Into the Impossible With Brian Keating - Juan Maldacena: On Theories of Everything, Blackholes, Wormholes, Inflation, & God vs the Multiverse (#077)

Episode Date: September 24, 2020

  Juan Maldacena joined me to discuss his fascinating new paper on human traversable wormholes and other topics in fundamental physics. Join in the chat to participate! We discussed the Multiverse, Black Holes, Wormholes, SETI, Life on Einstein Lane, Interstellar the Movie, and even God! We chatted about his recent paper “HUMANLY TRAVERSABLE WORMHOLES” https://arxiv.org/abs/2008.06618 which is based, in part, on this earlier paper: “Traversable wormholes in four dimensions” https://arxiv.org/abs/1807.04726 When you sign up for my newsletter, I’ll send you links to download two explanatory talks on these papers. Please join my mailing list; just click here http://briankeating.com/mailing_list.php We also discussed an interesting economic analog to the Higgs Mechanism first elaborated by Dr. Pia Malaney and Dr. Eric Weinstein, explaining gauge theory and electromagnetism. See Juan’s paper “The symmetry and simplicity of the laws of physics and the Higgs boson” here: https://arxiv.org/pdf/1410.6753.pdf . You will also enjoy his video lecture based on that paper here: https://www.youtube.com/watch?v=OQF7kkWjVWM 0:00 INTRODUCTION 04:00 Black Holes and Hawking Radiation 08:00 EPR states and Black Holes 13:00 Is faster than light travel possible using Wormholes? 20:30 What happens if you fall into a Solar Mass black hole? 25:30 Is studying wormholes a waste of money and time? 30:00 Why are there so many theories of everything like Weinstein, Wolfram, Lisi? 37:00 Cosmic Microwave Background non-Gaussianties and inflation and the Multiverse 44:00 Why are lower limits in physics so important? 52:00 What experiment or theory would Juan pursue if money was no object? 59:00 What is a gauge theory and how can currency trading in economics explain electromagnetism 1:09:10 What’s a day in the life of a Professor at the Institute for Advanced Study? 1:13:40 Juan’s Ethical Will 1:15:00 Juan on God, the Multiverse, aliens and more! 1:18:00 What would Juan put on his monolith? Juan Martín Maldacena (September 10, 1968 in Buenos Aires, Argentina) is a theoretical physicist and the Carl P. Feinberg Professor in the School of Natural Sciences at the Institute for Advanced Study. He has made significant contributions to the foundations of string theory and quantum gravity. His most famous discovery is the AdS/CFT correspondence, a realization of the holographic principle in string theory. Brian Keating’s most popular Youtube Videos: Learn more about your ad choices. Visit megaphone.fm/adchoices

Reminder to please subscribe to my YouTube channel, DR Brian Keating, for a video version of this episode with Malden Maldesana. It's full of interesting visualizations and other fun things. And I hope you'll subscribe and enjoy the rest of my channel and all the videos I put out there about one or two per week. Any sufficiently advanced technology is indistinction from magic. Hello, everybody. Watching out, hopefully, on YouTube and elsewhere.

I am Brian Keating, the fearful host of the Into the Impossible podcast. And today I'm joined by none other than a legend in the world of theoretical physics, cosmology, even I want to pick his brains about economics and other things that you might not associate with a physicist working at the Institute for Advanced Study. But, Juan, I want to thank you for joining us today. How are you doing? Hello, nice to see you. It's good to see you, too. So what I originally pinged you about is your willingness to come on to discuss a topic that we've been reviewing in my research group of cosmologists here at the University of California, San Diego.

We like to do things outside of our comfort zone. And one of those things is to do research into the very deep and provocative aspects of theoretical particle physics and also to investigate perhaps the deeper philosophical. implications of the work that we do and not only just turn screws. There's nothing wrong with turning screws, but certainly it's fun to get out of our comfort zone. And so we've been reviewing your papers on wormholes and even went to your back catalog, as they might say, and went into the original papers on the subject. And we came up with a lot of questions, but hopefully we'll be able to answer some of those

and some from the audience who's listening as well. So the paper in question is entitled Humanly Traversible Wormholes. And I wonder if we could start off by talking about the inspiration for that paper and its predecessor paper, which was traversable wormholes, not speaking specifically about humanly traversable yet, but in 2018, you and your colleague Alexi and Fodor Popoff wrote a paper called Traversible Wormholes. I want to ask, what was the impetus for you to investigate something so potentially fantastical as a wormhole? Well, this came out of thinking about black holes and the black hole interior and entanglement. So there is, of course, wormholes are fascinating to think about regardless, and that's also why we're thinking about this. But wormholes seem like they are very exotic. However, something like a wormhole is already present in the simplest solution of general relativity.

So if you take the general relativity with the vacuum solution and a spherically symmetric, you assume spherical symmetry, there is some solution which Schwarzschild wrote, which sometimes we call it the black hole solution or the Schwarzschild solution. And that solution has the peculiarity that it has two exteriors connected by a single interior. And this was a funny feature that Einstein and Rosen noticed in the 30s. And yeah, it's been well known for a long time. And so this solution has the geometry of a wormhole. At a spatial instant, so at an instant in time, you have a three-dimensional space. Our three, let's imagine you, we had the solution.

we would have our three-dimensional space is connected through a wormhole to a second copy of another three-dimensional space. It has the funny feature that the warmhole is not traversable. So if you try to go from one side to the other, you find that the solution is time-dependent, and this geometric connection closes off, and there is a part of space that shrinks. You have a kind of big crunch in this warmhole.

It shrinks. It's very similar. to what would happen if you took a piece of dough and you stretched it a lot, it becomes very thin, and that's what happens to this geometry. And the resulting very thin space is what we normally call the black hole singularity. So if you try to traverse it, you just end that singularity, you die. So not fine. That's not avoided, yes. Yeah. So that's present already in that solution. It's not traversable. And I should emphasize that if you had an actual black hole that is produced through astrophysical processes,

you don't get this full solution. You only get a portion of this solution because usual black holes are not the solution of the vacuumized and equations, but the solutions with matter. And those black holes, those black holes would have a geometry similar to the one we discussed after a certain point. And then you encounter the matter of the star that produced a black hole in space, somehow ends there and it doesn't have a second side. But it's a very closely related geometry, certainly allowed by Einstein's equations.

It's the simplest solution of enhanced equations. Okay, so that's one geometry, that's one part of the story. Another part of the story comes from a different line of reasoning, which is thinking about hawking radiation. So black holes have this funny feature of emitting some radiation, so even though they are solutions in the vacuum, they look like thermal objects. They emit radiations as if there were objects at some temperature. And this radiation is very small for astrophysical black holes, but could be larger for smaller size black holes.

So you can even run into the paradoxical situation of having a white black hole, because if the black hole has the size of the order of a micron or smaller than macron, the same. The size of the wavelength of light, you would see it white. And so that's a feature of black holes that involves quantum mechanical aspects. And by thinking about this quantum mechanical aspects and some other features of black holes, people came up with this conjecture that I would like to sometimes call it the central dogma of quantum black holes. It's like, you know, like there is a central dogma in biology.

there is central dogma of quantum aspects of black holes, which is that if you look at the black hole from outside, you can think of it as an ordinary quantum system, as an ordinary system. It obeys the loss of thermodynamics, it obeys the loss of quantum mechanics, and so on. And it does so in a rather non-trivial way, in an intricate way in which the loss of physics conspired

to give a picture where this would be consistent. And if you apply, if you have this solution like the one we discussed with Charlisle that contains, there's a closely related solution where these two space times that look completely disconnected are actually part of the same space time. So you have a solution which looks like two black holes that are separated in space, but are connected through, are connected through the interior. So they share a single interior. And the idea is that if you apply, this sort of central dogma separately to each black hole,

so each black hole can be replaced by quantum systems. And then the peculiarity that produces the connection is, or the idea is that the connection would arise if these two quantum systems are entangled with each other. So they have EPR or Hansen-Poloski-Rosome entangment. And yeah, so that's an idea for what, it's an interpretation if you wish, of the, Shrarshal solution in light of this results of Hawking and others about quantum aspects of black holes.

And again, there the fact that it is not traversable is good because you cannot send information using entanglement. So it's a consistency. I mean, it's consistent with this interpretation. Now, and people, well, we started this relationship a lot to try to learn about black hole. whole interiors, basically. That's how we should think about black hole interiors. There are weird features about black hole

interior such as this one, the two separate black holes can share the same interior, for example. And so it's like an exotic system that we would like to study to understand better than black hole interiors. Now, the next development in this direction came from an observation paper. paper by Gau, Jeffries, and Wohl. And they realized that if you introduce some interaction between these two black holes in the ambient space,

you could get a signal to go through this wormhole. And send the signal is closely related to quantum teleportation. So if you have two quantum systems that are entangled, then by doing certain measurements and sending qubits on one of them and sending classical information to the other, you could you could send a qubit, you could teleport the cubit. And in this gravity picture, the qubit is really going through the wormhole. So you create, you do a certain operation using the information. Roughly speaking, what you do is you measure the hooking radiation on one black hole.

And, sorry, I should start from the beginning. You have the two entangled black holes. You send the cubit that you want to send into one of the black holes. Then you measure the hocking radiation of that black hole. You send the information to the other. And by knowing that information, the person in the other black hole can send a negative energy pulse. It's something that normally could not be done into a normal black hole. But if you, roughly speaking, the hawking radiation is random.

But if it is entangled with another one and you measure the other one, you know what is going to happen. It's like having inside information. It's like in the stock market. It looks like a black hole if you don't know nothing, but if you have a friend inside the company and tells you something, then that. I would never do that. I would never. We'll cover economic trickery when we get to the Higgs mechanism, but. Yeah, yeah. But this is similar in the sense that you can lower the energy of that black hole.

You send in some negative energy pulse, and then you can get out of the, from the interior of this cubit that you sent on the earth side. So it's an interesting picture for what's happening with quantum. teleportation at least in this setup. And yeah, so the, these papers that you mentioned were sort of developing this idea a little more, just looking for situations where very naturally you would have this interaction between these two black holes, that it would happen in ordinary four-dimensional black holes and so on. And so the crucial aspect in both, well, in all the solutions, is to have two black holes that are relatively close to each other so that there is some interaction between them and

So that this and this particular entangled state of two black holes is the ground state configuration of the two black holes That's the quantum mechanical interpretation if you wish or in terms of gravity that you can form You can connect well you have this connected wormhole But but you create some negative energy through some fields that propagate in the space time. So space time becomes topologically non-trivial. What it means is that it develops some kind of handle. So you have the two black holes that are like little holes in space and you should picture them as connected by a kind of holes that connects the two black holes. So you can have particles that go

inside the hose and then come out in the space and then go in again. And the propagation of these particles create some negative anarchy. So in quantum mechanics, you can have negative energy. And that stabilizes the whole setup and makes it possible to have a traversal warmhole. Now, these traversal warmth holes, you build this way, are consistent with causality. So what does that mean? That means that if you go through the wormhole, you come out on the other side, later than

you would have come out if you had stayed outside the warmhole. So they cannot be used for traveling faster than light. So in the science fiction literature is common to find the wormholes that are used to travel faster than light or travel to the past, for example, and so on. But this we think are deeply inconsistent with the loss of physics. So there are different things you can mean by loss of physics. So there are general principles of physics that were established in the beginning of the 20th century, like general relativity, quantum mechanics, quantum field theory. So these are, this is a kind of framework, general framework with certain solid principles.

So particular theories that we have today obey these principles, but they kept changing because we needed to add more particles, we needed to add lots of particles since the beginning of the 20th century, all the quarks, all the, we now probably need to add dark matter particle and so on. But whenever that was done, it was done within this framework. So we can ask what is possible within this framework. So what is possible with ordinary, this is what I'm going to call ordinary matter, or non-exotic matter. So it doesn't mean the actual matter we have in nature,

but it's matter that obeys these kinds of principles, we could in principle have perhaps, but we haven't detected yet, for example. And the idea is that with this kind of matter, you cannot produce wormholes that allow you to travel faster than light. And that's very good. It's actually an interesting theorem in, well, that this is not possible. It wasn't completely proven, but several aspects of it were proven and it's an interesting interplay between positivity conditions of energy in relativistic quantum field theory and general relativity. I mean at the level of geometry you can imagine a geometry that connects points that are far away. I mean

nobody forbids you from writing down that geometry but Einstein theory is more than just arbitrary geometries. It's geometries that obey a certain equation. It's called the Einstein equations and the equation relates the shape of the geometry to the amount of energy, yeah, the amount of energy present in this geometry, energy or matter, or matter density, etc. And these shapes that would allow you to travel faster than light, they require a certain kind of negative energy, which is under those circumstances. A certain small amount of negative energy is allowed by quantum mechanics, and it's what we exploited in these solutions that we have this.

And so they allow you to construct these wormholes. It's interesting that you could have these configurations which have topology different than the topology of four-dimensional flat space. They seem difficult to build. So we only show that there are solutions. We don't know how you could develop them into solutions. And one interesting aspect is that the first solution, the first paper you mentioned, discusses these solutions. in the context of it could even be the standard model. So it could be the matter that we know, but at very short distances.

So distances that are so black holes that are very, very tiny. I mean, those black holes would be extremely difficult to produce by artificial or maybe natural means as they were producing the variable universe. And that's one possibility. So. And those differ from the, the 2020. paper differs in that it's actually displaying a five or higher dimensional background universe as opposed to the 2018 paper, which was a four-dimensional universe.

Can you comment on why you, it seems like we know we live in four dimensions, so why would we consider higher dimensions? Why can't we make it work in four-dimens, a humanly traversable wormhole in four dimensions? Right, right. So the construction we had in the 18 paper relied on the existence of light matter, some light matter fields. So matter fields, which are, let's say, almost massless. And we don't have such, well, we have the photon in nature, but we also wanted some charge matter fields, and we don't have those. We don't have massless ones.

We have the lectum that's massive. And so the idea was to postulate that maybe we have some kind of dark. sector. So the dark sector would be some type of matter that we only interact with gravitationally, but not directly. So in principle, it might be possible. And postulating such that dark sector, we were asking whether it would be possible to a wormhole that is big enough that a person could travel. It was mostly as a fun project, so just to see what's possible. And there is These models that involve extra dimensions are kind of equivalent to a certain type of four-dimensional matter theory, of four-dimensional very matter theory, massless matter.

And when it's very strong interacting, it could be realized in terms of an extra dimension. And these models were discussed in the past, so people thought, oh, maybe there are extra dimensions. So you could have, if the extra dimensions were flat, like flat space, they could have a size, which is somewhat smaller than a millimeter. Well, now I think there is 50 microns is the current limit, so it's fairly smaller. Anyway, so that's the current limit on the size of extra dimensions if they were flat. But Randall and Sundrum realized, so to researchers, they realized that you could have this extra dimension could be actually have infinite, infinite size as long as the space was curved.

And so, so you have the extra dimensional space is curved, has negative curvature, and then the extra dimension is large. And it's, the physics of this problem is essentially equivalent to adding massless matter to four dimensional phase, to four dimensions. If you don't like to think in terms of five dimensions, you can think in terms of four dimensions. And, In this setup, you could, by making the size of that extra dimension largely enough, so further the experimental limit, current experimental limit of 50 microns, you could have in principle traverse our warm hole, which is large enough for a person to go through it. So let me just maybe discuss how big it should be for us to go through.

Yeah. Now, it's often said that when we fall into a black hole, we die at the singularity. because the tidal forces or the forces of gravity will kill us. But we could be falling into a black, I mean, if we fall into a stellar mass black hole, for example, so a black hole with the mass of the sun, which has size of order a few kilometers. So if we fall into such a black hole, we are still bigger than the size of the black hole, but we would be killed before we get even to the horizon. Because we are very frail people.

We are very sensitive to tidal forces, and if we are pushed from the head and the toes in different directions, we might die. So actually, you need some black hole of further the size of the earth, so the horizon should be a horde of the size of the earth, in order for us to fall and not die at least at the horizon. And for similar reasons in this warm holes have to have a neck or an opening. So I mentioned the host before connecting the two points in space time, which has a size which is bigger than the size of the order of the size of the earth and Under those circumstances you could fall in and not be killed by the tidal forces The tidal forces the force is similar to the forces of tides that create the tides in the surface of the earth Yeah, on the earth

Anyway, so that so that requires pretty big black hole so that's a little unfortunate that we are so frail and this mechanism that produces the wormhole is also very well it requires some phantom mechanical effect so it's not too efficient so you can make more holes for their separate they will be separated the travel time will be very long so it would be for the 10,000 years so that's the time it would take you to go through the wormhole as seen by someone who remains outside the warm. Now something quite fun about this is that if you for the point of view of the person that goes through the wormhole that time is much shorter.

That time is about it's less than a second. So it's a bit like the twins paradox. So in the twins, in the twin paradox there is one of the twins remains at rest and the other one travels at very high speeds and then returns. Then the person who travels at high speed and returns is much younger than the person who stayed at rest. So this is something similar happens here. The person who goes through the wormhole is much younger than the person who sits outside the warmhold. And what do you attribute the kind of fascination that people have if the time travel aspects,

as you guys show, are really not possible in the classic sense and the interstellar movie sense, so to speak. Why do you think people are so fascinated in it? Why do you think people use this as a plot device so frequently that it's almost become kind of a trope in a sense that people really look to wormholes to solve a lot of problems in movie plot devices? Yeah. Well, I mean, the speed of light is tough. I mean, it doesn't allow us to go too far. They say it's not only a good idea. It's the law, right? Yeah, it's the law and it's, well, I think authors like to go outside the realm of ordinarily established laws of physics. They, usually the statement is, oh, well, now we, that's what we think now, maybe in the future, we'll realize there's a way to go around

it. And that might well be true. So it might well be true that we find the way to around. But But going around this, it's a very serious change to the loss of physics. So I personally would bet very strongly against. Actually, I remember a few years ago, there was an experiment claiming that the neutrinos travel faster. Yeah, the opera experiment. That's right. Yeah, so I met one of my neighbors. So, oh, you see, you know, relativity is wrong and so on.

So I said, okay, fine. I bet you $1,000 that this experiment will go away. he didn't want to take the better. Financially wise. I mean, it is possible. Everything is possible, but there are some things that are more unlikely than others. Yeah, a lot of times we talk on this channel and we have talked about, you know, theories of everything, which I definitely want to get into with you as well.

I can't miss the opportunity to discuss it. But, you know, oftentimes this kind of perception that such things are not really falsifiable or not testable. And so why should we kind of expend time, energy, money, which is so finite in value, in amount, but infinite in value. What are kind of some of the motivations to study these things when, you know, for example, some of the criticism, you know, on the internet of the recent humanly traversable wormhole theory is that, you know, we don't even know if the Randall Sundrum cosmology model five or whatever even exists and there's no evidence for that. So why study, you know, kind of an edifice that's built upon something which may not even

exist? Right, right, right. So here, here we are exploring not the things that nature exists, but possible natures that are consistent with the loss of the general principles of physics, general relativity, a special relativity, etc, quantum mechanics. With the goal of just understanding what is possible. The goal is not so it's not so much to go and build and look for this wormhole. It's just, well, that paper was just the fine exercise, but the main goal is to, I think the main goal is to understand black holes better, quantum aspects of black holes, with the goal of understanding why, well, how quantum gravity works. So black holes are an interesting problem because they force us to think about quantum gravity in interesting ways.

And if, does that not presuppose that there exists a theory of everything? In other words, is it mandatory? Certainly it seems that wormholes, at least non-simply connected regions are permissible in classical GR, but certainly to have the wormhole as described in the paper seems to rely on quantum processes, as you very rightfully explained. But I want to ask maybe a deeper question. which is kind of your opinion on theories of everything in general, which is that, you know, do we need a theory of everything?

Is it mandatory that we have? I don't like to match the word theory of everything. Yeah, me neither. I didn't use it, no. But I think what we need is a theory of what we would call quantum gravity. So quantum mechanics of space time or a theory of quantum space time. And this is needed because the current theorists do not explain what happens in certain circumstances. like what happens at the very beginning of the Big Bang or what happens in the interior of black holes.

And we would need that theory to really put all these principles that we discussed of the beginning of the 20th century together. And if you call that everything, yeah, that's, yeah, of everything that we learned in the 20th century, general relativity and quantum physics. The formalism of quantum field theory came from putting together quantum mechanics and special relativity. and special relativity. And I think we'd like to put in general relativity. And this is a very, very constrained structure. So the question, I mean, one question that, I think that the fact that we need this theory is clear, you could question whether we will ever get this theory without doing experiments. So I think this is a valid question. Now, why do we think we might get theory like this,

is that, well, we have some examples of candidate theories that are mostly like, we should really think of them as theories under construction, like string theory and so on, which have lots of mathematical intricacies and are put together, managed to put together gravity and quantum mechanics. We don't know whether it's the right theory for nature. We don't know if that's the correct framework, or correct theory, special theory to describe nature, but the goal, I think, is to to is that by thinking about those theories, you might even be able to abstract some principles that could be used to describe nature.

And in the process, people discover all kinds of relationship between these theories and mathematics and other areas of physics and might even, and we now think that gravity and quantum mechanics are connected in many different ways. So perhaps a provocative idea is, that you might be able to build a little toy universe in a lab. Yeah, yeah, Zia Morali, a friend of mine, has written a book about A Big Bang in a Little Room,

which is a wonderful little book. Before I turn to questions from the audience, I do just want to follow up and just, I can't resist, and if you'll indulge me, you know, I mean, it's not so often I have a great physicist to chat with live and ask questions of a, not personal nature, but I'd love to get your opinion on why are there so many different theories of everything. I mean, there's Wolfram has one, our mutual friend Eric Weinstein has had one, Garrett Lecy.

I mean, they seem to proliferate, and these are very, very, you know, legitimate ideas, some of which are very creative. Stephen Wolfram has a completely different approach from the geometric approaches of people like Lecy and Weinstein. What do you attribute, first of all, the upsurgence and interest and theories of everything? Well, I guess it's a natural frontier and people have different ideas for how things should go. Some ideas are more developed than others and have had a mean, yeah, of course the final arbiter of any idea is to make a definite experimental prediction that, you know, could be falsified. or basically a prediction that you could go and check that this theory has. There have been no predictions like this from any of the theories.

But along the way, some theories have had more predict for, let's say, mathematical predictions or predictions for other areas of physics or some more interesting structure. And some are consistent with these principles of the 20th century physics that I discussed, and some are not. So, for example, it's not clear whether Wal-Rams ideas are consistent with the principles of relativity and causality and so on. Time doesn't, it's not. And yeah, so, yeah, I think those of us that work on string-inspired ideas, what we like is that it's a theory with well-defined rules and, well, at least in some regimes, where you can do calculations and it's compatible with this general principles of the 20th century physics.

And when we look at some of the questions are coming up about connections between quantum field theory, one of my listeners whose name is Rust in Peace, who is a frequent contributor on the channel. He's asking whether or not the black hole information paradox shows that quantum field theory is incomplete. In other words, do we need a fundamentally new theory to merge quantum mechanics and GR as illustrated by the black hole paradox? Yes, I think I think that's right. But it's incomplete when gravity is dynamical. So when the effects of when the effects of the fineness of the Newton constant is important. And then others are asking about the perceived. I get this a lot, you know, failure of string theory to, you know, come up with this. But I think,

I think you've already sort of addressed this, that it may be sort of too much to ask for, or maybe not phrasing the meaning of the word theory of everything, and maybe there's too much expectation of things like string theory. So what's your current appraisal of the state of affairs in string theory, for example? Well, I think string theory, I view it mainly as a candidate theory for quite, but gravity and it's a theory that's been fairly developed and has a very interesting mathematical structure and has led to interesting connections between quantum field theory and gravity or between different quantum field theories and quantum field theories and

quantum field theory and condens matter and quantum mechanics and thinking about yeah quantum mechanics and space time in general and if but yeah the fact there isn't a concrete experimental prediction is a problem. And I think we understood that the landscape of possible, there was a roadmap for experimental predictions in the late 80s, which was, well, we'll have this very nice 10-dimensional theory and we'll find the internal space on which it's compactified. So six dimensions are small.

We'll find the possible shapes. There will be a finite small number of possible shapes. we'll find which is the one that gives the standard model and we'll be able to calculate things. That was the roadmap. That roadmap turned out to be, well, it was more complicated than expected because there were many, many possible shapes and many, the number was so big that it's very difficult to study them, them all or study them in a way that you could really make a concrete prediction. And the current thinking is that just to explain or accommodate the cosmological constant, you need to exploit this complexity.

And so the typical, like the typical, so if you take an off-the-shelf internal space, you will get the cosmorical constant, which is too large. So the idea that the current idea, well, among all they want, there are so many that one will have the right cosmorical constant. But that also makes it very difficult to make a concrete prediction. But I mean, people are, some people are still, well, definitely many people are trying to make statistical predictions. So maybe you don't know exactly which of the vacu where we live in or which, but making perhaps statistical predictions of what that landscape is sometimes called the stringline. landscape of what that landscape looks like. I personally think that also this connection between gravity and quantum mechanics maybe can lead to a different kind of prediction, a different kind of connection between the ideas

and the rest of physics and concrete physics, which is via perhaps quantum computers and maybe quantum experiments in the lab of building something, some systems. some complex ideas that very complex systems behave in a way that can be described by a certain space time. It's not our four-dimensional space time, but maybe some auxiliary, two-dimensional space time and so on. And there are people thinking more actively about how to get these ideas to work. And so this is, again, something that people, you know, doing string theory do, but it's a different angle on the connection. And kind of an allied effect to that is located behind my upper right shoulder over here.

I'm pointing to a couple of CMB balls. I want to bring up an allied question, which is related to the multiverse. You mentioned the landscape. I want to talk a little bit about that in our remaining 15, 20 minutes that we have. So I want to read something to you from a while back in Quantum Magazine, which talked about the study of non-Gausianities. In Quantum Magazine, they say the rigorous study of non-Gausianities took off in 2002 when Wal-Maldesana, her revered monk-like theorist at the Institute for Advanced Study,

calculated what's known as a gravitational floor. The minimum number of triangles and other shapes that are guaranteed to exist in the sky due to the unavoidable effect of gravity during cosmic inflation. Cosmologist had been struggling to calculate the gravitational floor for more than a decade since it would provide a concrete goal for experimentalist. If the floor is reached and still no triangles are detected, Malasana explained, then inflation is wrong. So I want to ask you, because I actually interviewed a real monk last week.

And I have to say, you guys have somewhat similar countenances. You're very revered and very reserved, but I don't know if the monk-like attribute is accurate. But leaving that aside, behind me are these balls. I'm going to go get one while you're on the screen. But can you first talk a little bit about what is a non-Gausianity in the cosmological context? And I'll bring up some visuals for the audience while you'll indulge me. Yeah. So an interesting fact about the universe is that it's very close to uniform.

long distances. But another in fact is that's not perfectly uniform. There were some primordial inhomogeneity. So it was to first approximation homogeneous, but with tiny little inhomogenities that I guess you've been studying for your career. And that's a map of those inhomogenes, as we see them through the CMB.

This inhomogeneities is believed that they were produced through quantum effects. They were due to quantum fluctuations during the beginning of inflation. And so they are random. So quantum fluctuations are random. But in quantum theory, the randomness has some pattern. So there are different patterns of randomness. And so the simplest pattern is so-called Gaussian pattern,

where each region could sort of fluctuate in the penalty of the others, roughly speaking. It's not exactly this. but each, let's say, wave fluctuates differently from the others. And that's like the simplest pattern, the bell-care, the Gaussian distribution. But in actual theories, actual theories are interacting, and the fluctuation in one place creates some decreases or increases another type of fluctuation in a similar region. So you have some non-gousian effects.

So some, on gasp means that there were some interactions between the waves. You could view this as waves or fluctuations in the geometry of the shape of the universe. And we, this deviations from Gaussian, I think gives us very deep information about the interactions that were present during the inflation rate times, during the times of inflation when these fluctuations were produced. And so the simplest interaction that we had was interaction of gravity. So that if you have a fluctuation that created, it's created an over density. Okay, it created some gravitational potential and then some other fluctuation would look different. And that's the so-called gravitational floor. So it's the minimum amount of non-deviations from Gaussianity that you would need if inflation is correct,

at least or at least single field inflation. But in principle, there could be larger effects due to other particles that could have existed during that time. And in some ways, the early inflation is like a particle detector or a particle collider. You create all these particles that what could be created. So the universe at the time was expanding rapidly, and there's an effect similar to the effect of hocking radiation that we discussed before that creates this quantum effect, that creates these waves, these fluctuations. And it could also create other particles which

have mass proportions, the effective temperature, these fluctuations. And they, so if you created those particles, it could also imprint all kinds of interesting patterns in the sky. I mean, so far, so far no non-gauceanities were detected. So that is, so it's very, very close to Gaussian. But still, there are.

couple of orders of magnitude to go to get to this floor somehow, to this minimal amount. And I guess there are very interesting experiments going on trying to calculate this to measure, I mean to experimentally measure this non-gaussianities better. Yeah, that's right. And it's certainly a hot topic, not only the actual pursuit of non-gasianities, which is there are very few ways we can actually access this enormous particle accelerator, as you call it, which is a nice way to think about the extremely early universe. But one of them is potentially through cosmic microwave backgrounds polarization.

And in doing so, we make the hypothesis that if inflation took place, there will be this stochastic background of primordial gravitational waves, not the late-time gravitational waves detected recently, fairly recently on cosmic timescales by LIGO. But actually, we could detect a background suffusing the, early universe. Unfortunately, these are kind of like no-go theorems in some sense. And what appeals to me, and I should take a step back, what I like about the non-gaussianity effect is that it gives a prediction that's a lower limit. So I'm kind of sick of upper limits. We've had so many upper limits in physics for so long that it's nice sometimes to get a lower limit. So let me explain to

my audience who might not be familiar. An upper limit says that a signal can be no larger than a certain amount. So it says that the Higgs boson can be no larger than, you know, 300 or whatever GEV in mass. But a lower limit allows you to say that such a quantity exists and it's bigger than a certain value and in fact that value can be bigger than zero. So for example, we know that neutrinos have mass. We have an upper limit on the mass of neutrinos from neutrino oscillation experiments. We also know that there's a lower limit on the mass of the neutrino. Sorry, we know the lower limit exists from neutrino oscillations. We know the upper limit exists from from collider experiments, from direct detection experiments, and from cosmology. And so we're kind of coming at the target from both

ends. It's not enough to say I'm lower than, you know, 600 meters tall and I'm bigger than one micron tall. What you'd like to have is a very tight range between the upper and lower limits. but when you have a lower limit, it gives a target for an experimentalist like me. I always say I'm just a simple experimental astrophysicist. You've got to break it down into, and there are very few things like that. We don't know that gravitational waves exist in the primordial sense. We know that they exist in a late universe. But your work on non-gaussianities really provides sort of a no-go theorem,

which could be used in combination with the primordial B-mode search. but there's a problem in that I think that we've basically hit a point of diminishing returns. When you wrote that paper in the early 2000s, that was pre-WMap. And now we have not only the beautiful phenomenal world-changing results of W-Map, but also Plank. And it's very hard to do much better in the CMB's temperature. So I wonder, you know, how much better can we do to, you know, in your opinion, before we hit this floor, which is known as cosmic variance, beyond which we can't really improve. In other words, might your lower limit also be an upper limit

in the sense that we'll never be able to detect it because of fundamental intrinsic variances in the pattern of fluctuations in the micro-a-backer? Well, that's, I think, a subject you probably know better than me. And I'm told by the experts that with the current angular resolution that you could get the CMM. B-Bead and so on. You just don't have enough power to get to this floor. Yeah, I think we're getting very close. I mean, it's, yeah, diminishing returns in terms

of noise level and angular resolution. But there may be other triangles in terms of large-scale structure. Is that a possibility to look for non-gousy entities? Yeah, so large-scale structure is something that would allow you to go a little further because you see basically one difference is that the CMB map is two-dimensional and that's a skill structure could be a three-dimensional map and there's been also some more futuristic ideas like you're looking at the so-called 21-centimeter hydrogen emission emissions to to see the matter distribution also in the early universe and to again make a map which is three-dimensional and i mean that that might be the best hope but well people yeah this is further into

to the future. We don't know that 21-centimeter, primordial signal is really there. I want to ask you a question that's maybe a meta question. When you make a prediction about this, how difficult is it to separate your own natural curiosity and feeling of ownership over this theory? I mean, I think we could both agree. It'll be very challenging to detect a humanly traversable wormhole. But when you make predictions such as these no-go theorems for inflation or the many other contributions you've made to physics, how tempting is it as a theorist to really advocate for the pursuit of your particular theoretical models and see confirmation in them wherever they occur?

Yeah, yeah. I think there are theories that propose models. They're more phenomenologists that produce models. I wouldn't call this humanly traversal model as a particular theory that I want to see confirmed in experiment because I think it's very unlikely that the universe is described by the Randall's syndrome two model and so on. I view a little more as a theoretical fun exercise, a bit of science fiction. I told Lisa Randall that I was going to write a science fiction paper. I think you should. There would be another side of the monk known as Maldesana.

And yeah, I tend to work on things which are not predicting specific models, but trying to find general principles and, yeah, general ideas, exploring more general features. But, yeah, I, for example, with Nima, we discussed the possibility of seeing extra particles during inflation and so on through this cosmological collider. It would be really fun if that was seen. I mean, there would be, But, well, again, I don't think it's necessarily likely. We didn't think that it was the most likely scenario. Right.

So I think part of the theorist work is to figure out where interesting signals could lie or where it should look for interesting signals. There might not be necessarily the most likely signals, but if they were present, they would tell you a lot. So you should make sure there are certain signals. make sure not to miss a list. And yeah, that's part of what I'm doing. But some people are more practically oriented and want to see what is actually the data

is saying and what can be extracted from actual data that you, for example, are taken. Right. And to what extent, you know, if you were kind of a director of experimental research, how would you choose to prioritize just on a selfish level your many? enthusiasm that you have, how would you, you know, rate the likelihood of the existence of these Randall syndrome? I mean, you obviously say that there's, you know, not terribly likely, and they're almost in the realm of science fiction as are wormholes. But inflation is held in the multiverse, the string landscape, swamp land. These are all held by, you know, there's an

awful lot of energy devoted at most universities to this pursuit. So how do you, how would you, or if you were the director of all research and physics on planet Earth from your monastery, how would you allocate this very precious limited amount of time or really attention? Well, you have to decide. Well, I think this Randall syndrome model, the particular version that we consider, I think it's highly unlikely. in general the randalsunma idea is an interesting idea not this particular model but the one that was trying to explain the hierarchy model and should be explained should be explored has the nice feature that is simply relatively simple to explore relative to other particle physics scenarios and it's a it's slightly different scenario than the ones typically people consider like new parts the core structure, which is basically similar to the one we already had.

And so it's worth looking for, it produces weird signals. So it's interesting to look at it. And people looked at it, mainly in the run-up to the LHC as possible things that the LHC could see. Now, the LHC didn't see any of them, but it was important that it looked for all this, all the possible things. So there was an era before the experiment where I think it was, was important to look for exotic scenarios, look for, I don't know, possibilities like supersymmetry, look for various possibilities, and well, then you do experiment and you make sure you don't miss any

possible signal. So I think something that is important is some diversity in approaches, in various ideas. So I think if you ask me what science policy should be, should find different. various ideas, just in theory, various different ideas. You said just in theory or do you mean? No, no, in theory this is a very important principle in experiment. It's a little more tricky because sometimes you need a critical mass of people following definite, you know, definite experiment and, you know, there are many, many people studying Cosmicrowave physics, and I think it's a very interesting very interesting, very interesting.

very interesting topic and I feel yeah so now one of the frontiers is the study of the primordial fluctuations I find this the most interesting aspects of CMB I mean CMB physics has many more aspects as you know very well like measuring neutrino masses I don't know much that you mentioned and I don't know the physics of early clusters etc and but yeah this this this discovery of primordial fluctuations is very interesting for what it says about the universe, the consequences it has for us. I mean, we are here thanks to these primary fluctuations in a way. And so I think it's a conceptually very interesting area. I mean, very interesting result that people should know and I don't know. It's a fun for the

public to know. Again, you could say, well, this doesn't give any technological application and so on, but I think it's a fundamental scientific thing that is interesting for us to know. very important cultural value. And speaking of cultural value, there's other ideas, and, you know, there's an approach to let a thousand theories bloom, so to speak. So I'm getting questions about your impressions of alternates to inflation. Obviously, you've spent a lot of time thinking about inflation, but what if inflation didn't happen?

What if the models of your nearby neighbor over across the way and Jadwin Hall, Paul Steinhart, who's a friend of the show, the sort of cyclic bouncing models, or Roger Penrose, who's been also been on the show, discussing conformal cyclic cosmology. What are your thoughts on those models, alternatives to inflationary story? Well, I should say that I think it's interesting to try to find alternatives, to try to find alternatives to inflation. And we were discussing with some students and some alternatives. But I have to say that none of the alternatives reached the level of precision and rigor, just even theoretical rigor that inflation has.

So inflation is an idea where you take the simplest idea, it's Starobinski model, and you can do the calculation of fluctuations in that model, was done. And you get some prediction and, you know, the prediction doesn't change. It's not that a new theory is come and they change the prediction, and it depends on exactly how you do the calculation. There is a well-defined way to do the calculation, and that's it. In these other models, it's unclear what the roots are for doing the calculation. So the models have an uncalculable element, so some level of assumption in the model itself. So you say, well, you start with some well-defined process. There is a point where an unknown physics happens where you need a quantum theory of gravity, some theory we don't completely have.

And then you make some assumption and then you get some prediction. But the prediction changes with the assumption and maybe the assumption changed. And well, I mean, it doesn't mean that those models are all wrong. I mean, maybe there could be an idea, the conceptual idea might be correct. But they certainly not calculate. It doesn't have the level of calculation, even already internally, the calculation of rigor that inflation has. So as a theory, they are behind in that sense. And well, yeah, comparing to experiment, well, many of these models were designed to agree with experiment.

At least experiment so far. But yeah, some of them make different predictions. Right. Yeah, I guess the question is attention. You know, there's such a dominance in most departments have, you know, cosmologists, whether working on inflation if they have, you know, early universe cosmology. We have multiple people here at Sandy. We're very fortunate my colleagues.

Raphael Flaugger, Dan Green, and others. But thinking about alternatives and how difficult it is to get traction. Imagine you do come up with some theory and you are working more or less. I mean, the way I always put it is people like Eric Weinstein or people like Roger Penrose cannot get traction and not have graduate students and sort of people working on it. How easy is it or how does the kind of monopoly effect? Does it take place where a theory is so dominant? It's so attractive that it basically sucks out the oxygen from alternatives that may prove superior had they had the intellectual capital behind them.

Well, I mean, it is a problem if everyone does the same thing, but I think there is an incentive for people to come up with another theory that is a competitor. But it has to be a serious competitor in the sense that at least it has to be a serious competitor, at least it has to be. internally internally somewhat least calculable or and there are and there are people working on some alternatives it's not i mean there was a paper today about some other alternative theory so um i i think it's well i think people there are people proposing alternative scenarios but if the alternative scenario is very vague it doesn't get traction because you yeah you don't know what's the next step or what I mean it's good to have in mind and my my feeling is that perhaps someone working in some problems in you know quantum gravity or gravity

in general might have an idea for a slightly for a different scenario perhaps and then that would be reasonable and would lead to either different yeah well at least it has to agree with the predictions have been checked but experimentally I mean the scaling barrier, the nearly scale environment spectrum of fluctuations and so on. But yeah, it could lead to other predictions. I think it's interesting to come up with different theories. I mean, historically, for example, people, Branson, D.K. came up with this alternative theory of gravity where there is also scalar force and so on.

And that played the, I mean, that had the advantage of being a theoretically well-defined theory. And then you could use it to compare, you know, you know, experiments against the, you take GR and this other theory, general relativity and this other theory and you compare them and see what you get. So I feel, yeah. Yeah, I want to then turn towards a completely different direction, which is your paper entitled the symmetry and simplicity of the laws of physics and the Higgs boson where you used theories of economics as an analog to help people understand

an approach to how this very complex notion, so-called Higgs mechanism, could be understood in terms of a monetary or economic analogy. And that was building on, as you cite, the work of my friends P.M. Malali and Eric Weinstein in the sort of what they consider, and they've talked to me about this is sort of an upgrade of differential calculus. And I want to ask you, are there other applications of gauge-through? I mean, if you ask people, they might have heard of calculus, not the kind on my teeth or something, but they might have heard of calculus.

They might know what a derivative is or an integral, but almost none of them know what a gauge, you know, theory is. So, first of all, what is a gauge theory? Why is it useful to physicists? And are there other analogs that could be used to either understand gauge theory as you use economics based on, you know, Pia and Eric's work? but also to extend this to other fields where, you know, people like me might not see the connection between gauge theory and some other analog and physical world. Yeah, so gauge theory is basically a theory where you introduce some redundancies that help you understand, that help you describe the theory, but that they are not, do not reflect physics or they're not real. So you insert, you produce something which is kind of conventional and you, but at the end of the day, it doesn't reflect reality. And example is, well, the gauge potential of electromagnetism.

So both the electric potential or magnetic potentials that we discussed for electromagnetism. They are not physical. You can shift them by constants. You can shift them by some certain particular function. and what's really physical are the electric and magnetic fields. And electromagnetism is a gauge theory in this sense, and many of the theories of particle physics are also gauge theory, so it's a very important type of theory that we used to describe physics.

And yeah, so this economic analogy is based on thinking about, it's an analogy between economics and electromagnetism and it well should I describe it there yeah so maybe no please there yeah yeah so the basic idea is to think about the currency so people sometimes well so for example dollars right we measure things in dollars but if someone decided to change the value of the dollar say let's say people tomorrow they decide that, well, the $100 of today will be valid one new dollar of tomorrow, let's say. We could invent a different name, let's say, one peso, let's say. One peso, yes.

We'll call them one paces. We'll just change number of zeros and define a new unit of currency. But if all the salaries adjust appropriately and all the exchange rates with other currencies in the world adjust appropriately, that change doesn't affect anybody. And it's just a change in the units we used to. measure the value of things. And I come from a country in Argentina where this happened many times, so many times they took a few zeros out of the currency through this type of process.

Now that's an example of a gauge symmetry. That's something that doesn't change how rich you are because you change the number of zeros you're having the currency. Now there's some other more physical information in the more real information in the exchange rates between different countries. So, but not exactly exchange rates between two countries, because if you have the exchange rate only between two countries, if any one of them changes the currency, that the particular nominal value of the exchange rate will also change. So when you change the currency units. But if you have the exchange rates between three different countries,

and imagine them arranged in the vertex of a triangle, and so you have the exchange rates between any of the two countries along the edges of the triangle. Then each individual's exchange rate depends on the currency units of each one. But imagine you travel between the three countries in a circle. The net gain that you get by exchanging those exchange rates, that's independent of the currency units. So if you gain a factor of two or a factor of 1.1 when you go around in one way or you lose a factor, you know, you get a factor.

0.09 that is really physical and that's what in physics we call a magnetic field so it's analogous to a magnetic field now if you had a situation like this where you can make money by going around these three countries then you would have speculators that buy one currency sell it and so on and now normally this wouldn't happen if we were in equilibrium or but that you would think that the exchange rates would adjust themselves so that this doesn't happen. But imagine for a second that the exchange rates are arbitrary, and you could make money by doing this. Then you would have speculators that go around these three countries. Now, this is what happens in nature when you have an electron.

So an electron goes around the magnetic field. So you have magnetic field, the electron goes around in a circle. And so the electron is a bit like those speculators that are trying to make money. And yeah, so that's an example. And yeah, so you can have some fun with this example, and you can assume some behavior for the people who set the exchange rates and the speculators and so on and get the Maxwell equations, et cetera. I mean, this is not too surprising given that Maxwell himself

got the Maxwell equations from a mechanical model, and we think we don't have that particular mechanical model that Maxwell had. But there are many microscopic models that could give rise to Maxwell's equations. This is just one of them. Now, but in actual economics, we're in sort of like a Higgs phase of electromagnetist. It's analogous to a situation where the electromagnetism is spontaneously broken. And because the prices of ordinary goods that we can take between one country and the next is analogous to the Higgs field. So like we could have a certain quantity certain thing that gold or oil or you know bananas that we can take between different countries and

So the speculators could also commerce in this one of this and The prices of these quantities are well are certainly arbitrary they depend on the monetary units but we could We could set our monetary units in terms of those prices so we can some all the countries could say, well, we measure everything in terms of the price of bananas. Anyway, and that's, then the exchange rates between different countries would become more meaningful. And yeah, so, well, that's roughly the analogy. I could go on on it on this. And then are there other, you know, kind of approaches that where gauge theory might not be widely appreciated as a, you know, potential, a potential under, you know, way to understand

to understand something. Well, yeah, I don't know. So you were asking me to find the other analogies where I don't know of another one that is as close as economic one. Yeah, and then of course with the Higgs, you make a lecture week force, you talk about, you know,

spheres, replacing circles. I think that's delightful and an interesting extension of the work that we discussed. I want to talk just in the final few minutes if you if you still have a little bit more time we'll finish up soon a couple more questions from people in the in the chat room how how how how is it possible that by adding these dimensions seems a little reminiscent of you know kaluzza klein etc so what's the difference between a physical dimension which we have no evidence of existing and sort of a mathematical

dimension where we can add things at will even though they may not exist in in reality Well, a physical dimension is some dimension where some physics can happen. So, you know, a particle can move in the extra dimensions. Gravity can extend to the extra dimensions and so on. So that's what we normally call a physical dimension. I'm not sure what the mathematical dimension is. I mean, of course, the concept of many dimensions in math makes sense, and it could be applied to depends on what your mathematical dimension is.

application is so for example people who think about you know recognizing language artificial intelligence for language think of words as vectors in a high dimensional space and stuff like this so this is some other application of the idea of dimension that has nothing to do well engage just you know being analogous vocabulary lookup table between different cultures or languages yeah interesting a few more questions from from both me and my audience So one involves you're at this very, a little bit less technical now if you'll indulge us. So you're at one of the most storied institutions and the annals of all of science,

the Institute for Advanced Study. What is sort of your daily life like there? Is it all, you know, contemplation or what's a day in the life of besides your six hours of prayer, fasting every day as a monk? What's a day look like for you, Dr. Meldicen. Well, I think my day is similar to the days of university researchers. Normally, we come to our offices. We look at the papers that came out the previous night.

We discussed with our colleagues. We maybe are working on some papers. We do calculations. As a theorist, we spend a lot of time discussing calculations and math and different approaches to actually doing certain calculations. There is, of course, maybe some discussion of more conceptual things. But that's what we mostly spend our days on there. We go to talks, presentations, and the like.

And then in terms of, you know, kind of future things that you're interested in, what's sort of the near-term looking like for you in terms of research directions, maybe students and advisories? Yeah. So currently we're all. We're all mainly working on my group, working on aspects of black holes, quantum aspects of black holes, trying to understand what the black hole interior is, understanding better the information paradox.

There was recently very interesting progress on understanding how the information comes out in Hawking radiation in papers by Bennington, by various research groups. And yeah, so that's a very exciting development in the last couple of years. And so I've been working mostly on that. So the last question that I have, let me just scan the chat section here. We've got 100 plus people in the chat section. A lot of these have been asked. So I think we've covered most of the questions from the audience.

I'm going to finish up with two questions for you that I ask in some version or another. I ask most, if not all of my guests. And that first question kind of relates to the far future of humanity. You know, hopefully you live to be, you know, many. Well, first of all, I don't ask you. Actually, I don't get this opportunity very often. If I could give you, one of my kids is working on a pill, which he calls the never-dying pill, which would allow the ingester, whoever eats it, to live forever.

But no one else on the entire planet would live forever. I want to ask you, Juan, would you take such a pill to live forever as you are right now with everything you know? You can't take anyone with you, not even me. Yeah, I don't know, maybe. Yes, yeah, probably yes. Okay. And the next question revolves around something that in Hebrew is known as an ethical will. So Alfred Nobel left the famous will, which endowed a prize that bears his name.

But the will, in addition to recognizing discoveries and inventions, and physics, chemistry, et cetera, was meant also to benefit all mankind, so to have some benefit towards the human species. And so in that way, it was what was known as an ethical will. It had more than just a monetary, financial, tangible purpose and outcome of it. I want to ask you, if you were to write an ethical will, what kind of wisdom or things, knowledge that you've obtained in your life would you want to pass on separate completely from your, you know, financial material will. Well, the importance of collaboration, of truth-seeking in general.

I think these are important principles. And do you see yourself primarily as an educator, as a researcher, as a mentor, a student? How do you think of yourself? And what is your sort of superpowers that allow you to be so successful? Well, I think of myself as a researcher first. Yeah, also mentor. I have the, well, one of the secrets is that we have an outstanding young people coming through the institute that become our collaborators and so on.

And yeah, that's perhaps one of the greatest privileges of being here. Yeah, absolutely. Then I want to ask you, because I don't get to ask people of your stature and prominence so often, what's your theory or what's your, if you had to predict, what's more likely, so to speak, that the multiverse exists or that God exists? I think that God exists is more likely. Very good. Care to elaborate?

Are you, do you practice any religion out of curiosity? Yeah, yeah, I am sort of Catholic, but yeah, I think some general idea of God, I like the idea of superior intelligence and stuff. on. But yeah. But I think the multiverse is likely. The multiverse, I think it's, yeah, it's also likely. Maybe both are, maybe both are true. It's difficult to see how to prove it. Yeah, it's also difficult to see how to prove the existence of God. Yeah. I asked Freeman Dyson that same question, more or less when I was writing my book, and he said, well, both are kind of great puzzles. You know, puzzles can be solved or maybe mysteries, he said, is the right word, because the mystery might not

be solvable. A puzzle could be solved. I might not be able to solve a Rubik's Cube, although I was joking today. I solved five sides of a Rubik's cube, and I'm having trouble with that sixth side. But in reality, I was wondering, the last question kind of maybe relates to that as well, or actually the second to last question, if you have a few more seconds. The second to last question is a life on other planets and intelligent life in particular, do you think that's a worthy, you know, quest given finite resources? What do you think the likelihood is of extraterrestrial intelligence that we could communicate with potentially? Well, I think this is also one of the great questions that I think we should devote some resources to answering. And yeah,

I think the likelihood, it's, well, it's hard to tell. Of course, the Fermi paradox, I guess you'll know. And, yeah, so that makes me think it's unlikely. But, yeah. Interesting. Okay, the last question is. The anthropic principle, then it's very unlikely. Right.

That's right. And fine-tuning. I think. Yeah. So the last question that I have is usually, I don't know if you've ever seen the movie 2001, a space odyssey. Yeah. But there are these monoliths that play a role in the movie as a plot device.

These are left by an ancient civilization to be found when humanity is ready technologically to appreciate them. And I want to ask you, Richard Feynman once said the following. He said, if there was a cataclysm that destroyed all scientific knowledge, and you could only pass on one sentence to the next generation of creatures, what statement would contain the most information in the fewest words? Now, I'm not going to ask you for one sentence. He said the simplest one was about atoms and how everything is made up of atoms. But now we know so much more than what he knew in the 60s or 70s when he made that statement.

I want to ask you, what would you put on a monolith, a time capsule that would represent the culmination of physics knowledge or personal knowledge that would last for a billion years as a time capsule for the future? Yeah, I think this idea that matter is made out of particles is very important. Probably that perhaps general relativity. Depends on how much you can put in. Right, yeah. The sentence could be a run-on sentence. It's made out of small particles.

That's something that fits in a sentence. Very good. Well, Dr. Juan Maldesina, it's been a pleasure to talk to you. I hope to maybe contact you again in the future as I develop a little more understanding of your excellent papers, very provocative, very entertaining papers, as is your style. And I appreciate this very much. I'll put some resources in the show note, links to your papers, links to a talk you gave at the Institute several years back on the same topic. I want to express my gratitude to you, Juan, for sharing so much of your time with my audience today.

Sure, and it's a pleasure. Yeah, thanks. Thank you, one. Be well. I'll talk to you again soon. Thank you very much. Any sufficiently advanced technology is indistinguishable from Magic. If you enjoyed this episode of Into the Impossible, please subscribe, comment, share, rate, and review. For a chance to win a free copy of our most recent guest's newest book,

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