Is string theory still worth exploring? | Roger Penrose and Eric Weinste...

Is string theory still worth exploring? | Roger Penrose and Eric Weinstein battle Brian Greene The Institute of Art and Ideas 381K subscribers Subscribe 5.6K Share Download Clip Save 360,292 views Premiered Jul 16, 2023 #StringTheory Roger Penrose and Eric Weinstein go at loggerheads with Brian Greene over the relevance of string theory today. We previously saw Weinstein and Greene battle it out over the string theory community's toxic culture. Today we get to see physicist Roger Penrose join the the dissention, weighing in on whether the once revelotionary theoretical framework is a thing of the past. Watch the full debate at https://iai.tv/video/the-trouble-with... String theory has been dominant in theoretical physics for thirty years, with more scientific papers arising from it than any other theory. But critics argue the theory has held undue influence and it is an error to pursue it. Is it time to move on from string theory, recognise that the search for supersymmetry has failed, and seek alternative accounts of the universe that are supported by observation and experiment? Or is the continued dominance of string theory justified by its potential to unify our understanding of the universe once and for all? #StringTheory #TheoryOfEverythingInTheUniverse #StringParticles Eric Weinstein is a mathematical physicist and the host of the podcast The Portal. He is the former Managing Director of Thiel Capital in San Francisco and was formerly a Co-Founder and Principal of the Natron Group in Manhattan as well as a Visiting Research Fellow at Oxford University in the Mathematical Institute. Sir Roger Penrose is a world-renowned physicist, best known for his work on general relativity and sharing the Wolf Prize for Physics with Stephen Hawking for their work on black holes. His books include The Road to Reality and The Emperor’s New Mind. Brian Greene is renowned for his groundbreaking discoveries in superstring theory and best-selling books. He has been chairman of the World Science Festival since co-founding it in 2008. The Institute of Art and Ideas features videos and articles from cutting edge thinkers discussing the ideas that are shaping the world, from metaphysics to string theory, technology to democracy, aesthetics to genetics. Subscribe today! https://iai.tv/subscribe?utm_source=Y.. . For debates and talks: https://iai.tv For articles: https://iai.tv/articles For courses: https://iai.tv/iai-academy/courses Transcript Transcript Search in video Intro 0:00 It's outrageous. The theory is outrageous. Quantum theory as a whole is wrong. It's not Einstein 0:06 was wrong. Quantum mechanics is wrong. What do consciousness, the measurement problem, and black 0:14 holes have in common? With characteristic boldness, Sir Roger Penrose outlines his 0:20 controversial views on the collapse of the wave function. The Schrödinger equation, quantum theory as a whole is wrong. The role of gravity in quantum mechanics. The principle of equivalence, 0:31 which is the basis of general relativity, is in conflict with the principle of superposition. 0:37 And his own radical theory of cyclic cosmology. I don't believe in inflation. That is the idea that 0:44 our universe evolved from a previous universe, and gives rise to another, forming an ever-repeating 0:51 cycle. Penrose doesn't just poke holes in existing theories, he offers ambitious frameworks like 0:57 twistor theory that could potentially unify quantum theory with general relativity. My 1:02 name is Curt Jaimungal. This episode was filmed on location at the Math Institute at Oxford, 1:09 directly after our interview at the Institute for Arts and Ideas. It's a rare in-person glimpse into 1:16 one of the most influential mathematicians and physicists of the 20th century. Sir Roger Penrose, Cosmology and Twistor Theory 1:24 it's been a long time coming. I've been a huge fan for, I think, decades. Literally decades. Thank 1:31 you. And welcome. My pleasure. Good meeting you at the Institute for Arts and Ideas. Lots of people 1:38 don't believe some of them. The arts and ideas? What do you mean? Well, the ideas about cosmology, 1:44 which I have, which are... Certainly, people have a lot of trouble believing them. Even though we 1:51 have good evidence. Still, never mind. Is that the torch that you want passed on most? The 1:58 conformal cyclic cosmology? Well, I have a trouble because there's more than one thing. You see, one 2:03 of the things is twistor theory and its progeny. There's been a conference. You see, this is taken 2:10 seriously in the sense that there has been a conference going on, all about twistor theory. 2:16 Not just a conference, but a whole term, I think, dedicated to the subject of twistor theory, which 2:25 is something which I sort of started in 1963, I think it was. And it's had many developments and 2:35 many offspring, you might say. And it's spread out to have interest in different areas. Now, it's one 2:45 of the things that I've been working on for most of my life. And I can't explain it without being 2:50 a little technical. It's just that... You can feel free to be technical on this podcast. Okay. 3:00 It's a bit like... Well, Hamilton discovered quaternions, which was a way of talking about 3:06 the geometry of three-space. And he introduced this thing called the vector product, which 3:12 if you have two vectors... Well, it's really an algebra of vectors. You have vectors and scalars 3:18 mixed together. And if you multiply two vectors, you have this thing called a cross product, which 3:23 gives you a third vector. Now, this kind of notion is coming in at a different level with what I call 3:33 twistors, or now what I call bitwistors. See, the twistors... The subject took ages to develop. As I 3:41 say, 1963, when I first had the concept, which... So I gave a talk in Cambridge just recently, 3:50 where I explained the origin of the ideas. And there was a certain, you might call it, slight 3:57 misconception. There are two different concepts which get confused in twistor theory. And these 4:02 two concepts are positive and negative frequency, and positive and negative helicity. And the thing 4:09 is that the positive-negative frequency idea was something that I learned from Engelbert Schuching, 4:16 who was somebody I shared an office with when I was in a group of people working on general 4:24 relativity in Syracuse, New York State, in the United States. And there were a lot of 4:33 people working on relativity theory there. And this was, I think, in 1962. And I learned from 4:42 Engelbert Schuching two things which I found very interesting. One of them was this question of what 4:50 you mean by... What's important in quantum field theory? And he said the most important thing in quantum field theory is the splitting of field amplitudes into their positive and negative 5:01 frequency parts. You keep the positive frequency and you throw away the negative frequency. And 5:07 I thought, gosh, that's an interesting idea. The other thing he told me was... And he told 5:13 me various things, but these were the things of relevance to what I'm saying. The other thing he said was to do with the Maxwell field equations. Maxwell's equations, which are very important, 5:24 they describe electricity, magnetism, and light. So it's a theory of light, as well as how electric 5:32 and magnetic fields interrelate to each other. Very beautiful equations, which I learned about 5:37 when I was a graduate student. And I was very keen on the Maxwell equations, especially when 5:43 you write them in this formalism called two-spinor formalism, which I can say a bit more about later. 5:50 But the Maxwell equations, he told me they are conformally invariant. So they only depend on 5:56 space-time structure independent of the scaling. So if you magnify the scale up or down, magnify 6:04 the metric up or down, if you like, it makes no difference. That's conformally equivalent. So the conformal maps are ones, or the conformal transformations are ones which can change the 6:14 scale, but they don't change the... Well, they don't change the light cones in special relativity 6:21 terms. So the speed of light is the same. Of course, light, after all, speed of light is the 6:27 same when you magnify and change the scale. But what struck me about this, these two facts that 6:35 I learned from it, is there seemed to be a little of an impasse between the two. I mean, how do you 6:41 decide what's splitting the positive and negative frequency? You look at the individual frequencies, which means you do a Fourier decomposition. And you take each individual Fourier component, 6:51 and you split that into its positive and negative parts. That's not conformally invariant. You do a 6:56 conformal map, conformally scaling, the Fourier decomposition does not go into itself. And so 7:04 I thought it would be lovely to have a way of looking at this, which is, they come together, 7:09 and you don't have this sort of impasse between the two. Well, I was aware, I don't know whether I 7:16 was told or I thought about it myself, I was aware of the fact that if you take the field of complex 7:23 numbers, fold them up into a sphere, so you've got a point at infinity as well, and you take the real 7:29 numbers, and think of that as the equator. So the real numbers go around the equator, and the complex numbers go up and down. And if you have a function which is defined on the equator, 7:40 which extends into one hemisphere, that's positive frequency, if it extends into the other 7:46 hemisphere, it's negative frequency. This is a completely conformally invariant description. You 7:51 conformally invariant the sphere, and it doesn't change the splitting into two halves. So I wanted 7:57 a way of doing this, but globally for space-time. So for the whole space-time, I wanted it to be 8:05 somehow that the real space-time is the boundary between two extensions into the complex. But if 8:11 you just complexify space-time, make all your coordinates complex, you get an eight-dimensional space, not a five-dimensional space. That's no good. It doesn't split it into two halves at all. 8:22 You get a thing called the forward tube, which is a little tiny thing at one side or the other, on which you can talk about things being regular there or not, but it doesn't split anything in 8:31 half in the same sort of way. So it didn't satisfy me. I don't know why, I mean, what was I doing? 8:37 It didn't seem to have any rational reason for looking at this. But it did seem to me there ought to be a way of exploiting this beautiful way in which you do the positive and negative frequency 8:48 without having to look at the Fourier components individually. It's a deeper concept, if you like, 8:54 and it's also conformally invariant. So the scale business that Maxwell theory has, you don't lose 8:59 that. Okay, well, I had this sort of going around in my mind. I didn't know what to do about it. It 9:07 was a very unfortunate occasion because I was in Texas, in Austin, Texas, and I was working with 9:15 various colleagues in Austin, Texas. Engelbert Schucking was running this particular meeting. It was a year-long meeting where people like Roy Kerr, Ray Sachs were there too, and very 9:27 distinguished people working in relativity theory. And there were also people in Dallas, Texas, 9:35 and one of them in particular was somebody I was collaborating on a book. I don't think I was doing 9:40 it at that time, on spinors, and this was Wolfgang Winder. And Ivor Robinson, he was somebody who 9:50 was a very clever fellow, had wonderful ideas. He never wrote anything down. He relied on getting a 9:57 co-author to write the paper. It was all done with words. He had a wonderful way with words. 10:04 The Americans loved him because he spoke in this way that they weren't used to, which the words all 10:10 fitted together in this beautiful way. Yes, he did have a wonderful way with words. There's no doubt about it. Was he the one that didn't write papers? Yes. Well, he was important in another story, 10:21 which is a different story, my story, namely the singularity theorem, because that was walking 10:28 down the street and crossing the road. That's a different story. It was the same person. 10:33 That was Ivor Robinson. Yes. So he obviously was somebody who could take my attention. But what he 10:43 had told me about was he'd found some solutions of Maxwell's equations, which had a very special 10:50 character. They're what are called null. They have points in one direction. You see, usually you have 10:57 these two directions, which are called principal null directions, on the light cone. They're 11:02 light-light directions. And if they coincide, it's what's called null. And these are more like radiation fields. And he found a beautiful family of solutions, which he constructed in the 11:14 following strange way. You take a light ray, one light ray, and you take all the light rays 11:19 which meet it. When I say a light ray, I mean the trajectory of a photon. So in space-time, 11:25 it's the space-time picture of a photon. It's thought of as a particle. So now if you think of 11:31 one light ray, and you look at all the light rays which meet it coming in, then you have a family of light rays. And then he constructs this solution, which is based on those light rays. Now they have 11:42 this awkward singularity, which is the light ray that they meet. Why is that a singularity? Well, they all start coming together, and so they're not... The nature of the solution is different 11:52 when they come together, you see. Okay, but it's of a different sort of singularity than the singularity theorem. It's not a serious singularity. It's a singularity in the maximum. 11:59 I think things become infinite. I see. I don't remember the details of it. Sure. They just become infinite on that solution. Just because the light rays don't make this nice family anymore. They got 12:08 crunched up on the other light ray. But what Ivor Robinson did, he had this clever trick, 12:15 where you just place the light ray into the complex, make it a complex light ray, then you 12:21 can keep the light rays which meet it. There's a family which is still real. So you can see those 12:26 real ones, even though the one they meet is in the complex. And they twist around each other 12:32 in this wonderful configuration. I thought about this before, and I think I knew in detail what 12:39 this configuration was. It corresponds to what's called Clifford parallels. Clifford parallels are 12:47 a beautiful geometrical configuration. If you take a 3-sphere, so that's an ordinary sphere, 12:54 but in 4 dimensions. So it's a 3-dimensional surface in 4 dimensions. So it's a family 13:03 of points which have the same distance from the origin in 4 Euclidean dimensions. I'm not talking 13:08 about space-time now. That 4 Euclidean dimensions. So you have a 3-sphere, and there's this beautiful 13:14 family of circles which fill the whole 3-sphere. No two of them intersect, and they all link each 13:21 other. It's called Clifford parallels, or it has a name which is the topological people like better. 13:31 But it's called the fibration. Right. It's a sphere's worth of circles. It's a very nice 13:39 example of a fiber bundle, and how you have this diagram that people like to draw where 13:45 you have the fiber, which is the circle, and the bundle, the entire bundle is the sphere, 13:51 and the projection down is a 2-sphere. So each circle corresponds to a point on a 2-dimension, 13:57 an ordinary 2-sphere, an ordinary sphere. So the each point corresponds to a circle. 14:03 So it's a beautiful example of a fiber bundle. It's the one most simple and beautiful example 14:09 you can have in a way. I was well aware of it. I just liked the geometry. I thought it was really elegant. And it's the same kind of thing you get with these, except that now you're talking about 14:18 light rays. So if you think of the light rays—not quite the easiest way to say this is—it's now the 14:27 circles correspond to each point of the Clifford 3-sphere corresponds to a light ray, and the whole 14:37 family of them twists around in this complicated way. So I was familiar with this configuration, 14:43 and that this was a sort of way of thinking about a complex light ray. You push it into the complex, 14:49 and you get this real description of it, which somehow feels out this complex light ray, 14:54 but only in this real configuration that you can visualize. So I found this very beautiful. Now, “Most Significant Thought I Had” 15:00 is this any use to me? Well, the occasion that I'm talking about here was a particular occasion 15:08 which was maybe in a sense the most significant thought which I had had, which was that there 15:18 was an event, a very unfortunate event, when Kennedy was assassinated. And this was in 1963, 15:29 and it was in Dallas. And my Dallas colleagues, including Wolfgang Rindler and Ivor Robinson and 15:36 other people there, Schuchart, Pitch Oshvart was there. And they were at a dinner, and Kennedy was 15:46 supposed to go and give a talk at this dinner. And he was awfully late, and they sort of joked, 15:51 well, maybe somebody shot him. Somebody had shot him. And they came, and it was a way of… someone 16:01 said they came. It was just about a week later, I think, when we decided to go to southern Texas, 16:09 to go to a nice place where there was a beach, and people could relax and try and recover from this awful occasion. And do some math? So we went down there. I don't think we taught much 16:19 math. I don't remember. But I remember coming back, and most of the people wanted to talk, 16:25 gossip with each other, including my then-wife. They really wanted to gossip. I wasn't interested 16:31 in the gossip. I just wanted some peace. And I was the one who was committed, more or less, 16:38 committed to be in the car driven by Pitch Oshvart. Now, the thing about Pitch Oshvart, 16:44 he was a Hungarian who did speak English, but he didn't like to speak, even in Hungarian, I think. He didn't like speaking. He was a silent person. Okay, so he was the Hungarian dirac. Yes, 16:56 but he was definitely, he could speak English, but with a strong Hungarian accent, of course. And he 17:03 was the driver of the car when I came. And so this was very nice for me, because I didn't have to make up conversation to speak to him. He preferred not to have conversation. So I think to myself, I 17:14 knew about this Robinson Congruence of rays, which sort of describe a light ray, but which has been 17:20 displaced in this way. And I said, the thing to do is to count, and I thought I didn't say anything, 17:26 to count the number of degrees of freedom this configuration has. How much freedom does it 17:31 have? And I counted them, and it has six degrees of freedom. And that's significant because? Yes, 17:38 this is very significant, because light rays themselves have five degrees of freedom. So 17:44 it's only one. You make your light ray complex in a sense, and you only drop your dimensionality 17:51 by one. It's not really what you do if you're complex around light, where we have five complex dimensions. No, no, this only gives it, drops it by one. Why is that so important to me? Because 18:02 this gives me a picture, the light rays themselves are represented by points on this bound three, 18:10 sorry, this five-dimensional boundary. And the Robinson Congruence, as I call them, these 18:17 twisting congruences of light rays, represent the points. If they go right-handed, they're one side, 18:23 and if they go left-handed, they're the other side. This is the splitting of the space into two halves, just what I was looking for. Only it does it globally for the whole of space-time. Don't 18:33 think of points, think of light rays. And then the complex ones, in this strange contorted sense, 18:40 are only one more dimension. So that was the origin of twistor theory. I went back, got him 18:48 back much earlier than anybody else, because they were still gossiping, I guess. And I went to the, 18:54 I had a blackboard there, and I worked it out in terms of two component spinors. And 19:00 it worked beautifully. And this was twistors. You take two two-component spinors, the way you can 19:07 think of it, see a two-component spinor ordinarily points along the light cone. It has a null vector 19:15 associated with it, and that null vector points along the light cone. In addition, there's a 19:20 little flag plane, and the flag plane tells you its phase. So the length of a, not the length, 19:26 but the sort of extent of the null vector gives you one scale, and the other scale is the phase, 19:36 which is the little flag plane. So you have this nice geometrical way, apart from the sign, which you have to add in addition, you've got the nice way of describing two-component spinors. I was 19:46 well familiar with that. So the thing about the twistors, as you can think of the light ray, where 19:52 does it hit the light cone of the origin? Some point. Then you look at the light ray going up, 19:57 it hits that point. That's a thing I called omega. I didn't call it omega at the time, but it's to do with angular momentum, really. It's the moment of the light ray about the origin, 20:07 and the other is pi. That's the momentum of the photon. So you've got the momentum and the moment, 20:14 and they're two two-component spinors. They give you a four-dimensional entity. This was a twistor. So that was the origin of twistor theory. I tried to talk about it to my colleagues there. 20:25 None of them were interested. Engelbert was. He was the only one that was at all interested 20:30 in what I'd done. So it was a little bit of a- Why weren't they interested? Because it wasn't 20:36 general relativity. I didn't know how to do general relativity with twistors. It took me 20:43 decades to find out how to do general relativity with twistors. Do you think twistors will be an “Twistors Are Inherently Chiral” 20:48 ingredient in a theory of everything? So something that combines the standard model? They should have 20:53 a much broader application. But you see, what you have to do is take another step, 21:00 which I sort of made a couple of years ago. I made it in a slightly different way. Well, 21:05 it was a couple of years ago, but in a slightly different way, about six years ago. I wrote an 21:13 article then, which wasn't published until much later. But the article I wrote more recently 21:18 was in honor of C. N. Yang, the great physicist, one of the people who got a Nobel Prize for weak 21:25 interactions and their chirality. I mean, it's quite curious because of that, too. You see, 21:32 you have the chirality. The twistor has a chirality to it automatically, which is 21:40 the way it's described. If you reflect it, it really goes into something else. It goes into 21:49 a dual twistor. So you have a twistor, which is a four-complex-dimensional space, vector space, if 21:55 you like. The dual of that space is the opposite twist. So you have a twistor and a dual twistor, 22:03 and they twist the opposite way, roughly speaking. But this was all to do with... I was trying to do 22:10 positive and negative helicity. I learned not too long after this that you can describe momentum 22:16 and angular momentum of twistors very nicely. And the null ones, if you're talking about light rays, 22:23 this is just a twistor, basically. It's a twistor and a dual twistor together. 22:28 But the nice thing, you can describe the angular momentum. This is the notation I use later to call 22:36 the moment an angular momentum thing. That's the omega. And the momentum is the other one, which is 22:43 the pi part. And that's just the splitting which gives you these 2 interpretations. They're the 22:50 2 parts. These have 2 2-component splinters. And they give you these 2 parts. It's also conformally invariant. The conformal transformations work beautifully. Conformal invariance. It got more 23:01 mixed up with positive and negative helicity. You see, what you really see is that the twistor, 23:10 the positive and negative... You have the space, which is split into 2 halves. The space, 23:16 incidentally, is a well-known space to geometers. It's a complex projective 3-space. So it's a 23:22 6-real-dimensional space, which is really complex 3-dimensional space. So it's nice to visualize, 23:28 because you just think of it as 3 dimensions. And you say, well, it's really complex too. So you can visualize lots of things in there. And it's really 6 real dimensions. And the 5 dimensions go either 23:41 up or down, depending upon what is it that's positive or negative. Well, you look at... It took 23:47 a lot of time to analyze this. But when you really see its connection with angular momentum and so on, it really is the helicity. So the photon is rotating right-handed, if that's right-handed 23:58 or left-handed. So twistors are inherently chiral. They're inherently chiral. So this was where it 24:04 was. I talked about helicity. That's what it was at that time. Whereas the intention was 24:10 this should be positive-negative frequency. So the whole subject kind of got mired, in my view, with 24:18 this confusion. And it got particularly so when one started to talk about general relativity. And 24:25 there were some ideas which came from Ted Newman, who was a close colleague of mine. And he was 24:31 interested in making spacetime a little complex and looking at angular momentum and things which 24:37 come from your displacement into the complex. It was a very deep insight that he had there. And 24:43 I realized that that was the sort of thing I was doing. And one of his ideas... I won't go into the 24:49 details. I realized you could take this and talk about them in twistor terms. And this described a 24:56 kind of twistor, a twistor which actually referred to a curved spacetime. Okay, wait. When you say 25:03 you talked about them do you mean the complex spacetime in twistor terms? Yes. It is a complex 25:10 spacetime. And, you see, Ted Newman didn't mind about his spacetime not being directly physical. I 25:17 don't know whether he minded it or not. He called it H-space. He had a construction which involved 25:23 making spacetime complex and looking at it in this particular particular way that he did. So why 25:30 was that interesting to you? Because when we've talked off-air if I mention the word supersymmetry Extra Dimensions 25:37 there's a grimace on your face. If I mention string theory because it has extra dimensions and maybe some other flavors there's an even worse grimace. I can tell you where the grimace 25:47 comes from. See, all these things are adding extra dimensions to spacetime. Now what I was doing was 25:53 absolutely crucially tied to the spacetime having three space and one time dimension. If you change 26:00 that you wreck the theory. A theory that works in n dimensions especially mathematicians that's 26:06 a feature that it can work in any dimension. And if you say my theory only works in four dimensions 26:13 some people see that as a weakness. You see that as, no, that's a strength. Absolutely. That is 26:18 absolutely the point. I'm seeing it as a strength because you're not looking at mathematics. Okay, 26:25 mathematicians pick up on twistor theory and they generalize it to higher dimensions and all sorts of things. Good stuff, but it's pure mathematics. I'm interested here in specifically the 26:36 mathematics which applies to the physical world. Now that, whether you can generalize that to 17 26:43 dimensions is of no particular interest to me. And if people do string theory initially when I heard 26:48 about string theory I thought it was a beautiful idea. And then when it went and they said oh no, it only works in, I think 26 dimensions originally I thought, okay, that's not okay, you can work on 26:59 that. I'm not going to work on that. It's not physics anymore. So you mentioned C and Yang, Algebraic and Differential Geometry 27:05 you mentioned fiber bundles and implicitly hopf fibrations. Those are differential geometric ideas 27:11 and the standard model and general relativity are based in differential geometry. Standard model 27:18 is not even differential geometry, it's really flat space time really. Do you see differential 27:23 geometry as what will be the language of physics in the next few decades or do you think it, 27:29 you started off in algebraic geometry. Do you see algebraic as the chopped liver that should be? 27:36 You're talking about my shady history here. Now it is true that when I went to Cambridge. I'm going to ask about Grothendieck soon. Well you can if you like. But it's always like saying yes. You see 27:48 when I was in Cambridge doing algebraic geometry I was trying to solve a problem that my supervisor, 28:00 William Hodge, had suggested. He had given a list of problems and said you can work on any of these 28:07 and I didn't understand any of them. Oh the bottom one I can understand. Yeah I'll try that one. You see I think suspect it was the one that he was least interested in. I'm not sure. I think he 28:17 was quite interested in it but it was not part of the march of algebraic geometry and what the 28:27 my close colleague at that time Michael Atiyah would have been doing. He was the real expert on 28:33 these things. I mean all these things are driven by anecdotes I'm afraid. You see Hodge suggested 28:40 at one time. There were various people in my group and for one reason or another they didn't sort of connect with what I was doing. But he suggested well maybe you're not so keen. Hodge 28:50 is suggesting maybe you're not so keen on the subject. I was expressing some disappointment with it I think. He said okay but maybe you prefer to work on one of the other topics. You might like 29:01 to sit in on one of the other graduate students. So I did. I sat in on this class and I didn't 29:09 understand a single word that went on. It was way above anything I knew at all. And I thought this 29:15 graduate student if they're all like that what am I doing here? What I didn't realize is that 29:21 graduate student was Michael Atiyah. Michael Atiyah was later to become a Fields Medalist, 29:28 become one of the first winner of the there's another prize, mathematics prize. Dirac Medal? 29:37 No no it's a play on Nobel but it's somebody else. Abel Prize. That's right the Abel Prize. He was 29:42 one of the earliest winners of the Abel Prize and he became president of the Royal Society. 29:53 Anyway he was obviously not your average student. It's what I mean the fact that he sort of I mean 30:00 he became very important in my life later on by telling me that things I was trying to do were really cohomology which I had no knowledge about. When I found this way of doing integrals 30:10 for finding yes I was interested in this just what I was trying to say in a way. The solutions that 30:18 Ted Newman had found and I tried to convert them into twistor theory which I realized you could do 30:26 in a way but by making twistor theory curved and you can make it curved provided you don't have 30:34 any what I've related called alpha planes. I mean when you don't have beta you have alpha planes. 30:40 I've got said it the wrong way but as long as you have alpha planes. Alpha planes are things which can only exist if half of the conformal curvature vanishes. When I say half it's a bit difficult 30:53 to do that in space time because the signature is wrong. You can do it for the kinds of space 31:01 geometries for geometries that mathematicians like because the signature is right for them. You have 31:07 got all pluses. You take your metric it's all got pluses and they like that and that gives you a 31:13 nice theory and you can make that what's called anti-self dual. If the vial curvature that's the 31:20 conformal curvature it splits into two parts make one part zero and the other part still exists and 31:26 you get these curved solutions. If you try to do that with space times and if they were real space 31:33 times you can't well you can but it doesn't get you very far because the vial curvature 31:39 the two parts one is the complex conjugate of the other. So if one of them is zero the other 31:45 one is zero. So it's not it's conformally flat. It's not interesting as a conformal 31:51 manifold. However Ted Newman didn't worry about these things that was my Pittsburgh colleague 31:58 who I did a lot of work with. He was a very inspirational and inspiring character and he 32:08 had this idea of sort of complexifying space in a way which was sort of half doing it and 32:14 in that half doing it way you could see that you could do what I was trying to do and this led to 32:20 what I would refer to later as the non-linear graviton. It's a complex space time for which 32:27 this vial curvature part does vanish and so you can do twistor theory in it. In this complex 32:33 space time you say what's it good for in physics? Ah well what's complex naturally in physics? Wave 32:40 functions. So if you're doing complex stuff you could be doing quantum theory. So this could be a 32:46 wave function of a crazy sort. So it's what I used to call a non-linear graviton. So it's the wave 32:53 function of a graviton but it's not the ordinary linear wave function. You see normal quantum 32:59 mechanics is linear. You can add one wave function to another and the whole point about, well not the 33:04 whole point, but the big point about quantum mechanics is that you have this superposition principle. You can add states together. The wave functions is a linear thing. You can add them. 33:17 Now this thing was a non-linear thing. You can't add one solution to another. It's just a solution. 33:22 It's a complex solution of the vacuum Einstein equations which has this twist to it and the 33:28 vial curvature vanishes and you have twistors. The kind of twistors you have are a new kind which are 33:35 curved. So you can have these curved twistors. It makes sense. However it's a bit stuck if you want 33:45 to have your physics out of it because it's to do with this conflict or confusion I would say 33:53 in twistor theory. It's inbuilt into the whole subject. You see positive and negative frequency is what I was striving for and I sort of haven't got to that because I got a little confused in my 34:04 discussion here. But you see it does turn out to do positive and negative frequency. It took a long 34:10 time for me to see that. I was driven to positive and negative helicity. They could see that almost 34:16 directly. The photons twist one way or the other way and that's what classical twistor theory does 34:21 for you. But then if you start to do integrals and things like that you can see it's a little bit more confused and then you can see these integral things you're doing are really wave functions. And 34:30 if they're wave functions, then they can have positive and negative separately, frequency, 34:36 the right-handed. They can be right-handed or left-handed depending on whether it's twistors or 34:42 dual twistors and they can be positive frequency as well. But you've got to talk to them about 34:48 complex solutions. So it's this confusion between the two which in a sense limited twistor theory 34:55 to the situations in which you have alpha planes. Now I haven't said what an alpha plane is but the 35:03 vanishing of this half of the valve curvature is the integrability condition for the existence of 35:09 alpha planes. If you have the alpha planes, they are the twistors. So if a plane has alpha planes, 35:16 each alpha plane is associated with a twistor and that's the geometrical description. But 35:21 real space-time doesn't have any alpha planes in it. It's only much more recently I consider what 35:28 you do. You consider what I call bi-twistors. Now bi-twistors I described in the paper which was in 35:36 honor of C.N. Yang. I'm very much delayed with this paper because I was trying to work things 35:41 out. And it came out, well it's in honor of C.N. Yang's 100th birthday I should say. He's still 35:49 alive as far as I'm aware. This was two years ago or something, so it came out. So I wrote this paper which was about bi-twistors and about the connection with split octonions. See I mentioned 36:02 right at the beginning the Hamiltonian quaternions and you have the analog of that when you go up, 36:09 these are things called octonions. It didn't take long after Hamiltonian produced its quaternions 36:15 when various, several people independently discovered this generalization to these eight 36:20 dimensional things which are called octonions. I was aware of the octonions and I was aware that 36:25 there were split ones as well where you have four plus signs and four minus signs. And I thought maybe there's something to do with twistor theory there. I didn't know what it was. That was 36:35 just a hunch at that point? Well this was what this paper was really the result because I could see how to do it. You can actually describe the split octonions. You have to have a product now, 36:46 going back to what I said at the beginning, quaternions you take two, product of two gives you a third. Now it's a product of three things give you a fourth. You make one, you choose another 36:57 element, make it the unit element and then this other two gives you the split octonian product. 37:02 So it does give you the split octonions. I only vaguely thought maybe there's some connection at 37:09 one time and later I see it really does. It gives you the split octonions. But for that you really 37:15 need these things called bitwistors. You've got to combine a twistor and a dual twistor otherwise 37:21 these things don't even exist. There's got to be that combination and you have a bigger space. 37:28 But what's nice about it from the physics point of view is you sort of got rid of this inherent 37:33 twist into the theory. They're not really twistors in the sense that the twist goes 37:39 one way rather than the other. So it removes this awkward confusion between helicity and frequency. 37:49 You see positive frequency and positive helicity are two different concepts. But 37:54 in twistor theory they're confused as being the same. So I want to ask about definitions because Alexander Grothendieck 38:00 when you're an undergrad people tend to think that you focus on proofs and that's what it is to be a researcher. And Grothendieck said that what's more important are definitions. So he 38:11 would say you keep your definitions convoluted and you make your proofs simple. What makes a 38:16 good definition in physics though? Well going back to Grothendieck you see there was this, when I was talking about my period in Cambridge I was really an outsider working on this particular 38:27 problem that Hodge had suggested. Although it was a bit like twistor theory in a way. You see if you want to describe a curve and a twisted cubic is a good example. It's a twisted cubic, you don't 38:36 have one equation for it. You can think of it as an intersection of two quadrics where you throw away a line. The normal intersection is a quartic surface. You specialize it so it's a line and a 38:48 cubic. And that cubic is called a twisted cubic. It's not the intersection of two hypersurfaces. 38:53 But can you write down an equation for it? Yes you can. You think of your space of straight lines and 39:01 those straight lines which meet the curve is one condition and that gives you a formula. And this is the Cayley form thing. And that's what I was actually working on. Not that, but how do you do 39:11 that in higher dimensions? How do you work out how things intersect and stuff like that? And it 39:17 got rather too messy. So I had to develop a diagrammatic notation for handling all the 39:22 complications. That's another story too. I won't tell you that one now. But anyway. Grothendieck. 39:31 Grothendieck was the big high priest of all. I think initially it was sort of crept up before you 39:37 got to Grothendieck. He was the real high priest. And that's what people like Atiyah were doing and 39:44 making it more and more abstract as he went on. I was going on a completely different route. I was thinking about, okay. Something concrete? Well it was much more concrete, yes. I mean, I could think 39:54 of light rays meeting curves. No, not light rays. I mean, straight lines meeting curves. That was my 40:02 problem was of that character. But you do that in higher dimensions. Yeah, there's a phrase, abstract nonsense. Have you heard of that? About category theory? Oh sure, that's right. That's 40:12 the whole. That's your feeling as well? The whole move of, you see that. Yeah, that's what they were all doing. To this day? That's what, Michael Atiyah was a great expert in that subject. Oh 40:21 yeah. And Grotendieck was a greater expert. Well he, what was the, there was a sort of 40:28 sub. I mean, Grotendieck was the, well he went off and sort of worked in isolation and disappeared 40:34 from the. Sure. What do you see as the tension between gravity and quantum mechanics? So you Gravity and Quantum Mechanics 40:42 mentioned linear. Yes. Some people think one is non-linear and the other's linear and that's where the tension is. Some people say it's non-commuting variables on one side and then 40:50 commuting variables on the other. There is a big tension. Observable, sorry. But there's a worse tension. You see, there's a tension in the sense that general relativity is not really linear, 41:02 it's non-linear. You see, and people in quantum mechanics, they like linear things. They don't care how many dimensions is there. It could be a million dimensions. It could be an infinite 41:10 number of dimensions. Lots of things are. They love infinite dimensions. That's fine in quantum 41:15 theory. But space-time has got three plus one. From that point of view, it's pretty boring. 41:22 It's only got a finite number of dimensions. But the space-time has, and Einstein of course, 41:30 he was good. He got his Nobel Prize for quantum mechanics, of course. But the photoelectric effect 41:36 was just nothing to do with GR. Some physicists even like to say Einstein was wrong. They like 41:47 to write that on a t-shirt. Well, they were all saying that then. You see, that was nothing new in those days. Of course, it was the Eddington Expedition, which suddenly startled everybody 41:59 to show the bending of light was in agreement with Einstein's theory. And that did change 42:04 things. It made Einstein a big celebrity too. So it was a big thing. But it didn't really make the 42:13 quantum field theory or quantum people didn't like curved spaces because they're all flat spaces. 42:19 They may have infinite dimensions, but they're flat as a pancake. They don't fit in very well 42:27 with the basis of general relativity. And then perhaps you want me to go in that other way, 42:34 because there's another way they don't fit in together, which is another thing. It's not so much twistor theory as it stands, but it's an important thing. Consciousness? Collapse? Collapse. Yes, 42:47 there's consciousness, but that's... Oh dear. There are too many stories here. We're going to 42:52 talk about consciousness as well. Let's stick with the collapse for now. No, the collapse is important. We have to do that first anyway. You see, I always thought that I didn't like the Collapse of the Wave Function 43:03 collapse of the wave functions being... I mean, quantum theory was terribly confused. You see, 43:09 you've got the beautiful... Well, think of the Schrodinger equation. The Schrodinger... I mean, 43:15 Schrodinger was just confused. I mean, he understood why he was confused. I mean, he was absolutely on the ball, but lots of people were confused. Anyway, let me not go into that 43:25 story. You see, take a quantum system. How do you describe it? You take the wave function or vector 43:33 in Hilbert space or something, isn't it a wave function? You take the wave function. How does that evolve in time? Schrodinger equation. So, it evolves in time, according to the Schrodinger 43:41 equation. Is that the way the world evolves in time? No, it doesn't, because you cheat. You say, 43:48 no, no, you've got to a certain point and you make a measurement. What does making a 43:53 measurement mean? I don't know. People have funny ideas about making a measurement. The trouble is the word observation, I think, crept in there a little too... To sneakily, too early? Sneakily, 44:03 too strongly, I would say. Because people think, as many, one of the big proponents of this view 44:13 was Wigner, Eugene Wigner. And I actually, when I was in Princeton, I did talk to Wigner about it. 44:19 I had a long lunch talk with him, and I talked about this issue of does the wave consciousness, 44:26 if you like, collapse the wave function? Because that was the Wigner view. He was not so dogmatic 44:33 about that view as I was expecting. He was saying, it's a view, but a point of view. I don't think, 44:39 for many reasons, it really makes sense. But it was nevertheless, I think a lot of people, 44:45 even von Neumann seemed to have that sort of idea, too. A lot of people had the idea that it was a conscious being observing the system which somehow changes the rules. You change your wave 44:57 function and write it down in terms of its certain basis, and then you give the amplitudes, 45:06 and then you look at these complex amplitudes, square them, square the modulus, and that makes 45:11 your probabilities. So then what would they say, not to take you off track, but what would they say is what observes the observer? I don't say any of that, you see. I don't care what 45:21 they say. I don't know what they say, because it's not what I say. And I think it's wrong. 45:27 So although I think consciousness relates to it, the question, it's in a completely different way. It's not what collapses the wave function. What collapses the wave function is physics. So 45:40 there is something in physics which collapses the wave function. The Schrodinger equation, quantum 45:45 theory as a whole, is wrong. It's not Einstein was wrong. Quantum mechanics is wrong. Now I 45:52 say this very blatantly because it's a blatant topic. I mean, Einstein and Schrodinger were 45:57 much more polite. They said it was incomplete. Okay. Incomplete means wrong. But you're telling 46:05 it like it is. Yeah, you've got to change it so it's wrong. But incomplete is a more polite 46:12 way of saying it's wrong. Okay, they're fine. I should be polite sometimes to quantum mechanics, 46:17 although it's pretty robust as it is. It doesn't mind people like me being rude to it. But anyway, 46:23 so Einstein and Schrodinger both thought that it was wrong, that the theory needed some amendment, 46:33 could be an important amendment, which changes the nature of the whole subject, quite likely. As you know, on Theories of Everything, we delve into some of the most reality-spiraling concepts 46:43 from theoretical physics and consciousness to AI and emerging technologies. To stay informed in an 46:50 ever-evolving landscape, I see The Economist as a wellspring of insightful analysis and in-depth 46:57 reporting on the exact topics explored here, and even more. The Economist's commitment to rigorous 47:03 journalism means you get a clear picture of the world's most significant developments. Whether 47:08 it's the latest in scientific innovation or the shifting tectonic plates of global politics, The Economist provides comprehensive coverage that goes beyond the headlines. What sets The 47:19 Economist apart is their ability to make complex issues accessible and engaging, much like we strive to do in this podcast. If you're passionate about expanding your 47:28 knowledge and gaining a deeper understanding of the forces that shape our world, then I highly recommend subscribing to The Economist. It's an investment into intellectual growth, one that 47:38 you won't regret. As a listener of TOE, you get a special 20% off discount. Now you can enjoy The 47:45 Economist and all it has to offer for less. Head over to their website www.economist.com slash TOE 47:53 to get started. Thanks for tuning in, and now, back to our explorations of the mysteries of 47:59 the universe. So you think both Einstein's, both general relativity and quantum mechanics need to 48:09 be modified, or primarily quantum mechanics and a tinge to general relativity? I would say more 48:15 importantly quantum mechanics. You see, people sometimes say to combine these two great theories, 48:22 you've got to quantize general relativity. Can you explain what does it mean to quantize? You 48:28 mean to haul it into the framework of quantum theory. So you have, you make it into a Hilbert space and operators and goodness knows what. And you sum over metrics, or sum over 48:38 geometries? Yeah, well lots of people were trying to, Wheeler was trying to do that when I was in Princeton. Yeah, lots of people were trying to do that. Bryce DeWitt was certainly trying to do 48:49 that. And so when you speak to string theorists, they would say, well that's quite obviously the approach. We're the only finite quantum gravity game in town. Yes. I mean, there's nothing wrong 48:59 with quantizing gravity. It's just the weak, I don't know what I'm saying. I don't read the 49:06 right adjective. But let me... You don't have to be polite anymore. No, no, I'm not trying to be 49:12 polite here. I'm trying to be more illustrative of what I mean. I mean, I sometimes talk about a 49:20 planet, a distant planet, which has an atmosphere on it. It's a planet very much like the Earth, 49:26 almost identical. And there's a space probe going out to look at it, because it's very interesting, 49:33 because it's just like the Earth. However, there is no life on it. No life has ever evolved on it. 49:39 There are no butterflies to flap their wings, and weather is supposed to be a chaotic thing, and so 49:45 even sensitive to the flapping of a butterfly's wing. There aren't any butterflies on this planet. 49:51 There are no conscious beings on that planet. So all the different weathers that they might have 49:56 on that planet all coexist in superposition. It's a mess. The probe is going out to take a 50:04 photograph of this mess. It comes back to the Earth, and when it's within distance of being 50:10 able to send signals to the Earth, somebody's sitting against the screen, and finally the 50:15 first picture of the weather on that planet, this person looks at it—snap! His consciousness or her 50:23 consciousness makes that world into weather into one weather. What could be more absurd? Absolutely 50:31 ridiculous. It's lightweight, it doesn't have any interest in us. Why does its weather become one? 50:38 Just because this chap isn't taking a photograph of it. Absolute nonsense. I'm just trying to 50:43 emphasize that I don't believe it is consciousness that collapses the wave function. Instead, it's 50:49 the collapse of the wave function that produces consciousness? Well, that's my other story, which I think is another story, and is a story which I also try to pursue to some degree. I don't 51:01 regard it as what I do most in my life, because it's too much biology and things like that, which I don't know anything about. Are you wedded to microtubules being the mechanism or the place? 51:12 Or are you just saying, look, if it's going to occur, it needs to occur somewhere in the brain. This chap named Stuart Hameroff put up his hand and said, it could be microtubules. I found 51:21 this in the brain. And then you said, okay, well, maybe. That's more or less it, yeah. 51:27 Yes, it wasn't quite like that. But I do think microtubules are a good candidate for various reasons. But you wouldn't be heartbroken if it turned out to be some other structure? Heartbroken 51:35 is too strong. I'd be a bit disappointed, yes. Because I think microtubules... No, there are various features of microtubules that I find fascinating. I don't think it's 51:45 a coincidence. Did you see the recent news about the super radiance in microtubules? I did hear something. I didn't see it. It said that there are quantum effects that are 51:57 coherent in microtubules. No, there better be, yes. Do you feel vindicated from that? 52:04 The trouble is, I did look at the paper which was referred... I think it's, if it's the same one you're talking about. I did look at the paper. Stuart is mentioned. There is a reference to his, 52:14 but it doesn't really talk about his stuff. It looks like something else. I don't know. 52:20 I might be connected. Look, I'm not a biologist. So I'm not even a chemist. I find chemists is too 52:26 difficult for me. Chemistry is, it's full of words that I can't remember. Yeah, same. I was supposed to be a doctor. My parents were both doctors. They thought I should be a doctor. They 52:35 were both medically trained. I was the one they thought would be the doctor. They won in the end because my little sister eventually got a doctor and she married one too. So they got two for the 52:44 price of one. No, I disappointed them terribly. I would have been hopeless because I don't remember 52:50 names of these things. You can tell, I forget them immediately. I would have been putting the wrong 52:55 prescription on people's... Well, you invented quite a few. Biotwistors, dual twistors, alpha planes, beta planes. Well, yes. I remember most of those more easily, yes. So I'm jumping ahead Gravitational Fields and the Wave Function 53:06 because the audience is familiar with that gravity has something to do with the collapse of the wave function. Yes, but let me make that a little more specific. You see, I wasn't so clear on that until 53:16 much more later. I think just a little before the turn of the century. I can't quite remember then. 53:23 It took me a little while before I actually wrote the paper on it. I wrote a paper on it which was to explain a conflict between the two basic principles, one of general relativity, 53:37 the other of quantum mechanics. What's the basic principle of general relativity? It's the 53:43 principle of equivalence, which Einstein admitted. He didn't give Galileo credit. I think he should 53:50 have given a reference to Galileo. I'm not sure he did. Because Galileo already noticed the principle 53:57 of equivalence. And he talked about... I like the one of the fireworks. He describes his fireworks. 54:03 Go out and they make this beautiful sphere of sparks. As it falls, it remains a sphere. You can 54:10 get rid of gravity by free fall locally. He's very explicit. Not just the big rocks and the little 54:18 rocks and why the feather doesn't because of air resistance and all that. I mean, he was right. But 54:26 of course, you needed special relativity and make that into a four-dimensional space-time 54:34 as Minkowski did, and then bend it as Einstein did. So the collapse and gravity come in? But 54:42 my argument is that the principle of equivalence, which is the basis of general relativity, is in 54:49 conflict with the principle of superposition. And the argument... is more or less this. I say, think 54:59 of an experiment done in a lab on a tabletop. And you want to take the Earth's gravitational 55:06 field into consideration. Now, there are two ways you might do this. The way any sensible physicist 55:12 would do it, you put a term in the Hamiltonian. If you don't know what that means, don't worry. Put 55:17 a term in the Hamiltonian for the gravitational field. And just chug away the usual procedures. 55:23 Fine. Then you notice that Einstein's sitting in the corner, or Galileo even, and say, no, no, no, 55:30 you shouldn't do it that way. The gravitational field of the Earth is locally just like free fall. 55:36 So you can consider your lab, your coordinates are falling, and the lab is just accelerating in this 55:44 thing. And there's no gravitational field. Okay, you do it this other way. It's a different way. 55:49 Different coordinates, you do it a way. And you come up, eventually, you come up with almost the 55:55 same answer. The key, of course, is in the almost. The wave function you get is just the same, 56:04 except for the complex multiplier. The phase factor, if you like, which people would quite 56:12 like to discard, because when they're going to measure anything that you observe, they're taking amplitudes, you take squares and moduli. So you don't worry too much about that. Until you look 56:21 rather too carefully at this actual factor, which is different between these two procedures, that 56:28 actual factor involves the time, an exponential of the time cubed. And that is not, that's serious, 56:39 if you really think of it. If you're thinking of quantum field theory, that's serious, because that's telling you that's a different vacuum. You're actually working in a different vacuum. 56:50 So you might say, well, you still might say who cares, because you say stick to your vacuum, and 56:57 you get the right answer at the end. Okay, so I'm going to change the problem a little bit, rather 57:04 seriously, actually. I'm going to say that in this experiment, there is a lump of some sort, which 57:13 is put into a superposition of two locations. So it's a little stone, which goes into two places, 57:19 a little bead or something, which is part of the experiment. Now, I try to use the Einsteinian, 57:26 Galilean Einsteinian perspective, and I ran into trouble, because as I get close to the bead, 57:32 I see that whether it's here or here, I can't get rid of them both at once. And that's, of course, 57:38 the Einstein problem, which is a general relativity. I can't get rid of them both at once, 57:43 by free fall. So what do I do? I do what any sensible physicist would do, I cheat. I say, okay, 57:51 I know I should be using the Einstein perspective, but let's just try instead, measure the mistake 57:58 that I'm making by adopting that, by the Newtonian perspective. So I adopt the Newtonian perspective, 58:05 but keep track of what might be a little error in doing it. Then I integrate that error over space, 58:13 and I do a little integration by parts and some little bit of fiddling around with it. And I get 58:19 with an answer, which looks like a uncertainty in the mass of a system. It is the mass of 58:28 the system, but it's not the fact that it's a superposition that gives me an uncertainty of that 58:36 mass. Now the thing is, that's a bit like particle physics, where if you have a decaying particle, 58:46 its mass is not completely well-defined. It has an error, a fuzziness in its mass, which is given by 58:53 the Heisenberg time-energy uncertainty principle. So its lifetime, if it's an unstable particle, is 59:00 inversely related to this sort of fuzziness in its mass. Now here I have a fuzziness in the energy of 59:11 the system, the mass energy of the system, so I say that's the reciprocal of that in natural 59:17 units. When I say natural units, I mean making all the things equal to one that you can do, 59:24 as Dirac sort of pointed out, I guess. And I get the formula, which Diosi had already discovered 59:32 a couple of years earlier than me. Right, for different reasons. I didn't know he'd done that. It was a different argument. But I thought this was a nice argument because it just revealed the 59:42 tension between these two very basic principles, the principle of equivalence and the principle of 59:48 superposition. And they're a bit in conflict with each other. And the resolution of this 59:54 conflict comes through allowing your unstable state to collapse into one or the other. Now, 1:00:03 what you only get from this way of looking at it is an uncertainty in the mass. And I 1:00:09 know that Ivette's looking directly at this thing rather than looking at the collapse, which is a powerful thing to exploit. And just for people who are wondering about Ivette Fuentes, 1:00:20 there's a podcast on screen right now where we go into two hours in depth into this topic. Now, 1:00:26 do you have a mechanism for why or how gravity collapses the wave function? Or do you just say 1:00:32 it has to collapse? I said that's where the new theory has to come in. I'm just saying, 1:00:37 look, I have a problem. I need a theory. No, all I can say is that it tells me how big the factor 1:00:45 should be. It tells you, you can measure this uncertainty. And it's not so hard. You just think of the bead that I was looking at. Imagine the two copies of the same bead. And I move it into this 1:00:57 superposition. And I ask, how much energy would that cost me where I ignore all forces except 1:01:04 gravity? Very tiny usually, but it's nevertheless. It's enough to collapse the state for any, even a 1:01:14 flick of dust will collapse in a very short period of time. So it gives you that much. I mean, it's 1:01:19 the same as Diosi. It's the same formula. It's not a theory in the sense that his was. I mean, 1:01:25 I think his ideas got, as far as I'm aware, rather shot down by the Gran Sasso experiments, 1:01:33 was it? They took this thing down a mineshaft or something. No, it's to do with the heating. They 1:01:39 anticipate bodies spontaneously heat, which I don't want. That shouldn't happen. But that's 1:01:45 because the collapse has a very curious... You see, if you want to make it consistent with special relativity, don't worry about general relativity at the moment, you're really already 1:01:54 in trouble because you imagine a body going, splitting. It's the superposition. It's not 1:01:59 two bodies. It's one body, superposition of here and here. They get very far away from each other. 1:02:04 They haven't collapsed yet. And now they're going to collapse. One goes. In whose frame does that 1:02:11 happen? Is that the frame you should be talking about? How do you make that consistent? Well, 1:02:18 what you've got to do... I mean, I worried about that. Lots of people seem not to worry about that. 1:02:23 I worried about that. You say, okay, the only thing you can do, which is relativistic... I mean, 1:02:29 there are other wrong routes you can take, which I won't go into because it's quite a bit of a more story than I'm making out here. The only route you can take is to say the collapse actually 1:02:39 took place right back to where the split initially took, and then there was only one route. But what 1:02:46 about the other route? Well, what I have to do is to describe things in terms of two different kinds 1:02:54 of reality. One of them is quantum reality, and one of them is classical reality. So one doesn't 1:03:01 give rise to the other? They're actually separate? Well, it's the quantum reality, if you like, which does give rise to the way that the classical reality behaves, but it does it in 1:03:10 a kind of retrocausal way. So that's what's so confusing. In a kind of retrocausal way? Or is 1:03:16 it retrocausal? It's kind of retrocausal. Okay, explain. I'm saying this deliberately because it's 1:03:23 only quantum reality. You see, this is a puzzle I had, and you can resolve this in a rather peculiar 1:03:32 way. You might say, oh sure, if it was retrocausal and it went back to the beginning, then how do 1:03:40 you... what am I trying to say? You can travel faster than light. Yeah, you can travel faster than light or backwards in time or something. Sure. So I've got to tackle that problem. Or you 1:03:50 can signal backwards in time, that's the thing. And you were trying to retain special relativity 1:03:56 before? I'm just saying you can't do that. Think of Alice and Bob. I had this in some notes which 1:04:04 I circulated, but I don't think it was actually published. It's sort of pseudo-published. You see, 1:04:10 I have a book. The book I wrote, which was with the Princeton University Press, called Fashion, 1:04:19 Faith, and Fantasy in the New Physics of the Universe. The fashion was about string theory, 1:04:26 which I'm not sure was still so fashionable now, but it was then. Faith was quantum mechanics 1:04:31 at all levels. And fantasy actually had to do with cosmology. It was to do with inflationary 1:04:38 cosmology, because I simply thought inflation is much too fantastic. That's another story. 1:04:44 But the fashion... so I had to write this new preface. I think it's almost out now, 1:04:51 a new printing of Fashion, Faith. I wasn't allowed to change anything in the book, but I was allowed to write a new preface. And I do give an outline of this idea. I think I 1:05:01 do. The retrocausal thing. You see, the thing is, think about the standard EPR. So you have a spin 1:05:09 zero state, splits into two halves, spin half, and Alice takes one off in the spaceship and Bob takes 1:05:18 it up on another half. Alice makes a measurement. What do I say happens to the quantum reality? It's 1:05:26 a quantum measurement. Quantum reality propagates along the past light cone. What could be crazier 1:05:33 than that? The backwards way, along the past light cone. It hits Bob's world line way earlier than he 1:05:41 does his experiment. So his state is already changed into the one which is the opposite of 1:05:48 Alice's state. Bob makes his measurement later. He doesn't know what the state is. 1:05:56 Alice can only communicate classically with him. This is a quantum information. Now, 1:06:04 quantum reality information. Quantum reality, you cannot measure, you can only ascertain. 1:06:11 Explain the difference between ascertaining and confirming. Because when you were on stage with Sabine Hossenfelder, you said you can confirm, I think it was the classical level, you can confirm, 1:06:22 whereas at the quantum you can ascertain. Like you can ask a question. That's right. Well, you see, it's really Einstein. It's Einstein's fault. Because he was saying, I think a lot of 1:06:36 people were worrying about the reality of the wave function. Is it real? Is it really there? 1:06:43 Not real, it's complex, you see. It's not real in the sense of real numbers, but is it really there? 1:06:50 And Einstein produced the statement. He said, well, a concept of reality isn't introducing, 1:06:56 which is if you can make, if there's a measurement you can make on the system without disturbing it, 1:07:02 and which with 100% certainty gives the answer yes, then that measurement is revealing an element 1:07:09 of reality. So he says that the state, the quantum state is real in that sense. What he didn't say, 1:07:17 as far as I'm aware, is that is quantum reality. It's not classical reality. Think 1:07:23 of the spin of a spin-half particle. I always like spin-half particles. Sure. Spin up and spin down, 1:07:31 if you like, or spin right and spin left. Suppose its spin is about that way. If I know through its 1:07:39 origin, where did that spin come from? Oh, yes, I know. Oh, it should be spinning that way. Wait, sorry. Is this a hidden variable that it's carrying with it? No, no. It's not hidden 1:07:46 variables. Forget about Bohm. Forget about Bohm. You're not a fan of Bohm. I had arguments with 1:07:54 Basil Hiley on that topic, and I prefer not to go back there, when I was at Birkbeck College. 1:07:59 All right. Let's not talk about hidden variables. If you can call them hidden variables, you can, 1:08:05 but that's not my idea. It's not that. Got it. It's quantum reality. So the state is that, but 1:08:12 it has a quantum reality of spinning right-handed about that particular direction. And we know it 1:08:18 is because we've set up and we've produced it in that state. You could do that by some experiment, 1:08:25 and it comes out in that state. Now, I'm going to use Einstein's criterion. I can measure the 1:08:31 spin in that direction, as long as it's got a magnetic dipole or something. I can measure it, 1:08:39 and I can... If I've got it right, every time I measure it, or I can measure the same experiment 1:08:46 many times over, 100% certainly, that's real. That's what Einstein said is his element of 1:08:53 reality. I'm just slightly modifying what he said. It's an element of quantum reality. It's 1:09:01 not classical reality. I can't say to the state, hello, state, which way are you pointing? Just 1:09:08 looks at you blankly. It says, I don't answer questions like that. Give me a better question, 1:09:13 you see. If I say, are you spinning that way? It can say, no, or yes. If you say, 1:09:19 which way are you spinning? It doesn't answer that question. That's a quantum reality thing. Quantum 1:09:25 reality doesn't. You can't ascertain it. That's why I say you can't ascertain. You can't ascertain 1:09:34 which way it's spinning. However, you can confirm which way it's spinning by the Einstein criteria. 1:09:40 I see. Now, if Alice and Bob, you see, if Alice propagates back in time, Bob's state is already, 1:09:48 in a certain sense, the opposite of what Alice is going to measure, but Bob can't ask the state, 1:09:57 which way are you spinning? If he could, then you could send signals faster than that. The 1:10:02 whole of special relativity goes down the tubes. The whole of modern physics does. So that's not 1:10:08 a good idea. So quantum reality, sure. Bob can't say, hey, can I ask it? His spinning state says, 1:10:17 don't ask me such a question. I don't answer questions like that. Suggests a direction. So he does. He suggests a different direction. He has no idea what Alice has spinned. I did 1:10:27 worry about this quite a lot by saying, can he ascertain which way Alice is measuring it, 1:10:33 and even if you don't know which answer she gets? So there's a bit of a subtlety there, because she 1:10:38 might orient her apparatus in some way, and does that information somehow, you want to make sure 1:10:45 that can't be ascertained by Bob either. Uh-huh, that she's free to choose independently? She's free to choose. She says, yeah, but she might say, oh, I think I'm gonna choose that direction 1:10:55 because Bob's keen on that direction or something, and that will tell me I'm happy. No, she can't do 1:11:01 that. Have you thought about free will? I've thought about it. In fact, I thought about it Free Will 1:11:08 even quite recently. First of all, I think it's a useless kind of thought because even though, 1:11:14 you see, Stuart is very keen on free will because he says that this theory of microtubules and all 1:11:21 that stuff gives a room for free will. See, maybe it does in a way, but you see, often people say, 1:11:29 well, it's all determined anyway, and so I think people get a little bit confused. You see, 1:11:37 going back to my experiences I used to have when I was very young, and my younger brother was even 1:11:43 younger, and he could always wallop me at this game, scissors, paper, stone, and I thought, how 1:11:48 can he be walloping at that game of chance? Right. So to make sure it was a game of chance that he 1:11:53 couldn't wallop me at, I went into my father's study and I got out a book of logarithms and went into the middle of it and got out the string of numbers and produced which way you went by the 1:12:02 string of numbers, followed it very carefully, and he couldn't beat me. So I thought, thank goodness. 1:12:09 He's not reading my mind. It's just that he knows, that's recognizing patterns and things like that. 1:12:15 He's good at that. Maybe even unconsciously, he recognized these patterns and he knows which way 1:12:20 I'm going to do next because I'm not really being random. So it's not randomness. Yes. The free will is not randomness. So what is it? You see, maybe I thought, I think it's probably, 1:12:36 you're free to do something which may be very well determined. You see, you might, do I take course A 1:12:44 or course B? You may be in some meeting, you see, which is making decisions about some big plan. And 1:12:50 you want to know, what is the consequence of doing A or B? Well, then you rely on your understanding 1:13:00 of which is the right thing to do. So free will, it might be the same as somebody would do just by 1:13:05 chance. That's not the point. The point is that you've used your consciousness as something to 1:13:13 employ in making your decision. So that's what free will is for in a sense. I don't know if I 1:13:22 can say much more. And I also get impressed by things when I hear things about bees and 1:13:27 they're unbelievable. Yeah. And they seem to play. They're unbee-lievable. Unbee-lievable. Yes, well, 1:13:34 they sort of, even they play football. There's some, see, they were telling me about little, 1:13:41 they're not trying to hunt for honey. They do things in little balls and they kick them 1:13:46 around. There's some kind of football that they play. Why are they doing that? For fun? That 1:13:53 would mean they have to be conscious, doesn't it? Maybe they are. I don't know. I don't have a view on this. I do believe that consciousness goes way down in the animal kingdom, sure. Is the universe Is the Universe Discrete or Continuous? 1:14:04 discreet or continuous? I used to be very keen on discreet. I did, yes. People tell me, oh, 1:14:10 I got to go into anecdotes. I'm too old. I just talk about anecdotes in the physics. Okay. If you want an anecdote, I can give you an anecdote. I used to be very keen on discreteness. There were 1:14:20 two things in mathematics that I thought, oh, these are the nice things for physics, ultimately, to be based on. Combinatorial things or maybe complex numbers. I think I sort of, 1:14:31 at that time, thought combinatorial things. I'm surprised. If you came from algebraic geometry, 1:14:36 that you would be more keen to the finite side, the discreet side. I probably was at that time. 1:14:43 You see, I had this sort of gradual conversion. I think the conversion came with David Finkelstein. 1:14:50 When, as he said after his talk, he gave this talk that Dennis Sharma took me to when I was 1:14:55 a research fellow at St. John's in Cambridge, and we drove to London to hear this lecture given by 1:15:02 David Finkelstein, which was on the Schwarzschild horizon, which is not a singular, it's a horizon. 1:15:09 Sure. And he described that. And I found that amazing. I thought it was very beautiful. At the end of the talk, I had a long chat with him about spin networks. So I described the spin networks to 1:15:19 him. And he told me afterwards that this meeting, we swapped subjects. I did gen relativity from 1:15:26 then on, and he had been doing GR. He swapped on to combinatorics. I consider I got much the better 1:15:31 deal. But that's, you see, I was thinking about combinatorial things. Spin networks are very much 1:15:38 that kind of thing. Can you not think about the complex numbers which give you the directions of spin for a spin-half particle, or do you instead think about this network, which is really the 1:15:48 important thing, and the direction comes out of the network? I was playing with that idea. 1:15:56 You said you've changed your tune now to be on the more continuous side, or continuum side. Well, 1:16:01 the power of complex analysis was the other thing which has impressed me. And it's more drifted onto that side. Do you think the continuous lies at the classical level, and then 1:16:11 the discreteness lies at the quantum one? Do you think that's the way to quote-unquote unify them, 1:16:17 or harmonize them? I wouldn't say anything like that. I mean, maybe. Obviously, there's something 1:16:27 discreet in quantum mechanics. I mean, something which people used to think was continuous, shock, 1:16:33 shock, is actually discreet. Now, speaking of what people used to think, you used to think Ai’s Capabilities 1:16:39 that AI couldn't do what mathematicians do. Do you still hold that view because of their limitations, 1:16:47 their formal systems? In a certain sense, yes. I mean, you've got to be a little careful about these things. But I was hearing just recently, I think it was on Zoom talk. Yeah, 1:16:57 the remarkable 01 model of ChatGPT. What would be an example of something mathematical that 1:17:05 you think a computer could never do this? Well, it doesn't do anything. You've got to tell him. Well, 1:17:12 even if you put it on play, you just press play, and you say, generate for me some math. Because if 1:17:18 it's the autoplay that's the issue here, that's easily solvable. I mean, there's a confusion, 1:17:23 I think. I mean, it's also important to me. See, because one of the talks that I attended when I was a graduate student at Cambridge, nothing to do with what I was doing, was a talk by a man 1:17:33 called Steen on mathematical logic. And I learned about the notion of computability. I learned about 1:17:42 the Gödel theorem. I found it stunning, because what it told me, you want to prove something in 1:17:49 mathematics? How is this statement? What the Gödel theorem says, it says, I am not provable by your 1:17:56 methods. Yet, I know it's true. Why do I know it's true? I know it's true by virtue of my belief that 1:18:05 the proof procedures only give you truths. There is the idea that people can brain upload. That is, 1:18:12 they can take your consciousness and put it onto a computer? No, I'm saying no on that one, definitely. If a computer, when you say the word computer, you have to be saying what I mean by 1:18:23 a computer, and what Turing meant by a computer, which is a computational system. So if it's that, 1:18:30 no is the answer. If you're talking about a physical entity, which is not an animal, or not a living being in our ordinary sense of the word, maybe. But it has to take advantage 1:18:40 of what we're taking advantage of without even worrying about it. Which is, presumably, 1:18:48 here I'm going way outside of what I know, but I'm saying it's whatever the physics is which 1:18:53 governs the collapse of the wave function. Right. Now that is not quantum physics, because quantum physics doesn't have an answer to that question. It's this physics which combines GR with quantum 1:19:03 mechanics. Maybe it used multi-twistors for all I know, I have no idea. It would be very nice if it Many Worlds Theory 1:19:09 does. Do you think if quantum theory was not to be modified, then the many worlds interpretation 1:19:15 is the way to go? It would just be wrong. I'd say it could be any way people believe in. Stick to 1:19:23 quantum mechanics, that wrong theory, then they would have to go that way. But I don't want to go that way, because I want to go the way that the world goes. Oh, what I mean to say is, do 1:19:32 you think quantum theory as it stands implies the many worlds theory? Quantum mechanics doesn't say 1:19:41 anything about the many worlds theory. Yeah, in a sense, yes, because it says all these things are in superposition. But I'm not quite sure what the many worlds theory is, because it can't be just 1:19:51 that. Otherwise, I wouldn't see just one world. So what is the rest of the theory which tells me that 1:19:57 I only see a limited proportion that may be there in superposition, but not many? Certainly not as 1:20:03 different as they could be. I don't see all these alternatives. Now, is that to do with this little 1:20:10 creature crawling through this multitude? Now, why doesn't this creature going off in another 1:20:17 branch? It doesn't explain anything. Recently... I'm just saying it's wrong. You're trying to say 1:20:25 if I believed in quantum mechanics, yes, but then I can believe in a wrong thing and I get another wrong answer. I'm just being my rude self to say that quantum theory is wrong. We like that on 1:20:36 theories of everything. So, you were recently speaking to Bernardo Kastrup about idealism, Idealism 1:20:44 which is about consciousness as fundamental. So maybe you don't recall, but it doesn't matter. The point is some people believe consciousness to be fundamental. Was this a video thing? Yeah. No, 1:20:54 I think I did recover that. Okay. Yes, I think he was saying things which seemed to me orthogonal to what I was saying. Okay, so please recount your views on is consciousness 1:21:06 fundamental? Yes and no. How's that for an answer? A superposition answer. It depends at what level 1:21:16 you're asking this question. I mean, if there were no consciousness, I can't see... You see, 1:21:28 a question like this has to have a framework. You see, I'm talking within a certain framework 1:21:34 of theories. What's something that you used to be dismissive of when you were younger that you used CCC 1:21:41 to disregard, repudiate? Many-worlds theory. As you're older, that you're more open to it. Oh, 1:21:47 I see. Oh, no, no. I'm worse. I've got more narrow-minded as I've got older. Interesting. Oh, 1:21:54 yes. I'm terribly narrow-minded now. I'm prepared to listen to other things, sure. But I... No, 1:22:02 I think CCC is right. I think that collapse of the wave function is right and it's a gravitational effect. Can you talk about that, about the CCC? Now? Yeah. Just briefly, if you don't mind. Sure. 1:22:15 Well, it was one thing when I was saying fashion, faith and fantasy. The fantasy was inflation. See, 1:22:21 I don't believe in inflation. Right. The current view of cosmology is that the very early stages 1:22:26 of the universe, first tiny fraction of a second, there was this inflationary phase. 1:22:31 Which was supposed to smooth out the universe and that's why it seems so uniform. Now, it's a load 1:22:37 of poppycock as far as I'm concerned. I don't know about that word to use here. It's probably poppycock's early mouth. Because if you reverse time, it gives you the wrong answer. I mean, 1:22:49 black hole singularities are... I mean, any theory which would iron out singularities should iron out the singularities in black holes. They're completely different. The singularities 1:23:00 in black holes are absolutely wildly diverging via curvature. The singularity in the Big Bang 1:23:10 was an extraordinarily special event. I haven't seen any explanation of this. I had various wrong 1:23:19 explanations of my own. I thought maybe quantum... Yes, when you have quantum theory, I was trying to 1:23:27 say that singularities had to be one way around. What would you like your legacy to be? It's really Roger’s Legacy 1:23:35 fairly equally split, I think, between CCC on the one hand, the cosmological picture, and well, 1:23:43 the wave functions. You see, the theory there is not developed enough to anything there. It needs much more. You see, the theory, that's more twisted. twistors and their offspring. 1:23:55 And I'm hoping that... You see, when I talked about... I talked to too many people today. Did I 1:24:02 talk to you about the product of three vectors? I did, didn't I? Yes. Yes. You see, you multiply... 1:24:08 In twistor theory, in bi-twistor theory, you have a product of three things gives you a fourth. And 1:24:15 this is useful if you want to talk about split space. But there's another thing which might be useful for. Those three... It's really the span of those three things. It's like a vector product. 1:24:25 It's not your... It's you lost the vectors. It's really the span of the two. It's the way you talk 1:24:31 about the plane. So with the three things, it's the way you talk about a three space. Now that's 1:24:37 awfully tempting to me to think that that might have something to do with strong interactions. 1:24:44 That it's the SU3. That's where the SU3 resides. See, in one of my conversations with Feynman, 1:24:51 they're all stories, and each one is a nice story. But I had a conversation with Feynman, which 1:24:57 Stephen Hawking had organized. And he was a bit grumpy because Stephen had disturbed his holiday. 1:25:05 But anyway, and I was trying to describe twistor theory to him. And then I was trying to describe how you might describe particle physics in it. And he said, don't follow that route. He said, 1:25:19 what I said about twistors, it's very interesting. Yes, keep that going. But don't try to follow that 1:25:24 particular route towards particle physics. That's wrong. That's not a fruitful route. And he was 1:25:31 completely right. That was wrong. It was much too early. So we tried to do particle physics with 1:25:38 twistors, putting a few of them together and all that. And I think that was wrong. I think he was 1:25:44 right. He was right that I was wrong. However, it doesn't mean that the thing with bi-twistor, 1:25:50 it's much more like what, it's more like SU3 because you really don't care where the 1:25:55 vectors are. It's the space. And it's a way of attributing another entity to it. I don't know 1:26:01 if I can say what I mean. It's a bit more like the other exact gauge theory there is in physics, which is electromagnetism. And you do have a thing like this in Biotwistor theory as well. 1:26:11 You have this thing which I call multiplying by I. I needed that as well. So it's another, it's a circle. So you have this circle and you have this three-dimensional space. The question is, 1:26:24 what do you want your legacy to be? Well, I say it's a twistor theory, you see. But CCC is quite 1:26:30 a good one for a legacy, I guess. Because it does change our picture of cosmology completely. 1:26:37 Do you believe it to be the case? Or do you just posit that as a possibility? Look, it's a completely different story. In this case, there is strong evidence that nobody pays any attention 1:26:48 to. But I say nobody, not quite anybody. About conformal cyclic cosmology? We see these signals. 1:26:55 I mean, there isn't a nice wrongness about them, too. Okay. But the wrongness is just a factor of 1:27:02 two. I mean, all these are anecdotes. As I say, I'm too old to do physics. I just do anecdotes. 1:27:09 No, I had Zoom, not Zoom. This was just email communication with Alan Guth about… Cosmology? 1:27:19 Yes. That's right. And he was telling me about… I'm giving him all the credit. He put our boots 1:27:27 on and followed exactly what we should do in our calculations. And he said, your calculation of how 1:27:34 big the Hawking points are, these are spots which we claim are there in the… They're observed with 1:27:41 strong observational 99.98% confidence level. Particle physicists tell me that's much too 1:27:47 small. You need much more confidence level than that. It's only about three sigma or something. I don't know what all that means, but that's what they tell me. But still, for cosmology, 1:27:57 that's a pretty confident level. And these spots are there. They're all the same size. They're all 1:28:07 about eight times the diameter of the full moon. Alan Guth tells me, you're wrong. They should be 1:28:14 four times the diameter. He doesn't tell me the diameter. He tells in terms of radians or 1:28:19 minutes of arc or something. I forget what that means. So I'm used to the full moon. I'm using my 1:28:25 low grade… They're only four times. He said they should be four times. So I email Christoph and I 1:28:30 say, look, Alan Guth tells me that we got the wrong size. They're not eight. They're only four times. Christoph tells me, no, that can't be right. I go and check. But sure, 1:28:39 he's just made a mistake. He comes back to me. He's right. They should only be four times. So 1:28:48 we have to do something with our theory. We have an idea what you should do. It doesn't change the 1:28:54 whole scheme. I mean, ordinary cosmology doesn't get them at all. Getting just a factor of two 1:28:59 wrong is mild. It's minimal. And they're seen both in WMAP and in Planck. I'm only counting the ones 1:29:07 which are strongest and which are the strongest ones, which are the same ones as seen both in 1:29:15 WMAP and Planck. There are five points. When I say points, there are these little spots in the sky, 1:29:21 five of them, which we see in exactly the same places in WMAP and in Planck. Confidence 1:29:27 level calculated by Christoph, because I don't know how to do that kind of thing, 99.98% confidence level. People contact me and say they don't believe us. Well, people say, no, 1:29:40 I've done the calculus all by a different way, and I only get 95% confidence level. Okay, well, 1:29:46 you could use your method if you like, but that's not interesting to me. You just outlined how you'd 1:29:52 like to be remembered in physics. And I'm curious how you'd like to be remembered as a person. As a 1:29:59 person? Not too much of an idiot, I hope. Well, look, there's a book coming out any minute. I'd 1:30:05 better read it first. And I'll see how it tells me how I might be remembered by people. I don't 1:30:11 know. Who's taking on the torch that you're passing? Who are the people? Yeah. And what is 1:30:21 that torch? Briefly speaking. Well, there's more than one of them, you see. There's one in twistor theory. I don't know who's carrying it on twistor theory, because it's gone. You see, if I'm talking 1:30:32 about twistor theory, there's three versions. No, the answer is there's pseudo-twistor theory and 1:30:39 twistor theory and pseudo-twistor theory. And then pseudo-twistor theory done by the mathematicians, 1:30:45 which is all positive definite space. The pseudo-twistor done by Ed Witten and company has 1:30:50 got two time dimensions and two space dimensions. Those are pseudo because the dimension is wrong. 1:30:57 Mine has got one time and three space. So I'm calling that the real twistor theory. Now, the 1:31:02 number of people doing real twistor theory is not very big. The ones who do pseudo-twistor theory is 1:31:07 quite huge, particularly the mathematics people. It's quite a big subject now. But it's not my 1:31:13 twistor theory because it's still pseudo-twistor theory. What's your advice to students who are 1:31:19 getting into the field of theoretical physics? And what are your views on academia as it stands now? 1:31:27 I think there's probably too much domination by things you do on computers. I'm not quite 1:31:34 sure what I mean there. I don't know. I mean, I don't really, I don't know most of what people 1:31:40 do in physics, and I can't really comment. So I can't be rude about it. It shouldn't be rude about things I don't know. I think it's difficult to shake. I've noticed that in cosmology. You see, 1:31:51 this is a scheme. I'm talking about CCC now, which is not taken seriously simply because it's too 1:31:59 outrageous. It is outrageous. So if somebody had mentioned it to me before I thought about it, I 1:32:04 might have thought it's not worth thinking about. I did even have a session with Stephen Hawking, me and Stephen and nobody else, and I described CCC to him. I don't know what he thought of it. He 1:32:15 came away without saying a word. Though he asked me one question which showed he didn't completely understand what I'd said. So I tried to get that straight. I don't think he believed a word of what 1:32:24 I said. What do I do? Well, it's outrageous. The theory is outrageous. I agree with that. Doesn't 1:32:31 mean it's wrong. There's evidence for it. Then it solves the problem of the specialness of the 1:32:37 Big Bang. Nothing else does that I've seen. Now just imagine you're speaking to students 1:32:43 and they want to know what advice do you have, sir? I think when people ask me that question, apart from being completely flummoxed, I say do what excites you. I mean, you have to concentrate. 1:32:55 In doing physics or research in general, you have to have your area which you concentrate on, 1:33:01 but you've also got to have a broader area. So it's a bit like a funnel like this. You go way down deep in the area you're interested in, but you should keep an interest in what's going on 1:33:11 all the time as well. So don't shut your eyes to what the rest of the world. Then you may see a connection which nobody else has spotted. Thank you, sir. It's been a pleasure. Thank you. 1:33:24 Also, thank you to our partner, The Economist. as it sounds like. Secondly, if you haven't Outro / Support TOE 1:34:00 subscribed or clicked that like button, now is the time to do so. Why? Because each subscribe, 1:34:06 each like helps YouTube push this content to more people like yourself, plus it helps out Curt 1:34:12 directly, aka me. I also found out last year that external links count plenty toward the algorithm, 1:34:18 which means that whenever you share on Twitter, say on Facebook or even on Reddit, etc., it shows YouTube, hey, people are talking about this content outside of YouTube, which in turn 1:34:30 greatly aids the distribution on YouTube. 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