Into the Impossible With Brian Keating - Carlo Rovelli: Loop Quantum Gravity & The Order of Time (#122)

Episode Date: March 2, 2021

Carlo Rovelli (born 3 May 1956) is an Italian theoretical physicist and writer who has worked in Italy, the United States and since 2000, in France. His work is mainly in the field of quantum gravity, where he is among the founders of the loop quantum gravity theory. He has also worked in the history and philosophy of science. He collaborates with several Italian newspapers, in particular the cultural supplements of the Corriere della Sera, Il Sole 24 Ore and La Repubblica. His popular science book Seven Brief Lessons on Physics has been translated in 41 languages and has sold over a million copies worldwide. In 2019 he has been included by the Foreign Policy magazine in the list of the 100 most influential global thinkers. He is author of the international bestseller Seven Brief Lessons on Physics, Reality Is Not What It Seems, and The Order of Time. Rovelli lives in Marseille, France. Already a bestseller in Italy, and written with the poetic vitality that made Seven Brief Lessons on Physics so appealing, The Order of Time offers a profoundly intelligent, culturally rich, novel appreciation of the mysteries of time. http://www.cpt.univ-mrs.fr/~rovelli/ @carlorovelli 00:00:00 Intro 00:08:00 About the book, THE ORDER OF TIME 00:09:41 How did you get the idea for this book and deem it worthwhile? 00:13:43 Why do you think theology was an important issue for Stephen Hawking? Comments on the "boundary" problem. 00:16:40 The story of George Lamaître, Pope Pius XII, science and god. 00:32:35 Loop Quantum Gravity theory and variations in the speed of light. 00:35:22 Cosmic parity violation evidence from the Planck 2018 data release: a new experiment? 00:40:00 Is quantum gravity theory a tautology? What LQG predicts about black holes. 00:46:30 One of the greatest hypes in science? 01:00:30 Carlo's opinion on dark matter. 01:03:33 How can future experiments test quantum gravity theories? 01:05:17 Carlo proposes a quantum gravity lab experiment could prove quantum geometry. 01:10:30 Loop Quantum Gravity (LQG) masterfully explained. Is there a unit of quantum area? 01:22:15 Can quantum mechanics be simulated? Support the podcast: https://www.patreon.com/drbriankeating And please join my mailing list to get resources and enter giveaways to win a FREE copy of my book (and more) http://briankeating.com/mailing_list.php 📝 🎥 🎥 Watch my most popular videos🎥 🎥 Frank Wilczek https://youtu.be/3z8RqKMQHe0?sub_confirmation=1 Weinstein and Wolfram https://www.youtube.com/watch?v=OI0AZ4Y4Ip4?sub_confirmation=1 Sheldon Glashow: https://youtu.be/a0_iaWgxQtA?sub_confirmation=1 Michael Saylor The Physics of Bitcoin https://youtu.be/CaN_CDKqXOg?sub_confirmation=1 Sir Roger Penrose, Nobel Prize winner: https://www.youtube.com/watch?v=AMuqyAvX7Wo?sub_confirmation=1 Jill Tarter https://youtu.be/O9K9OBd3vHk?sub_confirmation=1 Sara Seager Venus LIfe: https://youtu.be/QPsEDoOTU6k?sub_confirmation=1 Noam Chomsky: https://youtu.be/Iaz6JIxDh6Y?sub_confirmation=1 Sabine Hossenfelder: https://youtu.be/V6dMM2-X6nk?sub_confirmation=1 Sarah Scoles: https://youtu.be/apVKobWigMw Stephen Wolfram: https://youtu.be/nSAemRxzmXM 🏄‍♂️ Find me on Twitter at https://twitter.com/DrBrianKeating 🔥 Find me on Instagram at https://instagram.com/DrBrianKeating 📖 Buy my book LOSING THE NOBEL PRIZE: http://amzn.to/2sa5UpA 🔔 Subscribe for more great content https://www.youtube.com/DrBrianKeating?sub_confirmation=1 ✍️Detailed Blog posts here: https://briankeating.com/blog.php 📧Join my mailing list: http://briankeating.com/mailing_list.php 👪Join my Facebook Group: https://facebook.com/losingthenobelprize 🎙️Please subscribe, rate, and review the INTO THE IMPOSSIBLE Podcast on iTunes: https://itunes.apple.com/us/podcast/into-the-impossible/id1169885840?mt=2 🎙️Listen on all other platforms: https://wavve.link/into A production of http://imagination.ucsd.edu/ Support the podcast: https://www.patreon.com/drbriankeating Learn more about your ad choices. Visit megaphone.fm/adchoices

Hi, everyone. I just did an amazing interview with Carlo Revelli. The man is like Stephen Hawking plus Albert Einstein reincarnated, and he's so fascinating. Such a European, such an Italian, and such an inspiration to me as an experimentalist that I can have high-level conversations, talk about experiment, talk about philosophy, talk about poetry, talk about our influences and human nature. And to me, these kinds of interviews are what make doing the Into the Impossible podcast all worth it. You're going to learn about his new kind of perspectives on theories of everything, on quantum gravity, on working with Benedict Cumberbatch. How would you like to have your audiobook read by Benedict Cumberbatch, which he did and just be delighted by this incredible character who's tremendously inventive, creative, and is not afraid of controversy. and I press him as they do with all my guests.

No one gets a free pass on the end to The Impossible podcast. But nevertheless, you're going to enjoy this interview as much as I did. Please do those following things. If you're on listening to this on iTunes, please subscribe, please leave a rating. If you're on Spotify, et cetera, do a follow. YouTube, do the same. Please do so.

It keeps the show going. Gets me great guest access. Like today, and you'll hear about an upcoming project that I hope to involve Carlo with, that involves El Maestro Galileo. And you'll hear about that and much, much more, and get tuned up, teed up, and ready for his upcoming book,

which is coming out this spring slash summer, depending on where you are. And we will have Carlo back. He had such a good time he's coming back on. Thank you very much. Now enjoy this blast of a voyage. Into the impossible. Any sufficiently advanced technology

is indistinguishable from magic. For everything, there is a season and a time for every purpose under heaven. A time to be born, a time to die, a time to plant, a time to pluck up that which was planted. A time to kill. A time to heal. A time to break down. And a time to build up. A time to weep and a time to laugh. A time to mourn. And a time to dance. A time to cast away stones and a time to gather stones together. A time to embrace. And a time to reverse. refrain from embracing. Time to seek and a time to lose, a time to keep and a time to cast away.

A time to rend, a time to sow, a time to keep silence, and a time to speak. A time to love and a time to hate. A time for war and a time for peace. Today we're talking with the incomparable Carlo Rovelli, master of time, master of the order of time. Carlo, this that I just read you was written in 2000. Coheleus, very good. The greatest text humanity ever has ever written. I believe it is too.

And I actually quoted from it in my book, losing the Nobel Prize, but also in my thesis, the opening chapter was, better is the end of a thing than the beginning thereof. I'm going to ask you, do you think that Coheles influenced

the following two people, Isaac Newton, who said, for every action, there is an equal and opposite reaction. and or Arthur C. Clark, the namesake of this fine institution that I am the co-director of at UC San Diego, who said, for every expert, there's an equal and opposite expert. Did co-helet, did Ecclesiastes influence these two great minds? I don't know. Certainly not.

But it certainly influenced a lot of thinkers also for humankind. Indeed. So today we're talking about a lot of things, including emergence of perhaps, space time itself, but before we get there with one of the really the guiding lights of modern, not only of modern physics and fundamental theories, but also of the popularization and the entrangment of such an concept exists with human beings all over the world with his popular writing and even his appearances in such vast and diverse projects as Disney movies as I learned that you were in a Disney movie. Is that right? I was a Disney character. I was a Disney character. I was Disney diodes.

I don't know if there's a verb of that. So there's a little Carlo character there with a Disney face. If I was in a Disney, you know, movie, it would be Pinocchio because I think. Well, we're careful. Pinocchio is the only Italian book that has been translated more than my seven brief lessons in physics. Which I know has been translated. Right now it's being translated into the 42nd, 43rd. 44.

Oh, really? We'll get into 44, yeah. Wow, unbelievable. Well, I want to talk to you, and this is something I'm springing on you without any notice. I'm sorry, but I am involved in a project to translate this. Not to translate this book. This is the dialogue concerning two chief world systems. It was written by a fellow Italian who knew a thing or two about time.

That's perhaps one of your great influences, Galileo, El Maestro, the Galileo, of course. And it turns out, Carlo, that this book has been translated, obviously, many, many times. it has been even published in an e-book, which is hard to find, but it does exist. But no such audio book of this exists. So what I'm going to propose to you, if you're willing, after this interview, is to help me, with an Italian colleague of mine, just record the foreword in Galileo's voice. We are making the first authorized edition, courtesy of the publisher of the estate of that owns the rights to this book, not Galileo, but the University of California owns this particular translation. So anyway, I'm going to ask you to read the voice of Galileo when the time comes, not today. It's a great honor.

I mean, of course, Galileo is a myth for everybody doing science. But he's not just one of the fathers of science. Science has many fathers, but one of the great fathers of science. But he's also an incredible writer and is an inspiration for anybody who want to write about science. He was writing in a way that everybody at his time could read his books. That's right. And I actually quoted from that in a piece I'm doing a series just kind of on a physicist take on the dialogue. And I noted that he came up not only with concepts in physics, Carlo, as you know, but also concepts in psychology.

For example, there's one effect called the Dunning Kruger effect, which basically I exhibit, which is that you think you know a little bit. And so because you know a little bit, you think you know everything. So Gallo, Gallio says this. He says, this vain presumption of understanding everything can have no. other basis than never understanding anything. For anyone, for anyone who had experienced just once the perfect understanding of one single thing and had truly tasted how knowledge is accomplished would recognize that of the infinity of truths, he understands nothing. I mean, how beautiful is that. How to, how to, how to. It resonates that what Newton says at the end of his life, right,

that he's like a child in front of the ocean of our ignorance. And you know what? In my popular books, I've noticed something. The people who love my books more are those who know nothing about science or those who know deeply about science. I mean, the scientists. The people who know something about science tend to like my books less because they think they know already.

That's very interesting. I think it is a manifestation of this. I actually learn a great deal. Not only how to frame things in a way that was influential on me from your writing, on my own popular science writing, but also understanding new concepts and just the essence of a concept. I mean, let's get to the order of time. We'll get that out of the way. Then we'll get to some.

We're going to take a deep dive. My audience is incredibly astute we had on this summer. Lee Smollin you might have seen. Sabina Hassenfelder, Eric Weinstein, Max Tagmark, Stefan Alexander and also James Beecham. We went over this. Over a million people saw our conversations about theories of everything. I'm going to talk to you about a provocative new idea I have for an experiment of everything.

But before we get there, I want to talk about the order of time because it is such a lovely book. And it really crystallizes in my mind. I read it and I listened to the audiobook read by none other than Benedict Cumberbatch. I like his name because it has CMB in it. And that's very interesting. He has a great voice. Although he does make a typo. I listen to him and I said, did I really write this?

It's so beautiful. Well, one of my kids caught a typo that I'm sure that you didn't make, but I think he did. He calls the process that produces helium from hydrogen in the sun. He calls it vision. Oh, no, no, it was my mistake. Oh, really? I'm totally stupid. Yeah, yeah, I'm totally stupid.

When I did catch it, I said, oh, come on. How can I do it? I confuse fusion with fission, which is made. no sense at all. I mean, a physicist shouldn't do this stupid thing. Especially an Italian physicist, Carlis. But I did. So, apologies. I mean, it's corrected in the new editions, of course. I said, so I saw it. But it was my being idiot. Good to know. Well, anyway, it doesn't detract from the enjoyment of that wonderful book. So in that book, you really, if I can summarize it, it's really, you know, an ode to Classias, et cetera. But why did you, why did you come upon this

as an idea worthy of your time? You have an incredibly demanding schedule. With this, you're so generous with your time, but it took me a long time to set it up because you're so busy, traveling, doing research. How do you decide that a topic is worthy of Carlo Rovelli's time? That is the most precious commodity, some say. I actually disagree with that, and that will be my next question. But how do you find the time?

Well, it's hard. I wrote a book to explain that time is different than what we think about, but in reality, in our lifetime is this difficult thing we have to juggle with. But you know, the big mystery about time, the big problem about time, I think everybody's puzzled and confused because it's not one.

It's many-layered problems, the problem about time. So everybody talks about some different aspects of time. And my book, I try to disentangle the various pieces. So I think we make a mistake when we say time is this, or time is in fundamental physics, time is not in fundamental physics, time emerging this way, time's emerging that way. That's a mistake.

Time is a time of our experience. It's a very structured notion, layered. It has a direction, it has memory, it has a metric, it has a lot of properties that we bundle together in a single notion of time, but in nature, they come from different parts of nature. from thermodynamics, from the Newtonian approximation, from disregarding quantum gravity effect,

from our brain, because we remember the past. So the book tries to separate this different aspect of time, and I think then it's much more clear what this complex and mysterious thinks that Haim is actually emerges from the complexity of the natural world. Yeah, I recently reread a brief history of time, Stephen Hawking's magnum opus. And in addition, I came out just a year or two before he died, a third or fourth edition. And I had never really appreciated it when I read it when I was 16.

I couldn't really understand it. And it was very, it was beyond my appreciation. And now I come to it with the sophistication of a practicing physicist, a professor of 17 years at UC Cal, San Diego. and the comments that I would make on it was really startling in that it's really a book about God and his feelings about God, which startled and shocked me because he was known, of course, as a devout practicing atheist most of his life. He wrote many, many works on that, but actually the last word of his book is about God. And it's like, we would know the mind of God.

And he was always kind of mischievous, as you know, and you knew him, of course. but that his main purpose in that book was to present these different arguments, thermodynamic time, psychological time, biological time, and then the notion of time in physics. And I feel that he felt victim

to the very same thing that our friend the maestro, Galileo, fell victim to, which is what we call confirmation bias. I'm certainly used to this as well. But in the book, it's really a polemic about the no boundary proposal

in that he's trying in the number, 1980s to justify why the no boundary proposal is the right notion of how perhaps the origin of time itself emerges. I guess you can be more precise with your definition. But how time came about basically cleaving off from this abstract notion of space time becoming time itself, and that he viewed that as an invalidation of the two main reasons to have God. In other words, God was necessary to create time. And God was necessary. to create the universal laws of nature.

We'll get into that in a bit. But to Hawking, he could get rid of both of those, and therefore there'd be no need in physics for God. I wonder, why do you think, you know, religion and theology, why do you think it's so important to Hawking, who was an atheist in that, you know, he wrote one book called A Brief History of Time

to obviate the need for God to create time, but also he wrote his second, another book, The Grand Design, to establish that M theory gives the laws of nature. I assume you don't agree with that. I don't. Let me give your take first on the no boundary proposal. Do physicists take this seriously?

My belief is that they do not as a justification of how time itself began. What do you think? Oh, I think they do. Really? I mean, not as a solved problem, but that's one of the possible hypotheses, not the only one. If you use loop quantum gravity and you study the same problem, maybe what happened at the Big Bang, essentially. So you know very well, much better than me.

We understand the history of our universe pretty well for 13, 14 billion years in the past, but then we don't know what came before. And what came before requires quantum gravity, and quantum gravity has been the job of my life, of course. So to understand what come before, we need a quantum theory of gravity, and like loop quantum gravity is one. And Hawking had a tentative theory of quantum gravity, his Euclidean quantum gravity. So he tried to use it to see what happened.

And he came up with Jim Hartle, of course, with his idea that, in fact, you don't need time to exist in visibility. No, in fact, lupt quantum gravity seems to suggest something else. If you write equations, a sort of quantum gravitation equation, you run back on time, what you find is a big bang. you can continue easily and you find a previous contracting universe, a big bounce. So that's another possibility. It comes out from new quantum gravity, it comes also out from other ideas. We just don't know. I think we are going to know. I mean this is a simple scientific problem. Well simple, it's a difficult scientific problem, but the kind of scientific problem

that humankind struggled for a while and then souls. And it's possible that before the Big Bang there was a previous phase. In fact, I tend to favor it right now, but I mean, I've changed mine various times. But it's also possible that time started, what we call time, the cosmological time, started there. There's nothing contradictory now. There's nothing mysterious. You don't need God for that. In fact, God has nothing to do with that.

Let me tell you one thing. There was a beautiful conversation between the guy who first started thinking about this question, which is Le Maitre. Le Maitre, in French means the master, the master. But he was a very humble and marvelous scientist, one of great scientists. And he's the one who realized that Einstein theory really predicts a big bang and something quantum must happen there. And Dyrac, everybody knows Dierach. Dierach was an atheist. Le Maitre was a Catholic priest, so obviously a religious person and a believer in a god who create.

The two things being different, but he was both. And there's a beautiful conversation that it's reported by D'Iraq himself in a recollection of his conversation with Le Maitre, which D'Iraq sort of trying to be in kind. You know, D'Iraq was borderline autistic. It was not very good in social relations. But trying to be kind to Le Mette says, well, you did this great things in cosmology. It should be very close to your religious. Cosmology is the closest thing to religion.

And Le Maitre, the priest, the Catholic, the greatest cosmologist of the early times of cosmology, answer, not at all. Astrocosmology and religion have nothing to do with one another and then the Iraq asks a surprise and says so why do you say that is there are other sciences which are closer to religion and Le Mette the Catholic answers psychology okay and he's a believer and I think it's totally right I'm not a believer I'm an atheist I'm a serene happy without any doubt atheist but I think he's right

religion is not a bunch of stupid ideas at all. It's an intense experience that people have. It's a way of looking at the world. But if you want to understand what it has, if we want to understand it in scientific terms, which is possible, you have to look in your brain, how we work, how we think, how we conceptualize.

There's nothing to do with what happened 13 billion years ago. That's a scientific question. Yeah. When I read for the first time that La Maitra's ideas were first tried to be used by the Pope at that time to bolster the, you know, the creation Genesis. That's true. It's a fantastic story.

I mean, the Pope, this is a Pius 12, 9, I forgot. He gave some speeches saying, oh, the cosmologists are proving God because it's a big bang. This confirms the genesis. And Le Maitre, who is a much more intelligent person, run to Rome and try to talk the Pope out of that. And he succeeded. In fact, his point was just not confusing. This is nothing to do with, I mean, the history of the universe is nothing to do with God.

I mean, if there is anything interesting in the Genesis, it has to do with the personal experience of people, with what happened inside people, not the history of the world. And in fact, he convinced the Catholic Church. It's remarkable because other Christian denominations nowadays, still try to connect cosmology with theology. I think it's totally idiot. I mean, the Bible is absolutely nothing to do with what we know about the universe. Right, I always point out that the biblical, because I read Hebrew, I read Aramaic, I'm a practicing Jew, I'm not Orthodox, fundamentalist, but I am a practicing Jew, and I don't work on the Sabbath,

I take time, and you're right, the most meaningful thing, even from a religious point of view, people should note that there are 35 verses in the Torah in the Old Testament, as we call it the Torah, that involve plausibly some version of creation or creation of animals or people. So 35 verses out of 35,000 verses, so it's 0.1% of the entire book could be considered about the creation of the... I always say, like, imagine you picked up a book, and it was like, the title of the book was, like, great football players of 1975. And it's a thousand pages long, and there's only one page about football players.

And the rest, it's about, you know, like the Vietnam War. And if you feel like this book is not an accurate, it's like the people misconstrue the notion of wisdom and knowledge in that science means, and you can correct me, I'm sure you know Latin, much better than I do, but science means knowledge, not wisdom. And I think there are different things. And I think there's an attempt to reconcile and combine wisdom and knowledge from pure scientific fact. And I don't, I think that's a misapplication. And one thing that speaks about...

Oh, I don't think it's a misapplication. I think that we should not break our knowledge and our wisdom in pieces. I think we should keep them together. I don't think there are different levels of our thing in the world. I think that that's a mistake. We learn things from science. Science, it's a great tool. Of course, I mean, we're humans with humans concerned.

There are a lot of things about ourselves that we don't understand. If we, but we shouldn't, the mistake is to mix different parts of our knowledge. I think that our, how would you say, spiritual or whatever, our worldview should be deeply informed by science. You change because of science, because we learn. I mean, when we learn Darwin, when we learn Copernicus, when we learn Einstein, or when we learn or quantum mechanics, we change our view of the world, and I try to talk about my books about all that. And this changes our view of ourselves also. I don't believe in the ancient wisdom at all. I don't think that we find great wisdom in old books, because old books are

old books. What's the good of old books is that a lot of people have been talking about them over and over, so we don't read the book. We read the stratification of commentaries, and if you If you read the Torah, you know what I mean. And that's interesting, but it's also a lot of, you know, going back to wrong ideas. So I think that we can, science is complex, but science can include the science of you, ourselves. And it can include understanding of our values, our emotions, our... Morality? Yes, and our sense of why we live.

and namely what we want from ourselves or what we fear, we shouldn't separate wisdom and science. Of course, we should separate what we want in life from the cosmology of the Big Bang. These are two different stories. It's like, you know, it's my furnace broken. That's a problem. It's my girlfriend happy.

That's a totally different problem. I mean, this is a, it should mix these two problems. But we are the same. And in my science, in my philosophy, in my life, I try to bring things together. I work in loop quantum gravity. It's a very specific problem. It brings to a rethinking of space, a rethinking of time. I want this rethinking to stay together with the way I think about myself.

Hope you're enjoying this episode of the Into the Impossible podcast, wherever you may be listening to it. I hope if you are listening to it via the iTunes platform, if you will leave me a small asterism, a constellation of stars ranging from one to five, but please let it be closer to five. That will help me so much in the algorithm. We hear about algorithms and we talk about algorithms, but Apple's one really defined by how many reviews and comments these channels get. So I read each and every one.

I am just so thrilled and such a treat to get reviews. by people. Here's one I just recently got. In fact, today from Jake Enderman, who wrote this podcast is so much fun. It's great brain food. Maybe he meant Brian food. So Brian tackles heavy subjects and deep questions with his truly amazing guess. He's not afraid to respectfully challenge them. That's true. And it's also a great way to get your kiddos introduced to some heavy concepts. Thank you so much, Jake. It is my goal to get people interested and share my passion with physics and the universe and great ideas. So stay tuned. We've got many more great episodes. I hope you'll continue to enjoy this episode and many, many more to come. I see that in your writing. It's it is not just

in its prose, which is poetic and beautiful, but that is sort of a vector, a delivery mechanism. You know, we're in this age of viruses and so forth. But you can infect in a good way, the reader with beautiful prose for he or she may not understand the depths of the science. And actually, them opportunities to skip ahead, skip back as is necessary. But I guess, you know, the fundamental thing for me is, is that there is sort of a halo effect. You know, for example, Einstein was asked to be the, you know, the second prime minister of Israel. Now, the man had very, very baroque notions about nationalism and so forth. And, you know, because he knew a lot about Brownian motion, and he knew a lot about the photoelectric effect and gravity and time, but you and I both know,

he had, you know, seven major discoveries, each worthy of a Nobel Prize. Yes. And he had seven major blunders, each worthy of an Ig Nobel Prize in some sense. Oh, yes, yes, yes. I wrote a paper on the list of mistakes of Einstein. Oh, really? Oh, really? I want to link to that afterwards. Oh, yeah, yeah, yeah.

I could say more than that. I think Einstein is not one of the, I mean, maybe the, without maybe, the scientists who have got more right things in his life, at least, I mean, after Newton. But he's also, of all the scientists I know, the one who has more mistakes. Yes, like Babe Ruth, the famous home-run hitter. I mean, mathematical mistakes, a conceptual mistake, assumptions which are wrong, mistakes that he himself recognized. He changed his mind, various times back and forth.

Some he corrected some know. You know what? I think the two things go together. Yeah. It's a sign of intelligence, changing your mind. So I tell my string theory, friends, you know, change your mind. It's a sign of intelligence. Yeah, I always ask the question, you know, before I debate with somebody, as Galileo does in this great book, this book is a book about debates. It's a debate between three people whose names you can pronounce better than my Simplicio Salviati and Sagredo.

Fantastic. You know, I also wrote a debate with the same characters. Oh, you did. Oh, you must give it to me. So now you're basically agreeing to be a part of this project to transatlantic. like Galileo in audio form. Imagine that. Imagine Benedict Cumberbatch reading Simplicio.

I don't know. We'll get some ideas from you, Carlo. But I think you're right. And in America, I don't know if you're familiar from your time spent here, but we have famous baseball heroes. And one of whom was Babe Ruth, who was one of the greatest players of all time.

He could pitch the ball, you know, incredibly fast. He could hit more home runs, but he struck out more than any other player. But he also hit more home runs than any other player. And he's sort of, you know, the Einstein of baseball, I suppose. say. But it kind of brings you back to what you said about La Maitre. I mean, this guy is remarkable

the matre because he resisted the insults, the daggers, the barbs of Einstein who called his misapplication of GR atrocious, despicable. You know, Einstein was brutal to him. And the matro was just this happy kind of cherub. And he was just like, I let me tell you my view, by view of Lebetra. So he went to the Pope and said, oh, Pope, you are wrong in trying to connect the genesis of the Big Bang, and he actually convinced the Pope, right? The Pope follower. And he went to Einstein,

when Einstein, as you said, was, and said, Einstein, you were wrong. And Le Mette was right. I mean, in the 30s after Hubble and so on, Einstein changes his idea. So, I mean, it's not a thing of nothing, of, you know, the same person going to the Pope and finding it wrong, and the Pope agreeing,

and going to Einstein and finding wrong, nice and agreeing, it's quite an achievement. And not only that, the most wonderful things about Lemaitre is how humble he was. You know, in the paper, all the credit about the Expansual Universe nowadays goes to Hubble,

to Hubble, which of course has played a huge game. But the paper by Le Maitre has already the idea, has already the analysis of the first observation of the red shift of the Nebulae before a humble measurement and has already the humble law, essentially. But then something incredible happened. When this paper was translated in English, much later, because it was not in the English literature, he put it in an obscure little journal, he himself took away the part that made clear

that he was the first one to read the data correctly because he said, well, how about that are so much better than mine that is no point in it? So you see, he didn't care. He cared about truth, not about his own personality. And this is wonderful. I wish scientists would be like that today. I know some that are like that, some not at all like that. Let's get into that because I find it very interesting.

I get emails every day and some people are listening to this podcast. you know, friends of mine that will be listening to this, watching this on YouTube and listening to this on the podcast form. And they'll send me their theories of everything, and they're very earnest. And they'll usually say things like Professor Keating, I'm sure you get these, Carlo. Einstein was wrong.

You know, I know that there's a theory of quantum gravity that he failed to do. But I'm not good at math. So if you help me do it, I'll split the Nobel Prize proceeds. They'll never split the medal with me. And I claim in my book that that's a form of modern-day idol. worship in the sense that people worship the Nobel Prize and, in fact, refer to it so much that it's become sort of a secular religion. But we'll get into that some other time. Anyway, I get these

comments, but I never get comments. Boltzman was wrong. Clousius was wrong. Why is it that Einstein is this target? You know, I think the Italians say, you know, the higher you fly, the easier you are to shoot down or revenge is the best dish, best serve cult. I don't know. But tell me, Carla, why is this fixation with a man? Why shouldn't it be with the ideas? Why are we always? so consumed with taking, you know, Einstein was wrong or I can do what Einstein didn't do, and I can do, you know, this or that, why not say, here's an idea, it's for the universe? Why is it the fixation with the man or the woman in some cases? Well, we're humans. We have our weaknesses. We have ego and all that stuff.

But ideas are more intensely. Let's talk about ideas instead of talking about God and human, and let's think about quantum gravity and look at quantum gravity. I'm going to see how human you are in this. Okay, so I'm going to say something by a quote. Again, I don't like to venerate people just because they have Nobel Prizes. But the famous Richard Feynman said the following. He said, I don't care how beautiful your theory is, how lovely the math is. If it disagrees with the experiment, it's wrong.

Absolutely. I want to ask you, in the context of loop chromium gravity, there was a claim that there would be a variability of the speed of light depending on its energy. and it's called this dispersion. Its energy would be dependent, its propagation speed. Effectively, an index of refraction would be color dependent. And that was a prediction of luke quantum gravity.

No, that was a mistake. That was a stage in which the dynamics of luquantan gravity was not clear and yet. This was many, many years ago. So at the time, there was only the Hamiltonian formulation. So it was much, much harder to see whether quantum gravity actually implemented a local loyalty variance invariants, which is the one of generativity, the symmetry of space-time and spatial activity.

Later on it became clear, especially with a covariant of emulation of luke quantum gravity. It's called spin-form, sort of fine and some of it geometries in between, which you can do explicitly loop quantum gravity. It became clear that the theory is locally lawrence invariant, so it doesn't break Lawrence-in-Variance. So there's no preferred reference system, if you want. So then the claim disappeared. But that was very good because there were various suggestions at the time, and it prompted an astrophysical research, in fact, a large number of astronomical research for violations

of Lawrence Bargans, for seeing if in fact one can see a phenomenon that break the symmetry of special relativity. And this was successful because nowadays we have a lot of bounds on this effect. So nature seemed to be a law and invariant in many phenomena far beyond the Planck scale. So this is one of the example in which people say there are no experiment in quantum gravity. There are experiment in quantum gravity. That's one. And in fact there were theories of quantum gravity like OJava theory and other theories which were

trying to build the theory itself on the breaking of Lawrence invariants of the Planck scale. And these are largely ruled out. I mean, you never really rule out anything in science. I mean, the proper story is a little bit mythical. But they are very much in difficulty because of these experiences. quantum gravity, on the other hand, I mean, it's theoretical development, has been, has clarified that the dynamics is a lawrence environment, so there is no breaking a Lawrence environment expected.

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Live only on Netflix. Saturday, May 16th at 9 p.m. Eastern Center time, 6 p.m. Pacific time. Would there be, you might be aware of a recent claim, discovery using Planck 2018 data, of an observation of evidence or hint at 2.4 Sigma, which sounds less impressive than 90, 9.2% confidence, but they're the same thing, that their universe exhibits cosmic parity

violation via Chern-Simon's additional term to the electromagnetic Lagrangian. This is by Ichirokamatsu, who's a friend and colleague, and his colleague, who's also a colleague, Yuto Miyamori, who works on the polar bear experiment with me and my team. But they claim that the photons, cosmic polarization photons rotate as they travel from the last gathering surface to the earth. And it made me think of a potential probe that I want to pitch to the Ravelli funding agency, which would be looking for parity violating signatures, or maybe even, maybe less broke than that, just looking for a time of flight difference between vertical polarization of distance sources and horizontal polarized light and their

propagation. And when we see them from a gamma ray burst or from a supernova, it's actually not well known. I've had conversations with some of the top supernova physicist Robert Kirchner, my late colleague Andy Friedman here, about testing Lorentz invariance violation and parity violation using time of arrival from supernova

of vertical and horizontal polarization. Is there any test analogous to the speed of light for red and blue photons, for example, is there any test like I'm proposing that could have some discriminating power for LQG?

I'm not aware of anything specific of that in the literature, but I wouldn't exclude that. Like, I mean, if you, nowadays, if you tell me about breaking a Lawrence invariance, you know, everything is possible, but that's not everything possible is interesting. But parity or chirality in nature, I mean, we know that nature is carrel, and we know that nature treats left and right differently. And if you remember, loop quantum gravity was both. The action of loop quantum gravity is not exactly the generativity action. There's another term that has no effect in the classical theory,

but has an effect in quantum theory. It's called the whole term with a parameter which goes on the name of Berberianzzi parameter, which has the opposite parity, if you want, as an epsilon inside. And the old... Luke Cantorquitt was born on a formalism that treats the two opposite chyralities differently. So I wouldn't be surprised if something could happen. I mean, I think it's a very interesting direction to explore.

It has not been explored sufficient... There are some papers, but I don't think it has explored very much in the literature. Remember Smolin and what's his name Juan? Gajer, McGajor. Yeah. They were trying to explore something in that direction. They were excited at some point. But the way I understand loop quantum gravity today,

loop quantum gravity is a very, the way understand it, it's a very, I would say, it's not a theory of everything, it's not a grandiose thing, but it's very well defined. I mean, it has very clear, hithu space, very clear evolution. equations. So it's a theory of quantum gravity. We don't know if it is right, because until we make

a successful prediction, we cannot say this is right. But I think it proves that a theory of quantum gravity can be written and is there. It's finite, an ultraviolet divergences. And in it, the way it is, I don't see it, carality breaking, this effect that you're, you're, you're, you're, you, I mean, this effect that you're saying, but I wouldn't exclude that it might come in exactly because there's this other term, which is in a possible signature. Yeah, when I, I want to get to possible tests under the strong gravitational regime of colliding black holes in a minute, but before we get there, I want to take one step back for the audience who may be getting a little bit lost, but, but probably not because they're

They're very astute. We've had on Frank Wilcheck, Juan Maldesana, Martin Reese. We've had on the top luminaries in this field. And I always ask them, and Sir Roger Penrose has been on four times, including after he won his Nobel Prize. And I asked him at that time in conversation with him about black holes. And here's the following thing. Let me run this by you. I feel like the quantum gravity argument is sort of this Oroboros, this snake that eats its tail.

almost like a tautology. In that, we say we need a quantum theory of gravity to understand the properties of black holes within their event horizons, near singularities, and strong gravitational fields. We also say we need it to explain the origin of time, if indeed time had an origin in a quantum sense, in a big bang, in inflation, something like this. We need to have, now, both of those, as Hawking himself proved for both of those fields, we are fundamentally firewalled off. never observe a singularity. We don't believe there are naked singularities. We don't believe we can observe what's inside of an event horizon and get that information out. So it's sort of firewalled off. Conversely, the beginning of the universe, when time, as you point out, how does time pass when

time comes into existence in a certain sense? So we may, and Hawking showed that there would be this singularity along with Penrose, and I asked this of Roger. And I said, so there are these two scenarios, we say we need quantum gravity, and yet we can't observe quantum gravitational effects. What do you say? Is this a tautology? Is there any other reason that we believe we must have a quantum theory of gravity? I mean, who says that we have a quantum theory of gravity? Why do we need it? No, I disagree. I disagree entirely. And black holes are a good example. Because let me tell you what loop quantum gravity predicts about black holes. This is a fact, the main sort of hard science in which I'm working right now, last night I was up until

very late trying to do and not succeeding, to do a calculation. You've got to get time in order. I have to get the order of time right. Right. That book should have been titled The Disorder of Time. But anyway, that's a different story. So if you take the question of Luke Antogal, This has been done in a number of different ways.

I mean, different luke quantum gravity formalism. So it seemed to be pretty, pretty solid as a prediction of lukewarm gravity. If you fall into a black hole, you have the equations. You see what happened. You go to the center. At the center, the curvature increases. So you enter the quantum gravity regime. You do the calculation.

And you discover that you continue in a region, which has a geometry, not of the inside of a black hole, but inside of the white hole, which is a well-known solution of Einstein equations as well. And if you look at the thing from the outside, the black hole for the outside, what you see is that there is hokely radiation, so it becomes smaller, smaller, smaller. Some point is very small, so there is the horizon. And then when it's sufficient it is small, there's a quantum transition, a tunneling effect that transform it from a black hole horizon to a white hole horizon. And this is compatible with the Einstein, classical Einstein theories, equations outside.

So, therefore, now you have a white hole. You've gone through this quantum phases, a tunneling, like the standard quantum tunneling, a particle that goes through a potential wall. It's the same phenomenon. So the black hole has become a white hole. So whatever is inside comes out and easily comes out. In fact, it has to come out because it is a white hole. Now, I was sure that this is what nature has decided.

Well, no, of course, because we're not sure that the quantum gravity is correct. But that's a scenario, it's a possible scenario. And in fact, I think it's a reasonable scenario. I think that the idea that people have that the end of the black hole evaporation, a white hole, a black hole disappears into nothing is silly. There's no theory that says it's appearing to nothing. What it does is to tunnel into a white hole and inside, you see, A small old black holes, which is a teeny, teeny mouth, tiny horizon.

But inside is a huge, huge, huge thing inside. So you don't disappear into nothing. It passes a quantum region and then it comes out from the small mouth. So therefore, we do see the quantum gravity region. Of course we do see the quantum gravity region is whatever comes out. And there is no reason whatsoever for thinking, that is hidden. In other words,

the horizons exist. You know, Hawkins once wrote a paper saying there are no black holes. It's sort of butad, but I think it's a, he was playing on the definition of black hole. If you define a black hole as an event horizon,

then I don't think there are black holes. Because an eventorizon is horizon survives all the way to infinity. But horizon don't survive all the way to infinity. There's nothing forever in life. Quantum mechanics changes things. So the horizon of the black hole, the real black holes we see in the sky, it's a trapping horizon. The correct notion that Roger Penn also got a Nobel Prize for this introduced.

So it's an horizon. You cannot come out from there, but it's not something that lasts forever because it's quantum gravity. Right. Right. So when it becomes small, it becomes a white hole. And if you want, a white hole has a single. in the past, the black hole is a singularity in the future, but singularities are just what happened when you enter in a quantum gravity region in generativity.

So you enter into this quantum gravity, there are no singularities. The theory is not being able to continue because something else is coming in, and we know what comes in. It's quantum mechanics. So the black hole singularity, it's actually a quantum transition to a white hole singularity, which is just whatever comes out, and then you see what comes out. The argument is hidden behind an inventorizer. I think it's wrong. So that we won't.

All right, so that it is possible. Now are there ways, as you know, probably Sabina Hassanfelder and others who's been a guest on the show, she claims that the hawking, well, the information loss paradox, which would be leading to the resulting emission of hawking radiation or concomitant reorganization, perhaps destruction of it. I've had John Prescoe on as well. She calls it one of the greatest hypes in all of science, you know, that this is not really a paradox. And in any case, it's unavoidable, unobservable because we, you know, hawking radiation, it won't occur for, you know, millennia to the millennia power. So how do we, how do we go about, again, you know,

adhering to Feynman? I ask this of John Prescott. If you're saying, you know, hawking radiation, you, you won this bet. Okay. But, Do you really know if you won this bet? Because we won't actually be around to witness these types of phenomena. So, Feynman, and by the way. How do you know? Well, you know, that we'll witness hawking radiation. I mean, the timescales are, you know, for a large enough black hole are, you know, longer.

How do you know they aren't small black holes? Well, we don't have any, currently don't have any evidence. I don't know for sure that we don't have. We didn't have evidence of black holes, big black holes, 20 years ago. It doesn't mean that they didn't exist. didn't mean that they didn't. Yeah, I'm not saying that they don't exist. I'm saying the...

This is sort of wild speculation. It's just a solution of icing equation. I mean, they could very well be there. In fact, there is a lot of work on the possibility that, you know, small black holes were produced in the early universe, the primordial universe. You should be a will. I'm sure you know about that, right?

You're closer to your job at mine. Yeah, yeah. No, and certainly we are, and we think about that. So it may very well be that there are small black holes in the early universe which were produced. We don't know because it's a tricky, complicated story, calculation, depending on many details. But it's very plausible. And I think, look, when I was a student, I studied on Stephen Weinberg, fantastic book on generativity,

which essentially says, come on, black holes don't exist in reality. It's very unlikely that they exist. He talks about the steady state theory, too. Yeah, it's interesting. No, no, I mean, he has a chapter on the mathematics. is completely clear, completely. And then he says, look, to make a black hole, you should squeeze the earth in a centimeter cube.

Come on, this is not going to happen in the nature. But nature is more creative than even the Stephen Bindberg. It's a great scientist. And in fact, in those years, the first indication of black hole seria were coming out, right? The 70s, the 70s, the 70s, 23, when it's sinus. And now we are totally sure that things in the sky exist, which are well described by the most. mathematics of generativity in black holes.

But we first find the stellar ones, and then to our surprise, we said they were the galactic one, which in fact we were receiving signals by decades, we didn't know what they were, and then we find billions of solar times, and then we find the intermediate ones. I mean, we are discovering new kinds of black holes every day. So I think it's perfectly plausible that there are black holes, I don't know, but it's perfectly plausible that there are black holes producing the early universe, or, or, you know, or even if there was a bounce instead of a big bang from previous phases of the universe. Black Hawk can easily go through the bounce.

That's hawking. Those are a hawking points that Sir Roger. Yeah, yeah, this is a... Although in that case, I did falsify that to him. I mean, the actual publication, and he and I have been over this, he's a good friend of mine, that the hawking points, again, I felt were another example of confirmation bias rearing its ugly head, because essentially what he did is take the Bicep 2 data that we released and just analyze the maps and show where regions were high, you know,

an apparent visual impact. In other words, he looked at these maps and said, oh, they must be points of high B mode concentration. And that was totally not the way that the maps are intended any more than an artist's conception is intended to give you a perspective of what a black hole looks like. But I feel like, yeah, that is a notion.

I want to ask you now about gravity in the strong, or quantum, you know, gravity, LQG, in a strong gravitational field because it seems to me, I had this conversation with Lenny Susskin about a month or two ago. he believes that the, you know, what he calls the stretched horizon or something is more quantum mechanical than the singularity in that.

I think it's wrong. I think he's wrong. Okay, why? Because let me, this is, this is in fact the same question you asked me before about the information loss paradox. Let me be a little bit more precise here. I think some of your audiences, it's well-versed in these things and we can go a little bit in more detail.

The information loss paradox, it adds. actually comes into versions. The naive one and the subtle one. The naive one is, well, things, information falls into a black hole, and then the black hole disappear where it is gone. But that's a naive one, and the solution is very simple. I mean, it will just come out later on. You go through a quantum gravity region.

But then there is a subtle one, which is the one that is being discussed today, and is what everybody really today calls the information loss paradox. And this is the idea that the paradox is not actually. after the end of the evaporation, it's before. Okay? And this comes from this argument by page. In fact, then there was a cleaner version that when a black hole becomes small, okay,

if you believe the Beckenstein idea that the number of state of black hole is limited by the area of its horizon, then there are few possible state of a black hole. Black hole is small now, so it can have few possible state. Therefore, there's not enough room for information inside because you need a lot of states to hold information.

Therefore, when the black hole is become very small, the information that is inside should have already come out. And this is what a lot of people today believe, and I am convinced that this is gone. Because of loop chronic gravity? No, no, no, not because of loop chronic gravity. It's a logic point. These people have been blinded,

and I think they are blinded by taking, by overplaying holography. They, fell in love with holography, they found ADF, CFT corresponding that somehow seems to be connecting a boundary theory with the internal theory. So they believe holography blindly more than established physics. A lograph is not established physics. It's an hypothesis, right? So it's not like saying, the Axel-C-F-T-E-S-E-E-X-E-Qaeda, quantum mechanics, class. mechanical mechanics. This is correct within its own domain, along that it's an hypothesis. And it's not a clear hypothesis. This is a vague hypothesis. It can play in different ways. In some

sense, it's true, for sure. It's easy to prove. In some sense, it's an hypothesis. Some sense is speculation. But now it has become a dogma. If you take this as a dogma, that's a mistake. Then you think that all the observables are at infinity. All you can say about the world you can say from outside. So about the black hole, you imagine a black hole or something that lasts forever, and anything can measure it's on the surface and there's little number of degrees of freedom. But you forget one thing, and that's a key point, that inside this small surface, there can be a huge volume and all sort of possible quantum state inside, information inside.

So this is a confusion between two notions of entropy. The entropy that governs my exchanges from the outside with this thing, this is a black hole. Black hole is small, has a small horizon, small area. So it's entropy for me, it's limited. But this doesn't mean that the internal state with whom I can be entangled can't be large. And in fact, it is large. Just a simple, just look, go into the equation, believe generativity, believe quantum mechanics, believe Philtheree tells you that inside there's a huge amount of information.

So it's false and is dictated by this falling in love with the holography, is false that the information comes out before the quantum gravity regime. It's false that the late Hawking Quanta must necessarily be entangled with early Hawking Quanta, which is what people got sort of enchanted. enchanted into believing. And if you're enchanted to believe in there, you come out with all the nonsense, like the firewalls on the horizon, like this idea that there is some crazy quantum stuff on the horizon. I mean, I'm a relativist. I've spent my life in relativity. There's nothing special happening on the surface of a black hole locally. If you're in a small region, it's a completely natural. If it is special, it's just your perspective. You're sort of, there's a little curvature there. You're zooming. to a even in this stretch horizon

which is crazy even in what Lenny calls it he says you know the thermal background and the stretched horizon which is a plank length above the event horizon

apparently but he calls it the most quantum of all phenomena and so it's surprised I agree with you and I had Juan Maldesana on the show

and I asked them specifically I said what is the value of ADS CFT it works only in five dimensions I mean it's one of the few things we do know and he said well the value

of it is in part because it teaches us about quantum mechanics. And I said... It doesn't. It teaches us as an a version of quantum mechanics that is not the one that might be true in our world. Yeah. If these people are so crazy about this idea,

why then don't do a realistic theory? Instead of doing unrealistic theories, which they know they're unrealistic theory, they say it's unrealistic theory, and they say, yeah, but the true quantum theory of gravity should resemble that the day we're going to find it. Well, find it. might be wrong, it might be ugly, it might be spectacularly beautiful in my eyes.

It might have incomplete pieces. I'm not saying it's perfect size. Far from me. But there's a theory. I mean, we know the equation, the fundamental equation. You can write them down, totally clear. There's no space, fundamental. There's no time.

They're quantum space. You can write the transition in four-dimension. There's no supersymmetry. There is no holography in some sense, in a weak sense. There's a holograph in fact. but it's a weak sense, not in this strong sense, and it allows you to do calculations in quantum gravity. So we do have a quantum theory of gravity.

There is a quantum theory of gravity. Perhaps it's wrong. Perhaps I'm going to change my mind. I mean, say, oh, this equation don't work. Fine, we'll change them. Einstein changed the equation of generativity five or six times before writing the group of the good one. So fine, I mean, just Einstein changed.

I'm going to change. Everybody should change. But we have a theory which is realistic, which is consistent with the theory with quantum mechanics, consistent with general relativity, and there is no information problem. And, you know, Sabine, I sometimes I disagree with her. Sometimes I find her she has strong mind, a strong opinion, but I think she's totally right. I see another thing she said.

She's totally on the point here. It's just hype. Yeah. And I wonder, you know, why we give into that. And you mentioned, you know, about why don't they do calculations that are practical with ADS CFT. So I asked Juan exactly that.

And he said, well, this paper that he wanted to talk about is about a humanly traversable wormhole. Okay,

so that's a reasonable thing. And you know, Juan, of all this group, is one of the more reasonables. Yes, he is. He is extremely.

And I asked Kamran Vafa the questions I'll ask. He's kind. Yes, I do have his ilk. No, I love Juan.

He's incredibly generous. And we have on, you know, I am an experimentalist. So I look for experiments of everything. I want to know as much information in the limited amount of time I have

to pay attention, to do work, to love, to do all the things. I wish, I wish I could do more. I could give you more on that. You know, to find experiments, I mean, my hope is to, before dying, to see a confirmation of quantum gravity, a support of loop quantum gravity. Something coming in.

There's a lot of attempt in the CNB, okay? I try to connect the loop-quant gravity picture of the early, of the primordial universe with CNB anomalies. But it's a lot of work. I've not worked on that, but there's a large literature. I am more confident in black holes. And, you know, I, there have been papers on signature on very high energy cosmic rays.

Let me give you the gist of the idea here. If a black hole forms in the early universe, let's say after the Big Bank, it traps some very high-energy photons inside. It's small enough, it evaporates, it liberate this high-energy photon. This high-energy photon flies and gets to us. This is one of the primordial high-energy photons. If you do the calculation, the spectrum of these things and the distance frequency, dependency dependence is very peculiar because of this phenomenon. And this might leave in prints in their distribution or stuff.

That's one idea. There are papers. Will it be done? I don't know. I'm waiting. You probably know that at some point faster at your birth where there was a hope to connect it. I mean, I don't know how strong it is.

I think I'm less of believer that this could happen, but it's not closed them. And then I have my own favorite idea. I wish I could give you, which is dark matter. How so? Dark matter, the best picture we have of dark matter right now is that it's something that interact only gravitationally. It's a sort of powder which has no electromagnetic decent interaction. It's sort of flying around, there's a little bit, the sort of density of roughly inside

the galaxies like matter, even a little more, but not concentrated in stars. Now, suppose there were this primordial black holes, and they have evaporated, they become white holes. And white holes, according to the model we have, have a very, very long survival time before ending, because all the thing inside should slowly come out. So white holes are a little thing. What's the size of a black hole? It's a microgram.

Plank scale is a microgram. It's huge from the point of view of particle physics. It's very small from the point of view of your point of view. It's just a powder. And how does it interact only gravitationally? It's neutral. I mean, this could be a component of dark matter. Do I have a way to test it?

No, unfortunately. So every time the other components are shoot down or lose credibility, you know, like the supersymmetry one. I mean, is there anybody who still believe in supersymmetry in the planet? I interviewed Sheldon Glashow last year. And I said, you know, in your book, because he wrote a book called Interactions, and he forecasted, you know, where could physics go in the next 10 years? And this was in 1988.

And basically nothing had been seen, you know, including proton decay, including, you know, signatures at the super connecting supercollider, which was never built, but he didn't know it at the time. And, you know, so I started to ask him, you know, well, does this not mean that super symmetry is ruled out? And I thought he was one of the foremost opponents of string theory. And he said, no, not at all. And he seemed to be much more sanguine about the, uh, you know,

You know, possibility that string theory could be manifest, but not as much as my friend and yours Kamran Vafa. We'll get to why I say that later on and I take you into the impossible with the three questions that I ask all my guests. Now, take a quick break to just implore people. If you're liking this video, this conversation, please leave a thumbs up and subscribe to the channel. Please leave a review or follow me. Whatever you have to do. Follow Carlo. He's not super active on Twitter, which explains why he's so active. I'll put up his Twitter. handle why he gets so much done in writing, in physics, et cetera. But just to go back to the notion of testability, when I talk to Lenny Susskin, by the way,

I have on many more theorists than experimentalists, although I have had on Barry Barish and Ray Weiss, speaking of Black Hole physics, and Kip Thorne has promised me he'll come on one of these days when COVID is over. I think he's just like passing me off, but he's so productive. He says he's so productive, and it echoes a little what you were saying before we started recording. Now, COVID's been great in the sense, you know, it's been tragic for billion, millions around the world. But, but it's been good for productivity for people like Kip Thorne. He's like, I'm not, I'm turning down every interview request. I'm working on books. I'm

working on papers. It's never been so productive. I should do that. I should do that. I'll let you off in a couple minutes. Don't worry, Carla. No, no, no, no. Come on. It's lovely. It's great to talk to you. Yeah. So I, but I talk to Barry and I talk to Ray Weiss. And I said, you know, what are the exciting things that you can do with future experiments? And they started talking about, yeah, you could test quantum gravity. In particular, I wonder from the LQ, LQ perspective, is not black hole, the, you know, colliding black hole with 30 solar masses each, is that not the ideal laboratory? In other words, when people say to me, we need the future circular collider, which is going to cause 20 billion euros to build, not to operate, just to... I'm not a fan of colliders.

I mean, I don't want to make a strong point here. I don't know, but for the kind of physics I do, it's not colliders we need. And that's, I mean, look, the ruling out of some quantum theory of gravity with breaking a Lawrence invariance of the Planck scale was not done by Collider. You mentioned proton decay. Proton decay was a great experiment, right?

You ruled out as you five. It's an effect at sort of two-oldings, of magnitude of the Planck Energy, much, much higher than any collider could even dream to get there. And it was now, yeah, a big tank of water and some detectors around. So smashing particles is not the only way. It's a good way, but it's not the only way to test nature. There are other things. I mean, there is cosmology is fantastic.

Astronom is fantastic. Gravitational wave detection is fantastic. There are a lot of things. That's what I say. Let me tell you one thing, because there is a quantum gravity experiment, which is being much discussed now in some corner of the community, which can be done in a lab.

Talk about it. And I think it's extremely solid, it's extremely good, it's not easy to do, but it's not impossible in a few number of years. It's not a quantum gravity experiment that is going to distinguish whether Luke quantum gravity is true or string theory is true

or whatever it's true. But it would definitely put, create a superposition of geometries in the the lab. And it's a fantastic experiment. It was suggested by two groups, contemporary at the same time, one in London, Sugato Borza and his collaborators, and Carameletto Vidal in Oxford. And it's a fantastic idea. You take it in a nanoparticle, you split it in two, like a Stenggerlach. You take another one, you split it in two. So you have four branches. And in one of these two branches, you have

the two particles be very, very close. Okay. They're so close by that they affect gravitationally one another. So there is a different phase in the quantum evolution in that particular branch but not in the others.

So you deface that branch and when you bring together the two particles, they are correlated. The quantum correlated. So do you create quantum entanglement via a very weak, delicate gravitational interaction? Okay, and if you do that, you can prove that this can only happen if gravity itself, namely geometry itself, is in a quantum superposition. So this will be, in my opinion, solid proof, I bet that the results, if the experiment can be done, the results are going to be positive.

Yeah. Solid proof that quantum geometry exists, that geometry is not fixed, that you can put geometry in quantum superposition. So you see, one, quantum gravity experiments, are possible. I mean, the astrophysical measurement of the Planco violation of Florence invariants, this experiment in the lab, if you want the non-finding of supersymmetry at CERN, which threw many people in desperation. You know, physics is in crisis. Yes, the tension. There's no, it's in crisis. I mean, the physicists are like, man, we're rejoining.

We spent years and years saying, come on, supersymmetry, who believes that? A lot. A lot of people believe it still. We've had honest. A lot of people believe it still, but, you know, a lot of people believed in the autonomy system here, 100 years of the Copernicus. I don't know. I mean, supersymmity might be true. It's not ruled out totally, but science doesn't work ruling out things totally. It makes things more plausible or more unclosable.

Well, it's the whole consensus is science, you know, proving it by the number of authors on a paper. etc. that I objected. Let me ask you a question though, because when Bicep 2 made our announcement in 2014. Yeah, I remember. I'm sorry. Yeah, no, it's okay. I mean, we learned more about the universe. We learned about truth. Oh, yeah, we did. We did. At that time, Lawrence Krauss and Frank Wilczek, you know, had come with a paper that said, we have, you know, prove quantum gravity, evidence for quantum gravity in the inflaton, in the quantization of gravitational wave. And I thought that was nonsensical. I actually told Frank that on the show, and we didn't, we didn't get into too much detail about it, because Bicep 2 turned out to be a non-confirmation, just confirmed, as you know.

Yeah, I thought about that. I thought about that. It's a very good question, yes. So you're asking me, would it be, if we were successful? Suppose we had observed it. Yes. Which, you know, the fact might still be there. The fact we haven't observed doesn't mean that doesn't take on it. I still have a $100 million project behind me. That's right. That's right. So can we say, It's evidence for quantum gravity. I think I would incline in your side. It's a bit stretched. Yeah.

The experiment that you mentioned is, you know, what I call quantum, and I love your next book, has a lot to say about this. We'll talk very briefly about it because I want to have you back if you'll be so generous with your time in the future. But the point is, you know, what is quantum? What does it mean? Well, people think about the double slit experiment. People think about, you know, the interference, the reality of phase,

Aharana Bome effects, et cetera. What do you make about these new, you know, kind of conjectures? Sean Carroll has spoken a lot of your friend. Sean Carroll has spoken a lot about, you know, many worlds. And, I mean, where do you come down on that? Is there any impact, you know, because I think ultimately what I'd love to talk to you about today is get a better understanding of the role of entropy within L, LQG, in the sense that, you know, when I'm a lay person, I'm a simple experimentalist, right?

So I only can remember certain bullet points at a time. And what I think about is space time is quantized at a certain loop scale. There's spin network, spin foams. I can understand those. I can't do the calculations, but I can understand metaphorically what they mean and physically what they mean. I can even think about tests as I've already described and how we could perhaps measure it. But things like when you talk about holography and so forth, I would have thought you

would be a proponent of it because at some level, don't you say that there is a fundamental unit of quantum area, of volume, of pixel? of voxels in LQC, in LQG. How does it work? Yeah. Is that not the most quantum manifestation of quantum mechanics there is? Space-time itself is quantized.

Yes, yes. Well, first of all, you're not a simple experimentalist. You're a great experimentalist. That's the main result of loop quantum gravity. Not an input, it's not an assumption, is a result. I am a, you know, I don't, I don't believe that space and time exists as they are. I believe that in a very strange theory,

but I'm a very conservative person. I don't believe in a lot of speculations. I think that we should build on what we understand about the world. And if you take generativity, what we have understood about generativity, namely that the space time, the geometry of space time is the gravitational field. It's the same thing.

So we shouldn't think about space and stuff over it. We should swing at the gravitational field and the electromagnetic field and the Dirac field and the the young mills fields Because that's one thing we know and the other thing we know is quantum mechanics Quantum mechanics is incredibly Powerful. I mean it's 100 years that it just Comes out right maybe one day we'll find it wrong, but it will come I mean for the moment until we find it wrong we we better assume our best bet by far is the same is right So if you take the two together

That's you get loop quantum gravity It's just that. It's a quantum theory of generality of space time, which is the gravitational field. But the gravitational field now is a quantum field. So you can make measurement of the gravitational field and predict what you come out. And in quantum mechanics, make measurement and predict what will come out means finding the eigenvalues of observables, right? The energy of the atom, you compute the eigen values of the energy.

And often they come out discrete. energy of an hydrogen atom, of monic oscillator is discrete. The angular momentum of something rotating is discrete. So if you do this calculation in loop quantum gravity, you're the key calculation of gravity, you're curious about the geometry, the geometry of anything. You have this piece of this notebook, you want to know the area of the surface. The area depends on the gravitational field. It's something that compute with the gravitational field, which is a quantum field.

So the area of this is a quantum observable. Space time is quantum. That's the point. You do the calculation and you find discrete eigenvalues. So you find that the area cannot be arbitrarily small. It sits on either zero or it's a plank size area which you can compute or the next one or the next one or the discrete. So this makes space time not continuous but discrete because you cannot zoom arbitrary small.

There's no arbitrary small. It doesn't exist in nature. And you have this quantum space, this elementary grain of space, the volume also is quantized, so you have discrete, you have chunks of volume which can be this big, this big, this big, but not arbitrary small. And you have to think about the possible quantum states of space time as this quantum space, sort of connected to one another, that's a picture of spin networks, that with transition amplitude from one another, and they don't sit in a space.

They are space. The space is made by these things here. And this is what explains why luquantan gravity cures the ultraviolet divergences. Because ultraviolet divergence, they all come from the hypothesis that you use in perturbation theory, that space is continuous all the way down. You have arbitrary high frequency in the theory, but there are no arbitrary high frequencies. When you get to the plank, that's it. Careful, and now I come to your point.

Space is quantum, so it's not discrete in the sense in which, you know, you take a set of things. It's not discrete in the classical sense. It's not like the lattice in when you do lattice QCD, you take a lattice and you say, okay, this is discreetness, it's there, it's fixed. It's in the quantum sense. Maybe you can have a quantum superposition of different discrete space time. Right? In an harmonic oscillator, you have discrete agen state of the energy, but the generic quantum

state is not any one of this. It's an arbitrary quantum superposition of this. So the quantum states of loop quantum gravity are quantum superposition, arbitrary quantum superposition of these discrete things. That's the two pictures. So it's deeply quantum mechanical. And one has to stop at space in the classical sense. what has to think

at this quantum state of things. Of course, in the classical limit, when you disregard quantum gravity effect, you go back to classical general relativity and you get space time. It's like photons. Photons, we know photons. When you go to the classical limit of describing many, many photons, you're just a smooth

electromagnetic wave on a large scale. So the same here. The Newtonian space, of the Einstein space, with curves and is just the approximate description of at large scale of particular semi-classical quantum states, which are in reality seen in the small, the quantum superposition of this quantum space. And so would you say... This is the quantum reality.

When I think about it and you have this ode, even in the order of time to John Wheeler, but it also, I wonder, who would you rather talk to and explain the current? status of loop quantum gravity to. Feynman or Wheeler? And keeping in mind, they were both heavily. I mean, Wheeler was Feynman's teacher, was he not? I wish I could talk with either of them. I talked to, I talked to Wheeler a lot.

Wheeler, I had a marvelous, for me, of course, relation with John Wheeler. I mean, he read my first papers on loop quantum gravity. He was enormously excited. He wrote, well, he was excited about everything, was his personality. But he wrote to me marvelous letters. I adore him. In my office, in Marseille, there is a copy of his, there's his letter on the wall. I put it.

And I went visiting him. In fact, you know, I'm a relative, but I didn't, I did not study on his book, the big Bible in generativity. So, no, I did not. I studied on Bob Wald, Weinberg, and so on, many other books, but not his. And when I went to Princeton, he invited me to Princeton to give one of my first talks on Lupuantum Gravity, and I went there with my little models of discrete space time done with key rings attached to one another, because I wanted to show a three-dimensional thing, which is discrete in the small, but you can. And he was excited like a baby, and he ran and took his book and opened the page of his book

in which he has all the key rings attached to one another in a picture for quantum. space time, he loved the early stage of luve quantum gravity. I mean, he was old at that time, but was very enthusiastic. And then I discussed, of course, he had immense influence on me on quantum mechanics also, because the relational quantum mechanics, we're going to talk about relationship of quantum mechanics next time when Elgolan come out. But it was deeply, deeply influenced by it from Bitt information, Willer ideas. So if I could go back to Joe Willer, and tell him how much has Lubb Quantum Gravity evolved.

Lubb Guantan Gravity is entirely based on his wheeler intuition. I mean, the form, I think he was a deep thinker and he has opened a path for thinking on which I and my colleagues have walked. And my last meeting with him, he was very old. And I visited Princeton and we, I visited Princeton, and we were walking in the outside, in the countryside together. He was talking to me. He was very frail and talking very low voice,

and I'm a little bit deaf, so I didn't understand what he was saying. I couldn't say to me or two, please talk higher, louder. So I missed several of the things, but it was still great. Yeah. No, he was famous for so many things and so influential on so much of physics. It's surprising to me that he's not as well known as he should be, but of course that's a game of psychology and politics. But of course if I talk with Feynman would be fantastic.

I mean, Heimann invented all the Feynman theory and spin-form. It's pure Feminology, it's Femannology, right? It's computing transition amplitude by these are graphs, it's two complexes, because they're not particle moving in space. It's a quantum space evolving. evolving, you're summing of evolution of quantum space. That's what spin form is. And the difference is that the quantum space are connected. So they're not described by points, they're described by graph. So when you evolve a graph, you get it too complex. So the point, the node of the graph, the quantum space aligns, but then the links span

surfaces. So you have a sort of bubbly thing. This is the spin form picture. The form come from this bubbling thing that you get when you evolve the links. And so the space, you have to think about space time, from some quantum state of space to another quantum state of space, as a summing of a form in between, which you can think at the same time as a phymonology of the quantum space and the connection moving, or as will reform.

It's the same thing, will reform. Right? So things come together in the intuition. And the beauty of that is you do quantum mechanics, not in space time, right, but off space time, in a way which is finite in the ultraviolet. So this is the beauty of blue quantum gravity. I mean, science is step by step, one by one. Okay, we know this, we know this, maybe let's make a little step, and it's going to work. This is the way it works, in my opinion. I think the universe is made by real stuff that interact, this interaction is a really,

So if you ask me, are the quantum space predicted by loop quantum gravity real? I think, yes, they are. This is a good way of thinking about the universe. These are little chunks of space. I mean, assuming that the theory is right. Is this is wrong? They're right in the same sense, in which atoms are real, okay? Even if we don't see them.

But then we have a very good intuition of atoms and molecules, a powerful way of making concrete. This is realism. Realism is developed appropriate intuition for what's there and using it for grasping the reality which of course is outside of our mind Yeah, I'm trying to get Gerard Uff at Hooft to come on because he has some Recent speculations in this in this field about you know can quantum mechanics be manifestly simulated in other words can you on an ordinary You know classical computer made of silicon? You know can not exotic? superconducting materials such as those we use in our lab, qubits, et cetera. But can you actually

simulate it? And if you can't, you know, does that have some implications as to the veracity of whether or not it's possible to ontologically speak about, you know, what is a model of quantum mechanics? So anyway, I'm hoping to have him on. But one of the questions I get, you know, quite frequently with, you know, Garrett Lacey, Eric Weinstein, you know, these kind of multiple divergent. And I had Stephen Wolfram on, you know, he's sort of the most, you know, clearly, I guess, what Einstein used to say, you know, marble and wood or, you know, whatever, there are these different concepts of theories in physics. You know, I classify Stephen Wolferm as a cellular automata. It's kind of like wood. It's a construction. It's something physical. Whereas marble is,

is this pure form that God uses to make sculptures or whatever. And the question of, you know, like, is there only a theory of everything? Is there only one theory of everything? And I know you've talked about this, like, Luke Quantanagravi is not a theory of everything for what does that even mean? But it seems to me, that Luke quantum gravity might have a better ability. And I'll tell you what I mean in this end. I'm not flattering you. You know, you know me better than that. No, no, please do flatter me. I'm happy. Okay. Yeah, that's, yeah, I have to flatter, you know, I have to flatter somebody in the hopes vainly that someone will flatter me someday. But Stephen Wolfram, you know, I asked him on the show,

I said, do you get, you know, Bell's inequality? Do you get the EPR paradigm? Like, it's not a theory of everything in the sense that it's not going to predict all phenomena, but it may have something to say about, you know, he claims it makes testable predictions about black hole, you know, collisions that can propagate at a certain speed, et cetera. So you say you're not particularly as interested in theories of everything. But it does seem to me, and maybe it's, maybe it's not true, but in loop quantum gravity, wouldn't things like EPR and so forth emerge in a sense? In other words, isn't that built into the fabric of your version of emerging space time? Oh yeah, absolutely. I mean, look, Luke

is conservative. It's genuine quantum mechanics. It's not trying to replace quantum mechanics with something else. So you have entanglement, obviously you have entanglement, you have entanglement, you have a VPR. You have all general activity stuff because you have the classical limit with generativity. That's one, some theorems that do that. So let's distinguish a theory like luke quantum gravity which builds on quantum mechanics and builds on generativity and has just is quantum mechanical theory. We're appropriately adapted from generativity, so times comes in in a proper weight and so on and so forth, but it's the standard quantum mechanics.

Let's distinguish this from wild speculations, like, oh, behind quantum mechanics, there is a classical story, like toft ones, like Wolfram one, like Wolfram one. like other people won't. I mean, I owe my wishes for them to succeed, but there are very strong theorems that say that it's impossible to have a local hidden variable theory. So you can do a non-local hidden variable theory. So you can do a classical theory that reproduce the same prediction of quantification. mechanics, but it's going to be even more wild than what you started from, because it has

things happening here affecting really classically something happening there in an extremely funny way. It has to break Lawrence invariants. So you want to go back to a classical metaphysics, but the price to pay is to deny everything we've learned about the world with classical mechanics, like Florence invariants. I mean, why want to do that? I think you have to adapt your metaphysics

or your intuition to what you have learned with physics and not the other way around. It's a little bit like when they all look like me like Ticobri. Do you remember Ticobri? When Copernicus came out with his story,

one of the difficult things to digest that everything goes around the sun is that the earth moves. Right? I mean, in Copernicus model, the Earth moves like crazy. I mean, we are going crazy speed around the rotate and also around the sun, both. So Ticobrai was the great experimentalist who they call this astronomical measurement and then hired Kepler, which is not a bad idea.

He came out with his own model, and Tico model is a third one. It's neither Copernicus nor Ptolemy, is Tico model. And the Earth is not moving, and then around the Earth goes the Sun. sun and everything goes around the sun, right? So it's an attempt to save the advantage of the Copernical Revolution, but not moving the Earth. It was completely misleading, right? It's a silly idea.

Why was a silly idea? Because it was trying to conserve an intuition, a pre-Cuperticopernical evolution intuition, not willing to give it up. So there's a lot of physicists that try to save a pre-quantum mechanical intuition. instead of just give up, believe quantum theory. The world is not, I mean, one of my, title of my books, is reality is not what it looks like. Reality is not the way we used to think.

I mean, simultaneously, it is not well-defined. Things are not classical. They're genuinely quantum. We have to understand quantum mechanics, but in its own terms, not by reducing it to classicality. And this is also in a different direction, the quarrel I have,

which people who have to, people who take the wave function and the quantum state too seriously. They want to reinterpret the state as if it was a thing, a classical field, maybe in Hilbert space. Sean Carroll is one of that. Many world people.

Leonard Mallard now, you know, Hawking's final collaborator was one too. I think it's a mistake. I mean, the quantum state is like the Hamilton-Jacobi equation. It's like a Hamilton-Jacquescobey function. In fact, the hematom-cordial function is the limit, of the classical limit of quantum state.

So that's what it is. And the Hamilton-Jacquesqueb function is just a tool for computing where we're going to find the particle. But it's not the thing. The thing is a particle. That's right. And quantum mechanics is about things, and these things I think is the interaction. That's my deep understanding of quantum mechanics. Quantum mechanics tells you how things are interacting with one another.

This is about the relation between things. And things have property when they interact. And in loop quantum gravity, this. applies to space itself. So space is a gravitational field, it's a bunch of stuff that interact with something else because this pen interact with all the quantum space around. And so it tells us how the quantum space act on the pen and how the pen act on the on the quantum of space and how all these things move together. And that's the story of the world. This happening, relative happening

of things well described, but equations that we can write now, which of course probabilistic equations. When I think about that, I think about, well, what can I test? You know, because one of the poetic things about your book, the order of time, is how longing you talk about the taste of a madeleine, you talk about, you know, the sipping of wine and good friends and good company, et cetera. And it's longing. And I start off the conversation talking about, you know, well, time is the most irretrievable

asset. Everybody says that. I actually don't believe that. I think innocence is the most perishable of all qualities because innocence is time bound. You know, I've got a bunch of young kids. I'm blessed to have them. And I look at them and I'm like, I want to preserve their innocence as long as possible because it's like a ratchet and pall. It never goes backwards.

And once you're exposed to something maybe good, maybe bad, you can never really get back from that. You know what John Wheeler used to say? What's that? Never run after a woman, a bus. or a theory of everything, because don't worry, there will be always another one coming after a while. Well, one of my friends is a cowboy or cowgirl, and she says, you know, cow droppings are like men, the older they are, the easier they are to get rid of. So, you know, some of these things are perishable in a certain sense.

But before we get to the final questions that I ask everybody on these, I want to talk about a project that I'm interested in, which is modeled after Galileo, Galilee, and that I'm calling it Il Sagittori or the Asseer you know Gallo is one of his little-known books but to me it's it's another example of his genius, of his brilliance and of his humanity

that he was you know subjected to confirmation bias as much as any other physicist in the world but he also despite that had so many great conjectures about the nature of reality and that was that comets were a phenomenon in the earth's atmosphere that was what he believed

And it's really one of the only blunders that he made besides the fact that the Earth's tides are caused by the Moon, sorry, by the Earth's motion instead of by the Moon. He desperately wanted to prove Copernicus and others. Well, that's blunder that you're referring to. It's, in fact, if you read the dialogue carefully scientifically, it's totally wrong. Yes, yes, it is. Because that's, yeah, so that's the entire dialogue hinges on this argument, you know, that. You know what he wanted to call it, by the way, Carla? Do you know what the original title of the book was?

The original title that Galileo chose was on the flux and reflux of the Earth's tides, which, as you just pointed out, is completely incorrect. It has nothing to do with that. It's completely correct. So the entire point, he wants to prove the Copernican system by arguing that since the Earth goes around the sun and rotating itself, the oceans are in a sort of non-inertial movement. that creates the tides. And if you think for a moment,

this means not understanding Galilean invariance. Yeah, which is his greatest contribution, relativity, right? Exactly. But the other thing that's kind of that makes me want to pursue this project, and the project is basically

look at existing data and see if you can get information about unification of forces. Rather than saying you have to propose a new experiment that could cost $20 billion. In other words, look at past experience. And I give the following example. One of, one of Galileo's observations, which he did make was on the procession of sunspots, which Mary Olivier, who you might probably know very well, he claims that Galileo that's the best evidence

for the revolution of the earth around the sun is the appearance of those. But it was, he didn't interpret them right or he didn't emphasize them enough. But my point is not whether he was right or wrong. That's a matter of history and science and historians of science can speculate on. But what I want to say is that that data existed at his time and he could have used it to prove his theory better than the theory of the tides, which was completely wrong. I'm asking you, you know, is it possible that there are data that are out there that we can use already to confirm or refute because you're a good scientist, the veracity of loop quantum gravity or maybe even of string theory? I mean, you might already say that string theory is not only refutable or falsifiable, as other people who've come on the podcast have said, it's been falsified.

So, you know, are there other examples of low energy limits? Take Hertz. You know, Hertz could, you know, prove the, you know, electromagnetic waves, which later would be, you know, the foundation of quantum mechanical waves and matter waves as well. So, and gravitationally. Yeah, let me, yeah, I'm going to answer. Let me first just correct, because then, um, um, people are going to quote you. I don't want to say the strength

though is falsified. I don't think it's falsified. I didn't say you did. No, no, it could still be true. I think that science doesn't go falsification. I mean, all speculations are not falsified, but they all can be true. What happens is that you pile up sort of Bayesian confirmation of disconfirmation that make things more plausible or less plausible.

So, for instance, the non-discovery of supersymmetry at CERN is a heavy disconfirmation, technically in a Bayesian sense, of super symmetry and therefore string theory. Namely, if we had found supersymmetry, the people doing string theory would have said, you see, I am, we are on the wrong track. It doesn't prove it right, but it's in the right direction. It waits in our direction. The fact of, for this very same thing, reason, in the Bayesian logic of giving credibility to things, the fact of not having found something when most people were expecting it lowers the confidence level. That's why many people have moved away from, you know, sort of taking supersymmetry as

string theory is a plausible hypothesis about the real structure of nature after the non-discover subsimity. So I would not use falsification. I would use disconfirmation in the Bayesian. No, I think... But let me come to your question, because your question is very good, of course. It's an ordinary good, and I wish...

I mean, the answer is obvious. Certainly is possible. Of course it's possible, but where? I don't know. I wish I could find something of that sort. I mean, with my students in Marseille, in postdocs and colleagues, we often have just trying to brainstorm.

One thing we have done, for instance, is that think at all the experiments, that gave indication about quantum mechanics in the early day of last century, right? There were so many, I mean, is there anything similar about quantum gravity, is something interference phenomenon or something we can read in the immense amount of data we have about the universe that could be a hint of that? We've been searching here and there. Interference is a key that we were...

I don't know any. If I knew I would immediately write a paper to nature and say, Look, look, let's look there. Or I'll call you and say. Yeah, exactly. Hey, Brian. Let's do that. That would be fun to collaborate.

But, yeah, don't give up because, you know, it's true that we actually discovered, or McKellar is claimed to discover the CMB in 1944 from the observation of certain transitions in cyanogen gas. And that was 20 years before the discovery by Penn Zayson of the CMB. So this happens, and there can be data. And actually. And the big black hole of such, Terry. was there were data about it since since and Galileo discovered Neptune but he didn't realize that that was what he was seeing he thought it was oh I didn't know I didn't know that he had a situation of Neptune I didn't I always say it's too bad because he could

have had a good career okay you know Einstein used mercury you used mercury anomaly which of course wasn't the data before yes I mean he just found a way to and and he got it from Poincereoherre noticed that I'm writing a small introductory book, a textbook on generativity on the course that I gave in generativity. And in fact, I realize that for Mercury is just, it's pretty obvious.

I mean, if you, I understand how poor, I got it. If you take just the data of Mercury, the orbital period, and you fold it the speed of light, C square, and you get a dimensional number, this number is exactly of the order of magnitude of the of the anomaly in the procession. So, posteriorly, I mean, it was obvious that it is a relativistic effect.

It's a C-square effect. You just read it in a numbers. So it's a relativistic effect, obviously, it's a sort of magnetic effect of the gravitational field. So it's the right thing to test relativistic theory of gravity. Interesting. Yeah, when I think about Galileo and Einstein, first of all, Einstein wrote the forward to this edition, this book,

and he calls it one of the greatest books of popular science writing. Of course, you... It is. It is. Absolutely. So I'm hoping to get you involved to read just the forward by Galileo, where he... I wish, I would be humbled

and honored of doing so. Okay, it's one of my life's goals. I will talk to you about that after the show. Okay, for now, we're going to finish up because I, you know, Carla, when I became an astronomer, I thought I'd be on using telescopes all the time, but I really use telecons all the time.

I'm always on telecons, I got one in five minutes. I want to finish up if you'll indulge me with questions I ask all of my guests, ranging from eight Nobel Prize winner, soon to be nine, all the way up to the humblest of all people that I am humbled to have on my show. I'm so grateful that people like you come on. And I call these the Into the Impossible thrilling three questions. And to hear them, you have to subscribe to my mailing list,

and I will send them to Carlo. But for those of you who have not signed up for my mailing list at Brian Keating, dot com please do so you'll get life tips from jim simons the world's smartest billionaire you'll get frank will check's uh questions you get avie lobe you may have noticed carlo avi lobe has a new book out which we'll talk about some other time perhaps about an external extraterrestrial intelligence that visited us anyway if you want to hear carlo's answers please subscribe to my newsletter and i will send them to you the thrilling three and these involve in one sense or another time which Carlo is the foremost exponent proponent

and really just such a lovely book, Carlo. I know you don't need to hear it, or you don't need to, my opinion about it, my encomium on it, but it is. It was a very touching book. I was listening to at the very end of it with my nine-year-old in the car, and he was talking about,

wow, that's like, is this a physics book data? Because he hears me listen to, you know, physics books all the time, and has a lot more fewer equations than those words. Carlo, thank you so much for going into The Impossible with me. I hope we can get together in person maybe here on the sunny Southern California beaches. And I wish you all the best.

And until your next book, Eggoland, comes out in a few months. We'll have you back on. Brian, it was great talking to you. Thank you very much for having you. My pleasure. Any sufficiently advanced technology is indistinguishable from magic. Hello, I'm Stuart Volko, producer of Into the Impossible. If you enjoyed this episode with Professor Brian Keating, please let us know by subscribing,

commenting, sharing, and most importantly, rating and leaving reviews. It really helps keep our universe expanding. We appreciate hearing from you and read every review and comment, and we're always open to your suggestions for future episodes. Watch our YouTube channel at Dr. Brian Keating, DR. Brian Keating, and join our premieres every Tuesday at 8 a.m. Pacific time for live chats. Follow Brian on Twitter and Medium at Dr. Brian Keating. For free access to exclusive content, please visit Professor Keating's website and sign up for his informative newsletter at briankeating.com.

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