 It is a great pleasure for me to welcome today to our discussion the Dirac medalists of 2020 Professor Andhra Navu and Professor Pierre Rameau together with Professor Miguel Verazaro who was a former director of ICTP and they were awarded the Dirac medal last year. Unfortunately, Miguel is not with us anymore so I will be interviewing the two of you and this Dirac medal was given for the inception and formulation of string theory which led to new symmetries both bosonic and fermionic it introduced these new symmetries into physics namely in your case it was the world sheet supersymmetry and the space time supersymmetry and it is a very novel very new kind of symmetry which nobody had thought of before and it has really has had a huge impact on the field subsequently in many several years after that. So, I just wanted to understand from you the history of this and what is your perspective on this because I myself am string theorist. So, I know how important and influential was your work because if you walk around in the corridors of any physics department you will often see string theorist at the working at the blackboard saying Ramon Ramon Nehvush words Nehvush words. So, it must be interesting for you to see your name being sort of you know being pronounced all over the world in this manner and you probably didn't imagine it when you did this word. So, maybe let me start with Pierre incidentally you're both French but you did not do your work in France right? No, I did not do your work in France. So, but Pierre let me start with you because in some ways you're my academic grandfather because my advisor Jeff Harvey was your student at Caltech and at Caltech those must have been really exciting days I remember these were the days of symmetries and particle symmetries groups and so on and your name in particular you know perhaps you have not anticipated at the time and I think it's particularly appropriate for the Dirac Medal because your name is now even associated with Dirac himself and there could be no bigger honor than that that there is a Dirac Ramon operator and so I just wanted to understand how did you arrive at this you know what was your path to the discovery of super symmetry. Well, yes it's like all these scientific things you really do not know what you're doing at first but you have an instinct that certain things are worth pursuing and you pursue them most of the time it doesn't work but in this case we were lucky that the dual resonance model also known as the Veneziano model had just been formulated and it had led a lot of directions which were unexplored and in the analysis of this which was coming purely from amplitudes people started extracting propagators and vertices okay and the propagators certainly looked a lot like a generalized propagator for a point particle and so my idea which was developed a bit at CERN sorry not at CERN but in Aspen yes was basically that maybe looks like a generalized particle okay because the string picture was not known at that time well yes not to me but it was known to by Nambu much earlier but I did not know because all I knew is that there was these amplitudes and at the beginning correct me if I'm wrong things were a bit you know compartmentalized I mean the insight of Nambu was not really shared by many people and but people had been working on this amplitude quite a lot and they were extracting from it some simpler structures that were underlying these things and I recognize that one of the simple structure was like a point particle and I decided to pursue the analogy in a in a process I basically started I found that the formalism was good you could do it it gave rise to I recognize I had to expand the momentum to include harmonic oscillators and and this and then the square of this momentum had like the square of harmonic oscillators and out came something which became known roughly at the same time as verisoral operators and it went on and on like this and then and after a while I decided to generalize it to the Dirac equation now Dirac was my god once I understood his book at least I'm not sure I really understood his book but one once I appreciated the beauty before behind his book it was normal that I should emulate I should emulate as much as I could and and then I just followed Dirac in his generalization that's all I did and in a process all these symmetries kept coming up and I did not realize it I knew they were there were new symmetries I didn't quite understand what they were I don't think but you see Dirac was I became acquainted with Dirac in I never met Dirac first time I met Dirac was at the ICTP in 1969 and is it time for a little anecdote yes please because I think Dirac was a very close friend of the center yeah and it's an association that we this one is interesting so I my advisor Balashangran yes okay and before that George Sudarshan had gotten me a two or three months stay at the ICTP right after my PhD I arrived here and Dirac soon afterwards was there and there was a there was some conference in that conference room here and I was sitting two rows behind Dirac and I'd never seen him before but I noticed his head was very small and and I couldn't believe that I was surprised you know out of that head another head came that okay and suddenly in the middle of the talk there is there are steps coming down rather noise and a woman taps it on the shoulder and says come on Paul you can sleep at home now my my musing of this disappeared because one of my god I finally understood once I got married but the the the question is that and Dirac me me followed but this is where I met Dirac and I met meeting is different you he was like I saw him he saw him and but that was here that's very interesting because I think his wife was the sister of uh of of of of of Vigner yeah we've not always used to refer to my famous brother-in-law yeah because he was at Princeton and I was a student there so yeah I see him it's a very nice but going back to the real thing all I did was to follow the Dirac equation I had to invent a generalization of the gamma matrices I introduced oscillators for this and I must tell you that once I started doing this I was I was almost brought to a sense of awe because I knew that I'd done something which was which was bigger than me except I had no idea what it was okay and in my whole career this has never happened again I mean I you know it's just that but as I said we were lucky to be you know at the beginning of of this fantastic field right well we we basically by instinct we just went after it and then we found marvelous things occurring so maybe Andrea can ask you because you worked from a very different perspective perhaps and you were in Paris at that time no no I was in Princeton are you actually yes the amusing thing is the well one of the turning points I would say of my career in retrospect was when I first met Pierre and that's what I'm going to reenact with him tomorrow but perhaps you saw the a little bit of it of what you know what what is going to happen tomorrow it was very amusing and a remarkable coincidence when we first met and then after that we kept in touch and Pierre sent when I was in Princeton sent us with John Schwartz I was working with I was interacting a lot with John Schwartz sent he sent me his paper on the fermionic string say this was 1970 1971 January or something like this 71 and then with John we thought that was quite interesting because we were I more I'm probably more mathematically minded than Pierre and I thought that was a very interesting mathematical structure but we thought that oh fermions Dirac matrices that's too complicated and so we decided to build a completely bosonic model which turned out to be the never Schwartz string oh it's called now and and so that's how little by little we discovered that it was working and that it actually worked very well when married with the fermionic string of Pierre and that's how that's that's how it all began that's the beginning of super strings it was either ultimately yes that was ultimately super string in our paper with John we introduced the word super gauge which after that became supersymmetry and super gauge because we thought it was a miraculous structure which was responsible for the the fact that it all worked and that was a big that was an exciting moment for me yes yeah for all of us yeah for all of us it's also it's fascinating because in fact as it was revealed later both your sectors were somehow essential for the more complete formulation of theory for a consistent formulation of the theory right so even though you thought that you were doing bosons and he was doing fermions you had to they had to get together that's what I was joking to Pierre that he should come to this he was debating whether to come or not because of kovid then I said okay we really need the nebush words and rub on sector together to get together yes to get spacetime supersymmetry and modular invariance and you know summing over spin structures of the Riemann surfaces all this was still not on the horizon yes and this this all this I mean all these pieces of the puzzle came together little by little took a few years took a few years you know the projection GSM projection and all that yes little by little and spacetime supersymmetry afterwards yes but I think the main the really important stuff is is that which is I still cannot get over it is that Dirac's the I mean all of this stuff is based on Dirac's algebraic structure and the fact that Dirac's algebraic structure is so potent and that for for example one of the things which a lot of people were worried about is that we were introducing fermionic operators which had apparently vector indices and it looked totally strange but the fact is that when you go and then it was learned later on that the super string was was working in in 10 spacetime dimension that means eight physical dimensions and in eight physical dimensions the spinner and vector representation of the little groups are the same yes I mean and it had to be in the because tryality of the speed yeah I mean that's completely amazing so this this great man Dirac I mean you know put his finger on something and and and then of course you know eventually many things came out of it but without his his impetus it would not have happened no also then later as you know the Dirac equation has come to play also very important role in mathematics yeah index theory anomalies yes and Witten has very deftly made use of the world line supersymmetry so to speak the to really reformulate the index theory and it really crucially depends on thinking of the gamma matrices as fermions on the world line so that concept it's a very different way of looking at the Dirac equation that it's a kind of your first quantized theory you're just doing some first one well it becomes a Dirac equation in space as Dirac says in his paper he does mention explicitly as I talked about tomorrow was that he thinks of them as spin as the as the you know the dynamical spin variables on the world line of the basketball yeah I mean so so what can you say so we were very lucky we we were at the right time yes yes and the only thing in our favor I would say is that we had a good taste of following the right people well I must say that you know when each time I hear my name associated with that John right or with I feel a little bit strange because I know for sure that if I hadn't met Pierre two years before that or a year and a half before then the Ramon Neveschwart string would be called Ramon somebody else string probably probably you cannot redo rerun history but yeah probably that's impossible yes it's possible of course yes yes yes well but you know maybe I can make a digression here so it would have been called by some some other names besides Pierre when before Abdul Salam got the physics Nobel Prize I thought that maybe he could be it could be a good candidate for the Nobel Peace Prize because he founded this institute and nobody else would have done it whereas we know as we know the standard model other people found it also so well I just didn't get the Nobel Peace Prize but in my opinion he would he could be more proud of this institute than of his scientific discoveries I think it's true actually I have talked to his family and he certainly felt that this was a more lasting legacy yes and I can certainly identify with that I mean he's my predecessor the founding director of this institute but also I share with him you know because he comes from Pakistan I come from India and I know how important is this vision to connect the world through science and to make this scientific resources available to the world around so I think it's you're absolutely right that this aspect of ICDF's vision is perhaps equally important as important or even more important than the scientific contributions coming out on a side thing I could tell you in my career I would be today a probably a rich man and I would probably be doing working for Google or somebody okay because the the beginning of my scientific career was here because that summer that I spent in Trieste okay got me on to onto the track of studying these things and we Andre will talk later on a little bit about what happened but on the way back I mean I was completely working on these things that I did not know what I was going to do but I was working on these things but I would say that the people I met here played a crucial role in my own career and that that is the lesson that when you basically get people together in a in a pleasant environment etc things happen and no that that is also very true that you know we really bring together some 5000 scientists every year and really from all corners of the world and just putting them together in this manner both for science and for more general understanding international cooperation is it's a very amazing thing that I said it does and the the other thing is that going back to what Andre said is that there are no nationalities yes I mean in our field I mean if you can do some physics if you can do this etc then that's it doesn't matter it doesn't really matter this is wonderful this is a wonderful aspect and unfortunately the society is slightly different I think you know but I think I share also Salam's optimism about this that I think science can contribute you know towards bringing and there are examples of ICTP's mission in that direction like the Cezami Synchrotron in Jordan there through science you really bring people who otherwise not talk to each other into the same room but okay going back maybe Andre I can ask you I think it appears sort of suggested that this discovery of the Ramon string was the perhaps the most exciting moment of his scientific life you have worked on many other things I know like the gross novel model QCD and so on so what was in your career the what would you say was the most exciting moment the most exciting moment I think in which respect it was probably indeed in which respect I feel very excited about how the first time we met but in retrospect otherwise otherwise probably yes when we realized that well the Ramon of a short string was working or at least beginning to work and obviously was going to yeah it was going to work yeah probably probably and although we could not forecast the foresight a foresee that it was going to go it was going to go so far and have such a so many consequences both in well in physics I'm not sure but in mathematics certainly well in physics it has come very close well who knows with the aterotic string it's a close call yeah yeah it's almost there and it's missing something also I think one of the things it led to was space-time supersymmetry and space-time supersymmetry yes that was also it grew I guess perhaps some Russians had arrived at independently I don't know the history yes they work off and I could have there was a paper on non-realization non-linearization of the norm of supersymmetry but I think lessons I mean are probably late yes they were perhaps inspired by well they would know they were late they were late I mean the Russians Lieckman and Gelfand and Lieckman first and then a year or two later but they were not inspired by the supersymmetry of at that time the rise completely different there was a the Cold War was in no but also Wesson-Zumino were not I think they were Wesson-Zumino were not aware of string theory they knew about string theory oh yes yes yes oh yes they knew they knew about string theory but arenas string they did they well they were working on two-dimensional stuff a few years before and yes yes and well well they realized at that time the two-dimensional supersymmetry had been discovered of course that's what I thought well why don't why not generalize it that was my understanding generalize it to four dimensions exactly that's what Wesson-Zumino thought yes but the Russians independently I mean there was a work of the knuckle of came a little bit later the Gelfand and Lieckman basically they wrote the the basic multiplet yeah and nobody paid including the Russians you know it is the way the way the way it goes but but that is oftentimes science you know that happens this is the way it is yeah so you know in terms of the sort of the impact of string theory you know it's also space-time supersymmetry of the super string it's connection with gravity unification of all forces all this then later on anomaly cancellation and all this you could not have foreseen otherwise you would have worked on it but also I think then later on I mean even though string theory has not yet made contact with the experimental world it has really led to some very deep insights about the physics of black holes yes and holography yes yes and you know very deep connection with gauge theory from a very through this holographic duality so that's also it's a completely unimaginable consequence of string theory right and well you know the the fact of space-time supersymmetry okay he's a fantastic tool for probing you know physics there was an interesting thing at you know vigner at the urging of his brother-in-law and looked at the representations of the Poincaré group yes there's a famous paper of a famous paper but in that paper you realize there are some very special representations continuous continuous ones which are basically supersymmetric duels of one another one one is the elicity is integer the other one is half of the integer I see I see yeah which is called xy and xy prime and since they did not occur in nature nobody paid any attention to it but they but they are there and this was 1939 or something like this so today I'm sure it's somewhere now in somebody's papers there are some fantastic things so Pierre I know that I mean of course you trace your intellectual sort of lineage to Dirac and vigner I know that you love group theory and also Jeff my advisor you know he was trained well by you I think yes I know I know which led to the E8 cross E8 not extreme I mean that these kinds of really abstract and marvelous creations of you know human mind and so to speak like E8 cross E8 you know you would never come across something like that on the street or in any real context right but somehow such a thing coming to play a role in physics there it's a well this the standard model you know if you extend it it goes to E8 naturally naturally as was by then and to that we should mention Fez agurse great Turkish theoretical physicist who basically was obsessed by group theory and it was very good at it and I followed him but you know the all these studies about the exceptional groups and everything that was Fez agurse the impetus and and it was and therefore you said and this was a direct thing see you said oh my goodness we have these exceptional structures like the platonic solids or something okay therefore nature must use it because it's stuck there and this is the direct view yes this is the direct view sort of a very platonic idealistic view which is which somehow has been quite successful when we would say yeah I mean sometimes it works sometimes it doesn't work it doesn't work but but there is this principle of beauty okay which we all we we all are basically customers of this yes I mean as Vigner famously said the unreasonable effectiveness of mathematics right well there is this paper of Dirac a public lecture in the night in the 1930s where he talks about this thing I mean the Vigner was did not invent this stuff Dirac wrote something about this and basically that you have simplicity and beauty simplicity would be like the Newton's equation very simple beauty would be like special relativity with extra symmetry and that some and and he says those are the guiding principle okay and he said things like which were completely amazing for the time he said why do we have a complicated universe because we have equations but the boundary conditions are complicated because of quantum fluctuations he said that in 1930s okay so so at that point you see it's like oh you know when you open when you go to the Musée d'Orsay and in the Musée d'Orsay there's a room where you have the vangles and you walk into it it could be raining outside or anything like that but suddenly you're sort of okay and that's what happens Andrea you made a French reference maybe yeah what was your what led you to do this kind of physics I mean you were were you brought up in the French school of training or how was but it was well I since I was young I wanted to be a scientist really so and I remember when I was really young after learning when was that in second grade or something like this learning addition subtraction division multiplication I asked my father well what goes next oh really that's fantastic is that art it's very interesting and then he told me how to to compute by hand a school route which I have forgotten since then yeah and so since I was a good student I ended up naturally at the Ecole Normale and then between physics and mathematics I chose physics because well I was more interested by the real world in principle than by purely abstract constructions so it was a natural just a natural natural path I'm still on this path have you you did you grow up in the US or no in France I left France right after high school for a few years and then within so no I mean the same thing you know you you go there in Paris there are places you go to palette de découverte I think if I remember correctly basically you the public goes and you have these beautiful crooks tubes and you have this and you've that and this makes a fantastic impression the impression in retrospect the impression is that the complicated world becomes simple which is quite a remarkable thing and at the time you don't realize this later on you do and so I just felt you know drawn by this that there has to be simple stuff and when I look at the Iraq equation again that is a simple stuff which describes a whole absolutely incredible things so you must have had similarly yes certainly I think string theory again and again sort of gives you this sort of surprises and even though we we are still grappling to really understand what string theory is there is somehow many people in the community cannot shake this feeling that there is some it is really revealing some truth there is probably still much more to be discovered in the structure of the theory which we don't understand yeah what is your take on I mean I mean I guess oftentimes there is a sometimes it's called you know what are they called paparazes you know people have this very somewhat narrow view of science that okay if it is not immediately falsifiable then it is not science I think this which of course is does not correspond to how science is actually done because people really play with ideas and you know just by going by the your hunch and develop them and you have to actually develop them sufficiently to even put them to some falsifiable tests and this is especially true in a field like string theory where we have been able to make progress without a lot of guidance from experiments so how do you what are your views on this from a philosophical point of view if I may say well when you are facing such a not complicated but such a rich structure it takes much a lot of time to really extract from it something which which will be which will maybe which will I don't know connect with some real experimental fact or some physical fact see for example black holes where ultimately some non perturbative so well I shouldn't say that but in principle since if string theory is finite somehow then it should solve the problem of the singularity of the center of a black hole yes and also solve the singularity of of the big bang or at least provide a provide a model for those singularities which would eliminate them it may not be the right one but which could eliminate them and and lead to further developments I would think in cosmology probably but nobody knows yet but you see we are you know physics is such that we are we understand the universe on a very large scale and also on a very small scale but not ultimately to scale zero nor to scale infinity and but these the scales where we understand us are very very far from our world for the moment and so it's difficult to have a falsifiable thing to put forward immediately but who knows who knows after all the quantum field theory which seems to be a very abstract thing is that work in a computer you know in a transistor because and so so actually yes supersymmetry where there is supersymmetry in nuclear physics because there are nuclear argument or symmetric one from the other and you can relate their properties through through some form of supersymmetry I think in solid state physics so but little by little these things are being discovered and the domain of applicability changes but it looks like the the view of the world I mean there are some some theories like the standard model etc I have no doubt that the problems with it will be solved when we put gravity into it in a way okay and but there are other problems I'm not sure they will ever ever be solved I don't know whether or not given our universe will be able to answer some questions but nevertheless you don't think about that when you practice physics you just do it and you're lucky just you have a model to work with it's like and then you find out what what's wrong and if there's a problem you go beyond a little bit and you go beyond and you go beyond so I think the picture of the scientist having deep thoughts is true for people like Dirac or Einstein or Newton etc or Descartes even and but it's not true for most physicists let's face it I mean we just but we are we're attracted to something and we do it and and we have the ability to do it to to some point I mean we're not but also I think Dirac himself said this that you know somehow the equation is smarter than the person who invents it yes that's right certainly it's true for the string because it's really so mind-boggling that what has come out of string theory that for example you said about the resolution of singularities I mean already in string theory even though we don't understand the black hole singularity or the early universe singularity already some singularities like the orbifold singularity or the conifold singularity which in normal geometry are singular but string geometry are not singular so there is reason to hope that you know there is a new way of looking at the singularities which can change a little perspective so yeah there's also something so in the history of the discovery of the standard model I mean the second half of my career has been very much concerned with phenomenological things and I've given I've not given up but I have not worked on on on on on string theory and the the thing that is remarkable is that of all the particles in a standard model that basically are the most interesting to many people right now are the neutrinos and the neutrinos were particles which were in the idea was invented in the mind of a theorist whereas most other particles have been basically discovered in the experiment before and as a result of that you will find that the community it's not true anymore but for a long time did not believe in neutrinos okay because they were just invented in the mind of some guy but who was answering a real problem and and now the experimental front of the standard model is on basically neutrinos is in neutrinos and and we don't know we know it's not finished it's a history that is not finished and after a proton has to decay whether whether we can observe we will observe it in our lifetime is a different matter yeah and so there's a lot more stuff to go it is going on but but the important thing is the excitement of this and and I think at some point we've all been both of us certainly have been tremendously excited to the point of not being able to sleep not not being able to you know it was all encompassing yeah and it was you know it's I don't know very good so I think yeah tomorrow we have the ceremony I'm looking forward to your lecture there maybe do you want to add some comments to wrap up our well I am I'm honored and completely delighted to have the name dirac in this thing because that is somebody that basically influenced my life and not only that but somehow opened up something which you know was a deeper appreciation of certain things and I was lucky enough to be able to contribute in that direction but I followed one of the one of the outstanding physicists of his uh of the last century yes I think it's yeah I think in this particularly rock metal is particularly appropriate oh yeah in its connection so we thank you we thank you yes yes I'm a sermon only saddened by the fact that Miguel is not with us yes and uh Miguel is another one who started was contributing a lot and then went to do in a different direction in a different direction yes but continue to contribute yeah yeah I think tomorrow we'll have a memorial for him with the talks from the Niziano and Parisi but he was he was different from us because he also had a sense of social responsibility yes I'm not saying we do not have it but we we do not look for it in other words he was also a former director of ICT yeah right the coming from Argentina I can also understand that yeah this mission of ICT people only resonated with him so early in his career he left to go back to Argentina and he could not and then he that threats against him so he had to go back so it's kind of that is a sad part but anyway we were completely well and Andre you want to say something though well I'm particularly I'm very honored by this this medal and particularly happy to share it with with Pierre I think it's really it's really this is really nice yeah I'm glad you could come both of you now that's why I tried very hard I'm very happy that you could make it in spite of that thank you so much yeah very good thank you both of you thank you for me to actually meet the stalwarts of my field so thank you thank you