Neil Turok: Physics is in Crisis

um most I I want to emphasize that most of what theorists do is wrong okay and one of the main sort of in my view most important things about a theorist is they should be willing to recognize when they've gone wrong any sufficiently advanced technology is indistinguishable from Magic welcome everybody to an episode that is coming to you courtesy of audience demand as well as host demand uh and it is with a renowned uh theoretical physicist cosmologist uh named Neil Turok who I've known for decades uh since he's been so kind as is his want to Mentor thousands maybe millions of people around the world and as a young grad student I met him uh when he first came up with some of the ideas that would later encourage experimental cosmologists such as myself to pursue a unique signal in the cosmic microwave background that we'll get to called b-mode polarization and Neil did some of the definitive work on that he's also collaborated with uh good friends and Friends of the show like like Paul steinhardt and Aegis and others and today he is joining us all the way from Edinburgh Scotland and that is Neil Turok a renowned scientist His official bio is sometimes out of date uh but it is reading as follows per he is the director emeritus of the perimeter Institute for theoretical physics and that uh he became Emeritus in 2019 he was there much longer uh than that or I spent many weeks visiting with him and his colleagues and he originally originates his personal Big Bang came in South Africa and Johannesburg and will maybe get to some of that how that is early uh childhood influenced him in San Diego and Neil you may not know this but I have to get you here we have a huge South African population I don't know if you've ever been to La Jolla but it's a it's quite astounding I have yeah and I'm very jealous Yes actually yeah they say Cape Town is more similar than Johannesburg but at any rate he is the also the uh the holder of the inaugural hake's chair of theoretical physics at the University of Edinburgh and he has been there since uh since 2020 he obtained his uh his PhD uh way back when in 1992 was it uh uh he was a postdoc at fermilab in Santa Barbara he's one of the Maxwell Metal He's written many books he's worked with uh the only you know one of the few guests I never got besides your fellow South African uh Elon Musk I hope to get him someday Neil if you can put in a good word but uh Stephen Hawking who I barely miss getting maybe a few years back but um right but that's for the ages at any rate I want to ask you first of all uh I want to thank you so much for for joining us and you are seriously here in part because of my strong desire uh but also because the audience was basically begging for it and will take audience questions in just a bit okay so uh so Neil we always start off by asking authors of phenomenal books such as yourself along with your co-author and past guest uh Paul steinhardt we always ask you if you're willing to play a game that we call judging books by their covers [Music] you're never supposed to do but you wrote uh along with Paul a phenomenal book uh called endless universe and in fact that's the title of this episode and uh I want to ask you we'll get into all your incredible uh delightful work but that book is a popular book and I want to ask you what is the meaning of the title of the book and what is the cover meant to evoke in the minds of readers and we'll show a cover over this so can we please judge your book by its cover okay um wow the book was really trying to convey how exciting it is to be able to make models of the entire universe and its entire history um and then test those models against Real data um and so I'm always very clear to differentiate between theorists which I call imaginary people and experimentalists who I call real people thank you and that's a little bit of a joke on uh complex mathematics where you have real and imaginary numbers but that's really the way I see things is that the theorist's job is is of course to benefit from the incredible observations which are made by people like you think a lot about them try to make mathematical models which fit them and ideally which make more predictions which then people like you can check um most I I want to emphasize that most of what theorists do is wrong okay and one of the main sort of in my view most important things about a theorist is they should be willing to recognize when they've gone wrong um put themselves up to scrutiny to test both mathematical and and observational and if either fail move on to a better Theory so although that book I was very excited at the time we had a theory which was connecting the big bang with string theory and a development of string theory called M Theory I was excited about it but at the time but I have to say uh the more I thought about it the more I doubted its uh foundations and so although I was excited about endless universe I've written another book since called the universe Within that is actually also a popular book um which again tries to give a picture of the what it's like to think about the universe but what I'm really excited about now is almost the opposite of what's in the endless universe which is that the point the main point is that observations of the universe made by people like you uh have revealed something incredible which is that universe is unbelievably simple and by simple I mean very economical in what it takes to describe it you just need five numbers um and so far there's no evidence for anything more than those five numbers whereas when we look at our theories they are they have become unbelievably complex Arcane with a million assumptions and fixes and starting about five years ago um I basically decided this has all become you know a bit of a joke to to be honest uh what we should be doing is being strongly Guided by the data to constructing much simpler models of the universe and by simply I don't mean uh less precise or vager or or anything like that I mean that basically we the evidence is we've been missing something um and I'll I'll go into detail about what that something is and once I made this switch As I said about five years ago I said look I'm just not willing to build these Arcane models anymore I'm going to be ruthlessly self-critical meaning that I'm not willing to introduce even one extra field into the standard model standard model is basically a well well verified picture of what we know about physics I'm not gonna I'm gonna be extremely reluctant even to introduce one new ingredient by that assumption I'm just reeling out all the models that have been developed in the 40 in the last 40 years everybody's been introducing extra Fields extra particles extra dimensions you know and what did we end up with we ended up with the Multiverse which is the least predictive Theory ever okay and uh most predictive well it predicts yeah it predicts the most but it's it's the the least testable let's say where is the evidence both on the very large scale and on the very small scale has gone in the opposite direction so the Large Hadron Collider you know the greatest experiment ever built discovered the Higgs boson and absolutely nothing else okay so most theorists like me 99 of theorists are extremely disappointed at that result oh my God everything we've done for the last 40 years has led to nothing there's just no extra particle to be found and uh I'm exactly the opposite what my interpretation is that nature is has been smarter than we have been and nature figured out how to get away with just having the bare minimum you know the Higgs boson which is necessary to make uh standard physics work and no more so on the tiniest scale we have this surprising economy in the laws of physics on the larger scale it's the same thing the Planck satellite uh subsequent experiments your forthcoming very exciting experiment with the Simon's Observatory you know so far these have revealed nothing new uh that's not bad that's that's a huge challenge for fundamental physics it says to us maybe we're working on on you know a questionable set of assumptions maybe there are principles very economical very powerful principles which we haven't yet figured out which will resolve the paradoxes we have such as the dark matter the dark energy the Big Bang itself uh what goes on in black holes you know that they're very very basic paradoxes and maybe we just need to think a little harder um so after I've started following this line of research about five years ago it's very difficult because you've essentially tied your hands together I'm not allowed to introduce a new particle okay and but we've made amazing progress at least I find it amazing we've realized what the dark matter is it's probably a right-handed neutrino which is already there in the standard model it's extremely economical explanation we've found this is something I'm most excited about recently a new explanation for why the universe is so simple on large scales you know the the geometry of the universe what is the universe like on large scale well in first approximation it's flat space it's the thing you learn about in geometry in Primary School you know there's X Y and Z there's no curve at curvature at all why is it the simplest possible geometry it's a huge puzzle which motivated the theory of inflation so now we have a new explanation and the explanation is extremely economical it it doesn't make it easy to understand but it basically develops Stephen Hawking's ideas about black holes and we we literally do a calculation of the thermodynamics of the universe which I'll say very briefly shows that you know just like the gas in a room um will distribute itself evenly in space because that is the most probable configuration of the atoms if you Chuck them in with some energy allow them to randomize they will spread themselves out uniformly in a smooth distribution you don't have to introduce somebody to smooth that or do something active another field or particle it just does it itself that's thermodynamics and so we figured out the thermodynamics of the cosmos using Hawking's insights and with no finay going um with new particles or whatever with some very simple mathematical assumptions we find the most probable universe is flat uh exactly the geometry we see and it's the simplest geometry and so that's an entirely new explanation it doesn't require any new ingredients it will take people a long time to accept this well aware of that because people have built their careers for 40 years on differing different assumptions but I'm personally very excited about it I think what we're seeing is a way through to explain all the puzzles all the major puzzles in theoretical physics with absolutely minimal additions to what we already know well there was a man who was an alumna alumnus of uh Irfan University who had uh had a fair a bit of experience with simplification with unification and uh with really constructing a strict mathematical model of the universe and uh it worked pretty well uh except for the fact that it was also based on very simple principles involving gears and vortices and whirlpools and of course we're speaking about the late great uh James Clerk Maxwell who's a talent in all of it and maybe you know in the spirit of of a Higgs or a Yang Mills or uh in the same in the same way what do you make of his ultimate what he did Neil is so interesting because he was absolutely correct for all the wrong reasons and we see that again and again in science you see that with Galileo he was right about Universal gravity or Newton was around about universal gravitation completely wrong about how it propagated Galileo was completely right about the the orbit of the Earth around the Sun thought it was responsible for the tides that had nothing to do with the times um but tell me Neil is it possible sometimes that brilliant theorists can have the right idea for the wrong reason and in that way give us a glimpse of Truth and maybe could that be happening with inflation in the Multiverse just to be a little bit of a steel man and yeah yeah no it's a good question and it's a big puzzle why inflation and the Multiverse have become so popular because objectively this is a theory with uh an infinite variety of models of lots of parameters lots of Freedom extremely hard to prove wrong um so on the face of it uh it's a theory which isn't particularly scientific traditionally it would be regarded as unfalsifiable and therefore not part of science but um what happened is the field of theoretical physics has kind of been pushed into a corner where many of The Luminaries I mean very uh great theorists like Stephen Weinberg um who you know was more or less a founder of our modern picture of of uh physics and the standard model um came around to this point of view of the Multiverse and inflation and I've I always found it sort of surprising uh that they did but they did for for for you know what you could say were good reasons I mean there's a certain logic behind the steps people followed but it's just a case of you know when you when when you make a few one false term and there's no uh kind of experimental check or insufficient experimental checks you can very easily go wrong and so I think I think that's what's happened I think in fact around the time I entered theoretical physics you know um in the 1980s um the uh that's when the field went wrong okay I'm not saying it was my fault yeah Stephen had something to do with it I think Stephen Hawking had a little bit to do with it he actually in in A Brief History of Time which I went back and read yeah after his death he didn't think it's a big deal about not only is uh is is there no boundary is there no beginning but but that you know the CMB basically proves that there is an inflation there is a Multiverse and uh and he really went quite quite uh and he's so influential uh although my first guess my first ever guest on the podcast uh was Freeman Dyson uh who I loved and uh was incredibly influential I'm sure you knew him when you were a professor at Princeton as well yeah many interactions with he he said the safest thing in life to do Neil is to make a bet with Stephen Hawking because either he was wrong uh AB initio or he would eventually switch positions so you'd win no matter what but I think in this case he he really did and then he went even deeper in his final book uh with Leonard Milan now who was a guest on the show and he said M Theory is basically accepted which I even as an experimentalist I know that's not correct so who do you make of this influential you know kind of these towering figures that really suck up all the oxygen and and kind of mandate the direction of the field like the weinbergs like the you know nowadays there's many of them many young ones and I don't want to criticize any of them but there are very few working on what I would say are the flaws right often I hear I hear this Neil I hear well inflation's not a theory and the Multiverse isn't a theory it's a consequence of a paradigm and I'm like well where do we go to hear about you know like um these are excuses is honestly they're just excuses and it takes some courage um to say that out loud yeah I could really only do it because I was you know academically secure I had a position in fact the reason I really came to my view that the field has gone wrong is that I was director of perimeter Institute which was the fastest growing best supported Institute dedicated to theoretical physics in the world and so my responsibility was to hire young people who were actually going to make discoveries you know and I was committed to doing that and so I had to look very carefully at all the different fields of theoretical physics and weigh up the real prospects of progress and during that it put me in a very unique position where I I sort of had to have an overview of the whole field and based on that um had to be objective because you know we we were essentially investing you know in a place where which had opportunities to invest like no other um and so what I decided is that um going with this going with the flow was absolutely not the way forward um and so I made that decision in my capacity as director I also made it personally in my own research and because I had the freedom with my own research to go down whatever path I I wanted this really made me rethink everything um so now you asked about Maxwell Maxwell is an amazing example uh what happened historically was you know he was a product of his environment uh Edinburgh and and Scotland at that point it was it was the age of Scottish Enlightenment in the 18th century and they questioned everything they questioned you know Big Brother in England uh England had two universities Oxford and Cambridge and Scotland had three okay and the Scottish ones had a totally different philosophy which was Public Access so no matter which background you came from bright kids were very strongly encouraged to go to university and so in this environment people are essentially the mentors of Maxwell were trained and uh you know blossomed so people like David Hume Adam Smith in economics these people rethought everything from scratch okay and so that was the culture Maxwell was was raised in and being very bright he then went to Cambridge uh I mean he went to Cambridge after he made his discovery about light and electromagnetism um but uh he he was absolutely unafraid to challenge the Orthodoxy and you're quite right to say that his way of picturing the world turned out not to be you know what we use now we take the mathematics much more seriously than we take the machines that he used to build the mathematics but but that doesn't matter at all I mean the equations are valid and I would say Maxwell's equations are actually guiding us to what happened at the Big Bang because they guided Einstein to his theory of gravity Einstein said that he's basically developing a version a theory for Gravity modeled on Maxwell's theory of electromagnetism uh Maxwell's equations tell you about relativity the speed of light ultimately told you about photons and quantum mechanics and so you know Maxwell is sort of the inspiration for modern theoretical physics and part of my reason in fact of coming to Edinburgh is I feel it's a place with this amazing history of sort of breakthrough thinkers and it's not too high bound okay having spent time in Princeton in Cambridge you know dot dot dot um I I wanted to come somewhere where I felt there was an openness um to rethinking the foundations because that is what I think is needed yeah if I could show a slide I'll illustrate this let's do that let me uh cue you up okay yeah you should have your screen sharing permissions there you go all right so let me just show you can you see my screen yeah I see it uh you want to push perfect yeah perfect right so this is all of physics in one line uh it's an amazing achievement we have gravity which is sort of Newton and Newton's constant is here and Einstein and the curvature of space now describes black holes which we see then we have Maxwell that's this term and the photons all the forces which keep the particles together then we have the description of particles due to the rack that's this PSI quantity here and this is dirac's formula and then we have the Higgs okay now uh it's quite funny that the Higgs although it's a relatively simple thing has three terms in this equation that's actually a minus because we we always look for an economy and when you have uh you know long equations it's usually a sign you don't really know what's going on but anyway there are three terms involving the Higgs these are particle masses and these are um the electro-week Gage boson masses originate here and then the hex boson which uh Higgs predicted you can think about the Higgs boson really is the water which the particles travel through um and because the water makes the provides some resistance to the particles um uh it it gives them mass and and stops them moving at speed of light so here is everything now in this formula you'll see it's mathematical there's E oil is number 2.718 dot dot dot that's just because exponentials are right in the heart of physics you know exponential growth is what we use in the inflation describing economic inflation for example exponential growth of populations in physics you get an exponential but it ha it's of a strange number whose square is -1 and you know non-physicists always find this extremely worrying it's called the imaginary number um but this was discovered in the uh 1500s by some Italians that if you introduce this imaginary number some somehow you can you can solve uh an infinite number of equations much more easily and um so this imagery number lies at the heart of physics quantum physics in in sort of physical terms you can say that all of physics is just interference uh these are called phases and you add up the phases and they interfere and that's everything okay so here are all the laws of physics now why do I say we have to rethink this the reason is that we actually don't know if this integral it's a very beautiful thing it's saying that you allow so if a particle goes from A to B you actually allow it to go anywhere on root so it can go to the moon and come back and then what you do is you add up all the phases for all of the paths and they interfere typically they interfere destructively so the particle doesn't go there but you have to add them all up anyway and that gives you the amplitude to go from A to B and then you square it and you get the probability so this is a beautiful formula due to Richard Feynman All the known laws of physics are compatible with it yeah but a very long-standing puzzle is whether this formula actually makes any sense um the reason is it's very infinite this formula you know the number of ways of going from A to B is infinite and you have to very carefully deal with that Infinity and so actually that's a puzzle which I've been working very hard on in the last couple of years we think we have a nice way of dealing with it but I have to say that this formula although used everywhere in quantum physics um is uh without solid mathematical foundations and and so I've come to the point of view that making sure we understand those foundations is actually critical so what is that though Neil is it is it an interpretation I've I've heard things like Einstein I mean Einstein would say so many different things of course uh yeah sometimes they're mutually inconsistent I mean he would talk about the time and then he said you know time is is doomed as an allusion to fade away and I've never really understood what that meant but I guess the question for you is is this is this a you know kind of a tautology this equation that basically you're using math but but essentially you're saying it's inconsistent we don't understand it and it's not just because as a past guest you know Michio Kaku says well you know string theory is just the same as Maxwell's equations both have an infinite number of terms and you have to tell me what the vacuum stand is I said that's not my job my job is to prove you wrong not not to prove you're right right so what do you mean that it's inconsistent or that it's you know is it philosophical where are we going no no no it's a very so if you ask if you ask an any sort of honest theoretical physicist how do you justify using this formula the first thing they will tell you is if if they're honest and and sort of rigorous is that you've got to get rid of this imaginary number by rotating time to imaginary values right as hockey very powerful trick okay and it's actually used and the reason you need to do it is because it removes the oscillations you see what what this formula tells you is you've got to add up all these phases the the way physics works is these phases interfere this is like you know two water waves like a water wave encountering a barrier with two slits in and the water wave continues through the slits and then these waves interfere and you get basically beautiful pattern what we call interference pattern and uh but you've got to keep track of these phases properly and that's very difficult so usually people just remove them by changing time making time imaginary and I Stephen you know taught me this method uh I used it to study gravity and we discovered it fails it fails miserably but in this book Neil of course he says he says I'm going to introduce it it's just a trick and uh we shouldn't take it seriously and then later on he bases the no boundary you know a Hawking heart yes on this trick so what is it is it is a trick it is a trick and Hawking to his credit was always looking for the very simplest way to explain anything and here's no boundary proposal is an extremely beautiful idea it basically says why is the universe is the way it is today well we don't Prejudice that in any way by assuming anything about the beginning we allow it to do whatever it likes to do um in the past and is no boundary proposal was that there was no boundary uh in the quote beginning of the universe so you you sum over geometries which are smooth uh and sort of round off nicely in the past the virtue of it was that it was mathematically precise and principled and very appealing very economical the problem was that when you calculate it in detail as we did um this would be three or four years ago we found it as mathematically inconsistent so now Hawking to his great credit was open to the criticism they invited me to a uh a private retreat I went with a whole bunch of with him and a whole bunch of his collaborators we discussed it in detail and I wouldn't say I can't say Hawking accepted it but he didn't argue against it and then when his collaborator um sorry you just mentioned his name he the internal no the one who wrote the popular books with him oh Leonard Millard now yeah Leonard not not enough when he he's written a recent book yes about um basically what it was like to work with Hawking yeah and in that book he explains how he asked Hawking what do you say about Neil's work because it directly contradicts your no boundary proposal and and Neil is claiming it's wrong and Hawking was unbelievably generous Hawking said when you're a theorist most of the time you're wrong and when somebody shows that points out a floor in your assumptions you have to be grateful because what they're doing is actually saving you time you don't want to waste your time on a thing that's wrong I mean if you read the quote in not enough's book about our work on no boundary you have to come away saying Hawking was amazingly scientific and generous generous gracious you know gracious so um what I'm do the way I would describe what I'm doing now is try trying to implement Hawking's idea because I think it's the most beautiful idea for the beginning of the universe whatever that means I'm trying to implement it in a way which is consistent and if I have time I'll show you some pictures of how we think it it yeah let's go there now because you you have the screen okay yeah so so main picture for main uh take home from this slide I mean it looks like a horrible mathematical equation but it's describing everything all the laws of physics in one formula as I say the our task is there is really to make sure this equation is Meaningful um and uh uh and and that's what I'm I'm focused on I should say my uh listeners so about half the audience you have a hundred thousand people in the uh into the impossible family about half of them are probably uh listening on audio only so please make sure to visit Dr Brian King to see the slides but also uh look up a video by Neil Tura called the astonishing Simplicity of the of the universe uh it has several million views um and it is really everyone uh or you know a renowned kind of introduction to some of these ideas that Neil's exploring from a few years ago when he was first grappling with them so I want to point that out but we'll Endeavor to discuss these Topics in more detail now you're showing uh Peter higgs's uh paper I think this is his first paper uh yeah he's also called Gage boson so yeah let's uh let's explore this equation thanks Brian uh yeah the lecture is called the astonishing Simplicity of everything yes and as you say that that's really when I was first beginning to explore these ideas hopefully today I'm going to tell you a lot more detail yeah where we've been LED now I want to point out Peter Higgs paper this is the entire thing right this is the paper that won in the Nobel Prize it's one and a half pages and uh the funny thing is I gave a talk at Princeton I don't want a badmouth Princeton too much okay but you know they they can take it yeah uh I gave a talk at Princeton a few years ago and I when he when this Higgs boson was just discovered and I was celebrating this you know somebody comes from Left Field with a new idea about this uh the way of how you break symmetry and then 50 years later right it was it was almost 50 years to the day what they predict you know was discovered in in nature in a 10 billion Euro Machine you know it's it's just an amazing story and in fact what won him the Nobel Prize is this one line in the paper this this is the Higgs boson this is its mass okay and uh so now here's Peter Hanks okay he's he's still around uh I see him regularly he's he he's quite ancient and housebound now but very gracious uh individual uh here he is in the biggest experiment ever conducted the Large Hadron Collider and he looks like he knows what's happening and I can assure you you he has absolutely no idea how this thing works we only let theorists into the experiment for publicity shots Neil you know that exactly exactly so and that doesn't matter at all you know his job is to think through uh you know what makes sense and and that sounds easier than it is it's a tough job because these things which are going on are extremely remote from any of us you know very hard for us to picture in our minds and we have to use mathematics as a guide because it's our only sure way of checking that the logic is correct and uh and that's what he did you mentioned Princeton and I'm waiting for the for the uh you know for the the claws to come out but uh yeah right close it was passed guest first guest on the podcast Freeman Dyson who Peter to come to the institute for advanced study in the summer when he was unsabbatical after this paper that really gave him the courage so I'm curious to hear what was the what's the essence of the of the gentle kind of uh uh we ought to have a little bit of spice on the podcast yeah two things so actually when Peter was a young lecturer in Edinburgh he had a PhD student who got an offer from uh North Carolina at Chapel Hill to go for a postdoc and at that time Bryce DeWitt was the head and it was a famous place you know Nuclear Physics lab um one of the most prominent places Bryce exactly huge Guru at the time so the student decided to leave physics and so Peter wrote to Bryce DeWitt and said can I come instead so he went to Chapel Hill as a postdoc he offered he a very shy person by the way Peter Higgs very shy very modest went to Bryce DeWitt and said could I give a seminar about this idea about symmetry breaking and Bryce DeWitt said well explain it to me first and so he did and Bryce DeWitt who was like the world expert on Quantum field Theory and everything related to this said no it's nonsense um you can't give a seminar you'd be wasting our time so and so Peter never gave a seminar there and then as you say um Freeman Dyson uh uh invited Peter to Princeton and and uh and then the rest is history but um but I the reason I mentioned Princeton is actually I showed this slide and to my great surprise at the end of my seminar a number of the prominent gurus in the field who were there came up to me and said oh you give him too much credit you're giving him too much credit well uh what he did we now see is kind of trivial and Goldstone was there first and you know yeah they had a whole number of arguments but basically it was uh you know so which I was just shocked at because um to not recognize that a stiff to to refuse to recognize that in extraordinarily simple idea which everyone else had missed by the way suddenly brought things into consistency you know and and and and to be grudging about that I just found extraordinary but uh but but anyway that that's their choice and Princeton is now the hub for string theory the Multiverse uh you know all super symmetry all kinds of complicated ideas which so far have no experimental evidence at all and so it's quite clear who won that particular debate uh you know the Higgs boson was found nothing else what has been found none of these other theoretical constructions have been found now I I sound a bit like a curmudgeon but I'm not no I know um here's the wonderful story 50 years and 10 billion euros later they built the biggest experiment uh of all time and they found the Higgs boson and there's Peter Higgs uh chatting to the other Nobel Prize One winner Francois angler also an extremely unusual and creative uh personality so I think what I wanted to just before we go to the next episode I assume is going to be on cosmology you know back in the 80s and 90s when I started grad school in the 90s and met you for the first time as a Dapper young Professor I remember uh you visiting um uh Brown University at one point and then we visited you in Toronto uh but the um but back then there was a pejorative uh coined first by uh Alan sandidge who called cosmology the search for two numbers and I kind of poked and prodded at Frank close in our interview about Peter Higgs I said isn't the LHC worse because it's a search for one number right it's done since and then it's oh there's hints of new physics and oh we have believe me Neil you romanticize experimentalists a little too much because you you think that we're all just no these guys are now talking about building a collider on the moon and building right the size of the solar system and uh right that's the question that I have for you before we turn to cosmology which is another area of redoubt and expertise that you uniquely have in the world uh and that is you know are we kind of in an ambiguity the human brain hates ambiguity they hate we love to make decisions pro-life pro-choice we love no guns guns at least here in America I I don't know brexit or how about this brexit or no brexit uh that'll that'll get you uh agitated I'm sure but at the at the heart we we kind of fixate on targets and then when there is no Target now we're in this desert between in cosmology where inflation you would freely admit and I know that you would that inflation could be right I mean it could be um sure but it could be it could be true but we'll never be able to detect it because the energy right are going to produce negligible demotes now when we're in the state with particle physics and cosmology then other things like string theory M Theory um uh supersymmetry all these things will Bloom but is it ultimately hopeless list without a tool an instrument to right what can the Mind by itself the Duncan experiment that Einstein Pioneer you know thought about someone how much can we really do without experiment and without hope of building a a 10 to the 16th you know gev collider to replicate the primordial Universe are we doomed no no far from it uh I believe that we need um new insights into very fundamental questions so let's go to one question so it says this is slightly technical it is a technical field I apologize for that the audience is very technical too I mean we've had 13 12 Nobel Prize winners on so far so they're very technical good so um I've emphasized we have to make sense of this formula yes now the way we use this formula in physics so far is very very uh restricted okay so we use certain aspects of it which work unbelievably well one aspect is to calculate what are called scattering amplitudes how particles scatter off each other and those things are measured in Laboratories like the Large Hadron Collider now most of those in fact all of those calculations almost all of those calculations are done um using what we call perturbation Theory okay now perturbation Theory says if some parameter is small in your formula then you can hope to calculate it by an expansion a mathematical expansion in that parameter okay so uh scattering amplitudes most of what we know about them is perturbative and and so this formula has only ever been checked as an ex now the small parameter may be really small like the fine structure constant which is 1 over 137 that's a fairly small number and if you calculate you know to whatever uh fifth order in in one over a hundred you know then you're going to get um 10 to the minus 10 as the correction and uh and you you may be happy with that so physicists have become used to sort of only uh using this formula in perturbation Theory what you discover in perturbation Theory so it's a you know basically this is a poor man's approach you know the the rich man's approach to this formula would be to say I want the answer okay don't give me some approximation to it I want to know this formula actually makes sense as it is for for all quantities whether I calculate them perturbatively non-perturbatively Etc we don't know if this formula makes sense non-perturbatively in fact for Gravity nobody has even tried this rotation to euclidean time definitely does not make sense but that's not what this formula says either this formula says do it in real time calculate the interference of different space times uh all at once you know it's it's very ambitious but that's what the formula tells you you have to do and we haven't been able to do that now the reason people went for string theory is that in perturbation Theory it's very hard to get rid of the Infinities in gravity without adding extra ingredients like extra dimensions of space and more particles like supersymmetry but that's only perturbation Theory there's a physical mechanism which may of itself get rid of all those Infinities and that is that when you when you consider very high energy processes which is where these Infinities come from Gravity makes them into black holes that's what gravity does and so if you fire two particles together with high energy you're going to make a black hole and so gravity itself eats up high energy regions and then we believe recycles them into Hawking radiation now that is a very natural mechanism whereby in this formula all the Infinities may be removed without adding anything extra at all the problem is the calculations which would show that are currently too difficult to do nobody's ever tried they they're so hard you know to calculate what happens when I fire two particles together include the effect of gravities um allow gravity to eat up the high energy reason regions and see if that removes the Infinities maybe it does in fact this is more or less how String Theory Works um string theory is sort of toy model of of gravity I would say so we don't know that we have to add all this extra junk we don't know that at all that's an assumption based on an approximation uh of what we call perturbation Theory so nevertheless you know the vast majority of great physicists like Stephen Weinberg and and and many others accepted that we have to try out String Theory because perturbation Theory and string theory looks better than perturbation theory in plain old Einstein gravity so there are ways to resolve the Infinities without adding extra stuff and that's what I find much more interesting currently is does nature do these laws suffice to describe nature as I said we don't actually know that they don't and the only way we'll decide that is by developing our capability to calculate exactly what this formula um means and and yeah so I'm busy just trying to take this formula more seriously and see if maybe it resolves all of these problems without any need for extra Dimensions or strings or or other particles or anything now before I rudely interrupted you uh you're about oh please go ahead you're showing something from the great Bard and it is not as uh the actors would say that from the Scottish play oh that's right would you like to uh show the Cosmetics yeah so on the very smaller scale we've discovered that nature is more economical than 99 of theorists expected right the LHC has come up with a blank um still worth every penny I would say uh knowing there's nothing in my view is in a way more inspiring than finding a particle because it forces you back to the drawing board that's always a good thing you have to figure out how the hell does nature work if it doesn't use all these tricks and and model you know models which we invented to make it work how does it work those paradoxes which motivated strings and and super Symmetry and all the other additions the paradoxes are still there how that how it might work is that nature is more subtle and we have to understand that formula the first Formula uh you know more um in more depth than we currently do so now that's on small scales on large scales the same story uh uh this is the picture I'm showing the picture of from the playing satellite of the visible Universe uh it's the whole sky and what you see is the pattern of irregularities in the OR density variations in the early universe as it came out of the big bang and these variations gave rise to galaxies and stars and ultimately us um so it's a marvelous picture with very lucky generation to see it um it literally is the the vast Shore washed with the farthest sea that's uh in Shakespeare's words uh from Romeo and Juliet because we're seeing waves and we're seeing the waves in the uh distribution of matter and radiation as it emerged from The Big Bang and it's really like an ocean we live in the middle of this ocean and now we can see it um so wonderful picture uh what is unbelievably what is astonishing about it is how simple it is uh you know a priori if the universe was built out of Lego as you went to larger and larger scales it would get more and more random and complicated or if it was a Multiverse you know surely we would expect that as we went to larger scales it would get more complicated what we see is the opposite that the universe is extremely simple on the larger scales you just need five numbers to describe everything we see so far and there's a ton of data it's all consistent with essentially models that were proposed in the 1970s um by Jim Peebles and others which require um you know five numbers so again most theorists very upset oh no there's no clue from the data um there's no new physics I'm the opposite I say wow the universe is unbelievably simple what we need is a principle to explain how it how nature got away with being so simple so the five numbers I won't go through them in detail three are for the different kinds of energy in the universe the baryons like us the the neutrons and protons we're made of um and then uh the dark matter and as I'll explain based on this philosophy of economy we have a new explanation for the dark matter which is now going to be testable within the next uh five to ten years and what I'm going to convey is this was staring Us in the face since the 70s there has been an obvious candidate for the dark matter but due to theoretical preconceptions we sort of refuse to see it so I'll explain that in a moment the huge thing is the dark energy what is this so most of the energy in the universe 70 of it is in this form of this weird energy which is absolutely uniform in space uh the same with time it doesn't change in time it's constant despite people searching for variations it seems to be absolutely constant in time and um it is the simplest form of energy you could imagine in fact that's why Einstein did imagine it in 1917 he thought you know he wrote down these equations for gravity and then he said well let me try and make a universe so I'll throw in some some form of matter or energy uh he showed energy and matter or equivalent so he threw in a form of energy which is the simplest possible form and that is what dark energy is so he made a model cosmology it wasn't correct but now uh it turns out that the dark energy introduced is there and it's the most important energy in the universe so you know talk about uh uh seeing things in advance um you know when your blunders are noble yeah it's pretty great you know it was no blunder it was the simplistic assumption what we learned from this is that um nature does in many cases use the simplest available option and in the case of dark you know the simplest Universe full stop would be one which only contained dark energy and that's what Einstein imagined so he was close he was he was 70 70 right oh yeah and he uh and it's too bad because he could have had a good career Neil if he hadn't made that point he would he would go down in history but I want to just gently push back the respect and love that you know I have for you but uh but recently I did a video on my Channel about some work that you and and Nathan Boyle had done on a so-called anti-universe travel backwards of time and I had on one of the experimentalist um Abby vereg professor in Chicago old friend of mine she's young but we've known each other for a long time and uh about the Anita experiment in Antarctica um yeah how how does a how does a how does an anti-universe uh simplify things uh let's go right there there's the paper yeah so in a video above well I'll sort of Link right I did about your wonderful work with Nathan but but still it's it's it's bemusing but but how is it simpler right so uh as I said I've been following the same philosophy that you know maybe the answers are really staring Us in the face but we've got to you know we've got to see them and understand them and that's where this idea of a a universe which which where the big bang is preceded by an anti-universe actually came from so how did we how did we get to that crazy idea okay and actually this crazy idea underlies uh a lot of recent progress not all of which is written up but part of which is going to be if it works an explanation for those density variations which we now see an explanation in which we predict the amplitude from first principles okay that's our goal I told you we're not allowed to introduce any new particles we we want to try to explain the university as it is on the basis of the laws we already know and what's in Prospect and that's why I'm very busy this summer it's a hard and complicated calculation if it works we will explain that the density variations in the sky they're about one part in ten thousand and the reason for that is that's the square of the fine structure constant okay I've mentioned one over 137 if you square it you get 10 to the minus 4. um roughly speaking that's how our uh new picture of the universe works and the origin of that number is something extremely extremely fundamental which is that when you couple the matter in the standard model to gravity there's something weird called the trace anomaly okay sounds very technical what it means is that a symmetry of the matter gets broken due to the curvature of space-time and this is called a trace anomaly um and what goes along with it is that you know when when you have all this these Quantum fields which are describing the matter so photons electrons all of them are associated with a Quantum field the field is unable to stand still the vacuum so the vacuum is not empty the vacuum consists of all the vibrations of all the fields that you add in the standard model and the problem is those vacuum vibrations gravitate gravity detects their energy and so for uh it must be nearly 100 years now physicists have essentially been cheating taken that vacuum energy of all the fields that we know about and we've just subtracted it okay but that is not really consistent that is not consistent and if you ask somebody in their bones I mean Feynman acknowledge this um you know all the great physicists acknowledge this that what we do is essentially when we do Quantum field Theory and couple it to gravity is essentially to cheat so we've found a way around that cheat we've found a way to cancel the trace anomaly and to cancel the vacuum energy without adding even one particle to the standard model so that's very exciting and that mechanism turns out to give fluctuations as a side effect and those fluctuations May match the observations we see so that would be the best of all possible worlds if it does work out as I hope I think all rival theories will just fall by the wayside uh because we'll be able to actually calculate from the a theory we know makes sense what the fluctuations were at the Big Bang so of course that's extremely ambitious it'll probably fail but uh that's what I'm after I'm after an absolutely minimal and compelling explanation for what we see if we don't find one fine we might decide you know either we weren't smart enough or there isn't if there isn't one but uh I don't see any way of resolving that apart from trying do you think you could get information about this not from the particulate content of the universe but from the electromagnetic sector in other words we're looking for what we call turn Simons or Cosmic birefringine signals that would be indicative of CP violation not necessarily CPP but if you know if you could ask God you know one question or Mother Nature I feel like I would ask about you know are the laws of the universe Lorenzen variant you know because we assume that they are but right could that be the most you know kind of preposterous assumption and we only have access to energy scales on Earth where I guess the photons obey you know uh parity uh inversions right uh but time is another matter and and so I wonder could we use the laboratory that these CMB photons which have provided so much richness in my life and made me a wealthy they haven't made me that wealthy but but the point being it's my it's my uh industry right so intellectually intellectually like myself so is that a more promising than looking for you know neutrinos or are you trying to solve you know they're they're they're both extremely promising um let me just say a little more because you you you about why we came up with this crazy antiverse idea uh you know that before the Big Bang there was a an image of our universe so that actually is motivated by something we know very well in electromagnetism which is that which is a mirror if you when you look at a mirror you see yourself right but you're inverted uh left is right and right is left so you look a little bit different in the mirror than if somebody else sees you but um when you try to understand a mirror you know there are two ways to do it either you deal in detail with the way the light interacts with the material of the mirror and the way we say it is you impose boundary conditions on Maxwell's equations which which essentially tell you that the electric field has to vanish and the magnetic field is allowed to oscillate um on the mirror but uh a much more beautiful way of dealing with it is to say put an image of yourself behind the mirror okay where you've reflected left to right and right to left um and then throw the mirror away uh then the light which travels from the image to you will be exactly what you see and in physics we call this method it sounds like a cheap trick and it kind of is but we call it the method of images namely instead of solving a problem with boundary conditions you instead um reflect uh your side of the boundary through the boundary to the other side and then solve the equations as if there were no boundary um and so that was that was our idea a couple of years ago that there was a pre a pre in a sense a pre-bang but it's a perfect mirror cop mirror image of us is not it's not only uh left and right that get inverted it is time itself CPT uh on the other side of the Big Bang time is going appears to go in the other direction you know the universe is growing and galaxies are forming but in the opposite direction of time and so on so it's really a mirror image of us uh you might say this is a sort of empty notion why am I just uh sticking it there the reason I stick this universe there going away from us is that it allows us to solve if you like the boundary conditions of what happened at the Big Bang in a very natural way without just starting it by hand we are actually able to uh you know give a consistent description of what happened at the Big Bang without putting putting it in my hand namely we just mirror ourselves using CPT which is believed to be absolutely fundamental symmetry of nature uh no theory has ever violated it that any no sensible Theory consistent with Lorenzen variants I should say has ever violated it and uh so we make the CPT image and then we use the regular Einstein equations to uh to show you know to evolve the universe from one side to the other so it's a very very minimal assumption and over the last couple of years we've been thinking very carefully is this Mirror Image Universe actually identical to ours you know mathematically identical you know is there Brian Keating on the other side interviewing I'm left-handed I'm Sinister in that universe and we've come to the conclusion through a range of sort of mathematical arguments that indeed it is so so the antiverse is simply a mathematical copy of our universe it's there for convenience for mathematical ease of discussion it doesn't add anything new in a sense of you know another place where things could happen so it's actually extremely economical it's it's it's an absolutely minimal theory if you like our answer to what came before the Big Bang is uh it was us it's just the same as us so when people uh just just pause for one second and talk about the interpretation by the way I want to remind folks I'm talking with a renowned uh uh theoretical physicist the inaugural Higgs chair at uh Edinburgh University uh University of Edinburgh and that's Neil Turok who I've known for a very long time uh and uh has influenced cosmology me my by his writings and his and his work and I've done videos based on his work uh and you should check out his uh just phenomenally popular uh videos online is currently uh in Scotland but before that was the uh was the director of perimeter Institute but um prior you know to to getting into this we we talked about you know uh we did talk about matter and dark matter but there's another form of matter anti-matter which as I understand at Wheeler and and Feynman at all had a notion that antimatter could be viewed as ordinary matter traveling backwards in time um and and I wonder uh if you know I had wanted to ask you what are the biggest misconceptions that lay people have that undergraduates have and then what your fellow theoretical uh you know physicists have but I don't know if we'll have time for that but I is that really a misconception I mean is it really the case that we could we really think that there is a part there is a negative direction of time or is that like Hawkings Wick rotations it's a simple trick no I don't think it's a simple trick um I think it's an extremely deep Insight that Feynman and Wheeler both had and and before them actually a guy called stukelberg whose little known and not so popular was a very shy person a bit like Peter Higgs but he was the true genius uh in Quantum field theory in the 1930s um but apparently he wasn't recognized and and basically went ended up going to chemistry where people were more receptive but he wrote papers where there with this idea of a particle going back a particle going backwards in time was an anti-particle very very beautiful idea uh it's absolutely consistent with uh with everything we know um and in fact Feynman himself made the following statement that um and Diamond you know as as you know won the Nobel Prize for Quantum field Theory and was one of the most accomplished uh practitioners Feynman said the whole of quantum field theory is nothing but a clever attempt to hide the fact that particles go backwards in time particles can go backwards in time and when they do their anti-particles so he viewed you see nobody has ever seen a Quantum field if you if anybody tells you you know Quantum field theory is the answer to life the universe and everything just ask them has anyone ever seen one uh no because the only way we see Quantum Fields is through particles we do observe particles in experiments and um and so what you've you know these fields May somehow represent that they do seem to represent the particles at some level of uh accuracy very high level of accuracy but what is actually going on you know maybe uh maybe particles indeed uh going backwards it may be but you know as my brother older brother would say you know have you ever seen your brain I say no and he says well how do you know uh we haven't seen quarks either and quarks are you know thought to be part of so what do you would you say this would push back and say look you know we absolutely yeah absolutely I I I think we don't know uh and it's true people are very suspicious about quarks because they don't exist at free particles but you know on the other hand why should they uh you can imagine particles being you know tied together with a little piece of string uh in such a way that you're if you try to pull them apart all that happens is you break the string into a new particle appears on on each end of this free end of Frank will check as discussed on the podcast yeah yeah so so um no I think the the what I would say is that you see the why do I prefer one image mental image over another the first thing to say about Quantum field theory is it's basically a gigantic algebraic machine right that's actually what Dyson Dyson's contribution was to turn it into a machine it's a calculational machine and basically the philosophy was shut up and calculate don't worry what's really going on calculate the scattering Matrix and don't worry about what actually happened okay the kind of work I'm doing now to understand this path integral we don't accept that we want to know exactly what went on during these you know inside the path integral and people who study quantum mechanics on its own you know to the the foundations of quantum mechanics and who do experiments to understand the weirdness of quantum mechanics increasingly they are asking exactly that question what is actually going on in the in the middle um it's called the theory of weak measurement you know if you may if you measure something precisely you notoriously collapse the wave function let's do a concrete example the double slit experiment walk us through that experiment exactly so if You observe an electron as it goes through the slits you will destroy the interference pattern okay so we know that a strong measurement uh the classic measurement in quantum mechanics spoils your ability to see what has happened what is actually happening but a weak measurement this is a very clever idea that if you couple the quantum system to another system and you only perform a strong measurement on the other system and the two systems are coupled very weakly then you then what you can do is repeat the quantum experiment in which you know the coupling to the other system is so weak it doesn't spoil that at all non-destructible non-destructive so the quantum system is happily doing all its interference and everything but then by repeating experiment thousands or millions of times and Performing real observations on the weekly couple system you can make predictions based on what the quantum particle was doing in the interim you know as it was going through the two slits or as it was doing something very quantum mechanical and tunneling Quantum tunneling or whatever so that's a very beautiful idea and part of the reason I like it is it's exactly what we have to do in cosmology we live in the universe we're not in a scattering Matrix we're in the middle of the thing you know we're after the big bang but we're we're before the end we're coupled to it right right we're a couple to it we're coupled very weakly I mean whatever we measure the Hubble constant to be does not the universe doesn't give a damn it's much bigger than us okay so there are all kinds of parallels and I firmly believe that understanding how to reconcile quantum physics with the universe requires us actually to understand quantum physics in these intermediate regimes and literally to ask you know what happens when a Quantum particle tunnels where is it um how would somebody trying to measure the particle as it is tunneling and measure it very weakly what would they tend to see um so it what's fascinating to me is that sort of these the work on Quantum foundations which until about 20 years ago was really philosophy in the worst sense it was you know going around in circles about um rather academic points without tests that field has changed because now we can do experiments we can attempt to build quantum computers uh you know Technologies reached a point where these sort of academic questions about what's really going on in quantum mechanics are becoming testable in experiment and I think we can learn a lot from them about how we deal with cosmology see almost all the Quantum physicists and I would say without except almost without exception all the string theorists for example who do cosmology do it in the following way you say given a classical universe namely a space-time Arena right just given that how do I propagate particles or Quantum Fields or whatever on top of that Arena and then see what happens okay now that is not that doesn't make any sense at all in quantum mechanics 6 you cannot couple consistently a classical object with a Quantum one that makes no sense people have understood that from the beginning of quantum mechanics either you're all classical or your old Quantum you can't mix the two now you know there's some approximations in which it looks very classical in some respects but if you want to do it properly you've got to quantize everything and that means space-time itself must be Quantum and that path integral formula I showed you tells you how to do that actually so John Wheeler knew how to do it which is that you've got to sum over all possible space times that connect you know a given um the universe at one moment of time let's say to the universe at a later moment of time it's a very difficult calculation not just practically but conceptually you know if somebody gave us the most powerful computer of all time we still wouldn't know how to do the calculation because we don't know exactly how to implement that interference formula and that's what I'm busy trying to figure out and I think it's possible but it needs more mathematical insights uh what I love about this is that the ingredients we which go in are actually very well established Einstein's theory of gravity quantum mechanics this notion of a path integral these are all kind of very solid Notions even if they aren't mathematically rigorous yet especially in the path integral and so by making them more rigorous uh I you know it's very tough work it's very mathematical work but um I'm really hopeful that we will gain insights and what I'm hoping in particular is we'll see how to resolve the big challenges in physics without adding more junk okay nature is telling us very clearly don't add junk okay and yeah and if we add junk we are falling into the oldest trap in science which is when am I when the data don't fit the model add a new parameter right that's what everyone does in financial mathematics economics you know you know modeling of all sorts and people have learned the lesson that a forecast made using a model where you just added something to fit the prior data you know it very often fails uh you you the model is only useful if it's predictive you know and those predictions are based on assumptions which are minimal um uh don't keep adding parameters and extra stuff so we've got to stop doing it it's an addiction it's an addiction in the field uh the there's vast numbers of papers which are doing that so it's quite hard to resist this right because what I'm doing implicitly is criticizing all my colleagues have written tens of thousands of papers with tens of thousands of new particles and parameters and I'm saying we've got to stop okay this is not leading us to new understanding and I'm afraid you know as as wonderful as inflation is and I'm I'm a big I fully acknowledge that inflation Theory drove helped to drive the observational efforts you know it was what whatever inflation model was being advocated you know was an inspiration in the sense that you could then try to shoot it down as an experimentalist and and that's really really important so I think inflation was extremely important to the field uh was an inspiration but doesn't need to be correct um what do you say to those people like I've had on David spurgle I've had um uh conversations with Will Kinney but his new book on the Multiverse effectively and they push back you know with all due respect and they'll say well how do you explain the large angular scale te correlation without inflation um how do you explain the uh the the not quite scale invariant you know uh spectral index how do you how do you explain the successes of forget about the Multiverse which Paul and I have talked about and Aegis and I have talked about links to those videos yeah but let's just focus on the successes of inflation so can you thank you thank you yeah so so I can I can and this is our new work so so it's a great question uh now let me just tell you how it works okay so the first the puzzle which everybody believes uh and you know Dave circle is a good friend and will Kinney too they have bought the inflationary explanation okay but the inflationary explanation comes with a bit of baggage you've got to assume an extra scalar field for which there is no observational evidence you've got to assume that field was displaced from its minimum and that it rolled very slowly downhill okay so you put in the initial conditions by hand you have to assume all kinds of things about the quantum state of that field and so on so it comes with a lot of baggage um and essentially it's a model you know contrived to fit the data I'm sorry Neil but it's just a again just a for the listeners that may not be watching we're all talking about uh uh some technical matter now that we'll show video on the YouTube channel but um but in particular couldn't one say the same thing about the Higgs it it comes with some initial value it it is you know the job of the theory is not to explain you know I always say when I took a biology class they don't start with you know how did life form on in the universe they start with here's DNA here's microbiology yeah in other words is it a problem for the theory that it has to come up with the initial condition like it has to instantiate itself does it have to be it from bit as wheeler would say I mean isn't that asking like I mean you could say the same thing about about no no there's a there's a there's a huge difference between the Higgs and inflation the Higgs was a mechanism to explain a known fact the the the weak interactions and um so that it's not just one fact there was an abundance of data yeah and what Higgs did with one hypothesis introducing a new admittedly introducing a new particle was to explain a vast array of data okay whereas with the with the inflation field you're introducing um well essentially as I think you said earlier inflation isn't really a theory it's a it's a collection of models so you're opening the door whereas the Higgs mechanism is really quite unique I mean it's tied down by the standard model and its symmetries that when you introduce this Higgs field you're extremely constrained in how you introduce it and essentially there's only one free parameter and that parameter turns into the particle mass and and as all the other observations of all the kind of side effects of the Higgs mechanism as they became more and more precise the prediction for the Higgs particle Mass became extremely uh narrow and so people are very nervous oh my God is it going to be ruled out and and you know as late as 2012 uh people were still worried it's going to be ruled out that seemed to me the most likely thing and then very last minute when that window was finally narrowed a little bump appeared and there it was so uh now inflation absolutely different you see inflation so the Higgs mechanism is explaining a wealth of complex processes okay uh involving particle physics all of which are measurable in accelerators and experiment the inflaton and inflation is explaining one actually two numbers one is the amplitude of these density variations as they come out of the Big Bang there's roughly one part and ten thousand that number is is being uh explained except a number isn't explained it's a free parameter and then secondly what is called a slight tilt that the fluctuations on the sky are ever so slightly larger on large scales than they are on small scales it's only a one percent effect um but um but you know it does seem to be there in the data so basically we've got uh two numbers to explain and the uh minimal inflation models essentially introduced two parameters to fit those two numbers they don't predict anything but they do fit that they are able to fit the data the problem is they also predict something else which are gravitational waves which you know very well and on that basis they are under severe pressure now um and so the the inflation models you know are way less constrained theoretically than the Higgs model ever was and um so then you you're forced to say well why do I favor one inflation model over another you know there's some notion of what's simpler uh but the simpler models are now wrong and uh so now inflation modelers are in the position of adjusting their model you know with with every new piece of data you know if you have to adjust the model by adding a new parameter you know you're going in the wrong direction so I would say inflation is you know at best A fitting model it because it's basically trying to fit these two numbers uh you know the Higgs mechanism is fitting a Million numbers measured in laboratory experiments and it's just totally different much more principle Theory and is fitting a vastly greater array of data so that encourages me to believe that instead of inflation there might be a much simpler explanation a much more principled explanation so let me try and give you a flavor of what I think it is and this is our res our recent paper which explains the flatness of the Universe on large scales just using thermodynamics gravity and quantum mechanics that's all okay so and I'll tell you how we did it yep I'm very excited about this and I think again you know the mathematics is crystal clear the assumptions are crystal clear if it may be right or wrong because there are assumptions but uh the explanation is absolutely unique so that there are still some puzzles about it uh there always are but um this could be the the definitive explanation uh with without any sort of uh bells and whistles so let let me explain our new explanation with an analogy okay because it is rather technical it's using Stephen Hawking's work on black holes which is very famous Stephen Hawking figured out what's called the entropy of a black hole and all we've done is import his method of calculation of entropy yeah of gravitating systems we've taken that calculation and applied it to the real Cosmos okay so we have calculated For the First Time The entropy of a realistic Cosmos with dark energy with radiation and with spatial curvature and we find that provided the universe is sufficiently big and I'll explain what I mean by big in a moment the most probable universe is flat okay and the answer is crystal clear so um if this explanation is correct no extra theoretical ingredients are needed right it's it stands on its own it relies on gravity and quantum mechanics quantum mechanics is important in thermodynamics because it allows you to it quantizes the states and it allows you to count how many states there are and our explanation is sympathy that the flat universe is the most probable uh if you allow the universe to take all of its possible States it's most likely going to turn out to be flat so what's the analogy well why is the earth flat and I'm showing here a picture of the Earth from space made by NASA and what you notice when you look at these pictures is the Earth is just this perfectly round marble okay smooth as anything perfectly round and smooth and what this means is that if we I've got a little circle showing Edinburgh if we live in Edinburgh and if we only travel you know uh 10 kilometers or 100 kilometers we don't need to worry about the curvature of the Earth because locally the universe the Earth is very flat okay so the flatness of the Earth is a consequence of several things one is the Earth is very big earth is made of about 10 to the 50 atoms okay if the Earth was any smaller you know and and it were round we would see the curvature of the earth um so the tent first of all you need to to know that the Earth is a big object secondly you need gravity gravity pulls all those atoms inwards and when it does so it makes the earth round but you have to have dissipation you know if a mountain collapses it doesn't rebound and uh you know whereas an elastic ball will vibrate the Earth doesn't do that you know once it falls inwards it stays inwards and the dissipation redistributes the energy the potential energy let's say in the mountain or in a ball that energy is redistributed into heat so uh there are vastly more ways of arranging the Earth and a given amount of energy where I put all that energy and just the the vibrations of the atoms and molecules into heat there's so much heat capacity in the Earth that you know if things fall on the earth and they make for example a sound wave that sound wave will just go into heat and all the energy that was in the object as it fell will will be redistributed into heat in the earth so once you unders and essentially this is entropy that while it may seem sort of surprising at first sight that the most probable Earth is round whereas a most random Earth you know would be very Jagged and spiky if I took 10 to the 50 atoms and treated them like Lego I'd get a very crazy geometry but in reality what happens is when you when you include gravity and dissipation then the most probable geometry for the Earth is actually spherical um because it you know we don't see it looking random because we're not looking at the vibrations of the molecules but all the vibrations of the molecule is extremely random there's a ton of entropy there and so um entropy favors around smooth Earth so it's a wonderful explanation because it doesn't require any new physics you don't require somebody to come and polish the Earth and make it round and smooth you know physics does that for you and I think Einstein said that anytime you use thermodynamics to explain something you know that explanation May last forever because uh the laws of probability are not about to change anytime soon and if uh you know they're just many more ways to make around Earth than there are to make a jagged Earth um you know it's very likely and whatever your laws of physics um uh the Earth is going to be round so um so I take inspiration by the way there's some new evidence in favor of this explanation involving um plankton in the oceans which is very beautiful so life actually had a role you know there are mountain ranges on the earth after all there's uh the Himalayas and the Andes and the Rockies turns out all these mountain ranges arose about two billion years ago and the reason they Rose was precisely because the friction of content between continental plates was reduced about two billion years ago you know so when two continental plates collided instead of just sort of grinding each other into dust and making something smooth they slid one above the other uh due to the um lubrication and the lubrication was was the carbon in the form of graphite created by the Plankton when life formed about two billion years ago so the origin of life preceded the formation of mountains sorry just aside there's no life elsewhere in the universe how could you I always say to get a solar panel you don't make a solar panel from a solar panel you don't make a transistor from a train you had to have pre-existing material raw materials and we got uh to communicate using Zoom today because at one point we're using whale oil to light lamps that then wrote down equations that built Factory in other words the the improbability of what you just described and by the way that Plankton only survived because the dinosaurs were too large to notice them and then the dinosaurs only got wiped out because I have to ask you just yes or no do you think there's you know intelligent life elsewhere in our galaxy I don't know I don't know but I don't want to dwell on it because I want to go oh no I I you know it's a wonderful question I don't know but I think the case is getting more and more interesting uh we've just discovered that Pluto is a lot more intricate than we expected uh there's there's uh a lot of ice and the ice is active there are volcanoes ice volcanoes on Pluto indicating that perhaps under the ice there is an ocean and you know having water is is certainly very helpful for uh formation of life so perhaps there's some primitive life on Pluto I I think it's absolutely fascinating oh it is yeah I I I really don't know I mean I guess my you know philosophically uh our human egos tend to encourage us to Think We're Alone uh and that makes us feel very important but uh on the other hand the people that believe in alien life feel like they're uh not not unimportant but that aliens would would want to visit us uh just the same but but also that yeah there's a privileged about uh us and that uh on the one hand on the other hand we shouldn't take ourselves uh so seriously because life is teeming throughout the Galaxy even though there's no evidence anyway I don't want to distract no no you know we'll solve the origin of Life another time my friend yeah you know actually it brings me on to something else I I'll come back to this but it's a very important Point how does life fit into the cosmos and I have a slide about that which won't answer the question of whether there is maybe we'll do a part two Neil because actually you brought up so much interesting stuff and I know your your time is limited and I want to uh complete but the other thing I want to talk about is where does forgive me if this is loony sounding but Consciousness in the wheelarian sense of it from this in the Universal how does it fit into the anti-universe Paradigm but I I don't want to talk about that now because I I really want you to keep going with what you're just talking about you later this summer and I also want to read your book yourself I'd be I'd be happy to do that uh in fact I was lucky enough to work at Princeton when wheeler was uh retired and John Wheeler used to come uh to all the physics department colloquia but he wasn't allowed to drive at that point because he was too old and so I used to drive him home wow and so John Wheeler I had a very young daughter at the time who was I think two or three and I brought John Wheeler home and um so uh I was trying to explain to her who John Wheeler was Freeman Dyson when he met my father oh yeah over dinner here these were incredible people and I think uh one of the joys of being in theoretical physics is to spend some time with them so I said job in the world Neil not just theoretical physics but but also to be a scientist exposed as you've been exposed on every concept depth Antarctica and and your work uh you know South Africa where I have yet to I've lectured on all six continents except for Africa I hope they go there somewhere but that you've met so many interesting people you've been involved with young people with um science in Africa and uh the anti-apartheid movement I'd love to talk to you about that so let's do a part two uh but later this summer no that's fine let's keep going with the with your uh anything else you want to talk about but uh but I know you have to go at about 15 20 minutes I gotta go babysit myself no problem I just want to tell you one thing about wheeler so he I said um my daughter says to me you know who who's John Wheeler and I said oh he's the person who believes that there are wormholes in the sky and so my daughter's answer was oh everybody knows that's wrong wormholes are in the ground [Laughter] in that black hole the word black hole and he also invented the word Wormhole and he was the first to think about such a kind of mind-boggling effects which people like me are trying to now kind of implement mathematically and and see if those ideas hold water but uh yeah amazing person so um yeah I want to come to this explanation for flatness um we have an explanation for the flatness of the universe which exactly parallels this explanation for the flatness of the Earth um it's not atoms that you need to count it's how many possible states are there for the entire material that makes up the universe okay it's because if you like gravitational atoms so imagine you're building a space-time out of something how many of those atoms are there okay and what I claim is that if there are many and by many I only mean let's say a thousand times more than we already know about because we already have seen you know a vast region of the universe so if there are only a thousand times more than what we've ever seen well I should say precisely I mean that the entropy is a thousand times more than what we've already seen um then um then the most probable universe is flat that's all it takes wow just as more atoms of the universe in the Earth make it flatter more degrees of freedom we say technically in dealing with gravity make it flatter so this is my audience that may not be familiar the uh astonishing thing in in Neil's famous you know kind of lingo about the curvature of the universe that's flat wherein there are an infinite number of real numbers that could be corresponding to the curvature being positive of the universe being a spherical positive curvature identically there's an infinite number of negative curvature universes where the curvature is negative but there's only one you know zero is a very exactly and uh and to explain it requires either an astonishing coincidence or a mechanism and what Neil's describing here is a mechanism forcing the universe no other choice to be flat exactly exactly right in the same sense as the Earth is locally flat that in a small neighborhood of the earth you see something locally flat I mean this work has convinced me that by the way I have to say that our calculations assume that the universe is finite not infinite it can be positively curved it can be negatively curved it can be an arbitrary size but it has to be finite to even talk about the number of states you have to assume it's finite and the result of this calculation convinces me whereas I didn't take the possibility seriously before it convinces me that the Universe could very well be finite after all um certainly if it's positively curved it would be a sphere a finite radius but if it's negatively curved it can also be finite it requires various Arrangements like mirrors in it to make it finite uh and such a universe providing it's larger than you know the region we see the most probable States will be flat so just show a little graph there's a graph from our new new paper it's about the gravitational entropy of the universe and so Hawking I won't describe the graph in detail just to say it exists it's a mathematically precise calculation the only assumptions of gravity and quantum mechanics and Hawking's way of calculating entropy and personally I think Hawking would have loved this calculation now what happened is so people people before us studied the Lambda Universe the empty Universe which only has dark energy that's what they could do mathematically and they call that the sitter space the set of space-time it's an empty Universe apart from the dark energy right and and mathematically it's rather easy to handle and you can calculate its entropy so there was this desitter entropy and then various people asked well what happens if I add some stuff inside this dark energy Universe like matter radiation what happens to the entropy and what they discovered is it goes down okay you the more stuff you put in it the smaller the entropy gets and eventually it hits zero and the reason it hits zero is that um it's possible to have a static Universe you see the dark energy is repulsive drives the universe apart as you add more and more radiation the radiation is gravitationally attractive and you can balance the two to make a static universe and and in fact this is Einstein's static Universe model that has zero entropy in in gravity um and and technically the reason for that is it has no Horizons it's just a static space it has no entropy that's not the universe we live in in fact none of the universes I've just described are the ones we live in we live in a universe which has more radiation than the Einstein static universe which came out of a big bang which is dominated by radiation so we succeeded recently in extending this calculation of gravitational entropy into the realistic regime where you've got lots of radiation and that radiation dominates you know decider space is is like a sort of hyperboloid it bounces as you go back in the past it bounces and re-expands um the universe we live in didn't do that there was so much radiation that it just collapsed into as you go back in time it collapses into a big bang singularity so um sorry their dogs barking don't like singularities we succeeded in doing this calculation for a realistic Universe including lots of radiation and when we do that we find that you see one is the magic number if the gravitational entropy equals the sitter entropy so we know what the dark energy is today and so we know what the corresponding entropy is of a decita universe if our universe has more than a thousand times the entropy of that the sitter universe then it it turns and because entropy goes like volume it essentially means it's 10 times bigger than what we see the radius has to be 10 times bigger than what we see then it turns out that the curvature the most probable Universe has curvature nearly zero and that's what the blue line on this curve shows so I I claim that you know this calculation of gravitational entropy indicates that the vastly most probable universe is actually spatially flat um if that if this is the case then all of us have been on the wrong track for the last 40 years and uh uh in fact you know a very simple uh explanation along the same lines of why the Earth is flat was staring Us in the face it's due to gravity and how gravity is reconciled with thermodynamics and also it would reconcile this great puzzle that was at least brought to my attention by Sir Roger Penrose of why the entropy was so low in the early universe and and yeah there's your family there's this famous diagram yeah you want to explain yeah let me let me tell you a little bit about Roger Penrose Roger Penrose is uh absolutely inspiring figure in the field of gravity uh he's the one who um discovered the mathematical properties of black holes and who inspired Hawking um to do the same for cosmology and prove that uh classically the universe began in a big bang Singularity so Roger Benner is just a legend he's also one of the nicest people you could meet he's a four-time guest on this podcast so I know I know he features that very it's the top of his CV there's you know Nobel Prize right so yeah Roger interviewed me for a PhD place and I unfortunately only did physics as an undergrad I didn't do mathematics and so he interviewed me in Oxford and he said um he kind of looked down his nose at me and said um what what what problem do you want to work on I mean you're just a bloody physicist you don't know anything about mathematics and so I I rather um arrogantly or forthrightly said what's the hardest problem in the in the subject and he said oh it's describing massive particles and so I said oh great that's what I want to work on and he sort of looked at me like I've worked on this for 20 years and haven't gotten anywhere so who the hell are you so he didn't he didn't offer me a place but actually it was a good thing because the problems he was working on were actually very very hard and wouldn't be good for a PhD student anyway but he's an amazing person he's a very outspoken critic of inflation and his argument is is shown in this picture he he draws the most beautiful pictures too of mathematical ideas and and also just uh his father was an artist his father was a great artist oh I didn't know that aha didn't know that so uh well he his many talents um and so this shows the puzzling logical geometry of the universe so you know Einstein's theory as you said allows space to be curved and wiggled and and to take any shape um and uh and yet it doesn't you know the geometry of the Universe on large scales today is just what people taught in ancient Greece you know Euclid taught uh geometry the axioms of geometry and three-dimensional geometry you've got X Y and Z and it's exactly what you learn in Primary School uh that is the geometry of space in the universe why well what a mystery I mean why did we need Einstein if the universe you know chose this ridiculously ridiculous euclidean geometry such a trivial and simple thing with no curvature or anything so Roger puts it in this beautiful picture he has the Creator uh you know deciding to start the universe in this ridiculously special geometry um which doesn't need Einstein at all to understand um why is the universe so peculiar um and so Penrose made the argument that if you cut if you do the calculation of thermodynamics Allah Hawking you again used Hawking's idea of gravitational entropy he guesstimated you know what the what was the probability of a universe so so special and flat uh as ours um now the what he had done in in that guesstimate is not say anything about the Big Bang okay basically his argument that was that the most probable Universe would be a giant black hole which just contained everything that we see uh and yes he got used hulking's formula for the black hole and he basically argued on General grounds why didn't the universe just form form a giant black hole that has so many possible states such high entropy that's what it would be but we're clearly not living in a black hole so that was his Paradox what we've done is we actually Implement very precise mathematical condition at the Big Bang this perfect mirror as I said it's this reflecting boundary condition at the big bang that we see ourselves in a sense through the big bang and we implemented that and then we used that to calculate the entropy and it turns out that our reflection symmetry the CPT symmetry is what excludes there being a one huge black hole that doesn't satisfy this reflection symmetry and um could you have multiple like his prime or his error bonds or his uh Hawking points could you have multiple black tiny black holes or is it precluding black holes in general from Permian this this boundary condition precludes any black holes at the Big Bang there's a mathematical statement that it's what's called a conformal zero the Big Bang is a conformal zero it means that spaces shrunk to a point and the size if you like of the universe the scale factor um has a zero which is analytic and that means mathematically nice so the scale factor shrinks to zero but the geometry which the scale factor is multiplying is uh what we call regular namely it doesn't have any um divergences at the Big Bang itself and that alone that alone is enough to rule out big bang it'll rule out black holes at the Big Bang so the black holes that formed formed later they formed subsequently and and for that reason there are no very big black holes because you know they formed uh from sort of small sizes upwards uh our initial condition excludes there being a big black hole and and then when we calculate the gravitational entropy we're not calculating the entry of a big big black hole we're calculating other eight other Cosmos and so um so yeah it's interesting I gave a talk to Roger recently and halfway through the talk he said oh but you're not talking about a cyclic Universe anymore no and and I said no I'm not um what I'm doing is actually implementing your old ideas from the 1970s and 80s because he had this idea called the vile curvature hypothesis which is basically what I just said this conformal zero he was trying to explain why the cosmos was simple he didn't explain why it was flat but he was trying to explain why it it wasn't crazier in in the Big Bang and he made this hypothesis I said no I'm implementing your old idea um which you know you gave up on some time ago and he switched to cyclic yes okay but now I'm switching to his uh previous idea and um we'll see yeah very interesting yeah we'll have that's the luxury of theorists we can switch sides and uh you know Hawking did according to Sir Roger um so Neil we're coming up on two hours now uh I'd love to indulge your uh forbearance to ask you uh three questions that I ask all my guests uh and then I would like to further solicit for Barons and ask you to come back on the show uh fourth with after uh I digest your your second book or your uh the book uh I haven't yet read of yours so would you would you feel comfortable uh answering my existential questions courtesy okay great the first question uh these are my so-called thrilling three questions uh but the first one has to do with your own personal Horizon so if you want to stop sharing the screen we'll take off or actually I can I can shrink sir Roger to a to a conference okay I shrunk him to a singularity anyway um so the very first question I like to ask involves your legacy uh both uh both ideologically and and sort of wisdom and that has to do with this concept of and what's called an ethical will [Music] uh what what sorts of wisdom not monetary not Material uh bequeathment would you like to leave the world with when you spring forth the Mortal coil as The Bard said at age 120 in the biblical tradition what wisdom one piece of wisdom would you would you like to leave the the universe with gosh that's a tough question um yeah I I think it's an appreciation and this is what I like to share with everyone it's an appreciate it's a feeling I've had it's just a feeling which I've had ever since I was a child that um that the universe is is just extraordinary and our appreciation of it uh gives us more riches than anything else and and that's the wisdom that actually the wisdom is in nature that's my guiding guiding philosophy I think uh nature keeps us you know um keeps us on the right path and and but so take what the recent discoveries right the universe has turned out to be surprisingly simple uh the Higgs was found nothing else was found no Multiverse in the sky all right it's Simplicity itself and are we able to learn from that I literally feel that the universe is our guide that's the role it plays for humankind and it has if you think about it when people you know in in the Stone Age you know look up at the sky and they thought well you know that's amazing and so it lifts you beyond yourself it has an unimaginable sort of beauty grandeur that comes from symmetry it's not chaos right the universe is the furthest thing you can imagine from chaos that's in a sense why and and this matters not a single thing scientifically but this is why I don't really like the idea of uh a chaotic Multiverse you know I can see why some people find it appealing but for me it's the opposite uh that the universe is a guide it's uh it's it it shows us I mean I think about the history of physics you know how did Newton Law learn the laws of motion it wasn't on Earth it was by watching the planet by taking data from the planets he didn't he did the easy work he just did the math other people took the observation so you know time and again and again and likewise with Maxwell you know Maxwell always gave credit to Faraday Faraday discovered the laws of electricity and magnetism uh plus some other people but Faraday probably most coherently experimental and experimentally and Maxwell just had to write down the math which described those laws and Maxwell gave all the credit to Faraday now what he was doing is not so much being kind to experimentalist he was saying nature tells us how it works we just have to listen okay and that is the job of a theorist to listen and I don't the the criticism I have of my own field and my own earlier work is we weren't listening you know we were so full of ourselves we said oh we'll come along and introduce an extra Dimension and brains and all kinds of uh phenomenal imaginary phenomena you know but and to be fair to us we didn't have that much data you know now we have tons of data and it's all going in this direction of extreme Simplicity and economy and so I think any theorist worth their salt should be forced now to reconsider and say you know maybe my model was just too complicated very good very good okay so the next question on my topic now goes uh maybe further into the future Sir Arthur Clark said any sufficiently advanced technology is indistinguishable from Magic in his movie 2001 A Space Odyssey we see these apes and they they come upon this monolith and we don't know what it is it could be a time capsule it could be a uh it could be a warning who knows it could be some technology some magical technology uh I want to ask you kind of you know taking off from where Feynman said uh the most the most um most important information filled statement in the fewest words is the so-called Atomic hypothesis I want to ask you if you could update Feynman or give your own spin on Feynman what kind of magical statement could we use to brag about what physicist or Humanity has learned it could be human it could be something not related to your job but what contains the most information that human beings should rightfully put into a billion year long time capsule and let aliens know how proud We were of it some billion years hence [Music] so we haven't yet it but I think um I honestly feel that reconciling quantum mechanics with gravity will will be that something the reason why it it's so interesting and it actually relates to particles going backwards in time because particles what are particles after all we think they are what we call World lines you know a world line tells you where a particle is in space and time but if you think you take the big picture and just look at kind of all of space and all of time what's a particle well it's just a curve in space time and that immediately is telling you that geometry is somehow gets reconciled with quantum mechanics so quantum mechanics is making things spread everywhere explore everything that's all these phases I was talking about you know the quantum mechanics is incredibly exploratory and indefinite geometry is the opposite it's extremely definite I know exactly where the particle is at every moment of time so these are opposites and when we try to link gravity to Quantum Mechanics we've got to understand how these things reconciled uh I think they can be it's extraordinarily difficult when it is uh we will we will truly be sort of uniting opposites quantum mechanics there's the uncertainty principle so if you say where something is now or what geometry does the universe have now inevitably there's something you know nothing about which is in the case of the University how fast is it expanding you know if I know exactly what the geometry is now then I cannot know anything about how fast it's expanding according to Quantum Mechanics so the only way to know anything is you say well I know approximately this and approximately that um so you can see there's a huge tension between even the notion of geometry and uh the notion of Quant and the uncertainty principle in quantum mechanics so that I think is we've got so many Clues you see this is not Pie in the Sky we know how particles work we know what they do in colliders we know Quantum field Theory Works to very high Precision what we don't yet have is a sort of geometrical picture of exactly what the particles are doing and what that even means during one of these processes and if we gain such a understanding mathematical understanding precise understanding we're going to have to do the same thing for the universe and our place in the universe wow um so so yeah even though quantum gravity may sound uh very Arcane and um you know just the kind of last uh the dot of the eye in theoretical physics it isn't it's much more than that it's actually understanding the whole thing it's reconciling these two opposites um and that makes it you know very very challenging but I think if we do succeed in reconciling these opposites you know that will be the crowning achievement of of physics wow great okay third question um I'm actually gonna ask you four again you've been so generous I I hope you'll continue and won't slam shot the laptop on me but the third uh statement of Sir Arthur was when a distinguished but elderly scientist I'm not calling either one of us elderly but when it's distinguished but elderly scientist says something is possible they're most certainly right when they say something is impossible they are very probably wrong I want to ask you Neil have you changed your mind on anything recently uh have you been wrong about anything [Music] foreign I've been wrong multiple times and I think it's been very good for me um I was um I've always been a skeptic about inflation it always looked to me too many too many artificial ingredients in the models but so what I did I'm trying to be constructive is to develop alternative mechanisms which would explain structure in the universe so I worked on what seemed to be a very appealing idea at the time which was based on Grand unified theories which is an attempt to go beyond the standard model that is now kind of fallen out of fashion and these theories predicted as structures called Cosmic defects cosmic strings and I what fascinated me about that idea is it it was very predictive it explained that there were these objects swishing around in the early Universe explained how they formed out of fundamental physics and then they switched around and they stirred up the matter and that would end up making galaxies so it was a very principled and very predictive Theory and I decided to you know devote uh more time than I should have to working out all of its predictions which I did and then the experiments came along and they proved me and the theory utterly wrong um and yes it was disappointing uh I think for about six months afterwards I felt oh God I wish it had been right but um but actually with hindsight it was a really good thing that happened to me because it made me uh even more of a natural skeptic that and even more I believe that a theorist job is to come up with testable you know precise ideas which challenge experimentalists to go after them and ideally to try to prove them wrong right right your theory only succeeds to the extent the experimenters have failed so far to prove you wrong and uh so a theorist job is really a provocateur I mean that's what we should be and if our ideas are any good at all they serve a purpose of getting people to test them against nature and um so yeah I I I have been proven wrong I think it was great that I have uh I really pity other theorists who work on Frameworks and paradigms which are not provable wrong because they're just condemned to spend the rest of their days recycling the same old ideas and never really knowing if they're true right my uh one of my mentors a theoretician named Alexander pulmonary you probably remember the name I know him yes yeah and he is a Queen Mary uh at College he used to say zeldovic would tell him when he was doing something trite or repetitive he said and I guess it's more poetic in Russian but he would say you are like somebody who eats food someone else has already eaten which uh that wasn't my favorite my favorite zeldovic quote was uh when I would try to do too much Alex would say zeldovic would tell you nine women cannot have baby in one month uh so that was it all right last question for you today Neil you've been so generous so gracious speaking of impossible Sir Arthur C Clarke's third law says the only way of discovering discovering the limits of the possible is to venture a little way past them into the impossible that's the origin of the podcast name as I am the associate director of the Arthur C Clarke Center for human imagination at UC San Diego um among other things that I'm involved with but accordingly I want to ask you what mysterious aspect of life it doesn't have to be science of Life perplexed you as a 20 year old a 30 year old and what advice would you give to that young man to give him the courage to do as you've done to go into the impossible [Music] right uh I think and it may sound strange from a physicist but I think the most fascinating thing in the universe is life um and the way it's organized uh when I was young in my um uh late teens uh undergraduates I wanted to go into biology and do mathematical biology and understand what is the law that governs life that tells you that life will emerge um we still are none the wiser I mean but it's still the most fascinating question so I I think what I I think what seems impossible now is to make a predictive theory of life uh now maybe even predictions aren't the right language for dealing with life but somehow to gain an insight into what life is um i s you know we know kind of the constraints life operates under um but we don't have any idea of we have some glimpses maybe of how decisions are made um but but you know there's a very sort of fundamental I've talked about entropy you know life violates the the this second law of physics which is never going to change that uh only things that happen are ones which increase energy and life sort of violates that by using energy to deliberate to to actively um counteract the growth of it uh of entropy and to build ordered structures and so I think it's absolutely uh this day this dilemma uh of what's driving life you know and where is it taking it and can we understand that in any way um I think that that's the impossible so just as an example I have an undergraduate with me who in Edinburgh came to me um six months ago and he's been reading all kinds of crazy uh books he's actually doing engineering physics but he read David Deutsch's book on something about impossibility I I um yeah something like that it's an absolutely beautiful book which I highly recommend and um and we've been discovered discussing you know the general question of the emergence of complexity in the universe the universe is extremely simple on small scales right there's the Higgs and their laws of particle physics and that's it no evidence for anything else and then on large scales utterly simple too but in between it's this horrible complicated mess and if we think in a bigger picture where are we going where is AI going to go where is humankind going to travel into space explore the universe change the universe you know so there's this enormous scope for complexity in the middle while there's extreme simplicity at both ends of the spectrum why uh or how do you attempt to model a system like that which is complicate complex in the middle and extremely simple at the two ends small scales and very large scales and uh anyway so he's uh he's an undergrad and you know if and I am telling him uh I'm encouraging him to approach these impossibly difficult questions I'm honest with him you know your chances of actually making progress are tiny um but it's incredible fun as it is and this has been incredible fun for me and I hope we will be able to do a part two Neil this has been so great we're talking with Neil Turok I've known and been inspired by for decades now um he's still so young and exuberant I can't believe you're an Emeritus professor of perimeter institutes the least director there but you're now the inaugural Higgs Professor chair at the University of Edinburgh Neil it's been such a delight I I thank you for staying up late or into the afternoon I thank your dog for being very well behaved and I hope we welcome a part two where we can get into Consciousness the brain origin of life and um and a little bit maybe of commentary on your friends sir Roger Penrose Anna Aegis Paul steinhardt on their bouncing models and and Contra distinction with your uh CPT and very for now I want to thank you and bid you a good night thanks for the lovely questions thanks a lot thank you [Music] thank you

Channel: Dr Brian Keating

Views: 271,892

Keywords: Dr Brian Keating, into the impossible, brian keating, Big Bang, Theory of Everything, Theories of Everything, Experimental cosmology, Brain Keating, Into the impossible Podcast, Science Podcast, Scientific interviews, exploring the universe, Universe Facts, Scientific podcasts, Universe exploration, Cosmology podcast, neil turok, theoretical physics, higgs, Turok, neil turok the astonishing simplicity of everything, neil turok cyclic universe, neil turok general relativity

Id: Dt5cFLN65fI

Length: 133min 56sec (8036 seconds)

Published: Sun Oct 02 2022