 Well, that's already an retrieval question, because I work in several communities in three language fields. I play in three language fields, so in different languages my name sounds differently. So my original name is Nikita Nikrasov, as I come from Russia. And then in the United States, or in English, my name is Nikita Nikrasov, and then in French I'm Nikita Nikrasov, three different ways of naming me. I'm currently a permanent professor at the Simon Center for Geometry and Physics in Stonybrook, United States. Before going there, I was a permanent professor here at the IHS from 2000 until 2013. But of course I visited the IHS before that and after that, both unofficially and unofficially. So I have a very deep connection to this place. For the first time, I think the first time I came here it was very unofficial. I came here to play volleyball at the residence de l'Hermaye with some visitors. And that was a very important experience as I learned later. But then I think I actually had one scientific visit. I think it was a visit for lunch. I came here to meet with Maxim Konsevich. It was probably in 1998. I was visiting some university in Paris. I was at Harvard at the time and I had some questions I wanted to discuss with Maxim together with my collaborator, Andrei Losev. So we took the train, came down here. We didn't actually come to the IHS. We met at a restaurant which no longer exists. Unfortunately, it was a very nice restaurant. I think it was called Pirene. It went bust, as many restaurants here. And I think even though I didn't get the answers to my questions, and Maxim probably didn't get answers to his questions, but somehow we established some sort of connection which helped me later. So I was offered a job here in the year 2000. And I came the same year. And so became part of my life, part of my family. My children were born here. So I literally have my roots in here both scientifically and personally. And so I think I did my best work while I was here. So far, maybe. Hopefully not. So that's that. The fondest memory. There were many nice memories. Since I lived through very important personal experiences here, there are many things which for me are emotionally attached to the IHS. But I guess scientifically the most important thing is the work I had done which was in 2002 I wrote a paper which kind of was the end of the long period of research. For me at that time, so seven years, it looked like a long period. But then it began a new venue of research which continues to this day. This conference, this school is also part of that. So it's what grew out of that work. So to put things in perspective, I came to Paris for the first time in 1994. I was not even a student there. I was finishing my studies in Moscow and moving to Princeton to the graduate school. And in between I came to Paris to attend a conference. I was not even invited. I was too young for that. It was the International Congress of Mathematical Physics. It took place I think in UNESCO in the center of Paris. And I came by bus. It was a long route from Prague. So first Moscow to Prague by train and then from Prague to Paris by bus. It was a night bus. It was exhausted. And in the morning I went to some lectures. And there was a lecture by Edward Whitten who came from Princeton who was presenting his work with Zyberg. It just came out, maybe even before it came out, it was the summer of 1994. Where they claimed to have solved a kind of prototypical example of quantum field theory which is not the theory which we believe describes our world. But at the time it was considered to be maybe the best approximation to that in the sense that it's the theory in which you can probably compute something exactly. And so see some qualitative features which we believe take place in actual nature. And so it was an important work. But from the point of view of, let's say, mathematical physics it was really a conjecture. It was some educated guess which they made based on their work. And that influenced a lot of people. But I was so exhausted at times that actually I literally fell asleep during the talk. But even I understood that it's important work and something has to be... But there are things to be understood about it. So it was not rigorous by mathematical standards and something has to be done. And so that was basically the work which I finished in 2002 when I already came here. But in order to do what I did, lots of little things had to be done before that. So one of these little things involved the notion of non-commutative geometry which was introduced by Alain Kohn. So Alain Kohn is technically a professor at Collège de France but he actually is physically present at IHS very strongly. So he has shared Leon Machin. It means that he has an office here, he comes to have lunch with us and he is not paid by the institute. But nevertheless he has a lot of influence over the means of research here and he had as well. And so even though for me that subject seemed very abstract I was taught in a school which preferred actual geometry to something more abstract which is this non-commutative geometry thing. But it turned out that it was very useful for the research I was doing. Even though it's a research in physics but things I do involve a lot of mathematics. So some people say that it's not even physics, it's more mathematics than physics. So it's kind of a borderline domain. And so that was one of the reasons why for me it was interesting to come here because non-commutative geometry was useful for my research. And another reason was of course Maxim Konsevich who introduced a lot of geometrical structures and also algebraic structures which we believe will help us to understand what quantum field theory is actually. So this is not something we understand yet but we're all interested. Both physicists and mathematicians. Well it's a summer school so it's a kind of conference where lectures give lectures which are aimed at students, graduate students mostly. So the graduate students come from all over the world so I see lots of students from Asia, from the United States, from Europe, from Russia. So it's one of the activities which IHS has been involved in recently which I think is a very healthy thing. And I believe this is actually the first true physics school, summer school in physics. Previous schools were more on the mathematical side. So the subject of the school is called supersymmetrical localization and exact results. This is the topic I already spoke about a little bit briefly. So in physics we are faced with the task of describing the nature but nature is very complex. It has lots of players. You cannot describe the phenomenon precisely because so many things are involved. So we usually make some approximations. We decide that if we want to describe the weather, the blowing in the wind we don't need to know the structure of the atom. That's irrelevant. But we want to describe the structure of the atom. We probably don't need to know the atom here on my hand. We probably don't need to know about the structure of some andromeda galaxy or something which happens very far away. So we constantly make some approximations. We decide what's relevant, what's irrelevant. And then we make some calculations which are always approximate. So they have some degree of precision which in a good theory can be improved systematically if it's needed. But it's always an approximation. Nevertheless, sometimes there are sort of idealized problems in which the computation can be done exactly. So there are some trivial problems where, for example, the elementary particles which are playing a role, taking part in some event, don't interact. They are free. In this case everything can be computed exactly but it's not interesting because there is no interaction. And I guess since the early year 1900, sorry, 1990, 1990, we slowly started accumulating examples of computations in quantum field theories which are exact, which involve interactions. So they are non-trivial and they may teach us something about the more sophisticated theories. And in all these computations a novel kind of symmetry is involved, so-called supersymmetry. I mean, it's novel on the scale of physics. So it was introduced in the 70s. And that's a symmetry which relates elementary particles of different kind. The particles which are so-called bosons, the particles which mediate interactions like the particles of light, the photons, and the other particles which are called fermions are the particles which comprise the matter, like electrons. And when we interact with them, we perceive them, they have very different properties. So the bosons like to be together and fermions don't like to be together. Nevertheless, mathematically it was found that there is possibly a symmetry which relates them in a tricky way. And when such symmetry is present in the theory, it turns out that there are certain quantities which can be computed exactly. And every time such a computation is done, there is some deep connection to mathematics, in particular to topology. And so the exactness of the computations in supersymmetric quantum field theories is related to the fact that in topology you can produce some invariance of geometrical structures which are not sensitive to small details. And so when the question you're asking is not sensitive to details, it's easier to produce an exact answer. So that's what the school is about. It's dedicated to supersymmetric field theories and the ways to compute exactly correlation functions in those theories. It started with the desire to build a machine which would drive itself. I was probably 10 or 11 and I wanted to be able to control it remotely using radio. So it started with some kind of bricolage, as we say. It didn't work very well, so my engineering capabilities were not so good. But I got interested in scientific part of that, so the physics and mathematics of that. So that was one driving force. Another reason was that I was always fascinated by stars. Every person at some stage is fascinated by stars. And I also was fascinated by computers because computers were a very new thing. So I had the bright idea of writing a computer code which would predict the evolution of the star. Whether it would explode, where it would become a supernova, and then become a black hole or a white dwarf or something like that. And again, it also failed because it's a complicated problem. Maybe some astrophysicists these days can do that using supercomputers. But unfortunately I sidetracked and decided that predicting the future of stars is not ambitious enough. So one should predict the future of everything. And so that's how I got interested in string theory. Not in everyday life. So there are some big questions which interest me, of course. Like what is quantum field theory? Is it the right theory to describe the world of elementary particles? And the world of big structures like the universe? What is string theory? Which is the theory which is believed to combine both quantum field theory and gravity. Quantum gravity in particular. But these questions are too big. These are the questions which are comparable to the meaning of life. So what's the meaning of life? Every day I try to work on some simple questions where I can see that there is some progress can be made to understand specific quantum field theory, specific computation in quantum field theory, or specific string computation. But if I should specify the kind of domain in this big area in which I'm working, it's mostly super symmetry and maybe integrability. Well, maybe symmetry in general. So the unusual symmetry is hidden symmetries which are not produced by local generators. This is not something I can explain in two words. So symmetry in a big sense. I cannot, it's not for me to decide what's the main contribution is. I mean I have several works which I like. It's like which one of your children is your favorite. It's a tricky question. But I guess judging by the fact that we have a school in supersymmetrical localization, this is probably my work of 2002, where I introduced the method of using supersymmetrical localization to compute the partition functions of the theories which Zabrik and Witten studied in 1994, which actually led to the mathematical proof of their statement. I had to rely on the help of my friends mathematicians, namely most strongly on Andrey Okunkov. So we wrote a paper in 2003, a year later, where we proved using the computation which I had done a year earlier that what Zabrik and Witten did was correct. And then it led to various generalizations and new directions of research. Some of them are discussed at this school. So that's probably the most influential work. So it's anticipation of discovery. And when I say discovery, it need not be something big, something about which newspapers will write. It's my personal discovery. You might compare it to the excitement of traveling, seeing around the world. If you see exotic places, find interesting people, but I'm blessed with the opportunity to do that without actually stepping out of my office. It's not people I discover, it's formulas. So I'm both blessed and handicapped in liking formulas. So that's what drives me. And actually it's very funny. I cannot really explain what is really the driving force. Sometimes I just know that I have to sit down and do the calculation even though I don't know what it will lead to, but it's something inside me. So it's both good and bad because you have to separate yourself from society for a while to do that. You become socially awkward because you have something internal going on and you can't really be always present when you need it maybe for your family or for your friends. And then also it makes it miserable because it may take a long time and there is some frustration, you try and you try and you try and it doesn't work and there is some stupid mistake or you can't find this mistake and you know that this should be correct but when you actually write the formula it doesn't work or when you try to check yourself on the computer something doesn't work. But then if you succeeded after some long period of frustration that makes it even more exciting. So when you want something and you have to really work hard to achieve that that's the best thing that can happen to you. Recently I spent two weeks checking a formula which I conjectured and two weeks with the help of a computer. So the formula had, if I remember, it was a particular example but to check that I had to make a sum of more than 2,000 terms so it's impossible to write them all in a piece of paper but even to feed them into a computer in kind of a reasonable way I had to split the problem into many sub-problems and so two weeks of fear that maybe after you've done this all it will not work and then if it doesn't work you have to find out whether it doesn't work because the formula was wrong maybe you made a mistake because when you have 2,000 terms it's easy to make a mistake. And so it wouldn't work, it wouldn't work and then I had to go on a trip with my son and then in some hotel room at night it finally worked. It was so exciting. But I couldn't wake him up to tell him that. So it's kind of funny that you're excited because the only person you can share it with maybe there are two or three people in the world you can share this excitement with but eventually maybe it will become more important, yes. It is a tough call and many people say that people like me are not physicists at all we are the best mathematicians and then most mathematicians don't think we're mathematicians we use physics language and physics way of arguing so we're not rigorous enough mathematicians so we're not mathematicians neither so we're somewhere in between and it's the same about nationality so we are here in France and I was born in Russia and I work in the United States and it's all kind of melting and mixed lack of identity, lack of nationality lack of clear goal but it works so somehow I know inside of me I know that what I'm doing is right and there is some beauty to this and to me the beauty of what we write is the most important thing so I mentioned formulas formulas is language in which we express our findings and these are like little bricks in the big building which we are building and eventually when we are done we will be able to confront this with nature, with experiment maybe it will happen next year maybe people who look at the early universe using the map of the cosmic microwave radiation will see some features which tell us that these are the features of quantum gravity at the early universe maybe it will happen in 50 years I don't know this is a long route but it's not the first time that humankind is faced with long projects to build a cathedral the Cathedral de Charte for example it took I don't know how many years 100 years and there were people who were just piling up stones and there were people who even though they were piling up stones knew that they were actually building the Charte Cathedral so I'd like to think that I'm building a cathedral or something like that but it may end up being just a pile of stones who knows it's a question of believing in yourself and I believe