Peter Woit: Theories of Everything & Why String Theory is Not Even Wrong | Lex Fridman Podcast #246

the following is a conversation with. peter white a theoretical physicist at. columbia outspoken critical string. theory and the author of the popular. physics and mathematics blog called not. even wrong. this is the lex friedman podcast to. support it please check out our sponsors. in the description and now here's my. conversation with peter white. you're both a physicist and a. mathematician. so let me ask what is the difference. between physics and mathematics.

well there's kind of a conventional. understanding of the subject that. they're. two you know quite different things so. that mathematics is about you know. making. rigorous statements about. these abstract you know abstract things. things of mathematics and and proving. them rigorously and physics is about you. know doing experiments and. testing various models and that but i. think the more interesting thing is that. the. there's a. yeah there's a wide variety of what.

people do as mathematics what they do is. physics and there's a significant. overlap and that i think is actually the. much much very very interesting area and. if you go back kind of far enough to in. in in history and look at figures like. newton or something i mean there it at. that point you can't really tell you. know was newton a physicist or a. mathematician yeah mathematicians will. tell you as a mathematician the. physicist will tell you as a physicist. but he would say he's a philosopher yeah. yeah. that's that's interesting but uh yeah. anyway there there was kind of no such.

distinction then it's more of a modern. thing and. but anyway i think these days there's a. very interesting space in between the. two so in the story of the 20th century. and the early 21st century what is the. overlap between mathematics and physics. would you say. well i think. it's actually become very very. complicated i think it's really. interesting to see a lot of what my. colleagues and. math department are doing they. most of what they're doing they're doing. all sorts of different things but um. most of them have some kind of overlap.

with physics or other. so i mean i'm personally interested in. one spec one particular aspect of this. overlap which i think. has a lot to do with the most. fundamental ideas about physics and. about. mathematics but um. there's just. you you kind of see this this uh. really really everywhere at this point. which particular overlap are you looking. at group theory yeah so the um. at least. what the way it seems to me that if you. look at physics and look at the our most. successful um. laws of fundamental physics.

they're. really you know they have a certain kind. of mathematical structure it's based. upon. certain kind of mathematical objects and. geometry connections and curvature the. spinners the rock equation. and uh that. these this very deep mathematics. provides kind of a unifying. set of meth of ways of thinking that. allow you to to make a unified theory of. physics but the interesting thing is. that if you go to mathematics and look. at what's been going on in mathematics.

the last. 1500 years and even especially recently. there's a. similarly some kind of unifying ideas. which bring together different areas of. mathematics and which have been. especially powerful in number theory. recently and. there's a book for instance by um. edward frankel about love and math and. oh yeah that book is great i recommend. it highly it's uh partially accessible. but there's a nice audio book. that i had listened to while. running an exceptionally long distance.

like across the san francisco. bridge. and uh there's something magic about the. way he writes about it but some of the. group theory in there is a little bit. difficult. uh yeah it's a problem with any of these. things to kind of really say what's. going on is. and make it accessible is very hard. he in this book and elsewhere i think. you know takes the attitude that kinds. of mathematics he's interested in and. that he's talking about are provide kind. of a grand unified theory of mathematics. they um they bring together geometry and.

number theory and. representation theory a lot of different. ideas. in a really. unexpected way. but i think to me the most fascinating. thing is if you look at. the kind of grand unified theory of. mathematics he's talking about and you. look at the physicists kind of ideas. about unification it's more or less the. same mathematical objects are appearing. in both. so it's this um i think there's a really. we're seeing a really strong indication. that you know the deepest. ideas that we're discovering about. physics and some of the deepest ideas.

that mathematicians are learning about. are really are you know intimately. connected. is there something like if i was five. years old you were trying to explain. this to me is there ways to try to sneak. up to the to to what this unified world. of mathematics looks like you said. number theory he said geometry. words like topology. what does this universe begin to look. like are these what should we imagine in. our mind is it a. a three-dimensional surface.

and we're trying to say something about. it. is it uh. triangles and squares and cubes like. what what are we supposed to imagine our. minds is this natural number what what's. a good thing to try to. for people that. don't know any of these tools except. maybe some basic calculus and geometry. from high school that they should keep. in their minds. as to the unified world of mathematics. that also. allows us to explore the unified world. of physics. the i mean what i.

find kind of remarkable about this is. the way in which. these we've discovered these ideas but. they're they're actually quite alien to. our everyday understanding you know we. grow up in this three spatial. dimensional world and we have. intimate understanding of certain kinds. of geometry and certain kinds of things. but um these things that we've. discovered in both math and physics are. that they're not at all. close have any obvious connection to. kind of human everyday experience that.

they're really quite different and i can. say some of my initial fascination with. this when i was. young and starting to learn about it was. actually. exactly this um. this kind of arcane nature of these. things it was a little bit like being. being told well there are these kind of. some semi-mystical experience that you. can acquire by a long study and whatever. except. that that it was actually true there's. actually evidence that this actually. works. so you know i'm a little bit wary of.

trying to give people. and that kind of thing because i think. it's mostly misleading but one thing to. say is that you know that geometry is a. large. part of it and um. maybe one interesting thing to say very. that's about more recent some of the. most recent ideas is that it um when we. think about the geometry of our space. and time it's kind of three spatial and. one. time dimension it's a um. physics is in some sense about. something as kind of four dimensional in. a way and that a really interesting.

thing about um some of the recent. developments and number theory have been. to realize that the um. these ideas that we were looking at you. know naturally fit into a context where. your theory is for is kind of four. dimensional. so. so so so i mean geometry is a big part. of this and we know a lot and feel a lot. about you know two one two three. dimensional geometry so wait a minute so. we can at least rely. on the four dimensions of space and time.

and say that we can get pretty far by. working that in those four dimensions i. thought you were going to scare me that. we're going to have to go to many many. many many more dimensions than that. my point of view which is which goes. against a lot of these ideas about. unification is that no this is really. everything we do we know about really is. about four dimensions that um. and and that you can actually understand. a lot of these structures that we've. been seeing in fundamental physics and. in. in number theory just in terms of.

four dimensions that it's kind of. it's in some sense i would claim. has been a really um. has been kind of a mistake that. physicists have made and. for decades and decades to try to. to try to go to higher dimensions to try. to formulate a theory in higher. dimensions and then then you're stuck. with. the problem how do you get rid of all. these extra dimensions that you've. created and. because we only ever see anything. important. that kind of thing leads us astray you. think so so creating all these extra.

dimensions just to get to give yourself. extra degrees of freedom. yeah it's not i mean isn't that the. process of mathematics is to create. all these trajectories for yourself but. eventually you have to end up at the uh. like a final place but it's okay to. it's okay to sort of um. create abstract objects on your path to. uh proving something. yeah so yeah certainly but and from from. mathematicians point of view. i mean.

the kinds of mathematicians also are. very different than physicists and that. we like to develop very general theories. we like to if we have an idea we want to. um see what's the greatest generality in. which you can talk about it so from the. point of view of most of the ways. geometry is formulated um. by mathematicians it really doesn't. matter it works in any dimension we can. do. one two three four any any number. there's no particular. for most of geometry there's no. particular special thing but for. but um. and anyway but but what physicists have.

have been trying to do over the years is. try to understand. these fundamental theories in a. geometrical way and it's very tempting. to kind of just. start bringing in. extra dimensions. and using them to explain the structure. but. um. typically this this attempt kind of. founders because you just don't know. you end up not being able to explain why. we only see four and anyway. it is nice in the space of physics that.

uh like if you look at from o's last. theorem. it's much easier to prove that there's. no solution for n equals three. than it is for the general case. and and so i guess that's the nice. benefit of being a physicist is you. don't have to worry about the general. case because we live in a universe with. n equals. four in this case. yeah the physiophysicists are very. interested in. saying something about specific examples. and. i find that interesting even when i'm.

trying to do things in mathematics and. i'm trying even teaching courses and. mathematics students i find that. i'm teaching them in a different way. than um most mathematicians because i'm. very often very focused on examples on. what's. what's kind of the crucial example that. shows how this um. this powerful new mathematical technique. how it works and why you would want to. to do it. and i'm less interested in kind of. you know proving a precise theorem about.

exactly when it's going to work and when. it's not going to work do you think. about really simple examples like uh. both for teaching and when you. try to solve a difficult problem are you. do construct like the simplest possible. examples that captures the fundamentals. of the problem and try to solve it yeah. yeah exactly that's often. a really fruitful way to if you've got. some idea to you just kind of try to. boil it down to what's the simplest. situation in which this kind of thing is. going to happen and then try to really. understand that and understand that and.

that that is almost always a really good. way to get insight into do you work with. uh paper and pen or like for example for. me. coming from the programming side if you. if i look at a model if i look at some. kind of mathematical object. i like to mess around with it sort of. numerically i just visualize different. parts of it visualize however i can so. most of the work is like with neural. networks for example as you try to play. with the simplest possible example and. just to build up intuition by.

um you know. any kind of object has a bunch of. variables in it. you start to mess around with them in. different ways and visualize in. different ways to start to build. intuition. or do you go to einstein route and just. imagine. like. everything inside your mind and sort of. build like thought experiments and then. work purely on paper and pen. well the problem with this kind of. stuff. i'm interested in is it you you rarely.

can kind of. it's really something that is really. kind of. or even the simplest example. you know it can is you can kind of see. what's going on by it looking at. something happening in three dimensions. there's there's generally this the. structures involved are um. either they're more abstract or if you. try to kind of embed them in some kind. of space and where you could um. manipulate them in some kind of. geometrical way it's going to be a much. higher dimensional space so even simple. examples. the embedding them into.

three-dimensional space you're losing a. lot yeah or but to capture what your. what you're trying to understand about. them you have to go to four or more. dimensions so it starts to get to be. hard to. i mean you can. train yourself to try it as much as to. kind of. think about things in your mind and you. know i often use pad and paper and often. if i'm. in my office often use the blackboard. um and you are kind of drawing things. but they're really kind of more abstract. representations of how.

things are supposed to fit together and. they're not really. unfortunately not just kind of really. living in three dimensions where you can. are we supposed to be sad or excited by. the fact that our human minds can't. fully comprehend the kind of mathematics. you're talking about i i mean. what do we make of that i mean to me. that makes me quite sad it makes me it. makes it seem like there's a giant. mystery out there that we'll never truly. get to experience. directly it is kind of sad you know how.

difficult this is i mean or i would put. it a different way that um. you know most questions that people have. about this kind of thing. you know you couldn't you can give them. a really a true answer and really. understand it but. the problem is is one more of um of time. it's like. yes you know i could explain to you how. this works but you have to be willing to. sit down with me and you know work at. this repeatedly for. you know for hours and days and weeks. and you you mean it's just going to take.

that long for your mind to really wrap. itself around what's going on and um. and that so that does make things an. inaccessible which is uh. which is sad but it again i mean it's. just kind of part of life that we all. have a limited amount of time and we. have to decide what we're going to. what we're going to spend our time doing. speaking of a limited amount of time we. only have a few hours maybe a few days. together here on this podcast. let me ask you the question. of um.

amongst many of the ideas that you work. on. in mathematics and physics what to use. the most beautiful idea or one of the. most beautiful ideas maybe a surprising. idea and once again unfortunately the. way life works we only have a limited. time together try to convey such an idea. okay well actually let me just tell you. something which i i'm tempted to kind of. start trying to explain what i think is. this most powerful idea that brings. together math and physics ideas about. groups and representations and how it.

fits quantum mechanics and but in some. sense i wrote a whole textbook about. that and. i don't think we really have time to get. very far into it so well can i actually. on a small tangent you did write a paper. towards the grant unified theory. mathematics and physics. um maybe you could step there first what. is the key idea in that paper well i. think we've kind of gone over that i. think that the key idea is what we were. talking about earlier that um. that just kind of a claim that if you. look and see what's that have been. successful ideas in unification in.

physics and over the last. um 50 years or so and what. has been happening in mathematics and. the kind of thing that. frankl's book is about that these are. very much the same kind of mathematics. and so it's kind of an argument that. there really. is. you shouldn't be looking to unify just. math or just. fundamental physics but taking. inspiration for looking for new ideas in. fundamental physics that they are going. to be in the same direction of. getting deeper into mathematics and.

looking for more inspiration mathematics. from. these successful ideas about fundamental. physics. could you put words to sort of the. disciplines we're trying to unify so you. said number theory are we literally. talking about all the major fields of. mathematics so it's like the number. theory geometry. uh so the differential geometry topology. like yeah. so the i mean one one name for this. that this is acquired in in mathematics. is the so-called language program. and uh so this started out in.

mathematics it's that. you know robert langland's kind of. realized that a lot of what people were. doing and um. that was starting to be really. successful in number theory in the. 60s and so that this actually. was. anyway that this could be could be. thought of in terms of um. these ideas about symmetry in groups and. representations. and and. in a way that was also close to some. ideas about about geometry and um then.

it more later on in the 80s and 90s. there was something called um. geometric language that people realize. that you could take what people have. been doing in number theory in language. and and and get re just forget about the. number theory and ask what is this. telling you about geometry and you get a. whole some new insights into certain. kinds of geometry that way. so it's anyway that that's kind of the. name for this area is langlins and. geometric language. and just recently in the last few months. there's been um.

there's kind of a really major paper. that uh appeared by uh peter schultz and. laurel farg where they. you know made you know some serious. advance and trying to understand. a very much. kind of a local problem of what happens. in number theory near a certain prime. number and they. turn this into a problem of exactly the. the kind the geometric. language people had been doing these. kind of pure a pure geometry problem and. they. found.

by generalizing the mathematics they. could actually reformulate it in that. way and it worked perfectly well. one of the things that makes me sad. is you know i'm um pretty knowledgeable. person and then. uh what is it at least i'm in the. neighborhood of like theoretical. computer science right. and it's still way out of my reach and. so many people talk about like language. for example is one of the most brilliant. people in mathematics and just really. admires work. and i can't.

it's like almost i can't hear the music. that he composed and it makes me sad. yeah well i mean i i think that. unfortunately it's not just. you as i think even most mathematicians. have no really don't actually understand. this about them in the the group of. people who really understand. all these ideas and so for instance this. paper of. schultz and farg that i was talking. about the number of people who really. actually understand how that works is. anyway one. very very small and so it's uh so i i.

think even. you find if you talk to mathematicians. and physicists even they will often feel. that you know there's this really. interesting sounding stuff going on and. which i should be able to understand. it's kind of in my own field i have a. phd in but it still seems it's pretty. clearly far beyond me right now. well if we can step into the back to the. question of beauty uh. is there an idea that maybe is a little. bit smaller. that you find beautiful in the space of. mathematics or physics.

there's an idea that you know i kind of. went got a physics phd and spent a lot. of time learning about mathematics and i. guess. it was embarrassing and i hadn't really. actually understood this very simple. idea. um until and kind of learned it when i. actually started teaching math classes. which. is maybe that there there may be. there's a simple way to explain kind of. the fundamental way in which algebra and. geometry are connected so you normally. think of geometry is about these spaces.

and these points and. and you think of algebra is this very. abstract thing about with these. abstract objects that satisfy certain. kinds of relations you can multiply them. and add them and. do stuff but it's it's completely. abstract and there's nothing geometric. about it but the um. the kind of really. fundamental idea is that unifies algebra. and geometry is to is to realize is to. think when whenever anybody gives you. what you call an algebra some abstract.

thing of things that you can multiply. and add. that you should ask yourself. is that algebra the space of functions. on some geometry. so one of the most surprising examples. of this for instance is a. i mean a standard kind of. thing that seems to have nothing to do. with geometry is the um. is the. the integers so then they're you can you. can multiply them and add them it's. it's an algebra but the um. it has seems to have nothing to do with.

geometry but what you can it turns out. but if you ask yourself this question. and ask you know is are integers can you. think if somebody gives you an integer. can you think of it as a function on. some space. on some geometry and it turns out that. yes you can and the space is the space. of prime numbers. and so what you do is you just if. somebody gives you an integer. you can make a function on the prime. numbers by just. you know at each prime number taking. that. that integer modulo that prime so if uh. if you say i don't know if you get given.

10. you know 10 and you ask what is its. value at 2 well it's. it's 5 times 2 so mod 2 it's zero so it. has zero one what what is what is this. value at three. well it's nine plus one so it's it's one. mod three. so it's about it's zero at two it's one. at three and you can kind of keep going. and so. this is really kind of a. truly fundamental idea it's at the basis. of what's called algebraic geometry and. it just links these two parts of.

mathematics that look completely. different and it's just an incredibly. powerful idea and so much of mathematics. emerges from this kind of. simple relation so uh you're talking. about mapping from one discrete space to. another to another so. um. for a second i thought perhaps. uh mapping like a continuous space of. discrete space like functions over a. continuous space. because yeah well you can i mean you can. take if somebody gives you a space. you can ask you can say well let's let's.

and this is also this is part of the. same idea the part of the same idea is. that if you try and do geometry and. somebody tells you here's a space. that what you should do is you said wait. say wait wait a minute maybe i should be. trying to solve this using algebra and. so if i do that the way to start is you. give me the space. i start to think about the functions of. the space okay so for to each point in. the space i associate. a number i can take different kinds of. functions and different kinds of values. but but basically functions on a space.

so. what this. insight is telling you is that if you're. a geometer often the way to to to work. is to trans change your problem into. algebra by changing your space stop. thinking about your space and the points. in it and think about the functions on. it got it and if you're if you're an. algebraic and you and you've got these. abstract algebraic gadgets that you're. multiplying and adding say wait a minute. are those gadgets. can i think of them in some way as a. function on a space what would that.

space be and what kind of functions. would they be and that going back and. forth really brings these two. completely different looking areas of. mathematics together do you have uh. particular examples where it allowed to. prove some difficult things by jumping. from one to the other is that something. that's a part of modern mathematics. where such jumps are made oh yes this is. kind of all the time. a lot much much of modern number theory. is kind of based on this idea but. and and when you start doing this you. start to realize that you need you know.

what simple. things simple things on one side. algebras start to require you to think. about. the other side about geometry in a new. way you have to kind of get a more. sophisticated idea about geometry or if. you. start thinking about the functions on a. space. you may have you may need a more. sophisticated kind of algebra but um but. in some sense i mean much or most of. modern number theory is. based upon this move to geometry and um. there's also a lot of geometry and.

topology is also based upon. yeah changing if you want to understand. the topology of something you look at. the functions you do dram comology and. you get the topology. anyway. well let me let me ask you then the. ridiculous question you said that this. idea is beautiful. uh can you formalize the definition of. the word beautiful. and why is this beautiful like first why. is this beautiful and second. um what is beautiful. well.

and i think there are many different. things you can find beautiful for. different reasons i mean i think in this. context. the notion of beauty i think really is. just kind of. an idea is beautiful if it's. packages a huge amount of kind of. power and information into. something very simple so in some sense. you i mean. you can almost kind of try and measure. it in the sense of you know what's the. what are the implications of this idea. what. non-trivial things does it tell you.

versus. you know how how how how simply can you. can you express the idea and so so level. of compression yeah uh what is it. correlates with uh beauty yeah that's. that's one and one aspect of it and so. you can start to tell that an idea is. becoming uglier and uglier. as you start kind of having to. you know it doesn't quite do what you. want so you throw in. something else to the idea and you keep. doing that until. you get what you want but that's how you. know you're doing something uglier and. uglier when you have to kind of keep.

adding in. more. more into what was originally a fairly. simple idea and making it more and more. complicated to get what you want. okay so let's put some uh philosophical. words on the table and try to make some. sense of them one word is beauty another. one is simplicity as you mentioned. another one is truth. so. do you have a sense if i give you two. theories one is. simpler one is more complicated.

do you have a sense which one is more. likely to be true. to uh. capture. deeply. the fabric of reality. the simple one or the more complicated. one yeah i think all of our evidence. what we see in the history of the. subject is the the simpler one though. often it's a surprise it's simpler in a. surprising way but um. yeah that that we just don't we just.

anyway when the kind of best theories. have been coming coming up with are. ultimately when properly understood. relatively simple and uh much much. simpler than you would expect them to be. do you have a good explanation why that. is is it just because humans want it to. be that way are we just like ultra. biased then we we we just kind of. convinced ourselves. that simple is better because we find. simplicity beautiful or is there. something about at the our actual. universe. that uh at the core is simple. my own belief is that there is something.

about a universe that that's simple and. i was trying to say that you know there. is some some kind of fundamental thing. about math physics. and physics and all this picture which. is um. which which is in some sense simple. it's true that you know it. it's of course true that you know our. minds have certain have. are very limited and can certainly do. certain things and not others so it. it's it's in principle possible that. there's some. great insight there are a lot of. insights into the way the world works.

which is aren't accessible to us because. that's not the way our minds work we. don't and that what we're seeing this. kind of simplicity is just because. that's. all we ever have any hope of seeing but. so there's a brilliant. physicist by the name of sabine. hasenfelder who both agrees and. disagrees with you i suppose agrees. that uh. the final answer will be simple yeah. but uh simplicity and beauty leads us.

astray in the lo in the local pockets of. scientific progress. uh do you uh do you agree with her. disagreement do you disagree with her. agreement. i agree with the agreement uh well i i i. i i i. yes i thought it was really fascinating. reading your book and and and anyway it. was finding disagreeing with with a lot. but then at the end when she says yes. when we find. there when we actually figure this out. it will it will be simple and yeah and. okay so. we agree in the end.

does beauty lead us astray which is the. the core thesis of her work. in that book i actually i guess i do. disagree with her on on that so much i. don't think and especially and i. actually fairly strongly disagree with. her about sometimes sometimes the way. she'll refer to math and. so the problem is. you know. physicists and people in general just. refer to as math and and they're often. um. they're they're often meaning not what i. would call math which is the interesting. ideas of math but just.

cause some complicated calculation and. and so um. i i guess. my feeling about it is more that it's. very. the problem with talking about. simplicity and using simplicity as a. guide. is that it's very um. it's very easy to fool yourself and you. know it's very easy to decide. to you know to fall in love with an idea. you have an idea you think oh this is. this is great and you fall in love with. it and it's like any kind of love affair. it's very easy to believe that you know.

you're the object of your affections is. much more beautiful than they others. might think and they're that they really. are and that's. very very easy to do so um if you say. i'm just gonna pursue ideas about. beauty and. this and mathematics and this it's. extremely easy to to just fool yourself. i think um and i think that's a lot of. what. the story is she was thinking of about. where people have gone astray that i. think it's i would argue that as more. people it's not that there was some.

simple powerful wonderful idea which. they'd found and it turned out not to be. um. not to be useful but it was more that. they kind of fooled themselves that this. was actually a better idea than it. really was and it was. simpler more beautiful than it really. was is a lot of the story um i see so. it's not that the simplicity would be. lisa's astrays that's just people or. people and they. uh fall in love with with whatever idea. they have and then they they weave. narratives around that idea or they.

present in such a way that uh emphasizes. uh the simplicity and the beauty. yeah that's part of it but i mean the. thing about physics that you have. is that you you know what what really. can tell. if you can do an experiment and check. and see if nature is really doing what. your your idea expects that you you do. in principle have a way of really of. testing it and and it's certainly true. that if you um. you know if you thought you had a simple. idea and that doesn't work and you got.

into an experiment and what actually. does work is somewhere maybe some more. complicated version of it that can. certainly happen and. that that that can be true. i think her emphasis is more that i. don't really disagree with is that. um. people should be concentrating on. when they're trying to develop better. theories on. morons on self-consistency not so much. on beauty but you know not is this idea. beautiful but you know is there. something about the theory which is not.

quite consistent. and that and use that as a guide. that there's something wrong there which. needs fixing and and so i think that. part of her argument i think i was. we're on the same page about. uh what's what is consistency in. inconsistencies. what what exactly um. do you have examples in mind. well it can be just simple inconsistency. between theory and an experiment that if. you so we have this. great fundamental theory but there are.

some things we see out there which don't. seem to fit in it like like dark energy. and dark matter for instance. but if there's something which you can't. test experimentally i think. you know she would argue and i would. agree that for instance if you're trying. to think about. gravity and how are you going to have a. quantum theory of gravity you should. kind of. be you know and test any of your ideas. with kind of. kind of a thought experiment you know is. does this actually give a consistent. picture what's going to happen of what. happens in this particular situation or.

not. so this is a good example you've written. about this um. you know since quantum gravitational. effects are. really small. super small arguably unobservably small. should we have hope to arrive at a. theory of quantum gravity somehow. what are the different ways we can get. there you've mentioned that you're not. as interested in that effort because. basically. yes you cannot.

have uh ways to scientifically validate. it given the tools of today yeah i've. actually you know i've over the years. certainly spent a lot of time learning. about. gravity and about attempts to quantize. it but it. it hasn't been that much. in the past the focus of what i've been. thinking about but. i mean my feeling was always you know as. i think speed would agree that the uh. you know one way you can pursue this if. you if you can't do experiments is. just this kind of search for consistency. you know it can be remarkably hard to.

come up with a completely consistent. model of model of this in a way that. brings together quantum mechanics and. general relativity. and that's i think kind of been. the traditional way that people who have. pursued quantum gravity have often. pursued you know. we have the best route to finding a. consistent. theory of quantum gravity and string. theorists will tell you this. other other people will tell you it it's. it's kind of what people argue about but.

but the problem with all of that is that. you end up. um. the danger is that you end up with that. that everybody could be successful. everybody everybody's. program for how to find a theory of kind. of gravity you know ends up with. something that is consistent. and so. in some sense you could argue this is. what happened to the strength there is. they um. they solved their problem of finding a. consistent theory of quantum gravity and. they ended but they found 10 of the 500. solutions so.

you you know. if you believe that everything that they. would like to be true is true well. okay you've got a theory but it's. it ends up being kind of useless because. it's just one of. an infant essentially infinite number of. things which you have no way to. experimentally distinguish and so this. is a. just a depressing situation. um but but i but i do think that there. is a um. so again i think pursuing ideas about. what. more about beauty and how can you.

integrate and unify. these issues about gravity with other. things we know about physics and can you. find a theory which were they were these. fit together in a in a way that makes. sense and and hopefully predict. something that's much more promising. well it makes sense and hopefully i mean. we'll sneak up. onto this question a bunch of times. because you kind of said. uh a few slightly contradictory things. which is like it's nice to have a theory. that's consistent. but then. if the theory is consistent it doesn't.

necessarily mean anything. so like it's it's not enough it's not. enough it's not enough and that's the. problem so it's like it keeps coming. back to. okay there should be some experimental. validation. so okay. let's talk a little bit about string. theory you've been uh. a bit of an outspoken critic of strength. theory. maybe one question first to ask is what. is string theory. and uh. beyond that why is it.

wrong. or rather the title of your blog says. not even wrong okay. well one interesting thing about the. current state of strength theory is that. i think it i'd argue it's actually very. very difficult to at this point to say. what string theory means if people say. they're string theorists what they. mean and what they're doing is uh. it's kind of hard it's hard to pin down. the meaning of the term but the but the. initial meaning i think goes back to um. there was kind of a series of. developments starting in 1984 in which.

people felt that they had found a. unified theory of. our so-called standard model of of all. the standard. well-known kind of particle interactions. and gravity and it all fit together in a. quantum theory and that you could do. this. in a very specific way by. instead of thinking about. having a quantum theory of particles. moving around in space time think about. uh quantum theory of kind of. one-dimensional loops moving around in.

space-time so-called strings and so. instead of one degree of freedom. these have an infinite number of degrees. of freedom it's a much more complicated. theory but you can imagine. okay we're going to quantize this theory. of loops moving around in space-time. and what they found is that they. is that you could make you could do this. and you could fairly relatively. straightforwardly make sense of. of such a quantum theory but only if. space and time together were. 10-dimensional.

and so then you had this problem again. the problem i referred to at the. beginning of okay now once you make that. move you've got to get rid of six. dimensions. and so the hope was that. you could get rid of the six dimensions. by making them very small and that. consistency of the theory would require. these that these six dimensions um. satisfy a very specific condition called. being a claudio manifold and that we. knew very very few examples of this. so what got a lot of people very excited.

back in. 84 85 was the hope that. you could just take this some 10. dimensional string theory and. find one of a limited number of possible. ways of. of getting rid of six dimensions by. making them small and then you would end. up with a an effective four-dimensional. theory which looked like the real world. this was the hope so then. there's been a very long story about. what happened to that hope over the. years i mean. i i would argue and like part of the. point of the book and its title was that.

um. you know that this this ultimately was. it was a failure that you ended up that. this idea just didn't um. there ended up being just too many ways. of doing this and you didn't know how to. do this consistently. that it was kind of. not even wrong in the sense that you. couldn't even you never could pin it. down well enough to actually get a real. falsifiable prediction out of it that. would tell you it was wrong but it was. um. it was kind of in the in the realm of. ideas which initially looked good but.

the more you look at them. they just um. they don't work out the way the way you. want and they don't actually end up. carrying the power or the that you. originally had this vision of. and yes the the book title is not even. wrong your blog your excellent blog. title is not even wrong. okay but there is nevertheless been a. lot of excitement about string theory. through the decades as you mentioned uh. what are the different flavors of ideas. that came. uh. like they branched out you mentioned 10.

dimensions you mentioned. loops with infinite degrees of freedom. what what other interesting ideas to you. that kind of emerge from this world. well yeah i mean the problem in talking. about the whole subject and well partly. one reason i wrote the book. is that you know it it gets very very. complicated i mean there's a huge amount. you know you a lot of people got very. interested in this a lot of people. worked on it and and in some sense i. think what happened is exactly because. the idea didn't really work.

that this caused people to. you know instead of focusing on this one. idea and digging in and working on that. they just kind of. kept trying new things and so. people i think ended up wandering around. in a very very rich space of ideas about. mathematics and physics and discovering. you know all sorts of really interesting. things it's just the problem is there. tended to be an inverse relationship. between how interesting and beautiful. and fruitful this new. idea that they were trying to pursue was. and how much it looked like the real.

world. so there's a lot of beautiful. mathematics came out of it. i think one of the most spectacular is. what the. physicists call two-dimensional. conformal field theory and so these are. basically. [Music]. quantum field theories and kind of think. of it as one space and one time. dimension which. you know have just this huge amount of. symmetry and a huge amount of structure. which. and just some totally fantastic. mathematics behind it and um and again. and and some of that mathematics.

is exactly also what appears in the. language program so a lot of the um. first interaction between math and. physics around the language program has. been around these two-dimensional. conformal field theories. is there um something you could say. about what the major problems are with. strength theory. so. like um. besides. that there's no experimental validation. you've written that a big hole. in string theory has been its.

perturbative definition yeah. perhaps that's one can you explain what. that means well maybe to begin with i. mean i think i mean the simplest thing. to say is. you know the the initial idea really was. that. okay we're we have this. instead of what's great is we have this. thing that only works. that's very structured and has to. work in a certain way for it to make. sense. and um. but but then you ended up you ended up. in ten space time dimensions and so to.

get back to physics you had to get rid. of five of the dimension six of. dimensions. and. the bottom line i would say in some. sense it's very simple that what people. just discovered is just. there there's kind of no particularly. nice way of doing this there's an. infinite number of ways of doing it and. you can get whatever you want depending. on how you do it so the you you end up. the whole program of starting at ten. dimensions and getting to four. just kind of collapses out of a lack of. any way to kind of get to where you want. because you can get anything.

the hope around that problem has always. been that. the standard formulation that we have of. string theory which is. you can go in by the name perturbative. but it's kind of um. there's a standard way we know of given. a classical theory of constructing. a quantum theory and. and working with it which is. that's the so-called perturbation theory. that um that we know how to do. and that.

that by itself just just doesn't doesn't. give you any hint as to what to do about. the six dimensions. so actual perturbed string theory by. itself really only works in 10. dimensions. so. you have to start making some kinds of. assumptions about how i'm going to. go beyond. this formulation that we really. understand of string theory and get rid. of these six six dimensions so kind of. the simplest one was the um. the claudio. postulate. but um.

when that didn't really work out people. have tried more and more different. things and and the hope has always been. that. the solution. this problem would be that you would. find a a deeper and better understanding. of what string theory is that would. actually go beyond this perturbative. expansion and which would um which would. generalize this and and that once you. had that it would um. it would solve this problem of. it would pick out what to do with the. six dimensions how difficult is this.

problem so. if i could restate the problem it seems. like there's a very consistent. physical world operating in four. dimensions. and uh how do you map a consistent. physical world in 10 dimensions to a. consistent physical world in four. dimensions right and how how difficult. is this problem is is that something you. can even answer. um. just. in terms of physics intuition in terms.

of mathematics mapping from. ten dimensions to four dimensions well. basically i mean you have to get rid of. the of six of the dimensions so there's. i mean there's kind of two ways of doing. it one is what we call compactification. you say that. there really are 10 dimensions but for. whatever reason six of them are really. are so so small we can't see them. so you basically start out with ten. dimensions and what we call you know. make make six of them. not go out to infinity but just kind of. a finite extent and then make that size.

go down. so small it's unobservable but that's. like that's a math trick. so. can you also help me build an intuition. about. how rich. and interesting the world in those six. dimensions is. because so compactification seems to. imply. well that's very interesting well no but. the problem is that what you learn if. you start doing math mathematics looking. at geometry and topology and in more and. more dimensions is that.

i mean. asking the question like what are all. possible six dimensional spaces it's. just a it's kind of an unanswerable. question it's just uh i mean it's even. kind of technically undecidable in some. way they're just they're just too too. they're too many things you can do with. all these. if you start trying to make if you start. trying to make one-dimensional spaces. it's like well you got a line you can. make a circle you can make graphs you. can kind of see what you can do but as. you go to higher and higher dimensions. there's just so many ways you can.

put things together of and get something. of that dimensionality and. so it it. unless you have some very very strong. principle which is going to pick out. some very specific. ones of these six dimensional spaces. and. they're just too many of them and you. can get anything you want but um so if. you have 10 dimensions. the kind of things that happen. say that's actually the way. that's actually the fabric of our. realities 10 dimensions there's a.

limited set of behaviors of objects i. don't even know what the right. terminology to use that can. occur when within those dimensions like. in reality yeah. and so like. what i'm getting at is like is there. some consistent constraints. so if you have some constraints that map. to reality. then you can start saying like. dimension number seven is kind of boring. all the excitement happens in the. spatial dimensions one two three yeah.

and time is also kind of boring. yeah and like. some are more exciting than others or we. can use our metric of beauty. some dimensions are more beautiful than. others once you have an actual. understanding of what actually happens. in those dimensions in our physical. world as opposed to sort of all the. possible things that could happen in. some sense i mean just the basic factors. you need to get rid of them we don't see. them so you need to somehow explain them. what you have to the main thing you're. trying to do is to explain why we're not. seeing them. and so you can you have to come up with.

some theory of these extra dimensions. and how they're going to behave and. string theory gives you some ideas about. how to do that but. but. the bottom line is where you're trying. to go with this whole theory you're. creating is. to just make all of its effects. essentially unobservable so it's a it's. not a really. it. it's an inherently kind of dubious and. worrisome thing that you're trying to do. there why are you just. adding in all the stuff and then trying.

to explain why we don't see it i mean. it's just good this may be a dumb. question but it's is this an obvious. thing to state. that. those six dimensions are unobservable or. anything beyond four dimensions is. unobservable or. do you leave a little door open to. saying. the current tools of physics. and obviously our brains aren't unable. to observe them. yeah but we may need to come up with. methodologies for observing so as.

opposed to collapsing your mathematical. theory into four dimensions. leaving the door open a little bit too. maybe we need to come up with tools that. actually allow us to directly measure. those dimensions. yes i mean but you mean you can. certainly ask you know assume. that that we've got. model look look at models with more. dimensions and ask you know what would. the observable effects how would we. know this and you go out and do. experiments so for instance. you have a. like. gravitationally you have an inverse.

square law of forces okay if you had. more dimensions that inverse square law. would change something else. so you can go and start. measuring the inverse square law and say. okay an inverse square law is working. but maybe if i get get and it turns out. to be actually kind of very very hard. measuring gravitational effects and even. kind of. you know somewhat macroscopic distances. because they're so small so you can you. can start looking at the inverse square. law and say start trying to measure it. at shorter and shorter distances and see.

if there were extra dimensions at those. distance scales you would start to see. the inverse square law fail and um so. people look for that and again you don't. see it but. you can i mean there's all sorts of. experiments of this kind you can you can. imagine which test. for effects of extra dimensions at. different at. different distance scales but. you know none of them. i mean they they all just don't work. nothing yet i think yeah but you could. say ah but it it's if it's just it's.

just much much smaller you can say that. which by the way makes ligo and. the detection of gravitational waves. quite an incredible project. ed whitten. is often brought up as one of the most. brilliant mathematicians and physicists. ever. what do you make of him and his work on. string theory. well i think you know he's a truly. remarkable figure i've. you know had the pleasure of meeting him. first when he was a postdoc and um i.

mean he's a. just completely. amazing um mathematician and physicist. and uh you know he's. quite a bit smarter than just about. about any of the rest of us and also. more hard working and it's a it's a kind. of frightening combination to see how. much he's. been able to do. and um but i would actually argue that. you know his his greatest work the. things that he's done that have been of. just this mind-blowing significance of. giving us i mean he's completely. revolutionized some areas of mathematics.

he's totally revolutionized the way we. understand the relations between. mathematics and physics. and most of those. his greatest work is is stuff that. doesn't have has little or nothing to do. with string theory i mean for instance. he um. you know he so he was actually one of. fields the very strange thing about him. in some sense is that he um. he doesn't have a nobel prize so there. there's a very large number of people. who are. nowhere near as smart as he is when. don't work anywhere near as hard who.

have nobel prizes i think he just had. the misfortune of. coming into the field at a time when. things had gotten much much much tougher. and nobody really had. no matter how smart you were it was very. hard to come up with a new idea that was. going to work physically and get you a. nobel prize. but he but he um you know he he got a. fields medal for. a certain work he did in um in. mathematics and that's just completely. unheard of you know for mathematicians. to give a field medal to someone outside. their field and physics is really um.

you know you wouldn't have before it he. came around i don't think anybody would. have thought that was even conceivable. these things um. he came into the field of theoretical. physics at a time when um. and still to today. is you can't get a nobel prize for. purely theoretical work a specific. problem of trying to do better than the. standard the standard model is just. this insanely successful thing and it. kind of came together in 1973 pretty. much.

and post and so and and all of the. people who kind of were involved in that. coming together you know many of them. ended up with nobel prizes for that but. but if you look. post 1973 pretty much it it's a little. bit more there's some. edge cases if you like but the if you. look post 1973 at what people have done. to try to do better than the standard. model and to get a better unified theory. it really hasn't it's been too hard a. problem it hasn't worked the theory is. too good and so it's not that other.

people. went out there and did and did it and uh. not him and that they got nobel prizes. for doing it is that no one really the. kind of thing he's been trying to do. with string theory is not um no one has. been able to do since 1973. is there something you can say about the. standard model so the four laws of. physics that seems to work very well and. uh. yet people are striving to do more. talking about unification so on why. what's wrong what's broken about the. standard model.

why why does it need to be improved i. mean the thing which gets most attention. is um. is gravity that we have trouble um. so you want to you want to in some sense. integrate. integrate what we know about the. gravitational force with it and have a. unified quantum field theory that has. gravitational interactions also so. that's the big problem everybody talks. about um. i mean. but but it's also true that if you look. at the standard model it has these very. very deep beautiful ideas but.

there's certain aspects of it that are. very. let's just say that they're not. beautiful they're not um. you have to to make the thing work you. have to throw in. lots and lots of extra parameters at. various points. um and a lot of this has to do with the. so-called uh. you know the so-called higgs mechanism. in the higgs field that if you look at. the theory it's. everything is if you forget about the. higgs field and what it needs to do. the rest of the theory is.

is very very constrained and has very. very few free parameters really a very. small number there's a very small number. of parameters and a few integers which. tell you what the theory is. to make this work as a theory of the. real world you need a higgs field and. you need to. it needs to do. to do something and. once you introduce that higgs field all. sorts of parameters. um make an appearance so now we've got. 20 or 30 or whatever whatever parameters. that are going to tell you what all the. masses of things are and what's going to.

happen so you've gone from. a very tightly constrained thing with a. couple parameters to uh. this this thing which the minute you put. it in you had to add all this extra. all these extra parameters to make. things work and so that. it may be one argument as well that's. just the way the world is and. the fact that you don't find that. aesthetically pleasing is just your. problem or. maybe we live in a multiverse and those. numbers are just different in every. universe but but you know another.

reasonable conjecture is just that well. this is just telling us that there's. something we don't understand about. what's going on in a deeper way which. would explain those numbers and there's. some kind of. deeper idea about where the higgs field. comes from and what's going on. which we haven't figured out yet and. that's. that's what we should look for but to. stick on string theory a little bit. longer. could you play devil's advocate. and. try to argue for string theory.

why it is something that. deserved the effort that it got. and still con. like if you think of it as a flame still. should be a little flame it keeps keeps. burning well i i think the i mean. the most positive argument for it is is. all the um. you know all sorts of new ideas about. mathematics and about parts of physics. really emerged from it so it was very a. fruitful. source of. ideas and i think you know this is. actually one argument you'll definitely.

which i kind of agree with i'll hear. from from whitten and from other. strength here i said you know this is uh. this is just such a fruitful and. inspiring idea and it's led to so many. other different things coming out of it. that you know there must be something. right about this. and um yeah that's you know okay that. anyway i think that that's probably the. strong the strongest thing that they. that that they've got um but you you. don't think there's. aspects to it that could be uh. neighboring to to just to a theory that.

does unify everything to a theory of. everything like it could it may not be. exactly um. uh exactly the theory but uh sticking on. it longer might get us closer to the. theory of everything. well the problem now really is that you. really don't know what it is now you've. never nobody has ever kind of come up. with this non-perturbative. theory so there. it's become more and more. frustrating and an odd activity to try. to argue with the string theorists about.

string theory because it's become. less and less well-defined what what. what it is. and it's become actually more and more. kind of uh whether. you have this weird phenomenon of people. calling themselves string theorists. when they've never actually worked on. any theory were there any strings. anywhere. so what has actually happened kind of. sociologically is that. you started out with this fairly. well-defined proposal and then. i would argue because that didn't work. people and.

branched out in all sorts of directions. doing all sorts of things it became. farther and farther removed from that. and for sociological reasons the ones. who kind of. started out. or now or or were trained by the people. who worked on that have now. become this string string theorist and. um. and. but but but it's become. almost more kind of a tribal denominator. than a um. i think so it's very hard to know what. you're arguing about when you're arguing. about string theory these days well to.

push back on that a little bit i mean. string theory it's just a term right it. doesn't. like you could uh like this is the way. language evolves. is it could start to represent something. more than just the theory that involves. strings it could represent the uh the. effort. to unify the laws of physics right yeah. and uh at high dimensions with these. super tiny objects right or something. like that. i mean we can sort of uh put string. theory aside so for example neural.

networks in the space of machine. learning. there was a. time when they were extremely popular. they became much much less popular to a. point where if you mentioned you'll. never gain no funding. and uh you're not going to be respected. at conferences and then once again. uh you know networks became all the all. the rage about 10 15 years ago and as it. goes up and down and a lot of people. would argue that uh using terminology. like machine learning and deep learning. is um. is. you know often misused over general.

you know everything that works is deep. learning everything that doesn't isn't. yeah something like that you know that's. just the way uh. again we're back to sociological things. but i guess what i'm trying to get at is. if if we leave the sociological mess. aside. uh do we throw out the baby with the. bath water is there some. besides the side effects of nice ideas. from the edwins of the world. is there some core truths there.

that we should stick by. in in in the full. beautiful mess of a space that we call. string theory that people call string. theory. you're right it is kind of a common. problem that you know how what your what. you call some field. changes and evolves in. interesting ways as the field changes. but. i mean. i guess. what i would argue is the you know the. initial understanding of string theory.

that was quite specific we're talking. about a specific idea 10-dimensional. super strings compactified in six. dimensions. to my mind the. the really bad thing that's happened to. the subject is that. you it's hard to get people to admit at. least publicly that that was a failure. that this really didn't work. and so. the fact facto what people do is people. stop doing that and they start doing. more interesting things but they keep. telling talking to the public about. about string theory and.

referring back to that idea and using. that as kind of the starting point and. this kind of the. the place where the. the whole. where the whole tribe starts and. everything else comes from and so the. problem with this is that having as your. as your initial name and what what. everything points back to. something which. um. which really didn't work out it kind of. makes everybody makes everything you've. created this potentially very very.

interesting field with interesting. things happening but. you know. people. in. graduate school take courses on string. theory and everything kind of and this. is what you tell the public in which you. continually pointing back so you're. continually pointing back to this idea. which never worked out as you're. guiding. inspiration and it really kind of. deforms the whole your whole way of um. your your hopes of making progress and. that's to me i think you know the kind. of worst thing that has happened in this. field okay so there's a lack of.

transparency and sort of authenticity. about communicating the things that. failed. uh in the past and so you don't have a. clear picture of. like firm ground that you're standing on. again those are sociological things and. yeah. i i. there's a bunch of questions i want to. ask you so one. what's your intuition about. um. why the original idea failed so what can. you say about. why you're pretty sure has it has failed.

you know and the initial idea was as i. tried to explain it it was quite. seductive in that that you you could see. why whitton and others got excited by it. it was um. you know. at the time it looked like there were. only a few these possible claudios that. would work and it looked like okay we. just have to understand this very. specific. model in these very specific six-special. spaces and we're going to get everything. and so it was a very subjective idea but. it just. you know as people.

learn worked more and more about it it. just didn't um. they just kind of realized that they're. just more and more things you can do. with these six dimensions and you can't. and this this is just not going to work. meaning like it's. i mean. what was the failure um. mode here is is you could just have an. infinite number of possibilities that. you could do so it's you can come up. with any theory you want you can fit. quantum mechanics you can. you can explain gravity you can explain.

anything you want with it right is that. the basic failure mode yeah so it's a. failure mode of kind of that this idea. ended up. being kind of being essentially empty. that it it just didn't. doesn't ends up not telling you anything. because it's consistent with. just about just about anything. and so i mean there's a complex if you. try and. talk with strengtheners about this now i. mean there's a there's an argument. there's a long argument over this about. whether um. you know. oh no no no maybe there still are. constraints coming coming out of this.

idea or not and or maybe we live in a. multiverse and. you know everything is true anyway so. you can there are various ways you can. kind of the strength here as i kind of. react react to this kind of argument. that i'm making but. try to hold on to it. um what about experimental validation is. that uh. is that a fair. standard to hold before. a theory of everything that's trying to. unify quantum mechanics and gravity yeah. i mean ultimately to be really convinced.

that you know that on some new you know. idea but unification really works you. need some kind of uh you need to look at. the real world and see that this is. telling you something. something true about it i mean you know. either either. telling you that if you do some. experiment and go out and do it you'll. get some unexpected result and. that's the kind of gold standard or it. may be. just that like all those numbers that. are we don't know how to explain it it.

will show you how to calculate them i. mean you can it can be various kinds of. experimental validation but that that's. certainly ideally what you're looking. for. how tough is this do you think for a. theory of everything not just string. theory so for something that unifies. gravity in quantum mechanics so the the. very big and the very small. is this uh. let me ask it one way is is it a. physics problem a math problem or an. engineering problem. my guess is it's a combination of a. physics and a math problem that you.

really need. it's it's not really interesting it's. not like there's some kind of. well-defined thing you can write down. and we just don't have enough computer. power to do the calculation that's not. the kind of problem it is at all. but the question is you know what. mathematical tools you need to properly. formulate the problem. is unclear so one reasonable conjecture. is the way the reason that we haven't. had any success yet is just that um.

we're missing. either we're missing certain. physical ideas or we're missing certain. mathematical tools which. or some combination of them which would. which we need to kind of properly. formulate the problem and see and and. see that it. it has a solution that looks like the. real world but those you need uh i guess. you don't but. there's a sense that uh you need both. gravity. like all the laws of physics to be. operating on the same level so this. isn't it feels like you need an object.

like a black hole or something like that. in order to make predictions about. otherwise you're always making. predictions about this joint. phenomena. or or can you do that as long as the. theory is consistent and doesn't have. special cases for each of the functions. well your theory should i mean if your. theory is going to include gravity our. current understanding of gravity is that. you should have um. there should be black hole states in it. you should be able to describe black. holes in this theory and um and just one.

aspect that people concentrate a lot on. is just this. kind of questions about if your. theory includes black holes like it's. supposed to and it includes quantum. mechanics then there's certain kind of. paradoxes which come up and so that's. that's been a huge focus of kind of. quantum gravity work work has been just. those paradoxes. so stepping outside of string theory uh. can you just say first at a high level. what is the theory of everything what. does the theory of everything seek to.

accomplish. well i mean this is very much a kind of. reductionist point of view in the sense. that so it's not a theory this is not. going to explain. to you you know. anything it doesn't really this kind of. theory the theory this kind of theory of. everything we're talking about doesn't. say anything interesting particularly. about like macroscopic objects about. what the weather is going to be tomorrow. or. you know things are happening at this. scale but. just what we've discovered is that as. you look at um. the universe that kind of.

you know if you. kind of start brit you can start. breaking it apart into and you end up. with some fairly simple pieces quanta if. you like and which are doing which are. interacting in some fair in some fairly. simple way. and it's um. it's good so what we mean by the theory. of everything is. a theory that describes all. all the objects all the correct objects. you need to describe what's happening in. the world and describes how they're. interacting with each other at a most.

fundamental level how you get from that. theory to. describing some macroscopic incredibly. complicated thing is there that becomes. again more of an engineering problem and. you may need machine learning or you. made you know a lot of very different. things to do it but i don't even. think it's uh just engineering it's also. science it one thing that i find. um. kind of interesting. talking to physicists is is a little bit.

there's a. a little bit of hubris so some of the. most brilliant people i know are. physicists both philosophy and just in. terms of mathematics in terms of. understanding the world but there's a. kind of uh either a hubris or what would. i call it. uh. like a confidence that if we have a. theory of everything we will understand. everything like this is the deepest. thing to understand and i would say. and like the rest is details right. that's the the old rutherford thing uh.

but. to me. there's like this is like a cake or. something there's layers to this thing. and each one has a theory of everything. yeah like at every level. from biology like how life originates. that itself like complex systems yeah. like that in itself is like this. gigantic thing that requires a theory of. everything and then there's the in the.

space of humans psychology like. intelligence collective intelligence the. way it emerges among species. that feels like a complex system that. requires its own theory of everything. on top of that. is. things like in the computing space. artificial intelligence systems like. that feels like it is a theory of. everything and it's almost like. once we solve. once we come up with the theory of. everything that explains the basic laws. of physics that gave us the universe.

even stuff that's super complex like uh. how like how the. universe might be able to originate even. explaining something that you're not a. big fan of like multiverses or stuff. that we don't have any evidence of yet. still we won't. be able to. have a strong explanation. of uh. why. food tastes delicious oh yeah yeah i. know no anyway i yeah i agree completely. i mean this. there is something kind of completely. wrong with this terminology or theory of.

everything that it's not um it's really. in some sense very bad term very. hubristic and bad. terminology because it's not um this is. explaining. this is a purely kind of reductionist. point of view that you're trying to. understand. certain a certain very specific kind of. things which. you know in principle. other things. you know emerge from but. to actually understand how anything. emerges from this is it's hope it can't. be understood in terms of.

this this underlying fundamental theory. is going to be. hopeless in terms of kind of telling you. what about this um. this various emergent behavior and as. you go to different levels of. explanation you're going to need to. develop new you know different. completely different ideas completely. different ways of thinking and. i guess there's a famous kind of um. phil anderson's. slogan is that you know more is. different. and then yeah so it and. it's just it's just. even once you understand how what a. couple things well if you have a.

collection of stuff and you understand. perfectly well how each thing is. interacting with it. with the others what the whole thing is. going to do is just a completely. different problem it's just not and you. need completely different ways of. thinking about it what do you think. about this. i got to ask you at a few different. attempts at the theory of everything. especially recently uh so. i've been. for many years a big fan of cellular. automata of complex systems and. obviously if because of that a fan of. stephen wolfram's work on in that space.

but he's recently been talking about a. theory. of everything through his physics. project essentially. uh what do you think about this kind of. discrete. theory of everything for like from. simple rules and simple objects on the. hyper graphs emerges all of our reality. where time and space are emergent. basically everything we see around us is. immersed yeah yeah i i have to say. unfortunately i have kind of pretty much. zero sympathy for that i mean i don't um.

i spend a little time looking at it and. i just don't see. it doesn't seem to me to get anywhere. and it really is just really really. doesn't agree at all with what what with. what i'm seeing this the kind of. unification of math and physics that i'm. kind of talking about around certain. kinds of very deep ideas about geometry. and stuff this. if you want to believe that. that your things are really coming out. of cellular automata at the most um. fundamental level you have to believe. that everything that i've.

seen my whole career and as. as beautiful powerful ideas that that's. all just kind of a mirage which just. kind of randomly is emerging from these. more basic very very simple-minded. things and i. you have to give me some serious. evidence for that and i'm saying nothing. so mirage you don't think there could be. a consistency. where. things like quantum mechanics. could emerge from much much much smaller. discrete. like computational type systems i think.

from the point of view of certain. mathematical point of view quantum. mechanics is already. mathematically as simple as it gets it. really. is a story about really. the fundamental objects that you work. with in when you write down a quantum. theory are in some in some point of view. precisely the fundamental objects. at the deepest levels of mathematics. that you're working with they're exactly. the same. so. and cellular automata are something. completely different which don't fit. into these structures and so i just.

don't see why anyway i don't see it as a. promising. uh. you know promising thing to do and then. just looking at it and saying does this. go anywhere does this solve any problem. that i've ever. that i didn't does this solve any. problem of any kind i just don't see it. yeah to me cellular automata and these. hypographs. i'm not sure solving a problem. is even the standard to apply here at. this moment to me. the fascinating thing is that the. question it asks have no good answers so.

there's not good math explaining forget. the physics of it math explaining the. behavior of complex systems yeah and. that to me is. both exciting and paralyzing like we're. at very early days of understanding. you know. how complicated and fascinating things. emerge from simple rules yeah you know i. agree i think that is a. truly great problem and. depending where it goes it may be um. you know.

it may. start to develop some kind of. connections to the. the things that i've kind of found more. fruitful and. hard to know it just i think. a lot of that area i i kind of strongly. feel i. best. not say too much about it because i just. i don't know too much about it and uh i. mean again we're back to this original. problem that you know your time in life. is uh. is limited you have to figure out what. you're going to spend your time thinking. about and that that's something i've. just never seen enough to convince me to.

spend more time thinking about it well. also timing it's not just that our time. is limited but. the timing of the kind of things you. think about there there's some. aspect to cellular autonomy these kinds. of objects that it feels like. we're very many years away from having. big breakthroughs on. and so it's like you have to pick the. problems that are solvable today in fact. my intuition. again not perhaps biased. is it feels like the kind of systems. that complex systems that cellular.

automata are. would not be solved by human brains. it feels like well like it feels like. something post-human that will solve. that problem or like significantly. enhance humans meaning like using. computational tools. very powerful computational tools. to us to to crack these problems open. um. that's that's if our. approach to science our ability to. understand science our ability to.

understand physics will become more and. more computational or there'll be a. whole field that's computational nature. which currently is not the case that. currently computation is the thing that. sort of. assists us. in um. understanding science the way we've been. doing it all along but if there's a. whole new i mean that. world from new kind of science right. it's a little bit dramatic but you know. this. if computers could do science on their. own computational systems.

perhaps. um. that's the way they would do the science. they would try to understand the. cellular automata and that feels like. we're decades away so. perhaps he'll crack open some. interesting facets of this physics. problem but it's it's very far away so. timing is everything that that's. perfectly possible yeah. uh well let me ask you then in the space. of geometry. i don't know how well you know eric. weinstein oh bro quite well. what are your thoughts about.

his geometric community and the space of. ideas that he's playing with. on. in his proposal for a theory of. everything well i i think that he has. he fundamentally has i think the same. problems that everybody. has had. trying to do this and you know they're. various they're really versions of the. same problem that you try to um. you try to get unity by put it putting. everything into some bigger structure so. he's. has has has some other ones that he that.

are not so conventional that he's trying. to work with but um. he has that he has the same problem that. even if he can. if he can get a lot farther in terms of. having a really well-defined. well-understood clear picture of this. these large these things he's working. with they're really kind of large. geometrical structures with many. dimensions many kinds and i just don't. see any way. he's going to have the same problem the. string leaders have how do you get back.

down to. the structures of the standard model and. how do you um. yeah so i i just. anyway. it's the same. and there's another interesting example. of some similar kind of thing is um. garrett lucy's. theory of everything again you know he's. there it's a little bit more specific. than eric's he's. working with this e8 but it um. again. i think all these things found her at. the same point that you don't. you know you create this unity but then.

you have no. you don't actually have a good idea how. you're going to get back to the to the. actual. to the objects we're seeing how are you. going to you create these big symmetries. how are you going to break them and and. because because we don't see those. imageries in in the real world and um so. ultimately there would need to be a a. simple. process. for collapsing it to four dimensions. you'd have to explain well yeah and i. forget in his case but it's not just.

four dimensions it's also these um. these structures you see in the standard. model there's a. you know there's certain very small. dimensional groups of symmetry so called. u1 su-2 and su-3 and. the problem with. and this has been the problem since the. beginning almost immediately after 1973. about a year later two years later. people started talking about grand. unified theories so you take. the u1 the su-2 and the su-3 and you put. them in together into this bigger. structure called the su5 or so10.

but then. you're stuck with this problem that wait. a minute now how. why does the world not look why do i not. see. the these su5 symmetries in the world i. only see these and so. and and i think you know those id. the kind of thing that that that eric. and all sudden garrett and lots of. people try to do they all kind of found. her in that same. in that same way that they don't have. they don't have a good answer to that. are there lessons ideas to be learned.

from theories like that from gary leases. from eric's. um i don't know it depends i have to. confess i haven't looked that closely at. a. at uh at eric's i mean he explained to. this to me um personally uh a few times. i've looked a bit at his paper but it's. um. again we're back to the problem of a. limited amount of time in life and. yeah i mean it's an interesting effect. right. why don't more physicists look at it. there.

i mean i i'm in this position that. somehow. you know. uh. i've of uh. people write me emails for whatever. reason. and i'd work in the space of ai and so. there's a lot of people perhaps ai is. even way more accessible than physics in. a certain sense it's a lot of people. write to me with different theories. about they have for how to create uh. general intelligence. and it's again a little bit of an excuse.

i say to myself like well i only have a. limited amount of time so that's why i'm. not investigating it but i wonder if um. there's ideas out there. that are still powerful they're still. fascinating and that i'm missing because. i'm. because i'm dismissing them. because they're outside of the sort of. the usual process of academic research. yeah well i mean the same thing and. pretty much every day in my email. there's a somebody's got a.

theory of everything about why all of. what physicists are doing. perhaps the most disturbing thing i. should say about my uh critique being a. critic of string theory is is that when. you realize who your fans are. um that they. every day i hear from somebody that oh. well since you don't like string theory. you must of course agree with me that. this is the right way to think about. everything. oh no oh no. and you know. most of these. are you know you quickly you can see. this is person doesn't know very much.

and doesn't know what they're doing you. know but there's a whole continuum to. you know people who are quite serious. physicists and mathematicians who are. making a fairly serious attempt to try. to to do something and like like eric. and uh and eric and then. then your your problem is. you know you spent you. you do so won't try to spend more time. looking at it and try to figure out what. they're really doing but. then at some point you just realize wait. a minute you know for me to really. really understand exactly what's going. on here would just.

take. time i just don't have. yeah it takes a long time which is the. nice thing about ai. is unlike the kind of physics we're. talking about. if your idea is good. that should. quite naturally lead to you being able. to build a system that's intelligent. so you don't need to get approval from. somebody that's saying you have a good. idea here you can just utilize that idea. and engineer a system like naturally. leads to engineering with physics here. if you have a.

perfect theory that explains everything. that still doesn't obviously lead one to. um. to scientific experiments that can. validate that theory and two to like uh. trinkets you can build and sell right. right at a store for five dollars i. can't make money off of it. [Laughter]. so that that makes it much much more. challenging um. well let me also ask you about something. that you found especially recently. appealing which is roger penrose's.

twister theory. what is it what kind of questions might. it allow us to answer. what will the answers look like it's. only in the last couple years i really. really kind of come to really i think to. appreciate it and to see how to really. what i i believe to see how to really do. something with it and i've gotten very. excited about that last year too i mean. one way of saying. one idea of twister theory is that what. it's it's it's a different. way of thinking about. what space and time are and about what.

points in space and time are. but but which only which is very. interesting that it only really works in. four dimensions so four dimensions. behaves very very specially unlike other. dimensions and in four dimensions. there's certain. there is a way of thinking about. space and time geometry where you know. as well as just thinking about. points in space and time. you can also. um. think about different objects it's all. called twisters and then when you do. that you end up with a um kind of a. really interesting insight that the um.

that. you can formulate a theory and you can. formulate a very take a standard theory. that we formulated in terms of points of. space and time and you can reformulate. in this twister language and in this. twister language it's the um. the fundamental objects actually are. more kind of the. are actually spheres in some sense kind. of the light cone so maybe one. way to say it which actually i think is. is really.

is quite amazing is if you ask yourself. you know what do we know about about the. world we have this idea that. the world out there is this all these. different points in these points. well that's kind of a derived quantity. what really really know about the world. is when we open our eyes what do you see. you see a sphere. and you and that what you're looking at. is you're looking at this you know a. sphere is worth a light rays coming into. into your eyes and what penrose says is. that. well what what a point in space-time is.

is that sphere. that sphere of all the light rays coming. in and and he says and you should. formulate your um instead of thinking. about points you should think about the. space of those spheres if you like and. formulate the degrees of freedom as. physics that's living on those fears. living on so you're kind of you're kind. of living on your degrees of freedom are. living on light rays not on points. and it's a very different way of. thinking about um. about about physics and you know he and.

others working with him developed a. you know a beautiful mathematical this. beautiful mathematical formalism and a. way to go back and forth between our. kind of some aspects of our standard way. we write these things down and. work on the so-called twister space and. you know they. certain things worked out very well but. they ended up. you know. i think kind of stuck by the 80s or 90s. that they weren't. a little bit like string theory that. they they um. by using these ideas about twisters they.

could develop them in different. directions and find all sorts of other. interesting things but they were they. were getting they weren't finding any. way of doing that that brought them back. to kind of new insights into physics. and um my own i mean what's kind of. gotten me excited really is is that what. i think i have an idea about. that i think does actually does actually. work that goes more in that direction. and um i can go on about that endlessly. or talk a little bit about it but that's. the um.

i think that that's the one kind of easy. to explain insight about twister theory. there are some more technical ones i. should mean i think it's also very. convincing what it tells you about. spinners for instance but that's more. technical well first let's like linger. on the spheres and the light cones. you're saying twisted theory allows you. to. make that the fundamental object with. which you're operating yeah. how that i mean first of all like. philosophically that's. weird. and beautiful.

maybe because it maps. it feels like it moves us so much closer. to. the way human brains perceive reality. yeah so it's almost like um. our perception is. like the the content of our perception. is the fundamental object of reality. that's very appealing yeah. is it mathematically. powerful.

is there something you can. say. can you say a little bit more about what. the heck that even means uh for because. it's much easier to think about. mathematically like a point. in space time like what does it mean to. be operating on the light cone. it uses a kind of mathematics that's. relative that you know what was kind of. goes back to the 19th century among. mathematicians it's not um. anyway it's a bit of a long story but. one problem is that you have to start. it's crucial that you think in terms of.

complex numbers and not just real. numbers and. this for most people that makes it. harder to for mathematicians that's fine. we love doing that but for most people. that makes it harder to think about but. um i i think perhaps the most the way. that there is a uh something you can say. very specifically about it. you know in terms of spinners which i. don't know if you want to i think at. some point yeah. so maybe what are spinners let's start. with spinner because i think that if we. can introduce that then i can. by the way. twister spell with an o.

and spinner is spelled with an o as well. yes okay. so in case you want to google it and. look it up that's very nice wikipedia. pages as a starting point i don't know. what is a good starting point for. twister theory. one thing you say about penrose i mean. penrose is actually a very good writer. and also very good draftsman he's on. drafts he to the extent this is. visualizable he actually has done some. very nice drawings so i mean almost any. kind of expository thing you can find. him writing is is a very good a good. place to start he's a.

he's a remarkable person but the um. so. spinners are something that. independently came out of mathematics. and out of physics. and um to say where they came out of. physics i mean what people realized when. they started looking at elementary. particles like electrons. or whatever that there there seemed to. be. there seemed to be some kind of doubling. of the degrees of freedom going on if. you. counted. what was there in some sense in the way. you would expect it and when you started. doing quantum mechanics and started.

looking at elementary particles there. were seem to be two degrees of freedom. they're not one. and one way of seeing it was that if you. if you put your electron in a strong. magnetic field. and asked and asked what was the energy. of it instead of it having one energy it. would have two energies there'd be two. energy levels and as you. increase magnetic field the splitting. would increase so. physicists kind of realized that wait a. minute so in we thought when we were. doing first start doing quantum. mechanics that the way to describe.

particles was in terms of wave functions. and these wave functions were complex to. complex values well. if we actually look at particles that. that's not right there they're they're. pairs of complex numbers. and pairs of complex numbers. so you know why so one of the kind of. fundamental from the physics point of. view the fundamental question is why are. all our kind of fundamental particles. described by pairs of complex numbers. just weird and then but if you go and. then then you can ask you know what. happens if you like.

take an electron and rotate it so how. how do things move in this this pair of. complex numbers. well now if you go back to mathematics. what had been. been understood in mathematics you know. some years earlier not that many years. earlier was that if you um. if you ask very very generally think. about geometry of three dimensions and. ask. and if you think about things that are. happening in three dimensions. in the standard way everything. the standard way of doing geometry.

everything is about vectors right so if. you've. if you take any mathematics classes you. probably see vectors at some point. they're just triplets of numbers tell. you. what a direction is or how far you're. going in three dimensional space and. most of everything we teach in most. standard courses in. mathematics is about vectors and things. you build out of vectors so you express. everything about geometry in terms of. vectors or how they're changing or how. you put two of them together and get. planes and.

whatever but what. had been realized that early on is that. if you ask very very generally what are. the. if you have. what are the things that that you can. kind of consistently think about. rotating. and um. and you can so you you ask a technical. question what are the representations of. the rotation group well. you you find that their one answer is. their vectors and everything you build. out of vectors. but then people found but wait a minute. there's also these other things. which you can't build out of vectors.

but which you can consistently rotate. and they're they're described by pairs. of complex numbers by two complex. numbers and they're they're they're the. spinners also and. to make a lot and to make and and you. can think of spinners in some sense is. more fundamental than vectors because. you can build vectors out of spinners. you can take two spinners and make a. vector. but you can't. you can't if you only have vectors you. can't get spinners. so there in some sense at there's some. kind of level of lower level of geometry.

beyond what we thought it was which was. kind of spinner geometry. and this is something which. even to this day when we teach graduate. courses in geometry we mostly. don't talk about this because it's a bit. it's a bit hard to hard to do correctly. if you start if you start with your. whole setup is in terms of vectors. getting describing things in terms of. spinners is a whole different ball game. but um the but so but anyway it was just. this amazing fact that this.

this kind of more fundamental piece of. geometry spinners and what we were. actually seeing if you look at electron. are one in the same. so it's a. i think it's kind of kind of a. mind-blowing thing but it it's very uh. un counter-intuitive. what are some weird properties of. spinners that are currently. counter-intuitive. there are some things that they do for. instance if you rotate a spinner around. 360 degrees it doesn't come back to. where it's it it becomes minus what it. was.

so it's. anyway so so the way rotations work. there's a kind of a funny sign you have. to keep track of in some sense um so. they're kind of too valued in a way. another weird way but there's but but. the fundamental problem is that it's. just not. if you're used to visualizing. vectors you just there's nothing you can. do visualize in terms of vectors that. will ever give you a spinner it just is. not going to ever work. as you were saying that i was. visualizing a vector walking along a. mobius strip. yeah and it ends up being upside down.

um but you're saying that doesn't really. capture. so i mean what really captures it the. pro the problem is that it's really. the simplest way to describe it is in. terms of two complex numbers and your. problem with two complex numbers is. that's four real numbers so. your spinner kind of lies in a four. dimensional space so you that makes it. hard to visualize and. it's crucial that it's not just any four. dimensions it's just it's actually. complex numbers you're really going to. use the fact that.

these are the complex numbers so it um. it's very hard to visualize but but to. get back to what i think is mind-blowing. about twisters. is that the. another way of saying this this idea. about talking about spheres another way. of saying the fundamental idea of. twister theory is. in some sense the fundamental idea of. twister theory is that a point. is a two. is a two. is a two complex dimensional space so. that every.

and that it lives inside the space that. it lies inside is twister space. so in the simplest case it's. for twister space is four dimensional. and. a point in space time is a two complex. dimensional. um. subspace of the f of all the four. complex dimensions and as you move. around in space time you're just moving. your planes are just moving around okay. and that. and but but then the it's a plane in a. four-dimensional space it's a yeah it. plays complex complex planes so it's two.

complex dimensions in four comics. okay but then to me the mind-blowing. thing about this is this then. kind of tautologically answers the. question is what is a spinner well. a spinner is a point i mean the space of. spinners at a point is the point in. twister theory. the points are the complex two planes. and and you want me to and you're asking. what a spinner is. well a spinner the space of spinners is. that two plane. so it's you know just your whole.

definition of what a pointed space time. was just. told you what a spinner was it's they're. they're just it's the same thing yeah. we're trying to project that into a. three-dimensional space and trying to. intuit but yeah. yeah so the intuition becomes very. difficult but um but. from if you don't you not using twister. theory. you have to kind of go through a certain. fairly complicated rigor role to even. describe spinners to describe electrons. whereas using twister theory it's just. completely tautological they're just. what you want.

to describe. the electron is. fundamentally the way you're describing. the point in space-time already it's. just there. so. do you have a hope you mentioned that. you've been uh you found it appealing. recently is it just because of certain. aspects of its mathematical beauty or do. you actually have a hope that this might. lead to a theory of everything. yeah i mean i certainly do have. such a hope because what i've found i. think the thing which which i've done. which i i don't think as far as i can. tell no one had really looked at.

from this point of view before. is. has to do with it this question of how. do you how do you treat time in your in. your quantum theory and um. so. there's another long story about how we. do. quantum theories and about how we treat. time and quantum theories which um. it is a long story but. to me the short version of it is that. what what people have found when you try. and write down a quantum theory. that. it's often.

it's often a good idea to take. your time coordinate whenever you're. using your time coordinate and then. multiply it by the square root of minus. one and to make it purely imaginary and. so you all these formulas which you have. um. in your standard theory if you do that. to those i mean those those formulas. have some very strange. strange behavior and they're kind of. singular. if you ask even some simple questions. you have to very. take very delicate singular limits in.

order to get the correct answer and you. have to take them from the right. direction otherwise it doesn't work. whereas if you just take time. and if you just put a factor of square. root of minus one wherever you see the. time coordinate. you end up with. much simpler formulas which are much. better behaved mathematically. and what i what i hadn't really. appreciated until fairly recently is. also how dramatically that changes the. whole structure of the theory you end up. with a consistent way of talking about.

these quantum theories but it has very. some very different flavor and very. different aspects that i hadn't really. appreciated and in particular the way. the way symmetries act on it is is not. at all what i originally had expected. and so. that's the new thing that i've where i. think i think gives you something is to. um. to do this move which people often think. of as just kind of a. kind of a mathematical trick that you're. doing to make some formulas work out. nicely but to take that mathematical.

trick as really fundamental. and um turns out in twister theory. allows you to simultaneously talk about. your usual time and the time times the. square root of minus one they both. fit they both fit very nicely into. twister theory and um you end up with a. some structures which look a lot like. the standard model. well let me ask you about some nobel. prizes okay. do you think there will be uh. uh there was a bet between um.

michio kaku and somebody else uh about. john horgan here and john horgan about. uh. uh by the way maybe discover a cool. website longbets.com or dot org yeah. yeah it's cool it's cool that you can. make a bet with people. uh and then check in 20 years later. that's uh i really love it there's a lot. of interesting bets on there yeah i. would love to participate but it's. interesting to see you know time flies. yeah. and you make a bet about what's going to. happen 20 years you don't realize 20. years just goes like this yeah yeah and.

then and then you get to face oh and you. get to wonder. like. what. was that person what was i thinking that. person 20 years ago is almost like a. different person what was i thinking. back then to think that. is interesting but so let me ask you. this on record. uh you know 20 years from now or some. number of years from now do you think. there will be a nobel prize given for. something directly connected to a first. broadly theory of everything.

and second. of course one of the possibilities one. of them. string theory. um. strength. definitely not that uh things have gone. yeah. so fine if you were giving financial. advice you would say not to bet no do. not but. and and even i actually suspect if you. ask strength here is that question these. as you you're going to get a few of them. saying i mean if you'd asked them that. question 20 years ago again when.

kaku was making this better whatever i. think some some of them would have taken. you up on it but um. and certainly back in 1984 a bunch of. them would have said oh sure yeah but. now i get the impression that. they've. even they realized that things are not. looking good for that particular idea. again it depends what you mean by string. theory whether maybe the term will. evolve to mean something else which. which will work out but i don't yeah i. don't think that's not gonna. likely to work out whether um. something else i mean i i still think. it's relatively unlikely that you'll.

have any. really successful theory of everything. and and the main problem is is just the. um. it's become so difficult to do. experiments at higher energy that we've. really lost this ability to kind of get. unexpected input from. from experiment and and you can you know. while it's maybe hard to figure out what. people's thinking is going to be 20. years from now looking at um. you know energy particle energy. colliders and their technology it's.

actually pretty easy to make a pretty. accurate guess what it's going to look. what. except what you're going to be doing 20. years from now and um. i think actually i. i would actually claim that. it's pretty clear where you're going to. be 20 years from now and what it's going. to be is you're going to have the. um you're going to have the the lhc. you're going to have a lot more data an. order of magnitude or more. or more. data from the lhc but at the same energy. you're not going to you're not going to. see a higher energy.

accelerator operating successfully in. the um in the next 20 years and like. maybe machine learning or great sort of. data science methodologies that process. that data will not reveal any. major. like shifts in our understanding of the. underlying physics you think i don't. think so i mean i think that that that. feel that my understanding is that they. they're starting to make a great use of. those techniques but but it seems to. look like it it will help them solve. certain technical problems and be able.

to do things somewhat better but not. completely change. the way they're looking at things what. do you think about. the potential quantum computers. simulating quantum mechanical systems. and through that sneak up. to sort of simu through simulation. sneak up to a deep understanding of um. the fundamental physics. the problem there is. that that's promising more for this um. for uh you know for phil anderson's. problem that you know if you want to.

there there's lots and lots of if you. know. you take. you start putting together. lots and lots of things and we think we. know they're pair by pair interactions. but what this thing is going to do we. don't have any good calculational. techniques. you know quantum computers may very well. give you those and so they may. what we think of as kind of strong. coupling behavior we have no good way to. calculate. you know even though we can write down. the theory we don't know how to. calculate anything.

with any accuracy in it the um quantum. computers may solve that problem but the. problem is that they i don't think that. they're going to solve the problem that. they help you with the problem of not. having their. of knowing what the right underlying. theory is. as somebody uh. who likes experimental validation let me. ask you the perhaps ridiculous sounding. but i don't think it's actually a. ridiculous question of. do you think we live in a simulation. do you find that thought experiment at. all useful or interesting.

not really not not really i don't uh it. just doesn't uh. yeah and anyway to me it doesn't. actually lead to any kind of interesting. lead anywhere interesting and yeah to me. so maybe i'll i'll throw a wrench into. your thing uh. to me it's super interesting from an. engineering perspective so if you look. at virtual reality systems. the the actual question is. how much computation and how difficult. is it.

to construct a world. that uh like there are several levels. here. one. is you won't know the difference our. human perception systems and maybe even. the tools of physics won't know the. difference between the simulated world. and the real world. that's sort of more of a. physics question. the the most interesting question to me. has more to do with why food tastes. delicious which is create how difficult. and how much computation is required to.

construct a simulation. where you kind of know it's a simulation. at first. but you want to stay there anyway and. over time. you don't. even remember yeah. well yeah anyway i agree these are kind. of. fascinating questions and they may be. very very relevant to our future as a. species but um. yeah they're just very far from anything. so from a physics perspective it's not. useful to you to think. taking a computational perspective to.

our universe think of it as an. information processing system. and then think of it as doing. computation and then you think about the. resources required to do that kind of. computation and all that kind of stuff. you could just look at the basic physics. and who cares what the the computer it's. running on us yeah it just i mean the. kinds of i mean. i'm willing to agree that you can get. into interesting kinds of questions. going down that road but they're just so. different from anything from what i. found interesting that i just. again i just have to. kind of go back to life is too short and.

i'm very glad other people are thinking. about this but. i just don't see any anything i can do. with it. what about. space itself so i have to ask you about. aliens. again something uh since you emphasize. evidence. do you think there is how many do you. think there are and how many. intelligent alien civilizations are out. there. yeah i have i have no idea i have. certainly as far as i know unless the. government's covering it up or something.

we haven't heard from uh. we don't have any evidence for. such things yet but there's there seems. to be no. there's no particular obstruction. why there shouldn't be so. i mean do you. you work on some. fundamental questions about the physics. of reality when you look up to the stars. do you think about whether somebody's. looking back at us. actually i originally got interested in. physics i actually started out as a kid. interested in astronomy exactly that and.

a telescope and whatever that and. certainly read a lot of. science fiction and. thought about that i i find over the. years i find myself kind of less. anyway. less and less interested in that well. just because i don't i don't really know. what to do with them. i've also kind of kind of at some point. kind of stopped reading science fiction. that much kind of feeling that there was. just two that the actual science i was. kind of learning about was. perfectly kind of weird and fascinating. and unusual enough but and better than.

any of the stuff that. and isaac asimov so why should i. yeah. and you can mess with the science. much more than the the distant science. fiction. yeah the one that's exist in our. imagination or the one that exists out. there among the stars yeah. well you mentioned science fiction. you've written quite a few book reviews. i gotta ask you about some books perhaps. if you don't mind. is is there one or two books that you.

would recommend. to others and maybe if you can. what ideas you drew from them. either negative recommendations positive. well do not read this book for sure well. i must say i mean. unfortunately. yeah you can go to my website and. there's you can click on book reviews. and you can see i've written. read a lot of a lot of i mean. as you can tell from my views about. string theory i'm not a fan of a lot of. the kind of popular books about oh isn't.

straight theory grade and. about. yeah so i'm not a fan of. a lot of things of that kind can ask you. a quick question on this a small tangent. are you a fan. okay can you explore the pros and cons. of forget string theory. sort of science communication. sort of cosmo style. communication of concepts to people that. are outside of physics outside of. mathematics outside of even the sciences.

and helping people to sort of dream and. fill them with awe about the full. range of mysteries in our universe. that's a complicated issue i think. you know i certainly go back and go back. to like what inspired me and um maybe to. connect to connected a little bit to. this question about books i mean. certainly one. the books that some books that i. remember reading when i was a kid were. about the early history of quant. mechanics like heisenberg's books that. he wrote about you know kind of looking. back at telling the history of what.

happened when he developed climate. change it's just kind of a. totally fascinating romantic. great story and uh those were very. inspirational to me. and um i would think maybe other people. might also. also find them that but the um and. that's that's almost like the human. story of the development of the ideas. yeah the human story but yeah just also. how you know they they're these very. very weird ideas that didn't seem to. make sense that how they were struggling. with them and how you know they actually. anyway it's it's it's it's i think it's.

the period of physics kind of beginning. in 1905 plank and einstein and. ending up with the war when these things. are get used to you know make massively. destructive weapons is it's just that. truly amazing so many so many new ideas. let me on another tangent on top of a. change on top of a tangent ask. if we didn't have einstein. so how does science progress. is it the long geniuses. or is it uh some kind of weird network.

of ideas swimming in the air and just. kind of the the geniuses pop up to catch. them and others would anyway without. einstein would we have. uh special relativity general relativity. i mean it it's an interesting case to. case based i mean i mean especially. special relativity i think we would have. had. i mean there are other people. anyway. you could even argue that it was already. there in some form in some ways but i. think special relativity would have had.

without einstein fairly. fairly quickly general relativity. that was a much much harder thing to do. and um. required a much more effort much more. certificate that. i think he would have had sooner or. later but it would have taken taken. quite a bit longer. another thing that took a bunch of years. to validate scientifically the general. relativity but even for einstein from. you know the point which he had kind of. a general idea of what he was trying to. do to the point where he actually had a. well-defined theory that you could.

actually compare to the real world that. was you know i kind of forget the. numbers of the order of magnitude 10. years of very serious work and um if he. hadn't been. around to do that it would have taken a. while before anyone else. got around to it on the other hand there. are things like. with quant mechanics you have um. you know heisenberg and um schrodinger. came up with two. which ultimately equivalent but two. different. approaches to it you know within months. of each other and you know so if.

heisenberg hadn't been there he already. what about schrodinger or whatever and. if neither of them been there it would. have been somebody else a few months. later so. there are times when the um. you know just the. a lot often is. the combination of. the right ideas are in place and the. right experimental data is in place to. point in the right direction and it's. just waiting for. somebody's going to find it um. maybe maybe to go back to your uh to. your aliens i guess the one thing i. often wonder about aliens is would they.

have the same. fundamental physics ideas as we if we. have in mathematics would their mouth. you know would they. you know. how much is this really intrinsic to our. minds if you start out with a different. kind of mind when you end up with a. different. ideas of what fundamental physics is or. what or what the structure of. mathematics is so this is why like if i. was uh. you know i like video games the way i. would do it as a curious being so first. experiment i'd like to do is run earth.

over. many thousands of times and see if our. particular. um no you know what i wouldn't do the. full evolution i would start at homo. sapiens first and then see the evolution. of homo sapiens millions of times and. see how the the ideas of science would. evolve like. would you get. like how would physics evolve how would. math evolves i would particularly just. be curious about the notation they come. up with. um every once in a while i would like. throw miracles at them to like to mess. with them and stuff and then i would.

also like to run earth from the very. beginning to see if evolution would. produce different kinds of brains that. would then produce different kinds of. mathematics and physics and then finally. i would probably millions of times run. the universe over to see what kind of um. what kind of environments. and what kind of uh life would be. created to then lead to intelligent life. to then lead to. um theories of mathematics and physics. synthesis the full range and like sort.

of uh like darwin kind of mark okay. it took them uh. what is it. several hundred million years to come up. with uh. calculus. i would just like keep noting how long. it does and get an average and see see. which ideas are difficult which are not. and and then and then conclusively. sort of figure out if it's uh. if it's more collective intelligence or. singular intelligence that's responsible. for shifts and for big phase shifts and.

breakthroughs in science. if i was playing a video game and. i got a chance to run this whole thing. yeah. but um. we were talking about books before i. distracted okay of course yeah go back. books and yeah so and then yeah so. that's one thing i recommend is the. books books about the. from the original people especially. heisenberg about the. how that happened and there's also a. very very good kind of history of. of the kind of what happened during this. 20th century.

in physics and you know up to the time. of the standard model in 1973 it's. called the um the second creation by um. pop crease and uh and man that's one of. the best ones i know that's. but the one thing that i can say is that. so that book i think. forget when it was late 80s 90s. the problem is that there just hasn't. been much that's actually worked out. since then so. most of the books that are kind of. trying to tell you about all the. glorious things that have happened since. 1973 are.

they're mostly telling you about how. glorious things are which actually don't. really work it's really. the argument people sometimes make in. terms in favor of these books as well oh. you know they're really great because. you want to do something that will get. kids excited and then you know so. they're getting excited about things. something that's not really quite. working it's doesn't really matter the. main thing is get them excited yeah the. other argument is. you know wait a minute when if you're. getting. people excited about ideas that are. wrong you're really kind of you're. actually kind of discrediting the whole. scientific enterprise in a not really.

good way so there's. these problems so my uh. my general feeling about expository. stuff is yeah it's to the extent you can. do it kind of honestly and and and well. that's great there are a lot of people. doing that now but. to the extent that you're. just trying to get people. excited and enthusiastic by kind of. telling them stuff which isn't really. true this is you really shouldn't be. doing that. you obviously have a much better. intuition about physics i i tend to um.

in the space of ai for example you could. you could use certain kinds of language. like calling things um intelligent. that could rub people the wrong way but. i never had a problem with that kind of. thing you know saying that a program can. learn its way without any human. supervision as. alpha zero does to play chess. to me that. may not be intelligence but it's sure. that as heck seems like.

a few steps down the path towards. intelligence yeah and so like i think. that's a very peculiar. uh property of systems that can be. engineered so even if the idea is fuzzy. even if you're not really sure what. intelligence is. or um. like if you don't have a deep. fundamental understanding or even a. model what intelligence is if you build. a system that sure as heck is impressive. and showing some of the signs of what. previously thought impossible. for a non-intelligent.

uh system then that's impressive and. that's inspiring and that's okay to. celebrate in physics. because you're not engineering anything. you're just now swimming in the space. directly when you do theoretical physics. that it could be more dangerous you. could be out. too far away from shore yeah well the. problem. i think if physics is it in a i think. it's actually hard for people even to. believe or really understand. how. that this particular kind of physicist.

has gotten itself into a really unusual. and strange and historically unusual. state which is not really i mean i. spent half my life among mathematicians. and athletic physicists and you know. mathematics is kind of doing fine people. are making progress and it has all the. usual problems but also. so you could have a. but but you i just i don't know i've. never seen anything at all happening in. mathematics like what's happened in the. specific area in physics it's just. the kind of sociology of this the way.

this field. works. banging up against this harder problem. without. anything from experiment to help it it's. really. it's led to some really kind of. problematic things and those so it's one. thing to kind of. you know oversimplify or to slightly. misrepresent to try to explain things in. a way that's not quite right but it's. another thing to start promoting to. people. as a successes ideas which which really. completely failed and um so i mean i'm.

i've kind of a very very specific. if you so have people. won't name any names for instance coming. on certain podcasts like you're telling. the world you know this is a huge. success and this is really wonderful and. it's just not true. and and this is this this is really. problematic and it carries a serious. danger of um you know once. when people realize that this is what's. going on you know they. you know the the loss of credibility of.

of science is is a real real problem for. our society and and you don't want. you don't want people to have an all too. good reason to. to think that what they're being. what they're being told by kind of some. of the best uh institutions in our. country or authorities is is not true. you know it is. it's not true it's a problem. that's it's obviously a characteristic. of not just physics it's uh. it's sociology yeah.

and it's uh i mean obviously in the. space of politics it's the the history. of politics is uh. you um. you you sell ideas to people. even when you don't have any proof that. those ideas actually work if you speak. as if they've have worked and that that. seems to be the case throughout history. and just like you said it's human beings. running up against a really hard problem.

i'm not sure if this is like a. particular. uh like trajectory through the progress. of physics that we're dealing with. knowledge it's just the natural progress. of science you run up against a really. difficult. stage of a field. and. uh. different people that behave differently. in the face of that. some sell books and sort of. tell narratives that are beautiful and. so on they're not necessarily grounded. in um solutions that have proven.

themselves. others kind of uh put their head down. quietly keep doing the work others sort. of pivot to different fields and that's. kind of like yeah ants scattering and. then you have feels like machine. learning which is there's a few folks. mostly scattered away from machine. learning in the in the 90s in the winter. of ai ai winter as they call it but a. few people kept their head down and now. they're called the fathers of deep. learning yeah. and and they didn't think of it that way.

um. and in fact if there's another yeah i. went to they'll just probably keep. working on it anyway sort of like loyal. ants. to a particular. sure yeah. so it's it's it's interesting but you're. sort of saying that um. we should be careful over hyping things. that have not proven themselves. because people will. lose. trust in the scientific process yeah but. unfortunately there's been other. ways in which people have lost trust in. the scientific process that ultimately.

has to do actually with all the same. kind of behavior as you're highlighting. which is. not being honest and transparent about. the flaws. of mistakes of the past yeah i mean. that's always a problem but um this. particular field is kind of fun mostly. it it's a. it's always a strange one i mean i think. in the sense that. there's a lot of public fascination with. it that it seems to speak to kind of our. deepest questions about you know. what is this physical reality where do. we come from and what and these kind of.

deep issues so there's there's this. unusual fascination with it mathematics. is versus very different nobody nobody's. that interested in mathematics nobody. really kind of expects to. learn really great. deep things about the world from. mathematics that much they don't ask. mathematicians that so. so so it's a very unusual it it draws. this kind of unusual amount of attention. and it really is historically in a. really unusual state it's kind of it's. gotten itself. way kind of down uh.

down a blind alley in in in a way which. it it's hard to find other historical. parallels but sort of push back a little. bit there's power to inspiring people. and if i just empirically look. physicists. are really good. at. um combining. science and philosophy. and communicating it like there's. something about physics often that. forces you to build a strong intuition. about the way reality works.

right and that allows you to think. through. sort of and communicate about all kinds. of questions like if you see physicists. it's always fascinating to take on. problems that have nothing to do with. their particular discipline they think. interest in interesting ways and they're. able to communicate their thinking. interesting ways and so in some sense. they have a responsibility not just to. do science but to inspire. and not responsibility but the. opportunity and thereby i would say.

a little bit of a responsibility. yeah yeah and sometimes but um i know. anyway it's hard to say because because. different um there's many many people. doing this kind of thing with different. degrees of. of success and. whatever i i guess one thing um. but but i mean my what's kind of front. and center for me is kind of a more. parochial interest is just kind of what. what damage do you do to the subject. itself. ignoring.

misrepresenting you know what high. school students think about string. theory and not that doesn't matter much. but but what the smartest. undergraduates or the smartest graduate. students in the world think about it and. what paths you're leading them down and. what story you're telling them and what. textbooks you're making them read and. what they're hearing and um and so a lot. of what's motivated me is more to try to. speak to. as kind of a specific population of. people to make sure that look you know. people.

it doesn't matter so much what the. rest of what the average person on the. street thinks about string theory but. you know what. what what what the best students at. columbia or harvard or princeton or. whatever who are who really want to. change work in this field and want to. work that way what what they know about. it what they think about it and that. they not be go into the field being. misled and believing that a certain. story this is where this is all going. this is what i got to do um is it is. that's important to me well in general.

for graduate students for uh people who. seek to be experts in the field. diversity of ideas is really powerful. and is getting into this local pocket of. ideas that people hold on to for several. decades is not good no matter what idea. i would say no matter if the idea is. right or wrong. because there's no such thing as right. in the long term like it's right for now. until somebody builds on. something much bigger on top of it it. might end up being ripe but being a a.

tiny subset of a much bigger thing. so there you always should question sort. of the uh the ways of the past. yeah yeah so so how to kind of achieve. that kind of. diversity of thought and uh within kind. of the sociology of how we organize. scientific research researches i know. this is one thing that i think it's very. interesting that uh sabine hassenfelder. is very it's interesting things to say. about it and i think also at least mohan. in his book which is also about that. very. very much in agreement with them that.

there's. anyway there's a really kind of. important. questions about you know how. how how research in this field is. organized and how people. you know. what can you do to kind of get and get. more diversity of thought and get more. to and get people thinking about um. about a wider range of ideas. at the bottom i think humility always. helps. well. but the problem is that it's also it's a.

combination of humility to know when. when you're wrong and also. but also you have to have a you have to. have a certain very serious lack of. humility to believe that you're going to. make progress on some of these problems. i think you have to have like both modes. and switch between them when needed. let me ask you a question you're. probably not going to want to answer. because uh. you're focused on the mathematics of. things and mathematics can't answer the. why questions but. let me ask you anyway.

do you think there's meaning to this. whole thing. what do you think is the meaning of life. why are we here. i don't i don't know yeah i. was thinking about this so the um. it did occur. one interesting. thing about that question is that you. don't you know so i have. this life in mathematics and this life. in physics and and i see. some of my physicist colleagues you know. kind of. seem to be people are often asking them. what's the meaning of life and they're.

writing books about the meaning of life. and teaching courses about the meaning. of life and. but then i realized that no one ever. asked my mathematician colleagues. nobody ever asks mathematicians yeah. that's funny so. [Laughter]. yeah. everybody just kind of assumes okay well. you people are studying about that. actually whatever you're doing it's. maybe very interesting but it's clearly. not going to tell me anything useful. about the meaning of my life and i'm. afraid a lot of my point of view is that. if people realized how little difference. there was between what the. mathematicians are doing and what a lot.

of these theoretical physicists are. doing they would they might understand. that. it's a bit misguided to look for. deep insight into the meaning of life. from from. from many theoretical physicists it's. not uh. they you know they're they're people. they have they may have interesting. things to say about this you're right. they have they know a lot about physical. reality and about. about. and sometimes about metaphysics about. what. is is real of this kind but um. you're also.

to my mind i think you're also making a. bit of a mistake that you're you're. looking to uh. i mean i'm very very aware that you know. i've led a very. pleasant and fairly privileged existence. of a fairly. without many challenges of different. kinds of a certain kind and and um. i i'm really not in no way the kind of. person that. a lot of people who are looking for to. try and understand. in some meaning of life in the sense of. the challenges that they're facing in. life uh i can't really i'm really the.

wrong person for you to be asking about. this well. if struggle is somehow a thing that's. core to meaning yeah perhaps. mathematicians are just quality the ones. who are. most equipped to answer that question if. in fact the creation or at least. experiencing beauty. is uh. is. is at the core of the meaning of life. because it seems like mathematics is the. methodology but which you can most.

purely explore beautiful things. right yeah. so in some sense maybe we should talk to. mathematicians more. yeah yeah maybe but but the uh. unfortunately you know people do have a. somewhat correct perception that what. these people are doing every day. whatever is is pretty far removed from. anything. yeah from from what's kind of close to. what i'm. what i do every day and what my typical. concerns are so you may learn something. very interesting by talking to.

mathematicians but it's uh. it's probably not going to be you're. probably not going to get what you were. hoping. so when you put the pen and paper down. and you're not thinking about physics. and you're not thinking about. mathematics and you just get to breathe. in the air and look around you and. realize that you're going to die one day. you know you think about that. um your ideas will live on but you the. human. not not especially much but certainly. i've been getting getting older i'm now.

64 years old you start to realize well. there's. probably less ahead than there was. behind and so you start to. that starts to become you know wait what. do i think about that maybe i should. actually. get serious about some getting some. things done which i. which i may not have which i may. otherwise not have time to do which i. didn't see this didn't seem to be a. problem when i was younger but um. that's the main i think the main way in. which that thought occurs. but it doesn't uh you know the stoics. are big on this meditating on mortality.

helps you. more intensely appreciate the beauty. when you do experience it. i suppose that's true but it's not yeah. it's not. not something i've spent. a lot of time trying but um but yeah. day to day you just enjoy the positive. mathematics just enjoy yeah or. our life in general life is. have a. perfectly pleasant life and enjoy enjoy. it and. often think wow this is i think things.

are. i'm really enjoying those things are. going well. yeah life is pretty amazing yeah i think. you and i are pretty lucky we get to uh. live on this nice little earth yeah with. a nice little comfortable climate and we. get to have this. nice little podcast conversation thank. you so much for spending your valuable. time with me today and having this. conversation thank you glad thank you. thank you. thanks for listening to this. conversation with peter white to support. this podcast please check out our. sponsors in the description.

and now let me leave you some words from. richard feynman the first principle is. that you must not fool yourself. and you. are the easiest person to fool. thank you for listening and hope to see. you next time. you.