Into the Impossible With Brian Keating - Sean Carroll’s Biggest Ideas (#259)

Episode Date: September 20, 2022

Sean Carroll joins me to discuss his magnificent new book, The Biggest Ideas In the Universe. Sean is an American theoretical physicist and philosopher who specializes in quantum mechanics, gravity, and cosmology. He is the Homewood Professor of Natural Philosophy at Johns Hopkins University in Baltimore. 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. He is known for atheism, critique of theism and defense of naturalism. He has appeared on the History Channel's The Universe, Science Channel's Through the Wormhole with Morgan Freeman, Closer to Truth (broadcast on PBS), and Comedy Central's The Colbert Report. Carroll is the author of Spacetime And Geometry, a graduate-level textbook in general relativity, and has also recorded lectures for The Great Courses on cosmology, the physics of time and the Higgs boson. He is also the author of four other popular books: From Eternity to Here about the arrow of time, The Particle at the End of the Universe about the Higgs boson, The Big Picture: On the Origins of Life, Meaning, and the Universe Itself about ontology, and Something Deeply Hidden about the foundations of quantum mechanics. He began a podcast in 2018 called Mindscape, in which he interviews other experts and intellectuals coming from a variety of disciplines, including "[s]cience, society, philosophy, culture, arts and ideas" in general.He has also published a Youtube video series entitled "The Biggest Ideas in the Universe" which provides physics instruction at a popular-science level but with equations and a mathematical basis, rather than mere analogy. The series has become the basis of a new book series with the installment, "The Biggest Ideas in the Universe: Space, Time, and Motion". https://www.preposterousuniverse.com/ https://twitter.com/seanmcarroll Mindscape Podcast on Apple: https://bold.org/scholarships/mindscape/ Connect with me: 🏄‍♂️ Twitter: https://twitter.com/DrBrianKeating 📸 Instagram: https://instagram.com/DrBrianKeating  🔔 Subscribe https://www.youtube.com/DrBrianKeating?sub_confirmation=1 📝 Join my mailing list; just click here http://briankeating.com/list ✍️ Detailed Blog posts here: https://briankeating.com/blog.php 🎙️ Listen on audio-only platforms: https://briankeating.com/podcast   Join Shortform through my link Shortform.com/impossible and you’ll receive 5 days of unlimited access and an additional 20% discounted annual subscription! Subscribe to the Jordan Harbinger Show for amazing content from Apple’s best podcast of 2018! Can you do me a favor? Please leave a rating and review of my Podcast:  🎧 On Apple devices, click here, scroll down to the ratings and leave a 5 star rating and review The INTO THE IMPOSSIBLE Podcast. 🎙️On Spotify it’s here   🎧 On Audible it’s here Other ways to rate here: https://briankeating.com/podcast  Support the podcast on Patreon or become a Member on YouTube Learn more about your ad choices. Visit megaphone.fm/adchoices

Welcome friends to a fascinating episode of The Into the Impossible podcast. Today's episode features not other than my friend, Sean Carroll, the Homewood Professor of Natural Philosophy at Johns Hopkins University. Sean recently departed Southern California in Maryland's gain as our loss. But the reason I had him on is not only because he's a fascinating thinker, physicist, philosopher, and commentator, but also because he has a new book out. And whenever Sean comes out with a new book, I can't resist. But to host him, after all, he endorsed my first book,

losing the Nobel Prize with his Encomium. And it's quite a delight to have him back for the third or fourth time on the podcast. Last had him on right before the pandemic in 2019. And December 2019, if you can remember it, where you're in person. And the audio quality was even worse than it normally is remotely from Timbuktu. But this audio hopefully is much better. And you're going to enjoy it.

He has a very fine setup. He's upped his game as I've tried to up my game, and you'll find out some more tips on podcasting that he's learned about. But really, we're here to discuss his newest book and the project that he's embarked on to educate young people, both at the level of high school and approximately beginning college, all the way up through people that just want to know more about physics. And this book is a great guide to all those things. So if you're a new listener to my podcast into The Impossible Podcast, make sure you check out

Sean's as well called the Mindscape podcast. This particular episode covered a huge amount of ground. We even went from discussing alien life in the universe to his experience with psychedelic drugs and their effect on consciousness. We talked about the beauty and value of math, the most mysterious equations in the universe, why they're so fascinating. We talked about past guests on our shows, Nick Bostrom and Sir Roger Penrose and Sean's theories about each one of them, our thoughts about each one of them. Talked about many worlds interpretation. And, we talked about relativity. We couldn't resist discussing what I think is the most profound question in all of science right now, at least how can we get a computer to emulate the creativity,

the imagination? After all, I am the Associate Director of the Arthur C. Clark Center for human imagination, not for computer imagination, but could someday a computer replace me. So these are fascinating topics that we get into, and I hope you'll stay tuned. And also, don't forget to give Sean's channel and podcast a try. Any sufficiently advanced technology is indistinguishable from magic. December 2019, an event began that would change history forever. Sean Carroll and I were in person at Loyola Marymount University in Southern California. And after that, something else happened around the world.

I can't remember exactly what happened. But I'm told it was quite substantial. And that was on the occasion of Sean's previous book. called something, something deeply hidden. We'll have links to that up there. And since then, Sean, you were really the first, you know, honest to goodness guest on the Into the Impossible podcast in the new format that I've taken on where I do interviews

and I do explainer videos. And you have been somewhat of an inspiration with all the great content that you put out on your Mindscape podcast. We're going to talk about that. We're going to talk about your Mindscape Fellowship, your new fellowship program that you have cobbled together, which is quite substantial, $10,000. All I give away are like little meteorites,

but you give away fellowship, Sean. That's amazing. And we'll talk about much more, including this wonderful new book, which is out now as we release this today. Biggest ideas in the universe, space, time, and motion, I think. And I want to welcome you.

Welcome you back. It's too bad we're not in person. You have moved on. We'll talk about that in just a bit. How are you doing? Doing great. Just move from L.A. to Baltimore, already spent a few weeks visiting the Santa Fe Institute, getting ready to teach a class in physics and a class in philosophy in the fall, getting boxes unpacked, being kept off the streets overall. It's a good feeling. Yeah, it's really quite exceptional. And I ask my, I have a computer assistant here. Computer, who is Sean Carroll? According to Wikipedia, Sean Michael Carroll is an American theoretical physicist and philosopher who specializes 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 and an external professor at the Santa Fe Institute. Computer, stop. My device there needs to be updated, updated, etc. In fact, I'm going to punish it, Sean. What do you think is going to happen? I have that device plugged into a plug, which it can control. And I want to know if, and it knows that it controls itself. So I'm going to ask this device to turn itself off. What do you think it will do? Has it achieved general artificial intelligence and will it try to save its own life?

What do you think? Yes or no. Yeah, that's what I call a strange loop, I guess. That will probably, this, you're going to do the Keating test instead of the touring test. That's right. full of human, but the Keating test is, will you kill yourself? That's right. Computer, turn off the plug.

Oh, it didn't work. Computer, open the Pod Bay door. Computer, open the Pod Bay door. Maybe it is dead. I'm sorry, Dave. I'm afraid I can't do that. Oh, my God. Also, a nut-how, and we're not in space.

All right, fine. All right, my computer device friend is acting up. But I do want to get into some topics on interesting. tidbits like AI and great advances. I talk to your friend and mine, Nick Bostrom, this week. But I first want to start with where your new title is that my

device needs to upgrade its artificial intelligence. And that says a natural philosopher, the Homewood Professor of Natural Philosophy at the Johns Hopkins University. Not John Hopkins University, Johns Hopkins. I don't think I'll ever understand that. But I want to harken back

to a great philosopher, natural philosopher of the past, friend of the show, and that's Galileo Galilei, for those of you listening, I'm fingering a puppet with the visage of the great Galileo holding a telescope. And Galileo said many things to kind of upbraid philosophers, including once he looked at the Pleiades, he said, we have now discovered the nature of matter in the Milky Way itself. And the words of philosophers that have been vexed for many generations are destroyed by visible certainty. In other words, he was saying that just by looking through a telescope, you can prove a theory and these worthless philosophers have now been disabused of their prominence.

What do you make of this? Is this just an example of the tension between philosophers and physicists going back to the earliest days of civilization? Well, no, because there were no physicists at the time. The idea didn't exist. Galileo would have qualified himself as a natural philosopher at the time. It's just like you or me making fun of physicists, which sometimes we do because we don't always agree with our colleagues. So he was just saying, you know, all of us, my peer group, we're not doing as well as we should. There was a time before we had written down the scientific method or really thought a lot about rationalism versus idealism versus empiricism, you know, different ideas about how to approach knowledge.

And he was on the cutting edge of saying the best way to approach knowledge is to go out there and look at the world. And your previous book to the previous book, I guess your second book, the big picture really did cover a wide swath of topics like that. And I had the honor to review that for physics today. It was the centerfold of that particular edition way back when. And this is kind of in keeping with the tradition, as you say, that physicists really didn't make this artificial distinction between philosophy. Why do you think, let me ask it this way,

Do you think that not approaching philosophy or not having any training and maybe purely adversarial, not just making fun of our own group, the in-group, the physicist's group by other physicists, but that we do have this tension between philosophy or at least unidirectionally, maybe just physicist kind of tease philosophers? Is that to the detriment of our students? In other words, is part of your role there to recreate the kind of golden era where these things were not so disparate? Well, in part it is, but also there's a,

bigger picture in the sense that any academic within a field has a sort of loyalty and interest in their discipline and then a broader interest in intellectual endeavors more widely. And I think it's a tragedy that not just physicists, but many sets of academics, only like their own field. They will not really have the respect or interest in other fields. And that respect shows up as saying, for example, that I need to listen to people in other areas rather than thinking that I can just sit back and in 15 minutes figure out all the difficult problems in those fields. So that's something that physicists do with philosophy, but they also do it with economics or biology or atmospheric science or literature or math for that matter, right?

So my kind of physicist is the one who knows what they know and is interested in learning other things by actually talking to the people who do know and gaining some knowledge thereby. And so now I want to pivot to a new segment, new since you were on the show. And maybe I can get all your past covers and titles judged in this segment that I've come to call judging books by their covers. Something you're never supposed to do, right? That's the advice. But what else do you have to go on if you've never heard of Sean M. Carroll or his doppelganger, Sean, who's the other Sean Carroll? It's a biologist.

B for biology. That's right. So I want to take the viewers, listeners, through an exposition of how you came up with the title, the cover design, the subtitle, and what, if anything, is meant by, you know, Volume 1. Can you talk about the cover design, help us judge this book by its cover? Sure. You know, I came up with the title by a no especially rigorous process. The whole idea for the books, there will be three of them eventually, is a spinoff of a set of videos that I did. And the videos that I did were a spinoff of a little pandemic that hit us a couple years ago.

And when it became clear that we might be locking down and not going outside, many people in different ways ask themselves, you know, what can I do to make this unpleasant situation a little bit better for people, whether it's entertaining or educating or whatever it is. A friend of my- I started making scraps of my T-shirts and selling them as N95 masks. Yeah, that works. Made the world a little bit better.

A little bit something. A friend of mine, Lauren Gunderson, who's a playwright, started doing educational videos about playwriting on the Internet, and that gave me the idea that there's something I could do, namely educational videos about physics. But of course, there's many, many things about physics on the Internet, and you've contributed to some of them. So how can you be different and useful? And I thought that what I could do was just try to fill the gap between popular level discussions that I've contributed to also and textbook level discussions.

You know, a textbook basically assumes that you're going to be a professional. You're going to be doing this for years and you're just doing a little step, a little bite of the apple that's going to take you a lot longer to do. and you really need to be able to solve problem sets and things like that. Whereas the popular level treatments think that you're afraid of equations and you can't possibly look at them and you just need metaphors and analogies and visualizations. So there is something in between where you talk a little bit about the real equations, but not at a level where you're expecting anyone to become a professional physicist or even solve problems, at homework problems or anything like that.

You just want to understand the ideas. So that was the basis for the videos. And it was, I didn't have a lot of time to set it up because, you know, we were being locked down. I literally went out and bought a green screen and a video camera. And two days later, I was not allowed to go outside. So it was just in time. And I called them the biggest ideas in the universe. And it's not a great title.

Honestly, it's fine. It's okay. But it's very unfortunate because I also have a previous book called The Big Picture and that's kind of confusing between those two. But so be it. You know, it was stuck there. And then when I pitched them as an idea for books, the publisher and I agreed that it just makes sense to use the same title because some people will know the videos and therefore they'll be interested in the books because they're very complimentary, although the videos were much more informal in slapdash. And the books, I'm careful and I make far fewer mistakes in the books than I did in the videos. And then the big issue was, okay, how many books?

I did 48 videos, you know, 24 videos and then 24 Q&A. follow-ups. My vision was one giant book. I was going to write a thousand-page book, and that would be the magnum opus of all the physics you need to know. So the publisher came back, said, how about we break it up into seven books? Because short books are very popular right now. And I said, no, that it would just, like, book three would make no sense, right?

I mean, it would be caught in the middle of a whole bunch of things. So we compromised on three books, and there's actually a pretty natural division. Book 1 is all about classical physics, up to and including relativity. Book 2 will be about quantum physics and quantum field theory. Book 3 will be about emergent phenomena, complexity, and the bigger macroscopic world. Now, I couldn't help when I first heard about what you were doing is reflect upon our mutual friend Lenny Suskin, past guest on the podcast, and his so-called theoretical minimum. For those that might be on the fence about whether to buy three versions, you know, three versions,

all three versions of this book or just two. You know, I should point out the audio version is read by Sean and the text versions are written by Sean. But you should buy all three. But I wonder what is the relationship between those wonderful books by Lenny and this particular series that you're envisioning? Yeah, I think there are basically only two books that are competitors to this series. One is the series by Lenny, the theoretical minimum. And then, of course, another previous podcast guest, Roger Penrose wrote The Road to Reality, where he really just goes a lot into the equations and so forth. And I think the differences are pretty clear.

I mean, Penrose is a genius, but he has his quirky idiosyncratic take on a lot of these issues. And it's not always necessarily the mainstream view. So it's his view and it's great and it's very worth learning. But it's a little bit different than what the average physicist would give you. So my goal is to really not in this particular set of books be speculative in any way. And in that sense, it's very different than my previous books. Most of my books try to present an argument. It's not just here's some pedagogy, here's some cool stuff.

It's like, here is something I think is true. Not everyone agrees. Let me explain the reasons why plus and minus. Whereas in the biggest ideas, I'm just going for the known classics, you know, the ideas that are accepted. will still be accepted a thousand years from now as useful to modern physics. So in that way, it's different than Penrose. Compared to Suskin, you know, it's a little bit more, my books are a little bit more explicitly meant for this purpose. You know, his books came out of more or less formal classes that he was teaching at Stanford.

Not to physics majors. He was teaching to a more general audience, but they're a little bit more traditional physics classes. They go through the steps in the usual order and they teach you how to diagonalize a matrix and whatever. And so it's a little bit, you know, it's a broadly aimed physics course, but it's still a standard physics course. Whereas what I can do, since I'm not pretending to be a course, so I'm not pretending to sort of march through the curriculum in any standard way, the first book has Einstein's equation in it and the short shield metric, you know, with all of the details. The second book will do the whole standard model of particle physics. You know, I can skip to the good stuff. So I think that's the fundamental difference between my books and Lenny's, but you should buy them all.

And Penrose is also. These are all great books. Yeah, we'll get to Penrose because he was a guest on the podcast just last week. We're recording this in August, but he was on for the occasion of his 91st birthday. And I know you've had him on your show as well. And the context of what we spoke about last week was his, you know, rather controversial notions about collapsing wave functions and I asked him a question on your behalf, and I want to get to that later. But I want to start where this particular book starts, which, as you say, is basically

with math, with basic foundations of calculus. And I found it very refreshing. Obviously, I know calculus for many years. But the distinction between, you know, just from seeing it from your perspective, and you know that my audience is the smartest audience in the universe. You have the title of second smartest. I know the mindscape audience. Where's the top two? Yeah. It's quite, quite erudite. But I have a lot of aspiring students, a lot of aspiring, you know, graduate students, non-traditional students, people that want to go back to school.

I just was honored to receive an award at my alma mater at Brown University called the Horace Mann Medal. And graduating in front of me or seeing it was Manfred Steiner, who received his PhD in theoretical physics with Brad Marston at age 89. He was actually 90 when he got his actual PhD because of COVID. What do you say when people say, I want to go back, you know, and do this in my second life, if I could do it again. I hear this a lot about people, you know, wanting to go back for their MBA or go back for their, you know, maybe even their law degree or their medical degree. Sometimes I

hear it about physicists, too. Is it as practical or impractical to do any one of those august professions as it is to do physics as a PhD and become a professional physicist? Well, I think I would actually argue for distinguishing or separate. the idea of getting a PhD and becoming a professional physicist. These are both two worthy things, but they're different things. And I think this is one of the shameful aspects of our current educational system is that we only let you in to do a PhD if we think you want to become a professor of physics. And then maybe 25% of the students will become professors of physics, right?

And the rest of them are just triaged out of the field. I think it's worth learning physics whether or not you're going to be. become a professional physicist. And I think that's really what gives me the opportunity in these books to do something different, because I'm not even pretending that you want to be a professional physicist. I'm just trying to teach you the ideas. You will not be able to solve for the procession of Mercury once you've read my book, but you will know what a light cone is, and you will know why there is gravitational deflection of light and gravitational redshift. You won't be able to compute it because you're not going to become a professional physicist, but you'll be able to

understand it. And I think that the idea of people understanding and appreciating and loving physics should be absolutely universal and free of whatever restrictions of age and current state of the world that you're in. Becoming a professional physicist is much, much harder because it's like becoming a professional NBA player, right? You know, there's a lot more people who want to be professional basketball players than who can hack it. And that's fine. It's not like it's a mistake of society that we don't have three million professional basketball players. players, right? This is the feature of the system that is not going to go away. Even if we did, we would still all be watching the best ones. And likewise, I don't know what the right number of professional physicists is, but I do know the right number of real physics lovers, people who appreciate and want to learn more about it, could be much larger than it is right now. So I want to push back with love and respect, as I always do. But on two things. One, I do think it's for professional aspiring physicists, because I, I've recommended this book or, you know, when it comes out, to aspiring high school students.

I've recommended Lenny's books, actually, to, you know, friend of the show, Eric Weinstein, his son Zev, wants to, you know, is basically rolled together, you know, a graduate level course in physics as a high schooler. And one of the books series, I recommended to him, was Lenny's book series, which I think are quite fabulous. And I think yours even distills things in an even more perhaps approachable fashion. So I think you can get this book if you're a high school student and you do want to aspire to get a glimpse of what you're going to learn for real, maybe in grad school, but at least see it before you even go to undergraduate. I mean, it starts with calculus. And I think it was probably intentional to do that. The other thing I want to push back on.

I need to push back with your pushback because you're not pushing back at all. I 100% agree with all of that. I mean, I would have been incredibly in love with this book when I was 15 years old. I mean, this would have been just absolute candy to me because it's the idea, at least the hope, the aspiration, is to be very, very accessible to people who do eventually want to become professional physicists, but they don't want to, you know, wait. I mean, a lot of people, people don't understand most people who graduate with bachelor's degrees in physics, probably even most people who graduate with PhDs have not taken a course in general relativity, right? So here is a one, you know, one volume book. book less than 300 pages where you can learn general relativity. You don't need to slug through all that stuff to get there.

And that's just something I think is very important to prospective professional physicists. But my point is not only to them. That is not the only target audience. Yeah. I mean, I think you're being a little overly charitable with Roger. I mean, I think it would be very difficult. I tried to read The Emperor's New Mind, as I told Roger, and he inspired me as a 15-year-old. I didn't understand any of it.

And it could have turned me off, but it didn't. And on the other hand, I think Lenny's book is, so Roger's book is wonderful, but it suffers from this fact that it's a lot of kind of invented or novel nomenclature and really thinking about it as a magician rather than as a teacher. Lenny's book is, I think, a little bit higher, you know, it is for sort of people in grad school. I mean, there were people in his lectures, as you know, that were, you know, PhD. It was like the Feynman lectures or something. There turned out to be, it would start off with undergrads and it would end up with faculty members. But the other way I want to push back again with respect is that you said, you know, you want to, there are too many, you know, there are, we don't need millions like, just like we don't need millions of NBA players. We don't need millions of physicists. And then I wonder, well, why are you doing this, this fellowship? Let's, let's go there. Because it's kind of, you know, I was joking with one of my kids. It's kind of like, I was telling, teaching him the definition of an attractive nuisance. Like, you're making this subject seems really appealing, really exciting. People are going to get into it. And then you're going to offer them a fellow. fellowship and really attract them to it.

If we have too many physicists, Sean, like, is there a danger in attracting more by having monetary rewards? So I'm kind of being tongue in cheek. But if you really believe there might be too many physicists, should we just reserve it for, you know, what is the purpose of the fellowship? Is it for underprivileged people? Is it for people, you know, from other backgrounds? What's the real focus of it?

And your words, you say, we don't need millions of businesses. Yeah. But I think, again, number one, you're mixing up learning a field with eventually becoming a professional in it. And number two, whatever the criteria and how many physicists we need, no one thinks that we need just rich, white people whose parents were professors to become physicists. And I think that knowing it myself, you know, even if you're fascinated with the subject matter, depending on your background, it can be very unclear how you would even go about becoming a professional or becoming educated in this area. There's a lot of pressure to just

earn a living, you know, make some money, be the first generation in your household, which went from lower middle class to upper middle class, right? And some kids out there are going to be in that position, and they're going to think, yeah, but what I really want to do is sort of understand cosmology or understand metaphysics or whatever it is. And it might be hard for them. You know, there's not a lot of money out there. And so the idea of this scholarship that I've started with bold.org. It's called the Minescape Big Picture Scholarship. And we're raising money to give up to, well, we're giving $10,000 to someone who is an undergraduate studying the biggest ideas, right? Studying philosophy and physics and mathematics,

or not and I should say, or, you know, one of those things. But there's plenty of people who want to become doctors and lawyers. And that is great. There's nothing wrong with that. but I'm aiming it at underrepresented groups in these less practical areas that I love so much myself. And anyone is willing to either apply if they're college undergraduates or donate to the scholarship fund. Because if we make enough donations, we can offer more than one donation or we can offer it next year or whatever we're going to do. Your summer starts now with Memorial Day deals at the Home Depot. It's time to fire up summer cookouts with the next grill, or burner gas grill on special buy for only $199.

And entertain all season with the Hampton Bay West Grove seven-piece outdoor dining set for only $499. This Memorial Day get low prices guaranteed at the Home Depot. While supplies, price invalid May 14th or May 27, U.S. only exclusions apply. See Home Depot.com slash price match for details. Yeah, and I want to talk about, you know, kind of your perspective now that you, I mean, your position at Caltech, you were advising students and so forth. now you're, you know, you're officially a professor, as I understand it, in terms of, you know, the typical responsibilities and rightfully suits you delightfully well. But I want to ask about,

you know, college seems to me to becoming more and more of what I call the academic hunger games. I mean, first year, like, fighting to get people, you know, to be seen in high school and get into these places. They brag about rejecting, you know, at, you know, one of my alma monitors, you know, 97% of the people that apply. These are like things that they brag about. And, you know, to what extent is it really becoming a luxury, a luxury brand? And these colleges should be maybe treated differently. And I know Bloomberg is given a lot to Hopkins and there's other ways that have made it more affordable. But it's still, I mean, I heard from your, you know, one of the places you used to work at MIT, they could turn away, they could accept like 10 more

classes worth of students based on quality alone. In other words, they're turning away. tremendous numbers of qualified applicants. What's going on here? Why is it that our discipline, being a professor, physics or whatever, really hasn't changed in thousand years, at least the last 50 years after, you know, a thousand years of basically having this model where you have the sage on a stage. As our mutual friend, David Kaiser says, you know, one guy is scratching with a rock on another piece of a rock and they're all looking up in rapt attention. our profession hasn't changed substantially, at least maybe in 100 years, but maybe a thousand years since the University of Bologna opened its doors in 1080. I wonder, you know, how many other

industries can survive like this? I mean, it's great we're doing outreach. We're doing, you know, demonstrations. I do kind of live stuff on my show. But, you know, you and I are kind of rare, and you inspired me to do it. So there's not like maybe that many people that you can inspire to actually do it that are faculty. I believe I should say that faculty have a moral obligation. to give back to the public in some way. But let's not talk about that. Education. What's wrong?

Maybe you don't think anything's wrong, but I feel like it's become a luxury brand that we kind of are proud of the fact that we turn away more, you know, 30 times more than we could substantially educate. Well, I think that there's a whole bunch of things going on here at once.

And the first thing I should say is, I am not a professional at thinking about how to improve the state of education. I'm a professional educator, but there are people who actually study how you can do it better. And there are people who think very hard about education policy and how we can make the flow of money more equitable, things like that. And I'm not such a person. So I'm just bloviating right now about how things should work, take it for what it is worth.

And I do think that there are things changing. I mean, here we are on a podcast, right, which couldn't have existed a hundred years ago. So there are videos, there are online courses. I always encourage people to take really good online courses and MOOCs and so forth. Wondrium makes courses. I'm doing yet another course with them. So there's more opportunities out there. But I think you're right pointing at the sort of standard issue higher education paradigm. There are flaws in it, absolutely.

You know, I used to be at the University of Chicago, which famously has always been a really good school. But when I was a kid, you know, I was looking at what universities did. to go to, it was not a high ranked school in the traditional rankings. And part of that was because they accepted a huge number of applicants percentage-wise. And the reason for that was just that no one would apply to the University of Chicago unless they were already really, really good and wanted to go to the University of Chicago. But that is not a way to get up there in the rankings. So they very explicitly invoked a new policy to get a whole bunch of people to apply

just so they could reject them. nothing changed about the university or student body, but they skyrocketed up the rankings. And that's gaming the system in a very transparent way. And well, why would it work? You know, why would people care about that? And a lot of this is questions for employers and parents and students. You know, why do they care what the ranking of your school is? I mean, I remember running into someone who was a young student who was going to go to law school. And I said, well, where do you want to go to law school? and they said, I don't care, just one of the top five schools, right? And, well, that just rubs me the wrong way.

It's not what it should be about. But then there's also issues of, you know, the how we pay for it, right? And there I think that things have changed a lot. I mean, you know, again, in my day, it seems that university educations are a lot more affordable than they are now. And a lot of it seems, and I say seems, because again, I'm not an expert here, it seems to me that universities have learned that they can make a lot of money by charging an exorbitant tuition, but then just letting all their students get loans to pay it back. So they're really sort of getting money from the future of their students, which is great for the university,

not so good for the students. And so I think that the student debt burden is enormous and really, really bad. If we lower it, you know, maybe universities will suffer a little bit and maybe they should suffer a little bit. I don't want them to suffer, but it's a weird system. And, you know, throw in also the fact that public support for public education has cratered. You know, states used to support their own state universities to a level they just don't anymore. And I think that California, for example, where you are at a state university, is probably better than most, but still not nearly as good as it used to be, right, in terms of affordability to the average student. So, And then you have the issue of, you know, what is the best pedagogical method?

Is it just, you know, one person at one end of a log and the other person at the other end talking to each other. What about flipped classrooms and active learning? You know, there's just a million issues that we could talk about, none of which I'm really an expert in. I mean, part of me is just a dinosaur. And I think that there's nothing better than a bunch of people sitting around a table talking. And, you know, one of them is the professor and some of them are the students. But they're all trying to learn a little bit. And that's what I'll be doing in both of my classes this fall.

So I love lecturing when it's appropriate. But a good seminar where we can all talk about things is really, to me, the pinnacle of the university experience. Yeah. It's right up there with the sabbatical. But no, I really, I tend to agree with you. And I actually think that, you know, in the case of at least private institutions, you know, the question of why are they tax exempt organizations? Why do they have to, why does, you know, Princeton or Stanford brag about, you know, having a $50 billion, dollar endowment that grew 30% or 15% during the global pandemic if they're not going to spend it.

And then they're still soliciting people like me for donations, you know, as alumni. And they have this vast network. You know, so you take out a loan to go there, the government slash your and you can't discharge it in bankruptcy. So these, you know, they operate kind of like hedge funds. I mean, that's their primary role as to is the sustenance of the entity. Here, you know, I always joke like, how do I distinguish what I do. at UCSD versus UCLA.

You know, do I know some special brand of physics? You know, do I know the fourth Newton's law? You know, is there some other thing I can add to the Uber of physics? No, absolutely. Harvard doesn't know more than Johns Hopkins or San Diego. So they tend to now distinguish it based on perks, you know, like this dorm, you know, on campus near my office as an ocean view. That's pretty nice.

Or there's a rock climbing wall. Or there's a gym. or there's a cafeteria with fresh sushi or whatever. So that seems to me to be getting really far away from sitting on a log and scratching rocks on other rocks to map out a picture. Yeah, I agree. There is a beauty to the old way of doing things. It did, you know, some things have just been successful for thousands of years and there's a

reason for it. But I do think things like virtual, you know, learning, augmented reality. I mean, you're a wonderful teacher, Sean, but if I got to sit down with Plato and, you know, and he was like sitting there in the room with me and or with Einstein, that would be pretty good. I actually got, you know, the collected works of Galileo. And for the first time with Carlo Revelli, your friend Carlo and others, we made an audio book called the dialogue on the two world systems where he and I narrate it with another Italian physicist. Carlo and Fabiola Giannese. Reads Galileo's introduction and Frank Wilcheck reads Einstein's introduction. But I started to think, Sean, well, now I've got a million words of Galileo. It takes 21 hours to listen to the whole darn thing. You know, well, what if I put it into GPT3? Would you get out a convincing, you know, simulacrum of Galileo? And if you did, could you use that in an educational framework?

Have you thought about, you know, where AI could go, where my handy device behind me could go in the future of education? Yeah. I mean, I think that we're nowhere close to anything like that. Of course, you could put a whole large corpus of any one person into GPT3 or any other AI program and get something out that would sound a lot like them because it is just their words slightly rearranged, right? I mean, that's not really very surprising to me. But then as soon as you start asking questions out of context, it's easy to see that it has no insight, it has no understanding. And I'm not someone who thinks that it couldn't have insider understanding, but the optimization problem that is being solved right now is for cheap tricks, is for things that look good and slick and will amaze you without having that deeper understanding.

So someday we'll have that deep understanding. That'll be great. And then everyone will have their personal physics tutor and that'll be wonderful. But it's not something that I'm worried about in terms of my own job security. Yes, my venal instincts are to make sure it doesn't horn in on my racket. But I want to turn then also kind of on the idea of where this book ends up, which is with Einsteinian gravity. And you do have an understanding of it. Yes, you go through the math.

You shouldn't under promise what you do in this book. It actually shows in a very detailed appendix. I checked all the math. I did all the. it's really fun and it's great to see the diagrams in this book. I don't know if you drew them or not. I know some of them you drew in real time on your video series on which this is based. But you end up with Einstein and I want to talk just pertinent to the conversation we just had about artificial intelligence. You know what Einstein called his happiest thought, Sean, do you remember?

It was the principle of equivalence. That's right. So you want to explain that for our audience? What did he actually say for the audience? That was his happiest thought. Well, you know, Einstein became famous in 1905, his miracle year. And one of the things he did there was special relativity. That's the theory that says, you know, there's no such thing as an absolute velocity except for the speed of light, which everybody agrees on, right? And that sounds pretty benign, but it's hard to get it into a comprehensive system. And it was almost all in place before Einstein came along.

What he did was really say, you can get rid of the ether. All you need to do is change your notions of space and time. And it wasn't until two years later that his professor, Hermann Minkowski, said, you know, your picture, Albert, works even more beautifully if you think of it as combining space in time into a single four-dimensional space time. And I have a nice quote in the book where Einstein in a paper is saying like, yeah, this is just sort of useless mathematical puffery. I don't find this space time stuff very interesting.

But he did have the problem of putting gravity into his theory. Right? Like once you went from Newtonian mechanics to relativity, you had to sort of relativize all of physics. And happily, electromagnetism was already relativistic. That's what inspired relativity. But Newtonian gravity wasn't. And he really thought hard about how to do it because the easy ways didn't work. There's sort of some obvious tricks to try and they all failed. So his happiest thought was he was thinking about the nature of gravity. And he realized that if you were in a box, a sealed room, you wouldn't be able to tell in principle whether that box was just sitting stationary on the earth and you're in a gravitational field or if you are in a rocket ship and the rocket ship is accelerating at 1G right and the reason why is because and everyone says that here's what they don't say you can tell whether you're in an electric field if you're

in a box versus moving in the electric field because a positively charged particle and a negatively charged particle react differently to an electric field. The fact that the acceleration downward is exactly the same for everything, for every kind of particle, that's what makes it equivalent to accelerating. Okay. That's what makes a gravitational field equivalent to accelerating in a rocket. And that is special when it comes to gravity. That's a feature that is true for gravity, but not for any other force. And so what Einstein realized was that therefore, this specialness of gravity implies that gravity is not a force living within space time, like the other forces that we know and love.

It's a feature of space time itself, one that affects all the particles in the universe in exactly the same way. That was his happiest thought. And so then he has to say, okay, what does that mean? This is why you or I could have that thought. It's a pretty happy thought. But then there's going to be math involved, right?

You have to turn it into physics. And again, he was smart enough to say, you know, okay, my old professor Minkowski said, space time. It's a way of thinking about the geometry of space time. Maybe if space time had a more interesting geometry, that could be gravity. But he had no idea what that meant. So he had to talk to his friends and learn about Rivanian geometry and tensors and all this stuff. And he plugged through it because he was a good scientist and he invented general relativity.

Yeah, that's right, which later allowed him to make a blunder, which he would regret for the rest of life, what turned out to be a blunder, to call it a blunder. But the fact that I was trying to get at, and I name drop talked about this with Nick Bostrom recently, I know as a friend of yours, a friend of your show. And I said, by what sense could you imagine a super intelligent, you know, as he calls it, S.I, having, A, the experience of a happiest thought, you know, I don't know how my computational device behind me could experience joy. But also, if I just dropped it out the window, you know, I don't know if it would think of that of being so happy, but I think part of it was the visceral feeling that Einstein could do a Godalkin experiment about, right? So he had

a viscer, he had a corpus, a body, embody. How can an AI do that? And I asked this of, again, I hate to name, but, you know, what else are you going to do? I mean, I remember you once said, Sean, one of the most annoying words that people can hear another person say is, on my podcast. But what the hell, Sean? I mean, I'm talking to you. I use it all the time. I've talked to Nomchomsky.

And he said, he made a very convincing case that, you know, one of those, you know, things that Turing really appreciated is, you know, that can machines think is like, you know, can submarine swim? It's very different way of thinking. In other words, there is an importance to cognition of the words, but also of the visceral experience. In other words, the fact that we have a body and we can. gesticulate me more than you because I'm a New York Jew. But, but, you know, if I lose my hands, I become mute. But, but the point being, that aids in not only in grammar, but communication,

but in thought processes. So Chomsky says body and embodiment of neural ideas is kind of the ghost in the machine. And then on the other hand, Bostrom says, no, just, you know, Moore's law, continuing forever, we'll get this in silico. Where do you come down? Is there, is there some, you A, as a, you know, podcaster that I look up to, when you hear two different ideas and you think one of them is totally, totally not, how do you maintain? Because I know that's happened to you in 190 episodes or more of Minescape. But how do you deal with that, A, and then we'll get into the actual discussion of whether or not you believe that a body or something is necessary for the happiest thought to emerge that leads to an idea like GR that you finish this book with.

How do you deal with divisive thought processes in real time on a podcast? Yeah, you know, I think that my goal as a podcaster is not to debate the guest. It's to let the guest give their perspective and their knowledge in the clearest and most digestible way possible. I will certainly note my areas of disagreement along the way. And sometimes I do disagree. Just had Simon Conway Morris on the show, who is a wonderful guest. but he is what we call a theistic evolutionist. He thinks that God guides the course of evolution,

even though he's an evolutionary biologist. So I disagree with that, and I am happy to say so, and I'm not going to invite someone on the show who doesn't want me to say so because I will. But then I always only get guests who I think I can learn something from. Just because I disagree with them about something, doesn't mean I can't learn from them about something else.

So, yeah, I will very often have people who disagree with other guests of the show. I don't think that's a big worry. Yeah. So one other question, just from my own venal self-interest, when you're, you've done so many of these wonderful interviews. It's one of the few podcasts I have in my regular staple diet. And you can get that.

We'll have links to that. We'll have links to Sean's, the, the fellowship that Sean's raising money for. But also, how do you know when you're doing a podcast in real time or can you, that you as a host are doing a good job? In other words, how do you know? Because you don't get feedback until. months or weeks later when you release the episode and someone says, you know, how did you let, you know, Tom DeLong say that, you know, or Jim Semivant

I had on my show and he's like, oh, the CIA doesn't do this information. It's illegal. And then, Brian, you let that slip. You're the shitty podcaster. You know, how do you handle that in real time? How do you know that you're doing a good job or a bad job? Well, I don't think that counts is necessarily a bad job. I mean, there's a fine line to draw between noting your own disagreement and arguing with

the guest. And yeah, there's plenty of people out there who will argue with the guests. There's plenty of debates. There's plenty of roundtables, plenty of disagreement on the internet. There's no shortage of that. I think there is more of a shortage of people respectfully dialoguing and trying to learn from each other. So that's what I try to do. I don't always do it well. I absolutely do some interviews better than others.

I mean, sometimes I won't say who, but there was a recent interview where the first half was great and the second half wasn't. I've had interviews, but the first half was terrible and the second, not terrible, you know, not terrible. It's never terrible. But I get better at it. And part of it is that different guests like talking about certain things more than other things, right? And you might not know ahead of time. That's not, I don't think it's my fault if the guest is just much more comfortable talking about part of their work than some other part of their work or something like that. I also think that, you know, we don't, I don't know about you.

but I never took a course on podcasting. Yeah. And there is no one skill called podcasting. There's like a million. Yeah, there's a million little skills, right? So I think that you have to get better by, you know, your own gumption of realizing that you can get better and putting effort into thinking about how you can do that. You know, I know that early on my audio quality was not as good for one thing.

But also I was too over prepared and a little bit too insistent on following a certain, kind of path through the interview and things like that. And I've loosened up a little bit. And, you know, I do try to be more sort of sensitive to what the, what the guest is, wants to talk about and doesn't want to talk about and so forth. But you'll always make mistakes. It's human beings in conversation. That's what it is. Also, I don't edit my podcast. So whatever happens happens. And, you know, people are going to hear that. That's like, you know, swimming naked and helping no one else is around, which I will be doing later on tonight. No, I'm just kidding.

So getting back to the real aspect of that question was, you know, can a machine think? So here's our friend Albert and he feels happy. You know, there he is smiling. And he's in free fall. So I just did a demonstration. But for those of you who are, you know, I've got to give the alternate text. So those of you that are listening, I just drop my finger puppet of Albert Einstein. All of them have seen those guys be.

I even have a finger puppet of Noam Chomsky, if you can believe it. Someday they'll be one of you, I'm sure. So, but I want to ask you, can a computer have a sensation of happiness, A, and then B, can it visualize through a human experience or sort of perspective, free fall in Einstein's case, that leads to an insight that is sort of the culmination, at least of this book, but maybe as one of my late great colleagues, Hans Parr, used to say the culmination of Western civilization is GR. So where did you come down on this? Well, I think that it's important here, as in many cases, to distinguish between questions of principle and practice. I'm on Bostrom's side in the sense that in principle, I don't think there's any thought that human beings can think that a machine couldn't think also. But there's a big gap between making that statement and saying, any day now, we're going to have theoretical physicists replaced by artificial intelligence, okay? Because I don't think we're anywhere close to that in the near term for more or less exactly.

reasons that Chomsky was highlighting. And I've had people on my podcast who have talked about this, but way back from the early days, Lisa Aziz Zaday was someone who talked about embodied cognition, where the fact that we have bodies really matters. It matters a lot to how we think. As a matter of fact, does it need to? I don't know. I mean, maybe there's a different kind of thought that happens completely irrespective of bodies. But as a matter of fact, the way human beings, think is highly conditioned on the fact that our brains are part of bodies, right? Unless you're a dualist, unless you're really a Cartesian dualist and think of the mind is completely separate from the body, these two things are related.

And forget, I mean, you raise interesting and important things about sensation and experience, but I think of motivation and values and goals, right? You know, human beings get hungry and we get tired and we get cranky in ways that And computers just don't, right? And I think that's important. I think that we are open the systems that are constantly, you know, experiencing, from a very different point of view, I had a psychoanalyst on Mari Rudy, who is talking about the Laconian theory of Lack. And I think that it's actually quite closely connected to the fact that we need free energy as physical systems to survive. We're open systems.

We're dynamical. You know, like I can, the example I often give is you can sit as stationary as you want and you can be mindful and you can slow your breathing, but your heart is still beating. Your ATPs are still being generated in your mitochondria, right? There's a lot of churn going on beneath the surface because you are a dynamical system. And if you don't take in resources from the environment, you will very quickly break down on cosmic times. John, is this your way of telling me you need a coffee break? I just give hints. I don't say things explicitly.

I speak in parables. But look, you know, this is something where maybe someday we'll have computers who mimic that. And then they'll become very human-like in their thought process. I see no reason why not. But again, I don't think we're anywhere close. Yeah, I asked that of Nick. I said, maybe it would behoove us to take, you know, our computers and like pull a pop a circuit breaker or pull a capacitor every now and then to tell it what pain feels like. but he sort of startled.

He looked at me like I just kicked his dog or something. So he's a delightful guy that episode. I don't know if that came out before or after this episode, but look for that. And you have a wonderful interview with him as well. Sticking with quantum mechanics and also a relativity. So as I mentioned, I had on our friend, mutual friend, Sir Roger Penrose, who's delightful as ever at age 91. And you know that he has this orchestrated OR theory, which he didn't have when I read

Emperor's New Mind, it came about afterwards because a man by the name of Stuart Hammeroff, who was an anesthesiologist at University of Arizona, contacted him after that book and said, you better look at these microtubules. So I had on Stuart and Roger on to talk about this. And we went into some detail about it, but one of the things I kind of pressed him on, and I don't know that he had really talked about it is, you know, does consciousness exist in non-Copenhagen interpretation framework? So in other words, would it exist? And I know you hate this phrase, but most of my colleagues or most of the listeners will be more familiar with the many worlds interpretation. I know you don't use that, but let's just call it that for simplicity.

In the many worlds, I asked him, you know, would consciousness take place because there is no collapse? So there's no orchestrated, you know, objective reduction. So in your mind, and he said he doesn't believe that you're right. So he doesn't have to answer that question. So I want to ask you, in fairness to you, he wasn't like, you know, denigern. any Everett or anything that you've worked on. But he's just saying he doesn't believe in that, so therefore it's an irrelevant question.

And then he, you know, he snorted at me. Does gravity play a role in consciousness or does gravity play a role in quantum mechanics? Let me ask that question because it's in his model. You have the wild curvature. You have this collapse that is instantiated by some gravitational process that I don't fully understand happening in the microtubules, which are operating in a squishy, wet, warm, room temperature environment. But is it?

Okay. I'm not going to say, is it conceivable? because you always say that's your least favorite type of question on your AMAs, which I listen to as a supporter of Patreon and everyone should support Sean. But anyway, could consciousness be affected by gravity, Sean? I, you know, not in my view. And look, just so the audience is able to put these things in perspective. There's two things going on here. One is Penrose has an idea about the foundations of quantum mechanics, one in which the Schrodinger equation is not always true because wave functions. explicitly collapse onto random things under the right circumstances, and those circumstances are governed by something having to do with gravity. And you're not alone and not knowing exactly when that is. It seems to be a little bit difficult for people who are not named Roger Penrose to pin down when exactly that collapse happens. The other is the connection to consciousness.

And, you know, I'm not even going to talk about that because I don't understand it and I don't care that much. I'm a physicalist about consciousness. I think that whatever consciousness is, it could happen under whatever interpretation of quantum mechanics you want. But just so everyone knows out there, I mean, it's not even in principle a solution to what David Chalmers would call the hard problem of consciousness. Chalmers would be very quick to tell you, you can't just change the laws of physics and solve the hard problem of consciousness. It's not a matter of the dynamics of the wave function. That's not what the question is about. So you haven't solved it. And it's not really what Penrose wants to solve. What he wants to solve is the calculational capacity of human cognition,

which is a different thing than what we think of is the hard problem of consciousness. And he has elaborate arguments involving Kurt Gödel and computations, which I don't find convincing either, and experts in the field don't find convincing. But on the pure quantum mechanics level, his theory belongs in a category of theories known as objective collapse theories, and they're treated as fairly respectable, but certainly minority points of view among people who think about the foundations of quantum mechanics. It gets a lot more airtime on podcasts and in the public media because it's Roger Penrose. But there are a bunch of people who work very, very seriously on the foundations of quantum mechanics, and they do not think a lot about Penrose and Hameroff's

orchestrated objective reduction theory. Yeah, I agree. That's certainly true. And I think, you know, they, yes, it's fun to talk to them. It's, it's, actually really interesting to talk to Stuart as well, because he does do things that he can be an experimentalist and actually play around in some sense, as he says, with anesthesiology and putting his patients to sleep. And that's what he gets paid to do. I said, join the club. That's what I do when I'm teaching. Come on, Stuart. Well, and also, it's important to point out that, of course, they could be right. I'm letting people know that they have a very, very minority point of view that is not popular among physicists or philosophers in the foundations of quantum mechanics doesn't mean they're not right.

But I think there are reasons why their view is not popular. And part of it you sort of alluded to when you say it's kind of hard to pin down what their point of view is, which is not a hallmark of a well-constructed scientific theory. And on that topic, I talked to Stuart. I said one of the questions I had was about the opposite of anesthesia as sort of like ayahuasca or psychedelics. And actually, one of my audience members is asking me if I would ask you if you'd like to do an edible right now I'm just kidding but they're asking have you ever experimented with mind enhancing chemicals besides your treasured cocktails which I've experienced with you any mind enhancers in the in the not agitating but sort of enhancing cognition as these psychedelics are thought to do

well I think that's not the right way to think of them I did do LSD once that was the entirety of my experience there. It's recounted in my wife Jennifer Willett's book, me, myself, and Y, searching for the science of self. So we both did it exactly because there are these claims that you have a different level of cognitive capacity when you're on psychedelics. And I'm a huge believer that psychedelics have possible therapeutic uses. I think it's an absolute tragedy that very cheap arguments about the drug scare have prevented scientific research from being done on these so-called Scheduled 1 drugs in the United States and England and other places. It's beginning to break down. I've had people on my podcast like Robin Carhart Harris who do professional research

on psychedelics. And it's enormously promising for therapeutic uses. I don't think it's promising for being a smarter person uses. It's a different kind of thing. I mean, the very, very clumsy, but I think helpful way of thinking about what psychedelics do is the brain is really, really noisy underneath the surface, right? There's a lot going on in the brain. And you sort of get attuned to this when you're asleep and you're dreaming a little bit. And some of these sort of mismash of visions and sounds comes to your forebrain. But in your everyday life, you sort of suppress a lot of what you might think of as the vacuum

fluctuations in your brain. And what the, you know, the psychedelics don't turn on more activity, they just lower the inhibitions to you being aware of the activity that is already there. So I think that they have, that's, that can be very, very helpful when you're in a rut. This is something that is true for people struggling with addiction. It's true maybe for people with ADHD or something like that. And maybe under the right circumstances, it can make you more creative. It does not help you doing a derivative or an integral.

I promise you that. Sean, I don't know if you're aware of another podcaster named Tim Ferriss, not the astronomer Timothy Ferris, but Tim Ferriss. And he has created an endowment at, in partnership with Johns Hopkins, called the Center for Psychedelic and Consciousness Research. And that's part of their medical establishment there. So I don't know if you've encountered people from there, but it sounds pretty interesting, sounds like it's right up your alley,

and it sounds like it's for a good cause treating PTSD using, you know, controlled, I don't remember from Jennifer's book, the circumstances of your LSD experience. But in this context, it's supervised medically by arguably the top medical institution in the world at Johns Hopkins. So I want to just include that for completeness in this discussion. I'll have a link to Tim Ferriss's blog and stuff. And maybe you can help participate in that. Very good. So getting back to quantum mechanics, I think one of the most,

mystifying and magical things that comes out of part of this book, but will rely on the second volume to get to quantum mechanics, is the fact that you talk about the principle of least action, which some have called like past guests Sabina Hassenfelder, you know, as close to a theory of everything as we have. I'm not going to debate that, but, but, you know, these things that arise from things called Poisson brackets and commutation relations and let's nerd out for a little bit. I find it very mysterious that we have these things in classical mechanics that we can do as undergraduates that vanish when you do certain types of measurements. And then you merely add, you know, the square root of negative one and some constant with the proper dimensions.

And then in quantum mechanics, they don't commute. And in fact, they give you these imaginary numbers, not complex. But isn't that astounding? I mean, where, in other words, we have these commutations. I think Bourne has them on his tombstone, the commutation relations that don't vanish, so between position and momentum. But in classical mechanics, they do. Is that something deeply hidden, you know, for real this time, that the same structure,

the same mathematical operations, when applied classically versus to a quantum object, are so radically different. And then it involves the square root of negative one. What the hell is going on there? I don't think the square root of negative one is a big deal here. but it's helpful as a mathematical trick. What I really think is that, you know, we human beings have to get over our preoccupation with classical mechanics.

Classical mechanics is not how the world works. The question should not be. And I mean, the way that you phrase the question is exactly what every physicist would do. So this is nothing about your particular formulation. But everyone says, like, okay, classical mechanics and you have position and momentum and things are happening. And then quantum mechanics, things become weird. Okay. Well, but the world is quantum mechanical. I mean, you can say that, but you're only making a statement about your benighted view of the world. You're not making a statement about nature. The statement about nature should be of the form. Here's the quantum world. Here's how it works. And there's something called the classical limit where things are different. Okay. And from that perspective, you know, it just begins to make a lot more sense because you're not swimming uphill against these presuppositions of the classical.

way of thinking about things. In quantum mechanics, position and momentum are not two things that are true. They're not features of the system. They are possible measurement outcomes, but they are not characteristics of the system. And you got to get over that classical way of thinking about it. And when you do, your internal view about quantum mechanics becomes a lot more peaceful. So, Sean, do you have time for some audience questions and then some final questions from yours truly? Let's do it. Okay, so audience questions. We already asked the one about psychedelics,

so we no longer have to ask that question. So one is asking about your largest hope for the James Webb Space Telescope. Is there a certain question or topic that is within the purview of the JWST that could be answered by them? You know, when I was at Caltech, I was contractually obligated to say nice things about LIGO. Yes.

Because LIGO is a Caltech experiment. And now, I didn't have any difficulty doing that because LIGO is pretty awesome. Now at Hopkins, I'm contractually obligated to say nice things about JWST because literally I can look out my window in this office I'm in right now at the Space Telescope Science Institute where JWST is controlled from. And again, it's not a hard obligation to live up to because I think it's going to do a lot of wonderful things. What I need to emphasize is, I don't think there's any research question that I myself am working on or deeply interested in. The JWST is going to help us with it all because I want to know what the fundamental laws of physics are at an even deeper level than we already understand them. And JWST is about the working out of the known laws of physics in astrophysical situations. It's about galaxy formation and star formation and supernovae and planets.

all that stuff. And I need to really, really emphasize that that is really interesting and important, even though it does not teach us anything about quantum gravity. It's okay. It doesn't need to teach us anything about quantum gravity to be interesting. Okay. So what I say, on the one hand, it's not going to teach us anything about the origin of the universe of the Big Bang. And on the other hand, it's still worth doing. Oh, yeah. For example, you know, exoplanets are something which as much hype as there has been around them, there should be more. It's really just amazing. You know, when I was in grad school, we didn't have any exoplanets.

We didn't know about any planets around other stars. And now we have thousands of them. And some of the things that we've learned about them have been a bit surprising. And I'm looking forward to more surprises. And JWST as a giant infrared telescope is going to be able to sort of look at starlight shining through the atmospheres of extrasolar planets. and learn about what those atmospheres are like. You know, in some crude way, that was not what is optimized for,

but it'll be a little bit. Come on. That's got it. That's just like, you know, something my young self would have flipped out over. Like, let's get excited about that. I think that's really, really fun. Yeah. And you had a podcast not too long ago with, I think it was,

as a Fisher. With John Johnson. Say that, yeah, John, yeah, Josh. John Johnson. Yeah, that's right. Good. So actually, I want to take the liberty of asking, the host prerogative. So you talked about finding exoplanets and, of course, the hope that

there'd be life on it. I don't think we've ever talked about alien life. I don't know. It's something you talk about it, but it's dear aure nowadays in podcast world. So the first question I want to ask you is whether or not, since you are the master Bayesian of all Bayesian that I know, in terms of explicating it, maybe not only believing in Bayesian approaches to probabilistic reasoning. But anyway, the fact is, in 1997, there was a press conference on the White House lawn. And Bill Clinton was there. And you can actually see it in the movie Contact with past guests on my show, at least, And Jurian, who would make a great guest for you, the wife, the widow of the late Great Carl Sagan.

And she co-wrote the book Contact in which the movie is based. And in that, they take a scene from this. So that was 1997, 1998. They took a scene from the late 1996 when there was a declarative. announcement from a discovery of meteorite relics in Antarctica, a possible respiratory, microbial respiratory byproducts or something like that. Now, that was actually, you know, vetted by NASA and had to be to be broadcast from the White House lawn. It was actually some articles are published in science and so forth, peer reviewed and everything. And that showed

that there are meteorite activity that can come from Mars and land on the earth at one thing. and then that life could persist potentially. And by the way, that's never been retracted formally. I mean, it's never been like there's been a retract, oh, that we were wrong. It's just ambiguous. It hasn't been confirmed or refuted. It's pretty wrong. It's pretty wrong, by the way.

Be that as it may. We know that it's wrong. Yeah. The fact occurs to me that given that there is life on Earth and given that it arose a few hundred million years after the origin of the Earth, we've had four billion years for these little chunks of rocks, which by the way, you can win if you're one of the next 100 subscribers to my mailing list, Brian Keating.com. I send out meteorites to people in America. I can afford us to send out American meteorites through the U.S. Postal Service, but

gravity will deliver it once you get it. Given that we haven't found life on Mars or on any other evidence of life on Mars, is there some amount of Bayesian prior reasoning that we can then diminish the probability of life being present throughout the universe. In other words, we often hear that as soon as life came on Earth, which we don't know how that came about, maybe it's panspermia, maybe it's not, but kind of the fact that reverse panspermia can occur. We can kick tardigrades off of a chunk of the Grand Canyon and can go into space. How come can we use that to reason that life is actually not that abundant as many people think and certainly not advanced technological life? Or am I, you know, is this not an appropriate way

to view the problem. You said this place was steps from the water. We just haven't found the steps yet. How much did we save? Enough. Enough to get lost. Or you could book a stay with Hilton. Welcome to your oceanfront room.

Just steps from the water. The Hilton sale is on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you stay. Hilton for this day. Well, I don't think we can go quite that far,

but the fact that we do not see abundant, very obvious life on Mars or other bodies in the solar system, all else being equal lowers our probability of life being ubiquitous in the universe. On the other hand, if your theory that you're trying to update is 1% of Earth-sized planets have life on them, then the existence of no life on Mars doesn't change your prior probability very much at all.

And 1% of the planets out there would still be billions of places to have life out there in the universe. So, you know, I draw a big distinction between life and anything that you think of as advanced intelligent life, right? That's a very, very different question. I think that there are good Bayesian reasons to think that there are not that many advanced civilizations in our galaxy. That is something that we could have observed very, very easily and we haven't. And every time I say that, the UFO. people come on and say, wait until this guy is shown up in six months when the new report is released. But this has been going on for 10 years and the new report has never really shown me up.

So I'm pretty confident about that. But that's very different than saying is there simple unicellular life out there. That could be everywhere. That could be on Europa. That could be even there could be even multicellular life on Europa. We don't know in the oceans of Europa. But we'll have to go, look, you know, the best Bayesian does not get very far when you only have two or three data points. So we need to collect a lot more data. And the exciting thing is we're going to do it. That's kind of awesome. We're going to be updating our priors in a substantial way. Yeah. Yeah. And I think of nothing else that discovery in the late 1996 demonstrates that, you know, people think, oh, it would change humanity forever. The discovery, even of a microd of slime mold on Proxima Century B would change

forever. We'd have this community. I say, no, it wouldn't be. And there's proof. I don't know. Because 99% of the people that even heard about this in 1996 probably still think it was accurate or it could be true. And I don't think we've had this, you know, great kumbaya moment across humanity. Anyway, you have to respond to that. But, but the next question comes from a very good fan of yours and good friend of this show, Maya Benowitz from Twitter. You can follow Sean on Twitter at Sean M. Carroll. You can follow me at Dr. Brian Keating on Twitter. She asked, extracting the universe from the wave function was a very nice talk. My question is this, if in principle, whatever information behind the horizon can be recovered by holography,

then why assume a finite dimensional Hilbert space? So I haven't seen this talk, but... Well, there's a lot going on there for the person on the street, so I'll try to unpack it there. The talk that I gave on extracting the universe from the wave function is an illustration of this philosophy that I already mentioned, that we should think quantum mechanically first about the universe. And we have this thing, even among professional physicists, where we have a classical theory of this or that, field or string or what have you,

and then we quantize it, right, to make a quantum theory. But the real world doesn't do that. The real world just starts as a quantum theory and then it has a classical limit. So that's the program that is being pursued when I talk about extracting the universe from the wave function. Given a wave function and a way that it evolves, what is the classical thing that that represents.

And part of the one of the things I like to do in that talk, which is completely optional, but it makes my life easier, is I argue that the Hilbert space of the universe, which is just the set of all possible quantum mechanical wave functions. So it's a vector space, which means you can add wave functions together. That's all it really means.

It's like X and Y, except instead of two dimensions, you have 10 to the 10 to the 122 dimensions. There's a lot of dimensions. in Hilbert's space. Everyone gets a dimension. But that's still a finite number, 10 to the 10 to 122, is still not as big as infinity. And from the math methods point of view,

that matters a lot. That really sort of does affect how you go about the analysis. So the existence of black hole entropy is not a problem for this point of view. It's a feature of this point of view. It is one of the reasons why we think that the universe only has a finite, dimensional Hilbert space because a black hole, Stephen Hawking said a black hole is entropy.

And his argument for that was actually pretty phenomenological in the physics sense. In other words, he didn't have an underlying deep theory. He was sort of not Ludwig Boltzmann. He was Rudolph Clausius, for those of you who are big fans of 19th century thermodynamic history. Clousius is the one who invented the word entropy. But he didn't know what it was. He knew what it did.

And it was Boltzmann who eventually explained what entropy was later. And what Hawking did is closer to Clausius. Like he's explaining what entropy does without saying what it is in the black hole. And we still don't know for sure. But the leading idea is that it represents entanglement between what happens inside the black hole and what happens outside, quantum mechanical entanglement. And here is where I would argue that the typical physicist on the street is cheating a little bit. it or not taking seriously enough what's going on, if you just take a region of empty space in quantum field theory, right?

Quantum field theories are best way of thinking about the world right now. The standard model particle physics, QED, etc., they're all quantum field theories. There is an entanglement between empty space in quantum field theory in a region and the whole rest of the world. Everything outside the region, everything inside the world, the region is entangled. And therefore you can calculate the entropy associated with this region. Do you know what the answer is, Brian? No.

It is infinitely big. It's one of the divergences in quantum field theory. Because there's an infinite number of modes of a quantum field. They can be infinitely small or whatever. And so the fact that the entropy of the black hole is finite, even though there are good arguments that an entropy of a black hole is the most entropy we can fit into a region of space. Finite is less than infinite. And that's telling us something really, really profound, which is that gravity is not a quantum field theory in any straightforward way.

Gravity is something more subtle than that. I mean, maybe it's a sort of bizarre, warped kind of quantum field theory, so everything works out okay. But the facts you get to the question, you know, the fact that the holographic principle suggests, what it suggests is the number of cubic bits of information inside a black hole is equal, roughly speaking, to the area of the event horizon measured in plank units. And so you can think in some sense, Lenny Susskin would say, of the information in a black hole as living just on or just beyond the event horizon of a black hole. But all I care about is that it's finite. So that's perfectly compatible with everything I'm doing. It actually fits in very nicely.

All right, good. Okay, two more questions from the audience. And then four short ones, from yours truly, and then I'll let you go get that ayahuasca latte you've been craving all day. Joy Colbeck, good friend of the show, what's the difference between decoherence and wave function collapse? Oh, there's a big difference, except that there's a relationship because decoherence can trick you into thinking that wave functions have collapsed. Decoherence is a process that happens smoothly and in a way that is absolutely 100% described, by the Schrodinger equation. So you have two different quantum mechanical systems. We usually call them the system,

which might be like an electron or might be a cat or whatever it is. And then you have the environment. So all the photons in this room, all the stuff you're not keeping track of is the environment. And decoherence is just when the system and the environment interact in such a way as to become entangled. So there are many interactions between a system and environment that do not cause entanglement.

usual example I give is if you have a spin, you have a particle that is a superposition of spin up and spin down and you drop it. Professor Einstein in his principal equivalence experiment would tell you it's going to drop the same speed no matter whether it's spin up, spin down, or some superposition, right? So there's no interaction between the earth and the spin, namely it's pulling it under the force of gravity. But there's no entanglement because it's not interacting differently with spin up versus spin down. Whereas if you shoot a polarized photon at that spin, it might interact. This is something Brian knows a lot better than I do probably. It'll interact differently depending on if the alignment of the spin versus the polarization of the photon. So that's a

chance for entanglement and that would count as decoherence. So it's all perfectly smooth. It's just the Schrodinger equation, no magic there. But if you accept the many worlds form of quantum mechanics, then you would say, when decoherence happens, the universe branches into different worlds where different parts of the wave function of the system are entangled with different parts of the environment. And to each person living in the world, it looks like the wave function has collapsed. That's the relationship between wave function collapsed. If you don't believe in many worlds, if you're Roger Penrose, then you think that wave functions just collapse.

Like that's a thing. Okay. And that's something that is nothing to do with decoherence. So to a many world's person, decoherence leads to

the appearance of wave function collapse. To a objective collapse person, they're unrelated. Okay. Last question from my audience.

We have many, many questions, but Sean's a busy guy. If you want to get your question answered, guaranteed, join his Patreon for Mindscape. I'll put a link to that.

I'm a patron. Captain Brick, which I was going to call my firstborn son, Captain Brick asks, in many worlds, some branches are thicker than others. I find it easier to imagine that there are more copies of World A versus World B, depending on the thickness. Are these two views equivalent or is the thickness of the branch, quote, baked into the theory? I'm not 100% sure, so hopefully you are. There's another question about conservation of energy and branches, thickness versus branch

thickness from a different listener, but if that one doesn't. Yeah, I find the thickness of the branch is a useful way of thinking about it. It's just to those of you who know a little bit of quantum mechanics, it's the wave function squared. That's the thickness. So it's the amplitude for each branch squared. And that is what gives us the probability of finding ourselves on that branch once the branching happens. And the point is that the total thickness of the wave function of the universe remains constant,

But as time goes on, branching sort of slices the universe into ever thinner branches. And this visualization helps us understand things like conservation of energy because the way function of the universe overall isn't growing at all. But the number of universes is growing. And then we get into this very sticky philosophy problem, which is do we have to wait until the branching happens to call the two different branches, different universes? or can we call them different universes even before the branching happens and they are identical to each other? So I see the appeal of calling them different universes even before they're branched. But I don't think you can actually come up with a definition of universe in which two things that are really identical to each other and doing the same things in part of the same physical system are two different universes. I don't, I mean, maybe I'm wrong about that.

But I think that it's better to just bite the bullet and say that branching happens. And, you know, this is a situation where all the math is perfectly transparent. It all works out fine. There's no real problem here of what the theory says. The only problems are understanding at an intuitive level, which is, which is admittedly a big leap. Indeed. So, Sean, I now come to the most exciting portion of the interview where I get to ask my own existential questions that we call the fantastic for or the quintessential quattro.

But to get access to those answers from Sean to my existential questions, you're going to have to subscribe to our mailing list. So you can find Sean's mailing list and his YouTube channel and support that at preposterous universe and mine, bryankeating.com slash list. So to get the answers that you're dying to hear from Sean, you'll have to subscribe over there. Sean, thank you so much for being a part of this episode. Sean, I want to thank you and congratulate you on a number of different items, but especially on

your new book. The biggest ideas in the universe, Volume 1, Space Time, Matter, Motion. It's a wonderful, accessible book. I'm actually using it for one of my middle schoolers at home to learn about calculus. It's a little advanced for him to learn about special relative, although he did have a lecture from Jim Gates in person when I was back at Brown on Super Cemetery. but I want to congratulate you on this book, which he followed and he got some good pointers. I want to, yeah, congratulate you on this wonderful accomplishment and the great success. Wish you great success there on the East Coast, close to the halls of power. May you be a physicist on a hill there and influence the country towards the betterment of all mankind.

Thank you, Sean, so much. My pleasure. And, you know, keep on the spirit flying there in Southern California with the surfing and the sunshine, which I know is your big deal. So we'll miss you. Thanks, Sean. Any sufficiently advanced technology is indistinguishable from magic. Well, that is a wrap of another fascinating episode of the Into the Impossible podcast.

This time is Sean Carroll. Sean is a really delightful intellect, a scholar. And I always enjoy getting a chance to talk to him. Might be less frequent now that he's over there on the East Coast. But again, your gain, East Coasters is our loss. he'll miss out on some of the summertime surfing that we used to enjoy out here. So I want to just encourage you to stay tuned to the podcast. We have many, many great guests coming up on the show, Nobel laureates,

to hopefully some more Pulitzer Prize winners coming back on the show, but always taking deep dives to science, technology, engineering, math, culture, the arts, astronauts, aliens, and everything in between. And I want to encourage you if you like the show to support the show. you heard Sean talk about his Patreon. I have a Patreon. I don't talk about it much, but Patreon.com slash Brian, Dr. Brian Keating. That's one way to support me, of course. You know, it costs money to do these things. But really, I mainly want your moral and free support. And you can do that by, as I say, joining my mailing list, Brian Keating.com slash list.

You may win a meteorite sample that we discussed in this episode. The other thing is to leave a review. And you can leave a review now and basically rating, at least, on every major app that you're listening to this podcast on right now, on Apple. and on Audible, you can actually leave written comments. I'm going to read a written comment from a listener that I just got on Apple Podcasts. And it comes from a person by the name of K. Bunny Urk. I hope I'm pronouncing that right, although it would make kind of hilarious if that was somebody's actual name. And he or she says exactly what I've been looking for.

I'm a biochemistry graduate, but I've always been fascinated and interested in physics. Dr. Keating's podcast are exactly the level of science that I've been looking for in podcast. Oftentimes, science podcasts are produced at the layperson's level or graduate student who's active in the field and nothing between. I can follow about 95% of the podcast. That's almost as good as I can. K. Bunny, irk. And so this is kind of the vibe I'm going for in this podcast. People that are interested in reading books, popular science level, but I'll go deep to and nerd out. I can't resist. It's too much fun. And as I say, I'm trying to assemble the free university. You can attend in your pajamas or while you're driving to work or on a subway or whatever.

and I've just been thrilled. I've gotten over 550 reviews worldwide on Apple alone. So you can add your own. It really is all that I ask for. And you can support me in that way. You can also get access to video interviews where I add a lot of cool fun things at Dr. Brian Keating on YouTube.

I hope you'll subscribe there. And soon we hope to be doing an AMA-type episode as well on both of these formats. So you can leave comments, feedback when you enjoy my email list, or there's a little microphone icon on the podcast webpage. Brian Keating.com slash podcast where you can leave a question or a request or what have you for me and I'll listen to each and every one of them. I love listening to hearing your voices since you

are so generous with your listening to and encouraging of them listening to my voice. Anyway, for now, that is all. And I hope you will enjoy the rest of your time. It's so precious as the summer comes to an end. Right now, begin the fall, at least in the Northern Hemisphere. I actually have a lot of Southern Hemisphere listeners and even a couple at the South Pole and Arctica where I used to live. Well, just for a couple of days. or weeks. Anyway, wishing you a magical week. This is yours truly. Brian Keating, host of the Into the

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