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Interview of Sarah Demers by David Zierler on February 17, 2021,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
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Interview with Sarah Demers, Horace D. Taft Associate Professor of Physics at Yale University. Demers explains her academic lineage connection to Taft, and she surveys the challenges of remote work in the pandemic. She recounts her Vermont childhood growing up in the church as the daughter of a United Methodist minister and how her family discussed the compatibility of science and religion. Demers discusses her undergraduate experience at Harvard and her early struggles with physics. She describes her relationship with Melissa Franklin and her first experiences with the CDF detector project at Fermilab. Demers explains her decision to go to the University of Rochester for graduate school where she studied under the direction of Kevin McFarland, and she describes plotting the Z boson at Fermilab. She describes her first job teaching at Roberts Wesleyan College and her subsequent appointment as part of SLAC’s team for ATLAS at CERN, where she developed an infinity for the triggers of experiments. Demers explains the opportunities that led to her faculty appointment at Yale, and she describes the interests that led to her book on physics and dance. She discusses her ongoing collaboration with ATLAS, the tenure process at Yale, and her work on Mu2e. Demers describes the “aesthetic hints” that may prove to be physics beyond the Standard Model, and she explains why the LHC can play a pivotal role in the search for dark matter. At the end of the interview, Demers discusses her current interest in tau leptons, she describes the issue of bias as a blockage to improving diversity in the field, and she reflects on the technological improvements that have propelled her field forward.
Okay. This is David Zierler, oral historian for the American Institute of Physics. It is February 17, 2021. I am so happy to be here with Professor Sarah Demers. Sarah, it’s great to see you. Thank you for joining me.
It’s a thrill. Happy to be here.
All right. So, to start, please tell me your title and institutional affiliation.
I am currently the Horace D. Taft Associate Professor of Physics at Yale University.
Now do you have any connection to Horace D. Taft or the Taft family? How does that particular endowment play out?
Horace Taft actually died relatively young while still very active at Yale. He was a particle physicist, which I am, and it’s an unusual designation because it’s given to an associate professor. To become full, you actually lose that designation. But I do have a cool interaction or at least connection to Horace. He was my advisor’s advisor’s advisor, so he is part of my tree, my academic genealogy, I guess you would say, so it’s pretty neat. I also hear that he was a wonderful person, so I’m very happy to have that designation for a period of time.
Very cool. Well, Sarah, before we take it all the way back to the beginning, a very in-the-moment question on both the personal level and a research level. In what ways have the past ten months been extraordinarily difficult in terms of your research, and have there been any opportunities because of the physical and social isolation that we’re all going through, that because of remote work or data analysis, you’ve actually been more productive in certain areas than you otherwise would not have been?
I would say… Let me answer the easy one first. There is no area in which I am more productive. That’s pretty simple to get to the bottom of. I do think that there are ways that I have benefited in spite of that. I tend to travel quite a bit, so there are lots of meetings that I have missed that I haven’t had to go to. I love traveling. I love seeing my colleagues. They’re my friends, so I’ve missed components of that for sure, but I would say that it’s overall been less exhausting. So that’s personally been a benefit. My kids are fairly young, so it’s been nice to be home and not miss birthdays. I think last year I missed every birthday, my husband and both of my children. I was traveling for all of their birthdays.
So, that was nice to try to break that record. But no, it certainly has been challenging from the productivity perspective, both because of less time to work on my traditional work and also because of the expansion of what that work is, both from my teaching and mentoring and also my administrative work through research.
Now the big question on everyone’s mind right now: When this pandemic is finally over, what do we take from it? In what ways does the value of Zoom stay with us, and in what ways are the benefits of in-person connection really irreplaceable and we’re going to get back to that as soon as possible? For you, for the science, for the collaboration, what do you want to keep going forward, and what do you want to go back to as normal?
I think that my collaboration was international and Zoom-based forever. I mean, we had Zoom fatigue a decade ago. It wasn’t Zoom; that wasn’t the technology we were using.
But we were in meetings, you know, all day every day. So in many ways it hasn’t been that different aside from now in the field, people tend to turn their cameras on a little bit more than they used to, so that’s a plus and a minus. It’s a minus for me when I’m joining a meeting at 5:00 in the morning and everybody wants to wave and say hello and I’m still in my pajamas, right? There are some things that I hope we continue and that I hope we’ve learned from.
For one, I think there are people who have always been in the time zone, so they’re at the lab, they’re based at the experiment, and they don’t have a good sense of what it’s like to try to keep up with things and stay involved from a distance. I think that this has given everyone at least a little taste of that, so that’s a benefit in that people’s eyes are open to how hard it is to try to stay in touch and make forward progress when you’re not running into people in the halls. That’s great.
But I think it’s absolutely exhausting in some ways not being able to travel. So, my day begins at around 4:30 now because I have very early meetings. There’s a 2:30 a.m. meeting that I ought to be attending fairly regularly where typically I would be able to go to CERN for a couple of days and hit those kinds of meetings. Now I have to really shift my time zone more, so that’s a drain. That really means that I’ve shifted my life much more in terms of time zones than I used to have to when I could take care of some of those meetings by traveling. There has to be somewhere that you can go and occasionally get some sleep. So, I’m looking forward to traveling again and being able to go… It used to be, when I was in graduate school, you would go to the experiment and not sleep, but now I feel like the only time I can sleep is when I’m actually in the time zone of the experiment.
So, your sense is, post-pandemic, what’s happening over Zoom at places like CERN and DESY and places like that, every opportunity that there is to go back in person will be pursued. That’s your general sense.
Yes, because we’ve been doing so much by Zoom already. We have a collaboration of 4,000 people spread around the globe. Many of us have to be teaching throughout the semester. Many of us can’t afford to travel much. I hope that there are some conferences that are either dropped or merged. I think that the amount of conference travel is probably excessive, but I typically have avoided that travel. I haven’t gone to that many conferences. Most of my travel is for my own experiment, for my own collaborations—you know, for the actual research itself as opposed to presenting on that research.
Right. Well, Sarah, let’s take it all the way back to the beginning. Let’s start with your parents. Tell me a little bit about them and where they’re from.
My parents. So, my father is from…Gosh, where would you even say he’s from? Probably New Paltz, New York, though he met my mother in Burlington. My mom is from Vermont/Pennsylvania, and they met in high school in Burlington, Vermont.
Now when you say it’s hard to say where your dad was from, did he move around a lot when he was a kid?
It’s a combination of my memory…No, he didn’t move around that much. I think it was New Paltz to Burlington. Both of my parents identify emotionally as Vermonters at this point in their lives, and that’s a very sore subject because in Vermont, if you’re not born there, you’re for life branded a flatlander, right?
So, it’s hard for me, but I have to confess that my dad is from New York and my mom is from Pennsylvania. But they would love for me to say Vermont all the way.
What were their educational backgrounds?
My dad is a—well, he just retired—United Methodist pastor, but he really trained to be a musician. He was and remains extremely talented at piano, so he went to the Hartt School of Music. He started out [there] and then transferred to University of Vermont. So his training was in music, though he did go to seminary at Boston University and divinity school there so that he could become a pastor.
My mother, her formal training was also at the University of Vermont. Her degree was in art history, but if you look at her life’s work, that’s not something you would guess based on all of the jobs that she’s had.
Did your father have a pulpit?
Oh, yes. You mean did he preach?
Oh, yes! Oh, yes. I grew up going to church. That was pretty much my life, and I think it’s been a tremendous benefit for me in my teaching and communicating because I would listen to sermons. He is a great storyteller, and I really learned from that something about how to communicate and also what doesn’t work and also how quickly people forget what you said. My dad used to quiz us the next day, two or three days later about the sermon, and it was rare that we could remember a detail beyond the stories that he told. So, all of this research about physics education and how lectures are not necessarily an effective way of teaching is not something that I found shocking. But the power of a story and the way that maybe a story or something that’s personal can stick with you, that’s something that I experienced firsthand.
Where did you grow up? Did you move around a lot for your dad’s job, or mostly in the same place?
No, we moved around quite a bit, mostly within Vermont. The United Methodist Church moves pastors every…I don’t know. I guess the longest stint we had was eight years. Yeah, we moved around quite a bit when I was growing up, and we lived in parsonages.
What is a parsonage?
A parsonage—that’s where the pastor’s family lived.
Yes. That was my parents’ excuse for how we couldn’t put posters on the walls of our rooms because the church committee would come through because it was the church’s house. They would come through every year and look at all of the rooms. So it was your house, but you know, it was the parsonage that you were living in…and particularly in the smaller towns. I mostly grew up in Groton, Vermont, a town of about 700, and there the parsonage was certainly the town’s house. It felt very much like it was the church’s house, mostly in wonderful ways, actually.
Sarah, did you mostly go to public school? Did you have Sunday school?
Oh, it was public school that I went to until my senior year in high school, actually. I grew up going to public schools, small schools in Vermont.
What did you do for your senior year?
So, I was an ambitious and driven child. [Chuckles] The schools that I went to had many wonderful things about them, but there weren’t a lot of classes offered, so I ran out of classes pretty early. My junior year I pretty much had finished the courses, and so I applied for colleges that year and didn’t get into the ones that I wanted to go to because, as I mentioned, I was a very ambitious, naïve child. I applied to Harvard in particular and had four interviews with Harvard, which I thought was potentially a good sign, but my final interviewer confessed and felt terrible that they were using me to calibrate new interviewers and that I was not going to be accepted. She told me, “It’s very unlikely that you’ll be accepted.” But there were private schools that were an option for me that I didn’t really know anything about. So she had connections at Phillips Andover Academy in Andover, Massachusetts, and we, of course, couldn’t afford that school, but I was an athlete and so I actually went to Andover on an athletic scholarship for my senior year.
For what sport?
Oh, I was not that good an athlete that they actually had to designate the sport. I’m a basketball player and I ran cross country and did track. I was required to be in a sport every semester; that was the deal, and I was there as a Phelps Scholar, which is an athletic scholarship.
Sarah, when did you get interested in science? Was it early on?
Oh, no. No. Well, define early.
I mean like seven, eight years old—looking up at the stars, that kind of thing.
No. I mean I have nothing against the stars, but I did not get interested in science until I took physics. My parents were not scientists. Actually, algebra-phobic, I would say, is basically where my parents were. They didn’t go past algebra, geometry levels in school. For me, I always wanted to be a constitutional scholar or a defense attorney because my read of the Constitution and my understanding of the whole society was that those were the two most important jobs. Those were the most fundamental jobs that you could have. I didn’t know any lawyers either, but I thought, “That’s what I’m going to do,” because I also was very good at arguing and that seemed to be something that translated well. But I thought of myself very much as a humanities person—lots of music in my family, lots of art, and so maybe something in that direction. But I took physics and…
In high school, you mean.
In high school, yeah. Yeah. It was, just from day one, shocking, absolutely crazy. I have never recovered from learning that if you fire an object—we’ll call it a potato in a potato gun—over a horizontal surface, a flat surface, the potato that’s fired will hit the ground at the same time as a potato that’s dropped. That was so counterintuitive to me, and everything about physics was counterintuitive to me. A lot of subjects came easily to me. School was not that much of a challenge for the most part, but physics was hard! I had to really work at it. I didn’t understand how to take the ideas that I learned and translate them into solving the problems, and so it felt just like a massive challenge and a huge earth-shattering kind of…It just was…I had been paying attention to the world for 17-ish years and was wrong about so many things, and I found that really fascinating.
Growing up, to the extent that you engaged your parents in these kinds of questions or if these were the kinds of things that occurred to you yourself, would questions about the compatibility or not between science and religion—were those things that were discussed at the dinner table?
Everything was discussed at my dinner table, yeah. My dad in particular has a really strong interest in philosophy and theology. Both of my parents are very well-educated and very curious, I would say. My father’s theology was fairly liberal, to the point where it made us a little bit nervous about him keeping his job at times, like, “Maybe don’t say that from the pulpit, Dad. That might not be a good idea.”
Even in Vermont.
And I think it made my mother very nervous! But there is a lot of respect for science in my family, and my extended family certainly has many people who are very conservative theologically, with a lot of Evangelical Christians in my extended family.
So, it’s always been a puzzle to me or a disappointment that there is as much science-religion animosity as there is. I see a lot of misunderstandings. I see a lot of people trying to take one set of tools and apply them in a different context. People make a lot of assumptions about others, and I think maybe growing up with that strong Evangelical piece…yeah. I’m sorry. I’m very far away from your question. Yes, there were definitely art-science conversations when I was growing up, but it was always in a curious “Let’s talk about science and what we’ve learned and let’s look at history kind of perspective.” It wasn’t at loggerheads, I would say.
And to be clear, the statement you’re making about people misapprehending potential contradictions between science and religion—that cuts both ways. You could be referring to scientists and their views on religion, and you could be talking about religious people and their views on science.
I am absolutely having that cut both ways, yeah. I mean, I think my greatest frustration with scientists is the arrogance and the dismissal just of swaths of the population without thought. And I guess my greatest frustration from the other side with people who are more conservative is a misunderstanding of what science is to some extent or what science claims and a lack of acknowledgement about how relevant and interesting it can be, even in that different context. Yeah. I don’t know if that helps.
So just to get down to brass tacks, from all of the excitement in inflation in the early 1980s where we might truly understand what happened at T = 0, we still don’t understand that perhaps we’re farther from understanding based on all we know in the interim, right? Religious people will come at that and say, “Well, of course you’ll never understand because that comes from God and there’s a part of God that is unknowable to us.” Where do you see yourself fitting in in those broad debates where you might make bridges along these lines?
Yeah, I think that it is hard to talk about that even at that level of abstraction, right? I mean, there are the Stephen Hawkings of the world, or former Stephen Hawkings of the world who try to make progress…I think it’s not T = 0, but it’s T = -1 that is really interesting to talk about, right?
Meaning like if T = 0 required the laws of physics, where did the laws of physics come from, that kind of thing?
Yeah, yeah, yeah…I don’t know.
Well, I think the idea…You know, if there are hard-nosed people on either side of the debate and your perspective is there is a lack of understanding, there might be a certain specificity that you might draw to create that understanding because many physicists will say, “Well, of course there’s no God. There’s no evidence for God. Why would we think that there is a God? We’ll get to that understanding of T = 0 or even T = -1.” So, that’s just one example; there are many to draw on. I’m trying to think of ways in which you might operationalize these bridges that you think should be there.
Right. I guess the pep talk that I would give the religious people is that maybe there’s a God that’s big enough for them to think about that’s not threatened by the scientists trying to understand T = 0. And for the scientist, I would give them a pep talk about maybe a little bit more humility, about how far we’ve come, how far we have to go, and how potentially poorly matched our tools are to nature.
Right. Right. Well, you got into Harvard. How did that happen after four swings and misses as an eleventh grader?
[Chuckling] I know! I think that Harvard’s attempt to have some diversity in its class and the fact that I was from a very small town and survived at Andover for a year probably helped me. I do remember when I got to Andover, there was a big meeting for people who were interested in going to Harvard or applying to Harvard. I hadn’t met anyone who had applied to Harvard before going to Andover, and I remember walking into the room and there were hundreds of people there who wanted to go to Harvard! I thought, “What have I done? There’s no way I’m getting in now because they only accept like 15 people from this institution!” Not that my whole goal in life really was to get to Harvard. I was a little bit more broad in my thinking than that, but it did seem like I had not played my cards well. And at Andover, I really struggled in physics. I mean, I believe everybody hits a wall with physics and I hit it there. I was underprepared from the math perspective, and so I think I got my lowest grades in physics at Andover out of all of my subjects. I remember I applied to Harvard and I told them, “Physics is what I want to do,” and I thought, “There’s no way I’m going to get in.” So, I don’t know how I got into Harvard.
Were you taking college-level physics at Andover? What was so much harder in the curriculum from one year before in a public school?
Well, let me tell you that my public school AP English teacher was also my public school AP calculus teacher. We started every calculus class with the quote of the day. So, while my AP calculus teacher was a very smart person, I did not learn enough calculus, and certainly, the physics that I encountered at Andover was more sophisticated than what I had been exposed to. Yeah. I didn’t have the tools. I didn’t know the language. There was a level of sophistication there that I did not have. I could talk a good talk and fit in reasonably well, but I felt like it all came crumbling down when I had to hand in my work, you know? It was like all of the words that you mispronounce when you learn them by reading rather than hearing, right?
There’s a spectrum of responses to something like this, particularly for someone like you who identified in the humanities world. Given your frustrations or difficulties in physics, did you step away from it and only return back at Harvard or did that make you even more determined?
Well, I certainly was stereotypical in that I instantly thought, “I am terrible at this.” I can’t claim to have had a wonderfully strong growth mindset and think that I was exercising my physics muscles. It felt pretty hopeless, but it really didn’t…Well, okay. It didn’t change my path. Because I liked the challenge. Even though I only understood glimpses of it, bits and pieces of it, those bits and pieces were amazing, and that experience of finally fighting your way through and solving a problem was incredibly satisfying. My brain was wired in a way so that I would immediately forget how I’d done it and could repeat that experience all over again and have the same kind of victory just a few minutes later with the same problem! [Chuckles] Yeah, I’ve thought about this a lot because we lose a lot of people in physics when they hit this wall. And of course, the rational thing to think is that “I’m not wired for this,” right? But how do you get different kinds of brains in physics if we don’t encourage people to work on their wiring?
And what you’re saying, of course, is that we need different kinds of brains in physics.
Well, I think we need different kinds of brains in physics. You know, I’ve found that the kinds of things that I was good at before I learned how to do physics I still can do. We need people coming in from different perspectives with different backgrounds with different strengths, and yeah, we’re not selecting broadly with the way the curriculum is set up.
I think the biggest thing for me that I point to is that I had an incredibly supportive family. They were very proud of me. I could have failed out of Harvard and they would have blamed it on Harvard, you know? There were things that I just failed at, and that was allowed. I think that safety of knowing that I had that kind of support… And also, my parents… You know, I grew up in a “God will provide” household. I wasn’t stressed about having to have a job or figure out my life at that point. How am I going to pay for this? How am I going to do that? That wasn’t at all the framework. Education was just pure joy from my parents’ perspective. What do you love, you know, and maybe what are you called to do? That would be how they would put it. But from the education perspective, it was just freedom to think about what I found interesting, what I found challenging, which really let me continue to explore something that I was objectively terrible at.
[Laughs] Would you say you broke through the proverbial wall before or after you declared the major in physics and confirmed that this was what you wanted to do?
I broke through the wall in graduate school, and I didn’t realize that I had broken through the wall until leaving graduate school.
I didn’t realize that I had become a good physicist until I gave up on myself from the research perspective. I don’t know how to fix that. Even if you convince someone to have a growth mindset, getting people to take themselves seriously as physicists when they’ve struggled—that’s a really tough thing to do.
Being at Harvard in the mid-1990s, of course, it’s 25 years ago, and in many ways that feels probably like a short time ago and in other ways it feels like a long time ago. From an inclusivity perspective as a woman…I mean, Melissa Franklin was just recently tenured at Harvard, the first! Were you aware of these things? Were you aware that there was this glass ceiling? Was this something that you were alive to, or this was all sort of beyond your purview?
I don’t know. Yeah, I don’t know. Melissa was my boss at Harvard, right? I probably would not have persevered if not for that. I was the only girl in a couple of my classes. I was certainly aware of that. Yeah, I didn’t fit in with most of the physicists at Harvard. I was a rower. I was an athlete and not a great physicist, right? I wasn’t doing well, so I had my problem set groups and we sort of survived it together. If you’d asked me at the time, I would have told you that gender had absolutely nothing to do with anything. I avoided the Women in Physics group. I think there was one. There was some talk of one. I remember thinking, “Why would I want extra help? It doesn’t make any sense. It doesn’t seem right. It doesn’t seem fair. Not interested.” So, at the time, I was pretty oblivious. I certainly had some experiences that were uncomfortable or funny as a result of being the only girl in a class or the only woman in a space, you know, but I would say I was fairly oblivious to the structural challenges that were out there.
Did you engage with Melissa on these issues, or you kept it mostly to the science?
No. The first thing, when I got hired, Melissa…Well, okay. Not directly. We didn’t have conversations about this, but I remember one of the first things that she did was give me a tour of the physics building and brought me right into the women’s bathroom and showed me where the stashes of pads and tampons were in case I ever needed that. So, she did stuff like that that made me feel very much at home. I mean, it kind of had to happen because in the basement of the high energy physics building where I was working when I was her student researcher, there was only one bathroom, and it was a big room kind of bathroom, and it was a men’s bathroom. So, if you wanted to go in, there was a sign that you had to put up. You had to make sure that there was nobody in there and you had to put a sign up that said, “Women” or “Occupied.” I forget what it was. Then you would go in and really quickly use the bathroom and then kind of run out and take the sign down. So, it was definitely not a space that was set up for women, and I remember Melissa just raging through that basement when technicians had pin-ups or inappropriate pictures up. She just would rage. She was not a pushover. It felt like she was there to fight the battles that needed to be fought, and I could navigate what remained.
Did you have any other mentor kind of relationships with any other professors, for example like a Howard Georgi who was legendary for his mentoring skills and so welcoming of…and really ahead of the curve on diversity and inclusivity?
Yes! I took waves from Georgi. He wrote a book on waves, right?
So, I remember that was the class between the intro sequence and quantum mechanics, and if I hadn’t had that class…because it introduced the formalism of it, right? If I hadn’t had that class, quantum might have killed me. It might have been the death of me, as interesting as it is, right? I just don’t know if I would have survived. But I remember Howard Georgi telling me that I was smart, and he had no reason to tell me that I was smart, but he did.
Except maybe that he just…because you were smart.
[Laughing] There you go! I don’t know that I was demonstrating that in the moment, or I certainly didn’t feel smart when he said it, but yes, I do remember that. There were a number of interactions I had at Harvard that were very affirming. For the most part, it was not an affirming place.
Yeah. Yeah. I’ve heard this time and again. You’re saying this more broadly, like the culture of pedagogy of physics at Harvard was not very strong. This is not about men versus women; this is just a general problem for the department.
Well, I would put it beyond the department. In my experience, the undergraduates at Harvard were a nuisance to the faculty members who really wanted to do their research.
That was the feeling that you would get, and that wasn’t just the physics department, and it wasn’t universal. There were people who cared deeply about teaching. My sense is that things are very different now, right? I think that undergraduate education is much more central in places like Harvard. I assume that; maybe it’s not fair. It certainly feels that way at Yale, that people care about the undergraduate experience, that we try to take our teaching pretty seriously compared to what I experienced a while ago at Harvard. So, I’m projecting.
By the end of your time as an undergraduate, to the extent that there is this binary in physics between theory and experimentation and you have to choose a side essentially for graduate school, how well-defined was your identity as a physicist at that point?
I was certainly in the experimental camp, probably because my research was with Melissa in her group, and it was all experimental. That was an interesting experience for me. I mean, I was a work-study student, so I had to work ten hours a week. I started out in the library because they always had jobs, and then I thought, “I’m a physics major. I should try research.” I expected to hate it because, I don’t know, lab coats, basements, darkness. Labs are terrible. Lab classes are just awful! They suck the joy out of what you’re supposed to be learning. I don’t understand why it is because labs should be the best! Lab classes are the time that you get to act as a physicist and discover things yourself, but for some reason, we’ve just sucked the life and joy out of them, right? I don’t know why.
So, I was assuming that I would really hate research, but Melissa had an opening and so I got a position in her lab. She had a paid position because she had to make 10,000 field sheets for the upgrade of the CDF detector at Fermilab, and I loved it! I absolutely loved it, all the little engineering challenges that popped up about how we were going to glue something in a way that was repeatable. Particle physics is remarkably accessible to undergraduates, if you just look at how detectors work with charged particles moving through magnetic fields, and Melissa could explain what the detectors were doing in a way that made sense with a B-, C+ level of E&M understanding. So, I certainly felt like an experimentalist. I didn’t have the math, and I wasn’t going to ever catch up with that math or the interest to hang out with the theorists at that point for sure. I was an experimentalist.
Did you feel like you had a front row seat to the search for the top quark, or were you right there looking for it yourself?
I was after it. That really was tied up because I didn’t start until ’97 and that was done. But the excitement was still there.
Yeah, yeah. Did you spend any summer internships at places like Fermilab?
I did! Yeah, the summer after my sophomore year and also the summer after my junior year.
You went back to Fermilab two summers.
What were your initial impressions? I assume this was your first moment stepping into a national lab, let alone Fermilab.
Yes!! Oh my gosh! It’s so 1960s and 1970s! All of those…I mean the living accommodations were fascinating. I don’t remember if it was my sophomore or junior post summer when I was in dorm #2 with basically all Russian men in their forties to sixties for the summer! I will never forget that. And times when the alarms would go off in the middle of the night with the tornadoes coming through. We would all kind of walk out and huddle together in the common room and try to decide if we were going to make a run for it to the shelters across the way. Fermilab was bleak and depressing at some level.
It’s also in Batavia, Illinois. That doesn’t help.
Oh, but I grew up in a small town. You know, by that point I had gotten to Harvard, but no, I wasn’t…I’m not a location snob, I wouldn’t say, at least in terms of the surrounding community. The lab itself had a beauty that I didn’t grasp for a while. The sunrises and sunsets there are just amazing. But when I went, it was, I think, just kind of hot and bleak and scary, and I didn’t feel like I fit in very well. But there were lots of very kind people at CDF. I got involved with the running club and the dragon boat racing and made friends and loved it.
Did you talk to Melissa about graduate school? Did she give good advice in that regard?
Yeah! I think she did. Melissa was frustrated with me that I was rowing. Melissa thought that if I just left the crew team, I would be a star physicist, and the truth was more complicated because I worked like a dog on physics. I worked really hard. I was doing the best I could in physics, and subtracting crew from the equation would not have saved me.
And perhaps crew gave you an outlet that allowed you to be more productive in the time that you did devote to physics.
Yeah, I think so. I have to say I feel…It’s weird talking about myself. I was in a very odd frame of reference, frame of mind when I went to Harvard, and this idea that I’m just going to explore intellectually, do my best, and who cares how I do, really—that was really the frame of mind I was in.
When I came home for the summer and had gotten into Harvard and had that three months or whatever transition between Andover and Harvard, or two months, whatever it was, I didn’t have a lot of time to find a summer job. The pressure was not insane, because my parents made very little money, so tuition wasn’t too much of a problem. You know, Harvard is a need-based thing, but I was supposed to come up with a couple thousand dollars for my contribution. So, I was a maid at Stowe Mountain Resort, one of the resorts in Stowe, Vermont. We were living in Morrisville, Vermont at the time, near Stowe because my dad was pastor there. So, I had that and I also had a job on the tennis courts spreading chemicals on the tennis courts. So, I was a maid during the day and then went to the tennis courts, and two months in I had bruises all over my body and actually had a bloody nose for 24 hours.
I was diagnosed with idiopathic thrombocytopenic purpura. I’d gotten an autoimmune disorder that the doctors at the time thought probably had to do with the chemicals that I was working with either on the tennis courts or as a maid. So, the week that I was supposed to go to Harvard, I was having my spleen removed. I called Harvard and said, “I’m going to be late,” and they said, “We’ll see you in a year.” [Laughs] So, anyway, I had had that experience of very, very low platelet count where I couldn’t really move.
When I recovered from that and went to Harvard, I just was so gleeful to be able to exercise and work out again. I had been an athlete and I’d always cared about that that. When I saw the opportunity to join the crew team which required zero prior experience, I jumped on it and loved it and couldn’t believe that I could spend a couple hours a day rowing a boat around. I mean, talk about a ridiculous thing, but anyway. So that was central to my identity when I was an undergraduate, and Melissa was frustrated by the rowing. She just thought…You know, she had the skepticism of athletes or athletics.
[Laughs] She’s much more punk.
[Laughs] Yes, yes! Yeah. So anyway, aside from that, her main frustration with me…yeah. We had a disagreement because I got into Penn for graduate school, and I visited Penn and it was terrifying. I came back—and I also got into University of Rochester and Melissa--
What was terrifying about Penn? You’re coming from Harvard.
Oh! Well, but I was me coming from Harvard. They were very scary. I thought…They were extremely intimidating. I thought, “I don’t know physics. This is going to be…I can’t do this.”
“They” is who? The high energy people?
Yeah! Yeah! I interviewed with them. They remain scary. I still interact with them. I mean, I love them. Some of them are less scary than others, but…So I told Melissa, “I don’t want to go to Penn. I want to go to University of Rochester,” and she thought that was crazy because Penn was a better school, and she knew people at Penn. In her mind, it was a better school; she knew people at Penn and so we got into a bit of an argument, which was settled when she called her friend, Young-Kee Kim, a University of Rochester grad who gave me permission to go to Rochester.
Yeah, but University of Rochester in certain areas takes a backseat to no one. That’s the interesting thing about Rochester.
Well, yes, yes. I found an advisor there who was very intense, but the feeling you got in the group was very supportive, and so it was a great…I thought, “This is going to be great. I’m going to survive there if I go there.”
Where else did you apply? Just the two?
Oh, no! I got into Yale, actually, and Melissa told me, “Don’t go to Yale. It’s miserable to be a woman at Yale.” Lots of people were saying that at the time, and so I certainly didn’t go to Yale.
I mean what about Stanford to be close to SLAC, for example?
Oh, I didn’t apply to anywhere that wasn’t in the Northeast. It never would have occurred to me to go to Stanford, you know. My horizons were not stretched that far at that point for sure.
Like the driving home for Thanksgiving kind of range, that kind of mindset?
Yeah, maybe. But also, I’d never really…I had been to California once or twice as part of the crew team, but yeah, that didn’t occur to me. It didn’t occur to me. And these were not the days where people apply to 20 schools, right? I think I applied to four or five, something like that. Yeah. But no, I went to Rochester. The other disagreement we had about graduate school is I remember she sat me down and she said, “If you hate it, are you going to quit?” She said, “I need to know that you’re not going to quit even if you hate it.”
Meaning if you hate it, you can transfer; just don’t leave the field?
No. If you hate it, you suck it up. You tough it out. Like you need to head into this knowing that at times you’re going to hate it and you can’t quit. I remember saying to her, “If I hate it, I’m going to quit,” and she said, “You’re not going to make it,” with that mindset.
Did you visit Rochester? Did you get good vibes in a visit and that’s what did it for you?
Yeah! Great vibes, great vibes. They had an administrative assistant there who was like the den mother of all graduate students. I mean, it was…It just wasn’t stuck up.
The Carol Davis of Rochester.
[Laughs] Yeah. It wasn’t a stuck-up place. It felt relaxed. I thought, “I can come here and I can learn. I don’t have to pretend that I know stuff,” you know? This is not going to be full of jerks.
Who was your advisor? How did that relationship develop?
Kevin McFarland was my advisor at Rochester.
Now did you connect with McFarland only after you started, or this was before?
No. I met with him before I started, yeah. I wanted the security of knowing what I was going to do and who I was going to work for when I went, and so I connected with Kevin on the visiting weekend. He had a plan. He’s an intimidating guy. He’s an incredibly smart guy, but he’s also very kind. He was a great advisor.
Intimidating like in a brilliant way or in an intense way?
He is very intense. Kevin and I used to meet frequently and even frequently throughout the day. He was a very hands-on advisor. Looking back on it now, I have no idea how he could afford the time. But when he would ask for a plot and I didn’t have the plot, he would suggest that maybe we have a coffee. We would be up to like four coffees a day, you know, because I never had the plot! I mean I love coffee, but he was kind of like my druggie in that way. He would back us off. If we had too many coffees, he would then cut us off and move us to decaf and then like slowly sneak back the coffee in. He had this amazing espresso machine in his office and he would just…Yeah, the espresso was flowing.
What was he working on when you first connected with him? What was his research at that time?
He was doing NuTeV and CDF, and his interest in CDF was with the top quark, but tops decaying to a certain way to tau leptons where if you see an excess…It’s basically a charged Higgs boson search. Kevin had a master plan, and that’s one of the things I liked about him. It was his work from NuTeV that drove him to look for this on CDF and look for this and look for this. He had a landscape that he’d mapped out so clearly in his brain that he would communicate: “This is what I’m intrigued by, and this is my strategy.” He just kind of laid it all out and I found that very attractive, that kind of clarity of a plan.
What was the physical locus for NuTeV? Was it Rochester?
Oh, it was Fermilab.
But did you know him at all when you were there, or you didn’t connect at that point?
No, no, no. No, no. Kevin was new to CDF. He would tell you he’s a neutrino person. He didn’t spend that much time on the collider. I was one of his few graduate students on CDF.
How much coursework did you have before you jumped into thesis research full-time?
I don’t remember. I remember I moved out to Fermilab pretty early, maybe even in my second year. I think it was my second year, and I was taking classes remotely. Particle physics I took over a video conference system. We go way back, particle physics and video conferencing systems.
Yeah, early adopters.
Was that baked into the plan, that your intellectual home would be Rochester, but most of the research you would do would be conducted out at Fermilab?
Did you still have the Russian 40-year-olds who you were huddling with for…?
No! I actually had an apartment I was sharing with a wonderful post-doc. That’s another reason I went to Rochester maybe. There was a woman who Kevin hired as his post-doc, Kirsten Tollefson, who was wonderful on the visit. I really got along well with her, and that seemed like I could ask her questions. I didn’t have to pretend that I knew things with her. That was the goal.
Now in terms of having a hands-on mentor, where that really counts is the extent to which your mentor really hands you a problem that becomes your thesis research or allows you to figure out what you’re going to do on your own. Where did Kevin fit on that spectrum?
Oh, there was no figuring out what I was going to do on my own, I mean not in that kind of an experiment. I don’t find that with my students now, right? I mean, they don’t know which decay mode is interesting and how to map that out at the beginning of grad school. So, for Kevin, what was really good looking back is that there wasn’t a team of people working on the topic. So, Kevin gave me a topic, and he was right there. If I screwed up the code, he would look at the lines of code. He was right there, right? But I also got to learn about so many aspects of the analysis because there wasn’t a team behind it. All of the backgrounds I had to actually evaluate myself and learn from him how to evaluate myself, or from somebody else, right? So, that’s something that I feel badly for about my own students is that they don’t get to do all the aspects of an analysis as much, and when they do, the headaches are much bigger for them in terms of managing the data. You know, everything is more complicated now in terms of analysis work. But I really got to own that project and, yeah, it certainly felt like it was mine.
As you’re getting deeper into the research and you’re really figuring out your own talents and abilities, just to zoom out for a second, it’s always important in terms of establishing a history to these things. Was your sense at the time that the theory was driving the experiments, or were the experiments driving the theory?
So, I think you’ve mischaracterized how I was acting there. I was not getting a sense of my talents. I was hanging on for dear life in graduate school.
Okay! [Laughs] I was hoping; I thought you had broken through the wall at this point.
Oh no, no, no. No. Oh, so I did reasonably well on my courses, which was shocking. Yeah, and I was also…Yeah. I was not a bad graduate student. I worked very hard. I think I objectively was a good graduate student, but I was not…I didn’t know why I was doing most of the things that I was doing. What happened that was surprising to me after I left is that I learned things. [Chuckles] It doesn’t feel like you’re learning things if you don’t know what the next step is that you’re supposed to do or if you’ve misunderstood why you’re doing the step that you’re doing. I was always in such a panic to make progress and to get the next thing done that I never really took time to think about what I was doing or why, so it’s a little bit surprising that I actually learned so much about analysis from Kevin because I learned a ton about how to do an analysis in that process, even though I felt like all I was doing was catching the next crumb dropped that you’re following. I was like, “Okay, I’ve got to figure this out! I’ve got to figure it out! Oh, I did the wrong thing, but let me fix it. Then this is the next thing, and this is the next thing,” you know. So, anyway, was theory driving experiment or was experiment driving theory? I would not have had that perspective.
Your world was way too small and panicked to answer this kind of a bigger question.
Yes! [Laughing] Absolutely! Absolutely!
I mean, I guess let me refine the question. Did you have a general sense that the theorists were theorizing the existence of these things and that was shaping the way the experiments were designed?
Or even that basic question—that’s not where your head’s at at this point.
I don’t think that’s where I was at. I really don’t. I think it’s hard to go back and understand, but I think I was deeply lost in lots of ways at that point in terms of the theory, and here’s an example. [Laughing] I actually told a Collider story about it. It was early in graduate school. It was before my first year of graduate school. I went out to Fermilab that summer, and Kevin asked me to make a plot and I made a plot. I knew—I was working with taus in a hadron collider—it was going to be a garbage plot. It was going to be just some kind of a blobby thing. I made the plot, and it was a beautiful, sharp peak and I didn’t understand what I’d done wrong because it wasn’t supposed to be like that. I was making a mass plot with taus, and taus aren’t supposed to give you a nice mass peak. I showed the plot to Kevin and he laughed. He said, “Oh, Sarah, that’s because electrons have faked your taus. Those are Z to ee events and that’s a beautiful Z mass peak. If you’d made that plot a long time ago, you’d have gotten a Nobel Prize.” I remember laughing and that was funny, and I learned something, that electrons fake tau identification, reconstruction. That was useful information, but the really revolutionary thing about that for me was I had to accept the fact that Z bosons were real. I realized that I had been working as an undergraduate and now I was going to graduate school in particle physics and I said I want to learn about the universe and all these things, right, but it never really occurred to me that these particles were real. It didn’t seem possible that these things were actually real because they had such crazy names. Like who knows what this math that I’m doing or this data I’m playing with on the laptop, how it’s actually connected to reality in any way? When I made the plot that had evidence of the Z boson when I hadn’t gone out looking for the Z boson, I was really forced to confront the fact that these particles that I was studying were real. So, that tells you something about my mindset at the time. [Laughter]
When did you know that you had enough to defend? What was that intellectual process like, or did Kevin just decide that for you also?
No. I think that we made progress in the analysis to the point where we had it ready for publication. There was an opportunity to teach locally that had popped up in Rochester, and so I knew that I was going to leave research because I thought, “I’m certainly not capable as a researcher, but I think I’ve learned some physics.” So, I was looking for teaching positions and there was an opportunity locally at a small Christian college where there was—
Meaning you’ve survived this far. You’ll be a teacher at a non-research university.
Exactly. Right. Yes, because I love to teach and I thought, “That will be a good path for me.” So, I talked to Kevin about the opening. I was in year five, I guess. The analysis was converging. I started graduate school in ’99 and I took that position in 2004 and then defended within the year. I was still…We hadn’t published and so there were still some details that had to be worked out, but I went and taught as an assistant professor for two years at Roberts Wesleyan College in upstate New York.
Teaching at a small Christian college, to back to our earlier conversation about bridging these divides, it’s almost too perfect.
What doesn’t make sense is how SLAC comes next because that is a very different turn of events.
Yeah! So, I had gotten married in graduate school to one of my classmates, and he was not finished as early I was finished, and so I took this position at Roberts. He actually was from Rochester, New York; his family was from there. I loved it at Roberts. I really did. It was crazy. I was teaching up to five courses a semester. I mean I was the only physics professor there, so I was doing all the labs. I used to go to Home Depot on my way to school and buy with my own money what we needed for labs, you know, but I loved it. It was a mission-driven place. You felt like you were part of a team.
Culturally, did you feel at home from your childhood? Did it have that same…Did it have a familiarity to it?
I could blend. I could blend and it was more conservative than my own family. There were chapels that were required for the students. I would go to the chapels. I presented at chapels. They asked us to incorporate religion and prayer, et cetera, into our classes. I didn’t go that far, and I made that clear that I wasn’t really comfortable being an authority in a religious way in front of my students.
What does that look like?
Lots of faculty there would start their courses with a prayer, and they would try to make connections as they came. I mean I think it’s different in some disciplines than others, right? In a discipline like physics, I think people typically would maybe start with a prayer with their classes.
But it wouldn’t necessarily go so far in a biology class to say, “Evolution is false”? It wouldn’t necessarily go that far?
Oh no, no, no. No, no, no. I mean, the faculty there were wonderful. No. There were no creationists there that I was aware of. That certainly wasn’t taught. There was a real integrity to the science that was being taught. My favorite people were actually the theologians and philosophers who were good, interesting, deep thinkers. I think what I really liked about Roberts was the sense of community that was there. The research institutions that I’m at now, there is a real sense that in order to make progress or in order to be taken seriously, you have to be loud. You have to complain. You have to throw a fit, you know. How do I get a raise? Show that somebody else is going to give me a raise and then you’ll give me a raise. At Roberts, it was “We’re all going to take a pay cut.” The faculty meetings, they would splurge once a year and we all went to a Chinese restaurant. We were working insane amounts, but we had good, close connections with the students, and it felt like there was a mission there that everyone was behind. It’s a lot easier to work really hard when you feel like you’re part of a team. I do the same at Yale. I feel like I’m a part of a team; I just have to be honest with the fact that I’m manufacturing that team sometimes, you know? The people are my friends. They don’t always know that they’re my friends, but that’s how I choose to do my work. That was easier at Roberts.
Outside other considerations, could you have made a long-term career at a place like Roberts Wesleyan?
I think so. I think my ambitions are tunable. I would be happy ruling the world, but I also read a lot of Tolkien when I was growing up, and this idea that…Are you familiar with Tolkien?
[Laughs] Galadriel passes the test. I feel like I could pass the test. You know what I mean? If I make a difference in a couple of people’s lives, then that’s a life that’s lived well. A bigger platform at a place like Yale—I think there is a little bit more responsibility associated with it. You can maybe have an impact on some more lives or maybe people who might have more influence in the world after you, but those lives aren’t necessarily…They’re not more valuable than the lives at Roberts. So yeah, I think I could have been fulfilled at Roberts long-term, but I’m happy where I am.
Maybe even subconsciously, if you were so aware of how devalued teaching was at a place like Harvard in terms of leading a purposeful life, you might not be teaching at a place like Harvard, but you can make a far greater impact on the lives of students than many Harvard professors have for any of their students, really.
Yeah. It’s a tricky thing in a field like particle physics where the influence of any one faculty member to the overall flow of what’s discovered is debatable, I guess, if you think about it. Anyway, I was very happy at Roberts, and I guess two things happened at Roberts that were important to me deciding to go to research. One was I was teaching physics that I had never been taught. I had to teach a bunch of engineering classes like statics and electric circuits for engineers, which I guess that’s engineering, but still…And I was teaching classical mechanics, quantum mechanics, all of these things.
This is a tiny faculty, and you have to wear many hats, basically.
Yeah, yeah, yeah. I was the only full-time physics faculty member, and we had a handful of majors who wanted to be teachers, you know? There was a good nursing program there, so it was mostly a support role for biology majors, chemistry majors, those things.
And to be clear, Sarah, you’re not doing research at all at this point. You’re not going to Fermilab. You’re not doing that stuff.
No. No. I went to Fermilab once or twice. I had to go back to defend my thesis, and I went back to Fermilab to give a talk on the analysis results. I remember going back to the lab and giving a talk and just being so comfortable communicating with people, just feeling like I had learned how to talk to people. I had learned how to look at people in a room when I was trying to communicate. I had just been working so hard in my teaching full-time to communicate with people that it was so refreshing to be in that Fermilab space, have something to say that I understood, and to have some tools and practice and confidence to try to communicate it. So, that was a really positive experience for me to go back, and I got good feedback after the talk that, wow, that was actually kind of a story that had an arc to it, you know? That was a useful presentation. So, that made me feel…[Laughs] That was unusual for me. Most of my Fermilab talks had really been boxing matches up to that point, so that was nice.
But in the practice of teaching so many classes with so little time to prepare, I really came to terms with the fact that I had learned a lot of physics and I was a good physicist. I don’t know when it had happened exactly, how it had happened, but that really had happened. Whatever wiring needed to happen in my brain had been changed or adjusted or expanded to the point where I could turn on that “Let’s approach this like a physicist,” you know? I could do that, so that was interesting for me [chuckles] because I thought that I was going there, at least to some extent, to hide from physics.
The other thing that happened was that my husband got a job at Bates as a visiting assistant professor. He graduated, and so we were living hundreds of miles apart and that was ridiculous because we’d always told each other, “We’re not going to get married and then live hundreds of miles apart,” but I was living in his old bedroom at his parents’ house for that year and he was off at Bates. We knew we needed to make some kind of a change if we wanted to live together, and so I told him, “Hey, I bet that I can get a post-doc in the Geneva area if you can get a post-doc in the Geneva area. You go first. See if there’s anything over there in condensed matter. If you manage that, I will get a post-doc in that area, and we can go and live together.” He really had energy for exploring Europe because he had done a Fulbright after undergraduate, and he’d traveled. He knew German, all these things, and so he wasn’t afraid or intimidated by Europe. So yeah, that was the scheme. If he could land a post-doc, I would then try to find one.
Did you have any concern that you lost any muscle memory in research?
I had forgotten my analysis, and that became very apparent in the first post-doc interview that I got. I went to Cornell, and as you can imagine, I’d had no time to prepare because I was teaching full-time at Roberts. So, I showed up and started talking about my analysis and had forgotten what the plots meant. They asked questions and I couldn’t answer any of them. I’m still partially wanting to hide under a table when I see certain people from Cornell even now, how many years later. But over the course of doing a couple of interviews, I remembered my analysis and had picked up some communication skills and managed to seem confident and put together enough so that…You know, I also learned how to…Well, I had always been pretty good as a bullshitter, but I learned how to say, “I don’t know the answer to that question.” That’s something that I learned at Roberts, right? You really shouldn’t bullshit in some contexts, and so I was comfortable saying, “I don’t know the answer to that,” but trying to answer where I did. So, then I started to remember my analysis over the course of the interviews and then had a couple job offers by the time I got to the end of that experience.
What happened next for you?
So, the SLAC job offer was the most interesting and the least computer code-oriented, though it was very computer code-oriented. But I had an offer from Johns Hopkins that was to rewrite some silicon reconstruction software that just seemed like, “Gosh, this is not going to be a good fit for me. I am going to really disappoint you people if you throw me at that.” [Chuckles] SLAC was a little bit more broad. They were just starting out their ATLAS group. I was their first post-doc, and so Steve, my husband, and I drove across the country together. He got a post-doc at Lausanne. We spent a month and a half in Menlo Park and then flew over to Geneva and lived there from 2006 to 2009.
What was the work you were involved in? What did you get to be a part of?
So beggars can’t be choosers. SLAC was late to join ATLAS and so basically they showed up and said, “What are your big problems?” This was 2006, so we weren’t yet at collisions, but the idea was, when beams would circulate in the machine the LHC would say, “All right. Stable beam has been achieved, and now it’s time for ATLAS to say go. Start taking data.”
But after we pressed “go” at ATLAS it was taking 45 minutes for the configuration information to make its way through all of the computer farm. So, part of the software that was used to select or reject events at the Large Hadron Collider, it had to be told what to do, right? It had no marching instructions. It was taking 45 minutes for people at the press. “Go, let’s take data,” and for all of those computers in the computing farm to say, “All right, we’re ready. Send us events. We’re ready to tell you, is this interesting; we’re going to keep it. Is it not interesting? We’re going to throw it away.” They needed that to be 45 seconds, and so I worked on the DAQ (data acquisition) database proxy server that basically farmed out all of this configuration information to this network of PCs by making copies of trees of the databases and populating it so that it was a faster start-up time.
Chronologically, how far advanced was ATLAS at this point?
ATLAS was in no way, shape, or form ready for data-taking, even though the LHC was arguably already eight years late, but it was very far along. I definitely felt like a newcomer. I felt like I was late to the experiment. It was within a couple of years of data and ATLAS was first imagined in the ’90s, I would say, early ’90s, so pieces were being installed. The control room where I did a lot of my work was a really fun place to be, all hands on deck. Yeah. It was a very fun time to be a post-doc there.
Who were some of the leading figures? Who was driving the decisions and the way that the collaboration was moving forward?
Peter Yenni and Fabiola Gianotti. Peter Yenni was still the spokesperson when I joined ATLAS. Fabiola was the deputy spokesperson. She became spokesperson a couple of years later. So, I would say they were in charge, and then David Francis and Chris Bee were the trigger and data acquisition team leaders, and so they were the people I worked with most closely. I love the triggers of experiments, you know? It’s such an interesting, complicated job, and philosophically, it’s so interesting to think about how you design a system that lets you discover something new when you don’t want to make assumptions about what that new thing might be, right? Just the whole idea of the trigger was so intriguing for me, and the fact that it can’t screw up. If you don’t trigger on an event, it’s lost and gone forever, right? So yeah, I’ve always loved triggers.
I wonder if at this point you don’t have that same panicked perspective where your world is so small that you don’t have time or the headspace to think about the interplay of theory and experimentation.
Well, I think at that point I probably would have still felt like a poseur asking about those kinds of things or thinking about those kinds of things, but the nice thing about that panic is that when you’re a post-doc, it’s pretty broad. I mean, I was panicked in so many different directions, right, that I got to learn a lot. So yeah, I learned a lot as a post-doc and continue to learn. That’s one of the best things about the job.
Obviously you had to play some degree of catch-up since you did lose some muscle memory, but from the life perspective angle, from being a dedicated teacher to undergraduates, from being older, I wonder in what ways your experience at a small teaching college may have actually been useful in this radically different environment in Europe.
Hugely helpful. Hugely helpful. Maybe not as helpful as when I went on the faculty job market where I think it really, really was a benefit, but yeah, hugely helpful just to navigate the…Well, here’s another thing that happened that was really important. When I got to Roberts, I was very dysfunctional organizationally. When something would happen, my immediate impulse was not productive, and this is in part because of the CDF environment.
I mean, my very first talk at CDF—I was just starting out before my first year as a graduate student. I remember I was on my second or third slide to the Tau Working Group when Anton stood up and said, “This talk is a waste of our time. You should not be giving this talk. You have nothing to share with us that is new or interesting.” Then somebody else in the group stood up and said, “Okay, come on. She’s just a graduate student. You should let her give the talk,” and Anton said, “No. This is important, valuable time for us. She needs to finish and do more work and have a better understanding of this before…” and they actually got into an extended argument about whether I should not give the talk or whether maybe it was a good enough experience for me as a graduate student so that I should just go ahead even though it was going to kind of waste their time and give the talk. That’s what the Tau Working Group was like on the ATLAS experiment, and Anton, this guy who later was a godfather on my analysis—he was one of the three people who was in charge of reviewing internally my analysis—he just thought if we’re not in a fighting match, if we’re not yelling at each other, we’re not caring, you know? He used to yell at us if we didn’t interrupt him with questions in the middle of his talks.
So, it was a crazy environment, and my advisor Kevin, if I was asked a question, there were times when he wouldn’t let people finish asking the question…It was just escalation, escalation, escalation. It was unbelievable.
I got to Roberts, and I’ll never forget. There was an early situation where a student sent an email that was inappropriate. It was unkind and it was inappropriate, and the computer science faculty member responded in such a gracious, generous, productive way. I thought, “This is going to be interesting. This is going to explode,” and when I saw the professor’s professional response, I realized I am entirely dysfunctional! My whole organizational framework is like what’s next, like you’re coming at me and I’m ready to swing.
So that break, I think, was very helpful because when I stepped in as the first SLAC post-doc at ATLAS, there was this big problem that had to be solved. People were talking about it, like, “How do we configure this? How do we speed this up?” But there were groups on site that were very hesitant about the newcomers, and so the politics of it were challenging to navigate. But I had learned how to deescalate. I had learned how to diffuse and how to work with people and some skills that I think were incredibly helpful. [Laughing] If I had gone straight from CDF to ATLAS, I would have been so much more bombastic and so much more problematic as a researcher. [Laughing] I think Roberts was really helpful for me to see how organizations can maybe be a little bit more productive than…Yeah.
Sarah, to give a sense of the size of the collaboration, you know, going all the way from Fabiola to you, what was the reporting structure? How many levels were there in between? Who would you report to and was there anyone under you, so to speak?
Yeah, it would depend. The whole thing is fairly democratic, or at least in the goal of it that any undergraduate who has an idea, or anyone can speak at any meeting…We’re all on a first-name basis. It’s not very formal on that front, and it was kind of like the Wild West on the trigger. Everybody was trying to get it to work. So, there were certainly reporting structures, but no, it felt just like all hands on deck. Let’s try to make this thing run. The management, people like Fabiola and Peter Yenni, knew so much about the details of the experiment, you know? You didn’t have to translate things to people who weren’t really in the loop or explain your work in ways to them. There were certainly reporting structures, but not in as formal a way as there are now. It didn’t feel at all stifling, and I wouldn’t have claimed anyone was reporting to me. I was certainly mentoring different Stanford undergraduates—yeah, undergraduates, graduate students mostly and undergraduates at the time as a post-doc—but I didn’t have people reporting to me in any structured way. It was just get stuff done, and as a post-doc, that was the deal. Something needed to happen. You had to try to get it done.
Perhaps you’ve alluded to this in your explanation of the democratic nature of the collaboration, but to what extent was your affiliation through SLAC significant in terms of your purview, the kinds of things you were working on, and the way that you may or may not have been representing SLAC’s—I don’t know if parochial is the right word, or specific interests in the collaboration?
Yeah. I think that it was an interesting time to be an American at CERN. That was much more on my mind than my SLAC affiliation, maybe. Yeah. I don’t know. I was very aware that there were people who were threatened and that SLAC was coming late and that our goal was to do some crap work and earn people’s trust. The thing about crap work at an experiment is that it’s usually the most fun work there is, you know? Like you’re in the details, and so I was just grateful for an excuse to make a difference. I was actually contributing. Yeah. I don’t know. I did my best.
This is also perhaps a far too broad international kind of question, but in some ways, being affiliated with SLAC but working at CERN was a very post-SSC reality. It really is the embodiment of the mantle of leadership in high energy physics transferring from the United States to Europe. Were these things on your mind at that time, or that’s all too broadly conceived at this point?
The thing that was foremost on my mind was that I didn’t want being an American to slow me down, or I didn’t want people to distrust me because I was an American. My choice to go with an ATLAS institution was very purposeful at that point because I had learned that US CMS had its own structure of all of the physics groups. There was the Higgs group, the SUSY group, all of those things within US CMS. They had like a parallel structure, and I thought, “I am not going to be part of that. That sounds dangerous to me. That sounds like…Americans are such a big component of that collaboration, 40%. They have their own parallel structure. I’m not going to wade into that. I’m not interested in defending the US’s interests on that front.” I very much liked the SLAC newcomer; you know, “Let’s prove our worth here.” The fact that the US was 30% of the ATLAS experiment—it was a smaller component. We were less of a target. I thought, “I’m not going to have to worry as much about being an American and people not trusting me, how I can operate here,” because I didn’t have any designs that were dangerous. I just wanted to do good work and contribute.
Was the post-doc a set term? Was it somewhat related to your decision on when you were ready to come back to the States?
Yeah, I think it was maybe even yearly renewable. People tended to be post-docs for two to five years. I didn’t feel any existential crises over the end of my post-doc term. It would have gotten uncomfortable if I had stayed that much longer probably, or too many more years. No. I definitely feel like I applied for faculty jobs early in the course of the post-doc. I could have stayed for another year or two and it wouldn’t have been uncomfortable.
Given the ambitions of what ATLAS was after, how much of a success was the collaboration by the time you left? What do you feel like your contributions were to that mission?
Well, I’m still on ATLAS, but you mean my post-doc time.
When you formally left the post-doc.
I don’t know. It’s complicated. I think that we achieved our goals within the first year or two, the very specific thing that I was hired to work on, and then there were other things to do to move from putting out fires to more commissioning preparation things. But yeah, when I moved to be a faculty member on ATLAS, my physics interests and my physics push was almost identical, and I kept working on the tau trigger, the trigger for the experiment, through something that I had started as a post-doc. So, it didn’t even feel like that much of a shift in terms of the areas where I was working. It was a continuation of what I was doing.
Were you on the job market? Were you thinking about your next opportunity while you were still in Europe, or you kind of came home and figured out your next step then?
Oh, no. I moved home to take the job. I was on the market from Europe. I was on the job market in 2008, and I had a faculty interview at that point. I didn’t get that job, and then the next year I had a couple of interviews and had a couple of offers and at that point in 2009 took a position.
The running joke, of course, is that the job market is never good, but you’re applying right in the middle of the financial crash of 2008.
Yeah, it was tragic.
Was that tangible at that point that it was even worse that year than it otherwise would have been?
I think everybody makes excuses for why their year was a particularly bad year, yeah. It felt--
[Laughs] You had a pretty good excuse, though!
Yeah, yeah. Yeah. It felt…I was stressed. I could pretend that I wasn’t stressed, but I was really stressed about my job at that point. I had the sense that because I was so happy at Roberts, my identity is not going to be hurt that deeply if this doesn’t work. There are other things I can do, you know? But the momentum of it was there, and I was working very hard as a post-doc. Things were going well, and so I definitely wanted a faculty position badly at that point.
But how wide did you cast your net?
Everywhere in the US.
But most people…I mean, with your trajectory and what you had accomplished so far, most people with your CV up to this point would never have taught at a place like Roberts Wesleyan and would have never even considered it as a place to apply to. So were you prepared for that kind of a job again, if a place like Yale did not come available, for example?
So that’s complicated. I think that those kinds of positions are hard for people in particle physics because even Roberts wanted me to do research with undergraduates, and I had a five-course load there, right? But even Roberts wanted you to do some level of research with undergraduates.
The admission standards at Roberts were basically nonexistent. We just took people. But if you go to a liberal arts college and you’re a physics faculty member, an experimentalist has to have a program. You have to have research for people. So, I was a terrible candidate for those places for a couple of reasons. One, because I went to Harvard and who wants to hire somebody who went to Harvard at a school that’s Roberts caliber?
Meaning that you wouldn’t even be able to relate to that place or its students.
Exactly. I got a teaching award from Roberts when I was there, and I could have gotten letters from there, so I felt a little bit more bulletproof on that front, that in spite of my trajectory, maybe I could be hired anywhere to teach physics. But the research component is a real issue and it’s hard for people in particle physics to teach at liberal arts colleges that don’t have graduate programs. How do you make a case for it? And analysis at ATLAS requires so many meetings every week. You can’t keep up with it, and the funding streams aren’t set up for it. It’s really a hard thing to do. Some people manage, but…And the other kinds of research in particle physics were less interesting to me and I didn’t have expertise in them. So yeah, for me, if I wanted to keep teaching, it was either going to be high school that would require me to go back and do a bunch of certifications and…That would have been hard. I looked into it a little bit. Or it would have been a research institution faculty position.
Did you look at national labs?
No. [Laughs] No. I did not look at national labs. I love national labs, but I think my reason for being…It’s ridiculous to say it, but mentoring students, teaching students—I think I could not make it in a research environment if I were coding…It would not be as well-matched to my abilities. I did not look at national labs.
Did you harbor hopes that if you returned to a place like Roberts Wesleyan that you’d maintain affiliation with collaborations like ATLAS, or that would not be possible?
I don’t think that would be possible. That would be--
So, at that point you’d really be turning your back on that whole enterprise.
I think so. Yeah, yeah. And I love the people. I love the work. I love the experiment, you know? At that point, I had been acting much more as an independent player in it and thought, “I can make this a go.” There were measurements that I want to do, you know? So yeah. That would have been a loss for me, but I think I could have been happy and still could be in lots of different things.
How did Yale come together?
Really, it was the two-body opportunity, as we like to say. When Steve took his post-doc, he switched from being an experimentalist to being a theorist, so he wasn’t ready for the faculty job market when I was. We had offers from University of Michigan and from Yale. I mean, I had a weird CV, as you’ve pointed out. I think some people were really skeptical of it, but nevertheless, I had offers from Michigan and Yale. Michigan told us flat out, “We’re not going to have anything special for Steve, but we won’t hold it against him that he’s your husband.” Yale told us, “We’ll hold it against him that he’s your husband,” meaning his chances for advancing or getting a faculty position are low, “but we do have a position; we can give him a research position.” That seemed like a safer bet at the time, so he came to Yale and took a post-doc—and come on, it’s a great place, right? They talk the talk about teaching and caring about teaching. I didn’t believe them, but I have had lots of fun teaching opportunities here, so I think there was actually some truth to it. Yeah, it was…and it’s closer to my family. It’s a dream job for me. I never would have expected it, and when Melissa found out--
Yeah, I was just going to ask! [Laughter]
I ran into her in the CERN cafeteria and told her that I had gotten a faculty position at Yale, and I think she laughed and said, “It just goes to show that you never can tell.” [Laughter] That was Melissa’s reaction. That tells you how strong a student I was at Harvard.
Was your guard up because of what Melissa had told you earlier? I mean, did you have a sense of what you were getting yourself involved in?
In what way?
In just the culture of promotion, the culture of how Yale historically had treated its women professors, all of the above.
Oh, at that point, I had had plenty of experience navigating challenges like that. I read the Chronicle of Higher Education religiously. I knew more about tenure and the pitfalls of tenure than anyone else who was on the job market at that point, man. I was bulletproof because I thought I had to be because I had such a weird CV. So no, I was armed. I was strategic. I’d had, as a post-doc, a plan. Every year I had goals. I worked like a maniac. Yeah, I was ready.
Given that you were prepared for two very different lives, the small college life or Yale, so to speak, and you were obviously aware of these differences and what opportunities each would provide, so given that you’re at a place like Yale, given that ongoing collaboration with ATLAS would very much be a possibility, how did you operationalize that? How did you put that to good effect? In other words, meaning that it was an opportunity that you may not have had, for better or worse, but you did have this opportunity that so many other people, your peers that did not have the CV never would have even thought of in those terms.
Mm-hmm [yes], yeah. I like to think that there are many lives that I would find interesting. It was just evidence for me that that’s true. And when I’m interacting with students and different people who don’t have careers set, I think it makes a difference that I feel that there’s not just one path that is interesting and fulfilling out there. I think that my interactions with people at Roberts who I respected so deeply made me realize that the prestige and the elitism that we have associated with our various universities is just ridiculous. I mean, it’s ridiculous to think that we’ve got the top minds clustered in just a few places. It’s absurd, you know?
I also interacted with lots of students at Roberts who taught me about the privilege that’s associated with how I grew up and my relationship with education. I have a lot of colleagues here who are frustrated with students—and I feel this frustration at times too—with students who want to know what their job is going to be or how this will help them…You know, what can I do if I do physics? What does it do for me, those kinds of things. Or maybe a student who comes with a more transactional relationship with education. I remember at Roberts thinking that I was going to tell my students that they should follow their passions. They should do what they loved, but some of those students had to support their families, and interacting with first-generation students or students who, like me, didn’t have a strong preparation in math or science, it makes me recognize that we have wonderful faculty here at Yale. We have wonderful students, but those kinds of people, those kinds of students are all over the country, and perhaps we shouldn’t take ourselves all that seriously here. So, how do I operationalize? I guess that’s one thing that it gave me a sense of the breadth of the talent that’s out there, and that’s made a difference in terms of how I advise students and how I think about what our responsibilities are, I guess.
What were the expectations in terms of teaching load, research, and just your general sense, reading the writing on the wall—what would tenure expectations look like when the clock starts?
Yeah. I mean I think as much as Yale does appreciate teaching, my tenure was going to rest on my research and so…Yeah. That was very clear. It was research, research, research, so the teaching that I do—I love it and I take it seriously, but it’s not my main focus. It’s really about the research. That was very clear.
Clear like crystal clear? They said this in black and white, or you just got the sense that “This is just how things are here”?
Clear that when I got a teaching award before getting tenure at Yale, one of my good mentors said, “This is really going to hurt you.”
[Laughing] Oh, gosh!
But it was certainly not written into the expectations. The idea is that maybe it hurts you in the department. It’s not going to hurt you at the university level, but it’s really going to hurt you at the department level.
Did you have a Melissa Franklin as a senior faculty, anybody that you looked at—obviously not as a mentor; you’re a professor yourself at this point, but just somebody who you would turn to for broader perspective than you might have had yourself?
Oh, I certainly had mentors. I mean, I think you always need to have mentors, and Meg Urry was definitely in that category. Bonnie Fleming and Helen Caines were also more senior women to me at that point. Jo Handelsman was like that for me a bit. She was from University of Wisconsin. She left Yale to work at OSTP when Obama was elected and never came back; she went to Wisconsin. But she was behind the Scientific Teaching Center at Yale. She was the one who was concerned about the fact that I had won a teaching award [laughs] and lamented how it might damage me.
You know, I co-wrote a book on physics and dance, which is an interesting use of your time, and there was a senior female faculty member who told me, “Do not publish this book before tenure. Make sure that the book comes out after tenure. Please, for the love of God and all things holy, put that off.” [Chuckles]
So, I definitely had mentors who were useful helping me navigate things. Yeah. I felt, okay, my research has to be bulletproof so that all of these other interests that I have, which really do extend into the humanities and the arts—they’re hobbies, I guess, and if I can put something on my CV, great. I’ll try to make it that all the fun things I want to do I can put on my CV in some context, and so be it if it hurts me in some camps. I have to be bulletproof enough in my research that I can jump over the hurdles regardless of people’s concerns.
I was going to ask later on, but you mentioned it now. Where did your interest in physics and dance come from? What was the origin story of this?
I’m just generally curious, but I am also tall and thin, and so when somebody reached out to the physics department for a potential course on physics and dance, there was a general assumption that I must be a dancer.
The physics and dance course was an idea of the Dean of Science Education. He contacted Meg. Meg put out a call and I thought, “That’s going to be a great way to teach people physics.” I had a bunch of assumptions about what that might look like that were immediately destroyed by my formidable colleague from the dance studies, Emily Coates, who I co-taught that course with. Yeah, that was a lot of fun. Continues to be fun. We still plot together any chance we get.
When you say that you needed your research to be bulletproof, to what extent does that affect the kind of research that you wanted to do? In other words, there’s a perfect world in which you’re going to pursue the questions that are most intellectually important to you, and then there’s the world that you have to impress the right people at the right time to achieve tenure. Is that a Venn diagram that has two circles and a shaded area or not?
Well, I think that life is far too short to worry too much about that Venn diagram, so the best that I could do was make it so that my research that I cared about was completed, right? That’s what I mean by that. I had my own interests and things that I want to do, and I just needed to make sure that I had enough publications and that I gave enough talks.
Completed meaning what? I mean, for example, like ATLAS, ATLAS goes on, so what does it even mean in your field for something to be completed?
Oh! Well, there’s the Run 1 hunt for Higgs to tau tau, right, using that dataset. That has to be published. That has to make it. The ideas that I want to have in there have to make it. It’s no small feat to emerge from the ATLAS collaboration holding a paper of stuff that you’ve worked on. That probably seems crazy, but it’s true. It’s a massive effort to carry something across the finish line. I mean the number of bottles of wine and thousands of lines of comments that I made it through for some of these papers just to cross all of the T’s, dot all of the I’s—I mean, the reality is you need stamina and determination beyond all else. So, I had to bring things to conclusion. I had to get things published. I had to push things across the finish line.
In terms of your overall research agenda, just broadly conceived, is this largely a continuation of the post-doc, or by dint of being a professor, are you taking on new projects that you otherwise would not have?
Oh, okay. Yes, that’s a good question, and that brings up some question that tenure gave me. I am still working on taus, which is a thread you can draw all the way back to when I was a graduate student. That’s mostly because taus are so hard that it’s crazy people who work in them, fun people, people willing to take risks. So that’s a thread you can draw all the way through, but when I started at Yale, I had four graduate students and I knew that I needed to have some breadth in terms of my research, so I did go hunting for different things in different groups. You know, oh, it would be fun to do a search, and ah, that’s a measurement that I want to do, and then nm-mmm [no], let’s do this. So I would say topic-wise, I’m very far removed from what I did as a graduate student because I really tried to branch out in all these different areas, but I started working on the tau trigger as a post-doc. It wasn’t what I was hired to do; that was sort of an orthogonal thing. They say 50% we own and then 50% of your time is yours, right? So I started that as a post-doc on my own and continued that. But yeah, I don’t think you can draw that many direct lines through.
So, you took graduate students right away
Yes. Yes. Yes, I had money! I mean, you show up with a start-up, and yes, yes. Terrified. Took on graduate students and we all survived the experience.
[Laughs] Thinking to your relationship with Kevin and what a hands-on advisor he was, what did you learn from that relationship and how did you put it to your own use when you were on the other side of that relationship?
Yeah. I learned…Well, I am there as much as I can be when my students are giving talks because as intense as it was the way Kevin would treat those interactions, I always appreciated and knew that he had my back and he wouldn’t leave me hanging. If people got mean, he would be there, and people do sometimes get mean, not on ATLAS very much, but on Mu2e, which is the other experiment that I’m on that I have students give presentations on. That’s at Fermilab. No coincidence, maybe, that it has more mean people [laughing]—or people willing to ask questions that push students, questions that students perceive as mean. I guess that’s the best way to phrase it because I think people are driven by their curiosity and just don’t have many filters sometimes. So, that’s something that I do that I appreciated from Kevin, though I try to give students space to answer if they know the answer. I don’t always do that successfully.
I think that one thing that I learned (let me just say as a graduate student) that was so jarring for me is you would be in a faculty member’s office, and they would ask you all of these questions. You’d be there for some time, and then they would panic and realize they had so many things to do and you just needed to leave that instant. You would run out of the room, and you would think, “Huh. I swear I wasn’t the one who was extending that conversation, but I feel like I just took up that person’s time, even though I feel like they thought that that conversation needed to happen.”
So, I try, when I’m interacting with my students, to never put the burden of my schedule on them because I am ridiculously overcommitted to the point where it’s truly ridiculous because I have so many things that I’m interested in and excited about, and it’s really not their fault. [Laughs] So, that’s something that I try to avoid doing with my students, is any emotional burdens of the choices that I’ve made, I feel like that’s on me, you know. I can’t panic on them halfway through this conversation if I’ve asked them for this conversation.
But I think another thing that I try to do with my students is…yeah, think through things that maybe I didn’t do. You know, how do we give them time to think? How do you help them see what they’ve learned? I know how hard it is to be in graduate school. It’s just crushing. It’s crushing. You feel…You’re embarrassed all the time. I mean, that’s how it was for me, and I think that’s how it is for a lot of people. It’s just so humiliating, and it has to be that way to some extent because you have to leave understanding the full landscape of what you don’t know because it’s really dangerous if you don’t understand the full landscape of your ignorance, you know. You never can make a claim about anything that you think is new if you haven’t mapped out what’s known and what isn’t known. So, part of that is necessary, but it’s crushing, and so I try to be very supportive of them and encourage all little victories and make sure that we acknowledge everything that we learn together. And my brain, I rewired it to some extent for physics, but I still have to…I mean, I forget things and have to relearn things every single time, and so we’re all in it together to some extent…hopefully not to the point where they feel like it’s a rudderless ship, you know? There is a plan, but in terms of learning the details, I’m very much in it together with them. I’m not Kevin. I don’t have the ability to see eight steps in advance, which I think is maybe helpful for my students because we can work through, you know, how do we chart this path together? I think this is the next step for these reasons. Yeah. So, that’s a benefit in some ways, to not see so far ahead.
When your time came up for tenure, what did you learn about that process that you never would know learning about it from the outside?
Well, like I said, I think that I was very well-informed. I have read every post on tenure that was on the internet in the last 20 years…
So, with tenure I learned that it’s the external things that can matter. It doesn’t mean the same thing for everyone. Right when I got tenure Yale informed my husband that he would lose his position. So, the point of getting tenure for the two of us was a really awful time because it coincided with him losing that position and having to renegotiate and looking for other jobs. I mean, it was a mess. It was really hard.
Were you thinking about leaving Yale?
Oh, yeah. Absolutely. We almost did. Yeah, we came quite close to it. I’m barred from going into too many details. [Laughs] I had to sign all kinds of confidentiality things when we took our current contracts, but yes. I have a lot of backup plans, but still, it was hard to think about. And you also feel a burden of “So many people helped me get where I am,” you know, that you don’t want to disappoint people. That would have been crushing to have to walk away from an Ivy League tenured position. How many women do we have who have tenure in physics departments, you know? It just would have felt really…Yeah, it would have been really hard.
Did you have a sense when you accepted the job what the culture of promoting from within was at Yale? In other words, at a place like Harvard or Stanford, everyone knows assistant professors are like…You know, they’re glorified post-docs and the trajectory is you should expect not to get tenure. A place like Chicago is the opposite, right, that if you get that assistant professorship, we’re going to support you with the expectation that we’re rooting for you to get tenure. Where was Yale on that from your perspective?
Well, Yale had just transitioned a couple of years before I joined. It was 2007 when they had new standards adopted, right? I knew that Yale used to have a letter that went out when people were going up for tenure that said, “Who’s the best person in the world?” and didn’t even mention your name, right? So, letters would come back and suggest people who they maybe should go hire. I knew that Yale used to have a system where they counted assistant professors as half slots, so not everyone even had the option to go up for tenure, but that changed in 2007. So, if an assistant professor was hired, it was a full slot and there was a potential for you to go up for tenure. So, I understood that the shift had happened. I wasn’t sure how it worked. There weren’t many examples of people going through the process when I joined, so it was a little bit of trust and faith that there was an option, but at the same time, if I don’t get tenure, I don’t get tenure. That was a very real possibility.
To the extent that you’re able to talk about this (and I appreciate these are sensitive and there are family considerations and all the rest), did you make it known that you were thinking about leaving Yale and that prompted a response from Yale to make it so that they could solve the two-body problem into a two-body opportunity?
Yes. That is a nice, clean way of putting it. It was much more complicated than that, but yes, that is basically how things went. You don’t let them know that you’re considering leaving. That has to be a much more forceful statement, right? That has to be showing them that “There are opportunities” kind of statement. And that’s one of my frustrations. If I could design the university system, I would not design it like this. There is a concern that maybe Yale, and the physics department in particular, that maybe we need to convince people that we are capable of denying someone tenure, you know? There are people who have that mindset, like, “Wait. You guys have tenured a lot of people coming through. Are you capable of denying people?” I just feel like the denial of tenure is a failure, for the most part…I mean, there can be exceptions where people decide that’s not their life and they don’t want to pursue this, but for the most part, that’s a negative reflection of the mentoring that people have received and the opportunities they’ve been giving and how much care people are giving junior faculty members. It’s an indictment of the department and the institution as much as it is of the person, in my mind, and not everybody thinks that way at Yale, I understand.
Sarah, as you say, life is too short and you can’t only do research that you think is what’s going to get you tenure, and yet the reality of it is that it’s an inescapable fact that these two things are connected. With that in mind, when you did get tenure, did your research agenda change at all? Did you do things that were perhaps more adventurous or more out there than you otherwise wouldn’t?
No. I actually started that before I got tenure, so my physics and dance collaboration, physics in music course that I developed and have taught and…I joined the Mu2e collaboration. A lot of people thought that was a crazy thing to do, to divide yourself, but all of that was before tenure. So, I’ve managed to…yeah. I don’t think it did. The one thing that maybe I feel more comfortable doing now is I hope to never have four graduate students again, but I think that’s much more learning how well I can mentor a group.
Meaning that’s too many.
Meaning it’s too many? Four is too many?
It’s too many. Yeah, yeah. I mean, in a field like mine, or in a life like mine, if I had two post-docs, I could maybe have four graduate students, but I would not know what physics those students were doing at the level that I want to know the physics that my students are doing, right, because that’s my research. [Chuckles] That’s our group research. Yeah. So that’s something that I don’t feel pressured to have a big group now, for sure, which is convenient given the state of funding in my field.
What is the magic number for you for graduate students?
I think it’s two, maybe three in the transition times when someone is graduating.
Tell me a little bit about how you put your lab together from inception to where it is now in terms of the funding, in terms of the instrumentation, in terms of the collaboration among your peers within and beyond Yale.
Well, I am sadly…It’s ridiculous to say it because I chair the US ATLAS Institutional Board but feel very much not in the club. I don’t have a hardware program. I’ve never gotten funding for that. I’ve tried with no luck. So, I’m only half-physicist by some people’s measures, right? I don’t have a lab at Yale. I’ve been offered space if I need it, but it’s ridiculous for me from an environmental perspective to buy my own GPUs and the cooling for them if I can just use, you know…I can get access to machines in other places. The work that we’re doing on Mu2e includes a test stand. That’s at Fermilab. The trigger data acquisition stuff that we do at CERN is at CERN, so I don’t have a physical lab onsite at Yale.
So, the Demers Lab is almost conceptual and has no physicality to it.
Yes! And it’s a great conception. We have…I hire students or take on students, and basically, as long as people are kind…You know, it’s like what Melissa’s group was. I remember when I interviewed for a position in her lab, she asked me two questions: “Do you drop things?” and “Are you nice?” and that was it and I had a job. She didn’t care what my grades were, and for it to keep working I had to…For me to stay employed I had to work. I had to be curious. I think that it’s not that I just had to be nice, but that is my primary question when I’m thinking about students and post-docs. You know, are we going to be supportive of each other? Because this is hard enough without people being mean. There’s just no space for it.
Sarah, let’s return to these bigger questions because I know chronologically you’ve broken through the wall at this point, except you haven’t really situated it in any dramatic story or event or experience. So, you have broken through the wall. Now when did that happen roughly?
So, the physics wall…There are so many walls you could be talking about. The physics wall was when I was teaching it at Roberts when I realized that, oh, I know this to some level. I would say the research wall is chipped away at every day when I…I’ve effectively mentored a number of graduate students through to getting a PhD. I know what a thesis has to contain. When I look at a plot, I can see where there are problems and what’s lurking behind it. So, I guess that’s just been a process of learning that I understand how to construct an analysis and how to mentor somebody through it.
The bigger picture questions about what the work means, in some ways you have access to that more by realizing that no one knows everything, you know? I’m never going to be able to comment on the relationship between theory and experiment with a crystal-clear understanding of everything that theory and experiment encompass. That’s not going to be the case for me ever or for anyone else, right? So, I think that that, realizing that by interacting more with people who are at the top of these various fields, realizing that they’re human, that there are things that they’re missing, it makes the stakes change a little bit in terms of engaging in those kinds of conversations or thinking about them.
But I would say that at this point, it’s the security that I have that I have a job and that the confidence to just be honest with people, that when I’m interacting with theorists, I can tell them that I don’t know things, and sometimes that’s mortifying for them, and they typically recover. There are things that I do know, you know, and that helps, but yeah, I guess that you just at some point feel that you have permission to be in a space and it would be a waste to not use the fact that you’re in that space to try to learn. In those kinds of spaces, when we’re thinking about the frontiers of knowledge maybe, I’m not interacting in those spaces with the assumption that I’m going to cause a breakthrough, but I’m also not interacting with the assumption that I’m a waste of space. It may be that someone else is going to have a breakthrough, but I’m part of the conversation and maybe have insight to share that will help steer whatever brains need to be involved to making progress. I understand enough about the experiment to know what needs to happen for the experiment to function. I was just elected the Data Preparation convener for ATLAS, so heading into Run 3 I’m going to be making sure that we’re recording our data, that we can measure luminosity, that we know where the beam spot is. It’s a lot of stuff I don’t know, so it’s going to be right back to where I was as a student and a post-doc, right, but I feel like that’s where I live, in lots of panic in lots of directions, but so much opportunity to learn, and working hard and certainly not wasting the space.
Yeah, yeah. Given that you remain…I’ve been waiting to ask this question, and I’m getting the sense now that the answer is not forthcoming just in terms of your perspective and the way that you see yourself, but the bigger questions, right? So, let’s get beyond the theory/experimentation binary and talk more about your field and the goals that are happening particularly with you as part of the conversation and where this conversation is happening. So, let’s talk about physics beyond the Standard Model. Where are we today? Where are the exciting opportunities where we know there’s more beyond the Standard Model, and yet the Standard Model is very, very resistant to being challenged? Where do things stand now?
That’s a huge question.
I mean as it relates to, again, from your perspective, speaking on your being part of that conversation, your recognizing that fundamental breakthrough happens in collaborations.
Right. Sometimes it feels almost like we have an existential threat right now, right? I think you’re right. The Standard Model has proved to be remarkably resilient. It’s a little bit scary. I convened the Upgrade Physics Group on ATLAS for two years, and so we were looking at the reach that we have with the High-Luminosity LHC, and one of the things that’s exciting in thinking about the Large Hadron Collider over the next decade is some of the planned searches…And the searches that I’m the most excited about are ones that are motivated by, oh, what could be interesting about the third generation, which is so different from the first two.
What are the hints that we have right now in moving past the Standard Model? We have a category of aesthetic kinds of hints and we have other kinds of hints where the issue is that we have observations that do not match our predictions. The aesthetic kinds of hints are interesting. They’ve pushed us toward supersymmetry, and maybe you could argue that that’s made us as a field be a little bit more humble given that we haven’t found evidence for it, right? But the question of the Higgs mass I think is legitimate regardless of your aesthetics perspective, the challenge of the stability of the universe given the mass of the Higgs that we have. The question of matter-antimatter asymmetry is a question that goes way beyond aesthetics. It’s not just us as humans trying to force a model on nature that may or may not work… There’s a legitimate problem there that’s underneath that. I feel like the LHC has access to potentially help with both aesthetic and non-aesthetic kinds of questions.
I joined the Mu2e experiment because I worry that the reach of the LHC for direct production of physics beyond the Standard Model just might not be sufficient, in spite of the fact that we have another decade of data, and like I said, I was Upgrade Physics convener on ATLAS. I spent a lot of time looking at what potential we have for discovery and it’s there. There still is potential. There’s lots that we could see even without hints at this point. But Mu2e looks for new physics with indirect detection and has access to much, much higher mass scales. In some ways, the experiment is horrifically matched with my taste, meaning it’s very contrived. So Mu2e will be sensitive to leptoquarks of this flavor, supersymmetry of this flavor, composite Higgs of this flavor. It’s all ideas that people have written down with predictions that we can test, and what right do we have to think that any of those particular predictions are correct, right? So, it’s extremely broadly physics motivated, assuming we’ve already thought of the solution. That’s Mu2e. But at least it extends out to broader, higher energies than we have access to at the Large Hadron Collider. I love the LHC and the idea of being agnostic about what’s being produced. These protons colliding together gives you energy; we just wait and see what nature delivers. I understand that we’re kidding ourselves if we think that we have designed a fully agnostic experiment. I work in the trigger. You have to know what you’re looking for in order to find it to some extent, but still—
What do you mean, agnostic experiment? What does that mean?
Oh! Meaning that it’s an experiment that has a reach beyond what you may have imagined. You know, you’re looking for physics beyond the Standard Model, but what assumptions do you have to make about what that physics is in order to find it? The ATLAS experiment, in theory, by just colliding protons has access to any physics beyond the Standard Model that’s created with that energy, right? Nature gets to choose what’s made out of that energy, but we have to have designed an experiment that lets us see it.
So, we’re kidding ourselves to think that ATLAS is fully agnostic to the nature of the physics beyond the Standard Model. I guess that’s what I mean.
And it’s also wedded to the theoretical assertion that there is physics beyond the Standard Model.
Absolutely, and that’s one that you die on the hill for, right, because either there’s…Yeah. We have an incomplete description of nature, and we can either stop trying to interact with nature in a productive way or we can keep going, trying to have a better description of nature. I think that the idea that there’s nothing beyond the Standard Model for us to find—well then, okay. I think…I don’t know. I think that it’s very human for us to try to understand more about nature, and I’m not ready, certainly not ready, given how well the Standard Model behaves. I mean, in some ways you could say that’s evidence that there’s hope for us as a species to make progress here, right? Right. I think you don’t throw the field out right now. But it does feel like a tenuous time. You know, we’ve got a landscape of inquiry with the direct production at the Large Hadron Collider. We’ve got tons of diverse experiments like Mu2e that are looking for physics beyond the Standard Model in indirect ways. The question is what’s going to happen next?
If I could make one thing magically happen in the field, it would be progress on magnets and accelerator technology so that the political will that’s needed for the next steps is a little bit less daunting, you know, so that we can keep exploring the energy frontier of direct detection within the budgets. Yeah, that…It feels tenuous right now. Meg hates sports analogies, but I love them. It feels like we’re carrying the football, you know? We just can’t drop it. We have to keep moving forward somehow, even though I don’t know what the next machine is that we should build. I don’t know how we’re going to convince ourselves that we have a strong enough physics case for the next machine. I don’t know how this is all going to come together. So, it’s an exciting time. It’s a terrifying time, but yeah, we have an obligation to get everything that we can out of the data that we have and make sure that we can build the next thing that we need as cheaply as possible so that we have a shot at it.
Sarah, on the question of agnosticism, it’s inherently an unscientific question because the answer is not based in observation and analysis, but still, when you ask a cosmologist or a string theorist about the possibilities of a multiverse, it’s inherently a faith-based answer because we just don’t know. For you, what does it tell you that LHC and CERN have not seen anything beyond the Higgs? What does that tell you, even philosophically, and how might it serve as a motivator scientifically?
Well, I was never a SUSY person. I think it tells us something organizationally. You know, it’s interesting. Look at the ATLAS experiment. We had a dedicated supersymmetry group that was the biggest group. It was the most exciting group that lots of people joined. What right did we have to think that supersymmetry was the theory, right? What led us there? It’s interesting that that was such a vibrant, big group, and we didn’t see it and we haven’t seen anything that takes its place. But yeah, I don’t know how surprised we really get to be at that, to be honest. My read of the history of particle physics is surprise after surprise and mystery after mystery and huge gaps like between the bottom quark and the top quark masses. I mean, where does that come from, right? And decades-long hunts for the Higgs boson. So I don’t think we get to be uniquely surprised by not finding something in one of our designed experiments that’s limited by what we can afford based on our current magnet technology and money to dig a tunnel.
I think that it’s a mistake to forget about the discovery of the Higgs when we think about what we’ve learned from the LHC, and I also think that the work that’s been done carving out different phase spaces of potential new physics is incredibly productive. I think we’ve given theorists a ton to chew on, right? Yeah. So, what does it tell us? Well, it tells us that we are still in the game, that we’re not done. Nobody thought that we’d be done. Maybe we thought we’d be a little bit further along, but I don’t think that we get to be too surprised, and maybe that’s partly my ignorance talking as an experimentalist, right? Theorists had good motivation for being convinced that we were going to see things, but they were wrong.
[Laughs] Sarah, one of the major narrative through-lines of physics in the past 30 years has been the transition of so many particle physicists into astrophysics and cosmology, and what we’re seeing, especially in the past 10 or 15 years, is a lot of that knowledge coming back to benefit particle physics. I wonder if you can talk generally about how the work that you’re a part of might be relevant to questions that are of as big of a question mark as dark matter, dark energy, incorporating gravity into the Standard Model, these kinds of things. Where do you see your work, ATLAS, your other collaborations, as they have import in cosmology and astrophysics?
Yeah. Well, the LHC plays a really important role in that because we could actually produce dark matter in our experiments, and if we produce dark matter, we have some shot at seeing it because of conservation of momentum. [Laughs] I go to the dark matter talks and think, “Wow. What a hard problem,” right, “because, oh, I built a very, very sensitive detector. I didn’t see something, but maybe it’s because I used germanium and maybe dark matter doesn’t interact with germanium. Maybe I should try a different material,” right? Oh my gosh! The landscape of those questions is…I mean, that’s really a hard problem! At least at the LHC we get to celebrate by seeing nothing. There are ways for us to note the absence of things at the LHC, so that’s really important for dark matter. We can try to make it, and by not finding it, we’ve ruled out some regions of parameter space. Some theories of dark matter are dead because we haven’t produced it.
This is a great opportunity. These interviews go out to a pretty broad audience, and I know already the question is how the heck do you make dark matter if you don’t even know what it is? Can you explain the science there a little bit?
Oh! I should have found out more who the audience for these things was. That’s the first thing that I’m going to say. That’s very interesting! I didn’t think there was--
Let’s put it this way. It includes high school students and people who love listening to physics podcasts. So, everyone under the sun.
Oh! I’m sorry! I should have done a much better job trying to make sense.
No, no, no, no, no! You’ve been…No, no. I only ask now because this is the first time where you said something where this might not track with some of our readers.
Right. So, at the Large Hadron Collider, all we’re doing is taking energy of motion and making that available for potential mass. We collide protons at very, very high speeds, and inside of those collisions there is energy that’s released, and that energy can go toward lots of different things. We have an equivalence principle—well, you have to be careful with it, but you can make extremely heavy particles using this energy. So, we get to explore particles that are more massive than we’ve been able to explore before because we’re at higher energies at the Large Hadron Collider.
So, once you make that energy available, we can’t predict for any particular collision what will come out. We have no idea. All that we have is basically a list of probabilities of different things happening, different processes that are made with that energy that’s created, right? So, if you can make dark matter, if dark matter is out there, then this energy that we’re providing in the center of the Large Hadron Collider should be able to produce dark matter particles, or there’s the potential there, right? Nature is what gets to decide what to do with the energy and what not to do with the energy. So, unless you think that there’s a different nature of energy producing different things, we should have full access to that at the Large Hadron Collider. So, that’s the first thing. It’s just energy; nature chooses and then we have to just hang on for our dear lives and try to figure out what happened in the collisions.
Our real trick, both for accessing dark matter and for accessing gravity potentially…Dark energy, forget it. I don’t have a path there at the LHC, but maybe somebody else does. But in terms of dark matter and gravity, because our collisions come in and the protons hit each other head on, you can make a line through that, right—the beamline of particles, protons charging toward each other. When things come out of the collision and fly out to one side, we have to have momentum conserved with stuff flying out to the other side. You have the protons colliding, you have energy produced, and stuff flies up toward the sky—well, you’d expect a certain amount of stuff to fly down toward the ground to conserve momentum. You can’t have stuff created and then just fly off in some direction without conservation of momentum. So, what we get to do is if we see stuff fly in one direction without anything detected to balance it, you infer that there must have been stuff that flew off in the other direction, and some of the stuff that might have flown off in the other direction could actually be dark matter, right? Or it could be a graviton that’s responsible for mediating force of gravity that escaped into another dimension. So, there are all kinds of things that you can find by the absence of momentum or energy. It just means that you need to understand precisely how your detector works. You need to have an exquisite understanding of your detector so that you know that the missing stuff is not a detector mistake, but it actually could be something new that was produced that you can’t detect.
Your answer strikes me as a really powerful response to some of the malaise, the post-SSC malaise about the existential crisis that high energy physics went through in the late 1990s and is really in some ways still recovering from. Do you see these connections with cosmology and astrophysics as one of the most important ways to ensure that your field is most relevant and dedicated to answering the biggest questions out there?
Yeah. I think that’s true. I think that they’re some of the most exciting questions that we have. Yes, absolutely. I think that the links between different fields are the way of the future for all of us. I mean, you zoom into any of these fields that used to be distinct…I guess the best example of this—I would love for the LHC to be involved at this level, but you know the multi-messenger astronomy? All of these different telescopes and observatories are connected, and if somebody sees something in this spectrum of light, they send out the alert and then everybody else can chime in and turn their telescope to look at that part of space and see what they see from their perspective. I mean, that’s just so exciting to have actual phenomena out there with worldwide networks of experimenters that have different strengths and different insights all turned to one problem, right?
We’re a little bit like that, I guess, with dark matter and, yeah, maybe you could say gravity. Like I said, I don’t know that the Large Hadron Collider can compete on the dark energy front, but we’re certainly part of understanding that broader story of the makeup of the universe, the evolution of the universe. Those kinds of big questions are definitely on our plates at the LHC, in addition to understanding the particle content of nature. In what ways do the particles that we have discovered decay? What kinds of new particles can we produce? Those kinds of questions, classification questions that are at the root of how everything interacts.
Just to bring the narrative up to the present, what are some of the things that have been most interesting to you in recent years? What have you been working on?
Oh. Well, those are not necessarily the exact same answer. [Laughter] (Because I’m interested in a lot of things that I haven’t been working on.) Yeah. So, I’ve been working on the Higgs at ATLAS. It’s all hands on deck. There are four main ways that we produce the Higgs boson, and then once you’ve produced the Higgs boson, it basically immediately decays to lots of different particles. It couples to all kinds of things, and so it’s all hands on deck to make sure that we understand the ways that it’s produced, the ways that it decays, and you can pick combinations. “I’ll look for this production mode and that decay mode,” and I’ve done that with my group, something that hasn’t been covered.
It does two things for us. One, it teaches us more about the Higgs boson. It checks another aspect of the Higgs, which is important, and two, it lets us try out new analysis techniques. We picked a really challenging channel that makes us rely more and more on machine learning techniques to really get everything we can out of the data, in part in preparation for the run that we’re going to have over the next decade with the High-Luminosity Large Hadron Collider.
So, that’s been really exciting for me to have a piece of this Higgs puzzle, to try to map it out, and right now we’re blinded, meaning we’ve developed the analysis but we haven’t looked at the data to see if the Higgs is there or not. But we’re at the level of sensitivity where we think that if this production mode and decay mode of the Higgs is there, we’re going to see it when we open and look at the data. So, that’s a very exciting thing that I’m involved with my group.
We’re also looking at…In general, I’m a little bit obsessed with tau leptons. As I mentioned, they’re really challenging to work with in the context of the Large Hadron Collider, so pushing the envelope on taus, on triggering on them, on using them to try to make Standard Model measurements, or push for physics beyond the Standard Model is something that’s been really fun.
Mu2e that I mentioned, one of the experiments I’m on, it’s the few, the proud, the crazy. It’s trying to take a measurement of an incredibly rare process and improve it by a factor of 10,000. It’s a process that we’re looking at with just overwhelming backgrounds that we have to beat to a pulp in order to see it, and it’s a particular way that the muon decays that’s basically forbidden—not fully, but basically forbidden in the Standard Model. But it’s predicted in all kinds of extensions to the Standard Model that people talk about. So, trying to get Mu2e ready to take data, that’s been something that’s been very fun and exciting.
In general, though, I’m interested in all kinds of results in physics from the gravitational wave discovery. That was just thrilling. I remember the crazy LIGO people when I was in graduate school. I mean, they were really insane, almost as crazy as those people looking for Bose-Einstein condensates, right, which I guess everything has gotten a Nobel…Everything that was crazy when I was in graduate school has gotten a Nobel Prize at this point, which maybe says something about how old I am or how productive it is to do things that are crazy.
Yeah, so all kinds of things I’m interested in, you know, orthogonal to my field or parallel to my field. I’m really interested in questions that are very far afield also with energy. My husband works in energy-related questions in physics, and I think that’s an incredibly urgent line of inquiry, right? How can we make more energy-efficient devices, new sources of energy, hydrogen fuel cells, those kinds of things. So, all kinds of interesting stuff that’s happening. It’s hard to pick just a few to talk about.
That’s good, and it’s invigorating to hear. Sarah, for the last part of our talk, I’d like to ask a few broadly retrospective questions about your career, and then we’ll look to the future. First, I’d like to ask you. I want to come back to this idea that physics (and science in general, of course) needs different brains. It needs different perspectives. For you, it’s clear both on your CV, both in terms of your philosophical inclinations and your openness, which is so clear over the course of our conversation, to be aware of when you feel like an impostor, to be aware when you don’t know something, to say that you don’t know something. If you can reflect over your career so far, how has this perspective, this openness, this level of inquiry, how has it helped you advance both the questions that are most compelling to you, and how has it advanced the broader collaborations that involve so many people from so many different perspectives who are all sharing the overall mission of the research?
Yeah. Well, I’ve learned a lot by paying attention to the space of diversity and inclusion and anti-racism. I think that a lot of people have been very courageous, particularly over the last couple of years, in speaking out about how challenging the world that we’ve created and these collaborations that we’ve created is for people to navigate who are part of underrepresented groups. I think I’ve had enough experience myself with how exhausting it is to try to exist and operate in a space where you don’t feel like you fit in if you’re having to always pretend that you’re someone who you’re not. So, I’m really excited about the moves that we can make as collaborations to let people stop wasting some of that emotional energy and be themselves more at work. I think that everything that moves in that direction is fantastic, but even beyond that, a lot of things that we can do in those directions are good for everyone in our collaboration, right? It’s exhausting for everybody to try to be someone that they’re not or pretend that they know things that they don’t or not have permission to ask questions.
So, I think I’ve learned a lot by trying to pay attention, and in my group and in the different roles that I have and the managerial perspective, I think it’s a combination of both modeling that’s really important: asking the questions, making it clear that you don’t know everything, right? That’s a critical piece of the puzzle, but it’s not enough because it’s easy for me as a tenured faculty member to say that I’m comfortable admitting that I don’t know something. How is somebody who doesn’t have that kind of a position and who is actually going to be judged for not knowing that—how are they going to have that kind of courage? So, it has to go beyond that, and that’s something that I’m still trying to understand how we can do a better job at. I don’t know. We need to give people permission to admit that they don’t know things. It’s just so crazy because there’s far too much to know and so much to learn. Yeah. I don’t know. We have a lot of work to do. I think one of the things that I’m really mindful about is trying to keep all of this work fun. The fact that we can work together as a team, we can try to explore these kinds of questions together, trying to have an environment where people are invigorated and built up as much as possible in work as opposed to just kind of torn down—I think that’s really an important environment that people who are in leadership positions have to try to foster. I don’t know if I’ve answered any of your question at all. You asked a really big question.
[Laughs] You gave a really big answer! I want to return to this idea during the pre-tenure process that you were very focused on doing research that was completed. In other words, you found results and they were publishable, even if they were only a piece of a much bigger puzzle. If you could think about all of those papers, what has been most intellectually or scientifically satisfying to you, the wholeness of a research problem that you felt was completed? It might not be the whole story, but it’s an important story for you and it’s an important story for your field.
Yeah. All right. So, one of my proudest accomplishments was the first measurement of tau polarization at a hadron collider. It was not the strongest component of my tenure case because the paper that was written in—gosh, I don’t even know. 2012 did it come out eventually? It took so long. Maybe 2013. Anyway, it has like a dozen citations. It is not exactly…It hasn’t gotten a ton of attention, okay? But it was a measurement that…A polarization measurement is an elegant measurement, and taus, as I’ve mentioned, are not elegant beasts in the Large Hadron Collider environment, or in any environment. They decay in 10-13 seconds, often to sprays of other particles that are hard for us to characterize and actually say, “Oh, that mess over there is actually a tau.” So, the fact that you can do an elegant kind of measurement with such an inelegant beast was really exciting, and a lot of people didn’t think that it was going to work. I had a brilliant post-doc at the time, Zofia, who had a strong theory background and really helped guide our group through to the end of this. So, that’s one of the most exciting measurements that I’ve been associated with and guided at some level, and the result of that is we worked to understand some variables [chuckles], which doesn’t sound maybe very glamorous, but we got some variables to the point where we could actually make sense of them in the detector. They’re now being used, folded back into the very way that we identify taus at the LHC.
I mean, it was groundbreaking in some ways. It was the first of its kind. It’s got a lot of potential to even say something about the Higgs because the Higgs decays to taus. We can use tau polarization to go back and say something about the Higgs, actually, and that’s something that we’re working on that is more of a long-term project because it’s very hard to do. But the fact that it got reincorporated back into how we handle taus is exciting for me. It’s anti-helpful for something like a tenure case where you want citations and, you know, to say, “Oh, this is now part of our reconstruction software,” is not what people want to hear on the tenure committee. They want to see that it’s cited by theorists all over the place and moving in a more direct line toward new physics discoveries, but yeah, it’s one of the things that I’m more proud of and still excited to try to push forward.
One of the craziest things about it is that when you produce the tau…Or we have to simulate with computers everything that we’re looking for because otherwise how do you know that you found it? You have to know what a particular model that you’re looking for actually looks like in your detector. You have to translate between the physics processes that you care about and how particles interact with the matter of your detector. So, let’s hope. I am starting to get tired; I just lost my train of thought. Oh, right!
Quantum mechanics and the nature of particles was actually really important for us because a particle is flying through space, and if you want to measure the spin of that particle along a certain dimension, the act of measurement gives you a spin in that dimension, but before you make the measurement, you don’t know necessarily what that direction of spin will be along that axis until you make the measurement. It’s not a determined piece of information until the measurement is made, and so it was interesting to understand the limitations of our software where you might think that you should know going in the spin of a particle and the nature of quantum mechanics. So, that was really fun to explore how the unknowable components of nature actually interact with our machines when we’re trying to just code something into the computer. Oh, shoot! There’s quantum mechanics. I can’t just write a number in for that. It’s not a knowable quantity at that point and it matters.
Sarah, I think this is a comment you made before we actually hit record, but it was an important distinction that you drew that when we’re talking about inclusivity and diversity and equity, just because things are better now than they were 20 years ago does not mean that things are good now. On that point, I wonder if you can reflect during your time at Yale the extent to which Yale institutionally is aware that in many ways it sets the tone on things like this and what happens at a place like Yale reverberates beyond the campus, beyond New Haven. In talking to people like Larry Gladney, it’s obvious that Yale takes these issues very seriously, and so in taking them seriously, there has to be a level of recognition that, however far the University has come, it’s no time to pat itself on the back because of all the work that needs to be done. So, over the course of your time at Yale, what can you reflect on that indicates there is still work that needs to be done, and what do you think that work is going forward?
Wow. I think that there’s a sense still among a lot of scientists that we could be objective about humans, or about anything, right? It’s surprising to me. It’s something that I don’t understand because I mentioned earlier when we design analyses, we sometimes have blind analyses. We are paranoid about bias when we’re designing our experiments to the point where we don’t even look at the data. You know, you have an experiment that’s designed, and the worry is that if you look too early at the data, you might sculpt your choices around the data as opposed to making analysis that is more agnostic than that, right? So we are paranoid to the point where we don’t even let ourselves look at the data when we’re designing the analysis. We wait until everything is sort of buttoned up and done before we let ourselves look because we’re so afraid of how bias might creep into that process. Maybe you’ll stop looking for bugs in your code when things look good, but it’s too early because there are other bugs in your code, all these things that go into it.
But for some reason, when we think about our other judgments or our other decisions or our other work that’s not designed around a physics experiment, we stop worrying about bias altogether. I’ve never understood that, how people who are so paranoid about bias could think that it doesn’t come into play in other aspects of their lives, but the reality is that there still are people who are involved in hiring decisions and promotion decisions who do not acknowledge the influence of bias. I think that’s at the root of the work that needs to be done. An institution can ask people to care about bias or can require people to take a course to understand how bias functions, right? There’s data. There are studies that have been done that show how bias operates in damaging ways based on skin color, gender, different snap judgments that people will make on you based on those kinds of aspects of your identity. But until the people who are involved in making these kinds of decisions buy into this, there still is going to be work to be done, and even then I don’t see an end to worrying about bias. It’s not a matter of one more diversity training enterprise or hiring four more women or something like that that puts you over a tipping point. I think that’s the bottom line. The institution can do a lot and the institution needs to do a lot. You can lead a horse to water, but you can’t make it drink. As long as there are people who are involved in decision making who don’t buy this, there’s work to do. There’s really urgent work to do.
Sarah, for my last question, looking forward, our conversation has been sort of refreshingly not overly technological. It hasn’t been all about the computers, right? But to go back to the metaphor as it relates to your own life, right, about breaking through the wall, your field (and of course, physics in general) is very much in that mode of not only not breaking through the wall but searching for the wall to break through. On that vein, in what ways do you think things like AI and machine learning and quantum computing for your field and generally for physics will be useful to getting at those fundamental questions? To what extent are they merely going to be another tool in the toolbox and it’s still all about what it’s always been about, which is human ingenuity and collaboration and creativity?
So, when I started in graduate school, I remember one of the first big machine learning battles at the CDF experiment with the discovery of the single top. It could not have been done without machine learning techniques, and people were so suspicious of it. There were so many roadblocks put up. How could we use this thing that seemed to have black box nature to it? There were so many unknowns as opposed to physical quantities like let’s measure the energies and the masses and construct something that has meaning, right, and use that to design analysis.
So, those days are very far behind us now. I think there’s no doubt that the tools of machine learning are central to just functioning in the environments that we have to function in at the LHC. And it’s just going to be more and more critical for us to take advantage of those tools if we want to make sense of the environments in even higher energy machines or higher luminosity machines where you have so many overlapping interactions that you’re doing simultaneously in order to get high enough data rates to make sense of what you’re seeing. So, the tool aspect of it is real and is there.
I had an interesting relationship with machine learning where I had to really change how I viewed it because we’ve learned that there are instances where physicists are getting in the way, and the fact that we’re trying to construct variables…
So, you know, what is the ATLAS detector? You’ve got collisions inside. You have particles streaming through, and those particles that stream through interact with our detector in different ways. They leave electronic signatures in different ways. We’ve got lots of different technologies that are used. You might have pulses of energy that are deposited. You might be counting photons. You might be counting electrons, right? It’s a big mess of electronic signatures that the particles have left, and you would like to think as a physicist that knows something about the nature of particles that you could design ways to put those signatures together and find something interesting. But just handing all of those signatures to a machine learning algorithm and training that algorithm on what you want to find might be more efficient than trying to use your brain and look for quantities that have physical meaning.
So, I think one of the things that we have to understand as we’re using machine learning techniques is…I have talked about them as a tool, but to really get the full benefit of them, we have to get out of their way to some extent and stop thinking that, you know…Understand where we add value. You know, where do I add value as a physicist? Maybe it’s not in constructing the mass terms or the variables of it. Maybe it’s in understanding how to train this machine learning algorithm, which is a very different skillset than traditionally physics has been. [Chuckles] The work of doing analysis has traditionally been more about understanding some of your physical intuition than it has been knowing how many layers of a neural network you should have and how to best represent the data so that the algorithm can do good things with it. My students are pushing the envelope on this all the time because they’re obsessed with machine learning.
This is a generational thing to some degree, do you think?
I think to some degree. They are truly obsessed with it. I mean, undergraduates, that’s their first question. “Can I do a machine learning project?” I mean, that’s really what they want to do. Yeah, it’s definitely a different skillset that they have to have in order to train these networks, but the students I have who are most advanced in this also remind me that these networks are deeply stupid. I mean, you really have to point them in the right direction. You really have to present the data in a way that is useful for them so that they know how to crunch through it, so I don’t know. It’s fascinating, right, in that they are so powerful that they do a better job than we do when we work very hard to design an analysis. But at the same time, they are so stupid that they can catastrophically fail if you don’t steer them in the right direction and massage the data in a way that they know how to actually take it in and make something meaningful out of it.
It’s like a hammer is very good at hitting a nail, but you have to point it at the nail, basically.
Yeah, yeah, yeah. And we typically have been stereotypically very far behind the edge of machine learning algorithm development. In particle physics we’re fairly conservative, or at least we have been traditionally. I think the fact that so many students and post-docs and younger people in general, or early career people in general, are interested in this means that the gaps have closed a little bit so that we’re a little bit more on the cutting edge of it. We do have something to add in that our datasets are a little bit different than maybe what computer scientists are typically thinking about in development, so we have that going for us. And something that we care about obsessively is a quantization of our error. We care so deeply about the level at which we’re making mistakes—much, much, much more than maybe a translating program does because we need to know…You can’t just buy another Large Hadron Collider and stick it in your backyard, right? If we’re going to make claims about nature with this machine, we need to be very solid about those claims. So that’s a place where we really can push and help the development of machine learning algorithms. We call them systematic uncertainties, you know, understanding the ways in which we make mistakes in our analyses. That’s a really powerful thing.
Sarah, I want to thank you for spending this time with me. It’s been awesome listening to your perspective and all of your insights. I’m so glad we were able to connect, so thank you very much.
Oh, thanks for your time! It’s weird to talk about yourself so much. Thank you.