Into the Impossible With Brian Keating - Sean Carroll: Is the Universe Twisted? Limits on Lorentz Violation & other Screwy Ideas! (#084)

Episode Date: October 27, 2020

In 1990, Sean Carroll’s, George Field and Roman Jackiw wrote an epochal paper that had a tremendous impact on physics, and in particular, on me and my career as a young graduate student in the 1990���s. Recently, evidence for the parity violating effect from Cosmic Microwave Background observations by Planck was announced in Physical Review Letters: https://journals.aps.org/prl/accepted/b0070Yf9I0214c6835b00d89342658c8255c84496 Sean will discuss the background physics behind this effect and the implications for physics if the PRL is confirmed by upcoming polarimeters or otherwise convincing evidence is found. I will discuss some of the experimental challenges to making such a measurement and prospects for upcoming experiments such as CLASS, BICEP Array, SPT3G, Simons Array, ACT, LiteBIRD, Simons Observatory, and CMB Stage 4 to make a definitive, high confidence level claim. While you’re waiting for the livestream to start here is some homework 1) Subscribe to Sean’s Channel: https://www.youtube.com/channel/UCRhV1rWIpm_pU19bBm_2RXw?sub_confirmation=1 2) Enjoy this video from the SETI institute on cosmic birefringence, including a 1997 claim that Sean refuted, that I presented 4 years ago https://www.youtube.com/watch?v=QywRTlcocBE 3) Read the original paper by Carroll, Field, and Jackiw: https://www.researchgate.net/publication/13277928_Limits_on_a_Lorentz-_and_parity-violating_modification_of_electrodynamics 4) And, read the abstract of the current paper, accepted for publication in PRL: https://journals.aps.org/prl/accepted/b0070Yf9I0214c6835b00d89342658c8255c84496 5) Watch my review of Sean’s book, The Big Picture https://www.youtube.com/watch?v=Gg4t_snAPwY?sub_confirmation=1 6) Watch my interview with Sean about his latest book, Something Deeply Hidden: https://www.youtube.com/watch?v=BKEXbSe0hV0?sub_confirmation=1 Sean Michael Carroll (born October 5, 1966) is a theoretical physicist specializing in quantum mechanics, gravity, and cosmology. He is a research professor in the Walter Burke Institute for Theoretical Physics in the California Institute of Technology Department of Physics.[1] He has been a contributor to the physics blog Cosmic Variance, and has published in scientific journals such as Nature as well as other publications, including The New York Times, Sky & Telescope, and New Scientist. Brian Keating’s most popular Youtube Videos: Eric Weinstein: https://youtu.be/YjsPb3kBGnk?sub_confirmation=1 Jim Simons: https://youtu.be/6fr8XOtbPqM?sub_confirmation=1 Noam Chomsky: https://youtu.be/Iaz6JIxDh6Y?sub_confirmation=1 Sabine Hossenfelder: https://youtu.be/V6dMM2-X6nk?sub_confirmation=1 Sarah Scoles: https://youtu.be/apVKobWigMw Stephen Wolfram: https://youtu.be/nSAemRxzmXM Host Brian Keating: ‍♂️ Twitter at https://twitter.com/DrBrianKeating Instagram at https://instagram.com/ Learn more about your ad choices. Visit megaphone.fm/adchoices

Awesome. All right. Well, there's already a bunch of people out there on the intertubes to witness this once in a lifetime. Maybe it'll happen again next time there's some amazing announcement, amazing discovery. But I'm joined today by Sean M. Carroll, the California Institute of Technology, which I believe is a small technical college in L.A. Is that right? It is. Yeah, it's, you know, for vocational students who want to learn a trade. That's right. There's no better place to learn a trade, I suppose. Let me close up all these windows here. And you're reading me loud and clear, I hope. I can hear you.

Sounds good. Great. So, hopefully people out there are watching, and it is a treat to welcome none other than Sean Carroll, Professor Dr. Sean Carroll of the California Institute of Technology, who has been a great influence on me and many other scientists throughout the years. And one of the things that he is best known for in the outside of scientific communication, as many books, is that he is one of the originators of a modification to none other than the Maxwell's equations of electromagnetism that I find quite, quite intriguing.

And it's something that I thought of no one better to speak to than Sean about this claimed potential evidence for possible discovery of what is known as cosmic. biorefringence which would be sort of a mysterious discovery if confirmed let me make sure that sean is being shown yes he is and here i am i'm brian keating you know what i look like but but it's a pleasure to bring you this live today stream and there's a lot of people in the chat room already asking questions i encourage you to ask questions in the chat and we'll try to get to them and sean is joining us from his laboratory you know when i came to visit you last time you'll only had Richard Feynman's desk. How'd you get this, a resplendent laboratory, Sean?

You thought I was a theorist, but no, no. This is, you know, I have my secret experiments. I don't want to tell anyone, any of the details. You know, the world isn't quite ready for them yet. It's another talent that Sean has that only now are we privy to. So, Sean, I put together some slides, which people can access if they go to my website under blog. So I'll put that in the chat room right now. People can go. there and get show notes just look for the Sean Carroll episode that is listed there I run a website which features links to many interviews including ones like this

which you can find I'll put this also in the chat room on the on the actual internet on the actual YouTube video make that a public comment so here in the chat you'll find the link to the PowerPoint under I believe it's under bullet point number seven. I'll give people a chance to do that. But I'm going to be sharing the screen, so you don't necessarily even need the PowerPoint to follow along, but I thought it would be fun for us to talk over something

while we're discussing this monumental discovery, potential discovery, I should say, and we'll couch that in the appropriate gravitas as we go on. So here is a slide. I'm going to start off with a history behind this, how I came to set this meeting up with Sean. And that was because I saw an abstract for a paper entitled Limits on New Extraction of Cosmic Birofringens from the Planck 2018 polarization data.

And then this may not sound as stupendously important and full of intrigue as both Sean and I found it. But the key sentence is shown here where it says that this beta, which we'll talk about what that means, is a number, as an angle that the authors, Mir Mari and Ijiro Komatsu, discovered had a value which is inconsistent with zero.

So it says beta equals zero is excluded at 99.2% confidence limit. That's what the CL stands for. So they've increased the precision on this, and they've improved the accuracy too. And maybe we'll talk about the distinction between those two. Now, today, if you go to this link, you can download the PowerPoint, the links are all clickable. If you click on this link, you'll find abstract not found,

which is kind of unusual for such a thing to happen. I'm not sure what it means or why that did take place, but nevertheless, it is no longer available, so you'll have to take my word for it. I can actually, I do have a screenshot of the original abstract, which is save for posterity. I can share that later on if people are interested. But really, this made me want to talk to Sean because it is the anniversary of something very important to us. So on the third slide, I've got a picture that shows Galileo on the left and also wishing a happy 30th birthday to Carol Field and Jakhev.

I think that's how you say it, right, Sean, Jaquiv. And this is on a paper that Sean wrote while he was at the Harvard-Smithsonian Center for Astrophysics. That's where you got your Ph.D., right? That's right. This was my first ever referee publication. And it is enjoying its 30th anniversary. And not only that, it is enjoying a bountiful harvest of the currency in which scientists like Sean and myself traffic, which is citations.

How many citations does this now have? You received over 1,000. I don't know exactly how many as of today. I really have no idea, but it is over 1,000. I only know it's over 1,000 because Inspired tweets out. when a paper gets over a thousand citations. So I hadn't been keeping track until then. I think behind you, I don't know if that's true,

because behind you, I see a hit counter, a citation counter in the laboratory. It's real-time updating. Wow, that's amazing. Good, I've got to get one of those from my, you know, 100 citations that I have. So getting back to the paper, the interesting thing that, to me,

I can't notice the date without thinking about Galileo, because you published this on Galileo's 4206, anniversary, and that's very fitting because Galileo was one of the first people to talk about the concept of relativity. I believe he might have been the first, right, Sean? We certainly attribute it to him. I'm always a little careful when we talk about historical things, because my knowledge of history is not exactly very good, and physicists certainly don't worry too much about getting the history right sometimes. That's right. But as you encourage me when I was writing my book, losing the Nobel Prize, we've got a picture of that, DeRigour. So I've always

right here you can't see this Sean but on my couch in my office I have four books that you've provided your encomium for including my book losing the Nobel Prize Leonard Miladnos your colleague up at Caltech Stephen Hawking's memoir of friendship and physics and the Cosmic Revolutionaries handbook these are books that I'm reading for upcoming podcast so Sean is prolific at writing his own books writing scientific papers and also writing blurbs which is just he's a quadruple thread or triple threat whenever we got up to it. But getting back to this paper, when this paper came out, it's kind of been a slow boil. I actually do have a list of kind of how often these things have been cited.

But I want to take us through the title. So it's not as attractive a title as something deeply hidden or the big picture. How'd you come up with the title? I always judge papers first and foremost by their title and their abstract. Like I said, you know, this is my first ever published, repert publication. So I was not the intellectual leader, really, of this effort. I did a lot of the, you know, graduate student grunt work, and I did my best to provide the ideas that I could.

The title might have been mine. Like, I do often become the person who ends up with the titles. But, you know, this paper itself, there's a long version and a short version. I'll tell you the short version of how this paper came to be, because I was a new grad student at Harvard in the astronomy department. I'm not an astronomer. No one thinks I'm an astronomer. What was I doing in the astronomy department?

Well, the answer is the physics department didn't let me in, and the astronomy department did. And so George Field was randomly assigned to me as an advisor, and George was a world-famous theorist of the interstellar and intergalactic medium, so something I literally no interest in at all. But he had sort of spent a long time as the founding director of the Harvard-Smithsonian Center for Astrophysics. And then he left that position and sort of was intellectually curious, looking for new things to do. So he got into particle physics and field theory. And he actually attended a summer school as a student, you know, at age 60-something. You know, he attended as a young particle physicist.

And Roman Chiquet was there giving lectures. And Roman at the time was very interested in electromagnetism, in three dimensions, that's three dimensions of space, right? Two dimensions of space, sorry, three dimensions of space time. So two dimensions of space, one dimension of time. And he gave these lectures on them and that that is the context in which this idea of Tern Simon's theory arises, named apart after our buddy Jim Simons. And George, bless his heart, you know, as the down-to-earth astrophysicist,

he's like, well, okay, but what about four-dimensional space time? Like what about where we live? We don't live in three-dimensional space time. What is the point of all that? And Roman was like, well, you can't do it in four-dimensional space-time. It would violate Lorentz invariance. So George's answer was, you know, okay, let's do that. And that's when they brought me in and we looked for, you know, if we were to do this.

And the reason why this paper has so many citations is because at the time, in 1989, 1990, the idea of violating Lorentzian variance was just anathema. Like, we knew that Lorenzian variance was right. So what's the point? But that's not a very scientific attitude. You know, a good scientist will say, well, if it's not right, how would we know? And this particular idea that we came up with was sort of the easiest and best way for Lorenz invariants to be wrong. There's some vector field that picks out a preferred reference frame in space time. And it's gauge invariant, but it's also detectable experimentally. And so that's what we said. You know, we said, look, if Lorenzen invariants were not true, here is a benign, innocent way to violate it, and here's how you would look for it. Here are the experimental tests you can do. And so let's take us through it, maybe take a step back. What does it mean to be gauge invariant?

What does it mean to be Lawrence invariant? What do those terms mean for those of us who may not be as expertly conversant as you? No, exactly. So modern physics relies very heavily on the idea of symmetries, right? And a symmetry sounds like a big, sophisticated mathematical concept. all it means is there's something you can do, some transformation you can make, some change of perspective that doesn't change the underlying physical phenomena. So the most obvious thing is if I measure, you know, the strength of gravity right here, and I walk over 10 paces to the left, I measure the strength of gravity, I'm going to get the same number, right? If I measured the charge of the electron, it's going to be the same number.

So that's invariance under translations through space. It doesn't matter where you do your experiment, and that's an example. of a symmetry. Gage invariance is another example of a symmetry that is specific to electromagnetism. It later got promoted to other nuclear forces, the strong nuclear force, the weak nuclear force, even gravity has a kind of gauge invariance. And it's more subtle than spatial translations because it's completely internal symmetry. It doesn't move you through space. It just takes the fields in your theory, the electromagnetic field, the electron, the proton, whatever, and changes them amongst themselves in a certain way. And it sounds all, like I said, very abstract and

mathy, but it's absolutely at the heart of modern physics. All these different symmetries highly constrain what you can do in terms of the laws of physics, what theories you can write down, what experiments you can do. So if anything, gauge invariance, which is at the heart of electromagnetism and so forth, is more sacred than Lorentz invariance. Lawrence invariance is, like you said, an outgrowth, sort of leveling up of Galileo's idea. Galileo said, it doesn't matter where you are, and also it doesn't matter how fast you're moving. If you're on a train and doing an experiment, you're going to get the same answer. Lorentz invariance is just the relativity version of that.

You know, Einstein and Lawrence and Fitzgerald and Pontgray, people like that, 100-some years ago, said it doesn't matter where you are, and it doesn't matter how fast you're moving, but the way in which it matters is more complicated than you thought. So that's Lorenz-in variance. And when we speak about Lagrangian, I don't want to get too detailed, but when we talk about Lagrangians, that's sort of the underlying generator of all things of interest to physicists, is it not?

That's right. What you do as a working theoretical physicist these days is you either invent or find the predictions of different theories, right? usually different quantum field theories, but maybe string theory or maybe some discrete theory, maybe different kinds of theories. So what does that mean? You have a theory. It means you have some stuff, some fields, some particles, whatever, and you also have some equations of motion. You have some mathematical way of talking about how that stuff changes over time. And that's what the Lagrangian gives you. Lagrangian is just a slick mathematical tool for generating the equations

of motion for your stuff. So you say when you propose a theory, here's the stuff, here's the Lagrangian, any first-year graduate student can now go ahead and get all the equations of motion. I say that because I was a first-year graduate student when I did that with these equations. But that's the everyday life

of a theoretical physicist these days, writing on Lagrangians and coming up with their consequences. And was George, did he end up being your PhD advisor? He did, yes. I worked also with people from MIT, Alan Guth and Eddie Fari But George and I wrote several papers together We are still collaborating today, 30 years later.

Wow. So many people talk to think that SS Churn was Jim Simon's PhD advisor, but they actually, if it had been the case, it wasn't Jim Simons had a different advisor at Berkeley. He came to Berkeley to work with Churn as a graduate student, but when he showed up,

he found that Churn was on sabbatical for a year and he had a different advisor. But as he talked about in my podcast with him a few months ago with Jim Simons, he said, basically, if he had shown up, he might not have ever created Shurn Simons theory because he would have been just this rube of a grad student. And by the time he was actually working as almost a postdoc after only two or three years in graduate school, getting his PhD, he had the imprimatur of great success and great ability in mathematics that he wouldn't have had as a first year newbie graduate student. So we all, we can never live up to our graduates, uh, graduate advisors expectations. But yeah, go ahead. Something I can mention is, you know, this idea of Tern Simons theory was what we called it at the time. Uh, obviously Tern and Simons were pure mathematicians.

They were doing topology. They were coming up with different complicated to mean near mortals ways of characterizing two and three dimensional topologies. And so Roman Chiqui, who thinks of himself as a mathematical physicist, He was one of the people who really, starting in the 1970s, realized that you could make physical systems that are in effect two-dimensional, sheets of paper or sheets of conductors or something like that. And he knew enough about the math to know that there were things that could happen

in two-dimensional space that just can't happen in three-dimensional space. So he borrowed this math idea from Chern and Simons into a physics. idea. And then George and I and Roman turned it into a three plus one dimensional physics idea. But by the time you get there, it's pretty far removed from what Chern and Simons actually did. And one of the questions I got at my PhD thesis defense was, do you think if you showed this to Jim Simons, he would recognize anything that you've done? Yeah. And at the time, I had to say, well, honestly, I don't know. I'm not completely sure. But now I know he would recognize it because of you. Yeah, well, that's true. And he always is asking me, you know, has my, has my Nobel Prize prospects looking. And we'll talk about that because that, of course, drives some of the, some of the excitement, not the Nobel Prize, but the stakes that are involved. And another person I'm showing now on the fourth slide, I think it is, is James Clerk Maxwell. Now, I wonder, you know, if old James were alive and able to comprehend what he's seeing here, would he really understand the first set of equations lays us out really, You talk about gauge and the norentz invariants or two symmetries of Maxwell's

electrodynamics that have come to dominate all fundamental physical theory. And I wonder if he would have recognized that. I mean, as far as I know, he still had sort of, again, sorry, apologies for getting back into history, but I can't resist these great scientists that we're talking about. You get into these different extensions of electromagnetism, but at its heart, it's really modifying this master equation, this Lagrangian, your equation five, by, the addition of this term, and the term has a very special force. Now, did this equation six, where you add this four vector, did that just come to you out of the blue? I mean, what inspires

you to, or your colleagues, you and your colleagues, to create such a thing that had never before been considered? Well, again, yeah. So you want to start with some idea that in this case came from pure math, came from turn and assignments. And they figured out a way to, they figured out what we now call a topological invariant of three manifolds. So what that means is you have some complicated mathematical thing, which is three-dimensional. So locally, it has three dimensions. There's an up-down, left, right, forward, backward, but maybe it can wrap around itself, like there are donut holes and boundaries or whatever. And the ongoing program of mathematical topologists is to say, how do you know if two mathematical shapes are the same, if you can deform them into each other?

And there's no algorithm for answering that question, right? So what you can do instead is say, well, here are two things I can calculate about these different spaces that would be the same if they were deformable into each other. So like the dimensionality of a space is a topological invariant, okay? And I encourage people to check out. I did a series of videos, the biggest ideas in the universe. I do a whole video on geometry and topology where I talk about this stuff. But anyway, their topological invariant was specific to three dimensions. It's not meant, in fact, odd numbered dimensions more generally.

It's not meant to work in four dimensions. So our equation six, no one else had ever written down before, even Chern and Simons. This was our four-dimensional version of what something like a Chern-Simon's term would look like. And the important thing about it, even if you don't know anything about Lagrangians or physics at all, If you zoom in and see the very first thing that appears there, after the minus one-half, there's a P-alpha. And that P-alpha represents a vector in space-time that picks out a preferred direction. That's why it violates Lorentz-in-varyance. If Lorentz-in-varyance says, there are no preferred directions in space, there are no preferred velocities, et cetera.

This picks out a preferred direction. And that direction is the time axis, correct? Or the axis connecting? We assumed it was, but you don't have to assume that. We met our lives easy. The paper was long enough and expected enough as it was. What's so interesting about this paper is that you actually not only propose a new modification to one of the most, if not the most sacrosanct, fundamental theories of nature, namely Maxwellian Electrodynamics, but you also subject it to test, observational tests. And we're going to get into that because obviously the subject today is the claimed extraction of the,

this very effect, reproducing a type of special rotation in the cosmic microwave background polarization axis, linear polarization axis, that I want to discuss. But you, you know, the thing that really speaks to me is that you included not only some the speculative theory, but also the potentiality for testing it with existing data that you had access to at that time. So the, I want to just get briefly into why these types of measurements are hard to do in actually how we experimental, simple experimentalists go about trying to measure these things and why. Of course, one of the main goals in cosmology is to detect perhaps the imprint of primordial gravitational waves produced by an expansionary period that we call inflation. And you've worked on this as well and you've worked on an allied subject related to dark energy and accelerating, universe. But I wonder, you know, if we comment on here, I'm showing a slide that I borrowed

from Professor Matt Mews and the Cal State system. He has this beautiful diagram with kind of these blocks that my kids love to put together. Well, one likes to put it together and the other one breaks it, so it's kind of a symbiotic relationship. But he's declaring here there's a theory of everything that underpins all of reality. And it is supporting bricks that are labeled quantum mechanics, Lorentz symmetry and curved space time. Those then feed into the standard model of particle physics and general relativity. And then those support Newton's laws, classical dynamics, electromagnetism, atoms, classical cosmology, Newtonian gravity. But his point is that if you perturb the system on the next slide, you get something really wacky. That if you break Lorentz symmetry, you actually will have repercussions downstream. Namely, you'll be able to see. effects in the atomic world in electromagnetism, cosmology, and gravity. So the first thing I want to get into that some are asking in the chat room, what is your feeling about a theory of everything? Does such a thing have to exist? I've wondered off, and I've never asked you this. I had a series of

webinars over the summer with eminent physicist Lee Smollin, Sabine Hossensfelder, Eric Weinstein, Max Tagmark, Lisa Randall, and others. Do you think there's a need, do we need, a theory of everything, Sean? Well, there is a theory of everything. The universe does something. Whatever the universe is doing, that's the theory of everything. The question is, can we human beings find a version of that theory of everything that we can understand and that covers all the bases?

I think probably, but I don't know, we'll have to find out. So one argument, you know, I haven't used this on you because we haven't spoken since December, when we were actually in person in the travel district of Los Angeles International Airport. that was great and yeah we did a conversation on something deeply hidden that was wonderful you can find a link to it in my back catalog and we also have links to your YouTube channel as well and to your books but one of the things I've been asking lately is in what sense do we need we talk about unifying gravity with quantum mechanics but there's no well you don't believe in God but there's no letter from

you know some deity that says gravity and quantum mechanics have to be unified and then I always hear well, at the center of a black hole or at the Big Bang, there was a singularity, and you can't have a singularity without a quantum theory of gravity. What if there are no singularities, first of all? Would you still say we need a theory of quantum gravity? I mean, of course we need a theory of quantum gravity. There's nothing to do with singularities or black holes. Our current theory of gravity says, if you have some energy or mass right here, it gives rise to a gravitational field of the following form. Quantum, mechanic says, I can take that energy or mass and put it in a superposition of being here and being there. Okay. So that superposition causes some kind of gravitational field. What kind of gravitational field does it cause? We need a theory of quantum gravity to answer that. And some are asking you to do something very dangerous. Dallas here, I'll put up his comment. he's asking you to comment on the theories of everything of a past guest on the show, including Stephen Wolfram, Eric Weinstein, and Max Tagmark.

Would you take that challenge? Could you comment on why is there this proliferation? I don't really agree with. I encourage people to check out my podcast conversation with him on the Mindscape podcast. You know, it's good to be ambitious, but it's better to be right. So most ambitious ideas, including even observational tests like we're going to talk about later, are going to be wrong. You've got to be able to deal with that. Yeah.

So I have a guest coming up in a few weeks, Nima, Arkani Ahmed, of the Institute for Advanced Studies. And he's famous for saying things like, you know, it's very hard to break the standard model. I mean, it's very hard to do what I'm depicting here. Matt Mews is depicting here. But let's talk about that more. So, first of all, Lorenzen Variants, I'm just summarizing what you said earlier. the symmetry under various translations, rotations, and boost. It's implicitly assumed within special relativity in GR.

It's basically a foundational aspect component of the standard model of particle physics and beyond. And so, therefore, breaking it would be quite revolutionary. Another thing that Carol Jakee Field effect would manifest is in parity violation. Can you comment on what is parity violation? And who cares if it's violated? Can we all just get along with two hands that don't fit in the same glove? Well, parity is violated in particle physics, so it's not that surprising. And by the way, let me mention that even though Lorentzian variance is absolutely a pillar of modern physics,

one of the reasons why our paper was popular is because we violated in a very benign, innocent way. We violate in a way that doesn't make everything else break. It's still local quantum field theory, you know, it's still obeying the rules that we're all set up with. It just picks out a preferred reference frame in the universe, which is certainly interesting, but it's not likely to start from scratch with quantum mechanics and space time and all of that. Parity is a particular subset in some sense of Lorenton variance, which says you can take a system that has some shape, right, some orientation, and you flip its orientation. So if you have a set of vectors that are perpendicular to each other, you can sort of flip them so the other way around. I can't do it with my hand. I go left hand.

There you go. It's the difference between this and this, okay? Left-handed and right-handed. That is the actual difference. Sometimes people say it's as if you hold a mirror up to something. And if you think about particle physics, right? If you think about two particles bumping into each other and interacting and going off their own way, it's the most natural thing in the world to think that if you have an interaction that happens,

with a certain probability because of the rules of quantum mechanics. And all you do is ask about the same interaction, but in a mirror, it should have the same probability. It should be completely invariant under that, right? And so it was big Nobel Prize winning stuff when in the 19, I think it was in the 1960s, they showed that, no, actually, parity is not an exact symmetry of nature. The weak interactions of particle physics violate parity. Gravity and the strong interactions and electromagnetism all satisfied parity.

but the weak interactions violated. Isn't it possible, though, that gravity could violate it in the sense that you added a term to the Einstein tensor that's not unlike your term, that you would get chiral gravitational waves that would, in theory, or we could never test it maybe, but some including Lee Smollin, Stefan Alexander, et cetera, have thought about if there is a theory of everything, all the forces are unified. Gravity has to, at some point in the history of the universe, have chirality of parity violation. What do you make of such conjectures like that?

So you said two things. One thing is, isn't it possible that? And the answer is always yes. Any respectable physicist will always say, yes, it's possible. We don't know what the fundamental theory of everything is, like you said. So sure, it's possible. But then you said, you know, doesn't it have to be that gravity violates chirality river? No, it doesn't have to be like that. This is where we should be humble. We just don't know. That's why this kind of exploration is important, because we don't know ahead of time how these things work.

We should hypothesize that maybe they work and then go look for their experimental effect. So let's do a counterfactual Godankan experiment to throw a lot of scrabble words in there. So imagine that the weak nuclear force did obey parity. And just somebody told you that in 1989, you know, right? you're a bushy-eyed, bright-eyed graduate student. There's no parity violation in nature at all, Sean. Would you still write this paper?

In other words, does not the existence of parity violation in the weak sector suggests that there could, as again, possible arise, a violation in a lecture week or in electromagnetism solo? Yeah, no, absolutely. I mean, physicists are people, too. And when you think about different hypothetical scenarios that we haven't tested yet, different people are going to give different credences to them. Some ideas they're going to think are very reasonable, very probable, this is a good thing,

let's go look for it. Other ideas, even though they're also speculative, and we're not sure yet, they're going to say, I'm not even going to bother looking for that. So there's no question that, you know, we discovered both that parity was violated, and then we discovered the time reversal symmetry was violated, another Nobel Prize winning effort. So by now we're used to these simeastern. breaking just a little bit. And you know, like I said,

Lorenz invariants and these sort of orientation flipping symmetries are not even as fundamental as gauge invariance is. So maybe we shouldn't be surprised if these symmetries are broken at a fundamental level. I mean, I'm absolutely a big believer that quantum gravity might very well give rise to violations of Lorentz invariants.

Other people have investigated this idea. But it's one of the very, very few hands experimentally that we might have on quantum gravity, so we should take that super duper seriously. And then of the three discrete, there are three discrete symmetries in which you can invert a parameter or binary parameter plus and minus and charge in and parity left to right. And then in time, is there an analog of this carol effect, et cetera, in terms of time reversal symmetry being violated as the sub, as a subclass of Lorentz and variance violation? Well, like you say, there are these three symmetries.

There's parity, which is the mirror, time reversal, forward and backward in time. There's charge conjugation, which basically takes matter and anti-matter and flips them into each other. So we've detected violations of P and C and C-P and T and all these different things, but the combination, C-P-T, where you take an experiment, pull up at the mirror, run it backward in time, and flip all the particles to anti-particles, that seems to be like a good symmetry of nature. In fact, there's a theorem, the C-P-T theorem, which says that under very general assumptions,

C-PT has to be a symmetry of nature. True confession time, we didn't even realize when we wrote this paper in 1990 that our theory violates C-PT, which it does. And the reason... So, you know, once you... This is an example of the diagrams you showed.

Once you break something a little bit, there are downstream effects of other people, other things breaking that depended on what you started with. So Mark Ghiadia, I think I'm mangling that name, Max to maximum extent. He or she is asking, wouldn't the many worlds interpretation be a theory of everything? It's a different kind of thing because we have a technical definition of what we mean by a theory of everything. It's not a theory of everything is not just a theory of the whole universe. It's a complete theory of the whole universe at the fundamental microscopic level. So something like the many worlds formulation of quantum mechanics is a paradigm.

It's a way of saying this is how quantum mechanics works. But it's not a specific theory, right? Quantum electromagnetism, the standard model of particle physics, you know, a qubit in a quantum computer or something like that. These are specific physical models. All of them can be described within many world's interpretation of quantum mechanics. When physicists say that we're looking for a theory of everything, we want the specific model that describes the actual world down deep into its bones, and maybe or maybe not, that'll be part of the many world's interpretation of quantum mechanics.

So I want to turn back to our slides now. There's a picture of Jim Simons, for those of you playing at home. Let me get that up here. So this is the term that you added that we spoke about earlier. So you've already nicely described how that is added. I want to point out that this is not the first time that such a claim has been made, even in the context of CMB results. We're going to talk about an earlier violation detection claim in the late 1990s,

which got me extremely excited as a graduate student, that you actually played a role in debunking. And I want to get to why I believe that shows almost a heroic. level of scientific integrity. I've spoken on Eric Weinstein's podcast about you specifically being illustrative of the way a good scientist works his or her best to avoid confirmation bias and how some of the great scientist in history from Galileo to Einstein fell victim to it. So I always say it's too bad. They could have had good careers. But I want to take us back to August 2009 when a claim was made of a 3-Sigma detection of C-PT violation

using a churn-Simon's-like violation, the exact same term that you included in 1990. So this was by Zia, Lee, and Zhang. They're all friends of mine. And they were basically analyzing data from the Bicep W-Map and Boomerang Cmb's polarimeters, and using those data to control. instruct a very high confidence, several sigma detection, 3 sigma, which is higher than the current paper under discussion that we're talking about. And as I always joke, one of my late

colleagues used to say, you know, at 3 sigma, you can come and give a seminar, you know, at 5 sigma, you know, they'll pay for the seminar and at, you know, 7 sigma you can go to Stockholm. But, you know, sometimes those go away too, by the way. But looking at this paper, this really set me off on a campaign with one of my graduate students, John Kaufman, who is now a PhD out in Boston area. And we started looking at cosmic biorefringence of the Carroll variety and how it be manifest. So the next slide shows cosmic byrofringence with basically what does it mean to exhibit this effect? Assume nature has this added term in electromagnetic Lagrangian. You add a turn Simon's term, it would mean that the vacuum is birefringent. It would mean that a photon of the left

circular polarization state would travel slower or faster, depending on the sign of this effect, and the coupling. It would travel slower or faster such that when traversing cosmic distances, a rotation would accrue and a measurable rotation. The signature of polarization, and this is that your polarized sunglasses work, is that for every one physical rotation of the polarizer, my face will get darker and brighter for some this is great fun when I'm fully extinguished it'll get extinguished twice per physical rotation and this is relying on the fact that when you extinguish one when you select one polarization state and then you measure an orthogonal state you have zero photons transmitted and so what we do with our cm b polarimeters is we build detectors

that are intrinsically sensitive to one polarization state or the other and we essentially do this modulation where we rotate the polarizers with respect to one another in order to see if the incoming light is polarized and if so how now what the universe would exhibit uh if there were such a by a cp you know this Lorentz and parity violating property is that an initially polarized vertical photon would rotate and become slightly horizontal or rotated with respect to its original orientation state that's how you would detect it and it was claimed as i said back in in in 2009 based on Bicef 1 data, so the original Bicep data, half the subject of my book revolves around Bicep 1, the other half sort of Bicep 2, and why the stakes are so high when we do

polarimetry. And now I'm showing a cover of the New York Times. This is from April 18, 1997, and I'll show it on the screen here. Here we go. And it's a cover, and it shows, what I always think is interesting is that the New York Times is time translation invariant as well. So some of the same people that were on the headlines in 1997, including Newt Gingrich up here,

and Benjamin Netanyahu over here, they're still in the news, and Pataki sometimes hear about him. Anyway, it's interesting, but that's not what I want to draw your attention to. Down here, it's a subhead. It's on the front page of the New York Times. It says this side up may apply to the universe after all.

So I know that I remember where I was when I first saw this paper. And I want to get Sean, take us back to 1997. There's essentially a claim made using the properties of radio galaxies, which are distant astronomical objects known to have certain polarization properties. You are a freshly minted PhD, or you're a postdoc, or maybe you're a professor at Chicago. At an ITP. Yeah, so you're at the ITP. And you are coming across this paper.

which basically seems to have detected the very effect that you, now they don't cite your paper in the book in the New York Times, but it's effectively a detection of what you predicted. How did you feel as a person? Tell me what that felt like, that satisfaction that you might have had, must have had. Tell us what it felt like, and then as a physicist, and what happened next. How many discounts does USA Auto Insurance offer? Too many to say here.

Multi-vehicle discount. Safe driver discount. New vehicle discount. Storage discount. How many discounts will you stack up? Tap the banner or visit usaa.com slash auto discounts. Restrictions apply. So this is, you know, part of what I did

that original 1990 paper was what we were doing was looking at radio galaxies. So radio galaxies often have these long elongated jets, right? There's a black hole at the center spewing off matter in some direction. And what happens is that the matter gets spewed off, it stretches magnetic fields along with it. And so these magnetic fields, you know where they're aligned.

They're aligned along the jet. You can test this experimentally, but it's the most obvious guess also. And what that means is that electrons swirl around perpendicular to the magnetic field. They give off radiation that radio telescopes can detect. So if you know what a radio galaxy is and does, you predict with very, very high confidence that the polarization of light from the radio galaxy will be perpendicular. to the jet because that's what the electrons are doing. They're moving around perpendicular to where the jet is.

And so what George basically realized George Field was that, you know, if you collected a bunch of radio galaxies with red shifts and polarizations and you and you use what we call the position angle, where exactly the jet was on the sky, an eager young graduate student could type all that in. This, by the way, was the days when you had to like photocopy papers and then type in the data. Okay, so that was me. And then make plots of what it was true, that in fact the polarization was perpendicular to the jet.

And if we had this by-refringence effect, it would all be rotated a little bit, and it would be rotated more the further away from us you were. So we looked for that and we found no, there was no observable effect. We put an upper limit. There was not very much rotation, if any, in the polarization. And then, yes, seven years later,

the front page of the New York Times says someone has discovered it. Look, to be honest, my immediate response was, that's wrong. There was no time, I did not get any moment of satisfaction where I said, oh, my goodness, they found something. And I'll tell you the reason why. It's because in the New York Times article, they mentioned that the researchers used 160 radio galaxies. And I remembered, I typed in 160 radio galaxies. So they weren't using different data or better to.

data than me. They were using the data that I had typed in. I didn't collect any of it. That was collected by real astronomers, not me. But I knew that our data had any observable effect in it, so I knew that they were wrong. And I'll tell you why they're wrong. And I feel like, you know, dancing on the grave a little bit, because they were so wrong, it's kind of, it's kind of funny, almost. For some reason, they thought that the polarization of the radiation should be paralleled to the radio galaxy, not perpendicular to it. And so the problem with that is, of course, polarization is only defined plus or minus 180 degrees because the electric field goes up and down.

So it's not like it's defined this way or that way. Right. 180 degrees gives you the same answer, right? So how do you know what the polarization is? You have to resolve it somehow. And what they did was they said, well, in one half of the sky, will assume the angles between 0 and 180. And in the other half of the sky,

we'll assume it's between 0 and minus 180. Now, you and I know that it's actually 90 all the time. So what they found was that in one half of the sky, it was rotated by 90 degrees, and the other half of the sky was rotated the other way by 90 degrees. But that's the same rotation. It's not any different. So they just made a conceptual error.

It was not like they made an analysis mistake or anything like that. George and I actually George emailed me he said like you should look at the New York Helm so I said yeah yeah and then he emailed me again he said no no you really should look at it and I did and literally over the weekend you know we wrote a paper saying here's why it's wrong yeah well you have a lot more control self-control stoicism than I do yeah I always thought when you after you explained it so I'm showing your paper from 1997 with the histogram distribution under the slide that says radio galaxy polarization

It was kind of like, you know, remember when he used to play chicken in high school, Sean? And you'd say, like, you go right and I'll go left. You know, that usually doesn't work out so well. So anybody who plays chicken, make sure not to heed that particular convention. But again, since this is one of my undergraduates, Kelsey Lund, put this slide together. The next view graph has a display of the number of publications mentioning cosmic biofritory. It starts with a lonely peak at 1990, and that's Sean's famous paper, and then it builds as a slow, you know, I wish my stock portfolio look like this. And it's really just gone up almost exponentially.

And the reason is I think the stakes in some sense couldn't be higher. I was joking, you know, earlier, if God in my case gave me a piece of paper and said, on this piece of paper, write down which do you want to detect primordial B modes from inflation or Lorentz invariant cosmic birengens, and churn simons type i would definitely choose the latter because i think many people assume that the former took place and it's almost a foregone conclusion that something like inflation if not inflation itself took place i mean i don't want to i don't know how much you want to get into it but um part of this resurgence was many of the astronomy buffs out there will recognize 1997 as the year before 1998 and in 1998 uh people discovered that the universe is accelerated

through something which we call dark energy. And, you know, sometimes good things come out of mistakes. And so even though I think that the Nolitan-Rolson paper was a mistake, it got me thinking, again, about cosmic biorefringents and things like that. And in 1998, I realized that rather than violating the Rensin variance with some vector that we just made up, you could ask, you know, is there an effect that dark energy could have on the polarization of background photons? And it's the same effect. And so I wrote a paper explaining that if dark energy exists and is dynamical, is quintessence,

you should expect to see some cosmological birefringence. And to my mind, that's a way better motivation than violating the Rensenberry. Yeah, I think that's your quintessence in the rest of the world paper. Is that, is that it? Right. Yeah. So moving on, there were many other detections that have come about since the measurements of non-zero rotation angle. but most of those we attribute in this paper with John Kaufman that I've linked here

this is basically the misapplication of the way that systematic errors propagate from experiment to experiment and really the lack thereof of an astronomical reference source for astronomical calibration of polarization angle the reason it's so hard and you and I have talked about this before a rotation of your detector by a minuscule amount can introduce the same type of effect that would masquerade as a real rotation of the C&B photons polarization state, leading you to misattribute a detection of cosmic biofringes. And so we work to great lengths to reduce this type of systematic error. The problem is the way to reduce a systematic error.

This is for the real cognizante, the biofringes in systematics. You can skip over that. But that a small rotation of your axis can be detrimental and, could be much larger and induce a signal far, far larger than the cosmic signals that are sought. And so we started thinking about, well, how could you calibrate your instrument's polarization angle? And it turns out, whereas for most astronomical sources, even in the CMB measurement, what the plank instrument did for its temperature calibration or the WMAP satellite's beach ball behind me is that they use, say, Jupiter. And Jupiter is a known blackbody. It has a known size

at a distance to the earth, et cetera, and therefore it's a very reliable absolute temperature calibration standard. But there is no what I call standard stick. There's no object that we know exactly what its orientation is. And so we cannot absolutely calibrate our polarization angles using this with the CMB as easily as we can calibrate the temperature response. So we go to great lengths to do this. And some of the different ways are shown here. But again, none of these are as standard a candle as is the measurement of CMB temperature and isotropy. So it's a great challenge to us, but again, the stakes are quite high. We've actually gone so far as to propose building a satellite, a Brad Johnson at the University of Virginia has proposed a satellite that would orbit the Earth,

not looking out at the CMB, but looking down at the Earth, spraying it with a calibration signal that we would use to measure our polarization angles against. So before we turn back to the paper and maybe just finish up with the most recent plank analysis and what's come of it, I want to point out there are many experiments that are seeking to measure the cosmic microwave backgrounds polarization, in particular looking for effects due to primordial perturbations, whether they be gravitational waves or even density perturbations, and using it as a probe of all the physics in the intervening universe and perhaps earlier prior to the epoch of decoupling. But some of them are shown here.

I think I got a fairly exhaustive list. But the comments I asked Ichi Rokamatsu and to come on this podcast with us, but he wanted to wait until some of these experiments returned data. I didn't have the heart to break it to him that many of these are not observing and won't be observing for many years due to...

Maybe he knew that. Maybe he did. But let's get back to the original claim, which is that this effect, this causing fire fringence effect, was measured with this extremely high level of confidence, 99.2% confidence. What does that mean when you hear such a number? How should we think about the interpretation? I mean, if I had a 99.2% chance of dying in a plane crash, the next commercial airline I took, I would not get on that plane. What do you think about this, this type of confidence level? How do you...

Yeah, be very clear, just so no one misunderstands, I think this result is probably going to go away. I think it's probably wrong if I were to bet right now, despite them saying it's a 0.2% of it going away, right? And that's because, you know, this confidence level, 99.8 or whatever it is, doesn't mean there's a 99.8% chance this is right. What it means is that if you did something like this over and over again many, many times,

you should not get a signal this large except for 0.2% of the time. So the signals should be smaller. But that fact hides a number of other facts. Number one, you're looking for lots of different things, right? So you're actually doing a lot of different things and you're going to get unlikely things. Someone wins the lottery, even though it's unlikely that you're going to win the lottery. Number two, you get more excited when you see a result than when you just see what exactly what you expected. So you're more likely to write a paper about it.

Number three, as you've already indicated, there are systematic effects. So there are effects that are not exactly random numbers. There can be hidden effects that push all of your errors in the same direction, and that can trick you into seeing something. And number four, most importantly, this would be such a big deal that you should be super-due. cautious about it no matter what okay so I think that it's very interesting very intriguing that they claim that there's some evidence here the confidence level even at 98 99.8 you want it to be way higher than that just as a numerical fact and also you want it to be verified by independent groups not

just by one telescope because anyone telescope can have a secret little mistake in it so it's not something that's going to be cleared up in the next couple weeks and so that's yeah that's very That's very good to hear that take from you. We have a question from Stuart Volkow, who's the producer of the Into the Impossible podcast. He's taking advantage of his proximity to me. Stewart's asking, what is Sean looking forward to that may come out of observations from the next generation instruments coming online like Vera Rubin Observatory? Obviously, Simon's Observatory.

Are there other probes that could get at this effect? You mentioned 130 radio galaxies back in 1990. Well, how many are there now? Are there other ways to get at cosmic biofringens besides the CMB? Yeah, well, in fact, the CMB was not even something we thought of. If you think about 1990, it's hard, you know, some of your viewers, I'm sure we're not born in 1990. It's pre-Cobie. That makes me very sad, but it's probably true.

We hadn't discovered the amisotropies in the cosmic microwave background in 1990. We knew that they were there. We knew that we had satellites in the sky that were going to look for them and hopefully find them. but we hadn't, I mean, the whole thing had been under theorized in some sense, you know. I'm sure Jim Peebles knew all of it, but the community as a whole was not nearly as informed about the meaningfulness of CMB and isotropies as they could have been. And so when George and Roman and I did it, we used radio galaxies, and that was more than good enough to show that the effect is going to be small if it's there at all.

When I wrote my paper about quintessence, they're, you know, unlike the, you know, unlike my paper with George and Roman where we just made something up, you know, no good reason for it to be there. You can make up whatever size effect you want and we put an upper limit on it. With the quintessence stuff, there is a target. There's a natural size for that effect to be. And I was tickled to see it was smaller than the current limits, but big enough to potentially be observable. That's why I got very excited about that particular effect. But these days, you know, we do, as you say, look at the CMB to do it. People soon figured out. That was something you could do. It's a more subtle analysis because you have to, you know, it's not like a radio galaxy which does look like a stick in the sky, right? You know, the CMB is a more complicated beast.

But also, you know, if you want to know what else I'm interested in, we all know there's something called the Hubble Tension. There's this purported disagreement between cosmological parameters as measured by the CNB, with the Planck, satellite, WMAP, etc. And the expansion rate of the universe as measured our local neighborhood, the Hubble constant. One of the possible explanations,

this tension between these different measurements is tricky because unlike the acceleration of the universe that we discovered in 1998, there's no obvious explanation. There's no obvious theory that would easily fit this particular discrepancy. So you kind of have to bend over backwards a little bit and you worry about it.

The joke that theorists say is that it's a experimental result that has not yet been confirmed by theory. And I think, I think who said, Eddington said never believe in experiment until it's confirmed by theory. There you go. But nevertheless, there are theories. People write down theories. You know, my friend and colleague, Mark Kameinkowski, had a theory, one of many theories to propose

to get rid of the Hubble tension, which is dark energy, but not now, an early period of dark energy before recombination, before the microwave background was formed. And that could also be a kind of dark energy that gives rise to bi-refringence in the cosmic microwave background. So even if we see the bi-repringence there, it's not necessarily the quintessence that I was talking about. It could be something more exotic. And so I don't have a target to shoot for in future experiments so much as I have a bigish morgous board of things I want to understand better. Parity violation, tensor modes

with gravitational waves, reconciling the Hubble tension. All these things are potential discovery vectors, and so we need to push forward on all of them. Yeah, that brings up kind of an allied point from an experimentalist point of view. In addition to the many flowers that will hopefully bloom, when we go to measure the primordial B modes, we get limits on this type of biorefringens for free. We get limits on things like axions, which I want to

conclude our conversation, just getting your take on that. But the other thing that we get that we know exists are called primordial magnetic fields. In other words, we know that magnetic fields exist in all-bound clusters of objects. There's a cluster that's a 10 megaparsecs across. It has a magnetic field that's been measured. But we don't have yet a measurement at truly cosmological distances that are not gravitationally collapsed. And so the theory is that some early time in the universe it could have been a seed field, perhaps a relic of a phase transition, et cetera.

But we have a lower limit and we have upper limits. And so what we try to do is experimentalists is converge the upper limit to the lower limit and hopefully result in a detection. And so that I see is a low risk. I see looking for, you know, if you were just building an experiment and your proposal was to look for cosmic biofringens only,

that probably shouldn't be funded. if you can get all this other cool stuff, the primordial perturbations from inflation, permanent magnetic fields, limits on evolution of dark energy, et cetera, I think it becomes very fruitful to pursue such things where you have guaranteed results in some sense. Similar with neutrino masses, and one of the comments is a question about dark matter, which I always say neutrinos are the only form of dark matter we know exist that have mass and actually don't interact other than weekly and gravitationally. So a person by the name of outsmoked is asking,

Hi, Sean, I wonder, why isn't dark matter mentioned in the formation of supermassive black holes? If we know that dark matter warps space, bend space, wouldn't it end up in a black hole in the end? So does dark matter, would dark matter be part of a black hole? Well, it might very well have something to do with it, but there's a good reason why, we think that ordinary matter, even though there's much less ordinary matter than dark matter, has an easier time forming black holes than dark matter does, namely that ordinary matter can stick together. So you get a bunch of ordinary matter, hydrogen atoms or whatever, and they run into each other, and they stick. You make a shockwave or a pancake or a bunch of stars or a black hole or whatever,

because ordinary matter dissipates. It gives off light and heat. It interacts electromagnetically. And so There's all these extra forces over and above gravity that allow ordinary matter to condense into very dense objects and eventually form black holes. Whereas dark matter, as we know this from the bullet cluster and other observations, you send two clouds of dark matter together. They just go right through each other. So there might be a lot of mass in them, but it's not high density mass. To squeeze the dark matter into a really tiny region of space is really, really hard. It just tends to go right through your fingers. And another candidate for the dark matter in some extent is the axiom.

I wonder, can you say something about axions that was coined, a term coined by Frank Wilczek, who's an upcoming guest on the podcast for his new book coming out early next year? I wonder, can you say something about that? And how is it an allied or is it an allied phenomena related to the Carroll Field and Jaquiv mechanism? Yeah, the Axion is a very promising dark matter candidate. It's becoming more and more promising every day, not because of anything that Axioms are doing, but because their biggest competitor

are something called weekly interacting massive particles, which we put a lot of effort into detecting and haven't detected yet. Okay, we could have detected weekly interacting massive particles yet. We haven't. We haven't yet crossed the threshold where we ruled them out by any means, But every time we could have detected it and we don't, their probability goes down and the probability of everything else goes up a little bit, right? So the axions are more popular now than it used to be. And like the quintessence that we talked about, the stuff that gives rise to biorefringens, the axiom is what we call a pseudo-scaler field.

If you do this parity transformation, take the axiom and hold it up to a mirror, it turns into opposite of what it was. In some, well, in some sense it's going to remain big for this discussion, but it's actually mathematically. very, very well defined. And what that means is axions interact with electromagnetism in exactly the same way as this quintessence field would interact. The difference is the quintessence field very, very slowly rolls down its potential so that over cosmological time, a photon builds up a polarization rotation that eventually we can observe, whereas an axon very rapidly oscillates back and forth. So there's no net effect whatsoever on the polarization. There's particle physics effects.

You can try to actually shoot a magnetic field or a photon. You can shoot a photon through a magnetic field and have it turn into an axiom or vice versa. Turn on a magnetic field, let axioms go through it and look for photons being produced. So it's a family cousin, but not exactly the same effect. Very good. I can't resist just asking you your thoughts on the recent awarding of the Nobel prize to Sir Roger Penrose to Andre Gess and to Renan and Gensel. What did you make of it? How do you react to it? It's sort of a unique prize in a sense, especially the component that went to Sir Roger.

And then the observation, it noticed it didn't say for a black hole discovery, did it? So what was your reaction to that, to that Nobel Prize? I mean, I think it's good Nobel Prize because it's good science that is being rewarded. I don't really follow. carefully enough what exactly the citation was or so forth. But we've all seen these movies that they made, of stars zipping around to some very massive, very dark object at the center of our galaxy. And I think this is one of those things that crept up on us, right?

You know, black holes have been understood since the 60s. We've had some evidence for them since the 70s. The evidence got a lot better when Gaines and Gensel did their observation. near the center of the galaxy, the evidence got even better when LIGO found gravitational waves from black holes, but LIGO already won the Nobel Prize, okay, so that's in there. So I think what happened was, you know, there's sort of a, it wasn't like a big phase transition so much as a gradual creeping up to the point where people said, well, we have enough evidence to say that, yes, black holes really exist, and here are these people who have observed them, they win the Nobel Prize. And then someone in the back of the room can say something like, well, that's the experiment. What about the theoretical side of things? And someone says, well, I guess, you know,

probably the best work theoretically on Black Hole's was Hawking and Penrose back in the 1960s. And Hawking is no longer with us. Penrose still is. So that's a very deserving Nobel Prize, although I was surprised that he got it. I would not have picked that. Yeah.

It was interesting. I mean, I think he's done a lot. He also has his own alternative cosmological models, which are nothing short of controversy. But yeah, I was certainly gratifying to see the recognition of this wonderful award and and just the excitement that it brings to astronomy, winning, racking up all this attention and accolades. Well, Sean, we've come to the end of the hour. I want to thank you so much and also refer people to your YouTube channel, which is easily accessed, your preposterous universe blog, your many books. one of which has been shown this all time, something deeply hidden, a phenomenal book.

I have an interview with Sean about that from back in December 2019, BC, before COVID. And I want to thank you for everything you do, both personally that you have helped me, the way that you provide a role model for physicists and how to react and act with integrity. As a scientist, your outreach, your communication skills, and your ability to eat almost any type of hot sauce, no matter what the skull will rate it. Never been invited on the hot ones. You know, that's a future goal for me. I'll see what I can do.

All right, Sean, be well. Say hi to Jennifer for us, and we wish you the best, and hopefully we'll have you back when these results are confirmed, if not sooner. I'll be too important. I won't come on your podcast anymore. Well, that hot sauce. I'll remember the days.

Bye, Sean. Thank you very much. Bye, everybody. Thank you so much for joining us on the Into the Impossible podcast, the special Sean Carroll. edition. You can find a few different things I've done with Sean in the past. Find his blog. Find him on Twitter. And you won't be disappointed. And especially thanks to the producer of the show,

Stuart Volkow, for helping arrange it and putting it together. That's all for now. Stay tuned for more upcoming, interesting, exciting analysis and news and interviews in the coming weeks with, as I said, Frank Wilcheck, Barry Barish and many other scientists. And I do want to put plug out for a live stream I'm going to be doing with Adam Reese, Wendy Friedman, Jan 11, and I'm forgetting who else. There's, oh, Professor Sarah Seeger of the, of MIT. We're doing a live stream to commemorate the 100th anniversary of the great debates in astronomy, which took place in 1920, the famous Curtis Shapley debate. That, that live stream will be on the evening of November 10th and we will do it in conjunction with the Wyoming Stargazing Association

which is an organization that I'm involved with that has access to half meter diameter size telescopes will be reviewing some of the Hubble space telescopes greatest hits because it's also the Hubble telescope's 30th anniversary 30th birthday these are just incredible milestones to reach both in our understanding of the size the scale the scope of our universe in the case of the Curtis Shappley debate, and also in the context of the Hubble telescope celebrating its anniversary. So who better to share it with than a bunch of friends looking at telescopes live on the air in the evening of a November 10th.

So stay tuned. Please subscribe to this channel and subscribe to the podcast version, The Into the Impossible podcast on Apple iTunes or Google Play. Please leave ratings and so forth. That's how we get more attention so we can get great guests like Sean on such short notice. is really such a treat and the many, many luminous intellects that we've had on. Just this past week, we had Emily Levec, professor of astronomy at the University of Washington, and in the next couple of weeks, we're going to have this stellar, outstanding cast of characters.

So please do subscribe to the Into the Impossible podcast to this YouTube channel. Leave a like, leave a notification. I don't know if he can leave a notification. Anyway, this has been a blast for me. Thanks to Sean. Thanks to all of you out there for your awesome questions. and please subscribe to my newsletter so you'll be the first to know whenever I do a live stream like this. Signing off, I am your fearful host in this time of pandemic podcast, Professor Brian Keating, University of California, San Diego.

Have an awesome weekend, everybody.