Harrison Prosper

Zierler:

This is David Zierler, oral historian for the American Institute of Physics. It is October 9, 2020. I am delighted to be here with Professor Harrison B. Prosper. Harrison, thank you so much for joining me today.

Prosper:

I’m very happy to be here.

Zierler:

To start, would you please tell me your title and institutional affiliation?

Prosper:

I am the Kirby W. Kemper Endowed Professor of Physics at Florida State University.

Zierler:

And who was, or is, Kirby W. Kemper?

Prosper:

Well, Kirby is an internationally known nuclear experimental physicist, who basically was one of the founders of the nuclear physics group at Florida State, and for many, many years, he was the head of the group and also chair of the Physics department, vice president for research. I mean, he’s done huge numbers of things. And when he retired, he rather kindly endowed this chair and asked me to be the first occupant.

Zierler:

Oh, wow.

Prosper:

…which I thought was really quite extraordinary an honor.

Zierler:

That’s quite an honor.

Prosper:

Yeah.

Zierler:

When did you get named to this chair?

Prosper:

When? That’s a good question. Maybe 5, 10 years ago, something like this?

Zierler:

Well, Harrison, let’s take it all the way back to the beginning. I’d like to start first with your parents. Tell me a little bit about them and where they’re from.

Prosper:

My parents are from Dominica in the West Indies, which is this island that used to be a colony of the United Kingdom. So, they left, actually, Dominica, I believe, in the late ’50s, and they went to England and sort of left me back there with my relatives. Initially, my father tells me when he arrived in Bristol, he was, of course, very excited, because that was a new place. And then he was told by one of his friends, actually, you know, you can do more interesting things if you go north. And so, he headed to Bradford in England, and arriving in the downtown area, he immediately thought: oh, my goodness, what a mistake, because this was a dismal, gray place. You know, those were the days when there were smokestacks all over the place. People burnt coal. And he was really thinking: I need to go back. But he was persuaded to stay there, and he did. He stayed. So, when my parents arrived, they were given the impression that: ah, this is the land of opportunity. This is where one can sort of really do things. But as it turned out, things were not quite as rosy. And to cut a long story short, he ended up having to just do whatever jobs he could find — for example, being a bus driver and other such jobs. But eventually, my father decided to go to night school, so he would basically learn things after work and eventually got himself to the point of becoming a precision grinder. He basically would work on making precision instruments, like calipers and what have you. And then later, my mother decided to learn to become a nurse. And I can remember, I have these really vivid images of her cooking and working at the stove with a book in her hand, reading about all kinds of things. Now, she was not very good at drawing, and so, my brother and I would actually do all the drawing of the parts and anatomical structures in the body. And so, she literally would be learning about all these things while doing her housework. And eventually, she was able to become a registered nurse and worked until she retired in this capacity. So, they had aspirations for doing other things, but of course, things were not quite as easy as they always had hoped it would be.

Zierler:

You joined them in England at some point?

Prosper:

Yes. So, they went before me, and then I believe I arrived in England in 1961. So, I was 5 years old, a rather sickly child. Everything was new and quite strange, actually, because you can imagine, one comes from a place which is just lush and green and very, very different to this industrial heartland of England, where we talk about pollution today, but in those days, pollution was pretty appalling. And this is where I arrived, and of course, because I arrived just at the age to start elementary school, I actually enrolled in the Green Lane Elementary School in Bradford. And I’m not quite sure whether I was 6 or 5, but around that time.

Zierler:

There must have been a racial dynamic that your parents had to contend with that they would not have back home.

Prosper:

Indeed. In fact, it was quite severe. Even though it was not official — it was not the official policy — as was the case in parts of this country, it was nonetheless baked into the society, this — in England, in those days, they called it the “colour bar.” That is, there were some places that one could not go. There were certain things one could not do. In fact, renting houses or apartments was quite a challenge. And so, it was a very difficult period. But nonetheless, my parents’ attitude was: well, okay. Maybe for us, it’s going to be extremely difficult, but the one way to make sure that the children can overcome those difficulties was to make sure that they are educated. And so then, it was clear that education was key. That was the way to — it wouldn’t necessarily remove those barriers, but it would make them at least bearable, and provide a way to overcome them. And so, they were never bitter in that regard. They just thought: this is what one has to do, and this is what they encouraged all of us to do.

Zierler:

Was your family part of a larger expatriate community? Was there anything like that in England?

Prosper:

Yes. And so, you can imagine what happened — Britain, the wars — you know, the Second World War ended 10 years before I was born. There was this enormous destruction in the country and a huge need for people to work — workers. So, what did Britain do? It reached out to its colonies, one of which was this little island in the middle of nowhere, an island in the Caribbean. And so, there was this promise to the colonists: please come to the motherland, and you’ll be welcomed. Of course, that was not true. So, there was a huge wave — and some people would call it actually a “brain drain,” because typically, it’s people who were a little bit better educated who went to the U.K. and other places. And so, there was a community in Bristol, there was a community in Bradford, and that community sort of tried to help each other, of course, but it was still very difficult, because the opportunities were limited not by law, but by custom.

Zierler:

In what ways did your parents try to maintain their culture, their religion, their heritage, as expats in Britain?

Prosper:

Yes. That’s actually very interesting. So, my father tells me that when he was a young man — his father died when he was — well actually, his mother died when he was 10 years old, which was very sad for many reasons, not least of which because one misses one’s parents, but it was very sad because his mother had recognized that her son had some potential. And so, she tried to get him to go to this reasonably good school in this island that was basically run by the Brits, for bright kids. But she died, and my grandfather on my father’s side was not quite as enamored of the idea of education, and so wanted my dad to basically work on the land — my grandfather had some land in Dominica and wanted my dad to basically help him with this. Of course, my father was not interested, and after all, he was only 10 years old. And eventually, when he became a teenager, he decided to go and do other things, and he became a sailor, who would — well, he would basically — in those days, because it was a very small island, very mountainous, the way people got around was to have a boat, a ferry boat, that would circumnavigate the island. And so, my dad basically worked on those boats for a while. And so, yeah, that was sort of his background. But then, [laughs] for a while, he said he became a preacher, which I found quite hard to believe, given his current attitude about these things. But he became a preacher. Well, then he kept arguing with people, and he was one of those people — he tells me that he was a very strong young man who was quite capable of defending himself, but he was also a preacher for a while. And as a consequence, he actually learned a great deal about the Bible. I mean, really in depth. And my mother, on the other hand, she was — she’s as Catholic as they come. I mean, really, dyed-in-the-wool Roman Catholic. But eventually, my father basically turned away from Catholicism in a very, very definitive way, and so I grew up in a family that was split down the middle: on one side, my hyper-Catholic mother; on the other side, my sort of Atheist father. But my mother kept a lot of her Catholicism and sort of ways of doing things from the islands, from the Caribbean — sort of fire and brimstone, and all that, which was really very, very striking. And of course, they kept a sort of cultural awareness — the music that they enjoyed in their youth, calypso and so on. But they were also mindful that if they wanted their children to have any chance of success in this rather harsh reality that they lived in, you know, we had to be educated. We had to make sure that we learned the language well, etcetera, etcetera. So, it was kind of a balance between the two — between trying to maintain connections with where they came from, while making sure that their kids took education seriously. And it was difficult. It wasn’t always easy, because there were times when, for example, their own community was a little bit rejectionist, because they said: well, you’re trying to get your kids to disassociate from where their parents come from. But my parents were really determined that we would not grow up with the same kind of strictures that they had to endure.

Zierler:

Now, Harrison, is your sense that when your parents initially left for England that they were leaving permanently?

Prosper:

No. So, this is the point. There is a tradition to go to the country, you know, the seat of the empire, for a year, make some money, and return. Right? That was a tradition in that part of the world. And so, when they left for England, that was the intention. In fact, this was why [laughs] I was left behind.

Zierler:

Right. Right.

Prosper:

Right? They would go to England, make a bunch of money, and return to Dominica. But it became quite obvious that the job that he got — so, his very first job, actually, was a ticket collector on a bus. You know, you can imagine the pay in those days was utterly miserable. He wanted to be a bus driver, because the salaries were higher than for collecting tickets, but he was too young. And so, this was the struggle, and so it became very clear that going back was just not an option — simply, financially not an option. And so, later on, they said: look, we’re here to stay. And I was then sent from Dominica to England by, I believe, my late auntie, Auntie Rita, who — I think it was she that took me over.

Zierler:

Also, how did you identify yourself growing up? What were some of the ways — did you see yourself as an immigrant, as a Briton, as somebody from the Caribbean? These must be complex issues and terms. But how did you think of yourself?

Prosper:

Yeah. So, when I went to the infant school, the very first person I spoke to — I was maybe 5 or 6 years old — was one Henrik Ludwig Peter Krzykawski. He was born in England, but his parents were Polish, and his parents owned the Star Pub in Bradford. So, he was my first friend. In fact, we’re still friends, all these years later. And I grew up in a very mixed neighborhood. It was interesting — mostly Polish people and people from the Caribbean, and a few people from India and Pakistan. And of course, a few native English people. So, it was a very mixed community. Because of the racial attitudes, I was always completely clear that I was apart from the rest. For example, in the infant school — even though I lived in a mixed neighborhood, the school itself was predominantly white. And in fact — this has been the history of my life, being the sole Black person, or maybe one of two non-white people. And so, I’ve always felt myself to be never quite one or the other. Right? For example, because of the cost of returning to Dominica — in fact, the very first time I went back to where I was born was in 1990-something, long after I’d arrived in England. And so, the only relatives I really knew were the ones who had already come to England, some of whom lived in Manchester, England, some who lived in London. And so, I got, of course, to know my larger circle of relatives rather well. But I always felt not quite fitting anywhere, because I wasn’t really culturally West Indian. Certainly, the white English kids didn’t consider me one of them. So, it was always — yeah, I mean, it was interesting. It didn’t actually bother me very much, strangely enough. I mean, there are people who get extremely concerned about it. They feel rootless and unattached to place. I’ve never felt that. I really feel like a person whose feet — I have one foot in England, and one foot in the Caribbean, and I’m in the middle. I’m kind of a hybrid: neither one nor the other. So, I’ve never felt culturally one or the other. Although, people look at me now, and they hear my accent, and say: well, of course, you’re a Brit. But I tell you, growing up, it was made clear to people around me that I was different.

Zierler:

Is your sense that, given your parents’ intellectual abilities and their aspirations, that they would have attained higher levels of education if they had the opportunity to do so?

Prosper:

Oh, absolutely. I mean, really, one of the things that my parents, especially my father, encouraged was discussion, and argument. And it was quite clear from all the discussions we had in the house that he — yeah, if he had been given — if he’d had the opportunity, he would have done very, very well. He would then actually have gone much further. And in fact, that was the aspiration. That was what they thought they were coming to. Right? And also, my mother as well. She had to raise a large family, but at the same time studying to become a nurse, and in fact, she became really one of the very best in her field. So, I do think that they — yeah, they could have gone further, but the circumstances were such that it was not possible.

Zierler:

Was your school diverse at all when you were growing up, or were you essentially always the only Black kid in class?

Prosper:

Essentially almost always the only Black kid in class. And so, that started off in infant school, and then to the middle school, and then to the grammar school. And certainly in the grammar school. I went to an all-boys grammar school in England. And so, as was the case in those days, in these grammar schools, there were five “forms,” starting at age 13 through 18, with a total of 500 schoolboys in my grammar school. And yes, in every form, I was the only Black kid — or perhaps there were one or two other Black kids. In those days, Britain was obsessed with stratification, [laughs] of grades and so on. And so, in every form, you had different levels. And I was always in the upper level, and there, I was the only one. I mean, this has just been the reality of my life.

Zierler:

The stratification, in some ways, I’m sure, is a microcosm of the larger class structure in England as well.

Prosper:

Very much so. We were definitely not middle-class. [laughs] I remember one of the things which — now that we’re talking about this, I remember — is that there’d be the summer holidays, six-weeks’ holidays, when people would go off and do things. And we got back in the autumn, in the fall. Typically, the English masters would say: okay, can you write an essay about what beautiful things you did for the holidays? Where did you go? And of course, we were a working-class family. We went nowhere. I mean, going to Manchester from Bradford, just 35 miles away, was an adventure.

Zierler:

Yeah.

Prosper:

That was something spectacular. And going to London was like going to the Moon. And so, I would just invent stories. [laughs]

Zierler:

And so, if London was going to the Moon, going back to Dominica was like, just out of the universe, essentially.

Prosper:

Yeah, exactly. And in fact, my parents — bless their heart — I think it was in the middle school, there was a school trip to go La Baule, France, which is in northwest France. And they, my parents, worked like crazy to scrape together the money to pay for me to go on this school trip, because I’d never been on anything like that before. And I must say, it was very touching, because for them it was a huge amount of money. But they did it, and I was actually able to — the first time, actually venture out of the country to another place. And I remember this vividly, because this, for me, was just an unbelievable adventure. But that was fairly rare, and quite a financial stress on the family. But they did that.

Zierler:

Harrison, when did you start to get interested in science and the natural world? Was it perhaps even before your exposure to academic science in middle school or high school?

Prosper:

I can tell you precisely, to the day actually.

Zierler:

Wow.

Prosper:

It happened with the Moon landing.

Zierler:

Ah.

Prosper:

July 20, 1969. I’d just turned 13, and so that was the summer between leaving the middle school, Drummond Road Middle School, and going to Carlton Grammar School in the fall. So, there was this summer, and there was this Moon landing. I remember watching. We had this old black and white TV, and I’m watching those images. I was — I don’t know. I was simply awestruck by what I was seeing. And in fact, that summer, my mother — who obviously recognized that something had happened to me — she bought me a small telescope. Again, that was, for her, a big deal. She bought me this small telescope, and for the rest of the summer, I spent it looking at sunspots, the Moon, and so on. I was just simply enthralled — every single night that it was clear, which wasn’t very often in Bradford — I was there, looking at the stars. And so, in the middle school, yes, we did all the subjects and so on, but my interest at the time was mostly in art: you know, painting, drawing, this sort of thing. Right? I had a fairly superficial interest in science. But this particular incident completely changed my direction. And so, when I arrived at the grammar school, Carlton Grammar School, this dark building complete with gargoyles, and the Masters (school teachers) all dressed in black gowns. If you’ve seen Harry Potter, it’s Harry Potter without the witches. [laughs] I mean, quite a sight for a 13-year-old entering such an environment, it was quite something. And so, when I went to the grammar school, I went from being kind of a completely indifferent student when it came to science, to just being a vacuum cleaner of anything scientific — you know, about science. And it was just a complete transformation. So, that was when things really changed.

Zierler:

I wonder if the rootlessness that you referred to before, with your personal identity — in some ways, science served as a root system for you.

Prosper:

It could well be. It could well be that I’d finally found something that I thought I could be part of. I mean, of course, at the time, I had no idea what — I mean, I just knew that this was interesting, exciting — you know, there were people who did this sort of thing, and I wanted to be a part of it. But in hindsight, I think maybe that’s probably what happened, I finally found something that I thought I could be a part of. And of course, this was reinforced in the very first term of grammar school, when — yeah, there was a transformation in me. I suddenly felt that, yes, this is what I want to do. Now, of course, a 13-year-old doesn’t really know what he wants to do. All I knew is that I wanted to be a part of this…

Zierler:

Yeah.

Prosper:

…whatever “this” was.

Zierler:

It must have felt liberating to you that this was even possible, something like this.

Prosper:

Yes, because no one — see, here’s the thing. No one in the community of which I was a part did any of this. Right? People in my age group, some left school at 16 and went off to do — you know, what today we refer to as sort of ordinary working-class jobs. And so, yes, this was just a very different world that was suddenly opened. And I actually felt that it was a possibility that I could be a part of this. Nothing was guaranteed, of course. And I also discovered I was good at it, which also was helpful and sort of helped to increase confidence. But mainly, it’s because I already thought I could be a part of something really exciting.

Zierler:

Harrison, looking back, in middle school and high school, did you receive a good education in math and science?

Prosper:

Yes, especially in the grammar school. Here’s the thing. The education system in England has gone through many, many revolutions. I entered grammar school — which is really when I got my real education — at the time when the standards were very, very high. I mean, brutally so. In the grammar school, in the physics class, we had a thermometer with 100 percent at the top and 0 at the bottom, stuck onto the wall. And after your exam, your name was placed [laughs] at your grade. Speak of pressure, right, and humiliation, or whatever. So, the condition was brutal. Not just academically. This was a school where the philosophy was this: mind and body are both important. So, at the start of the term, you had to decide — you had to try all the different sports for the first week or two, then choose one, and stick with it, come what may. And you had to sort of cycle through the sports. And there was no excuse. I mean, it could be freezing outside. You had to don your shorts and go off and do soccer, or if you had to go fellwalking, which is really running over bogs and [laughs] hills, you had to do that. If you didn’t know how to swim, it doesn’t matter. You’d be pushed into the deep end. I mean, it was felt that this was what we do. Consider, for example, our P.E. master. There were these exercises where you were testing your reaction. We were lying on our backs in the gym, and he went around with a big medicine ball — this heavy thing — and he was going to drop it, and you had to react and catch it [laughs] before it would hit you. This was the grammar school. You had to be physically fit, essentially vibrant. And so, it was a place of very high standards. But the great thing is, that the masters — who were all men — really took their jobs seriously. For example, English writing was critically important in that grammar school. So, in every single class, whether it was English literature, or regular English, or chemistry, or physics, you had to write. I mean, my essays would come back dripping with red ink. I mean, the Masters were brutal in that sense. But I’m actually very grateful, because that’s what really gave me the education that I now rely upon. Another thing, there was one very important person — the physics teacher, my first mentor. Mr. West — I think he was fair to all the boys, but he was particularly attentive to me for whatever reason. And I think that was very helpful, actually, to be very honest. It was very helpful. And so, yes, when I finished, it was quite clear that this is the life I was going to lead, and it was something to do with science.

Zierler:

Physics specifically? In other words, when you were thinking about college programs, were you thinking specifically about physics departments?

Prosper:

Yes, physics, because my initial interest was actually astronomy. As noted, the Moon landing triggered my interest in the stars, and I still have this deep love of just looking at the night sky. That’s been with me from age 13. Astronomy was the thing that really got me into science. But then, in the grammar school, learning about the laws and so on, and seeing how one could say so much about everyday stuff, that just appealed to me. I’ve always enjoyed history. I think history is an amazing subject. But it struck me: if you like history, and English, and so on, in the end, how you assess it is a matter of judgement. When the master grades your essay, it’s ultimately a matter of judgement whether he gives you a good grade or not, whereas what I discovered in physics, is you’re asked to solve this problem, and you solve it in whatever way you want to solve it, and you get the right answer, you get full points. And so, in some sense, that appealed to me. It appealed to me that there was a thing I was good at, which relied less on judgement of my teachers than in other subjects. And that was appealing. But just the fact that one could actually say so much about the world around us, that’s what appealed to me. And even chemistry — I enjoyed chemistry. I enjoyed messing around with chemicals and solids. But we were teenage boys in a grammar school, all-boys school, so you can imagine it was a bit — you know, it was typical teenage bedlam. And I just enjoyed messing around with chemicals. And doing stupid things that — you know, teenage boys do, such as seeing how hot I could get a penny. You know, could I get it to glow white? And so, we had this Bunsen burner, and were cranking the thing up, because the Master was off doing something. And of course, as luck would have it, the penny fell off the the Bunsen burner onto the bench. And there was a lot of smoke, and suddenly, of course, the master walks in, and we all sort of stood with this thing behind us. And he addressed us, and said, “Okay, is anything amiss?” And of course, [laughs] with all the smoke billowing behind us, we said, “No, sir.” [laughs] So, yes, I enjoyed chemistry. I really enjoyed doing those experiments. It was really great. But physics was the thing that appealed to me, just the fact that you didn’t need to know a lot, I think, is what really just struck me. You didn’t need to learn and memorize a lot of stuff in order to do a lot of things.

Zierler:

It’s not anatomy and physiology.

Prosper:

Yeah. You just learn a few rules, really understand those rules, and then you can do lots of things, and that appealed to me.

Zierler:

Now, of course, Manchester is close to home, which I’m sure was attractive. But at what point did it dawn on you that you were actually able to get a world-class education at Manchester, also?

Prosper:

Yeah. [laughs] It’s funny, now. It only dawned on me after I got there. So, I applied to various places, of course, and I got into Manchester. But again, there was no deep reflection — here’s the thing. Getting through the grammar school was already, for me, an amazing thing. I didn’t really consistently think about those things at all. I know it sounds sort of naïve, but I didn’t think about those things. I just thought: I want to learn more physics. I want to learn more mathematics. I just want to learn more science. And, where can I go? Manchester was one of the places. But I didn’t think: “I want to go to a place to get a really good education.” That wasn’t the thought at all. It was just, “I want to go somewhere where I can learn more of this stuff.” That was the motivation, actually. And so, yeah, I went to Manchester, and I was very happy about it, because one of the things I’ve always enjoyed as a teenager, and even now, is hiking. And, when I was a teenager and in my 20s, rock climbing, running, biking — I enjoyed being very physical, partly because that’s the way the grammar school was. Physicality was very important. This has been taught to me. When I went to Manchester, I met some friends who were likewise very much into all this kind of stuff. So, for me, this was great. I could continue all these very physical things while getting the kind of education, which, when I look back on, I realize was really quite extraordinary.

Zierler:

Is your sense that the curriculum for undergraduates at Manchester was sufficiently broad that you had essentially a full exposure to all of the different kinds of physics available to pursue?

Prosper:

Yes, indeed. It was extremely broad. And in fact, we had some really excellent teachers. In Manchester, there was in the Department of Physics the Manchester Book Series, where many of the professors there wrote textbooks — so, there’s a kind of coherence among the textbooks — but the education was actually extremely broad. One of the things I found really enthralling was that Manchester not only was the place where I could learn a very broad range of physics, but also it was prominent in astronomy as well and had an astronomy department. Therefore, the thing that initially got me into science, after the trigger that I received from the Moon landing, I was able to pursue that as well. And indeed, I quickly learnt that in Manchester, in the downtown, there was actually an observatory, a 12-inch refractor telescope, in the Godlee Observatory. And so, of course, I decided to find out how I could get access to this telescope. I was pleasantly surprised to be told, “Sure. Here’s the person you have to talk to, to get a key.” So, we had this little club that would meet up at midnight and walk to downtown Manchester, to this old Victorian building, and we’d go up the spiral staircase to the observatory at the top. And we had access to this amazing machine. The only difficulty was that we would then leave at 4:00 in the morning, having to get up in time for the class at 9:00, which was sometimes difficult. And so, yes, Manchester was great in that I was able to pursue both of my interests in basic physics, in all domains — but also, maintain my interest in astronomy, which I have maintained to this day, and continue physical things as well, like hiking.

Zierler:

Yeah. Harrison, as you were thinking about graduate programs, I’m curious: how well formulated was your identity as a physicist as an undergraduate? In other words, when you were thinking about graduate programs, were you thinking specifically about the kind of physics you wanted to pursue in graduate school?

Prosper:

Yes. What I have discovered about myself — especially toward the end of my undergraduate days at Manchester — where I did all my education including doctorate in six years — what really attracted me was understanding the fundamentals, the rules that are at the base of things. That’s what, really, I found most interesting. I was interested also to see how those rules explain everyday things. So, this is why I’ve always had a very deep interest in condensed-matter physics, surprisingly, some people think, because it is practical. I’ve also enjoyed seeing how these very basic rules can explain everyday things. I remember one of the first times when I learnt about how, from statistical mechanics, you can actually derive the gas laws, and so on, and properties of materials. I just found it thrilling; I’ve always enjoyed that. But, the thing that drove me was wanting to know what’s at the bottom of things. It was exciting. And I just came to the conclusion that particle physics was the thing that got to the core of things, and therefore, it just seemed natural that this is what I should pursue. And Manchester group had what was already a fantastic group; so I stayed.

Zierler:

And of course, in the late 1970s, this is a fantastically exciting time in the world of particle physics.

Prosper:

Fantastically exciting time. It was just when I joined the Manchester group in the fall of ’77 — I had one year of what one would call a kind of diploma, or a master, program. And then, I was deployed to DESY in Hamburg, Germany, in the fall of 1978. It was, again, just one of those magical times. I remember arriving at the main building of DESY, where I had to go and talk to one Frau Bartels. You know, I’d just arrived from the U.K., and I knew nothing about anything to do with Germany, really. So, I went to see one Frau Bartels, and I think that initial interaction with this woman was really so wonderful. She was very, very warm, kind, and said, “Ah, you are Harrison Prosper, and I understand that you need to find an apartment,” and so on. So, I said, “Yeah.” I don’t know German or anything. And that afternoon or the next day, she said, “Ah, I found a place for you that I think you’ll like very much,” and she drove me all the way out to Rissen, west of Hamburg, to an apartment in the basement of a house that was owned by a German family. I have to say, when I saw the apartment, I was [laughs] stunned. I have never, ever in my life lived in such a luxurious place as that. Remember, I was at Manchester, and I lived in a [laughs] in a terrace house, in a townhouse, that we dubbed “the flea pit,” because it was pretty dismal. In fact, I shared this house with two of my friends, and I remember telling them, you know, “I don’t have much money, so please find something that’s relatively inexpensive, relatively cheap, and whatever it is, I’ll join you.” Well, they took it to heart, [laughs] and they found something that was really, really, really cheap, but it was just a dismal place. We realized it was dismal because the first time it rained — which it did often in Manchester — we saw slug trails on the carpet, and we thought: oh, no, we have slugs that are coming in.” So, we had several weeks of the battle with the slugs, putting down salt barriers. But then, we realized that the slugs are not very intelligent creatures. They still go across the salt barriers, and of course, they explode, and it was such a mess cleaning up those exploding slugs that we decided it was better to simply live with the slugs. So, I went from that to this beautiful apartment, with a hi-fi system — it was just fantastic. And the German family was just so pleasant. This was my initial reaction. This was my initial contact with Hamburg. And note, I was a teenager in the ’70s, so my musical taste is heavy metal, you know, Deep Purple, Uriah Heep, Pink Floyd. And one thing I discovered about this German family: they were like clockwork. Saturday morning, between this hour and that hour, they went going shopping, every Saturday. And so, I would crank up [laughs] the hi-fi to play some of my heavy metal music. So, this was my initial reaction. So yeah, this was a period for me that was just magical — my initial contact with my German colleagues was very, very warm and welcoming. But then, after Frau Bartels had found this apartment, of course, I had to go to the hall where the experiment would be. I remember arriving at the northwest hall of DESY and seeing a big hole where there should have been an experiment, I thought. There was nothing there. I thought to myself: oh, my goodness. I’m going to be a graduate student forever. But amazingly, within six months, the thing was there. And for me, this was so exciting, because this was the time when — these were the days when experiments were not very large. You know, there were maybe 50 people on an experiment, and that was considered huge in those days. This was when a graduate student could do everything. I was involved in putting together the muon chambers from Manchester, testing them, installing them, cabling them up, writing software to reconstruct the muons; the entire chain of activity that surrounds experimental physics, and that was very exciting, including being on shift. In fact, speaking of being on shift, taking those data that eventually led to the discovery of the gluon was very exciting. Some years ago, my German colleagues did some archaeology to resurrect some of the old logbooks that, of course, were written in longhand. On my machine somewhere, I have photocopies of these, or pictures of these, logbooks. And so, I can actually go back and tell people: ah, I was actually on shift on that particular night, with this particular individual, and this is what happened. It’s all there, written down. It was just exciting. It’s incredibly exciting. And the other students in the other experiments — you know, we talked to each other, and no one was bothered about this. Yes, there’s competition, but I just felt I was part of the community. I would go over to Mark-J and talk with the students there; we would really work together and help each other, even though we were on different experiments. And it was just thrilling. It was the summer of ’79 when we got reports from the other experiments — TASSO Mark-J — that there really were three-jet structures. When we saw our first three-jet structure, it’s a difficult thing to describe, this thrill that you’ve found something that, even if 100 years from now, 200 years from now, the physicists of that era conclude that our interpretation of what we found was wrong, it doesn’t alter the fact of the discovery of something new. That’s a thrilling thing, to think that you’ve found something that would be there forever, irrespective of your interpretation of it, and I just feel extraordinarily fortunate to have been in that situation on three occasions, starting with the gluon discovery. One of my colleagues took a picture of me at a German pub with my other colleagues. We were celebrating in the usual way that one celebrates in Germany — drinking beer — the discovery of the gluon. I have a picture: December 10, ’79, sitting around this table. And it was just one of those absolutely thrilling years. I mean, it was just unbelievable.

Zierler:

Harrison, of course you were fully ensconced in the world of experimentation, but I wonder: in terms of your collaborators and just your broader exposure, to what extent were you involved on the theoretical side of things, particularly at this moment? And perhaps, beyond the U.K. as well, in terms of what was going on with Glashow and Weinberg and everything in the United States.

Prosper:

Yeah. So, of course theory was something that was always very important at Manchester, but really, what I recall is that I was bothered for a long, long time, actually, by theory. Not so much because it was difficult, but mostly because I just had this urge to really understand. [laughs] And I remember that the very first time that I learnt about, for example, renormalization, I was pretty shocked, actually, that one could do this peculiar manipulation and get answers that were remotely applicable to experiment. And then I remember having long discussions with my theory professors about this. But how can that be? How can that be sensible? And so, I think for a long, long time, I had a kind of a — not really an aversion, but I couldn’t get past the fact that what I was taught didn’t make sense, mathematically, to me. That yes, it was extremely useful. It would actually give answers that agreed with experiments. But this idea of doing these manipulations to sweep away infinities, really was a road block for me for a long, long time, actually. It was only later, when I became a postdoc, talking to other people, the theorists, that I started to take theory a bit more seriously, in the sense that I had a better understanding of what they were getting at. So yeah, for a long time, I was kind of resistant to this. But actually, there was sort of a fork in my career, in that when I became a postdoc, it wasn’t theory, but it was a different area of _mathematics: statistics that I stumbled across; it was just happenstance. Note, I got my Ph.D. in 1980, October 1.

Zierler:

And Harrison, I just want to interject here. Where did you actually do and defend the dissertation? Was it at DESY, or was it at Manchester?

Prosper:

At Manchester.

Zierler:

Okay.

Prosper:

So, yes.

Zierler:

And the committee were Manchester professors?

Prosper:

That’s right. And one external person who joined the committee. That’s right. What happened is I returned to Manchester in — I believe it was in the early part of 1980, in order to write my dissertation and defend the dissertation that year. I was successful in doing so, and handed the thing in on October 1, 1980. Then came, of course, the decision: what would I do thereafter? I decided to take some time off. I thought, you know, it had been very exciting, of course, but an intense time, right, at DESY — a really intense time — and I thought it would be good just to decompress for a bit. Embarrassing to say, but my initial [laughs] plan was to do nothing much, actually. I’ll just say, in England, this would be called being a dosser. Just do odd jobs here, and just basically chill for a while. That was the plan. And then what happened was, I think it was in November of 1980, I got a call from a friend of mine who was a teacher in a school in Rochdale in Lancashire. And she said, “Look, Harrison, we are desperate. We absolutely need a science teacher. We need someone who can teach science, who can teach biology, a bit of mathematics, and so on. We just need someone for the next year. I know you’ve just finished. I know you don’t want to do anything, but we would very much like you to help us out.” Of course, I initially said no. I said, “I’m just exhausted. I need to do nothing much.” But she was very persuasive, and so I ended up going to the school and talking to the headmaster there. And literally the Monday after, I was in front of a bunch of 13- and 14-year-olds, having zero idea of how to teach. But that was — and it’s interesting how a single decision can completely change the direction of one’s life. Because my plan was to spend a year doing nothing much, and then back to physics — I knew that there were postdoc possibilities at the University of California in La Jolla, and I thought, yeah, why not? Let’s go to America for a year or two, just to see, and so I thought, let me spend one year doing nothing, and then get back into research. That was my plan. Go to La Jolla, California. That was the plan. Well, this teaching job intervened. I arrived at this school in Rochdale: Broadfield School, Rochdale, to teach science. Then two things that happened that were very important, extremely important, to the direction of my life: one, this is where I met the beautiful young woman who would become my wife; and the other thing is that I discovered that I enjoy teaching. I enjoy explaining things to kids. I’ll give you an example. In one of my lessons, I was trying to explain solar eclipses. I did it the usual physics way: diagrammed them on the board, with the lines and so on. It was simply obvious that the kids just had no idea what I was talking about, and it was terribly frustrating. So, I said, okay, fine. I told them, “Please go and get a whole bunch of black sheets of paper from the office, and tape. And someone should get a flashlight, a football, and a tennis ball.” And then, I wanted them to get boxes of chalk. So, they went off to get boxes of chalk. I asked them, “Okay. I want you all to grind all the chalk into powder.” So, the kids grind the chalk into powder and I had them cover all the windows with black paper and tape. We had the soccer ball as the Earth, and the Moon was a tennis ball, and then the flashlight. And I said, “Okay, let’s turn off the lights. What I want you to do: I’ll count to three, and when I count to three, I want you to throw the chalk dust up into the air. One, two, three.” And then __the lights went out and they saw this beautiful, conical shadow hitting the soccer ball, and they immediately understood how this thing worked. And so, yeah, I just sort of discovered that this is what you need to do. You need to have something that’s vivid and engaging, not just lines on the blackboard. I discovered that I enjoy explaining things to people. Of course, I can imagine the cleaners were not very happy with me, but the kids obviously learned something. Like I said, that’s just one important thing. This is also where I met the person who would become my wife. She was a French girl who was there as a French assistant for that year. There are these images that are burnt into one’s memory, that will be there forever. I remember going to the staff room for tea, as one does in England, and on the far wall was this beautiful young woman, I later learnt was from France, a white girl who — I can remember distinctly — was wearing black corduroy jeans and a brown waistcoat and a white shirt, leaning against the far wall. I was just stunned. I thought I’d never seen anyone so beautiful in my life. That was just a fleeting image, but fast-forward a few months. The beautiful young woman came to me, and she said, “Look, I and this German boy and this Spanish girl are renting a house in Rochdale. But it’s very expensive. There’s a spare room, and we need to have one more person who can share the rent.” And I said, “Yeah, sure.” I mean, I was happy to do that also, because at the time, I was commuting from some small town in the middle of Lancashire every single day, back and forth, which involved taking the bus, and then the train, and a bus. It was a big mess. So, this was great. I would be living in this town. And, coincidentally, in the same house as this young woman. [laughs] So, to cut a long story short, my plan to apply for a postdoc position in La Jolla, California, changed, of course, because Marie-France turned out to be far more interesting. And so, what happened was that this: in 1981, at the end of the school year, she went back to France, and I was out of a job. But I then got a small job working in this tiny startup company, and my tasks were two: one was to do micro-coding for some telecommunication device, so I had to learn about telecommunications and so on; and the other thing was to do some coding to control disco lights. [laughs] So, two rather different things. But that was very fun, trying to figure out how to make the lights do all kinds of funny things, and in the afternoon, working on the microcode. Basically, what we had two signals coming in, which had to be spliced together and interleaved in some way, with lots of error-checking. I worked on those two things. I did that only because my interest at the time was to save enough money so that I could go to France to go and see my girlfriend. This was okay for a while, but, eventually, I thought, “oh, my goodness,” I need to get a real job, really. So, I applied to the Rutherford Lab in Oxfordshire. And, I have to say, again, I pity my young colleagues today, because I think the competition today is just ferocious for jobs. I’m sure it was hard in those days too, but my recollection is that I wasn’t anywhere near as ferocious as it is today. I applied to this one place, and they said, “Sure, come down for an interview.” [laughs] And I tell you, the day of my interview, going to take the train, I had foolishly forgotten to prepare — I had no clean trousers. And so, I went to my sister and said, “Can I borrow your jeans?” [laughs] This was kind of the attitude. There was not the sort of desperation that I see in some of my young colleagues.

Zierler:

Where was the interview?

Prosper:

At the Rutherford Lab in Didcot, Oxfordshire. I had to take the train all the way down from Rochdale. I went to this interview and talked to Chris Batty, Keith Green, and a few other people, and they said, “Okay, sure. You have the job.” What particularly appealed to me was they told me that the actual work is in Grenoble, France. I said, “This is ideal. I’m game. Sure.” I think it was January ’82, when I was shipped off to Grenoble, France, to work on two amazing experiments, absolutely fantastic experiments. One of them was looking for neutron antineutron oscillations, because, at that time, I got much more interested in theory, and so, there was this amazing idea that if you impose an SO(10) symmetry on SUSY, one of the possibilities could be neutron antineutron transitions. You could actually have a situation where a neutron could transform into an antineutron, thereby violating baryon number by 2. And I read those papers, and it just seemed very exciting. And sure enough, that was one of the experiments that people wanted to do in Grenoble. Unlike today, in this particle physics experiment, there were just a few people, and I was the sort of main postdoc at the experiment at the Institut Laue Langevin (ILL). The other experiment was using ultracold neutrons to measure the neutron electron dipole moment, the Norman Ramsey experiment. Those experiments were thrilling, because, you know, if I wanted to have a meeting, it was easy, because it was a meeting with myself. [laughs]

Zierler:

Right.

Prosper:

I could do anything I wanted. I just loved this freedom of being able to decide what to do.

Zierler:

Harrison, how was your French? Or, was English the lingua franca?

Prosper:

Of course, in school, I learnt French for a couple of years, and so I knew enough — and especially having met Marie-France — I knew enough to be able to get by. I could do the shopping and so on in Grenoble.I made lots and lots of mistakes, even to this day, but it was good enough to function. But I have to say, this was again one of those glorious times of my life, because of the intellectual freedom to do what I wanted to do. For example, the neutron electric dipole moment experiment itself was within the containment building of the nuclear reactor — a research reactor. And of course, there were lots of protocols one had to follow to get to the experiment. One of the absolutely crucial things one had to really do is: the safety drills. The siren would go off, and you literally had to “down tools” and leave. There was no ifs and buts about this. But as you can imagine, you’re doing this experiment, and suddenly you had to “down tools,” you leave things in a poor state, and of course, it takes hours thereafter to get them back to a reasonable state. Therefore, I decided to become a hacker. I learnt about how to do remote access to machines using remote access tools. I built tools that would allow me, from my office, [laughs] to hack into the control system of the experiment in order to keep controlling it, even while this drill was in progress.

Zierler:

Harrison, I can’t help but ask if you felt at all like you were channeling your father’s abilities when he learned how to craft precision tools.

Prosper:

Yeah, it could be. It could well be that. You know, the idea of being able to — to really do things like this, and be bold about it. I’ve always felt this is what I really like about physics, if you’re given the opportunity, it’s that you can be bold. You can try different things. And this was just, for me, a thrilling experience, because it really taught me a great deal about the importance of, first of all, being persistent, being bold, and not being afraid to defend your ideas. This is important. The other thing that was, for me, extraordinarily important is the importance of having mentors who are really selfless. And the one person at the time who was absolutely extraordinary in that regard was Maria Fidecaro from CERN. She and her husband, Giuseppe Fidecaro, were on the other experiment, the neutron antineutron experiment, and Maria is just one of those extraordinary people who is forceful, but in a very warm, welcoming way. One thing she taught me — and I’m really, really grateful for this — she taught me the importance of keeping notebooks, of writing down not just technical stuff, but how you felt — who annoyed you that day — just a record of what was going on at the time. I have several notebooks from that era, so I can go back and tell you: this is what I was doing then. And I’m forever grateful for that. She also taught me the importance of precision. When you describe something in a paper or an article, be precise. Be complete. It’s just marvelous. And because she was at CERN, this gave me the opportunity to visit CERN from Grenoble. And that was crucially important, because as the resident postdoc, I was also in charge of doing the analysis of this experiment. We had some data that I had to analyze, but I got stuck on a statistical problem. I couldn’t solve this, because you know, as was true of most physicists at the time, my knowledge of statistics was pretty rudimentary, basic stuff. And so, I was stuck. I went to the ILL library to get out books on statistics, because I thought surely, in all these big tomes, there must be a solution. I read through all these books, nowhere to be seen was there a solution for this problem I had. Maria suggested contacting a person, Dr. Fred James at CERN, who is a well-known physicist who also happens to know a lot about statistics. Why don’t we go and have a chat with him? So, I took the train to CERN. This was 1983. And again — see, this is very important, right, how people treat you on the very first encounter. It really makes a difference. I remember going to the main building at CERN, knocking on Dr. James’ door, and he said, “Come in.” I came in. I introduced myself, and I then explained to him the problem I had. And Fred James didn’t say, “Well, I’m too busy. Come back later,” he stopped what he was doing, he went to the board, started scribbling things on his blackboard. Then I started arguing with him. I said, “No, no, this cannot be right.” He agreed, and we had this amazing discussion back and forth. Remember, this is the first time I’d met him. Never met him before. And because I disagreed with what he was trying to do, he said, “Okay, I guess I agree with you. This doesn’t really make much sense.” He then picked up the phone, and he called his CERN colleague, Daniel Drijard. He said, “Daniel, I have this young man here who has this problem. I wonder whether you could sort of think about it as well,” and he explained to Daniel the problem that I had. Daniel said, “Okay, I’ll think about it.” I think the next day or the day after that, I went back to Fred James’ office, and he said okay, “Daniel has written this for you.” Daniel had written, in French longhand, a solution to the problem, which I still have a handwritten solution, a Bayesian approach to this problem. I had never heard about Bayesian statistics or anything like this. I remember reading Daniel Drijard’s note and being just utterly thrilled at how beautifully simple the thing was. I realized, “Oh, my goodness. There’s a huge, other intellectual world out there, of which I know absolutely nothing,” and that led me, again, onto a quest to try to educate myself in that regard.

Zierler:

And what was that world that you wanted to move into as a result?

Prosper:

That was the world of data analysis, trying to use statistical techniques in order to extract as much information from data as possible. That’s what I saw from Daniel Drijard’s solution. I saw that there was a way of thinking about data analysis that is sort of like Newton’s laws. You have these very basic rules, and they’re simple, but from those rules, a lot can come out. I realized that this way of thinking, even if one did not use a Bayesian method to solve a problem, one can use the Bayesian reasoning to think about the problem. Why do I find that appealing? I found that appealing for the same reason I found particle physics appealing. That is, there’s some basic fundamental rules that you can learn and master, and then once you’ve mastered those, there’s a huge array of problems that one can solve. That was the doorway and that led later on to my interest in machine learning and many other techniques that sort of all came together. And those things were crucial in the next big thing, which is when I was involved in the discovery of the Top quark at Fermilab. So, again, an unanticipated intellectual adventure, which turned out to be useful later.

Zierler:

But Fermilab comes after Virginia Tech.

Prosper:

That is correct, yes. That’s right.

Zierler:

How did the opportunity at Virginia Tech come about for you?

Prosper:

Yeah. So, I worked on these two experiments: the electric dipole moment experiment of the neutron, and the neutron antineutron oscillation experiment. My term with the Rutherford Lab was coming to an end, but then I was offered a position there — a permanent position at the Rutherford Lab. But the idea of going back, living in Didcot, Oxfordshire, just didn’t appeal [laughs] after being in Grenoble.

Zierler:

[laughs] There’s a bigger world out there.

Prosper:

Yeah, and Grenoble’s a fantastic place, because you’re surrounded by mountains. You know, Marie-France and I would go onto our balcony, and we’d look to the left and downtown, and there would be the Chartreuse Mountains. We look straight ahead, and it would be the Belledonne chain of mountains. I go to the kitchen, and there would be the Vercors Mountains. So, every weekend, she and I and our little girl of 1 year old, would go for a hike in the mountains. To go from there to Didcot, Oxfordshire, just didn’t quite cut it. Now, there was this professor from Virginia Tech, Luke Mo, who happened to be in the neighborhood. I don’t know how I got to talking with him about this, but we get talking, and he said: look I have a postdoc position — I told him, “Look, what I would like to do, actually, is stay in Grenoble, but I’d like to work on the next generation of neutron antineutron oscillation experiments.” I’d already been doing some design work along those lines, how to construct neutron beams to make their divergence less. I was already thinking about this experiment, and he said, “Okay, this will be great, because you could work on this, because we’d like you to get involved in this experiment as well, but you’ll be a Virginia Tech postdoc.” And I thought this was a fantastic arrangement. I can stay where I want to stay, I’ve got the connection with the United States, and I said, “Sure. Yes.” So, he offered me this postdoc.

Zierler:

Was the postdoc — Harrison, did you see it as a lateral move, given how advanced your career was at this point, or was it a step up, or did you feel like you perhaps left something on the table just to have this opportunity?

Prosper:

What I felt was that this is what I wanted; this was something I wanted to do. I wanted to work on this new experiment, because we had reason to believe we could increase the sensitivity by a factor of 5 to an order of magnitude, and I just wanted to have someone pay me to do it.

Zierler:

Yeah.

Prosper:

It’s as banal as that. It was an experiment that I wanted to do. So, I said yes. But then what happened is that Prof. Mo came back to me and said, “Unfortunately, the funding that we thought we were going to get didn’t materialize, so we cannot afford to keep you based in Grenoble to work on this experiment. But we do have another experiment at DESY. However, you would have to basically work in the United States. And I said, “Okay. Why not?” I mean, this gives you a chance to go to the U.S. for a year or two and to see what it’s like. And after all, that had been my plan before Grenoble, to go to La Jolla, California. And so, I said, “Sure. Yeah. Let’s do that.” We heaved anchor and moved the family to the U.S. But it turned out that the work was actually being done at Fermilab. Therefore, even though I was a Virginia Tech postdoc, the actual technical stuff was being done at Fermilab. We were developing these photomultiplier tubes and other things for an experiment at DESY called ZEUS. And so, there we were. We were in the United States, and the plan was to be there for a year, two at most, and then return to Europe.

Zierler:

This sounds quite familiar to your parents’ experience, in a very different context.

Prosper:

Very different context. That’s right. So, history is repeating itself.

Zierler:

Harrison, where would you spend most of your time? Was the plan to be mostly in Virginia, and then go to Fermilab as needed?

Prosper:

No. We were based at Fermilab, and what would happen is that the head of the group would come to the lab to discuss progress. So, we were actually based at Fermilab, and in fact, we lived in Batavia, and I was working with another postdoc (or perhaps she was still a student, Bin Lu). This is a delicate subject, but I have to say that I didn’t like the way she was treated, to put it bluntly.

Zierler:

In what way specifically?

Prosper:

Well, she was treated like a personal assistant or worse. What would happen is that the boss would show up, and this young woman felt that she was obliged to simply stay at the lab until he left, even though she had been working like crazy for the past several days, she didn’t feel that she had the freedom to basically just leave, you know, at a normal time. I just felt that she was treated like a personal assistant, not a scientist who has intellectual freedom to challenge, and so on. What happened is that after a while, I would explode with rage, [laughs] and I realized this was not healthy…

Zierler:

Yeah.

Prosper:

…that this was not good, that I had to move on. And so, yeah, again, I’ll be very honest. I left in disgust. Then came this critical decision, right? [laughs] I knew I was going to leave this group, and of course, I had a family. What to do? This was when we had to decide: do we go back to Europe, just abandon this United States experiment, or stay? So, I applied to — I guess what I did then was, I said, “Well, let me at least try something.” So, I applied to Fermilab, since I was already based there anyway. Again, there was no deep thinking behind that. I just thought: I’m at Fermilab already. We’re living in Batavia. We may go back to Europe at some point, but in the meantime, I need to have something. So, I applied to Fermilab for an associate scientist position.

Zierler:

And Harrison, at this point, I want to just broaden out the conversation a little bit, because as if your identity was not confusing enough in Britain, here you are in the middle of the United States, where I assume by appearance, you’re perceived as an African-American. Right?

Prosper:

Absolutely.

Zierler:

Right? And here, you have this erudite accent, and so — and of course, the United States —

Prosper:

And I’m married to a white French woman. [laughs]

Zierler:

Right. Right. And of course, the United States has its very own problematic history with race relations, to say the least, very different than Britain.

Prosper:

Right.

Zierler:

What were your experiences in that regard, and how might that have influenced these bigger decisions you were making, now that you were at this crossroad, both personally and professionally?

Prosper:

Yeah. Thank you. This is a good question, and I think it’s a very poignant one now, because I have to say that I have — you know, for my entire life, I’ve experienced my share of blatant, obvious racism. This has happened; this is true. But it also has to be said that I’ve also experienced the kindness of people. Utter selflessness. And that’s also important to make clear.

Zierler:

Like your high school physics teacher, for example.

Prosper:

Yeah. Marie-France and I, we decided to go visit the United States in the summer of 1986 to find an apartment, because we’d be moving our 1-child family over there later that year. We arrived in Chicago, and driving along Roosevelt, and entered the east gate of Fermilab. I must say, we were a little bit depressed when we arrived in Batavia, because again, we were coming from Grenoble. [laughs] With the mountains, and so on. And here’s this dead flat place, right?

Zierler:

Yeah.

Prosper:

With these pastel-colored buildings. It was a bit depressing entering Fermilabvfor the first time. But then I saw this amazing building in the distance, and I thought: wow. I’m arriving at this special place…

Zierler:

Yeah.

Prosper:

..even though we had this feeling of having left something that we really enjoyed.

Zierler:

Harrison, did you have any concept of what a national laboratory meant? Are there any equivalents to that in…

Prosper:

Yes.

Zierler:

…either France or Britain, or this is a new concept to you?

Prosper:

No, no, no. This was very clear with me, because the ILL in Grenoble is a national lab, and the Rutherford Lab is also a national lab. So, I was very much aware of what these labs do: that is, the scientists there, their role is to basically help researchers that would come in, as well as doing their own research.

Zierler:

Yeah.

Prosper:

It’s something that I knew about. I remember distinctly arriving in downtown Batavia, looking quite lost, obviously, because someone had just come up to us, a perfect stranger — right? This white person had come up to us, and we were a mixed couple, and said, “Can we help you?” And for me, I don’t know, it was unexpected. I said, “We’re looking for a place to live. We’ve just arrived.” And they gave us some hints about where to go. That was the initial interaction with Americans when we arrived. I really did appreciate this very much.

Zierler:

You’re very lucky that you had that positive first impression.

Prosper:

Yeah.

Zierler:

Because you very easily could not have had such a positive first impression.

Prosper:

Exactly. And subsequently, of course, I had other not quite so pleasant experiences, but still, I’m one of those people who insists on seeing the world as a glass half full. Because I’ve had enough good experiences along with the bad. I would not be where I am today were it not for a few individuals along the way who just said exactly the right thing at exactly the right time.

Zierler:

Yeah.

Prosper:

Had any one of those things gone a different direction, game over. That is both an indictment of our society, and it’s also a glorious affirmation of humanity — that is to say, that individual human beings can make a huge difference.

Zierler:

Yes.

Prosper:

But it’s an indictment also, because if any one of those things had gone a different direction, I would not have succeeded.

Zierler:

It’s a testament to how fragile the system is.

Prosper:

Exactly.

Zierler:

In other words, your talents and your ambition should be strong enough to survive negative interactions.

Prosper:

Exactly. Exactly. And that’s the thing that, for me, is terrible. And I wonder how many other young men and women there are out there, throughout this entire world who won’t get the chances I got. You know, one of the things I like to quip sometimes with my colleagues, just to annoy them a little bit, is that I tell them — look, CERN is an amazing place, as is Fermilab. Collectively, there are 20,000 people who use these facilities. These are among the very best scientists on the planet. That’s 20,000. Between the ages of 16 and 64, there are 7 billion people.

Zierler:

Yes.

Prosper:

So, the probability that among the 7 billion people, we have fantastic ideas that are off the wall, that are truly creative, is extremely high. I would love to have a system whereby, among that 7 billion, we can give opportunities to those people who can change the world. It shouldn’t have to depend on the good graces of these selfless, gracious, few along the way. Even to this very day, there are people who are completely selfless, and they do things on my behalf, for no other reason than they want to help. So, I’m truly grateful for this. I’m really grateful for this. But again, still, it’s an indictment that things are so fragile.

Zierler:

Harrison, what was that initial project at Fermilab that you got involved with?

Prosper:

When I arrived there, the way things were done in those days is that you had the choice. You could choose which project you wanted to work with, and got some startup money, etcetera. And because of my experience hitherto, I was involved in small experiments with just a few people. I was basically, you know, the person doing most of the work. That was what I wanted to do: something small. But I was persuaded by my late Fermilab colleague, Rajendran Raja, who subsequently became my supervisor, I was persuaded to put aside my reservations about joining a large experiment and join the DZero experiment.

Zierler:

Yes.

Prosper:

And he said, “If you join the DZero experiment, you have a chance that you’ll be able to participate and contribute to the discovery of the Top quark.” And given the absolute thrill I experienced at DESY with the discovery of the gluon — participating in collecting the data for the discovery of the gluon — that, of course, was very appealing to me.

Zierler:

Yeah.

Prosper:

So, I said, “Okay, fine.” I hate the idea of working in this huge collaboration of 100 people, whatever it was, but let me go for it. And so, I joined the DZero experiment, and with the goal of really contributing to the discovery of this — really looking for this thing and making contributions. But, Raja was of Indian origin, and that is when I began to see the other side of things. The initial experience that we had was wonderful, of course, but at the lab, I saw my advisor — who sadly succumbed to cancer some years ago — not get the full credit is deserved. He was one of the most brilliant people I’ve ever met. An astonishingly creative fellow. But the way he was overlooked — again, I don’t want to cast aspersions on my colleagues at Fermilab, but my late former supervisor should have done better in his career trajectory.

Zierler:

The fact that he was Indian held him back, you’re saying.

Prosper:

Yes. I hate to say this, because it’s really shocking to have to say this, but this is my honest opinion. And again, it’s not that it’s overt. It’s just that…

Zierler:

Yeah.

Prosper:

…one sees others move on in their careers, and others, often more deserving, remain stagnant.

Zierler:

It goes to show also how deep these things run, because you’d think that perhaps somebody like a Chandrasekhar would have made it so that people would say, you know, “Maybe Indians can really contribute in physics.”

Prosper:

Yeah. Right. And you know, he did not get the Nobel Prize until his 80s, even though his was an unbelievably spectacular contribution to the field of astrophysics. Rajendran Raja, this really extremely creative fellow, was very supportive of me. He was a fantastic mentor. He had an incredibly high standard. But that’s what I wanted. That’s what I was accustomed to, you know, being held to a high standard. He had an incredibly high standard and — I have to confess, he didn’t suffer fools lightly. If you didn’t achieve this high standard, he was sometimes a little too brutal…

Zierler:

Yeah.

Prosper:

…in his manner. And that was unfortunate, because there were two people who, I think, suffered badly because of this. But still, if you did reach the standard, he would defend you to the very end. [laughs] But I just find it incredibly sad that someone of that caliber didn’t advance as much as his peers did. And again, it’s not overt. It’s not overt. It’s just that the system has not been constructed to allow persons like that to advance, in spite of our biases. You see, we all have biases. We all have biases. We all have blind spots. But the problem is that we’ve built a system where, unfortunately, those biases and blind spots govern what we do.

Zierler:

Yeah.

Prosper:

And that’s wrong. I began to see these problems, and that I found very depressing, because I thought: well, we’re in the world of science. We’re all about searching for truth. We’re all about trying to cast aside our differences, and so on, and yet still in that environment, these biases persist. It’s very depressing, actually.

Zierler:

So, Harrison, on the positive side of things, particularly among white people, where it would be so important to have them as allies in this regard: who were some of those people where you felt like — you know, on the DZero, they were a force for positive change? Who might have been some of those colleagues of yours who represented that?

Prosper:

Absolutely. Yeah. So, hands-down, without a question, Professor Tom Ferbel. I mean, just hands-down. And even to this day — this guy’s retired. He doesn’t have to do anything. Even to this day, he’s still helping me, still trying to be supportive — and it’s people like him — he’s an exemplar of the sort of persons along the way who have been helpful. And he has been consistent. Tom Ferbel. Another person is Kirby Kemper at Florida State. And Jeff Owens and Vasken Hagopian. You know, Kirby Kemper once scolded me and said, “Harrison, if you don’t apply for stuff, you shouldn’t complain if you don’t get anything.” And he was always urging me to apply for this, that, and the other, and really supported me. Tom Ferbel founded the NATO summer school in St. Croix for particle physics graduate students. When he stepped down from that, he came to me, and said, “Harrison, would you like to take over?” It was partly because of my connection with the region, but partly because he wanted to help. And so, for a few years, I ran this thing, and it was, again, one of the fantastic opportunities that I otherwise would not have dreamt was possible. Or, supporting my APS fellowship, these sorts of things. And it’s all selfless. This is what I appreciate about colleagues like Tom, Kirby, Jeff, and Vasken.

Zierler:

Tom, of course, is very different from you, but he’s also a bit of an outsider.

Prosper:

Yeah. He’s a bit different. Right? He doesn’t fit into the mold, and maybe partly that’s why he understands. He has some appreciation for what that is. But the fact is that yeah, again, I repeat: I would not be where I am today, absent the support of these colleagues. And I think it shouldn’t be that way. [laughs] It’s not that this is bad. This is, of course, a good thing. But one should not have to rely upon this sort of fragile string of pearls.

Zierler:

Whoever said science wasn’t a human endeavor, right?

Prosper:

[laughs] Yeah. It’s definitely a human endeavor. And of course, there are times when things happen that are just shocking. Again, I have to be careful. I don’t want to cast aspersions on people. But for example, it was shocking and also wonderful when the Top discovery was announced. You know, there were people who essentially usurped — wanted to usurp — all of the glory. But then, there were people who were quite the opposite. One of my colleagues in Miami, Steve Linn was contacted by some media person and said, “Can you tell us about the Top discovery?” And Steve told this person, “Actually, the person you want to talk to is Harrison Prosper.” He could have said, let me take the glory, but no. He said, “This is the guy you need to talk to.” And so, indeed I got a call from this media person, this radio person, and was interviewed on the radio to talk about this. And so, yeah. It’s definitely a human endeavor. There are people I know — I won’t give names — who likewise [laughs] got calls from various media persons and chose to mischaracterize things. Let’s put it that way.

Zierler:

Harrison, what was the day-to-day like in the search for the Top quark? What would your day look like at the lab?

Prosper:

It was an intense period, especially 1994, because in that year, our sister collaboration, CDF, announced evidence for the Top quark. And of course, all hell broke loose in DZero. We realized that if we didn’t get our act together, we were going to be toast. I’d already moved to Florida State in 1993. So, for me, it was literally back and forth between Tallahassee and Chicago, almost every other week, back and forth, working around the clock through the night trying to figure out how to improve our analyses. You know, hours-long working meetings. At the time, there was a bunch of people who went running at lunchtime at Fermilab. I was among this crowd. We would take some time out to go running around the ring, or down to the Fox River and back, and so on. We’d come back, and we’d work through the night. And there were many, many all-nighters, because we were desperate trying to figure out: how can we improve this analysis? In fact, I recall in the winter of ’94-’95, DZero sent some results to Aspen, Colorado. There was a meeting there where we presented our latest results. But then, there were a few of us, including my colleague and friend Dr. Pushpa Bhat at Fermilab, and a student by the name of Cary Yoshikawa, and others, who were convinced that we could do better. [laughs] We just were convinced we could do better. The student had an interesting idea. He said, “Okay. Why don’t we just try the whole range of different section criteria, and try to find which one gives you the best result?” And he did it in a way that would work but was incredibly computationally intensive. It was just pushing to the limit the computational resources that we had at the time. And so, again, like I said, I was going back and forth, back and forth, between teaching in Tallahassee and going to Fermilab. It was really an incredibly intense time. Another colleague and friend, Chip Stewart, and I were running around the ring, the accelerator, and we’d just come from a meeting that was hosted by _Pushpa trying to figure out how we could improve things. Chip an I were running around the ring, we must not have been running very fast, because we were able to talk with each other, and talk physics. [laughs] So, I guess we were just jogging gently. We were approaching the Wilson Hall (aka the highrise), and thinking. And then, a lightbulb came on [laughs] in our minds. We were so excited that we sped up. We just sprinted to the highrise, got showered, got changed, and within a couple hours, Chip had written a program to implement the algorithm that crystalized in our heads. This was exhilarating, because: boom.

Zierler:

What was exactly that “eureka” moment?

Prosper:

The student Cary had discretized the variables describing the data. Let’s say that you had five variables, and each one is split up into 10 discrete values. You would have this huge grid of points, a huge number of points to search for the best possible selection criteria. What Chip and I realized, which was prompted by the discussion we had earlier with Pushpa, what we realized was that we have a simulation of where, among those variables are the best places to search this space. If you think of the Top quarks as points in this space, you have a cloud of points in the space where the Top quark events should lie, and another cloud of points where the background is most prevalent. What we realized was that we could use the prediction of where this cloud should be in this space as potential selection criteria.So, rather than having a uniform grid of points to search, we had what we called a random grid of points. And because it was a random grid, you’re searching where you need to search, where the Top quark events ought to reside in this space. And it’s fantastic, because it mitigates the curse of dimensionality, because you’re putting your resources where you need to put them. And so, we just sped back to the highrise, and then we just ran the new algorithm. It takes seconds to run, maybe a minute or two for something more complicated, and there it was. There is the optimal set of selection criteria. And so, it was exciting, because we saw that yes, CDF had this beautiful, beautiful vertex detector that could measure very precisely particle tracks, and they had this one event that is just breathtakingly beautiful, where you can literally measure the momentum and energy of every single particle, and you could actually compute the mass of the Top quark in that one event. And we didn’t have anything like this, except later that year in ’94, when we discovered a spectacular electron-muon Top quark candidate event — in fact, it was discovered by my colleague Boaz Klima, who is a Fermilab physicist. In the DZero experiment, we had a data stream called the “express line,” where we would funnel out events that we thought were potentially very interesting, something I was very much involved in building some software infrastructure for. In the express stream was this one event, one collision event, with these high transverse momentum electron and muon, probably the most analyzed event in DZero history. I even wrote the paper on this, and we all worked on this thing like crazy. We were convinced — I convinced myself and other colleagues, and it’s actually in my notebook — that we think this is our equivalent of the CDF Top quark event. And I even went further and actually worked out a way to infer the mass of the hypothesized heavy particle. In the early part of 1995, we were pretty convinced that we were getting there, and so it was just a fantastic time, but extremely intense. Literally, we realized that, especially when we discovered that the CDF was likely to make an announcement later that year, that it was, literally, all hands on deck.

Zierler:

There’s a spirit of competition in the air.

Prosper:

Yeah. But it was thrilling, because, again, it was just one of those rare things that happens to scientists.

Zierler:

Harrison, to go back to that question about the interplay of theory and experimentation: what were some of the developments in the world of theory that might have been useful in shaping how you went about searching for, and ultimately discovering, the Top quark?

Prosper:

Yeah. One of the most beautiful things that occurred was this very nice paper by Dalitz and Goldstein. Before that paper, it was simply accepted that if you had two neutrinos present in an event there was no obvious way to measure the Top quark mass, if and when it was discovered, using these two-lepton events; it was not possible. But then came this paper by Dalitz and Goldstein, this theory paper, in which they showed how, by imposing a probabilistic distribution on these events from theory, by thinking about it in a different way, you could actually arrive at a measurement. And that was incredibly inspiring to me. In fact, I have a notebook filled with calculations that came directly — that were inspired directly from that paper. That was one of the most direct things that came out of this. But really, the influence of theory has been mostly to inspire ways of thinking about analysis. I’ll give you an example of this. When I started learning about parton distribution functions and the idea of jets, and long after the discovery of the gluon, I learnt of the necessity of being able to define jets in a formal way so that you can compare experiments with theory. When I learned about this, I realized that what we were doing at the time in DZero was not actually physically meaningful. We would say take a parton and try to map that parton directly to the jets that we see in an experiment. In discussion with my colleagues at the lab, in particular, Boaz Klima and Chip Stewart, we realized that what one should really do is impose the same algorithm to the partons as one applies to the particles that are seen in the detector. Then the computations — the predictions that are made by theorists at the level of partons could be meaningfully compared with jets at the level of detectors, via jets defined at the level of partons. We actually realized this is what has to be done. And in fact, Boaz Klima and Chip Stewart went off and wrote the algorithm to do that. So, finally, we had a much more meaningful way of comparing with theory. So mostly, the theory has inspired new ways of doing the analyses, new ways of thinking about the analyses.

Zierler:

For you, was the discovery a dramatic moment, or was it something that was confirmed incrementally over time, until finally the evidence was indisputable?

Prosper:

It was incremental in that, you know, [laughs] we’d seen some papers saying: oh, if this thing exists, the mass would be bigger than yea, so much. Right? And then we’d do another paper and say: it must be bigger than yea, so much. But when the paper from CDF came out that said “we have evidence,” and they had one beautiful event, there was this crescendo of activity. So, yes it was incremental and then it was six months or so of “all hands on deck,” no time to spare. In that sense, it wasn’t quite as dramatic as seeing this image of three jets at DESY. For one thing, at DESY, it required no analysis. It was just obvious. It was visually obvious, [laughs] whereas to eke out the Top quark events required really kind of digging, scratching our heads, and trying all sorts of things, whereas the DESY thing was just obvious. The only analogy I can think of is the discovery of the J/psi: turning a knob and visually recording the event counts, and suddenly, at some point, the count went off the scale, and the knob turning continued, and the event count went down to zero again. Then the physicists scanned backwards, then boom. It was a bit like that. At DESY we had this image, this unmistakable image of three jets that we could see on our event displays, and that was exciting.

Zierler:

What else were you involved with at Fermilab?

Prosper:

My day job at the lab was to lead the DZero online controls group, which is interesting, because I was, what, 32 at the time? Rajendran Raja put me in charge of this, and the task of this group was to build the control system for DZero, the online control system — high voltage systems, low voltage systems, and so on. What was interesting for me was that I, a 32-year-old, was in charge of a group where many of the people who I directed were far older than me, [laughs] and in many ways, had far more experienced with these things.

Zierler:

Yeah. 32, you’re a kid, essentially.

Prosper:

Yeah. And, again, it was a wonderful experience. Every day, I was like a country doctor. Every day, I would do my rounds among these experts to figure out: okay, what’s going on? What are the issues that we need to resolve? What results do we need, etcetera? It was a little strange initially, because here is this 30-something directing some 50-year-old guy who’s been doing this thing forever and knows a ton more than I did. But what was great was that they were for the most part very gracious. It was clear that they had a lot of deep knowledge and understanding, there’s no question about it. But what was interesting and useful is that I came with a very fresh attitude and opinion about what could be done. And there’s some virtue, actually, in not knowing too much sometimes, because you can make suggestions that initially might seem impossible, [laughs] and the older scientists would say, “No, no, this is not going to work.” But you say it anyway, because you did not know any better. But that was one of my main tasks, to really run this group and get the control systems ready for when the experiment would start. That’s one aspect. The other aspect was building analysis software because I was in the Fermilab DZero software group. I was very much involved in simulations among other things. There was one particular piece of the simulation that I had to do. We had this beautiful liquid argon calorimeter. At the time, no one had done a precise simulation of its complicated shape, so that we could really be confident that our simulation of the showering in this device was reasonable. So, I took on this task. One of the things I’ve always enjoyed doing is automating things that can be automated. I’m a great fan of letting the computer do the work, if you can make it do the work, so you can think of other things. The problem was this: how do you build this very complicated shape? I thought: okay, I could do it by hand. I could literally write down all the numbers, or I could write an algorithm that would figure out how to build this. I wrote an algorithm to do this. I was very proud that we could finally simulate the precise shape of this device, and therefore, the complicated interaction of the particles, especially in the end caps of the calorimeter. I was involved in all aspects of the __event reconstruction software, especially for the calorimeter. And, speaking of boldness, there was one utility I had written for reading parameters into our analysis programs and our reconstruction program. [laughs] At the time, we were restricted to six characters for symbols, because we used FORTRAN back in the day. Then we went to FORTRAN 77, and we could use more characters. I needed to change every single program in the DZero software library that used my utility to use the new names. So, what do you do, when you’re a 30-something? [laughs] You say: okay. You write an algorithm that would do something crazy, namely, go through every single program, find the name of the routine, replace it with a new name, and hope to God that [laughs] you don’t screw up the entire library. And that’s what I did. And again, it’s just part of the fun of doing this sort of research.

Zierler:

Harrison, one thing I assume you were not doing much of was teaching during your tenure at Fermilab.

Prosper:

That is true, except occasionally giving lectures on statistical things and machine learning, back in the day. It was not formal teaching, but it was giving workshops and tutorials. That’s something I was involved in. Also, the other thing I was involved in when I was at Fermilab was outreach. Every so often, I would drive a truck into the west side of Chicago, some of the neighborhoods there that were pretty depressing in some respects, and this truck would have all kinds of activities I could show and demonstrate, including things with liquid nitrogen and what have you. I would drive there and basically give demonstrations and talk to the students. Of course, it came to an end when I joined Florida State, but I got involved in other things. These were the sorts of things I did, as well as keeping my love of physical activity, like running and biking. And doing the Chicago marathon. The first time I did that — I did it twice — I know precisely because that was the year my second daughter was born: 1991. It was November, and because we were not clear when her birthdate would be, I ran with a pager in the Chicago marathon, just in case I had to bail out. I did the marathon just because it was a challenge. My friend, Chip Stewart, came to me one day and said, “Why don’t we train for the Chicago Marathon? It’s going to be this November.” I thought initially, this is insane. That’s 26.2 miles. I can do 10 miles, barely. My comfortable distance is a 5K. That’s what I enjoyed doing. That just seems ludicrous. But you know, I said, “What the hell.” And so, we trained, and trained, and trained, until finally I could actually do 26.2 miles. And just to convince myself that this was not a fluke, a few years later, I did it again, [laughs] just to make sure that this was real.

Zierler:

Harrison, were you looking for a new opportunity at some point? Did Florida State recruit you? How did that all come about for you?

Prosper:

Yeah. Again, it’s one of those somewhat sad situations. I came from Europe, I had a green card — no, I didn’t have a green card. I had an H-1 visa, which required that it be renewed periodically. And it was always a pain. Whenever I traveled to Europe, there was always a problem. Anyway, I knew that there was a mechanism at the lab to get a green card, but then because of the intense activity that I was engaged in at Fermilab, building up to the start of the DZero experiment, I had missed the deadline for renewing my H-1 visa. In the previous years, I had received an email reminder from someone on the 15th floor of the high-rise stating: oh, by the way, you need to do this, and you’ve got this time to do it in, and so on. I’m sure this email was sent, but I just missed it because of the frenetic nature of the activity I was engaged in. But then, I found the attitude of some of the higher-ups — a particular individual — again, I won’t name any names — very off-putting. His attitude was: well, you know, it’s your responsibility. If this doesn’t get done, you won’t be paid. The reason that bothered me a lot is that I was working intensely hard, but rather than suggesting a solution to the problem, the attitude was: tough. It’s your problem. Deal with it. That is the day — when I heard this — that I said, “I am leaving the lab. I’m done.” I had no idea where I was going to go.

Zierler:

This wasn’t simply about individuals. You’ve sensed that there was a lack of support at the institutional level.

Prosper:

Yeah, absolutely. And of course, when word got out that I was going to leave, it caused a lot of embarrassment. And indeed, I was offered all sorts of things. I was even offered [laughs] to become the — I guess they’re called it the director of the computing division, or whatever — all sorts of things. But I said, no, I’m done. I’m not going to be bought off. I said: at the end of this year, I’m out of here. I’m done. Now, of course, word got out into the open, and I was approached by a colleague at Florida State, and they said, “Look, there’s someone who’s leaving our department. Why don’t you apply?” I said, “Sure, why not?” I applied to all sorts of places. I also applied to Imperial College in London, but I didn’t get a position. It was given to someone internal. There was also an offer of a position in Italy, but I looked at the salaries there, and they just seemed utterly miserable. So, I said, “Sure, why not?” and I applied to Florida State, and I told them, “I’m happy to join you guys, but here are my conditions.” [laughs] They agreed. Green card after my first year and associate professor with tenure after a year — I’ll do it if these conditions are met. And they said “sure.” And so, here I am.

Zierler:

You knew Kirby Kemper before Florida State, though.

Prosper:

No, I did not. I met Kirby when I arrived at Florida State, and he has been just an amazing mentor. You know, he’s the sort of person who practices tough love. He will tell you when you’re screwing up, when you’re not doing the right thing, and be supportive when support is required. And that has been critically important.

Zierler:

Harrison, as an experimentalist coming from a national laboratory to an academic environment, in what ways did you want to ensure that you would have access to instrumentation and laboratories, so that you would continue to be able to do the research at the level that you were accustomed to?

Prosper:

I think the best way to answer this question is that by the time I arrived at Florida State University, I had sort of morphed from the kind of experimentalist who builds stuff — my postdoc days when I did everything, from literally pulling cables to doing statistical analysis at the very end — had gradually come to an end. When I joined Florida State, I was mostly focused on analysis, building software tools, developing algorithms, that sort of thing.

Zierler:

Does that indicate also a certain shift in the kind of physics you were doing also?

Prosper:

Yes. Yeah. So, one of the things I was interested in was searching for new physics, which was becoming a bigger thing in those days, and that required a different kind of mindset, because there, the question is: well, how do you look for something when you’re not quite sure what you’re looking for? How do you maximize the sensitivity of analyses and so on? And so, I became much more interested in, for example, machine learning techniques. Not just as a tool to use — I actually wanted to really understand, mathematically, what these things were doing. So, I really did a deep dive in trying to understand these things, partly to demystify them, because I was getting quite concerned that these things would develop an aura of magic. So, there was this shift and I didn’t really need to have lab space at Florida State, because when I worked on test beam experiments, those were done at CERN or at Fermilab, where we did small experiments. For example, one of my grad students and one of my postdocs, worked on characterizing silicon photomultipliers at CERN, which was a very detailed experimental investigation. But for the most part, it was a transition to more — okay, here are the data. How can I best extract information from them?

Zierler:

So, to be clear, when you left Fermilab, even though you left in frustration to some degree, you were careful not to burn bridges, because you still wanted to be able to come back and do the work that you wanted to do.

Prosper:

Yeah. That’s right, because — it’s funny, because it’s not the lab, per se, because Fermilab is a fantastic place. There’s no question about it, and I went to work exhilarated every single day, because this was a place I was given opportunities. I mean, as a 30-something, being in charge of this incredibly important thing, because if that failed, we would have been in a mess. I was rewarded: the honor of the very first public presentation of results from DZero was given to me. This was thrilling. [laughs] And of course, because it was the very first public presentation in Wilson Hall, everyone in the experiment wanted to have their slide in my presentation. I collected all these things, put together this talk, and even as I was walking down the stairs to the front of Wilson Hall to give this presentation, there were literally colleagues coming down the stairs with me, handing me their slides [laughs] to put into my presentation. This was great. Right? I mean, it’s the very first presentation, and I want to say I was grateful for this, because it could have been anyone else in the collaboration, but I was given this honor. And also, by the way, that was also when I learnt about PowerPoint, because of one of my younger colleagues, Laura Paterno, a computer scientist. I was, of course, doing my slides by hand, scribbling the things by hand. Laura looked at my slides and said, “Harrison, this is not going to work. This is awful.” [laughs] “This is really not going to work.” And she said, “There’s this thing called PowerPoint. Let me teach you how this thing works.” She gave me a crash course on this new-fangled thing, and she helped me put together the slides that were half decent. So, not only was it the first public presentation of DZero results, but it was also the first use of PowerPoint in DZero as well. [laughs]

Zierler:

[laughs] Oh, wow. Harrison, can you talk —

Prosper:

So this was fantastic.

Zierler:

Can you talk a little bit about your work for HEPAP in the late 1990s? Of course, this is after the rise and the fall of the SSC, and high-energy physics in the United States is very much asking itself the most basic existential questions about its future. So, can you talk a little bit about your involvement and what was going on with HEPAP at that time?

Prosper:

Yes. When I was appointed to HEPAP, it was a difficult situation. The field was in a bad state, and there was really a concern that we didn’t have a clear vision about the future of particle physics.

Zierler:

Yeah.

Prosper:

But I have to say that I was a little — again, I’ll just be very frank — a little disappointed with being on the HEPAP, because I thought, “Well, this is supposed to be the organization that maps the future.” I just felt that we were insufficiently bold. I just had this feeling that we —

Zierler:

Meaning, that there should be large-scale projects in the wake of SSC?

Prosper:

Yeah, that’s right. Really bold, and to say, “Yes, this was a disaster. We’ve learnt from it. Let’s go for bold and go for broke.”

Zierler:

Harrison, how might your work at CERN have influenced your ideas about the future of high-energy physics in the United States?

Prosper:

What I find interesting about the Europeans is that — and of course, it’s a different culture – they tend to have a longer-term vision for things. I’ve often lamented the fact that we seem unable to think really long term — though, as is the case right now, we have a process to try to figure out what we’re going to do for the next decade or so. I like the fact that in Europe, CERN, a place like that, they can be assured — no, not “assured.” They’re never assured of anything. But there’s a greater sense that they can rely upon the agencies and countries to say, “Yup, we’ve agreed this is what we’re going to do, and this is the plan for the next 10 years.” This, of course, is not the way things work here, and this has been problematic. However, now that I’m a member of this huge collaboration — as a matter of fact, the chair of the collaboration board of CMS — I do fear that the time scale of these experiments, preparing them, is so long that there’s a danger that the field could actually become less attractive to 20-somethings.

Zierler:

Well, why would they even bother pursuing it in graduate school if there’s no work to be had after graduate school?

Prosper:

Yeah. Oh, there’s that, but there’s also just the fact that someone who is in their 20s may not see the fruition of their work until they’re in their 40s.

Zierler:

Yeah.

Prosper:

In my 20s, if someone had told me, “Oh, by the way, it’ll be 20 years before you would be able to discover X, or do this,” I would have literally said, “No way. I’m going to do something else” — and that is the concern I have, which is why I’m urging my colleagues — when I have time to participate in some of these broad discussions, that sure, we need some big new machine, but we also need small things. You know, everything takes 10 years. Okay, fine. But we need things that are small enough so that bold, dynamic young people can really take risks and do things which are interesting to get them excited, in addition to planning for the thing that’s going to be coming online in 2050. And that’s a real problem, I think, and we haven’t resolved this issue. And I don’t see how that is going to work, to be honest.

Zierler:

Harrison, one aspect we have not yet talked about is your work as a teacher to undergraduates and a mentor to graduate students at Florida State. So, let’s first talk about your undergraduate teaching, and this goes back, of course, to your discovery that you loved to teach, and that was sort of an accidental discovery on your part.

Prosper:

Sure. Yeah.

Zierler:

What have been some of the most productive and enjoyable undergraduate courses for you to teach?

Prosper:

For many years, I taught an introductory physics class — you know, Newton’s laws and electricity and magnetism. I particularly enjoyed office hours. These always became sort of little tutorials that students would come to. Those are fun and interesting, because I had many experiences in which students would send me an email where it was quite clear that a lightbulb came on. What is wonderful about those courses is that once you convince students that Newton’s laws really work, [laughs] and they work in all circumstances in classical physics, once you really convince them this is true, then a lightbulb comes on, and they realize that in every single circumstance, even without doing any calculation, they can figure out what should be happening. Every semester, there was always this group of students who initially didn’t do very well, but they get to that point where they realize: yup, these rules, in every single circumstance, they’re true. And once you realize that, you can then make an assertion about what’s happening. I’ve always loved very vivid images of things. I have these little monster trucks that I used to bring in and say: okay, let’s forget about massless strings and all this nonsense. Let’s think about a real situation. You have two monster trucks pulling against each other with a heavy chain between them, and this guy is able now to drag and accelerate in this direction. And I’d tell the students: okay, the truck has mass. The chain has mass. The other truck has mass, and it’s accelerating in this direction. Tell me, what is the force at this end of the chain and that end of the chain? Don’t tell me the number, just give me some qualitative reasoning. And the students who get that these laws really work in every circumstance, they come back and say, “Ah, yeah. Well, it’s obvious. The chain is accelerating.” Well, f=ma, “a” is nonzero. So, there must be a net force there, which means the force on this end must be bigger than the force at that end. End of story.” And to get them to that point without any computation is just a thrilling thing. It doesn’t always work, but that’s something that I’ve enjoyed. The other thing I’ve enjoyed at Florida State is this amazing program called the Young Scholars Program, where we invite bright high school students to FSU during the summer. For many, many years, I taught the physics part of this program. Now, these are bright kids. Bright teenagers. My task: teach them relativity, special relativity, and get them to the point where they can actually explain and describe some of the paradoxes. Again, no computation, just pure conceptual reasoning. The thing I’ve always enjoyed is, again, making things very vivid. So, the first week or so, I try to get them to the idea of thinking of space and time as a thing. Think of it as a thing, an actual thing, that can be sliced in different ways — okay, it’s four-dimensional, which is a bit of a problem. You can’t visualize it. But still, it’s a thing, a four-dimensional thing. And now, we’ll get them to the point of saying, “Okay, if you slice this thing, what’s the dimensionality of the slice, the surface?” And eventually, they get to the point of saying, “Well, it’s just like an orange. Oranges are three-dimensional things. I slice it. The cross section is two-dimensional. So, by analogy, if I slice this four-dimensional thing, the cross section is three-dimensional.” I said, “Yes! That’s right.” And that slice is space. But because you can slice the thing different ways, you have different spaces. So, once they have this image in mind, I say, “Okay, now think of a worm or a thread through this thing, in two different directions, and at every single point along that thread, that’s the direction of time for those people at that point.” So, if you slice through this line, then that is space at that instant for that person. And, eventually, after a week or two they have this vivid image in mind. Then I can move towards doing quantitative stuff, and then eventually, there’s this fantastic — this just utterly fantastic problem that was the cause of a lot of discussion among physicists in Japan some years ago. It’s a paradox involving two spaceships that begin accelerating at the same time in the frame of reference of the Earth, and then they stop accelerating after some time, and then you have to answer some questions about it. Usually, I can get about half the kids at the end to correctly explain and resolve that paradox, and to me, again, it’s just fabulous. I enjoy seeing lightbulbs come on in kids. It’s just wonderful. So, right now, there are kids out there who may not be able to calculate anything with relativity, but given a picture of some paradox, they can work through it and tell us how to resolve it.

Zierler:

And on the graduate side of things, who have been some of your most successful graduate students at Florida State?

Prosper:

One of my most successful grad students is now a postdoc at the University of Hamburg, Germany. At Florida State, we have students who you know could have got into wherever, but for whatever reason, they decided to come to us. Sam Bein was one of those students. He was working with me on testing a supersymmetric theory, the so-called phenomenological minimal supersymmetric standard model (pMSSM). I told him: okay, I want you to learn about supersymmetry. Learn enough so that when you present your project, you can give enough background on SUSY to convince people that you really know what this is. And of course, I was expecting the typical superficial thing from a grad student, because this is a complicated theory. But when he gave his presentation, I was blown away. [laughs] I mean, it was far better than I could ever dream of doing. It was beautifully done with real understanding of what this thing is.

Zierler:

What was his real talent that struck you?

Prosper:

The real talent that struck me, really, was his thinking out of the box, thinking just differently from his peers. For example, we had to have a way of visualizing the high dimensional parameter space of this theory, and we were just struggling. Out of the blue, he said, “Oh, parallel coordinates.” “What the hell is that?” I said. [laughs] Sam could always come up with something that was very novel that no one had thought about, and that was the thing that most struck me, just thinking of things differently — this was very, very impressive to me, because that’s what thrills me, is when something unexpected happens like this. Sam made a discovery which was very interesting during his Ph.D. This theory is basically the MSSM — the minimal supersymmetric Standard Model — in which one imposes some mild conditions that are consistent with what we know, and then it was shown by JoAnne Hewitt and company in 2009 that you can reduce the parameter space from 120, whatever it is, down to 19. It’s still large, but what was interesting about this particular theory is that it was a reasonably good proxy of the full theory. The thing that’s always bothered me — that’s always been a big bother to me — DZero and CDF spent quite a bit of effort testing these theories, the MSSM and so on. But because of computational limitations and also tradition, we did things that I thought were, strictly speaking, not very meaningful. We would say, “Ah, let’s make an assumption about physics at 10¹⁵ GeV. Given this assumption, we collapse things down to a theory that only has two or three parameters, and then we proceed to set limits on those parameters. I was engaged in this nonsense. It’s not useful. It is too contingent. It says: this is the limit on these parameters, if this, and this, and this, and this — if all these things are true, that’s what we can say. And for me, what I want to know, what I would like to know, by the end of the LHC era, is: is the hypothesis of lower-energy supersymmetry true or false? I don’t care about the details. I want to know, is that hypothesis true or false? And so, when JoAnne Hewitt and colleagues came out with this paper in 2009, I was very pleased. I thought: aha! The pMSSM is a good proxy of the MSSM, and therefore, if we can either discover or exclude this theory by the end of the LHC era, then we will have said something very meaningful about the MSSM, which makes it much more interesting than these very, very constrained models. One of the things that Sam discovered was that half the parameter space that was potentially accessible to us had been excluded by the CMS data, and ATLAS found the same thing. Of the remaining half that was not excluded, half of that parameter space had large cross-sections. We were puzzled; if the cross-sections are large, why have we not been able to say something about that part of the pMSSM parameter space? Sam discovered that the phenomena predicted in that part of the parameter space involved low transverse momentum, low missing energy events. Alas, this is exactly the sort of events that we have excluded, a priori, [laughs] because we tend to be looking for things at high transverse momentum. That was a wake-up call. That was really an eye-opener; that we may be throwing the baby out with the bath water because of our prejudices as to where new physics should lie. Coming to realize that was great. But, how to solve the problem and how to work in the dirt, [laughs] as it were, is still an issue that we’re trying to understand.

Zierler:

Well, Harrison, just to bring the narrative right up to the present: what have been some of the projects that you’ve been working on in recent years?

Prosper:

In December 2009, my then-postdoc, Sezen Sekmen from Turkey, came to my office at CERN very frustrated. She said, “Look, Harrison, we’re constantly having to write programs by hand to extract data from our datasets to make these reduced datasets, these so-called ntuples. And everyone in CMS has their own thing for doing this. Surely, today, in this day and age, we ought to be able to automate this.” And of course, I went: boom, automation! That’s the thing I like to do. And so, we were on our whiteboard, thinking, doing some brainstorming, and we realized that we didn’t know how to do it in December 2009, but we concluded that it ought to be possible, with the software technology that was available. I just took the bold decision and said, “Yeah, I’m going to try. I’m going to see.” And indeed, a few weeks later, there was the first version of what we would call the TheNtupleMaker, which is literally a system whereby you can specify in a text file: these are the things I want to get out of this pile of data, and it automatically builds the software, whatever it is, to do this. So, one no longer has to do any coding. In fact, right now this morning, actually last night, I was working on some version of that tool for the new datasets that we have in CMS. Then came another far more ambitious idea from my former postdoc, Sezen Sekmen. In 2015, she introduced this idea. At a workshop in_Les Houches France, Sezen presented her plan to develop a language that would allow people with an idea that they would like to try out, but who do not have the expertise for digging into our data, to try out the idea. We’ve been developing this domain specific language since then. I’ve been involved in many of these technical things. But on the physics side, I have been interested for a long, long, time in quantum chromodynamics at very high transverse momentum. The reason I’m interested in that is because of a very generic prediction that if quarks are composite then just as was the case with the SLAC 1960s experiments, where there was a rise of the cross-section, when the probes were able to, in effect, sense the partons within the proton. Likewise, if we have enough momentum and energy, we can sense the substructure of the quarks; you should expect to have an enhanced cross-section at high transverse momentum (PT). I’m interested in looking at that because it’s very generic, and I like to do things which make general statements about things rather than statements of limited validity. So, I’ve been working off and on with my colleagues at DESY, Hamburg, to see whether there’s a way to do this investigation in a way that is meaningful. Because one of the problems, of course, is that as you go to higher and higher PT, our ability to measure the energies becomes progressively worse. There are many uncertainties that we have to take into account, not least of which is the uncertainty in the parton distribution functions (PDF) that directly affect our ability to say anything that’s meaningful. One of the things that my colleagues and I have been looking at recently is whether there’s a way to do the analysis where we look for something new while simultaneously fitting the parton distribution functions. The reason that’s important is because what we currently do. We fit predictions — well, theorists fit the PDFs by comparing predictions with data, assuming the validity of the standard model. Then, we use these PDFs to search for new stuff. So, you can see where the problem could be. What if there’s already new stuff in the data that we use to fit the PDFs? How would you be able to disentangle this?

Zierler:

Also, we know that there’s room for improvement in the standard model.

Prosper:

Yeah. We want to basically do two things: to do a search for deviations at high PT, high transverse momentum for all the jets, in the traditional way, and then either find something or set a limit, and do the same thing, where in addition to looking for the same deviation in the same way, we also simultaneously fit the PDFs. Surely, if you’re looking for something — if you have an hypothesis that you’re testing for some new physics, then you should at least check that if you were to include the hypothesized new physics and simultaneously fit the PDFs and do the search, you get the same answer as you would if you assume the standard model PDFs and did the search. Right? You’d like at least the results to be insensitive to which path you’ve chosen, because if they’re sensitive to the path chosen, then there’s a problem. And this is also, by the way, the reason that I have been advocating at the LHC, amongst my colleagues, the need to put a lot more effort into improving our simulations because of my concern that by using data-driven methods where we say: let’s go to this part of the phase space where we think there are no signals, and we should use the data there to make a model for the background that will apply to the signal region. This all sounds wonderful. But again, the same problem can arise. What if, in the region that you claim may not have any signal, that there are signals? Then, how do you take that into account? I don’t see any way around this, other than accepting that we have model, the standard model which is very, very, well tested, and we should put more effort into being able to simulate that model — the predictions of that model very, very precisely, as precise as we can, both theoretical predictions as well as the actual modeling of the detector. Because then, that way, if you see a deviation, it’s either: there’s something new happening, there is some sort of anomalous problem in our simulation — the simulation’s faulty — or there could be a combination of the two. Right? This really bothers me, because we have not seen any new peaks other than the Higgs boson at the LHC. What if the new physics is present as subtly varying distributions throughout the data? There are no resonances, but there are deviations. Then, we could be completely missing them.

Zierler:

And to be clear, you’re able to push these frontiers even without the higher energies that so many people in the late 1980s and early 1990s were saying were required…

Prosper:

Yeah.

Zierler:

…for pursuing new physics.

Prosper:

Yeah. That’s the thing, right, is that even though we may not be able to reach the 20 TeV or what have you, the point is that the new physics can have residual effects at energies that we can probe. For example, let me go back to my own dissertation. I was looking at the simple process of electron positron annihilation to muon pairs. This is long before the W and Z boson discovery. We wanted to test whether or not there were any residual effects that, even in 1979, could be seen from the hypothesized W and Z bosons. And sure enough, there was. There was some hint that just pure quantum electrodynamics was not sufficient to explain the differential cross section. You had to add these extra terms to explain what we were seeing. And so, even though our machines were not capable of directly testing the hypothesis that W and Z existed, because we could not produce them, there were still some residual effects. And so, I believe that this is going to be an important way of actually probing the data for signs of new physics. Just yesterday, we had a fantastic colloquium by a colleague who was talking about one of the experiments I worked on way back. Of course, way beyond what I was doing in Grenoble, but it was the search for the electric dipole moment of the neutron, and I was very happy to see that he was making a point that these beautiful desktop — it’s a big desk, but — desktop experiment, with just a handful of people — within the next 5 years or 10 years, were going to probe scales that are 200 times greater than the scales that the LHC can probe directly.

Zierler:

Yeah.

Prosper:

And this is why I’m a strong, strong advocate of, “Sure, let’s build a 100 TeV collider that’s going to come online in 2060.” Fine. But between now and then, I would like to see a whole host of small, super precise experiments that do one thing very, very, well, that will also give a chance for the creative 20-somethings and 30-somethings to do something they can be really be proud of. That’s going to be important.

Zierler:

Well, Harrison, that’s a great segue to my last question, which is: reflecting back, how academically you really came of age at, arguably, the perfect time in physics for your field. Right?

Prosper:

Yep. Absolutely.

Zierler:

And so, looking to the future, given how much energy and optimism you continue to have, what are the prospects, as you say, for not waiting around forever for these large-scale projects that may or may not come to fruition…

Prosper:

Yeah.

Zierler:

…and yet, continuing to push the boundaries with the resources that are available to you? Can you talk about what the next 5 or 10 years look like within the realm of the resources that are available and under your control?

Prosper:

That’s a great question. Of course, the LHC and its experiments are going to be upgraded. We’ll have a lot more data. In fact, we’ve only collected 5 percent of the data that we hope to collect. But for me, the real breakthroughs are going to be when we start doing what I call “global analyses,” when we start saying: you know what? The data from the LHC, the data from gravitational waves, the data from supernovae, and so on — after all, physics is a unified thing. We ought to be able to analyze all these data collectively and really focus on those theoretical ideas that have something to say about all of these domains. And we’ve already started to do that. An example of this is the work that Sam Bein did with my colleagues, which was a joint effort between Sabine Kraml, who is a theorist at Grenoble, and a few other people including Sezen Sekmen. When we did this study, we decided that it would be good to incorporate constraints from other experiments. Traditionally, we particle physicists do our own thing without taking into account other results from other domains. But our argument was that, well, this is a theory, the pMSSM, that can say something about big bang nucleosynthesis. It can say something about particle physics. It can say something about supernovae. So, if we incorporate all these data at the same time, maybe if we analyze them together, we might be able to see where there are the holes, the discrepancies, and make progress that way. It’s a very general approach, where the more different kinds of data that you use, the more likely you are to find that there’s a mismatch. This is why I love these plots where you have: here’s the thing from the LHC. Here’s something from supernovae. Here’s something from gravitational waves. And if everything is consistent, they should all be consistent. We need more of this, and that, to me, is where I would like to go. I would like to put resources into making it possible for astrophysicists, particle physicists, gravitational wave people, to work together. But that requires a cultural change, because traditionally, we’ve all been jealous of our own field. And we don’t tend to have this cross-fertilization. But this is changing, though. Among the young people, the idea of doing these kinds of analyses is becoming more and more accepted.

Zierler:

It sounds like what you’re really saying is if we’re going to unify physics, we need to unify physicists. [laughs]

Prosper:

Absolutely! I mean, one of the things that we keep on bragging about, which is true, is the amazing connection between the microscopic world and the macroscopic world. Right? This is something that’s just breathtaking. I mean, this is, to me, extraordinary. It’s really extraordinary that at the LHC, we can actually reproduce conditions that were thought to exist when the universe was just a microsecond old, or younger. And so, there is this connection, and yet we all work separately from each other, and this is bad. So, I think the future of science is going to be one where there’s collaborations across these disciplines with intellectual barrriers abroken down, and frankly, I would go even further. I would like to see a time when science is completely open. I once gave a talk in Lyon, France, in 2010 called “Citizen Scientists,” and gave reasons why I thought this was important. You know, the argument’s always, from my colleagues, that, well, if you open everything up, there’ll be lots of horrible papers that are nonsensical. I said, “Of course there would be. So what?” The great thing about science is that it has an automatic filtering process. There’ll be lots of nonsense, lots of mistakes, lots of things, but after a while, we get rid of all the chaff, and something comes out that actually is meaningful. And I personally would be the most thrilled person on the planet if a bunch of teenagers in Zimbabwe, for example, were able to use our open data, CMS open data, make a discovery that we failed to make, because these teenagers thought about the data differently. I would be absolutely thrilled. I wouldn’t feel threatened at all. On the contrary, I would just be excited to bits if that were to happen.

Zierler:

Harrison, I can’t help but observe, going back to the beginning of our conversation, that in some way, the lack of complete identity that you ever felt in one place, inescapably has colored your worldview in science, you know, to push against this idea of protecting turf…

Prosper:

Absolutely.

Zierler:

…or to be sort of closed off to what other colleagues are saying. It’s inescapable to me that this has influenced you.

Prosper:

Yeah. That is absolutely the case. For me, it is really — it’s something I feel strongly about, that this is a human endeavor, and all humans should participate. And it’s not true to argue that the best ideas are among the 20,000 or 50,000 persons who live on this planet and who do this sort of work. You know, there’s this amazing story of Ramanujan, the mathematician, who was spotted by — I think it was Hardy — scribbling something in the dirt in some village in India, or a town in India. And the mathematician looked at what this young man was doing and was simply floored by what he saw. How many of those people like Ramanujan are there right now? This was exciting to me. Right now, as we are speaking, there are probably a million — one in a thousand — a million such young people scattered across the planet, and we’re not able to make use of their creative powers.

Zierler:

Yeah.

Prosper:

That is, to me, a terrible indictment of how we are doing things.

Zierler:

We have to harness it.

Prosper:

We have to harness it. And this is why I’m optimistic. This is why I really do see the world as the glass half full, because I think the potential of our species is staggering. It’s part of our craziness. We’re living at a crazy time. But I think the potential of our species is staggering, but we have to have a different mindset.

Zierler:

Well, Harrison, on that note, I want to thank you so much for spending this time with me. It’s been incredible talking to you and hearing your recollections and insights from so many different parts of your life and career. So, I’m so appreciative of this time together. Thank you so much.

Prosper:

This has been fun, so, great.