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This transcript is based on a tape-recorded interview deposited at the Center for History of Physics of the American Institute of Physics. The AIP's interviews have generally been transcribed from tape, edited by the interviewer for clarity, and then further edited by the interviewee. If this interview is important to you, you should consult earlier versions of the transcript or listen to the original tape. For many interviews, the AIP retains substantial files with further information about the interviewee and the interview itself. Please contact us for information about accessing these materials.
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Interview of Naomi Ginsberg by David Zierler on May 19, 2021,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
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Interview with Naomi Ginsberg, Associate Professor of chemistry and physics at University of California, Berkeley and faculty scientist at Lawrence Berkeley Lab. The interview begins with Ginsberg discussing her multidisciplinary background in science and how she prefers not to draw boundaries between research fields. She talks about how the Covid-19 pandemic has affected her research and the science community in general. Then Ginsberg turns to her childhood in Canada and recalls being a curious child with many interests. She describes her undergraduate studies in engineering at the University of Toronto and her summers of research at the Institute for Biodiagnostics, which is where she became seriously interested in physics. Ginsberg discusses pursuing a PhD at Harvard University under Lene Hau, where she worked on ultraslow light in Bose-Einstein condensates and superfluid dynamics. She then talks about wanting to switch gears toward biophysics and choosing to go to LBL for a post-doc in photosynthesis work. Ginsberg describes accepting her current position at Berkeley and the different cultures between the chemistry and physics departments. Towards the end of the interview, she touches on her DARPA grant for research on organic semiconductors, as well as the advances in technology that have informed and shaped her research over the years. Ginsberg looks back on the many grad students she has mentored and points to open-mindedness and confidence as key characteristics for their success.
OK, this is David Zierler, oral historian for the American Institute of Physics. It is May 19th, 2021. I am so happy to be with Professor Naomi S. Ginsberg. Naomi, it’s great to see you. Thank you for joining me today.
Oh, my pleasure.
Naomi, to start, would you please tell me your titles and institutional affiliations? I pluralize that because I know you have more than one.
OK. I am currently an associate professor of chemistry and physics at University of California, Berkeley, and also a faculty scientist at Lawrence Berkeley Lab in the material sciences and molecular biophysics and integrated bioimaging divisions. I’m also a member of the Kavli Energy NanoScience Institute, and a variety of other centers, but in particular the STROBE National Science Foundation, Science & Technology Center for Realtime Imaging Science.
Wow, that’s very impressive if you just came up with all of that off the top of your head. That’s amazing.
Yeah, well, it’s usually written on a slide [laugh]—
—from the beginning of a talk [laugh].
Naomi, before we unpack all of those titles, you as much as anybody else that I’ve talked to, it’s a great opportunity to get your sense of where the distinctions between scientific fields are real, and where they are just these barriers that people put up for administrative reasons.
So, to just—you know, a brief stampede through your educational trajectory. You have engineering. You have physics. You have this dual appointment in chemistry and physics. You have this whole nanoscience and biology thing, right? For you, for the research that’s most compelling and interesting to you, where do you see actual important distinctions in these fields, and where is it “it’s all just science, and I just follow the things that are interesting and important to me”?
Yeah, that’s a great question. The short answer is that I like to draw a distinction between scientific research and scientific discipline. For example, as you mentioned, I was educated initially in a program called engineering science, which was a hybrid of both engineering and science. But that was a discipline. I took certain classes that constituted the canon of classes from that discipline, and then I did my PhD in physics, and I was educated in the canon of physics, and I took all of the graduate courses that physics graduate students take. And then that was the end, I suppose, of my formal education.
But now I have students in my lab who come from various different backgrounds. So, some of them are also educated in physics as a discipline, and some of them are educated in chemistry as a discipline. And the discipline is basically a huge foundation. As in, each of those is a specific foundation. But the science is the science, right? The physical laws are invariant to discipline And sometimes you need to draw from elements of different disciplines, but the basic concepts are all the same, and it just depends on like what lens people saw them through.
So, I don’t like to think about research fields as being engineering or science…or chemistry or physics. That doesn’t make sense to me because in research, you have a question about the world that you’re trying to answer, and you should use whatever tools you need in order to answer that question.
Yeah, I know. I mean, this will be a theme—
I have very strong opinions [laugh] about this.
Yes, of course, of course. Maybe to refine it a little bit, in terms of your collaborators, do you have an intellectual comfort zone or a home discipline where you are the expert, and you… and others rely on you? And in other places where you follow the science, here’s where you’re interested and you’ve gone there, but you need somebody that has more of a solid grounding in that particular area where you’re relying on their expertise?
Yes—well, the reason it’s hard to answer that question is because the relationships you have with what you know and what you’re learning are dynamic. And, I guess I always want to learn new things. That’s, you know, basically my goal.
And I start off not knowing them, and then I learn them, right? And in many cases, I do end up learning them through collaborators or also through students. For instance, I don’t have any formal education in chemistry. In fact, I’ve never even taken most of the chemistry courses that the undergraduates that I teach have to take [laugh].
[laugh] So, I definitely feel as though I rely on people, but not in all cases. But in many cases, my goal is not specifically to become the person, but to be able to do the science at a level where I do become that person who is the resource and isn’t just, you know, leveraging others. And then I don’t necessarily stick with all of the fields in research where I have become, you know, a, quote, unquote, expert, [laugh] to whatever degree anybody can actually be an expert.
So, sometimes it starts off with collaborators, and then, I feel like I’m growing into the area as my lab learns more and more. I believe the one place where I know that I will probably never be able to just do it all myself is when the theory behind the science gets super sophisticated. That is something that is too difficult to dabble in, right. I would need to do another PhD.
So, I definitely prefer to analyze my own data, or have my group analyze its own data, and we do plenty of simulations and calculations because, to me, as an experimentalist, handing off your data for somebody else to analyze just takes all of the fun out of it. But I definitely feel I’ll always be at the mercy of and hopefully have a mutual respect for theory collaborators that are advancing methods, just like we advance experimental methods in order to solve problems.
That was exactly my next question, which is in what disciplines or subfields or research endeavors are to you most alive to the interplay between theory and experiment? In other words, over the course of your research career, when have you paid the most attention to when theory provides guidance to experiment, and when experiment provides guidance to theory?
Well, first of all, I don’t think it’s that causal, or, at least, if it is, it’s not very interesting for one or the other party, at least in the type of work that I’m interested in. I know that there are entire fields of thousands and thousands of physicists who do work that way: “Here’s a prediction. Now, it’s my job as the experimentalist to test it.” Or, “here’s a result, and now it’s somebody else’s job to explain it with the theory.”
But, I’ve often found that if I have an unexplained result, and I go to a theory colleague, and ask them, “Can you help us explain this? We’re really mystified,” in many cases—not all—and I think it works in both directions—in many cases, they say, directly or indirectly, “Oh, we could, but that’s not really turning my gears. That’s just kind of like turning the crank, and that’s not very stimulating.”
And, so, I believe the best collaborations are ones where everybody’s intellectually engaged and to a similar extent, and similarly invested. In my own career, the place where I’ve had that sort of connection and investment has, to a large extent, been when I started studying more and more complex systems. So, in particular, now, the chemical physics side of things, especially in the condensed phase, is very—it’s very complex, and I’m still catching up. I will probably be catching up for the rest of my life [laugh]—
—and learning what this field is about because it’s—you could think of it as largely steeped in classical statistical mechanics, and, more recently, also in non-equilibrium phenomena that can’t be described within thermodynamics, and people are developing new theorems and methods to be able to address systems out of equilibrium. And that’s really complex. So I can strive for a deep conceptual understanding, but everything else, I need to entrust to collaborators who I really do trust, and who are engaged by the problems that we’re working on, or we decide on those problems together.
And for areas like atomic physics, which I worked in in the past, it seemed a lot more tractable to do the simulations and understand the theory. I don’t know that that’s still true because that was 15, 20 years ago. And the sophistication of those experiments has increased dramatically and in ways that I would never have been able to anticipate.
But there, it seemed more tractable, and it was actually really fun as a graduate student to have that ability to answer my own question by doing the numerical counterparts to the lab experiment as well. So, sometimes, it is possible. And, still in my lab now, it is possible some of the time. It just depends on the scope and complexity of the problem: how realistic does the model need to be in order to, you know, describe your experiment?
Naomi, that’s a great intellectual and also sensibilities foundation to all of your titles and affiliations. So, to get back to that, your—is it a joint appointment, a dual appointment between chemistry and physics? Are you 50:50 between two departments?
I’m not 50:50. It’s technically, 100:0.
But that basically just dictates where I teach. So, I teach physical chemistry but I don’t teach in the physics department. But it’s often recommended especially to assistant professors to not have an even split of accountability so that at tenure time, there aren’t, you know, awkward disputes between departments. With 50:50 each department takes equal claim.
Of course, the way that it was actually advertised to me —from the physics perspective, I was told, “If it weren’t to work out for you in chemistry, then we could always vote to make you 100% a faculty member in the physics department,” or something like that. So, I don’t know. It seemed like a reasonable way to feel that there weren’t people vying for my service with the same expectations, as an assistant professor. But I feel like a fully-fledged member of both departments and do my best to participate in both communities.
And administratively as vice chair of physical chemistry, vice chair of what?
Is physical chemistry its own entity?
[laugh] It depends on who you ask.
So, the different departments have different structures. And in the chemistry department at Berkeley, there are three subdivisions, each of which has a vice chair—physical chemistry, which is what I do, synthetic chemistry, and chemical biology—and those different divisions operate their graduate programs in slightly different ways.
That’s an administrative responsibility that I have that largely pertains to the graduate program, so, basically, admissions and recruiting, and ideally retention, organizing the students’ qualifying exams and committees equitably, making clear to all the students the expectations for the PhD program, and, various other responsibilities associated with the department. So, I guess in some sense, it is like its own entity. But it’s mainly an administrative role. Somebody has to do all of that.
Naomi, in what ways is Berkeley Lab central to your overall research agenda, both in terms of the people that you might work with there, access to instrumentation, access to funding? How does the lab work for the kinds of things that are most important for you?
Well, one really fantastic aspect of Berkeley Lab, and this is probably accentuated here between UC Berkeley and Berkeley Lab relative to other universities that also are managing a national lab, is the proximity. The physical proximity is especially valuable. But a national lab is not organized around disciplines, right?
A national lab, like many companies, forms teams of people that are often multidisciplinary in order to address big challenges in science. And, so, that’s really perfect. It catalyzes a lot of collaboration and connection. It certainly encourages it. Apparently, in the olden days, whenever that was, not that long ago, certain lab scientists would have funding exclusively to them and their own research portfolio, and there was still a lot of collaboration.
But now, the way that it typically works is we’re all in teams. You can’t really hold a grant from DOE through LBL without being part of the team of other people you’re working with. And, so, when I started, for example, as an assistant professor, and I had this faculty scientist appointment, I didn’t even know which direction to turn in because there were so many people who said, “Oh, we’ll support one of your graduate students if you join us on this project. And all you need to do to get started is, make any measurement within your expertise, so long as it’s on the themes of this program”—and sometimes it’s not quite as easy as that.
There’s also a lot of encouragement to put heads together whenever a big call comes out from the DOE for a funding call. You know, the lab helps to organize workshops and discussions about what to anticipate, and to help form teams. And this ends up being collaborative through the Berkeley campus too. For example, because there are quite a number of faculty who have joint appointments at the Lab, when there are limited numbers of submissions that the funding agency will accept through any one institution, the two entities will coordinate to maximize the collective opportunity for funding here. So, that’s one big part of it, and it’s really great.
And then there’s another big part, which you mentioned also, which is the facilities aspect. And this comes in in multiple different ways. When there are big facility upgrades that are being anticipated, it’s always very important to be able to make the scientific case for them. So, there are a lot of workshops and brainstorming that go into those, and really thinking big, you know.
For example, at one point we were asked, if we get to build a free-electron laser here—which we didn’t end up getting to do, but we have one, you know, not too far away—well, I shouldn’t say “we”. It’s not mine [laugh]. But there was lots of brainstorming, asking: what are all the possible science experiments that we would be able to do? And that’s often happening. It’s happening with the synchrotron right now in multiple different ways. There are many different workshops that go on, and those sorts of things.
But the other thing that’s totally amazing about being here is that there are these facilities in the first place, and that the access to them is so great. Of course, we don’t get special treatment because of the proximity. Everybody has to write a user proposal in order to use a national facility. But we do that, and a large part of my research program now is related to these.
Initially, my main point of connection was at the Molecular Foundry at Lawrence Berkeley Lab where over the past decade, we’ve collaborated pretty closely at various points with staff scientists to develop abilities to do cathodoluminescence microscopy, so basically, collecting not only the electrons that give topography in a scanning electron microscope, but also the light that comes out of many samples as a result of the impinging electron beam. And we’ve developed a very high efficiency light-collection system. They’re continuing to add more and more bells and whistles so that we can do more and more sophisticated in situ experiments in order to look at how the electronic properties of materials change as a function of time or temperature or all sorts of other things.
And my lab in particular has wanted to push this to the limit where you can look at more and more delicate materials. So, that’s allowed us, for example, to even make the very first cathodoluminescence measurements on metal halide perovskite materials, which are very, very popular low-temperature processable direct bandgap semiconductors right now. We were able to really just see what these materials look like and how heterogenous they are at high resolution—people don’t use imaging nearly enough, but maybe I should get into that a little bit later.
But the only reason we were able to do that without damaging the material, mitigating damage to the point where we could also look at dynamics like interesting phase transitions that occur in this class of materials, is because we have that high light collection efficiency. And, you know, it’s not like I showed up with this apparatus. That was a really great collaboration with the staff scientists. One of my first postdocs, David Kaz, working super closely with, well, in particular Frank Ogletree, who’s been a staff scientist there since the Molecular Foundry began, and at LBL even longer, and also Shaul Aloni.
More recently, my students and postdocs still go up, you know, every week, and we’ve had the access that we need, and it’s been really fantastic. But also more recently, we’ve started doing more x-ray scattering experiments, and so there, it’s also been extremely valuable to have a synchrotron just up the hill. In many cases, we go to other facilities as well. You can’t do all of your experiments or get all of the access you might need at LBL, but still...
It’s definitely been really valuable, and I doubt I’d even be doing any x-ray experiments if it weren’t for the fact that the Advanced Light Source at LBL is right there, and either we were encouraged through LBL to send out proposals for certain DOE calls, or students in the lab get curious and say, “Oh, it’d be really neat if I could get some structural information on this. I’ve got a friend who says we should try and use x-ray scattering to do it. Can we try it?” Well, you’ve got nothing to lose by writing a user proposal, and another great thing about these user proposals is that when access is granted, they’re free.
The DOE is footing the bill for users to use the machine, right—not for your whole research program. But that helps a lot, and I believe that’s also really valuable for not just my lab but for all labs. That it really is equal access. And then you also know that if you develop technology to be used there, like the cathodoluminescence capabilities as an example, then that ends up being something that all other users will ultimately be able to use as well.
In what ways is nanoscience and your membership at the Kavli Institute at Berkeley—is that an affiliation unto itself, and in what ways is nanoscience really integrated with your overall research agenda?
That’s a really interesting question.
Because I can easily see nanoscience having relevance in everything that you’ve said so far.
Yeah. To me, nanoscience really refers to a particular scale, and it’s a scale that’s important in many different contexts. So, I don’t particularly walk around saying, “I’m a nanoscientist”—
—“and you’re not.” Or even, like we’ve talked about already, “I’m a physicist or I’m a chemist or I’m an engineer or whatever.” So, yeah, it’s not a term with which I feel I super strongly identify. But, as you point out, all of the research that we do qualifies, and then that’s why we’ve been a part of this Kavli Institute from the beginning. And many of the things that we work on of course are also very related to energy science.
And I wouldn’t say that—we don’t make devices or anything like that. We’re not really on the applied side. But a lot of these energy-related applications are, in many cases, directing us to the materials that we try to study more fundamentally at the nanoscale.
Naomi, a more broad question, one we’re all dealing with right now, how has your science been affected one way or another with remote work in the pandemic? In what ways has being home, not traveling, given you more bandwidth to work on stuff that you might not otherwise have?
And in what ways is it just too painful to be away from the lab and your collaborators in person?
Oh, that’s very complex. When the pandemic hit, I was one of a number of people really advocating to shut things down for the sake of the greater good. And the other thing that I remember believing, and that I still do believe, is that maybe the resilience that gets cultivated in our trainees right now is going to distinguish them as not only one of the most resilient generations in a long time but also as one of the most creative. So it might depend on the type of work people do in the lab.
Obviously, if you’re an experimentalist, you need to do experiments, and that’s super important. But it’s at least as important to reflect on what you’re doing, and to think about whether you’re taking the right approach. There’s a lot of reflection that is extremely important in science, and educating trainees to reflect on their results is in my opinion underemphasized. Of course, in some areas, if your main focus is to make a material or molecule, you have to be there to make it, and you may not have as many predictive ways to do that. The pandemic shutdowns were particular rough for labs in that category. But for my lab specifically, part of what I’d like to be able to contribute to science is, let’s say, more mechanistic, to provide physical principles to help guide how to make materials with certain properties. So in my lab, we could still think about what we’d been doing beforehand and what we’d want to do next and how to interpret our experiments.
If you’re making measurements, like we do, then there’s often a lot to think about, like “what do they mean? Did we design this experiment right, or how should we be designing it? If we simulate this, what components do we need in order to recapitulate what we see experimentally?” There are just so many questions. And, so, that’s part of the fabric of the work that we do in my research group.
And, so, while from a psychological and social perspective, it was absolutely traumatic for our students and postdocs and also, you know, for pretty much everybody to all of a sudden be at home and completely isolated, there was definitely plenty of work to do and activities to keep busy with, whether it was analyzing data, developing new experiments, or really just having more opportunity to reflect, although it was sort of forced. So, I guess, that’s my philosophy on how our science is affected. However, whether it’s physically being home or spending so much time staring at a computer monitor or just ending up being more sedentary—given there are all these micromotions, getting up and sitting down, we would do in a normal work setting that we’re not all having access to over the course of the pandemic—that definitely has taken its toll on everybody working from home, whether or not people are willing to admit it.
And, I mean, now, everybody is at a stage where—but it depends where you are in the country—but in California, we’re at a stage when people are sort of becoming re-socialized. Like, when you meet somebody in person again—so, for the past few weeks, I’ve had the privilege, I would say, of meeting my trainees in person at least for one-on-one meetings. Nobody knows how to make eye contact anymore.
[laugh] We’re all thinking, “how did we do this before? This is so awkward.” On a video call like this one, I can stare right at your eyes right now, but you can’t really see that I am, and vice versa. So, also—
Kind of like we have—Zoom is its own mask in a way.
[laugh] Yeah, in some ways. There are some things that it does really well. I mean, it just shows us that, in principle, we can connect just as easily with collaborators across the world as we can with, people who are close by. And that’s hugely enabling.
But, yeah, it’s definitely the inclination that people have to work from morning to night, and probably not very efficiently and all these sorts of things, that’s real. That’s definitely real. So, it’s hard to say in the end how it might affect my science in particular. There’s just—I just felt a huge responsibility to look after my trainees—
—and other people on the campus, and probably too much initially, and to my detriment. And the concern that people have for family or other people who are very close to us—that all takes its toll. And, so, I feel as though over this time, I have learnt a lot more about not only compassion. I believe I was—well, you can always get better, but I was at least aware of compassion before—but certainly about equanimity, which has allowed me to really ponder what I really value, and, professionally, what do I really value in science?
And if my time is finite, and there are opportunity costs abounding, then you really—you do have to choose really carefully when you have a series of constraints. And there’s never enough time to reflect on what are the best things to choose. But I definitely feel that I have done my best to try reflecting along those lines.
Naomi, where are you specifically on the question of remote data analysis? You know, on the one hand, it’s fantastic that we can do this stuff from home. But on the other, where are the existential concerns of decoupling the experimentalists from the physical presence of being in the laboratory, particularly in terms of training the next generation of scientists?
Yeah. To me, it’s not only about training the next generation of scientists.
It’s your own muscle memory?
It’s, about how are we more functional? There’s a lot of research in social science that emphasizes to us over and over again that human beings are social beings. So, whether or not you are introverted or extroverted, we each require some amount of social connection in order to draw meaning to our lives. There may be many other things that draw meaning to your life, but that is basically an accepted fact.
And, so, I always believe that if you want people to do their best work, they need to be able to focus on their work instead of other anxieties or things they’re wondering about. And having a sense of social connection with other people, that you are valued and part of a community, is essential to enable people to do their best work and focus their energy on their science. So, that’s one part of it, and having that connection with others is really essential for those reasons.
But also, there are discrete events that happen in our minds that are really pivotal, though I hesitated to call them breakthroughs, because of overemphasis on the myth of genius in scientific culture. These obviously require solitude part of the time, which can be more readily achieved by definition in isolation, but to make progress, let’s say, in the problem that we’re trying to solve, there are so many random chance encounters with others that are important, and often underemphasized.
So, what I’ve been trying to encourage my students to do at the rate at which they feel comfortable is to spend more time in the offices. It’s only the past few weeks that we’ve even been allowed into offices. It still feels so weird for people, and we’ve all convinced ourselves that we’re actually more functional being insular than we actually are. But whether it’s just the facility with which you can walk down the hall and ask somebody a question, or who you bump into making a coffee, or, somebody else asking you a question that prompts you to think in a slightly different way, all of those are absolutely essential to each of us making progress in our work.
And that is irreplaceable, no matter how much we leverage tools like Slack and Zoom and other forms of remote communication. All of the chance encounters and the incidental parts—I mean, there are some buildings that have been designed at scientific institutions in order to promote those sorts of chance encounters, and, there’s totally a reason for that. I believe it really is important, and it really does work.
So, I appreciate that there are times when it is valuable to be alone, and I’m grateful, especially for my early mornings when I get the opportunity to use them focusing on something that requires more of my brain and for a longer period of uninterrupted time because that’s invaluable. But it can’t be the only thing.
Well, Naomi, we’ve been talking a lot about the present, and looking to the future. Let’s finally do some history now. Let’s go back—
—to Canada, and let’s start first with your parents. Tell me about them and where they’re from.
They’re from Canada too. My parents were both born and raised in Toronto, Canada, and that’s where I went to university but it’s not where I grew up. I grew up in Halifax, Nova Scotia, which is on the east coast. And they had moved there before I was born. So, that’s where I lived my entire childhood until I went to university.
And Halifax is a relatively small city. Well, not as much as it was 30 years ago, for sure. It always had over 100,000 people. But it was a size that was easy to get around in. At that point, at the very least, it had a great public education system that I benefited from tremendously. Nova Scotia is not technically a bilingual province, but it has a long history of Francophone culture, with the Acadian population that has been there since the French found (and were deported from and then returned to) Nova Scotia.
And, so, I received a bilingual education for free. And I suspect that learning languages is a great way to make different neural pathways in your brain, though I’m definitely not an expert on that. And there was a great school music system too. It was all practically free, all these group lessons and ensembles and choirs, which to some extent took privilege out of the equation. So, it was just a very enriching place for me to grow up.
How many generations back does your family go in Canada?
A few, but not too many. Everybody’s origin in my family is from somewhere in Eastern Europe or Soviet Union. Three out of four of my grandparents were born in Canada but not all of their parents were.
And then I have one grandmother who was born in Russia, and moved to Toronto with her family when she was 14 years old, I believe, and had to learn English in kindergarten upon arrival, which must have been rather humiliating. But she used to tell this story of how she caught up to her age-appropriate grade within the year. And most of my family began in this country by working in the sort of places that people of Jewish origin were able to find work—starting a convenience store, selling or making clothes. My parents had a shoe store that they ran for a number of years, and so that was also their work for a large part of their careers.
Although, there’s lots of serendipity in terms of careers and career trajectories, as I always try and point out to my students. So, for example, my father studied languages. He’s infinitely better at languages than me. He had to learn tons of them, and he’s great at it. His intonation and accents for them are all awesome, and he doesn’t seem to forget anything.
So, he actually has a PhD in French language, and he taught briefly at university, or I guess at multiple universities, in Halifax, which is how my parents ended up moving to Halifax in the first place. But once my mother decided that she wanted to, you know, try and use the MBA that she earned in Halifax—and while pregnant with me, which I’m very proud of her for—to be an entrepreneur, he decided it was more exciting to go into business with her. So, that’s what he did.
Naomi—What kinds of science were you interested in when you were growing up, maybe as a way to foreshadow the fact that, you know, you’re interested in everything now?
I was just—I was interested in everything then, and I would also say I was not only interested in science. One thing that I am eternally grateful to my father for is he’s a very curious person, and that really rubbed off on me. Just curious about everything, not just how the world works from a scientific perspective, but from all perspectives.
For example, he’d point out, “this person is really interesting. This is kind of your job now too, right? This person is really interesting. It’s just fascinating to talk to them. I want you to meet this person. Let’s go and talk to them.” And, you know, “what’s their story?”
So, yeah, I was just interested in everything. That’s why it was super fun to learn French and to read French books and to see how they were similar or different to English books, and to go to Montreal in Canada, and see how much more European the culture was than Halifax. I was just interested in everything in school, and lots of art. I—it was also just equally compelling to me. So, yeah, it’s hard to say what specifically in—
Did you have a vague idea that you would be a scientist, that that’s where you wanted to go with your life when you were growing up?
No, absolutely not because, I still remember really struggling to—I’ve always struggled to make decisions. I remember really struggling to decide what to select to study in university. Like, “I don’t want to leave all of these other things behind to study more of one area than something else.” I was always the sort of person who anticipated to double major or, somehow, not have to make the decision to rule things out. Actually, perhaps I did have some leanings because at one point, I thought—I still think the human body is so amazing. I mean, if you don’t, then I think you’re crazy [laugh].
But amazing on so many levels. And, part of the art that I did as a young person was a lot of dancing and, so long as injuries don’t prevent me, I’m still trying to continue that now. And I was very curious, for example, about kinesiology as a result. And also, I remember being very excited when my friend Peter’s mother, who was a nurse, set us up to interview a gastroenterologist on her hospital floor at one point when I was in high school, which was fascinating. And, I don’t know—I just found many different things interesting about biology: our insides, outsides, mechanics.
I remember at a summer science program in Canada called Shad Valley, putting electrodes on our limbs and making our muscles move— electrophysiology. And I just found that fascinating. So, for a while, I thought I should do an MD PhD, with the PhD in biomedical engineering, so that I could research more about the human body, and on what level, at what scale, I don’t know. I mean, I doubt I knew as much about scales at that point. So—
Is this to say that when you got to University of Toronto, you were not set on a science major?
Oh, I was.
At that point, I was. And, yeah, but making the decision to go there and to do that program was hard for me. I mean, I believe it’s always hard for people to make these sorts of decisions, right? But, yeah, I definitely don’t feel like I knew from the beginning. And I was nervous about the fact that I would no longer have the opportunity to study humanities and arts.
One thing I remember thinking that might have helped to make the decision is that I’m a very slow reader, still today. I’m just slow generally in following any involved thread of ideas, even if it’s somebody speaking. I don’t know, I feel a need to follow all the details. I don’t know how to speed read. I’m not good at skipping steps. This is both a blessing and a curse.
So, I thought I would just never be able to keep up with the reading if I studied something that required a lot of reading. I mean, I love reading. I don’t have a TV. I guess my form of entertainment that would be an analog to TV-watching is reading, so I read a fair amount, but I’m not fast at it. So, maybe that helped me decide on science a little bit [laugh].
Was the engineering science program a hedge in some ways to expose you to as much as you could?
Yeah, absolutely. And even though I didn’t know disciplinary-wise—or maybe that’s not a word—discipline-wise what I necessarily wanted to do, it was a really challenging program, and that was part of the allure for me, that it was challenging. And that’s something you can say about science generally in terms of trying to pick a major. But I definitely believe that that did factor into it.
And that is the sort of program that one applies to directly—you don’t show up as an undeclared major, and then declare it. And, so, I was basically joining a program, and it was a fairly small program, it’s essentially the honors engineering program at University of Toronto. And there are many, many classes, and very few electives. So, I knew I was actually getting into that—in that program.
But it was sort of way to hedge my bets, like you said, in the sense that, well, I really like the fundamentals, I think I knew that about myself always, and so I did want to study science and not only engineering. I didn’t want it to be all applied because it’s all, for me, about asking ‘why’ questions. I kind of told myself at least, and other people, that the engineering aspect was a way to maintain a creative aspect to it.
Of course, science, in retrospect, is ridiculously—I mean, all [laugh] good science, in my view, it’s all about creativity]. But somehow I thought, engineers design and build things, and so that’ll be the creative part, and I’ll balance that with learning the science. And, so, from a discipline perspective of what education you’re getting, I think it is true. I mean we did have to build bridges out of cardboard, and I made a backgammon-playing robot with my friends in one course. And that was all part of the curriculum.
Naomi, as a woman at Toronto, were you ever made to feel not welcome, that this was something where you didn’t belong, or was that not part of your reality?
Yeah, certainly, on a certain scale, and I don’t think it was ever intentional—and you can never say for certain—well, actually, sometimes you can. But, in many cases, you can’t say for certain if it has anything to do with your gender.
I remember, for example, for one course when I just really had trouble digesting the information. It wasn’t anywhere near the hardest course in the curriculum by anybody’s judgment, but I remember going to the professor to say, “I’m a little bit concerned about my performance,” and having them say, “Oh, you mean you do better in your other classes?” I believe that those incidents probably still do happen all the time. That was likely a case of implicit bias, although there’s a lot more awareness about implicit bias now. I also remember, for example, walking into a computer lab, because that’s where we had to go–we had to go to a computer terminal to do our [laugh] homework assignments or projects, whatever we were working on.
And, much of the time, I didn’t really think about it. I’m not a highly gendered individual, I would say. I don’t see the world through particularly gendered eyes, so maybe that’s a good thing to preface my remarks with. But I do remember noting, “wow, there are no other women in this room right now.”
And, what do you do with that information? I mean, wow, I don’t know if it explicitly troubled me or changed my course of action. I still sat down at a terminal to do my work, and being at a terminal was definitely part of my identity. But, I believe that implicitly identifying as ‘other’ probably does contribute to a lack of sense of belonging. And like we were talking about just a bit earlier, that can really take some of the cores of your own brain away from, you know, doing your homework in subtle and maybe not so subtle ways. Those are just two examples—
—but—yeah, there were very few women in my program. And, when I first began the program, they used to tell us our rank at the end of each semester. They stopped doing that. That was a good idea to stop.
They would tell you your ranking on your report card. I remember being told, “You’re the nth highest ranked woman in the program,” not by an official person, but in a discussion with students, and thinking, “What does my sex or gender have to do with it?”
That’s really weird, actually. Like, what benefit does that serve?
Yeah, but it happened a lot. Oh, the ranking or the gender aspect?
Well, the gendered aspect of the ranking.
Oh, well, that I don’t think it’s surprising that people said it. The ranking is kind of unfortunate, and they did actually dispense with it during my time there. But that sort of thing happened all the time, and nobody meant anything by it, but it’s a reflection of how we’ve been socialized and of how minority populations draw attention they don’t necessarily want—you know, impact, not intent…
Who were some of the professors who exerted a formative intellectual influence on you, or who were really supportive for what you wanted to accomplish?
As an undergraduate?
Yeah. And if it doesn’t easily come to you, that’s your answer.
Well, let me just say that that program is amazing. In fact, I got the opportunity a few years ago to go back and be a speaker at this day-long conference that they have for the current students, and I was super honored that they asked me to represent physics for that. It helps the students pick which of the different tracks they go into in their third year.
So, there’s no faculty of engineering science, so the program tries to handpick the faculty from different departments who get to teach these classes for this honors program. So, overall, I would say the education that I received was just phenomenal. It was extremely challenging. But it was just phenomenal.
And, pointing to particular individuals, I don’t know. I’m still grateful for the curriculum. For example, engineers learn lots of math. Math is also super important for physics. And the math that you learn, especially, I do a lot of work with—well, don’t we all?—with electromagnetic radiation. It’s all about time harmonic systems.
And we had bazillions of courses about waves and Fourier analysis and different transforms to make it easier to solve problems, and frequency analysis, and so on. So, the sum total of all those courses, I realize now, it’s made me the way that I am. It makes me think the way that I do. I don’t remember how to do root locus plots anymore. Maybe I should.
But a lot of these concepts, by the way, come up as I’m learning more about the statistical mechanics of liquids and other seemingly unrelated topics. It’s all the same stuff. But, yeah, it’s shaped who I am, and I sometimes have to think about what my students, whether in chemistry or physics, haven’t really learned that I got to learn, when working on problems together. So, that isn’t necessarily specific people. But it was hugely important.
I also—I often had a tendency to—I told you I was slow at reading and at other things. So, I had a tendency to really do poorly on my midterm exams and make a comeback in the final exam. And I remember one class in particular was a thermodynamics class in my second year, and the professor was a chemical engineer, her name is Yu-Ling Cheng, and she was super tough in the best possible way.
And I remember this sort of protocol of mine of failing midterms and then—and doing better on the final. She really challenged me, and that was absolutely a fantastic experience in the end. And it was one of the classes that I loved the most. You know, it’s hard to say what I loved the most. But that was definitely super influential.
I think there were also—
Well, I was going to say there were other scientists who I did research with, but never took a class from, who were extremely influential on me.
Two forward-looking questions, as an undergraduate, how did you come to focus on physics for graduate programs, and what advice might you have gotten about going beyond Canada for graduate school—
—in a way that probably in high school, going to an American university was, I would assume, not on your radar?
It was actually—
—I mean, just briefly. I almost went to MIT. But, especially once you see, the relative cost. With far more modest scholarships, I was basically able to get an education completely free in Canada that is absolutely on par with the education I would’ve gotten at MIT, which would’ve led to an unbelievable amount of debt and—
—yeah, who knows? I’m sure that would’ve been wonderful too. So I did consider it, but I didn’t apply super broadly in the US. It was just sort of random, like, I thought “that would be really cool.” MIT seemed like a place that also values having a balance of many different area of study, and really going after them all rigorously.
But, your question was more about how did I end up getting into physics for my PhD. And that does have a lot to do with my summer research. I took lots of physics as part of my program, and I did summer research pretty well every summer as an undergraduate. And for two of the summers, I went to the Institute for Biodiagnostics, which was part of the National Research Council in Canada. The NRC comprised a series of national labs, which, sadly, don’t exist the same way they did then.
But I was really fortunate to end up in a program whereby I spent three summers in a national lab setting in Canada, and two of those at this Institute for Biodiagnostics where my mentor was a scientist, David Hoult, who has done some pretty pioneering work in the early days of magnetic resonance imaging. He originally worked at NIST in Bethesda and moved to Canada to work at this Institute for Biodiagnostics. Anyways, I went there, and originally I thought I was going to do biomedical engineering, which was aligned with my interests at the time.
And it just turned out that the project that he had planned for me was very pure physics. We were measuring spin noise. You know, we typically spend all this time as experimentalists optimizing the signal-to-noise ratio and he had me do a calculation to optimize the noise-to-signal ratio, and—I made all these fun gadgets. It was so great, it really was. It really felt like arts and crafts in a lot of ways, and of course there were calculations, and it was just a great blend of all these things, a fantastic, fantastic project.
And I believe that that really helped me to see that I wanted to do something that wasn’t so applied. And at the time also, this may sound cliché, but, I was reading Richard Feynman. Lots of popular Feynman books, and just learning a lot about light matter interactions in his general book about QED. And in the research that we were doing, the explanation that we provided for what we observed was, these words that I learnt from David, “an exchange of virtual photons.” And [laugh], that was the first time I heard these words and I thought “this is really cool,” and just reading Feynman’s intuitive descriptions of virtual photons… I felt, “oh, my goodness, this is amazing.” And I was really hooked by those virtual photons.
And I don’t remember if that was during the summer after my second or third year at university. But, I just—I even changed as much of the curriculum in my fourth year as I could within engineering science to take all the physics classes that I could in my final year in order to be as ready for a PhD in physics as possible.
Naomi, did you apply to Harvard just by reputation? Did you know about Lene Hau before you got to Harvard?
I did know about Lene Hau before I got to Harvard. I had a printout of her cover of Nature paper, bicycling at the speed of light—it was completely wrinkled with handling. I had tried to decipher it, probably not very successfully, over and over again, because I was absolutely fascinated by it.
Did Lene’s genius jump out at you even from the printed page at that point?
The work just seemed really different and special. I just—it was really unique, and I was really drawn to that. After the virtual photon excitement with David, I needed to do an honors thesis in a research lab as part of a program requirement for my engineering science degree, and that was actually the only time I did research during the semester. And I worked in the quantum optics group of Aephraim Steinberg, and so I continued learning more from the technical scientific side as an undergrad in his group. And there was just a great culture of people there excited about quantum optics. I asked way too many questions—
—[laugh] of the students and also of Aephraim. He was very generous to me, and so he’s definitely, you know, a professor who stands out as being super influential, along with David Hoult, whom I mentioned. And so in my final year at university I was just swimming in quantum optics, and atomic physics, and so, in particular, Lene’s work stood out to me. And, so, that was definitely the motivation, I believe, to apply to Harvard.
But I also didn’t know very much about, you know, who’s who and all of the other amazing strengths of that physics department at Harvard. And a lot of American students will apply to bazillions of places for grad school. And I didn’t really have a whole strategy worked out. And, so, it was one of three places in the US that I applied to, and I probably applied to maybe three places in Canada also.
And I felt like I was pretty late coming to all of this because I’d switched to the physics focus pretty late in my undergraduate degree. So I didn’t really have a backup plan. I wasn’t sure what I was going to do the following year if I didn’t end up in any of these graduate programs.
What were your initial impressions of Harvard generally when you arrived in Cambridge?
[laugh] I don’t know if you want to know.
I do want to know.
My visit there, I—it wasn’t even about imposter syndrome. I was … repulsed [laugh]. I mean, I felt like—
You mean like alpha-nerd male kind of repulsed?
Oh, no, no. I mean on the prospective grad student visit. So, first of all, it probably didn’t help that I had stayed up all night before my flight to try and finish my classical mechanics homework because—that was an amazing class, actually. And I don’t remember that professor's name off the top of my head, and I regret that because I loved that class so much. It was amazing.
But, yeah, I was still trying to finish it because when I told him, “I have to go to Harvard. I’m not going to be able to turn in my homework on time,” he said, “Well, either you turn it in or you don’t turn it in.” As he should have said [laugh].
So, I was probably pretty tired by the time I got there. But, you know, it’s self-directed, so you go around, you have your meetings with faculty, and get lab tours, and stuff like that. And then they encourage the visiting prospective students to go to meals with one another. And I felt like a real outsider. I felt like even though I was coming from this giant metropolis of Toronto, and—I don’t know how the University of Toronto is ranked in the world, but it’s a major—
—university in the world. And it holds its own. And somehow, I ended up at lunch with a bunch of people, many of whom became great friends, who had all gone to what I viewed as more privileged, private, exclusive American schools, and it just—I perceived that as being so foreign, and from my vantage point they seemed so like they were all entitled to be at Harvard because they were just doing a trade between one of these institutions and another. And I was just some outsider. They probably didn’t see me that way, but I felt that way. So, I just didn’t want to be around that.
—that wasn’t really what it was about for me. And looking back, I imagine they were at least partly staying together there at the visit because most people are afraid of strangers, right, and they had found some sort of connection with one another.
So, that’s the sociological aspect. In the courses, right, when you were actually in courses with, you know, fellow students who might’ve been physics undergraduates at Princeton or Caltech, was—were you underprepared, not because you were coming from Canada obviously, but because simply you just weren’t a physics undergraduate?
Yeah, an emerging theme you may notice in my career that I often show up [laugh], you know, unprepared—
—not in a literal sense [laugh] but, I mean, without all of the official credentials for something, and then I just try and learn it, you know, from the back end. And, so, I guess it was that way there too. I mean, I think I—technically, managed to get all of the requirements in. But I’m sure I spent less time focusing on those things.
For example, I never took particle physics or some of the other courses that would’ve been elective. I did all the labs, and I got all my semesters of quantum mechanics in, and, like I said, classical mechanics, and I took statistical mechanics, and I don’t know what else. But, yeah, what I experienced upon arrival happens to virtually every first-year physics graduate student—or not only in physics; probably like any [laugh] graduate program.
You show up, and you think you’re prepared… I remember thinking at Harvard, well, the standard that we took in undergrad was five classes per semester, and they’re telling us that we’re only supposed to take two classes per semester, that that’s normal—maybe three—and teach. Well, that seems like not very much. I think this happens a lot. And then you realize, yeah, but these two classes are all like that classical mechanics class that I took that was a lot of work in undergrad.
So, I think it’s that just, not knowing in advance that there is another level of rigor and length of problem sets and extrapolation that needs to be done. And then between that and, in particular, the E&M class that I took in my first semester, it was a course from Jene Golovchenko, and he—who, incidentally, was just like a fascinating, fascinating person—he was teaching it for the first time after it had been taught by somebody else for a long time.
And he decided he was going to do a whole bunch of differential geometry in the beginning, and that really threw me for a loop because I didn’t know what the prerequisites were for that. So, there were events like that. But, yeah, I think whether people articulate in their first year of graduate school that they’re mostly feeling like, “maybe this was a mistake. Maybe I don’t belong here.” I’d say the majority of people feel that way. They don’t all act the same as a result though.
Do you have a clear memory of your initial interaction with Lene, and did you superfan that interaction? Did you tell her how much you admired her?
My gosh. I’m not sure I remember details of the first time we met.
Was it a class, like, in a hallway?
It would’ve been during that visit, when I had mentioned it felt like I was surrounded by entitled people from what I viewed as fancy places who are now my friends, but who probably didn’t all feel as entitled as I had believed, by the way. It must’ve been during that visit. Actually, one thing that is kind of interesting is I remember there being a meeting on my schedule that I hadn’t requested with Jene Golovchenko, and him asking me, “What are you interested in?”
And I thought, “I don’t know why I’m here because this guy does condensed matter, and I like light.” And when I told him, “I like light,” he said, “Oh, you need to talk to Lene.” And, so, I don’t know if I already had talked to her at that point. But I was definitely excited to, and I had my crumpled paper. At that point, her lab was at the Rowland Institute—
—which at that point wasn’t part of Harvard.
And I recall her driving me over to see the lab as a part of that visit. So, that was probably the first time that we met. I don’t know if I was effusive or not. Hopefully, I was polite.
What was Lene’s research? What was she working on at that moment in time?
Her research was ultraslow light in Bose-Einstein condensates, and that’s what I ended up working on with her. And, there’s no way to reproduce the excitement and enthusiasm with which she could describe it, but I’ll do my best because obviously I was very excited to join that project, and to work with her on it. I think what really caught many people’s attention was the mind-bending concept that you could take a pulse of light and somehow slow it down to bicycle speeds, so, only meters or tens of meters per second in a cold atomic gas.
And slow light became a whole field, and there are many people who participate in this field, and I don’t really follow it anymore. But I believe that was just tantalizing to many people. And for me, it wasn’t so much that you could slow it down, basically by manipulating the group velocity of a light pulse inside of this medium. It was the fact that the way you did it was not just to send this light pulse into a cold atomic gas, but it required another light pulse that you used to control the optical properties of the medium.
So, there are lots of ways to describe it, for example, you could say you’re dressing the atoms with that light field or talk about it as an interference effect. But it basically required that there be this first light matter interaction that would make the combined light-matter medium dispersion—how the index of refraction varies with photon energy close to resonances—have more wiggles in it to facilitate this very slow group velocity for the second light pulse. And there are all sorts of other things that were cool about it. I mean, the fact that you’re basically doing those sorts of manipulations, that you were basically creating this spatiotemporal quantum mechanical superposition between different atomic states. In her case, they were sodium atoms.
Was your sense that Lene’s research was geared exclusively in a basic science framework, or were—was she thinking about applications at all?
I think the questions were always rooted in basic science, and one thing that she really fostered was a need for really deep understanding. And we resonated a lot in that way. Of course, there were connections to quantum information or quantum communication applications, and it’s always amazing to ask yourself, “Wow. What if this could be the concept or the component that opens up the possibilities for a lot of really sophisticated technology?” But I didn’t get the impression that she was trying to make a device.
And what was—?
It was always about ‘why’.
What was the intellectual process for you developing your own thesis research? Did you come to her with an idea? Did she hand you a problem? How did all of that work?
Well, that’s the sort of thing that always evolves. You don’t just say, “This is what my thesis is going to be on,” and then some number of years later that’s what actually happens—
I definitely wanted to work on that project, in fact, but the first project that she had me work on when I started in her lab was not that. I ended up moving over to that a little bit later. The first project actually turned out to be the project that my spouse did for his PhD.
We didn’t want to work on the same thing. He really wanted to work on that project, and he did in the end. I don’t remember the details of that transition but as with many things in life, it ended up working out.
And I mentioned that the lab was at the Rowland Institute, and so one of the first things that I did as a graduate student, once I joined that project, was to completely dismantle it and move it to Harvard. And that was a great learning experience, and it took quite a while to be able to set the experiment back up again. You know, we marked our progress by mapping to what year it had been when they had first achieved one milestone or the other. Like, “Oh, at this point, we’re back up to 1998”— this was in the real-time year 2001 or 2002.
“Oh, we’re at 1998 right now [laugh]. We’re at 1997 [laugh], and we gained this capability.” And we made a lot of improvements and made many aspects more robust. But then there was a certain point when… it worked. And as is often a great approach, you pick back up by trying to reproduce the most recent work. And, so, that ended up being trying to use these slow-light pulses to look at interesting density excitations in the BEC. You see, the light pulses are not only slowed but they get shorter in space by the same amount that they get slower in time.
And they had already published the paper looking at the shockwaves that emanate from the Bose-Einstein condensates as a result of that, and the ensuing dynamics. And, so, I was doing that too, and that set the stage, as it turned out, for the first—I don’t know—I guess few years of—more than a few years of my PhD.
And, so, that grew out of saying “let’s start with where we had previously ended up,” but then realizing various things. For example, the simulations had all been in 2D, but the gases were cylindrically symmetric. And I don’t know at what point we started— Lene had the idea that rather than just make one of these compressed light pulses in the condensate, which basically ejects a bunch of atoms from the primary condensate hyperfine state and leaves a hole in the middle, that we should instead make two and send the resulting shock waves on a collision course.
In any case, whether you make one or two, you generate these shockwaves, and they shed these solitons, which, in principle, would be non-linear structures that would preserve their shape, and not be subject to dispersion as they propagate along. And, in this case, they become unstable in the transverse direction, and decay through this instability, and generate vortices. And because everything had been done in 2D in the simulations, the mental model was in 2D, and one of the things that I remember realizing and really trying to persuade people of is: this is 3D. It’s cylindrically symmetric. These are vortex rings, not pairs of vortex lines!
And that led to a lot of exploration in that work using these compressed light pulses to be able to set, like Lene had hoped for, shockwaves and solitons and vortex rings on a collision course with one another. And how do they interact? The way that they interact ended up fundamentally being related to the fact that it was a three-dimensional structure. And that was the first new idea that I felt I had contributed to the project, and I spent an awfully long time making these movies and trying to explain what we were seeing and doing lots of numerical experiments, as I like to say, as well, in order to figure that all out.
When did you know or when did you consult with Lene where you had enough that you were ready to defend?
I don’t remember.
I guess the question is, was there a natural sort of satisfaction that the experiment had gotten to a place where—I mean, it never really ends in such a clean way. But what convinced you that you had something that was complete enough to at least talk about in a thesis defense?
So, that one project was a superfluid hydrodynamics project. And that took me through the majority of my PhD. But it seemed to me, and probably also to her, that that wasn’t a whole thesis. It was very involved, but that wasn’t a whole thesis. And, so, I think I knew, I’ve got to come up with another experiment to do. And it wasn’t super obvious what that should be.
And I remember talking to various potential collaborators, and brainstorming ideas, and experimenting in the lab, and checking out whether there was any interesting physics coming out. And I don’t remember exactly where it all came about. But the experiment we ultimately decided to follow through on, along with Sean Garner, who joined as a postdoc in the lab toward the end of my PhD, was basically to make not one of these condensates but two, and to try to demonstrate that if we completely stored one of these light pulses by first compressing it in one of the condensates and then shutting off that controlling light field, that if we got the momenta of the laser beams and the momentum imparted to the part of the BEC that gets ejected—if we got all of that right, then that ejected matter wave would be able to translate over to the location of a completely separate condensate. And if we were to flash our control light pulse on at the right time, we would be able to revive it, and make what was probably the world’s most complicated optical delay line.
So, that ended up being the final experiment of my PhD that we ended up going for. And I don’t remember when we decided, OK, this is the moment. This is good enough. But I do remember Sean and me thinking, “OK, we’ve got the data we need”. And the way that we had obtained it was to first make one Bose condensate, and then separate it into two pieces by applying a potential that drove the atoms to two separate sides. And Lene saying, “You know, to really unequivocally show that this doesn’t have anything to do with a well-defined relative phase between those two condensates, we’ve got to form the condensates separately from one another.” And, so, we did end up doing that, and—
Why was that insight so important?
Well, it was more proof that the reason for the result wasn’t because there was already some coherence between the source of the matter wave and this receiver for the matter wave. So, in the end, I agree with Lene—I agree it was a good idea, and I don’t know if the outcome in terms of the review process would have been different otherwise. But, yeah, it made it more cool to me in the end [laugh] as well. But, I don’t remember a specific moment or anything like that.
Who else was on your thesis committee, and did they have actual involvement in the experiment?
So, Jene Golovchenko was on my thesis committee as well, and so was Michael Brenner. And Michael Brenner—you asked me earlier about who were influential professors who taught me as an undergraduate. I would say Michael was an extremely influential professor who taught me as a graduate student. He taught possibly my favorite course that I took as a graduate student, which was an asymptotic methods class, and he was—he still is—an amazing teacher. And he was so dedicated, and the homework was so hard—but I loved it.
And, so, I feel as though I got to know him pretty well by taking his class to start with, and was very enthusiastic, not only to have him on my thesis committee but to engage with him throughout my PhD. He was one of the people, for example, that would brainstorm with me, for example, “Maybe you could make a mushroom cloud in a BEC, the scaling of how it grows would be like so, because the”— all sorts of amazing applied math.
But he was also, I should say, just unbelievably supportive of me, and continued to be even after my PhD. So, I was grateful to have him there for multiple reasons. And, incidentally, Lene thought that since we were doing fluid dynamics, we should ask how Howard Stone, who, as you may know, is a sort of—well, not sort— a preeminent fluid dynamicist of our age. And Howard is also an amazing teacher and is very supportive. He’s also very self-deprecating, and when I asked him, he said, “Oh, I don’t know enough to be on your committee.” [laugh]
Were you self-consciously looking to switch gears after graduate school? Did you know that you wanted to do things beyond your work with Lene?
Yes, absolutely. Much as I really was engaged by that work, I was ready to try and study something that existed outside of the vacuum chamber by the time I was getting close to finishing my PhD, and I didn’t know what that was going to be. Just like I was attracted to the engineering science program because it was challenging, I knew I wanted to keep on doing something that was challenging, and for me, science was so much about light matter interaction, and I wanted to continue with it being that way.
I explored a lot of biophysics because it definitely happens outside of a vacuum chamber, and I thought it was kind of curious. And I mentioned a while ago that I had this interest in—I was talking specifically about the human body but, at least, that’s biological, so I thought biophysics would be a place to investigate. And a lot of what I saw, I was worried that they might not have the sort of technical challenge.
There are a lot of challenges in doing good biophysics experiments, given the stochastic nature of living systems, but they don’t usually involve, you know, two laser tables full of optics and all the electronics that run everything inside of a vacuum chamber, which was an overt type of challenge I was familiar with at the time. I felt I enjoyed that complexity on some level. And that was part of the reason that the biophysics that I did end up choosing to do as a postdoc involved, you know, a complicated laser system and optical setup too.
Where were you looking? What was compelling to you at that point?
I don’t know. It was all new and different. So, I probably, knowing me, looked exhaustively at anything that you could possibly find when you google “biophysics”. Yeah, and a lot of what I didn’t choose, I currently find really fascinating.
And, no, I don’t have the skills to do those things now, and I wish I did. Of course, I wish I had the skills to do all sorts of things.
What was going on at Berkeley Labs specifically in biophysics?
Oh, tons of things. But—
No, I mean, for you—that you were specifically interested in.
The big part there for me was photosynthesis. And the reason that I was ultimately drawn to that was because I like light-matter interactions. And, so, here was a system that definitely existed outside of a vacuum chamber, but where you could excite and probe it with light because the primary steps of photosynthesis involved figuring out how to take light energy, and turn it into something else. How does that happen?
And I didn’t know anything about the ultrafast processes in photosynthesis that I ended up studying. My only experience with anything ultrafast, rather than ultraslow, involved another summer research experience at NRC, in this case with Paul Corkum, one of the kindest and certainly most creative scientists I’ve had the good fortune to work with. We most recently caught up at a conference and recorded a short interview, actually, for a class about getting into undergrad research that I was teaching, and it reminded also of how curious he is, too, which also made him an amazing mentor.
In any case, I’m not certain, but I think that one of the ways that I sort of got on to photosynthesis was through a conversation with Michael Brenner, who had met Jay Keasling at LBL, who has developed all sorts of things, including, how do you study termites in order to break down cellulose, because that’s something that human beings don’t know how to do as well.
Cellulose is what gives plants their structure, so he must’ve learned more about plants at LBL and told me “Oh, you should look into this.” And, independent from that, in my web surfing, I found Graham Fleming’s website, and thought, oh, maybe this is the right way into photosynthesis for me. Maybe this was the connection. Incidentally, Graham Fleming, who was my postdoctoral advisor, and is now my colleague, he’s a big deal, right. If you’re a chemist, and you don’t know who Graham Fleming is then, you’re on another planet.
He’s known not only for photosynthesis but also for pioneering work in moving the study of physical chemistry to the solution phase. I didn’t realize that, before then, most experiments were done in vacuum chambers, too, with molecular beams, so not so different from atomic physics. Anyways, I didn’t know who he was. I didn’t know at all. When I emailed him, and asked him to interview for a job, I didn’t know who he was. I think it took me until I was at my first conference as a postdoc, and introducing myself to people. When I said, “I work in Graham Fleming’s lab,” they would say, “Oh!” I didn’t know he was this big important chemist, but their tone indicated so much. So, hopefully, he’ll forgive me for saying that. [laugh]
[laugh] Naomi, to go back to something you said earlier which was striking about how the national laboratory environment is built for interdisciplinary approaches, did that sort of wash over you immediately when you got to Berkeley Lab? Did that sort of get you excited in a way that being in just a department or in a particular lab, you know, was limiting to some degree?
I think that the prospect of it being multidisciplinary, that definitely seemed really cool. I don’t know how much of that I ended up encountering immediately, being a postdoc working on a specific project. I mostly remember thinking, it’s really beautiful, and it smells good here because there are all these eucalyptus trees [laugh].
But it was actually around this time of year, it was late May, and—I don’t know—well, it’s fragrant here many times of year but it’s especially so with the eucalyptus, and seeing the view, taking the bus up the big hill to LBL in order to get my ID and HR paperwork. You know, that was just really awesome in the true sense of the word. But, some of these things that I mentioned about brainstorming and putting people together in teams and so forth at LBL, that became apparent to me as a postdoc participating in some aspect of the onsite grant review, and seeing the other collaborators, and interacting with them, and seeing not just our collaborators but other related projects within the same division who were being reviewed at the same time, and what they worked on, and the fact that all of the scientists being reviewed were all familiar with one another. I think that is definitely something that you wouldn’t necessarily get if you were a postdoc in a traditional department—with your blinders on, trying to get your work done.
Naomi, besides being in a brand new environment operating in a brand new field intellectually, what sensibilities or what did you learn from your thesis research that might’ve been just generally valuable scientifically? What sensibilities were valuable that you learned in graduate school in terms of how to do the science that you wanted to do that you might’ve carried with you?
So, this is the thing I always like to emphasize to trainees – that your skills are all transferable. It’s not always clear when you’re going to use which skill or which idea. And there’s a lot of unlearning you have to do when you move from one place to another or one sort of research area to another. But, yeah, they all end up being useful.
I mean, basically as a PhD student, your job is to learn to solve problems. Some people’s problems are more interesting than others. Some of them involve more plumbing, and some of them involve more pencil-paper work, and so forth. But you basically develop the facility to solve problems, and troubleshoot, and hopefully also to see the big picture, and synthesize information.
And, so, I think one thing, at least, what I hope most new postdocs realize is that even though they’re encountering a lot of unfamiliar stuff, their skills are more transferable than they anticipate. So, yeah, I think that that was really important. For me, coming from atomic physics, I still remember this moment, having this discussion with some of the graduate students in my postdoc lab, and realizing that they were measuring the width of their—spectra in nanometers. There are lots of other units you could use for that.
But I remember telling them, “We measure our linewidths in megahertz.” And I don’t even know how to convert megahertz to nanometers in my head—the number of nanometers would be equivalent to way, way too many megahertz. It just would not make sense to do that. So I thought, “Why is this so different? Oh, my goodness, I joined this lab without really realizing that the fundamental thing that’s different about the systems they study here, and the atoms I studied before, is that because molecules have bonds between atoms, they vibrate and that leads to this giant mess—this much broader linewidth.” It sounds embarrassingly naïve not to realize this, but it’s all about context. I had such a different context. Why would someone studying atoms have vibrations at the forefront of their mind? So, I mean, there are all sorts of things that—you can put all of those sensibilities to work, but you have to do a bit of digging in order to figure out where they belong and what you have to shed.
Did you have a mentor at Berkeley Lab—
—in the way that at Harvard, you know, Lene …was so obviously your mentor, among others?
Well, yeah, I mean, Graham was my mentor, and his mentorship style was different from Lene’s. I didn’t have as much interchange with him about all the gory details of my project, but he has this amazing knack for listening to a trainee describe their problem or describe their progress, and then zeroing in right on the key point that will help them to make progress. I hope I now do that for my trainees. It takes a lot of experience.
For the gory details, the research group had lots of really amazing people working in it. And that was part of the reason I wanted to go there was that there seemed to be great people to work with and learn from, in addition to Graham. And, in particular, you know, we had offices in pairs. And I felt I learnt an awful lot from the two officemates I had in sequence. This is why it’s really important for people to be in the office together – to learn from one another.
So, they both happened to be theorists. One of them just, by the way, was Yuan-Chung Cheng, and then the other was Aki Ishizaki, who are now both faculty in their respective home countries. Well, Yuan-Chung is in Taiwan, and Aki is in Japan.
And, yeah, maybe coming from a physics background, it was a little bit easier for me to connect what I knew or, to have what I knew translated into this new language for me by talking with theorists. I’m not sure. But, yeah, it was absolutely wonderful. So, we were peers but, in some ways, I felt that they were also mentors.
Did you start gradually being involved with UC Berkeley, or that happened only after your postdoc was coming to an end?
Only insofar as the fact that the lab itself where I did my postdoctoral work was on the UC Berkeley campus. My affiliation was with Lawrence Berkeley Lab. So, in some sense, I was already physically at UC Berkeley. So, there’s that. But the only way in which my affiliation with UC Berkeley was gradual was the fact that the academic job market takes a really long time.
Did they specifically hope that you were going to stay? Were they proactive about that?
I don’t think I was identified in advance or anything like that. I knew I wanted to apply for academic positions. In fact, most of the positions I applied for were in physics departments. This was, by the way, around the time of the Great Recession. So, there weren’t that many positions of any sort in 2009-2010.
And I remember Graham as a really incisive mentor, saying, “I think you should apply for some chemistry positions too.” So, at that point, I suppose I must’ve had a very strong physics identity, and physics culture seemed, at least in my experience then, to foster a strong identity that looks more inward that outward—that does necessarily believe that science beyond the traditional discipline of physics is what ‘we’ do or that that science could actually interest ‘us.’ ‘Othering,’ as it’s now called, is a part of the culture of physics that is slowly disappearing, and I personally believe it needs to disappear. There are now lots of efforts to make Physics more inclusive, and I really appreciate that for so many reasons.
One difference in the cultures, however, is that chemistry departments tend to request applications and interview people for positions earlier, so I’d missed most of the application deadlines for chemistry because I was targeting the physics ones. One of the only places that still had an open job ad was Berkeley, and so I applied to the Berkeley chemistry department. So, that was pretty fortunate, especially given Graham’s advice.
That, and in terms of applying for jobs, one of the most important lessons I learnt from him in terms of pivoting my career to where it is now came from him really trying to emphasize how important it is to state the motivation and the importance of your problem clearly. And he is still, in my view, the true master of doing this. And that’s something that I’ve tried to convey on to my students ever since he really conveyed it to me when he listened to the first version of my job talk.
Why not just stay in the lab exclusively like so many people choose to do? Did you specifically want more interaction with students? Was there a culture of an academic department that was attractive to you?
I love teaching. So, I definitely wanted to do that. It’s also not that easy to, you know, get a job at a national lab.
You know, they don’t just have a position that’s open like that so frequently.
What are the origins of the Ginsberg group? When did that essentially come together? Was that at the beginning of your faculty appointment?
By design, a faculty appointment on this continent at least requires that you have your own research group. So, yeah, those were definitely the origins, and so I basically—I moved downstairs.
A big move.
[laugh] Functionally, a lot changed though, having my own research group.
So, I moved downstairs into this initially and temporarily quite a small space where I was supposed to house whoever I recruited to my lab. And then, when the new crop of graduate students showed up, I did my part [laugh] telling them, “Here are the opportunities in my lab, and these are the sorts of projects I want to work on.” And fortunately, people joined my group, and that was very exciting.
And for the first year they were still preparing my lab space for me. At that point, I had a few students, and had hired a postdoc, Cathy Wong, who is now a professor on the chemistry faculty at University of Oregon, who’s just coming up for tenure. And she had joined before we had access to a lab, and before we’d gotten our first laser, and so we did a lot of planning and ordering parts from McMaster-Carr.
And it’s hard to try and teach people how to equip a lab from scratch rather than just going to the toolchest and grabbing the right wrench. There are a lot of possible wrenches you can purchase at McMaster-Carr. But, anyways, that was the beginning, and we grew, obviously. I still remember cracking open the crate for my first laser.
But I remember cracking the crate open, and being so excited, and telling my first graduate student, Sam Penwell, “Sam, really hard work bought this laser.” It seemed really profound to me coming out of my mouth. And, yeah, each time you have to build a new lab or start a new experiment, it’s just a huge, huge investment every time. But then before you know it, you’ve got a whole operation.
And then there’s—often, postdocs who are trying to come up with plans for their faculty applications, find it really hard. I found it hard to come up with experiments that nobody had done yet, too. But there’s some sort of phase transition that happens, right. Next thing I know, there are so many experiments I’d love to do, and there is just no possible way I would ever have the bandwidth to carry them all out all at once.
Naomi, I’ll update my question about going into a new field from graduate school to postdoc specifically because you’re now entering yet another new world in chemistry. To what extent was that a launchpad to do more different stuff, or was this less of a transition from the national lab into the department?
So, the crazy ideas that I did come up with for my faculty job proposal were thematically related, but they were not in any way a continuation of the work that I did as a postdoc. And so, in that way, I was already in unknown territory. So, for example, I mentioned cathodoluminescence, and that was part of my job proposal.
And the idea was to use a very thin scintillating material as a sort of barrier film and transducer for electrons to light. So the barrier idea was that we wanted to put an encapsulated photosynthetic membrane on one side of the film and have the vacuum environment in the chamber of a scanning electron microscope on the other, and try and image the dynamics inside this photosynthetic membrane. And there are a lot of really interesting questions of how the membrane structure dynamically reorganizes on scales that weren’t really accessible. I’d never used an electron microscope, let alone cathodoluminescence. I probably didn’t know the word before I wrote my proposal.
And, so, I was terrified that at one of my job interviews, somebody would ask, “Oh, well, but do you actually know anything about electron microscopy?” But nobody even asked, which was good. And, same, I was terrified when I first went to LBL to visit my now longstanding collaborator Frank Ogletree, who people had told me I should talk to if I was interested in doing this in case we could connect. Frank knows all the instrumentation and capabilities like the back of his hand, and I was terrified that he would find out that I had no idea yet of any practicalities. My knowledge was completely theoretical.
That’s just one example but there were elements that were related to my experience. For example, a common thread was the theme, the motivation of photosynthesis, and aspects of photosynthesis, which I had learnt a lot about as a postdoc. But I was asking questions on different scales, and in particular, I was asking about more directly looking at space, not only time. During my postdoc, we were looking at what happens in the very first instants – femtoseconds and picoseconds – after light is absorbed by chlorophyll or some other pigment in a protein that binds all of these pigments. And then asking, how does that energy move around among the different pigment molecules in the protein?
And, in my own lab, I needed to use spatial resolution and imaging a lot more explicitly because I wanted to look either at how those proteins reorganized relative to one another in a membrane, or, the other side of things was to ask questions about how not only does the energy get through one chlorophyll in one protein to another chlorophyll on the same protein, but how does it get from wherever it gets absorbed in that membrane in one protein all the way to some other more distant spot? And it doesn’t have to go far—this is where the nanoscience is super important—but it needs to get there, and how does it get there? And, so, the motivation was familiar to me. But we had to develop a lot of instrumentation in order to be able to try and answer that sort of question.
Did you take on graduate students right away? Was that important to you?
Yeah, absolutely. I did, but my bandwidth is definitely limited because I do like to be intellectually invested and contributing to the work that we do. And, so, I didn’t take on graduate students super, super quickly. Of course, before you know it, there’s a full lab of trainees. But, yeah, I definitely believe that if you want to take risks on the science, you also want to find the people who are also really, really excited to take those particular risks. And, so, that and my bandwidth are probably the factors that determine the rate at which the group grew.
Naomi, in terms of your connections to the lab, and the obvious connections that that would have to DOE, where is NSF at all in your funding?
Well, NSF, like I said at the very beginning, is really instrumental in my funding, and it’s funded so much of the imaging development that we’ve done. So, well before we worked to propose this science and technology center several years ago led by Margaret Murnane, focusing on real-time imaging, I submitted a proposal to NSF to do the cathodoluminescence work that I was describing earlier. We call it clear cathodoluminescence-activated imaging by resonant energy transfer, basically this way of using a scintillator to protect really delicate materials so that you can study their dynamics.
So, that was the first NSF proposal that I wrote, and I squeaked in getting funded right at the end of the fiscal year. And, so, NSF has always funded a lot of the imaging development in my lab. And I would say that they don’t only fund the research. I think one thing that is really special about NSF is that they are putting effort and encouraging all of the people who they fund to emphasize diversifying who does science, and issues of equity in science, and access to science education. And that’s another essential part of the mission, and something that’s been very natural to integrate into the research as part of the science and technology center—no small part to thanks to Margaret.
Naomi, what was your sense of the culture of promoting junior faculty at Berkeley at that time? Were you under the impression that junior faculty were hired with the intent that they were given the opportunities to succeed, or was it not like that?
No, it absolutely was. So, it was very clear that there was a place for everyone to continue, but that you had to earn the right to continue. But it wasn’t about weeding people out in any way.
The dual appointment with chemistry and physics, was that in some way similar to the intellectual environment that you had at the lab where you had multidisciplinary access, or was it entirely different?
Entirely different; two completely complementary cultures—
—both of which I still believe could learn a lot from one another, and, you know, I kind of see that as part of my role—to shuttle information about the cultures back and forth between the departments. But, yeah, definitely two different cultures, even though the buildings are right next to one another, and so forth.
And what about teaching responsibilities? You alluded to this earlier. But what sort of expectations were there? What did you want to do yourself in terms of teaching undergraduates?
Oh, well, because my appointment was 100% chemistry, 0% physics, whether I was teaching undergraduates or graduate students, I was teaching in the chemistry department. So, that was kind of funny in and of itself. You know, originally they asked me to teach a statistical thermodynamics class for upper-year chemistry students, and I thought, oh, my gosh, I don’t know the words in the syllabus, why are you asking me to teach this?
But I guess you have to teach something, right, and not everybody gets to teach quantum mechanics.
And even if I had taught quantum mechanics, the focus, especially in the undergraduate courses, is quite different in the two disciplines. And, so they showed me, “We really need somebody to teach this class. Here are some of the notes.” And I probably flipped through the first two weeks, and thought, “Boltzmann distribution, yeah, OK, yeah, I can do this”.
I was flying by the seat of my pants teaching a new class, period. But then after those first few weeks, I hadn’t seen any of the concepts before. And, so, I learnt a lot, and I really fell in love with the subject, and I taught both undergraduate and graduate level statistical mechanics many, many times. And the more that I learnt about it and became fascinated by it, the more it overtook a larger portion of the research we do in my lab.
How did DARPA get wind of what you were doing? What was the intellectual connection there?
I just applied for a grant. I just applied for one of their young faculty awards, and I was successful. But there wasn’t any sort of discussion or phone calls to program managers or anything like that.
What was the research that they supported? What were you working on?
What did we propose to do? Something with studying the photoexcited dynamics of organic semiconductors, so basically semiconductors whose basic building blocks are molecules, not atoms like we’re often used to. And we still study those sorts of materials in my lab, and study how energy moves from one place to another on really fast timescales. And it was a function of the heterogeneous structures that they can have, and heterogeneity is still a big theme for us.
So, if you make a film of this material, especially because of the way that it’s made, it’s often polycrystalline, there’s lots of disorder in it. And, so, the proposal focused a lot on trying to correlate the structural disorder with how photoexcitations reside or what character they had in those structures. So, that was definitely the very beginning of some of the ultrafast microscopy work that we did in my lab.
And sort of a broad technology question on instrumentation, between microscopy and spectroscopy, what were some of the technological advantages that have happened, you know, in the past decade or so that have been really important to you?
You mean that have enabled the sort of methodologies that we’ve developed?
Yeah, I mean, when I started my lab, the type of ultrafast laser system that I really needed, like the specs that I needed in order to do the sort of experiments that capitulated my assistant professorship in that area, a technique that we called TRUSTED, time resolved ultrafast simulated emission depletion microscopy, that laser system, we bought in my third year because it didn’t exist when I started. So, having this sort of repetition rate, and total power, and flexibility to parametrically amplify all these different wavelengths—that we couldn’t have bought from the get-go. So, that’s one example.
And then, more recently, we developed another one of these ultrafast microscopies which—so, TRUSTED relies on fluorescence, and we used it to make measurements at very, very sensitive energy migration lengths. And another approach that we developed more recently that we call stroboSCAT—they all have funny names—that really relied on the fact that you can get cheap CMOS cameras [laugh], and do shot-noise-limited measurements. I mean, that wasn’t like super, super new when we started using them but it makes a world of a difference compared to older CCDs. But that development in my lab is something I don’t even want to attribute to myself. That was my postdoc at the time, Milan Delor, who is now on the chemistry faculty at Columbia.
What about computers over the past decade? In what ways have the phenomenal advances in computational power enabled your work, or have made things possible that were not before?
That’s a little bit harder for me to say, to be honest. I guess, the primary thing is there’s so much data. It’s so fast to collect the data. Whether it’s this ultrafast imaging, whether it’s with the electron microscope and the cathodoluminescence. And then especially when you move all the way to the free-electron laser experiments, and there’s the size of these massive detectors, and the fact that you’re collecting as fast as you can. Getting the data to and from the server, just trying to transfer it—that’s an endeavor, and I don’t feel like it’s a challenge that my lab in particular is facing on its own—
Sure, it’s everywhere.
—we’re standing on the shoulders of people who have put a lot of effort into that sort of infrastructure.
I’ll ask a purposefully naïve question. We all learned photosynthesis in biology in 10th grade or whatever, right?
What don’t we understand? What is this high school—
—subject that is, you know, of unlimited interest still? What is it about photosynthesis?
Yeah, that’s a great question. The first few picoseconds, let’s say, of photosynthesis basically involves a process that we cannot yet replicate in any synthetic material. And that is that when the light energy gets absorbed in one spot, the quantum efficiency with which that energy can make its way to this dedicated location, the so-called reaction center where the biochemistry to turn the energy into a storable fuel like starch, that process can occur with near-unity quantum efficiency.
I mean, nearly every photon that gets absorbed anywhere goes into an event at that reaction center. And we don’t know how to make energy flow via electronic coupling between components through any material with that efficiency without there being far more dissipation. So, if we could figure out how that happens, then we would stand a much better chance to develop synthetic analogs which would be important for, basically anything electronic, especially optical electronics—all of the energy efficient lighting that we have, or our cell phone displays, and then obviously also for solar cells for renewable energy.
So, this is really—the goal is biomimicry?
Well, you take what works, and you don’t have to take the rest. I mean, photosynthesis in terms of generating biomass is not super efficient, and people like Jay Keasling are actually trying to increase that efficiency, using synthetic biology. But, like Graham Fleming would say, photosynthesis only evolved to be as good as it has to be.
And after many years of evolution, it’s figured out how to, essentially, get the B grade because it’s also problematic when there’s excess energy that can’t be used, in this case because there’s a mismatch of timescales. That first part happens in picoseconds, but all the actual making and breaking of chemical bonds takes way longer. And, so, if the system gets backlogged, you have all these photoexcited states, which can react. And then there can be side reactions that ultimately lead to killing the plant. You don’t want that. But you do want to take the best stuff always.
Naomi, I don’t want to ask you to name names in terms of all of your amazing graduate students and postdocs, but I wonder if you could reflect generally on some shared characteristics perhaps that your most successful students, graduate students, postdocs have that, you know, their approach to science, their work ethic, the way that they collaborate with others. What have you learned in your own capacity as a mentor that really give you a sense of, you know, this person is really going on to great things?
There’s no one right way to go on to great things. But I think that—let’s see, what sort of characteristics? Open-mindedness and ability to adopt perspectives different from one’s initial perspective. Also, one thing that is really hard but that can always be developed is confidence. Before I had confidence, it probably took until, you know, I had a faculty job offer before I stopped focusing quite so much on self-doubt, everything was just way harder—way, way harder.
Do you see that in gendered terms at all, the confidence issue?
Maybe, but not always. I mean, there are plenty of people of all genders who don’t have confidence. We’re probably socialized by gender to display it in different ways, which—
Right, that’s important right.
—I believe can creates an even bigger divide. I’ve probably been socialized more than you to seek approval for everything, which is probably just annoying for everyone. Other elements, though—curiosity, you know, the sort of growth mindset that really helps people grow. OK, it helps people develop. It begets confidence, and confidence begets it. So, it’s sort of a catch-22 until you get into that good feedback cycle.
But if you can—like, when curiosity is a really big driver—and, I mean, you can be curious about things on so many levels—then I believe that can get people started. And this is kind of a weird thing to say, but faith in outcomes is another trait. Sometimes I tell my trainees, “There’s no substitute for experience. It’s easier for me to believe that your experiment is going to work out because I’ve done way more experiments than you.” [laugh]
And if this is your first experiment in your PhD, you won’t necessarily believe that it’s going to work out yet. Your inherently human negativity bias is probably just going nuts, right. And, so, can you try and have faith based on what I’m saying, at least in the tiniest possible way? And then you sort of ratchet your way up? Those are good ones.
I don’t know. There are tons of good ones.
Yeah. Naomi, just to bring our conversation right up to the present, a snapshot in time circa May 2021, what are you working on right now, or what are all of the things you are working on, because I’m sure it’s not just one?
I don’t know if we have time [laugh].
[laugh] What are you most excited about right now? What’s at the top of your agenda?
Oh, that’s also really hard.
Yeah, it’s so hard. So, there are so many—so, I mentioned the ultrafast microscopy side of things, and that’s still really exciting to me for many reasons. For example, recently, we learnt that not only can we be sensitive to electronic excitations, like charge carriers in semiconductors, but we can also see heat, and we can actually see how heat and charge carriers interact with one another, and I think that’s pretty cool to be able to visualize, and we want to see how far we can push it.
And then I mentioned also that work more closely tied to statistical mechanics is expanding in my lab. So, beyond ultrafast things, we look at a lot of other processes—how do materials form and transform, especially when they have complex building blocks? So, I would call these materials with greater-than-atomic building blocks hierarchical materials. And, so, we’ve been looking at hierarchical materials formation and transformation at multiple different length scales.
But going with the theme of the nanoscale, we’re really getting into doing a series of different x-ray scattering experiments to look at how strongly coupled superlattices of nanoparticles are able to be formed. A superlattice is essentially a lattice—and ordered solid—of crystalline nanoparticle building blocks. There’s a lot associated with what goes into that. But, this is really largely inspired by my collaborator, Dmitri Talapin, who is an amazing chemist at University of Chicago, and very, very creative, and always—I don’t know—blowing my mind.
So, anyways, he’s solved the problem of how to get the particles close enough to one another that they’ll strongly couple by having these very short ligands that allow them initially to be suspended in a solution, so, very short molecules at their surface. And, there are all sorts of really interesting science questions associated with how all of the different ions in the surrounding solution configure themselves in order to mediate an interaction between the particles that we’re studying with Dmitri’s group and also with my awesome theory colleague David Limmer and awesome experimental collaborator Sam Teitelbaum at ASU. And metal particles will form into these ordered structures, while typical semiconducting ones won’t. And we want to try and figure out how to change that, and we’re hoping to use things like light fields in order to do it.
And I’ve been learning a lot recently about how to probe these sorts of systems at the structural level with the x-ray scattering. And the only actual hands-on science I got to do, for example, during the pandemic was to go to the LCLS [laugh] a month or two ago and, you know, stay up all night [laugh] and do this crazy experiment, trying to figure out, what are the structures of these superlattices that form, and what are the formation mechanisms? So, this is all new territory for me. I’m not yet an expert. But I’m—it’s just another opportunity to learn—yet another opportunity to learn [laugh]. Especially because we’ve assembled this great team that also includes many amazing x-ray beamline scientists we’ve worked with.
And there are so many more exciting things we’re working on, but I see we’re running short on time.
Naomi, now that we’ve worked right up to the present, for the last part of our talk, I’ll ask a few sort of broadly retrospective questions, and then we’ll end looking to the future. So, first, for you, I really have no idea the answer to this question because the breadth of your science is just—it’s just remarkable. So, I’m excited to hear your response to this. If you could think back maybe to even high school or undergraduate when you were really in sort of formative learning mode in science, right, what are some of the scientific concepts or laws or theories or approaches that no matter what you’re working on, always stay close to you or always central in informing the way you go about doing your work?
That is a really hard question to answer after three hours. Yeah, it’s testing my memory too. For me, it’s not about the specific concepts though. I don’t know.
But I feel it’s about experiences. You know, what did I experience? For instance, one of the only chemistry labs I remember from high school involved silver nitrate, and we were cautioned that if you got it on your hands—we studied chemistry in French, so we called it tache noire because it makes these little black spots [laugh].
Anyway, I don’t know what that taught me. I also remember being a smartass, though not deliberately, when we learned about parameters to control vs vary in an experiment in junior high. We had to do an experiment where we selected which parameters to vary and control. My only experiment with photosynthesis in grade school was when I decided to make one of the controlled parameters the illumination—so my plan was to try and grow all these seedlings planted at different soil depths—that was what I varied—in the dark, so in our shed. And, not surprisingly, nothing grew. And, so I should’ve known that. Maybe I already did but was just trying to be original, not a smartass. I don’t know why I decided to do that, but I still remember it to this day.
I still remember the first time I stayed up all night doing a science fair project with 11 cups of lemon tea, kind of shaking [laugh] by the end in order to finish this massive study, trying to observe how much carefully cut swatches of different types of fabric shrank as a result of—I don’t know—eight different permutations of washing and drying variables [laugh]. Those are the sort of formative experiences that come to mind, but not specific concepts.
Looking over your publication list with the mind-boggling number of topics that you’ve tackled, and also the number of collaborators that you’ve had, what’s the through line in terms of the way that you work with collaborators? In other words, is there something that’s always the same regardless of the topic or the people that you work with in terms of what you specifically bring to a collaboration either in terms of work style, or your approach to experiments, or anything like that where you see connecting points no matter what it is that you’re working on?
No—but I would say that the sort of strength of a really successful and long-lasting collaboration is to have a really strong and balanced mutual interest where all parties are equally engaged whether for the same reason or for different reasons. It’s about sharing, right. And communication ends up being really important, so if you can’t communicate with the people or what you want to do is not engaging to your collaborator or vice versa, then it doesn’t usually work so well. I mean, you can always make it work, but those things help a lot.
Is there any scientific problem that has gnawed away at you that you’ve always hit a wall no matter how you approach it?
[laugh] Probably. I mean, there are things we can’t yet measure that I really want to be able to measure, and that I’m still hopeful that we’ll measure or that somebody will measure. For example, that question that we discussed already about what happens in those first picoseconds of photosynthesis, after more than 10 years, we’re still gearing up to do [laugh] the measurements on that system, and I believe it is getting closer and closer to actually happening. And I really want to see that through, so stay tuned on that front.
And there is still the question of what capabilities we have to develop in that other example I gave you with the nanoparticle superlattices. And this is a really complicated many-body problem with all these correlations between all the ions that are in the solution around particles, and so forth. And there still isn’t really a great way to directly make a map atom-by-atom, and that sort of resolution will take a really long time to achieve. But, continuing to strive for that ideal, and then doing our best that we can in the meantime, that’ll keep us going [laugh] for a long time.
[laugh] Naomi, last question looking to the future, I’ll go right back to one of the earliest comments you made about, you know, there are some distinctions, but at the end of the day, the science is just the science. And, so, to the extent that that is really where the field is headed, where 50 years ago, the divisions between the departments were really substantive, and biologists did not talk to chemists, who did not talk to physicists, right, how might you see your own sensibilities, your own agenda, the kinds of questions that are going to be currently and into the future most important to you? How might that contribute overall to at least intellectually or scientifically a more—you know, a merging of the disciplines, going more towards a multidisciplinary or interdisciplinary approach?
I believe education is going to continue becoming more multidisciplinary. A perfect example is that engineering science program that I did, more than 20 years ago now, and they continue to evolve their curriculum actively in order to give students more of what they’ll need for the modern workforce. They put a lot of effort into monitoring and updating their curriculum, and the focus options that they offer continuously change. It’s pretty—it’s still pretty hard to get rid of a physics department or get rid of a chemistry department because, from a discipline perspective, they are quite different. So, I think students are going to need to be exposed more to both. But there is definitely a limit to how much stuff you can put in people’s heads before they explode. [laugh]
There I’m kind of quoting Carolyn Bertozzi when she gave an amazing commencement speech for Berkeley Chemistry a few years ago—
—she’s amazingly charismatic and, I guess, dramatic sometimes. But it’s really hard to get right. I mean, if you spread people too thin, then their understanding is shallow. But you need to find the right balance. So, I don’t know what universities will look like—how they’ll be structured 50 years from now. But it’s definitely going to change, and especially physics has to continue working toward a culture that appreciates the science that has historically happened outside of physics departments. There’s actually a lot of physics that happens outside a physics department. Actually, even if you open up the Feynman Lectures, you’ll see that he was pretty agnostic to the labels of disciplines and saw straight to the physics in a really wide and inclusive range of systems. As for many things in Physics, that’s a good model.
And, of course, the whole story with biophysics, that’s central to that. For a long time—
—you know, places like Princeton did not consider biophysics to be physics.
And you’re saying that there are—the vestiges of that remain with this? This is—you’re singling out physics for this way of thinking?
Well, I can’t speak to every scientific discipline.
Of course, of course.
But I have found that chemistry is a lot more eager to embrace various different research topics outside of canonical chemistry, including physics and biology, than physics might be.
Maybe if everyone gives up on dark matter, they’ll have no choice but to be more open-minded?
Well, I’m not calling physicists closed-minded. Dark matter is super important, and I’m really grateful to have amazing colleagues who work in that area. I’m just saying, very generally, that part of our education is knowing what we don’t know. And learning to respect what we don’t know.
I’m also not trying to point a finger at any particular subfield within physics. But I would say that the sort of strong identities that some physicists can have with their subfield—that, if for someone, physics IS their subfield—that’s dangerous.
And that’s something that we will benefit a lot from continuing to change. Maybe the Feynman Lectures are a good example to return to! Actually, Physics Today is a great example of showcasing the diversity of what is physics. Maybe we all need to commit to reading it more thoroughly.
Naomi, this has been so fun to talk with you all these hours. I’m so appreciative we were able to do this. Thank you so much.
Yeah, thank you very much, and thank you for all of these really thought-provoking questions, and for giving me the opportunity to share.
Oh, my pleasure.