J. Michael Kosterlitz

Zierler:

This is David Zierler, oral historian for the American Institute of Physics. It is January 7, 2021. I’m delighted to be here with Professor John Michael Kosterlitz. Mike, it’s great to see you. Thank you so much for joining me today.

Kosterlitz:

You’re welcome.

Zierler:

To get started, will you please tell me your title and institutional affiliation?

Kosterlitz:

My title is the Harrison E. Farnsworth Professor of Physics at Brown University.

Zierler:

Now, do you, or does your position, have any particular connection to the Farnsworth family?

Kosterlitz:

I presume it does. I’ve never actually investigated. All I know is that it gives me $4,000 a year of a slush fund (laughter).

Zierler:

(Laughter) Mike, I’d like to ask, to get started, a sort of very present question, and that is: in what ways has the pandemic been a challenge for your research, and in what ways perhaps have you been able to be more productive than you otherwise would be in an in-person physical environment?

Kosterlitz:

Well, the pandemic hasn’t really affected my research very much, but what it has affected is this remote teaching, because that requires time to produce lecture notes, which take forever to construct, as I’ve been used to just lecturing with a couple of hand-scribbled pages of notes, just to make sure they can get the equations correct, because I don’t trust myself to derive them on the board (laughter).

Zierler:

But the physics, you’ve been able to keep up the research. That hasn’t been affected.

Kosterlitz:

Well, some of it. I mean, I’m sort of at the end of my career, so I’m really not doing that much in the way of research, except reading papers and thinking about things.

Zierler:

Well, let’s take it all the way back to the beginning. You have a remarkably interesting background, so of course, first I’d like to start with your parents. First, please tell me a little bit about where they’re from.

Kosterlitz:

Okay. My father worked in the Charitee hospital in Berlin. Both my parents are German, although I was born in Britain, I don’t have a centiliter of English blood at all. I’m pure German. And so, my father, in about 1932, realized that that life wasn’t too good, because he came from a Jewish family although he didn’t practice the Jewish religion. And he suddenly discovered that Hitler allowed him to work, but not to be paid. So, he decided things weren’t good in Germany and negotiated with some of his contacts in Britain and got offered a job- several jobs. But there was one in Aberdeen, Scotland, which was a permanent job. So, he accepted that because security was important to him under the circumstances.

Zierler:

Mike, he was married at this point, or he was single?

Kosterlitz:

No, no. He was single. He had a girlfriend, of course, who was the woman who became my mother and she joined him a year or so later and they got married in Glasgow in Britain in 1934 or so. And I was the eventual result in 1943 (laughter).

Zierler:

Where did they meet?

Kosterlitz:

They met in Berlin, because my father had access to concert tickets, and so he was very popular with the opposite sex, because they liked to go out and listen to music and stuff. So, that’s how they met, basically.

Zierler:

Was there family that he left behind and who was subsequently lost during the war?

Kosterlitz:

Yes, quite a few, because essentially none of my father’s family survived. One or two of the family survived because they had already moved to the United States, but otherwise, it was not a good thing.

Zierler:

Mike, of course you were too young to remember, but I wonder if your parents talked about their experiences in Aberdeen during the war.

Kosterlitz:

No. My parents were basically too upset to even talk- they never mentioned Germany. I mean, I knew they were German of course, because German was the secret language which I wasn’t supposed to understand. But otherwise, they never talked about their life in Germany.

Zierler:

Growing up, were you Jewishly connected at all? Did your family retain any observances?

Kosterlitz:

No. No. I mean, my mother came from a right-wing Aryan Christian family. My father came from a Jewish family, Jewish background, so they couldn’t marry in Germany and so eventually married in Scotland. My mother used to drag me to church every Sunday while my father read the Sunday paper at home or in the car.

Zierler:

What career did your father settle into in Aberdeen?

Kosterlitz:

He was a physiologist, so he continued teaching physiology at Aberdeen University, and eventually over the years, he transformed himself into a- what do you call it, a neuropharmacologist.

Zierler:

Growing up, did you have a sense of what it meant to be a scientist from your father? Would he involve you at all in his career and his studies?

Kosterlitz:

A little bit. Yeah, I used to visit- he used to take me occasionally to his lab, and I would wander around and be very impressed with all the things going on there. And I was thinking, not a bad way of making a living, until I found a dead cat in a wastepaper basket with its brain exposed. And I decided: nope, that’s not for me.

Zierler:

Physics is a lot cleaner (laughter).

Kosterlitz:

Yeah. Right (laughter).

Zierler:

Mike, what was your early schooling like? What kind of school did you go to as a small child?

Kosterlitz:

Okay. I started my school career at a nursery school, which was basically mostly a school for girls. And then I went to a grammar school called Robert Gordon’s College, which at the time was a single-sex boys’ school. I went there when I was about four or five.

Zierler:

In middle school and in high school, were these large schools or smaller?

Kosterlitz:

This was- I don’t know. It was a biggish school by British standards, but by American standards, it was small.

Zierler:

And how would you describe your education, your curriculum in math and science? Was it strong?

Kosterlitz:

Not really. I do remember our guy who tried to teach us physics in high school. He had the name of Boozy because of his very red nose, and he really didn’t know much about the subject at all (laughter). The thing is that, at school, I enjoyed the math and science classes. At least, I wasn’t bored out of my skull. But the other subjects, like history, geography, humanities, etcetera, etcetera, I discovered that my memory couldn’t cope with them, because I seem to have a rather poor memory. I like to say that I can remember a maximum of ten facts, but I’m not too sure about the last four. So, if I can’t basically derive everything from six facts, I’m lost. So, the math, physics, etcetera, that suited me, because I could reconstruct almost everything from a very small base of knowledge, whereas with the humanities, I just couldn’t. There’s too much memory involved.

Zierler:

Was going to Cambridge a specific goal of yours, or a dream of your parents for you?

Kosterlitz:

It wasn’t particularly a goal of mine. I remember my father- my parents seemed to be very pleased with how I was getting on at school, and they said: you should be able to get into Cambridge, but in order to do that, we’ll have to send you to school in Edinburgh for a couple of years, because to get into Cambridge at the time, you had to do a set of exams, which the Aberdeen schools didn’t do. To get into Cambridge, you have to have A levels and higher S levels, whereas the Scottish schools only did the so-called Scottish Higher Leaving Certificate, which was considerably below. And so, I went to the school in Edinburgh for a couple of years and then managed to get myself a scholarship to Cambridge. So, that’s where I went.

Zierler:

Now, in the British system, you declare a focus or a major right away. For you, did you know it was physics from the beginning?

Kosterlitz:

Oh, yeah. Sure. Sure. Oh, yes, yes, yes, because that was the only thing I was really interested in doing was the mathematics and the sciences. In Cambridge, it’s called the natural sciences, and so that’s what I went for. I took physics, chemistry, biochemistry and mathematics. In England, I was able to quit everything which I disliked except these at age sixteen.

Zierler:

To the extent that physics is not immune from trends, what were some of the most exciting things among the faculty during your time as an undergraduate?

Kosterlitz:

I don’t really remember. All I really remember was the first few classes in physics that I went to in Cambridge, I got pretty bored, because I had actually done it all at school. And so, actually at Cambridge, I stopped going to lectures, simply because they weren’t telling me anything new, and I got corrupted by the sport of rock climbing. And so, that’s what I spent all my time doing- I found I enjoyed it and was quite good at it, so that became my main interest in life.

Zierler:

(Laughter) To the extent that you were exposed to both the theoretical and the experimental side of physics as an undergraduate, what did you gravitate more towards?

Kosterlitz:

Oh, the theoretical side, because the experimental side of physics as an undergrad was horrendously boring compared to chemistry. You see, all the experiments were basically set up, and all I had to do was press a few buttons and pull a few levers, and the experiment sort of worked. Chemistry was more fun. I used to have fun in the chemistry lab, because the particularly- at school, because a long time ago, in the lab, I was sitting on stools at a lab bench, and there was a shelf- a couple of shelves going down the middle of the lab bench, and on that were a selection of chemicals all of which would be forbidden today. And so, I amused myself by mixing all these chemicals, pairwise. I got some very interesting effects from it. I must have cleared the lab at least six times, and once I actually cleared the whole building (laughter).

Zierler:

And in those days, was it solid-state physics that you mostly focused on?

Kosterlitz:

Oh, no. No, no, no, because when I was at Cambridge, the only physics that interested me was high-energy physics. It’s rather ironic, because I was actually offered a space as a graduate student with Nevill Mott, later Sir Nevil Mott, who was a famous solid-state physicist. But solid-state physics never really turned me on. I don’t know why, because it’s quite ironic, because that’s the field in which I eventually got a Nobel Prize. But at the time, I didn’t like it. I was into the high-energy physics, field theory, and stuff like that.

Zierler:

Was the culture of the department at the time, as an undergraduate- were you able to develop meaningful relationships with professors, or they were too far removed from undergraduates?

Kosterlitz:

Oh. Well, I thought they were too far removed. I’m sure that I could have, had I been interested, but remember that my main interest was actually rock climbing, so I wasn’t terribly interested in the academic side. I was more interested in going to climb rocks all the time, and buildings, and so on (laughter).

Zierler:

Mike, how then did you make the decision to pursue physics at the graduate level?

Kosterlitz:

It seemed like an obvious choice, because of all the subjects, physics seemed to suit me the best, because not too much memory was required. I had some little ability at making logical conclusions from a few facts which seemed to suit my way of thinking. I enjoyed mathematics, but I hated pure math. I hated the pure math side of it, because I could never understand why the mathematicians insisted on proving that two plus two was four, and things like that. Because I thought: look, it’s obvious, John. Take your fingers and, one, two, three, four (laughter). That’s it. So, I could never understand why mathematicians made such a meal of proving obvious statements (laughter).

Zierler:

(Laughter) Mike, I’m curious. When you were thinking about graduate school, if you got any specific advice one way or the other, if it was best to stay at Cambridge or to leave.

Kosterlitz:

Oh. No, that was very simple. Of course, the advice was: stay at Cambridge. But in my case, you see, remember that my main interest was the rock climbing, so I actually didn’t go to classes very often. I didn’t study. And so, when the final year came ’round on which everything depended, five weeks before the final exam, I didn’t even know what the syllabus was. And so, I had to frantically ask all my friends: could I possibly borrow your notes for a week or two, so I could read them? And then I was faced with the final exam. I don’t know if you’ve looked at the Cambridge Tripos exams. They are- the questions are non-trivial. But you know, because the English education, in my day, seemed to be quite narrow, but in great depth and so, I was very good at- pretty good at doing a certain narrow set of things. But I didn’t have much in the way of breadth. And so, the English in my case was very different to say, American education, which is not so deep, but much broader.

Zierler:

Was the motivation to go to Oxford by reputation, or was there a particular professor you wanted to work with as your graduate advisor?

Kosterlitz:

No, just the reputation, because basically, it was the second best (laughter).

Zierler:

(Laughter) What year did you get to Oxford? Would that have been the fall of ’66?

Kosterlitz:

Yes, that’s exactly right. Yeah. 1966.

Zierler:

And how did you go about developing a relationship with your graduate advisor and choosing a specific field of research to work on?

Kosterlitz:

Yeah, that was a bit weird, because we were all assigned an advisor, and then you were put in an office with other graduate students, and basically in my case, left on my own to sink or swim. So, I developed some friendships with the other graduate students who worked on various problems together, with no input from the advisors. I guess that was a very painful bit of my education, but in later years, it stood me in good stead, because I was forced to develop some ability to come up with my own problems. I had to, as a graduate student. Then, this was very useful in my later career.

Zierler:

What was your specialty? What did you focus on for your thesis research?

Kosterlitz:

Okay. It was a bit of high-energy physics. Oh, I remember what it was. It was — you’ve heard of the Veneziano model?

Zierler:

Sure.

Kosterlitz:

Dual resonance models? Alright. So, that was what I worked on. And I wrote a couple of papers on it, but I suspect that only about two or three people have read them (laughter). You know, myself, and my advisor. That’s it.

Zierler:

Mike, on the social side of things, being at Oxford in the late 1960s, were you involved at all in student protests or the counterculture, or anything like that?

Kosterlitz:

Not explicitly. I had friends, of course, who were into this sort of thing. But remember, in my spare time, all I wanted to do was climb rocks.

Zierler:

(Laughter) You didn’t break the habit as a graduate student.

Kosterlitz:

No. No. I was as mad as ever (laughter).

Zierler:

I’ll test your memory: who was on your thesis committee?

Kosterlitz:

My advisor was called John Taylor. I remember that much. Of course, the only problem was there were two John Taylors here in high-energy physics. One was quite well-known, but I was a student of the other one (laughter). And as I say, you know, I wasn’t terribly enthusiastic about what I was doing, but it was something to fill in my time.

Zierler:

To the extent you thought about such things, looking back at your thesis research, what were your principle conclusions, and what did you think you had to offer physics as a career?

Kosterlitz:

Actually, I didn’t think I had anything to offer, because I couldn’t quite understand why I was doing what I was doing. It’s just that I was able to actually push it through and do some of the silly calculations. You see, it was a bad time in physics, because it was before the days of gauge theories, and people were just sort of spinning their wheels. You know, it’s just one of the situations where there was a lot of very smart people in the field but not making any progress, and just going ’round and ’round and going nowhere. So clearly, they weren’t doing the right things. And then shortly after I changed over to condensed matter, gauge theories came along and a lot of big strides made.

Zierler:

Would you say that your graduate education and background in high-energy was useful later on to the transition to condensed matter?

Kosterlitz:

Not useful- I didn’t learn anything useful, but you know, at least it trained me to do long, tedious calculations and not make too many mistakes. So really, it didn’t teach me that much about what was interesting. I didn’t get really excited about physics until I ended up at Birmingham. At first, after Oxford, I went to Italy as a postdoc and got one of these Royal Society fellowships which I could take anywhere in Europe.

Zierler:

What was the host institution in Italy?

Kosterlitz:

Well, this was- I could take this thing to anywhere I wanted to, and I so chose very carefully, so I went to Torino in Italy, because that was nice and close to the mountains. And it just so happened that the physics there was quite good as well, which was a bonus. But the main reason I went there was because of the mountains.

Zierler:

I’m curious, Mike, given your research on Regge poles in the Veneziano model, if you ever thought to be engaged more fully in string theory as it was developing.

Kosterlitz:

No, because when I was struggling with these Veneziano dual-resonance models, string theory hadn’t been ever thought of, and it wasn’t until much later that I realized that what I’d been doing was basically exactly, more or less, what string theorists were doing. But by that time, I was into condensed matter, and so I wasn’t interested anymore.

Zierler:

How long were you in Italy?

Kosterlitz:

One year.

Zierler:

And how did the opportunity at Birmingham come available to you?

Kosterlitz:

Oh, that was because the obvious place to go for a high-energy postdoc, to go after Italy, was to go to CERN in Geneva.

Zierler:

Yeah.

Kosterlitz:

So, that’s where I intended to go. But being somewhat- I tend to procrastinate a lot, I turned in my application rather late, and got the reply: sorry, all the desk space is taken. Try again next year. So, I now faced unemployment, and at the time, I shared an apartment with another English postdoc and my girlfriend, who is now my wife. And when I got this reply, I sort of was a bit horrified, so I explained to my girlfriend what had happened, and she looked at me in some contempt and walked about a mile down to the railway station where you could buy English newspapers with academic job adverts in them. She came back, sat me down at the kitchen table, put the job adverts in front of me, and said, “Apply.” So, I did (laughter). And one of the few jobs that were available was a three-year postdoc in Birmingham, so I applied for it and was offered it. It was one of the few offers I got, so rather reluctantly, I accepted it.

Then a couple of weeks after I accepted the job, I got a letter from CERN saying, ‘we’ve now decided that we’ll have two people per office, so you can come.” Now, I was all set at this point to renege on Birmingham and go to CERN, but my father and my wife were very much against this, because they said: “no, you can’t do things like that. Since you signed the contract, you’ve got to honor it.” And so, I ended up going to Birmingham although Birmingham was actually the last place I wanted to go to. Remember that my main interest in life was mountains and rock-climbing. Right? And Birmingham was a big, dirty, industrial city in the flat middle of England, without a mountain in sight, and so it was the last place in the world that I wanted to be.

Zierler:

Although, perhaps that was good for your career, to not be around mountains.

Kosterlitz:

Oh. I mean, I had no idea at the time, but of course professionally, it was the best move I ever made. You know, it couldn’t have gone any better place professionally. But, at the time, my main interest was mountains and climbing so I didn’t want to go to Birmingham. I really wanted to go to Geneva, because that was close to some nice mountains and so on you know, but I was dissuaded and went to Birmingham. And so, there I continued doing these tedious calculations in high-energy physics for probably zero return. Twice, I had just finished a calculation and was about to start writing it up for publication, when the preprint doing exactly the same thing arrived on my desk. The first time, I just shrugged my shoulders and said, “Okay. These things happen.” Two months later, exactly the same thing happened, so I sort of threw my hands up in disgust and said, “I can’t compete with a group of people at Berkeley, doing exactly what I’m trying to do.” So, I started walking around the department at Birmingham, asking everybody I came across, “Do you, by any chance, have a problem that I might look at?” And the answer was “no,” until I got to David Thouless’ office.

Now, I have to explain something here, because David Thouless had a hell of a reputation at Birmingham as one of the most difficult people to talk to, because he was unfriendly. He could put you down and make you feel like a fool. So, I was a little bit nervous about knocking on his door and asking him if he had a problem. So then, I went in there, and he seemed to be quite reasonable, and started explaining something to me. He started writing on the board. After a half an hour, I realized that I hadn’t understood a thing, and that I had to stop him and try to get him to back up a bit, because I was wasting both his time and my time. So, then I said, “Sorry, I’ve got to stop you there. Could you please tell me: the first equation you wrote on the board- where did that come from?” And he turned around and looked at me, and said, “Didn’t I tell you that?” And I could honestly say, “No, you didn’t. That’s why I’m lost.” And he said, “Oh.” Then he proceeded to give a very clear explanation of what his problem was and what he was doing.

And from that point on, we got on very well together, because I lost my- you know, I was very afraid of him, because this guy- remember, this guy, his mind seemed to operate from a different level to normal mortals. And so, the general opinion that he didn’t suffer fools gladly was certainly true, because basically everyone else, compared to him, was a fool (laughter). So, I got over my fear of being a fool, and I could ask him stupid questions, which are always the best questions to ask. And from that time on he didn’t seem to mind being asked what were, to him, probably stupid questions, and we got on very well together from that point on.

Zierler:

Mike, coming from high-energy physics and then walking into David’s office that first time, what were some of the major gaps in your education and experience that didn’t give you a fighting chance to understand what he was saying?

Kosterlitz:

You know, actually that never crossed my mind that I was at this huge disadvantage not knowing a thing about the- I really didn’t know that much about condensed matter. But the things he was talking about were so different to the normal standard wisdom in any field, that it didn’t matter that I was starting from scratch and didn’t know anything about what he was talking about, because nobody else did, either.

Zierler:

What was his research? Do you remember what he was working on specifically at the time you got to know him?

Kosterlitz:

He mostly worked in localization theory, electron localization. You know, electrons moving around, the random potential, that sort of thing. But he was interested in all sorts of things. What he was particularly interested in at the time was the question of superfluidity in two dimensions. And of course, the superconductivity thing, you know, phase transition in two dimensions. But this was fine, because in order to make any progress in this field, everybody was starting off from ground zero because, you know, all the standard wisdom about phase transitions simply didn’t work in two dimensions.

Zierler:

Mike, I wonder if, given how much of a novice you were to this new branch of physics to you, and given how intimidated you were by David initially, even though you were a postdoc, I wonder if your relationship with him was more akin to that of a graduate student and a mentor.

Kosterlitz:

I suppose it was. But you know, eventually it got to the point where we were — you know, in this field, at least we were equal collaborators, simply because so little was known about this subject at the time, and we were approaching it from a completely different viewpoint. You know, the usual wisdom about phase transition was that you started with the theory of the disordered state, and then you looked at the fluctuations, and you found that something funny happened. But in the two-dimensional system with continuous symmetry, like a superfluid, the fluctuations were violent at all temperatures which destroyed long-range order. In other words, there’s no ordered state, and the gurus of phase transition, Lev Landau and so on, had told us that the low-temperature phase had long-range order. But there was a rigorous mathematical theorem that says that such systems, a two-dimensional superfluid, has no long-range order at any temperature. And so, this seemed to exclude the possibility of phase transition, because we assume that a phase transition is a transition from a state of long-range order to a state of only short-range order. But since this system had no long-range order at any non-zero temperature, there was obviously no phase transition. At least, that’s what theory said.

But as Thouless pointed out to me, these experiments- come on. Look, there’s all the experiments here which clearly show it’s a phase transition in a superfluid helium film, which is completely contrary to any present day theoretical knowledge. And so, this was a huge mystery. It was a major conflict between theoretical wisdom and experiment, and it needed sorting out, because there was no question but that the experiment showed that, damnit, this system did become superfluid. And so, this was the problem that Thouless basically suggested that I look at. And so, since nobody knew anything about this system except there’s this conflict between fairly elementary theory and observation, I was as good a person as any to look at it (laughter). Then, I might even be able to solve it.

Zierler:

But Mike, surely it was more than that. I mean, it sounds like the dominant theme of your academic career, up to this point- up to the point of meeting David at Birmingham was one that really lacked direction or passion for you, in high-energy physics.

Kosterlitz:

Oh, yes.

Zierler:

And so, that begs the question: what was it about phase transitions and superfluidity that turned you on to this subject?

Kosterlitz:

Oh, well. I mean, the thing was that this was- these were the last great problems in condensed-matter physics, you know, dealing with strongly interacting fluctuating systems.

Zierler:

So, this is to say, you saw an opportunity to be right in the middle of fundamental work, whereas in high energy, that was not necessarily the case.

Kosterlitz:

Right, because in the phase transition, critical phenomena game, it was clearly- theoretical progress was being made. You know, Ken Wilson’s renormalization group, and stuff like that. But the two-dimensional systems, except the Ising system were a big mystery. But this was completely different from, as far as I was concerned, to whatever I knew of high energy now, because high-energy physics was all related to complicated perturbation theory and stuff. And so, it was clear that the perturbation expansion wasn’t going anywhere, at least, not for me.

And I couldn’t understand why people were trying to calculate, you know, you could calculate two-loop diagrams with some work, and three-loop, four-loop, etcetera, were almost impossible. But that was what everyone was doing, it seemed to me. It seemed like a complete waste of time and effort. You know, these incredibly complicated, difficult calculations, all you were doing was calculating one more term in some stupid expansion, which obviously was asymptotic at best. I mean, even as a non-mathematician, I understood exactly why these perturbation expansions couldn’t converge because you’re expanding a singular point. And so, unless you could do something exact, or quasi-exact, you weren’t going to get anywhere. That’s why I just thought- you know, people were just being ridiculous, spinning their wheels. And it wasn’t till I read some of Ken Wilson’s stuff that I realized that this weird and wonderful technique of the renormalization group could actually tell you something.

Zierler:

Mike, at what point did you transition from being essentially a novice, and clueless as to what David was doing, to being a collaborator who he found useful?

Kosterlitz:

I suppose when I started doing- okay, one of the papers that David threw at me was this paper- these set of papers by Phil Anderson and Gideon Yuval, who actually solved this one-dimensional, 1/r² Ising model and showed that this thing had a transition. And I looked at this paper and spent about six months actually reproducing the calculations and thought: this is interesting, because the excitations that this paper concentrated on seemed to be similar to the important excitations in a two-dimensional superfluid. And so, I learned Anderson’s renormalization group technique, what he called “poor man’s scaling,” which he applied to the Kondo problem and managed to modify this to work for this two-dimensional problem. Because, you know, vortices also have a logarithmic interaction, and I managed to modify this one-dimensional calculation to this two-dimensional system, and we succeeded in getting somewhere with that.

Zierler:

Mike, what was so revolutionary about Ken Wilson’s renormalization group?

Kosterlitz:

It enabled one to understand what was going on at a phase transition and is a method of dealing with these strongly interacting fluctuations. You know, okay, it was basically perturbative, but Wilson’s renormalization group was a very clever way of summing up exactly the set of diagrams needed to make some progress with this problem. But it’s a very strange way of doing this resummation, and then I realized that basically it’s a brilliant way of reducing all the complicated physics down to a very simple set of equations, and if one could do this, you could actually get some interesting information out.

Zierler:

How did you become aware of Phil Anderson’s work, and what impact did that research have on what you were doing?

Kosterlitz:

Oh, it had a huge impact. I mean, as I said, David Thouless threw a lot of papers at me that he thought were relevant to the problem we were working on and said: read these, and they might be of interest. So, as I said, I did read them and when I understood these papers by Anderson and Yuval, I realized that if I was lucky, I could extend what they’d done to my two-dimensional system, and it worked.

Zierler:

Did you ever think that a place like Bell Labs would make sense for you as a next move?

Kosterlitz:

Sure. I mean, I applied there, but I wasn’t accepted. It was probably a good thing, because shortly after, Bell Labs fell apart. You know, because I was quite keen to work with people like Halperin, Hohenberg, and so on, who were at Bell Labs at the time, because they were doing a lot of stuff in critical phenomena, which was what really intrigued me. But you know, I applied, but not seriously. I wasn’t successful. But actually, at the end of the day, Birmingham was the best possible place for me, because I was under the mentorship of this guy who never got- well, he does have a lot of the credit now, but at the time, he never got really the credit for what he was doing, and he was brilliant.

Zierler:

Perhaps his personality had something to do with that.

Kosterlitz:

Yeah, it did. But as a physicist, he was just out of this world.

Zierler:

How did the opportunity at Cornell become available to you?

Kosterlitz:

David suggested that, after my three years at Birmingham, I should go to Cornell. He thought he could get me into Cornell to broaden my outlook on physics. And so, I got an offer for a postdoc from Cornell. And so, I went there, and I had a wonderful year there.

Zierler:

And was the specific motivation to work with Michael Fisher and Ken Wilson?

Kosterlitz:

Well, yeah. The idea was to learn more about phase transition and critical phenomena. But of course, that’s where I met David Nelson. At the time, he was this incredibly smart young graduate student. He was Michael Fisher’s graduate student. We got on well and did some work together. The thing was that, surprisingly, nobody at Cornell really understood what David Thouless and I had done. The only person who really understood and appreciated it was David Nelson. And so, we got quite close and friendly and we worked a bit together.

Zierler:

And what was it about Nelson that gave him this appreciation that the others didn’t have?

Kosterlitz:

He was just brilliant. I mean, his mind was very fast. He was one of these people that basically knows everything about everything and has a very fast mind. So, give him a calculation, and he’d do it.

Zierler:

Now, was this your first time in the states, when you first arrived at Cornell?

Kosterlitz:

It wasn’t the first time I’d been there, but that was the first time I’d spent any time at Cornell. Yes.

Zierler:

Now, to the extent that one department, you can extrapolate overall national impressions, I’m not sure if you can or can’t but on a cultural level, what were some of the differences that you detected in Ithaca than what you had gotten previously at Cambridge and Oxford and Birmingham?

Kosterlitz:

Oh, of course there’s one major cultural difference, and that was that in Britain, one worked for a department in general. Well, that was the impression I had, that you worked for a department, not for a particular person, whereas in the states, it was definitely you worked for a person, because you’re on their grant money. It’s funny, because I’m not sure which is the better system, because relying on grant money is a very- how should I say- it’s a very tenuous existence, because the grant can be cut off at any time. But at least this grant system keeps the principal investigators on their toes, (laughter) because of the competition for money. But of course, this competition for money is both a good thing and a bad thing in that there are a number of very smart people who are simply, if you like, not in the in-crowd, and so they are out of the granting. They can’t get grants. Whereas in Britain, since money comes to the department, if you’re there and with tenure, you get research money no matter how good or how bad you are. And so, there’s no real incentive to keep going. You know, so basically, I know a lot of people in Britain, although they’re so-called professors, they’re actually not doing anything (laughter).

Zierler:

Mike, your collaborations with Nelson and Fisher led to such foundational work. Just as a matter of partnership, what did each of you add individually to the overall collaboration in terms of talents or research styles or approaches?

Kosterlitz:

Never thought about it. It was really- I suppose that the collaborations we had was because we just recognized that we were all working with other smart people, and we enjoyed it. So really, that’s — all I thought about was these guys. They’re very good. They can do things I can’t do; I can do things they can’t do, and we got on well together. I do remember the first time I met Bert Halperin, who of course had a hell of a reputation at the time as being something very special. For a while, for a couple of years, every time I met Bert Halperin, I’d be reduced to a babbling idiot, because I was so overwhelmed by him (laughter).

Zierler:

What do you see as your most significant research during your time at Cornell?

Kosterlitz:

Oh, it’s probably that work I did with Nelson and Fisher on these crossover problems and critical phenomena, the anisotropic antiferromagnets and so on. It was always one of the big things at the time, were these crossover problems and anisotropies and the interactions, etcetera, because some major effects. You know, this tiny- if you had a problem- you know, a magnetic system with, say, rotational symmetry, the slightest deviation from this in the interactions would make the ordered state different. You know, it changed the phase transition to a different universality class, if you wish. And so, this was an absolutely fascinating topic, as to why this happened.

Zierler:

Mike, as they say, “Ithaca is gorges,” G-O-R-G-E-S, I wonder if you were happy to be back in the mountains, and if you took advantage.

Kosterlitz:

Oh, sure. I met John Reppy there, who was also a very enthusiastic rock climber. So, we used to go quite often to the Shawangunks- It was a cliff in New York state and climb there. And we climbed together elsewhere in New England. And even- oh, yeah. One time we even tried to do the north face of Half Dome in Yosemite together, but the temperature was too hot and I just could not stand the heat so we had to bail out.

Zierler:

Mike, did you consider your next move to stay in the United States? Were you thinking about making a life for yourself, or did you know that you wanted to return back to Birmingham?

Kosterlitz:

Well, I was keen to stay in the states, but I had a permanent position in Birmingham. I was offered that. You know, I’d got the postdoc in Cornell, but also at the same time, Birmingham- I was offered a permanent job in a year’s time when I came back. And so, I decided to go for the permanent job.

Zierler:

“Permanent,” meaning that you came in tenured?

Kosterlitz:

Yes.

Zierler:

Had you done much teaching up to this point, or when you got back to Birmingham, that was the first time, really?

Kosterlitz:

No. I had done a little bit of teaching as a postdoc in Birmingham. So, teaching as a professor didn’t make much difference.

Zierler:

Now, did you keep up your collaboration with David Nelson?

Kosterlitz:

Yeah, we kept it up for a while.

Zierler:

What did you continue working on with him?

Kosterlitz:

The same things. You know, critical phenomena. But then he moved on to other things like biophysics, and I stayed in physics, so our collaborations sort of dropped off.

Zierler:

Did you keep an eye on opportunities in the United States? I know in 1978, you returned. In the intervening years, were your antennae up to the best opportunities in the states?

Kosterlitz:

Well, my life took a bit of a change then, because I was in Britain from 1974 to ’77 or ’78, and then I came down with this disease, multiple sclerosis. And so, I thought my life had sort of ended. Certainly, I had to quit climbing. So then, I became more interested in my career as a physicist. You know, up to that point, I had this double life. Half my life was as a climber. Half my life was as a physicist. Then, I had to quit the climbing part because of this disease. And so, I became a full-time physicist and got an offer from Brown, so I took it. And then, we moved to the states in- when was it? I got that offer in 1978 or ’79, but then it took a long time to go through the bureaucracy of immigrating, so I didn’t manage to move until 1982.

Zierler:

What was your first stay in the United States? What did you do first, prior to Brown?

Kosterlitz:

Other than postdoc in Cornell for a year, I had a couple of- I went to Bell Labs for a couple of weeks, and then Harvard for a couple of weeks. And then I was in Yosemite Valley for, I don’t know, a couple of months. So, that was my experience in the United States until I moved. Yeah, I actually liked America, because I liked the people, and I liked the scenery and surroundings, so I thought: yeah, I could make quite a nice life in the states. So, I- and then, of course, Britain became less and less attractive because of the cuts in funding for universities, Margaret Thatcher, all that sort of thing. And so, I removed to the U.S., and then came across Donald Trump (laughter).

Zierler:

Really?

Kosterlitz:

Yeah. So, actually, the politics in the United States is even worse than Europe.

Zierler:

That’s for sure.

Kosterlitz:

(Laughter) But what can you do?

Zierler:

Mike, broadly conceived, over the late 1970s and early 1980s, what were some of the major advances in research on superfluidity?

Kosterlitz:

Because basically, the two-dimensional superfluid stuff had been thoroughly understood, both theoretically and experimentally. The experiments done by Dave Bishop and John Reppy in 1977-78 basically verified the theory of two-dimensional superfluidity and then, of course, there were all these advances by Ambegaokar, Halperin, Nelson, and Siggia. That’s right. AHNS. And so, their theory was based on what I had done for the statics, so they’d extended it to dynamics. And when you use that theory to analyze the experimental data of Bishop-Reppy, which were done necessarily at non-zero frequency, the agreement was amazingly good. So, that could be taken as verification of the theory, because there’s no- I don’t think there’s any competing theory that could explain those results. And then, of course, there’s all the other work that was done so the work on superconducting films and you know, Josephson junction arrays and there was a theory that basically fit everything. So, this whole field was basically worked out in the eighties. And then, of course, there came along the Quantum Hall Effect and related stuff, and what are called topological insulators and so on. But that’s all quantum mechanical, and I have basically spent my whole career trying to avoid quantum mechanics (laughter).

Zierler:

(Laughter) So, when you got to Brown, you focused more specifically on Josephson junctions’ arrays.

Kosterlitz:

Well yeah, because that’s a very nice system to which I could apply what I knew about these two-dimensional systems.

Zierler:

What were some of your major findings with this research?

Kosterlitz:

I’m not sure if any of the findings were major. I don’t know if there was anything in particular. One of the things was that- I think it was very important- if you’re in that field was to have close ties with an experimental group working on these systems, because there’s some unusual features in the measurements which needed some explanations. You know, that was one thing- to go back to working with David Thouless- that was one thing that was very important, in that David taught me this very important lesson that basically it doesn’t matter how fancy your theory is- you know, how beautiful, how fancy it is, if the predictions don’t agree with the observation, then you’re wrong (laughter). So, you know, that lesson has really stuck with me, in that I’ve always tried, not very successfully, but I’ve always been interested in trying to calculate something measurable.

Zierler:

Mike, when did you meet Enzo Granato, and what was it about him that allowed for this to be such a productive and long-term collaboration?

Kosterlitz:

He came from Brazil as my graduate student. This was a long time ago. So, he was and is this very smart guy, and so we kept our collaboration going.

Zierler:

And what did you work on with him?

Kosterlitz:

Mostly things like Josephson junction arrays, and so on.

Zierler:

Did you ever look at any of your research as possibly having industrial relevance or application?

Kosterlitz:

No. No. I’ve never really been interested in the practical applications of the research I do. I mean, of course it’s nice to see that it does have some application, but it’s never been my motivation. You know, personally, I’ve got no feeling for experimental measurements. And so- well, I don’t really know what to say about this, because for me, the experimental, or practical applications are not a motivating factor at all. For me, the motivating factor always- okay, this is some strange effect, and we don’t understand what the hell is going on here. And so, that aspect always intrigued me. You know, can I explain something that is unusual and different? And again, I think I learned this when I was working with Thouless, because he was always interested in trying to explain some weird observation and cook up some incredible theory which explained it.

Zierler:

Mike, was your time at Saclay and D’Orsay, was that a productive time for you in terms of the research?

Kosterlitz:

Not particularly. You know, it was reasonably productive in that I sort of learned how to look at problems from a different point of view and so on. But I didn’t really make any contacts that really carried on.

Zierler:

When you returned to Brown, how did you get more involved in numerical work?

Kosterlitz:

Oh, that was very simple. It was because there were lots of problems that analytically just seemed to be too difficult, but were approachable numerically, so I thought: okay, if I can come up with some clever algorithm, maybe I can do a better job than what’s been done before. So, it’s a lot of things which are really not understood, which are sort of approachable numerically, but not analytically.

Zierler:

And is this how you became more involved in superconductivity?

Kosterlitz:

Not really, no. I mean, the superconductivity work was just trying to understand some general features of it, with no particular wish to- no particular object to understand anything in particular. You know, I just had the techniques to do something in it, and maybe we could explain some odd features. I mean, it was clear that the underlying theory was a bit strange, because you know, remember these two-dimensional systems, you’ve got these rapidly growing length scales, which can grow up to the size of the system quite easily. And in two-dimensional superconductivity and superfluidity, there are two diverging length scales at the critical point. One of them is much larger than the other, but they both diverge exponentially. And the question was: what effects do these diverging length scales have on the measurements? So, that was a problem that was intriguing and quite a lot of fun.

Zierler:

When did you get to know Tapio Ala-Nissila?

Kosterlitz:

He was a postdoc at Brown shortly after I arrived, and we became friendly, and we liked to look at some of the problems. And so, when he went back to Finland and had control of some money, it was quite useful, because that meant I could get my expenses paid in Europe (laughing).

Zierler:

And what kinds of things have you worked on with him over the years?

Kosterlitz:

Mostly just various phenomena in two-dimensions, and also in higher dimensions. You know, I got interested in basic growth problems. You know, if you have a- if you rain some atoms down on a surface, how does this system then grow? So, that was one problem we worked on. Then, you know, basically what we tried to do was try to measure numerically these so-called growth exponents. You know, how fast the height of an interface grew as a function of time, and stuff like that.

Zierler:

How did you develop your collaboration at the Institute of Advanced Study in Seoul?

Kosterlitz:

Again, that came because I had a graduate student, Jooyoung Lee, who was actually very, very smart and very good. And we got friendly, and he got this job in Seoul. And so, he was interested in inviting me to work there. So, I thought, never been there, so it sounds like a good idea.

Zierler:

(Laughter) When did you start vacationing in Sweden, and when did you want to establish a permanent residence there?

Kosterlitz:

Well, my wife’s Swedish. And so, she inherited a little summer house from her parents, and we still own it. And you know, I like going there and spending time there, just basically pottering around. You know, it’s got about an acre of land associated with it, and stuff like this. So, I enjoy pottering around, cutting the grass, and generally doing nothing. It’s very pleasant, as long as the weather’s good.

Zierler:

Mike, when did you become aware of what Duncan Haldane was doing?

Kosterlitz:

Oh, I’ve always been aware of what he was doing for a long time. It’s just that Duncan- as far as I was concerned, Duncan was one of these absurdly smart Cambridge graduates who was far too smart for me, and he was doing stuff that I would have loved to have done but couldn’t. So, I think we basically had a lot of respect for each other, but that’s about as far as it goes.

Zierler:

But you never worked directly with him.

Kosterlitz:

No.

Zierler:

Mike, given how broad your research agenda has been, what was the work prior to your work on exotic states of matter that was most relevant for the award eventually given by the Nobel committee?

Kosterlitz:

The thing is that I know that the prize was given generally for these exotic states of matter, but then I never actually worked on that. It’s just that some of the techniques that I developed during my research is relevant to this. And so, it was also the- Thouless and I were the first people to basically apply what the mathematician's called topology to some of these physical problems. Because I remember, back in the old days, when working on these vortices and two-dimensional superfluids, Thouless, who knew everything about everything, mentioned that, oh, yeah, you could call these vortices “topological excitations,” because if you take a system of one vortex which is in a different topological class to a system of no vortices, if you like. And so, this was my first introduction to the ideas of topology. I knew what a vortex was, but I had no idea that something I was working on had anything to do with topology. And then Thouless called it “topological excitations.” I said, “Okay. Whatever rings your bell”(laughter). “I’ll go along with it.” And so, that’s really how the connection between my work and these topological insulators and stuff- now just because we were the first people to introduce some of the concepts of topology into physics.

Zierler:

Mike, to the extent that the Nobel committee is conservative with regard to theory, insofar as they want to make sure that the theory plays out in the world of observation or experimentation- what were those proofs in the experiment that allowed the committee to say, “Okay, this is something that we’re going to recognize”?

Kosterlitz:

Yeah, because the theoretical prediction is so absolutely definite and inescapable. You know, you can predict a number, which is, within the theory, absolutely inescapable. If this number is measured and if the experiment disagrees with theory, then the theory is wrong. That would be all there was to it. But it turned out that the measurements were spot-on, agreed with the theory, both for superfluid Helium films and for the melting of some two-dimensional systems, solids, where you could make a very similar prediction based on doing the same calculation for dislocations, just more complicated. But in both cases, the predictions and measurements agreed completely.

Zierler:

Mike, as I’m sure you know, for some Nobelists, the buzz about whether they would receive the award comes year after year after year, and for others, it’s immediate. It’s a very sudden kind of announcement. What was your experience on this? When did you first start to perceive that there was a buzz surrounding your research that might ultimately be recognized by the Nobel committee?

Kosterlitz:

Okay. I remember when I was still at Birmingham, Thouless said, “What we’ve done is pretty good, and it may even be worthy of a Nobel Prize.” And I thought, “Oh, that’s interesting. It would be nice if it was.” And then all the developments and predictions started working out, and I kept on thinking: maybe, maybe, it’ll happen. I am aware that our work was nominated year after year from the early eighties onwards for the Nobel Prize. But it never happened, until I was on sabbatical leave in Finland. By that time, I had completely given up any thought of being awarded the Nobel Prize.

When the announcement came, we were in an underground carpark about to go up to the mall for a beer and a sushi lunch. And my cell phone went off in my pocket. And I sort of managed to dig my cell phone out and answered, and there was this Swedish accent came over: blah, blah, blah, Nobel Prize. And I sort of thought, “Did he actually say that I had won the Nobel Prize, or what?” I had no idea that this work was under consideration anymore. You know, I sort of just stopped thinking about it. Okay. We did the work in, let’s say, the mid-1970s, and this was now 2016, so this was, what, thirty-five, forty years later.

Zierler:

That’s quite a gestation period.

Kosterlitz:

A long gestation period. So then, as I said, it slowly penetrated through, what the guy had said, and I was sort of going- trying to struggle to say something, but I was so astonished that nothing came out. So, there was a thirty-second silence. And the only thing I can think of saying at the end was, “Jesus” (laughter). That was the end of the conversation.

Zierler:

(Laughter) Mike, clearly for Thouless in the mid-1970s to suggest that possibly this was Nobel-worthy work, clearly, he was something of a visionary in that regard. Not from an ego perspective, but that he recognized in the long-term what significance this research would have.

Kosterlitz:

Right. No, Thouless always was a sort of- I don’t know how you’d describe him, but he was always basically doing his own thing, and he was always ahead of the crowd. And I was incredibly- I really didn’t like being in Birmingham and working with Thouless basically made up for it. You know, I recognize him as somebody who was- as I said, worked at a different level to normal people. And so, that by his- basically, he was an amazing guy. He knew everything about everything and was- you know more than knowing it, he could actually use it all. And so, the problems he would look at were way ahead of the time. I mean, after all, he was responsible, basically, for these transitions by these topological excitations. He’s also responsible for- basically, his theory was a fundamental theory for these topological insulators. And so, Thouless was always somebody who was way ahead of his time in the field. And unfortunately, he didn’t really get the recognition for it. He was just the most amazing- he’s a genius. I considered him at least on the same level as Feynman, Schwinger, and so on, and so forth. Working with a mind like that was an incredible experience.

Zierler:

Mike, how did you deal with all of the attention and frenzy surrounding the announcement? Was it difficult?

Kosterlitz:

Well, I was on leave in Helsinki at the time, so it was okay. It was so surprising and so astonishing that the only thing I can say about it- it was different (laughter). You know? Because as I say, I had sort of stopped even thinking that the work that I’d been involved in would ever get a prize. I mean, you know, I’d been awarded- what’s it called, the Lars Onsager Prize, which I thought was pretty good. But then when the Nobel Prize came along, I was just- I was so astonished that basically I couldn’t believe it. And so then, from that point on, everything was just- I was just going with the flow, because it was so unreal. So, I just sort of went along, smiled in the right places, and shook hands, and was a pleasant guy, etcetera, etcetera. But it was all so unreal. I couldn’t even believe it.

Zierler:

Mike, in the years since, of course, the recognition by the Nobel committee is an order of magnitude greater than anything else in science. And so, that allows you a platform, if you choose to step on it, so to speak, to have a voice and talk about other issues beyond science, if you want it. I’m curious if you ever took advantage of that platform.

Kosterlitz:

I try not to take advantage of it. It’s just that- you know, since I got a Nobel Prize, I’ve been asked all sorts of- I’ve been questioned on all sorts of topics. And so, I have become I found that I have an ability to talk about almost any subject off the top of my head, even things I know nothing about (laughter). So, I clearly have some prospects as a politician, which, that’s the last thing I want to do. But I discovered this sort of surprising talent that I seem to have, in that- you know, if I’m asked something, I am able to say something that seems to make sense. You know, if it doesn’t make sense or not, I’ve got no idea. But I seem to be able to hold forth on almost any topic under the sun and sound as if I knew what I was talking about (laughter).

Zierler:

Mike, I can see a variety of positives and negatives with regard to winning the Nobel Prize, as it concerns the research. On the negative is, of course, it can be a distraction. But on the positive, perhaps it gives you more access to funding or graduate students. So, on balance, has it been good or bad for your research, would you say?

Kosterlitz:

On the whole, I would say it’s been very good.

Zierler:

In what ways?

Kosterlitz:

Well, I haven’t had a grant for years, because at one point, the grant proposal was turned down, and I’ve never managed to get another one since, and I just gave up. It’s been a waste of time trying. So, after the Nobel Prize, I got a little bit of slush funds from the university, which I could use for anything I wanted to, in particular, my research. So, I had a little bit of money to do some research and buy myself a nice computer and stuff like that. So, at the end of the day, it’s been good. But remember, by the time I got this prize, how old was I? 73? So, I was getting on, sort of past retirement age and definitely at the end of a career. So, I was quite pleased to be able to continue doing research, and I could at least do research on topics that turned me on. I could give up caring what other people thought about this. If I thought it was interesting and exciting, then I was able to do it.

Zierler:

And on that point, just to bring the narrative up to the present, Mike, what has been some of the research you’ve been involved with in recent years?

Kosterlitz:

Well, my main interest has been- okay, if you consider some sort of dynamical system that’s evolving in time, and if this system comes to some stationary state, is there- and if there are many possible stationary states, is there some mechanism that picks one out from the others? And that was something that always intrigued me, because the methods that were floating around had nothing to say about this question, especially if each of these stationary states is precisely equivalent to every other one.

And so, experimentally in some systems, it seemed that a particular stationary state was selected. But why? And that was my big question, because there seemed to be no way of trying to approach this analytically. And so, I have been doing, with the students, some numerical calculations. And I said: okay, my conjecture would be that there’s no point in trying to look at this process in the absence of random noise, because in any real system, there will always be some random noise. For example, a truck driving around the laboratory. Well, you know, that will cause some random noise on your apparatus. And so, any real system will be subject to some random noise. So, we decided to do some simulations where you wrote down some one dynamical equation and added on some random stochastic noise. And we ask the question: does this system ever come to some unique stationary state? And the answer, numerically, was: damnit, yes. It does seem to do that.

So, the next question was: why? Eventually, I was in China, and this group in Shanghai who were actually interested in the same problem as I was, and they had cooked up some theory that seemed to work for certain biological systems and eventually managed to apply it to this physical system. And it was quasi-analytic, and it seemed to agree pretty well with the numerical results we had already obtained. So, this is a problem that I think might be relevant to reality in some sense, because after all, the main system that’s in the back of mine has always been biological systems, which seemed to be very good pattern formers. Right? But they’re subject to the most unbelievably noisy environment, if you think about a cell, or- my example would be, take an animal of a particular species. Now, basically when they’re an adult, all these animals are essentially the same- about the same size. You know, normal animals have got the same number of limbs, etcetera, etcetera, etcetera. So, they all reach some stationary unique pattern, and they’re driven out of an equilibrium system, because obviously, these systems are out of equilibrium, and they’re driven. And the driving forces will be random, because the food supply is not too steady, etcetera, etcetera. So, there’s a lot of randomness there. But the eventual adult system is pretty much unique. And so, I thought that’s an interesting problem. Why?

Zierler:

How far have you gotten to answering the “why”?

Kosterlitz:

Well, that depends, I think, who you ask, because I think we’ve got a fair way towards answering the “why,” at least partly numerically and partly analytically. And other people would say, of course: no, you’re talking garbage. The problem is completely different. Blah, blah, blah. And this is the sort of problem that I find that having won a Nobel Prize, I’m allowed to spend my time working on. It’s completely impractical, just trying to answer a question which I think is relevant, but difficult. And so, it’s something that I find very intriguing. I think most people don’t care about it, but I am now free to think about such things.

Zierler:

But you don’t have to care that they don’t care, you’re saying.

Kosterlitz:

Exactly. Yes. Yes, yes, yes. I can do my own thing, and to hell with everybody else (laughter). I don’t care what they say or think. It’s nice being in this position. I just wish I wasn’t- I had been much younger when I had got into this position, because now that I’m in my late seventies, I’m really coming to the end of my career, and so my mind is not what it was. And so sometimes I think that maybe I’m just fooling myself and that I’m wasting my time and other peoples’ money following this trail. Maybe it is nonsense, but it does seem to work.

Zierler:

Perhaps though, Mike, looking at the experience of your father, who was active well into his eighties, gives you a sense that you have some time on your hands, that you can continue pursuing these things.

Kosterlitz:

Ah, maybe. Maybe. I mean, the trouble is that I realize I’m a lot slower than I was when I was younger, and so on and so forth. And you know, I don’t have the energy that I used to have. I remember when I was working on the- trying to work out this two-dimensional planar rotor model. You know, I would work for fifteen, sixteen hours a day on that, on these calculations, trying to get them- to make sure they’re right. You know, covering page after page after page of paper with tedious algebra- it’s not that it was difficult. It’s just that there were so many steps, one after the other, and the only way of checking the answer was to start again- you know, no way of checking each individual step. The only way I could do it was to start again and repeat the calculation. If it got the same answer twice, by definition, that was the right answer. So, in my younger days, I could do that part. In my later years, I’ve found that I could never reproduce the damned answer. No matter how often I tried it, I’d never get the same answer twice (laughter). I couldn’t do this sort of thing anymore.

Zierler:

Mike, now that we’ve brought the conversation right up to the present day, for the last part of our talk, I’d like to ask a few broadly retrospective questions and then one looking forward. First, I’d like to ask: if you can reflect on, long-term, your reaction to receiving that devastating diagnosis of multiple sclerosis. Perhaps even beyond wondering whether you would survive it or not, in those dark days, perhaps you were concerned about, even if you had lived, would you be able to maintain your academic career? And so, I wonder if you can reflect a little on- in what ways receiving that diagnosis, long-term, actually was beneficial to your career. Not just in terms of keeping you off the mountains, but perhaps what it taught you about perseverance and overcoming challenges.

Kosterlitz:

Okay. Well, I found it pretty difficult to deal with, because the main thing was that I had to cut out half my life. I had to cut out the mountain’s half of my life. Because remember, the mountains were very important to me. They were half my life. It was at one point I was seriously thinking about dumping physics and becoming a professional mountaineer, because at the time, I was probably good enough to do that. Of course, making a living at it is a different matter, but I never thought too hard about doing that, but I could have become a professional climber. And I might even have succeeded at that, but it was very fortunate that I didn’t, because this illness came along when I was still pretty young, mid-thirties or so, and it just basically stopped any such ambitions in their tracks. I had to just completely cut that out.

Of course, I didn’t take it very well. My wife complains that I went into depression for fifteen years or so. You know, I was basically wandering in around in a very depressed state for a long time before I finally managed to come to terms with it and sort of restart semi-normal life. So, that diagnosis was pretty devastating. You see, what happened was that I got these funny feelings and double vision, etcetera, etcetera, and then this diagnosis came along, and I thought my life had come to an end. Because after all, at the time, basically the neurologist said, “Well, you’ll probably be dead by age fifty,” which is not a nice thing to hear when you’re in your mid-thirties. So, it took me a while to come to terms with that.

You know, but it actually turned out I was pretty lucky, because I was one of the better cases, where the remissions- it was a relapsing-remitting version of the disease. But the trouble was, after each attack, it was a long remission, but I never quite got back to the level I was before. You know, my son keeps on complaining about the fact that I now walk, you know, feet wide apart, and so on, because my balance is gone. In my climbing days, I could actually walk a tightrope. At least, I could make a few yards along it before I toppled. But now, if I am standing on the floor and close my eyes, within about a minute, I will fall over, because my sense of balance is basically gone. And so, as an ex-mountaineer, it was pretty difficult to accept these defects, the loss of physical abilities. It took me a long time to come to terms with this. A very long time.

Zierler:

Mike, when you say that mountain climbing was half your life, is that to suggest that you were only half as productive in physics as you could have been, or do you think you achieved that balance?

Kosterlitz:

I achieved a sort of balance in that I never stopped thinking about physics problems. Even when I was sitting on a ledge on a cliff somewhere, I’d always be thinking about problems. You know, my climbing partner would quite often get very annoyed with me, because I’d be sitting there, supposedly paying out the rope, and suddenly my attention would just- because I’m dreaming about my physics, would drift- I’d be sitting there clutching the rope, not paying it out, and the guy would almost fall off when the rope went tight (laughter). But when I say it was half my life, you know, I loved this sort of freedom of being on a cliff somewhere.

You see, I think that I am naturally a bit of a risk-taker. In physics research, you’re wandering around an unknown territory with nothing to guide you but the penalties for failure are just embarrassment. Nothing serious about failing at what you’re trying to do. You just have to give up and do something else. But in rock climbing, it’s a bit similar in that you’re on some steep cliff somewhere, and there are often no- there’s nobody to guide you where to go next. But the penalties for screwing up are somewhat higher, up to and including death. But every time I- I used to enjoy that, because you read about these incredible things that climbers like Alex Honnold does, doing the El Capitan solo. It’s a very difficult climb: 3,000 feet. He did it completely on his own, and so on. And if he’d fallen, he’d be dead. And so, taking risks of this nature, you know, different people can stand different levels of risk. And I’m not saying I could do anything like Alex Honnold could, because that level of risk is much higher than what I personally could absorb. But at a much lower level, I actually enjoy the risk-taking, because basically, it makes life worth living, because doing everything in complete safety, etcetera, etcetera, that’s really boring (laughter). I used to drive cars far too fast. And it made me feel alive. I fortunately got away with it and the same with my climbing career. I got away with it.

But there were many times when I may not have got away with it. But one time when, for example, I was climbing with a friend, and we managed to do this big cliff in the French Alps and had to spend the night out about 100 feet from the top in a sort of cave. And the weather- there was a hell of a thunderstorm, and this pinnacle had its point- with us, more or less, on the point, right in the middle of a thundercloud. And so, sitting there with all this metal work- all this metal near you, which was essential for the climb, and there was this loud hissing noise, and this pulsating light. And you know, we were right in the middle of this charged thundercloud. And you know, we could have been killed at any moment. And getting ourselves down the next morning was sort of an amazing business. We got back on the glacier, and then we discovered that instead of having an easy walk back down, we were up to our thighs in new snow. So, walking was a non-trivial operation. And then the guy I was with suddenly collapsed. He basically collapsed from hypothermia, and so I tried to get him moving again. He just sort of- you know, he couldn’t speak. His speech was very slurred. He didn’t make any sense, and so on. You know, hypothermia is not good. And so, I realized that the only way I could survive- one, or the other, or both of us could survive- was for me to walk down on my own through this deep snow. Now, I don’t know if you’ve spent much time on glaciers, but when you can’t see the crevasses, it’s quite dangerous. And so, I knew this glacier quite well, and so I sort of ploughed on down it. And then I sort of remembered that at some point, I had to go to the left, because there was big ice cliffs. And so fortunately, I didn’t walk over the ice cliffs. And so, when I found these ice cliffs, I went left, and got round them down to the mountain hut, walked in, and the hut warden sort of looked at me. And so basically, in my pidgin French, I explained what had happened, pointing on the map roughly where I had left my climbing friend. You know, he was in a hole in the snow, with all the warm clothes we could find. And so, I lost interest in the proceedings at that point and just basically went up to bed and fell asleep. Fortunately, he was still alive when they found him and got him down, so that was quite an adventure.

And so, you know, it’s the sort of things that can happen. But it’s fun, if you like that sort of thing (laughter). And I miss that sort of lifestyle, since I couldn’t do it anymore. There was always some risk that something could go wrong, and so on, but if you’re sensible and tough enough, you’ll survive it. I mean, because something like that could have easily- would have killed us, and it would have killed a number of people. But fortunately, I was strong enough to survive it. And so, I thought that I was strong enough and good enough to really do something interesting in the mountains. And it’s the sort of lifestyle that basically, if you survive it all, it makes you feel alive.

Zierler:

Right.

Kosterlitz:

You know, that life is nice and worth living (laughter).

Zierler:

(Laughter) Mike, a reflective question about technology over the course of your career. Going back to when you were a graduate student, of course, computers were quite primitive, and today we have supercomputers, and we seem to be closer and closer to quantum computing. I’d like to ask generally, in what ways has that rise in computational power been useful for your research over the decades?

Kosterlitz:

For me, not particularly, because somehow, I have never been able to learn to code a computer. Yeah, okay, I can write simple programs and some of the high-level programming language, but I’ve never been any good at writing code so the machine can work at its top level. And also, one of the things that put me off computing was my experience as a graduate student, because sharing an office with five other people, I think- graduate students, and most of them were involved in some high energy theory and this was back in the late sixties. Most were involved in doing computations for high-energy physics. And you know, these guys would- as the time went by, they’d start getting paler and paler and staying longer and longer in the office, and so I decided that this computation stuff is not for me, because it’s ruining these other peoples’ health, because of not getting enough sleep, and so on (laughter). So, I’ve always tried to do things analytically, until I couldn’t anymore, and discovered that I was interested in problems that I couldn’t do analytically, and nobody else could, either. So, I turned to graduate students to write the computer code to look at them numerically.

Zierler:

Mike, next year will be your fortieth anniversary at Brown, a university that prides itself on its commitment to teaching undergraduates. And so, I’d like to ask you: over the course of your teaching career, what have been some of your favorite courses to teach undergraduates, and what are the most challenging concepts in physics to convey to undergraduates?

Kosterlitz:

I’m not the greatest of teachers, basically because to me, physics is one of these subjects that comes easily. It’s one of the few subjects I can actually cope with, because as I said before, I have a memory of a maximum of ten facts, and I’m not too sure of the last four. So, I have to basically deduce everything from the remaining six. And physics is one of the few subjects that allows this. You start off from a very narrow base of knowledge and evolve from that. And so, I’ve always found it very difficult to appreciate why undergraduates have such difficulty in doing some simple maths. I suppose it’s because my mathematical education was started off at a very young age. So, by the time I was in what you would call high school, I could basically- if you gave me a single integral of almost anything, I could do it. I could substitute this, and if that didn’t work, I’d substitute that. And eventually, I’d come up with something that I recognized, and so boom, it was done. So then by the time I came to- you know, when I was in college, I had a database of tricks that I could use doing some techniques of applied maths. And without this database, I would find it very difficult, and somehow, students- the undergraduates here don’t seem to have this sort of database. They never seem to have developed it.

And so, I have a lot of trouble in trying to understand why the students find some pieces of elementary mathematics so difficult. Because to me, this was sort of just obvious and simple, and doesn’t require an explanation, because I’d learned it at school, not in college. And so, this sort of thing has always been a challenge for me is to appreciate how little the undergraduates know. Basically, you’re starting to try to teach them, and they have a clean sheet- a blank sheet you’ve got to sort of write on. And so, trying to teach somebody with a blank sheet I find difficult, because there’s no knowledge base that you can build on, and I find this difficult and frustrating to deal with. So basically, what I am trying to say is that I am at my best teaching graduate courses which I have done for the last twenty years or so.

Zierler:

Mike, for my last question, looking forward: you’ve been involved in so much research that has solved, or has gotten us so much closer to understanding, some of the fundamental mysteries in solid-state and condensed-matter physics. Looking ahead, either through your own research or simply staying on top of the literature, what are those mysteries that are ongoing that continue to capture your imagination? And what do you see, drawing on your powers of extrapolation, that might be the most efficacious means to solving those mysteries?

Kosterlitz:

I’m very reluctant to say anything at all about that, simply because in physics, what always comes up against something that is not understood, no matter what branch of physics you’re in, you always come up against something that nobody understands. And so, I think whatever you do in physics, you will always come up against new problems, and so that’s what I like about it. I don’t know what else to say. I’m sort of reluctant to say anything about the direction we should go in, because it depends on what your point of view is and what we think is important.

Zierler:

But I’m asking you for your point of view, what you think is important.

Kosterlitz:

You see, that’s why I’m reluctant to try to say that A is more important than B, because neither A nor B is properly understood; therefore, they’re both important, because if you think Topic A and Topic B are relevant to real life, or is relevant to something, then one should understand it. And since neither are understood properly, they’re both intriguing problems. That’s what I mean. It doesn’t matter what branch of physics you think about. There are always, no matter what, you look at the literature, and you see there’s some progress being made, and suddenly it stops, because people start spinning their wheels. There’s lots of smart people in any branch of physics, but it always seems to be that eventually, the progress stops, and all these smart people start repeating the same calculations, the same thing over and over again, because- and the reason for this is because the conventional wisdom has gone as far as it can. You know, you need somebody to come in from left field to say: look guys, why don’t we think this way? The way you’re thinking is not being productive anymore. What happens if we think out of the box in this direction? And sometimes that works, and sometimes it doesn’t. But when it works, it’s an important breakthrough.

Now, things like this happen in all branches of physics all the time, because as I say, there are very smart people in every branch of physics, but in most branches, they’re stuck somewhere. And the reason they’re stuck is because they’re not thinking quite the right way. And it needs somebody coming from left field to change- to alter the way of thinking. But there are many fields, and basically if I could make the breakthrough in thinking in different fields, that would be wonderful, because a lot of these fields, basically, the breakthrough is often worth a major prize. So, if I could do this in more than one field, I would have gotten more than one Nobel Prize. So, I don’t expect this to happen again (laughter).

Zierler:

But you’ve made these choices throughout the course of your career, on what to work on, of course.

Kosterlitz:

Yes, because my choices have usually been sort of accidental. You know, I’d just come across a problem that intrigues me, and I don’t think about whether this problem is important or not. If this problem intrigues me, I will look at it and try to do something. Usually I fail and I like to say to some kid who is thinking about making physics a career: it’s okay, it can be fun, but research in physics is ninety to ninety-five percent frustration and failure and five to ten percent success. So, as long as you can put up with ninety-five percent frustration and failure, you’ll enjoy it (laughter).

Zierler:

Well, Mike, on that note, it’s been an absolute pleasure to spend this time with you. Thank you so much for sharing your recollections and insights over the course of your career. I really appreciate it.

Kosterlitz:

You’re very welcome. It’s been fun.