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Peter Woit Λ Joseph Conlon: The String Theory Debate
December 28, 2024
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If you're going to do this, if you're going to not have experiment telling you whether you're right or wrong, it's very easy to fool yourself. I agree with Peter, but then I disagree. We just see that question very differently.
This is an unprecedented conversation. Today we have Peter Wojt from Columbia University, known for his trenchant critique of string theory in Not Even Wrong, both the book and the blog.
and Joseph Conlin from Oxford University, author of Why String Theory and a radiant defender of string theory. This remarkable and forthright exchange covers the technical ins and outs of a theory that's dominated fundamental physics for the past few decades in a manner that's never been seen before in podcast form. Both agree that the field of fundamental physics faces structural problems in how it trains new generations and evaluates competing ideas,
yet they diverge drastically on whether the problems string theory solves are indeed problems it solves, whether it's as elegant as people suggest, and whether it's unparalleled mathematical divination, foreshadowing, for instance, mirror symmetry and modularity of partition functions,
actually signals that string theory is on the right track or a seductive dead end. Many in the public jump on the string theory bandwagon either being for it or against it without knowing the details of what they're supporting or criticizing. That's why it's thrilling to bring this conversation to you. My name is Kurt Jaimungal and on this channel I research mathematical physics and philosophy in front of you in podcast form, bridging these disparate subjects and making abstruse concepts digestible while not skimping on, nor being afraid of, the technicalities.
Welcome to the podcast. Joseph Conlin, Peter White. Joseph, you're known in the popular sphere as a sharp defender of string theory and Peter, you're known as a sharp critic of string theory. Joseph, you have a book called Why String Theory from 2015 and Origins the Cosmos Inverse from a month ago, 2024.
And Peter, you have a book called Not Even Wrong from, remind me of the year? It was published in 2006, I guess. It was written a couple years earlier. And both of those are on screen and the link are in the description. I recommend you check it out, especially the Why String Theory book as it's relevant to this conversation and Not Even Wrong. Although for a more poetic excursion into these topics, origins, the cosmos and verses is relevant. Now, many people are watching this expecting
Perhaps even hoping for disputatious and entertaining bickering. Now, I'm less interested in that, as you know, if you watch this channel, I'm more interested in how can we productively move theoretical physics forward with congenial generative technical exchanges. After going through both of your work, I found several lines of convergence. So how about I pose some of those questions first, and then we can get into your respective defenses and critiques of string theory. Okay, sure.
Alright, what aspects of the Standard Model do you find to be most ad hoc and unsatisfying? And we'll start with you, Joseph.
So I think, so let me split those into what's kind of seems sort of definitely needing explanation and things where we also think there's kind of experimental chance in the near future. So things like the Yukawa couplings of the standard model, for example, the fact, you know, the electron-Yukawa coupling is 10 to the minus 6, there's three families and you've got roughly a kind of an order of magnitude or so, or two orders of magnitude or so.
between them in terms of masses. So that's clearly structure not explained by the Standard Model and we need something more. But the thing which I think where there is most experimental chance to do something in the near future is that of what's called the strong CP problem. And this is an angle that's present in the Lagrangian of the Standard Model in the strong force sector.
and it's equivalent to the question of whether the neutron, which is electrically neutral, whether this has an electric dipole moment and this appears to be zero. The
I think the general view which I also subscribe to is the best explanation for this would be that the angle is dynamical and in this case this leads to a particle called the the axion which could possibly be a part of dot matter and there is a lot of intense experimental work covering trying to think about how you would look for the axion in the various different regimes or masses and couplings it could have.
The first thing to say about the standard model is that what's most amazing about it is how good it is, how successful it is. I think my point of view is different than many people's. I think it's actually something much closer to a final theory that really is perfectly satisfactory than what many people think. The things that are some basic facts about it, some basic aspects of it that really kind of
Just kind of cry out for some kind of explanation for where did that come from? I mean, one is the pattern of gauge groups and representations of gauge groups describing the matter particles, the forces between them. It's kind of a frustratingly kind of simple kind of structure, geometric structure, but with no explanation. Then, of course, as Joe mentioned, there being the Yukawas, what's causing and the whole general story of the Higgs, there's clearly something about the Higgs sector that we don't understand where this is coming from. Most of the
I guess,
If I wanted to point to something and I think there's some hope of getting some experimental evidence about in the reasonable future, I'd point more to the neutrino sector. That's a very funny story and the story about neutrino masses and the story about a right-handed, possible right-handed neutrino field is something, again, it looks like where there's something that, both something we don't understand and something going on and
possibly is something we actually have some hope of getting experimental evidence about, about the axion. I guess I'm less fond of the idea that that's dynamical. I think it may be the reason that that term is zero may just have something more to do with our incomplete understanding of the quantum field theory that governs that. So the other ideas with the axion have been, for example, there's an idea that because it's equivalent to
you could tie it to relations in terms of the corkset, you could move things slightly about. So one of the things has always been that there's the intrinsic Yukawa of I think the up cork is zero, and that there's no and then in that case, the action ceases to be dynamic, there ceases to be a kind of a physical field, and you can solve the strong CP problem, because you can tie it to the phase of the corkset when there is no physical phase if the actual Yukawa is zero. I think lattice results tend to dis dis favor this, this explanation.
And so to me, the action is it's one of these things which is kind of theoretically simple.
explains the required phenomenon. To me, my judgment call is that this is something like the Higgs was prior to its discovery. It's the simplest and most minimal way of explaining the strong CP problem of the standard model. You can't say it's 100% guaranteed that there definitely will be an axiom, but to me it seems by far the most appealing and most likely explanation
Compared to the the other possibilities. Yeah, I just think I just think I see things somewhat differently partly because I I don't I think unlike you I don't see a good good candidate for a dynamical field for where that would come from. It seems to me an extra structure. I don't actually my original work in this year when I was a graduate student. I was working on lattice gauge theory calculations of topological charge and actually very specifically the whole in some in some sense
This was supposed to be a calculation of the theta dependence in pure QCD. It's been a long time since I've thought really seriously about this, but I kind of left that subject feeling that there were kind of fundamental things about the whole story that we didn't really understand. These arguments about theta dependence kind of make various assumptions about, for instance, they only make sense really in Euclidean space-time.
They make various assumptions about quantum field theory, which are quite plausible and it's quite understandable you should accept them, but it's also quite possible that there's something we're missing there. One of my fellow students at Princeton at the time was a very brilliant physicist named Hidanaga Yamagishi, who unfortunately died relatively early in life, but he was always strongly of the opinion that there was a fundamental misunderstanding going on of the theta dependence problem and of this whole story.
Not long before he died, he sent me some short papers he'd written about this. Anyway, I think there's at least some chance that the explanation is that he's right or that some version of that we're missing something about this because it's a bit trickier, I think, than people really actually realize.
I'll simply, the answer is going to be experimental. Yeah, I mean, the good thing about, I think, with axion searches is there's a very active experimental program. There's a sort of a canonical line, you can do this sort of plot of kind of axion mass against coupling for the kind of the canonical values that would, where the axion would be expected to solve the strong CP problem.
And I think it's generally true that things are not there, but there is a developed experimental program that is looking to just kind of bring down the couplings for which you can search for axioms with the aims of either discovering or excluding the axiom across this range of parameter space. And so I think ultimately what's going to happen is this parameter space is going to be covered and then either the axiom will be discovered
or if it's not discovered then I think it'd be reasonable to say then the question of is the axiom the solution of the strong CP problem would then we would then say well if it hasn't been discovered why not. But ultimately there's going to be an experimental answer to this and I think it's also likely to be an experimental answer to this in the next kind of
10, 20 years, hopefully shorter, but there's a very active experimental program concerning looking for axioms across a whole wide range of masses and couplings. This is something I have worked on myself as well. So Joe, people know you also because of your one page paper. What is the direct experimental evidence of string theory, of which there's a single line and everyone's jealous that you were able to publish with just a tweet and it says,
There is none, something like that. Yeah, so that's actually in the book. That's in Why String Theory. So the books are like a 230 page book or something, which is designed as an intellectual kind of explanation of and defense of kind of string theory as a, you know, why so many people work on it and why my view is kind of such an intellectually solid and interesting thing to work on. But then one of the chapters is called Direct Experiment in String Theory. And this is the one page one page chapter.
and if you if you take this in the context of the book you will see that what then follows in the next chapter is the question of well is there if there is no direct experimental evidence for string theory which is true there is no direct experimental evidence for string theory and it's important to be honest to the public and you know and say that because that's true then
One can, and I think one does, to then give this reason for why do so many people work on this, given that this is not something like QCD or something where you can say there is abundant experimental evidence that this is absolutely the correct theory of nature.
So going through your work, Joe, I found four different critiques that you consider to be invalid. I found some critiques that you do consider to be valid. I'll talk about the misguided ones first. People will demand direct experimental evidence at the Planck scale as a prerequisite for taking string theory seriously. You don't think that's terribly valid. People dismiss string theory based on
Criticisms from people who have little to no expertise in the field and they probably don't know what richie flatness is or what that has to do with string theory So that's to be dismissed and then there's an over stating of the significance of the landscape problem without acknowledging that there are ongoing efforts to address it and That I guess this is a defense that that string theory is like the opposite of fossil fuels because you get these positive externalities where you provide tools and mathematical insights, so
Let me know if I summarized that correctly and then feel free to expand and then Peter, I would like to hear your thoughts. Let me address, let me come to some of these. So first of all, quantum gravity intrinsically, if you want to write things that go beyond the standard model, go beyond general relativity.
So the number of people in the world with a technical understanding of things like quantum field theory or general relativity is kind of a relatively small fraction of the population. The fraction of the population who seem to have strong views on string theory and whether or not string theory is a correct theory of quantum gravity seems to be a lot higher than the fraction who have some sort of technical knowledge of say quantum field theory or general relativity.
And so I think there is it is a bit odd to me that there seem to be far more people invested in the notion of what is the correct approach to quantum gravity than have on any reasonable level an ability to form a technical judgment about any of the issues
relevant to it. I'm sure Peter agrees with this because it's just. Yeah, undeniably. Actually, I did want to actually say it's hard to kind of overemphasize that these are complicated topics. And I do think Joe's Y string theory book is the best and serious kind of defense about this and addressing a lot of the issues that I brought up. So I find that yeah, I think a lot of
Anyway, first advice to everybody who wants a kind of a serious understanding of these issues is read his book. I think he actually did an excellent job of doing it much better than anywhere else. At the same time, you should also read my blog and my book and you'll get a different point of view. But it's hard to overemphasize how complex a lot of these issues are. I mean, these discussions that people are conducting on most ridiculously on places like Twitter are kind of just kind of absurd given the
Okay, so how about we get to the Brian Green question? What grade do you respectively give to string theory? And we'll start with you, Joe, then we'll get to Peter, and then we'll have this exchange of lobsome vitriolic aspersions.
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Okay, so I'll give it an A plus because you want to give it an A plus and then Peter can give it an E minus and then we can have some verbal. Okay, a grade for what? So like I said, there's no, I mean, a grade as a
Well, there's largely three families or particles.
Number one string theory as a physical theory. Number two string theory as a production of mathematical insights as well as physical insights, but outside string theory. And number three string theory as a sociological phenomenon with its concomitant hype. So how about a different grade set for each of these?
Okay, so if you want so strict string theory on a time scale of kind of two or 300 years, you know, this is the question is string theory, a true theory of nature. So I'm going to say I think it is okay, high grade string theory, where is something there, where
As happened in, say, the Standard Model happened in the 1960s, 1970s, where you have this very close interplay between theory and experiment and the two drive each other forward. So on the kind of five, 10 year time scales, well, let's give it a D or an E because clearly that's not happening. The kind of question of sociology or string theorists, I mean, whether everything is optimally structured to create progress in the structure in the subject. So I'll give it a C.
Okay, yeah, so I guess starting with the I think that the first one is where I mainly disagree with Joe I don't think I mean everything I've seen about string theory. I mean, I understand why people I understand what why is it why is it an attractive idea and why why some people that find it Have found it that way and and and believe that you know on a you know said sooner or later this is going to turn out to be the right way doing it that I Everything I've seen is kind of the opposite. I just think that this is an idea which I
The more you look at it, you find that it's just not working. It's not doing what you want to need. So that's where I think we have the strongest disagreement. I'm not sure what grade that corresponds to, but a very low one. On the question of what's been going on in string theory research and positive and negative, I think
There again, we're starting to get into this very serious issue that it is very, very hard to actually know what people at this point when you say string theory, what you're talking about. If you're talking about very specifically the proposal for a unified theory based upon starting with a 10 dimensional super string and doing compactification, that's a specific proposal and that I'm
I think it's one that's not going to work out. But now when you talk about string theory, you can be, you know, is ADS-CFT string theory? There's a new paper by Whitten and a collaborator this morning about JD gravity in two dimensions. Is that string theory? I mean, it's become, it's actually very hard to kind of give any kind of evaluation of what
String theory as currently practiced by most string theorists is because it's impossible to actually tell who's a string theorist and what string theory is. And that and that's part of that ties into a sociological problem that it it's I'm interested to see that Joe's grade is relatively low. And I think, you know, I think it's hard to deny that there actually has been a serious problem with how this has been practiced as a field of science in terms of
And it's a difficult problem. How do you evaluate and conduct research on a subject which is so difficult to get any experimental evidence about? A lot of what I was writing about in the book and what I have often written about has been the problems that this causes. And we can talk more about those, I think. But again, it's a very complicated subject.
And a lot of the problems are also driven by the lack of kind of better alternatives of people not, you know, of people. I think a lot of people is that, well, I'm not very happy with how things are going or what's going on now, but I don't see anything better to do. And that's a large part of what's going on. Let me pick up on the thing of which I think is absolutely true what Peter says about the question of, you know, what's meant by a string theorist or what's because
This has become highly amorphous in the sense it's almost the case that what is meant by string theory is the research done by certain prominent researchers at places like the IAS or Harvard or Stanford. It's obviously true that the actual connection to, for example, quantized strings on the world or something that very clearly involves strings, as in one-dimensional extended objects,
can often be rather nebulous. And so I think this is certainly, lots of people have observed this, if you look at the strings conference, the actual topics that people might talk about, there may be rather small number of strings there. And so this is certainly true that often when people talk about string theory,
It's a really much more nebulous idea which is almost like a certain community which is around a certain number of people and the actual topic, the actual research we're actually talking about is not and one thing it certainly isn't which I think often gets people probably get completely wrong. What it isn't is the idea of
string theory as a fundamental theory of nature that is sitting behind the standard model as the kind of, you know, the deep structure of the standard model, the deep structure of this universe. For good or ill, I think mostly ill, but lots of people think for good. I mean, most of the research that is in string theory is kind of much more in the sort of mathematical physics
area with kind of very tangential at best connections to the physics of this world. So then, Joe, what is the definition of string theory? It's whatever is practiced by the people who are at least previously called string theorists. In some ways, that's how, when people use the term, you can of course, and I said that I would, when we think of string theory and string theorists, I've
I would give a very strong defense of there is this theory that you develop from starting the theory from starting from quantizing one dimensional relativistic strings. And this then leads you to strings and this as they're to a lot of this things like holography, ADS, CFT, lots of dualities, there's a lot of this stuff, which very clearly fits into this framework. But that, that intellectual structure, I will, this is, I will absolutely 100% give this an
A grade and you asked me to bet I will say this intellectual structure really does sit underneath at the smaller scales. But it's clear obviously that a lot of the people in the community do does not necessarily fit into that. And so I'm afraid it is a slightly nebulous term. And yeah, that's the word.
Now Joe, ADS-CFT and holography aren't exclusive to string theory despite them being birthed by it. So is the argument that they're just best developed, best articulated in string theory, is that sufficient in your eyes to plant the string theory flag on the holography continent? I think that the best developed examples of holography are those where
The idea of holography does exist in a way that does not rely on string theory, but it might be all the kind of really most solid and really fully worked out examples are all in string theory. So what do you say to that, Peter?
I agree with Joe that the connection to string theory and being able to say something more than general things, vague things about holography is in this ADS-5 case, in the five-dimensional case.
And your problem is that doesn't connect very well to the real world, either in being at, you know, we live not in five space-time dimensions, but in four, and the hope that there's always been a very different hope for that, that I think motivates some of that research, which is that you're going to be able to solve QCD using that. And there's technical reasons why that hasn't worked out so well. But I think
That ADS-CFT was 1997, so that was 27 years ago. This is actually something I didn't really say much about in the book because the book was largely written in the first few years of the 2000s when the ADS-CFT was just starting to get going. It wasn't clear at that point how much it was going to dominate the subject and a large part of the subject.
And I think it has, and there's a lot of, it would be interesting, there's a lot of interesting to say about that. I think one thing that really struck me actually this morning waking up, as I do, I often look and see what new papers there are on the archive. And I kind of mentioned this earlier, I mean, one paper that appeared today, there's like 60 some pages written by Ed Whitten and Jeff Pennington, which is very,
A lot of very, very technical stuff and actually, you know, a huge amount of kind of work and intellectual power that goes into the, and has gone into this work clearly. But what it is, I think, is a thing that is an example of something that's been a major theme, you know, in string theory as practiced by people at the IAS or very influential people, especially in a subject, which is to
To address the fact that there's a lot, the whole idea of this ADS-CFT duality, there's a lot missing there. You don't really understand exactly what this means or exactly what's going on. So you want to kind of find some simpler case where you really can get control of it and really use it and really understand exactly what's happening. So you start
One thing you do is you go to lower dimensions and use, one thing you do is you look at ADS3 CFT2 where you really have a lot of control of the, you know a lot more about the CFTs and you hope to be able to kind of say something about three dimensional gravity. And then if you look at what's happened in that subject, I mean, that's turned out just to be very complex and how gauge gravity duality is supposed to work in this, even in this lower dimensional case is
Is quite quite tricky and turns out to be very complicated and you can then People spend a lot of time going even farther down and going down to to to you know to basically, you know to two and one dimensions and to this JT gravity and so there's there you can calculate all sorts of things and you can apply is also things you do but it if you want to make this look like instead of having a nice simple beautiful picture about yours how this works it it becomes very complicated and very
very tricky to get this to do what you want. So I mean, so on the one hand, you know, Witten and very influential people have spent a lot of their life now down in these very low dimensional toy models, trying to get some, you know, trying to get some, some a handle on what's really going on there. And I don't think that that's to my mind, you know, that hasn't been much of a success at the same time. I also saw online, you know, Witten is giving a talk, opening a conference, um,
In Turkey today and he's giving a talk he's often given about you know, what every physicist should know about string theory and and you know that that talk is You know very much a promotional effort. It's completely, you know, I actually have very serious serious problems with them You can look up very version raised version of this talk and you know, he's you know, he's he's he's a genius He's very smart, but he's making a very
Hey, he's giving a certain technical reason for a whole kind of ideology, which I really don't think works out very well. And at the same time that he's kind of still kind of doing this to try and trying to promote this idea and trying to get that part of it is, I guess, defense against critics like me.
At the same time, if you look at what he's actually doing, he's, you know, been going down a bit of a rabbit hole of where ADS-CFT is led to. And, you know, there's all sorts of interesting things down that rabbit hole, but they don't really look like what you want. One thing I will pick up on, which I think maybe I broadly agree with Peter on, is that sometimes if you look at things like the Strings Conference, which is this, sometimes they have these kind of public talks, and then you look at what's been put in the public talk, and it will be something like, you know, you start with a standard model,
Yeah, we need to get the physics of the Standard Model, we need to do the physics of gravity, string theory, fundamental theory of nature. And the justification that is kind of presented in that for string theory is the sort of, you know, basically, we are fundamentally doing particle physics, and we are trying to get the smallest things of nature. And then you actually look at what all the technical talks on the conference are, and they're all on kind of physics in two dimensions, or six dimensions, or three dimensions, or any number of dimensions other than four. And, yeah, with two
n equals two symmetry symmetry when you thought supersymmetry yeah yeah so that all the actual research that they you know that is most elevated is actually nothing to do with these kind of particle physics questions and so this i do agree that well that the case whatever the case you would make for something like detailed studies of holography in n equals two or jt gravity or anything like that
This case is not really a case. This is not what we are trying to do is we are trying to understand the laws of the laws of this universe. And we are trying to kind of go go beyond the standard model, which often is is the case that is made in in public tools. Peter, you said that you had several criticisms of the talk by Witten, at least, I don't know if it's the most recent one, but some of the ones in the past, what every physicist should know about string theory.
What is
I'm not going to forget. I think I wrote about it in the blog and tried to kind of go through this carefully and and address seriously what this was. But I think the. I was just looking at this again this morning, so I'm trying to understand the witness point of view, and I think what he. Well, there's some very technical issues. I mean, one thing is he he kind of tries to motivate this by starting out with. Not quantum field theory, but but.
Kind of the path integral quantization, we're saying we're going to have a particle theory and we're going to sum over paths. And then if you try and put in interactions, then you have to decide what's going to happen when paths join. And you can think of this as a little bit of a caricature of where the problems of renormalizability come from, from the short distance behavior. And then he says, well, then in strings, instead of having
These paths, you have world sheets and the world sheets don't have the same, you know, they don't have interactions aren't introduced by what's happening at intersections of paths. So, you know, so you're not going to have that problem. But it's kind of, it's kind of avoiding the main issues. I mean, because because the what he's talking about is actually a single particle theory. And that's actually not what
What we do i mean that's actually not what quantum field theory is quantum field theory is a theory of fields interactions that come from these have a geometrical origin and gauge symmetries and separate they're not. So he's he's kind of giving a really unfair caricature or characterizing quantum field theory in a way which which i think is really.
Doesn't have much to do with the real thing and the real problems of the thing and then trying to You know to use that as justification. Well, you know world cheats are gonna are gonna solve our problems and I don't Anyway, so so that that's kind of a tech just a beginning of a technical argument against it It is interesting that goes looking at a more recent version of this that he gave and and you know, it's clear that he his I think what he's confronted about this. I mean he
he's making a bit the case that joe is making that you know there's there's clearly something there's something very interesting going on here and i think the way he he likes to say it is that you know this is it's very very hard to find any kind of consistent thing which goes beyond quantum field theory which is not a quantum field theory but but but still sat it but which generalizes quantum field theory and still satisfies the fundamental principles you need to satisfy and that the fact that string theory exists and is such a thing you know makes it you know highly worth
We're studying. This is certainly true. The problem again is that people have been doing this for a long time. He first proposed the idea of M-theory in 1995, so now nearly 30 years ago. There's something very complicated and interesting going on there with S-dualities relating theories in unexpected ways.
But the kind of idea that there is some kind of, you know, well-defined, you know, fundamental, in some sense simple basic structure which is behind all this and which is going to actually be useful for describing the real world. I just don't see the last 30 years as being very kind to that idea.
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Joseph, what do you broadly agree with and disagree with? Yeah, let me say this. So there's a few among a lot of string theorists, this is because string theorists, the community that would go there would go some something like this. So this is a view I don't actually agree with, but I'm just going to try and state it in the best version I can, which is that when you encounter string theory, you encounter this extraordinarily rich and deep structure with
Many connections to quantum field theory, to gravity, many deep and surprising properties about it. And because the Planck scale is so large, i.e. gravity is so weakly coupled, the right intellectual approach is to try and study this deep, mathematically complex, extremely intriguing set of ideas and to study it as deeply and as thoroughly as possible.
and to try and get as full as understanding of it with the idea that when you do get as full of understanding, by developing this full understanding, you will then be in the best position to understand then how this theory can be connected to the real world. Okay, so that is, I think it's a view a lot of people have and it's a view I broadly disagree with that. So what I would say is, so my view is that
Mathematical physics, this type of thing has been on a sort of diminishing returns for the last kind of 40 or so. I mean, ADFCFT is a big kind of peak against the broad trend of diminishing returns. But there have been awful lot of people working in this kind of way for a long time. And I think if you look at the kind of say the theoretical results, for example, GR, the results about black holes of Hawking and Penrose in the 90s, these were both kind of
extremely intellectually deep, extremely intellectually profound, with also profound observational consequences. So now I think you often have people arguing for kind of results that are deep, but they're really kind of quite divorced from. So my view in terms is in terms of applications to physics as a whole, mathematical physics has been delivering, which includes a lot of this kind of what kind of string theorists do has been delivering diminishing returns for
a few decades. I think I also think there's a danger, which is as follows, that if when you have people who are working in theories and to debate theories in highly subjective theories, which where there is no real attempt to make connections to the physics of this universe, and then they train students who are working in these areas, and then those students themselves become, you know, is that you lose the connection with what it is to measure something.
And so some of the research I've most enjoyed is when you actually have to think about, you're trying to measure something, so you have a telescope or something, you actually have to understand how it works, how it actually gets data, what actual data is, you have to actually think about how experiments actually work. And I think there is a structural danger in that you have at least two, sometimes three generations of people who get trained in an environment where they don't
Actually, no, they don't they never they've never really worked with data
And they've never really thought deeply about what it is to measure something in the real world. Now, the people of the older generation who were kind of, you know, Peter's mentioned like Ed Whitten, for example, or obviously they grew up in the generation where the generation of the standard model and they were kind of surrounded by this. Yeah, this was kind of part that they were kind of just incubated in the thing of how you measure stuff, because that was just where they were. But as you go on to kind of as you move forward in time towards the present, then you have people whose entire career is, yeah,
Where they haven't written a single paper, which involves how you actually measure anything in the real world. And the students haven't written a single paper in this. And it's like muscles, you know, if you never use your muscles, if you spend your entire life sitting on a sofa.
It's not the case that you're then by thinking deeply, you'll work out how to walk and then you'll get up and be able to walk really well. If you never use the muscles, they're a trophy. And so my worry is that there is a danger that this is happening because people have never worked on how you connect anything with data and so they lose the ability to think about such problems. I have a somewhat different point of view on all this because actually, so I mean,
I'm often people often characterize my views as my main criticism of string theory is that oh well you know it's not really it doesn't have experimental backing and so this is the main problem with it but that's not actually what actually bothers me about it most I mean I do have this great respect for experiment I went through this you know I spent some time working on a particle physics experiment early in my in my career and that was actually a very extremely eye-opening experience in terms of
Understanding why your theories are the way they are. Our best theories are the way they are because they were determined by what was measurable, what could be measured and what couldn't. The problem is that it has legitimately become very difficult to approach these
Questions about you know how how to do better than the standard model experimentally and we really are We may already at this point with the LHC have basically run out of steam and you know, it's there's a big argument about whether you know to build another next-generation accelerator and the the problem is that Anyway, we know how to how to do it is going to be very very expensive and not not that big an increase in dumb and that the resolution the energy you can go to and
So we are kind of stuck. I think the field, if you want to make progress on these questions, you may have to. I'm more sympathetic. I think the point of view that Joe is less sympathetic to among his colleagues that, OK, well, maybe you need to kind of go somewhere else for inspiration, go to go to mathematics or go to try and figure out how you can make progress on these things without having a connection to experiment.
And, you know, I've spent most of my life in a math department. So I know I have a lot of sympathy to kind of what the way mathematicians think and what mathematics, how mathematics works. And but I think I see much the same phenomena that he's talking about from a summit from this different point of view. Even if you like myself, if you're actually willing to say, OK, I'm I'm willing to accept
Maybe to put it in the most extreme fashion, if somebody today, tomorrow came to me with a completely beautiful, completely simple mathematical structure, saying, okay, here's why the standard model works the way it was and why gravity works the way it was. But unfortunately, it's incredibly beautiful and simple.
and and they were right and I agreed with that and there was a but but there's no it shows what there's no way for us to really get any more evidence for this experimentally I would be tend to be I say okay well that I'm happy that that's great whereas I think Joe and many others would not be so happy with that but but but but even if you if you focus on on them on the on the mathematics I think he's right that they've been really diminishing returns there were some just truly um revolutionary amazing things that came out of
especially the late 80s, early 90s, and this kind of overlap between math and physics. And a lot of it was generated by kind of joint efforts of Witten and Michael Atiyah. And they just completely, they have wonderful, for explaining some actual physical things, but they also are just completely revolutionary for mathematics. I mean, these ideas about the so-called churn time as Witten theory and
I did and the things that happened with with three manifolds and four manifolds they were just and mirror symmetry that they really have just revolutionized parts of mathematics but you know but watching what's happened since then since the early 90s it's just been kind of a every every it's just been kind of a monotone decreasing amount of that kind of new insight coming coming in at least as I said I often spend my day get up in the morning and look and see what
What new papers are there in this field? And it's just the number of days when I see something, oh, that's actually something new and interesting, has just become starting to become vanishingly small, or as it used to be a fairly common occurrence. So here, there's something I say in my book, and I've said this a few times, but it's the idea that you can, you can buy from people in your language, but you have to sell to them in their language.
What are the reason kind of string theories grew so much and spread so much was discovered this thing that Peter's alluding to is that it was able to solve other people's problems and contribute to other people's fields. So this example of things like mirror symmetry in the 1980s, it was able to
do things that mathematicians cared about. It wasn't a case of you now need to start caring about quantum gravity and start thinking and care about our problems. It was able to say these are the problems you care about and we can solve these problems for you. And likewise with quantum field theory and holography ideas like dualities and ADS-CFT. Again, there were lots of people who were kind of quantum field theorists and then there was this, well, you can do these calculations in gravity,
Then using ADS safety, you can solve problems at strongly coupled quantum field theory, which people were interested in as quantum filters. So this is one of the reasons I think string theory grew so much, particularly some of the people say, well, there are all these models for quantum gravity. Why is there so much on string theory? But I think part of the reason for this is that there were these types of losses in the 1980s and the 1990s on where string theory was able to solve other people's problems.
And this is what led to the thing going on. But I do kind of broadly agree with what Peter said. I think the I mean, I think ADS CFT was a huge peak around 1997. But I think the the test on this is, you know, I read Cliff Burgess calls this the kind of the the the ego test is kind of, you know, do you start advocating for ideas that aren't your own?
And the sort of thing is, yeah, so the subjects that are kind of around theoretical physics, you know, the question is, when do they want to start saying that, yeah, advocate saying pulling, pulling in ideas from kind of string theory and saying, well, look, we really need these stuff to solve our problems. And I think this is what happened a lot less now in the last, say, 10 years or 10, 15 years or something than it did in the 1980s and the 1990s. Yeah.
But maybe just to say one other thing about that, I mean, one thing, and this is actually one thing that I was trying to do a lot in the book I wrote was to, I mean, the story of these ideas that came in the 1980s, 1990s, a lot of them were,
String theory was part of the story, but very much only a part. A lot of these really were ideas that were purely just very new insights into quantum field theory. Sometimes they had come about because people had been thinking about something in string theory and then realized there was actually something really interesting happening if you just looked at some related quantum field theory story.
Anyway, there's an incredibly complicated and confusing story about a lot of these great mathematics, mathematical physics developments of that era about their relationship to string theory, often which was kind of heavily oversold or which is actually different than, just for instance, I think people
I found it very, very hard to convince anyone of something that is actually true, which is that Ed Whitten did not win a Fields Bell for string theory. If you look at what he actually, it's just truly amazing thing that a physicist won the highest award in mathematics for some just amazing new developments in mathematics and everybody assumes that this happened
In the early nineties, and so, you know, during the period of string theory and with was working on string theory. So this must be a, a Fieldsville for string theory. And it's just simply not true. If you look at the citation and you look at the actual work that he, um, you know, they had this, this, this deepest mathematical, um, content at the time, it wasn't, um, this actually wasn't string theory, but actually getting anyone. When I say this to people, they, I find it almost impossible to convince anyone of this, but.
Maybe just to pick up one other thing that Joe had said. He was worried about the way people being trained to do physics in a way that's divorced from experiment has led to this kind of atrophy of certain kind of skills, which are really important. And that's true. But I also think what I've seen, which I find very disturbing, is when I look at students now and I talk to them, they're
I remember being a student like that and what you wanted to do was you wanted to say, how do I get to the cutting edge of the subject and to the really newest, most exciting ideas that are moving forward as fast as possible? This is what you want to do. What it causes them a lot to do is to really skip over learning quantum field theory. They take a quantum field theory class and
They do some problem sets, so they learn how to do a few computations, but then they immediately are then trying to do ADS-CFT or string theory or whatever the hottest topic is of the year. I'm really increasingly worried that the system has trained a couple of generations of people who don't actually really understand the standard model as a
You know what the quantum field theory issue has a quantum field theory what the actual technical issues behind it are and you know that they've ended up being trained in topics with you which aren't aren't that fruitful while completely skipping over you know just the real fundamentals of what what the problems are.
Let me come in on that because that's something where I think I don't really agree with. So if you take, for example, Peskin and Schroeder, so this is a well-known quantum field theory textbook, loads and loads of people learn quantum field theory through Peskin and Schroeder. And you see what it's structured to. So Peskin and Schroeder kind of builds up to, you know, one loop precision electroweak calculations in the standard model. And these were kind of, at the time it was written, kind of the LEP collider was doing lots of precision electroweak tests.
And I think it's true, you know, very, very few students learn, you know, are kind of fully on top of precision electric. But then I also think that's, you know, the subject, the subject changes the in that the calculations that you need to get, you know, you need to be really in the in the weeds of they do change with times, for example, you could argue now that knowing gravitational wave emission and understanding
gravitational waves is or understanding the physics and physics of axioms is more important for people who want to be connected to experiment than understanding how to do by hand one loop calculations in the electroweak sector of the standard model. Because it's also true that the people who do kind of standard model calculations, they are not doing them by hand, they've all got
Co-co-coach to do them. So I do think this true that the skill set, the skill set changes with time and the kind of the problems you can be where you can be fully conversant with all the kind of nitty details of does it just change by generation and it's kind of right that it changes by
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By generation. So I don't know whether that's exactly what Peter's Peter's referring to, but that. Sorry, just before I also don't see it as something that's
Your critiques, Peter, as being about this generation. So as I was preparing for this talk, I went through the critiques of string theory that you have Joseph, which are you're not a fan of the overhype in the same way that you're not a fan of the uninformed criticisms. Both do damage. You see that there's difficulty in constructing decider vacua because they require a balance of delicate balance of multiple
contributions to the potential. There's also the scale separation in ADS-CFT, and yes, ADS-CFT is powerful, but constructing compactifications that correspond to scale-separated CFTs where there's a large hierarchy in operation and operator dimensions is difficult. And I know that's relevant for realistic, modulized stabilization scenarios. I'll put some of your work on screen.
There's also the G2 compactifications in M theory, which unlike the Calabi-Yau manifolds, which are complex, these ones are real and there's a palpable lack of examples of compact ones with the singularities necessary for the non-abelian gauge theories. Now, Peter, your critiques of string theory are that unless I'm mistaken, they don't have something to do with this new generation being trained without being tied to experiments or
without knowing the fundamentals. When last we spoke, Peter, you spoke about the lack of predictive power and this huge landscape, which is even larger in F theory than it is in regular string theory, that there's no consistent non-perturbative formulation, but also you both agree on the hype and you think ADS-CFT is a distraction. I'm not going to
Well, I would love to have you all speak about that. And then the other two or three that I recall are that the claim that it's mathematically rich is true, but that doesn't validate it as physics, and that there's an ignoring of alternative approaches.
Epitomize by its only game in town. So does that correctly summarize your respective critiques of stream theory? But but but but Kurt, are you trying to characterize my views or are you bringing me? I think
You're not not Joe's. I think Joe is not going to be on board with all of this. Yeah. No, no, no, no. Just the first few were Joe's, up until Joyce Manifold. Then the rest were yours. Anyhow, the point is that all of what I've stated, I don't see as being unique to this generation. I see it as a critique you could have said 20 years ago. I remember when I came into the field, so I was
I was really fascinated by this. This was the mid-70s. To me, from the beginning, what was the cutting edge was the standard model. Everything was
My whole kind of conceptual framework of how do i think about what i'm trying to do here is i want to learn as much about the standard model as possible i happen to be also very interested in mathematics i want to learn as much about the mathematical structure of the standard model as possible i want to learn about the non-perturbative issues in the standard model and so this was this was how i was brought up and how and my own this is what my whole motivation was about i i i see
The last few generations, now going back 20 or 30 years, of students coming in with a very different thing. The things which to me seem really the most central deep issues, which there's still something there we don't understand and which you need to work on, that's just something they've kind of skipped over. Joe was pointing out to one thing about a typical standard, maybe just to say one slightly technical thing, quantum field theory textbooks, if you look at them,
Yeah, they're mostly fairly similar. I mean, they do things in different ways and they have different virtues and different problems, but they really are aimed at showing how to do these kind of perturbative calculations in the standard model, like as he was referring to, and there's a certain technology for doing that. They're training you how to use that standard technology. I mean, the problem is what they're not doing is they're not really kind of telling you about any of the
Any of the technical problems about what things are still on is, you know, to me, the kind of central question, what is still unsatisfactory about the standard model? What doesn't really work right? And that you don't get out. It's very hard to get out of a quantum field theory textbook. Anyway, it starts to get to get to be a little bit more complicated. But I really I really see a big difference between kind of my
the environment in which I was trained and what I was focused on and what, and I see that what students these days, how they're being trained and what they're focused on. And, you know, I think the thing that, the thing that to me I think was most central and I think still is a most central question in our subject. I think they're really kind of not, they're trained pretty much to ignore. And even worse than that, this is a field with a lot of intellectual arrogance.
And it's a very, very difficult subject. People kind of come into this environment thinking, well, oh, you know, I must, you know, anybody who understands this stuff like me is a real genius. I kind of understand it. I must be a genius too. And, um, the other people also come out of the standard educational experience these days, not just being unaware of things they should be aware of, but, but at least somewhat morally convinced that, you know, anybody who cares about those
Issues is somebody who just never understood the textbook you know that you know these are old textbook issues which have long been settled and you know if somebody is kind of trying to bring these things up and talk about them it must be you know they were just one of these students who kind of never really understood that understood the textbook that and that's that's a little bit exaggerating but it's um
So there's one things where I want to speak in defense of students. So I think this also something applies with experimental particle physics. So I think it's with students, I think students really need a chance to, people need to, when young people want to do something, they need to have a chance to have a career. And I think this involves a certain thing where you know, the thing where you're going to work hard on something, you're going to work really hard on something, it may not work out.
But that you've kind of you get your lottery ticket or your ticket, you know, you get your chance of that you work really hard and then there might be something kind of really big. So experimentalists get this. You had this with the LHC, for example. Yeah, they work really hard. They have a there's a chance of discovery. I think it's really important that people have a they have the chance of contribution. And so I think the. What I have some sympathy with what Peter is saying, I think it's also from a student's point of view, I mean, the
It's really hard to be the idea that you're going to say, well, we've got this standard model and Weinberg at his peak was spending huge amounts of time thinking about the structure of the standard model. Witten has been growing up thinking about the structure of the standard model. And so this is an area where there's been a lot of extraordinarily smart people have
Been over and been over and been over and so this is why I think you will could I think you can fully understand why she would want to be something where they're going to something which is maybe less explored and then then they feel they have a kind of so I also want to pick up on this comment on on arrogance which I think is kind of interesting and I think it's
it's true but there's also a sense in which i think it's kind of it's important it's true and i think it's kind of what i want to kind of explicate this a bit so this comes back you know if you're a student and then you think well
Okay, you're a student in particular and you want to make, and this is kind of held at every time and you want to make a contribution to the subject. And if you think too hard about the idea of, I want to make a contribution, and you know, Weinberg's been spending his career in this area, Witten's been spending his career in this area, Wilczek's been sending in this career, or the previous generation, you say, well, Heisenberg's been thinking all about this, Dirac's been thinking all about this, Feynman's been done.
If you kind of worry too much about this, I think you will just collapse under the weight of what you're trying to do. So I think actually the healthiest attitude for students is almost some simultaneous combination
of kind of almost extreme arrogance and extreme humility. Not just one or the other, but somehow to be able to hold them both at the same time. Because on the one hand, you really want people to be saying, actually, I think all these people who are genuinely obviously super smart have been in this area before me, have been thinking about this before me, but I can make a contribution and do something none of them do. I can do something that Witten didn't do, that Weinberg didn't do, that Wilczek didn't do. And
Yeah, to be honest, some degree of arrogance is going to help helps in that, otherwise you just collapse under the way. But then you also need the humility of saying, all these extraordinary people have been here before me, I need to learn from what they've done, I need to learn from the best of what they and so this isn't to my view. I mean, theoretical physics has a justly deserved reputation for arrogance. But I think also there's also a big element of humility.
To buy also and this is the kind of thing which is maybe slightly controversial is I think this arrogance is actually a structurally positive part of the subject because the subject could not make progress.
without it, because otherwise, if you think about what you're trying to do, you just will, people will just wilt under the expectation that you're, you know, that you could the idea that you could be 22 or 23. And you've had 1000s of really smart people in this area before you. And you can do something that they they haven't done. But it's needed. We constantly need 22 or 23 year olds thinking this in order for the subject to make progress. So this is my slightly nuanced view on arrogance in theoretical physics and why it's actually a structural and ultimately a structurally positive
Why would you say arrogance and humility versus confidence and humility? Why do you say arrogance over confidence? So, I mean, so this is coming back to the thing that, you know, the rational of evaluation of anyone is if you are saying, look, Feynman's been thinking about this, Weinberg's been thinking about this, Witten's been thinking about this, you know, can I
Can I do this? I mean, I think, you know, if you are going to rationally say, well, oh, yeah, I can rationally evaluate myself as you're not talking about me here, but, you know, someone could rationally say, well, I'm confident I could do better than Weinberg or Witten or five. Yeah, I don't think that's, you know, it's somehow it's not you can't do it rationally. It needs, I think, I think actually this sort of slight, you know,
I pretty much agree with Joe. I should make clear that this kind of
This wasn't completely a critique about arrogance. I mean, I've just been sitting here telling you about how Ed Witten is wrong about something. I mean, I clearly have plenty of arrogance to go around myself. He's right. You need some intellectual self-confidence and ambition to get anywhere in these kinds of very difficult subjects. At the other time, you also need the humility to realize that you're
You're quite possibly wrong about things. It's a very interesting experience being in a mathematics department because mathematicians are, the whole thing is about these very precise issues of exactly what is right and exactly what is wrong. So mathematicians are actually quite used to the fact that most of the time
Very often you're going to be wrong about something and it's going to be completely undeniable because it's going to be an issue of rigorous mathematical proof. Anyway, I agree that this intellectual ambition and arrogance of the young is a good thing and is what leads to progress.
This was just kind of a more of an issue of the way this often shows up. It does become a problem in this particular context. When the field itself is not that healthy, it isn't making a lot of progress and ideas that are being promoted as the latest ideas are not working well, then the danger of being an arrogant student coming in is that you might actually believe
but believe this and and and and this will uh anyway you'll you'll you'll lack the necessary understanding of what's actually right and what's what's what's wrong um but i think maybe i think joe started to talk about something which i think maybe we should talk about which is related which is this question of you know of careers if you're a young person your other main concern besides whether
You're arrogant and smart and other people are not. Are you going to be able to have a career? Are you going to find a job? Whatever your intellectual goals are, what you want to pursue, is there going to be a way for you to do this? Are you going to be able to support yourself? Are you going to be able to have a real research career? How are you going to go about this? I think that's really a real fundamental issue.
If you do agree that there's been some problem with the field not making progress the way it should be in recent decades, you have to ask yourself, is this part of the problem? What can be done about this? What can be done to actually change the reward structure so that ambitious young people actually can work on more promising things and still feel that, as Joe says, they have a shot, they have a chance to actually do something.
Okay, here's something I'd like to say, which I think this is not this is not something which is at all unique to string theory or particle. So I saw basically a kind of a quite interesting plot. So this was this was from the US. This is the I think the National Institute of Health and they have something called like R1 grants. And these are the grants which basically go to kind of start when people start a lab of their own. And what the plot was, it was the percentage of these grants that go to people under 35 compared to the percentage of such grants that go to people over 66.
And so this is kind of gone from like from 1970. It's something like, you know, maybe like 35, but roughly something like 35% are going to be under 35, 1% of these are going to over 66. And then you kind of you come to today, and the numbers are sort of inverted.
That is a very large fraction. These grants are going to people over what is what we would use to be a retirement age and a very small fraction are going to people under 35. And I think you can see simple things in kind of fundamentals, particularly with things like the Simon's Foundation and this habit of some private foundations giving extraordinarily large sums of money to very senior people basically to run their
large numbers of junior researchers in their research in their research programme. Whereas I think a much more similar things like the sort of these Simon's collaboration again, which are kind of very, very large, very well funded things, but are basically are kind of very much supporting established research. And I think the ability to give young people the head give them, you know,
enough money that they could properly do something by themselves without relying or feeling that they have to sort of sit in the network of someone much more senior and obviously not all these things will kind of work out. So I think this is a sort of structural weakness in terms of
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Great. Now, as I mentioned in the introduction, I would like this conversation not just to focus on string theory, but also theoretical physics. What are the problems? So you just mentioned that there are disproportionate rewards that go to senior individuals instead of the fresh talent.
What else? And I understand that this doesn't just affect whatever we're about, or you all are about to speak about, won't it just affect theoretical physics, but perhaps science as a whole? But let's just speak about our domain of theoretical physics here. So what are the problems actually with fundamental theoretical physics as theoretical physics as a whole is quite large? I mean, I think the obvious one is that of experimental data. I mean, I think maybe people's views on the subject. I mean, Peter's from a generation where
The standard model was being discovered in real time, as it were. There's a period in the 1970s, the late 70s, where particles are kind of not quite at the rate of one a year, but almost at a rate of one a year. And I think what you experience when you're young inevitably sets your notion of what kind of is normal or what should be normal. I mean, my PhD is in 2006. I'm from very much the generation where
Yeah, almost your expectation is every single time you try and break the standard model, the standard model wins. That's, that's been the pretty much throughout, throughout, throughout my career. Obviously there is physics beyond the standard model. We know there is, there has to be physics beyond the standard model, but in terms of your expectations, your, your default thing of what happens, I mean, yeah, we are from, we were formed in very different times. Actually, not, not that different than you think. I was also the, um,
I started learning about the Standard Model in 75, 76. It was already in place and this phenomenon of that as experimental results came in, they all... Anyway, there's a lot of excitement that everything was agreeing with the Standard Model, but I think it didn't take that many years to start to become a little bit depressing.
Wait a minute. It's great that we're so successful and everything agrees with the standard model, but if we don't have something soon that disagrees with the standard model, we're going to be in trouble. This goes way back. We've been in that situation for a long time. Hype is not a new thing. Supersymmetry was first discovered in 1984 at CERN.
at UA1 and UA2. Yeah, I think it was undiscovered in, you know, 1985 or, yeah, but it was, yeah, so claims of kind of discoveries, claim your hype, which are things which are not subsequently justified. Yeah, I think they've always been there. Maybe to try to address a little bit, I think what you're trying to get at. I mean, one is, you know, there's technical questions about, you know, what we might see as how to make progress. And, you know, and I'm in this
Very weird state of the last few years. I've actually some old ideas, which I long convinced myself couldn't possibly work. All of a sudden I started to see ways forward and I've been very happily exploring those and I actually think this is really going somewhere. So I feel myself in this question of, oh, what's the future of the subject? What's the right thing to be thinking about?
Feel like I start to become like every crank in the subject. Yes. Well, you know, I know what the right thing is and and I'll tell you all about how twisters and This and how this this is the thing to do. So I mean there are various ways of thinking about twisters Hitchens From way of thinking about them and the relation of hyper echelon manifolds. I've actually kind of realized that that's actually a better way of understanding the relation to some of the other things that I've been trying to do so
And there's this, maybe just to say a couple words about the whole thing, it's really just, there's a fundamental idea in twister theory is that a point in space-time should be thought of as a different kind of geometrical object, as a sphere. If you like, maybe when you open your eyes and you see the celestial sphere, that sphere is the way you should describe a point in space-time. Or mathematically, it's also equivalent to saying that
If you're looking at the vial, like let's say the right-handed vial spinners at a point, that you should actually describe the points in spacetime by using those spinner spaces. So in some tautological sense, if you want to know what a spinner is, in this geometrical setup, the space of spinners at a point is the point.
So there's a long story about this, but I'm seeing quite a lot of different ways of seeing the symmetries that really govern how the standard model works. There's a new way of thinking about them coming about from this geometry that I find very promising. Maybe that's the best to say, but it really is kind of work in progress, but I keep finding them.
Unlike most ideas I've had in my life, I've found that if you think about them for a while, sooner or later things just kind of work less and less well and you realize this wasn't such a great idea, this is actually something that just kind of keeps doing something interesting that I'm quite excited about. But I can understand it. Anyway, there's a lot to be done to get anyone else interested in this.
If falsifiability is not immediately achievable, then what are the other criteria that one should use to evaluate between different competing theories of fundamental physics? I think there is an intellectual depth and an intellectual richness of strength theory, which I think is the more people are able to evaluate it at a technical level, the more people agree with this.
And now you can say it is an aesthetic judgment to say that ideas which include quantum field theory include general relativity and are very kind of rich and complex and kind of hold together in lots of non-trivial ways. So it's an aesthetic judgment to say that probably nature doesn't leave this out.
You could say, well, you could have this structure and you could say you could if you were going to say to me, yes, string theory may be mathematically beautiful. It may be intellectually rich. There is no logical reason why that means it has anything to do with nature. I can only agree with you. There is no logic. There's no logical reason that is not logically implied. So there's an aesthetic judgment that things which are really mathematically subtle, mathematically
complex and somehow tied to a lot of what we already know to be true are not left out by nature. So that's what I would say and part of that's an aesthetic judgment. I in some sense agree though. I think my own
Anyway, my own aesthetics and the mathematics and the things that I've been interested in. I think I see this differently than Joe. I mean, string theory, it's true it's a very rich subject, but I've always thought that to some extent it's a very rich subject in some ways because it hasn't really worked out. I mean, if this had worked out in 1985 and you'd found that there's some certain clobby-ow
you know, gave you the standard model on this all worked, you know, it would be, you know, a fairly complicated and, you know, very interesting theory. And it would be, and that amazingly works described as the real world. But instead, you know, that people had trouble getting that to work out. So they started on a very, very long intellectual journey and by some very, very smart people. And they ended up exploring all sorts of very, very different
different things and discovering all sorts of interesting different things about mathematics and about physics. The problem for me has always been that to the extent that I find the things that they're discovering really compelling and really beautiful, they often were orthogonal to the things that were looking more, to looking like the real world. That if you, when you tried to move this in the subject into the, and try to get something that looks like the real world, you
you had to move in kind of not so aesthetically pleasing directions. Whereas if you'd said, I'm going to follow, you know, my aesthetic judgment that what is a really deep idea? What's a, you know, something worth looking at totally independent of whether it has, of whether it agrees with the experiment, you ended up going in directions which, which don't so much look like the standard model or look like the real world. Can you give an example of where you've had to move away from what's aesthetically pleasing?
um well i mean anything even um i mean mirror symmetry again is an example it's uh there's beautiful mathematics there it just doesn't connect very well to anything about telling you about four dimensions um maybe adscft is also somewhat somewhat of an example that you want to you know it works really nicely and
You know in five dimensions and five dimensional space time if you the minute if you try and use it to kind of say something about real fit real physics but four dimensional space time or you use it to try to solve QCD you. You end up just kind of struggling and having to try to.
The question that I just asked was about what is it that should allow us to decide between competing theories when we don't have experiment to guide us? So in other words, when we don't have something objective to guide us, and then Joe and you, Peter, you both said, well, aesthetics, which a synonym is beauty or elegance,
but yet you both find different aspects of the world, beautiful and elegant. And so that doesn't converge. Yeah. So one thing where I can, can I come say where I think we might, um, where I kind of both agree and disagree with Peter is that the species that the bits that when you get to the real world, that you lose a lot of this beauty. But so what I would say is that the tour to talk about the beauty and the aesthetics, it's talking about the, and this is an adjustment in terms of the theory.
not necessarily in terms of the solutions. So that, for example, if we were going to talk about simple gravitational things, you'd say, well, okay, a sphere, a sphere is a very nice, aesthetically beautiful and simple object. But if you want to talk about the Earth, for example, then it's very important for the history of humanity that there are kind of there are continents that there are some continents are more separated than others. And then you have to get into the very much the specific weeds of
These are the precise details of the actual realization and you know no actual planet is just a perfectly perfectly straight. So in this way my aesthetic judgment is relating to the theory and you know I agree with Peter that if when you try saying well now you want something to look as close to the standard model as possible.
It's no longer the kind of maximal beauty and simplicity of, for example, maximal, maximal, you've got some kind of messy compactification. Yes, there'd be some kind of the fact that the standard model might become some particular contingent detail detail of that. So in that sense, I kind of I agree with Peter, but then I disagree because my aesthetic judgment relates more to the
The issue is more about the kind of structure of the of the theory and the problem than about the actual solutions. You may have complicated solutions to it. But maybe I want to say one thing about this. This is something I did try and write about in my book and there was kind of a about exactly this question. How do you evaluate things when you don't
When you don't have experiment to keep you honest. And there's kind of a line from a Bob Dylan song that kept going through my head. It goes something like, to live outside the law, you must be honest. And I think what this means to me is that if you're going to do this, if you're going to not have experiment telling you whether you're right or wrong, and I'm going to rely upon aesthetic judgments or your own
judgments of what's really consistent, of what's really a compelling idea. You really, really have to be very honest with yourself. It's very easy to fool yourself. It's extremely easy to fool yourself that some idea is beautiful and wonderful and even when, you know, as you learn more about it, you find out this is really not such a great idea. And this is actually kind of what
I see as one of the fundamental problems of how string theory has been pursued and especially the problem of hype. I think the whole field of fundamental physics and especially string theory has just suffered a lot over the decades from this kind of, to put it bluntly, a lack of honesty about what has really been going on here. It's very tempting. It's very easy for people to go out into the world and write books and have
TV programs and promote, you know, so everything here is so great. But, you know, it's doing that is very, very dangerous if there's no experiment to keep you honest and you really need. Anyway, anyway, so the whole subject really, really kind of needs some kind of much better internal structure of kind of. Acknowledging when things aren't working.
and keeping track of what really works, what really doesn't work, and kind of not running out and issuing press releases from your university about how great something is, about what's going on when it's just not. So that's been a large part of my kind of feelings about the subject over the years. So here I'm going to come in, I'm afraid if you want to fire here, at this point I'm going to largely agree with Peter that
The I think like I said earlier about, you know, kind of, you know, intellectual ambition, intellectual, arrogant, arrogant, arrogant, strong personalities. Now, I think even though this, yeah, this may not literally people are necessary, quote unquote, nice,
But I do think that is always kind of a part of, you know, a necessary part of making progress in fundamental physics. But yeah, but ideally, you have experiment that kind of, you know, can kind of tame this, as Peter says, that the, you know, the thing that experiment is telling you you're wrong, and this has something to do with and this has an ability to because to tame, you know, strong personalities, people are strong, strong personalities, you know,
intellectually very self-confident and experiment does have an important role in taming that and keeping everyone on the straight and narrow and I think there is a kind of a structural danger so in terms of how you make so I said earlier on in terms of the kind of are things optimized to make progress and I gave that that a C and I think there is a definite danger when you lack experiment as the as the time and then you have the danger of hype where people you know
You have prominent newspapers, people send press releases from newspapers, prominent newspapers write big articles about writing things up as massive progress, which in reality are not massive progress in nature. And in the long term, the subject suffers because if people get the sense that you are not communicating honestly to the public about what you have done and what you haven't done, then
in the in the long in the long term you suffer and this is why yeah this is why i said when i come back to this thing you said well there is no direct experience i think it's important to say that because it's true and we've got a responsibility to the public to communicate honestly and i also when i say that i think string theory is an extraordinary strongly deep and rich intellectual structure and i think it is probably part of nature and i also am saying i'm putting that equally up there with that there is no direct experimental evidence please because i think both of these are true statements
But when you go to the public with press releases or articles in newspapers or these kind of very kind of puff write ups by certain kind of online science magazines, then that does damage broader confidence in the subject and broader confidence in the Academy. Yeah, Scott Aronson was just interviewed.
alongside another professor of quantum computing i believe is a professor or researcher in quantum computing and then that researcher was saying look i don't feel the need to counter the hype in this field all i care about is that if i'm correct or incorrect when i publish something is it correct that's what i care about and then scott quit he said well the fact that you don't feel the burden just doubles the burden of other people yeah okay so
I think string theory is
an abundant source of rich ideas for how you go beyond the standard model of particle physics. And if you read Preeti's blog, he would generally say that this sort of stuff is all a waste of time. And it's not what you were doing. So this is an area. I think string theory is an abundant source of rich ideas. So I think about how you think go beyond the standard model. And I think, yeah,
The common critique that you'll hear on places like Twitter is that those who critique string theory, they just don't know the subject. They're uninformed. They're not bright. Peter's clearly none of these adjectives. Well, bright people who are informed can also be wrong. Yeah, that's not in itself. That's not a particularly strong point to say that somebody is bright and well informed to say that therefore.
Well, yeah, anyway, I think my disagreement with Joe, actually, I've, you know, it's been my long standing disagreement, kind of, kind of since the beginning and over the long term, especially like with my, with my colleague, Brian Green, for instance, you know, it was always that not that I just always thought, okay, you know, he's got some enthusiasm for a certain picture of a world for a certain set of ideas. And I, you know,
I look at them and from earlier, early on, I lacked this enthusiasm and as years go on, it just kind of looks, I feel more and more justified for this lack of enthusiasm. So the big difference you're seeing between us is really just, we're looking at different kinds of, trying to see a way forward to a better theory, a better understanding. There's certain
certain set of ideas involving string theory, which, um, you know, some people, people significantly smarter and harder working than me, you know, I find very, very, um, very, very compelling. And it's, you know, part of it is also that I've got, I've always, because of my own particular interests and the way I've learned the subject, there are always different things which, which seemed to me kind of most intriguing and most promising. And, uh,
And, you know, for many years when I would write about this, I kind of felt that, well, I've only got kind of the vaguest, if people ask me and put me in this spot, is I've only got kind of the vaguest ideas about, you know, maybe you should be doing this kind of thing, not what you're doing. And now I feel I have something much more specific to point to, but it's, um, anyway, we come from different backgrounds. We've, we know different things. We, we sit, we see,
We see this whole problem and this whole structure, everything in a different way, so people quite legitimately are making their own decisions about what they think is the most promising thing to do and to think about. Can I come here? I'm going to try and express a criticism, which I think I've heard Peter make and I've certainly seen other people make, and then I want to explain why I think that criticism is wrong.
So the criticism would go something like this. If you're trying to connect string theory to particle physics, then you need to compactify the extra dimensions onto something like Calabi-Al. There are something like 500 million known Calabi-Als.
The number of ways when you do this to sort of ensure that what I call the moduli are stabilised, that the kind of geometry is something stable, you often need what are kind of fluxes. And if you don't know the details, it doesn't so much matter. But let's say which common ground, which I think we will agree on, that there are an astronomically large number of ways, the number 10 to 500 is often quoted here, for turning these fluxes on.
So the argument that is then given is you want to connect string theory to particle physics by compactifying on a Calabria. There are something like 500 million, however many, Calabrials. There are something like 10 to the 500 ways of turning fluxes on. There are something like 10 to the 500 possibilities for what you are doing. Every single one of them will give you different low energy physics.
You've no possible chance of finding the correct theory. You would never know if you do. This is worse than the needle. Every compactification will give you different physics. Therefore, you're not going anywhere. There is no kind of intellectual value or worth in what you're doing. Joe has done an excellent job of channeling me or people with this criticism. Go ahead.
And actually, that's going to be the preamble to the next Ed Witton, what everyone should know about string theory. So then what I would say is that it's not that there are various aspects of the physics of these compactifications are actually universal that across these 10 to the 500 of these for all these boxes, that there are certain things that are kind of always present. So that, for example, one of the things I've worked on a lot is the presence of what's called relatively like modular. So these are particles whose essentially all interactions are gravitational strength.
And these can have profound impacts on early universe cosmology. They can come to dominate the entry into the universe in lots of, you know, you very often get the thing, the idea that the universe could be filled at an earlier set. So the universe is unconstrained roughly for about 30 orders of magnitude in time, about half its lifetime and logarithmic scale between inflation and nuclear synthesis. And these regions, this period of the universe, for example, could be entirely 100% dominated by string theory particles, by moduli.
And the presence of such a module is completely ubiquitous across these 10 to the 500 compactifications. So what I would say is another thing is that it's not actually true that the particle physics is all different. There are lots of aspects of the physics that are actually broadly universal across these things. These lead to very interesting modifications from, for example, the standard cosmology. Such modifications are reasonably well motivated and
they could really be part of the history of this universe and therefore it is right and proper to do as i do and other people do to say what signatures could these give rise to how in principle could you look for these how in principle could you detect these how in principle could you say that the early universe
In this period where it is currently observationally unconstrained, we don't know half the history of the universe on a log scale. How do you look for the physics of what happened in that time? And the string theory suggests lots of interesting things that could happen there and these are very worthwhile things to think about. So that is why I think the criticism is wrong.
Your fundamental problem with that is that no one is, I mean, you're correct that these issues about moduli and seeing effects of moduli is a generic issue in these kinds of theories, but you're seeing it as an opportunity and it's a legitimate thing to do to go out and ask, can we actually see these things? But you're still stuck with the fact that we haven't seen them, right?
You'd be in a much better shape if there were a couple of fields out there which looked like moduli fields and then you'd be in much better shape.
Yeah, I mean, here, this is kind of this is coming back to the thing that I think the thing that particle physics really as a whole has missed over the last few decades is really striking new data. And data is the foundation of the subject. And in this I include then, there's lots of particle astroparticle physics, for example, the search for dark matter, for example, for example, as well. OK, so then given this lack of data,
Peter, you mentioned that one of the problems of the way that fundamental physics research is conducted is this lack of honesty. Are there other issues? Well, I don't mean that there's a lot of, there's, there's a lot of different, anyway, there's, it's a very complex, it's a complicated step, but there's a lot of interest, there are a lot of different things to say. I mean, one,
There when the issue, we've already dealt with a lot of these. I mean, one is I think the kind of the kind of career issues about how you, um, and, you know, I, I understand, you know, I think Joe's right that there, there are related problems in other fields, but, but, but there are some races that this is exceptionally bad and exceptionally a problem in fundamental physics in general, that yeah, that there, you know, that if you, if you are an ambitious young person, you want to do something new in the subject, you know, how,
First of all, it's very, very difficult to come up with a good idea, but the other question is, it's also very, very difficult to find a way to support yourself in a job and to fit into the funding structure as currently. Can I just come here? So one thing I'm sure Peter will agree, so one criticism you sometimes hear of string theory,
is that string theory is robbing all the money that should be going elsewhere. So I think it's worth making completely clear that the amount of money that goes to particle theory as a whole is a tiny fraction of what goes to experimental particle physics, which is a tiny fraction of what goes to condensed mass physics, which is a tiny fraction of what goes to medical physics. The idea that if you consider the science funding pot, that somehow there's a huge chunk that is going to string theory or any kind of fundamental particle physics is
That's really not not the actual problem. I think maybe maybe a good way to focus on the actual problem I think is to be an experience which I think Joe's probably had I've had in that
More on the math side is, you know, when you're when you're an academic department, you know, part of what you do is hire people and try to reproduce yourself. And so you're you're sitting there looking at these these folders of people's applications and and you have to decide, you know, who are who are we going to hire? And it's in a I think I think it's kind of the problem is, is that the people do
Put in that position in theoretical physics, at least to my mind, they have a lot of applications. They have many, many talented people with very, very good credentials coming from very well-known places. If there were a lot of jobs out there and it was hard to hire people, if somebody came to you and said, well, I'm not
I'm not working on the latest, the ideas that got all the attention, I'm doing something a little bit weird on my own and if there's something I'm trying to do, you might hire them just because they were better than the, they seemed a bit smarter than the other people. The problem right now is if you're looking at this stack of folders of very smart people with these very, very good letters saying how brilliant they are and who are quite talented, what happens, at least I'd be interested to hear what Joe says about this,
In my experience, people then say, okay, well, now that we have this stack of these very good people, we can kind of focus on people who can come here and can be part of what's currently the kind of leading edge or the latest, hottest new idea. And so you end up with a hiring system where people have to be
They have to be really both smart and talented and do everything right and they have to kind of seem to be saying something about the newest hottest idea in order to get a job. I don't know what your reaction to that is, Jim.
One thing I think, I think there's a difference between sort of US and European hiring. So for good or real, it can work different at different times. I think that is more true of US hiring than European hiring. I think European hiring is more willing to, tends to be less kind of fashion,
I say fashion driven sounds slightly as it's necessarily a bad thing but the kind of positive side of this is sometimes you know problems that need a lot of a lot of progress is to be made and by just throwing a lot of people at this problem and hiring everything the problem you make an awful lot of progress quickly. So I don't know it's not necessarily true but for good or ill I think what you're describing where people have to be working on the latest hot idea is more true of US hiring broadly than your European hiring.
Yeah, I think also one thing just I want to say is about the video was talking about written in the Fields Medal and the idea is the idea that good scientific fields, you know, aren't surrounded by kind of high walls, they're surrounded by kind of very low, you know, boundaries, you can step easily over. And so the idea that kind of people are string theorists or not string theorists,
is really kind of not true. People can work on many, like myself, on one level I'm a string theorist. I've also done work on kind of searches for axioms with x-ray astronomy. I've got these various, you know, different legs in kind of like things like cosmology and astroparticle physics. On the more formal side, you have people you could call them string theorists, but you could also say they're kind of quantum field theorists. You know, there's been lots of kind of reasonably active areas in quantum field, for example, the bootstrap, for example, which has
Relative huge connections with strength and the idea that people aren't on strength theory or off strength theory. It's also something you're in and out. I mean, good fields are healthier. People can kind of wander across between what's tightly you could call strength and what's not strength. I mean, I think the more broad thing is, are you are you having things which are
into, you know, to maximize the conditions for intellectual creativity and intellectual productivity and for kind of, you know, and for interesting, you know, and important ideas to appear, you know, which also, I think the other thing you're saying is that you often can't tell on a one year time scale or two year time scale, what are the most interesting and important and important ideas? Yes, because I when I was talking about I've seen this happen. I mean, to some extent, this also happens in
in mathematics as much the same thing but but there you know when you have a very healthy subject where you know the things which are kind of the hot topics or the fashion or whatever are actually really legitimately kind of exciting and major sources of progress it's it's a perfectly reasonable thing to be doing and academia moves along quite well when you if the kind of if you've kind of gotten into trouble and if the fashion driven things are not really working then it becomes more of a problem
but maybe to get to something else that related to what Joe was saying. I think one of the more disturbing things I've seen happen in this subject over the years has been this kind of, um, you know, this business of, you know, who's a strength theorist and who isn't a strength theorist. There's this weird way in which it's become kind of tribal and that, you know, people feel that, you know, you know, either you're a strength theory, either you're part of the tribe or not of the tribe.
And if you're a string theorist, then you have to defend string theory against these outsiders who are going to kind of coming in and trying to steal your funding and your jobs. And I kind of noticed this most when I was kind of starting to write about string theory. It was really kind of shocking the extent to which
You talk to people and they would say, yeah, you know, I more or less agree with you or agree with you a lot, but, you know, I wouldn't dare to say any such things publicly because that's going to get me in trouble. You know, I'm not going to, I'm going to have trouble with my next grant for my students having jobs or, you know, this is, you know, this has become kind of a toxic situation where you don't want to, you know, you don't want to, you don't want to be caught saying the wrong thing and, and that people in my tribe are all of a sudden going to want to get rid of me.
And then I realized after I'd started the blog at first, I was thinking, well, you know, anonymity is important on the blog comments because it means that, you know, people who are wanting to be critical of string theory are going to be able to, um, to do so without retribution. Um, and then after a while I realized that the, the way things were going, there were string theorists also needed anonymity. Cause if you were a string theorist and you decided to kind of come and comment on my blog and
and forcefully defend the theory, then you know, then you may offend people from the other tribe and you may get in trouble and you don't want to do that either. So it's a, it's been, anyway, it's something actually, you know, quite bad intellectually to make it, to have it be so difficult to actually, you know, have these kinds of discussions. Yeah. So I do recognize some of the dynamic you're talking about the idea that it is
Coming back to the idea that you have some number of people who are very powerful at certain elite universities in the US and people don't want to criticize them or they don't want to criticize their papers or they don't want to say that this paper is wrong and because people either fear and rightly that their career will be impacted.
I don't think it's an entirely healthy dynamic and this is why experiment is
So good when it's working properly because experiment is the thing that it doesn't it doesn't it doesn't matter whether you're the, you know, whatever name distinguished professor of, you know, be a big shot physics at Big Shot University experiment just comes along and says your theory is wrong. Now, before I move to the closing remarks or closing questions, I want to ask, what is the role for multiple time dimensions in physics?
Okay, so there are various questions that I think are fair to formulate. So these include like, why do we just experience one time dimension? Why does time run forward? Why are the equations of quantum mechanics what they are? Why the Schrodinger equation is what it is?
I think it's fair to say that even if you're doing things like the most profound theories that we know of, these are not answered questions. In the same way you say why are the equations of quantum mechanics what they are, ultimately you're just going to come back and say well this is what they are. So multiple time dimensions, what role are they? None as far as I'm
aware, but I'm also aware that this is not a very studied, this is not a very studied, yeah, why do conscious brains, why do we perceive time moving forward? Well defined question, but also one that I think we do not really, what not really study and for good of real do not do not spend time thinking about. Yeah, maybe just to say something related to what I have been thinking about. I mean, so in some sense, a lot of what I have been thinking about has been the relationship between
the Euclidean signature and the Minkowski signature theories, which in some sense you can think of it's the difference between having zero time dimensions, I mean, just four space dimensions and one time dimension. And anyway, there's, I think there's a lot of amazing mathematical structure there, just thinking about four dimensions about this relation between zero time and one time. The thing, and how this works out with spinners and twisters and everything, the one thing
It kind of bothers me a little bit that I still don't know what to think about is that if you look at the possibilities in four dimensions, you know, because you have your choice between what's, you know, in the metric signature, what's positive, what's negative, but you basically got three possibilities, you basically got kind of zero time dimension. So all four positive or all four negative, and you've got, which is where things are kind of nice mathematically, or you've got one time dimension, which is
one positive or one negative, and that seems to be where we live, and that's when Caskey saves time. But there's also this possibility of two positives and two negatives to have this split signature of signature two-two in four dimensions.
In some sense, the whole story about spinners and reality and everything actually works most nicely in that story. So everything I'm thinking about, there's clearly a story happening over there in this split signature. But as far as I know, it has nothing to do with the real world. And again, it's this problem of, if you're purely thinking about mathematical beauty, I'm very tempted to go think about that 2-2 signature case.
I just can't see any possible conceivable relation to any question about the real world that I know about and someday somebody may tell me one but um but anyway that that's the only way this topic has come up in my own thinking. There's something I just like to put in which I kind of wanted to say it's about the kind of relation between hype and then ultimate intellectual substance I mean it's
Even if there is some hype-ridden press release about something that isn't really very substantial, that doesn't take away from the existence of the actual subject, the actual is an intellectual coherent thing, the existence of things. Peter was referring earlier, both completely agree with me about, for example, mirror symmetry, there are lots of these things which are just there and they're correct and they're lasting and they're extremely deep.
it areas mathematics for example there there areas which for example like finite group theory is one of these areas where at one point there was a lot of work and i think the subject basically was exhausted because all finite groups were classified and yep that doesn't mean the fact that there are there aren't lots of new results in finite group theory is not a is not a criticism of the kind of the intellectual value or validity of that it's just that sometimes you find something that which are really deep and profound and you find and you
I am very strong in my defense of the intellectual value and lasting validity of string theory. I'm much more nuanced about whether everything right now is kind of optimized for an environment that creates maximal progress, but my defense of the underlying theory itself is completely unqualified.
Peter, how much of your criticism towards string theory would be removed if string theory was classified as mathematics and not mathematical physics?
It's, um, yeah, you know, anyway, anyway, that the problem is kind of what people mean. Maybe I have my own views on my own, which I've been kind of accused of being kind of semi mystical in the sense that I believe that deep physics and deep mathematics are heavily intertwined and are in some sense, maybe even will turn out to be the same thing. Um, so it's not, um,
I don't know how to say this, but maybe I'm going in the wrong direction with this, but just to say that the thing that I really dislike hearing is saying that, oh, the problem with string theory is that it's mathematics, it belongs in mathematics environments. If you look at something like ADS-CFT, there just isn't any particularly deep mathematics there. That is not
That does not belong in a math department. Mathematicians might be able to tell you something, but it's an idea about physics and it needs to stand or live or stand as an idea about physics. And it's true of a lot of string theory and the things, there's a complicated relation, but this idea that, oh, string theory is just mathematics. That's really kind of a wrong way of thinking about it because it's not, and mathematicians have a very,
Our field has its own structure and it's only doing, and this is, no mathematician would say that this is true, oh yes, string theory is just a natural part of math departments. That's really not the way it's, the way things are. I think there's a, yeah, I think there's a cultural, there's a,
Often people start off with that young and they're good at stuff, but then there is a very big cultural difference between maths and physics. And I think one of the, Edwidge is one of the very few people who's really been able to speak both languages almost like as a native speaker. I think most people are either physicists or they're mathematicians and there's actually quite a deep cultural difference between the two. Yeah. No, anyway, I think anyway, it's been one of the great fascinations of my life to see both communities and to
There is a fascinating relation between the two. They are very different. They have different histories. They have very different ways of thinking about things, but I think they are also in some ways deeply related. It's a fascinating subject to see the interrelation between the two, but the idea that the problem with strain theory is that it's been improperly categorized and should be mathematically is just wrong.
Well, speaking of mathematicians and physicists, a large portion of this audience are either professors or academic researchers in math and physics, and then another large portion are people who are becoming researchers. So, Joe, what's your advice to young researchers, people entering the field? I'm sure you'd want to skip the existing researchers. To learn, you know, to learn whatever part of the subject you want to learn it properly.
So try and avoid the kind of popular science books and learn quantum field 3 properly, learn GR properly. Then that gives you the position to make informed intellectual decisions about what you really want to study. And in terms of research, I think try and
Just to echo famous advice by Weinberg, try and be in areas that are messy rather than areas that are clean. Peter. Well, I mean, the one category of student I often get to meet and talk to are people who are interested in both math and physics. And the standard kind of advice I give them is at least in the US, the US job situation that I'm most familiar with.
If you can't decide between the two and you like doing both, you probably should go to graduate school and try to have a career in mathematics. It's a lot easier environment. The ratio between really, really smart people and jobs where you can actually think about what you want to think about is much better in mathematics. That's a little bit of
Just kind of practical advice. It's very hard. I think it's a very tough situation for students who really understand very well. They're in love with questions about fundamental physics. They want to figure out how to do something with this, how to make their way. It is very, very tough. And the situation in getting a PhD in theoretical physics, trying to find a job, is quite difficult. I don't know of something that I have really good advice.
It's an extraordinary privilege to be able to think about these areas and the worst thing that can happen is someone has to kind of like quadruple their salary by going and working, leaving the subject and going and working somewhere else. I should say also that seeing what's going on with students these days, most of them are very worried about and thinking about what's going on with AI and what's going on with their own
Yeah, it's quite possible that we're going to be, you know, we're on the cusp of these, these kinds of research and these kinds of fields changing quite a lot, because in some ways driven by AI, if only whether or not for intellectual reasons, but if only if only that's where all the money is going to is coming from. And so, you know, I mean, mathematicians are very much, I don't know how much effect is having in physics, mathematicians are very much
starting to debate the standard ways in which we've done mathematics research in terms of writing proofs and checking proofs. Should we start using automated theorem checkers or provers? What is it? In some sense, mathematics research looks like it's something that AI might actually really be able to do
It's possible I can do it as well as or better or I can teach mathematics probably better than the rest of us. So what's what's going to happen there? So I'm curious if Joe has any if you see this in physics also how what is the AI going to have an impact on people's careers? I don't have a I mean I do I do feel that undergraduate level we need to have a
Very clear, you know, there needs to be a very clear thing as to the traditional, you know, where there's a lot of calculations you do by hand. Yeah, so it's important to understand how calculations work, but I think one has to kind of review, revisit all this and think, is this in the same way we don't use slide rules, we have calculators and think about, as we're training people for the future, learning how to do complicated integrals by hand.
Is this the right skill set? Perhaps it is, perhaps it's not. But to think about. In terms of solving problems, whether. We just kind of get the old methods are still the right ones, but I don't have a clear answer. And lastly, Joe and Peter, what are you excited about research wise in the near future? Starting with Joe. So if I talk about the subject as a whole, myself, so your own personal.
research. I want to talk about both because if you're intellectually you need to talk about both I think. So the subject as a whole I think gravitational waves is kind of across the spectrum of fundamental physics I think is the single most kind of interest you know it's like it's 10 years after the birth of optical astronomy in 1620 you know we're really at the very birth of gravitational wave astronomy and this is going to be the ability to look at the universe in ways and this also ties to what I'm going to talk about myself
which is this question of what was the universe, this period between inflation and big value synthesis which could cover 30 orders of magnitude in time and which is observationally unconstrained, how
Peter, what are you excited about? Well, I mentioned very specifically the stuff about
This, but maybe there's one to connect it to the larger field. There's some, and again, in my mystical feelings of the best physics and mathematics, deepest physics and mathematics are connected. I mean, the, perhaps one of the most healthy fields in, if you want to say kind of fundamental mathematics has been these ideas about arithmetic geometry.
It's a story with a long history. How do you think about numbers and arithmetic geometrically? There's in some sense these things like spaces whose points are primes.
It's a long and beautiful subject. It's been making a lot of progress recently. A lot of this goes under the name of this Langlands program. A lot of the questions are really about these deep questions about the symmetries of the integers and of numbers. Anyway, there's just been a lot of progress on this. To my mind, I probably spend much more time, I'm in no sense an expert in this field.
I'm kind of, but I'm kind of fascinated by it. I probably spend more of my time learning about it or trying to learn about it than I should for, I should be probably doing things I'm better at. But it, um, yeah, anyway, I think that's, that's a part of mathematics, which is really quite healthy. It's, it's moving forward quite, quite quickly. Um, and, and these most recent developments go along, kind of bring together some, these are these ideas about arithmetic geometry with ideas about, um,
What's called geometric Langlands and which actually have a lot of interesting historical connections to physics. So when Witten and people were thinking a lot in the late 80s about things, ideas that came out of conformal field theory, that the mathematics that they were developing was taken over by a lot of mathematicians and turned into this, became this field of geometric Langlands, which is quite
Quite fascinating. And we're starting to see, especially through Schultz's work, a kind of bringing together of these geometric ideas from so-called geometric Langlands and then this arithmetic geometry ideas and to bring it in number theory. So it's fascinating to watch. And the thing which also kind of fascinates me, and I don't really quite know what to think of, is that in these ideas I've been thinking about, about physics, of twister theory, there's the notion of a point
As I said, it's kind of a, you should think about a point as something that's called the twister P one and it's a CP one complex projective one space, which is a sphere, but with, with opposite points identified in some sense. And that's called the twister P one. It's, it's one of the fundamental things that shows up when you do, um, twister theory and physics, but especially if you try to do it in Euclidean signature.
But the most kind of thing that's completely amazed me is if you look at the recent work on trying to bring geometric and arithmetic Langlands together, you know, Schultz and others are, you know, finding that, you know, if you, if you look at a different point, if you look at different arithmetic points, which are primes, you find an interesting structure that's called the Farg-Fontaine curve. But if you take, um,
If you sometimes take the point off to infinity and if you if you look at the real numbers, the analog of the Faraday-Fontaine curve is the twister P1. So this exactly the same mathematical structure that I'm seeing is really, I can really do something if I think of points physically that way. You know, Schulze and others have found that, you know, thinking of
They're more advanced notions about geometry and how to bring them together. The number theory, they're also finding the same twister P one, the same structure showing up. So it's, you know, I don't know what to make of this other than it, it make, you know, my deep belief in the mystical connection of everything at the deepest level seems it's probably, this is probably some vindication of it, but I don't know anyway. Well, thank you both for spending
Two and a half hours on the subject of how do we advance fundamental physics and the state of string theory before we leave why don't you summarize Joe what is it that you agree with Peter about and what is it that you disagree with him on. I think we yeah I think we disagree on the
Yeah, the overall intellectual substance of strength theory. And I think we agree in thinking there, you know, there are some kind of problems in how things are kind of, you know, organized and, you know, in terms of actually making kind of intellectual progress in fundamental physics at the moment. That was that's how I see it. And Peter can tell me whether he Yeah, yeah, more or less, more or less. Right. Yeah, I think we finally
Our fundamental disagreement is, as we discussed, is more just about trying to see forward what is a promising direction to move forward with this. We just see that question very differently and we see string theory's role in that very differently.
Thank you all again. The books are not even wrong. So that's Peter White. That's your book. You also have a book on quantum theory groups and representations. Joseph, your books are why string theory from 2015 and origins, the cosmos inverse. Those are on screen. All of these are on screen and in the description as well. Thank you so much for spending time here on this subject of fundamental physics. Thank you. All right. Thank you. Thank you. That's it. That's wonderful. Thank you. Thank you. Merry Christmas.
Don't go anywhere just yet. Now I have a recap of today's episode brought to you by The Economist. Just as The Economist brings clarity to complex concepts, we're doing the same with our new AI-powered episode recap. Here's a concise summary of the key insights from today's podcast. All right, let's jump right in. Today, we're taking a deep dive into a couple of episodes of Kurt Jemangal's theories of everything. Oh, you know those.
Those hardcore physics discussions, PhD level stuff. Exactly. Jay Wangal really gets into the weeds with his guests. And you know, he's got a serious math physics background, so he really pushes them. Yeah, he's known for going deep like weeks or even months of prep before he even sits down to talk with them. So today we're looking at two physicists with very, let's just say very different views on string theory.
Yeah, Peter Wojt, who's a pretty well-known critic of string theory, and Joseph Conlin, who's actually a big defender of it. It's a fascinating clash of perspectives, and right off the bat, Jim McGaul asks them both to grade string theory. Like a school grade. Yeah, it's almost like a playful way to get things started. I like it. It gets right to the point. Totally. So, Conlin, he gives string theory a big A+. Wow, high praise.
He's really enthusiastic about his potential, you know, for the long haul. But then White, he just throws down an E-. Ouch. That's rough. Right. I mean, that's practically failing the theory completely. So what creates such a huge divide between them? Well, that's what makes this deep dive so interesting. It forces us to ask, like, what happens when these brilliant minds
can't even agree on the basics. It's fundamental, right? Like what are we even talking about when we say string theory? Yeah, and that's actually one of the first things they get into. They both kind of agree that string theories become this fuzzy concept. Fuzzy how? Well, White, he points out that a lot of research that gets labeled string theory
isn't really
And this is where it gets really tricky, because if we're trying to evaluate string theory, but we don't even know exactly what it is. It becomes really hard to judge, right? Like, how do you grade something that's constantly changing? Exactly. And this isn't just an academic problem, it's a fundamental issue in physics, especially when you don't have any direct experimental evidence. You're talking about, like, how do you know if a theory is right if you can't test it in the lab? Right.
And that leads them into this really interesting discussion about add SCFT correspondence, which is this big area of research in string theory. Now, add SCFT, that's something I've heard a little about. It's about a connection between different dimensions, right? Yeah, like a duality between a theory of gravity in a higher dimensional space and a quantum field theory in a lower dimensional one. But Wojt argues that this focus on add SCFT is
kind of leading physicists down a rabbit hole? A rabbit hole? How so? Well he says they're getting too caught up in these like toy models. They're mathematically interesting but they might not have anything to do with our real universe. So it's like they're playing with theoretical Legos but not building anything real. Exactly. And he even brings up this recent paper by Ed Whitten. Whitten? He's like a rock star in the physics world. Right. But White sees this paper as evidence
that even the top minds in the field are getting lost in these abstract, low-dimensional models. Like even Whitten's getting sucked in. Okay, so one guy says Ad SCFT is leading physicists astray, but what does the other guy say? Well, Colin, he comes back swinging. He defends Ad SCFT, calls it a profound discovery. He argues that even if it doesn't directly describe our universe, it's still valuable for understanding fundamental physics.
Interesting. So even though they disagree about at SCFT, they both have strong opinions about it. Oh, yeah, for sure. But here's where things get a little surprising.
They both actually agree that there's too much hype around string theory. Too much hype? Yeah, like all these big claims about how it's going to revolutionize physics. And Conlon thinks all this hype is actually hurting public trust in science. I can see that. It makes it seem like physicists are all talk and no action. Right. And White, he goes even further. He sees the hype as a symptom of a lack of honesty in the field. Ooh, that's a strong statement. Yeah. He even quotes Bob Dylan. He says, to live outside the law, you must be honest. Hmm. I wonder what he means by that.
It's a great question. I think he's getting at this idea that when you're working in a field where it's hard to get experimental proof,
It's even more important to be intellectually honest with yourself. To admit when you're wrong, to question your own assumptions, that kind of thing. Exactly. And that's what makes this conversation so compelling. It's not just about string theory. It's about how we do science, how we evaluate ideas when we can't rely on experiments to tell us what's right or wrong.
Right, it raises those big philosophical questions about the nature of truth and knowledge. And then Conlon throws in this really interesting twist. He argues that string theory can make testable predictions. Wait, really? I thought that was one of the big criticisms, that it wasn't testable. Yeah, but he says that even without having one single unified solution for string theory, you could still get predictions out of it. And he points to these things called moduli. Moduli, what are those? Well, basically they're particles. Yeah.
But they're weird. They have these super weak interactions and Collins suggests that they might have dominated the very, very early universe. Wow. So we're talking like way back before even the cosmic microwave background. Yeah, even earlier. And he says that these moduli could have left behind traces, signatures that we might be able to detect in cosmological observations. So like fingerprints from the Big Bang. Exactly.
And if we could find those fingerprints, it would be a huge step towards connecting string theory to the real world. That would be amazing. Right. And that's why Conlon's so excited about it. He sees it as a way to finally bridge the gap between the abstract mathematics of string theory and the observable universe. It's like opening a window into the earliest moments of time. It's mind-blowing, right? And it shows you how even in the midst of all this disagreement,
There's still room for new ideas, new ways of thinking about the universe. It really challenges our assumptions about how the universe evolved. Like, we think we know the big picture, but maybe these tiny particles hold the key to understanding it all. Right. It's like, we're so focused on the big stuff, the galaxies and the Big Bang, that we might be missing the really important stuff. Exactly. And that kind of gets to the heart of this whole debate between Boyd and Colin.
White thinks string theory has gone off track, too focused on mathematical beauty instead of experimental testing. Like, he thinks they're chasing these elegant theories, but they've lost sight of how to actually prove them. Right. And Conlon actually agrees to some extent. He's worried that physicists are forgetting how to connect their theories to real-world data.
He makes this great analogy about muscles, like if you don't use them, they atrophy. Oh, yeah. He says you can't just think about walking. You have to actually do it. Exactly. And that's his point. Physicists can't just keep thinking about theories. They have to find ways to test them. It's like we build these incredible machines, but we don't know how to drive them. Yeah. And they both see this as a symptom of a bigger problem in physics, this disconnect between the theory and the experiments.
They're even critical of how research is done these days, like how everyone's trying to publish in these big journals and chase the latest trends. So it's like a popularity contest instead of a search for truth? Kinda, yeah. Conlon even says that hiring practices are different in Europe. Maybe they're not so focused on trends over there, which allows for more diverse research. So maybe there's more freedom to explore different ideas in Europe.
Possibly. And that raises the question, is this pressure to be trendy actually hindering innovation? Like, are we missing out on big discoveries because people are afraid to go against the grain? That's a good question. What would it take to create a research environment where people are encouraged to take risks and think outside the box? That's a tough one. But I think Boyd and Conlin would agree that we need to reward truly creative research, even if it doesn't fit the mold. Speaking of going against the grain,
Boyd brings up this idea of tribalism in physics. Yeah, like how some physicists agree with his criticisms of string theory, but they won't say so publicly because they're afraid of hurting their careers. Oh, that's kind of scary. Like there's this pressure to conform. Right. And he jokes that even people who support string theory might need to remain anonymous to avoid backlash.
So it's not just about the science, it's about the politics of the field too. Exactly. And this kind of division can really get in the way of progress. You know, people get so caught up in defending their own turf that they forget they're all on the same team. Right. Ultimately, they're all trying to understand the same thing, the universe. Exactly. But even with all this disagreement, Conlon makes a really important point.
He says that just because there's hype or criticisms around a theory doesn't mean there's no substance there. Like there might be some good ideas hiding beneath the surface. Exactly. He uses the example of mirror symmetry, which came out of string theory research, but has had a big impact on mathematics. So even if string theory itself doesn't pan out, it could still lead to valuable discoveries in other fields. Right.
And it shows you how interconnected knowledge is. You never know where an idea might lead. It's like following a winding path. You might not end up where you expected, but you'll discover something interesting along the way. Exactly. And then Jay Mongal asks Voight this really interesting question. He's like, would you stop criticizing string theory if it was just classified as math and not physics? Hmm. Trying to put him on the spot there. Yeah.
And, Voight, he completely rejects that idea. He's adamant this ring theory is about physics, and it needs to be judged as such. So for him it's not just a mathematical game, it's about trying to describe the real world. Right. He even pushes back against this idea that anything mathematically complex is somehow not physics. It's like he's saying, don't underestimate the power of math to reveal the secrets of the universe.
Yeah, it makes you wonder if we try to put things in boxes too much, you know, like physics over here, math over there, when really it's all connected. Right, like these rigid categories can actually hold us back from making real progress. And that kind of brings us back to this big question. How do we judge a theory when we don't have experiments to tell us if it's right or wrong, especially in these really abstract areas of physics? It's like we're stuck between these two different ways of doing physics, one that values beautiful math,
And that tension is really strong in fundamental physics, where we're dealing with things that are so far removed from our everyday experience. Right, so maybe we need to rethink what we mean by
good physics in those areas where our usual methods don't really apply. Yeah, maybe we need a new approach, one that combines the elegance of math with the grounding of experimental data. Because in the end, it's that interplay between theory and experiment that really drives science forward. And near the end of the conversation, Jaimungal tries to find some common ground between Boyd and Conlin. He asks them, like, where do you guys actually agree? Trying to bridge the gap, huh?
Exactly. And it's interesting because Colin, he admits that even though he and White have these fundamental disagreements about string theory, they both see problems with how physics research is done. Like the system itself is holding us back. That's what they seem to be saying.
Conlon even suggests that these structural issues might be a bigger obstacle than their debate about string theory. And White agrees with that, saying that they both think the current system doesn't really encourage innovation. So even though they're coming from different perspectives, they can still recognize these shared problems.
Which gives me some hope, you know? It means that there's potential for them to work together to make things better. It's like they're saying, hey, we might disagree about the details, but we both want physics to thrive. And that's really inspiring because it shows that even in the face of strong disagreement, there's still room for common ground and collaboration.
Because at the end of the day, they're both driven by the same desire to understand the universe. Right. It's that shared curiosity that unites them, even when their ideas clash. So as we finish up this deep dive into theoretical physics and the debate about string theory, we're left with a big question.
Could string theory still point us towards some deeper truth about nature, even if it doesn't describe our universe in the way we currently think? Or is it a distraction, like White suggests, leading us away from more concrete, testable ideas?
We don't have the answers, but I think what's important is that these conversations are happening. Right. It's the debate, the questioning that pushes science forward. Exactly. And I think these episodes of theories of everything really highlight the complexity of the questions physicists are wrestling with and the passion they bring to their search for understanding. It's a reminder that science is a journey, not a destination. And it's the journey that truly matters. Beautifully put. And on that note, thanks for joining us on this deep dive. We'll see you next time.
New update! Started a sub stack. Writings on there are currently about language and ill-defined concepts as well as some other mathematical details. Much more being written there. This is content that isn't anywhere else. It's not on theories of everything. It's not on Patreon. Also, full transcripts will be placed there at some point in the future. Several people ask me, hey Kurt, you've spoken to so many people in the fields of theoretical physics, philosophy, and consciousness. What are your thoughts?
While I remain impartial in interviews, this substack is a way to peer into my present deliberations on these topics. Also, thank you to our partner, The Economist.
Firstly, thank you for watching, thank you for listening. If you haven't subscribed or clicked that like button, now is the time to do so. Why? Because each subscribe, each like helps YouTube push this content to more people like yourself, plus it helps out Kurt directly, aka me. I also found out last year that external links count plenty toward the algorithm,
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"text": " This is an unprecedented conversation. Today we have Peter Wojt from Columbia University, known for his trenchant critique of string theory in Not Even Wrong, both the book and the blog."
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"text": " and Joseph Conlin from Oxford University, author of Why String Theory and a radiant defender of string theory. This remarkable and forthright exchange covers the technical ins and outs of a theory that's dominated fundamental physics for the past few decades in a manner that's never been seen before in podcast form. Both agree that the field of fundamental physics faces structural problems in how it trains new generations and evaluates competing ideas,"
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"text": " yet they diverge drastically on whether the problems string theory solves are indeed problems it solves, whether it's as elegant as people suggest, and whether it's unparalleled mathematical divination, foreshadowing, for instance, mirror symmetry and modularity of partition functions,"
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"text": " actually signals that string theory is on the right track or a seductive dead end. Many in the public jump on the string theory bandwagon either being for it or against it without knowing the details of what they're supporting or criticizing. That's why it's thrilling to bring this conversation to you. My name is Kurt Jaimungal and on this channel I research mathematical physics and philosophy in front of you in podcast form, bridging these disparate subjects and making abstruse concepts digestible while not skimping on, nor being afraid of, the technicalities."
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"text": " Welcome to the podcast. Joseph Conlin, Peter White. Joseph, you're known in the popular sphere as a sharp defender of string theory and Peter, you're known as a sharp critic of string theory. Joseph, you have a book called Why String Theory from 2015 and Origins the Cosmos Inverse from a month ago, 2024."
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"text": " And Peter, you have a book called Not Even Wrong from, remind me of the year? It was published in 2006, I guess. It was written a couple years earlier. And both of those are on screen and the link are in the description. I recommend you check it out, especially the Why String Theory book as it's relevant to this conversation and Not Even Wrong. Although for a more poetic excursion into these topics, origins, the cosmos and verses is relevant. Now, many people are watching this expecting"
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"text": " Perhaps even hoping for disputatious and entertaining bickering. Now, I'm less interested in that, as you know, if you watch this channel, I'm more interested in how can we productively move theoretical physics forward with congenial generative technical exchanges. After going through both of your work, I found several lines of convergence. So how about I pose some of those questions first, and then we can get into your respective defenses and critiques of string theory. Okay, sure."
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"text": " So I think, so let me split those into what's kind of seems sort of definitely needing explanation and things where we also think there's kind of experimental chance in the near future. So things like the Yukawa couplings of the standard model, for example, the fact, you know, the electron-Yukawa coupling is 10 to the minus 6, there's three families and you've got roughly a kind of an order of magnitude or so, or two orders of magnitude or so."
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"text": " between them in terms of masses. So that's clearly structure not explained by the Standard Model and we need something more. But the thing which I think where there is most experimental chance to do something in the near future is that of what's called the strong CP problem. And this is an angle that's present in the Lagrangian of the Standard Model in the strong force sector."
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"text": " I think the general view which I also subscribe to is the best explanation for this would be that the angle is dynamical and in this case this leads to a particle called the the axion which could possibly be a part of dot matter and there is a lot of intense experimental work covering trying to think about how you would look for the axion in the various different regimes or masses and couplings it could have."
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"text": " The first thing to say about the standard model is that what's most amazing about it is how good it is, how successful it is. I think my point of view is different than many people's. I think it's actually something much closer to a final theory that really is perfectly satisfactory than what many people think. The things that are some basic facts about it, some basic aspects of it that really kind of"
},
{
"end_time": 399.224,
"index": 16,
"start_time": 369.377,
"text": " Just kind of cry out for some kind of explanation for where did that come from? I mean, one is the pattern of gauge groups and representations of gauge groups describing the matter particles, the forces between them. It's kind of a frustratingly kind of simple kind of structure, geometric structure, but with no explanation. Then, of course, as Joe mentioned, there being the Yukawas, what's causing and the whole general story of the Higgs, there's clearly something about the Higgs sector that we don't understand where this is coming from. Most of the"
},
{
"end_time": 412.022,
"index": 17,
"start_time": 399.787,
"text": " I guess,"
},
{
"end_time": 435.145,
"index": 18,
"start_time": 412.449,
"text": " If I wanted to point to something and I think there's some hope of getting some experimental evidence about in the reasonable future, I'd point more to the neutrino sector. That's a very funny story and the story about neutrino masses and the story about a right-handed, possible right-handed neutrino field is something, again, it looks like where there's something that, both something we don't understand and something going on and"
},
{
"end_time": 462.824,
"index": 19,
"start_time": 435.538,
"text": " possibly is something we actually have some hope of getting experimental evidence about, about the axion. I guess I'm less fond of the idea that that's dynamical. I think it may be the reason that that term is zero may just have something more to do with our incomplete understanding of the quantum field theory that governs that. So the other ideas with the axion have been, for example, there's an idea that because it's equivalent to"
},
{
"end_time": 491.51,
"index": 20,
"start_time": 463.473,
"text": " you could tie it to relations in terms of the corkset, you could move things slightly about. So one of the things has always been that there's the intrinsic Yukawa of I think the up cork is zero, and that there's no and then in that case, the action ceases to be dynamic, there ceases to be a kind of a physical field, and you can solve the strong CP problem, because you can tie it to the phase of the corkset when there is no physical phase if the actual Yukawa is zero. I think lattice results tend to dis dis favor this, this explanation."
},
{
"end_time": 500.179,
"index": 21,
"start_time": 492.381,
"text": " And so to me, the action is it's one of these things which is kind of theoretically simple."
},
{
"end_time": 529.855,
"index": 22,
"start_time": 500.776,
"text": " explains the required phenomenon. To me, my judgment call is that this is something like the Higgs was prior to its discovery. It's the simplest and most minimal way of explaining the strong CP problem of the standard model. You can't say it's 100% guaranteed that there definitely will be an axiom, but to me it seems by far the most appealing and most likely explanation"
},
{
"end_time": 557.432,
"index": 23,
"start_time": 530.282,
"text": " Compared to the the other possibilities. Yeah, I just think I just think I see things somewhat differently partly because I I don't I think unlike you I don't see a good good candidate for a dynamical field for where that would come from. It seems to me an extra structure. I don't actually my original work in this year when I was a graduate student. I was working on lattice gauge theory calculations of topological charge and actually very specifically the whole in some in some sense"
},
{
"end_time": 583.166,
"index": 24,
"start_time": 557.756,
"text": " This was supposed to be a calculation of the theta dependence in pure QCD. It's been a long time since I've thought really seriously about this, but I kind of left that subject feeling that there were kind of fundamental things about the whole story that we didn't really understand. These arguments about theta dependence kind of make various assumptions about, for instance, they only make sense really in Euclidean space-time."
},
{
"end_time": 613.2,
"index": 25,
"start_time": 583.763,
"text": " They make various assumptions about quantum field theory, which are quite plausible and it's quite understandable you should accept them, but it's also quite possible that there's something we're missing there. One of my fellow students at Princeton at the time was a very brilliant physicist named Hidanaga Yamagishi, who unfortunately died relatively early in life, but he was always strongly of the opinion that there was a fundamental misunderstanding going on of the theta dependence problem and of this whole story."
},
{
"end_time": 630.418,
"index": 26,
"start_time": 613.712,
"text": " Not long before he died, he sent me some short papers he'd written about this. Anyway, I think there's at least some chance that the explanation is that he's right or that some version of that we're missing something about this because it's a bit trickier, I think, than people really actually realize."
},
{
"end_time": 650.555,
"index": 27,
"start_time": 631.459,
"text": " I'll simply, the answer is going to be experimental. Yeah, I mean, the good thing about, I think, with axion searches is there's a very active experimental program. There's a sort of a canonical line, you can do this sort of plot of kind of axion mass against coupling for the kind of the canonical values that would, where the axion would be expected to solve the strong CP problem."
},
{
"end_time": 677.432,
"index": 28,
"start_time": 651.049,
"text": " And I think it's generally true that things are not there, but there is a developed experimental program that is looking to just kind of bring down the couplings for which you can search for axioms with the aims of either discovering or excluding the axiom across this range of parameter space. And so I think ultimately what's going to happen is this parameter space is going to be covered and then either the axiom will be discovered"
},
{
"end_time": 701.8,
"index": 29,
"start_time": 677.875,
"text": " or if it's not discovered then I think it'd be reasonable to say then the question of is the axiom the solution of the strong CP problem would then we would then say well if it hasn't been discovered why not. But ultimately there's going to be an experimental answer to this and I think it's also likely to be an experimental answer to this in the next kind of"
},
{
"end_time": 731.732,
"index": 30,
"start_time": 702.602,
"text": " 10, 20 years, hopefully shorter, but there's a very active experimental program concerning looking for axioms across a whole wide range of masses and couplings. This is something I have worked on myself as well. So Joe, people know you also because of your one page paper. What is the direct experimental evidence of string theory, of which there's a single line and everyone's jealous that you were able to publish with just a tweet and it says,"
},
{
"end_time": 759.974,
"index": 31,
"start_time": 732.142,
"text": " There is none, something like that. Yeah, so that's actually in the book. That's in Why String Theory. So the books are like a 230 page book or something, which is designed as an intellectual kind of explanation of and defense of kind of string theory as a, you know, why so many people work on it and why my view is kind of such an intellectually solid and interesting thing to work on. But then one of the chapters is called Direct Experiment in String Theory. And this is the one page one page chapter."
},
{
"end_time": 778.763,
"index": 32,
"start_time": 760.282,
"text": " and if you if you take this in the context of the book you will see that what then follows in the next chapter is the question of well is there if there is no direct experimental evidence for string theory which is true there is no direct experimental evidence for string theory and it's important to be honest to the public and you know and say that because that's true then"
},
{
"end_time": 793.37,
"index": 33,
"start_time": 779.531,
"text": " One can, and I think one does, to then give this reason for why do so many people work on this, given that this is not something like QCD or something where you can say there is abundant experimental evidence that this is absolutely the correct theory of nature."
},
{
"end_time": 817.398,
"index": 34,
"start_time": 795.691,
"text": " So going through your work, Joe, I found four different critiques that you consider to be invalid. I found some critiques that you do consider to be valid. I'll talk about the misguided ones first. People will demand direct experimental evidence at the Planck scale as a prerequisite for taking string theory seriously. You don't think that's terribly valid. People dismiss string theory based on"
},
{
"end_time": 847.415,
"index": 35,
"start_time": 817.841,
"text": " Criticisms from people who have little to no expertise in the field and they probably don't know what richie flatness is or what that has to do with string theory So that's to be dismissed and then there's an over stating of the significance of the landscape problem without acknowledging that there are ongoing efforts to address it and That I guess this is a defense that that string theory is like the opposite of fossil fuels because you get these positive externalities where you provide tools and mathematical insights, so"
},
{
"end_time": 864.974,
"index": 36,
"start_time": 848.951,
"text": " Let me know if I summarized that correctly and then feel free to expand and then Peter, I would like to hear your thoughts. Let me address, let me come to some of these. So first of all, quantum gravity intrinsically, if you want to write things that go beyond the standard model, go beyond general relativity."
},
{
"end_time": 892.398,
"index": 37,
"start_time": 865.384,
"text": " So the number of people in the world with a technical understanding of things like quantum field theory or general relativity is kind of a relatively small fraction of the population. The fraction of the population who seem to have strong views on string theory and whether or not string theory is a correct theory of quantum gravity seems to be a lot higher than the fraction who have some sort of technical knowledge of say quantum field theory or general relativity."
},
{
"end_time": 909.428,
"index": 38,
"start_time": 892.841,
"text": " And so I think there is it is a bit odd to me that there seem to be far more people invested in the notion of what is the correct approach to quantum gravity than have on any reasonable level an ability to form a technical judgment about any of the issues"
},
{
"end_time": 933.575,
"index": 39,
"start_time": 910.162,
"text": " relevant to it. I'm sure Peter agrees with this because it's just. Yeah, undeniably. Actually, I did want to actually say it's hard to kind of overemphasize that these are complicated topics. And I do think Joe's Y string theory book is the best and serious kind of defense about this and addressing a lot of the issues that I brought up. So I find that yeah, I think a lot of"
},
{
"end_time": 964.343,
"index": 40,
"start_time": 934.48,
"text": " Anyway, first advice to everybody who wants a kind of a serious understanding of these issues is read his book. I think he actually did an excellent job of doing it much better than anywhere else. At the same time, you should also read my blog and my book and you'll get a different point of view. But it's hard to overemphasize how complex a lot of these issues are. I mean, these discussions that people are conducting on most ridiculously on places like Twitter are kind of just kind of absurd given the"
},
{
"end_time": 989.155,
"index": 41,
"start_time": 964.787,
"text": " Okay, so how about we get to the Brian Green question? What grade do you respectively give to string theory? And we'll start with you, Joe, then we'll get to Peter, and then we'll have this exchange of lobsome vitriolic aspersions."
},
{
"end_time": 1013.353,
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"start_time": 990.043,
"text": " As you know, on Theories of Everything, we delve into some of the most reality-spiraling concepts from theoretical physics and consciousness to AI and emerging technologies. To stay informed, in an ever-evolving landscape, I see The Economist as a wellspring of insightful analysis and in-depth reporting on the various topics we explore here and beyond."
},
{
"end_time": 1037.944,
"index": 43,
"start_time": 1013.797,
"text": " The economist's commitment to rigorous journalism means you get a clear picture of the world's most significant developments, whether it's in scientific innovation or the shifting tectonic plates of global politics. The economist provides comprehensive coverage that goes beyond the headlines. What sets the economist apart is their ability to make complex issues accessible and engaging, much like we strive to do in this podcast."
},
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"end_time": 1059.701,
"index": 44,
"start_time": 1037.944,
"text": " If you're passionate about expanding your knowledge and gaining a deeper understanding of the forces that shape our world, then I highly recommend subscribing to The Economist. It's an investment into intellectual growth, one that you won't regret. As a listener of Toe, you get a special 20% off discount. Now you can enjoy The Economist and all it has to offer for less."
},
{
"end_time": 1075.265,
"index": 45,
"start_time": 1059.701,
"text": " Thanks for tuning in and now back to our explorations of the mysteries of the universe."
},
{
"end_time": 1094.155,
"index": 46,
"start_time": 1076.681,
"text": " Okay, so I'll give it an A plus because you want to give it an A plus and then Peter can give it an E minus and then we can have some verbal. Okay, a grade for what? So like I said, there's no, I mean, a grade as a"
},
{
"end_time": 1120.179,
"index": 47,
"start_time": 1094.838,
"text": " Well, there's largely three families or particles."
},
{
"end_time": 1139.206,
"index": 48,
"start_time": 1120.452,
"text": " Number one string theory as a physical theory. Number two string theory as a production of mathematical insights as well as physical insights, but outside string theory. And number three string theory as a sociological phenomenon with its concomitant hype. So how about a different grade set for each of these?"
},
{
"end_time": 1159.275,
"index": 49,
"start_time": 1141.51,
"text": " Okay, so if you want so strict string theory on a time scale of kind of two or 300 years, you know, this is the question is string theory, a true theory of nature. So I'm going to say I think it is okay, high grade string theory, where is something there, where"
},
{
"end_time": 1189.36,
"index": 50,
"start_time": 1159.838,
"text": " As happened in, say, the Standard Model happened in the 1960s, 1970s, where you have this very close interplay between theory and experiment and the two drive each other forward. So on the kind of five, 10 year time scales, well, let's give it a D or an E because clearly that's not happening. The kind of question of sociology or string theorists, I mean, whether everything is optimally structured to create progress in the structure in the subject. So I'll give it a C."
},
{
"end_time": 1220.162,
"index": 51,
"start_time": 1190.435,
"text": " Okay, yeah, so I guess starting with the I think that the first one is where I mainly disagree with Joe I don't think I mean everything I've seen about string theory. I mean, I understand why people I understand what why is it why is it an attractive idea and why why some people that find it Have found it that way and and and believe that you know on a you know said sooner or later this is going to turn out to be the right way doing it that I Everything I've seen is kind of the opposite. I just think that this is an idea which I"
},
{
"end_time": 1242.688,
"index": 52,
"start_time": 1220.674,
"text": " The more you look at it, you find that it's just not working. It's not doing what you want to need. So that's where I think we have the strongest disagreement. I'm not sure what grade that corresponds to, but a very low one. On the question of what's been going on in string theory research and positive and negative, I think"
},
{
"end_time": 1269.957,
"index": 53,
"start_time": 1244.377,
"text": " There again, we're starting to get into this very serious issue that it is very, very hard to actually know what people at this point when you say string theory, what you're talking about. If you're talking about very specifically the proposal for a unified theory based upon starting with a 10 dimensional super string and doing compactification, that's a specific proposal and that I'm"
},
{
"end_time": 1294.326,
"index": 54,
"start_time": 1270.794,
"text": " I think it's one that's not going to work out. But now when you talk about string theory, you can be, you know, is ADS-CFT string theory? There's a new paper by Whitten and a collaborator this morning about JD gravity in two dimensions. Is that string theory? I mean, it's become, it's actually very hard to kind of give any kind of evaluation of what"
},
{
"end_time": 1324.275,
"index": 55,
"start_time": 1294.735,
"text": " String theory as currently practiced by most string theorists is because it's impossible to actually tell who's a string theorist and what string theory is. And that and that's part of that ties into a sociological problem that it it's I'm interested to see that Joe's grade is relatively low. And I think, you know, I think it's hard to deny that there actually has been a serious problem with how this has been practiced as a field of science in terms of"
},
{
"end_time": 1349.889,
"index": 56,
"start_time": 1324.838,
"text": " And it's a difficult problem. How do you evaluate and conduct research on a subject which is so difficult to get any experimental evidence about? A lot of what I was writing about in the book and what I have often written about has been the problems that this causes. And we can talk more about those, I think. But again, it's a very complicated subject."
},
{
"end_time": 1377.927,
"index": 57,
"start_time": 1350.213,
"text": " And a lot of the problems are also driven by the lack of kind of better alternatives of people not, you know, of people. I think a lot of people is that, well, I'm not very happy with how things are going or what's going on now, but I don't see anything better to do. And that's a large part of what's going on. Let me pick up on the thing of which I think is absolutely true what Peter says about the question of, you know, what's meant by a string theorist or what's because"
},
{
"end_time": 1408.66,
"index": 58,
"start_time": 1379.172,
"text": " This has become highly amorphous in the sense it's almost the case that what is meant by string theory is the research done by certain prominent researchers at places like the IAS or Harvard or Stanford. It's obviously true that the actual connection to, for example, quantized strings on the world or something that very clearly involves strings, as in one-dimensional extended objects,"
},
{
"end_time": 1434.684,
"index": 59,
"start_time": 1408.951,
"text": " can often be rather nebulous. And so I think this is certainly, lots of people have observed this, if you look at the strings conference, the actual topics that people might talk about, there may be rather small number of strings there. And so this is certainly true that often when people talk about string theory,"
},
{
"end_time": 1459.292,
"index": 60,
"start_time": 1435.469,
"text": " It's a really much more nebulous idea which is almost like a certain community which is around a certain number of people and the actual topic, the actual research we're actually talking about is not and one thing it certainly isn't which I think often gets people probably get completely wrong. What it isn't is the idea of"
},
{
"end_time": 1485.879,
"index": 61,
"start_time": 1459.855,
"text": " string theory as a fundamental theory of nature that is sitting behind the standard model as the kind of, you know, the deep structure of the standard model, the deep structure of this universe. For good or ill, I think mostly ill, but lots of people think for good. I mean, most of the research that is in string theory is kind of much more in the sort of mathematical physics"
},
{
"end_time": 1514.343,
"index": 62,
"start_time": 1486.442,
"text": " area with kind of very tangential at best connections to the physics of this world. So then, Joe, what is the definition of string theory? It's whatever is practiced by the people who are at least previously called string theorists. In some ways, that's how, when people use the term, you can of course, and I said that I would, when we think of string theory and string theorists, I've"
},
{
"end_time": 1542.346,
"index": 63,
"start_time": 1514.906,
"text": " I would give a very strong defense of there is this theory that you develop from starting the theory from starting from quantizing one dimensional relativistic strings. And this then leads you to strings and this as they're to a lot of this things like holography, ADS, CFT, lots of dualities, there's a lot of this stuff, which very clearly fits into this framework. But that, that intellectual structure, I will, this is, I will absolutely 100% give this an"
},
{
"end_time": 1564.138,
"index": 64,
"start_time": 1542.671,
"text": " A grade and you asked me to bet I will say this intellectual structure really does sit underneath at the smaller scales. But it's clear obviously that a lot of the people in the community do does not necessarily fit into that. And so I'm afraid it is a slightly nebulous term. And yeah, that's the word."
},
{
"end_time": 1592.415,
"index": 65,
"start_time": 1564.667,
"text": " Now Joe, ADS-CFT and holography aren't exclusive to string theory despite them being birthed by it. So is the argument that they're just best developed, best articulated in string theory, is that sufficient in your eyes to plant the string theory flag on the holography continent? I think that the best developed examples of holography are those where"
},
{
"end_time": 1618.848,
"index": 66,
"start_time": 1592.995,
"text": " The idea of holography does exist in a way that does not rely on string theory, but it might be all the kind of really most solid and really fully worked out examples are all in string theory. So what do you say to that, Peter?"
},
{
"end_time": 1644.548,
"index": 67,
"start_time": 1620.674,
"text": " I agree with Joe that the connection to string theory and being able to say something more than general things, vague things about holography is in this ADS-5 case, in the five-dimensional case."
},
{
"end_time": 1674.104,
"index": 68,
"start_time": 1644.923,
"text": " And your problem is that doesn't connect very well to the real world, either in being at, you know, we live not in five space-time dimensions, but in four, and the hope that there's always been a very different hope for that, that I think motivates some of that research, which is that you're going to be able to solve QCD using that. And there's technical reasons why that hasn't worked out so well. But I think"
},
{
"end_time": 1702.585,
"index": 69,
"start_time": 1675.145,
"text": " That ADS-CFT was 1997, so that was 27 years ago. This is actually something I didn't really say much about in the book because the book was largely written in the first few years of the 2000s when the ADS-CFT was just starting to get going. It wasn't clear at that point how much it was going to dominate the subject and a large part of the subject."
},
{
"end_time": 1729.701,
"index": 70,
"start_time": 1703.063,
"text": " And I think it has, and there's a lot of, it would be interesting, there's a lot of interesting to say about that. I think one thing that really struck me actually this morning waking up, as I do, I often look and see what new papers there are on the archive. And I kind of mentioned this earlier, I mean, one paper that appeared today, there's like 60 some pages written by Ed Whitten and Jeff Pennington, which is very,"
},
{
"end_time": 1757.261,
"index": 71,
"start_time": 1730.333,
"text": " A lot of very, very technical stuff and actually, you know, a huge amount of kind of work and intellectual power that goes into the, and has gone into this work clearly. But what it is, I think, is a thing that is an example of something that's been a major theme, you know, in string theory as practiced by people at the IAS or very influential people, especially in a subject, which is to"
},
{
"end_time": 1784.07,
"index": 72,
"start_time": 1758.404,
"text": " To address the fact that there's a lot, the whole idea of this ADS-CFT duality, there's a lot missing there. You don't really understand exactly what this means or exactly what's going on. So you want to kind of find some simpler case where you really can get control of it and really use it and really understand exactly what's happening. So you start"
},
{
"end_time": 1814.155,
"index": 73,
"start_time": 1785.06,
"text": " One thing you do is you go to lower dimensions and use, one thing you do is you look at ADS3 CFT2 where you really have a lot of control of the, you know a lot more about the CFTs and you hope to be able to kind of say something about three dimensional gravity. And then if you look at what's happened in that subject, I mean, that's turned out just to be very complex and how gauge gravity duality is supposed to work in this, even in this lower dimensional case is"
},
{
"end_time": 1844.258,
"index": 74,
"start_time": 1814.701,
"text": " Is quite quite tricky and turns out to be very complicated and you can then People spend a lot of time going even farther down and going down to to to you know to basically, you know to two and one dimensions and to this JT gravity and so there's there you can calculate all sorts of things and you can apply is also things you do but it if you want to make this look like instead of having a nice simple beautiful picture about yours how this works it it becomes very complicated and very"
},
{
"end_time": 1871.288,
"index": 75,
"start_time": 1845.094,
"text": " very tricky to get this to do what you want. So I mean, so on the one hand, you know, Witten and very influential people have spent a lot of their life now down in these very low dimensional toy models, trying to get some, you know, trying to get some, some a handle on what's really going on there. And I don't think that that's to my mind, you know, that hasn't been much of a success at the same time. I also saw online, you know, Witten is giving a talk, opening a conference, um,"
},
{
"end_time": 1896.305,
"index": 76,
"start_time": 1872.005,
"text": " In Turkey today and he's giving a talk he's often given about you know, what every physicist should know about string theory and and you know that that talk is You know very much a promotional effort. It's completely, you know, I actually have very serious serious problems with them You can look up very version raised version of this talk and you know, he's you know, he's he's he's a genius He's very smart, but he's making a very"
},
{
"end_time": 1919.531,
"index": 77,
"start_time": 1898.968,
"text": " Hey, he's giving a certain technical reason for a whole kind of ideology, which I really don't think works out very well. And at the same time that he's kind of still kind of doing this to try and trying to promote this idea and trying to get that part of it is, I guess, defense against critics like me."
},
{
"end_time": 1949.104,
"index": 78,
"start_time": 1919.855,
"text": " At the same time, if you look at what he's actually doing, he's, you know, been going down a bit of a rabbit hole of where ADS-CFT is led to. And, you know, there's all sorts of interesting things down that rabbit hole, but they don't really look like what you want. One thing I will pick up on, which I think maybe I broadly agree with Peter on, is that sometimes if you look at things like the Strings Conference, which is this, sometimes they have these kind of public talks, and then you look at what's been put in the public talk, and it will be something like, you know, you start with a standard model,"
},
{
"end_time": 1978.183,
"index": 79,
"start_time": 1949.275,
"text": " Yeah, we need to get the physics of the Standard Model, we need to do the physics of gravity, string theory, fundamental theory of nature. And the justification that is kind of presented in that for string theory is the sort of, you know, basically, we are fundamentally doing particle physics, and we are trying to get the smallest things of nature. And then you actually look at what all the technical talks on the conference are, and they're all on kind of physics in two dimensions, or six dimensions, or three dimensions, or any number of dimensions other than four. And, yeah, with two"
},
{
"end_time": 2006.92,
"index": 80,
"start_time": 1978.541,
"text": " n equals two symmetry symmetry when you thought supersymmetry yeah yeah so that all the actual research that they you know that is most elevated is actually nothing to do with these kind of particle physics questions and so this i do agree that well that the case whatever the case you would make for something like detailed studies of holography in n equals two or jt gravity or anything like that"
},
{
"end_time": 2034.258,
"index": 81,
"start_time": 2007.619,
"text": " This case is not really a case. This is not what we are trying to do is we are trying to understand the laws of the laws of this universe. And we are trying to kind of go go beyond the standard model, which often is is the case that is made in in public tools. Peter, you said that you had several criticisms of the talk by Witten, at least, I don't know if it's the most recent one, but some of the ones in the past, what every physicist should know about string theory."
},
{
"end_time": 2064.65,
"index": 82,
"start_time": 2034.701,
"text": " What is"
},
{
"end_time": 2093.575,
"index": 83,
"start_time": 2064.889,
"text": " I'm not going to forget. I think I wrote about it in the blog and tried to kind of go through this carefully and and address seriously what this was. But I think the. I was just looking at this again this morning, so I'm trying to understand the witness point of view, and I think what he. Well, there's some very technical issues. I mean, one thing is he he kind of tries to motivate this by starting out with. Not quantum field theory, but but."
},
{
"end_time": 2120.862,
"index": 84,
"start_time": 2094.258,
"text": " Kind of the path integral quantization, we're saying we're going to have a particle theory and we're going to sum over paths. And then if you try and put in interactions, then you have to decide what's going to happen when paths join. And you can think of this as a little bit of a caricature of where the problems of renormalizability come from, from the short distance behavior. And then he says, well, then in strings, instead of having"
},
{
"end_time": 2148.012,
"index": 85,
"start_time": 2121.664,
"text": " These paths, you have world sheets and the world sheets don't have the same, you know, they don't have interactions aren't introduced by what's happening at intersections of paths. So, you know, so you're not going to have that problem. But it's kind of, it's kind of avoiding the main issues. I mean, because because the what he's talking about is actually a single particle theory. And that's actually not what"
},
{
"end_time": 2169.258,
"index": 86,
"start_time": 2148.507,
"text": " What we do i mean that's actually not what quantum field theory is quantum field theory is a theory of fields interactions that come from these have a geometrical origin and gauge symmetries and separate they're not. So he's he's kind of giving a really unfair caricature or characterizing quantum field theory in a way which which i think is really."
},
{
"end_time": 2195.879,
"index": 87,
"start_time": 2169.667,
"text": " Doesn't have much to do with the real thing and the real problems of the thing and then trying to You know to use that as justification. Well, you know world cheats are gonna are gonna solve our problems and I don't Anyway, so so that that's kind of a tech just a beginning of a technical argument against it It is interesting that goes looking at a more recent version of this that he gave and and you know, it's clear that he his I think what he's confronted about this. I mean he"
},
{
"end_time": 2226.493,
"index": 88,
"start_time": 2196.596,
"text": " he's making a bit the case that joe is making that you know there's there's clearly something there's something very interesting going on here and i think the way he he likes to say it is that you know this is it's very very hard to find any kind of consistent thing which goes beyond quantum field theory which is not a quantum field theory but but but still sat it but which generalizes quantum field theory and still satisfies the fundamental principles you need to satisfy and that the fact that string theory exists and is such a thing you know makes it you know highly worth"
},
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"end_time": 2253.183,
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"text": " We're studying. This is certainly true. The problem again is that people have been doing this for a long time. He first proposed the idea of M-theory in 1995, so now nearly 30 years ago. There's something very complicated and interesting going on there with S-dualities relating theories in unexpected ways."
},
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"text": " But the kind of idea that there is some kind of, you know, well-defined, you know, fundamental, in some sense simple basic structure which is behind all this and which is going to actually be useful for describing the real world. I just don't see the last 30 years as being very kind to that idea."
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"text": " Hola, Miami! When's the last time you've been in Burlington? We've updated, organized, and added fresh fashion. See for yourself Friday, November 14th to Sunday, November 16th at our Big Deal event. You can enter for a chance to win free wawa gas for a year, plus more surprises in your Burlington. Miami, that means so many ways and days to save. Burlington. Deals. Brands. Wow! No purchase necessary. Visit BigDealEvent.com for more details."
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"text": " Joseph, what do you broadly agree with and disagree with? Yeah, let me say this. So there's a few among a lot of string theorists, this is because string theorists, the community that would go there would go some something like this. So this is a view I don't actually agree with, but I'm just going to try and state it in the best version I can, which is that when you encounter string theory, you encounter this extraordinarily rich and deep structure with"
},
{
"end_time": 2386.749,
"index": 94,
"start_time": 2363.183,
"text": " Many connections to quantum field theory, to gravity, many deep and surprising properties about it. And because the Planck scale is so large, i.e. gravity is so weakly coupled, the right intellectual approach is to try and study this deep, mathematically complex, extremely intriguing set of ideas and to study it as deeply and as thoroughly as possible."
},
{
"end_time": 2413.933,
"index": 95,
"start_time": 2387.108,
"text": " and to try and get as full as understanding of it with the idea that when you do get as full of understanding, by developing this full understanding, you will then be in the best position to understand then how this theory can be connected to the real world. Okay, so that is, I think it's a view a lot of people have and it's a view I broadly disagree with that. So what I would say is, so my view is that"
},
{
"end_time": 2442.398,
"index": 96,
"start_time": 2417.227,
"text": " Mathematical physics, this type of thing has been on a sort of diminishing returns for the last kind of 40 or so. I mean, ADFCFT is a big kind of peak against the broad trend of diminishing returns. But there have been awful lot of people working in this kind of way for a long time. And I think if you look at the kind of say the theoretical results, for example, GR, the results about black holes of Hawking and Penrose in the 90s, these were both kind of"
},
{
"end_time": 2467.961,
"index": 97,
"start_time": 2442.927,
"text": " extremely intellectually deep, extremely intellectually profound, with also profound observational consequences. So now I think you often have people arguing for kind of results that are deep, but they're really kind of quite divorced from. So my view in terms is in terms of applications to physics as a whole, mathematical physics has been delivering, which includes a lot of this kind of what kind of string theorists do has been delivering diminishing returns for"
},
{
"end_time": 2494.701,
"index": 98,
"start_time": 2468.422,
"text": " a few decades. I think I also think there's a danger, which is as follows, that if when you have people who are working in theories and to debate theories in highly subjective theories, which where there is no real attempt to make connections to the physics of this universe, and then they train students who are working in these areas, and then those students themselves become, you know, is that you lose the connection with what it is to measure something."
},
{
"end_time": 2521.954,
"index": 99,
"start_time": 2495.691,
"text": " And so some of the research I've most enjoyed is when you actually have to think about, you're trying to measure something, so you have a telescope or something, you actually have to understand how it works, how it actually gets data, what actual data is, you have to actually think about how experiments actually work. And I think there is a structural danger in that you have at least two, sometimes three generations of people who get trained in an environment where they don't"
},
{
"end_time": 2526.459,
"index": 100,
"start_time": 2522.858,
"text": " Actually, no, they don't they never they've never really worked with data"
},
{
"end_time": 2554.889,
"index": 101,
"start_time": 2527.295,
"text": " And they've never really thought deeply about what it is to measure something in the real world. Now, the people of the older generation who were kind of, you know, Peter's mentioned like Ed Whitten, for example, or obviously they grew up in the generation where the generation of the standard model and they were kind of surrounded by this. Yeah, this was kind of part that they were kind of just incubated in the thing of how you measure stuff, because that was just where they were. But as you go on to kind of as you move forward in time towards the present, then you have people whose entire career is, yeah,"
},
{
"end_time": 2566.954,
"index": 102,
"start_time": 2555.708,
"text": " Where they haven't written a single paper, which involves how you actually measure anything in the real world. And the students haven't written a single paper in this. And it's like muscles, you know, if you never use your muscles, if you spend your entire life sitting on a sofa."
},
{
"end_time": 2594.599,
"index": 103,
"start_time": 2567.773,
"text": " It's not the case that you're then by thinking deeply, you'll work out how to walk and then you'll get up and be able to walk really well. If you never use the muscles, they're a trophy. And so my worry is that there is a danger that this is happening because people have never worked on how you connect anything with data and so they lose the ability to think about such problems. I have a somewhat different point of view on all this because actually, so I mean,"
},
{
"end_time": 2623.251,
"index": 104,
"start_time": 2595.794,
"text": " I'm often people often characterize my views as my main criticism of string theory is that oh well you know it's not really it doesn't have experimental backing and so this is the main problem with it but that's not actually what actually bothers me about it most I mean I do have this great respect for experiment I went through this you know I spent some time working on a particle physics experiment early in my in my career and that was actually a very extremely eye-opening experience in terms of"
},
{
"end_time": 2648.729,
"index": 105,
"start_time": 2623.951,
"text": " Understanding why your theories are the way they are. Our best theories are the way they are because they were determined by what was measurable, what could be measured and what couldn't. The problem is that it has legitimately become very difficult to approach these"
},
{
"end_time": 2676.527,
"index": 106,
"start_time": 2649.258,
"text": " Questions about you know how how to do better than the standard model experimentally and we really are We may already at this point with the LHC have basically run out of steam and you know, it's there's a big argument about whether you know to build another next-generation accelerator and the the problem is that Anyway, we know how to how to do it is going to be very very expensive and not not that big an increase in dumb and that the resolution the energy you can go to and"
},
{
"end_time": 2703.285,
"index": 107,
"start_time": 2677.005,
"text": " So we are kind of stuck. I think the field, if you want to make progress on these questions, you may have to. I'm more sympathetic. I think the point of view that Joe is less sympathetic to among his colleagues that, OK, well, maybe you need to kind of go somewhere else for inspiration, go to go to mathematics or go to try and figure out how you can make progress on these things without having a connection to experiment."
},
{
"end_time": 2730.555,
"index": 108,
"start_time": 2703.729,
"text": " And, you know, I've spent most of my life in a math department. So I know I have a lot of sympathy to kind of what the way mathematicians think and what mathematics, how mathematics works. And but I think I see much the same phenomena that he's talking about from a summit from this different point of view. Even if you like myself, if you're actually willing to say, OK, I'm I'm willing to accept"
},
{
"end_time": 2749.821,
"index": 109,
"start_time": 2731.305,
"text": " Maybe to put it in the most extreme fashion, if somebody today, tomorrow came to me with a completely beautiful, completely simple mathematical structure, saying, okay, here's why the standard model works the way it was and why gravity works the way it was. But unfortunately, it's incredibly beautiful and simple."
},
{
"end_time": 2778.985,
"index": 110,
"start_time": 2750.247,
"text": " and and they were right and I agreed with that and there was a but but there's no it shows what there's no way for us to really get any more evidence for this experimentally I would be tend to be I say okay well that I'm happy that that's great whereas I think Joe and many others would not be so happy with that but but but but even if you if you focus on on them on the on the mathematics I think he's right that they've been really diminishing returns there were some just truly um revolutionary amazing things that came out of"
},
{
"end_time": 2807.585,
"index": 111,
"start_time": 2779.462,
"text": " especially the late 80s, early 90s, and this kind of overlap between math and physics. And a lot of it was generated by kind of joint efforts of Witten and Michael Atiyah. And they just completely, they have wonderful, for explaining some actual physical things, but they also are just completely revolutionary for mathematics. I mean, these ideas about the so-called churn time as Witten theory and"
},
{
"end_time": 2834.718,
"index": 112,
"start_time": 2808.302,
"text": " I did and the things that happened with with three manifolds and four manifolds they were just and mirror symmetry that they really have just revolutionized parts of mathematics but you know but watching what's happened since then since the early 90s it's just been kind of a every every it's just been kind of a monotone decreasing amount of that kind of new insight coming coming in at least as I said I often spend my day get up in the morning and look and see what"
},
{
"end_time": 2860.828,
"index": 113,
"start_time": 2835.623,
"text": " What new papers are there in this field? And it's just the number of days when I see something, oh, that's actually something new and interesting, has just become starting to become vanishingly small, or as it used to be a fairly common occurrence. So here, there's something I say in my book, and I've said this a few times, but it's the idea that you can, you can buy from people in your language, but you have to sell to them in their language."
},
{
"end_time": 2882.568,
"index": 114,
"start_time": 2861.493,
"text": " What are the reason kind of string theories grew so much and spread so much was discovered this thing that Peter's alluding to is that it was able to solve other people's problems and contribute to other people's fields. So this example of things like mirror symmetry in the 1980s, it was able to"
},
{
"end_time": 2908.387,
"index": 115,
"start_time": 2883.217,
"text": " do things that mathematicians cared about. It wasn't a case of you now need to start caring about quantum gravity and start thinking and care about our problems. It was able to say these are the problems you care about and we can solve these problems for you. And likewise with quantum field theory and holography ideas like dualities and ADS-CFT. Again, there were lots of people who were kind of quantum field theorists and then there was this, well, you can do these calculations in gravity,"
},
{
"end_time": 2933.49,
"index": 116,
"start_time": 2908.831,
"text": " Then using ADS safety, you can solve problems at strongly coupled quantum field theory, which people were interested in as quantum filters. So this is one of the reasons I think string theory grew so much, particularly some of the people say, well, there are all these models for quantum gravity. Why is there so much on string theory? But I think part of the reason for this is that there were these types of losses in the 1980s and the 1990s on where string theory was able to solve other people's problems."
},
{
"end_time": 2957.176,
"index": 117,
"start_time": 2934.36,
"text": " And this is what led to the thing going on. But I do kind of broadly agree with what Peter said. I think the I mean, I think ADS CFT was a huge peak around 1997. But I think the the test on this is, you know, I read Cliff Burgess calls this the kind of the the the ego test is kind of, you know, do you start advocating for ideas that aren't your own?"
},
{
"end_time": 2984.138,
"index": 118,
"start_time": 2957.91,
"text": " And the sort of thing is, yeah, so the subjects that are kind of around theoretical physics, you know, the question is, when do they want to start saying that, yeah, advocate saying pulling, pulling in ideas from kind of string theory and saying, well, look, we really need these stuff to solve our problems. And I think this is what happened a lot less now in the last, say, 10 years or 10, 15 years or something than it did in the 1980s and the 1990s. Yeah."
},
{
"end_time": 3002.159,
"index": 119,
"start_time": 2984.445,
"text": " But maybe just to say one other thing about that, I mean, one thing, and this is actually one thing that I was trying to do a lot in the book I wrote was to, I mean, the story of these ideas that came in the 1980s, 1990s, a lot of them were,"
},
{
"end_time": 3029.394,
"index": 120,
"start_time": 3003.422,
"text": " String theory was part of the story, but very much only a part. A lot of these really were ideas that were purely just very new insights into quantum field theory. Sometimes they had come about because people had been thinking about something in string theory and then realized there was actually something really interesting happening if you just looked at some related quantum field theory story."
},
{
"end_time": 3049.855,
"index": 121,
"start_time": 3029.991,
"text": " Anyway, there's an incredibly complicated and confusing story about a lot of these great mathematics, mathematical physics developments of that era about their relationship to string theory, often which was kind of heavily oversold or which is actually different than, just for instance, I think people"
},
{
"end_time": 3073.882,
"index": 122,
"start_time": 3050.691,
"text": " I found it very, very hard to convince anyone of something that is actually true, which is that Ed Whitten did not win a Fields Bell for string theory. If you look at what he actually, it's just truly amazing thing that a physicist won the highest award in mathematics for some just amazing new developments in mathematics and everybody assumes that this happened"
},
{
"end_time": 3103.319,
"index": 123,
"start_time": 3074.923,
"text": " In the early nineties, and so, you know, during the period of string theory and with was working on string theory. So this must be a, a Fieldsville for string theory. And it's just simply not true. If you look at the citation and you look at the actual work that he, um, you know, they had this, this, this deepest mathematical, um, content at the time, it wasn't, um, this actually wasn't string theory, but actually getting anyone. When I say this to people, they, I find it almost impossible to convince anyone of this, but."
},
{
"end_time": 3134.138,
"index": 124,
"start_time": 3104.514,
"text": " Maybe just to pick up one other thing that Joe had said. He was worried about the way people being trained to do physics in a way that's divorced from experiment has led to this kind of atrophy of certain kind of skills, which are really important. And that's true. But I also think what I've seen, which I find very disturbing, is when I look at students now and I talk to them, they're"
},
{
"end_time": 3160.589,
"index": 125,
"start_time": 3135.998,
"text": " I remember being a student like that and what you wanted to do was you wanted to say, how do I get to the cutting edge of the subject and to the really newest, most exciting ideas that are moving forward as fast as possible? This is what you want to do. What it causes them a lot to do is to really skip over learning quantum field theory. They take a quantum field theory class and"
},
{
"end_time": 3184.053,
"index": 126,
"start_time": 3161.067,
"text": " They do some problem sets, so they learn how to do a few computations, but then they immediately are then trying to do ADS-CFT or string theory or whatever the hottest topic is of the year. I'm really increasingly worried that the system has trained a couple of generations of people who don't actually really understand the standard model as a"
},
{
"end_time": 3202.773,
"index": 127,
"start_time": 3184.974,
"text": " You know what the quantum field theory issue has a quantum field theory what the actual technical issues behind it are and you know that they've ended up being trained in topics with you which aren't aren't that fruitful while completely skipping over you know just the real fundamentals of what what the problems are."
},
{
"end_time": 3233.37,
"index": 128,
"start_time": 3204.087,
"text": " Let me come in on that because that's something where I think I don't really agree with. So if you take, for example, Peskin and Schroeder, so this is a well-known quantum field theory textbook, loads and loads of people learn quantum field theory through Peskin and Schroeder. And you see what it's structured to. So Peskin and Schroeder kind of builds up to, you know, one loop precision electroweak calculations in the standard model. And these were kind of, at the time it was written, kind of the LEP collider was doing lots of precision electroweak tests."
},
{
"end_time": 3260.64,
"index": 129,
"start_time": 3234.309,
"text": " And I think it's true, you know, very, very few students learn, you know, are kind of fully on top of precision electric. But then I also think that's, you know, the subject, the subject changes the in that the calculations that you need to get, you know, you need to be really in the in the weeds of they do change with times, for example, you could argue now that knowing gravitational wave emission and understanding"
},
{
"end_time": 3285.333,
"index": 130,
"start_time": 3261.049,
"text": " gravitational waves is or understanding the physics and physics of axioms is more important for people who want to be connected to experiment than understanding how to do by hand one loop calculations in the electroweak sector of the standard model. Because it's also true that the people who do kind of standard model calculations, they are not doing them by hand, they've all got"
},
{
"end_time": 3304.991,
"index": 131,
"start_time": 3285.589,
"text": " Co-co-coach to do them. So I do think this true that the skill set, the skill set changes with time and the kind of the problems you can be where you can be fully conversant with all the kind of nitty details of does it just change by generation and it's kind of right that it changes by"
},
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"text": " This episode is brought to you by State Farm. Listening to this podcast? Smart move. Being financially savvy? Smart move. Another smart move? Having State Farm help you create a competitive price when you choose to bundle home and auto. Bundling. Just another way to save with a personal price plan. Like a good neighbor, State Farm is there. Prices are based on rating plans that vary by state. Coverage options are selected by the customer. Availability, amount of discounts and savings, and eligibility vary by state."
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"text": " By generation. So I don't know whether that's exactly what Peter's Peter's referring to, but that. Sorry, just before I also don't see it as something that's"
},
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"text": " Your critiques, Peter, as being about this generation. So as I was preparing for this talk, I went through the critiques of string theory that you have Joseph, which are you're not a fan of the overhype in the same way that you're not a fan of the uninformed criticisms. Both do damage. You see that there's difficulty in constructing decider vacua because they require a balance of delicate balance of multiple"
},
{
"end_time": 3424.275,
"index": 136,
"start_time": 3400.794,
"text": " contributions to the potential. There's also the scale separation in ADS-CFT, and yes, ADS-CFT is powerful, but constructing compactifications that correspond to scale-separated CFTs where there's a large hierarchy in operation and operator dimensions is difficult. And I know that's relevant for realistic, modulized stabilization scenarios. I'll put some of your work on screen."
},
{
"end_time": 3453.541,
"index": 137,
"start_time": 3424.804,
"text": " There's also the G2 compactifications in M theory, which unlike the Calabi-Yau manifolds, which are complex, these ones are real and there's a palpable lack of examples of compact ones with the singularities necessary for the non-abelian gauge theories. Now, Peter, your critiques of string theory are that unless I'm mistaken, they don't have something to do with this new generation being trained without being tied to experiments or"
},
{
"end_time": 3476.152,
"index": 138,
"start_time": 3453.968,
"text": " without knowing the fundamentals. When last we spoke, Peter, you spoke about the lack of predictive power and this huge landscape, which is even larger in F theory than it is in regular string theory, that there's no consistent non-perturbative formulation, but also you both agree on the hype and you think ADS-CFT is a distraction. I'm not going to"
},
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"end_time": 3503.387,
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"start_time": 3476.817,
"text": " Well, I would love to have you all speak about that. And then the other two or three that I recall are that the claim that it's mathematically rich is true, but that doesn't validate it as physics, and that there's an ignoring of alternative approaches."
},
{
"end_time": 3517.995,
"index": 140,
"start_time": 3504.531,
"text": " Epitomize by its only game in town. So does that correctly summarize your respective critiques of stream theory? But but but but Kurt, are you trying to characterize my views or are you bringing me? I think"
},
{
"end_time": 3541.169,
"index": 141,
"start_time": 3518.183,
"text": " You're not not Joe's. I think Joe is not going to be on board with all of this. Yeah. No, no, no, no. Just the first few were Joe's, up until Joyce Manifold. Then the rest were yours. Anyhow, the point is that all of what I've stated, I don't see as being unique to this generation. I see it as a critique you could have said 20 years ago. I remember when I came into the field, so I was"
},
{
"end_time": 3554.974,
"index": 142,
"start_time": 3541.886,
"text": " I was really fascinated by this. This was the mid-70s. To me, from the beginning, what was the cutting edge was the standard model. Everything was"
},
{
"end_time": 3583.234,
"index": 143,
"start_time": 3555.776,
"text": " My whole kind of conceptual framework of how do i think about what i'm trying to do here is i want to learn as much about the standard model as possible i happen to be also very interested in mathematics i want to learn as much about the mathematical structure of the standard model as possible i want to learn about the non-perturbative issues in the standard model and so this was this was how i was brought up and how and my own this is what my whole motivation was about i i i see"
},
{
"end_time": 3612.841,
"index": 144,
"start_time": 3584.087,
"text": " The last few generations, now going back 20 or 30 years, of students coming in with a very different thing. The things which to me seem really the most central deep issues, which there's still something there we don't understand and which you need to work on, that's just something they've kind of skipped over. Joe was pointing out to one thing about a typical standard, maybe just to say one slightly technical thing, quantum field theory textbooks, if you look at them,"
},
{
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"index": 145,
"start_time": 3613.353,
"text": " Yeah, they're mostly fairly similar. I mean, they do things in different ways and they have different virtues and different problems, but they really are aimed at showing how to do these kind of perturbative calculations in the standard model, like as he was referring to, and there's a certain technology for doing that. They're training you how to use that standard technology. I mean, the problem is what they're not doing is they're not really kind of telling you about any of the"
},
{
"end_time": 3664.599,
"index": 146,
"start_time": 3641.817,
"text": " Any of the technical problems about what things are still on is, you know, to me, the kind of central question, what is still unsatisfactory about the standard model? What doesn't really work right? And that you don't get out. It's very hard to get out of a quantum field theory textbook. Anyway, it starts to get to get to be a little bit more complicated. But I really I really see a big difference between kind of my"
},
{
"end_time": 3693.848,
"index": 147,
"start_time": 3665.998,
"text": " the environment in which I was trained and what I was focused on and what, and I see that what students these days, how they're being trained and what they're focused on. And, you know, I think the thing that, the thing that to me I think was most central and I think still is a most central question in our subject. I think they're really kind of not, they're trained pretty much to ignore. And even worse than that, this is a field with a lot of intellectual arrogance."
},
{
"end_time": 3720.35,
"index": 148,
"start_time": 3694.121,
"text": " And it's a very, very difficult subject. People kind of come into this environment thinking, well, oh, you know, I must, you know, anybody who understands this stuff like me is a real genius. I kind of understand it. I must be a genius too. And, um, the other people also come out of the standard educational experience these days, not just being unaware of things they should be aware of, but, but at least somewhat morally convinced that, you know, anybody who cares about those"
},
{
"end_time": 3741.34,
"index": 149,
"start_time": 3720.845,
"text": " Issues is somebody who just never understood the textbook you know that you know these are old textbook issues which have long been settled and you know if somebody is kind of trying to bring these things up and talk about them it must be you know they were just one of these students who kind of never really understood that understood the textbook that and that's that's a little bit exaggerating but it's um"
},
{
"end_time": 3764.428,
"index": 150,
"start_time": 3741.817,
"text": " So there's one things where I want to speak in defense of students. So I think this also something applies with experimental particle physics. So I think it's with students, I think students really need a chance to, people need to, when young people want to do something, they need to have a chance to have a career. And I think this involves a certain thing where you know, the thing where you're going to work hard on something, you're going to work really hard on something, it may not work out."
},
{
"end_time": 3792.176,
"index": 151,
"start_time": 3765.026,
"text": " But that you've kind of you get your lottery ticket or your ticket, you know, you get your chance of that you work really hard and then there might be something kind of really big. So experimentalists get this. You had this with the LHC, for example. Yeah, they work really hard. They have a there's a chance of discovery. I think it's really important that people have a they have the chance of contribution. And so I think the. What I have some sympathy with what Peter is saying, I think it's also from a student's point of view, I mean, the"
},
{
"end_time": 3810.879,
"index": 152,
"start_time": 3792.773,
"text": " It's really hard to be the idea that you're going to say, well, we've got this standard model and Weinberg at his peak was spending huge amounts of time thinking about the structure of the standard model. Witten has been growing up thinking about the structure of the standard model. And so this is an area where there's been a lot of extraordinarily smart people have"
},
{
"end_time": 3834.514,
"index": 153,
"start_time": 3810.879,
"text": " Been over and been over and been over and so this is why I think you will could I think you can fully understand why she would want to be something where they're going to something which is maybe less explored and then then they feel they have a kind of so I also want to pick up on this comment on on arrogance which I think is kind of interesting and I think it's"
},
{
"end_time": 3846.22,
"index": 154,
"start_time": 3835.913,
"text": " it's true but there's also a sense in which i think it's kind of it's important it's true and i think it's kind of what i want to kind of explicate this a bit so this comes back you know if you're a student and then you think well"
},
{
"end_time": 3868.507,
"index": 155,
"start_time": 3846.971,
"text": " Okay, you're a student in particular and you want to make, and this is kind of held at every time and you want to make a contribution to the subject. And if you think too hard about the idea of, I want to make a contribution, and you know, Weinberg's been spending his career in this area, Witten's been spending his career in this area, Wilczek's been sending in this career, or the previous generation, you say, well, Heisenberg's been thinking all about this, Dirac's been thinking all about this, Feynman's been done."
},
{
"end_time": 3882.125,
"index": 156,
"start_time": 3869.599,
"text": " If you kind of worry too much about this, I think you will just collapse under the weight of what you're trying to do. So I think actually the healthiest attitude for students is almost some simultaneous combination"
},
{
"end_time": 3909.189,
"index": 157,
"start_time": 3882.295,
"text": " of kind of almost extreme arrogance and extreme humility. Not just one or the other, but somehow to be able to hold them both at the same time. Because on the one hand, you really want people to be saying, actually, I think all these people who are genuinely obviously super smart have been in this area before me, have been thinking about this before me, but I can make a contribution and do something none of them do. I can do something that Witten didn't do, that Weinberg didn't do, that Wilczek didn't do. And"
},
{
"end_time": 3932.841,
"index": 158,
"start_time": 3909.804,
"text": " Yeah, to be honest, some degree of arrogance is going to help helps in that, otherwise you just collapse under the way. But then you also need the humility of saying, all these extraordinary people have been here before me, I need to learn from what they've done, I need to learn from the best of what they and so this isn't to my view. I mean, theoretical physics has a justly deserved reputation for arrogance. But I think also there's also a big element of humility."
},
{
"end_time": 3944.138,
"index": 159,
"start_time": 3933.353,
"text": " To buy also and this is the kind of thing which is maybe slightly controversial is I think this arrogance is actually a structurally positive part of the subject because the subject could not make progress."
},
{
"end_time": 3972.637,
"index": 160,
"start_time": 3944.735,
"text": " without it, because otherwise, if you think about what you're trying to do, you just will, people will just wilt under the expectation that you're, you know, that you could the idea that you could be 22 or 23. And you've had 1000s of really smart people in this area before you. And you can do something that they they haven't done. But it's needed. We constantly need 22 or 23 year olds thinking this in order for the subject to make progress. So this is my slightly nuanced view on arrogance in theoretical physics and why it's actually a structural and ultimately a structurally positive"
},
{
"end_time": 4000.367,
"index": 161,
"start_time": 3973.183,
"text": " Why would you say arrogance and humility versus confidence and humility? Why do you say arrogance over confidence? So, I mean, so this is coming back to the thing that, you know, the rational of evaluation of anyone is if you are saying, look, Feynman's been thinking about this, Weinberg's been thinking about this, Witten's been thinking about this, you know, can I"
},
{
"end_time": 4024.411,
"index": 162,
"start_time": 4001.51,
"text": " Can I do this? I mean, I think, you know, if you are going to rationally say, well, oh, yeah, I can rationally evaluate myself as you're not talking about me here, but, you know, someone could rationally say, well, I'm confident I could do better than Weinberg or Witten or five. Yeah, I don't think that's, you know, it's somehow it's not you can't do it rationally. It needs, I think, I think actually this sort of slight, you know,"
},
{
"end_time": 4043.217,
"index": 163,
"start_time": 4026.391,
"text": " I pretty much agree with Joe. I should make clear that this kind of"
},
{
"end_time": 4073.08,
"index": 164,
"start_time": 4043.814,
"text": " This wasn't completely a critique about arrogance. I mean, I've just been sitting here telling you about how Ed Witten is wrong about something. I mean, I clearly have plenty of arrogance to go around myself. He's right. You need some intellectual self-confidence and ambition to get anywhere in these kinds of very difficult subjects. At the other time, you also need the humility to realize that you're"
},
{
"end_time": 4100.043,
"index": 165,
"start_time": 4073.712,
"text": " You're quite possibly wrong about things. It's a very interesting experience being in a mathematics department because mathematicians are, the whole thing is about these very precise issues of exactly what is right and exactly what is wrong. So mathematicians are actually quite used to the fact that most of the time"
},
{
"end_time": 4125.162,
"index": 166,
"start_time": 4100.469,
"text": " Very often you're going to be wrong about something and it's going to be completely undeniable because it's going to be an issue of rigorous mathematical proof. Anyway, I agree that this intellectual ambition and arrogance of the young is a good thing and is what leads to progress."
},
{
"end_time": 4154.07,
"index": 167,
"start_time": 4125.725,
"text": " This was just kind of a more of an issue of the way this often shows up. It does become a problem in this particular context. When the field itself is not that healthy, it isn't making a lot of progress and ideas that are being promoted as the latest ideas are not working well, then the danger of being an arrogant student coming in is that you might actually believe"
},
{
"end_time": 4177.568,
"index": 168,
"start_time": 4155.179,
"text": " but believe this and and and and this will uh anyway you'll you'll you'll lack the necessary understanding of what's actually right and what's what's what's wrong um but i think maybe i think joe started to talk about something which i think maybe we should talk about which is related which is this question of you know of careers if you're a young person your other main concern besides whether"
},
{
"end_time": 4206.323,
"index": 169,
"start_time": 4178.404,
"text": " You're arrogant and smart and other people are not. Are you going to be able to have a career? Are you going to find a job? Whatever your intellectual goals are, what you want to pursue, is there going to be a way for you to do this? Are you going to be able to support yourself? Are you going to be able to have a real research career? How are you going to go about this? I think that's really a real fundamental issue."
},
{
"end_time": 4235.981,
"index": 170,
"start_time": 4206.971,
"text": " If you do agree that there's been some problem with the field not making progress the way it should be in recent decades, you have to ask yourself, is this part of the problem? What can be done about this? What can be done to actually change the reward structure so that ambitious young people actually can work on more promising things and still feel that, as Joe says, they have a shot, they have a chance to actually do something."
},
{
"end_time": 4266.015,
"index": 171,
"start_time": 4236.51,
"text": " Okay, here's something I'd like to say, which I think this is not this is not something which is at all unique to string theory or particle. So I saw basically a kind of a quite interesting plot. So this was this was from the US. This is the I think the National Institute of Health and they have something called like R1 grants. And these are the grants which basically go to kind of start when people start a lab of their own. And what the plot was, it was the percentage of these grants that go to people under 35 compared to the percentage of such grants that go to people over 66."
},
{
"end_time": 4282.978,
"index": 172,
"start_time": 4266.493,
"text": " And so this is kind of gone from like from 1970. It's something like, you know, maybe like 35, but roughly something like 35% are going to be under 35, 1% of these are going to over 66. And then you kind of you come to today, and the numbers are sort of inverted."
},
{
"end_time": 4311.766,
"index": 173,
"start_time": 4282.978,
"text": " That is a very large fraction. These grants are going to people over what is what we would use to be a retirement age and a very small fraction are going to people under 35. And I think you can see simple things in kind of fundamentals, particularly with things like the Simon's Foundation and this habit of some private foundations giving extraordinarily large sums of money to very senior people basically to run their"
},
{
"end_time": 4339.326,
"index": 174,
"start_time": 4312.176,
"text": " large numbers of junior researchers in their research in their research programme. Whereas I think a much more similar things like the sort of these Simon's collaboration again, which are kind of very, very large, very well funded things, but are basically are kind of very much supporting established research. And I think the ability to give young people the head give them, you know,"
},
{
"end_time": 4357.142,
"index": 175,
"start_time": 4340.145,
"text": " enough money that they could properly do something by themselves without relying or feeling that they have to sort of sit in the network of someone much more senior and obviously not all these things will kind of work out. So I think this is a sort of structural weakness in terms of"
},
{
"end_time": 4384.616,
"index": 176,
"start_time": 4358.2,
"text": " This is the season for all your holiday favorites, like a very Jonas Christmas movie and Home Alone on Disney Plus."
},
{
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"index": 177,
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{
"end_time": 4436.408,
"index": 178,
"start_time": 4407.176,
"text": " Close your eyes, exhale, feel your body relax, and let go of whatever you're carrying today. Well, I'm letting go of the worry that I wouldn't get my new contacts in time for this class. I got them delivered free from 1-800-CONTACTS. Oh my gosh, they're so fast. And breathe. Oh, sorry. I almost couldn't breathe when I saw the discount they gave me on my first order. Oh, sorry. Namaste. Visit 1-800-CONTACTS.COM today to save on your first order."
},
{
"end_time": 4450.93,
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"start_time": 4437.415,
"text": " Great. Now, as I mentioned in the introduction, I would like this conversation not just to focus on string theory, but also theoretical physics. What are the problems? So you just mentioned that there are disproportionate rewards that go to senior individuals instead of the fresh talent."
},
{
"end_time": 4479.65,
"index": 180,
"start_time": 4451.152,
"text": " What else? And I understand that this doesn't just affect whatever we're about, or you all are about to speak about, won't it just affect theoretical physics, but perhaps science as a whole? But let's just speak about our domain of theoretical physics here. So what are the problems actually with fundamental theoretical physics as theoretical physics as a whole is quite large? I mean, I think the obvious one is that of experimental data. I mean, I think maybe people's views on the subject. I mean, Peter's from a generation where"
},
{
"end_time": 4510.23,
"index": 181,
"start_time": 4480.333,
"text": " The standard model was being discovered in real time, as it were. There's a period in the 1970s, the late 70s, where particles are kind of not quite at the rate of one a year, but almost at a rate of one a year. And I think what you experience when you're young inevitably sets your notion of what kind of is normal or what should be normal. I mean, my PhD is in 2006. I'm from very much the generation where"
},
{
"end_time": 4536.766,
"index": 182,
"start_time": 4510.52,
"text": " Yeah, almost your expectation is every single time you try and break the standard model, the standard model wins. That's, that's been the pretty much throughout, throughout, throughout my career. Obviously there is physics beyond the standard model. We know there is, there has to be physics beyond the standard model, but in terms of your expectations, your, your default thing of what happens, I mean, yeah, we are from, we were formed in very different times. Actually, not, not that different than you think. I was also the, um,"
},
{
"end_time": 4557.329,
"index": 183,
"start_time": 4537.466,
"text": " I started learning about the Standard Model in 75, 76. It was already in place and this phenomenon of that as experimental results came in, they all... Anyway, there's a lot of excitement that everything was agreeing with the Standard Model, but I think it didn't take that many years to start to become a little bit depressing."
},
{
"end_time": 4584.445,
"index": 184,
"start_time": 4557.619,
"text": " Wait a minute. It's great that we're so successful and everything agrees with the standard model, but if we don't have something soon that disagrees with the standard model, we're going to be in trouble. This goes way back. We've been in that situation for a long time. Hype is not a new thing. Supersymmetry was first discovered in 1984 at CERN."
},
{
"end_time": 4614.804,
"index": 185,
"start_time": 4584.804,
"text": " at UA1 and UA2. Yeah, I think it was undiscovered in, you know, 1985 or, yeah, but it was, yeah, so claims of kind of discoveries, claim your hype, which are things which are not subsequently justified. Yeah, I think they've always been there. Maybe to try to address a little bit, I think what you're trying to get at. I mean, one is, you know, there's technical questions about, you know, what we might see as how to make progress. And, you know, and I'm in this"
},
{
"end_time": 4637.193,
"index": 186,
"start_time": 4615.401,
"text": " Very weird state of the last few years. I've actually some old ideas, which I long convinced myself couldn't possibly work. All of a sudden I started to see ways forward and I've been very happily exploring those and I actually think this is really going somewhere. So I feel myself in this question of, oh, what's the future of the subject? What's the right thing to be thinking about?"
},
{
"end_time": 4667.585,
"index": 187,
"start_time": 4637.688,
"text": " Feel like I start to become like every crank in the subject. Yes. Well, you know, I know what the right thing is and and I'll tell you all about how twisters and This and how this this is the thing to do. So I mean there are various ways of thinking about twisters Hitchens From way of thinking about them and the relation of hyper echelon manifolds. I've actually kind of realized that that's actually a better way of understanding the relation to some of the other things that I've been trying to do so"
},
{
"end_time": 4696.015,
"index": 188,
"start_time": 4667.858,
"text": " And there's this, maybe just to say a couple words about the whole thing, it's really just, there's a fundamental idea in twister theory is that a point in space-time should be thought of as a different kind of geometrical object, as a sphere. If you like, maybe when you open your eyes and you see the celestial sphere, that sphere is the way you should describe a point in space-time. Or mathematically, it's also equivalent to saying that"
},
{
"end_time": 4720.589,
"index": 189,
"start_time": 4696.903,
"text": " If you're looking at the vial, like let's say the right-handed vial spinners at a point, that you should actually describe the points in spacetime by using those spinner spaces. So in some tautological sense, if you want to know what a spinner is, in this geometrical setup, the space of spinners at a point is the point."
},
{
"end_time": 4744.206,
"index": 190,
"start_time": 4721.118,
"text": " So there's a long story about this, but I'm seeing quite a lot of different ways of seeing the symmetries that really govern how the standard model works. There's a new way of thinking about them coming about from this geometry that I find very promising. Maybe that's the best to say, but it really is kind of work in progress, but I keep finding them."
},
{
"end_time": 4766.869,
"index": 191,
"start_time": 4744.787,
"text": " Unlike most ideas I've had in my life, I've found that if you think about them for a while, sooner or later things just kind of work less and less well and you realize this wasn't such a great idea, this is actually something that just kind of keeps doing something interesting that I'm quite excited about. But I can understand it. Anyway, there's a lot to be done to get anyone else interested in this."
},
{
"end_time": 4797.585,
"index": 192,
"start_time": 4767.961,
"text": " If falsifiability is not immediately achievable, then what are the other criteria that one should use to evaluate between different competing theories of fundamental physics? I think there is an intellectual depth and an intellectual richness of strength theory, which I think is the more people are able to evaluate it at a technical level, the more people agree with this."
},
{
"end_time": 4822.193,
"index": 193,
"start_time": 4797.944,
"text": " And now you can say it is an aesthetic judgment to say that ideas which include quantum field theory include general relativity and are very kind of rich and complex and kind of hold together in lots of non-trivial ways. So it's an aesthetic judgment to say that probably nature doesn't leave this out."
},
{
"end_time": 4851.152,
"index": 194,
"start_time": 4824.258,
"text": " You could say, well, you could have this structure and you could say you could if you were going to say to me, yes, string theory may be mathematically beautiful. It may be intellectually rich. There is no logical reason why that means it has anything to do with nature. I can only agree with you. There is no logic. There's no logical reason that is not logically implied. So there's an aesthetic judgment that things which are really mathematically subtle, mathematically"
},
{
"end_time": 4870.333,
"index": 195,
"start_time": 4851.476,
"text": " complex and somehow tied to a lot of what we already know to be true are not left out by nature. So that's what I would say and part of that's an aesthetic judgment. I in some sense agree though. I think my own"
},
{
"end_time": 4900.23,
"index": 196,
"start_time": 4871.271,
"text": " Anyway, my own aesthetics and the mathematics and the things that I've been interested in. I think I see this differently than Joe. I mean, string theory, it's true it's a very rich subject, but I've always thought that to some extent it's a very rich subject in some ways because it hasn't really worked out. I mean, if this had worked out in 1985 and you'd found that there's some certain clobby-ow"
},
{
"end_time": 4927.858,
"index": 197,
"start_time": 4901.203,
"text": " you know, gave you the standard model on this all worked, you know, it would be, you know, a fairly complicated and, you know, very interesting theory. And it would be, and that amazingly works described as the real world. But instead, you know, that people had trouble getting that to work out. So they started on a very, very long intellectual journey and by some very, very smart people. And they ended up exploring all sorts of very, very different"
},
{
"end_time": 4957.807,
"index": 198,
"start_time": 4928.985,
"text": " different things and discovering all sorts of interesting different things about mathematics and about physics. The problem for me has always been that to the extent that I find the things that they're discovering really compelling and really beautiful, they often were orthogonal to the things that were looking more, to looking like the real world. That if you, when you tried to move this in the subject into the, and try to get something that looks like the real world, you"
},
{
"end_time": 4984.394,
"index": 199,
"start_time": 4958.507,
"text": " you had to move in kind of not so aesthetically pleasing directions. Whereas if you'd said, I'm going to follow, you know, my aesthetic judgment that what is a really deep idea? What's a, you know, something worth looking at totally independent of whether it has, of whether it agrees with the experiment, you ended up going in directions which, which don't so much look like the standard model or look like the real world. Can you give an example of where you've had to move away from what's aesthetically pleasing?"
},
{
"end_time": 5007.807,
"index": 200,
"start_time": 4985.862,
"text": " um well i mean anything even um i mean mirror symmetry again is an example it's uh there's beautiful mathematics there it just doesn't connect very well to anything about telling you about four dimensions um maybe adscft is also somewhat somewhat of an example that you want to you know it works really nicely and"
},
{
"end_time": 5029.036,
"index": 201,
"start_time": 5008.66,
"text": " You know in five dimensions and five dimensional space time if you the minute if you try and use it to kind of say something about real fit real physics but four dimensional space time or you use it to try to solve QCD you. You end up just kind of struggling and having to try to."
},
{
"end_time": 5058.524,
"index": 202,
"start_time": 5029.735,
"text": " The question that I just asked was about what is it that should allow us to decide between competing theories when we don't have experiment to guide us? So in other words, when we don't have something objective to guide us, and then Joe and you, Peter, you both said, well, aesthetics, which a synonym is beauty or elegance,"
},
{
"end_time": 5086.596,
"index": 203,
"start_time": 5059.019,
"text": " but yet you both find different aspects of the world, beautiful and elegant. And so that doesn't converge. Yeah. So one thing where I can, can I come say where I think we might, um, where I kind of both agree and disagree with Peter is that the species that the bits that when you get to the real world, that you lose a lot of this beauty. But so what I would say is that the tour to talk about the beauty and the aesthetics, it's talking about the, and this is an adjustment in terms of the theory."
},
{
"end_time": 5116.101,
"index": 204,
"start_time": 5087.022,
"text": " not necessarily in terms of the solutions. So that, for example, if we were going to talk about simple gravitational things, you'd say, well, okay, a sphere, a sphere is a very nice, aesthetically beautiful and simple object. But if you want to talk about the Earth, for example, then it's very important for the history of humanity that there are kind of there are continents that there are some continents are more separated than others. And then you have to get into the very much the specific weeds of"
},
{
"end_time": 5133.268,
"index": 205,
"start_time": 5116.476,
"text": " These are the precise details of the actual realization and you know no actual planet is just a perfectly perfectly straight. So in this way my aesthetic judgment is relating to the theory and you know I agree with Peter that if when you try saying well now you want something to look as close to the standard model as possible."
},
{
"end_time": 5157.261,
"index": 206,
"start_time": 5134.65,
"text": " It's no longer the kind of maximal beauty and simplicity of, for example, maximal, maximal, you've got some kind of messy compactification. Yes, there'd be some kind of the fact that the standard model might become some particular contingent detail detail of that. So in that sense, I kind of I agree with Peter, but then I disagree because my aesthetic judgment relates more to the"
},
{
"end_time": 5187.244,
"index": 207,
"start_time": 5158.046,
"text": " The issue is more about the kind of structure of the of the theory and the problem than about the actual solutions. You may have complicated solutions to it. But maybe I want to say one thing about this. This is something I did try and write about in my book and there was kind of a about exactly this question. How do you evaluate things when you don't"
},
{
"end_time": 5216.8,
"index": 208,
"start_time": 5188.097,
"text": " When you don't have experiment to keep you honest. And there's kind of a line from a Bob Dylan song that kept going through my head. It goes something like, to live outside the law, you must be honest. And I think what this means to me is that if you're going to do this, if you're going to not have experiment telling you whether you're right or wrong, and I'm going to rely upon aesthetic judgments or your own"
},
{
"end_time": 5245.145,
"index": 209,
"start_time": 5217.278,
"text": " judgments of what's really consistent, of what's really a compelling idea. You really, really have to be very honest with yourself. It's very easy to fool yourself. It's extremely easy to fool yourself that some idea is beautiful and wonderful and even when, you know, as you learn more about it, you find out this is really not such a great idea. And this is actually kind of what"
},
{
"end_time": 5274.65,
"index": 210,
"start_time": 5245.52,
"text": " I see as one of the fundamental problems of how string theory has been pursued and especially the problem of hype. I think the whole field of fundamental physics and especially string theory has just suffered a lot over the decades from this kind of, to put it bluntly, a lack of honesty about what has really been going on here. It's very tempting. It's very easy for people to go out into the world and write books and have"
},
{
"end_time": 5300.196,
"index": 211,
"start_time": 5274.991,
"text": " TV programs and promote, you know, so everything here is so great. But, you know, it's doing that is very, very dangerous if there's no experiment to keep you honest and you really need. Anyway, anyway, so the whole subject really, really kind of needs some kind of much better internal structure of kind of. Acknowledging when things aren't working."
},
{
"end_time": 5329.138,
"index": 212,
"start_time": 5300.469,
"text": " and keeping track of what really works, what really doesn't work, and kind of not running out and issuing press releases from your university about how great something is, about what's going on when it's just not. So that's been a large part of my kind of feelings about the subject over the years. So here I'm going to come in, I'm afraid if you want to fire here, at this point I'm going to largely agree with Peter that"
},
{
"end_time": 5344.07,
"index": 213,
"start_time": 5329.701,
"text": " The I think like I said earlier about, you know, kind of, you know, intellectual ambition, intellectual, arrogant, arrogant, arrogant, strong personalities. Now, I think even though this, yeah, this may not literally people are necessary, quote unquote, nice,"
},
{
"end_time": 5368.473,
"index": 214,
"start_time": 5344.377,
"text": " But I do think that is always kind of a part of, you know, a necessary part of making progress in fundamental physics. But yeah, but ideally, you have experiment that kind of, you know, can kind of tame this, as Peter says, that the, you know, the thing that experiment is telling you you're wrong, and this has something to do with and this has an ability to because to tame, you know, strong personalities, people are strong, strong personalities, you know,"
},
{
"end_time": 5396.015,
"index": 215,
"start_time": 5368.797,
"text": " intellectually very self-confident and experiment does have an important role in taming that and keeping everyone on the straight and narrow and I think there is a kind of a structural danger so in terms of how you make so I said earlier on in terms of the kind of are things optimized to make progress and I gave that that a C and I think there is a definite danger when you lack experiment as the as the time and then you have the danger of hype where people you know"
},
{
"end_time": 5422.79,
"index": 216,
"start_time": 5396.834,
"text": " You have prominent newspapers, people send press releases from newspapers, prominent newspapers write big articles about writing things up as massive progress, which in reality are not massive progress in nature. And in the long term, the subject suffers because if people get the sense that you are not communicating honestly to the public about what you have done and what you haven't done, then"
},
{
"end_time": 5450.418,
"index": 217,
"start_time": 5423.422,
"text": " in the in the long in the long term you suffer and this is why yeah this is why i said when i come back to this thing you said well there is no direct experience i think it's important to say that because it's true and we've got a responsibility to the public to communicate honestly and i also when i say that i think string theory is an extraordinary strongly deep and rich intellectual structure and i think it is probably part of nature and i also am saying i'm putting that equally up there with that there is no direct experimental evidence please because i think both of these are true statements"
},
{
"end_time": 5472.432,
"index": 218,
"start_time": 5451.288,
"text": " But when you go to the public with press releases or articles in newspapers or these kind of very kind of puff write ups by certain kind of online science magazines, then that does damage broader confidence in the subject and broader confidence in the Academy. Yeah, Scott Aronson was just interviewed."
},
{
"end_time": 5499.326,
"index": 219,
"start_time": 5472.722,
"text": " alongside another professor of quantum computing i believe is a professor or researcher in quantum computing and then that researcher was saying look i don't feel the need to counter the hype in this field all i care about is that if i'm correct or incorrect when i publish something is it correct that's what i care about and then scott quit he said well the fact that you don't feel the burden just doubles the burden of other people yeah okay so"
},
{
"end_time": 5522.432,
"index": 220,
"start_time": 5499.821,
"text": " I think string theory is"
},
{
"end_time": 5549.718,
"index": 221,
"start_time": 5522.432,
"text": " an abundant source of rich ideas for how you go beyond the standard model of particle physics. And if you read Preeti's blog, he would generally say that this sort of stuff is all a waste of time. And it's not what you were doing. So this is an area. I think string theory is an abundant source of rich ideas. So I think about how you think go beyond the standard model. And I think, yeah,"
},
{
"end_time": 5581.186,
"index": 222,
"start_time": 5551.323,
"text": " The common critique that you'll hear on places like Twitter is that those who critique string theory, they just don't know the subject. They're uninformed. They're not bright. Peter's clearly none of these adjectives. Well, bright people who are informed can also be wrong. Yeah, that's not in itself. That's not a particularly strong point to say that somebody is bright and well informed to say that therefore."
},
{
"end_time": 5607.79,
"index": 223,
"start_time": 5581.732,
"text": " Well, yeah, anyway, I think my disagreement with Joe, actually, I've, you know, it's been my long standing disagreement, kind of, kind of since the beginning and over the long term, especially like with my, with my colleague, Brian Green, for instance, you know, it was always that not that I just always thought, okay, you know, he's got some enthusiasm for a certain picture of a world for a certain set of ideas. And I, you know,"
},
{
"end_time": 5636.647,
"index": 224,
"start_time": 5608.473,
"text": " I look at them and from earlier, early on, I lacked this enthusiasm and as years go on, it just kind of looks, I feel more and more justified for this lack of enthusiasm. So the big difference you're seeing between us is really just, we're looking at different kinds of, trying to see a way forward to a better theory, a better understanding. There's certain"
},
{
"end_time": 5666.681,
"index": 225,
"start_time": 5637.978,
"text": " certain set of ideas involving string theory, which, um, you know, some people, people significantly smarter and harder working than me, you know, I find very, very, um, very, very compelling. And it's, you know, part of it is also that I've got, I've always, because of my own particular interests and the way I've learned the subject, there are always different things which, which seemed to me kind of most intriguing and most promising. And, uh,"
},
{
"end_time": 5691.903,
"index": 226,
"start_time": 5667.654,
"text": " And, you know, for many years when I would write about this, I kind of felt that, well, I've only got kind of the vaguest, if people ask me and put me in this spot, is I've only got kind of the vaguest ideas about, you know, maybe you should be doing this kind of thing, not what you're doing. And now I feel I have something much more specific to point to, but it's, um, anyway, we come from different backgrounds. We've, we know different things. We, we sit, we see,"
},
{
"end_time": 5717.381,
"index": 227,
"start_time": 5692.654,
"text": " We see this whole problem and this whole structure, everything in a different way, so people quite legitimately are making their own decisions about what they think is the most promising thing to do and to think about. Can I come here? I'm going to try and express a criticism, which I think I've heard Peter make and I've certainly seen other people make, and then I want to explain why I think that criticism is wrong."
},
{
"end_time": 5730.64,
"index": 228,
"start_time": 5717.517,
"text": " So the criticism would go something like this. If you're trying to connect string theory to particle physics, then you need to compactify the extra dimensions onto something like Calabi-Al. There are something like 500 million known Calabi-Als."
},
{
"end_time": 5756.032,
"index": 229,
"start_time": 5731.271,
"text": " The number of ways when you do this to sort of ensure that what I call the moduli are stabilised, that the kind of geometry is something stable, you often need what are kind of fluxes. And if you don't know the details, it doesn't so much matter. But let's say which common ground, which I think we will agree on, that there are an astronomically large number of ways, the number 10 to 500 is often quoted here, for turning these fluxes on."
},
{
"end_time": 5777.312,
"index": 230,
"start_time": 5756.425,
"text": " So the argument that is then given is you want to connect string theory to particle physics by compactifying on a Calabria. There are something like 500 million, however many, Calabrials. There are something like 10 to the 500 ways of turning fluxes on. There are something like 10 to the 500 possibilities for what you are doing. Every single one of them will give you different low energy physics."
},
{
"end_time": 5801.817,
"index": 231,
"start_time": 5777.312,
"text": " You've no possible chance of finding the correct theory. You would never know if you do. This is worse than the needle. Every compactification will give you different physics. Therefore, you're not going anywhere. There is no kind of intellectual value or worth in what you're doing. Joe has done an excellent job of channeling me or people with this criticism. Go ahead."
},
{
"end_time": 5831.323,
"index": 232,
"start_time": 5801.817,
"text": " And actually, that's going to be the preamble to the next Ed Witton, what everyone should know about string theory. So then what I would say is that it's not that there are various aspects of the physics of these compactifications are actually universal that across these 10 to the 500 of these for all these boxes, that there are certain things that are kind of always present. So that, for example, one of the things I've worked on a lot is the presence of what's called relatively like modular. So these are particles whose essentially all interactions are gravitational strength."
},
{
"end_time": 5859.957,
"index": 233,
"start_time": 5832.193,
"text": " And these can have profound impacts on early universe cosmology. They can come to dominate the entry into the universe in lots of, you know, you very often get the thing, the idea that the universe could be filled at an earlier set. So the universe is unconstrained roughly for about 30 orders of magnitude in time, about half its lifetime and logarithmic scale between inflation and nuclear synthesis. And these regions, this period of the universe, for example, could be entirely 100% dominated by string theory particles, by moduli."
},
{
"end_time": 5886.647,
"index": 234,
"start_time": 5860.845,
"text": " And the presence of such a module is completely ubiquitous across these 10 to the 500 compactifications. So what I would say is another thing is that it's not actually true that the particle physics is all different. There are lots of aspects of the physics that are actually broadly universal across these things. These lead to very interesting modifications from, for example, the standard cosmology. Such modifications are reasonably well motivated and"
},
{
"end_time": 5902.381,
"index": 235,
"start_time": 5886.647,
"text": " they could really be part of the history of this universe and therefore it is right and proper to do as i do and other people do to say what signatures could these give rise to how in principle could you look for these how in principle could you detect these how in principle could you say that the early universe"
},
{
"end_time": 5923.968,
"index": 236,
"start_time": 5902.381,
"text": " In this period where it is currently observationally unconstrained, we don't know half the history of the universe on a log scale. How do you look for the physics of what happened in that time? And the string theory suggests lots of interesting things that could happen there and these are very worthwhile things to think about. So that is why I think the criticism is wrong."
},
{
"end_time": 5945.196,
"index": 237,
"start_time": 5924.497,
"text": " Your fundamental problem with that is that no one is, I mean, you're correct that these issues about moduli and seeing effects of moduli is a generic issue in these kinds of theories, but you're seeing it as an opportunity and it's a legitimate thing to do to go out and ask, can we actually see these things? But you're still stuck with the fact that we haven't seen them, right?"
},
{
"end_time": 5956.442,
"index": 238,
"start_time": 5946.032,
"text": " You'd be in a much better shape if there were a couple of fields out there which looked like moduli fields and then you'd be in much better shape."
},
{
"end_time": 5985.128,
"index": 239,
"start_time": 5957.602,
"text": " Yeah, I mean, here, this is kind of this is coming back to the thing that I think the thing that particle physics really as a whole has missed over the last few decades is really striking new data. And data is the foundation of the subject. And in this I include then, there's lots of particle astroparticle physics, for example, the search for dark matter, for example, for example, as well. OK, so then given this lack of data,"
},
{
"end_time": 6009.326,
"index": 240,
"start_time": 5985.538,
"text": " Peter, you mentioned that one of the problems of the way that fundamental physics research is conducted is this lack of honesty. Are there other issues? Well, I don't mean that there's a lot of, there's, there's a lot of different, anyway, there's, it's a very complex, it's a complicated step, but there's a lot of interest, there are a lot of different things to say. I mean, one,"
},
{
"end_time": 6037.449,
"index": 241,
"start_time": 6010.145,
"text": " There when the issue, we've already dealt with a lot of these. I mean, one is I think the kind of the kind of career issues about how you, um, and, you know, I, I understand, you know, I think Joe's right that there, there are related problems in other fields, but, but, but there are some races that this is exceptionally bad and exceptionally a problem in fundamental physics in general, that yeah, that there, you know, that if you, if you are an ambitious young person, you want to do something new in the subject, you know, how,"
},
{
"end_time": 6063.49,
"index": 242,
"start_time": 6039.428,
"text": " First of all, it's very, very difficult to come up with a good idea, but the other question is, it's also very, very difficult to find a way to support yourself in a job and to fit into the funding structure as currently. Can I just come here? So one thing I'm sure Peter will agree, so one criticism you sometimes hear of string theory,"
},
{
"end_time": 6093.2,
"index": 243,
"start_time": 6063.882,
"text": " is that string theory is robbing all the money that should be going elsewhere. So I think it's worth making completely clear that the amount of money that goes to particle theory as a whole is a tiny fraction of what goes to experimental particle physics, which is a tiny fraction of what goes to condensed mass physics, which is a tiny fraction of what goes to medical physics. The idea that if you consider the science funding pot, that somehow there's a huge chunk that is going to string theory or any kind of fundamental particle physics is"
},
{
"end_time": 6113.285,
"index": 244,
"start_time": 6093.2,
"text": " That's really not not the actual problem. I think maybe maybe a good way to focus on the actual problem I think is to be an experience which I think Joe's probably had I've had in that"
},
{
"end_time": 6141.51,
"index": 245,
"start_time": 6113.968,
"text": " More on the math side is, you know, when you're when you're an academic department, you know, part of what you do is hire people and try to reproduce yourself. And so you're you're sitting there looking at these these folders of people's applications and and you have to decide, you know, who are who are we going to hire? And it's in a I think I think it's kind of the problem is, is that the people do"
},
{
"end_time": 6170.094,
"index": 246,
"start_time": 6141.903,
"text": " Put in that position in theoretical physics, at least to my mind, they have a lot of applications. They have many, many talented people with very, very good credentials coming from very well-known places. If there were a lot of jobs out there and it was hard to hire people, if somebody came to you and said, well, I'm not"
},
{
"end_time": 6200.418,
"index": 247,
"start_time": 6171.118,
"text": " I'm not working on the latest, the ideas that got all the attention, I'm doing something a little bit weird on my own and if there's something I'm trying to do, you might hire them just because they were better than the, they seemed a bit smarter than the other people. The problem right now is if you're looking at this stack of folders of very smart people with these very, very good letters saying how brilliant they are and who are quite talented, what happens, at least I'd be interested to hear what Joe says about this,"
},
{
"end_time": 6228.183,
"index": 248,
"start_time": 6200.708,
"text": " In my experience, people then say, okay, well, now that we have this stack of these very good people, we can kind of focus on people who can come here and can be part of what's currently the kind of leading edge or the latest, hottest new idea. And so you end up with a hiring system where people have to be"
},
{
"end_time": 6241.084,
"index": 249,
"start_time": 6228.592,
"text": " They have to be really both smart and talented and do everything right and they have to kind of seem to be saying something about the newest hottest idea in order to get a job. I don't know what your reaction to that is, Jim."
},
{
"end_time": 6265.538,
"index": 250,
"start_time": 6241.22,
"text": " One thing I think, I think there's a difference between sort of US and European hiring. So for good or real, it can work different at different times. I think that is more true of US hiring than European hiring. I think European hiring is more willing to, tends to be less kind of fashion,"
},
{
"end_time": 6292.79,
"index": 251,
"start_time": 6265.913,
"text": " I say fashion driven sounds slightly as it's necessarily a bad thing but the kind of positive side of this is sometimes you know problems that need a lot of a lot of progress is to be made and by just throwing a lot of people at this problem and hiring everything the problem you make an awful lot of progress quickly. So I don't know it's not necessarily true but for good or ill I think what you're describing where people have to be working on the latest hot idea is more true of US hiring broadly than your European hiring."
},
{
"end_time": 6318.797,
"index": 252,
"start_time": 6294.804,
"text": " Yeah, I think also one thing just I want to say is about the video was talking about written in the Fields Medal and the idea is the idea that good scientific fields, you know, aren't surrounded by kind of high walls, they're surrounded by kind of very low, you know, boundaries, you can step easily over. And so the idea that kind of people are string theorists or not string theorists,"
},
{
"end_time": 6346.305,
"index": 253,
"start_time": 6319.667,
"text": " is really kind of not true. People can work on many, like myself, on one level I'm a string theorist. I've also done work on kind of searches for axioms with x-ray astronomy. I've got these various, you know, different legs in kind of like things like cosmology and astroparticle physics. On the more formal side, you have people you could call them string theorists, but you could also say they're kind of quantum field theorists. You know, there's been lots of kind of reasonably active areas in quantum field, for example, the bootstrap, for example, which has"
},
{
"end_time": 6371.135,
"index": 254,
"start_time": 6346.698,
"text": " Relative huge connections with strength and the idea that people aren't on strength theory or off strength theory. It's also something you're in and out. I mean, good fields are healthier. People can kind of wander across between what's tightly you could call strength and what's not strength. I mean, I think the more broad thing is, are you are you having things which are"
},
{
"end_time": 6397.807,
"index": 255,
"start_time": 6371.749,
"text": " into, you know, to maximize the conditions for intellectual creativity and intellectual productivity and for kind of, you know, and for interesting, you know, and important ideas to appear, you know, which also, I think the other thing you're saying is that you often can't tell on a one year time scale or two year time scale, what are the most interesting and important and important ideas? Yes, because I when I was talking about I've seen this happen. I mean, to some extent, this also happens in"
},
{
"end_time": 6428.575,
"index": 256,
"start_time": 6398.848,
"text": " in mathematics as much the same thing but but there you know when you have a very healthy subject where you know the things which are kind of the hot topics or the fashion or whatever are actually really legitimately kind of exciting and major sources of progress it's it's a perfectly reasonable thing to be doing and academia moves along quite well when you if the kind of if you've kind of gotten into trouble and if the fashion driven things are not really working then it becomes more of a problem"
},
{
"end_time": 6456.578,
"index": 257,
"start_time": 6429.189,
"text": " but maybe to get to something else that related to what Joe was saying. I think one of the more disturbing things I've seen happen in this subject over the years has been this kind of, um, you know, this business of, you know, who's a strength theorist and who isn't a strength theorist. There's this weird way in which it's become kind of tribal and that, you know, people feel that, you know, you know, either you're a strength theory, either you're part of the tribe or not of the tribe."
},
{
"end_time": 6486.169,
"index": 258,
"start_time": 6456.732,
"text": " And if you're a string theorist, then you have to defend string theory against these outsiders who are going to kind of coming in and trying to steal your funding and your jobs. And I kind of noticed this most when I was kind of starting to write about string theory. It was really kind of shocking the extent to which"
},
{
"end_time": 6516.271,
"index": 259,
"start_time": 6486.596,
"text": " You talk to people and they would say, yeah, you know, I more or less agree with you or agree with you a lot, but, you know, I wouldn't dare to say any such things publicly because that's going to get me in trouble. You know, I'm not going to, I'm going to have trouble with my next grant for my students having jobs or, you know, this is, you know, this has become kind of a toxic situation where you don't want to, you know, you don't want to, you don't want to be caught saying the wrong thing and, and that people in my tribe are all of a sudden going to want to get rid of me."
},
{
"end_time": 6545.828,
"index": 260,
"start_time": 6516.766,
"text": " And then I realized after I'd started the blog at first, I was thinking, well, you know, anonymity is important on the blog comments because it means that, you know, people who are wanting to be critical of string theory are going to be able to, um, to do so without retribution. Um, and then after a while I realized that the, the way things were going, there were string theorists also needed anonymity. Cause if you were a string theorist and you decided to kind of come and comment on my blog and"
},
{
"end_time": 6575.128,
"index": 261,
"start_time": 6546.305,
"text": " and forcefully defend the theory, then you know, then you may offend people from the other tribe and you may get in trouble and you don't want to do that either. So it's a, it's been, anyway, it's something actually, you know, quite bad intellectually to make it, to have it be so difficult to actually, you know, have these kinds of discussions. Yeah. So I do recognize some of the dynamic you're talking about the idea that it is"
},
{
"end_time": 6599.957,
"index": 262,
"start_time": 6575.384,
"text": " Coming back to the idea that you have some number of people who are very powerful at certain elite universities in the US and people don't want to criticize them or they don't want to criticize their papers or they don't want to say that this paper is wrong and because people either fear and rightly that their career will be impacted."
},
{
"end_time": 6619.07,
"index": 263,
"start_time": 6600.555,
"text": " I don't think it's an entirely healthy dynamic and this is why experiment is"
},
{
"end_time": 6644.189,
"index": 264,
"start_time": 6619.701,
"text": " So good when it's working properly because experiment is the thing that it doesn't it doesn't it doesn't matter whether you're the, you know, whatever name distinguished professor of, you know, be a big shot physics at Big Shot University experiment just comes along and says your theory is wrong. Now, before I move to the closing remarks or closing questions, I want to ask, what is the role for multiple time dimensions in physics?"
},
{
"end_time": 6677.056,
"index": 265,
"start_time": 6647.21,
"text": " Okay, so there are various questions that I think are fair to formulate. So these include like, why do we just experience one time dimension? Why does time run forward? Why are the equations of quantum mechanics what they are? Why the Schrodinger equation is what it is?"
},
{
"end_time": 6707.159,
"index": 266,
"start_time": 6677.961,
"text": " I think it's fair to say that even if you're doing things like the most profound theories that we know of, these are not answered questions. In the same way you say why are the equations of quantum mechanics what they are, ultimately you're just going to come back and say well this is what they are. So multiple time dimensions, what role are they? None as far as I'm"
},
{
"end_time": 6736.34,
"index": 267,
"start_time": 6708.029,
"text": " aware, but I'm also aware that this is not a very studied, this is not a very studied, yeah, why do conscious brains, why do we perceive time moving forward? Well defined question, but also one that I think we do not really, what not really study and for good of real do not do not spend time thinking about. Yeah, maybe just to say something related to what I have been thinking about. I mean, so in some sense, a lot of what I have been thinking about has been the relationship between"
},
{
"end_time": 6766.22,
"index": 268,
"start_time": 6736.783,
"text": " the Euclidean signature and the Minkowski signature theories, which in some sense you can think of it's the difference between having zero time dimensions, I mean, just four space dimensions and one time dimension. And anyway, there's, I think there's a lot of amazing mathematical structure there, just thinking about four dimensions about this relation between zero time and one time. The thing, and how this works out with spinners and twisters and everything, the one thing"
},
{
"end_time": 6796.237,
"index": 269,
"start_time": 6767.739,
"text": " It kind of bothers me a little bit that I still don't know what to think about is that if you look at the possibilities in four dimensions, you know, because you have your choice between what's, you know, in the metric signature, what's positive, what's negative, but you basically got three possibilities, you basically got kind of zero time dimension. So all four positive or all four negative, and you've got, which is where things are kind of nice mathematically, or you've got one time dimension, which is"
},
{
"end_time": 6815.367,
"index": 270,
"start_time": 6796.681,
"text": " one positive or one negative, and that seems to be where we live, and that's when Caskey saves time. But there's also this possibility of two positives and two negatives to have this split signature of signature two-two in four dimensions."
},
{
"end_time": 6842.773,
"index": 271,
"start_time": 6816.237,
"text": " In some sense, the whole story about spinners and reality and everything actually works most nicely in that story. So everything I'm thinking about, there's clearly a story happening over there in this split signature. But as far as I know, it has nothing to do with the real world. And again, it's this problem of, if you're purely thinking about mathematical beauty, I'm very tempted to go think about that 2-2 signature case."
},
{
"end_time": 6865.606,
"index": 272,
"start_time": 6843.507,
"text": " I just can't see any possible conceivable relation to any question about the real world that I know about and someday somebody may tell me one but um but anyway that that's the only way this topic has come up in my own thinking. There's something I just like to put in which I kind of wanted to say it's about the kind of relation between hype and then ultimate intellectual substance I mean it's"
},
{
"end_time": 6893.046,
"index": 273,
"start_time": 6865.998,
"text": " Even if there is some hype-ridden press release about something that isn't really very substantial, that doesn't take away from the existence of the actual subject, the actual is an intellectual coherent thing, the existence of things. Peter was referring earlier, both completely agree with me about, for example, mirror symmetry, there are lots of these things which are just there and they're correct and they're lasting and they're extremely deep."
},
{
"end_time": 6920.759,
"index": 274,
"start_time": 6893.251,
"text": " it areas mathematics for example there there areas which for example like finite group theory is one of these areas where at one point there was a lot of work and i think the subject basically was exhausted because all finite groups were classified and yep that doesn't mean the fact that there are there aren't lots of new results in finite group theory is not a is not a criticism of the kind of the intellectual value or validity of that it's just that sometimes you find something that which are really deep and profound and you find and you"
},
{
"end_time": 6950.794,
"index": 275,
"start_time": 6921.152,
"text": " I am very strong in my defense of the intellectual value and lasting validity of string theory. I'm much more nuanced about whether everything right now is kind of optimized for an environment that creates maximal progress, but my defense of the underlying theory itself is completely unqualified."
},
{
"end_time": 6981.596,
"index": 276,
"start_time": 6951.681,
"text": " Peter, how much of your criticism towards string theory would be removed if string theory was classified as mathematics and not mathematical physics?"
},
{
"end_time": 7009.343,
"index": 277,
"start_time": 6982.193,
"text": " It's, um, yeah, you know, anyway, anyway, that the problem is kind of what people mean. Maybe I have my own views on my own, which I've been kind of accused of being kind of semi mystical in the sense that I believe that deep physics and deep mathematics are heavily intertwined and are in some sense, maybe even will turn out to be the same thing. Um, so it's not, um,"
},
{
"end_time": 7036.186,
"index": 278,
"start_time": 7012.142,
"text": " I don't know how to say this, but maybe I'm going in the wrong direction with this, but just to say that the thing that I really dislike hearing is saying that, oh, the problem with string theory is that it's mathematics, it belongs in mathematics environments. If you look at something like ADS-CFT, there just isn't any particularly deep mathematics there. That is not"
},
{
"end_time": 7065.469,
"index": 279,
"start_time": 7036.51,
"text": " That does not belong in a math department. Mathematicians might be able to tell you something, but it's an idea about physics and it needs to stand or live or stand as an idea about physics. And it's true of a lot of string theory and the things, there's a complicated relation, but this idea that, oh, string theory is just mathematics. That's really kind of a wrong way of thinking about it because it's not, and mathematicians have a very,"
},
{
"end_time": 7088.097,
"index": 280,
"start_time": 7065.998,
"text": " Our field has its own structure and it's only doing, and this is, no mathematician would say that this is true, oh yes, string theory is just a natural part of math departments. That's really not the way it's, the way things are. I think there's a, yeah, I think there's a cultural, there's a,"
},
{
"end_time": 7118.183,
"index": 281,
"start_time": 7089.206,
"text": " Often people start off with that young and they're good at stuff, but then there is a very big cultural difference between maths and physics. And I think one of the, Edwidge is one of the very few people who's really been able to speak both languages almost like as a native speaker. I think most people are either physicists or they're mathematicians and there's actually quite a deep cultural difference between the two. Yeah. No, anyway, I think anyway, it's been one of the great fascinations of my life to see both communities and to"
},
{
"end_time": 7141.903,
"index": 282,
"start_time": 7118.507,
"text": " There is a fascinating relation between the two. They are very different. They have different histories. They have very different ways of thinking about things, but I think they are also in some ways deeply related. It's a fascinating subject to see the interrelation between the two, but the idea that the problem with strain theory is that it's been improperly categorized and should be mathematically is just wrong."
},
{
"end_time": 7171.032,
"index": 283,
"start_time": 7143.524,
"text": " Well, speaking of mathematicians and physicists, a large portion of this audience are either professors or academic researchers in math and physics, and then another large portion are people who are becoming researchers. So, Joe, what's your advice to young researchers, people entering the field? I'm sure you'd want to skip the existing researchers. To learn, you know, to learn whatever part of the subject you want to learn it properly."
},
{
"end_time": 7197.005,
"index": 284,
"start_time": 7171.186,
"text": " So try and avoid the kind of popular science books and learn quantum field 3 properly, learn GR properly. Then that gives you the position to make informed intellectual decisions about what you really want to study. And in terms of research, I think try and"
},
{
"end_time": 7227.978,
"index": 285,
"start_time": 7198.353,
"text": " Just to echo famous advice by Weinberg, try and be in areas that are messy rather than areas that are clean. Peter. Well, I mean, the one category of student I often get to meet and talk to are people who are interested in both math and physics. And the standard kind of advice I give them is at least in the US, the US job situation that I'm most familiar with."
},
{
"end_time": 7257.21,
"index": 286,
"start_time": 7228.592,
"text": " If you can't decide between the two and you like doing both, you probably should go to graduate school and try to have a career in mathematics. It's a lot easier environment. The ratio between really, really smart people and jobs where you can actually think about what you want to think about is much better in mathematics. That's a little bit of"
},
{
"end_time": 7287.125,
"index": 287,
"start_time": 7257.961,
"text": " Just kind of practical advice. It's very hard. I think it's a very tough situation for students who really understand very well. They're in love with questions about fundamental physics. They want to figure out how to do something with this, how to make their way. It is very, very tough. And the situation in getting a PhD in theoretical physics, trying to find a job, is quite difficult. I don't know of something that I have really good advice."
},
{
"end_time": 7313.951,
"index": 288,
"start_time": 7287.773,
"text": " It's an extraordinary privilege to be able to think about these areas and the worst thing that can happen is someone has to kind of like quadruple their salary by going and working, leaving the subject and going and working somewhere else. I should say also that seeing what's going on with students these days, most of them are very worried about and thinking about what's going on with AI and what's going on with their own"
},
{
"end_time": 7343.148,
"index": 289,
"start_time": 7315.828,
"text": " Yeah, it's quite possible that we're going to be, you know, we're on the cusp of these, these kinds of research and these kinds of fields changing quite a lot, because in some ways driven by AI, if only whether or not for intellectual reasons, but if only if only that's where all the money is going to is coming from. And so, you know, I mean, mathematicians are very much, I don't know how much effect is having in physics, mathematicians are very much"
},
{
"end_time": 7368.08,
"index": 290,
"start_time": 7343.677,
"text": " starting to debate the standard ways in which we've done mathematics research in terms of writing proofs and checking proofs. Should we start using automated theorem checkers or provers? What is it? In some sense, mathematics research looks like it's something that AI might actually really be able to do"
},
{
"end_time": 7390.794,
"index": 291,
"start_time": 7368.541,
"text": " It's possible I can do it as well as or better or I can teach mathematics probably better than the rest of us. So what's what's going to happen there? So I'm curious if Joe has any if you see this in physics also how what is the AI going to have an impact on people's careers? I don't have a I mean I do I do feel that undergraduate level we need to have a"
},
{
"end_time": 7419.889,
"index": 292,
"start_time": 7391.732,
"text": " Very clear, you know, there needs to be a very clear thing as to the traditional, you know, where there's a lot of calculations you do by hand. Yeah, so it's important to understand how calculations work, but I think one has to kind of review, revisit all this and think, is this in the same way we don't use slide rules, we have calculators and think about, as we're training people for the future, learning how to do complicated integrals by hand."
},
{
"end_time": 7448.336,
"index": 293,
"start_time": 7420.367,
"text": " Is this the right skill set? Perhaps it is, perhaps it's not. But to think about. In terms of solving problems, whether. We just kind of get the old methods are still the right ones, but I don't have a clear answer. And lastly, Joe and Peter, what are you excited about research wise in the near future? Starting with Joe. So if I talk about the subject as a whole, myself, so your own personal."
},
{
"end_time": 7474.104,
"index": 294,
"start_time": 7448.729,
"text": " research. I want to talk about both because if you're intellectually you need to talk about both I think. So the subject as a whole I think gravitational waves is kind of across the spectrum of fundamental physics I think is the single most kind of interest you know it's like it's 10 years after the birth of optical astronomy in 1620 you know we're really at the very birth of gravitational wave astronomy and this is going to be the ability to look at the universe in ways and this also ties to what I'm going to talk about myself"
},
{
"end_time": 7486.203,
"index": 295,
"start_time": 7474.394,
"text": " which is this question of what was the universe, this period between inflation and big value synthesis which could cover 30 orders of magnitude in time and which is observationally unconstrained, how"
},
{
"end_time": 7511.374,
"index": 296,
"start_time": 7486.852,
"text": " Peter, what are you excited about? Well, I mentioned very specifically the stuff about"
},
{
"end_time": 7534.872,
"index": 297,
"start_time": 7511.869,
"text": " This, but maybe there's one to connect it to the larger field. There's some, and again, in my mystical feelings of the best physics and mathematics, deepest physics and mathematics are connected. I mean, the, perhaps one of the most healthy fields in, if you want to say kind of fundamental mathematics has been these ideas about arithmetic geometry."
},
{
"end_time": 7564.753,
"index": 298,
"start_time": 7535.06,
"text": " It's a story with a long history. How do you think about numbers and arithmetic geometrically? There's in some sense these things like spaces whose points are primes."
},
{
"end_time": 7592.807,
"index": 299,
"start_time": 7565.572,
"text": " It's a long and beautiful subject. It's been making a lot of progress recently. A lot of this goes under the name of this Langlands program. A lot of the questions are really about these deep questions about the symmetries of the integers and of numbers. Anyway, there's just been a lot of progress on this. To my mind, I probably spend much more time, I'm in no sense an expert in this field."
},
{
"end_time": 7621.852,
"index": 300,
"start_time": 7593.353,
"text": " I'm kind of, but I'm kind of fascinated by it. I probably spend more of my time learning about it or trying to learn about it than I should for, I should be probably doing things I'm better at. But it, um, yeah, anyway, I think that's, that's a part of mathematics, which is really quite healthy. It's, it's moving forward quite, quite quickly. Um, and, and these most recent developments go along, kind of bring together some, these are these ideas about arithmetic geometry with ideas about, um,"
},
{
"end_time": 7648.626,
"index": 301,
"start_time": 7622.773,
"text": " What's called geometric Langlands and which actually have a lot of interesting historical connections to physics. So when Witten and people were thinking a lot in the late 80s about things, ideas that came out of conformal field theory, that the mathematics that they were developing was taken over by a lot of mathematicians and turned into this, became this field of geometric Langlands, which is quite"
},
{
"end_time": 7678.37,
"index": 302,
"start_time": 7649.343,
"text": " Quite fascinating. And we're starting to see, especially through Schultz's work, a kind of bringing together of these geometric ideas from so-called geometric Langlands and then this arithmetic geometry ideas and to bring it in number theory. So it's fascinating to watch. And the thing which also kind of fascinates me, and I don't really quite know what to think of, is that in these ideas I've been thinking about, about physics, of twister theory, there's the notion of a point"
},
{
"end_time": 7703.695,
"index": 303,
"start_time": 7678.831,
"text": " As I said, it's kind of a, you should think about a point as something that's called the twister P one and it's a CP one complex projective one space, which is a sphere, but with, with opposite points identified in some sense. And that's called the twister P one. It's, it's one of the fundamental things that shows up when you do, um, twister theory and physics, but especially if you try to do it in Euclidean signature."
},
{
"end_time": 7731.169,
"index": 304,
"start_time": 7704.377,
"text": " But the most kind of thing that's completely amazed me is if you look at the recent work on trying to bring geometric and arithmetic Langlands together, you know, Schultz and others are, you know, finding that, you know, if you, if you look at a different point, if you look at different arithmetic points, which are primes, you find an interesting structure that's called the Farg-Fontaine curve. But if you take, um,"
},
{
"end_time": 7755.23,
"index": 305,
"start_time": 7732.415,
"text": " If you sometimes take the point off to infinity and if you if you look at the real numbers, the analog of the Faraday-Fontaine curve is the twister P1. So this exactly the same mathematical structure that I'm seeing is really, I can really do something if I think of points physically that way. You know, Schulze and others have found that, you know, thinking of"
},
{
"end_time": 7780.913,
"index": 306,
"start_time": 7755.913,
"text": " They're more advanced notions about geometry and how to bring them together. The number theory, they're also finding the same twister P one, the same structure showing up. So it's, you know, I don't know what to make of this other than it, it make, you know, my deep belief in the mystical connection of everything at the deepest level seems it's probably, this is probably some vindication of it, but I don't know anyway. Well, thank you both for spending"
},
{
"end_time": 7805.657,
"index": 307,
"start_time": 7781.578,
"text": " Two and a half hours on the subject of how do we advance fundamental physics and the state of string theory before we leave why don't you summarize Joe what is it that you agree with Peter about and what is it that you disagree with him on. I think we yeah I think we disagree on the"
},
{
"end_time": 7834.155,
"index": 308,
"start_time": 7806.169,
"text": " Yeah, the overall intellectual substance of strength theory. And I think we agree in thinking there, you know, there are some kind of problems in how things are kind of, you know, organized and, you know, in terms of actually making kind of intellectual progress in fundamental physics at the moment. That was that's how I see it. And Peter can tell me whether he Yeah, yeah, more or less, more or less. Right. Yeah, I think we finally"
},
{
"end_time": 7853.2,
"index": 309,
"start_time": 7834.974,
"text": " Our fundamental disagreement is, as we discussed, is more just about trying to see forward what is a promising direction to move forward with this. We just see that question very differently and we see string theory's role in that very differently."
},
{
"end_time": 7883.268,
"index": 310,
"start_time": 7854.019,
"text": " Thank you all again. The books are not even wrong. So that's Peter White. That's your book. You also have a book on quantum theory groups and representations. Joseph, your books are why string theory from 2015 and origins, the cosmos inverse. Those are on screen. All of these are on screen and in the description as well. Thank you so much for spending time here on this subject of fundamental physics. Thank you. All right. Thank you. Thank you. That's it. That's wonderful. Thank you. Thank you. Merry Christmas."
},
{
"end_time": 7909.753,
"index": 311,
"start_time": 7884.07,
"text": " Don't go anywhere just yet. Now I have a recap of today's episode brought to you by The Economist. Just as The Economist brings clarity to complex concepts, we're doing the same with our new AI-powered episode recap. Here's a concise summary of the key insights from today's podcast. All right, let's jump right in. Today, we're taking a deep dive into a couple of episodes of Kurt Jemangal's theories of everything. Oh, you know those."
},
{
"end_time": 7933.37,
"index": 312,
"start_time": 7910.23,
"text": " Those hardcore physics discussions, PhD level stuff. Exactly. Jay Wangal really gets into the weeds with his guests. And you know, he's got a serious math physics background, so he really pushes them. Yeah, he's known for going deep like weeks or even months of prep before he even sits down to talk with them. So today we're looking at two physicists with very, let's just say very different views on string theory."
},
{
"end_time": 7957.056,
"index": 313,
"start_time": 7933.439,
"text": " Yeah, Peter Wojt, who's a pretty well-known critic of string theory, and Joseph Conlin, who's actually a big defender of it. It's a fascinating clash of perspectives, and right off the bat, Jim McGaul asks them both to grade string theory. Like a school grade. Yeah, it's almost like a playful way to get things started. I like it. It gets right to the point. Totally. So, Conlin, he gives string theory a big A+. Wow, high praise."
},
{
"end_time": 7980.35,
"index": 314,
"start_time": 7957.056,
"text": " He's really enthusiastic about his potential, you know, for the long haul. But then White, he just throws down an E-. Ouch. That's rough. Right. I mean, that's practically failing the theory completely. So what creates such a huge divide between them? Well, that's what makes this deep dive so interesting. It forces us to ask, like, what happens when these brilliant minds"
},
{
"end_time": 7999.036,
"index": 315,
"start_time": 7980.759,
"text": " can't even agree on the basics. It's fundamental, right? Like what are we even talking about when we say string theory? Yeah, and that's actually one of the first things they get into. They both kind of agree that string theories become this fuzzy concept. Fuzzy how? Well, White, he points out that a lot of research that gets labeled string theory"
},
{
"end_time": 8018.251,
"index": 316,
"start_time": 7999.48,
"text": " isn't really"
},
{
"end_time": 8041.22,
"index": 317,
"start_time": 8018.558,
"text": " And this is where it gets really tricky, because if we're trying to evaluate string theory, but we don't even know exactly what it is. It becomes really hard to judge, right? Like, how do you grade something that's constantly changing? Exactly. And this isn't just an academic problem, it's a fundamental issue in physics, especially when you don't have any direct experimental evidence. You're talking about, like, how do you know if a theory is right if you can't test it in the lab? Right."
},
{
"end_time": 8067.961,
"index": 318,
"start_time": 8041.561,
"text": " And that leads them into this really interesting discussion about add SCFT correspondence, which is this big area of research in string theory. Now, add SCFT, that's something I've heard a little about. It's about a connection between different dimensions, right? Yeah, like a duality between a theory of gravity in a higher dimensional space and a quantum field theory in a lower dimensional one. But Wojt argues that this focus on add SCFT is"
},
{
"end_time": 8094.275,
"index": 319,
"start_time": 8068.183,
"text": " kind of leading physicists down a rabbit hole? A rabbit hole? How so? Well he says they're getting too caught up in these like toy models. They're mathematically interesting but they might not have anything to do with our real universe. So it's like they're playing with theoretical Legos but not building anything real. Exactly. And he even brings up this recent paper by Ed Whitten. Whitten? He's like a rock star in the physics world. Right. But White sees this paper as evidence"
},
{
"end_time": 8121.886,
"index": 320,
"start_time": 8094.65,
"text": " that even the top minds in the field are getting lost in these abstract, low-dimensional models. Like even Whitten's getting sucked in. Okay, so one guy says Ad SCFT is leading physicists astray, but what does the other guy say? Well, Colin, he comes back swinging. He defends Ad SCFT, calls it a profound discovery. He argues that even if it doesn't directly describe our universe, it's still valuable for understanding fundamental physics."
},
{
"end_time": 8130.606,
"index": 321,
"start_time": 8122.022,
"text": " Interesting. So even though they disagree about at SCFT, they both have strong opinions about it. Oh, yeah, for sure. But here's where things get a little surprising."
},
{
"end_time": 8159.787,
"index": 322,
"start_time": 8131.015,
"text": " They both actually agree that there's too much hype around string theory. Too much hype? Yeah, like all these big claims about how it's going to revolutionize physics. And Conlon thinks all this hype is actually hurting public trust in science. I can see that. It makes it seem like physicists are all talk and no action. Right. And White, he goes even further. He sees the hype as a symptom of a lack of honesty in the field. Ooh, that's a strong statement. Yeah. He even quotes Bob Dylan. He says, to live outside the law, you must be honest. Hmm. I wonder what he means by that."
},
{
"end_time": 8171.084,
"index": 323,
"start_time": 8160.299,
"text": " It's a great question. I think he's getting at this idea that when you're working in a field where it's hard to get experimental proof,"
},
{
"end_time": 8190.811,
"index": 324,
"start_time": 8171.357,
"text": " It's even more important to be intellectually honest with yourself. To admit when you're wrong, to question your own assumptions, that kind of thing. Exactly. And that's what makes this conversation so compelling. It's not just about string theory. It's about how we do science, how we evaluate ideas when we can't rely on experiments to tell us what's right or wrong."
},
{
"end_time": 8219.224,
"index": 325,
"start_time": 8190.811,
"text": " Right, it raises those big philosophical questions about the nature of truth and knowledge. And then Conlon throws in this really interesting twist. He argues that string theory can make testable predictions. Wait, really? I thought that was one of the big criticisms, that it wasn't testable. Yeah, but he says that even without having one single unified solution for string theory, you could still get predictions out of it. And he points to these things called moduli. Moduli, what are those? Well, basically they're particles. Yeah."
},
{
"end_time": 8244.94,
"index": 326,
"start_time": 8219.394,
"text": " But they're weird. They have these super weak interactions and Collins suggests that they might have dominated the very, very early universe. Wow. So we're talking like way back before even the cosmic microwave background. Yeah, even earlier. And he says that these moduli could have left behind traces, signatures that we might be able to detect in cosmological observations. So like fingerprints from the Big Bang. Exactly."
},
{
"end_time": 8268.831,
"index": 327,
"start_time": 8245.401,
"text": " And if we could find those fingerprints, it would be a huge step towards connecting string theory to the real world. That would be amazing. Right. And that's why Conlon's so excited about it. He sees it as a way to finally bridge the gap between the abstract mathematics of string theory and the observable universe. It's like opening a window into the earliest moments of time. It's mind-blowing, right? And it shows you how even in the midst of all this disagreement,"
},
{
"end_time": 8293.08,
"index": 328,
"start_time": 8269.121,
"text": " There's still room for new ideas, new ways of thinking about the universe. It really challenges our assumptions about how the universe evolved. Like, we think we know the big picture, but maybe these tiny particles hold the key to understanding it all. Right. It's like, we're so focused on the big stuff, the galaxies and the Big Bang, that we might be missing the really important stuff. Exactly. And that kind of gets to the heart of this whole debate between Boyd and Colin."
},
{
"end_time": 8315.145,
"index": 329,
"start_time": 8293.677,
"text": " White thinks string theory has gone off track, too focused on mathematical beauty instead of experimental testing. Like, he thinks they're chasing these elegant theories, but they've lost sight of how to actually prove them. Right. And Conlon actually agrees to some extent. He's worried that physicists are forgetting how to connect their theories to real-world data."
},
{
"end_time": 8340.93,
"index": 330,
"start_time": 8315.555,
"text": " He makes this great analogy about muscles, like if you don't use them, they atrophy. Oh, yeah. He says you can't just think about walking. You have to actually do it. Exactly. And that's his point. Physicists can't just keep thinking about theories. They have to find ways to test them. It's like we build these incredible machines, but we don't know how to drive them. Yeah. And they both see this as a symptom of a bigger problem in physics, this disconnect between the theory and the experiments."
},
{
"end_time": 8364.445,
"index": 331,
"start_time": 8341.476,
"text": " They're even critical of how research is done these days, like how everyone's trying to publish in these big journals and chase the latest trends. So it's like a popularity contest instead of a search for truth? Kinda, yeah. Conlon even says that hiring practices are different in Europe. Maybe they're not so focused on trends over there, which allows for more diverse research. So maybe there's more freedom to explore different ideas in Europe."
},
{
"end_time": 8393.183,
"index": 332,
"start_time": 8364.514,
"text": " Possibly. And that raises the question, is this pressure to be trendy actually hindering innovation? Like, are we missing out on big discoveries because people are afraid to go against the grain? That's a good question. What would it take to create a research environment where people are encouraged to take risks and think outside the box? That's a tough one. But I think Boyd and Conlin would agree that we need to reward truly creative research, even if it doesn't fit the mold. Speaking of going against the grain,"
},
{
"end_time": 8414.701,
"index": 333,
"start_time": 8393.456,
"text": " Boyd brings up this idea of tribalism in physics. Yeah, like how some physicists agree with his criticisms of string theory, but they won't say so publicly because they're afraid of hurting their careers. Oh, that's kind of scary. Like there's this pressure to conform. Right. And he jokes that even people who support string theory might need to remain anonymous to avoid backlash."
},
{
"end_time": 8436.493,
"index": 334,
"start_time": 8414.838,
"text": " So it's not just about the science, it's about the politics of the field too. Exactly. And this kind of division can really get in the way of progress. You know, people get so caught up in defending their own turf that they forget they're all on the same team. Right. Ultimately, they're all trying to understand the same thing, the universe. Exactly. But even with all this disagreement, Conlon makes a really important point."
},
{
"end_time": 8460.64,
"index": 335,
"start_time": 8437.312,
"text": " He says that just because there's hype or criticisms around a theory doesn't mean there's no substance there. Like there might be some good ideas hiding beneath the surface. Exactly. He uses the example of mirror symmetry, which came out of string theory research, but has had a big impact on mathematics. So even if string theory itself doesn't pan out, it could still lead to valuable discoveries in other fields. Right."
},
{
"end_time": 8484.923,
"index": 336,
"start_time": 8461.032,
"text": " And it shows you how interconnected knowledge is. You never know where an idea might lead. It's like following a winding path. You might not end up where you expected, but you'll discover something interesting along the way. Exactly. And then Jay Mongal asks Voight this really interesting question. He's like, would you stop criticizing string theory if it was just classified as math and not physics? Hmm. Trying to put him on the spot there. Yeah."
},
{
"end_time": 8508.899,
"index": 337,
"start_time": 8485.299,
"text": " And, Voight, he completely rejects that idea. He's adamant this ring theory is about physics, and it needs to be judged as such. So for him it's not just a mathematical game, it's about trying to describe the real world. Right. He even pushes back against this idea that anything mathematically complex is somehow not physics. It's like he's saying, don't underestimate the power of math to reveal the secrets of the universe."
},
{
"end_time": 8538.285,
"index": 338,
"start_time": 8509.172,
"text": " Yeah, it makes you wonder if we try to put things in boxes too much, you know, like physics over here, math over there, when really it's all connected. Right, like these rigid categories can actually hold us back from making real progress. And that kind of brings us back to this big question. How do we judge a theory when we don't have experiments to tell us if it's right or wrong, especially in these really abstract areas of physics? It's like we're stuck between these two different ways of doing physics, one that values beautiful math,"
},
{
"end_time": 8551.391,
"index": 339,
"start_time": 8538.712,
"text": " And that tension is really strong in fundamental physics, where we're dealing with things that are so far removed from our everyday experience. Right, so maybe we need to rethink what we mean by"
},
{
"end_time": 8578.473,
"index": 340,
"start_time": 8551.886,
"text": " good physics in those areas where our usual methods don't really apply. Yeah, maybe we need a new approach, one that combines the elegance of math with the grounding of experimental data. Because in the end, it's that interplay between theory and experiment that really drives science forward. And near the end of the conversation, Jaimungal tries to find some common ground between Boyd and Conlin. He asks them, like, where do you guys actually agree? Trying to bridge the gap, huh?"
},
{
"end_time": 8592.722,
"index": 341,
"start_time": 8578.643,
"text": " Exactly. And it's interesting because Colin, he admits that even though he and White have these fundamental disagreements about string theory, they both see problems with how physics research is done. Like the system itself is holding us back. That's what they seem to be saying."
},
{
"end_time": 8610.657,
"index": 342,
"start_time": 8593.097,
"text": " Conlon even suggests that these structural issues might be a bigger obstacle than their debate about string theory. And White agrees with that, saying that they both think the current system doesn't really encourage innovation. So even though they're coming from different perspectives, they can still recognize these shared problems."
},
{
"end_time": 8631.561,
"index": 343,
"start_time": 8610.657,
"text": " Which gives me some hope, you know? It means that there's potential for them to work together to make things better. It's like they're saying, hey, we might disagree about the details, but we both want physics to thrive. And that's really inspiring because it shows that even in the face of strong disagreement, there's still room for common ground and collaboration."
},
{
"end_time": 8649.121,
"index": 344,
"start_time": 8631.817,
"text": " Because at the end of the day, they're both driven by the same desire to understand the universe. Right. It's that shared curiosity that unites them, even when their ideas clash. So as we finish up this deep dive into theoretical physics and the debate about string theory, we're left with a big question."
},
{
"end_time": 8664.411,
"index": 345,
"start_time": 8649.906,
"text": " Could string theory still point us towards some deeper truth about nature, even if it doesn't describe our universe in the way we currently think? Or is it a distraction, like White suggests, leading us away from more concrete, testable ideas?"
},
{
"end_time": 8692.995,
"index": 346,
"start_time": 8665.043,
"text": " We don't have the answers, but I think what's important is that these conversations are happening. Right. It's the debate, the questioning that pushes science forward. Exactly. And I think these episodes of theories of everything really highlight the complexity of the questions physicists are wrestling with and the passion they bring to their search for understanding. It's a reminder that science is a journey, not a destination. And it's the journey that truly matters. Beautifully put. And on that note, thanks for joining us on this deep dive. We'll see you next time."
},
{
"end_time": 8720.23,
"index": 347,
"start_time": 8693.166,
"text": " New update! Started a sub stack. Writings on there are currently about language and ill-defined concepts as well as some other mathematical details. Much more being written there. This is content that isn't anywhere else. It's not on theories of everything. It's not on Patreon. Also, full transcripts will be placed there at some point in the future. Several people ask me, hey Kurt, you've spoken to so many people in the fields of theoretical physics, philosophy, and consciousness. What are your thoughts?"
},
{
"end_time": 8732.415,
"index": 348,
"start_time": 8720.589,
"text": " While I remain impartial in interviews, this substack is a way to peer into my present deliberations on these topics. Also, thank you to our partner, The Economist."
},
{
"end_time": 8757.039,
"index": 349,
"start_time": 8734.667,
"text": " Firstly, thank you for watching, thank you for listening. If you haven't subscribed or clicked that like button, now is the time to do so. Why? Because each subscribe, each like helps YouTube push this content to more people like yourself, plus it helps out Kurt directly, aka me. I also found out last year that external links count plenty toward the algorithm,"
},
{
"end_time": 8768.131,
"index": 350,
"start_time": 8757.039,
"text": " Which means that whenever you share on Twitter, say on Facebook or even on Reddit, etc. It shows YouTube, hey, people are talking about this content outside of YouTube, which in turn"
},
{
"end_time": 8790.145,
"index": 351,
"start_time": 8768.302,
"text": " Thirdly, there's a remarkably active Discord and subreddit for theories of everything, where people explicate toes, they disagree respectfully about theories, and build as a community our own toe. Links to both are in the description. Fourthly, you should know this podcast is on iTunes, it's on Spotify, it's on all of the audio platforms."
},
{
"end_time": 8805.316,
"index": 352,
"start_time": 8790.282,
"text": " All you have"
},
{
"end_time": 8828.746,
"index": 353,
"start_time": 8805.316,
"text": " I'm"
},
{
"end_time": 8846.34,
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"start_time": 8828.746,
"text": " You also get early access to ad free episodes, whether it's audio or video. It's audio in the case of Patreon video in the case of YouTube. For instance, this episode that you're listening to right now was released a few days earlier. Every dollar helps far more than you think. Either way, your viewership is generosity enough. Thank you so much."
}
]
}No transcript available.