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