you're just now swimming in the space,

link |

directly when you do theoretical physics,

link |

that it could be more dangerous.

link |

You could be out too far away from shore.

link |

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

link |

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

link |

or really understand how that this particular kind

link |

of physics has gotten itself into a really unusual

link |

and strange and historically unusual state,

link |

which is not really.

link |

I mean, I spent half my life among mathematicians

link |

and half of the physicists,

link |

and mathematics is kind of doing fine.

link |

People are making progress

link |

and it has all the usual problems,

link |

but also, so you could have a,

link |

but I just, I don't know,

link |

I've never seen anything at all happening in mathematics

link |

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

link |

It's just the kind of sociology of this,

link |

the way this field works banging up

link |

against this harder problem without anything

link |

from experiment to help it.

link |

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

link |

of problematic things.

link |

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

link |

or to slightly misrepresent,

link |

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

link |

but it's another thing to start promoting to people

link |

as a success as ideas, which really completely failed.

link |

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

link |

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

link |

for instance, coming on certain podcasts like yours,

link |

telling the world, this is a huge success

link |

and this is really wonderful.

link |

And it's just not true.

link |

And this is really problematic

link |

and it carries a serious danger of once,

link |

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

link |

that the loss of credibility of science

link |

is a real, real problem for our society.

link |

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

link |

to think that what they're being told

link |

by kind of some of the best institutions

link |

or a country or authorities is not true.

link |

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

link |

That's obviously characteristic of not just physics,

link |

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

link |

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

link |

even when you don't have any proof

link |

that those ideas actually work in the US

link |

because if they've worked in that,

link |

that seems to be the case throughout history.

link |

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

link |

against a really hard problem.

link |

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

link |

through the progress of physics

link |

that we're dealing with now

link |

or it's just a natural progress of science.

link |

You run up against a really difficult stage of a field

link |

and different people behave differently in the face of that.

link |

Some sell books and sort of tell narratives

link |

that are beautiful and so on.

link |

They're not necessarily grounded in solutions

link |

that have proven themselves.

link |

Others kind of put their head down quietly,

link |

keep doing the work.

link |

Others sort of pivot to different fields

link |

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

link |

And then you have fields like machine learning,

link |

which there was a few folks mostly scattered away

link |

from machine learning in the 90s,

link |

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

link |

But a few people kept their head down

link |

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

link |

And they didn't think of it that way.

link |

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

link |

they'll just probably keep working on it anyway,

link |

sort of like loyal ants sticking to a particular thing.

link |

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

link |

that we should be careful over hyping things

link |

that have not proven themselves

link |

because people will lose trust in the scientific process.

link |

But unfortunately, there's been other ways

link |

in which people have lost trust in the scientific process.

link |

That ultimately has to do actually

link |

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

link |

which is not being honest and transparent

link |

about the flaws of mistakes of the past.

link |

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

link |

But this particular field is kind of fun.

link |

It's always a strange one.

link |

I mean, I think in the sense that

link |

there's a lot of public fascination with it

link |

that it seems to speak to kind of our deepest questions

link |

about what is this physical reality?

link |

Where do we come from?

link |

And these kind of deep issues.

link |

So there's this unusual fascination with it.

link |

Mathematics is very different.

link |

Nobody's that interested in mathematics.

link |

Nobody really kind of expects to learn really great,

link |

deep things about the world from mathematics that much.

link |

They don't ask mathematicians that.

link |

So it's a very unusual,

link |

it draws this kind of unusual amount of attention.

link |

And it really is historically in a really unusual state.

link |

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

link |

in a way which it's hard to find

link |

other historical parallels to.

link |

But sort of to push back a little bit,

link |

there's power to inspiring people.

link |

And if I just empirically look,

link |

physicists are really good at combining science

link |

and philosophy and communicating it.

link |

Like there's something about physics often

link |

that forces you to build a strong intuition

link |

about the way reality works, right?

link |

And that allows you to think through sort of

link |

and communicate about all kinds of questions.

link |

Like if you see physicists,

link |

it's always fascinating to take on problems

link |

that have nothing to do with their particular discipline.

link |

They think in interesting ways

link |

and they're able to communicate

link |

their thinking in interesting ways.

link |

And so in some sense, they have a responsibility

link |

not just to do science, but to inspire.

link |

And not responsibility, but the opportunity.

link |

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

link |

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

link |

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

link |

with different degrees of success and whatever.

link |

I guess one thing, but I mean,

link |

what's kind of front and center for me

link |

is kind of a more parochial interest

link |

is just kind of what damage do you do

link |

to the subject itself, ignoring,

link |

okay, misrepresenting what high school students think

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about string theory and that doesn't matter much,

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but what the smartest undergraduates

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or the smartest graduate students in the world think about it

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and what paths you're leading them down

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and what story you're telling them

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and what textbooks you're making them read

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and what they're hearing.

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And so a lot of what's motivated me

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

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of people to make sure that, look, people,

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it doesn't matter so much what the average person

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on the street thinks about string theory,

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but what the best students at Columbia or Harvard

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or Princeton or whatever who really wanna change,

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work in this field and wanna work that way,

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what they know about it, what they think about it

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and that they not be going to the field being misled

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and believing that a certain story,

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this is where this is all going,

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

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Well, in general, for graduate students,

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for people who seek to be experts in the field,

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diversity of ideas is really powerful

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and is getting into this local pocket of ideas

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

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no matter what the idea.

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

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

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like it's right for now until somebody builds on

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something much bigger on top of it.

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It might end up being right,

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but being a tiny subset of a much bigger thing.

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

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Yeah, so how to kind of achieve

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that kind of diversity of thought

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and within kind of the sociology

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of how we organize scientific researches.

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

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that Sabina Hassenfelder has very interesting things

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And I think also Lee Smolin in his book,

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which is also about that very much in agreement with them

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that there's a really kind of important questions

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about how research in this field is organized

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

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and get people thinking about a wider range of ideas.

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At the bottom, I think humility always helps.

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Well, the problem is that it's also,

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

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and also, but also you have to have a certain

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very serious lack of humility to believe

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

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I think you have to have like both modes

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and switch between them when needed.

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Let me ask you a question

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you're probably not gonna wanna answer

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because you're focused on the mathematics of things

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and mathematics can't answer the why questions,

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but let me ask you anyway.

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

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What do you think is the meaning of life?

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Yeah, I was thinking about this.

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So the, and it did occur to me,

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one interesting thing about that question

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is that you don't,

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yeah, so I have this life in mathematics

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and this life in physics

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and I see some of my physicist colleagues,

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

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what's the meaning of life?

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And they're writing books about the meaning of life

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and teaching courses about the meaning of life.

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But then I realized that no one ever asked

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my mathematician colleagues.

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Nobody ever asked mathematicians.

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Yeah, that's funny.

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So yeah, everybody just kind of assumes,

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okay, well, you people are studying mathematics,

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

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but it's clearly not gonna tell me anything useful

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about the meaning of my life.

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

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if people realized how little difference there was

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between what the mathematicians are doing

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and what a lot of these theoretical physicists are doing,

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they might understand that it's a bit misguided

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to look for deep insight into the meaning of life

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from many theoretical physicists.

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It's not, they're people,

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they may have interesting things to say about this.

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

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and about, in some sense about metaphysics,

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about what is real of this kind.

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But you're also, to my mind,

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

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

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that I've led a very pleasant

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and fairly privileged existence

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and fairly without many challenges of different kinds

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and of a certain kind.

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

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that a lot of people who are looking for

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to try to understand in some sense the meaning of life

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

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

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for you to be asking about this.

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

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perhaps mathematicians are just quietly the ones

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who are most equipped to answer that question

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

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is at the core of the meaning of life.

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Because it seems like mathematics is the methodology

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

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maybe we should talk to mathematicians more.

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Yeah, yeah, maybe, but unfortunately,

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people do have a somewhat correct perception

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that what these people are doing every day

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or whatever is pretty far removed from anything.

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

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and what my typical concerns are.

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So you may learn something very interesting

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by talking to mathematicians,

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but it's probably not gonna be,

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

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So when you put the pen and paper down,

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you're not thinking about physics

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and you're not thinking about mathematics

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

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

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Do you think about that?

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

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Not especially much.

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Certainly, I've been getting older.

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I'm now 64 years old.

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You start to realize, well,

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there's probably less ahead than there was behind.

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And so you start to, that starts to become,

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what do I think about that?

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Maybe I should actually get serious

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about getting some things done,

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which I may not have,

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which I may otherwise not have time to do,

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which I didn't see.

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

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but that's the main,

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I think the main way in which that thought occurred.

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

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Meditating on mortality helps you

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more intensely appreciate the beauty

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when you do experience it.

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

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

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

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Just enjoy, yeah, our life in general.

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

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And I often think, wow, this is,

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things are, I'm really enjoying this.

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Things are going well.

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Yeah, life is pretty amazing.

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I think you and I are pretty lucky.

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We get to live on this nice little earth

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with a nice little comfortable climate,

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and we get to have this nice little podcast conversation.

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Thank you so much for spending your valuable time

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with me today and having this conversation.

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Glad to, thank you, thank you.

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Thanks for listening to this conversation with Peter White.

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To support this podcast,

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please check out our sponsors in the description.

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And now, let me leave you with some words

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from Richard Feynman.

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The first principle is that you must not fool yourself,

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and you are the easiest person to fool.

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