2014-12-94

Interviewcentury between us, we apparently learned to programat the same time….…and then you could write simple code that producedgraphics as good and sophisticated as was commerciallyavailable.And this is not true today.Definitely not; the learning curve is much steeper. Backthen, you could be self-taught and self-contained. Nowyou have to do it much more modularly, invoking alreadyavailable programs.This definitely takes the fun and charm away from it.Programming can be a very good pedagogical wayof implementing mathematical ideas, provided youdo it from scratch. If you just push buttons, invokingalready available tools, it will of course be muchmore efficient but you will be bored. It is like doingmathematics by combining theorems which you donot understand but instead treat as black boxes – goodfor getting on and getting results but ultimately selfdefeatingas far as mathematical enjoyment is concerned.But returning to encountering mathematics:when I was young, it was classical Euclidean geometrythat triggered my interest. I was fascinated by theway you could reason logically and compellingly – inmany ways a moral insight. Did you have anything ofthat? It has been removed from Swedish curricula fora long time.If you mean proving that different angles are equal, usingthe congruence theorems and such things, we wereexposed to it but it was never pursued further.So it did not make too deep an impression on you?Not really.Programming is about the same thing: implementingsmall logical steps.But what really made an impression on me was Cauchy’sresidue formula. I was very impressed; it seemed to comeout of the blue. Before, when studying mathematics, therewere no surprises. You more or less understood what wascoming and how to prove it. But this was very different –so totally unexpected.It is only when you get to analytic functions that theelement of magic enters mathematics, when you realisethat there are very deep connections.This is true.What were your interests besides mathematics?Physics and computer science. I actually studied physicsand wrote my thesis on physics, but really it was moremathematical and my thesis advisor was more of a mathematicianin spirit.You did not pursue computer science?No. As I indicated to you, in the past amateurs couldproduce codes that provided graphics on a commerciallevel. I simply imagined that I knew everything there wasto know and saw little point in starting all over again. Iknow in retrospect I was being unfair.Perhaps, but not really. There is a much richer culturein mathematics than you can find in programming. Infact, I suspect that early on your interest in programmingwas provoked by mathematics. Mathematics doesprovoke so many excuses for programming, making ittangible.That is true. Still, I did consider a career as a commercialprogrammer. I knew it would provide a good salary andallow me to live a very comfortable life.As we discussed, you do not get stuck in programmingthe way you do in mathematics. The challenges can alwaysbe met.The academic world struck me as rather harsh and I worriedthat I might not make it. I decided to give it a chance.I applied for a post-doc grant and I used the money toattend a special year arranged at Warwick where I hadpreviously attended a special year devoted to stochasticpartial differential equations. In fact, Warwick is aboutthe only place in England such things are being done.Yes, I know about those special years. They have beenarranged for almost 50 years I believe.Yes, more or less since the university was founded. It isone of the very best universities in England as well.And you got stuck there.I would not put it that way, but it is quite interesting howI got to end up there.You married a UK woman?More or less. My wife is actually of Chinese origin, butshe did her PhD in England on an exchange programmethat was rather unusual at the time (during the late1980s). She also spent time in the States before returningto the UK. But another reason was that my researchwent very well. As it turned out I and a friend ended upin some kind of competition: what we were doing wasalso of interest to other people, and there was a preciseconjecture many different teams wanted to prove, manyof them quite distinguished. But we had a good idea andfelt that we had an edge.So the competition stimulated you? This is not so commonin mathematics, where people tend to fan out, accordingto the image formulated by von Neumann, andthere is often no one else doing what you are trying todo. It makes for peace and quiet. I suspect that the physicistsare far more focused.They certainly are. The main thing about the competitionwas that it certainly made us finish up much faster thanwe would ordinarily have done without this pressure.And then it caused a minor sensation and I was hailed asan upcoming young star.In other words, your luck was made. I guess this was thereason you got tenured only two years after your PhD.44 EMS Newsletter December 2014