Brian Greene: Does the MULTIVERSE
Actually Exist?

Brian Keating:

He’s known literally throughout the universe for his groundbreaking discoveries in the field of string theory. He co invented mirror symmetry, and he brought the notion of Calabi Yau manifolds to the mainstream. Meet the one and only Brian Greene. Brian’s a Professor of physics and math at Columbia University and the author of numerous best selling books. Join us on this It’s in person conversation held late at night at Columbia University as we uncover the hidden reality of our universe and delve into parallel universes and the deep mysteries of the fabric of reality. Let’s go. Here we are today with a man That needs no introduction. Fellow Brian.

Brian Keating:

Oh, my my mom at least claims she named me Brian, so people are confused with brain. I don’t know about you. But Yeah.

Speaker:

I haven’t heard that one directly, but,

Brian Keating:

Now they, we have the 2 of the 3 Brian’s. Of course, I’m I’m the least well known of them, but Brian Cox is, of course, the The ultimate also, another Brian who gets a lot of attention. Maybe he’ll come on someday, but so far, he’s ignored my messages unlike you, and, I wanna Express my gratitude. Last time I was in these luxurious offices here at Columbia University, I was beseeching you for an encomium On my book, Losing the Nobel Prize

Speaker:

Oh, I remember that. Yeah.

Brian Keating:

Which you graciously provided back in, 2016, and the book came out in 2018. So I wanna I appreciate you and, express gratitude for for all that you’ve done for me personally and for the field of astronomy and cosmology and science communication. Thank you very much, Brian, for joining us. Thank you. One of my most requested, if not the most requested guest, and I have a ton of stuff to talk about today. We’ll run out of, I’ll run out of, energy And adrenal system excretions before we run out of questions, I’m sure, but we’ll see how far we get. The first thing I wanna do is I since I’ll introduce you later, But I wanna ask, what is in your estimation? I call this the experimental minimum. I’ve had on Lenny Susskind before, and he’s written books, The Theoretical Minimum.

Brian Keating:

I I wanna ask you, what should a theoretical physicist, cosmologist, what should she or he know about experimental physics and why?

Speaker:

Well, look, none of what we develop theoretically has any real value if it doesn’t make contact ultimately with Experiment. And so my quick answer would be know as much experiment as you possibly can. Right? Because That is the way in which you can make contact between abstract mathematics and the actual physical world. But the reality, of course, is There’s a limited amount of time that any graduate student, any undergraduate, any faculty member has. And so you need to know the basics for cosmology, Micoid background radiation, evidence for expansion of the universe, evidence for the accelerated Expansion of the universe. You should know something about black holes. You should know the Observational evidence from motions of stars in the Milky Way galaxy to the Event Horizon Telescope’s actual images of black holes. If you don’t know about that Stuff people will look at you kinda weird.

Speaker:

And, you know, I think it’s also really good to know the basics of particle physics.

Brian Keating:

Right?

Speaker:

I mean, you should know the standard model of particle physics. You should understand the experiments that give rise to The gauge symmetry of the standard model, and you should understand that in 2012, we confirmed the Higgs particle. You should know that supersymmetry has not yet been confirmed. That’s an important experimental null result. And beyond that, you should understand That there is this mismatch between our calculations of Dark energy, which really comes from understanding the quantum physics of elementary particles and the observational evidence for dark energy. That I would call perhaps the minimum. No doubt there are other things that should be included, but that’s a good start.

Brian Keating:

Yeah. And this building have been renowned, and this campus have been renowned, purveyors of both theory and experiment. I’m thinking about Rabi and and, of course, CS Wu, and and, of course, you know, all the many great experimentalists and and theoreticians who have come through this building, and I see it as a as sort of and I believe Arnold Penzias was a student here. Wasn’t he?

Speaker:

I didn’t know that.

Brian Keating:

I think I think

Speaker:

he was. I’m not

Brian Keating:

I’m not sure. We’ll have the fact checks here.

Speaker:

But the students. Yeah. That could well be because that yeah. That would have been a long time ago. Yeah. Sure.

Brian Keating:

Many of them came through here. And I I think about kind of what do I want my graduate students to know as experimentalists? Yeah. For me, I say you shouldn’t have to do theory, But you should know a theory as well as an incoming graduate student. Otherwise and no offense to plumbers out there, Lenny Selskin, as you know, was a plumber. But you’re kinda just doing plumbing and microwave And then it’s very important and interesting stuff. But you’re a technician, and you can get paid a lot more in, you know, free industry. Actually, I was talking to Jim Simons recently, As the benefactor, of course, of the Simons, Observatory, and I believe he supports the w World Science

Speaker:

of the World. Yeah.

Brian Keating:

He and Marilyn are huge champions of all the great work you and Tracy do. But, but he was saying, you know, once he had to call a plumber in the middle of the night, and the plumber came over and, fixed up the thing and the same good stuff. And by this time, Jim was in his hedge fund career, and the plumber said, that’ll be $700, please. And Jim is like, oh, I’m one of the richest guys in the world, but this is ridiculous. $700, you know, I’m a hedge fund manager. You know? You make $700 for 15 minutes. And he goes, oh, you’re a hedge fund manager. Yeah.

Brian Keating:

That’s That’s about what I used to make when I was a hedge fund. Right. But when you think about, you know, technicians and and stuff like you should understand the why, I believe, of what you’re doing. And so want them to understand the theory, but not necessarily to do it. And it’s always kind of been curious to me because when we let a theorist on those occasions come into my lab, we had Katie freeze over, just about a week or 2 ago. And we don’t let them into the lab because they’re always you know, they’re gonna touch something, fiddle with something. But in reality, I think there is sort of a mismatch between What theoreticians do. And then I wonder if you could get into that.

Brian Keating:

What do you do as a theorist? It’s not like saying, you know Yeah. Think for your supper, but What does a theorist spend his or her day doing? And I realized, you know, every each theory is different, and I’ll get a different answer when I talk to Jana. But tell me, what, Brian, what do you do as as your craft, Yeah.

Speaker:

Well, it’s an interesting way of framing what you do day to day because the day to day changes drastically regarding depending on what project you happen to be involved in. But I would say the general rhythm is you read papers that others have written in order to get a feel for the state of the art in whatever Ever problem you’re interested in, and more often than not, when you read somebody else’s paper and you See things from a different perspective, it inspires all sorts of new ideas that you, The individual theorist can begin to pursue. And what does that mean? You begin to say, hey. They did this calculation. What if we were to change this, that, or the other and redo the calculation. What would that yield? Or, hey. They did this calculation in this context, But wait a second. I remember this other problem from a couple years ago, and I think that if I take that calculational method And adapted to that other problem, there may be something interesting to do.

Speaker:

And so it’s a variety Of incremental steps that are often seeded by the community. It’s usually not the Albert Einstein off at the Patent office coming up with this radically new idea.

Brian Keating:

I get emails all the time when I’m at

Speaker:

the science. We do. Yes. And and and, you know, Einstein did a lot of great things for science, but working in the patent office, at least from the perspective of modern day physicists, Was a real disservice, and I mean that in the following way that you already understand, which is so many people think you don’t need to be within the community. You can be off in left field just having big thoughts and you’ll change the world. On occasion, that happens. It certainly happened once And, you know, a handful of other times. But for most of us, we’re embedded in a community, and there’s an ongoing conversation.

Speaker:

Sometimes it’s a real conversation. Sometimes it’s To reading other people’s papers. And so day to day, that’s what we do. We are pursuing mathematical developments and trying to See what insight we can extract from them.

Brian Keating:

Hey, friends. I’ll keep this pretty short, but I’ve been doing some data analytics on previous episodes that are related to the topic of string theory, including one with my friend and Brian’s friend, Kumran Vafa. And when he was on last time, You can see at the bottom there, it says the watch time from subscribers versus unsubscribers means that more than half of you aren’t subscribed to the channel, and yet you’re enjoying the videos. And that’s just not right. No. I’m just kidding. I would really love it, though, if you would consider subscribing because it really helps me get some of the guests that we’re getting on, and we’re poised to get some phenomenal guests. But when their agents or their publishers look At podcasts, they have to say, well, is this worth me sending my beloved author or thinker to appear on? And a lot of times, they do that, unfortunately, just based on sheer number of subscribers.

Brian Keating:

So I wonder if you could do me a favor. It would really help a lot If you would subscribe. And I promise in doing so, you’ll help me help you, bring the best guest to this podcast that we can possibly get and onward into, 2024 and beyond. So I really appreciate your help in helping us grow the podcast. Now to the conversation with Brian Greene. So you’re no doubt familiar with the fact that string theory has come under attack, And and you’ve been actually gracious and kind enough to participate in debates with past guests on the podcast, like Eric Weinstein and and, of course, you know, Peter White and And many others that have alternative theories alternatives to string theory. And you did your thesis, I believe, in 1986 on string theory, which is, you know, kind of the salad days. And I Wanna ask you, if you had to appraise, appraise string theory, I asked Mike Turner about inflation and dark energy recently, gave him the same thing.

Brian Keating:

Give string theory, a grade, a report card, and break it down into the subcategories of string theory. Where is it exceeded? Where does it need more work? And where is the teacher Conference is gonna happen.

Speaker:

The only reason I’m laughing is because the 25th and this is not a plug, folks. So it doesn’t matter, but it’s just because you asked a question. The 25th anniversary edition of the Elgin universe coming out in August. And on the final pages of this new chapter I’ve written, I give string theory a report card. So part of me is like, hey. I don’t really wanna spill beef right here, but I thought I’ll give you a rough feel for it. So it’s a good way of phrasing it because You need to judge a theory among many different criteria. Right? And and some string theory has done extremely well, and some it hasn’t done is 1.

Speaker:

So let me start with the stuff where it hasn’t done as well. Mhmm. When it comes to making contact with experimental data, the very question that we began with, String theory is not as far along as I would have hoped. Right? So back in 1986, I don’t wanna calculate how many years ago that was. It was a long time ago. And if you would have asked me then, and I think most string theorists at the time, 2023, Are we gonna know through experiment or observation whether these ideas are correct? 95% of the community would have said, of course, we’ll know by then. And yet here we are, and and we don’t know. So on that, I would give a relatively low grade, but I’m gonna come back to How? I’ll give the final grade on that in just a second because the theoretical developments in string theory have been so Astonishingly powerful, well beyond anything that I would have anticipated back in 1986.

Speaker:

And one development in particular that No doubt you know something about because it’s the most famous development in the last 20 years, this ADSCFT correspondence By Juan Maldacena. And, actually, again, it’s a whole great. It’s a whole community of people, of course, but Juan wrote the paper that really took the world by storm. The relevance of that well, it’s got a huge degree of relevance, but the relevance to the experimental question is interesting because Once we learned, as we did with Juan’s insight, that string theory is not as a radical separation from previous biology as we once thought, which is a great development. There’s a deep connection to older techniques that are Still at the forefront because there are most powerful techniques, quantum field theory. Once you learn that quantum field theory and string theory are Joined at the hip, which is what Juan showed us, quantum field theory is the most Powerfully tested theory in the history of of particle physics, in the history of quantum mechanics. It’s a framework that works. Tested in in what sense? Tested in terms of internal consistency, philosophical expediency.

Speaker:

In what ways have been I’m talking flat footed here. Take the Standard model of particle physics. It’s a particular quantum field theory, and that particular quantum field theory makes predictions that we can confirm. I mean, the, You know, take the magnetic moment of the electron. Right? Decimal place. Yeah. That’s is is that not the most insane

Brian Keating:

I think it’s about the most accurate thing. No number.

Speaker:

Yeah. So so So think about the fact that you can do a calculation using this framework of quantum field theory. It agrees to observation to that many decimal places. Right? So So that’s the sense in which these ideas have been rigorously tested. When you learn that that framework is Intimately connected to the framework of string theory that they’re not these 2 radically different things, which is what we initially thought. It doesn’t prove string theory, of course, but it shows you that we are within the same universe of ideas all of a sudden. And that to me mitigates to some extent that string theory has not gone as far as we had hoped to actually make An experimental prediction that we can confirm, but the fact that it has joined together with the most experimentally tested approach, That is good. That’s strong.

Brian Keating:

So one one of my, you know, favorite canards is that I feel like you, and I’m gonna say this, you know, some my best friends are theorists. You know, I don’t know if I’d let my daughter marry a theory. But anyway, the the the point of, you know, string theory and all of experimental on all of science within this context scientific method is to make some connection with reality and then as you call it the fabric of reality so beautifully and poetically. But I feel like some of your ilk Yeah. Have, And including I when I talked to Shelley Glashow on the podcast a couple years ago, I said this to him as well. I feel like many of your colleagues, not you necessarily, Have put what I call the toe before the gut. In other words, we are searching for a theory of everything, and then string theory is a candidate theory of everything. I believe that’s that’s safe to say.

Brian Keating:

And yet and yet necessarily have a brand unified theory that people agree with. I mean, Shelley had his s e five and Yeah. Many different instantiations of it. But to my knowledge, and I’m just a humble experimentalist. But but tell me, why is there kinda why do we skip?

Speaker:

Yeah.

Brian Keating:

You know? But Why aren’t there as many people pursuing in the sociology of science, pursuing GUTs, grand unified theories, which would maybe can explain the difference between a theory of everything in a gut. But why are so many people over indexing on toes versus guts?

Speaker:

Yeah. So first of all, I don’t use that language much. I mean, sort of grand unification, certainly. But TOE theory of everything is a term that I tend not to use very much, really for sociological reasons that if you’re working on the theory of everything, then what is somebody Who’s not working on it, doing with their time, theory of nothing, you know, you know. So so I’ve never really warmed to that idea, but, of course, that’s not the point of your question. The question is, Where should we be putting our energy? And the way I would say it is this, if Shelley’s s u five Or if the other grand unified theories like s o ten, for the people who are not no. No. These are just names of certain symmetry principles that Equations can satisfy, and we’ve learned that symmetry is vital to formulating the laws of physics.

Speaker:

And as we went further along in physics, we invoked Ever more robust symmetries, and those are two examples of them. How those theories born fruit? That is had their predictions been directly confirmed, which could have happened. Right? Because George I, Glashow, in their approach, it predicted their grand unification theory predicted that the proton should decay. And as we all know, We searched for that to get no sign yet. So

Brian Keating:

waiting. Yeah.

Speaker:

So that that so that was certainly, I think, sociologically why people didn’t just Put all their energy into going in that particular direction. But I think that the the deeper answer is that we’ve come to realize That to go further in physics, you’ve got to understand how gravity and quantum mechanics coexist. And all of the work on grand unification ignored the force of gravity. That was not the way that people were pursuing the next Step in our understanding of physics. And so to leave out gravity is to leave out an essential part of the story. And when string theory came along and provided a means for putting gravity and quantum mechanics together, that was Deeply alluring to so many people because now all of a sudden, you weren’t leaving anything out. So it could be the biggest unification of all. And moreover, when we began study string theory, we began to see the more conventional grand unified theories like George I and Glashow’s s u five and like s o ten.

Speaker:

We began to see those emerging from the unification of gravity and quantum mechanics.

Brian Keating:

Mhmm.

Speaker:

And so it felt as though we can Have our cake and eat it too. Right? We can put gravity into the story, and we can unify everything. Mhmm.

Brian Keating:

Well, let me just Push back with love and respect is, is my hope is my trademark. But say, imagine a counterfactual history where Shelley and Weinberg And Abdus are working, and they say, well, we’re not gonna look at, electroweak unification until we can incorporate gravity And the strong force into it. Wouldn’t we have been a stymied in flamox for an additional who knows how? He could still be looking for electroweak investigation.

Speaker:

Two quick answers to that. One is Absolutely. Right? So I would never advocate that every single theorist goes along And tries to get the big prize of putting gravity and quantum mechanics together. So so, certainly, I I would say that you do need people who are More phenomenologically oriented trying to come up with theories that are closer to data. And that’s, Of course, what Glashow, Salam, and Weinberg were doing, that was a time when the particle physics data Was right there. It was right ready to talk about how do you put electromagnetism and the weak nuclear force together. Because after all, It was, what, you know, 1979, I think is when they get their Nobel Prize, but the paper itself was in the early seventies. Well, late is glacial Glacial.

Speaker:

And and then early seventies. So it was only 7 years away or it’s only 8 years away. So the Theory in the the experiment were pretty close, temporally speaking. So so that’s wonderful. You need people who are having this Ongoing dialogue with phenomenology, and and that’s that is what was happening. Today, we are, as people often say, the victims of our own success. The open questions are at length scales that are so tiny, energy scales that are so huge that we simply don’t have an accelerator That within 7 years is gonna probe the scales where the open questions currently lie. And that’s why we’ve gone So far beyond what experimenters can do, and that’s why here we are 40 years later with string theory, and I don’t have any experiment to show for it.

Brian Keating:

Well, I wonder how you react to a statement made by our mutual friend, Kamran Bafa, when he was on the podcast a couple years ago. I said the same thing, which is a canar that We experimentalists used to tease you brilliant theorists. We said, no. String theory hasn’t made any testable predictions or connection to it. He said, Brian, you’re wrong, and he’s such a gentleman as you know. He said, Brian, you’re wrong. String theory predicts the mass of the election. I said, holy cow.

Brian Keating:

Tell me more. And he goes, within string theory, it’s possible to come out with The calculation that shows the mass of the electron should be between something like 10 to the minus 1 Planck masses to 10 to the minus 30 Planck masses. Okay. So it’s 30 orders. He said, I know that’s not good. And it’s like me saying to you, you weigh less than, you know, 10 to this, 26 kilograms, which I think is accurate, but not precise.

Speaker:

Yeah.

Brian Keating:

And so when you when you hear things like that, as an experimentalist, I feel like it’s hopeless. And I would only think that, well, To what extent should we continue to over index or index on, young Brianna Green, you know, going into Akita going into this Field where, where sociologically we can ignore, but but just in terms of intellectual satisfaction of having something complete Yeah. And and and and visceral that you could accomplish in 6 to 7 years.

Speaker:

Yeah. I think that’s all all good questions. And let me just jump off from what Krumrin

Brian Keating:

said.

Speaker:

I mean, Krumrin’s, you know, A a dear friend and one of the most brilliant people. So and I know exactly where he was coming from on that particular answer, but I can well on well imagine how it doesn’t feel satisfying as you had hoped when he initially said it.

Brian Keating:

That’s right.

Speaker:

So so let me give another unsatisfying answer that that one can give to. I’m sure you, of course, heard it before. String theory does make a prediction. It predicts the existence of gravity. Now before anybody rolls their eyes, there’s something really, really deep Here, which is the following. You, a moment ago, said imagine an alternative counterfactual history where, Yeah. Salom and Weinberg and and and Glascia hadn’t done their work, you know, what would have happened? Imagine another counterfactual, another Possible universe where there wasn’t an Albert Einstein who came up with the general theory of relativity. Okay? But imagine instead that we found string theory.

Brian Keating:

Mhmm.

Speaker:

By working on string theory, which does not have gravity manifestly in its equations from the get go, string theory truly is A theory that describes the motion of vibrating filaments. There’s no gravity in there per se. Right? But if you study String theory, the mathematics of it, you find that there’s a vibrational pattern of a string, which has exactly the right properties To be the quantum mechanical conveyor of the gravitational force, which means when you study the motion and Properties of this particular vibrating string, you study it close enough and you find Einstein’s equations. You find Einstein’s equations. Einstein had to spend 10 years from first principles banging his head against a blackboard to try to learn Differential geometry and to come up with the Riemann, the you know, and all of this deep differential geometry, and he comes up with the Einstein equations. Had he not done that, we wouldn’t have had it. But had string theory come along and people studied it, they would have extracted what we now call the Einstein equations from the theory. So that’s pretty darn deep Mhmm.

Speaker:

Right there. And that yeah.

Brian Keating:

Go ahead. I was gonna say, is is that in a similar vein that you could derive Newton’s equations or even classical mechanics from quantum mechanics? Is it then or is it completely different?

Speaker:

I I I It depends. So so if you’re talking about how you can get sort of something akin to f equals m a from Schrodinger’s equation.

Brian Keating:

Einstein’s theory of universal gravitation.

Speaker:

Yeah. So I don’t know how to get that from Quantum mechanics. I do know how to get f equals m a from quantum mechanics.

Brian Keating:

I think it was I’m sorry. Yeah. I was maybe complaining 2 different things. I was asking the first time analogy I asked was, Can you get it in the same way that you’re saying you can derive Yeah. Einstein’s g r from string theory? Can you also is it in the same vein technically, mathematically as the way that we can derive Newton’s law of gravitation from I from g r.

Speaker:

In other words Oh. Oh.

Brian Keating:

Would you predict this can you also say Yeah. Is it predicted in the same sense that g r predicts Newton.

Speaker:

So so in in a sense, yes. Right? But the difference is In the string theory context, you are unifying Einstein with Quantum mechanics, something Einstein had never done.

Brian Keating:

Because it’s oh, I should say it’s a classical theory emerging from quantum.

Speaker:

Yeah. And then you’re pulling out from that The classical gravitational equations that Einstein wrote down. And so many of us find that to be you know, is it really A prediction in the conventional sense of go out and look for this. No. It’s a postdiction. We certainly knew about gravity and Einstein’s equations beforehand. But, you know, Had let me ask you let me ask you this question. Had we had no Einstein and had we had string theory And some string theorists pulled out of string theory, Einstein’s equation, and made a prediction for the bending of starlight.

Speaker:

And then we went out and measured during a solar eclipse, The bending of starlight and it was confirmed, wouldn’t you feel, oh my god, string theory.

Brian Keating:

It is the

Speaker:

I should. Right. Right? Wouldn’t that be where you go?

Brian Keating:

So in this other history Yeah. In the counterfactual the the green counterfactual history, I would be forced to at least grapple with it. I think the ultimate base level of fabric of reality to use your poetic language, It would be a less satisfying, less nourishing intellectually than, say, discovering these in extra dimensions in, say, a particle. Yeah. Because you could also maybe extrapolate the other way. Could you get quantum field theory from from string theory? If if it counterfactually, you know, Schwinger wasn’t in this building And and didn’t come up with Feynman into manga. And he didn’t come up with QED. Could you get that emerging from string? I assume the answer is yes.

Brian Keating:

Hey, everyone. We’re talking about Space and time in this episode with my good friend, Brian. Thanksgiving season is upon us. And as you can tell, I’m very thankful Well, my kids’ favorite, Brian, appeared on Into the Impossible. For many, Thanksgiving means good old American traditions like family turkey dinners, football, arguing with your loved ones, and, of course, Black Friday discounts, my favorite day on the calendar. And if you Spend a lot of time in your computer like I do, you need to check out the Black Friday deals that AppSumo has on software tools. All the deals are available right now until December 1st. This deal covers all sorts of software courses and more, and the discounts are huge.

Brian Keating:

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Brian Keating:

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Brian Keating:

So once again, For all of you listening and watching out there, check out AppSumo’s Black Friday offers at AppSumo .com. The sale is running till the end of November. So go to AppSumo .com, and make sure you take advantage of these amazing deals. Now back to the episode. Then you’d have to ask, well, what are the what are the, you know, Classical emanations from which that we could test with particle accelerators or cosmological accelerators, which I wanna get into, the universe as as a laboratory. So, yeah, that that is certainly I think you asked, well, what is the difference between, you know, counterfactual and a or let me say this, A retrodiction or a post prediction and a prediction. I kinda don’t believe that the job of the science is just to make new predictions because there’s an infinite number of things that could be Possible. And there’s a very, very small, you know, set of things that are possible and are testable.

Brian Keating:

Yeah. So, you know, Einstein’s, perihelion of Mercury anomalous precession of the of The absence of of perihelion, that is a retrodiction, but it was very powerful. And then from that, yes, there were new things that came along. I think it would be, mean, the coolest thing and I’m gonna ask you, you know, for other speculations when it comes to things like string theory or the multiverse, which are both domains that you’ve trafficked in very successfully. But, when we think about what is it that the goal should be, can it be to make a connection, to make something that I, my experimentalist, my colleagues test in a laboratory or not. That’s technologically dependent. That’s their situation dependent. We wouldn’t have been able to discover.

Brian Keating:

And I I love to read, like, the the original. You like you talked about Einstein in the patent office. If you read, like, Maxwell’s original treatise on electromagnetism

Speaker:

Hard to read.

Brian Keating:

It’s hard to read, and then the fluxions Yeah. And he was, like, inventing new new terminology. But, ultimately, he got the right answer because he came up with these 4 equations that are, you know, Tattooed on many people’s, you know, foreheads in the in the space. But if you look at the underlying physics, the model for it, it’s a bunch Claptrap, weirdo, a cold stuff with wheels and gears and and electromagnetic virtues.

Speaker:

Yeah.

Brian Keating:

I always joke, like, what if he was on Twitter? What if Twitter existed in 18/65? And he’s like, I got this great theory, and it involves these whirlpools and eddies, but, like, people said, you’re an idiot. Like, there’s no whirlpools and eddies. We already know that. But but then to look back, you would have thrown the baby out with the bathwater, the electromagnetic virtue because you could have rejected a correct theory. And I worry that we’re doing that with string theory, or I’m worried that in some sense, the nutrients in the earth, there’s only so much nutrition. So are we neglecting other models? And I guess I wanna ask you. I’ve asked this of other people. Yeah.

Brian Keating:

Steven Wolfram, Eric Weinstein, Garrett Lisi. Whenever I ask them, what do you think not about String theory, because I know I’m gonna get an earful about string theory from all these, gentlemen. But what do you think about, competitor b? You know? What What does Eric Weinstein think about Garrett Lisi, or what does Garrett Lisi think about Peter White or or Steven Wolfer? And I’ll say, I don’t have time. And I’m like, Come on, guys. You know, I I’ve got little kids. I’ve got teaching responsibility. I’ve got an experiment in Chile. I’m not nearly capable to comprehend the mathematics.

Brian Keating:

But at some level, You don’t have time? I mean, string theory, your thesis, I’m not gonna date you, but it’s over over 30 years ago. Right? Yeah. Do people really not have Time in the theoretical community to actually purview, or is it like you only have so much time, so I’m not gonna develop unless I could do it to every

Speaker:

Well, I guess what I would say is when any of these Newer ideas have come online. There’s usually been some string theorist

Brian Keating:

Mhmm. Who

Speaker:

has spent some time on it. And if it’s someone who I respect, Then, you know, my motivation to then redo the analysis and try to confirm what my colleague Has concluded I I feel less motivated to do it. So I’ll give you an example. Mhmm. You know, I believe it was with Garrett Lisi’s thing that Jacques Distler.

Brian Keating:

Mhmm.

Speaker:

Do you know him from University of Texas Austin?

Brian Keating:

But I don’t know.

Speaker:

Yeah. So Jacques is a brilliant theorist. He and I did we used to work Very closely together way a long time ago back in the eighties. We’re still, you know, good friends. Every time we go down there, we hang out. And he wrote A variety of things on on Garrett’s ideas, and I perused those. And I trust Jacques, he’s one of those people. I mean, it’s not like you go and redo every experiment.

Speaker:

Everybody does. You know? So I trust him. He’s a thoughtful whole person and the conclusion that he reached was there’s nothing here. And when I read something like that, I’m like, okay. You know, I don’t feel the motivation. When it comes to Stephen Wolfram, I do feel differently. I do want to put some effort in to understanding exactly what he is saying. Again, I I know him reasonably well.

Speaker:

We’re we’re, you know, not best buds, but we’re friends. And, he’s encouraged me a few times to, And he sends me articles, and I am starting, for instance, to do that now. He and I are gonna do a conversation at some point in the not too distant future. So I will be educating myself on that one. You know, in terms of the others, loop quantum gravity, I did maybe 15, 20 years ago. I put a little bit of time in so I would understand The basic framework that they were developing, and, I found it interesting. It’s not in any way crack pot, But I didn’t find it sufficiently compelling.

Brian Keating:

Mhmm.

Speaker:

And I also didn’t like the fact that unlike string theory, It didn’t naturally incorporate everything, all forces. You know, again, staying away from theory of everything, there is an appeal, nevertheless, in string theory That it’s got the capacity to to embrace everything. So so on those, that’s sort of where I stand. Do I leave somebody out of the, discussion?

Brian Keating:

Stop there. Your you guys have debated, and, you had a memorable exchange at the IAA conference where he said something, and you said, well, maybe we were over at Zuber. And he said, like, the My Lai massacre. As only Eric Weinstein could do. So his geometric unity theory, which features some testable predictions. Again, I’m an experimenter. Right? So I’m looking for, well, what things could we do say how would the prediction of Garrett’s theory or Steven’s theory or Ava Silverstein? You know, any idea. How will that affect observables that say the Simons Observatory can measure? One of the things we can do is measure abundances.

Brian Keating:

We can measure look for spin dependent, phenomena and Those theories and I think the thing that Eric always harps on is that we don’t we seem now I say we, collectively as physicists, and I’m including myself, even though I’m not a theorist. But, in in the things that seem to not trouble us troubles Eric. In other words, why is it that we have 3 flip families of fermions And we don’t have an explanation. Yeah. We just we just sort of know it as a taxonomy. And as Feynman said, just because, you know, name of something tells you bug gets about it. Right? Does that trouble you? I mean, is that part of Hey.

Speaker:

If you go back Yeah. You mentioned my thesis, which I haven’t thought about in a very long time. But, Now the point of that thesis was to try to answer why there are 3 generations from a string theoretic perspective. And way back then, there were only a handful of known shapes for the extra dimensions that string theory requires. And in string theory, the number of generations of Particles is related to a geometrical quantity in the extra dimensions, half the Euler characteristics for those who are keeping score at home. And so if you have 3 generations, you’re looking for Euler characteristic 6.

Brian Keating:

Okay.

Speaker:

And there were only really 3 known examples That had been constructed around those times. And with a colleague, another graduate student at Oxford, we proved that 2 of them are actually the same. Ah, so unified So we unified them. So we’re sort of down, you know, by 1. Mhmm. And, I may be aggrandizing, but I think we also pulled in the 3rd one. So I think we basically got it down to 1 if I’m if I’m maybe being generous with myself 40 years later, but it was it was 1 or 2. I believe it was 1.

Speaker:

And so what we did was we then went further and tried to calculate the mass of the electron or the mass of the other particles From this particular geometrical form of the extra dimensions. And at that time, with the limited mathematical understanding, which has since become much more deep, we got Partway down that road, but as we did, more and more shapes for the extra dimensions were discovered. So all of a sudden, this motivation to This study 1, well, if there are only 4 or 5 total and only 1 with 3 generations, of course, you’re gonna study it. But then when they’re 500 or 10,000 Or 10 to the 500, your motivation for studying any specific example drops precipitously. So that is the historical way, but, yes, does it Does it intrigue me, this question of why there are 3 generations? Absolutely.

Brian Keating:

When I interviewed Nick Bostrom, you know,

Speaker:

he’s Bostrom, so

Brian Keating:

I asked him I said to him, he’s from Sweden. I said, look, Nick. You know, you’re from you’re from Sweden. And if I had on, you know, ABBA, if I had them on Into the Impossible podcast, And I did not ask them to play dancing cool. It would be there’s both which you and I have sworn to. I have to ask you, Calabi Yau manifolds, because I’m here with at least, you know, the the foremost, For, you know, proprietor of of all things Calabia. What is a Calabia? What is a manifold? How does it have to do with The fabric of reality Sure. Could you could you enjoin us with this, with this no doubt delightful explanation from the godfather of the

Speaker:

Well, yeah. I mean, very briefly. So I think as many people know, when we study the equations of string theory, even as far back as, you know, the the 19 seventies, it And very clear that the theory required more than 3 spatial dimensions that we all see in the world around us. Indeed, we needed Six additional spatial dimensions that we don’t see. How do we explain them? This goes way back to Kaluza and Klein in the early part of 20th century. Just imagine that the extra dimensions are here, but they’re crumpled to a size that’s so small that we can’t detect with the naked eye and perhaps even with our most Powerful magnifying equipment even with accelerators, perhaps. It’s just too small. Good.

Speaker:

So that’s why the dimensions would be tiny. But then you say to yourself, Can you curl them up in any which way, or are there mathematical restrictions on the geometrical shape Of the extra dimensions. And indeed, there are these restrictions. And the particular kind of restriction that people began to study in the 19 eighties was to demand that the theory preserve this thing called supersymmetry, which we made reference to very briefly Before not finding it at the Large Hadron Collider, but in any event, the goal was to preserve this symmetric quality of the equations. And when you impose that, you find that the extra dimensions have to be curled up into this so called Calabi Yau shape or Calabi on manifold. A manifold is really just a geometrical Shape. There’s some technical details, but that’s the basic idea. And so what is a calabial shape or manifold? Well, it’s a it’s a manifold that Preserves or perhaps I should say it in the following way.

Speaker:

It’s a manifold that is as close as you can be to being flat Without literally being a flat shape. So you might say, well, what does that mean? But in 6 dimensions, you can have something which is known as Ritchie flat. It’s a Kind of flatness that was developed in the early days of differential geometry. And so you can have the shape that’s as Closest it can be to being flat and yet not literally being flat itself. For those who wanna know a little bit more detail, the idea is if you take a a vector On this space, when you parallel transport it around any loop, it comes back to itself up to a symmetry transformation, And that symmetry transformation is demanded to line a particular group. And what is that group? That group is s u three. So that’s the idea Of this particular kind of shape which solves the equations of string theory and preserves supersymmetry At low energy. Do those

Brian Keating:

have Euler characteristics, or do they They can have a whole variety

Speaker:

of Euler characteristics. And so as we’ve studied these more and more, the range of numbers has grown, but roughly speaking, Call the Euler characteristics a number between you know, that that it’s less than, say, a1000. It can be negative. It can be positive. So There are a lot of possibilities in there. Euler characteristic 6 would be the preferred number if you’re trying to make contact with Particle physics as we know it. And over the years, more and more of the order character of 6 possibilities have been developed.

Brian Keating:

Do we know there will be no other forces, you know, discovered? I mean, we hear about these 5th forces. Yeah. Those are sort of esoteric in the in the forced Space, I call you know, if Yeah. If the muon has this anomalous moment, then it might be mediated by these virtual particles, which themselves would be a byproduct of Yep. Bosons, which are the Gauge, you know, force mediators, honest to goodness forces. I mean, do you do you believe there are, you know, possibilities that there could be Something as manifest as as gravity or or Yang Mills or or whatever that we would identify. That’s an honest to goodness force, or Can we not say right now that we will never or we will ever discover a new force, a new proper force?

Speaker:

So there’s sort of 2 answers to that question. 1 is in string theory proper, There are many versions of the theory that do give rise to other forces. For the most part, these Forces aren’t manifest at the energy scales that we have access to. So they would only come to life, if you will, if you’re probing the universe on Incredibly short distance scales or incredibly high energies. But the other answer is, look, if you have additional forces that Most of the particles that we know about are immune to, then those forces won’t have a whole lot to act upon that we have Observational insight into. So can you have additional forces that persist even at low energies? In principle, yes. Now there are Balance that come to this mostly from cosmological perspective because there’s a limit to the number of degrees of freedom that you can have commensurate with the Expansion rate of space and things of that sort. So is it possible that there are extra forces? Absolutely.

Speaker:

Is there any evidence for it? No. But string theory Has an abundance of additional forces at higher

Brian Keating:

end. So back in the the days of yore in 1986, there were 2 movies that changed my life tremendously. 1 was Top Gun, and the other one was Back to the Future. And a recent paper of yours, cowritten with our good good friend, John 11, It’s shown here. I read through it. Back to the future, causality on a moving brain world. I wanna get into this. I wanna say, 1st, again, thank you for that explanation, Klaviyal, and thank you for the connection between, 3 generations of fermions.

Brian Keating:

I wanna get from you what is braneworld. But before I go there, what interests me most lately, I kind of most cosmologists sort of assume inflation or something like inflation occurred. And I often like this term, which actually David Albert, your colleague and and our mutual friend, told me, actually, this thing originally came from, philosophy of science, but you’ll know it from Natty Seiberg who said if anything comes up, you know, that looks like string theory, that’s not part of string theory, we’ll just call it string theory. He said something along those lines. Right. David said that anything that, I think a philosopher of science that David’s like screaming at the camera now telling because he just told me 20, you know, 20 minutes ago or so. But he said that a philosopher of science said, you know, when we discover something in the philosophy of science, and then later it gets incorporated into physics, we just call Physics and say the philosophers didn’t help us at all. We’ll talk about philosophy, hopefully, if you if you have the energy as I’m getting my 2nd wind now at late at night here in Upper, upper, New York pen peninsula of, Manhattan Island rather.

Brian Keating:

But I wanna, first ask you, when I look at exciting things to me. It may be that inflation occurred or something like inflation occurred. We’ll get into alternatives to inflation just a bit. But those alternatives might look a lot like inflation. The alternatives to string theory might be subsumed within. But one thing that seems so different From all the you know, it’s like the platypus of of math also is Lorentz invariance. And if we were to show there was a a violation of Lorentz invariance, I think it would be almost a bigger advance or a bigger crisis in in science than, say, proving that inflation took place or motivating that inflation took place through CMB studies and Yeah. Faron Ahmedabad.

Brian Keating:

What what is your what are your thoughts about Lorenz and Vance? Is it sacrosanct? And maybe if you give a quick Definition. Some of the work was done by Madame Wu, and then this building was parity violation, which is a is a kind of an offshoot of Lawrence invariance. What is Lorentz invariance? Why is it central to string theory? How does it play role in this theory and then moving in back to the future?

Speaker

Yeah. So so Lorentz invariance is is Much, much bigger than string theory. You know, it it predates it, and it is a fundamental Symmetry property of just about any theory that we take seriously. And the idea really goes back To Einstein and, of course, Lorentz, who in the early years of 20th century, even actually the later years of 19th century, We’re thinking about Maxwell’s equations that you made reference to and noting that within those equations, there is this deep symmetry principle, which In modern language, basically says that any perspective that’s moving at a fixed speed in a fixed direction, constant velocity motion It’s really as good as any other perspective moving with a different speed in a different direction. So it’s describing An equivalence or really lack of preferential frame of reference when you consider the constant velocity observers That might be examining the world. And we we do, at least in a local environment, consider this to be A sacrosanct symmetry. This is what gives rise to the special theory of relativity. This is what gives rise The speed of light being constant, the way the symmetry is realized, light has a special quality of its speed being fixed.

Speaker:

And so the data behind this and the experimental confirmation of this is so strong over the past 100 years That people are would be loathed to give up this idea. But the one thing I wanna stress relevant to our paper is The symmetry really is confirmed in a a local sense. I mean, those are the experiments that we do. We consider some region of space Over some interval of time and within that region, call it the laboratory, call it your home, call it whatever. Yeah. Yeah. We we do our experiments and we establish this to be true. What we considered in our paper is not whether Lorentz Symmetry, Lorentz and Barrons would be violated in any local environment, but we wondered what if the overall grand Structure of space time is such that the symmetry is violated not locally, but only in the global sense.

Speaker:

What do I mean by that? Well, imagine that space doesn’t go on forever in a given direction. Imagine that if you go out in one direction, You go far enough, you wind up returning to your starting point, much as what would happen on the surface of the Earth, of course. And so we imagine that idea applying to the fabric of space. And in that environment, there are subtle violations of the Lorentz symmetry. You would never detect them locally. Rather, you’d have to circumnavigate the universe in some sense.

Brian Keating:

About the Laboratory or the bulk, or is it a micro dimension that you’re circumnavigating?

Speaker:

I don’t care what size the dimension is right now. So so I’m I’ll be agnostic on the size of this extra dimension. And the interesting thing is to ask yourself, If you redo Einstein’s analysis in a universe that has this nontrivial shape for one of the dimensions, How does it change what Einstein did way back in 1905 for the special theory of relativity? And we found some surprising results. We found that you can Send signals in this universe at a speed that’s actually greater than light speed.

Brian Keating:

Is it always greater, or can it be greater? It can slow down. It can

Speaker:

So so if we get a little bit more into the detail, you mentioned this idea of a brain Yeah. Before. So that’s one of the key ideas here. We imagine that our universe It’s living on what I like to poetically think of as a giant slice of bread that itself is floating in a larger environment. So imagine Everything that you know just for visualization purposes takes place on this giant slice of bread universe. Obviously, it’s only 2 dimensions of space, but In the real version, it would be 3, but it’s too hard to picture. So allow let’s do this lower dimensional version.

Brian Keating:

Right.

Speaker:

And imagine that’s right. So this slice of bread is called a membrane or a brane. Yep. That’s where this idea of brane comes from, and it’s a very natural idea in string theory to envision that the universe, as we know it, takes place on a Three-dimensional membrane, but the two dimensional version of the piece of bread is a good one to have in mind because then you can picture it. But imagine that Perpendicular to that slice of bread is an additional dimension of space and that our slice of bread can move In that additional dimension of space. And imagine that that additional dimension of space has a circular shape.

Brian Keating:

Is So

Speaker:

in principle, This slice of bread can be moving around this extra dimension in the shape

Brian Keating:

of a circle. Dimension. Right? Mhmm. You want some

Speaker:

Now here’s the interesting thing. If I wanna send a signal to my friend who’s far away on our slice of bread, you would think the easiest and fastest way to do that is send a light signal along the slice of bread. Right. Just ignore the extra dimension. That’s just superfluous, you know, if you wanna get there as fast as possible. We found, however, that if you are moving, If your brain is moving in this extra circle dimension, there’s a faster way to get the signal to your friend. You don’t send the signal right along the piece of bread. You send it in the circular dimension, allow it to wrap all the way around the circle, and then hit your friend.

Brian Keating:

Because it’s moving. That’s sort it’s a Galilean relativity now, you’re boosting it.

Speaker:

Well, but it’s actually it’s really special relativity and and Lorentz symmetry that comes into the Story here when you do the mathematical analysis. But yes

Brian Keating:

In the in the combined rotating branes Yes. Along that one special axis.

Speaker:

Yeah.

Brian Keating:

So would there be, Satrapy, I mean, would you have this violation also in spatial

Speaker:

Yeah. You do have you you have a kind of left right violation because The question is, are you moving clockwise or counterclockwise around the circle? And that can affect The results that you get, in fact, it does affect the results.

Brian Keating:

Weird time and causality issues

Speaker:

like that. So causality is the big one. Uh-huh. Because, normally, Whenever anyone says, I can send a signal faster than the speed of light, which is what we are saying. Yeah. The response of most physicists will be, Oh, that’s interesting. You must be violating.

Brian Keating:

Father.

Speaker:

That’s right. You must be violating causality. Because if you can send a signal faster than the speed of light, we’re trained to conclude That causality must be violated. That training is actually wrong because here’s the thing. What you really need to determine is whether a so called Closed time like curves. Yes. That is, can you send a signal to your friend and have your friend send the signal back to you and have the return signal get to you before you send the original signal in the 1st place.

Brian Keating:00:51:52]:

I

Speaker:

see. Because let’s say that return signal killed me. Mhmm. How would I be alive to send the original signal in the 1st place? So we did that calculation. We did the round trip Travel time. I send a signal to my friend. The friend returned it to me. It will always get back to me a smidgen of a second after I’ve sent the original signal.

Brian Keating:

Oh, so so so the causality is built in. So, yeah, I’m reminded a little bit of Of, you know, famous girdles.

Speaker:

Yeah.

Brian Keating:

He also had a Sure.

Speaker:

Girdle universe. Yeah. Girdle universe. Yep.

Brian Keating:

And then, I believe, yeah, he he sort of went to his deathbed believing that that was true, and he was a character for sure. And, wow, that’s that is really fun.

Speaker:

But let me just answer the other question you mentioned before. You asked me in of how fast can the signals go. Mhmm. And so our calculations show that when I send the signal To you, far away on the brain, the speed of that signal can be arbitrarily large. And in fact, the formula for it Uses a very famous symbol called gamma that we all teach to our special relativity students. Yep. Again, I usually don’t talk in mathematics, but Why not? Smartest audio Again, it’s one over the square root of 1 minus v squared over c squared. Now now, normally, That is a factor that we use in special relativity to talk about length contraction.

Speaker:

You divide by gamma or time dilation. In this particular case, it enters differently. It enters as the speed of the signal. The speed of the signal is not one over gamma. It’s gamma or gamma times c if I put c back into the story. Gamma can be arbitrarily large.

Brian Keating:

Yeah.

Speaker:

And therefore, the speed of the signal can be arbitrarily large. Now what does that mean? Normally, when we talk about the possibility of aliens, and I’m just using this

Brian Keating:

We have

Speaker:

to talk about.

Brian Keating:

This is podcasting in 2020 3.

Speaker:

So this is this is but this is so Maybe I shouldn’t even use this thing.

Brian Keating:

No. No.

Speaker:

Keep it. You can’t you can’t drop a bomb. Alright. Alright. So imagine there is some extraterrestrial civilization far away. Normally, we say, Well, it’d be interesting to know they’re there, but we can’t really have a conversation because we’ll say hello, and then, like, a 100000 years later, we’ll get the signal. Then a 100000 years later, again, we’ll get the return signal. We won’t even remember that we sent it.

Brian Keating:

This podcast with you. You’re so busy. Yeah.

Speaker:

But I I exactly. So So so so that would suggest that, you know, you can’t have real time communication when the other person at the other end of the line is too far away. In this approach, we can have a real time conversation with a civilization arbitrarily far away because we can get the signal there Arbitrarily quickly if we are moving sufficiently quickly in this extra dimension, and then they can get it back to us. And it will always arrive after we sent the signal, but it could be very it could be a second later. So we’ll say, hey. How are you doing? Oh, we’re doing fine. Oh, really? What’s going on? And and You could end

Brian Keating:

principle Right.

Speaker:

In in this universe. Now I’m not saying that this is necessarily our universe. I don’t know if there’s an extra Dimension, I don’t know if there is 1. It’s in the shape of a circle. If it’s there, I don’t know that we’re on a brink moving through it. But what’s beautiful to me about this example is Einstein wrote his paper a 100 and whatever, 18 years ago. Yeah. Okay.

Speaker:

One would have thought That there’s nothing else to extract from thinking about Einstein’s special relativity. It’s ensconced in the textbooks. We We teach it to our students. It’s done with. Right? And yet, by just imagining this little generalization of Einstein And where you have this extra dimension in the shape of a circle, you extract these wonderful new results. So you asked me when we started, what does a theorist do? Here’s what a theorist does. Now normal usually, we don’t go back to Einstein in 1905. You know? Most state, you know

Brian Keating:

get a lot of emails saying

Speaker:

Einstein is wrong. But but, normally, that’s More on the crackpot today, but here it is going back to Einstein 1905 and doing rigorous calculations and coming to something which to me At least was shockingly unexpected.

Brian Keating:

And as I said, I I think I would if you gave me or God gave me the choice between, you know, say, verifying that, you know, inflation is Consistent with, you know, this production of gravitational waves from early universe tensor perturbation or, you know, just kinda a lot of people assume is true. I actually don’t. I wanna get into, cosmological alternatives. But if you if you assume that you had that choice or you could prove that Lorentz, you know, invariance is violated, to me, that’s That’s the holy grail. And in fact, I wanna get your reaction to this because I can’t resist. Again, we’re in this building, this historic building, on the campus of of Columbia University. And, Chinseng Wu, when she discovered, in the course of, like, Christmas break, she got down to 3 Thousands of a Kelvin in an apparatus with a radioactive spinning cobalt nucleus that she magnetized just to try. I mean, The catch of that today.

Brian Keating:

I mean, it’s not like it’s some easy thing that, oh, you can go like most of our experiments in our lab classes at San Diego. They’re they’re previously, you know, won Nobel prizes, Davis or Milliken oil drop or whatever. This, my students are not gonna do. It’s cost $1,000,000 to get an evolution for it that you could possibly Anyway, she verified that that the actual the weak force is as maximally parity violating as possible, which you You couldn’t, you know, think of as another kind of symmetry that that could be respected under the grand rubric of all possible symmetries that nature could be expected to respect. We found that electromagnetism later is unified with the weak with the with the weak force and the work of Slom and, Glashow and Weinberg that we discussed earlier. Is it possible that not only the strong nuclear force would exhibit, would exhibit parity violating properties, but also potentially electromagnetism. And I’m speaking now of things like Chern Simons, cosmic birefringence, and and and things that we’re looking for actively. And, actually, Jim Jim is hoping that we’ll discover it because, you know, Brian, we got him an asteroid.

Brian Keating:

I I got an asteroid named after Jim Simon. Oh, is that right? He’s got a boat. He’s got a a plane. You know, he’s done it, But the one thing he doesn’t have is a Nobel Prize. And so every every year he talks to his friend, Frank Yang, gets because you can nominate people who, for the Nobel Prize if you’ve already won 1, which, you know, unfortunately, I have not, so I can’t nominate them. And I wrote a book that’s kinda, yeah, a few of it. But I wanna ask you, is it possible that not only Electricity magnetism might have, like, violate parity at some level, but gravity, because all the forces are unified Yeah. If unification is true.

Brian Keating:

Or if you don’t see it, does it mean that unification possible. Yeah.

Speaker:

The bottom line is I have no idea, and I don’t think anybody really does. You know, again, what do theorists Due to that question, one of the things that we do is we take established theories and we add new terms to them In order to break some cherished symmetry or some cherished principle and then Try to determine through mathematical calculations whether this new term violates something else that we’ve already confirmed experimentally, Or does it give rise to a prediction for something that we can go and look for? So there are a gazillion papers which should do this. And, of course, the challenge to the experimentalist is, which ones do you take seriously enough to actually put the effort in to try to test? So, you know, far be it for me to pass judgment on, you know, a whole body of work where all sorts of symmetry violating terms have been added to various Theories, it’s exciting to imagine that something new and profound can happen even in the most well tested theories. Mhmm. But I think it unlikely. Mhmm. But, of course, the prize is huge if the unlikely thing actually bears fruit, so I don’t know. Mhmm.

Speaker:

So

Brian Keating:

I wanna pivot from the very small to the very large and talk about cosmogenesis. You know? I would say, why are people so interested in this? And all you have to do is ask I’ll ask you. What’s what’s your favorite day on the calendar?

Speaker:

My favorite day on the calendar. Mhmm. I guess I’m supposed to say my birthday, but I won’t. Is that what you were looking for?

Brian Keating:

Now. Could be your birthday. It could be your anniversary. It could be when your kids are born.

Speaker:

I wish I could give you my anniversary. I just don’t know it. It’s either October 9th or October 10th.

Brian Keating:

Tracy, both of them.

Speaker:

Well, thankfully, both. My wife and I both Completely get it mixed up. So I’m gonna go for October 9th. Good to yeah.

Brian Keating:

And I think you’re born on February 9th. So 9th are the key here.

Speaker:01:00:03]:

That’s true. Yeah.

Brian Keating:

So, couple days before Galileo’s birthday on February 15th. Yeah. I always ask people that because, usually, it’s in a it’s a beginning of something. And people are always fascinated beginnings, and I think the universe is no different. And I think that explains the surface of ideas for cosmogenesis, right, and, among other things. But but when you look at the kind of spectrum of of models, we we’ve discussed Candidate alternative. I don’t like to say it’s a string theory, but let’s examine, work that you’ve done and others, that we both know have worked on that Purport to explain things other than, requiring inflation. I’m thinking of conformal cyclic cosmology with our mutual friends, Roger Penrose Yeah.

Brian Keating:

Paul Steinhardt and the Aegis, Milturoch, and they’re, they’re bouncing in cyclical cosmologies. And even I my old My current office is occupied by Jeff Burbage of of, you know, quasi steady state cosmological fame. And I actually talked to Giant Narlikar not too long ago on the podcast, the Sole remaining survivor from the quasi study state base. So, when you look at these models, a lot of them start from the starting point that Inflation and the multiverse that comes concomitantly with it. In most models of inflation, you have the multiverse. Andrei Linde said the same the very thing in my very on this podcast. They find that distasteful. Paul has said Paul Steinhardt, good friend of mine, has said that not only is the multiverse dangerous to science, it’s dangerous to society, because it undermines the efficacy of the 400 year old scientific method pioneered by our hero, Galileo, and and, and and many others.

Brian Keating:

So I wanna ask, Is that a coach is that a valid reason to kinda pursue alternatives? Is the multiverse so anathema to not only let’s let’s leave society a bit. I think society’s got his own problems, but what’s your take? Is a multiverse a problem? Is it a journey? I have to

Speaker:

say I’m a little bit surprised that Paul went that far In his critique of the multiverse. Because there is something very real to say, and he’s been saying it Loudly and with intelligence for a while, which is the following. If you wanna make predictions In the context of a theory that involves other universes, you’ve gotta have some means of saying which universes are more likely And which universes are less likely. Because if all universes are out there, then all manner of physical Phenomenon, all manner of observables, all manner of values of those observables takes place in some universe. And if you have no means of saying, Well, yeah, those universes are incredibly unlikely, and this one and that one are very, very likely. And therefore, I believe that those values are the ones that are most likely. If you can’t make that’s right. If you can’t make a statement like that, you are lost from the standpoint of making predictions.

Speaker:

So, Paul, this is called the measure problem. You You wanna be able to place a measure to say this one’s likely and this one’s not likely. Now that’s a scientific question To try to come up with a means of assigning likelihood to given universes, it’s not a problem that we’ve cracked. But there are many proposals, many mathematical ideas that people have put forward. And so I find it surprising that Paul would go Further than that and say this is somehow fundamentally, like, bad for science when there’s a real scientific issue on the table. And if you can resolve that Scientific issue, then this fits squarely within the scientific method. It’s a little bit different in detail, but it’s still you have a idea, you develop it mathematically, and from that, you make predictions. Because once you have a measure, you can make predictions.

Speaker:

So that that’s a little bit surprising. But coming back to your question, Yeah. I would say the following. If we could resolve all puzzles in physics without recourse to a multiverse, My inclination, more like an Occam’s razor approach, would be to take those ideas most seriously first. But if we continually run into a brick wall in trying to answer fundamental questions in a single universe framework, And we can answer those problems in a multiverse, a multioniverse framework. We should at least allow that to be part of our toolkit. We should allow it to be among the ideas that we take seriously and pursue it mathematically and, for instance, try to answer this measure problem. Mhmm.

Speaker:

With that, we are doing science. And so I think that to me is the most rational and sensible way of thinking about it.

Brian Keating:

And what about the syllogism that, you know, we and I use this to, you know, butter my bread in the in the Keating household, but, you know, that if you measure gravitational waves in primordial form Via their imprint on the cosmic microwave background’s b mode polarization, as we claimed to do about 8 years ago, and then recant it, and now have an opportunity to detect it again for the 1st time, with science observatory by separate array and and many other experiments. If we do that, then that will be circumstantial, but the strongest possible evidence that we could hope to measure of the epoch about a trillion of a trillionth of a trillionth of a second after the big bang. And, therefore, that would be indirect evidence for the multiverse. In fact, on the day of which the BICEP two announcement took place, People like Max Tegmark, mutual friend Max Tegmark, would say things like, you know, hello, gravitational waves, you know, hello in a multiverse. Yeah. And it was almost, you know, almost too Hollywood perfect for his book, The Mathematical Universe, to to resist. So I wanna ask you, at what level does that syllogism, Hold, get a curry favor with you or hold water with you. In other words, I tell you tomorrow, I’m trying to hear some secret information.

Brian Keating:

China’s never tried to measure it. Would you believe the multiverse more than ever?

Speaker:

No. So not quite that quickly. So generally speaking

Brian Keating:

I’ll say it’s confirmed, by the way.

Speaker:

Yeah. I I get it. I get it. But I would generally say the following. It’s certainly the case that if you have a theory that predicts a multiverse and also makes a whole variety of other predictions that you really can test And confirm in our single universe, then, of course, that adds weight to the prediction of things that we can’t confirm directly. So, yes, I do agree that evidence of a theory can accumulate from observations in our universe, and that allows us to take seriously predictions for things that we However, it’s also the case that there may be competing explanations for whatever it is that you’re confirming in this universe, And those other explanations may not involve a multiverse. And, indeed, I think that’s where we’re probably going in this conversation Because, yes, were inflation truly the only game in town, the only cosmological theory that can give us Insight into the cosmic microwave background radiation. Solve the horizon.

Speaker:

Problem solved. The flatness problem. Give us all Of these insights into things that we observe in our universe and also by the way it predicts a multiverse, then sure, we’d be led in that direction. And, yes, Your example of finding that primordial gravitational waves would be one more piece of observational evidence in our universe, and that would be an interesting and tidy story. But there are other ideas that people have put forward, and those proponents claim that they can explain all the things that I just mentioned. The horizon problem, the flatness problem, and so on and so forth, and and that would be interesting to see. Now In this very specific case that you gave, finding primordial gravitational waves, these competing theories, and one in particular, Paul Steinhardt, doesn’t give rise Did that

Brian Keating:

Rogers theory doesn’t give us It

Speaker:

doesn’t argue with it. But these are simply the ideas that we’ve developed to date. And so I would not immediately jump to the existence of a multiverse if you were to come with to me with that data because I would say, Let’s allow our brains to continue to strive and see whether there’s a single universe theory that does comport with everything. Again, I wouldn’t rule out a multiverse. I’ve written a whole book on the multiverse. Right? So I’m not I’m not anti multiverse.

Brian Keating:

No. I’m

Speaker:

not. But I am Reluctant to jump so quickly to such a radical proposal of other universes. I would rather say, hey. This lends credence. It increases my Bayesian probability that that that that this idea may be true. However, I’m gonna still hope myself and others inspire others to continue looking for more pedestrian explanations that don’t involve a multiverse. And if 10 or 15 years later, there there’s nothing comes up, yeah, sure. Then then then it becomes even more fun.

Brian Keating:

Ever, just before we pivot to our maybe final couple of topics, if you do you do you have 4 minutes? I can’t I’ve definitely got my my 2nd and third win being here with you, Brian. It’s so exhilarating. So you view the multiverse as a prediction. Actually, I’ve never I’ve never heard it phrase like that. In other words, I’ve heard it phrase as a consequence, a Paradigm, but not a prediction. And I and I think that’s an interesting way to look at it because I would say that inflation’s very successful when it comes to retrodictions In that, it explained, you know, Dicke’s conjecture of the the the paradox of fine tuning of the of the curvature of the universe that even in the Seventies, they knew it was around 1. It wasn’t 0. It wasn’t infinity.

Brian Keating:

And then the the, you know, the the oldness or the in the horizon problem. Those are kind of retrodictions that you want your theory to explain. But the the novel prediction and even, I do believe that the the b models are Primordial tensor perturbations, in and of themselves per se, are actual are novel effects that would falsify, not prove inflation, but falsify over the arrival. Right? So in that sense, what would you like to see in a you can talk to god. Right? And so you say to god, I want a candidate theory that replaces I’ll tell you what I would like. I would like for these alternatives to not have the kind of sine qua non of inflation, which is the infotainment field. I would like to have a theory, and none of them have it today, Have a scalar field free version of a cosmogenic event. Maybe I’m wrong because I’m not, like, searching this.

Brian Keating:

Sir Roger has the or he doesn’t have a scalar field, in the sense that that Anna, Aegis, and and Paul Steinhardt too, but he has these aropons, these mysterious dark matter particles that act like The creation field of of Hoyle and and Do

Speaker:

you know it at a level of detail? I don’t. Yeah. I don’t I don’t know about that yet.

Brian Keating:

So so I when I if I was, you know, a good theorist or a theorist at all, I would say I wanna invent the theory that’s at least at least like inflation as possible, which means not having a sine quaonon, which means I’d like it to not have a scalar What is your minimal universe? What would be the minimum viable product that you would ship as a theorist, you know, to say that here’s an alternative to cosmogenesis It doesn’t look like inflation. It doesn’t have this this these features in it. What was your minimum viable?

Speaker:

Well, I I I’m not sure I would go in the direction that you go. Okay. I find inflation actually a beautiful mathematical theory Oh, sure. Including a scalar field, the Most simple kind of field that there is and one that we now know does exist, at least the Higgs field is a Specific example of a scalar field. So it’s no longer this hypothetical thing that it was when it was first introduced into inflation. Now we know there are fields that have this quality called being spin zero and have being a scalar field. It’s a very beautiful theory. It makes use of this spectacular feature of Tacular feature of Einstein’s theory that gravity can be repulsive as opposed to just attractive, that’s a a beautiful quality of the theory, And it so elegantly resolves many cosmological problems that people scratch their heads over before the theory was put forward.

Speaker:

So I don’t look at inflation and say, let’s, god, do one better than that. That that’s but what I would say is inflation doesn’t resolve all questions. For instance, where did these fields come from? Mhmm. Why is there a universe at all? What happens at time 0? Because Even though inflation changes the nature of time zero, it doesn’t allow us to truly answer the question of how things got Started in the 1st place. It’s still a theory of how things evolve from a tiny fraction of a second after whatever Created the environment and the ingredients that allows the theory to clock forward. Mhmm. So those are the questions that I would want, You know, the all powerful thing to to resolve or give a theory that transcends inflation and can embrace Answers to those questions.

Brian Keating:

So in a sense, the inflation may be that minimum you know, Occam’s were Occam’s cosmology in a sense. Yep. I want you Get your reaction. You know, when physicists get older, they they devolve into the interpretations of quantum mechanics. But I wanna get into the interpretations of the multiverse. Having written books as yourself, it’s never been clear to me why in both the multiverse and the string landscape, Why we say things like there’ll be different vacuum states, and those could lead to different not only different constants of nature, but they could lead to different laws of physics. I’ve heard that said, and, and you’re shaking your head, so maybe I’m maybe I’m correct. I’ve certainly heard people say such things.

Brian Keating:

I don’t know if it’s actually true. But my question to you is perhaps a philosophical one. Why stop there? Why not say actually, there are different laws of mathematics and even Different laws of so called predicate logic. In other words, in different universes, modus tollens doesn’t work. And not only are is the differ is is g, capital g, 9.9 meters per second or, you know, or whatever. Yeah. The gravitational for lowercase g, But it’s actually, it doesn’t follow that that that, you know, if a then b and b doesn’t follow. Here.

Brian Keating:

Right?

Speaker:

So so yeah. So so the case that

Brian Keating:

we have a different laws of Philosophy, mathematics Yeah.

Speaker:

So so it’s an important question to ask because the answer requires that I spend just 1 minute, A little bit more detail on where the multiverse comes from, say, in the in the theory. Let’s use string theory as as a as an example Or in string theory coupled with inflation, if you wanna talk about, you know, the process by which other universes might come to be. So the idea is That there’s 1 overarching mathematical structure that applies to all of these universes, And it’s simply in string theory say that the extra dimensions are curled up in different ways in these different universes. But because the overarching mathematical structure is still string theory, it’s just string theory in the universe with the dimensions curled up like this

Brian Keating:

Or

Speaker:

string theory in the universe with dimensions curled up like that. So in that sense, the equations are the same, and it’s just environmental differences, The shape of the active dimensions, you know, and and that’s really all that it is. So Mhmm. That’s why I would say it’s not even that the laws of physics Vary from universe to universe. It’s that the laws of physics manifest in different ways because the environment changes from place to place. I mean, we’re all familiar. Gravity on the moon seems different than gravity on Earth. Right? Astronauts can jump whatever 20 feet into the air, But we all know that it’s still the very same law of gravity, the ideal Universal.

Speaker:

Yeah. That Newton wrote down or Einstein, whichever take, you know, take your pick the level of accuracy. It’s just that the environment is different. Because the moon is less massive than the Earth, gravity manifests somewhat differently on the moon than on Earth, and that’s the way In which these different universes differ. Same overarching mathematical structure, same overarching formulae, but the way they manifest can change Based on the shape of the extra dimensions. So that’s why it’s not going to different logics and different different kinds of mathematics. It’s really a uniform Form quality that permeates all these universes. Now having said that, you can use your imagination to imagine more Robust versions of a multiverse where, yeah, you could imagine that the kinds of mathematics that take place is different.

Speaker:

You know, continuing mathematics, P adic mathematics or or the different kinds of logics can can differ. Those multiverses though are coming directly out of the human imagination. They’re not coming out of a rigorous mathematical theory like string theory or inflationary cosmology. It doesn’t mean that those ideas are wrong, but they’re just less motivated. Mhmm. Because they’re just coming from a what if standpoint as opposed to here’s this theory, We study it, and, oh my goodness, look what comes out. A multiverse because there are different ways for the extra dimension to be curled up, or there are different big bangs and say an inflationary multi 1st giving rise to different swelling domains, each of which should rightly be called the universe of its own. Those multiverses come directly out of the mathematics, And that limits the ways in which those universes can differ from each other.

Brian Keating:

Test each other. I I see. Okay. Excellent. So you are gonna pivot now, to 2 last topics. 1, Is, education and pedagogy, and last 1 is aliens. By law, you know, we must talk about aliens, and then it’s either aliens or Bitcoin. Which would you prefer, Brian? Yeah.

Brian Keating:

It’s up to you.

Speaker:

Yeah. We’ll go. Yeah. They’re kinda the same. But, yeah. Not.

Brian Keating:

Alright. Send your hate mail to this Brian, not to this Brian. So, education. Yeah. You’re a renowned educator. I’ve learned tremendous amount from you. I saw you first. I met you in person Back in 1995 at Brown University where I was a grad student, you were, I believe, moving from Cornell to Yeah.

Brian Keating:

This very location and your career, and it was, you know, what is it? About the anniversary or your book had just come out maybe a couple years earlier? Or and, you’ve taught millions, And and you continue with your World Science Festival that you have this phenomenal team and you and your wife are are doing so much so much effort. First off, How do you envision the role of a scientist as an educator? And I’ll I’ll I’ll make a bold statement. I believe it’s my moral duty to have A podcast to give a lecture to make a TikTok to do something based on the fact, hey. I’m teaching at a public university, but all of us were supported by the public. We’re all serving at the largesse Of the American taxpayer or whatever government you’re in or work for, or or live in rather. And, I believe that we we take a lot, and we would do this for I mean, you and I have such pleasure in finding what we do as a living. I think we do it for free, more or less, at least I would. I love building and tinkering and playing around with physics.

Brian Keating:01:18:30]:

But, a lot of my colleagues will react negatively to that. They’ll say, no. Stay in your lane. Stay in the lab. It’s too hard, and we’re not good at it. Obviously, I I’ve never I haven’t had, like, much training in terms of, like, podcast. You can probably tell. I’m always learning, but, you I know that people have have investigated it.

Brian Keating:

And I also say to people, had a battle with Sabina Hassenthalder, who’s my curmudgeonly friend from from Germany who has a wildly successful podcast. And she said, yeah, stay in your lane, basically. And I said, well, why? And she said, well, it’s really hard. It’s very difficult. It’s not in the skill set of most scientists, so why force them to come out of the laboratory to go into the and I said, Sabina, you know, to be fair, like, did you come out of the womb knowing quantum field theory? No. It was hard, and you learned it. And to say that something is hard, so we shouldn’t expect our students and actually to teach them that communication with the public who feeds them, who pays their is unimportant or that they should ignore it. I think we do that at great peril, not only to the public understanding of science, but To science itself, because once the public loses faith in science and scientists that were just these specialized insects working on one thing and that’s too hard for them to understand, gonna stop funding.

Brian Keating:

I would stop funding. As people said, you’re not smart enough to understand what I do. You can’t even explain it to somebody. So I said a lot, but Let me know. What is your feeling on the minimal obligation of a scientist to explain his or her work to the general pub?

Speaker:

To go out to the public And to explain what you’re doing, you kind of gotta enjoy it. Right? So I I get the feeling that you do enjoy Oh. Doing this.

Brian Keating:

Right? This is a story I love doing. Yeah. Self promotion.

Speaker:

And and and so anybody you know, they’re not all physicists would like to be doing This kind of work. And so to imagine that there’s some moral responsibility that everybody should do it, That seems to me not necessarily a productive way

Brian Keating:

of focusing. Linear algebra. I mean, I just I just invested it. It was so boring. It’s just rope memorization. I wasn’t good at it. Should Should I not do it? I mean, because it’s uncomfortable and not easy for me?

Speaker:

Well, I would say that you probably did it because you wanted to learn quantum mechanics is my guess. Right?

Brian Keating:

Actually, it was, like, a civil engineering major for

Speaker:

But but you had you had motivation to learn it because as a team. You know? But for, you know, some physicists who are right at the edge. I mean, you know, take take someone like Edward Witten.

Brian Keating:

Mhmm.

Speaker:

Right? Who’s actually a wonderful popularizer, so this may not be the best example. But if you were to say, Edward, you’re not doing enough for the public. Yeah. You do some interviews. You did a wonderful World Science Festival program, but you’ve gotta have your own Podcast, Edward. Morally speaking, you gotta be out there. I don’t think it would be the right thing to force him because I’d rather have Edward And because

Brian Keating:

he did the world science studies.

Speaker:

That’s right. So so the point is, I think every physicist, if we just stick to our field, Needs to determine for themselves how much they wanna do and how much they’re interested in doing. And if there’s some who don’t wanna do it at all, I’m totally fine with that because I don’t feel like you should force someone to do something of this sort.

Brian Keating:

Let’s not take the Latin example because you don’t see So we do not I mean, it’s just the primus inter parum or whatever the Latin phrase is. Let’s take your grad student. Sure. Should she not do it? Isn’t it not good for Her to develop confidence talking to the public, talking to a camera talking and and perving, a lot of what you and I do is Persuasion and salesmanship, and and we have to be good at convincing funding agencies, tenure committees Yeah. Admissions. You know?

Speaker:

But those are all those are all Somewhat different skill sets.

Brian Keating:

Sure. I know.

Speaker:

So so it’s certainly the case that students need to learn how to write a grant. And in a grant, you need to be able to describe your work in a way that’s exciting and accessible. And if you don’t do that, it can have really negative implications. Yes. Certainly on that front. And when I look at my own graduate students, there are some who absolutely should go out Into the world, and some of them have in terms of explaining. There are other

Brian Keating:

of my

Speaker:

graduate students that I really do not think it would have been the best thing for them to go out Into the world and Sure.

Brian Keating:

And

Speaker:

and and and many of them them haven’t. But having said that, one of the things you mentioned, the World Science Festival, we try to provide a platform Where scientists from around the world can come and maybe not do a podcast where it’s gonna be every week, but maybe come once a year

Brian Keating:

Yeah.

Speaker:

And talk to the public in a way that can really have impact. So so, yes, I I partly agree with you. I think it’s obviously vital and important, But I wouldn’t necessarily say that it’s moral responsibility of everyone to do it. Rather, if you’re driven to do it and you enjoy doing it And it’s fun doing it, and it’s productive doing it. By all means, do it. Yeah.

Brian Keating:

I think you should try it and see if it does appeal. You fertilize water, the fertilized ground, and see what comes up. Yeah. But sticking with education, you and I are part of an august profession, you know, being profane. I always say, what’s the proof, Brian, that being a professor is the greatest profession on Earth? I don’t know if you have Proof. I have a proof. What was the only career suitable for the most famous man on earth right after he walked on the moon’s surface? Neil Armstrong became a professor at the University of Cincinnati. Oh, is

Speaker:

that true?

Brian Keating:

He was an engineering professor, and that’s, he lived out the rest of his life. I think I could’ve done anything. Right. And he was very satisfied in doing that. And and to think that, you know, we get paid to do it. I would say it’s like being, you know, paid to taste chocolate Or be a wizard and, you know, Harry Potter. But we get to do this great thing, and yet and yet our profession’s pretty damn Sclerotic. I bet, you know, when you were at Oxford, when I was at Brown, you know, there was some person scratching on.

Brian Keating:

There’s a beautiful, bespoke, chalkboards Floor to ceiling with your Harry Gumo chalk probably over there. Not with the Crayola. How could you, Brian? You’re letting down generations of theoretician. But there was some guy or gal scraping on a rock with another piece of rock as David Kocher always talks about it. And this goes back to the year 10/80 of the University of Bologna where the 1st Western University was And look. Okay. We so I use PowerPoint or Keynote rather. Okay.

Brian Keating:

Not much has changed. What do you see as Threats are opportunities for pedagogy in the 21st century with maybe new tools like artificial why should my students learn from Brian Keating when they can learn from Brian Green Virtually with an avatar in three d, you know, at the speed of light.

Speaker:

I think you’re you’re you’re right. Not that your students should learn from me, but that there are Huge opportunities. So one of the things that we’ve been developing are virtual reality experiences. We have a virtual reality experience for middle school kids where they can Build stars and have them go supernova. We have another experience where they play a game where as they Progress in the game, they go faster and faster getting closer to the speed of light, and all the weirdness of relativity comes out in the virtual reality experience so they can get a more Intuitive sense of these ideas. So I think there’s a huge opportunity using that kind of medium For science to become much more internalized as opposed to just seeing it written on a blackboard. In terms of education itself, I I agree too. You know, a handful of years ago, I did a course you probably haven’t seen on special relativity where, You know, I basically again, it was a purely digital course, but I was using, at that time, cutting edge technology, which is basically 8 foot wide iPads In which I didn’t just use the chalk on a chalkboard, but I could write, I could show video, I could do demonstrations.

Speaker:

And so to me, that refers a personal proof of concept That you could use these tools to create. Look at that. I just knocked your microphone over. Sorry about that.

Brian Keating:

Stops up. Are we

Speaker:

still working? Yeah. Yep. Yep. You know, that you could use Tools to to really radically change the educational experience. Right now, we’re doing a a new course in quantum mechanics, which will be for the general person, but it’s The full college level quantum mechanics course, chock full of visuals, chock full of interactive demonstrations. So I I agree with you. There is a way to go beyond what we’ve been doing for, I usually say, 500 years. But if you go back to 10/80 Yeah.

Speaker:

I gotta go. You you you take, you know, almost a 1000 years. You know? So yeah. I I absolutely agree.

Brian Keating:

Yeah. I’m really excited about it. UCSD, one of my colleagues is working on AI avatars that use voice synthesis, use Clothing from video game, you know, Unreal Engine to synthesize Gandhi or I’ve I’ve taken all of Feynman’s works because they’re all public domain now. And I’ve digitized them, and we have a Feynman bot on our website that you can communicate with as if he’s sitting right there. Now but you can imagine the the visceral nature There’s people in Maslow’s hierarchy of needs, and and you you look at how do people learn and what what’s the primacy of learning and the exposure, and the more visceral you make it, The better. And I think, you know, you as an educator, you know, are are really kind of doing yeoman’s work along with your with your team and your crew. How do you decide, you know, how to allocate your time? We talked about what you do, but you’re you’re doing so much with the WSF, and, you’re making time to do, you know, podcasts with But nobody’s like me. But but, Brian, how do you determine, like, I’m gonna do an explainer video.

Brian Keating:

I’m gonna do this fabulous TED talk seen by 6,000,000 people. I’m gonna do WSSF every single year for the past, what, 15 years. Yeah. Unbelievable. So how do you decide just what’s your what’s your day load, your workflow Well,

Speaker:

it was the case years ago when I was a assistant professor at Cornell, which is really when I started to To do stuff, more generally for the public, my strategy was pretty straightforward, which was I would do physics by day, and then sort of by 6 PM, I’d go home, eat dinner, and then I do the other stuff by night, writing articles, you know, Writing books. You know? The elegant universe was written totally in the evenings. I diligently did not allow these 2 different types of undertakings to interfere with each other. But then what happens is you get older, you get married, you’ve got kids, and and now all of a sudden, I, you know, Didn’t evenings didn’t exist any longer. Oh, did I write a kid’s book? Yeah. Well, that did that that’s that’s true too. But that’s when things really changed for me, really, when I had my first Child, which I guess that was 2005. Mhmm.

Speaker:

And then it really came down to a decision. Do I spend my time on x or on why. And in the early days, I struggled a lot with that, really trying to find the balance. Okay. I did this many hours of research this week. I gotta Do more next week. It was that kind of thing. And finally, I got to a place, and I said, look.

Speaker:

Life is short. And this struggle that I’m Creating for myself is totally in my own head. I can do whatever I want. And I just decided, let me just do whatever Feels right at a given moment. And so if it felt right to jump into a book and that meant that research projects Had to go on hiatus or even on complete hold, so be it. Then some interesting research project would crop up at some point later and say, Drop the book and work on the research product because that’s the most exciting thing at a given moment. So I stopped evaluating it. I stopped judging myself.

Speaker:

And I said, let me just live. As an individual who likes to do research and to write books and, you know, I’ve written stage pieces. I mean, you know, we had things of that sort, World Science Festival programs. I like these kinds of conversations, you know, and let me just go with the flow and see where it leads.

Brian Keating:

Wow.

Speaker:

And that’s been a perfectly fine And happy face going forward. You know?

Brian Keating:

So we’re coming up this Thursday, I believe, is the 90th birthday of Carl Sagan speaking of of Cornell. And, Carl, of course, is known for many things, but one of my favorite things that that he did I guess you did it with Icarus at the edge of time. It was write a fiction book. Yeah. Fiction book is called Contact, loosely based on our past guests and also Cornell alumna and last name maiden name Cornell, which is Jill Tarter. And, of course, these are subjects revolving around our final topic, which is aliens. So much is in the zeitgeist, of aliens, the spirit of the time, the the news Cycles we’ve had NASA panel led by the president of the Simons Foundation, David Spergel, an eminent, National Academy of Science member, leading a NASA panel to talk about these unidentified aerial phenomena. What do you make of this? What do you make of the eyewitnesses? I’ve had on a couple on my podcast, Navy fighter pilots, doing stuff I could never have the bravery or physical fitness to do, obviously.

Brian Keating:

What do you make about these? The eyewitness reports, the, the kind of technical, you know, I what I wanna say, identification or examination. How do you look at it as a scientist? How sure do the scientists look at it?

Speaker:

Look. Obviously, the the right person to answer that question is, say, a David Spergel, someone who’s really looked at the data I’ve been on a committee to try to evaluate whether or not there’s anything to this stuff. But if you ask me on the outside, My sort of gut feeling is it’s all nonsense. Why do I say that? Well, for following a simple reason. You know, if An alien civilization had the capacity to travel across the galaxy, you know, interstellar distances. Do you really think that they’d be sort of hanging out so that a fighter pilot could spot them and, like, oh my god. And they try to get out of the way really quickly, and they just get caught on camera. I mean, it just seems so incredibly ludicrous to me.

Speaker:

And then when you think of it in the context of time scales, right, life on planet Earth evolved pretty quickly, Half a 1000000000 years after the Earth formed, couple 1000000000 years later, we start to get multicellular organisms. Intelligence then follows relatively quickly upon that. So let’s say 1,000,000,000 of years is the time scale for intelligence. Now that would suggest that if there are other intelligent beings out there, and they’d have to be pretty intelligent to be floating around in our atmosphere. They are likely At a time scale that differs from us by the order of a 1000000000 years. Right? It’s not as though the clock said go and evolution It started on planet Earth and planet company. Yeah. And on planet x simultaneously.

Speaker:

Like, the thing is planet x, if they’re able to do interstellar travel, they’re not just A 100 years ahead, they’re likely a 1000000000 years ahead. And a 1000000000 years ahead, just think about it. We’d be so uninteresting To them. Right? How often do you stop and get down on all fours and speak to ants in an anthill? You probably I don’t

Brian Keating:

wanna say. You don’t I don’t wanna say.

Speaker:

That’s right.

Brian Keating:

My hobbies.

Speaker:

Don’t do it often because it’s not interesting. And if other civilization is a 1000000000 years ahead of us

Brian Keating:

would disagree.

Speaker:

Well, that that’s right. That’s right. So there are a few. But, the point is there’s probably a 1000000000 year difference in our evolutionary development. And so The idea that they’d be just in a ship that kinda looks like our ships or in a flying saucer that kinda looks like the flying saucers that we imagine, No. They’d be a 1000000000 years ahead. They would be traveling in ways that we can’t even fathom. And so the idea that we’re just kind of catching them is so ludicrous to me.

Speaker:

And more pedestrian explanations that I’ve heard bandied about Weather satellites, interesting phenomena with light band bounces off. You know, those explanations seem to be Much more likely to me. And when you put it in the context of everything that I just said, it just kinda feels ludicrous.

Brian Keating:

Yeah. I mean, often you hear that these objects defy the laws of physics. Some, you know, one of the things I always point out was that, you know, if there were a military, you know, campaign to mock or sow discord or or do whatever, They would make things that would appear to violate the laws of physics. My favorite, you know, kind of, analog here is Luis Alvarez in World War 2 Had these, radar jamming and and spoofing mechanisms that as a allied plane get closer to the to the German, forces, It would actually broadcast weaker and weaker radar signals to it declining as the inverse 4th power as a reflected signal would. They thought, oh, this thing’s getting, claw farther and farther when it’s really getting closer and closer. Therefore, to the radar operator in Berlin, these things defy the laws of physics, But they had a perfectly now I wanted to distinguish between extraterrestrial intelligent and and crafts and life elsewhere in the universe. So I think Where where do you come down in that spectrum? Or are we alone first and foremost, and then the secondary question of, you know, can we actually learn from? Or and I would say No one would like them to be the aliens to be visiting us more than a physicist because we’d be learning so much about them if they don’t beat us or study, you know, focus with with a magnifying glass like I Used to do with my aunts, but but I’m not gonna talk about those crimes against anthology. So tell me, life in the universe.

Speaker:

Yeah. I mean, obviously, We we don’t know. And there’s this famous thing called the Drake equation, which I always recoil when people call it equation. It’s just an encapsulation of ignorance and a of ignorance and a variety of

Brian Keating:

air. Of Mars. Right.

Speaker:

Yeah. It’s you know? So look. As we now have Discover what? 5,000 plus exoplanets. We’re pretty convinced that planets circling stars is the norm. It’s not the exception. So there could be Hundreds of billions, if not trillions of planets in our own galaxy, and our galaxy is one of hundreds of billions. So there’s so many opportunities for life Of the sort that we’re familiar with to take hold on a planet someplace out there. So when you take that into account and note that we now have evidence for, You know, amino acids and, you know, these things these these molecules necessary for life seem to be relatively ubiquitous or not that hard for To to to synthesize and to to be on any of these other planets, we’ll we’ll know for sure pretty soon with the James Webb Space Telescope, Study the atmospheres of a variety of exoplanets.

Speaker:

How could you not say yes? I think it’s reasonably likely That there’s other life out there.

Brian Keating:

I take a slight contrarian viewpoint on all these things, not just in the extraterrestrial Tell as a guard against confirmation bias and of the sort that I would love for there to be extra, you know, to ask questions to see if you’re right about String theory

Speaker:

Now that wasn’t intelligence, I’m saying.

Brian Keating:

No. No. I just lied. Yeah. But I’m also a contrarian and a pessimist, and a minimalist when it comes to even life. Because I say, like, what if I told you, Brian, one of those exoplanets, I I just heard, you know, from one of my friends, and you can’t check your phone to see if I’m sure or not, if I’m telling the truth or not. But, she told me that actually there’s a planet, and there’s a binary planet system. It’s it’s it’s near a g type, yellow subdwarf, just like our sun.

Brian Keating:

And one of those they’re both in the habitable zone, these 2 planets, different orbits, slightly different orbits, so they don’t interact gravitationally. But, one of them is teeming with life. It has life in every extremophilic location you could possibly imagine, and we don’t know yet because the James Webb has, you know, gotta Tilt over and look at it or what have you, and actually see if there’s, you know, there’s city lights on this one planet. And I said, what do you think As a as a good Bayesian, I hope you are. Otherwise, we can’t be friends. No. But as a Bayesian, what would you say the probability is for the twin planet, the other planet? Maybe it’s in the same orbit, maybe Slightly outside the orbit, inhabitable zone, same composition. And so what would you say is a guess at the probability that there’s also At least single celled organisms on

Speaker:

that planet. It seems seems reasonable.

Brian Keating:

It’s pretty high. Right? So I would say, well, we have that example. It’s called Mars. Right? So Mars is in the habitable zone,

Speaker:

But Yeah. It’s also a dynamical question. Right? So, in fact, it could be that life on planet Earth originated On that because I mean, that you know? So so where I’m going. Yeah. Yeah. Okay. So so

Brian Keating:

the nonobservation of life right now, at least to to to our Understanding we there could be lava tubes and. Our friend up at Harvard thinks that he might find the alien skeletons, you know, scraped on the side of the cave, which I want you all to do out there. You know, the 4 words that are most important to humanity, please like and subscribe. But the fact that we have an observed, not a lack of evidence as As your friend of mine, you know, Carl Sagan used to say, it’s not evidence of black. But at the same token, we should be able to set some Bayesian, you know, Prior reduction based on a nonobservation of life anywhere in the maybe we’ll find it tomorrow. So I’m just saying there there there seems to be this prediction as Carl and Anjurian, who was also on my podcast a long time ago. Carl wasn’t, but Anne was. And their daughter Sasha was on, and it was wonderful.

Brian Keating:

But as they said in contact, They said, well, if there’s no life out there, it’s an awful waste of space. And I’ve been to Antarctica twice. I spent over a month of my life out there.

Speaker:

There once.

Brian Keating:

You have? You’ve been South Pole. No. I got it. Trump you. Okay. Fine. I got one thing over you, Brian. Come on.

Brian Keating:

You’re my avatar. But, not much life there. There’s more penguins than people, and even there aren’t that many penguins in Antarctica. There’s no life at the South Pole besides the people that are there. So just by saying there’s there’s Possibility of life like these exoplanets. No. I totally agree. Talking about the actual problem.

Brian Keating:

Okay.

Speaker:

Yeah. Yeah. No. I I I completely agree with that. And so that’s why I say it a little bit facetiously That, look, the ingredients seem to be out there, and there seems to be a lot of opportunity for the ingredients to take hold. But in detail, Even giving a different example, what if we find that life on Earth only took hold Because of this incredibly obscure phenomenon that we’ve yet to identify, and that phenomenon is so incredibly rare That it perhaps never happens anywhere even if you got a 100 trillion, you know, that this is something that’s at least possible. 10 to 25th? That’s right. That’s right.

Speaker:

So if

Brian Keating:

So if

Speaker:

it’s, you know, 10 to the minus 100 likely for this obscure process now we’ve not found evidence for any such obscure you know? But, you know, Until we synthesize life in the laboratory and we actually know, hey. All you need are these very basic, A little bit of, you know, electric current.

Brian Keating:

Right. A little The Lavalier manifold. Yeah.

Speaker:

That’d be a little bit too far. But, you know, if you can synthesize it in the laboratory And it’s really damn easy to do, then the likelihood of finding it elsewhere, I would much more on the side of saying, yeah, I’m now much more in the camp of this is likely to happen. But until we do that, no. It could be that we’re missing something deep.

Brian Keating:

Well, Brian, I wanna thank you so much. And I always conclude with your indulgence of a few more minutes with the following 4 Questions that are existential in origin, but together Just

Speaker:

as long as it’s not why is this night different from all the

Brian Keating:

it’s coming up. That’s coming up in the in the spring. We will touch upon something related to that. But if you wanna hear Brian’s answers to these, you have to subscribe to my mailing list. I have links to subscribe to, the World Science Festival and all Brian’s cool stuff. And, and that is atbriankeeting.com/list. And if you have a dotedu email address, because I love students and I wanna encourage students to develop their Communication skills and learn from these conversations. You’re guaranteed to win a meteorite, a chunk of 4,000,000,000 year old space schmutz from the pre, so pre Earth, environment of our solar system.

Brian Keating:

So that’s at briaynekeating.com/edu. So go over there if you wanna hear that and the Answers to Brian’s final 4 questions. But before we go, I just wanna give you a business tip, a a business proposal. Sure. And that’s, you ever see these things you can buy a star, Brian, you can get a star

Speaker:

in the Star named. Yeah. Yeah. I think I may have even done it once.

Brian Keating:

That’s what I was I was hoping you’d said. Yeah. Because I have an idea for you, and this is free of charge, and you feel free to use it. Why buy just star when you can buy a universe within the multiverse. That is the world universe registry In the multiverse, Brian Green, thank you so much for being on Into the Impossible podcast.

Speaker:

My pleasure. Thank you.