Rationally speaking, is a presentation of New York City skeptics dedicated to promoting critical thinking, skeptical inquiry and science education. For more information, please visit us at NYC Skeptic's Doug. Welcome to, rationally speaking, the podcast, where we explore the borderlands between reason and nonsense, I am your host Master McKeel YouTube. And with me, as always, is my co-host, Julia Gillard. Julia, what are we going to talk about today?

Mathinna today we have a very special guest. We're here with Peter White, mathematical physicist and senior lecturer in mathematics at Columbia University and the author of the book Not Even Wrong The Failure of String Theory and the Search for Unity in Physical Law.

He's joining us today to talk about whether string theory has made testable predictions, whether it has the potential to do so in the future. And more generally, how do we distinguish a promising scientific theory from a dead end?

Peter, welcome. Thanks for joining us. Thank you. Thanks for inviting me.

Could you maybe start off just sort of by summarizing what string theory was trying to do and your sort of take on on how things have gone with that, if you summarise your book for us.

That's right. Twenty two minutes. Yeah. Well, so the history of string theory goes back to around 1970.

And it started out as a as an attempt to understand the issue of how to deal with strongly interacting particles, things like protons and neutrons, nuclei ended. So the idea was that fundamental objects in theory, instead of being point like the points moving around in space and in space, they're actually string like kind of one dimensional wiggling things moving around and in space.

And it within a few years in 1973, a much better theory of the strong interactions came along.

And that kind of put string theory out of business at that time for what they were trying to do with the then. But then it was revived later on in the in the early 80s. And as in a different context, with the idea of trying to make a theory, a quantum theory of gravity out of it and even better, a unified theory, a theory that would have gravity and the all the particle interactions we know about as a consistent quantum theory.

And in 1984, it really took off and one of the best people in the field got very interested in it. Many, many people got interested in it. And so and so since 1984, it's been very actively investigated. And my own take on it is that it really has it hasn't lived up to its promise that as people have learned more and more and more about it, working intensively on it since 1984, what they've just discovered is just that it leads to more and more possibilities.

So the string theory is such a kind of a flexible framework that you can pretty much get just about anything you want out of it. And you really kind of can't ever get anything out of it that you could would actually test the theory and give a distinctive prediction of the theory.

It's the title of, I guess, or your book. Right. Not not even wrong. Now, is that does that title, therefore, in your view of what counts as science versus non science, I guess. Yeah, I mean, that's part of it. So so the title of the book actually is it reflects a phrase which is actually well known among physicists. It was kind of how it's normally attributed to Wolfgang Pauli, who a well-known theorist, I guess he died in the late 50s.

And this would have been supposedly a few years before he died. He was asked about, you know, a certain piece of work. And he was he what people were used to him kind of shouting. And he was very irascible guy. And they're used to him shouting and in lectures that, you know, that's wrong. It's completely wrong. And so someone asked him, well, what about this, this new paper? And he only shook his head and said, well, that one that one's not even wrong.

And so it's become kind of the ultimate insult, but it really has kind of two two meanings.

And so so one meeting is kind of this fairly provocative insult that, well, this is this is so bad. It's it's not even wrong. The other is is this more kind of technical meeting that, you know, a theory can. A theory which can never really predict anything is, you know, can't ever be shown to be wrong, is a theory which, you know, you could best describe with these words as it's not not even wrong.

And so that seems to me like an example of something that we've talked about in the past a couple of times, which is the old idea of the demarcation problem in philosophy of science, which is, you know, what exactly or even approximately is the distinction between science and non science or science and pseudo science.

And, you know, the original version of the demarcation problem goes back to Karl Popper and his examples of non science, where Freudian psychoanalysis and Marxist theories of theories of history.

But his point was not that they were necessarily wrong as much that they were essentially compatible with any kind of observation, any kind of empirical outcome, and therefore you couldn't tell whether they were wrong or not. Is that more or less what you're talking about in terms of what your sense is that string theory perhaps is added to it?

Yeah, it's a bit different. I mean, the fun, the fun, it's very, very funny. Kind of getting involved in these debates and thinking about this is that I was when I started being more interested in philosophy of science when I was a student, but then at some point lost interest. And this kind of physics, the kind of this kind of particle physics that I was, you know, been working on and that this whole subject is about, I think is one which has never really seen these kind of debates over philosophy of science.

It was always kind of the hardest core. It was quite clear what we were doing. There was the kind of debates over things like Marxism or psychoanalysis or these very, very soft ideas, you know, and we particle theorists were writing down very precise equations. And and there really was never a kind of interesting issue about of the the problem of the demarcation problem of whether this was science or not. And so it's it's been interesting. And it kind of to see this field start to get involved in these discussions and in these philosophical issues precisely because, I mean, the rest of us are taught that physics is the queen of science.

And it is, in fact, surprising to see that there is an area of physics where there is that kind of discussion going on. And absolutely.

Oh, Peter, can we just quickly distinguish between theory that's not falsifiable and a theory that's not provable? Like, would it be possible to obtain results that would would confirm the predictions made?

What would make string theory seem more likely to be true, or is it just not possible to falsify it?

Well, it's the problem is that. I mean, this is kind of complicated discussion is kind of tricky philosophical discussion.

I'm not hard to say precisely about what I'm really trying to do, but it's not I mean, the the basic problem is string theory is that, well, first of all, there's one thing to say about string theory is that it's actually an ill-Defined notion.

We don't know exactly what string theory is mean. So string theory is more of a hope that a certain kind of theory exists satisfying certain properties. So one argument, one way of evading the problems of string theory, as always, is, is to say, well, you know, we just don't understand it well enough. We don't actually know what the theory is. And the day that we actually finally have a well-defined theory that does what we want to do, then these problems will go away.

The problem is that within the current context of what we know about what the string theory is supposed to be, there just isn't any. There aren't any. There's there's nothing like a legitimate sort of a standard prediction you expect from such a theory. There isn't a falsifiable prediction there. Isn't that a I'm not really quite I guess I'm not even really quite sure exactly what you mean to say that it's it's provable but not falsifiable.

Well, the part of the idea here is that whenever we for instance, in a teaser for this podcast, we summarize the problem as well. There is no empirical evidence that there has been empirical observation that could at this point be the result of string theory and only string theory. In other words, something that is a novel prediction right now.

Typically we get somebody who says, oh, what do you mean?

There is this idea about local spacetime symmetry and Planck length.

Somebody always points out to some obscure thing that, of course, I don't understand because I'm a biologist where they say, oh, no, no, no, string theory does make it, but it will make a prediction as soon as the Large Hadron Collider will start doing something.

Oh, by the way, before we go ahead, the universe isn't going to happen and soon because of the collider.

Right. And definitely not. Thank you.

Well, so. So what do you think? I mean, is there, in fact, something to this idea that there are there is a possibility to test the theory and that it's coming around the corner? Or do you think that that's, in fact, because of the ill defined nature of the theory that you're talking about? All of these attempts are actually not necessarily a test of string theory?

Well, there really isn't anything if you look carefully at what people say.

So I mean, there are. There are some string theorists who say, OK, I have a string theory of prediction, you know, about what the Large Hadron Collider will see. Now, if you if you look at what this actually is, you'll find that it's some some very specific model with a lot of different assumptions built into it. It's one of the many, many different classes of things which are consistent with what we know about string theory, but it's only one.

And so, you know, if you kind of pick out one of these infinite number of string theories, if you like, you can say, OK, this this one of them makes predictions. But but the problem is it's certainly not falsifiable. It's not if the string theory is not falsifiable, if you if the LHC doesn't see what that you know what that particular model predicts, well, you can say, OK, well, that was just one of an infinite number of models that we can just pick another one.

It's actually mean it does get to a very complicated.

I mean, it's not a complicated issue in science which has come up around this, what you see string theory is saying is that, well, string theory is just like the rest of our event, like even our best theory, the so-called standard model, in the sense that, OK, there are lots and lots of these different string theories. And, you know, all we can ever do is kind of pick one and go and look and see if if that's right.

The the situation, though, is different than in the standard model. You basically have a very rigid mathematical structure and with a certain number of parameters.

And there's a very limited amount of what you can of what you can change.

And there's a much wider class of theory is these quantum field theories and gaged theories and in principle, so and that's what string theorists like to compare to. But but if you look at the standard model, what the standard model is, it's really the simplest of this large class of theories. There are many, many there's an infinite number of these theories of a number of quantum field theory is just like there are an infinite number of string theories, basically.

But the what's what's actually what's interesting and why the standard model is predictive is that you don't have to go and pick some very, very complicated quantum field theory.

You pick kind of the simplest one of the simplest ones in that class. And then once you've made that choice, there's a huge amount of predictions flow from it. You have a very small amount of input is giving you a huge amount of output and a very rigid structure. So that string theory is that just kind of doesn't it's kind of the opposite.

You know, you have to kind of keep making it more and more complicated just to avoid having it contradict experiment.

Now, I want to go back eventually to the to the actual science, particularly this notion of a large family of theories, which may be interesting to explore a little bit in more detail. But we also need to get dirty at some point. As you know, the a lot of the controversy surrounding string theory and criticism of string theory has a lot to do with the sociology and in fact, even psychology. I would say science, not just a philosophy of science.

Now, since you are our guest, I'm not going to actually bring up comments that the people have made about you, but I'm going to go ahead if you want.

We can get into those as well. I've got I got to bring up something that, you know, as you know, you're certainly not the only one to raise these questions and to criticize string theory. And so there's an interesting comment that somebody wrote about Liz Mullen, who, as one of your colleagues, who has also written a book critical of the theory that that always is the trouble with physics, where he analyzes the current situation, as he sees it, of theoretical, fundamental theoretical physics.

Now, apparently, Leonard Susskind, who is a high profile physicist or theoretical physicist, referred to Smolin as and I quote, a mid-level theoretical physicist whose popular book writing activities and the related promotional hustling have given him a platform high above that generated by his physics accomplishments.

Ouch. What do you make of that? Well, yeah.

So, I mean, what happened was in it was a 2006 a few years ago, these two books came out at the same time. So it's at least Mullan's in my book. And they and we have a somewhat different points of view, but we have in many ways similar points of view about string theory. And and so it led to what's often referred to as the string wars. So during the that time, if you go to various blogs and look at the postings around that period, you can find all sorts of really kind of outrageous stuff going on and these kind of personal attacks on me and on Smolan.

And one problem that the people doing this had was that, I mean, that they couldn't really use the same arguments against Smolan and against me. So so so I mean, I've had a kind of kind of unusual career and I'm no longer in a physics department. So I guess I was portrayed as this kind of failed, failed and embittered physicist who really does know what he's talking about. And then but the problem was with the Smolan is he's a distinguished professor at the Perimeter Institute in Canada and kind of has every proper academic credentials of the field and has actually written papers on string theory.

So they couldn't use that against him. So against him. Well, they have to. One of the main arguments I got him as well, he has this alternate to string theory thing that he works on. And it was just kind of special pleading for his alternate theory, which is wrong anyway. And I guess the quote you're getting from Suskin was somewhat of an attempt to split the difference.

And you guys are in good company because I've seen this thing happen in other fields. Carl Sagan was often criticized for as being not a particularly good scientist because he was so interested in talking to the general public, to the Popular Front for the popular press. Stephen Gould, who was one of the most prominent evolutionary biologists of the later part of the 20th century, he was harshly criticized along similar lines. And, you know, so it's not it doesn't happen only in physics, but it seems to me very interesting that we're talking about it, you know, very important part of the sociology of science.

I could get back quickly to the falsifiability, to the testability, back to the science. I'm thinking, OK, if we're dirty enough for now. Yes.

So setting aside the question of the whether string theory is empirically testable now or or potentially ever, it struck me that it seems to have been tested in a sense, theoretically, just in that, if I'm not mistaken, it it has enabled developments in other fields of physics, like relating to the quantum mechanics of black holes, that the math that string theory uses has had enabled these further developments. Doesn't that seem like evidence in favor of it being true or why?

Why would that have happened if string if string theory was just is pure fabrication?

Well, I mean, it's not pure fabrication. It's a I mean, it's definitely a very interesting idea. So it's an interesting. It's definitely an interesting thing to pursue this question of what if instead of having kind of pointless degrees of freedom, you have these springlike degrees of freedom and you start applying the normal rules of quantum mechanics, of special relativity to this and try to see what you get. I mean, you definitely get some some, you know, very interesting models and some very interesting mathematical structures to study.

And, you know, and there may be things you can do with him in my claim is really has never been that, you know, that string theory is completely useless. You're never gonna get anything out of it. So it's really been that the specific thing that that string theory was sold as as was hoping to do, which was to unify physics and to have a unified theory of quantum gravity and particle physics, the standard model, to put them together into one predictive, unified framework that that.

You know that in that main application of these things, your idea is that that was sold and sold to the public and everyone else, that that really has hasn't worked and really can't work.

So even though it's useful, that doesn't bear on whether it's true. Is that what you're saying is right?

I mean, it's a very complicated when you start pursuing this, I mean, you find it's a very complicated subject. You find all sorts of complicated issues come up as you investigate those complicated issues. You learn things.

And you actually some of them, one of the best arguments for string theory is actually the effect it's had in mathematics, that it's raised a lot of very interesting mathematical questions and it's actually has some very serious impact in several sub fields of mathematics. And a lot of my mathematician colleagues kind of don't don't really kind of understand what I'm doing off and their attitude as well. You know? You know, I mean, I know something about string theory and it leads to all this great mathematics, which helps me understand it, which is given the so-called mirror symmetry, there's these great new relations between these six dimensional spaces and a lot of very interesting mathematics so that this is great.

What's the problem? And the problem is not that this this is some useless, worthless idea. The problem is that. One very speculative way of using these things really just doesn't work, and that that that that's the thing which doesn't work.

So I want to go back, however, to the point that you touched on earlier, which is this idea that there is a family, perhaps a theory or a large number of theories that that share certain fundamental similarities. Two points about that. First of all, again, I come from a different background in theoretical biology where I once heard a very prominent theoretical biologist saying that if you just give me four variables to play with, I can simulate whatever the hell you want.

That's right.

So if you have more than four, it's it's basically which which which, of course, comes to the second point, which is one philosophy of science is often referred to as the under determination or theory by the data, meaning that if you do have, you find the theory that comes in so many variety and so many flavors and which is dependent on the adjustment of so many parameters, it is essentially impossible for all effective purposes, impossible to actually come up with empirical data that are capable of discriminating between the different versions.

The theory is that part of the problem, and that's essentially what the problem is here. And I would say it maybe it's the same thing, is that in practice what you see is that if you look at these models that string theorists are studying, is that what they do is they they start out with simple ones and then they find that the the the simple ones kind of are in conflict with experiment somehow. And so they then make a little bit more complicated to avoid that conflict with experiment.

And what all they've got at this point is some fairly, quite complicated models which are kind of carefully tuned so as to avoid actually saying anything which can be kept can be tested by experiment because they would be wrong.

So that seems to me just the hallmark of an idea which doesn't work, that you have to kind of keep making it more and more complicated all the time to avoid actually confronting it.

That adding epicycles, basically we're talking about the same sort of thing.

So an argument that I've often heard in favor of string theory is that it's beautiful and that therefore it's more likely to be true.

I mean, you know, Einstein pointed to the beauty of his equations as evidence for the truth, not that he was right.

Can you talk a little bit about the the whether you think string theory is beautiful or elegant and whether how that's related to the the truth of an equation?

I mean, that's an argument I'm actually very sympathetic to. I mean, I also shared this philosophical believe that there is this kind of deep and beautiful connection between mathematics and physics and whatever. Our most fundamental theory is that it is going to be something quite beautiful.

What do we mean by beauty here, by the way?

Think so. So after I think about it, I realized it was not the sort of things you get on Sports Illustrated and that you know.

But, you know, actually, I think to me, I think beauty is being beauty or elegance is being used in a very specific way generally by physics when we're talking about this, which is that you've got a structure which involves a very small amount of input that that to specify what this thing is, you have to of, say very, very, very little. There's kind of one of these things where there's a small number of them and and you can specify it with some kind of clear and simple description.

And out of that simple specification, a whole world emerges. And this this huge number of different, very non-trivial predictions and all sorts of different structure comes out as you start, you know, investigating the the consequences of the structure.

So to me, kind of elegance or beauty here means it's kind of the ratio between the non-trivial, huge, wonderful structure you're getting out to, the very small number of principles you're putting in.

And that's that's really the hallmark of our best theories, things like the standard model. You can I mean, I can write down in one line. I've got to specify a small number of numbers and it's there and it makes an infinite number of predictions. The problem with string theory is that. When people talk about it being beautiful, what they what they're referring to, they're not referring to that because that doesn't work, or if they're referring to that, they're referring to a hope that someday that would happen.

So you have to look at what exactly they're saying when they're when they say it's a beautiful idea sometimes what they mean as well. It's a beautiful idea if it worked, which. Yeah, OK. And something but and anyway, so but yeah. I mean they when they talk about the beauty of the idea, they're not actually talking about the actual attempts to make it work. These so these kind of string theory models which people try and compare with experiment are things which are really spectacularly ugly.

They've been made more and more complicated to avoid experiment. And nobody, even the string theory, agree that the actual models are working with and trying to claim that maybe you can confront an experiment, that these things are beautiful.

But I want to follow up on Julia's question, which is, you know, the general idea that more beautiful mathematical constructions, however, you want to define beauty in mathematics or simpler theories, you know, all these tend to be variations of something.

And philosophy is known as Ockham's Razor. Now, the defense is there's many examples in the history of science where, in fact, more complicated and less elegant theories turned out to be correct. You know, the classic example is the shift from the original Copernican theory to the capillary inversion where the planets turned out not to be orbiting in perfect circles, but, you know, very perfect ellipses. That seems like the kind of situations where, in fact, in that case, Kepler was stuck for many years on this idea of circles because you really like this idea that things were simple and beautiful and all that.

And you can almost call this a metaphysical assumption. And it was only when it got out of that of that rut that it was actually able to make progress.

Do you think that there is a chance that sometimes in modern physics we run this this kind of problems, that people are a little too enamored with the with this idea of beauty and simplicity? Well, sure.

I mean, you never really know when you've got some certain model with a certain you're in a certain kind of conceptual structure. And within that structure, certain things are simple. Certain things are complicated.

I mean, it may be that you've you've got the wrong basic structure and you're going to have to move to another one.

And from the point of view of this, you're the one you've got now. The reality is it actually looks kind of complicated. And so you may actually have to move to more complicated things within your structure to finally see what's really going on. And but at least in the Copernican case, I mean, the reason for these. Anyway, I mean, there you had theories which, you know, whatever their problems actually did make kind of non-trivial predictions and were, you know, and had some kind of serious experimental backing to them.

I mean, the real problem with string theory is not that is that it's not like that. It's not like string theory has predicted some things and done some things right. And there's reason there's solid experimental reason to believe something is going on here. The problem is it really has got nothing right so far and it really hasn't got all promise. Yeah, it's all promise. And no, I mean, there aren't the kind of solid, you know, experimental results or results out of it that would lead you to believe that this is you're on the right track.

Yeah. On that depressing note, Peter, we're going to wrap up this section of the podcast, but we'll have to have you back on maybe after the Large Hadron Collider. OK, sure thing.

Assuming it hasn't killed us that the universe is not over still here.

You maybe more positive, more interesting story then. Thank you.

So now we're going to move on to the rationally speaking PEX. Welcome back. Every episode, Julia and I pick a couple of our favorite books, movies, website or whatever tickles our rational fancy, but this time, as usual, because we have a guest, we actually give you the honor of the pick of the podcast to our guests, Peter Boyd Peter.

OK, so my pick, I guess, would be a book called The End of Science by science writer John Horgan.

And it was written in the in the mid 1990s, I think was published maybe 1997. And at a time when string theory was kind of being kind of heavily promoted and all of the kind of popular science press was full of kind of very enthusiastic things about this wonderful idea. Oregon was already quite a skeptic, a skeptic. I mean, he really wasn't. It's kind of regretted in the wrong way. And he did this fit into the into this much larger argument he has about about the end of science.

And so I think it's kind of a fascinating book in many ways. I mean, it it there's this question of when, you know, ah, do you get to some point in a pursuit of a science or scientific area in which, you know, the thing really is going to come to an end, that you've you've been too successful in terms that you're a victim of your own success. And that's what this just works too well. And scientists actually hate this.

I should say that I've been at a conference with John Horgan where he was almost kind of physically assaulted by the people, by the scientists there who just who do not want to ever hear this, that perhaps what they're doing could sometimes come to an end. There's an end to it. But I think he had he had a lot of things right. He was right about string theory at the time. There are some other things I think he he had wrong.

But it's a I think it's a fascinating book.

I've actually had similar experiences talking to colleagues about the fact that, after all, there has to be, logically speaking, an end to science eventually. Not that anybody's claiming that it's happening right now simply because the number of big questions which make science interesting are, in fact, limited. I mean, once you and once you start selling some of those, for instance, you know, if we ever going to figure out the question of the origin of life.

Well, that's one question. And it's off the chart and it's a big one. Now, I do hear often some of my colleagues say, well, but for every question and answer, there's two or three that emerge. Well, that may be true in a trivial sense, that there's going to be always some little additional puzzle that is there is that comes up next. But if you conceive of science as the the enterprise that asks the big questions about nature and not just, you know, a set of small little puzzles to be solved on a daily basis, then it seems to me that it is obvious that, in fact, science is limited and therefore it's going to end one of these days.

Hopefully either that or we're going to run into a wall, epistemological wall where we're essentially running into a question that we do not have a good answer to. And again, the origin of life may be a good example simply because we don't have the historical traces for it to say much about it. And so we may be unable to answer that question period simply because we don't have the tools to do it.

Peter, what do you think that that sort of common wisdom is in the scientific community about about what's on the horizon for science, whether we're going to reach the limit of our understanding or whether it's just hard for me to understand how they could think that we have sort of an infinite future ahead of us and scientists in science, assuming we keep making progress.

I don't know about science in general, but she's talking maybe about particle physics, which I know best.

And within that, I think the I think most particle physicist kind of believe or or in some sense they'll say, well, you know, the LHC will maybe discover new things and we'll have some new better theories because of that. But that won't be the end of it. Then we can go to higher and higher energies and we'll learn more and there'll be more and more.

And and they kind of hold out this idea that, well, there is this kind of this this never has an end.

I think psychologically they just don't like to think of think of it ending. Right.

Some other physicists, I mean, have actually made this point. I guess Steven Weinberg refers to what we're doing as the search for the final theory. And then, you know, there really is and string theory was actually supposed to be such a thing. It really was supposed to be an endpoint that if if the original vision of string theory really was right, that was that was it. You know, once you've got that thing written down, that's all there is to say in that particular direction of science, in that particular search for a more fundamental objects.

You've you've identified them. You've you know, you have a theory of how they behave and that this must be the end of it. So while I'm a skeptic about string theory, I don't think it does provide the final theory that people had hoped. And I'm much more of an optimist than I think many physicists that they're that such a thing is out there and that we may actually be closer to it than we think, that the fact that this theory we have today is so good that there are no experiments at all, absolutely none that disagree with it means that we're we we may actually be closer to it than many is.

Do you think that any large areas, large fields of science that actually have already seen something like that, for instance, I often hear said that, well, for all effective purposes, chemistry as a fundamental science doesn't exist anymore because it is either about, you know, solving specific problems within the general framework of an established theory or the frontier kind of research is, in fact, physics or fundamental physics and not. Do you buy that kind of argument?

Oh, I don't know. I think I think it is true that certain certain directions of of investigation do you know, do or do reach an end.

So, I mean, there was a point when cantlon chemistry was about Caywood trying to identify these basic atoms and how they, you know, interacting either and fit together to form chemical compounds. And in some sense that was done, we don't know on mechanics, told us how that works, you know, but so that, you know, that kind of direction maybe over.

But it doesn't mean that there are not other directions in which which are.

So you're hopeful for chemists? I mean, I don't have any I'm not a chemist. I don't you know, I don't know what they is.

But that's a nice, optimistic note in which to wrap up much better than our last section, which ended on a downer. OK, thank you so much for joining us. This concludes another episode of rationally speaking. Join us next time for more explorations on the borderlands between reason and nonsense.

The rationally speaking podcast is presented by New York City skeptics for program notes, links, and to get involved in an online conversation about this and other episodes, please visit rationally speaking podcast Dog. This podcast is produced by Benny Pollack and recorded in the heart of Greenwich Village, New York. Our theme, Truth by Todd Rundgren, is used by permission. Thank you for listening.