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Lawrence Krauss: Multiverse, Dark Energy, Living Forever
October 10, 2023
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We can understand how our universe came to be as one of these sort of drops inside a rapidly expanding universe. But generally, if that's true, there are other universes out there that could be quite different that we'll never know about because the space between us and them is expanding.
Lawrence Krauss is a theoretical physicist and cosmologist. He's focused on issues ranging from the Big Bang to particles. In one of his cosmological papers, Krauss discusses dark energy as a quintessence field. If you think dark energy simply drives the universe's expansion, Krauss' work argues for a more dynamic role of this mysterious force. He's also investigating the puzzling question of why is there more matter than antimatter? Or why is there more antimatter than matter? It's the same question.
And by doing so offers insights into CP violation. We explore that in this podcast. Often it's assumed that both should be produced in equal amounts at the Big Bang. However, this is clearly not the case since we're here. Why this discrepancy? In other words, why are we here? How is this even possible? We also touch on Freeman Dyson's thought experiments about gravity and how we can live forever.
Also, while neutrinos are often relegated to the role of elusive particles in standard physics curricula, Krauss sees them at the heart of several cosmic processes. We talk about why this is. My name is Kurt Jaimungal, and I have a background in mathematical physics, and I use that to analyze the various theories of everything that are out there, like string theory, like Wolframs, like what's coming up is Peter White's Euclidean Twister Unification. But I also explore consciousness and its role in fundamental law.
Due to an ineluctable storm converging on Krauss's location, this interview will be more concise than usual, and we're super keen to expand on it in future episodes. If you have questions for Lawrence Krauss, then leave them below in the format query by writing the word query with a colon and then your question. This way, when I speak to Krauss again for part two, all I have to do is look through the comments, search the word query and then ask your question, citing you either in the description or orally in the episode itself. Enjoy this podcast with Lawrence Krauss.
Professor, welcome to Theories of Everything. It's an honor to have you. How are you doing? It's an honor to be here. I'm doing fine. It's an honor to be here. Actually, it's a little tense here. I was just outside preparing for a hurricane that's going to come by here. And so we're just getting the boat out of the water. And if you look, my Zoom will follow me. I think there's water back there. But so far, the weather is fine right now. So that's good.
We'll make it a short and sweet podcast. And if you as an audience member have questions for part two, then leave them in the comment section below because professor has to go and prep. I've been reading your book. It's a fantastic book. And in particular, see this subtitle says unsolved mysteries of the cosmos. I think that's particularly apt, because there's this series that I love called unsolved mysteries. And this is like the physics version of that.
Well, I think it's always I'm glad you like it. And one of the reasons the title is there because because mysteries are exciting. Most some people are afraid of mysteries, but mystery should be an invitation to everyone. And and and so, you know, unsolved mysteries are really exciting because it's an invitation to everyone to think about how to solve them. Yeah. So what is this process of refinement look like for the chapters? Because there are various unsolved problems in physics. Well, you know what I wanted to do? Look, I've written a lot of books and I wanted this in some ways to be a nice follow up book.
The book I wrote, A Universe for Nothing, was sort of at the forefront of cosmology and then I wrote a book afterwards called The Greatest Story Ever Told So Far, which brought people up to date about the development of what is by far the best scientific theory ever developed by human beings, the standard model of particle physics.
The next step is to see where we're heading in these fields. And to know where we're heading, it's good to know what we know we don't know. In fact, in England, the title of the book is called The Known Unknowns for that reason. Which is what you wanted. Yeah. And so it allowed me to take those forefront issues, which I know are pushing modern physics and also beyond physics,
And those are the areas. And of course, the forefront is just at the edge of knowledge. Literally, it's where we where we there are questions we have, but we don't know the answers. And I think that's the most exciting thing for people. And I think I wrote at the end of the book for a young person. When I was young, I read a book that got me excited about physics to realize the questions weren't all answered. And so I tried to focus on the most exciting questions and the neat thing about it.
The thing that made it particularly attractive is that those questions are the same questions that we all have about the universe. How did the universe begin? How will it end? Are we alone in the universe? How did life begin? These are the forefront questions of science, but they're the questions that in one way or another, everyone asks themselves. And it seemed a lovely way to touch, to tap into that common interest. The questions, how will the universe begin? How will it end? How did life originate? Are we alone in the universe?
When I see green is the same green as you see, what's consciousness? Those fundamental questions are really the things that are driving science and it's kind of satisfying that they are the same ones that interest people. So I always in my books try to think of ways to get people interested, more interested than they are to encourage them to ask questions and that's really the big point and a book about questions which is really what this is.
is really a book about learning because learning should be done by asking questions. Do you find that when you write books, it helps you clarify your own thinking? Of course. No, it always does. I mean, that's one of the reasons I write books. That's one of the reasons why I write books. Because, well, there are two reasons. Well, three reasons. One, because I want to repay the favor when I was younger. It was books about science that got me interested in being a scientist and it's nice to return that favor. But also,
When I write books, you could write the same book over and over again. I know a lot of people who've done that. I won't mention names. But in each book, I try and tackle things I'm aware of, but try and push my own boundaries. So it becomes a learning process for me as well. So it's a combination. Writing a book allows me to study a topic that I might not have the discipline to study otherwise if I don't know it. And if I do think I know it, it allows me to explain it and many, many times
As you say, I realize I understand things more than I did, or in a different context. For example, the chapter on consciousness, I had ideas and biases about the nature of understanding consciousness, but this forced me to delve into those ideas more carefully and try and even define what consciousness was, which is
Which is not the case. Another example is the origin of life. I'd led through the institute, I ran at a university, meetings a decade or two ago on the origin of life. And this allowed me to say, well, okay, I understand what those issues are, but what's been happening since then? And what are the key things that are being understood? I mean, long ago, and I remember in the first book I ever wrote, which is about dark matter, I was writing about particles called axions.
And I was writing about symmetries of nature and I realized in the context of axions and these symmetries that there was an experiment that showed
That gave strong constraints on one symmetry of nature but i realize in the process of writing it that i absolutely didn't understand it and i thought i did i understood what was needed to know but when i tried to explain it i realized hey there's problems now i think about it is that really right and that that happens to me every book i write and it's fun it's it's fun.
But it's also fun to learn stuff. And so I, you know, they're not all books on total new topics. So I wrote a book on the physics of climate change, which again, I've been tutored and over the years, especially as chairman of the board of sponsors, the Bolton Atomic Sciences for a decade. But but to go into the detailed history and understanding of climate science, that was a new area was also the beginning of the pandemic. So I had nothing else to do. So so I was able to do it. But and in this book, because it's very broad, it's really all of science.
Time, space, matter, life, consciousness. There are obviously areas where I knew I'd want to really read up and again the consciousness chapter probably was your favorite. Well I don't know it's my favorite, no it was the hardest which is one of the reasons why I left it to the end but it was the one where I had to read the most because it was an area where I had a vague understanding and I'd run some meetings
Also on aspects of consciousness, but to really go into it enough to try and say what are the open questions or to reinforce or invalidate my a priori bias that we don't understand consciousness, I had to really try and see what explanations people gave for consciousness.
Are there any interesting older sources that you looked at for any of your chapters, let's say the life and the consciousness one? I looked at older sources. What I like about the first chapter, which is on time, is I go back to black holes and I talk about this guy, Michel, who was an unsung hero of science a hundred years after Newton, who really was the first person to come up with the idea of black holes. It was fun to research
his own, you learn about him. There are some amazing scientists who really are unsung, and in the modern world they'd be at the very top, but they've sort of disappeared in the dustbin of history, I guess, in one way or another. And then same with, you know, with consciousness, going back to the early people who looked at consciousness, the early, the first neuroscientists and psychologists looking at their work and seeing how much or little had changed since then.
You know, and of course, when it comes to the origin of life, that's an area where there's been a huge number of developments. The origin of life has to be distinguished, as I tried to explain in the chapter first, from the origin of the diversity of life. That's, you know, evolution, which is, well, there are open questions with evolution. That's an area of science that's well-trodden. But to go back to determine how chemistry turned into biology is right at the forefront. But we have to start thinking about the early stages of
of the discovery of dna and how did such a complex molecule rise and then it was an amazing discovery of course i've actually an old colleague of mine when i taught at yale he was my dean and i and i you know i i still don't have a great opinion of deans but he was a good guy but i never realized he was a great scientist till after he stepped down and being dean and he won the noble prize
And I realized his work on RNA was essential. It showed that a precursor world to a DNA world could have been an RNA world. And so it's fun to go back and see the development of ideas. And I think that's another thing about science.
In some ways it's storytelling, it's not all storytelling, but I think people appreciate a story. And the human interest aspect of a story, how the red herrings or how we got to where we go is something that's interesting and worthwhile talking about. We don't often always talk about it in lecture courses, but I think in books it's fun to do that.
Yeah, well, in books it seems necessary because you have to open a chapter with something that's human and relatable to the general public. Well, I think you do. Yeah. Statistics to the scientist. It's like that's what we find interesting. Well, exactly. But you know, people are interested in things they don't know they're interested in. And I think the key point is to convince them they're interested in things. I often tell teachers that the biggest mistake they make is assuming their students are interested in what they have to say. You have to convince them to be interested. So you have to go to where they are and try and reach out and grab them and say, this is interesting.
And then, you know, it's like many people are afraid of science, but they don't realize they're interested in it. When you talk about warp drive or time machines, they suddenly get interested and they don't realize it's kind of forefront science. Yeah. Tim Modlin was saying that his favorite parts of most physics courses, most science courses in general, are the first lectures because they're selling you on the course. So he's like, when I went to quantum field theory, they told me about this is the most impactful theory in science. And then lecture three is on Green's functions. He's like, well, what happened to
Studying what is and when you ask what is they're like, oh that's philosophy actually don't even ask that here Yeah, well, I mean, you know, there's a lot well quantum field theory is certainly always been and probably well I don't know if it remains but it's always been the most challenging class to teach in graduate school and or to take and there's just a lot of stuff and a lot of intellectual baggage that you need to do and you can't and and before you can philosophy is useful for framing initial questions and
But physics has long gone beyond those initial questions so that it's driven by questions that are often quite mathematical in nature. And people don't realize that you can't just sort of start with those questions and expect to reach anything without going through the remarkable baggage that's been developed and that has taken you far away from the questions.
So, you know, what is, is a fancy question, but it actually, as I talked about in Universe for Nothing, that the whole concept of something and nothing just changed dramatically because of physics. And people don't like that, but I don't care. It's the way it is. It's called learning. And we now realize, as a matter of fact, because of quantum field theory, that the difference between something and nothing is not so great as imagined before, because nothing has lots of something in it. Yeah. Let's speak about that for a moment.
When I was younger, I remember questioning the universe and I couldn't figure out how anything could come from nothing and that was something that I had asked my brother who was studying physics at the time and then he mentioned quantum fluctuations and I was eight or so and then it was approximately that point that I became an arrogant and inexorable atheist.
Your brother, your brother did God's work, as we say. I realized years later, that's not an explanation to say vacuum. But I didn't know that at the time. So because I didn't know, I thought that that was an explanation. However, you have now figured out some way of making that indeed an explanation. So can you cover that, please? How you get something for nothing? You mean how the universe can come about from vacuum fluctuations? Yeah, well, yeah, I can give you a summary. As I said, I wrote a whole book about it. So it's kind of but
Look, the key aspect of quantum mechanics, which I do talk about in the new book, is that the quantum universe, many things are happening at the same time. And in particular, quantum fluctuations are happening all the time. We can't see them, but quantum systems are constantly fluctuating. And when you combine quantum mechanics and relativity, it's even more exciting because it says that
that empty space isn't empty. So the key thing about quantum mechanics when you combine it with relativity and I've described this in a number of my books, it implies that empty space isn't empty. I mean it has no real particles but over time scales that are so short that you can't measure them directly, and this is the uncertainty principle of quantum mechanics, things can happen that you can't see.
And in particular, particles can pop into existence that weren't there before and then pop out of existence in a time scale so short that you can't even see them. Those are called virtual particles. It may sound like counting angels on the head of a pin if you say, well, these particles are there, but you can't see them. Well, we can't see them directly. What we can do is see their effects indirectly. We know they're there because we have an impact on the on the atomic energy levels of atoms. They allow us to calculate the atomic energy levels of atoms with an accuracy
That's unprecedented in all of science. So we know we have to include the fact that on small scales and small times, particles are popping in and out of existence. It's quantum fluctuations in quantum fields. That's why quantum field theory is relevant. Allow you to produce particles that appear and then disappear. Fine. Well, that's for normal quantum field theory with particles in space and time. But gravity is a theory of space and time.
And so if gravity is a quantum theory, if gravity is a quantum theory, and that's a big F, we don't know for certain, but we have no reason to suspect it isn't, then the variables of that theory, space and time become quantum mechanical variables, and then space and time can fluctuate. And you can start literally with no space, no time, and then have a little universe with space and time appear and then disappear.
virtual universes can pop in and out of existence and in quantum gravity that kind of phenomena happens but it can happen that if a virtual universe pops into existence with zero total energy then the laws of quantum mechanics and relativity say that that virtual universe in fact can be real, it can exist for an arbitrarily long time and then
In order for it to not collapse again if it's if it's a starts expanding and not collapses certain processes have to happen but if you asked What would a universe that lit was almost 14 billion years old that? Spontaneously arose from nothing by quantum mechanical processes. What would it look like today? And the answer is it would look just like the universe we live in
All the properties would be the properties of the universe we live in. Now that doesn't prove that that happened, but it's strongly suggestive that that possibility could explain the existence of our universe. Now it's all possibilities right now because we don't have a quantum theory of gravity. I said if space and time, if gravity is a quantum theory, and it's a big if. We don't have a theory of quantum gravity. String theory is a good candidate for that, but no one knows if it is a theory of quantum gravity.
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And what's the name of that theory? What you just outlined, which is, okay, look, if you have fluctuating quantum fields, and you were to combine general relativity of fluctuating space time itself, universes, it's just a proposal, a vague proposal, like, or is there? It's a it's a it's a no, there's no names attached to it. I propose that other people have proposed it. But it's just a consequence, if you wish, of, of, of having a quantum theory of gravity. And lots of people thought about Hawking and Arnold. And, you know, Stephen Hawking has obviously thought about it a lot. I have other people have
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In the limited time that I have to speak with you, I want to ask you a bit about Dyson, your conversations with Dyson, which you talked about. Dyson was thinking extremely theoretically like what could it be? What could it be? Not just for us to live forever before possible being to live forever. What would that mean? Is it possible?
and he came up with a solution that has to do with well if a conscious being had an infinite amount of cycles that's akin to a living forever. Now I don't know if he has to assume a continuous amount that you can divide space or that you can divide time to but regardless you'll speak about that. He came up with very interesting proposals for how a hypothetical species could do that. We had wonderful debates
In principle, is it possible for a civilization to live forever? Yes, I'll define it as if it has an infinite number of thoughts. If it has an infinite number of thoughts, then that civilization will survive forever.
And then he said, well, how could you have an infinite number of thoughts? Because when we're thinking, it takes energy, 10 to 20 watts in our brain, which is not a lot, but enough. So clearly, you'd think it would take an infinite amount of energy to have an infinite number of thoughts. And if we only have access to a finite amount of energy, then we can't do that. But then he pointed out that you can have infinite series that converge to a finite number.
The Greeks discovered that and Zeno's paradox for those who know of it or at least we now know a solution of Zeno's paradox. I'm not sure the Greeks exactly figured it out but in any case and so he argued that if that one way to have an infinite number of thoughts would basically be wake up have a thought then go to sleep
where you're
The problem is briefly before we get to the problem Why is that so remarkable because like you mentioned we've known about infinite series that converge for quite some time now So why did it take Dyson to come up with that? What did he contribute to it that was different that was subtle? Well, I think His His realization that his well you see the point is that because we think in terms of metabolism
The standard wisdom was that non-zero metabolism will therefore require infinite energy access over infinite time in order to continue because it's always, and I think the cuteness of his example was imagining a system that could basically turn itself off.
and really have a life that many people would not sit well, if you get older, sounds nice, but a life where you're sleeping more and more and more and more, which most people don't think of as a vital civilization. So I think it was his recognition that in an expanding universe, you have to do the equations right. The free energy that you use, the integral of that could be finite.
Even though they're an infinite number of wake-up periods, it wasn't all obvious that you could get it to converge. And so I think it was a combination of that and realizing that if such a system could turn itself off, then you could in principle do that. But there's lots of problems there. Immediately quantum mechanics comes into a problem because quantum fluctuations are such
It's kind of hard for a system to use zero energy at all. But also, how do you wake up? There was one example. I mean, so you want to wake up, but then you have to have an alarm clock. Well, how do you have an alarm clock that has an infinite number of wakeups that uses less energy? And then we'd come up, we showed them, hey, the alarm crop is going to use an infinite amount of energy. They said, no. He came up with an orbiting planet scheme, which is really tricky for orbiting planets that eventually, or not planets, but orbiting particles where they collide, the alarm goes off.
It doesn't take any energy to orbit a planet and then we point out eventually the laws of quantum mechanics will get you there as well because the uncertainty principle means you can't at some very basic level you can't fix exactly the momentum of two particles and eventually you can't fix it well enough. You can fix it to some certain level of accuracy but if you want them to orbit each other for 10 trillion years before they collide
Then the uncertainty in their momentum is such that every now and then they're going to miss each other and you'll sleep forever. And they're little things like that. And anyway, and then his final argument was a black cloud like that of the black cloud of, oh, what's his name?
The Blackout is probably the best science fiction story ever written. It involved the discovery of a cloud and it was realized that the motion of the particles in the cloud encoded intelligence and he argued that that cloud could slowly expand and you could imagine it would live forever.
Ultimately and we're back and forth but ultimately this is before we knew we're having that debate before we knew that the expansion of the universe was. What's the meeting up something actually proposed in a few years later and and then it was discovered to be true.
But we both recognize that if the expansion universe was speeding up, then his arguments would fall by the wayside. There's no way life can exist forever in a universe that's accelerating like we have. Even though we agreed to disagree about what happened in other cases, we agreed about that case. And since that appears to be the case for our universe, it looks like
It's not good news for the for the future long-term future of life as I like to say the future is miserable Hmm, but it's gonna be a while before it's but before it's gonna get too miserable Trillions of years and with Dyson I sent a YouTube video. It's been a while since I've seen it, but he was saying that gravitons aren't detectable He had some in oh, yeah. Yeah. Yeah. No. No, in fact, actually he said that and then I actually and Actually was in a meeting with him
When he argued that that he gave a great argument for how all the experiments that are you could detect a Graviton directly wouldn't work and I'm not sure all of his arguments are exactly right but but it was a brilliant like typical dissonant paper was what could you do in principle to do this and in every case showing a real trick for why it wouldn't work but in fact but in fact what I talked at that meeting and he
He agreed with me ultimately, but I showed him that no experiment we can do on Earth will detect gravitons, but the universe as an experiment can detect gravitons because the universe can do things we can't do, like ultimately have regions that are expanding farther, faster than light away from each other. And I showed him that this process of inflation in the early universe would produce gravitational waves, but only
which we can measure today, but only if gravity was a quantum theory, in which case there would be gravitons. If we detect gravitational waves from the expanding universe, which we haven't done yet, we've detected gravitational waves from black holes that are colliding, but we haven't detected gravitational waves from the Big Bang or this period called inflation, if we could do that, those gravitational waves would be generated if and only if
At a very fundamental scales, gravitons were being created and destroyed. And so we could use the universe as a way to prove that gravity is a quantum theory. If we were able to detect gravitational waves from inflation, it would imply that gravitons exist. And so it'd be an indirect way. You wouldn't directly detect them. But the universe in that sense would be a graviton detector. You'd see, just like when a Geiger counter detects a radioactive decay, but I don't see the radioactive decay, what I hear is a click.
You also mentioned in your book about inflation that there are various inflationary models and that some of them can be used to indirectly
Inflation is an idea more than a theory. You can show that under certain conditions the universe will expand very fast at early times. It's almost generic. The hard part is to get it to stop from expanding very fast because if it didn't stop expanding very fast, life couldn't form.
Exactly how you do that is the context of a model. So you embed that idea in a mathematical model of how the universe is evolving. And there are different models and none of them are very pretty to tell you the truth right now, since I suspect there's things we're missing. But almost all of those models for how you stop expanding, very fast,
imply that there are actually other universes because what really happens is there doesn't seem to be any way to globally stop the universe from expanding very fast but what you have is sort of like little drops or snowflakes. The background universe is expanding very very fast but within a small region there's a phase transition like a snowflake forming or a raindrop forming out of vapor
And in that region, you decouple from that background fast expansion and you have a hot big bang. But that means most of the rest of this space is still expanding and somewhere else you decouple and have a hot big bang. But it turns out you can decouple from that expansion. You can have a phase transition in many different ways, just like you can create snowflakes that have many different shapes. And each different way you decouple from that background expansion,
Can result in different laws of physics.
But generally, if that's true, there are other universes out there that could be quite different that we'll never know about because the space between us and them is expanding so fast. We'll never know about it. That's the multiverse. And moreover, since it goes on infinitely long, you'll eventually get to create an infinite number of such other universes. OK, now we'll never direct detect those other universes. People say that's kind of science fiction or religion or something. But if we could detect, say, gravitational waves from inflation,
Then we'd be able to probe the exact model of inflation, the characteristic of how we decoupled from that background expansion. And we'd be able to tell which model, if any, of inflation was right and probe its theories. And once we did that, we'd know if that model predicted a multiverse. So we'd know indirectly that there are other universes because we'd probe the model and say,
That's what happened, but if that happened, there have to be other universes out there. So it's an indirect detection. Just the way in 1905 we knew atoms existed, but there's no one ever figured to be a way to see them directly. We always detected their effects indirectly. We can now more or less see them with fancy kinds of electron microscopes and other things. But all the evidence for atoms, we believed atoms existed shortly after 1905.
Because it explained everything we saw, even though we never thought we'd see one directly. And that's the way it'll be with a multiverse. We'll never detect those other universes. But if we have a theory and we can test it very, very well, let's say we had a theory of inflation that we could test very well, and it made 50 predictions and you tested all those 50 predictions and they were correct. Well, the 51st prediction that you couldn't test, you'd have strong reason to indirectly believe was correct.
Are we currently looking for these primordial gravitational waves? Yes, we're looking in different ways. We thought we discovered them 10 years ago or maybe 8 years ago, something 10 years ago close to. We're looking at ripples in the cosmic microwave background radiation, the radiation from the Big Bang. These gravitational waves would leave a signature that's very hard to detect. I think it was 2015 or somewhere around then, maybe a little later.
to a group of experimentalists thought they detected in fact it was kind of sad because they detected precisely what they thought the signal of such primordial gravitational waves would be with an amount as large as was allowed by other constraints but it turned out that they were they were fooled it was turned out that dust in our galaxy produced the signal that they thought they saw it doesn't mean that you know what it did I shouldn't say it that way it turns out that dust in our galaxy could produce a signal that was as large as what they saw
It doesn't mean that there wasn't a real signal embedded in that, but because extraordinary claims require extraordinary evidence, the simplest thing to assume is that what you can say is you cannot distinguish it from dust in our galaxy. So more refined experiments are going on in the South Pole and also in South America and in high levels building these probes of the cosmic microwave background radiation that are looking for this primordial gravitational wave signal.
It may not be there at a level that they can see, we don't know. But there are ongoing experiments looking for it. What you referenced was Brian Keating's work? Yeah, yeah. I mean, Brian Keating was part of the first experiment that thought they'd seen those gravitational waves. He was the PI on it, but he was working on it, yeah. And he's working on the subsequent experiments that are trying to refine the measurement. Maybe they'll see it, maybe they won't.
So neutrinos are your favorite particles. That's true. Yes. Yeah. And then there's something called CP violation and there's something called leptogenesis and neutrinos CP. Yeah. Wow. It's going to be this. Please integrate. We're getting quite technical. Okay. You read the book for sure. Well, so I'm a math and physics grad from U of T and the audience tends to be graduate students in physics, math, consciousness, computer science, as well as researchers. Well, I mean, neutrino. Yeah. Neutrinos are my favorite particles because they're most elusive particles.
And it turns out they may be my favorite particles for another reason, they could be responsible for our existence. Because one of the big problems that got me into cosmology and many other people, the first time particle physics was really applied to cosmology was in the 70s or so. One of the big problems is why do we live in a universe of matter? It may not sound like a problem, but it is if you think about it because matter and antimatter are largely indistinguishable. And if you have a hot big bang, you'd think you'd create as much antimatter as matter.
And if you did, then the matter and antimatter would annihilate, you wouldn't have anything left over. So there had to have been a slight excess of matter over antimatter early on. How was that created? We still don't know the answer, but we have ideas for how it might happen. But there are problems with all those ideas. If you create just these particles called baryons, which are like protons and neutrons, and you make a slight excess of them, then it turns out there are later things that can happen in the universe that will erase that excess
Or you require a theory that has parameters that we've already ruled out. And Andrei Sakharov, who later won the Nobel Peace Prize, was a brilliant Russian physicist, the father of their atomic bomb, who in 1967 gave three conditions that are required to have more matter than antimatter. You have to have a departure from thermal equilibrium. You have to have
The theory has to allow you to violate what's called baryon number, baryons and anti-baryons, distinguished protons from anti-baryons. It also has to have what's called CP violation or time reversal invariance violation. So it has to violate matter and anti-matter have to be different in a fundamental way, very small way but different. So you have baryon number violation but also matter and anti-matter can't be quite the same. They have to have some different interactions.
And he showed that if those three things were true, if you had a theory that those three things are true, then you could generate an asymmetry in the early universe that would produce more matter than antimatter. The problem was in 1967, none of those things were true. The standard model at the time didn't have baryon number violation. There was no evidence of any need for out of equilibrium processes in the early universe. And it certainly didn't have CP violation. Well, CP violation had just been discovered in 1965.
And of course, since then, our theories of going beyond the standard model include all of those things. The grand unified theories have very a number of violation almost automatically. Maybe they have CP violation, but it turns out it's hard to make them work. But what has been recognized is, well, the neutrino sector is largely unconstrained.
Because we've measured CP violation in the observed sector of the rest of particles, but because neutrinos are so elusive, it's been very hard to do experiments on them. And it's quite possible, especially if neutrinos are their own antiparticles, then that violates something called lepton number. An electron has lepton number one, an anti-electron has lepton number minus one.
But if I, it turns out, well, if neutrinos are only, are their own antiparticles, and if they have a mass, I should say that, and if they have a mass, that mass will, that will require you to violate lepton number. Namely, you could create two neutrinos out of nothing, okay? And instead of a neutrino and an antineutrino, because an antineutrino and neutrino are the same thing, right?
The lepton sector via neutrinos is very unconstrained and it's been realized that maybe if there's CP violation in the neutrino sector, if not only our neutrinos are on antiparticles but there's CP violation, then you could have a process in the early universe that's now unconstrained by our experiments that if you wish would produce more neutrinos and antineutrinos.
But in order for that to happen, you probably have to have extra kinds of neutrinos that we can't see right now. And if that happened, then basically those interactions and the decays of those particles would be fed into the visible sector and end up producing more electrons and anti-electrons and more protons and anti-protons. So basically you'd produce the isometry between particles and anti-particles in the neutrino sector and that would feed down
and eventually give us more matter than antimatter. It's called leptogenesis. And right now, many people think that might be the most attractive possibility for how we end up getting more matter than antimatter in the universe.
Two questions, is there a consensus right now to whether neutrinos have mass? Neutrinos have mass because they've been measured to oscillate between the electron neutrinos, muon neutrinos and town neutrinos oscillating to one another in a way that wouldn't produce measurable effects if they didn't have mass. Their mass has to be very small, we haven't measured their mass directly. We don't know exactly which mass, which particles heavier, all of those things are open questions.
But we do know that neutrinos have mass, and in fact in the standard model that's not really an easy thing to put in. So already that's indications that there's physics beyond the standard model. So that's another thing that's great about neutrinos because they're pointing us in the direction of sort of beyond the standard model of particle physics. So the inconsensus is what mechanism? Is it the seesaw mechanism or is it something else? Like we know it has mass, it's just what produces it? Yeah, we just don't know. I wouldn't call it lack of consensus, I'd just say we don't know.
There's a lot of ideas for where neutrinos get their mass and what their masses might be, but right now we don't even have the experimental data to be able to distinguish between them. There's a long baseline experiment in Fermilab that's going to shoot neutrinos to a detector in South Dakota.
Yeah. And if I heard correctly, I believe you said that in order for leptogenesis to occur, there has to be other kinds of neutrinos that we don't currently observe. And are you referring to right-handed or are you referring to like new generations? I'm referring to right-handed neutrinos. Yeah, heavier right-handed neutrinos. Generally, that's the case. Yeah. And then those can feed down into normal because they're unstable.
As far as I recall, neutrinos propagate as mass eigenstates, but they're detected as flavor eigenstates. That's the reason, yes, but that's the reason they oscillate. Because the mass eigenstates are not the weak eigenstates, if you want. So the particle that's propagating is not an eigenstate of
Well, if you want to think of it,
It's not a bad analogy. It turns out the weak eigenstate, the thing we label as electron neutrino, is a superposition of mass eigenstates. So it's like saying that a particle that's in the spin half is in a superposition of spin up and spin down or spin up and spin sideways or whatever you want to do, call it. So it's in a quantum superposition of two different states.
And sometimes you measure and it's fine to say that sometimes you measure it and you measure, you know, it's like if you're in a superposition of a spin up and spin down, if the particles oscillating, let's say in a magnetic field, sometimes you'll measure it spin sideways and sometimes you'll measure it spin up. And this is somewhat similar to that. Sometimes as the particles propagating, you'll measure it and you say, oh, it's an electron neutrino. And other times you'll measure it and say, no, it's a muon neutrino.
It's not that bad an analogy. It's saying because the mass eigenstates aren't the weak eigenstates, another way of saying that is the weak eigenstates, the flavor eigenstates are linear superpositions of the mass eigenstates, but that also implies that the mass eigenstates are linear superpositions of the flavor eigenstates.
So it's not like you can say, okay, well, which one is more fundamental? It's like you can draw your bases in any way. So well, I mean, one, well, I mean, yeah, well, you don't I mean, mass is energy is fundamental in terms of propagating in space and time energy and momentum. So they determine the states that propagate the mass eigenstates are the ones that propagate. Sorry, if this is a foolish question, I just don't know. No, no, no, no. No. So but but point is, it's kind of
It would be arbitrary if it weren't for the fact that the other particles we measure, like electrons and muons and stuff, that their mass eigenstates are weak eigenstates and so they're good labels. For all the other particles that we measure, the ones that make us up, electrons and protons, they're labels because they have electric charge. Those are good labels.
But the neutrino is neutral and so the label we give it is somewhat arbitrary for it. Okay. Now you have studied dark energy and dark matter plenty. So there's some people that say, well, it's not matter. It's a modified gravity. What do you make of that? There's also something called teleparallel gravity. There's lots of ideas. I don't know. Every week there's a new proposal. The simplest proposal is that it's the energy of empty space.
For dark matter, it's not anywhere near as exotic, it's just a new kind of elementary particle and the standard model and every theory that goes beyond the standard model predicts a host of such particles whether they're wimps or supersymmetric particles or axions.
You can't create a model that goes beyond the standard model. Maybe you could, but it's very hard to do without dark matter candidates. As my friend Frank Wilchick used to say, it's the most radically conservative assumption.
Which is what you do in physics, right? It's much more conservative to say there's a new kind of elementary particle, since we expect there will be, than to say that gravity, if one of the fundamental forces in nature, somehow gets modified in exactly the right way on the scale of galaxies to produce the weird effects that we see. That's why I find dark matter, the particle explanation for dark matter to be far more compelling theoretically and observationally than anything else.
Okay, now let's talk about infinities briefly.
It's a reflection of our ignorance about the fundamental laws. But still to this day, some people think of renormalization. Even some physicists, I was speaking to one off air and he said, no, no, it's still sweeping infinities under the rug. So what is your view? No, no, no. Look, look, the point that my view is that the mistake of thinking of infinities is the mistake of thinking that any theory is good at all scales.
We used to think of electromagnetism as a theory of nature, and it's true for all scales, but it's not true for all scales. We know in fact that at a small enough scale, electromagnetism unifies with the weak interaction. So if you take your theories and you do your integrals up to infinity, you're assuming the theory works at a scale where it may not work. So it's making vast assumptions about what happens at scales you can't measure. It turns out that the sensible theories that we can measure at low energies
are ones that are insensitive to the new physics that is inevitably going to happen at those high scales. And renormalization is just a way of separating out what we can measure and know from the physics that is irrelevant at low scales. It's relevant, but it's suppressed by powers of very large masses.
Any new physics that comes in has an effect that goes like one over m the mass scale of which it comes in and so we're normalization is just a way of basically systematically separating out those higher order effects that are relevant.
And if there are no theories, you can take that mass to infinity. And renormalizable theories are theories that make sense if you take that mass to infinity, if you take the scale of any new physics to infinity. If they weren't, if they were sensitive to high energy physics scales, then they wouldn't be renormalizable, but then they wouldn't be the theories we see anyway, because it would depend on new effects. The whole notion of associating with infinities is just because we don't know what the physics is.
We say, well, if it were infinitely big, how can we dissociate that from the level of the physics we measure? But it's really just equivalent to the statement, and this is Wilson's recognition, that those new theories at very high scales are relevant to understanding the physics at scales we see, but the theories evolve with scale. And eventually, that high-scale physics will be important.
And in fact, the physics that you can't always that some of the physics you can always see will will change the way in which those theories change with scale. One of the ways we look for new physics at the Large Hadron Collider is to is to look to see if the if the
if the strength of the weak and electromagnetic forces are scaling as you think they would. If they're not, then it may implies new virtual heavy particles that are contributing to the way those forces are behaving and it would be a signature of new physics. So it's not a matter of sweeping infinities under the rug. It is if you do the mathematics, but physically what you're just saying is I don't know what the new physics is and I'm going to isolate that physics that I don't know
And define a theory that works at this and that's defined and works at this scale and gives all the relevant answers at this scale at another scale the theory may change so we really realize there are no fundamental theories in nature all physical theories evolve.
With TD Early Pay, you get your paycheck up to two business days early, which means you can grab last-second movie tickets in 5D Premium Ultra with popcorn, extra-large popcorn,
I want to keep you for too much longer as there's a hurricane that's impending and I would like to speak to you again. Yeah, we good. This is certainly a fun and detailed conversation that's more detailed than I usually get to do online. Yeah, so you mentioned that the Hicks field is like a Bose Einstein condensate.
Now I don't know if you meant that poetically or literally. No, it is a condensate. As you know, and maybe your listeners know, that no two fermions can exist in the same state, but you have bosons, particles with zero spin or spin one, they can condense. They all want to be in the same state. And when they're in the same state coherently, it looks like a classical field.
That's why we can measure electric fields, because photons can exist coherently in the same state. Enough of them, enough quantum particles add up so the effect looks classical. Well, the Higgs field is a condensate of particles, of Higgs particles, and that exists in empty space.
It's like a background field. It's like a background electric field. It's just we don't measure it as an electric field. We can't measure it directly but the way we can measure it is by hitting it really hard with particles and then we knock other particles out and that's basically what we do at the Large Hadron Collider.
And so the Higgs field is really a Bose condensate of particles. A Bose condensate of particles is a background field that's made of a coherent superposition of many, many quanta of the Higgs field, which are Higgs particles. Well, professor, you got to get going and I could speak to you for another three hours, maybe longer. We'll speak again. Yeah, yeah, I would love to. And so why don't you tell the audience, what are you working on next? Are you writing another book?
I am probably writing another book. I just finished some work on ways to maybe test ideas of quantum gravity in the laboratory by using fluids. We have a paper that just came out in Nature Physics that's not yet appeared in print but it's just been accepted and appeared online. I'm writing a new book but it's probably not going to be a science book of the type that you're used to.
There's a number of possibilities. Fiction? Well, fiction is one of the possibilities, probably not for this book, but there will be a fiction book coming out. This book will either be, I've started because enough people have asked me to write a scientific memoir, to write a scientific memoir, so I've started it. We'll see how long my patience lasts. I've known many, many, many interesting scientists and other people over the years and
The link to that will be in the description. Thank you so much for spending your time with me during this tumultuous weather.
If you have questions for Lawrence Krauss then leave them below in the format query by writing the word query with a colon and then your question. The podcast is now concluded. Thank you for watching. If you haven't subscribed or clicked that like button now would be a great time to do so as each subscribe and like helps YouTube push this content to more people.
You should also know that there's a remarkably active Discord and subreddit for theories of everything where people explicate toes, disagree respectfully about theories, and build as a community our own toes. Links to both are in the description. Also, I recently found out that external links count plenty toward the algorithm, which means that when you share on Twitter, on Facebook, on Reddit, etc., it shows YouTube that people are talking about this outside of YouTube, which in turn greatly aids the distribution on YouTube as well.
Last but not least, you should know that this podcast is on iTunes, it's on Spotify, it's on every one of the audio platforms, just type in theories of everything and you'll find it. Often I gain from re-watching lectures and podcasts and I read that in the comments, hey, toll listeners also gain from replaying, so how about instead re-listening on those platforms?
iTunes, Spotify, Google Podcasts, whichever podcast catcher you use. If you'd like to support more conversations like this, then do consider visiting patreon.com slash Kurt Jaimungal and donating with whatever you like. Again, it's support from the sponsors and you that allow me to work on toe full time. You get early access to ad free audio episodes there as well. For instance, this episode was released a few days earlier. Every dollar helps far more than you think. Either way, your viewership is generosity enough.
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"text": " We can understand how our universe came to be as one of these sort of drops inside a rapidly expanding universe. But generally, if that's true, there are other universes out there that could be quite different that we'll never know about because the space between us and them is expanding."
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"text": " Lawrence Krauss is a theoretical physicist and cosmologist. He's focused on issues ranging from the Big Bang to particles. In one of his cosmological papers, Krauss discusses dark energy as a quintessence field. If you think dark energy simply drives the universe's expansion, Krauss' work argues for a more dynamic role of this mysterious force. He's also investigating the puzzling question of why is there more matter than antimatter? Or why is there more antimatter than matter? It's the same question."
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"text": " And by doing so offers insights into CP violation. We explore that in this podcast. Often it's assumed that both should be produced in equal amounts at the Big Bang. However, this is clearly not the case since we're here. Why this discrepancy? In other words, why are we here? How is this even possible? We also touch on Freeman Dyson's thought experiments about gravity and how we can live forever."
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"text": " Also, while neutrinos are often relegated to the role of elusive particles in standard physics curricula, Krauss sees them at the heart of several cosmic processes. We talk about why this is. My name is Kurt Jaimungal, and I have a background in mathematical physics, and I use that to analyze the various theories of everything that are out there, like string theory, like Wolframs, like what's coming up is Peter White's Euclidean Twister Unification. But I also explore consciousness and its role in fundamental law."
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"text": " Professor, welcome to Theories of Everything. It's an honor to have you. How are you doing? It's an honor to be here. I'm doing fine. It's an honor to be here. Actually, it's a little tense here. I was just outside preparing for a hurricane that's going to come by here. And so we're just getting the boat out of the water. And if you look, my Zoom will follow me. I think there's water back there. But so far, the weather is fine right now. So that's good."
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"text": " We'll make it a short and sweet podcast. And if you as an audience member have questions for part two, then leave them in the comment section below because professor has to go and prep. I've been reading your book. It's a fantastic book. And in particular, see this subtitle says unsolved mysteries of the cosmos. I think that's particularly apt, because there's this series that I love called unsolved mysteries. And this is like the physics version of that."
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"text": " Well, I think it's always I'm glad you like it. And one of the reasons the title is there because because mysteries are exciting. Most some people are afraid of mysteries, but mystery should be an invitation to everyone. And and and so, you know, unsolved mysteries are really exciting because it's an invitation to everyone to think about how to solve them. Yeah. So what is this process of refinement look like for the chapters? Because there are various unsolved problems in physics. Well, you know what I wanted to do? Look, I've written a lot of books and I wanted this in some ways to be a nice follow up book."
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"text": " The book I wrote, A Universe for Nothing, was sort of at the forefront of cosmology and then I wrote a book afterwards called The Greatest Story Ever Told So Far, which brought people up to date about the development of what is by far the best scientific theory ever developed by human beings, the standard model of particle physics."
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"text": " The next step is to see where we're heading in these fields. And to know where we're heading, it's good to know what we know we don't know. In fact, in England, the title of the book is called The Known Unknowns for that reason. Which is what you wanted. Yeah. And so it allowed me to take those forefront issues, which I know are pushing modern physics and also beyond physics,"
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"text": " And those are the areas. And of course, the forefront is just at the edge of knowledge. Literally, it's where we where we there are questions we have, but we don't know the answers. And I think that's the most exciting thing for people. And I think I wrote at the end of the book for a young person. When I was young, I read a book that got me excited about physics to realize the questions weren't all answered. And so I tried to focus on the most exciting questions and the neat thing about it."
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"text": " The thing that made it particularly attractive is that those questions are the same questions that we all have about the universe. How did the universe begin? How will it end? Are we alone in the universe? How did life begin? These are the forefront questions of science, but they're the questions that in one way or another, everyone asks themselves. And it seemed a lovely way to touch, to tap into that common interest. The questions, how will the universe begin? How will it end? How did life originate? Are we alone in the universe?"
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"text": " When I see green is the same green as you see, what's consciousness? Those fundamental questions are really the things that are driving science and it's kind of satisfying that they are the same ones that interest people. So I always in my books try to think of ways to get people interested, more interested than they are to encourage them to ask questions and that's really the big point and a book about questions which is really what this is."
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"text": " is really a book about learning because learning should be done by asking questions. Do you find that when you write books, it helps you clarify your own thinking? Of course. No, it always does. I mean, that's one of the reasons I write books. That's one of the reasons why I write books. Because, well, there are two reasons. Well, three reasons. One, because I want to repay the favor when I was younger. It was books about science that got me interested in being a scientist and it's nice to return that favor. But also,"
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"text": " When I write books, you could write the same book over and over again. I know a lot of people who've done that. I won't mention names. But in each book, I try and tackle things I'm aware of, but try and push my own boundaries. So it becomes a learning process for me as well. So it's a combination. Writing a book allows me to study a topic that I might not have the discipline to study otherwise if I don't know it. And if I do think I know it, it allows me to explain it and many, many times"
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"text": " As you say, I realize I understand things more than I did, or in a different context. For example, the chapter on consciousness, I had ideas and biases about the nature of understanding consciousness, but this forced me to delve into those ideas more carefully and try and even define what consciousness was, which is"
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"text": " Which is not the case. Another example is the origin of life. I'd led through the institute, I ran at a university, meetings a decade or two ago on the origin of life. And this allowed me to say, well, okay, I understand what those issues are, but what's been happening since then? And what are the key things that are being understood? I mean, long ago, and I remember in the first book I ever wrote, which is about dark matter, I was writing about particles called axions."
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"text": " And I was writing about symmetries of nature and I realized in the context of axions and these symmetries that there was an experiment that showed"
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"text": " That gave strong constraints on one symmetry of nature but i realize in the process of writing it that i absolutely didn't understand it and i thought i did i understood what was needed to know but when i tried to explain it i realized hey there's problems now i think about it is that really right and that that happens to me every book i write and it's fun it's it's fun."
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"text": " But it's also fun to learn stuff. And so I, you know, they're not all books on total new topics. So I wrote a book on the physics of climate change, which again, I've been tutored and over the years, especially as chairman of the board of sponsors, the Bolton Atomic Sciences for a decade. But but to go into the detailed history and understanding of climate science, that was a new area was also the beginning of the pandemic. So I had nothing else to do. So so I was able to do it. But and in this book, because it's very broad, it's really all of science."
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"text": " Time, space, matter, life, consciousness. There are obviously areas where I knew I'd want to really read up and again the consciousness chapter probably was your favorite. Well I don't know it's my favorite, no it was the hardest which is one of the reasons why I left it to the end but it was the one where I had to read the most because it was an area where I had a vague understanding and I'd run some meetings"
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"text": " Also on aspects of consciousness, but to really go into it enough to try and say what are the open questions or to reinforce or invalidate my a priori bias that we don't understand consciousness, I had to really try and see what explanations people gave for consciousness."
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"text": " Are there any interesting older sources that you looked at for any of your chapters, let's say the life and the consciousness one? I looked at older sources. What I like about the first chapter, which is on time, is I go back to black holes and I talk about this guy, Michel, who was an unsung hero of science a hundred years after Newton, who really was the first person to come up with the idea of black holes. It was fun to research"
},
{
"end_time": 705.862,
"index": 28,
"start_time": 677.346,
"text": " his own, you learn about him. There are some amazing scientists who really are unsung, and in the modern world they'd be at the very top, but they've sort of disappeared in the dustbin of history, I guess, in one way or another. And then same with, you know, with consciousness, going back to the early people who looked at consciousness, the early, the first neuroscientists and psychologists looking at their work and seeing how much or little had changed since then."
},
{
"end_time": 735.725,
"index": 29,
"start_time": 706.22,
"text": " You know, and of course, when it comes to the origin of life, that's an area where there's been a huge number of developments. The origin of life has to be distinguished, as I tried to explain in the chapter first, from the origin of the diversity of life. That's, you know, evolution, which is, well, there are open questions with evolution. That's an area of science that's well-trodden. But to go back to determine how chemistry turned into biology is right at the forefront. But we have to start thinking about the early stages of"
},
{
"end_time": 755.776,
"index": 30,
"start_time": 736.22,
"text": " of the discovery of dna and how did such a complex molecule rise and then it was an amazing discovery of course i've actually an old colleague of mine when i taught at yale he was my dean and i and i you know i i still don't have a great opinion of deans but he was a good guy but i never realized he was a great scientist till after he stepped down and being dean and he won the noble prize"
},
{
"end_time": 776.271,
"index": 31,
"start_time": 755.998,
"text": " And I realized his work on RNA was essential. It showed that a precursor world to a DNA world could have been an RNA world. And so it's fun to go back and see the development of ideas. And I think that's another thing about science."
},
{
"end_time": 793.404,
"index": 32,
"start_time": 776.783,
"text": " In some ways it's storytelling, it's not all storytelling, but I think people appreciate a story. And the human interest aspect of a story, how the red herrings or how we got to where we go is something that's interesting and worthwhile talking about. We don't often always talk about it in lecture courses, but I think in books it's fun to do that."
},
{
"end_time": 823.2,
"index": 33,
"start_time": 793.404,
"text": " Yeah, well, in books it seems necessary because you have to open a chapter with something that's human and relatable to the general public. Well, I think you do. Yeah. Statistics to the scientist. It's like that's what we find interesting. Well, exactly. But you know, people are interested in things they don't know they're interested in. And I think the key point is to convince them they're interested in things. I often tell teachers that the biggest mistake they make is assuming their students are interested in what they have to say. You have to convince them to be interested. So you have to go to where they are and try and reach out and grab them and say, this is interesting."
},
{
"end_time": 852.875,
"index": 34,
"start_time": 823.541,
"text": " And then, you know, it's like many people are afraid of science, but they don't realize they're interested in it. When you talk about warp drive or time machines, they suddenly get interested and they don't realize it's kind of forefront science. Yeah. Tim Modlin was saying that his favorite parts of most physics courses, most science courses in general, are the first lectures because they're selling you on the course. So he's like, when I went to quantum field theory, they told me about this is the most impactful theory in science. And then lecture three is on Green's functions. He's like, well, what happened to"
},
{
"end_time": 881.971,
"index": 35,
"start_time": 853.302,
"text": " Studying what is and when you ask what is they're like, oh that's philosophy actually don't even ask that here Yeah, well, I mean, you know, there's a lot well quantum field theory is certainly always been and probably well I don't know if it remains but it's always been the most challenging class to teach in graduate school and or to take and there's just a lot of stuff and a lot of intellectual baggage that you need to do and you can't and and before you can philosophy is useful for framing initial questions and"
},
{
"end_time": 906.032,
"index": 36,
"start_time": 882.483,
"text": " But physics has long gone beyond those initial questions so that it's driven by questions that are often quite mathematical in nature. And people don't realize that you can't just sort of start with those questions and expect to reach anything without going through the remarkable baggage that's been developed and that has taken you far away from the questions."
},
{
"end_time": 935.026,
"index": 37,
"start_time": 906.442,
"text": " So, you know, what is, is a fancy question, but it actually, as I talked about in Universe for Nothing, that the whole concept of something and nothing just changed dramatically because of physics. And people don't like that, but I don't care. It's the way it is. It's called learning. And we now realize, as a matter of fact, because of quantum field theory, that the difference between something and nothing is not so great as imagined before, because nothing has lots of something in it. Yeah. Let's speak about that for a moment."
},
{
"end_time": 955.196,
"index": 38,
"start_time": 935.725,
"text": " When I was younger, I remember questioning the universe and I couldn't figure out how anything could come from nothing and that was something that I had asked my brother who was studying physics at the time and then he mentioned quantum fluctuations and I was eight or so and then it was approximately that point that I became an arrogant and inexorable atheist."
},
{
"end_time": 985.299,
"index": 39,
"start_time": 955.606,
"text": " Your brother, your brother did God's work, as we say. I realized years later, that's not an explanation to say vacuum. But I didn't know that at the time. So because I didn't know, I thought that that was an explanation. However, you have now figured out some way of making that indeed an explanation. So can you cover that, please? How you get something for nothing? You mean how the universe can come about from vacuum fluctuations? Yeah, well, yeah, I can give you a summary. As I said, I wrote a whole book about it. So it's kind of but"
},
{
"end_time": 1014.462,
"index": 40,
"start_time": 986.425,
"text": " Look, the key aspect of quantum mechanics, which I do talk about in the new book, is that the quantum universe, many things are happening at the same time. And in particular, quantum fluctuations are happening all the time. We can't see them, but quantum systems are constantly fluctuating. And when you combine quantum mechanics and relativity, it's even more exciting because it says that"
},
{
"end_time": 1041.596,
"index": 41,
"start_time": 1016.476,
"text": " that empty space isn't empty. So the key thing about quantum mechanics when you combine it with relativity and I've described this in a number of my books, it implies that empty space isn't empty. I mean it has no real particles but over time scales that are so short that you can't measure them directly, and this is the uncertainty principle of quantum mechanics, things can happen that you can't see."
},
{
"end_time": 1071.51,
"index": 42,
"start_time": 1041.971,
"text": " And in particular, particles can pop into existence that weren't there before and then pop out of existence in a time scale so short that you can't even see them. Those are called virtual particles. It may sound like counting angels on the head of a pin if you say, well, these particles are there, but you can't see them. Well, we can't see them directly. What we can do is see their effects indirectly. We know they're there because we have an impact on the on the atomic energy levels of atoms. They allow us to calculate the atomic energy levels of atoms with an accuracy"
},
{
"end_time": 1100.265,
"index": 43,
"start_time": 1072.005,
"text": " That's unprecedented in all of science. So we know we have to include the fact that on small scales and small times, particles are popping in and out of existence. It's quantum fluctuations in quantum fields. That's why quantum field theory is relevant. Allow you to produce particles that appear and then disappear. Fine. Well, that's for normal quantum field theory with particles in space and time. But gravity is a theory of space and time."
},
{
"end_time": 1125.572,
"index": 44,
"start_time": 1101.169,
"text": " And so if gravity is a quantum theory, if gravity is a quantum theory, and that's a big F, we don't know for certain, but we have no reason to suspect it isn't, then the variables of that theory, space and time become quantum mechanical variables, and then space and time can fluctuate. And you can start literally with no space, no time, and then have a little universe with space and time appear and then disappear."
},
{
"end_time": 1151.664,
"index": 45,
"start_time": 1126.613,
"text": " virtual universes can pop in and out of existence and in quantum gravity that kind of phenomena happens but it can happen that if a virtual universe pops into existence with zero total energy then the laws of quantum mechanics and relativity say that that virtual universe in fact can be real, it can exist for an arbitrarily long time and then"
},
{
"end_time": 1174.718,
"index": 46,
"start_time": 1152.466,
"text": " In order for it to not collapse again if it's if it's a starts expanding and not collapses certain processes have to happen but if you asked What would a universe that lit was almost 14 billion years old that? Spontaneously arose from nothing by quantum mechanical processes. What would it look like today? And the answer is it would look just like the universe we live in"
},
{
"end_time": 1204.872,
"index": 47,
"start_time": 1175.657,
"text": " All the properties would be the properties of the universe we live in. Now that doesn't prove that that happened, but it's strongly suggestive that that possibility could explain the existence of our universe. Now it's all possibilities right now because we don't have a quantum theory of gravity. I said if space and time, if gravity is a quantum theory, and it's a big if. We don't have a theory of quantum gravity. String theory is a good candidate for that, but no one knows if it is a theory of quantum gravity."
},
{
"end_time": 1235.009,
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"start_time": 1205.367,
"text": " This Martian beast mode Lynch. Prize pick is making sports season even more fun. On prize picks, whether you're a football fan, a basketball fan, it always feels good to be ranked. Right now, new users get $50 instantly in lineups when you play your first $5. The app is simple to use. Pick two or more players. Pick more or less on their stat projections."
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{
"end_time": 1250.401,
"index": 49,
"start_time": 1235.009,
"text": " Anything from touchdown to threes and if you're right you can win big. Mix and match players from any sport on PrizePix, America's number one daily fantasy sports app. PrizePix is available in 40 plus states including California, Texas,"
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{
"end_time": 1272.09,
"index": 50,
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},
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"text": " And what's the name of that theory? What you just outlined, which is, okay, look, if you have fluctuating quantum fields, and you were to combine general relativity of fluctuating space time itself, universes, it's just a proposal, a vague proposal, like, or is there? It's a it's a it's a no, there's no names attached to it. I propose that other people have proposed it. But it's just a consequence, if you wish, of, of, of having a quantum theory of gravity. And lots of people thought about Hawking and Arnold. And, you know, Stephen Hawking has obviously thought about it a lot. I have other people have"
},
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"end_time": 1323.643,
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"start_time": 1303.063,
"text": " You know that fitness coaches can be expensive. Here in Toronto, in my building, there's someone who charges almost $200 for one session. That's why I was excited when Copilot Fitness approached us."
},
{
"end_time": 1339.224,
"index": 53,
"start_time": 1323.831,
"text": " It's one"
},
{
"end_time": 1363.985,
"index": 54,
"start_time": 1339.531,
"text": " As I'm writing this, my wife said in the background, I'm gonna beat you in it, babe. This is domestic rivalry at its finest."
},
{
"end_time": 1387.159,
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"start_time": 1363.985,
"text": " Changing the coach is as easy as swiping left. In person, there's always awkwardness, but it's wonderfully easy here. For me, however, I didn't have to switch as I love my coach. His name is Rod and Rod is rad. He took his time with me, found out what I was looking for. My wife's coach, Samantha, took the time with her. I recommend this app wholeheartedly. So are you ready to feel fit and fabulous?"
},
{
"end_time": 1413.268,
"index": 56,
"start_time": 1387.159,
"text": " Give Copilot a try. It was even listed by Forbes as the top rated personal trainer app of 2023. Head to go.mycopilot.com slash toe to get your 14 day free trial with your own personal trainer. That's go.mycopilot.com slash to for your 14 day free trial. Ever find yourself questioning reality and then you snap back to it. Remembering that you have nothing planned for dinner."
},
{
"end_time": 1442.415,
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"start_time": 1413.473,
"text": " That's where HelloFresh comes to the rescue. They deliver pre-portioned farm fresh ingredients and seasonal recipes right to my door. And they have over 40 choices every week, which keeps me and my wife exploring new flavors. They've got this quick and easy option that makes 15 minute meals. There's options if you're vegetarian, if you only eat fish. Something I chose personally was the pronto option. Their deliveries show up right on time, which isn't something I can say about other food delivery services."
},
{
"end_time": 1460.845,
"index": 58,
"start_time": 1442.568,
"text": " This punctuality is a huge deal for me and my wife, plus we love using HelloFresh as a way to bond. Cooking together is fun when it's all properly portioned out for you already. So are you still on the fence? Well, it's cheaper than grocery shopping and 25% less expensive than takeout. The cherry on top?"
},
{
"end_time": 1479.155,
"index": 59,
"start_time": 1461.101,
"text": " Head to HelloFresh.com slash 50 theories of everything and use the code 5 0 theories of everything to get 16 free meals plus free shipping. That's 16 free meals people. Don't forget HelloFresh is America's number one meal kit. Links in the description."
},
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"text": " In the limited time that I have to speak with you, I want to ask you a bit about Dyson, your conversations with Dyson, which you talked about. Dyson was thinking extremely theoretically like what could it be? What could it be? Not just for us to live forever before possible being to live forever. What would that mean? Is it possible?"
},
{
"end_time": 1519.838,
"index": 61,
"start_time": 1496.288,
"text": " and he came up with a solution that has to do with well if a conscious being had an infinite amount of cycles that's akin to a living forever. Now I don't know if he has to assume a continuous amount that you can divide space or that you can divide time to but regardless you'll speak about that. He came up with very interesting proposals for how a hypothetical species could do that. We had wonderful debates"
},
{
"end_time": 1549.258,
"index": 62,
"start_time": 1519.906,
"text": " In principle, is it possible for a civilization to live forever? Yes, I'll define it as if it has an infinite number of thoughts. If it has an infinite number of thoughts, then that civilization will survive forever."
},
{
"end_time": 1579.821,
"index": 63,
"start_time": 1550.265,
"text": " And then he said, well, how could you have an infinite number of thoughts? Because when we're thinking, it takes energy, 10 to 20 watts in our brain, which is not a lot, but enough. So clearly, you'd think it would take an infinite amount of energy to have an infinite number of thoughts. And if we only have access to a finite amount of energy, then we can't do that. But then he pointed out that you can have infinite series that converge to a finite number."
},
{
"end_time": 1601.8,
"index": 64,
"start_time": 1580.555,
"text": " The Greeks discovered that and Zeno's paradox for those who know of it or at least we now know a solution of Zeno's paradox. I'm not sure the Greeks exactly figured it out but in any case and so he argued that if that one way to have an infinite number of thoughts would basically be wake up have a thought then go to sleep"
},
{
"end_time": 1632.142,
"index": 65,
"start_time": 1602.449,
"text": " where you're"
},
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"end_time": 1661.357,
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"start_time": 1632.858,
"text": " The problem is briefly before we get to the problem Why is that so remarkable because like you mentioned we've known about infinite series that converge for quite some time now So why did it take Dyson to come up with that? What did he contribute to it that was different that was subtle? Well, I think His His realization that his well you see the point is that because we think in terms of metabolism"
},
{
"end_time": 1681.954,
"index": 67,
"start_time": 1662.688,
"text": " The standard wisdom was that non-zero metabolism will therefore require infinite energy access over infinite time in order to continue because it's always, and I think the cuteness of his example was imagining a system that could basically turn itself off."
},
{
"end_time": 1707.671,
"index": 68,
"start_time": 1682.585,
"text": " and really have a life that many people would not sit well, if you get older, sounds nice, but a life where you're sleeping more and more and more and more, which most people don't think of as a vital civilization. So I think it was his recognition that in an expanding universe, you have to do the equations right. The free energy that you use, the integral of that could be finite."
},
{
"end_time": 1736.613,
"index": 69,
"start_time": 1708.131,
"text": " Even though they're an infinite number of wake-up periods, it wasn't all obvious that you could get it to converge. And so I think it was a combination of that and realizing that if such a system could turn itself off, then you could in principle do that. But there's lots of problems there. Immediately quantum mechanics comes into a problem because quantum fluctuations are such"
},
{
"end_time": 1765.896,
"index": 70,
"start_time": 1736.817,
"text": " It's kind of hard for a system to use zero energy at all. But also, how do you wake up? There was one example. I mean, so you want to wake up, but then you have to have an alarm clock. Well, how do you have an alarm clock that has an infinite number of wakeups that uses less energy? And then we'd come up, we showed them, hey, the alarm crop is going to use an infinite amount of energy. They said, no. He came up with an orbiting planet scheme, which is really tricky for orbiting planets that eventually, or not planets, but orbiting particles where they collide, the alarm goes off."
},
{
"end_time": 1794.667,
"index": 71,
"start_time": 1766.254,
"text": " It doesn't take any energy to orbit a planet and then we point out eventually the laws of quantum mechanics will get you there as well because the uncertainty principle means you can't at some very basic level you can't fix exactly the momentum of two particles and eventually you can't fix it well enough. You can fix it to some certain level of accuracy but if you want them to orbit each other for 10 trillion years before they collide"
},
{
"end_time": 1814.753,
"index": 72,
"start_time": 1794.974,
"text": " Then the uncertainty in their momentum is such that every now and then they're going to miss each other and you'll sleep forever. And they're little things like that. And anyway, and then his final argument was a black cloud like that of the black cloud of, oh, what's his name?"
},
{
"end_time": 1838.217,
"index": 73,
"start_time": 1815.367,
"text": " The Blackout is probably the best science fiction story ever written. It involved the discovery of a cloud and it was realized that the motion of the particles in the cloud encoded intelligence and he argued that that cloud could slowly expand and you could imagine it would live forever."
},
{
"end_time": 1856.732,
"index": 74,
"start_time": 1838.473,
"text": " Ultimately and we're back and forth but ultimately this is before we knew we're having that debate before we knew that the expansion of the universe was. What's the meeting up something actually proposed in a few years later and and then it was discovered to be true."
},
{
"end_time": 1881.425,
"index": 75,
"start_time": 1857.517,
"text": " But we both recognize that if the expansion universe was speeding up, then his arguments would fall by the wayside. There's no way life can exist forever in a universe that's accelerating like we have. Even though we agreed to disagree about what happened in other cases, we agreed about that case. And since that appears to be the case for our universe, it looks like"
},
{
"end_time": 1906.578,
"index": 76,
"start_time": 1881.954,
"text": " It's not good news for the for the future long-term future of life as I like to say the future is miserable Hmm, but it's gonna be a while before it's but before it's gonna get too miserable Trillions of years and with Dyson I sent a YouTube video. It's been a while since I've seen it, but he was saying that gravitons aren't detectable He had some in oh, yeah. Yeah. Yeah. No. No, in fact, actually he said that and then I actually and Actually was in a meeting with him"
},
{
"end_time": 1930.657,
"index": 77,
"start_time": 1907.09,
"text": " When he argued that that he gave a great argument for how all the experiments that are you could detect a Graviton directly wouldn't work and I'm not sure all of his arguments are exactly right but but it was a brilliant like typical dissonant paper was what could you do in principle to do this and in every case showing a real trick for why it wouldn't work but in fact but in fact what I talked at that meeting and he"
},
{
"end_time": 1959.172,
"index": 78,
"start_time": 1931.561,
"text": " He agreed with me ultimately, but I showed him that no experiment we can do on Earth will detect gravitons, but the universe as an experiment can detect gravitons because the universe can do things we can't do, like ultimately have regions that are expanding farther, faster than light away from each other. And I showed him that this process of inflation in the early universe would produce gravitational waves, but only"
},
{
"end_time": 1986.169,
"index": 79,
"start_time": 1960.503,
"text": " which we can measure today, but only if gravity was a quantum theory, in which case there would be gravitons. If we detect gravitational waves from the expanding universe, which we haven't done yet, we've detected gravitational waves from black holes that are colliding, but we haven't detected gravitational waves from the Big Bang or this period called inflation, if we could do that, those gravitational waves would be generated if and only if"
},
{
"end_time": 2015.811,
"index": 80,
"start_time": 1987.073,
"text": " At a very fundamental scales, gravitons were being created and destroyed. And so we could use the universe as a way to prove that gravity is a quantum theory. If we were able to detect gravitational waves from inflation, it would imply that gravitons exist. And so it'd be an indirect way. You wouldn't directly detect them. But the universe in that sense would be a graviton detector. You'd see, just like when a Geiger counter detects a radioactive decay, but I don't see the radioactive decay, what I hear is a click."
},
{
"end_time": 2038.183,
"index": 81,
"start_time": 2015.811,
"text": " You also mentioned in your book about inflation that there are various inflationary models and that some of them can be used to indirectly"
},
{
"end_time": 2067.483,
"index": 82,
"start_time": 2038.848,
"text": " Inflation is an idea more than a theory. You can show that under certain conditions the universe will expand very fast at early times. It's almost generic. The hard part is to get it to stop from expanding very fast because if it didn't stop expanding very fast, life couldn't form."
},
{
"end_time": 2090.572,
"index": 83,
"start_time": 2068.626,
"text": " Exactly how you do that is the context of a model. So you embed that idea in a mathematical model of how the universe is evolving. And there are different models and none of them are very pretty to tell you the truth right now, since I suspect there's things we're missing. But almost all of those models for how you stop expanding, very fast,"
},
{
"end_time": 2115.64,
"index": 84,
"start_time": 2091.22,
"text": " imply that there are actually other universes because what really happens is there doesn't seem to be any way to globally stop the universe from expanding very fast but what you have is sort of like little drops or snowflakes. The background universe is expanding very very fast but within a small region there's a phase transition like a snowflake forming or a raindrop forming out of vapor"
},
{
"end_time": 2143.814,
"index": 85,
"start_time": 2116.015,
"text": " And in that region, you decouple from that background fast expansion and you have a hot big bang. But that means most of the rest of this space is still expanding and somewhere else you decouple and have a hot big bang. But it turns out you can decouple from that expansion. You can have a phase transition in many different ways, just like you can create snowflakes that have many different shapes. And each different way you decouple from that background expansion,"
},
{
"end_time": 2158.541,
"index": 86,
"start_time": 2144.889,
"text": " Can result in different laws of physics."
},
{
"end_time": 2188.148,
"index": 87,
"start_time": 2158.916,
"text": " But generally, if that's true, there are other universes out there that could be quite different that we'll never know about because the space between us and them is expanding so fast. We'll never know about it. That's the multiverse. And moreover, since it goes on infinitely long, you'll eventually get to create an infinite number of such other universes. OK, now we'll never direct detect those other universes. People say that's kind of science fiction or religion or something. But if we could detect, say, gravitational waves from inflation,"
},
{
"end_time": 2215.418,
"index": 88,
"start_time": 2189.377,
"text": " Then we'd be able to probe the exact model of inflation, the characteristic of how we decoupled from that background expansion. And we'd be able to tell which model, if any, of inflation was right and probe its theories. And once we did that, we'd know if that model predicted a multiverse. So we'd know indirectly that there are other universes because we'd probe the model and say,"
},
{
"end_time": 2242.995,
"index": 89,
"start_time": 2215.708,
"text": " That's what happened, but if that happened, there have to be other universes out there. So it's an indirect detection. Just the way in 1905 we knew atoms existed, but there's no one ever figured to be a way to see them directly. We always detected their effects indirectly. We can now more or less see them with fancy kinds of electron microscopes and other things. But all the evidence for atoms, we believed atoms existed shortly after 1905."
},
{
"end_time": 2270.196,
"index": 90,
"start_time": 2243.285,
"text": " Because it explained everything we saw, even though we never thought we'd see one directly. And that's the way it'll be with a multiverse. We'll never detect those other universes. But if we have a theory and we can test it very, very well, let's say we had a theory of inflation that we could test very well, and it made 50 predictions and you tested all those 50 predictions and they were correct. Well, the 51st prediction that you couldn't test, you'd have strong reason to indirectly believe was correct."
},
{
"end_time": 2297.978,
"index": 91,
"start_time": 2270.742,
"text": " Are we currently looking for these primordial gravitational waves? Yes, we're looking in different ways. We thought we discovered them 10 years ago or maybe 8 years ago, something 10 years ago close to. We're looking at ripples in the cosmic microwave background radiation, the radiation from the Big Bang. These gravitational waves would leave a signature that's very hard to detect. I think it was 2015 or somewhere around then, maybe a little later."
},
{
"end_time": 2327.295,
"index": 92,
"start_time": 2298.626,
"text": " to a group of experimentalists thought they detected in fact it was kind of sad because they detected precisely what they thought the signal of such primordial gravitational waves would be with an amount as large as was allowed by other constraints but it turned out that they were they were fooled it was turned out that dust in our galaxy produced the signal that they thought they saw it doesn't mean that you know what it did I shouldn't say it that way it turns out that dust in our galaxy could produce a signal that was as large as what they saw"
},
{
"end_time": 2353.66,
"index": 93,
"start_time": 2327.944,
"text": " It doesn't mean that there wasn't a real signal embedded in that, but because extraordinary claims require extraordinary evidence, the simplest thing to assume is that what you can say is you cannot distinguish it from dust in our galaxy. So more refined experiments are going on in the South Pole and also in South America and in high levels building these probes of the cosmic microwave background radiation that are looking for this primordial gravitational wave signal."
},
{
"end_time": 2382.619,
"index": 94,
"start_time": 2354.053,
"text": " It may not be there at a level that they can see, we don't know. But there are ongoing experiments looking for it. What you referenced was Brian Keating's work? Yeah, yeah. I mean, Brian Keating was part of the first experiment that thought they'd seen those gravitational waves. He was the PI on it, but he was working on it, yeah. And he's working on the subsequent experiments that are trying to refine the measurement. Maybe they'll see it, maybe they won't."
},
{
"end_time": 2411.92,
"index": 95,
"start_time": 2383.336,
"text": " So neutrinos are your favorite particles. That's true. Yes. Yeah. And then there's something called CP violation and there's something called leptogenesis and neutrinos CP. Yeah. Wow. It's going to be this. Please integrate. We're getting quite technical. Okay. You read the book for sure. Well, so I'm a math and physics grad from U of T and the audience tends to be graduate students in physics, math, consciousness, computer science, as well as researchers. Well, I mean, neutrino. Yeah. Neutrinos are my favorite particles because they're most elusive particles."
},
{
"end_time": 2442.517,
"index": 96,
"start_time": 2412.551,
"text": " And it turns out they may be my favorite particles for another reason, they could be responsible for our existence. Because one of the big problems that got me into cosmology and many other people, the first time particle physics was really applied to cosmology was in the 70s or so. One of the big problems is why do we live in a universe of matter? It may not sound like a problem, but it is if you think about it because matter and antimatter are largely indistinguishable. And if you have a hot big bang, you'd think you'd create as much antimatter as matter."
},
{
"end_time": 2472.142,
"index": 97,
"start_time": 2443.404,
"text": " And if you did, then the matter and antimatter would annihilate, you wouldn't have anything left over. So there had to have been a slight excess of matter over antimatter early on. How was that created? We still don't know the answer, but we have ideas for how it might happen. But there are problems with all those ideas. If you create just these particles called baryons, which are like protons and neutrons, and you make a slight excess of them, then it turns out there are later things that can happen in the universe that will erase that excess"
},
{
"end_time": 2501.527,
"index": 98,
"start_time": 2472.756,
"text": " Or you require a theory that has parameters that we've already ruled out. And Andrei Sakharov, who later won the Nobel Peace Prize, was a brilliant Russian physicist, the father of their atomic bomb, who in 1967 gave three conditions that are required to have more matter than antimatter. You have to have a departure from thermal equilibrium. You have to have"
},
{
"end_time": 2531.561,
"index": 99,
"start_time": 2502.329,
"text": " The theory has to allow you to violate what's called baryon number, baryons and anti-baryons, distinguished protons from anti-baryons. It also has to have what's called CP violation or time reversal invariance violation. So it has to violate matter and anti-matter have to be different in a fundamental way, very small way but different. So you have baryon number violation but also matter and anti-matter can't be quite the same. They have to have some different interactions."
},
{
"end_time": 2559.241,
"index": 100,
"start_time": 2532.073,
"text": " And he showed that if those three things were true, if you had a theory that those three things are true, then you could generate an asymmetry in the early universe that would produce more matter than antimatter. The problem was in 1967, none of those things were true. The standard model at the time didn't have baryon number violation. There was no evidence of any need for out of equilibrium processes in the early universe. And it certainly didn't have CP violation. Well, CP violation had just been discovered in 1965."
},
{
"end_time": 2579.343,
"index": 101,
"start_time": 2560.759,
"text": " And of course, since then, our theories of going beyond the standard model include all of those things. The grand unified theories have very a number of violation almost automatically. Maybe they have CP violation, but it turns out it's hard to make them work. But what has been recognized is, well, the neutrino sector is largely unconstrained."
},
{
"end_time": 2605.828,
"index": 102,
"start_time": 2580.367,
"text": " Because we've measured CP violation in the observed sector of the rest of particles, but because neutrinos are so elusive, it's been very hard to do experiments on them. And it's quite possible, especially if neutrinos are their own antiparticles, then that violates something called lepton number. An electron has lepton number one, an anti-electron has lepton number minus one."
},
{
"end_time": 2632.073,
"index": 103,
"start_time": 2606.527,
"text": " But if I, it turns out, well, if neutrinos are only, are their own antiparticles, and if they have a mass, I should say that, and if they have a mass, that mass will, that will require you to violate lepton number. Namely, you could create two neutrinos out of nothing, okay? And instead of a neutrino and an antineutrino, because an antineutrino and neutrino are the same thing, right?"
},
{
"end_time": 2657.807,
"index": 104,
"start_time": 2632.756,
"text": " The lepton sector via neutrinos is very unconstrained and it's been realized that maybe if there's CP violation in the neutrino sector, if not only our neutrinos are on antiparticles but there's CP violation, then you could have a process in the early universe that's now unconstrained by our experiments that if you wish would produce more neutrinos and antineutrinos."
},
{
"end_time": 2686.715,
"index": 105,
"start_time": 2658.319,
"text": " But in order for that to happen, you probably have to have extra kinds of neutrinos that we can't see right now. And if that happened, then basically those interactions and the decays of those particles would be fed into the visible sector and end up producing more electrons and anti-electrons and more protons and anti-protons. So basically you'd produce the isometry between particles and anti-particles in the neutrino sector and that would feed down"
},
{
"end_time": 2699.633,
"index": 106,
"start_time": 2687.159,
"text": " and eventually give us more matter than antimatter. It's called leptogenesis. And right now, many people think that might be the most attractive possibility for how we end up getting more matter than antimatter in the universe."
},
{
"end_time": 2730.026,
"index": 107,
"start_time": 2700.265,
"text": " Two questions, is there a consensus right now to whether neutrinos have mass? Neutrinos have mass because they've been measured to oscillate between the electron neutrinos, muon neutrinos and town neutrinos oscillating to one another in a way that wouldn't produce measurable effects if they didn't have mass. Their mass has to be very small, we haven't measured their mass directly. We don't know exactly which mass, which particles heavier, all of those things are open questions."
},
{
"end_time": 2759.838,
"index": 108,
"start_time": 2730.265,
"text": " But we do know that neutrinos have mass, and in fact in the standard model that's not really an easy thing to put in. So already that's indications that there's physics beyond the standard model. So that's another thing that's great about neutrinos because they're pointing us in the direction of sort of beyond the standard model of particle physics. So the inconsensus is what mechanism? Is it the seesaw mechanism or is it something else? Like we know it has mass, it's just what produces it? Yeah, we just don't know. I wouldn't call it lack of consensus, I'd just say we don't know."
},
{
"end_time": 2782.142,
"index": 109,
"start_time": 2760.179,
"text": " There's a lot of ideas for where neutrinos get their mass and what their masses might be, but right now we don't even have the experimental data to be able to distinguish between them. There's a long baseline experiment in Fermilab that's going to shoot neutrinos to a detector in South Dakota."
},
{
"end_time": 2811.886,
"index": 110,
"start_time": 2782.602,
"text": " Yeah. And if I heard correctly, I believe you said that in order for leptogenesis to occur, there has to be other kinds of neutrinos that we don't currently observe. And are you referring to right-handed or are you referring to like new generations? I'm referring to right-handed neutrinos. Yeah, heavier right-handed neutrinos. Generally, that's the case. Yeah. And then those can feed down into normal because they're unstable."
},
{
"end_time": 2839.497,
"index": 111,
"start_time": 2812.534,
"text": " As far as I recall, neutrinos propagate as mass eigenstates, but they're detected as flavor eigenstates. That's the reason, yes, but that's the reason they oscillate. Because the mass eigenstates are not the weak eigenstates, if you want. So the particle that's propagating is not an eigenstate of"
},
{
"end_time": 2868.507,
"index": 112,
"start_time": 2839.565,
"text": " Well, if you want to think of it,"
},
{
"end_time": 2891.783,
"index": 113,
"start_time": 2868.814,
"text": " It's not a bad analogy. It turns out the weak eigenstate, the thing we label as electron neutrino, is a superposition of mass eigenstates. So it's like saying that a particle that's in the spin half is in a superposition of spin up and spin down or spin up and spin sideways or whatever you want to do, call it. So it's in a quantum superposition of two different states."
},
{
"end_time": 2919.667,
"index": 114,
"start_time": 2892.125,
"text": " And sometimes you measure and it's fine to say that sometimes you measure it and you measure, you know, it's like if you're in a superposition of a spin up and spin down, if the particles oscillating, let's say in a magnetic field, sometimes you'll measure it spin sideways and sometimes you'll measure it spin up. And this is somewhat similar to that. Sometimes as the particles propagating, you'll measure it and you say, oh, it's an electron neutrino. And other times you'll measure it and say, no, it's a muon neutrino."
},
{
"end_time": 2940.538,
"index": 115,
"start_time": 2920.776,
"text": " It's not that bad an analogy. It's saying because the mass eigenstates aren't the weak eigenstates, another way of saying that is the weak eigenstates, the flavor eigenstates are linear superpositions of the mass eigenstates, but that also implies that the mass eigenstates are linear superpositions of the flavor eigenstates."
},
{
"end_time": 2970.213,
"index": 116,
"start_time": 2940.794,
"text": " So it's not like you can say, okay, well, which one is more fundamental? It's like you can draw your bases in any way. So well, I mean, one, well, I mean, yeah, well, you don't I mean, mass is energy is fundamental in terms of propagating in space and time energy and momentum. So they determine the states that propagate the mass eigenstates are the ones that propagate. Sorry, if this is a foolish question, I just don't know. No, no, no, no. No. So but but point is, it's kind of"
},
{
"end_time": 2994.957,
"index": 117,
"start_time": 2970.674,
"text": " It would be arbitrary if it weren't for the fact that the other particles we measure, like electrons and muons and stuff, that their mass eigenstates are weak eigenstates and so they're good labels. For all the other particles that we measure, the ones that make us up, electrons and protons, they're labels because they have electric charge. Those are good labels."
},
{
"end_time": 3023.404,
"index": 118,
"start_time": 2995.606,
"text": " But the neutrino is neutral and so the label we give it is somewhat arbitrary for it. Okay. Now you have studied dark energy and dark matter plenty. So there's some people that say, well, it's not matter. It's a modified gravity. What do you make of that? There's also something called teleparallel gravity. There's lots of ideas. I don't know. Every week there's a new proposal. The simplest proposal is that it's the energy of empty space."
},
{
"end_time": 3040.794,
"index": 119,
"start_time": 3024.002,
"text": " For dark matter, it's not anywhere near as exotic, it's just a new kind of elementary particle and the standard model and every theory that goes beyond the standard model predicts a host of such particles whether they're wimps or supersymmetric particles or axions."
},
{
"end_time": 3055.265,
"index": 120,
"start_time": 3041.135,
"text": " You can't create a model that goes beyond the standard model. Maybe you could, but it's very hard to do without dark matter candidates. As my friend Frank Wilchick used to say, it's the most radically conservative assumption."
},
{
"end_time": 3083.012,
"index": 121,
"start_time": 3055.845,
"text": " Which is what you do in physics, right? It's much more conservative to say there's a new kind of elementary particle, since we expect there will be, than to say that gravity, if one of the fundamental forces in nature, somehow gets modified in exactly the right way on the scale of galaxies to produce the weird effects that we see. That's why I find dark matter, the particle explanation for dark matter to be far more compelling theoretically and observationally than anything else."
},
{
"end_time": 3099.292,
"index": 122,
"start_time": 3084.224,
"text": " Okay, now let's talk about infinities briefly."
},
{
"end_time": 3123.08,
"index": 123,
"start_time": 3099.872,
"text": " It's a reflection of our ignorance about the fundamental laws. But still to this day, some people think of renormalization. Even some physicists, I was speaking to one off air and he said, no, no, it's still sweeping infinities under the rug. So what is your view? No, no, no. Look, look, the point that my view is that the mistake of thinking of infinities is the mistake of thinking that any theory is good at all scales."
},
{
"end_time": 3151.971,
"index": 124,
"start_time": 3123.746,
"text": " We used to think of electromagnetism as a theory of nature, and it's true for all scales, but it's not true for all scales. We know in fact that at a small enough scale, electromagnetism unifies with the weak interaction. So if you take your theories and you do your integrals up to infinity, you're assuming the theory works at a scale where it may not work. So it's making vast assumptions about what happens at scales you can't measure. It turns out that the sensible theories that we can measure at low energies"
},
{
"end_time": 3176.049,
"index": 125,
"start_time": 3152.227,
"text": " are ones that are insensitive to the new physics that is inevitably going to happen at those high scales. And renormalization is just a way of separating out what we can measure and know from the physics that is irrelevant at low scales. It's relevant, but it's suppressed by powers of very large masses."
},
{
"end_time": 3190.623,
"index": 126,
"start_time": 3176.391,
"text": " Any new physics that comes in has an effect that goes like one over m the mass scale of which it comes in and so we're normalization is just a way of basically systematically separating out those higher order effects that are relevant."
},
{
"end_time": 3220.316,
"index": 127,
"start_time": 3191.015,
"text": " And if there are no theories, you can take that mass to infinity. And renormalizable theories are theories that make sense if you take that mass to infinity, if you take the scale of any new physics to infinity. If they weren't, if they were sensitive to high energy physics scales, then they wouldn't be renormalizable, but then they wouldn't be the theories we see anyway, because it would depend on new effects. The whole notion of associating with infinities is just because we don't know what the physics is."
},
{
"end_time": 3248.899,
"index": 128,
"start_time": 3220.947,
"text": " We say, well, if it were infinitely big, how can we dissociate that from the level of the physics we measure? But it's really just equivalent to the statement, and this is Wilson's recognition, that those new theories at very high scales are relevant to understanding the physics at scales we see, but the theories evolve with scale. And eventually, that high-scale physics will be important."
},
{
"end_time": 3266.766,
"index": 129,
"start_time": 3249.514,
"text": " And in fact, the physics that you can't always that some of the physics you can always see will will change the way in which those theories change with scale. One of the ways we look for new physics at the Large Hadron Collider is to is to look to see if the if the"
},
{
"end_time": 3294.445,
"index": 130,
"start_time": 3267.244,
"text": " if the strength of the weak and electromagnetic forces are scaling as you think they would. If they're not, then it may implies new virtual heavy particles that are contributing to the way those forces are behaving and it would be a signature of new physics. So it's not a matter of sweeping infinities under the rug. It is if you do the mathematics, but physically what you're just saying is I don't know what the new physics is and I'm going to isolate that physics that I don't know"
},
{
"end_time": 3308.626,
"index": 131,
"start_time": 3294.77,
"text": " And define a theory that works at this and that's defined and works at this scale and gives all the relevant answers at this scale at another scale the theory may change so we really realize there are no fundamental theories in nature all physical theories evolve."
},
{
"end_time": 3336.971,
"index": 132,
"start_time": 3309.343,
"text": " With TD Early Pay, you get your paycheck up to two business days early, which means you can grab last-second movie tickets in 5D Premium Ultra with popcorn, extra-large popcorn,"
},
{
"end_time": 3367.892,
"index": 133,
"start_time": 3340.555,
"text": " I want to keep you for too much longer as there's a hurricane that's impending and I would like to speak to you again. Yeah, we good. This is certainly a fun and detailed conversation that's more detailed than I usually get to do online. Yeah, so you mentioned that the Hicks field is like a Bose Einstein condensate."
},
{
"end_time": 3394.292,
"index": 134,
"start_time": 3368.643,
"text": " Now I don't know if you meant that poetically or literally. No, it is a condensate. As you know, and maybe your listeners know, that no two fermions can exist in the same state, but you have bosons, particles with zero spin or spin one, they can condense. They all want to be in the same state. And when they're in the same state coherently, it looks like a classical field."
},
{
"end_time": 3416.186,
"index": 135,
"start_time": 3394.838,
"text": " That's why we can measure electric fields, because photons can exist coherently in the same state. Enough of them, enough quantum particles add up so the effect looks classical. Well, the Higgs field is a condensate of particles, of Higgs particles, and that exists in empty space."
},
{
"end_time": 3433.541,
"index": 136,
"start_time": 3416.476,
"text": " It's like a background field. It's like a background electric field. It's just we don't measure it as an electric field. We can't measure it directly but the way we can measure it is by hitting it really hard with particles and then we knock other particles out and that's basically what we do at the Large Hadron Collider."
},
{
"end_time": 3461.63,
"index": 137,
"start_time": 3434.189,
"text": " And so the Higgs field is really a Bose condensate of particles. A Bose condensate of particles is a background field that's made of a coherent superposition of many, many quanta of the Higgs field, which are Higgs particles. Well, professor, you got to get going and I could speak to you for another three hours, maybe longer. We'll speak again. Yeah, yeah, I would love to. And so why don't you tell the audience, what are you working on next? Are you writing another book?"
},
{
"end_time": 3489.735,
"index": 138,
"start_time": 3463.387,
"text": " I am probably writing another book. I just finished some work on ways to maybe test ideas of quantum gravity in the laboratory by using fluids. We have a paper that just came out in Nature Physics that's not yet appeared in print but it's just been accepted and appeared online. I'm writing a new book but it's probably not going to be a science book of the type that you're used to."
},
{
"end_time": 3515.947,
"index": 139,
"start_time": 3490.094,
"text": " There's a number of possibilities. Fiction? Well, fiction is one of the possibilities, probably not for this book, but there will be a fiction book coming out. This book will either be, I've started because enough people have asked me to write a scientific memoir, to write a scientific memoir, so I've started it. We'll see how long my patience lasts. I've known many, many, many interesting scientists and other people over the years and"
},
{
"end_time": 3539.889,
"index": 140,
"start_time": 3516.425,
"text": " The link to that will be in the description. Thank you so much for spending your time with me during this tumultuous weather."
},
{
"end_time": 3570.333,
"index": 141,
"start_time": 3540.503,
"text": " If you have questions for Lawrence Krauss then leave them below in the format query by writing the word query with a colon and then your question. The podcast is now concluded. Thank you for watching. If you haven't subscribed or clicked that like button now would be a great time to do so as each subscribe and like helps YouTube push this content to more people."
},
{
"end_time": 3600.35,
"index": 142,
"start_time": 3570.418,
"text": " You should also know that there's a remarkably active Discord and subreddit for theories of everything where people explicate toes, disagree respectfully about theories, and build as a community our own toes. Links to both are in the description. Also, I recently found out that external links count plenty toward the algorithm, which means that when you share on Twitter, on Facebook, on Reddit, etc., it shows YouTube that people are talking about this outside of YouTube, which in turn greatly aids the distribution on YouTube as well."
},
{
"end_time": 3621.152,
"index": 143,
"start_time": 3600.35,
"text": " Last but not least, you should know that this podcast is on iTunes, it's on Spotify, it's on every one of the audio platforms, just type in theories of everything and you'll find it. Often I gain from re-watching lectures and podcasts and I read that in the comments, hey, toll listeners also gain from replaying, so how about instead re-listening on those platforms?"
},
{
"end_time": 3650.435,
"index": 144,
"start_time": 3621.152,
"text": " iTunes, Spotify, Google Podcasts, whichever podcast catcher you use. If you'd like to support more conversations like this, then do consider visiting patreon.com slash Kurt Jaimungal and donating with whatever you like. Again, it's support from the sponsors and you that allow me to work on toe full time. You get early access to ad free audio episodes there as well. For instance, this episode was released a few days earlier. Every dollar helps far more than you think. Either way, your viewership is generosity enough."
}
]
}No transcript available.