back to indexPeter 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
link |
about the meaning of my life.
link |
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
link |
between what the mathematicians are doing
link |
and what a lot of these theoretical physicists are doing,
link |
they might understand that it's a bit misguided
link |
to look for deep insight into the meaning of life
link |
from many theoretical physicists.
link |
It's not, they're people,
link |
they may have interesting things to say about this.
link |
You're right, they know a lot about physical reality
link |
and about, in some sense about metaphysics,
link |
about what is real of this kind.
link |
But you're also, to my mind,
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I think you're also making a bit of a mistake
link |
that you're looking to, I mean, I'm very, very aware
link |
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
link |
and of a certain kind.
link |
And I'm really not in no way the kind of person
link |
that a lot of people who are looking for
link |
to try to understand in some sense the meaning of life
link |
in the sense of the challenges that they're facing in life.
link |
I can't really, I'm really the wrong person
link |
for you to be asking about this.
link |
Well, if struggle is somehow a thing that's core to meaning,
link |
perhaps mathematicians are just quietly the ones
link |
who are most equipped to answer that question
link |
if, in fact, the creation or at least experiencing beauty
link |
is at the core of the meaning of life.
link |
Because it seems like mathematics is the methodology
link |
by which you can most purely explore beautiful things, right?
link |
maybe we should talk to mathematicians more.
link |
Yeah, yeah, maybe, but unfortunately,
link |
people do have a somewhat correct perception
link |
that what these people are doing every day
link |
or whatever is pretty far removed from anything.
link |
Yeah, from what's kind of close to what I do every day
link |
and what my typical concerns are.
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So you may learn something very interesting
link |
by talking to mathematicians,
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but it's probably not gonna be,
link |
you're probably not gonna get what you were hoping.
link |
So when you put the pen and paper down,
link |
you're not thinking about physics
link |
and you're not thinking about mathematics
link |
and you just get to breathe in the air and look around you
link |
and realize that you're going to die one day.
link |
Do you think about that?
link |
Your ideas will live on, but you, the human.
link |
Not especially much.
link |
Certainly, I've been getting older.
link |
I'm now 64 years old.
link |
You start to realize, well,
link |
there's probably less ahead than there was behind.
link |
And so you start to, that starts to become,
link |
what do I think about that?
link |
Maybe I should actually get serious
link |
about getting some things done,
link |
which I may not have,
link |
which I may otherwise not have time to do,
link |
which I didn't see.
link |
And this didn't seem to be a problem when I was younger,
link |
but that's the main,
link |
I think the main way in which that thought occurred.
link |
But it doesn't, you know, the stoics are big on this.
link |
Meditating on mortality helps you
link |
more intensely appreciate the beauty
link |
when you do experience it.
link |
I suppose that's true, but it's not,
link |
yeah, it's not something I've spent a lot of time trying,
link |
Day to day, you just enjoy the positives, the mathematics.
link |
Just enjoy, yeah, our life in general.
link |
Life is, I have a perfectly pleasant life and enjoy it.
link |
And I often think, wow, this is,
link |
things are, I'm really enjoying this.
link |
Things are going well.
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Yeah, life is pretty amazing.
link |
I think you and I are pretty lucky.
link |
We get to live on this nice little earth
link |
with a nice little comfortable climate,
link |
and we get to have this nice little podcast conversation.
link |
Thank you so much for spending your valuable time
link |
with me today and having this conversation.
link |
Glad to, thank you, thank you.
link |
Thanks for listening to this conversation with Peter White.
link |
To support this podcast,
link |
please check out our sponsors in the description.
link |
And now, let me leave you with some words
link |
from Richard Feynman.
link |
The first principle is that you must not fool yourself,
link |
and you are the easiest person to fool.
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Thank you for listening and hope to see you next time.