Does beauty deceive physics? | Michio Kaku, Sabine Hossenfelder, Max Tegmark, Juan Maldacena

Foreign Faith and Physics I'm your host Mary Jane Rubinstein Tonight's debate is presented by the Institute of Arts and Ideas in association with Closer to Truth. Find his interviews with some of the leading thinkers of our time in Closer to Truth. .com and now, because of some fantasies, faith and

physics

, we think that we pursue sciences only for knowledge and truth, but is this a mistake? Untestable ideals such as

beauty

have been incorporated into theories throughout the history of science. Paul Dirac, one of the world's greatest scientists. The 20th century proclaimed that it is more important to have Beauty in equations than to make them fit the experiment and recently Roger Penrose described String Theory as a fad, quantum

physics

as a faith and cosmic inflation as a fantasy, arguing that scientists They suffer from the same prejudices as Does it affect the rest of us?

Do we pursue science out of a pure desire for truth or should we accept that some assumptions, especially in the foundations of physics, are akin to religious beliefs dressed in mathematical language? Should we see science as just another theology? that undermine the field of physics and the progress it has made over the past few centuries. I am pleased to tell you that today we have invited four wonderful speakers to address these questions. First, Juan Malasena is known worldwide for his field-defining contributions to fundamentals. of string theory and quantum gravity, works at the Institute for Advanced Studies in Princeton, New Jersey, is a theoretical physicist who specializes in quantum gravity, is the author, among other things, of Existential Physics, a scientific guide to the most important aspects of life, and then we have Max Tegmark, who is a pioneering cosmologist and computer physicist working at the Massachusetts Institute of Technology, he is the author of Our Mathematical Universe, which argues that reality is fundamentally a mathematical structure and, Finally, Michio Kaku is a famous futurist and co-founder of string field theory. spent his career inspired by the search for a theory of everything, his latest book is called Quantum Supremacy, how the quantum computer revolution will change everything, okay, a quick word about the format, we'll open the conversation with two-minute responses to an initial question and then We will move on to discuss three main topics related to this initial question.

Alright, here we go. Initial question. Let's start with Michio Kaku. Here we go. Two minutes on the question. Professor Kaku is a mathematician. Beauty is a guide to truth, please. Mathematical

beauty

is a guide to truth, but not the soul because ultimately we have to trust experiment; However, when you look at fundamental theories without exception, every fundamental theory has a description in terms of beautiful, beautiful mathematics, so what do we mean by beauty? to a physicist, beauty is symmetry, so when you mix objects you get the same thing again after performing the manipulation, so if you take a look at Einstein's theory of gravity, reparametrizations in spacetime generate the general relativity if you take a look at the standard. model uh s-u-n special unitary groups and N Dimensions is the symmetry group of quarks, for example, now hypothetically if you want to win a Nobel Prize in physics or at least be a contender, your theory has to explain at least three things first, things that Your theory would have to incorporate Einstein's theory of gravity, which as I said before has a beautiful cemetery behind it.

Second, the standard model, its theory would have to explain quarks, neutrinos, electrons and the entire zoo of subatomic particles that we see in our atomic Smashers. That's the second thing. that your theory has to explain third anomalies and divergences if you just get a piece of paper you write down Einstein's theory you try to quantify it what happens it blows up in your face because something is missing a cancellation mechanism to cancel out the divergences Until now, the The only theory that can do all three is string theory. That

does

n't mean it's correct, who knows, maybe there's a superior theory somewhere, but the only theory that can give a reasonable explanation of all three features of a theory of everything is. string theory now of course there are competing theories but they all fall down at some point they have anomalies they diverge they don't have electrons they don't have matter as we know it there is always something wrong with one of these theories and so far the only theory that can approve them It's string theory.

Now, of course, people can have their own opinions on this. Some people are critical, but when I was a kid we used to play a game and the game would shut down or go silent. is that if you say something try to top it try to say something even better or keep your mouth shut so my attitude is very simple you don't have to believe in a certain theory at all you can believe in another theory but that other theory has Satisfy these three criteria that I just exposing, for me it is the litmus test to know if you are embarking on the true path towards understanding the universe, if you can't do it, then well, maybe you should shut up, okay?

Thank you so much. Michelle Kaku has thrown in um let's move on if we can with Sabina Hasenfelder, can you answer the question? Please, she addresses the question. The question is mathematical. Beauty, a guide to truth. I think I'm going to go with Definitely Maybe. So I think we develop our sense of mathematics. Beauty through experience in physics We get this experience from the theories we work with and this shapes our sense of beauty. I think it's often a sense that can't be formulated into concrete mathematical requirements, but rather a gut feeling, a sense of what works and what

does

n't work and that's valuable exactly because we can't formulate it strictly and I also think that's why Some people are drawn to physics instead of mathematics because you can bring this intuition, this gut feeling but this sense of beauty only helps us as long as we stay in that corner of mathematics that we have experience with, if we are looking for a theory completely new one that can use completely different mathematics, will not be of any use, we have to get there by other means. means, but once we get there we develop a new sense of beauty and this has happened several times in the history of physics, for example, Kepler's elliptical orbits were once considered ugly, as was the idea that the Universe expands or quantum mechanics, but we don't.

I can no longer say that today we have developed a new sense of beauty, so I think that mathematical beauty can be useful in cases where the new theory resembles the previous ones, but if that is not the case, it can hinder the way in which string theory is a cautious approach. For example, companies think it's beautiful because it fits their sense of beauty that they've developed from existing theories, but that doesn't mean it's right and then there are alternatives like loop quantum gravity which many physicists think are ugly because it uses very different mathematics. but that doesn't mean it's bad.

Fantastic. Thank you so much. Max Tegmark is a mathematical beauty. A guide to the truth. I'm going to say yes and I want to take a little bit of historical perspective here, of course, back in ancient times thinkers like Plato and others. I felt there was something really beautiful in the physics of nature and I even saw mathematics in music and the world around us ever since. I think we've learned two main things, one by studying physics and the other, more recently, by studying artificial intelligence. I have discovered more and more beautiful patterns and not only rotational symmetry, translational symmetry, translation symmetry, time, symmetry, etc., which have been known for a long time, but also new ones, such as what Michoaco refers to as the so-called symmetries of gauge involving properties of elementary particles, etc. and eminent. showed us this beautiful relationship between symmetries and things that are more permanent in nature are conserved, so there is absolutely something there and we keep finding more, but very recently artificial intelligence has also shed light on who we are to what we are. intelligent beings are attracted. and they find it interesting in the world around them, which says that I think it's very deeply related to AI, if you have a data set with a lot of numbers and you can explain that data set with a lot fewer numbers, you say, ah, this is great.

It's actually often used even as a measure of intelligence for how much data can be compressed and that's only possible if there are patterns in the data that you've discovered and, uh, I think now something feels very beautiful even if it is. . t in the traditional sense of being symmetrical, but if you simply find patterns and structures there, for example, I once pulled out a book on an old library shelf with about a hundred thousand numbers that measured the wavelength of the spectral lines that came out of atoms, we can now calculate all those hundred thousand numbers from three numbers in the Schrodinger equation, which is also beauty in this sense of AI, where you get a lot more out of the theory than you put into it.

Thank you very much and finally Juan Malacena, can you please leave us? Let's know if in your world mathematical beauty is a guide to the truth, well, I think that beauty is a bit in the idol of the spectator, so I think that mathematical and physical consistency is a guide to the truth and by mathematical consistency I I mean internal consistency. of equations and by physical consistency I mean that it reduces to known physics in the appropriate regimes, so we are talking about the fundamental theory here. So physical consistency includes reduction to semiclassical general relativity and also to the standard model of particle physics, I suppose.

In general, we could demand that it be reduced to general relativity plus some quantum theorem, not necessarily the one of the standard model, since as we discover deeper theories we discover that, in some sense, they are simpler in the case of the standard model and the gravity. They are also based on something called the gauge principle which involves some, say, so-called symmetry. It's not a symmetry in the standard sense, but to the extent that symmetry is psychologically associated with beauty, then you could call them beautiful and, for some. Reasons why sometimes people say that theories that have a larger gauge group are more beautiful, but this is a bit subjective.

We also have concepts like Simplicity, like say in Occam's razor, so sometimes the simplest theories are called Beautiful. I mean I think the bottom line is that the theory is beautiful when it works and by works I mean it is mathematically and physically consistent now of course whether the theory is true or not is then decided by experiment so if you agree, but if for a theory to agree with experiment, it probably has to be a physically or mathematically consistent necessary condition, so I think those two conditions are a guide and I'll also end here, we're talking about the beauty of theories, but I would also say that sometimes experiments are beautiful, so they are beautiful when they manage to do something seemingly impossible, for example, you could say that gravity wave detectors are beautiful in this sense, thank you, this is amazing because you've provided a brilliant transition to our first thematic question that kind of intensifies the initial one, um.

Juan, when you say that a theory is beautiful when it works, that is, mathematically and physically, what do we do if these two disagree with each other? Um, our initial description cited, Paul Dirac says that it's more important to have beauty in the equations. have them in experimental form, was he right about that? Max, I'll send it to you first. It is more important to have beauty in one's equations than to have them in shape, to experience what you think about this, well, sometimes it is better to be. uh wrong in an interesting way than right in a boring way in the sense that the former can sometimes point the way forward.

I think that's why you were referring to Iraq and I want to add what you said there about Occam. razor because I think that when we say that a physical theory needs to work correctly, what we really mean by that is not only that it should be able to explain all the measurements so far, like all those spectral lines in the book, but that it should also be able to explain all the measurements so far, like all those spectral lines in the book. capable of predicting new things we haven't seen yet and that's where the beauty of Simplicity really shines.

You know, this is well known in machine learning: if you don't insist on having a simple description, you may encounter the so-called Overfitting Description which simply memorizes all the data and is useless for prediction, but the more beautiful your theory is in the sense of being minimalist, be short and have little information, the morewill generalize into the future, in a sense, there is this. The free lunch theorem, also known in complexity theory, says that if someone gives you just a string of random numbers, there is no algorithm, there is no computer program with fewer bits of information that can generate that, and so on, when we find a way. a physical theory that can describe a lot of data beautifully in a sense, in the sense of Occam's razor, by doing it with much less information, we know that this is not random data, that we have actually discovered some pattern and there it is where power arises. of generalization comes from the power of making new predictions in physics for things we haven't seen yet and when you check it, you know, wow, the prediction worked, missio, does that sound good to you that you get us the simplest, you get the simplest possible? theory and you maximize the chance that it can fit new experimental data yeah I think so and it goes back to when I was in high school when I was in high school I was struggling to learn the Schrodinger wave equation which was horrible it was ugly I said to myself how can God be so malicious by creating this short angelic wave equation and then one day I picked up a book and there was the Dirac equation simple elegant beautiful beautiful all the difficulties summed up in a half inch long equation theory of electron and I started to cry, well I had never done that before crying over an equation and then I realized that there is something hidden there, power that beauty is not just for beauty's sake, it is power, power to calculate things, power to understand the universe and then when I got into quantum gravity we had to calculate the scattering of gravitons and when you do that, the loop diagrams that you get diverge, they blow up in your face and it seemed impossible, absolutely impossible, to create a quantum theory of gravity because every time you calculate the search diagrams they blow up in your face and then one day I read an article where they showed that there are actually two sets of search diagrams, one family diagram set has, let's say, one electron going around and the other has a super electron going around and they canceled exactly this for me it was a shock because it meant that again beauty is not this in itself, it's just not there to be admired and people say oh wow, that It's pretty, no, it has the power to eliminate divergences, in fact.

As far as we know, the only known way to eliminate the divergences of quantum gravity is through supersymmetry, so that super particles cancel each other out. Such a simple idea. An idea so simple that it has the power to do something that greatest minds couldn't do. I gave up trying to quantify gravity because every time you quantify gravity it blows up in your face and there is a solution: symmetry, supersymmetry, the symmetry of particles canceling out against their superpartners and of course we still don't have any experimental data at all. regard. It's a shame, but deep in my heart I believe that one day we will find out, so the theory is going to lead the experiment that nature is telling us something, that all the divergences of quantum gravity are there for a reason that points in the direction of supersymmetry which As far as we know, is the only way to cancel out the horrible Infinities in quantum gravity Sabrina Hussenfelder, how are we doing so far?

You and your keynote talked about the importance of contextualizing our ideas of beauty, that different people find, different generations, particularly of people, find things. beautiful at different times um do Simplicity and symmetry are always beautiful they are beautiful from a limited perspective are attachments to simplicity and symmetry maybe they lead us down the wrong path or you think this is correct if we stick to the principles of simplicity and symmetry, we will eventually find out that our theory does, in fact, perform experimentally well, it just didn't work with supersymmetry, so I'm not sure there will be as much of a question, as if people had been looking for Grant's unified, supersymmetric theories . particles since the 1980s and they haven't found them so clearly, it doesn't work, but maybe let me, let me go back to the question you asked about Dirac and his statement about beauty because I think there is a kind of victim. from his own success, so he derived this beautiful equation and he didn't really know why it worked, so he tried to find an explanation and I think he stumbled upon this idea of ​​beauty, so he started thinking that his sense of beauty was what led to this success and then you tried to use it again and it didn't work, for example with your um, what did you call it the large numbers hypothesis? um, so I found it interesting what the owner said about consistencies or inconsistencies because what Iraq was really doing with his equation was that he was trying to eliminate an inconsistency between special relativity and the then-known version of the Schrodinger equation, so he misidentified the source of his success and, to some extent, still suffered from this today.

The theory was actually an approach to trying to resolve an inconsistency since a machine said it correctly. As far as I know, it was never shown to actually resolve the inconsistency. Do you want to come back here and weigh? Yes, well, regarding the question, of course, if you take the question out of context, it is of course incorrect, what the ACT probably meant was that an interest in mathematical structure could lead to an apparent contradiction with the experiment , but there is usually a long chain of reasoning in the interpretation of experiments, for what he meant. that perhaps it is more likely that there is some error in the chain of Reason in the theory now it is also true that his accent later in he said this later in his life the ark was trained as an engineer and it was important to him that the questions worked in the sense that we mentioned before and was interested in symmetries and general principles and, of course, had tremendous success with the direct equation and its prediction of the positron.

He also suggested the existence of monopods which haven't been seen yet but it's very likely that they exist um and Sabina mentioned the fact that varying Newton's constant with them is a case where it didn't work now, an interesting example I think which is what Yam Mill's theory is for, so when young people and men proposed the theory it was supposed to be applied to the description of pions and it didn't work but then it was useful for the development of the standard model so it was applied to weak interactions and strong interactions. Another example is the following in 1939 in a thought Iraq said in a talk on the power of mathematics and physics that the group of Analytical Transformations in the two-dimensional plane was an interesting mathematical topic that could be interesting for physics who did not know how , but actually in the 1980s In fact, this was brought to the study of phase transitions in two dimensions by 11 polarconological and we used it to explain experiments and so on, so that's a case where you know some beautiful mathematics that then they had some implications for um, let's look at another example of a famous mistake.

What came in handy was when Einstein thought it was mathematically elegant to include the so-called cosmological constant in his gravity equations and then called that his biggest mistake and now, of course, in retrospect, we know he was right, it's actually Dark. The energy in our universe and much more than that of the type of atoms that make us up is there to move on to the second topic, although there may be some assumptions that cannot be demonstrated experimentally or that will not be demonstrated experimentally. Should we accept the idea that some of the assumptions of the foundations of physics, for example the idea that there is a grand unified theory, could be similar to religious convictions?

Are these types of assumptions? Faith disguised as mathematics. um Sabina, I'll start. with you, well, I guess it depends on what you mean by accept, so should we accept them as the evidence establishes? No, of course, not because they're not sure we accept them as inspiration that physicists use to develop new hypotheses, uh, that's fine with me. because I'm a very pragmatic person, you know, as far as I'm concerned, anything goes if something turns out in the end, but there's a risk, you know, that people run into dead ends and then it sends them in front of a wall and looks the beautiful wall and we're not going to get anywhere, so I think one has to be a little bit aware of um, you know, what is faith and what is actually, um, science, what about you, Michio , you think these assumptions say that the notion that there is a grand unified theory that has the structure of faith or is different from faith.

Well, I personally believe that eventually all things are testable, it simply means that our instruments have to be improved to the point where they can reveal the true nature of things. For example, dark matter, we don't know what dark matter is, it makes up most of the matter in the universe. Some people think it's a presence of supersymmetry, which of course is a symmetry of the string, particularly the photino, when you look at the fortino. you discover that its properties are what you want it to be massive, it's not massless and it's invisible and that's exactly what dark matter is.

If I had dark matter in my hand, it would be invisible, and yet it would seep through my fingers. We've never seen anything like this before in a stable on a stable physics canvas, but now it's in outer space which won't cement string theory, but I think it would go a long way toward proving that supersymmetry is legitimate. Physical symmetry of the universe. There are also other ways to test these theories when we look at the fact that string theory exists in other dimensions. Some people laugh and say this is science fiction, but scientists are already trying to observe deviations from the inverse square law. this goes back to Isaac Newton Newton would say that in his living room gravity decreases as the universe squares off through his living room that has never been duplicated experimentally, but now our instruments are at the point where they can do that and That is why we can look with deviations from the inverse square law that would indicate the presence of higher dimensions and also satellites in outer space.

We are talking about the Lisa laser interferometry space antenna that will give us the best view of creation itself. Now, of course, it is very difficult to observe the creation incident. There was so much radiation back then, but we hope to get a snapshot of the moment of creation and String Theory really takes you before the Big Bang. String Theory does not stop at the big bang, but even before the Big Bang, and therefore this gives you a testable parameter by which certain string theories can be discarded if they do not fit the characteristics of the universe as such. as it was being created now, of course, we cannot measure the universe before creation, but I believe that the universe at the instant of creation itself eventually will. be measured by satellites and that will give us a third way to test these theories so, in summary, I think that yes, all the gray theories can be tested.

Does anyone want to come in here? There are two things I'm hearing from Michio and I think are you going to do it? Max, yes, first, I would like to say that, for me, the central principle of science is humility in the sense that I prefer to have questions that I cannot answer and answers that I cannot question. That's what I mean when I say I'm a scientist and that humility includes always being open to the idea that my favorite theories are all wrong, but like Mitchell said, always testing them, testing them, testing them, I wanted to also comment on what Michio said about how more and more things become testable and makes it clear that even if there are some things that cannot be tested at all, that does not mean that the theory that emerged from itself is not scientific because when we test in science they are theories, not things So for example Einstein's theory of gravity is absolutely scientific because it makes a lot of predictions that we can test and have tested like Mitch you mentioned, but it also predicts what happens inside black holes that we can't test and then come back and publish it in the physics journal, does that mean that relativity is not scientific, of course, doesn't it mean that we shouldn't trust that generativity predicts what happens inside black holes?

What happens inside black holes, you have to come up with a new theory that says something different about what happens to what you can't test, but still Express explains everything else that we can test and that has proven to be very difficult. in many of today's biggest controversies. physics, where some people are quick to dismiss them as science fiction, are exactly in this category, for example, inflation is the most popular theory of what caused our big bang explosion, we currently do not have the technology to directly measure someof ordinary matter. This is incredible, which is why string theory has had absolutely explosive interest in recent years because of that work.

However, there are some flies in the ointment and I believe this has not happened. It hasn't been mentioned yet, but I think that one of the problems with string theory, and although I promote the theory, is the problem of the landscape that the theory offers, is not only something that is very close to our universe, but perhaps offers an infinite number of others. Universes, a Multiverse of universes, now of course Marvel Comics and Hollywood have discovered the Multiverse, the Oscar winner, etc., but we physicists take very seriously this idea of ​​the Multiverse and the way in which We deal with this usually with computers, for example.

When we calculate the mass of quarks that interact with other quarks to create subatomic particles, the human mind is not strong or intelligent enough to do the calculation, we do it using computers with something called lattice gauge theory and that is why we have stopped trying to have the human mind master quark dynamics, we depend on computers so I think it's a long shot that quantum computers could eventually give us insight into the true void of string theory and by this I mean using the quantum to separate The mysteries of digital quantum computers are not powerful enough to probe the different gaps of string theory, so I think that maybe one day a quantum computer will be powerful enough to probe the quantum universes that enter in string theory and just remember that even ordinary quantum mechanics has this problem.

Quantum mechanics is where the whole Multiverse problem originated from, so we think that something that plagued ordinary quantum mechanics also plagues string theory and the ultimate solution may be to use quantum to defeat quantum. who use quantum computers to gain insight into the true vacuum of string theory, that's fascinating, um, so taking that to transition into our final topic and asking, um, we keep it seems in its limits, in the limits of theoretical physics in particular, um, clashing with assumptions about the first. On the one hand, and conclusions, on the other hand, that may in fact remain untestable, such as the very existence of a grand unified theory, whether it exists or not. the notion of a type of Multiverse or another type of Multiverse a Quantum Multiverse String theoretical multiverse the inflationary multiverse are these the same multiverses what happens inside black holes um what happens what exactly does inflation look like there may be some lingering instabilities here does this The untestability of your mind undermines the pro of the project of the physical or strengthens it and Juan, we will start here with you.

I think when we talk about physics in general I mean that most of physics is based on proven theories and in contact with experiments and So I want to say that here we are talking about the search for the next layer, so unknown the fundamental laws of physics and I think that for this the most important thing we can do is continue experimental exploration so that the construction of more powerful and rich accelerators. at higher energies, the telescope is better, telescopes that see deeper into the universe, including gravity wave detectors, etc., and are also interested in small-scale experiments that look for new particles, from axions to matter dark, etc., now what are we talking about?

What is discussed here is only one aspect of the fundamental theory and, in particular, the aspect having to do with quantum gravity, which is very difficult to test experimentally with our current and near future experiments; However, it is a clear inconsistency in our current understanding, so we might hope that only with the coherence criterion could we make some progress. It's something that had worked in the past with, say, Maxwell's equation, so the development of general relativity, but that's what we're talking about here, going to very high energies. much higher than what we could reach in the near future perhaps if we understood the theory well enough then we could make a prediction that we could test perhaps through some cosmological observation but as we said our theories are not understood well enough to make these predictions um so I think overall we're progressing towards developing this theory just based on consistency um and there are various ideas that people bring um I mean sometimes ideas sometimes come out of it's not directly related to string theory, so for example there was a recent development on holography using the so-called guitar model yes, so it's a model that was inspired by condensed matter physicists and before we were talking about symmetries and An interesting aspect of this model is that it is based on the disorder of random interaction, so the complete lack of symmetry, so it is the completely opposite philosophy, but the model itself develops a kind of symmetry from the interactions, so it's a new idea that people are exploring and we are exploring, in some ways we are connected to other ideas in string theory, but it is not directly related, but this is an example of how to look, how we are looking, an example of the methods we are using to search for theories, find general principles and take ideas from other areas of physics as well, what do you think, Sabina, are we getting closer?

We are improving? Technologies will help eradicate some of the limits we have encountered. I'm going to improve testability, things like that, yes, but probably not in the way Huan imagines, but first I want to say something else, so Mishu said that we physicists take the Multiverse very seriously . I would like to object that I don't take it seriously and I'm pretty sure that if you took a representative sample of our physicists and asked them about it, you would find that most of them don't take it seriously. I wanted to say this because, because the sample of physicists that you see at events like this or that that you hear about in the media or something like that doesn't give you a good impression of what most companies actually work on, so when it comes to new technology, I think where we will see the most progress is probably quantum technology because there are so many things happening there, like quantum computing, quantum optics, quantum information, quantum subway biology, quantum sensing, there are so many things happening, I think sooner or later they just stumble upon something they don't understand and then they'll come and ask the theorists, how do you explain that?

And then I think from there we will develop a new theory that goes hand in hand with my belief that it is a mistake to try to blame gravity when it comes to the unification of Einstein's theory and quantum theory, people He has tried to manipulate gravity, he tries to quantify it. I think our problem is that we don't really understand the quantum part of the question, which is why I think this new technology will help us make progress happen again, the fundamentals of physics are fantastic, well, it seems that even if we don't agree perhaps on the state of the Multiverse, both are hopeful that Quantum Computing will help us get there. past some of these some of these impasses well thank you all so much this has been a really wonderful conversation please join me in thanking our speakers for more debates, talks and interviews subscribe today to the Institute of Art and Ideas at IAI TV.