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Interview of Larry Gladney by David Zierler on October 28, 2020,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
For multiple citations, "AIP" is the preferred abbreviation for the location.
David Zierler interviews Larry Gladney, professor of physics and Dean of Diversity and Faculty Development at Yale. He describes the origins of this Dean position, and how he worked to make STEM a more inclusive, accepting place over the course of his career. He recounts his childhood in East St. Louis, opportunities that led to an undergraduate education at Northwestern, where he developed interests in experimental physics. He explains the attraction of being recruited to Stanford; Burt Richter invited him to work at SLAC. He describes his thesis research under the direction of John Jaros and Bob Hollebeek, looking for supersymmetric electrons. Gladney discusses postdoctoral research at Penn, where he worked with Brig Williams on the CDF project. He also goes into the excitement surrounding the search for the top quark at Fermilab. He describes joining Penn’s faculty, while also getting involved in diversity promotion within/beyond the physics department. He then discusses contributions to the BaBar collaboration and he explains the interest of particle physicists moving into cosmological research, at the turn of the century. Gladney describes his time as the department chair at Penn and his work on LIGO and the LSST, and he discusses the state of play in high-energy physics in the post-SSC environment. At the end, he surveys some of the most promising research in cosmology and why engaging young students is so crucial for the future of the field.
OK. This is David Zierler, oral historian for the American Institute of Physics. It is October 28th, 2020. I’m so happy to be here with Professor Larry Gladney. Larry, good to see you, and thank you so much for joining me today.
Oh, thanks for having me.
All right, so to start, would you please tell me your titles—and I put a plural on there because I know you have more than one—titles and institutional affiliation?
All right. So, currently, I am professor of physics at Yale University, and I’m also the dean of diversity and faculty development.
Is that dean of diversity position, is that—are you the inaugural holder of that position, or this goes back before your tenure?
No, I’m the inaugural holder.
And what were the circumstances that led to the creation of this position?
Ooh, well, it goes back quite a way if you want to get the entire history of it. But I would say the major impetus was, there were several events that happened in 2015 at Yale, and the response to that was multifold. But I would say the biggest piece of it, as far as resulting in my position, was around the issue that there was dissatisfaction, that there had been considerable increases in diversity for the undergraduate population—which of course is quite exclusive as I think most people know—but there had been much less in the way of diversity that was lasting for the faculty. And, in particular, what the faculty themselves noticed was that most of the increases in underrepresented minorities—who had come on to the faculty in the 2000s—were essentially gone by 2015, 2016. So, if we looked at just one group, African-American professors, there was no increase essentially from 2008 to essentially 2018. There had been an increase, and then essentially all of those people left, or at least the numbers had essentially been stagnant.
So, this led to the faculty themselves thinking that, independent of what the administration was happy to support doing, there needed to be more of a—an oversight role, I guess you could say—into the faculty hiring process. Now, oversight of course, is something that one has to be really careful in describing for faculty, who have been used to being pretty much autonomous in—certainly in the faculty hiring space. So, it was essential to the faculty that whoever you put into this position would, first of all, be a faculty member who is either a researcher who teaches or who carries out service responsibilities. So, it couldn’t be a full-time administrator. And it also could not be a situation in which I would say—to put it [laugh] in the way that it was described to me by Yale faculty—it couldn’t be a Yale faculty member, right. It had to be somebody from the outside.
The way they put it was one of the things that keeps Yale from advancing. It’s hard for it to get out of its own way. And so, the idea was that you needed a new perspective—a new set of perspectives actually. And you also needed to have someone who could not feel obliged to follow the tradition—if it was a situation where tradition in and of itself did not allow you to think more boldly or would keep you from, I would say, stepping on somebody’s toes, for example, you know—because you’ve had a long long-term relationship with them, and you don’t want to jeopardize that by saying, “You’re doing this wrong. We really need to go in a different direction.”
So that, as you might imagine, took some time to work out. And so literally it was from 2015 to roughly about 2018 before they were convinced that they had the right model in mind; they had support of the administration to bring this in because of course you need them to be a partner on this, and then actually start the search. And then, you know, 2018 the search begins in earnest, and I came in as the finalist in late 2018, and then, six months later, joined in January 2019.
So, your origins at Yale, this was a joint appointment? It was part of the package that you would be dual-hatted especial…particularly with this position, and being a professor in the department of physics?
That’s correct, yes.
And just in terms of understanding the hierarchy, in the dean position, who do you report to?
Well, you know, that’s interesting. I had turned down basically essentially a soft offer of the same kind of role—or I should say a role that had similar responsibilities in the Provost’s office at Penn, which is where I’d been for three decades before coming to Yale. And so, it was important to me that this model be the model that it was. That is, it’s someone who is a member of the faculty who works directly with the department’s faculties, and consequently is not perceived as being, you know, convinced that you have to obey the strict hierarchy of an administration. That is, I don’t work for the Provost. I do answer to the dean of FAS, but the dean and I are very much, you know, aware that I work independently.
My best version of this role is one in which I can give unsolicited advice, and I can also present to the faculty—without needing prior approval—my view of what Yale itself needs to do. So even though I formally answer to the dean, I also answer to the Provost and to the president. So, I advise both of them, as well. I also can work pretty freely with the other schools, and so I’m not strictly speaking a spokesperson for diversity within FAS. I’m a spokesperson for diversity broadly speaking.
It also means that because we have Yale College and we have the Graduate School of Arts and Sciences, which are completely separate entities, that I can also work in ways which enhance diversity within the graduate population, and I can also speak with—you know, obviously I try to work very closely with the college office-—but I can also work with undergraduates to get their input. That is hard to do if you’re, you know, strictly speaking within an administrative pipeline that goes from top to bottom. So, it was really important to me that this actual role works best, I think, if you’re actually able to cross boundaries without having to understand that you need to answer directly to a particular boss or follow a particular hierarchy.
Larry, I’m curious, either from your own personal background or your long-term work in diversity issues throughout your career—of course, 2020 has been a year—a national reckoning of race, you know, across our society, in higher education, in STEM, and of course in the field we work in in physics, of course, with the movement Particles for Justice and the way that that Black Lives Matter has informed diversity issues for #ShutDownSTEM and other issues. I’m curious, coming to Yale a year before all of these hit our national consciousness—of course, they’ve always been there but they’ve sort of become headline events in 2020—how well-positioned did you feel as these things became all of a sudden on the agenda of everybody, things that everybody was thinking about from all of their perspectives? How did you see these macroscopic events? Where were the opportunities and the challenges for you in this role at Yale?
Well, I think it was— you know—it’s hard to look up on anything having to do with the pandemic and the timing of George Floyd’s murder as being optimal or opportune. But it was, to me, really important that I had a year of experience being at the institution before these things happened, and also had begun the discussions before we needed to have these discussions. So, there was an immediate push, for example, by many universities to put out statements right away, right, that you had to respond to anti-Black racism. You had to respond to police presence on campuses.
And I think it was understood that because we had begun some of the conversation, that was really necessary for what, you would say, would be the response to those things happening on the national scene, it was vital that this didn’t feel as though we completely ignored it, and then all of a sudden we felt we had to respond right away before we’d given any strategic thought to what to do. So, that’s not to say that, you know, we weren’t surprised and shocked. But it is to say that we didn’t feel compelled to have to immediately say, “Ah, well, we’re going to form a bunch of committees. We’re going to have a bunch of White Paper reports come out, and then, within three months, we’re going to be prepared to go with something.”
Many places really felt they had essentially, you know, several weeks at most in order to actually be able to say something. But, for example, we already had a President’s Committee on Diversity, Equity and Inclusion and Belonging, that formed last January. So that committee was able to actually carry out its work. And, yes, we obviously were impacted by having social separation, and having to do everything by Zoom. But it was the case that we were already well on the way to understanding what the university needed to change—not in shock response—but because there was some measured understanding that there were ways in which we could do better at improving the sense of belonging for all of the constituencies on campus, so that’s staff, students, faculty, and alums.
That, I think, was pretty crucial to our understanding that we’re probably on the right path. And that’s not to say that other universities, that didn’t have as much time, were not. But I really feel as though we’re in a position where we’ve had enough discussions that we understand what people are prepared to do with the long-term as opposed to we’re going to immediately put together an effort, and it’s not clear whether those efforts can still be as energetic a year after George Floyd because they were put together in response to, right, or very much so in response to.
These are of course enormously complex challenges that we’re all facing, and they go back centuries, and there are enormous sensitivities. So, given all of that, what are some of the feedback mechanisms that you’re relying on? Given the fact that we’re right in the middle of this, as you chart a course forward, what are some of the benchmarks or feedback mechanisms that you’re looking for so that you have an idea that you’re on the right track, that you’re making the progress, that you’re doing what your mandate, what your personal interest and goals are set to be?
So, the first is that informatics has to be an essential part of any path forward. That is, we’re—despite the fact that we’ve had decades of experience at trying to do a better job—let’s just say on diversity but also on inclusion, we know that we’re not where we want to be, and, consequently, there’s a feeling that we must not be where we can be. But one of the things that should change is that we should be keeping regular tabs on what the feeling of inclusivity is among people on campus. So, we have to have just more opportunities for people to talk about their experiences of being on campus.
There are very, very few venues in which people feel there’s a safe space for them to give a record of things that they’ve experienced, that make them feel as though this cannot be the intellectual home for them. It’s a home where you have employment. And clearly you can survive that way, and obviously lots of institutions within the country have survived for many years that way, but it makes you complacent in thinking if people aren’t complaining, they must be happy. But of course, what’s changed or, sorry, what’s been true, and what has to change is that they haven’t just had opportunities to feel safe in saying, “Here’s what’s not right.”
So many more forms of information-gathering than we have had previously need to be in place, and that’s for—again—for alums, for students, particularly for staff that feel very much as though decisions are made without their intellectual input being valued. And there has to be recognition of people’s contributions that haven’t happened as regularly as they should and haven’t happened as thoroughly as they should. So, when you talk to people—as we’ve done this past summer of course...we’ve been listening a lot—there’s been a consistent message that I feel as though people respect my work because they know how hard it is to actually be a part of the community.
Our staff, for example, go through [laugh] a process which is every bit as exclusive as becoming an undergraduate student here, and almost as much as becoming a faculty member here. It’s really tough. Yale is a preferred employer in the area, and it’s not New York, and it’s not Boston. It’s not Philadelphia. So, you know, the jobs that are attached to the university are really highly prized, and they get huge numbers of people signing up for them. So, people do feel as though they’ve come out as being recognized for the skill sets that they bring and the contributions they make, just because they know how hard it is to actually get employed here.
But they don’t feel that they can freely talk without having pushback that makes them think, you know, I’m not on a level playing field here, right, that I can say what’s going wrong or what we should be doing more efficiently. And sometimes that’s taken, and sometimes it’s not. But there’s no regular way in which—when it’s not I can feel as though—I can come back and say, you know, I had a better idea for how to do this, and it wasn’t recognized, so let’s change our process for decision-making so that I can feel as though when we don’t make progress—because something I said was not taken as seriously as it should be—that there’s a recourse to come back and change course, as opposed to sort of saying we have to sort of stay this course as long as the people, who really have a charge of things, are prepared to go without changing direction.
Another thing that we heard pretty consistently was that even people who were in charge still felt as though they didn’t have authority. And so, what I mean by this is people would say, “How can we improve on diversity and inclusion?” And they would respond, “All right, we should be doing A, we should be doing B, we should be doing C, we should be doing D. I don’t feel as though I’m the one who can do any of those things [laugh] on my own, right.” But you would say, you know, “But you’re [laugh] an Executive Vice President.” [laugh]
[laugh] Or, you know, “You’re an Associate Provost, you know. If you can’t—you have control of budgets. If you can’t do it, then who does have the authority?” So, there is quite a bit of distraction that comes from people wondering if I got in front of this, am I going to be supported? Am I going to be backed up?
And so we—again—we express statements on websites, but it’s not clear that people—in fact, it’s clear that people are not getting the message that we would follow through on that in actuality when it comes down to someone saying, “All right, well, we made this change but, you know, making change is difficult and, consequently, who gave you the authority to actually decide that we could do this?” If, for example, we do these things with diversity, and it winds up being very visible, and Yale is very, very conscious of the fact [laugh] that essentially everything they do winds up in The New York Times at some point. I mean, it’s a very, very hard environment to think about even discussing things when you don’t understand where a part of your discussion might actually wind up in the general public’s view. It’s something I didn’t experience at Penn. But it’s very much on the minds of essentially everybody here, that if we change a website, it’s going to be picked up by people who are not necessarily friends of the university, who are going to, you know, make use of it in ways that were certainly not intended.
But that means that you’ve also got to assure people that if something does come out, and it’s seen as negative for the university’s image, that we’ve got justification of why that happened, and that we’ve got support for the people who do it. On the other hand, we also have to convince the faculty that that doesn’t give you carte blanche to say anything you want to say. So, I consider one of my roles is to say to people, “Academic freedom comes with academic responsibility. You can’t have one without the other.”
Consequently, you cannot just use the N-word in your classroom because Martin Luther King used it in a letter, right. This is just not the time. This year in particular, you should just avoid all use of it altogether. It’s not an issue of academic freedom that you’re allowed to use it. Of course, you are. No one’s going to take away your tenure.
But you should expect that if you do use it for any reason, there’s going to be considerable outcry, and that outcry...we can’t back you up from the administrative role by saying, “Yes, faculty are allowed to say whatever they want in the context of a classroom discussion.” Yes, sure they are. But they’re also expected to be moral leaders within the class, within the course environment. And that means that you have to be responsive to the fact that there’ll be emotional responses that maybe wouldn’t have happened five years ago.
And, consequently, we need to have discussions about this because free speech, of course, is never a correct terminology, you know. Anything that you say actually does have a real consequence. And some of that consequence you can count it as a cost if you want, but some of that consequence requires you then to come up with more of a rationale than simply saying, “But it’s always been the case that we should say whatever we want, and no one should berate us.”
Sure, there are limitations to that. But students feel much more empowered than they ever did to argue, to push back. And we actually want that, right. It’s part of the vision of a 21st century university that maybe wasn’t there in the 1960s, when authority figures were essentially never questioned. We just don’t have that as a perspective anymore. And, consequently, again, if you talk about diversity, increasing diversity means that there will be more people whose viewpoints are considerably different than your own, and whose background—for how they express those viewpoints—are considerably different than your own.
And, consequently, if we’re better at having those discussions, then I think that we’re more prepared to say that we are an inclusive environment. We’ve improved on inclusivity. So those are measures, right, and I very much tell people that we can—we will still count numbers, you know. Social identities are easy to measure, and therefore they’re quantifiable in ways that we can keep track of—so we’re not going to stop that, and there are federal laws and state laws and so forth that we have to contend with—around those numbers.
But that isn’t the point, right. That’s not the focus. The focus really is are we more inclusive of differing points of view? And those are things that are harder for us to measure, but they’re not without their—they’re not without the ability to quantify in some level. And so, keeping track of that is an essential piece of knowing that we are doing a better job.
Larry, I want to ask, as we develop your personal narrative—it’s as much perhaps an emotional question as it is an intellectual question but because you are dual-hatted—I mean, you’re a physicist as well, of course—have you now or in the course of your career felt like you wanted to retreat into cosmology and particle physics, and get away—
—from the tensions, or is that not a luxury that’s even been afforded to you even if you wanted to have that approach in terms of academic politics? In terms of the racial politics of a laboratory environment—have you felt like you’ve been able to separate those worlds--have you been able to separate those worlds, and have you wanted to separate those worlds?
Wow, great question. Really tough to give you a crisp answer on that as it’s true for most things that involve [laugh] administration and responsibilities to the side. So, I’ll tell you my personal journey—
There’s no racism in space is the idea, right. So, don’t you just want to go there sometimes?
Well, that’s the perspective that I developed when taking this job, that I didn’t necessarily have firmly in mind before. It was sort of always there but not quite there. So, you know, for 20, 25 years, I did just concentrate mostly on my science. It’s not that I ever retreated from issues of equity and diversity and, you know, anti-bias, anti-racism. But it wasn’t an essential part of my identity, to say, that I’m the person who is going to speak out on these issues. And part of it is that you feel isolated, and part of it is just this idea that it wasn’t part of the profession but this—
And perhaps there was some pushback on your part on feeling like there was tokenism, and an expectation for you to speak up on these things?
Very much so. But as a department chair at Penn, you know, it was uncomfortable for me to feel as though I always have to be the one to bring up this issue of lack of diversity on our faculty. And so, I didn’t want it, right. At some level, I really felt as though I needed my colleagues to spontaneously agree to this rather than being led into it.
But what changed for me was understanding—particularly in this last year, but even before that—that when I look around at cosmology, and I look around for people who are in physics who are feeling free to express themselves, the younger generation were very clear, “You failed, right, me, my generation.” When I graduated, I was told—I never checked it—that there were 12 experimental particle physicists in the country who were Black, right, when I—the year I got my Ph.D. in 1985. So, really, that should’ve been a clarion call to me that I needed to be working on this from—you know—from 1985.
Now, would I have been able to do as much as I did in my scientific career if I’d been as interested in it? I don’t know. But it’s clear that I should have found, to me—a personal responsibility in trying to do a much better job of pointing this out—first of all, and then saying that we can’t be satisfied—my colleagues and I can’t be satisfied with just doing our science because just doing our science leaves out the fact that science is as much as anything else a human activity. So, who gets to do it, and what they bring to it, which questions they ask and want to be driven to answer, and the way in which they approach solutions to the problems, is very much a piece of what we’re doing. It’s just that we’re doing it unconsciously, rather than making conscious choices about how we provide these opportunities to others, and who we take on as our colleagues.
So, I am very mindful in this position. I took it partly because I wasn’t prepared to simply live out my life and the rest of my career kind of doing this peripherally, right, and bringing it up only when it happened to come up, and then saying, “But, you know, you should know that I support one side of this argument or another.” And it’s not as though people are pushing back. It’s that they weren’t pushing forward, right. And so we just have to be more mindful that, all of us, no matter what we do, can afford to have one less paper and maybe even one fewer grant—if it’s possible for us to actually push other people forward who lack the same level of opportunity and the same degree of agency, to say that, you know, I want to not ignore these things, and I want to do science, and those are not incompatible with one another. It’s not one or the other. They really ought to be part and parcel of what we decide to do.
So, I don’t mind anymore, you know, what the level is between [laugh] how much time I get to spend on cosmology versus what I’m doing in my day job. I want to always be able to say, yes, right. And so, there’s no kids in the house [laugh], you know. My wife has her...has a career which keeps her busy. So, I really sort of feel I’m—if there’s anybody in the world who ought to feel as though they’re optimally engaged in not having to make trade-offs, it should be someone like me who’s tenured and obviously in various leadership positions throughout the American Physical Society and so forth.
So, I don’t give it much thought, to tell you the truth. I mean, I should. I’m preparing a talk now for the National Society of Black Physicists meeting next week. And I’m really enjoying thinking [laugh] about the connection between particle physics and cosmology, and boy, it would be great to have this entire day [laugh] just to think about how to put together a PowerPoint to tell the story of where we are right now, and what the promise is for these next 10 years, which are going to be incredibly exciting. So, you know, I’m still fired up by that, and I would love to, sure, be able to say, yeah, you know, 15 hours a day—
—on this for a month would be terrific. But I’m also mindful that, you know, tomorrow I’m going to be talking to a department that’s trying to pull together a better plan for how to improve on equity and inclusion. And, you know, I want to think about that, and be ready to answer their questions on it because some of the questions should be challenging. They should be hard. But I do get a kick out of it. It’s enjoyable to think this is a hard problem. This is what you like physics [laugh] for.
I don’t know that I could solve that problem. But that was the way I got introduced to particle physics [laugh]—was nobody knows how to build these things. You’ve got to figure it out. That’s the challenge of it. And the person who’s crazy enough to keep coming back is the person who is going to ultimately succeed. So, this—you know—these issues of diversity and inclusion are exactly that.
I have no idea whether we can solve them. They’re huge problems. We’ve been working on them for—you know, it sounds an awful lot like a physics problem that has just required people to keep pushing on it until they effect some kind of a breakthrough, with their colleagues, right. Not as a single individual genius who figures out all the answers, but as someone who’s part of a team.
Well, Larry, let’s now take it back all the way to the beginning. Tell me about your family background, your household, and your early childhood, how you grew up.
So, I grew up really poor in East St. Louis, Illinois. We were in a four-room house for most of the time, and that’s when we moved out of the back of St. Louis.
East St. Louis comes to mind because I believe Savage Inequalities, the book, Savage Inequalities—
That’s right, Jonathan Kozol’s page 1, chapter 1, is on my high school. But you know—that story, as horrible as it sounds now, and [laugh], you know, looking back, certainly there were lack of opportunities in comparison to what might’ve been offered—I still had access to an awful lot of opportunity there, right.
If you were sort of in the top 10 of a graduating class that was ultimately 695, you got opportunities to take classes at Southern Illinois University in Carbondale. I got to take Fortran programming; you know. An instructor would come down from the community college once a week. We would write programs on these little punch-card interfaces. He would take them away, and, a week later, come back and tell you your program failed because the first card had a—
—period in the wrong place. But, anyway, I mean, you know, the fact is that I had opportunities to get college courses under my belt two years before I actually went off to Northwestern. But, still, you know, the perspective of coming from a city that is—that was at that point, you know, more than 95% Black to essentially an all-white university and being put into a house environment because they were oversubscribed. They had taken more students in that year than they could house. I was housed in an all-white fraternity house.
So, that jarring kind of juxtaposition of one day you’re in East St. Louis, and then the next day you’re in this completely different environment was one that I don’t know particularly what I was—how I was prepared to deal with it. But I was able to get past the homesickness, and get past the—you know, everything you sort of say and do—you have to wonder is it the right thing because you’re meeting with people who come from a completely different background. You know, I’m in a fraternity with people who I’m pretty sure had never seen a Black person face-to-face in their life, coming from North Wisconsin.
Larry, on that point, did you ever consider an HBCU?
Not seriously. I knew that I wanted to be a physicist from the age of 12 when I discovered what physics actually was. I’d always been interested in science, but just wasn’t at all interested in chemistry or biology. They were too icky or messy, and not—you know—more in biology, it was just rote, to me, at that point. And then physics came along, and I discovered, oh, this is terrific.
But in order to do physics, you have to have a degree that allows you to then go on to get another degree, you know, a Ph.D. And so, I had just not thought about college seriously, just that I needed to go to a good college in order to get into a Ph.D. program. And so, what happened to me was completely by happenstance.
Someone from Northwestern, then assistant dean, came down to recruit, and basically said, “I invite you to come.” And so, he said it to an auditorium of people but [laugh] I actually went to visit. And it was the most beautiful place I think I’d ever seen, right. It’s a campus right on the lake. At that point, there was an observatory that sat on a little promontory that went out into Lake Michigan. And so, at night, it would open up, and you’re looking out literally into infinity.
It was an incredibly romantic notion to think of having the opportunity to go there and study astrophysics, which was my original intent. And so, no, I never thought about going anyplace else because I understood that University of Illinois is—was sort of the top that we could imagine ourselves going. There was no hope of going to—you know, it wasn’t even a thought, literally, that you could go to an Ivy League school.
And the HBCU schools that we knew were equally inaccessible, right. I mean, they were the storied ones, right, you know, the Howard’s or the Spelman’s. It just wasn’t—you know—these were things that were out of range. They were out of bounds. You could go to University of Illinois because they would give you a state scholarship, right, and that’s what would make it financially possible.
And I just knew—like I think essentially every other student—nothing about the idea of need-blind admissions or, you know, need-based financial aid to fully meet the need, the financial need to go to college. And so, Illinois was it, right. That’s where you could afford to go because you would get the state scholarship that would fill in part of the money, and you would be able to make the rest by working. And that was the only reality that permeated, right, that anything else is just a pipe dream, right, and you may as well say you want to go to the moon.
Larry, you’re remarkably strategic in understanding even as a teenager that you needed an advanced degree to succeed in physics. I wonder if you were open-minded in terms of focusing on experimentation or theory even as an undergraduate in terms of what you wanted to focus on?
No, I knew I wanted to be an experimentalist, and there is a good bit of ego in that [laugh] in that the role model was reading about Einstein, right.
And so, I thought, OK, well, if you can’t be as good as Einstein—
—[laugh] why would you want to be a theorist, you know? And there’s a certain level at which I still think that. [laugh] But, you know, I understand that you can make a career in theory in many ways. But, to me, it was being an experimentalist, and contributing in observation is a tremendously noble way of doing things, and it’s also a concrete way of doing things, right.
Theory always struck me as something that if you did it—how would you ever know that you were right, right, you came through with a theory? And so, I had read about Einstein and, again, when someone asked him this famous question, you know, “What if your theory is wrong?” and he replies, “Then I feel sorry for the good Lord because [laugh] the theory is right.”
If the experiment doesn’t match it then, you know, the implication is God just made the Universe wrong. I could never see myself in that role [laugh], you know, having that kind of perspective on a theory that I came up with. And so, whereas an experiment, yes, if you do the experiment right, you know that you’ve done it right. There’s a feedback there that says you succeeded. You’ve made some progress.
Was there opportunity to pursue experimentation in cosmology at that period, or you were thinking more in terms of astrophysics? I mean, there’s different responses to when cosmology really matured as a respectable field. I wonder, as an undergraduate, as you knew you wanted to do experimentation, and you were looking out into space, not—you know—not accelerator physics, not those kinds of things, if cosmology was available to you, if the field had matured at that point?
No, it hadn’t. So, I came in 1979—sorry, 1975—for college. And at that point, I was literally told that, you know, cosmology is the field in which people are seldom right but never in doubt.
Right. So, it just wasn’t—it wasn’t considered to be an honorable, respectable field at that point, but neither was astrophysics. And so, I really was set on astrophysics, and I had as a freshman advisor, first-year advisor, Bruno Gobbi, who was an astrophysicist. And he said, “It’s going to take about 20 years for this field to actually—if you’re set on experiment—it’s going to take about 20 years for this field to be where you can do the kind of rock-solid ‘I did the experiment here’ success that you’re talking about.” And he was exactly right.
So, he said, “If you really want some solidity to what you’re doing, go down to the particle physicists. There’s stuff they’re working on.” And of course, ’75 was right after the discovery of the charm quark, and then the discovery of the tau lepton, and then, you know, a couple of years later, the confirmation of the discovery of the b. So, yeah, things were really happening there. Nobel Prizes were being distributed or, you know, they were certainly expected, and the high-energy physics group at Northwestern was heavily involved, right.
You could start right away with doing things, even as a first-year student knowing nothing coming in. And so, particle physics was a nice segue of 20 years until [laugh] cosmology became the kind of real solid, solidly based, experimentally grounded field that we now think of it as. And so, it was time to move over back, or back, to my original goal.
But, yeah, I mean, you know, in theory in ’79 with inflation, right, there was—there were already on the theoretical side these ideas that particle physics and cosmology were really closely connected, right. The beginning of the universe, those laws are all particle physics laws. So, I had never sort of lost track of it. It’s just that experimentally, it wasn’t quite there yet.
What opportunities did you have as an undergraduate to work in laboratory environments that might’ve been useful for your future research interests?
Well, it’s a story I tell as hopefully an inspirational story for new students who are thinking about physics, which is when I came. I was a fully financially aided student. And as part of that, I had to work, a work-study job. As you imagine, you look at the 400 listings, and most of them are dining hall attendants or stamping books in the library.
None of that was interesting to me. And out of literally hundreds, there was one job with the physics department. And I really didn’t care what part of physics it was at that point. It’s just like that’s kismet, right. That must be for me. Who else is going to want a job like that?
And I went, and I was literally 13th in line, the last person in line.
There was a line out the door for an engineer who was working for the high-energy physics group. The interviews were very short, so it went very quickly. I got in, and the interview was less than 60 seconds, you know.
“Do you know how to program a computer?” “Well, not really. I took a little Fortran.” “Can you solder, you know? Can you use an oscilloscope?” “Really, no, no, no, no, no.” “Do you know how to build anything?” “No.” And so he just said, “I’ll call you.”
And that was the end of the interview. And so, I left with my tail between my legs, and really convinced that—I haven’t been in college one week, and I’m already a failure, right. I can’t do the thing that I need to do to get even a work-study job [laugh] with the high-energy physics group.
But over the course of the next week, of course, he didn’t call. And I got really incensed that, at the very least, he should call me up and tell me as a decent person that I, you know, I didn’t have the skill set for the job. So, I screwed up every bit of courage that I had, and I went back, and I was going to force him to tell me, you know, “I hired somebody else. You’re not sufficient.” I knocked on the door, and very nervously poked my head in, and he says, “Oh, you’re back. I guess you’re ready to get started.”
Oh, wow. [laugh]
And I said, “Well, no, you said you’d call me.” And he said, “Let me tell you something. There are things that I can teach people, and there are things that I can’t teach people.”
“Everything I asked you, every person that comes in here every year, I ask the same set of questions, and none of them can do any of them. [laugh] But those are all things that I can teach. So, I tell everybody I’ll call them. I never call anybody. I hire the first person who comes back.”
That stuck with you throughout your career, I bet.
Yes, that’s crazy, right. [laugh] I mean, why would you just hire someone who comes back? I didn’t realize that he was saying that’s part of what he can’t teach. So that lesson came a little later.
So, after three or four days of learning how to solder on old circuit boards, the senior professor came in, and he said, you know—[laugh] so if you know him, Jerry Rosen, right. He’s like six-six. He had a goatee that looked like a devil, and he smoked this big stogie all the time, even in places where you couldn’t smoke. And he just came with this booming voice, and said, “I hear we have fresh meat.”
“Where is he?”
I timidly raised my hand, and he said, “Come with me,” and he took me to a loading dock that was filled floor-to-ceiling with 20-foot lengths of steel beams, and bales of gold-plated copper wire. And he said, “I want you to take all of this, and, in the next 18 months, I want you to make me 24 planar drift chambers for this new experiment I’ve planned out at Fermilab.”
And of course, he knew I had no idea [laugh] what the heck a planar drift chamber was let alone how to build it.
And so, he just cruelly slapped me on the back and said, “Some assembly required,” and he left.
So, it started coming into me now, that, yeah, only somebody who’s crazy enough to come back [laugh] day after day. So, I did over the next 18 months, very patiently asked questions, kept coming back every afternoon. And eventually we got all these chambers assembled, and I did all of the electronics for them, and the readout electronics.
And so it was, you know, at the end of sophomore year, you are there, right. You are part of the team, but with something that was ridiculously impossible to do if you’d simply said, “This is what you have to do in order to be part of this crew,” right. This is the job, is to figure out how to make circuit boards from scratch literally, right, from circuit design literally on pieces on paper to putting tape on plastic to exposing the copper-plated PCBs, and then actually drilling them, and soldering electronics onto them, and testing them.
And so, yeah, you have to do it all, but it was an incredible learning experience but also, just, there isn’t any better way to have someone feel as though they belong in science than to help them along, right. You obviously have to have someone who’s patient enough to ask you, you know, how to use a drill press. [laugh] But by my soph…by my third year, you know, I’m teaching master’s degree candidates in electrical engineering how to make circuit boards. So, you just build a very strong sense of your sense, of your belonging in the field, and as having some degree of expertise.
Larry, on the opposite side of feeling like belonging, I wonder if you came into this almost completely white environment at Northwestern sort of girding yourself for, you know, anything ranging from today what we might call microaggression, right? Somebody might assume you were there on a football scholarship, or something like that, or even, you know, this is the ’70s, maybe more overt expressions of discrimination. Did you have those experiences? Were those things that you had to deal with, and you expected them? Did you not have to deal with them, and you were pleasantly surprised? What were your experiences in that realm as an undergraduate?
Oh, you hear the N-word quite a bit. [laugh] There were people that were not understanding...I mean, they understood that if they used it at me, then that was a taboo kind of thing to do. But they certainly didn’t understand that you shouldn’t use that word altogether if as—particularly if you’re white. And, you know, that kind of racism is—was not subtle. But it wasn’t as though I didn’t expect it and I couldn’t deal with it, you know. People ask to touch your hair, and their curiosity around the fact that you’re Black was palpable.
But, at the same time, people were friendly, and so I had a role in the fraternity, and I eventually joined it, and it needed leadership, right. I mean, having someone with an understanding of physics is actually pretty essential when you’ve got 18-year-olds, two dozen of them trapped in a house together [laugh]. And so, you could assert leadership by saying it’s not a good idea to put a mattress in the basement level, and then jump from the third floor of the stairwell—
—[laugh] thinking that you’re going to survive without injury, or that you should figure out how to do house repairs by stripping paint with a blowtorch, right—
—which you may have seen somebody do that, but trust me—
—you know, we can find other ways to scrape and to use elbow grease.
So, you know, I had a chance to show leadership, and that was what they respected. And so, for a fraternity, you have to do your—mostly your own repairs to the house because your dues otherwise go to fixing the house rather than social events. And when I was made house manager in the—in my—I guess my sophomore year or junior year, one of those, you know, you would have these jocks, high…you know, football jocks come in, and you have to gain their respect. And so, you could find various ways to do that.
And one of the ways was I understood how much power a horsepower is. And so, the very first thing I would do, even though it’s actually the last thing you do in cleaning the house, is we would begin with me informing all these big guys that you have to eventually figure out how to polish the floor with the floor polisher. And it’s a one-and-a-half-horsepower motor, which I don’t tell them, right. But I actually just gracefully move this thing over the floor with a pad underneath it, and it’s very good.
And of course, someone who doesn’t know it—you pick the biggest guy—he tries to wrestle with it, and the one-and-a-half-horsepower always wins, right. [laugh] So he winds up on his butt after 30 seconds, and then you have people’s attention, like you have to say, “Here’s what you need to do [laugh] precisely, and if you’re not following this, then accidents will happen.” So, you kind of learn these things to gain respect from people, and that made all aspects of being in this social environment much more manageable for me.
In the work environment, it didn’t matter, right. People wanted to know what you could do, what you were willing to work on, and if you volunteered for things and then figured them out, then it simply wasn’t a question, you know. I don’t know what they thought of me personally, but, you know, I was valuable because I was cheap labor [laugh] that was effective at getting things done.
Larry, what kinds of graduate programs were most interesting and compelling to you in terms of the kind of physics you wanted to pursue as a graduate student?
Well, I thought very seriously that I should try some other things, but that I was pretty much going to be, you know, like 99% fixed on doing experimental particle physics. And so, I applied to places that had great particle physics programs going on. And I got into all of them, you know. And so, I think I was waitlisted at Princeton. But, you know, I got into MIT and into Stanford, and to Wash U. And it was tremendously—you know, University of Chicago is really—like, these were all dream places.
And it was really difficult for me to imagine that I would succeed in getting into them, and so I thought that this—the choice would be pretty easy. When it came down to it, though, making the choice really revolved around the fact that people from Stanford called me up and said, “We want you to come here,” right. All the others were, “You’re accepted. Here’s your stipend. Here’s what we would offer you in the way of coursework,” and that’s it, right.
They were just glad, or they assumed you would be glad to come, and I would. I would’ve been glad to go to any of them. But to actually have somebody call you up, and then to get a letter from Burt Richter, a Nobel Laureate, saying, “You know, I hear you’re interested in particle physics. So, when you’re here, look me up,” which I did. [laugh] And so not recognizing that, of course, you can’t just ride up to SLAC and go to his personal secretary and say, “I want to see Burt.” So, but you know—
Larry, at the time, did you appreciate the differences between the department of physics and SLAC, that if you were going to be working with Burt Richter, it would be in a SLAC environment and not within the department?
I didn’t really much care at all. SLAC was obviously, you know, a National Lab. But I’d spent time at Fermilab, and so I was kind of used to the environment, per se. I knew I’d have to commute up by bike every day, which was fine. But, you know, the part of it that ultimately affected me most—about the difference between them—was that we had to be supported for our stipends and our tuition from SLAC.
And so, it happened once that for whatever reason, the [laugh] person at SLAC who is responsible for transferring that down to the appropriate person in the physics department on campus weren’t speaking to each other, and so it didn’t happen. And I wasn’t able to register for classes in my second year, as were, you know, 25 other students. And so that was annoying, because you had to go back down to campus, try to figure it out, go back to work, come back down to campus again and meet with someone else. So, it was a lot of back and forth, and you figured it’s just got to be fixed.
It took several days, a week basically, and it finally got resolved. And I went back to register for courses, and Stanford said, “Well, you had to sign this promissory note in order to be—to not be dropped, right, because you got to register in order to maintain your status. And the promissory, you know, is a loan,” [laugh] which we didn’t realize quite when we were signing it, “and there’s interest. There’s one-week interest on this loan. So, you now owe us $1.57.” [laugh]
And so, I pulled out the $1.57, and I said to the person I gave it to, “This will be the last nickel Stanford University ever gets out of me because it just seems ridiculous you couldn’t forgive this.” And then for 20 years, I didn’t give anything back, you know. I have since then. But, yeah, that was the only time that I was really cognizant of the fact that there was this real, you know—and you would hear stories about the separation between the two, going back to, you know, the really old days of Hofstadter, and his separation from campus when they built the new accelerator up on the hill, as he always used to refer to it [laugh]—
—whenever he—he never used the term “SLAC,” right. “The accelerator on the hill” was all he would ever say.
Did Burt end up becoming your graduate advisor?
He didn’t, and so what his secretary told me was, “Well, you know, [laugh] he’s now running this group, and running the accelerator division, right. He’s a busy person, so you do have to make an appointment to see him. But he has someone that he really likes, and thinks is really terrific right down the hall.” And so, I wound up working with an assistant—then-assistant professor, Bob Hollebeek, and that was OK for a while.
But then eventually, I wound up with a second advisor, John Jaros, who was building a new high-precision drift chamber. And so, the very latest thing was to get this piece of hardware integrated into the physics analysis program. And so, he took on graduate students who were seen as having too much time on their hands, right. And so, I wound up having two advisors, basically, and essentially doing the equivalent of two theses in order to satisfy both of them.
How well developed were astrophysics kinds of questions at SLAC at that point?
Not very much. I mean, there were people obviously. You know, inflation started there, and that obviously meant that there had to be people who were interested in cosmology already around, but—
Did you work with Alan Guth at all during that time?
No, I had very little contact with the theorists, other than as practical calculators, right. [laugh]
They were people you could go to to get advice about how to calculate things, and they were very—I mean, they were tremendous, right. They would always help you. They understood that, you know, these things that you learned in graduate school were not complete, and you had to figure out how to actually put them into practical use in order to make Monte Carlo simulations.
But we were really driven by the fact that the experimental program was pretty much on the backs of the graduate students because if you remember the timeline—in the early ’80s, there was this—the PEP-II accelerator, and PEP—no, sorry, the PEP accelerator at that point. It wasn’t PEP-II. The PEP accelerator was considered—it wasn’t as energetic as the e+/e- accelerator in Germany. And so, people just assumed that there weren’t going to be really great discoveries.
There would be bread and butter physics, as it were, done there. And all of the senior physicists had to move on to leadership in building the linear collider, doing the design for that, and getting it going because that was seen as the future of the lab. So, it was a tremendous experience. But we had to run the detector for the PEP accelerator, right. We had to do everything, like keep it running, repair it when it needed, figure out how to do physics analyses, find, you know, topics that you were interested in.
And so, you could—you would get guidance from the senior professors, but they were really not the people who were actually doing the bulk of the work. That was all on the graduate students, who took tremendous pride in being able to carry it out. So, I would say it wasn’t a situation in which everybody would thrive, but I think the particular set of people who were there at the time found it pretty invigorating to have as much responsibility as we did for things.
And so, for me, it meant on my second thesis, which was looking for supersymmetric electrons, we could just change the trigger, right, something that would [laugh] require, you know, a committee of 50 and multiple levels of DOE review to do anything remotely like this today. I heard a talk by Lawrence Krauss and Mary K. Gaillard on a Friday, and, by Friday afternoon, we had figured out how to manipulate the trigger in order to look for single electrons, and we just changed it. [laugh] So, by Saturday, it was up and going. We hadn’t informed anybody really—just snuck it in and started producing a data sample. So, it was tremendously heady to be able to just do things like this and have responsibility for it.
In what ways did doing essentially two theses sort of really help for your career in terms of what you wanted to do at the next level?
Well, it gave me a lot of cache, I think, at SLAC. So, I got picked as the graduate student to go to lots of things, right. So, I got sent off to conferences to report on results. I went to, I think it was the second Snowmass meeting, as the student representative from SLAC and worked on the super…the SSC detector designs as a graduate student. So, I had lots of opportunities to actually know people.
I did meet—as it turns out, y future employers at Penn were there. Wally Selove and Brig Williams were, you know, senior people and important people at Snowmass in ’83, and I got to see them working. And I understood that, you know, the role of the graduate student [laugh] is to actually do the work, [laugh] while the senior people sit around and sip espresso and talk about the great questions of the day. And then they would give you, “Hey, somebody needs to go and check this out.” Can I do a Monte Carlo simulation?
And so, you know, they—it was just assumed that people would have imaginative ideas. But they also just had this kind of daring about things, right. I mean, if you think about what the SSC was in the early ’80s, it was just this idea of an enormous, absolutely enormous project, billions of dollars. And who actually thinks they can build something like that, right? Who actually assumes that they can figure out all the problems that are going to arise just technically, and make something like this work?
Not only how you can build this, but where you can build it. That was even up in the air at that point.
Yeah, absolutely. So, it was—that was basically a great introduction to the kind of mindset that you have to take with you, which is this is long-term. It’s going to take a decade—more than a decade and a half to actually realize it. And so, you’ve got to think very carefully about what’s going to motivate you for 15 years of work before you even start the science, and then hope that the science is actually interesting enough to be worth all of that, right, two decades of your life ultimately.
So, that perspective, I think, really put me in the mindset that it was possible to switch over, right. I had no—in 2003 when I made the decision to switch over to cosmology, you know, I had no standing in that field. I knew less than any graduate student who had taken courses. I had never even taken a course in general relativ—…I did have a course in general relativity. I had never taken special relativity. And so that is a pretty amazing thing to think about, you know.
The DOE took away funding because I was expected to go on to the LHC and didn’t do that. So that part of it, I think was all settled early in my career, which is that people think about what’s going to affect them for two decades, and they’re prepared to move on it, and make real lasting decisions about how their career is going to go on that basis. I don’t think I could’ve done that if I had been trained in kind of, you know, condensed matter physics or something like that.
Just having the daring to say, OK, this is important enough to me that I’m going to stop where I have some expertise and I have some—you know—people know who I am, and I can join onto things pretty readily. And I’m going to join this whole set of people that I—about half of whom I did know because there were other particle physicists who were moving in the same direction. But, you know, most of the people don’t know me if they—if they’ve only been in astrophysics, and I don’t know them. And that’s pretty scary if you sort of think about it, even if you have tenure, because you have graduate students, and they need things to do. And so, I think I was put into that mindset early on by the—what I discovered in the Snowmass process.
Did you have for your formal thesis committee an oral defense? Were the two theses that you had, were they reflected in those, you know, singular administrative environments?
No, it was really only the one that had to do with the drift chamber because that was considered—that was—you know—that was considered the most important question to answer at the time. So, the context was that we became basically a lifetime science factory, right. We could measure the lifetime of the tau lepton. We could measure the lifetime of the b quark mesons. As it turns out, it was measurable even though we thought it wasn’t.
And so, as a graduate student, I was given or allowed to take on the task of measuring the charm meson lifetime. And at that point, there was this spectator quark model which gave you a rough value of around 10 to the -13 seconds. But there were two experimental measurements: one made in bubble chambers, which was quite a bit longer, about six 10 to the -13, and one made in emulsions for fixed-target experiments. And that one was coming out quite short.
Now, everybody understood that there were systematic biases in these measurements because the bubbles have to grow to a certain size before they can be photographed, so the lifetime can’t be too short. And the emulsion—the further you go, the—it’s a three-dimensional problem. You have to look for vertices in this block of emulsion. And so, if the lifetime is too long, you’re not going to see it because, you know, it extends beyond where you can actually have people search in a finite amount of time.
So, nevertheless, there were people on both sides who were saying, “We know what the systematic errors are, and we’re absolutely right.” So, for me, it was the first time I’d seen in physics people actually arguing in public, right. And so, there was a Science News magazine article in which there were letters to the editors in which these two groups were insulting each other personally—about this measurement.
So, everybody was very, very much concerned about this, and this was a measurement you couldn’t do at the DESY synchrotron, right, because we had the vertex chamber. So, there was a huge focus on knowing what that answer is, right. They gave us all of the computer time, basically, [laugh] to analyze the data for the Mark-II experiment, which our other graduate students were not too happy about [laugh] because they had to wait two months on their own PCs.
So, that was the important part. Whereas the supersymmetric electron...the first time I, along with my graduate student partner, got up to talk about the paper for that, Martin Perl, who of course, was to become a Nobel Laureate, said, “Before you start, I want you to change the title of the paper. Take ‘supersymmetric’ out.”
And I said, “But, Martin, it’s a search for supersymmetric electrons. [laugh] If I take ‘supersymmetric’ out”—
—“there’s no reason to have done the search.”
And he says, “I don’t care. I think supersymmetry’s just a trend, right, it’s just a fad, and it’s going to go away. I want to have my name on papers that are going to last.” And I said, “Well, I can’t do that.” And he said, “Well, take my name off the paper.” And he got up and walked out.
And so, my partner said, “Can he do that?” [laugh]
“Yeah, absolutely. We just go on, right. I mean, you know, everybody else is still here, so we continue on.” So, you know—
Larry, just to fast-forward in supersymmetry, looking back, was Perl—not in the way that he acted but just scientifically—has that reaction aged well, do you think?
Well, you know, ultimately, it wasn’t a fad, right. It’s still around. But, yes, of course, I mean, to the extent that he might’ve believed that it’s actually not a symmetry of nature, it certainly has not appeared in ways that it should have, really by this point, although there are still ways around it. So, yeah, I do think that there was a part of him which was right, which is, ultimately, if supersymmetry doesn’t turn out to be a correct idea for solving the problems that it claims to solve—which it doesn’t appear as though it can easily do at this point—then, yeah, he was right about that.
But I think what was wrong about it—which I recognized at the time, and I still believe is true—is that we’re experimentalists. And so, we have a motivation for doing a search, but the search itself is what stands, right, that we are actually looking in an area for examination which has not been seen before. And in many of the cases in which you do that, you’re not going to find anything new, but that’s the life, right.
I mean, it’s the surprises that come along that are really worth the 20 experiments you do and searches in which you don’t find anything. But I was very glad to actually have a measurement. And so, in my view, it was terrific to do both, right, exploration but then followed up with something that’s actually a measurement of a known effect for which you really just need to know what the answer is, and you’ve made progress in figuring out how to do that.
Larry, at the end of your graduate career—it’s always interesting in terms of the interplay of the experimentation and theory. Did you feel like with both of these research endeavors, was—were the implications of what you were finding, was it the situation where this was resting on theoretical foundations that made these experiments possible, or were the experiments really sort of driving the agenda, and then the theory advanced on that basis?
What we understood was that the experimental observations have ramifications which go beyond the theory, and certainly that was the case. And so, I was working very closely with a friend of mine, Nigel Lockyer, who is of course now director of Fermilab, and he was expected to do the lifetime of the b quark because the expectation from theory was you wouldn’t be able to see anything. You wouldn’t be able to measure it at all. And so, it was seen as the riskier chance to take, and that’s why a graduate student didn’t do it, right. I was supposed to do the measurement for which you knew, there was going to be an answer.
And then Nigel, of course, discovers that, oh, [laugh] we can measure the b quark lifetime. But it was understood that that made possible a whole range of new experiments with B-colliders, B-factories, that wouldn’t have been considered possible before. So, I think we understood that that aspect of not being dependent on the theory too much was an important one, because nature does still have surprises, and the follow-ons are really the important parts of what your career is built on, right. That there were people, like the discovery of jets, who could then go on to measure jets for the next 20 years, right, if they wanted.
But really, the expectation was you do an experiment, it kind of leads you in a new direction, and that direction is not one that you could’ve anticipated just by looking at theoretical papers. Like, maybe you could have, but really, it’s the fact that, hey, you know, the technology has taken us further than we thought, or it gives us a new idea for a new kind of technology that is actually pretty important—that kind of leads you. So, for experimentalists, that is really the romantic notion, I think, that we’re not just cutting down theories.
There’s some fun in that, but really that’s not what drives us. I mean, I think really what drives us is that we’re looking in this area, and we’re seeing something for the first time. And that’s what’s going to lead us to the next question that then takes you on to even more either fundamental questions or just more interesting aspects of how to build things.
Did you search pretty widely for your next postgraduate postdoctoral opportunity, or were the connections that you had already developed at Penn sort of put that opportunity together for you?
No, I looked, you know, I had an offer from Stan Wojcicki to stay at Stanford. I had offers from the University of Chicago and then Penn. I wasn’t convinced that I needed, you know, to look in very many places. So, I gave a talk at Berkeley, but I was pretty much of the mind that was too close to home, and I wasn’t going stay in—on the West Coast, and it was a good idea. But the expectation was that everybody was going to go to CERN, right, that—and I had that in mind. And so, when I went to Penn, I wasn’t there with the idea that I particularly wanted to stay at Penn, but there was this question. Are you going to stay in the US or are you going to go to Europe? And everybody says Europe is great, but that’s not where you’re ultimately going to get your permanent position. So—
And Europe, CERN is great specifically for the field that you’re pursuing, or just generally CERN is—it’s a great place?
Just generally—just generally, CERN, it’s just a great place to be. And, you know, everybody goes there, and they get their European experience, they get to know an international community, you know, you sip lattes [laugh], you have great views in the mountains, tremendous meals, and so it’s kind of a reward for having done a great job as a graduate student. But as a postdoc, it’s not really advancing your career that much, right. You’ll do work, and that work is what you build on with your next postdoc—
Now, are you a bachelor at this point? Is there a two-body problem to contend with at this point?
Yeah, I’m a bachelor at that point, and pretty confirmed [laugh] as a bachelor. But as—you know—as a postdoc, I could go anywhere I wanted. But really it was the idea that, yeah, get started on your career, right. What you want to do is to get into a faculty position, and so the faster way to do that is not to do two postdocs if you have to...unless you have to, but really to be in the US and start making connections at universities that are actually going to hire you.
Now, at Penn, was there an informal understanding that if things went well, the postdoc could turn into a faculty position?
Well, you know, oddly, my perspective was that they treated postdocs [laugh] better than they treated assistant professors. [laugh]
So, I mean, I was literally told that the purpose of the assistant professor is to assist the professors. [laugh] So they—you know—they took them in, and they fired them or didn’t give them tenure, and so—
That was an issue at Penn. There was a problem that—of not promoting from within.
That’s correct. But, you know, that was true everywhere, right, among the Ivies. It wasn’t unique there. But as a postdoc, I was told very pointedly that “you do not work for Brig Williams, right. We, the high-energy physics group, hired you out of the set of people that we saw. And so, he might be sort of directing you on CDF, but you should do what you think is the right physics to be working on.”
Uh-huh. Did that create a tension for you right out of the box; between where you would expend your energies?
It didn’t create a tension directly, but indirectly, yes, because one of the reasons that I really was attracted to Penn was that that’s where Nigel went, right, after his postdoc. And Nigel said, “I think it’s a great place, right. I mean, Chicago’s terrific but, you know, I think this is better.” And so, I came there expecting that I would work with Nigel, as a postdoc, who was then working with Brig, as a senior professor. And literally the summer after I got there, I came in April, and by July, they had split, right. They were still both on [laugh] CDF—they weren’t working together—but they’d taken on this major project for part of the trigger. And that all fell to me then, right. Neither one of them wanted to work on it because neither was going to get complete credit for it, and so it fell to me to do.
And in retrospect, it was way too much effort. I mean, I think the responsibility part was OK. But the effort on doing this one project was just—it was tremendously difficult, right. At Chicago, had I gone there, I would’ve had one circuit board on the trigger because that—Chicago was responsible for the trigger system. You know, it was one board for a postdoc.
In the project at Penn, I had five circuit boards, major circuit boards, you know, things like this [laugh] by this—to design, to test, and to implement. And there weren’t ,you know, there was supposed to be another postdoc hired, one that would work with Nigel and us. And Nigel worked—had a postdoc but was working on a completely separate project. So, I was the only one on the project, the only postdoc ever actually.
So, in retrospect, you know, it was probably not a wise idea to be so independent and to have somebody senior look out for you and say, which, you know, they did come along and say, “Look, if you want to quit this, and work on something else, that’s OK. But, you know, since you’d already promised to do this, you know, it’s up to you whether to break the promise [laugh].” You know, the language was pretty clear on it, to me at least, which was, “No, you know, you don’t get—it’s an ambitious thing.” But this is what I just learned from the Snowmass process, right: that you take on huge projects, and you figure them out, and figure out how to do them.
Larry, what was Brig Williams’s research specifically at the point that you joined, and what was the state of the CDF project at that point?
So, in 1985, CDF was still not finished. It was not constructed. But there was enough there that they could test runs. And the Penn group had just joined, so we needed to elbow a way into the process of building part of the CDF detector that would give, you know, enough responsibility to be worth the effort to DOE, but would also not take you away from being able to do physics right away.
And so, Brig had just moved over from running at Brookhaven—in fixed-target experiments—and finishing up the last of that work and being—I think at that point he either was or was just coming off of being chair of HEPAP —and so he was basically the person that was responsible for shutting down ISABELLE, right. I mean, he led the group that came to the conclusion that ISABELLE was not—that Fermilab had made enough progress with the Tevatron that ISABELLE was going to be overtaken just too swiftly even to be worth the investment. So, he really, you know, was also new into moving into the CDF environment and carving out a space that was relatively important. But that also meant that we didn’t have things that were guaranteed and promised to us, right. We were coming on as sort of the second set of universities to join up and having to find our place.
And what about the other, or just generally, your work in high-energy physics with the group that, you know, wanted you to be part of what they were doing, and not just exclusively working on what Brig wanted you to work on? What was that research?
Well, you know, in the end, I got so taken up with the projects that I was on, I wasn’t actually able to [laugh] do anything else. It literally was working day and night to try and not only produce the hardware, but also be consistent with starting up a physics effort, a physics research…a physics analysis effort. And having to do all this while you were remote from Fermilab, right, where—I mean, in my view, people literally thought if they didn’t see you, you weren’t working—because they are seeing each other there working feverishly to get CDF ready for the Tevatron to turn on at full energy.
And, you know, there really wasn’t any room to work…we had great things going on, and I would talk to people who were doing tremendously interesting things obviously with neutrinos. In 1987, 1987A came along, and of course, you know, Penn had a big role in building the—that acquisition system that was able to receive all the neutrino events from the supernova explosion. So, it was great to talk to the engineering people in the group. But really, there just was no time to really sit down and try and figure out how to be part of any other analysis that was going on, or really to even get that deeply involved in their physics, right. So, you know, the CDF was all-consuming, and I wasn’t that interested in searching for the top quark, which was the thing that all of the young Turks that were really fired up to make their mark were all focused on, and so—
So, people like Melissa Franklin or Peter McIntyre, you didn’t work with them so much?
No, because I really didn’t want to be in the mix of this place where there were so many people jockeying for position on being able to discover the top quark. So, we had a top quark effort at Penn—that I think was pretty robust—and Brig spent time on that. But it wasn’t the thing that really intrigued me because there were so many people working on it, and there was all this other physics going on.
And in particular, you know, having seen what Nigel was able to do with bottom quark physics—with b physics—that really was sort of in the back of our mind as the place where we might make some headway because, again, theorists don’t think that there’s much more to discover there that they don’t already know. And that’s kind of ripe for [laugh] tearing into because it means that there’s not a huge amount of bias, as to anything that you might find there that’s surprising. And so, ultimately, when my group did the first exclusive b decay reconstruction in the hadron collider environment, it was based on the fact that people thought, ah, you know, theory tells us it’s [laugh]—we’re not going to find anything, or at least it’s going to be really, really difficult.
But it turns out that if you look, yeah, it’s actually not that hard [laugh], right, really. It just really requires somebody to say, “Look in an area where people haven’t looked, and you’re sure to find something interesting in many cases.” But, you know, to be as interesting as it was, which was all these b measurements that people thought you could only do with a B-factory with e+/e-, you can actually do some of them with a hadron collider, which really, you know, made a lot of other things down the line really possible.
What were some of the major research questions that compelled the creation of CDF, and how might those research questions have changed over at least the course of your involvement with CDF?
Well, at the time, you know, in 1983, we were being told [laugh] by Sheldon Glashow that “you’re going to discover the top with a mass of 20 GeV, and then the Higgs [laugh] boson, these are all going to be discovered before you even get your Ph.D. It’s all going to be done.”
And so, there was a lot of drive to say, OK, well, you want to be part of these because there’s the possibility that the Higgs or the top could wind up in our data set. And then quickly it began to be clear that, you know, for the first set of data that comes in, just like with supersymmetry at the LHC, right, it’s not there, right. You would be seeing signs of it pretty early on.
So, we got somewhat discouraged, but then once we understood that we could do a lot more with b physics, then a whole bunch of other topics around b physics kind of came in, right: the idea that you might actually have a chance at looking at CP violation, which turns out it was still really difficult to do. But just given the fact that you—the b quark seems to be surprising, right. There are two major surprises about its properties that we didn’t really expect, and then it happens.
But then there was just—you’re at the energy frontier, right, and so you really ought to just feel free to be looking for things that are unexpected just because you can. And so, whether you’re interested in leptoquarks because there’s a theory behind them, or technicolor because there’s a model behind that, or you just want to start looking for long-lived particles because you don’t know whether or not there’s some other aspect of it that people haven’t thought about that’s out there. I think it was that kind of pure exploratory drive. But there was definitely the situation at the time that we have to justify the existence of the Tevatron, and the investment in it, by finding the top quark.
Was your sense—
Like, if we don’t do it here, it’s going to go to CERN.
Yeah. Specifically with the Higgs, or maybe you can just speak generally, was there a spirit of co-op…of competition with CERN at that point that this was either going to be discovered at CERN or at Fermilab, or was that sort of too early for those kinds of considerations?
It was too early, and of course we had all thought we were going to be blown out of the water by the SSC, right. So, the SSC was going to do all of this, right, the top quark, the Higgs, supersymmetry. And its original start date was 1999, so [laugh] really there was just the anticipation that you do as much as you can, but CERN is going to come on way too late, and if the Tevatron hasn’t found the top by the time the SSC comes on, you know, it won’t have been worthwhile to have even done that.
So there—the spirit of competition was really that we have to do a very thorough job, right, of understanding what we can. And I think there was maybe too much credence given to theoretical predictions at that point, particularly around supersymmetry, that we have to see something. And so, the race was really to get this before it’s all cleaned up by the next machine to come along, whether it was in Texas or Europe—didn’t matter.
Now, how much were you spending your time in Illinois versus at Penn? Was it sort of fifty-fifty or were you mostly in Illinois at this point?
Well, it was mostly in Philadelphia because after three years as a postdoc, I became an assistant professor, so I had to start teaching. And so literally you would fly to Fermilab on Thursday morning, take the red eye in the morning, and then you would fly back Thursday evening in order to teach on Friday, so, you know, on Monday, Wednesday, Friday classes. So, it was a pretty intense kind of a lifestyle for a while, which was, again, OK until I got married in 1992.
But it was all normal, right. I mean, there wasn’t any expectation that it should be somehow easier for you, right. We didn’t have the remote technologies in which we can do things by Zoom. Teleconferences were still a pretty dicey affair. I mean, they worked but not reliably enough. And then you just needed to meet with people, right. Face-to-face meetings were still important, as well as, your graduate students.
So, you would station graduate students out in Fermilab for long periods of time, and then you would see them one day a week [laugh]. So, that’s just the way it was. Postdocs would basically do what the faculty did, which is to fly back and forth as often as possible.
What were the circumstances surrounding the offer to join the faculty?
You know, I don’t really know. They always liked me at Penn, particularly the senior faculty, and so in their mind I think it was set in stone that, you know, I would join and then I would get tenure. The circumstances by which I got tenure is I got a tenured offer from UC Irvine, and so that moved the timeline up. So, I was promoted early, and, at the same time, they wanted also to keep Pekka Sinervo, right, so they had two assistant professors both in particle [laugh] physics, both getting tenure in the same year, which, you know, was completely unheard of, right.
So, that much I think was partly luck, and just being in a situation where people knew what they wanted, and they had settled on the two of us. So, I don’t know what the back discussion was, right. It’s just that, you know, my teaching was going really well. The experimental work—I think had a lot of promise to it because of the b—the work with the b meson. And so, at some point, you realize, OK, we turned down a lot of people who went elsewhere [laugh] when they were assistant professors, and so changing the trend, I think, maybe it was also an important thing to do.
Larry, did you get involved with diversity and inclusivity issues at Penn early on, or that came later, as you became more senior in the department?
As soon as I got tenure, I joined onto a lot of teaching efforts that were related to being able to diversify the undergraduate population at Penn. And so, one of the things that took up a lot of time and effort was this sort of academic boot camp—that took place in the summer—in which I did team teaching with someone from chemistry and somebody from mathematics. So, we did a lot of preparation, which, of course, in the summer is the time you’re supposed to be working completely on your research.
But it was important to me to understand that we lose a lot of diverse students in the introductory classes, particularly in the sciences and engineering. And so, it was really important to me to have some contribution to that, and so I did it there but, no, I wasn’t involved in mentoring other faculty. For a very long period of time, I was the only Black faculty member in the sciences at all at Penn, and so that weighed on me.
But it was very clear that, you know, as a university, we’re just not making an effort to bring people in. So, when I was asked to serve on committees, you know, I would turn them down because I just didn’t think there was a university commitment to actually doing anything. And if there were, I wouldn’t be the only one.
Now, when you say that, you know, this—your involvement came after tenure, was that a strategic decision on your part? Did you feel like you needed that level of security before you wanted to turn your attention to these issues, or that was not really part of the equation?
I was completely fearless. People would tell me, you know, “Direct your energies here. Don’t do this,” and I completely ignored it. No, the tenure part was that I got married that same year, right. [laugh] So it was a pretty momentous year. So, I got tenure, I turned down the offer to move to UC Irvine, and I got married.
And at that point, I had to just sort of make a decision, right. How much time am I going to get to spend chasing things at Fermilab, and how much am I going to spend in Philadelphia with efforts here? And so, it was pretty clear to me that, you know, I have to spend less time at Fermilab, and more time in Philadelphia, you know. And, consequently, if I’m going to spend more time in Philadelphia, I’m going to dedicate it to working on things that are actually intending to help students, particularly students of color.
Now, obviously, these things were of concern to you long before you got tenure. But I’m curious, when you started to devote yourself to diversity issues formally and at this level, what were some of the things that you saw were like low-hanging fruit, things that could be pretty easily dealt with, and what were some of the things where you said, you know, “This is going to take a lot of work. It’s going to take a lot of people. It’s going to take a lot of time”?
So, I’ve always been of the belief that things that you do to help improve diversity should also improve things for everybody else. That they’re not exclusive because if they’re exclusive, then they tend to, you know, frankly just not be good quality, to tell you the truth, because they’re, you know, they’re remedial or they are born of a belief that you have to fix people as opposed to fixing your systems. So, I also got involved in a lot of teaching.
So, we needed to revamp our teaching labs. And so, at the same time I was doing these things for what was called the “pre-freshman program” and talking about mentoring students, I also wanted to improve just the general physics introductory physics sequence altogether. Now, the teaching part of it in a lecture was OK, but I think the labs were completely not OK, right. There were still metersticks and so forth.
So moving around to making use of the latest physics education research in how to give hands-on experience to students: get them arranged into thinking more and not listening, and taking things on, and computerizing the labs, and figuring out how to make it relatively easy, to have what looks to the faculty like a canned lab in that it has very little chance of failure, and doesn’t need terribly sophisticated people to constantly be tweaking it, but on the other hand looks to the students as though it’s more exploratory, was a tough buy. But that also got recognition at Penn. So, when Judy Rodin came in as president, she took a half-hour out of her incredibly busy schedule, and she came down to see these things that I and others—another professor—had put together for how to revamp the undergraduate freshman first-year teaching for physics. So, it was understood that there was attention being paid to doing these things. But, in the back of my mind, if we improved these experiences for everybody, this also is going to help students who are underrepresented here have an easier time connecting to the subject matter, and maybe not—you know—not washing out as quickly in quitting before you’ve even finished the course, right, before you’ve gotten to the second mid-term.
What opportunities—in terms of how diverse the undergraduate population at Penn was—were there for you to serve as a mentor or a role model to underrepresented groups who would be sitting, you know, in these large lecture halls—who might’ve looked at you and said, “Maybe that’s something that I can aspire to myself”?
So, I had been working for a long time with administrators, and one administrator particularly in the engineering school. We just didn’t have very many students of color at all in the basic sciences. But we had more in engineering. And so, the focus for me was really to try and work with them.
But working with them had two branches to it, both of which probably required more of me than I was able to deliver—because I was doing both of them. So, one is get them engaged in research—that was my lesson as a first-year student—and so always having a bunch of students working with me in the summer. And I didn’t choose them that way. They came to me. But they would almost always be Black or Latinx. Very, very few white students came on.
But that wasn’t a conscious choice. That’s just who saw me, and, you know, the advising that I would be doing along with the engineering school. The other branch was outreach actually, and teaching students, undergraduate students, that they had a role to play in actually providing a pipeline from high school of more students, and girls in particular, into the sciences. And so, for a number of years, I also had a program in which—every Saturday we had classes for 90 to 120 middle school students—middle school through high school students—and I was the lead on that.
Penn gave me a bunch of money, like a half-million dollars, to spend on hiring instructors from other nearby universities, Drexel, and Temple and so forth. And the model we—I didn’t develop it. It was a model that was developed at Lincoln University, but Penn was the silent partner on funding it, and I was the lead instructor for it. It was to have a professor partnered with a high school teacher of science from the Philadelphia school system, and almost always from the West Philadelphia schools. And together they would come up with a curriculum in areas of biology or chemistry or engineering and math, and I would do the physics and engineering pieces.
And so, students—we would recruit undergraduate students to help with hands-on activities for those students, right. There’s no lecture, whatsoever. Everything was experimental approaches to actually understanding things. And the students, the undergraduate students could be quite daring with that, right. I mean, they could come up with all kinds of interesting analogies and things to do with students that would keep their attention because, you know, you have seventh graders in a classroom for three hours [laugh].
But, you know, ultimately, that was a huge amount of effort. I think all the students got something out of it, you know. I still hear back from some of the high school students, and even actually from one of the middle school students 20 years later, 25 years later. And so, I think there were two ways of getting people connected —the undergraduates—in doing this.
Can you talk a little bit about the Physics 590 program? It seems like such a unique curriculum. What were the origins of that, and what was your involvement with it?
So, there came a time in the late 19…you know, late ’90s where you just decide you don’t have enough energy to put together [laugh] an entire school for 100 students every Saturday. I mean, literally, we were—we would build the computer lab starting at 7:30 in the morning—
—have it ready by 9:00, and then break it down at noon. So, you know, as you get older, you start thinking are there ways in which I can have greater impact but without having to double the effort which is already impossible to maintain? So, working with teachers was a great way to do that. Surprising to me, the chemistry department had actually gotten an NSF grant to do that, and it was the most unexpected department on campus to actually be involved in outreach like that. But they did have teachers who were ready to do it, so they had started a master’s degree in chemistry education.
And then the idea came along that why couldn’t we expand this to other science teachers because there were only so many chemistry teachers within the district, which you’ll saturate at some point. And so, I was recruited for physics. The people that I worked with on this pre-freshman program in math and chemistry were recruited to those programs. And then a biology teacher was recruited to do the biology teacher’s part of that.
So, with the Physics 590, we had to learn a bunch of new vocabulary, right, from actual education research and training. And so backwards designs kind of came into our vocabulary. We discussed a huge number of things about how to rearrange our expectations for what we thought students, who take a course, should know when they’re finished. And when you translate that to here’s how we have to train teachers, so the teachers are making these expectations, it turns out to be pretty convoluted in a way.
But it seems much more natural, which is that the challenge that we give to teachers involves both respecting the fact that they are experts at teaching, right, and we are not. We’re professors. We profess. We don’t really teach so much. But, at the same time, we are the content experts, and so what we want is to raise the bar for them on where they think the understanding of the content is sufficient because there’s a certain aspect of it in which—and I learned this from having worked on many coding projects, right. There’s a certain level at which you know just enough to be dangerous, right.
When people learn C++, they want to use every feature of the language, and they make code that’s absolutely impossible to maintain. And then as you learn more, you become more comfortable with not using all the bells and whistles and concentrating on just the things that are necessary to make the code actually function the way it’s supposed to. But teaching is the same way, which is if you don’t know as much content as you want, then you stick to rules.
Like, here’s the way that we do this, you know, a titration, or here’s the way that we carry out a completing of the square. And those rules are complicated for no reason, right, because you don’t actually understand what it is you—a deep understanding of what it is you’re actually trying to get the students to understand at the end, which is not to complete the squares—you’re going to forget—which is it’s the mental manipulation of extraction in dealing with letters that represent numbers. And so, what we wanted to do was to get them into that middle point, right, which is you don’t have to be content experts at the level that we are for this, but you do have to be at the point where you understand there are rules which are way too complicated for what you need the students to do.
But, more importantly, you have to give the student a rationale for why to learn the rule, right. What’s the rule really for? What are they actually supposed to be getting out of it? So, 590 was developed with that in mind on the basis of a lot of studies that had come through from actual teachers, but also people who had done education research.
The pipeline issue is so important going all the way to, you know, really middle school. I wonder on the graduate side of things what opportunities you had as a mentor to graduate students to reinforce the importance of diversity and inclusivity at that level of education?
So, there were, I think, tensions in my mind about how much to try to involve graduate students in that because I really thought that as a graduate student, your focus has to be on getting your achievements in research really firmly established for yourself. You know, the rationale for this is that, ultimately, if you split your time as a graduate student, it takes you more time to get through. And I was very much of the opinion that it takes too long to get through your graduate career already, because you’re prepared long before you’ve got your thesis finished to actually go out and start doing research as a postdoc, right. You’ve learned a lot of skills, and you’ve seen a lot of research activity practiced by people who’ve been doing it for a long time—you can take that and start doing your own work.
And so, you really need to start leading on the research, I think, fairly early on. The really—the leadership part is the piece that is hard to learn. And so, I think what we did effectively at Penn, even in comparison to other places that, you know, might’ve had stronger graduate students from the physics perspective, is that we generated people who were able to lead as graduate students, and give them real responsibilities.
And if you look on, you know, at ATLAS at LHC, you know, you’ll see from the 2000s on that a lot of Penn graduate students were leading subgroups or even being conveners of really large groups of people. And, really, I think that leadership piece is where the graduate students learn what they need, so that later in their career when they do actually start to take up issues in diversity, they do it from the perspective of leading people rather than following somebody else.
I want to ask about your work for the BaBar collaboration. How did that come about?
Well, I pretty much thought that I’d done as much work as I could do on CDF. Effectively, we were going to have to get involved with the Tevatron upgrade, and it just didn’t seem as exciting to me. And I also still had in mind that I wanted a closer connection between the particle physics that I was doing and cosmology.
So, the CP violation problem is definitely a piece of cosmology, and so I thought I’m more motivated by this. But, more importantly, there—you know, every 10 years, I kind of figure I had to take a really big break. You know, it’s not that I intend it that way, but it takes me about that long before I decide I really want to do something that’s pretty daring. And moving to an experiment in which Penn was not a part—we did not have, you know, an existing group that had a senior professor already in charge of it—was important to me.
So, I got to work with people I’d worked with in graduate school. That was important. And it was a familiar territory to me, right. But, at that point, CDF and Fermilab were just not—they were not places I really felt were in my future, and I wasn’t yet prepared to go to CERN because I knew it was going to be a long time before the LHC came online. So, it was a great adventure basically to just say, all right, I’m striking out on my own, and who knows if this will work. But the physics part of it excites me more so than continuing to work on top quark physics or even b quark physics there, and the limitations that we did have.
And in the late 1990s and early 2000s, is this really the time when there is this merging of particle physics within or into cosmology? Is that really when this starts to get going?
Yes, that’s right, yep.
And did you feel like—I mean, who were some of the key people who were with you as this—as these developments were happening? Who were some of the key people that made this a reality?
Well, you know, they’re of course the people who kind of led things. But really, it centers around UC Berkeley for me, right. And so, you had an incredible cosmology group there, plus you had people like Saul Perlmutter, who had kind of a high-energy physics background, who were working there. So, when I went there in 2003 on sabbatical, it was my first sabbatical, and still only sabbatical at this point—
—it was definitely the idea that I wanted to not only work with the BaBar group there but with the cosmology people there. And so, for me it was people like Mike Levi and Natalie Roe, who I had been in the same group with on Mark-II, but had moved on to thinking about the cosmology aspect because the lab had seen that they really wanted, very strongly. And then meeting people like Saul, who was—I mean, I don’t know if you’ve talked to him but—
Right. So, just a tremendous intellect who can talk forever on almost anything but—and a very even keel, right. So, the people in particle physics who I had grown up with were very fiery and very contentious, and they had grown up in the German model in which you insult people in order to begin a conversation.
And Saul was this kind of person, it didn’t matter, right, whether you knew anything about cosmology, you—first of all, if you knew a lot about cosmology, you could learn from Saul. If you didn’t know anything [laugh] about cosmology, you could learn from Saul. But he also thought that he could learn from you, right. I mean, he really internalized this very easily, I think, for everybody that worked with him. And, consequently, working with that group, I started in September, and, by December, I was spending, you know, [laugh] 99%, literally 99% of my time with his group, and with—and Natalie’s and Mike—and Mike Levi’s group—
And this is how you got involved with the SNAP simulation team also?
That’s how I got started, right. And so, January, it was, OK, you’re not spending any time with BaBar people, [laugh] so that’s not working. So, LBNL, you know, put all its money into having me work with the SNAP team. But if you’re going to do that, do some real work with then. And so, the simulation effort started up there.
And were you focusing specifically on supernovas and ideas about an accelerating universe? That was part of this research endeavor?
Yes, yes, absolutely.
And this was—this is really new for you at this point, really going into—
—these cosmological issues?
It was not only new for me, but the whole approach was expected to be very different—because I think, you know, being a particle physics lab, or at least having a big particle physics group in the lab, meant that we were approaching cosmology with that mindset of how we do teamwork. And so, there was a certain level of professionalization to coming up with this simulation, you know. When I came, you know, I don’t think it’s insulting to say it, it was just the situation we had there.
But people were talking about building a billion-dollar satellite on the basis of a simulation. And when you say, “All right, well, show me where the simulation package is so I can load it onto my computer,” it turned out to be not a package. It was a process. So, someone [laugh] would generate an ASCII file, data file, in Fortran, and they would send it to somebody else by email to someone [laugh] who would then run, you know, IDL and generate another ASCII data file and then send it [laugh] to somebody else who would run C++.
So, just, no, we can’t do it that [laugh] way. We have to actually have a body of software that is evaluated, tested, it has regular updates. And so, we sort of brought all those things into work that wasn’t really as familiar to cosmology as it had been for high-energy physicists. We decided to do a brand-new language. Everything was made with Java, which nobody knew, so we had to teach ourselves, and learn basically from people in Silicon Valley the sort of best practices for object-oriented programming—the right way, as I say, as opposed to the C++ way—that BaBar had adopted, which was a mess.
So, everything was a challenge, and everything was new, and there wasn’t a whole lot of time. But it was tremendous fun because we could—you know—we didn’t have limits. We sort of had to design what we wanted, and then figure out how to make it happen, and then put it together in a way that could look convincing in the end for an experiment to go forward as an idea, as a concept.
It sounds culturally like this is a real—first of all, it’s a very different kind of research environment than an experimental particle physics environment. There seems like there’s a real frontier mentality where everybody is just really making it up as you’re going along.
Well, I wouldn’t say, you know, that they’re making it up. But it’s definitely the case that they had no idea about blinding analysis. I mean, they’d heard of them. [laugh] They knew them. But it just wasn’t done. There was a real—I’ll probably have to correct this word anyway [laugh] if you send me the transcript.
There was a kind of casualness about how to do analyses that were pretty important in terms of their answers—not that they did them wrong but, for example, it just took forever to get the results out, right. And so, they were working in areas which there were—small teams without much competition. And so, we had larger teams, and so people are competing with each other.
I had been used to the CDF environment where at the same time as we’re writing a paper, we are being evaluated internally by a group that’s also writing a paper [laugh] that’s trying to get it to the collaboration before ours. So, we just had to figure out ways to not get in each other’s way with biases, and those had not developed in cosmology at that point. I mean, it just wasn’t at that level of professionalism in understanding that biases are easy to come by and hard to mitigate.
Yeah, maybe the word is not ‘casualness’ but, as Saul told me, I mean, the cue that he took was from his advisor, Richard Muller, who was just—you know—he jumped at any kind of experiment to do. There was nothing that was off the table in terms of if it was interesting, let’s go for it.
Yeah, exactly, yeah.
Did you ever consider making the move to Berkeley, or you could continue in this collaboration even after your sabbatical there was over?
You know, it was very nice working [laugh] in California. It was the first time in which I’d actually seen physicists going home at 5 p.m.
[laugh] West Coast lifestyle.
The lab environments—yeah, it was really nice and attractive. But my wife was a tenured faculty member at Temple, so it wasn’t really a serious consideration for me, I think. And I had grown to love Philadelphia an awful lot. I mean, I hadn’t expected it when I came, but it really is a tremendous city, one of the great cities of the world.
And it sounds like you were really rooted in the community as well in terms of, you know, beyond—not just Penn but West Philadelphia and beyond in terms of your educational interests.
Yes, absolutely, and outreach, you know, there’s a lot that you can do there because I was known in that community. I could work directly with teachers. We could not flout union rules, but we could find ways around union rules—about which teachers you’re allowed to work with, and so forth. So, you know, there’s just an awful lot there that’s not—that’s more than just comfortable. It makes it more efficient for you to actually get done the things that you want to start up without having to go through lots and lots of introducing yourself to people and having a reputation that precedes you.
Now, when you’re named chair in 2009, of course there’s two basic approaches to this. One is, you know, oh, it’s my turn. This is service. I—you know—I’ll do it now, fine. And the other is that there’s a special opportunity there to set the agenda, to bring the department to places where you want to bring it. Where did you see yourself falling in that spectrum?
So, what I didn’t recognize was those were one and the same.
So, the way—I don’t know if you know anything about how you choose a chair in Penn’s physics department, but it’s a very Quaker environment. I mean, it was created by Quakers, that whole department, and so there were still Quaker traditions on how you—nobody runs for chair. Everybody runs for chair. And then you have a series of votes in which you eliminate half of the people each time.
And then at some point, you get down to the last two or maybe three people, and then the most senior person in the department—with the great respectability of having been a chair—doesn’t choose which of the three but has a conversation which informs the vote [laugh], right, the final vote. Nobody gives speeches. Nobody gives a vision for what they want for the department, right. That’s just not allowed.
So, in my case, it was Walter Wales. And Walter had been everything at Penn except president. He had been interim Provost. He had been in the dean’s off…you know, he had been a chair of the department. Pretty much every service role you could think of, he had at some point done it. And so, Walter was the person who came to me with the outcome of the final vote to convince me to become chair. And I was all prepared to have a long argument in which he was going to lose at the end—
—because I just didn’t think the department was ready for me to bring a vision to it.
Ready in what ways? Scientifically and sociologically?
As I said, I wasn’t—I never anticipated and never enjoyed this idea of having to be the one to bring up issues around diversity, so that was certainly one of them. And I had, you know, kind of knock-down, drag-out arguments with some of my colleagues around the importance of considering women candidates in our short list for searches.
Had there been a woman tenured in the department at that point?
Yeah, so Fay Selove got tenured back in the ’60s, but she sued to have that happen, and she was the only one basically up until 1997, ’98 or something, so for 35 years or something. So, it just wasn’t a friendly environment for issues around diversity, and I had no idea whether or not people would be responsive to having a different relationship with the dean’s office than they had had before. I was very much not going to be in the mold of someone who just waited for the dean’s office to deliver goods, right, more faculty slots, more space, and so forth.
So that meant convincing people that there’s a different way in which we do these things so that you essentially are doing what the dean has a strategic vision to do. And you don’t necessarily have to agree with every aspect of it, but, you know, the dean is the leader, and so you really need to absorb how you are fitting into that vision, right, and adapt your vision so that it actually does fit. It doesn’t have to be dishonest, but it does have to be the case that you use the language that allows people to understand this is how it helps me achieve where I’m trying to go with the school. So, the argument with Walter was basically—you know—it was like [laugh] my work-study job. I mean, it was more than 60 seconds but not much more.
Walter came down and said, “You’ve been chosen to be the next chair.” And I said, “Walter, I’m not sure that I’m ready to be the next chair, and I’m really sure that the department’s not ready to have me be the next chair.” And Walter said, “You’re probably right on both points, but that doesn’t matter. You, for whatever reason, have been chosen to serve, and when you’re asked to serve, that’s what you do.” And then he got up and left. [laugh]
And I was kind of dumbfounded. But then he stuck his head back in, and he said, “For what it’s worth, I’m sure you’ll do just great,” and he left.
Yeah, yeah, and maybe the sub…
Now, if you knew Walter, you’d know that he would not say that just to be kind or to give you courage, right. I mean, he always spoke the truth. And so, if he, with all his experience, thinks you’re going to be—you know—you’re going to do a good job, then you’re going to do a good job.
And maybe the subtext there was that Walter was the acknowledgement that the department was not ready to have you as chair. That was also not a good reason for you not to be chair. That it needed to be made ready for you to be chair.
Right. And he said—you know—he said volumes in just those two—those three sentences, yeah. So, it was pretty incredible.
How did you get involved first with the LIGO endeavor?
So LIGO had—the collaboration of course is reviewed annually by the NSF. And I think they had always had it in mind that there was no community of gravitational wave researchers when LIGO started. So, one of the things they had to do was to build that international community, but they also understood that we’re not an observatory in the traditional sense of an observatory in astronomy. We’re not a particle physics experiment—in that we don’t have an accelerator, per se, but an awful lot of the kinds of things that we need to do for quality control—and so forth that are like that.
So, they really, I think, had it in mind. And this I give a lot of credit to Beverley Berger and others at NSF for recognizing what the collaboration I think recognized, which is that we need people from other fields who are going to come in and give us a perspective, an honest perspective on how we’re doing. And the perspective is from that of people who are used to large projects, large-scale projects that take a long time to complete—that have a narrow window without necessary competition in order to advance things to the point where you could get to the point of actually having an observation—the first event seen.
And so, I’m not sure how I got invited onto that, but I came out to the first committee, and, you know, I just kept getting invited back. And so, at some point, they ask you to run the committee, and give good advice to them. And so, you know, it was terrific because, first of all, they’re just outstanding scientists, right, I mean, just incredible. But they were also working on something for which there was no guarantee that in your scientific career, you’re actually going to see this happen, right. You’ve been working—some people had been working on this for 30 years, going back to the ’70s.
You mean the detection of gravitational waves?
The detection of gravitational waves, yeah.
So, even at the late stage of you joining, because, like you said, this does go back—I mean, Rai Weiss had been working on this for 30 or 40 years at that point. Even when you come on in 2010, 2011, even at that point, four or five short years before the detection, it was still sort of up in the air? It was really not a foregone conclusion that this was going to happen.
Well, there were no good models for having large—you know—large numbers of really massive black holes in the universe in this range where we now know that there are existing, you know, in the sort of 30 to 100 solar mass range. So, there wasn’t real expectations that you could actually see these events because you didn’t know that there would be enough in the universe to actually make them visible, to be close enough to make them visible. And you could calculate what you did for neutron star and neutron star collision. That’s just small, right, really hard to do.
And, at that point, I think, when I first joined in, it was just starting to be known that you could do both analytical calculations of what the waveforms for these would be in order to verify what you were getting out of the computer models that, you know, solving general relativity on the computer. So, there were a lot of reasons to expect this may not just—you know, if you’re unlucky, this may just not work until you’ve pushed this to an exceedingly high level of technical sophistication, even given how much technical sophistication you’d have to do to get to the point where you were in 2010. So, I think it was really, to me, a great vision to see this, but also to help them move from—by advice—move from a situation in which they were working on this as experts who weren’t necessarily expecting to see anything but hoping to see it, but understanding that the first time you see it, there’s going to be a lot of skepticism, and there’s going to be a lot of leakage [laugh] of information, right.
And so how you keep from becoming the collaboration that releases something that is not verifiable and, in the end, gets seen as being, you know, like the BICEP experiment, right. It’s very easy to fall into that trap. And so, a lot of the advice we gave them—beyond sort of the advice on what they were doing technically, for which of course they didn’t really need very much—was on this whole aspect of how do you develop a collaboration that’s able to internally vet things at a level and with a degree of secrecy that allows you to be confident before you go out into the public with it? But, at the same time, understand that once you do go out into the public—and it’s real—the pressure becomes enormous, right.
And I don’t know whether we helped them a lot in that second point. But, at the very least, we did warn them that, you know, when this is out, the [laugh] degree of just force that the outside world wants to peer in and figure out what you’re doing and what’s next and, you know, when are the next events coming out, what’s the schedule, why is it this schedule? I think people are unused to how critical even colleagues who are...who have their vested interest in mind...can be when they’re excited about something. And then it’s not—it goes beyond sort of just being a nice person.
But, you know, rumors start, and the rumors in and of themselves can lead to the kind of internal politics, which it’s really hard for people to deal with. We understand for LSST that this is an issue that I think is being handled pretty well—that we’ve learned by experience, which is on BaBar—there were people that had spent 10 years helping build the detector who were completely overrun in the CP violation analyses by people who came in a year before we were able to get the result out—and just did analysis that entire time—ran Monte Carlo simulations, had done very little to nothing to actually build the experiment. And, you know, we can’t have this situation anymore—just in terms of keeping the field viable, but also just the right thing to do—that people who have spent this much time and effort making it possible should not be iced out because there are people who are really sharp who want to push their way in, and just get to the next physics.
You know, when you hear—in many different kinds of ways when you hear Kip Thorne and Barry Barish and Rai Weiss talk about LIGO, they’re all very careful to convey that, you know, in some ways, the recognition of the Nobel Prize, it’s in very—in many ways—it’s a 19th century kind of phenomenon where, you know, one or two people were involved in a project. And now LIGO is—obviously LSST is like that as well. It’s highly problematic to give these awards to individuals. And so, I wonder if you felt, you know, part of that broader recognition, that even though only very few people can actually receive the Nobel Prize, as a member of the LIGO collaboration, if you felt collectively a sense of pride in being recognized at this level?
Well, I was never a member of the collaboration. You know, I think our essential piece was that you don’t have to be part of the collaboration in order to make some contributions to it. So, advising, in my view, is an important thing to provide for the people who actually make this happen, right, who are not only leading it but also have to be responsible for the aftermath of what happens if you’re wrong about this.
So, I was, you know, sitting in the room, being the first among the first dozen people outside of the collaboration who heard about the first event, right, back in January in 2015, I guess. And to be among the first set of people who are hearing this, we were there basically to be the audience that says, “How do you receive this, right?” I mean, we’re all excited about it, but we understand that we have to be convincing here. And we’ve managed to convince ourselves, but we really need to hear how we sound, I mean, literally?
We present evidence, but there are lots of cases in which you—like with the supernova discovery and dark energy—there were lots of people who were senior scientists who said, “I don’t believe it, right. I mean, I see your data. I see your graphs. I hear how many, you know, how many tests you’ve done to try and make sure that you’ve done the measurements correctly. But it just doesn’t sound convincing to me,” right. And there’s so many ways in which things could have gone wrong. So how open do we have to be?
And so, people who were presenting this, the leadership that was presenting this was very clear that we want to state, first of all, how lucky it was that we were actually able to observe this, right. There was literally somebody outside three hours before this event came in who was banging on the pipes [laugh] because we had a noise source we didn’t understand. And had that happened when the event came in, of course, we would not be reporting this. And the reason why they stopped was because their—it was during the nighttime, and their flashlight battery ran out. [laugh]
So, you know, the expression of these things internally of here’s what it takes to actually—you know, years and years of planning, and it all could’ve been undermined by these really simple things that might’ve gone wrong and didn’t. It’s part of the story we tell. So, we were basically reflecting back to them, right. Here’s what sounds exciting and interesting about the revelation, right, as opposed to do...we believe the result, because you’ve got to publish the result, and that’s going to have to be gone over by a fine-tooth comb by lots of people over time, who are going to come up with all kinds of reasons why they think you’re wrong. But, really, the aspect of, you know, are you prepared for the onslaught that comes with this, you know, that’s an important piece I think for giving confidence to the leadership who could then relay that to them.
Larry, did you see any issue? Did you see any issue with that—about once they presented their findings—that there would be those people in the room who expressed doubts about the validity of the event?
Yeah, they allowed us to actually sit in on the final reading of the paper, and, yes, there was internal conflict around the issue of whether it was ready to go yet. But, again, I think the leadership had to feel that the majority of the collaboration was with them—that the objections had to be noted—because you wanted to keep these people working on the next set of events to come in, and there were already candidates. But also, that, you know, we’ve got outside people looking at how we’re leading the discussion here.
So, if we’re guiding this too much, if we’re overruling people and getting them to, you know, to side with going forward with this but they hear as outsiders that, you know, you’re being too persuasive here; then we’ve got a way of getting feedback on that. And so, you know, I think it—I actually have to give a lot of kudos to people being brave enough to have outsiders come in and listen in on their conversations, some of which, you know, were emotional, some of which did indicate that there were some doubts about whether to go forward with this or not. But, again, for a collaboration, that’s inevitably going to happen.
Larry, when did you get involved with HEPAP, and how much was the SSC a sort of dark cloud over existential questions in the field of high-energy physics?
Well, the HEPAP, you just get invited on, and you sit for, you know, for your term. But there were things that were very crucial about the particular period of time [laugh] that I was on. And so, you know, one of those was, of course, during the time when we did the first sort of decadal survey—the way astronomy does—and decided to put together a P5, and so that being part of the subcommittee that worked on that was pretty important.
And I think we did take lessons from the SSC. So, you know, I don’t know that there’s a way to really express how much disappointment there is from having this be the vision for the future, and being sure that you’ve got the political willpower behind you to do it, and then having it undermined in such a dramatic way, right, I mean, filling in the hole with concrete, even though it takes you millions of dollars to do that, just to make sure that politically it’s not viable to bring it back. That gave you an insight into the political process, which it informs you that, first of all, you don’t want to be on science projects [laugh] where politics is really that important, right.
Politicians, I would say, in Congress—not in the Senate but in the House—these were—I don’t know. I would use the Hillary Clinton terms. They’re deplorables, right. There were people who were completely ignorant of what the benefits were and didn’t care.
There were people who told me on the Pennsylvania delegation, “Does this have anything to do with Black Lung Benefits? Because if it doesn’t, I’m not interested. If it doesn’t have anything to do with Black Lung Benefits, it isn’t going to take. If it’s Black Lung Benefits, I’m happy to vote for it. But if the money’s going to go there, and not to Black Lung”—literally, this is the only issue, right, that you’re in Congress.
That’s why I’m in Congress, to protect Black Lung Benefits. Really? For an industry that we should be phasing out anyway. I...so there...it was...the SSC exposed us to that in ways that we hadn’t before, and I particularly just take it as impossible to work with Congress, literally, because the political winds can shift so easily for reasons that have nothing to do with rationality.
And there were a lot of, you know, there was a lot of opposition to Bill Clinton among the Texas delegation. And so, we, I think, lost a lot of our faith that America was prepared to—and still capable of doing really huge projects, right. NASA was doing it with the Space Station because they were spending so much money, and they made sure they distributed it through all 50 states.
So, it was really just a disappointing time to think that we, you know, we had...we admitted that we had ceded the leadership in particle physics, but we deserved to. We were just not a society, at that point, where I felt we could do things. LIGO was a breath of fresh air, right. That was really something for which it’s impossible to imagine how it got through all the political landmines—
—that it did. And, yet we still found a way to do it, and actually get it to the point where it discovered something. So, coming out to HEPAP, it was with that previous frame of mind, which is people want to build the, you know, the next collider in the US, I mean, literally. I think we could plan for it, but I just still don’t see that that could possibly happen, right. I just don’t know that the U.S. has the willpower to do it, and I’m pretty sure that the rest of the world is following in the same way.
So, particle physics for me in 2003, moving to cosmology—part of the reason I was glad to do that was that, you know, the HEPAP process to me is important. But the planning part of it doesn’t get you away from the fact that—I don’t know that, as a people we have the capability of doing really tremendous scientific projects, or really any project, right. I mean, infrastructure for the U.S., you know, any of these projects that really require us to be on the same page and to leave aside the kinds of things that might boost somebody politically—for the short-term—in order to actually get something completed.
So, your sense was that with SSC, the lesson was that the United States clearly ceded leadership in high-energy physics. But in cosmology, that was definitely not the case, and that the field was young enough where there was lots of reason, minimally at least, to be optimistic that the United States would and would continue to be a leader in experimental-based cosmology research programs?
It is. But, you know, it’s still the case that we’re not completely free of political machinations. And so, the LSST, part of the budget for maintaining the operations—was supposed to come from international partners in the form of cash. And because—as far as I can determine, and others who’ve heard about this—we didn’t want to take cash from particular countries—and one country in particular—we were not allowed to do that. We had to come up with a completely different way of supporting the operations completely out of the U.S. budget and bringing in our international partners through, you know, through collaborative agreements.
One last question. Let’s sort of fast-forward. I mean, we already covered at the beginning your prospects. But to get back to the science, when you called it your dean job right now—is your sort of day job, right—what are your prospects in terms of going forward in the future? You gave me, you know, a beautifully articulate vision for, you know, your goals in diversity. But in terms of the science—whenever you feel like you can get back to that more on a full-time basis—what are the things in physics that are most compelling to you now, looking, you know, going forward?
Well, I think LSST has tremendous potential across cosmology and astrophysics in terms of what it’s able to bring with this amazingly huge data set. And so, there’s a couple of things that I would like to be involved in, but, you know, whether I’ll get time to do them or not is a question. So just the basic cosmology piece—which is dark energy—is still out there is a question. Being able to be part of the team that actually looks at the coalition of results—from four different ways of observing dark energy, and actually seeing whether we can see whether it’s constant in time through the universe’s history or not—is great.
But the other thing that’s opened up here is that the data set will be open and available, so the citizen science possibilities are really tremendous. And I know that there’s a group that’s working on that. But I think it’s going to actually take scientists to sort of also help in leading people to not only know the possibilities of that, but, for example, reaching out to groups that—I think particle physics started this with QuarkNet. But, really, with LSST, we have the possibility of doing this with high school students and maybe even with middle school students, so just having basic explorations that are not thought about yet, and maybe not canned, but can actually still be very effective.
Well, Larry, I want to thank you so much for spending this time with me. You know, between the explanations on the science and the perspective on the diversity, and for all of the above, I want to wish you a lot of luck in your future endeavors. And this’ll be a tremendous historical resource to many, many researchers coming from a variety of fields and disciplines. So, thank you so much for spending this time with me. I really appreciate it.
Right, thanks, David.
OK, take care.