David E. Kaplan

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ORAL HISTORIES
David Kaplan
Interviewed by
David Zierler
Interview date
Location
Video conference
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In footnotes or endnotes please cite AIP interviews like this:

Interview of David E. Kaplan by David Zierler on July 13, 2020,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
www.aip.org/history-programs/niels-bohr-library/oral-histories/46735

For multiple citations, "AIP" is the preferred abbreviation for the location.

This is an interview with David Kaplan, Professor of Physics and Astronomy at Johns Hopkins University. He recounts his childhood in New York and then Seattle, and he explains his complex Jewish-Israeli family roots. Kaplan describes his early aptitude for math, and he discusses his education at Chapman College and his transfer to Berkeley, where he completed his undergraduate degree in physics. He explains his near-accidental entrée into the graduate program in physics at the University of Washington, and he describes the formative influence of Ann Nelson. He conveys the excitement surrounding supersymmetry during his time in graduate school and his research on quark masses, and he recounts his postdoctoral research, which was split between Argonne Lab and the University of Chicago. Kaplan discusses the crisis of confidence he felt in his early career and he describes his second postdoctoral appointment at SLAC where he worked with Savas Dimopoulos on supersymmetry and became involved in the B physics endeavor. He conveys his long-held contempt for string theory and attacks it on both sociological and scientific grounds, and he explains the circumstances leading to his hire and tenure at Johns Hopkins. Kaplan describes how he used startup funds to invite speakers to the department, and he explains how imposter syndrome affects faculty members as much as anyone else. He explains the various issues surrounding the cancellation of the SSC, the viability of the LHC, and the prospects of the ILC, and he offers his view on what these projects say about the state of particle physics globally. Kaplan discusses the significance of WIMP dark matter, and why more physicists should work on issues beyond string theory and collider physics. At the end of the interview, Kaplan describes how he tries to make his research an antidote to the problems he sees in the field, and he discusses his ongoing interest in general Higgs decays.  

 

Transcript

Zierler:

OK. This is David Zierler, oral historian for the American Institute of Physics. It is July 13th, 2020. It is my great pleasure to be here with Professor David Kaplan. David, thank you so much for joining me today.

Kaplan:

Sure, of course.

Zierler:

All right, so to start, would you tell me your title and institutional affiliation?

Kaplan:

Professor of physics and astronomy, I suppose, Johns Hopkins University.

Zierler:

OK. And now let’s take it all the way back to the beginning. Let’s start with your parents. Tell me a little bit about your parents, where they’re from.

Kaplan:

My father was born in I guess Palestine. He’s Jewish-Israeli. He is half-Sephardic, half-Ashkenazi Jew. And he was 16 when the Israeli war started, and so he was in the back lines, at 16 and 17 years old, moving his parents around during the war. This is the war of independence, let’s call it, for Israel.

And then he went to—his father was a choral conductor, and he went to the conservatory and became a choral conductor as well. Came to visit the United States for the first time in Aspen, Colorado, at the music tent, and met some famous composers and conductors, Darius Milhaud, and others. And then went back, or did a little driving tour, with a couple of American teachers, of the United States. He returned and years later he ended up eventually in New York, and became director of choral music at Juilliard.

Zierler:

Wow. [laugh]

Kaplan:

And he was also the choral conductor for the New York Philharmonic under Leonard Bernstein and George Szell. And then he—we moved to Seattle. My dad had—well, he had quite a sort of black and white response to people. And when he didn’t like somebody, he had quite a temper.

Zierler:

Enough to move across the country?

Kaplan:

No bones about it.

Zierler:

[laugh]

Kaplan:

Well, when George Szell was the philharmonic director, he couldn’t stand him. He thought he was just ethically a bad person, and let him know it. And so I think it probably hurt him. He stopped getting as many guest conducting positions. That’s my mom’s story. I don’t know if that’s actually true.

But I do know my dad, and that does seem plausible. We moved to Seattle, and Juilliard pays terribly because you’re famous if you’re at Juilliard, so you can get income elsewhere (guest spots). And public schools in the 1970s were a wreck, and so we went to a private school. And it was just getting very expensive, even though we were in a rent-controlled apartment in the Upper West Side. And then we moved to Seattle, and my dad became a professor at the University of Washington of Music.

Zierler:

Where’s your mom from?

Kaplan:

My mom was born in Far Rockaway, New York. And when she was a teenager, her family moved to Miami Beach, and she grew up there. And moved back to New York, had various crazy Israeli boyfriends, seemed to like Israelis, and eventually was introduced to my dad. And they got married in 1965 in New York, had me, had my sister, we moved to Seattle, and had my brother. My mom is a salesperson. She has sold everything under the sun.

Zierler:

[laugh]

Kaplan:

She has sold jewelry, clothing, land, travel—many, many things—and she’s extremely good at it. And we moved to Seattle, and they had a tormented marriage. And about two years after or a year and half after I left home to go to college, they divorced. My dad is 89. He lives near me—I convinced him to move to Baltimore a couple years ago finally. He was living by himself in Seattle. My mom is single, she’s 79, lives in LA.

Zierler:

[laugh] Wow.

Kaplan:

They’re both completely crazy, but I love them both.

Zierler:

[laugh] What—do you know the story of how your—what would it have been, your grandparents on your father’s side? Who fused the Ashkenazi and the Sephardi families together?

Kaplan:

My dad’s dad moved from Eastern Europe. I get different stories of where exactly, but somewhere in what was Poland, I think, at the time at the age of 17, he came—went to Israel or what was fledgling and going to turn into Israel.

Zierler:

As a secular Zionist?

Kaplan:

Well... His father was—well, his father was a cantor. But I wouldn’t even say secular Zionist as much as things were getting bad in Poland for Jews, and so it was really an escape. And so, yeah, I mean, because he came from a religious background in the sense his father was a cantor in a temple but—or a synagogue, but it really was about music. So they were secular in some sense, but studied the Bible and those teachings too—for an academic sense or basically to conduct music and diction and things like that.

Zierler:

Was your sense that Israel was easier to get to than the United States? Was that simply part of the equation, or did they specifically want to go to Israel?

Kaplan:

I suspect it was either possibility and there was a flux in that direction, you know, he started to know some people. I don’t actually know why. I would like to find out why he eventually decided. I mean, the kid went down there, decided it was a good idea, went back up, brought his parents down. Then he met his wife, who’s father had brought them from Bulgaria when she was a child, and they were the Sephardic Jews. And then they met.

She was older than him. They had my dad, and they divorced six months later. They had a very tormented marriage, and then they were basically separated, and my dad was raised by his mother, and grew up speaking Ladino. And then at the age of 5, she decided she was going to remarry, and decided to send my dad to his dad, even though he didn’t really know who he was. So instead she put him—she put him in a kibbutz-like boarding school at the age of 5, and then his dad would come once a week to visit.

His mom would come once a week to visit too. And then eventually he was shifted into the father’s home, the Ashkenazis. He remarried to another Ashkenazi Jew, to a Sabra, someone born in Israel. And they had a child, and that child then died at the age of 2. And then they had another child, and that child lived, and then they had a third child. So my dad had two half-sisters.

And then he would sneak once a week over to meet his mom—sneak because the kids didn’t know he had a different mother. And she was Sephardic, and there was a lot of racism against Sephardic Jews in Israel at the time. And I think that it added torment to him over the years—that, and the death of his sister. And eventually his sisters figured it out, that he had a different mother, because the stepmother was only 13 years older than him.

And then the war started. And after the war, visiting the United States, and coming back, he had a—he led a kibbutz in the north, and also led a chorus in Israel, and eventually just couldn’t take it anymore. And it was some combination of frustration with his family and frustration with hyper-patriotism around what sort of music you’re allowed to play and not allowed to play.

And I think just Juilliard was too enticing, and so he went back. He didn’t—his degree wasn’t recognized there, so they had him do one year to get his—I forget what it’s called back then—the diploma or something. There weren’t PhDs in music – they were just about to start. And then they kept him, and they thought he was amazing. Robert Schumann was the president of Juilliard at the time. He said—he called him the next Mendelssohn.

Zierler:

[laugh] High praise.

Kaplan:

So it became very intense. And then he had this amazing relationship with Leonard Bernstein, and I think that’s propelled things a lot. He—what’s it called? He premiered a number of Bernstein’s choral pieces. He convinced him to debut one in Israel. He did all kinds of cool things. He had a television program on CBS on Sundays for some cultural programming thing. I don’t know.

Zierler:

What’s his name, your father? I want to google him.

Kaplan:

Abraham Kaplan.

Zierler:

Abraham Kaplan, OK. How old were you when you left New York?

Kaplan:

Nine.

Zierler:

Oh, so you remember New York as a kid?

Kaplan:

Yeah, in fact, we went back every summer because he had—I think we’d go back because my mom desperately wanted to be in New York. And he had some gigs in New York that he still did, and then he had some summer school he taught at for talented high school—gifted high school kids in music, you know, for choral work. So we spent every summer basically in New York. And then we—a few summers we would spend in Israel, so I spent a lot of time in Israel, and we even lived for one year when he was on sabbatical in Israel when I was 12.

Zierler:

Did you grow up with a lot of like Zionist pride?

Kaplan:

[laugh] No, no. [laugh]

Zierler:

No?

Kaplan:

[laugh] My dad was suspicious—first of all—suspicious of all religious figures and of any authority.

Zierler:

Ecumenically, Jewish or non?

Kaplan:

Yes, yes. He would constantly make fun of them, and talk about them as scandal-ridden scumbags—not that—he used more flowery language. And, you know, he had a tormented relationship with Israel and hyper-patriotism, which also kind of scared him. He remembers being a kid and hearing on the radio that the Nazis were advancing in Western Europe.

And, I mean, he has the Jewish thing, which is like, you know, they’re going to go against the Jews—that kind of little paranoia stuff, like when that’s coming up, it’s becoming bad. But he doesn’t really have the pride side, you know. He doesn’t think much of the hyper-patriotic leaders or Zionism.

I mean, I’ve never heard him talk specifically about Zionism. But I think for him, it was like it made sense you have a homeland, and that this is a place to escape and be protected and protect oneself. So there was a logic to it that he understood and I think supported and thought well of. But there was a lot of the stuff that he didn’t.

Zierler:

Did you have the basics growing up? Were you bar mitzvahed? Did you have a Rosh Hashanah, Yom Kippur —

Kaplan:

I was bar mitzvahed, and we would celebrate Passover and Hanukkah. Those were the dominant things.

Zierler:

Those were the —

Kaplan:

But we did spend time in Israel—in the year in Israel, we celebrated all of them. I went to an intensive language school for a few months, and then I went to seventh grade basically in Israel in Tel Aviv. So, yeah, I got the—I would say more of the Israel experience than the Jewish experience.

You know, most people in Israel are not religious as, you know, most people in Italy are not religious Catholics. But by default, they are that. And so I remember in 1980 in that year there, or maybe it was ’78 because we had spent a number of summers—chunks of summers there, I went to a little food stand, and I asked for a ham and cheese sandwich. And the woman looked at me like I was completely crazy. [laugh]

Zierler:

[laugh]

Kaplan:

I had no idea [laugh] why.

Zierler:

What’s the problem? [laugh]

Kaplan:

Did not understand. I was trying to trans…I was with my cousin. I was trying to translate what ham is, and I was trying to explain it.

Zierler:

That’s funny.

Kaplan:

[laugh] Yeah. And then in the early ’90s or mid-’90s, I went back and sort of reconnected with the family that my father had sort of disowned—not totally disowned but just never spoke to his mother, stepmom, his half-sister. I mean, he really stayed pretty disconnected from them.

So I went back and reconnected with everybody, and just sort of healed a lot of those relationships, which were trivial because I didn’t have any of the pain, but the mothers did. So we sort of healed a lot of that. And then I just loved going there, and I have this great relationship with all of my cousins.

And I remember in the ’90s, we went—there’s a market like a farmers market, and at night it was a place to go there. There was no signs or anything. You just had to know where it was. And you could get in, and you could get—it was a pizza place, and you could get pizza with prosciutto. And so I’d have a prosciutto and fig pizza—fantastic pizza. It’s called Big Mama’s. But it was still, you know, a little uncomfortable because—

Zierler:

[laugh]

Kaplan:

—you know you shouldn’t be eating that. You can only get kosher stuff but, you know, eventually all that disappeared.

Zierler:

Great. So you went to public schools in Seattle?

Kaplan:

Yeah. We moved to—we were in a suburb. My dad wanted—and I say my dad because this—he was the vocal person about education—wanted to find the place that had the best public schools. And so we went to a suburb, it was called Mercer Island, which was just outside of Seattle, across a short bridge from Seattle. It’s actually where Barack Obama’s mother went.

Zierler:

Oh, really? Wow.

Kaplan:

Yeah, I found out very recently.

Zierler:

And to the extent that talent in math and science is genetic at all, do you have any family connections in the sciences?

Kaplan:

None.

Zierler:

Nothing?

Kaplan:

No, my dad loved—well, my dad had this thing about math that he wanted to get over. Like he had suffered in eighth grade. I don’t even know what level math it was. Maybe it was algebra, pre-algebra or something. He suffered, he did terribly, and then had a new teacher, and then finally was getting it.

And for some reason, that is a story that he repeated multiple times like it was something for him. And at night, he didn’t really like reading stories, so he would come up with math games. And so my storytelling at night as a kid was like I would now call it basic number theory—

Zierler:

[laugh]

Kaplan:

—which is like how do you know a number is divisible—an arbitrary number divisible by 3, divisible by 4, 5, 6, 7, 8, 9, 10, 11, which I had found many years later in the sort of number theory literature. But he was into numbers. There would be riddles, and we’d have sort of logic riddles that I had to solve, and then it was clear that I liked logic puzzles.

We traveled a lot in the early days because my dad was doing guest conducting and had a chorus that toured throughout the East Coast like up from Canada all the way down. And my mom would get me stacks of puzzle books to work through to keep me busy in the car, or in the airplane if we were flying somewhere. And so I was constantly doing puzzles and logic puzzles. I really liked logic puzzles, and that was my education. It was really only that because there’s nobody in my family that has any scientific background whatsoever.

Zierler:

So when did you figure out that you had this aptitude? Was it before your formal exposure in junior high or high school?

Kaplan:

Aptitude—I had aptitude in math. I was never a great student. I was never all-out. I got mediocre grades. I had trouble concentrating. I was in fourth grade when we moved to Seattle.

I mean, I can—I remember strongly in the library at the age of 6 or 7, and constantly going back to the astronomy books, and memorizing information about the planets, just factual details about those things. But I didn’t obviously have an aptitude. In fourth grade when we moved to Seattle, I seemed to be very good at math, and I would for some reason going through the solution books for the fourth grade teacher because there were errors in the solution books. There was some error on an assignment that was corrected wrong. So I would correct all of the solution books for the teacher, and understood that I was good at math, and that was it, just I was good at math—not a genius, not anything.

And my mom would use me as a calculator. So she had a business, you know, selling whatever she was selling at the time. And then she would call out, you know, multiplication things that she needed done—basically two- to three-digit multiplication. She would yell them out, and then I would yell out the answer to her. And so that was my—so I knew I was good at math at home because my mom (naively) was terrible at math. And so it became an obvious…I was the math person at home.

But in school, you know, I was advanced in my classes. I took algebra in eighth grade. I took calculus in 11th grade because I—pre-calculus looked stupid. But in calculus, I got a B and a C for my two semesters. So I wasn’t ever a star student. I had mediocre grades. I was in the bottom third of the class in terms of GPA.

And I hung out with a friend who was into making movies, and so we were making movies all the time. He had a Super 8 camera, and we were making these sort-of spy films a lot. And he convinced me that I should go to an information session about this college in Southern California, Chapman College. And I said, “OK.” I meant the representative and she told me about Chapman College. I don’t remember much of it. She asked, “What would you be interested in being a major in?” And I wrote, “Film and physics.”

Zierler:

[laugh]

Kaplan:

Because they had a big film department, and the relationship with USC, so they had an enormous amount of equipment, and that’s why—and my friend, Charlie, he wanted to go there for film. So I thought, “Sure, I’ll pick two.” But as time went on, I wasn’t really applying to any college.

And my sister who was two years younger was terrified that I would not go to college, and I would never be able to get a job, she finished my applications for me to Chapman College. I believe it’s the only place I applied. I may have applied to the University of Washington with her help, but I don’t remember applying there. It’s possible that I only applied to Chapman College, with the idea of they have a film department, and I’ll make movies. And I got in. Oh, go ahead.

Zierler:

But physics was part of the equation from the beginning?

Kaplan:

Weirdly, and it was only because in senior year, the next physics class you take is—I mean, the next science class is physics, right. There’s an introduction to physical science. There’s biology, chemistry, physics. That’s just the standard steps. And it was senior year—senior year, I had an incredible physics teacher. He had a PhD in physics education—was involved in the physics education core at the University of Washington. His name was Jim Minstrell.

And he was an incredible teacher, though I missed half of his classes because it was the first one in the morning, I was a senior. But I knew that he taught it again in the afternoon as part of a block, math and science block. So I would go in and catch the lectures sometimes in fifth period. And he said, “You really should take the AP exam. You should take the da, da, da.” And I didn’t do any of that. And then he gave me a project with my friend—my best friend Matt—a science project. He said, “Here’s basics instructions of how to build a hover board out of a piece of plywood, some Visqueen, and an old vacuum cleaner.” And so Matt and I built a hover board that winter, and it became a ride at the school fair.

Zierler:

[laugh]

Kaplan:

So he (Minstrell) was engaging me in these because he knew there was something there. And so when I applied, I thought, “Well, I should put physics too just because Dr. Minstrell says I’m good at it, so maybe I’ll put physics too.” Chapman College had one physics teacher who taught one physics class, or at least the one year of physics. That was it.

I got there, terrible student, I barely passed my courses in the first year, more interested eventually in going to Grateful Dead concerts. And I eventually followed the Grateful Dead around the country. And I would take trips up to Berkeley because I had this old hippie cousin, Frank, in Berkeley who—a lawyer who worked for Legal Aid. He was a single dad, and Frank kept encouraging me to come up. So my friends and I would take road trips and go up there. And I remember the summer after my freshman year, we were—we went to bookstores all the time. They were avid readers, and intellectual hippies, and crazy—my friends. I didn’t read much, but I enjoyed the dialogues.

And once we were in a bookstore, and I just walked to the physics section, picked up a book, which now I know is a book on quantum mechanics. And I was looking at the equations in that book, and I thought, “I should be able to understand these things.” And I decided at that moment that I should try to learn physics.

At the same time, my cousin Frank was trying to encourage me to transfer to UC Berkeley and to live with him. And so I looked into it. I had terrible grades. I had taken—I took no physics at that time. And I looked in what would it take to transfer to Berkeley in physics.

Now at the time, if you came from a junior college, community college, and you transferred in, and you were in state, which all it took you lived in California for a year, which I had, you could transfer in to a major, a specific major. And there were grade point requirements for each major. Nobody wanted to do physics, and so the grade point requirement for California State was 2.4 for UC Berkeley in physics. It was a C+. If you had a C+ average and had the basic core classes taken, you could transfer in.

So I said, “OK, I’ll do that.” [laugh] So I took—I went to community college and took the proper core English classes, moved up to Berkeley. It turned out I—there were other core classes I needed to take too, so I didn’t get in in the fall, and so I took more while I was living up in the Bay Area just working. I got into Berkeley the spring semester. And my friends are driving up and back to visit. They slowly all drop out of Chapman and we live together. We go to bars. I bring my physics books everywhere. We’re partying. We go to Grateful Dead concerts. I had my quantum mechanics book. I did terribly at Berkeley.

My parents got divorced at the time. My dad had started to go a little nuts. And probably the year before I graduated, after I had been on academic probation but recovered from that and got to stay in school, my dad had a nervous breakdown. And my brother was still living there. He was 13 or something at the time. And so it turned out my dad didn’t sleep for two weeks straight, and started hallucinating, and all kinds of things. And it turned out he was bipolar. But I was, you know, like 20, 21—at the time, 20 I guess—and went up there. And a friend of the family who had—who eventually had started dating him, but this woman really helped to raise my brother, and was like a godmother to us, Angela. She saw he was losing his mind, brought him to the head psychiatrist at the University of Washington Hospital, and he was committed, and he was in the psych ward for two weeks. And they put him on lithium.

As he tells the story, he acted normal to convince them to let him out. He was terrified of those situations. He stayed on lithium for I think maybe a month, max, and then he went off it. He didn’t like it. And that—it was sort of—appeared to be a result—the divorce with my mom had happened a year earlier. Things were very tormented. My brother had run away at some point but came back when he was 12. So that occurred. And I decided after I graduated from Berkeley, I would just move back up to Seattle to be there. And I wasn’t going to do physics. I finished my degree, and I passed. I barely got myself out of Berkeley with a degree in physics. And then I started working—

Zierler:

So you were not on a track? You were not on a full-steam-ahead graduate program at that point?

Kaplan:

No, no. No, I was like I have to do something good for the world. I’m not just going to study physics. I don’t know what—I’m going to do something. I started working for an environmental organization, one of these lobbying things: CalPIRG. I worked one previous summer for WashPIRG.

The PIRGs are the Public Interest Research Groups. They were started on college campuses by Ralph Nader. And so I worked for the PIRG one summer in Washington State. Then I opened an office in Southern California for a summer. And then I went back to Seattle to be near my dad. I had a girlfriend, and I worked at REI, the Recreation Equipment, Inc. in Seattle in their bookkeeping department. I worked at this outdoor place but I was not an outdoor guy, so I cashiered and I helped the accountant in the basement. And that was it. And I was living with friends in a house, just working. I wasn’t going to go to graduate school. That seemed crazy to me.

And my father and I did not have a great relationship. He was kind of a wreck. And I started thinking—I’m not sure what came first – but two things started happening with me and physics. One was I just decided to start to sit in on graduate courses at the University of Washington. I don’t know what compelled me. I just thought, “Well, you know, I have a physics degree. Why don’t I just sit in?” So I’d sit in on one class. I’d go for a couple of lectures, and then I wouldn’t go. The next semester, the same thing. And at the same time, we decided my girlfriend and I needed to make some money beyond REI, so I put up signs at the University of Washington offering tutoring.

We spent a lot of time making very clever and interesting signs, and I got a bunch of tutoring students that I would tutor in the student hub area at the University of Washington. And for some reason, I was a very popular tutor. I was extremely good at explaining things, and at some point I had 43 students, and I would sit eight hours a day in the University of Washington, one after another, doing physics and some math tutoring.

And at the same time, I had clicked on a class that was like an evening class for a Master’s students in Physics, taught by a guy named Vladimír Chaloupka in the physics department at the University of Washington—also an excellent teacher. And I loved it, and I decided I would stick with this class, and I would actually take the class officially. And it was two quarters maybe of quantum mechanics, and it was brilliantly taught.

It was just this—I remember this moment where the uncertainty principle between position and momentum when he explained that things are acting like a wave, and you can see that if you transform from position coordinates to momentum coordinates that a wave that’s very narrow in position coordinates become very broad in momentum coordinates. Or you can see in the position coordinates, you can see that if the wave is very long, you can put in a single frequency. But if the wave is very small, it’s a blob of many frequencies, and that shows you the uncertainty.

It was just such—there was a visual picture I thought, “Oh, my god, that’s completely clear. It’s completely beautiful. Why? This is the best explanation I’ve ever had. I now get something about quantum mechanics,” and I dove all the way in. And my final project was on the—something that Chaloupka was obsessed with, which is the Bell’s inequality experiment, where you measure something here, and it tells you something about over there, or it changes the wave function, and does that violate causality? No. And there’s this narrow community in physics that is obsessed with that direction. And so he was obsessed with that, and so I learned all about that, and read all about that, and gave a presentation at the end. I liked it.

And then the next quarter, I thought—so that was sort of for master’s students. The next quarter, I thought, “Well, I’m going to sit in on the”—wait, I don’t remember the time exactly, but I went to the graduate advisor, a non-professors academic advisor for the graduate students in the program. I went to her. I was always friendly with staff. Staff people, I felt comfortable with. You know, professors, I didn’t mostly feel comfortable with. Students, I felt shy with. But I could always talk to the staff.

And this woman, I asked her, “What is it going to take for me to get in? You know, I did terribly at Berkeley. I was on academic probation. I can’t really get letters from there. What should I do?” And she said, “Well, take some classes here, get very good grades.” I’d already taken the quantum class, and was top of the class. “Get very good grades. Take the physics GRE, and get some letters from the people here. And that could be your application.” And I said, “Great, that’s what I’ll do.”

So I was sitting in on the electromagnetism PhD course taught by a guy named Phil Peters, and he was the best teacher I’ve ever had. He was truly brilliant. He was Richard Feynman’s TA at Caltech for the years that he was there because I guess Feynman loved him as a TA, and I think he TA’d his—he taught a class on gravity. He TA’d that course. And Phil Peters was just amazing—again, very physical, beautiful explanations for the structure of electromagnetism, which is otherwise a very dry subject, and everybody’s hated subject in graduate school.

And in fact, the textbook was written by David Jackson, who has I think retired from Berkeley. It is the worst, most horrific textbook on the planet that has standardized that subject for some reason, I think in part because it is complete, it’s thorough, and it has the largest collection of hard problems. So people—it’s a rite of passage as opposed to an educational tool—

Zierler:

[laugh]

Kaplan:

—because it has no physical intuition. It just is a bunch of equations, you know. He said, “Look, you can solve this. You can—every equation, you can solve it.” But the solution is such a dramatic mess, there’s nothing in the problems—there’s no clever thing in the problems. Anyway, it’s terrible. But Phil Peters was just brilliant.

And, you know, sometimes I felt like I was a kid. Like he would pass around this jar, and he’d say, “Look, this jar has angular momentum in it. How’s that possible?” I’m like, “What? What does that mean?” And there was a magnet in the jar, there was some wiring inside of it, but angular momentum? It was stored in the electromagnetic field! And so we’re even like at a childlike level, and we’re in the first year of the PhD program, and he was still getting us, so. And then he had a weekly meeting with graduate students who needed—just wanted to talk to a professor, and ask far-ranging questions, advice about the field and physics, and etc. So he was a very special person.

And I took his class, and I was with the PhD students, but I was just some outsider sitting in on the class, and I was in the upper part of the class in terms of grades. And then Phil Peters my—in the second quarter, he had prostate cancer, and he died after the end of the second quarter. He just had a profound effect on me. And it—and because of the beauty of the explanations—you know, I even went to him. I said, “I want to work on electromagnetism.” And he said, “Yeah, you know, it’s a 150-year-old subject…there’s not a lot of new stuff to do in electromagnetism.” [laugh]

Zierler:

[laugh]

Kaplan:

But he worked—it’s funny because I didn’t go into it then but I’m doing it now. He worked in solving Einstein’s equations for complicated systems in gravity, like binary stars, and black holes, and gravitational wave predictions, basically. Beautiful work which is very meaningful now, but he didn’t see the fruits of it.

And then I started—what did I do? Yeah, I started grading papers for another professor, a guy named David Boulware in the department. And David Boulware, which also is a sort of well-known GR person, which I only learned very recently. He had me grade papers for his first-year physics class, and so I did that.

And now I had my three letters. I had Chaloupka, I had Phil Peters, and I had David Boulware. They could write me letters. And then over the summer, I studied like crazy for the GRE because I didn’t open some of my textbooks as an undergraduate, so I had to learn all of the subjects that were necessary for the GRE from scratch. So I was studying all summer. I roomed with two—with three people. One of them was entering the graduate program at the University of Washington, and I was trying to get into the graduate program at the University of Wash. I was studying for the GRE, and I got very a high score in the GRE somehow.

I’m a bit of an idiot savant, you know, I do things very quickly. And so test-taking, if I prepare for it, I can do very well in tests. And it’s like my mom yelling out numbers, I can—there’s some problems—half the problems in the GRE, I can answer instantly. So I either answered instantly or I’m totally lost. It’s not a deep intelligence. It’s just some kind of a facility with numbers and simple formulas. And so I got a very high score.

So I had this very weird record, which is I was a disaster at Berkeley; I had taken one course, you know, in the master’s program in quantum mechanics; one course on electromagnetism as part of the PhD program at the University of Washington; got As in those; a top student in the quantum mechanics course; you know, top three or four students in the E&M course; and these letters; and David Bowler, I was grading papers for him. And so I thought, when I got 910 on the GRE, I thought, “Oh, I should apply everywhere.” So I applied in, you know, a bunch of places. And so then the University of Washington, they knew me, and they thought, oh. They gave me a fellowship to convince me to go there in case I get into other places.

I didn’t get in anywhere else. My record was just too scary—except Berkeley, weirdly, I got on the waiting list, but I didn’t end up getting in. So I got into the University of Washington for the PhD program. And I decided in my first year, I would not be a disastrous student like I was—I got into Berkeley, and then I was a disastrous student. That will not happen again, I decided. I will be the best student in the PhD program.

Zierler:

[laugh]

Kaplan:

And in the first year, I was among the best. Francois—this guy, Francois Lepeintre, was better than me. But I was among the best students in the first year of the PhD program. I got some award. I did all my classes very well. Fine.

And we had just moved into a new building, or the department had just moved in. So when we got to that building, I had this fellowship, which means I wasn’t a TA, but it was too early for me to be in a research group. And so I had no office in the building, because the offices were explicitly set out for the TA grad students, or grad students who were in specific research groups. So David Boulware, he said his group had a free desk. Why don’t I just sit there? I said, “OK.” It was theoretical particle physics. So I said, “Fine.” So I did my first year of classes; did very well. Francois was also then—ended up in that group too. And then they—I thought, OK, I should look around for research to do.

And so I just interviewed all the professors which were nearby, and they were all particle theorists. And I interviewed Ann Nelson, Howard Georgi’s former student—Howard’s best student, according to Howard. And Ann’s project seemed like something I understood and it was interesting. The other projects either I didn’t really find interesting or I didn’t understand them. So I started working with Ann.

And my second year of graduate school was terrible. I couldn’t get things done. I did not know how to do research. I didn’t know how to do problems that didn’t have a guaranteed solution. You know, you work on something. You feel like is this even the right question? You start questioning yourself. I was terrified of working on something that was a waste of time. And I suffered in other ways in my second year—in my classes as well for some reason. I just was doing very badly that second year.

And by the third year, Ann was getting nervous. I wasn’t getting anything done. And by the end of the third year, she was even—she didn’t want to kick me out of the group because I think she was too—she didn’t want to be brutal, and she had very few students. She had come from San Diego where she had no students. She had one other student, a guy named David Wright, and she had me, and that was it. So she didn’t kick me out, but she said, “The group wants to take your funding away unless you get something done.” And so that was my kick in the pants, and then I did get something done.

And the projects were hard, or I would do a project, and I would think, “This isn’t really interesting.” So when I was done with the physics, I decided not to write the paper because it was—I decided it wasn’t interesting. [laugh] And Ann was like, “What? What are you”—[laugh] Or I wrote a paper, and sent it in for publication, and then there was argument from the reviewer—not rejecting it but just saying, “You have—there’s ambiguity here, and you have to do such and such”—and then I decided, “Well, I don’t think it’s interesting.” And so then I just didn’t publish it. And Ann was just annoyed (or something) by the fact her student is not publishing anything. He needs to publish papers. He has to finish his degree.

Zierler:

And obviously this is on the basis that she thinks that this stuff is publishable?

Kaplan:

Yes, of course, yeah. I mean, now I look back and I think, “Yeah, of course it was publishable, yeah.” [laugh]

Zierler:

Right. David, I want to rewind back for a second because I want to understand. Your interest in theoretical particle physics had really little to do with Berkeley itself. It was about your relationship with Ann. That was really the catalyst there. It wasn’t what you brought?

Kaplan:

No, I couldn’t—I didn’t—it was an accident I was sitting in that group.

Zierler:

Yeah.

Kaplan:

And then it was just that Ann made sense.

Zierler:

Right. So that’s such an obvious question. I’m trying to figure out what are the long-lasting impacts of your time at Berkeley. It seems like you almost weren’t even there.

Kaplan:

Yeah, I worked heavily with the political organization, with the PIRGs.

Zierler:

But it’s a world-class physics department, right? It’s like where—what’s the lasting influence?

Kaplan:

All my friends—yeah world-class, that’s all bullshit, man.

Zierler:

[laugh]

Kaplan:

It is total crap.

Zierler:

[laugh]

Kaplan:

Because there are great people who become professors, and they go everywhere, you know, and so—

Zierler:

Yeah. But that’s why it’s world-class because at a place like Berkeley, that’s where these world-class professors are concentrated.

Kaplan:

No. It’s because…yeah, that’s where they’re coming from because there’s a myth that Berkeley is a great place. And so you go to the great place, and everybody else goes to the great place because you’re great. And then, you know, you get some training and whatever—whether the training’s good or mediocre, you are great, and then you’re going to do great. The people who get into Berkeley but don’t go to Berkeley are still great, and they’re going to do great, and maybe they’ll do even better. It really depends on the advisor. There are advisors at Berkeley who are astounding. I mean, there are astounding researchers who are mediocre advisors, but it doesn’t matter because a student will do something with them.

Now, I was an undergraduate at Berkeley. So as an undergraduate [phone rings], it doesn’t—it really doesn’t matter. You can go anywhere. I did—I took quantum mechanics with Stanley Mandelstam, who’s a giant in particle theory. I barely passed the first semester; failed the second semester. And so then I took the second semester again with Bruno Zumino, a giant in theoretical physics. I liked him because he was Italian, and he spoke—talked about physics with an Italian accent, and somehow that made it more compelling. You know, I did mediocre in his class too.

But my friends from Southern California all had moved up. Most of them had dropped out of Chapman College, and they all were living with me. And so then we got an apartment in Oakland. There were five of us living in a two-bedroom apartment. I was paying 185 bucks a month for rent. We were going to Grateful Dead concerts. And I was barely getting through my classes, you know, bringing physics books to bars and stuff to try to learn something.

I really liked my undergraduate E&M professor. He was a—he turned out to be a particle experimentalist, but I didn’t know that. And I did fine in his first semester. And in the second semester, which I needed this pass—his class to pass, I did two out of the 13 homework assignments. I did mediocre on the midterm exam. I didn’t study for it. So I was failing the class. Badly.

And so I went to him some days before the final and, you know, of course my parents and family, everybody’s flying in for the graduation. And so I said, I better pass his class, so I went to him. I said, “What do I need to do to pass the class?” He said, “Well, you didn’t turn in any of the homework, so you need to ace the final. But how are you going to ace the final? You haven’t done any of the work, so you don’t know [laugh] any of it. So I recommend you fail the class, you stay another semester, you do, you know, these set of classes, you get your grades up, and then”— for some reason he said—“then you can get yourself into graduate school.”

And I thought, “Oh, shit, OK.” So I thought about that, and I thought, “No, I’ve got to pass this class [laugh] or—I mean, everybody’s coming. I can’t flunk out.” And so I studied electromagnetism’s second semester for 48 hours straight, no sleep. I did sleep in the end for 45 minutes, and then went and took the exam. And he was there, and he was handing out the exams, and he said, “Hey, you showed up.” [laugh] And I said, “Yeah, I’ve got to try.” He said, “Good attitude.” So I took the exam. I thought I did very well. I come out with the solution sheet. I see all the mistakes I made, and I’m panicking. I’ve no idea now if I aced at the level that I needed to.

So then all my family is flying in, and I’m running up to the fourth floor of LeConte Hall which is where physics is taught. And I’m going up to Dr. Woll’s, Professor Woll’s office where he has posted the grades and student numbers. And I run up there, and I cover the student numbers, and I look for Fs. And I find an F, and I look at the student number, it’s not me. And I find another F, and I look, and it’s not me. And I say, “OK, here, stop.” So I look at the student numbers, find mine, look at the grade, it was a C-. Oh, my god, thank god. And then I—he even drew the curve in the class, and I was the lowest C- in the class. I was exactly halfway between the next lowest C- and the highest F. And so he had made a decision. He could’ve failed me. He had made a decision to pass me, based on me coming to him, appeal, whatever—who knows?

Thank god, I barely scraped my way out of Berkeley. Years later, I’m a postdoc. I’m visiting Berkeley to give a talk. I said, “I got to talk to Dr. Woll. So I go find him. He’s in the hallway. I say, “Hey, I’m sure you don’t remember me, but I barely passed your class some years ago. I just want to thank you.” He said, “Yeah, I do think I remember you. What are you doing now?” I said, “I’m a postdoc at the University of Chicago in particle physics.” He said, “Oh, my god.” [laugh]

Zierler:

[laugh]

Kaplan:

He was in total shock. [laugh]

Zierler:

[laugh]

Kaplan:

Hilarious. What did I get out of Berkeley? I don’t know. I mean, I did poorly in the classes, but I did enjoy the quantum mechanics class taught by Zumino. I did like the E&M course.

There was a lab course, which people who have become theorists always tell horror stories about how horrible the lab course was. But there was this experiment where you reproduce what’s called the Mössbauer effect. And it worked. I did it. It worked. And I thought, “This is cool.” There was something very cool about it that you could measure these tiny, narrow frequency bands by just putting these two radioactive substances near each other, and kind of jiggling them a little bit. You know, the data plot came out the way it was supposed to. You run it, you run the data through the oscilloscope, you look, and there was this plot, and there were these absorption peaks. And so I had moments, you know, where we did some things. And I did the particle physics lab where we looked through data, old data on film, you know, to try to find particle tracks, and discover the pion, the kaons. There were things happening there that I liked.

I was flunking out, I was, you know, interested in saving the environment, and I was going to Grateful Dead concerts. I didn’t—I wasn’t doing drugs the way I did in the early days going to Grateful Dead concerts because then I couldn’t really concentrate in physics. And so that kind of subsided. Going to Grateful Dead concerts and taking LSD, things like that, that is something I did, and then I just—that kind of faded away because I couldn’t concentrate really. But it didn’t disappear. It kind of disappeared at the end when I graduated, and decided to do something different with my life. But I thought it was a waste of time to do those things because you couldn’t think clearly. At first, I thought I’d be very creative, write creative things. Yeah. But then after a while, it was like, no, it’s not really contributing.

So, yeah, Berkeley wa…for me, Berkeley was—now I look back, it’s very special. I had very special relationships with people. The people moved up with me from Chapman College, touring with the Grateful Dead. And my cousin Frank, who I lived with, was an important part of that. He’s the one who convinced me to transfer to Berkeley in the first place, so I can really credit him with that step. And, you know, the exposure to—if you look at my transcript, you might not think so. But the exposure to physics in some beautiful ways mattered. It really did matter, and it didn’t matter. The academics really just didn’t matter, like how I was doing and what it meant and whether I’d get in here, there or whatever. But I did like it.

Zierler:

What was it about Ann that clicked for you?

Kaplan:

[laugh] I don’t know. [laugh] Because, you know, I went and talked to her. She had a very well-defined topic idea. There’s this anomaly. We should study this, and maybe this—you know, if we introduce these new particles, we can solve the anomaly. I was like, “Oh, it’s a puzzle. Great. Let’s do it.” So it was just that. It was a doable problem.

Zierler:

Did you think of yourself more as a theorist than an experimentalist at that point? I mean, had you at least eliminated that –

Kaplan:

No, I literally did it by accident. I did not—if I hung out with the experimentalists, they would’ve said, “Oh, we’re doing such and such...” Actually, I did one summer just—you know, before I got in, I did work in a lab where I was building circuit boards or something for a neutrino-detection experiment (DUMAND), and it was boring. The problem was that I was given a task to do, but there was no connection with what was happening, why it was interesting. You know, I wasn’t part of a continuum. I think if I was, I could’ve done that.

Zierler:

Did you have any sense that, you know, in the early mid-’90s with the death of SSC that theoretical particle physics was, you know, perhaps an iffy—

Kaplan:

On its way out?

Zierler:

—any iffy—yeah, sort of an iffy proposition for beginning a career? Did you have any appreciation of that?

Kaplan:

Zero. I came in right at the time, and I was so unaware and disconnected from really what was happening. I was just, you know, self-centered, struggling, that sort of thing. Having my life, not trying to und…not—you know, just trying to get through graduate school.

Zierler:

What was Ann working on at that point?

Kaplan:

Well, Ann cared about the SSC. Ann was a theorist who really cared about details of experiments, and extracting information from experiments—to a scary degree—

Zierler:

[laugh]

Kaplan:

—because, you know, theorists couldn’t keep up with her. She would know exactly the details necessary to decide whether an experiment was interesting or not, and why, and what it could probe. And, oh, wait, what about this experiment over here?

So she—however—she, when she was at San Diego, she had written her first paper on what’s called gauge mediation of supersymmetry breaking. And at the time, supersymmetry was just—had just become the favored explanation of where the Higgs came from, and the solving the hierarchy problem, which was that the Higgs was unstable unless there was some bigger structure around it. And so people thought that this bigger structure could be supersymmetry because of some measurements a few years earlier—measurements of the weak mixing angle, which favored that the Standard Model had super-partners, and that it unified into a Grand Unified Theory at high energies—just of this one measurement. So it became—supersymmetry became like something, oh, …this could be the thing.

And so there were people who cared about the SSC and worked hardcore on SSC physics. And there were people who cared about the SSC but were doing, in a sense, bigger ideas. And Ann was a little bit more in the bigger ideas—solving those puzzles. And so she, along with Michael Dine, figured out how a complete theory of supersymmetry would work with the Standard Model. And it became—gauge mediation was the idea.

So supersymmetry is a part of the structure, but there has to be something that breaks the symmetry that allows for normal matter to look the way it does. And the question was, what broke this? And whatever broke the symmetry also gave the Higgs its mass. There were some subtleties. So she figured out the first model that actually did it, was complete, made predictions. The first model had some issues with it, and it was a bit baroque to solve those problems. And then when she got to Seattle, she figured out how to solve those problems. Then she wrote the next paper which became the paper on gauge mediation.

Zierler:

Was she involved in string theory at all?

Kaplan:

[laugh] No. She was extremely dismissive of string theory, and thought it was—you know, there was—my impression from her and from other people of that generation that weren’t doing string theory was that the string theorists were colluding in a sense, or were dismissing anything but string theory, and deciding that if you did string theory then you’re much smarter than the people who are not doing string theory. There was some unhappiness in the theoretical field. And the cancellation of the SSC probably added to that tension between the two.

But I don’t think she came of it from taking a side. I think she looked at the situation and said, “String theory is total bullshit.” In the mid-’80s, there were some realizations—there were some consistency checks that kind of worked in string theory, and people got super excited. Oh, my god, string—yeah, it could be the, you know, underlying thing to particle physics. But that was it.

The successes after that were few and far between. But there was an obsessive—like we’re studying the theory of quantum gravity. And it was deridingly called the theory of everything. And then they took that on, you know. We’re studying the theory of everything. And then the young people who want to do the greatest stuff would go to string theory. And there was a concern and some upset by the people not doing string theory that they’re absorbing a lot of people to do this crap, which is not very physics like. “It’s I believe the theory, and so I’m going to study all aspects of it, and maybe one day we’ll connect it with the physical world.” As opposed to I believe in the phenomenon, and I’m trying to explain that and more, and so I’m going to try out different theories and see what they’re consequences are.

And now I look back, and it’s obvious that string theory was bullshit in the sense of there were so many people working on it, and they were not manifesting any real progress externally. It was all internal consistency checks and things like that. And so at the time, you know, whenever it came up—and it didn’t come up much because there were no string theorists in Seattle—she was just very dismissive, like, you know, “What are those people doing? I don’t know what they’re doing.” [laugh]

Zierler:

Did you sort of adopt that mantle yourself?

Kaplan:

No. I thought, well, look, you know, maybe—you know, I think all directions should be explored, and even people doing crazy things—you know. Everything should be explored. Anything people think is interesting should be explored. So I didn’t.

And even I got a postdoc at the University of Chicago—half Chicago, half Argonne National Lab—and Chicago is dominated by string theorists. There was a guy named Jeff Harvey there, Emil Martinec, David Kutasov, just—and tons of postdocs, and Savdeep Sethi. And then they had a guy named Carlos Wagner, who was a particle phenomenologist, which is what I was calling myself then, who was half with Argonne.

And then there was Sean Carroll, who they had just hired, and who was doing cosmology type stuff. So I talked to Sean a lot. I was half and half, so half the time I was Chicago, I went to lunch with the group. [laugh] And they had no respect whatsoever for particle phenomenology. They were like, “What do you people do? Who cares?” And there was even [laugh]—

Zierler:

[laugh]

Kaplan:

[laugh] There’s a semi-famous paper in model-building in my field, particle physics. The semi-famous paper was written by Lisa Randall and Raman Sundrum, and so it’s just called Randall-Sundrum. And there was some geometric, extra dimension that could solve the problem with the Higgs without supersymmetry. And it was kind of—you know, it had problems but the picture was kind of cool.

And then later that year, Ed Witten explained what it is to show that it’s—it had a duality relationship to a lower dimensional theory, as described by Juan Maldacena. And so that connection was made, and that was interesting. Fine. I remember being at lunch, and this was maybe a year after this paper had come out, or something like that, or six months, and being at lunch. It’s clearly a famous paper at the time. It’s super hot. People are excited about it. And David Kutasov was saying how the stock market tracks the health of string theory and that—

Zierler:

[laugh]

Kaplan:

—the reason it had that mini crash the last year was because of Randall-Sundrum [laugh]—

Zierler:

[laugh]

Kaplan:

—because of this stupid paper. And Jeff Harvey was like, “What? What was so bad about”—Kutasov said, “It was not even the most interesting paper to come out that day.”

Zierler:

[laugh]

Kaplan:

And Jeff Harvey, who also has no respect for people who do actual physics, said, “Well, you know, probably the mo…probably the best that day.” He was trying to [laugh]—and I’m watching this like who are these people? What—I couldn’t grasp…I was trying to understand what the vitriol was. I didn’t understand it. I didn’t really understand it on Ann’s side either, and I really didn’t understand it with this group, other than to think they’re doing very hard math. I look at what they do, it looks hard, so maybe they’re smarter than me. They’re probably smarter than me.

And then the second year of my postdoc, Ed Witten had—was going around giving talks, saying the second string revolution is over. It’s because people had been super excited about Juan Maldacena’s conjecture there’s a duality between four-dimensional theories without gravity, and five- or 10-dimensional theories with gravity, and that duality tells us something about quantum gravity, and we’re going to learn everything. It was a cartoon picture.

They started on that road, and three years later realized that it’s very hard, and they’re not going to solve anything. And so Ed Witten was like that. He’s like, “Yeah, it’s not going to solve anything.” And then the string theorists got all depressed. They’re like, “I don’t know what to do.” And then there was an anomaly in the measurement of the anomalous magnetic moment of the muon. And so everybody at lunch was asking me about that, and what could it be, and could it be supersymmetry, or could it be this or that? [laugh] And that’s when I got it that there’s something pathetic about that world, that they’re driven by leaders. If Ed writes a paper, everybody writes another paper to cite it. And there’s—so there’s something wrong there.

And then I applied for postdocs, a second postdoc. And I had this rule for myself because—I’m kind of going out of order. But, you know, when I survived graduate school, and found my own, it came at a moment when Ann had given me another project. Hopefully I’ll actually accomplish something with this project.

Zierler:

Was that what your dissertation was?

Kaplan:

Yeah. She gave me a project. It was model-building in the sense of do something beyond the Standard Model. Can you explain both quark masses and the source of supersymmetry breaking? OK, da, da, da, da, I did. I snapped it together. The idea was suggested by somebody else, but I figured it out. I wrote to her “Look, here’s how it works. It predicts this, da, da, da.” And Ann wrote me an email that said, “You’re a model builder!” And that—finally I made her happy. You know, finally I’m doing something good, and it was a model-building. I said, “OK, I guess I’m a model-builder.”

And so that’s what I became famous for in the early days, which was building simple, elegant models that solved a bunch of problems beyond the Standard Model. And so I got to Chicago. I didn’t have a lot of postdoc choices because I didn’t write a lot of papers. I wasn’t a very accomplished graduate student. But somebody at Argonne saw this thing that Ann had written, which is that I had an idea, a little idea on my own, wrote it up in three weeks, and then discovered it had been done two years earlier, and was devastated. So she wrote that in a letter. Carlos Wagner at Argonne and was half-time in Chicago said, “That guy’s good. Let’s get him.”

And I went, and he had this—created this special joint position with the University of Chicago. So I never deserved to be at the University of Chicago because that’s a fancy place. They get fancy postdocs and—but I was half-time there because of this little position that was created. It was an accident. Another accident that I must say is Ann’s husband as you know is David B. Kaplan.

Zierler:

Right.

Kaplan:

And so when I was in the department, you know, I wrote my first paper, put it on the archive. I got an email from one of David’s long-time collaborators, Tom Banks, and I had specifically put in the paper not David Kaplan, but D. Elazzar Kaplan. That’s what Ann suggested so that it wouldn’t be mixed up, because I’m at the University of Washington, you know. [laugh] It’ll be very confusing. So I wrote D. Elazzar Kaplan, submitted the paper. But when you submit the paper on the email line, it does fill out your full name. Tom Banks emails me and said, “What’s this Elazzar crap?”

Zierler:

[laugh]

Kaplan:

“Are you going back to your Jewish roots?”

Zierler:

[laugh]

Kaplan:

“First, you do nuclear physics, and now this.” [laugh]

Zierler:

[laugh]

Kaplan:

[laugh] So I wrote an email. I said, “Well, actually, my name’s David E. I’m a different David Kaplan,” you know, blah, blah, blah. And he was very embarrassed. A similar thing happened when I went to my first real conference. I’d written this paper, this model of supersymmetry, and I went to the supersymmetry conference at Oxford. David Kaplan talk about supersymmetry. The room was totally packed. [laugh] And I was just a graduate student, you know, made a crappy model. So I went, totally packed, gave a talk. Lisa Randall came up to me, and she said, “Well, you know, I thought it was going to be the other guy. But, yeah, your talk was pretty good.” [laugh]

Zierler:

[laugh]

Kaplan:

So [laugh] there were lucky moments. And the other lucky moment was this Argonne-Chicago thing, part because I got to work with a guy named Hsin-Chia Cheng, who was a real postdoc at Chicago. He was a Berkeley grad student. He was doing his postdoc at Chicago— like the Miller Fellow or something like that, or whatever they called it at Chicago.

Anyway, fancy postdoc, great guy, spoke softly, had an accent—he was Taiwanese—and maybe a speech impediment, and so most people did not understand what he was saying. And I somehow could lock into his speech, and understood everything he was saying. And we got along great. I think of him very fondly. He’s a professor at UC Davis now. So I had the run of him. You know, we got to interact a lot, and I just learned a ton from him. And so I was very lucky in those times.

And then what finally happened was a guy named Martin Schmaltz, who was David B. Kaplan’s graduate student, who was four years ahead of me, but when they moved to Seattle, he had come visited and we had met—interacted a few days. But I was intimidated by him, and he thought I was an idiot. But he came to Fermilab on an exchange program from SLAC Stanford, and we interacted. And we had kind of the same idea for something. And we decided to collaborate on the idea, and this was an idea that had started with—that Ann and I saw at a talk, and we both realized something. And then I wanted to work. I said, “We’re going to have to write that paper.” She said, “Yeah, yeah.” And so then I—and then the speaker was in on it too.

So then I went to Chicago. Nothing was happening. Nothing was happening. We have to write that paper. And then I discovered Martin Schmaltz has the same idea. And so then I think, well, I can’t write this paper alone. I wanted—maybe I can collaborate with Martin. And I emailed one of the other collaborators and said, “Look, are we doing this paper or not? What’s happening?” And I don’t get an email for days, and that’s an eternity. And now I’m in a total panic. So then I talk to Martin. I said, “Look, I’m working on the same thing. You want to collaborate?” And we end up collaborating on a paper.

And then finally Chacko, one of the other guys and the original speaker in the old paper, he said, “Yeah, yeah, we are interested. We are interested.” And I said, “Well, now I’m collaborating with Martin Schmaltz.” And they—so we all agreed: “So you guys write a paper. We’ll write a paper. We’ll just do it at the same time and, you know, we’ll try to come out at the same time,” which is what happened. We came out at the same time. So that was lucky too that—I don’t know, you know, if I was somewhere else, I would’ve wanted to work on that paper but we might not have beat Martin to it. On the other hand, maybe I was an integral part of that paper, and the reason it came out in the speed it did was because I was part of it. Who knows? But the relationship with Martin was very important to me too. So I feel very lucky.

There have—I’ve had such negative opinions of myself. Even then, I still didn’t like I belonged in this field. Why am I not saving the world? Everybody around me is better at physics than I am. I will never make it. And I had rules for myself that if I get out of graduate school and don’t have a decent postdoc, if the postdoc I get is kind of lame, I’m dropping out. And I had the same rule for myself at Chicago and Argonne. If I don’t get a better postdoc than I have, I’m dropping out. And all the time, I would have these fits of questioning as to whether I should be in physics.

And I remember in graduate school writing lists of other careers I could do, and thinking through all of them. And in my first postdoc, I would write lists of things I can do, and try to figure out if I should be in the field or not. And I even went on an interview with McKinsey, who had recruited me, the consulting group. So I did my interview. I did a first interview there. It went fine. I did a second interview, and the test question was about the fifth-largest bank in the world. And then I felt this sickness in my stomach like I don’t want to solve problems for the fifth-largest bank in the world. People—[laugh] I can’t do that.

So I failed that interview and could not figure out what else to do with myself. And then I got—I had given a talk at Berkeley and at SLAC, and I had applied for postdocs, and I got a postdoc at SLAC—SLAC, Stanford. And I didn’t at Berkeley, although I was high on the list, but they gave it to someone else. So I thought, well, SLAC’s good. I’ll go there. And Fermilab had offered me a postdoc. They wanted to keep me in the area because at that point, Martin had actually gotten a permanent position at Fermilab. So I’d considered it, but I thought I should go to SLAC.

Zierler:

Did you think that you needed a second postdoc to really sort of test yourself and cement your status in the field before pursuing academic opportunities?

Kaplan:

At that time, there were so few jobs, and the jobs mostly were going to string theorists, so it was very hard to get a faculty job. So I just didn’t think I’d get one. I wasn’t even convinced in myself … I’ve got to get better at this, I thought. It was probably more that I won’t get one. And it’s what people did at that time anyway. People did two postdocs, unless they hit a jackpot on one of their papers. So it never occurred to me that I would be even, you know, able to get a faculty job. But it was clear then that I was kind of getting famous. I got the SLAC job, I was surprised to get the SLAC job, and then my papers were kind of hot.

Zierler:

What was the more important factor at that point? Was it Chicago or was it Argonne?

Kaplan:

Argonne, by far. Chicago was a joke in the sense that it was dominated by string theorists, who were depressed by my second year. I liked going to Chicago because we lived in Chicago, and the commute was short, and I liked Hsin-Chia.

And I talked to Sean Carroll quite a bit, who was faculty there. He was writing a textbook on general relativity, and said, “Probably this will cost me tenure.” And it did. [laugh] He’s a soft-money position at Caltech now. I liked Sean. And actually from Sean, I got something around the—he had a blog, one of the first science blogs, where he would talk about the field and what’s happening, and he had his own little server. You know, it was early days of this stuff. And so—and he was a beautiful expositor. He really could write in ways that physicists usually can’t. And so I appreciated that.

And we went to lunch regularly and, you know, I learned from him—that part; not physics. His physics was weird. But at Argonne, Carlos Wagner was great. It was a nice cadre of postdocs doing a very broad range of different things, and I was enthusiastic, and I could take over. And Carlos and I thought, “Let’s run some workshops here.” And I was big in organizing the workshops and who we should invite. And I felt, my god, it’s so easy to invite people. It was like who are the coolest people I want to invite? I want to invite that guy there. And most of them just come. My god, this is so easy. So it really—I really understood I could just enter the field, and take over, and decide what should be interesting, and what’s not. And so it influenced me, part where it gave me the space to work.

I met a guy named Tim Tait, who I really like, and we worked well together, and we wrote a couple of papers together. But I was clearly coming into my own. And by the time I got to my postdoc at SLAC, it looked like I had a shot at a faculty job. I didn’t really want a faculty job because I knew it was a lot of work, and postdocs are so much fun.

Zierler:

[laugh]

Kaplan:

But I knew I could probably get one. I had a good chance of getting one.

Zierler:

Also, you have to grow up at some point. You can’t be a perpetual postdoc.

Kaplan:

Right. I was married. We had our first kid right before I—[laugh] Ann Nelson said to me, “Do not have children unless you have them when you’re a graduate student, you know, early in your career, or you have them after you have tenure. Do not have them in between.”

Zierler:

[laugh]

Kaplan:

And a month before my postdoc was supposed to start, Liam was born. And then a few months before SLAC postdoc started, I discovered that my wife was pregnant, and Eva was born in November of my second postdoc, at the beginning. Disaster.

Zierler:

[laugh]

Kaplan:

But a very productive time regardless. Difficult time. And I worked with Savas Dimopoulos. I met Savas Dimopoulos, and I understood that I could be a physicist. It was really only then that I could picture myself as a physicist.

Zierler:

Wow. This is late in the game to have this discovery.

Kaplan:

I know, I know. Look, I was still applying to other jobs…I was still trying to figure out what to do with my life.

Zierler:

You realize of course that most people, their stories are “I knew I wanted to be a physicist when I was”—

Kaplan:

Thirteen years old.

Zierler:

Yeah, exactly.

Kaplan:

Yes, 13 years old seems to be the time. That was the time Savas knew—maybe 12. That was the time Nima Arkani-Hamed knew. That was the time David B. Kaplan knew.

Zierler:

Right.

Kaplan:

I remember David and I—I was visiting Seattle many, many years later, and he was saying, “You know, you’re interesting because this is not what you wanted to do. You know, I’m boring. I wanted to be a physicist from early age.” I think he actually wanted to be since he was 6. His uncle was a nuclear physicist or something like that, and so he loved physics from—he doesn’t remember a time he didn’t love it. He said, “You’re interesting because this wasn’t part of your—you know—you don’t have that standard background.” Yes, it was that. I met Savas, and within a few days, I was like, that guy is a physicist? This guy is a total goofball.

Zierler:

[laugh]

Kaplan:

He spends half of our time just being ridiculous, jokes, very silly, making fun of everybody in the field. And then the other half of the time, it’s like ‘that’s not interesting. That’s not interesting. That’s not interesting. Oh, wait, is that interesting?’ Yep, yep. Lightning-focused. He’s Greek, Mediterranean. My dad—there was some similarities and demeanor with my dad, like a very happy, gentle version of my dad. So I think there was something there too. That’s what it was. I pictured it as like I could be like that, you know.

Zierler:

And what was he working on at that time?

Kaplan:

I don’t know.

Zierler:

He was working on something presumably.

Kaplan:

He was, but it’s funny because he had gone through a little depression at the late—in the late ’80s. String theory became big. He thought it was stupid. He didn’t really know what to work on. Eventually the SSC was canceled. You know, he’d worked in the early ’90s on some little things, but then the SSC was canceled.

He was sort of up and down. And then I think maybe his mom died right before I got there, or something like that. It was—there was—he was sort of at a low period. He had just—no, I know what he was working on. He had just had Nima Arkani-Hamed there as a postdoc. And Nima had left, and they had done large extra dimensions. They had posited that there are additional dimensions to space, which could be as large as a millimeter, and that normal particles don’t travel in those dimensions, which is why they’re hard to detect. And that was huge, and that was its own big thing. But he surprisingly mines a subject, and then moves on.

So he was looking—so what else is interesting? And so I told him the little models I was working on. “Hey, man,” he said, “yeah, yeah, that’s interesting, yeah. But this is what I’m interested in.” And his basic—he said, “All that matters is the solution of the cosmological constant problem, the solution to the hierarchy problem, which is the Higgs mass, the explanation for why there’s matter and not antimatter, and what is dark matter?” Really, what is the contents of the universe, and what are the biggest questions in the underlying laws? That’s all he cared about. If we’re working on something which is a little thing over here, it’s like, “Yeah, ah, but this is what I think is interesting.” And he was very hard in the sense of—he never came across that way. It was more like you’re in a Greek market haggling with somebody.

Zierler:

[laugh]

Kaplan:

But you could tell—you know—like he would end the conversation, and move onto something else, just without batting an eye, like we’re done with that. He wouldn’t say anything. He would just say, “Mm, OK, well, let’s talk. Let’s figure out how to da, da, da, da.”

So he kept us focused, and we—I had these crazy sort of theories and things. And we sort of culled it down, and then made a little discovery that in the large extra dimensions world, you could also have unification of a kind—grand unification of a kind. And that wasn’t understood. That was the big drawback for Savas, because Savas was the one who wrote down the first explicit descriptions of supersymmetry in our world, and showed how it unified the forces back in 1981. And then in 1990 or so, when they discovered that the weak mixing angle was the right value to confirm that supersymmetry could be unifying the forces at high energies, and that was big. That was an almost discovery. [laugh]

In the salary categories, Savas was paid as near-Nobel prize, you know, coming soon Nobel Prize. [laugh] That was—that’s what he had negotiated. So that was his one problem with the large extra dimensions, and so I had a solution to that—a very cute, simple solution to that. And I wanted to do all kinds of other things with that, and he wasn’t interested in those things. And then those other things I wanted to do, we got scooped. I got scooped because he didn’t care for these other models, little Higgs models they’re called, so. But it didn’t matter. I mean, I—what was most important about that was that attitude. What is the most important thing you could—is that really important? Every paper, he would say—he had all these aphorisms. He had all these sayings or things that he repeated many, many times—“Every paper takes the same amount of time.”

Zierler:

It’s also an interesting blend of, you know, a very serious look at the biggest questions, and also being very, lighthearted, if you will, in his personal affect.

Kaplan:

We were laughing all the time. It was just—or if you weren’t in the room, you could hear the laughing on the floor. There was always laughing coming from that office. He was just constantly making fun of people. He was constantly just a total goofball.

That is now in retrospective, it’s obviously necessarily because you cannot think about physics constantly. You need breaks. And the bad breaks are you check your email or you do anything like that or associated with that. That is bad. A good break is making fun of people in the field because once in a while, you make fun of—and you’re like, “Oh, wait, actually, Raman’s, you know, short distance gravity conjectures. Do you think there’s something there?” It makes—now it makes sense.

At the time, I thought I couldn’t believe [laugh] we spend more than half of our time just being stupid. But, yes, it was a unique environment. And some people really didn’t like it with him, or just did not know how to connect with him, and some people connected instantly. And I connected instantly with him. And that was like I can be like that and do physics.

Zierler:

Yeah. So how did that influence the kind of work you wanted to do yourself?

Kaplan:

When I was a graduate student, and I was actually surviving at—I told Ann, “I want to do something big in a little field, or little in a big field.” And I mean—by field, I mean like importance. Like take an important part and problem, and add a little—add my little two cents to it. Or take a moderately important problem, and solve it, you know, do something big. Basically saying there was no way I could be really big because I was obviously substandard among the best physicists. I didn’t think that highly of myself. Here is this goofball who was only asking the big questions, and did not have the patience for things that are just for the sake of calculating or showing your, you know, technical muster. But you actually just want to solve something, and you want it to be testable.

And so one of the important things was I really stopped being interested in theories that didn’t really have important physical consequences. You know, they’re interesting. Model-building’s fine. But it’s speculative, and the probability that your model is correct is a set of measure zero. That a mechanism in your model is correct, there’s a better chance. But then you want to know what are the broad experimental consequences of it. If it depends highly on where you move this parameter and that parameter, it’s not clear you’re saying that much. So I don’t want to work too hard on that. And not because—I still believed at the time, and I still was— not because I thought badly of string theorists, although I did think badly [laugh] of the string theorists in Chicago. They seemed just depressed and useless. But I did—I still thought, no, you know—even as much as Savas hated that world, I still thought, no, everyone should be working on, you know, whatever they think is interesting, even if it doesn’t appear to have any connection with da, da, da. But I—

Zierler:

Is that, David, because, you know, a lot of people just lost patience, right? Like at some point, the string theorists need to actually prove something.

Kaplan:

[laugh]

Zierler:

Was your approach that there needs to be more patience, and that there might be a breakthrough that, you know, justifies all of this work up until that point?

Kaplan:

Yeah, I mean, I couldn’t ever justify volume, like how much work is being—how many people? I didn’t—you know, there is a judgment call there that’s asking like is it worth $10 billion to build a collider? Or, you know, I don’t know. I didn’t know how to answer those questions, and I didn’t even care.

But to attack the act itself of going in that direction I thought was just wrong because people doing it, I thought they were just like me, that they’re really trying to figure something out, even though there were signs that it was not so good, that people are just following Ed Witten, whatever he says, or Juan Maldacena, whatever he says, and just writing follow-up paper, blah, blah, blah. There was a lot of that. There was a lot of crap in my part of the field too. So I was like, yeah, there’s a lot of crap—but not the pursuit. Don’t complain about the pursuit because the pursuit is—you know—it’s a crazy direction. It doesn’t look like a crazy direction because it dominates the field. But it is a crazy direction.

So putting aside the sociology of it, people should be doing crazy things. That’s the whole point of this. We’re not going to discover something by doing something we did every other time. It’s the discovery is going to look totally different this time. So I don’t understand cutting that off, no matter what. You know, I understand voting with your feet, like that’s not interesting. I don’t—I’m betting against that. I’m not going to do it. Fine.

But not just saying that they’re corrupt, it’s bullshit, or whatever. I didn’t understand it, and part of it was I didn’t understand what they were. I didn’t study it. I didn’t dive in deep to make that decision myself. I just thought everybody’s trying to figure something out so it’s OK. And that they dominate the market, and how many jobs or whatever, OK, fine, I don’t know. I’m just lucky to be here. I—you know, it’s like playing baseball professionally, and complaining that in AAA, you know, the health benefits are not good enough. OK. You know, I agree.

I am against people taking advantage of other people, and things like that. But there’s an aspect to it which is I get to do this. I can survive. I can get—you know—I can buy enough food, and survive as a person, and I get to do this where people don’t know if it’s going to have benefits in the long run. I think humanity should be doing it, but I feel very lucky to do it. And so how everybody else decided what to do with themselves, or whether we get more jobs or less jobs, I didn’t know how to make out those priorities for the field. [laugh] I’m there—we’re doing—I’m doing the job [laugh], it’s good, you know. I think my student deserves that position, not that other student. OK. It’s the nature of the game.

This is su…we don’t know if we’re on a good track or a bad track, so I don’t—I never really understood that attack. But it was there, and it was—you know—it was deep. It was deep for Savas. He was very angry about it. And Ann really did think it was crap, so, you know. But I never—back then, I’d never even thought to come to that conclusion. And I still thought that they were probably smarter than me, you know. They could do these much more technical things than I could.

Zierler:

How did the opportunity at Hopkins come together for you?

Kaplan:

Well, my wife at the time was at wit’s end, said, “Can’t keep moving around like this. If you can get a permanent job, get a permanent job.” So I’d only been at SLAC for a few months. I’m having an amazing time with Savas. I don’t really want to apply for faculty jobs.

Zierler:

And is SLAC and Savas like totally—as far as your experience was concerned, was your time at SLAC all about Savas, or was there a larger framework that you were operating in?

Kaplan:

Savas, yeah. No, once I met him, and I understood what that was all about, that’s why I’m there—nothing else to do. And once he had me, I mean, he didn’t have another postdoc that year. He—they had no money. His group didn’t—the postdocs at Stanford were all string theorists that year. I was the postdoc at SLAC, and the rest of the postdocs at SLAC were doing much more technical—it’s called B physics, that phenomenology of certain colliders and things like that.

So it was just me, and a guy named Scott Thomas, who spent time at SLAC regularly. He was a—yeah—he was a professor on campus, but he spent time in SLAC quite a bit, so we interacted a number of times. And then he said, “You should come meet Savas.” So I went, met Savas, sat on his couch, talked physics. I never went back to SLAC—once in a while, once in a while.

I had a [laugh]—there were these three German postdocs who were at SLAC with varying—they all did B physics, they were all German, and they all could play a musical instrument. I could play a little bit of electric bass. And so the keyboardist, she actually had had a professional band in Germany for six years before she went back to physics. And so she decided to create a band, and I was the lead singer since I could barely play an instrument. [laugh]

Zierler:

[laugh]

Kaplan:

So my time at SLAC was interacting with those guys.

Zierler:

[laugh]

Kaplan:

But that was it. And I would go to give talks, or if there was an interesting talk at SLAC, I would go to SLAC for the talks. I loved talks at SLAC because they were very jam-packed, they would last for two and a half hours, but the talk—everybody is engaged in the talk. Everybody’s asking questions. People are getting up, changing things on the board, debating the—blah. It was an event. I enjoyed that a lot.

The talks at Stanford were a little bit more staid. There were a lot of string theorists at Stanford. I didn’t understand any of those talks. Or sometimes when the talks were not in strings, Lenny Susskind would yell at the speaker that this is bullshit or whatever, da, da, da, da—you know, abusive at some level. So Stanford was weird in that way.

SLAC was great for the talks, but 95% was Savas, you know. And then when I was—on the weekends, we got excited about the projects. So the weekends, I’d be out with the family, he’d call me, you know. [laugh] So I’d have to do—we’re doing physics, so then my wife at the time would complain about him. And then if I’m at work, and then my wife calls in the afternoon, then Savas would complain about her. And so there was some tension there. And so I decided I’d better apply for a faculty position somewhere. If I can get a good one, then great, then I’ll take it, and we can settle down.

Zierler:

And you did.

Kaplan:

I did. I applied, I got an offer from—first offer was from the University of Hawaii, which I thought, “Well, you know, Hawaii, it’s pretty good.” [laugh] And all these people were coming to me, Nima Arkani-Hamed and—which sort of—you know, my generation, they’re all coming to me like, “Oh, take the job in Hawaii. Look, we promise to come visit. Please take it, take it.” [laugh] But then I got Hopkins and University of Maryland, and so ultimately it just—it was one of those two.

Zierler:

Baltimore beats Hawaii, huh?

Kaplan:

[laugh] Yeah, apparently.

Zierler:

[laugh]

Kaplan:

Yeah, we—my wife and I decided to take it, and…

Zierler:

I mean, it’s a much more established program. I assume that was part of it.

Kaplan:

It’s an establi…no, and Raman—so, yeah, the people at both places were great. It was serious. I would do real physics. Hawaii is a risk, of course. It’d be isolated, so. So the thing that got me at Hopkins was that everybody got along, was that there was mutual respect of all fields.

Zierler:

And was that implicit in the fact that the astronomy and physics programs were combined?

Kaplan:

It didn’t have to be. You know, there could’ve been tension there. But it was more—it was just more about the fact that the place was small, and wanted to be great, and had a chance of being great, and the only way to be great was that it was strong in every field. And there was a core—at least at the time when I’m applying—there was a core belief among them—three fields, astronomy, condensed matter, and particle physics. There was a belief that the other two fields were good.

And whatever they wanted to do, whatever they thought they could do to improve themselves, we’ll support if it means, well, they’ll hire before we do. It’s OK, they need it. That—the missing crap, which takes a lot of energy and time, was very important. It means I can go into a place, do my thing, everybody’s happy. Everybody’s supportive. Everybody wants everybody else to succeed. That’s great. And because that’s how I felt, I was interested in everything. I thought people are doing things. I don’t know how to do them. It’s awesome.

I love to talk to people. I love to hear what people worked on. I’m—I think of myself and I think I was a very encouraging person about other people’s work. I think Nima loved to talk to me, not because I had a lot to contribute to his work often but because I was so enthusiastic, because I got what was interesting about it. I understood why he—what the motivation was. And I really liked all of that for—and so I liked—that should be the attitude, I thought. So I came to a place where everybody feels that way. Everything everybody is doing is interesting. Everybody’s pursuing something interesting, which is why it took me so long to turn on string theory because I just fundamentally thought people, they’re doing something interesting.

Zierler:

In what ways did the move to Hopkins provide you with new opportunities for your own research?

Kaplan:

It was hard. Becoming a junior professor is a bit painful. You—in that first year, you’re just on the faculty, and so you’re interacting with the faculty the way they interact with each other, which means there are all these crappy obligations and then these expectations, and you sort of forget. So the first year is like, oh, shit, sorry, oh. I’m already a bit, you know, irresponsible when it comes to obligations and things.

And so there was just a lot to do, and I felt bad about things, and—on the other hand, Raman was a fantastic person to have around—just a brilliant field theorist. I was surrounded by people smarter than me. And Jon Bagger, who’s another brilliant guy, he was not working a lot but he thought a lot about physics. The team was very good and very encouraging. It was just a somewhat unproductive beginning. On the other hand, I had all this start-up money, and I could just invite people. And I loved—like I learned from Argonne—you just create things out of nowhere. You just create events. And so I just would invite collections of people to come visit and do physics. And that kept me excited and engaged.

You know, it’s interesting because when you’re a postdoc, you’re at a good place. You’re coupled to the whole world. And when you’re faculty, you are siloed. It is much more of a silo. You have to make much more of an effort to connect with people. And I could tell. I came in. I was the young person. I knew what was going on. And the—and Raman’s like, “Who should we invite? Who should be—you know?” And I was, “Oh, my god, you should invite this guy and this guy, and that guy’s doing this other thing, and these people are doing the other with them.” And so I had loads of people in. “Get these people to give a colloquium. This thing is super interesting over here.”

As a postdoc, you’re seeing lots of people come through. You’re organizing seminars. You’re traveling a ton. You don’t teach. And so you are the sort of underbelly of what the up-and-coming physics ideas, even if the big idea comes from a senior person. Like the postdocs are like, “Oh, what’s that? What’s going on over there?” Change, drop this, do this other thing. And so when you get in, you have that. And when I—you know, then eventually, you become more and more disconnected. But you feel it at first that you’re disconnected from everybody.

And so my—the thing I did was to just bring as many people in as possible. And I was—that’s something Martin Schmaltz had told me early on, or early on as a professor. He said, “You know what you do that’s so good? You just talk to everybody.” If I was ever confused about something, I would just email the person, whoever the expert was on that topic, and I’d just email them, and say, “Hey, I’m, you know, David Kaplan. I’m a blah, blah, blah, blah, blah. I’m working on this thing. You’ve written this paper. I don’t really understand this. Could you—is there a good reference? Could you explain this? Do you have time to talk?” I had no problem. Like I’m confused. Let me ask somebody. And that turns out to be a little bit rare. So that’s my [laugh] superpower. I decided I’m never going to stop feeling like an idiot, and so I’m going to just let everybody know I’m an idiot.

Zierler:

[laugh]

Kaplan:

[laugh] And that’s right. It’s the only way I’m going to possibly achieve anything here. So that’s what I did [laugh] is keep telling people that I’m an idiot, that’s all. And it’s funny.

Many years later, Raman, Jon Bagger, and I were talking. We’re talking about seminars or something or young people. I don’t remember what we were talking about. But the notion of when we had people come for seminars, and we would ask questions and things, I said, “Yeah, I always ask really stupid questions.” And both of them agreed, “No, we’re actually scared of you because”—you know, Jon said, “I feel completely stupid because you ask these important questions, and then you understand immediately the answer. And I don’t understand what the hell just happened, and I’m—so I’m afraid to ask questions.”

So I’ve been—whatever way I had been being, I was suppressing the other members of the group in terms of their—because I would ask questions. But I would answer people’s questions just off the cuff, you know, with just a quick and probably dismissive-sounding, like, “I don’t know, it’s just this.” So I was doing some disservice. So I learned something about myself which I didn’t know, which was that I was very intimidating. And I decided, OK, I need to be even stupider. I need to really bring down the level. You know, I need to just be completely stupid. But they said whenever I asked a question, I said, “I have a really stupid question,” everybody would freeze up. [laugh]

Zierler:

[laugh]

Kaplan:

So that was my—but that was my thing. And so there was—it felt—when I left high school, as high school was hard, I went to college, I said, “Oh, I can invent myself. I can create this persona.” And I borrowed from a persona of my friend at the time, who organized things, who took charge, who was bold, who had no problem saying things, but was easygoing at the same time, and everybody loved him. So I said, “Oh, I’m going to be that, my friend Matt, I’m going to be that when I get to college.” And people responded to it, and I thought, “Oh, well, this works.”

It’s the same in physics. Everybody feels like an idiot, and if you just go, and you’re like, “Eh, look everybody, come, oh, what you’re work…that’s awesome. That’s awesome,” you get a lot of friends, and you can collect[?] a whole bunch of people, excited and inspired, and learn a ton very quickly, very efficiently, instead of reading a whole bunch of terrible papers, you know, trying to extract something that people barely understood when they wrote it. That why I’d be organizing conferences all the time.

I would give talks, and I would say, “This is what people should be working on; none of this crap. This—everybody should work over here on this stuff because nobody has been analyzing the data correctly, and we’re missing every…everybody do this.” And that also turned out—got me into some trouble too because people were insulted or upset that I dismissed this whole other [laugh] side of the field, not—you know—not thinking about, oh, people are working on it. I really want to help everybody, and I would see this is actually a waste of time. It’s a holdover for last years of the same research. It’s not actually going to turn into anything. Everybody should do this stuff over here.

I think people in the field are afraid to look stupid and to be stupid, meaning work on things that they don’t understand anything about. And so they will follow on tracks longer than is needed, and longer than is productive. And you get comfortable that you’re good at something. And I never feel good at anything. And if I do get good at something, I don’t even let myself get good enough to be, you know, the prominent person on that topic.

I just want to do something else because I—you know, it’s more fun to start something than to wrap it all up with the bow, clean it all up. So I think, you know, you come to a place as a new junior faculty, and you’re the world’s expert on something new, different than what the other people are, and I feel emboldened by that, and I felt emboldened by the fact that I knew what the young people were doing, and I could bring them in. And then it became—you know—then we started losing people. People were being stolen away or became administrators, and then I decided we have to build the group. That’s more important. So then I just worked on trying to bring in professors, you know, great professors and things like that, so.

Zierler:

What are the areas where you’ve come closest to prominence, and then have, you know, [laugh] run in the other direction?

Kaplan:

[laugh] Any paper I’ve done—I mean, when I was young, I did supersymmetry breaking, and I did stick with that for a few years, you know. And then I was—that’s what I was good at. And then I got to Hopkins, and I’d say—well, I was still model-building because I was the prominent—one of the best model-builders. And I thought, “No, actually what’s important is that we’re going to discover something.

And if I just keep model-building, the chance that any of these will be discovered is very low. So I thought to go backwards ask—take an experiment, what could it see that we’re not looking for? And so I kind of flipped to that, a little bit inspired by Savas, who was doing that kind of thing. So I flipped from ‘model building’ to ‘phenomenology’. But it was everything. You know, I’d write—I wrote this paper on the little Higgs, you know, just some mediocre paper or something. But it was so hot at the time. I wrote this paper with Martin, and it was hot. And I said, “OK, that’s enough. That’s not interesting.”

I would—you know—even the relaxion. After the horror of making a movie, I took a sabbatical at Stanford in Berkeley, and I hung out with Savas’s students, who were geniuses, who are brilliant. And I don’t know why they wanted to interact with me all the time. He kept strongly encouraging me to come visit. So I visit regularly. I came for a sabbatical. We wrote down a theory: the relaxion is what I called it, and it was a totally different way of solving the hierarchy problem – the problem with the Higgs mass. No supersymmetry, nothing at a collider would be discovered. It was its own totally different world. And so what Savas would do is he would write a paper like that, and write 10 follow-up papers, all of everything you could do, right. So I wrote the one paper, and then, yeah, that’s enough. Let’s do something else. [laugh]

I have yet to write a follow-up paper to that paper. But it has plenty of citations. Savas’s attitude was you write 10 papers because then you would get all those citations 10 times. [laugh] The cottage industry is [laugh] the point. You know, ultimately, our field is really fickle and ridiculous because prominence comes from just stupid shit, which is just things are exciting and popular.

And lots of—we have this heat bath of people who can react and write hundreds of papers. “Oh, wait, we may have seen a signal at the LHC!”—250 papers overnight. Total waste of time, garbage, terrible, just people doing all kinds of crap. Same thing, you write a very cool new model to explain something, 250 citations. Everybody has to do the follow. It is important to follow up interesting ideas, but not with frivolous paper-writing. Yeah, you know, 2% of those are useful.

Zierler:

But do you need the 250 to get to the 2%? Is that really what the game is?

Kaplan:

No, of course not. No, people are wasting time. People are following directions that are not interesting. There is a dishonesty with oneself. You just—like, people are afraid to not write papers. I have a problem. I’m super lazy, so to get me to write a paper, the topic has to be so interesting, so important, or at least important to my collaborators who I care about and whose judgment I respect that we get it out—that I get it out. But people writing papers, I think they’re afraid that they better write a bunch of papers so that they’re, you know, getting grants, doing—I don’t know what they—see, I don’t know. I never consciously thought about doing physics, and then me succeeding in my career because of that, you know.

What I do think about when I write a paper, I’m imagining explaining it to people as I’m like—as I would in a talk. And it’s just automatic, not directed, but it’s just that’s what comes up in my mind. I’m thinking about the subject, and I’m thinking about it in front of, you know, 30 people, and I’m explaining why it’s interesting. And, like, yeah, but then, you know, as I’m explaining it out loud in my head, “Wait, there’s something wrong with that.” And that’s how I find the holes, or that’s how I—like, I’m realizing what is the aim here of this thing? And the topics that I’ll work on that I can’t do that, I just I don’t finish the paper because I don’t know what I would talk about if I wrote that paper, so.

But—so I don’t—and it’s part of probably why I didn’t understand—I didn’t think of myself as a physicist because there’s a lot of physicists working very hard on what? I don’t know what they’re working on. It’s not—you know, I used to just think I’m too stupid to understand what they’re working on. And finally reading some of those papers, they’re not what—it’s stupid. There’s a lot of stupid stuff in there. String theory really is just stupid. It’s unbelievably stupid. There’s so many people who are working on it that don’t actually know physics that they can’t even describe a physical characteristic of the thing they’re calculating. They’re missing the whole thing.

So I’ve decided there are two diseases in theoretical physics. One is the exact solution disease, which is people think they’re doing something important if they can exactly solve something; no matter that the thing that they’ve created has nothing to do with the physical reality, and you can’t even pretend that it is connected to a physical system. It’s a cartoon of a physical system. And so you work on it, but the reason you would work on a cartoon of a physical system is to give you a hint of how to solve the thing in the physical system. But string theory just never left this simplification; never left the spherical cow. They’re still working on the spherical cow. You know the spherical cow joke?

Zierler:

I don’t know this joke.

Kaplan:

Yeah, the important—yeah—the unfortunate thing about the spherical cow joke is that the name of the joke is the punchline.

Zierler:

Ah. [laugh]

Kaplan:

So but I’ll summarize the joke, which is that a farmer has a cow that he can’t—no milk is coming from the cow. He asked the local physicist. The local physicist takes weeks to figure it out. And the farmer’s like, “What’s going on?” And he says, “Well, look, I’ve almost solved the problem of the spherical cow.” Meaning you take a system, you just say, “Let me just assume perfect symmetry. Can I solve it in that case?” And if you solve it with perfect symmetry, maybe some aspect of the solution then is important to the actual physical system you care about. And string theorists have never left the spherical cow. It’s in exactly supersymmetric, N = 4, and there’s a sort of a fringe element of the supersymmet…or the string theory world, the fringe element that tried to think about, “Well, what if we tried to break supersymmetry, would we figure that out?”

But that—you know—little bits of that come out every 10 years. And then there’s 10 years in between of people just solving these systems that have nothing to do with the physical world, and will not—clearly—will not contribute to understanding, at their own admission, in most cases. So that’s when I realized string theory is like a video game. There are people just addicted to it. That’s all that’s happening. And it’s couched in the theory of everything and da, da, da, da.

So that’s all. I just kind of—I learned quite a bit about these things. And then I saw the people like Lenny Susskind, who was terrorizing people who work on regular physics, as just a plain asshole. That there are actual people who are deciding string theory’s important, wanting to do string theory, and they’re even protecting the field. And some of those people are talking about how entropy now of a black hole can be described as a geometric thing, an entanglement, and that Hawking’s paradox about evaporating black holes is really wormholes, virtual wormholes coming from the inside to the outside, and all kinds of language. And you could test information theory of black holes using atomic physics experiments. And it’s literally bullshit.

There are people—prominent people—in physics who say, “I’m applying for this money from the DOE, but I know it’s bullshit.” And then there are experimental atomic physicists who don’t know and are shocked to learn that “What? String theorists don’t have a Hamiltonian? They don’t actually have a [laugh] description? What am I testing?”

So I have converted a little bit to the opinions of my predecessors, only because I’ve actually done the work. I’ve actually tried to understand black holes of late, and I’ve gone back to those papers which are the breakthrough, celebrated, amazing papers about black holes, and there’s nothing in them. It’s really—it’s just a very simplistic picture where, look, if you take this hyper-simplistic picture, these numbers match these numbers, which means thinking about a black hole having entropy is correct, da, da, da, da, da.

No matter that the black hole they’re talking about is extremal. It doesn’t actually Hawking radiate. It’s a totally hyper-supersymmetric, multiple charges, free parameters. So now that I’ve finally dug into it, I realize that—not that all humanities fields are bad. But it’s much more like a humanities field where there are the prominent people in the field, and they decide what’s interesting. And that if you impress those people, you can get ahead. But that dictates then what research is done. And they’re not going to discover anything in that context. They’re not going to get anywhere. There’s not a lot of people doing—you know—thinking outside the box or just thinking diff…you know, doing different things, you know.

Zierler:

What is your response to a string theorist who would say, and I know this because one has said this to me, “Look, four people were doing this in 1968, 20 people were doing it in 1984, 1,000 people were doing it in 2000, and now there’s 6,000 people who are doing string theory all over the world. And that’s proof that there’s something here that’s worthwhile”? What is your response to that line of reasoning?

Kaplan:

[laugh] Take those numbers, continue the exponential, and apply it to Christianity—

Zierler:

[laugh]

Kaplan:

—and Islam and Judaism and Buddhism. Give me a fucking break. They’re describing a religion that can attract and addict people. That is exactly the kind of statement that shows it’s bullshit and non-scientific. They’ve proven it for me that they are not about discovering something. They’re about dominating the field for the purpose of what? That’s proof? Give me a break. Give me a fucking break. Slavery was very popular, and became widely used. Nazism. Come on. You can take extreme examples and show that that is so non-scientific and sick that the progress they have made is to get more people to work on something that isn’t producing anything. Oh, man, I wish you didn’t tell me that. [laugh]

Zierler:

[laugh] I didn’t tell you who said it though.

Kaplan:

No, no, that’s fine. I don’t care anyway. I mean, I can imagine all the people that could’ve said it. It’s just terrible.

Zierler:

But to go back—

Kaplan:

It’s terrible, yes. [laugh]

Zierler:

To go back to the more laid-back sentiments you had earlier in your career [laugh]—

Kaplan:

Yes, yes.

Zierler:

—where, you know, your approach was, “Well, you know, there’s room for everybody, and let’s see what happens here.”

Kaplan:

Absolutely.

Zierler:

Right?

Kaplan:

I have that too.

Zierler:

Do you—but are there—but when you talk about DOE grants, right, isn’t there a finite amount of resources so that these issues matter in terms of who gets supported and what happens as a result? Is that a concern now more than it was before perhaps, now that you have your own graduate students, for example?

Kaplan:

Yes and no. I am still of the attitude that I would do physics if I lived in a van. I really—I cannot help but do this. And those are the people who are going to come up with something. The people that cannot do anything else but this will do it in their sleep. We’re just addictively trying to figure things out. Those are the people.

Now in theory especially, you can do it in your van. So in that sense, is it taking money away from the work? The scale of theory funding is small compared to the scale of experimental funding. I’m more concerned about bad choices in funding experiments, and not because of indoctrination or da, da, da, da, da. Or, I mean, I wouldn’t say that labs are trying to keep themselves afloat, and so they create make-work projects as opposed to important physics. But as a theorist, I can inspire experimentalists to go for more interesting things. And so that is a battle that I don’t feel angry about. It’s something I have facility in, and it really matters. People being able to do experiments of all types, of all sizes, that really matters. Theory, you know, the people who are doing phenomenology, there’s just a lot of garbage. There’s a lot of stuff that’s not going to amount to anything; same with string theory.

And a lot of people get funded for all kinds of reasons. The DOE is going to fund people for all kinds of reasons, and so a small percentage of that funding in theory will be useful. And, yeah, I celebrate when somebody who is really interesting, creative, gets award or funding or something great. I lament if, like, god, why are they funding all that crap? [laugh] But I don’t—seeing the world as it is today, I am still stunned that we are funding theoretical particle physics, that there is enough enlightenment in the world that this is still happening. So the sicknesses in theoretical particle physics, I do rail against but in a scientific way. You know, I give talks. I say, “Look, I think this is all crap because da, da, da, da, da, da, da.” But that’s it. I haven’t turned up the volume on that. I haven’t…

Zierler:

How much of your field—I mean, you know, talk about after railing against string theory, you’re putting up a mirror to your own field, right?

Kaplan:

Yes.

Zierler:

How much of this is about the fact that ILC, for example, is still in development? If ILC was signed, sealed, and delivered, and you were ready to go tomorrow, would you feel the same way about the relative lack of fundamental work that remains to be done, or are you more commenting not about the science but where we are as a society, and its capacity to support the next generation of science?

Kaplan:

Oh, that’s loaded. Look, I mean, there’s a lot in there. There are many aspects. One is the fact that there is significant funding for doing the kind of research that doesn’t have immediate consequences.

Zierler:

You mean here and now, not theoretically, here and now there’s plenty?

Kaplan:

Here and now, here and now, here and now, here and now. I can look at trends. I can say, well, our funding really came out of the Manhattan Project and the military. And after—you know—starting in the mid-’60s, there was question as to whether our field in particular actually does contribute to the war effort, and so funding kind of started turning a little bit, and stabilizing, and then slowing decreasing over decades. But it’s slowly decreasing. It wasn’t just cut off.

And so for me, and then worldwide, there’s varying levels of interest in these things. I mean the SSC was canceled. The LHC was built. These are big-budget items for things that almost nobody understands. I find that impressive. And, yes, we’re struggling at the front line, but it’s amazing. It’s amazing these things are built. They’re marvels. And if people completely understood, you know, the aspects of it, I think they would support building it because they’re cool, and because they have spin-offs, and because they’re part of the distribution of all science. You have to feed the very end of the distribution to get the feedback to allow for a broader development of knowledge in science.

But when the cost of the thing is so big, and the thing is so singular, then I get it, it’s hard. It’s hard. [laugh] It’s a hard push. And, you know, the very human aspects of this endeavor come out. All of those feelings and thoughts and arguments, you know, and intentions that are not hardcore objective come out because particle physics is super easy. The whole idea of particle physics is to—is a reductionist one. And you bring things to where the laws of physics are the simplest, and you describe them, and discover them. And sociological, political, and economic discussions all wrapped into one around a decision about scientific effort, the results, as far as I’m concerned, we can treat as random.

And so if you’re asking about the fact that the ILC was not funded or whatever, my feelings about that, I understand it. And, you know, some of those things are not funded because they’re internal questions. Yeah, the ILC’s OK. I wasn’t excited about it. There was a time when the ILC was being proposed, and the SSC was canceled, and the LHC was going forward. And there were people in the United States in our community saying, “Oh, the LHC is crap. It’s a mess. You’ll never see anything. Pile up, blah, blah, blah, blah, blah, messy environment, so.” They aren’t going to canc…even though the LHC was approved, and the ILC was barely at the drawing board—I mean, the ILC was not funded because it was not an obvious thing to do.

The SSC was canceled I think just because it was very—it was the most expensive thing, scientific experiment, on the ground ever built. I don’t count the space station. That’s not a scientific experiment. That’s something else. It invokes other things. But pure science, it’s the most expensive scientific thing. It’s the biggest physical machine ever built, and it was at a time where budgets were being cut, and they were trying to figure out what to do. So it’s just—you know, it hit a threshold. So there is a threshold.

Zierler:

So would you say that, you know, particle physics, theoretical particle physics is easy? It’s reductionist? How much of that though is—

Kaplan:

[laugh]

Zierler:

Does it exist because—

Kaplan:

I’m exaggerating.

Zierler:

Of course, I know.

Kaplan:

[laugh]

Zierler:

But that you are of a generation that was the beneficiary of, you know, the response to Sputnik, and people like Pief Panofsky, right, that created those scientific endeavors where you can say with confidence we understand at a deep level how these things operate, right? How confident are you that the same could not be said today, except absent those new large-scale projects, right? You know, in 50 years, the next generation can’t say what you’re saying, reflecting back on, you know, your lifetime in the field.

Kaplan:

So I think part of it you’re asking is that just if things are turning around now, 50 years from now we could be in the dark ages?

Zierler:

Well, not that we could be in the dark ages. But what’s the difference between not being able to continue to do fundamental work because there’s no more fundamental work to be—to do, versus there is fundamental work to do but we don’t have the tools to do it to push it to the next level?

Kaplan:

Good. I—there could certainly be that, yeah, for sure. But we’re not there, and we’re not even there to be able to assess that, for the following reason. There were budget cuts, and the solution from our field was to narrow down to only a few directions. “Everybody should work on collider physics.” And dark matter is popular. “Everybody should think about WIMP dark matter.” One theory was popular—so the same sickness as in string theory—one theory dominated. Supersymmetry, with a specific range of predictions for dark matter, a specific set of predictions for colliders, dominated the field. People worked on it very hard in great detail. The field became a field about large colliders and large detectors as a supplement to those theories that were predicting interesting things in large colliders. It narrowed terribly, such that the only solution, the only next step, is a collider that’s 100 kilometers around, and say a 10-ton WIMP detector. I think people were afraid of losing the financial support for these experiments, so they encouraged everyone to support them – so we don’t get a repeat of the SSC.

I think the field gets bigger, you go from, you know, a few hundred to 2,000 to 6,000 string theorists, you don’t get a broader set of ideas. You get a narrower set of ideas. How are we going to pay for all these people? It better be under the umbrella as the most important thing to do, which is the LHC and the next collider. That’s the most important thing to do. Dark matter, it could be anything. But we know it’s most likely this. So build 27 experiments as big as possible to do that one thing. That’s obviously stupid. And so it is true that a boundary — a threshold for understanding — one of the boundaries is energy. You go to higher energy. You can resonate with heavier particles or higher energy or shorter distance phenomenon. But it is not the only threshold.

And creating those phenomena is not the only resource for it, because those phenomena must’ve been created in the early universe, and there are many things that could be at lower energies but at weaker coupling. And that half of the field—if you just divide it in two halves, you can go for heavier particles to higher energies, or you can go for weaker coupling to the higher sensitivity – half of the frontier went orders and orders of magnitude deeper in sensitivity. The weak coupling side did not. And so we’ve just ignored, due to expediency or something, an entire half of the ‘theory space’ of possible things that could be happening. Of course half versus half is not a good measure, but you get the idea.

And so I don’t think, oh, god, we’re getting to colliders that we can no longer build, da, da, da. No, stop fucking just talking about colliders. There are so many things to think about. I don’t know what narrowed our field. I don’t see it as we’re dying because we’re coming to the limits of what we can do, the limits of what we can calculate in string theory, and the limits of how big of a ring we can build. I think most people are just doing useless stuff.

And there were very few ideas for the number of people working on it. And I do think there are experimental techniques which 50 years from now will be so much more important than collider physics. There will probably be collider technologies well beyond what we can imagine now. The point is, it is particle physicists pushing collider technology, but there is a whole world out there pushing sensor technology. Thus, I think the future will have technologies capable of answering many more questions. I don’t like to make predictions, so don’t trust me either because nobody should be making predictions about anything, especially the future – to quote Yogi Berra.

A nice example of the kind of things that I think about now that I’m not the expert in but I think about it because I think it’s important, and I’m watching it happen, and it’s very popular now is, let’s say quantum phenomena. There is a level of quantum state control in atoms, in molecules, in optical systems which has now crossed the threshold into being able to do fundamental physics. They’re not just testing the equivalence principle of gravity, which they’ve been doing for some time. But they have models of how to detect gravitational waves. They have models of ways of potentially measuring short distance forces, or dark matter that is in some large range of masses which is much lighter than the things that people were going for in the past. I think there’s a ton of stuff.

And the way my genius friend — who is the most creative physicist I’ve ever met in my life — he was a student of Savas’s, and we hired him—Surjeet Rajendran—he likes to say that we mastered electromagnetism in the 19th century, and that’s why colliders dominated the 20th century. But in the 20th century, we mastered quantum mechanics. And so the thing that’s dominating the 21st century will not be another collider. It’s going to be a completely different probe of new physics.

Zierler:

Wow.

Kaplan:

And so that’s why I—the whole depression or whatever, that’s a product of the non-willingness to feel stupid by the majority of our field. Expertise is more important to them than discovery. And that’s what I think is happening. And so what we’re seeing is not the death of the field, but the death of a direction that is being committed to by 98% of them.

Zierler:

[laugh]

Kaplan:

I am super optimistic about the future, super optimistic. And I’m working on things that I thought I would never get to work on because there will always been people faster than me. But there’s nobody working on it.

Zierler:

David, I can’t help but—I mean, 98%—I’ve heard that figure raised in talking about because of dark matter and dark energy, we really don’t understand how 98% of the universe works. And here you’re saying 98% of the physicists don’t even know what they should be working on. [laugh]

Kaplan:

Yeah, which is why we don’t understand 98% of the universe because they should be doing something else. [laugh] They should be doing—

Zierler:

Yeah. So really what you’re saying is that absent the mania of both string theory and this obsession with collider physics, there’s all kinds of fundamental work to be done right in front of our faces now—

Kaplan:

Yes.

Zierler:

—that’s not being done?

Kaplan:

Absolutely. It’s the young people who are converting to it. They see it. Different—so what you’ll see [laugh]—I mean, our field can’t help itself. What’s becoming popular is trying to discover the axion. The axion was a—is a theoretical, possibly interesting particle that was proposed in the ’70s [laugh] and, you know, as an interesting possible dark matter candidate in the early ’80s, and an idea for detecting it in the mid-’80s by Sikivie, and very little progress on this.

And people—for the last 35 years, people were talking about dark matter, and they would say, WIMPs, weakly interacting massive particles are the most likely, the axions are the second most likely, da, da, da, da, da, sterile neutrinos and then other things like that are less likely. That was their—everybody had that list. That’s why we work on these things because this is the most likely dark matter candidate.

If you’re an experimentalist, and it doesn’t take you six months to write a paper, it takes you 10 years to build an experimental program, then you’ve got four experiments in you. That’s it. What are you going to do with your life? You look at the list, you do number one. Why the fuck would you do anything else except number one? The theorists are telling me that’s the most likely dark matter, so let’s do that. The idea for detecting axions was developed in 1985 or something. And now we’re getting some progress in that?

Zierler:

[laugh]

Kaplan:

Is it—was it that the technology wasn’t there? OK, maybe. But come on. That’s crazy. Where—how did we do on WIMPs? Twelve orders of magnitude in sensitivity, 12 orders of magnitude, a trillion times more sensitive to WIMPs. But we haven’t discovered them. It’s probably not there. What are you doing? It’s—the markers in the field are obvious. This is exactly what is happening. Now axions are super popular, and people are even being broader about what an axion could be—thank god—and thinking they have axion-like particles. And so there are many papers working on that. Dark matter is axion or axion-like particles, and let’s think of experiments that could be developed to see those things. This is early days, so I say thank god. It’s all interesting and new. But we’re going to fall into the same stupid rut with the 6,000 people times .98—

Zierler:

[laugh]

Kaplan:

—all working on [laugh] detecting the axion of certain mass ranges. [laugh] So it’s going to happen again. But that’s OK. That’s OK. But there are a number—but there are a few people, you know, that are like, “Oh, no, but what about this? Or could we do this? Or could we do”—you know.

Zierler:

All right, David, last question. [laugh]

Kaplan:

[laugh]

Zierler:

Looking ahead—

Kaplan:

I went from a gentle—

Zierler:

[laugh]

Kaplan:

—like everybody’s cool to the total tirade, you know.

Zierler:

[laugh]

Kaplan:

This is why I get myself into trouble.

Zierler:

How do you see your—because in physics terms, you’re a young guy, right? Physicists never retire. You could do this another 30, 40, 50 years, till 120 we say, right?

Kaplan:

That’s—yes—that’s—you’re taking it out of the Jewish traditional blessing.

Zierler:

There you go.

Kaplan:

[laugh]

Zierler:

How do you see your own research agenda as testament to all of these structural problems that you’ve been railing against? In other words, how do you see your own future in the field as a way of saying look how we can do it? We can do it better, and I’ll show you how?

Kaplan:

My first experience with that was when I was at Argonne, and I was looking at Higgs data from the LEP experiment, which was the experiment previous to LHC, and I realized, well, that’s weird. They’re assuming the Higgs always decays in these ways, but there could be new physics. Shouldn’t you look for decays in other ways? So then I looked at the analyses, and there was a little work on that. But they were—it was based on very narrow ideas of supersymmetry.

Supersymmetry explained how the Higgs could decay in a funny way. And like, well I thought, what—we could do this other more general thing. What I found was that the analyses that people did, of the data, it was always biased by a specific theory. If the theory didn’t predict certain decays for certain masses, they didn’t do the analysis. They didn’t even look at the data. [laugh] And I thought, “Oh, we’re in trouble.”

And so I started giving talks about searches for general Higgs decays. And I would rail against theoretical biases. I would write a paper about—there were goofy papers about how Higgs could decay in all different ways. Then I realized that there were those kinds of decays in other decays like them. We would search for a Higgs that is not at the LHC ATLAS experiments but you would see it at the LHCb experiment, which is a B physics experiment. They don’t look at a collision, with everything going in all directions, try to see the heaviest particle that came out, and what it is. They had an experiment they—the things collided, and they only looked in the forward direction. So they look for these weak scatterings, and that would produce light particles like bottom quarks, and they decay in a funny way, da, da, da.

And I said, “Wait, actually, the Higgs is pretty light probably compared to the LHC. So the Higgs probably ends up there too. So if it decays in funny ways, just look for the Higgs there.” Actually, you can look for supersymmetry there. You can do all kinds of different things. And I thought how could I—who certainly didn’t understand experiments anywhere near as well as Ann Nelson, my old advisor, or the experimentalists building these things—how could I come up with these things?

And so then I just started thinking what are the types of experiments that could be. What—how could you discover different things? And I wasn’t that good at it. But I did a sabbatical at Stanford to visit Savas and his students in 2007. And I met these two students, Peter Graham and Surjeet Rajendran. And they had just realized that they could use atom interferometry to detect gravitational waves. And I thought that was the coolest thing I’d ever heard. And I thought that this is the future of the field because if that is the sensitivity, and the rate of sensitivity in atomic and molecular physics is not stopping, the slope is either constant or increasing, we’re going to—that is going to be an amazing direction. And so we should all do—listen to that and do that kind of stuff. And I am so untrained in that. I’ll try to learn as much as I can. But it’s going to take me years to start figuring those things out.

And I came back to Hopkins. I told everybody, “This is how we’re going to start to detect gravitational waves in future.” This was before LIGO’s finished. Nobody’s detecting anything yet. They’re like, “Uh, OK.” Then I made this movie called Particle Fever, this documentary film, which I’m thrilled, by the way, that we didn’t talk about at all. And then as my recovery program from filmmaking, I wanted to take a sabbatical, take 18 months to just do physics and nothing else. And the guys back at Stanford are like, “Oh, come visit, come visit, come visit.” And by then, Surjeet got a faculty job at Berkeley, and so I went back to do a joint thing there, and realized the relaxion could solve the problem with the Higgs, the hierarchy problem.

But we also did a nice little experiment proposal, which is if dark matter’s very light, then it acts more like a wave. And if it couples to matter then, when they fluctuate, they actually fluctuate the mass of fundamental particles. And if it’s a wave, and you have let’s say a block of matter, and the wave, you know, goes—has different amplitudes across the block, then particles on one side of the matter are heavier than the other, and that’s a force. That produces a force because particles want to move to lower potential energy.It turns potential energy mass into kinetic energy. And so that means dark matter that’s light could produce an oscillating force on objects. And so we looked at all of the experiments that we’re doing tests of weak forces, and ask could they test a time-dependent force on dark matter. And so there’s a nice experiment in Washington, a torsion balance. They’re looking for forces that are not gravitational that depends on a type of material.

And we said, “Look, we analyzed this for your experiment. It looks like you could do it.” And then we got a young guy from that experiment to join us. We wrote a paper, and that’s it. And I started thinking like I want to be engaged in this, though I am still—I’m weak compared to these guys.My strength is model-building and certain quantum field theories and things like that. And when that’s necessary, you know, I write that part of the paper. [laugh] And but I’m, you know, like a graduate student for the rest of it. I’m like, “Oh, wait, what about this? What about this? Oh, could you do this?”

And so I am just—have dived into those things. Those guys, are part of the axion revival, they came up with the first new way of detecting axions in a totally different mass range. That experiment is funded now, and being—it’s built. The first level is built, and they’re releasing data. Surjeet has loads of experimental ideas, and I’m like again a graduate student just learning from him. We’ve written a second paper on detecting spin-dependent forces. Surjeet is worse than me. I mean, he really thinks everybody’s an idiot.

Zierler:

[laugh]

Kaplan:

He has the sort of intensity around the righteousness of what should people work on, plus the ridiculous humor of Savas making fun of everybody constantly. So you never know if he’s mad at somebody or just making fun of him. He’s terrible, and he is the most creative person I’ve ever met—most creative human being I’ve ever met. And he—and I get to work with him, and I get to think about—we’ve thought about a different way of detecting gravitational waves.

Whereas LIGO has this other experi…their experiment is bouncing light back and forth, and they see if the mirrors move back and forth. And the problem is if the gravitational wave is very high frequency, then they don’t move very much because the gravitational wave basically cancels itself out one mirror to the other, so. However, if you make the experiment very small, then the effect is very small too because it’s proportional to the distance. So what do you do?

So we realized that you can change this into an angle. And if you change it into an angle, then the effect can be as small as you want, but you can make a very long baseline, and you can detect the movement of a laser at extremely long distances. So Surjeet searched, googled, and then he said, “Oh, there are these engineers in Germany that have built this device that they created in a 3D printer that if you push like this, they turn like this. And it’s an order one effect, so you have no loss. Let’s talk to them.” [laugh]

We’re about to submit a paper with them, a year and a half later, on a new addition to gravitational wave detection that can deflect the beam. What was weird when I was first so excited about this, the first 10 years, particle physicists were like, “Yeah, gravitational waves, you know, that’s astronomy.” I’m like, “What? [laugh] But it’s one of the great things in physics. It’s going to be—everything’s going to change with the gravitational wave. Everything’s going to change.”

So I—that’s—but I’m the graduate st…I’m—you know—I’m 51 but I’m just some—I’m an idiot constantly. There are always people around me who are better. And I’m looking for the people who are seeing something that’s important, and let’s see if we can figure out how to make progress in that. And I’ll just keep doing that, and I will—you know, and I’m also not attached to credit. I don’t—they’re the first author. They’re famous. They’re brilliant. I don’t care. I want to be a part of it, I want to have fun, and I want us to discover something. So if I have to share the Nobel Prize with Surjeet and Peter—

Zierler:

[laugh]

Kaplan:

—I’m perfectly happy to sit behind the Queen instead of next to the Royal—or whatever. I don’t care. [laugh]

Zierler:

Well, David, I have—

Kaplan:

But they don’t get it, you know. I could use the money to pay off debts or college for the kids or something, but the money would be great too. But this is the best part of it.

Zierler:

I have to say this is not one of those interviews where I would have to say, tell me how you really feel? [laugh]

Kaplan:

Yeah, yeah, I know, yeah. [laugh]

Zierler:

[laugh] But it’s obvious that it comes from a deep love of physics and, you know, a deep love of the importance of doing it the right way. So I think it’s—you know—it’s tremendously valuable to, you know, have this perspective out there in such unvarnished form. So that’s—I’m really glad we were able to connect, so I really appreciate our time together.

Kaplan:

Oh, thank you. I would say it’s even more just the love of people. And I rail against all kinds of things. But I want them to work on good things. I love them all.

Zierler:

Yeah, the love of people. You don’t hate the people. It’s that—

Kaplan:

Not at all.

Zierler:

It’s that you love the people, and you want them redirected towards productive things.

Kaplan:

Absolutely.

Zierler:

Yeah.

Kaplan:

And I think they can do it because they’re all smarter than me, and so I really think that—

Zierler:

[laugh]

Kaplan:

—we would make a lot more progress if people would just be willing to sit and not know what they’re going to do next, and do that for a long period of time. Then better stuff’s going to come out.

Zierler:

There you go.