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Interview of Stephon Alexander by David Zierler on June 7, 2021,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
For multiple citations, "AIP" is the preferred abbreviation for the location.
n this interview, Stephon Alexander discusses current research into quantum gravity and possible extensions to string theory; work to merge quantum mechanics and general relativity; research into the connection between music and cognitive science; experience as a jazz musician; intersections of philosophy and physics; experience as president of the National Society of Black Physicists (NSBP); challenges and stigmas associated with being a Black academic; growing up in both rural Trinidad and the Bronx; undergraduate experience at Haverford; graduate work at Brown; guidance from Robert Brandenberger into the field of quantum gravity, applying particle physics to astrophysics and cosmology; thesis research on solitons and topological defects and its role in string cosmology and theory; decision to take postdoc at Imperial College London focusing on M-theory and integrating string theory with cosmic inflation; influence of Alan Guth; work on D-brane driven inflation; experience in the underground London music scene; decision to go to SLAC in Stanford and work under Michael Peskin; loop quantum gravity; time as faculty at Penn State; the role and responsibility of the Black academic; recruitment by Brown University; intellectual influence of David Finkelstein; the process of becoming president of NSBP. Toward the end of the interview, Alexander reflects on his books, The Jazz of Physics and Fear of a Black Universe; being an outsider in the field of physics; and revisits his current work on quantum gravity. He emphasizes the importance of in-person collaboration and improvisation.
Okay, this is David Zierler, Oral Historian for the American Institute of Physics. It is June 7th, 2021. I am delighted to be here with Professor Stephon Alexander. Stephon, it's great to see you. Thank you for joining me today.
It's great to be here.
Stephon, to start, would you please tell me your title and institutional affiliation?
Yeah, so I am a Professor of Physics at Brown University. Also, a member of the Brown Theoretical Physics Center, and a member of the Center for Fundamental Physics of the Universe at Brown University. And I'm also the current president of the National Society of Black Physicists.
Now, your affiliations beyond the department of physics at Brown, do they include independent teaching and student supervisory roles, or does all of that happen within the department?
Yes, all of that happens within the department. All of those centers are under the umbrella of the department as well.
Just for a snapshot in time right now, Stephon, circa June 2021, what are you working on, both int he world of music and in the world of science?
Oh, wow. As you know, I'm a professional jazz musician as well as a physicist, and those words have evolved to kind of inform each other now, out of necessity and the efficiency of time, maybe. So, currently, I'm working on some things that I'm very excited about. I think the thing that I'm most excited about is this idea – so, my research overlaps with fundamental physics of any sort and how that informs cosmology – well, I'd say the physics of the very big and the physics of the very small.
So, particle physics and cosmology. That triad are legs on a chair, and the chair being our universe, is the kind of physics I'm involved with. Sometimes that means spending more time thinking more like the fundamental physics than the cosmology, or the cosmology than the – these days, I'm thinking about fundamental physics at the level of quantum gravity. I'm happy to go more into that, but in a nutshell, it's a striking idea that somehow quantum gravity might actually be encoded in a – our four-dimensional gravitational world, general relativity, should not be quantized in four dimensions. The quantum theory of gravity itself is a three-dimensional system. This is akin to the idea of holography, but the way – this thing I'm working on now is a little different in that you don't need to specify any spacetime background. In fact, the action is happening where there is no a priori spacetime. But the dimension, you can still talk about the dimension in a topological sense. But somehow, our four-dimensional world is encoded by a three-dimensional theory that purely encodes topology.
So, that's it in a nutshell, and it turns out I was led to that because of asking some cosmological questions, some questions related to a theory called cosmic inflation. And then the musical side, I've moved into a sort of collaboration with a guy named Robert Rowe and Edward Large, who are people that are cognitive scientists and music composers. Ed Large is at University of Connecticut, and Robert Rowe is at NYU. Robert Rowe and I came up with a mathematical model of maybe how the mind encodes or represents musical tones and chords. It turns out that structure is akin to some structures that we find in the mathematics of string theory, for example. So, it's nice that I'm able to, through collaboration with people who are more experts, be able to export certain tools that I've learned in physics into their field.
To go back to quantum gravity for a second, to what extent are your interests in string theory relevant to your current work in quantum gravity?
I think that some of my training in string theory has informed that, and the places where string theory has been successful – but also the places where string theory still is open ended, and there are some questions that are not resolved, that has informed – looking at what I call possible extensions to string theory. I've also worked on other approaches, so-called background independent approaches to string theory, or paid serious attention to those things like causal sets, causal dynamical triangulations, spin forms, loop quantum gravity, asymptotically free gravity. I have colleagues that I work on all those things, and those ideas as well as the ideas in mathematics and string theory, I say those things inform my work in cosmology.
Let me say it another way. You know there are very clear problems that have an observational flavor to it, because that's what physics is at the end of the day. It's an experimental science. So, that's the god I worship. Really trying to get a sense from talking to my experimental buddies of what the real problems are, or where the assumptions are when they build an experiment, or they make an observation. By paying attention to those open-ended problems, and also where theory comes close to explain or fails to explain – my approach there is to more think about theory as a toolbox that I can use as an arsenal of tools that address those observational problems. Therefore, as a result, why should I marry myself to one theoretical framework over another theoretical framework simply because it's more mathematically beautiful, or more elegant, or more mathematically self-consistent. That's fine, but at the end of the day, nature may not care about what's mathematically elegant or beautiful. So far, it has cared, but we should keep an open mind. So, I kind of look at all these theories as a palette which I can use to address the observational issues.
Now, given how expansive your research agenda is, how fundamental are the questions you're asking? In other words, at the end of the day, is what you're going for trying to help figure out how to merge quantum mechanics and general relativity? Is that really what it's all about?
Yes, I think you've nailed it. I mean, my first PhD advisor, Robert Brandenberger, the very first conversation I had with him was – I was working with Leon Cooper at the time, Leon Cooper the Nobel laureate. That was in the early days of machine learning, actually, and I was looking for experiments. I was looking for a way of using these unsupervised neural networks' data, and I went to Robert to talk about large-scale structure. So, my very first conversation, instead of us talking about large-scale structure, I said, "I have a question, Robert." One of the things that's special about him with students is that you feel enabled to go to him with any deep question that you have, and he's going to pull you in that vortex. I said, "You know, there's this thing in the quantum field theory class that I don't get, and I'm scared." And he goes, "Well, show me." And I showed him a Feynman diagram vertex. So, I said, "If I have a particle going like this, and I draw a graviton, how gravity interacts with two electrons for example, and I zoom in, I'm still going see this discontinuity." And he goes, "Ah, you want to work on quantum gravity."
So, that's – he was right. So, I guess my way into quantum gravity is to say, let's actually look at that vertex, and we realize, what's it saying physically when the electron comes really close to another electron such that they have mass? Gravity needs the equivalence principle. What happens there? Do the principles break down? Does the singularity or the divergence really exist? Does it not? So, I think that's kind of – but that's exactly what the string theorists did, right? They were like, let's look at that. Oh, there's a string in between that that softens the divergence. Okay, that's progress. But my point is – not to diverge, no pun intended – is yes, I'm basically fundamentally interested in that fundamental question about how to unify quantum mechanics or gravity.
Stephon, let's go even deeper than that, given your adherence, your sensibility to the fact that everything in physics needs to experimentally verified at the end of the day. It's a question that's been bothering me for a long time, and that is, to the extent that we can say at the very beginning, physics has an answer for how something can be created out of nothing. Whether you want to call it a vacuum fluctuation; whether you want to refer to the uncertainty principle in quantum mechanics; whether you want to cite any of Stephen Hawking's ideas on this subject. Is that assertion, that physic has an answer, that something can be created out of nothing, is that a theoretical assertion, or is there an experiment that has or will in the future verify that theory?
That's a very good question. I think that question gets to the heart of the matter. If we can pause, that question is so heavy it's going to need what the chemists call caffeine.
Buy yourself a little time to think about it while you're gone, too.
Exactly. It's really a way for me to let me bounce out of here. Okay.
Now, while you were gone, I thought about a corollary to that, and that's specifically why I was motivated to ask you. Because your sensibilities as a musician necessarily require an appreciation of non-scientific issues, like beauty, like soul, like connections, like emotions. So, I bring that in because there's that fundamental disconnect between a spiritual assertion that only a god can have created something out of nothing, to which the physicists, or many, would say, "No, that's actually not true. You don't need that first order to create something out of nothing." So, I wanted to add that additional layer of complexity to that question for you.
Yeah. It reminds me of a question that – let me just give a little side note on that. One of my mentors for many years was a guy named Ornette Coleman, who was the pioneer of free jazz, and I once brought this friend of mine to meet Ornette a few years ago. And this guy was a very heavy theoretical oriented musician and scientist, composer. And he kept asking Ornette about all this – "What's harmolodic? Tell me about your system, theoretically." And then, Ornette goes, "I'll tell you about that, but you first need to tell me where an idea comes from." So, yes, I do think I've evolved to have – and I've finished my second book, but the second book isn't exactly about your question, actually. It's coming out soon, Fear of a Black Universe.
Yes, yes. Oh, I love it.
An outsider's guide to the future of physics.
Did Chuck D write the introduction?
Yes, he did. He actually did. He gave me a blurb, and he goes, "This book is fundamentally about –" It says something like, "Stephon Alexander wrestles with the rabbit hole. This book is the best book I've read about, what is soul?" So, it goes back to your whole thing. Let me see if I can cast this in a – I think, fundamentally, when I was a young person, the reason I got into physics as opposed to – I was also looking into biology when I was younger – because I fundamentally wanted to ask the question, why are we here? Not only, what is the purpose of being here? But how the heck did we come on the scene? Life, the planet, the universe. And when I found that physics was a vehicle, or a way to analyze that without getting wrapped up in heated debates of speculative matters, that's kind of why I went into physics. But remember, the urge that led to that was these questions. Those questions got, of course, sidetracked by writing and publishing papers and getting promotions and all these things. But I think it's a mistake for me personally to think in the name of physics, and in the name of evading these questions about, is there a soul? What is the origin? Where does consciousness come from? What happens after we die? These are the questions I think that really fundamentally drive that. And right in my book, I did a lot of research – this book is not only about physics and giving a summary about what modern physics is. That's been done already, and better than me. But it's a book about how physicists came up with the breakthroughs.
So, one of the things that I found interesting is that the founders of quantum mechanics, which if we take a referendum on physics, is the place where we see all the crazy, spooky stuff that's really pointing at these questions. If you look at the architects of quantum mechanics – von Neumann; Max Planck; Schrödinger; Bohr; Heisenberg; even Pauli – those are a few. There are many more. All of them were seriously reading and influence conceptually, in terms of the conceptual kernels of quantum mechanics. And Wigner, I forgot to mention Wigner. All these people, can we not deny that these are demigods? All of them, when I did my research, the source of their ideas, an inspiration as well as the ideas themselves, like complementarity, the Born rule, all these things, they read deeply and practiced, some of them, deeply, eastern philosophy. Vedic philosophy, the Upanishads, Taoism, Buddhism, right? So, you don't have to go to the Tao of Physics to argue that. You can just go to the architects themselves, to see that they were asking these questions. Schopenhauer. Schrödinger read Schopenhauer, the German philosopher. Arnold Schopenhauer. I mean Schopenhauer was all about – I mean, he was really influenced by eastern philosophy. So, again, I think that's exciting because I think this generation of physicists should feel empowered, actually, to – and by the way, it doesn't get you away from learning the tools and learning the trade.
But as my postdoc advisor the great Michael Peskin once told me, I remember he gave me this crazy calculation to do. I was like, "Why are you making me do this crap – this stuff, man? I just want to do –" He goes, "You need to learn these things so that you can pursue your own ideas. You see? So, I think for me, it's more going back to like – the beautiful thing about physics, our tradition, is that we can provide these amazing tools, conceptually as well, but technical tools, experimental tools. But once you have these tools and you master these tools as a community, I think we can tackle these questions. One last thing there with that. We're already in that rabbit hole. For example, you talk about experimentally. Can experiment actually point to these weird things? Well, listen, look at beta decay. Beta decay is just a tunneling event where you have a particle transition from one element – inverse beta decay for example. An up quark and a down quark get transmuted to each other, release in a beta particle through a week interaction. That's quantum tunneling. Quantum tunneling is as weird as it gets. Something going through a classically – a quantum entropy basically transcending what we as classical beings find unimaginable. There is a potentially unallowable barrier, like a wall, and it's basically saying you can be a ghost and go right through it. That's weird. It's predicted by quantum theory. It's a completely non-classical result, and we have already, time and time again, and also just by the way the sun burns, this type of weird physics is happening. So, we have many examples of weird things happening that's already pointing that nature does things that transcends the way our five senses can perceive.
To go back to that original question – it was obviously very easy to go off on fun tangents – is there an experiment that can demonstrate physically that something can be created from nothing? Or is the assertion that physics has an answer for why the universe does not need a god only a theoretical assertion?
Well, I have to clarify what I mean by the word god, or the other linguistic equivalents of that word. So, when I use the word god, maybe I'm talking about Spinoza's god, or nature. And so, if I say God is basically the function and the happenings of nature at all levels. I would say the following. It now comes down to a question which is, can human beings, can the human mind come to understand all of nature? If I'm making this equivalent. So, therefore, I say, what God is this asymptote, or the difference between what is knowable and what is not knowable. So, that gap I call God. What was once the sun god, and now we understand something about stellar physics, it now falls into the category of the physical.
So, if I want to say there may be some things fundamentally the human mind cannot know or comprehend, and I want to call it God – the Buddhists call it the beginner's mind, or the don't know. Or maybe Socrates says there are something things he doesn't know, but he understands that not knowing. So, I would say that where I'm at right now is that we have evidence that for some magical reason we, tiny little specks on planet Earth, can come to know things that we maybe thought we couldn't know. Four dimensions, with Einstein's conception of curved spacetime. We don't perceive curved spacetime directly, but somehow, we're able to come to an understanding of that, and use it in mathematics as the sixth sense of – or good physical intuition. I don't know if it's physical intuition about curved spacetime, but I think my premise here is that I guess I must believe, fundamentally, that we could get to know as what Stephen Hawking says, the mind of God. Otherwise, I wouldn't be in this business. So, our ability to imagine beyond what is unimaginable, I do believe in that. But I also believe we have to be courageous moving forward, and we cannot hide behind cultural presuppositions about our projections of God, or in relation to religion and this kind of stuff. I think we should remain inspired by the architects of quantum mechanics, that they were engaging in conversations, and understand other types of philosophy, to other ways that human beings thought about the universe to inform their craft in physics. Or, I'd like to say it another way, what Abdus Salam said when he got the Nobel Prize, "Scientific inquiry is a common heritage of humanity."
Stephon, a very different topic, but no less heady. First, I'll just state editorially, this is a hell of a time to be the president of the National Society of Black Physicists.
You can say that again.
My goodness. Let me ask. I've had the privilege of interviewing people like Ron Nickens, who were there at the beginning. You've been involved in NSBP as a student. You have a strong institutional memory yourself. But would you say, to the extent that you understand the origins of the National Society of Black Physicists, are the things that you're dealing with today more or less the same as they were in the 1970s, or are they more different?
Oh, that's a – things are different, but there are some things, I think, that remain static, that remain in my experience, and in the experience of talking to Black physicists across the world. Some ways in which things are different, for example, is since its inception, which was 1978 – get that straight on the record. As the president, you think I should know that. But since its inception, for example, our membership have grown. And despite the fact that we had some dips in our evolution, dips in terms of certain issues, as any growing organization will experience, I would say that our membership has tripled since my presidency. We have on the order of 2,000 members. We are becoming more global, meaning that there are Black physicists outside the United States. Brazil, South America, Europe, obviously Africa. So, we are definitely extending our outreach as a global community as well.
We also have non-Black physicists as members. So, there are members of our physics community who are not Black that benefit tremendously from membership. So, all are welcome. That's one thing that's changed, amongst many other things. But some things that haven't changed, I think, is that I like to think about – I hate to sound like this – but I like to think about the Black scientists, not just the Black physicists, in America, as an endangered species. What I mean by that is that the survivability of that population, meaning that whether we – at every stage – first of all, physics is a very demanding field. It's difficult for everyone. Everyone who's trying to navigate a career in physic, regardless of who you are – even if Alf the alien comes down to Earth and wants to be a physicist, they're going to experience stuff. Difficulties, challenges. But I think with Black physicists, we still have a stigma to deal with. A stigma that some people do believe that Black people are inherently not as capable. Not all people believe this, but I think it's enough of an issue where some people – whether they carry that with them or – and then, in light of the post-affirmative action thing, that maybe there is still this thing where people feel that Black folk can't do physics.
The inception of NSBP since the beginning was basically in response to some prominent physicists went public saying that Black people can do physics. Anyway, not to put the focus on that. It's just simply to say that one of the things that we are very deliberate about at NSBP is to say, regardless of whether or not those things are out there, and people are functioning both formally and informally, anywhere from like – I quote a large-scale research called the Diversity Innovation Paradox, done by three departments at Stanford, where they basically studied on the order of over one million PhD dissertations from women and minorities, and they've basically found the simple fact that that population innovates more in the sciences than the majority population. But it's not as celebrated, or – there's a word for that – celebrated or promoted, let's say. The point that I'm trying to raise is, what is NSBP's strategy in dealing with some of the barriers that have persisted? Barriers of access, barriers of funding, of the informal networks that physicists may have with each other. Like, if I'm in your club, you're in my club. We don't necessarily find ourselves in those clubs simply because you might be an independent thinking person. That already kicks you out of the club. For whatever reason, you're not in the club.
I think NSBP's way of dealing with that at the moment is to still, on top of that, be productive. To figure out ways that we can continue to be productive, to do the physics. So, we have implemented our own programming. For example, we have the Simons-NSBP Scholars Program, where we have undergraduates that during the summertime do research. We're working on something called the NSBP Institute, which will pair up NSBP Black faculty with undergraduates and postdocs, or PhD students, across the nation, so that they can be mentored, and they can do research. So, we're doing things where we're saying, okay, despite that, how do we continue to not ignore the noise, but in spite of the noise, still manage to just do the work and be productive? And that's definitely – I mean, I really get that inspiration from people who I consider to be my predecessors in physics. Albert Einstein was still dealing with Nazi Germany when he was doing his physics. So, I think that's my take, that's NSBP's take on things. This stuff is there. We can raise our voice, and I think we should not be quiet about those things. But I think simply only doing that, and not despite that, figuring out creative ways, and also working with our allies and others in the community that recognize that and see through that is a strategy that we're giving a shot.
Stephon, in your leadership role, how have you dealt with, intramurally, debates that have a generational flavor to them about how to deal with inclusivity in STEM, and more generally? You have the vanguard, people like Jim Gates, who advocate in a particular way about how to deal with these things, and the younger generation, the Particles for Justice crowd, who have their own views. And you, as leader, and generationally, you're kind of in the middle of those two generational extremes, how have you dealt with these issues?
Yeah, that's a good question. First of all, I see a lot of validity to the other perspectives, and I think we need each other. We need to support each other. This idea of a divide and conquer, I support and did support the Particle for – I continue to support that movement. Obviously, support what Jim is doing, and also the APS and the AIP is also doing.
The question is, how does NSBP contribute in terms of as an organization, given our history. Given the fact that we are an organization that will continue on into the future. The seas have changed from 1978. NSBP has been a fixture of doing those changing tides. So, what I've done, and I think the board of NSBP have done, is that we've been actually – I know I can use the word grassroots. But my role as a person, I just interacted a lot with student. I spend a lot of my time just talking with students who are in a dorm room somewhere looking out the window trying to figure out the next move, how to get a job, writing letters of recommendation, talking to students, talking to groups of students, expanding our student council, student leadership, finding research opportunities and job opportunities.
So, it's been very grassroots in terms of dealing with students so that they can be productive. Lobbying for people to get postdocs, lobbying for people to get faculty jobs, working with AIP to do the Joe Johnson memorial award for the experimental physicists in NSBP, working with the Simons Foundation to increase funding and programming. So, it's more about the work, the action items on a day-to-day basis, dealing with Black physicists across the board, in terms of, how do we enhance their capacity and opportunity zones for them to succeed, despite the noise? That's much bigger than me, but I do think that if you want to deal with media and social media, I think those fights and those battles need to be taken.
But at the end of the day, I think that student who was trying to do a calculation – also, as president, I still manage to mentor, in terms of doing the research, actually, with NSBP students. I've managed to mentor three NSBP students in theoretical physics research, as well has high school students. We did a mentoring program with the Harlem Gallery of Science and NSBP undergraduates during the pandemic. So, the point is, that work needs to be done, and somebody has to do it. That's kind of the place that I think NSBP has function in the time being.
As a historian, I was immediately concerned that all of the opportunity to make #shutdownSTEM, which we're just about a year out from now, that there would be a lot of sloganeering, and a lot of people who do a lot of things in the short-term, but then eventually the impetus and the possibility of what could happen would fade from memory. To what extent has that been true, and to what extent, in your leadership role at NSBP, has this become the start of a conversation that's ongoing, and that will confer benefits in the long-term?
I think nothing is in a vacuum. I think just the fact that the pandemic and then the George Floyd event, as well as other things going on in the world – politics, what was going in our country – all of these things kind of led to this collision that brought to light many of these issues that have always been there, since the inception of the United States. I don't think that's going to go away. Still, I'm President of NSBP. I still have to write grant proposals. And if people go up for a tenure case, those deliberations and how that happens, that's still going to go on. So, I don't see – again, my way of – I sort of feel like the only reason why I'm in the position that I am in, I think a lot of it is that –
I mean, I ran for President of NSBP because I felt like there were some things as a physicist, I was able to navigate and learn to maybe pass on to the younger generation. These are some tools that enable me to be a better physicist, a better scientist. Because fundamentally, speaking like NSBP, who are we? We are a scientific organization, an organization that is about figuring out how to promote the success of scientists of color, or Black scientists, given the realities that we continue to face. How do you do that? We're not a political organization. We're a scientific organization. So, for me, it goes back to that fundamental principle. How do I enable that young mind that has the potential to make that breakthrough regardless of if they're Black or white or whatever, how do I create the conditions, or even get things out of the way so that they can thrive and maybe make the next breakthrough, be the next Feynman, and win a Nobel Prize? The first Black physicist to win a Nobel Prize. I'm interested in that. I'm guided by that principle.
Everything else, to me, is noise. It's been around for 400 years. Tell me something new.
To add even more complexity to this, and this will get us to developing your own origins, obviously your own lived experience is not that of somebody a generation older who may have grown up in segregated small-town Virginia. As someone who spent their early childhood in Trinidad, and whose family heritage does not have that African-American experience, to what extent has that quasi-outsider status for you been advantageous in this role, and in what ways is it difficult because your experiences are unique in the field?
Yeah. I mean, I think that's a good thing. First of all, I consider myself – I identify – I think as human beings we have complex sets of identities. So, human first, but obviously I'm Trinidadian-American, but I strong identity also with being African-American because I spent most of my life growing up in this country. I think some of the issues that my predecessors faced in Trinidad – colonialism, slavery – were commonplace and similar to the African-American experience. But yes, there are differences. I kind of grew up in a very Pan-Africanist household. Kwame Ture or Stokely Carmichael was Trinidadian. So, my dad was part of the Black Power Movement in Trinidad. There was a Black Power Movement in Trinidad.
So, I kind of came to America already with that sort of sensibility, that this is home. These are my people. So, just to let you know that I've certainly felt very African-American despite the geographic thing. We have a saying in Trinidad, we talk to another Black person, like, "Where are you from? I was dropped off in a different boat stop." But the second part of that question was –?
The extent to which you have that duality in your identity. Where is that advantageous in your current leadership position for NSBP, and where might that be difficult because maybe most of the demographic that you're dealing with does not have that background?
Yeah, yeah, yeah. I think it has given me an opportunity to see that basically the African Diaspora, including African-American is not a monolithic group of people. There's a huge diversity in thought and experience spread across the United States. I think it's given me sort of like an instinct to look at, what are the ways that bring us together? What is the glue that brings us together and that we can agree on and then productively move forward, rather than looking at the differences that tear us apart? Is it because one group suffered more than another group? No. Is it because one group is better than the other group, or because one group is a house Negro, and one is a field Negro? No. So, what are those things that bring us together?
I think one of the things that's really powerful that do bring us together is that in the face of oppression, that all groups within a diaspora, we manage to come together and together try and fight and transcend that as a group. We didn't bicker amongst each other – I'm sure there was some of that, but when we look back at history, we find that we are people of great perseverance. Yes, there were debates, and those debates you can look at Martin Luther King and Malcolm X, but then there were things that brought them together. Like, economics, for example. So, again, for me, it's about looking at those things. Another place where I feel is powerful is culture. Celebrating the things that we have done that should be celebrated, that speaks to our spirit of creativity, our ingenuity. To me, that's culture, and a promise that if you put the bet on Black Americans, that we can actually deliver and partake in this program called physics and make breakthroughs as well. I look at, for example, jazz music, hip hop music, as a perfect example. When you look at those creations and innovations not just as music, but purely in terms of cognitive creation, you find in my book The Jazz of Physics, there's a lot of resemblance between the creativity and innovation that happened in quantum physics that happened with jazz music, like what John Coltrane was trying to do, what Thelonious Monk and Miles Davis and Charlie Parker were doing, and Duke Ellington. So, you find this ability to have this elegance and sophistication, and to create order out of chaos in spite of that. I want to celebrate that within our diaspora, and say, okay, in spite of all this noise, how can we continue doing that? Because we did that already, and we are the children of those people.
On that topic, what opportunities have you seen to bring physics in Africa more into the global community, either in the world of observation, with some exciting telescope projects that are happening, either in terms of physics education, or even with the pandemic, just in the way that we can communicate over Zoom across the globe, and people feel connected because this is a normal way of interacting with colleagues?
Yes, yes, yes. One of the things I've set up, because I wasn't able to do everything, but for the next administration under the leadership of [00:43:55], who obviously is somebody you should interview – you probably did already – is in the earlier days, NSBP was very instrumental in the SALT telescope. We had a lot of – I remember when I was a student in NSBP's administration, I think it was under Charles McGruder, when he was president, really engage Africa. NSBP had great partnerships across the continent. We are going to, in the next coming years – there's going to be a resurgence of that, of our engagement with Africa. One of the things that I've set up in my administration is reconnecting with African physicists in the United States. A lot of Africans come to the United States to be educated. We have Dr. Anderson, who is the chair for Xavier University. He's from the continent. [00:45:02], who returned back to run science and technology in Rwanda. So, many of these relationships I've sort of reengaged, so that the next administration can fully go and be partnerships with Africa.
Well, Stephon, let's go all the way back to the beginning now for you. Let's go back to Trinidad, and let's start first with your parents. Tell me a little bit about them.
Yeah, my parents. My mother, Felicia, and my father, Keith. We come from a rural part of Trinidad. My mom comes from people who grew coffee, cocoa, banana, coconut, all that good stuff for generations. So, that's sort of like – I mean, as you know, Trinidad is roughly 50% of East Indian and African ancestry. Both populations built the country together, so a lot of us are of that type of mixed heritage, including myself. That makes for a very rich experience, growing up in Trinidad, culturally and cuisine-wise. So, that's my parents. My mom did the hard work of raising us at home, and my dad was a constable. So, then we moved in 1979 to the Bronx, New York, and my mom became a nurse. Actually, her involvement as a nurse really propelled a lot of my questions about life, because she would come home and tell these stories about putting somebody to rest for good, or what was going on with young people – people getting shot, and things like that, coming to the ER. So, that really aroused certain questions about my mortality, as a young person, that led basically to physics in a strange way. My dad was a cab driver, but a very entrepreneurial cab driver. On the side, he studied and did one of these vocational courses that you see on TV at some technical institute, and studied to become a computer tech. He had these books that would hang around about electrons and electron circuitry and things like that. So, that, again, led me to quantum mechanics.
Stephon, what are some of the dominant memories from Trinidad that you have from your early childhood?
Yeah, dominant memories, basically is the primordial force and power of the nature, of the ocean. We're from the southern coast of Trinidad, which is where, on the last voyage, Columbus mistook Trinidad for continent of South America, and landed in Trinidad. When he was in Trinidad, he was able to see South America. So, I'm from that part of Trinidad. As a kid, I have memories of even like 3 years old, of my mom taking me to the ocean, but this is like jungle. This is not like a tourist area. This is raw jungle, where you walk into this beach, and I remember experiencing just the life and the raw energy of nature and the ocean, and its impact on me. I think that memory still sticks in my mind, that sometimes when I'm doing physics, I'm imagining intuitively the universe or the formation of large-scale structure, I'm thinking about the power of nature, the vivaciousness of nature. And is there a Demi-urge? Is there a will that's driving that, as Schopenhauer calls? So, that's kind of interesting, how those experiences are connected still, and informs me subconsciously of how I do my physics.
What were the family considerations in making a life in the United States, and why the Bronx?
Because there were other family members there, and we tend to – network theory. There were nodes already. Be it in Miami, be it in New York City. There were places where our predecessors – my grandmother had already lived in the Bronx for two decades, so it was a good place to start. That's one of the reasons why. There are a lot of Caribbean influences in the Bronx. A lot of the people that were there at the formation of hip hop culture were mostly from Caribbean ancestry. So, that was ready to plug and play.
Was it a shock for you, given how dominant the pastoral memory of Trinidad was, coming to the Bronx, the concrete jungle?
Yeah, in fact, I had some experiences that still blows me away. I was unaware that – there were cognitive science studies about this many years later. When I was at Stanford, I had friends that were studying this in cognitive science. But let me tell you the phenomenon. One time, it was my first year in New York, and the playground at Public School P.S. 16, which is where I attended, was all concrete. The ground was concrete, so if you fell, good luck, right? Scrape your knee on the concrete floor. And then we had a big wall that separated the upper level of the playground and the lower level of the playground. There was this big, gigantic wall, and I was playing tag with some of the kids, and I literally ran into the wall because I didn't see it. I guess what I mean by that is that I grew up in an environment in Trinidad where there were no concrete walls, no concrete buildings, just all trees and ocean. I attribute it to the fact that somehow my visual apparatus simply did not process that wall. So, I didn't see it. It happened many times, where I would just walk into buildings because I didn't see it. It took me a while to actually start, in certain contexts, see concrete buildings. So, those are some ways – I still believe that there are some things functionally where maybe I don't see things the way others, as you said, who grew up, who were born in this country. And I think that's the beautiful thing about America, that we are a country of immigrants. When we bring in all these different perspectives, that's the building blocks of this country. That's why we thrive from always bringing in others to this country to build it.
In what way did your parents subconsciously look to preserve their culture and identity, and in what ways did they emphasize the importance of assimilation?
Well, again, the good thing about the Bronx was that there was no assimilation. The Bronx was really a dialectic collision of all these different cultures, and we have to learn how to coexist. I grew up in a neighborhood of Italians, Irish people, Jamaicans, people from India, Caribbean people, Puerto Ricans, Dominicans, Polish people. And it's like, okay, day in and day out, how do we coexist? But I think one of the places where I think some of the Caribbean thing – which is already a creolized culture anyway – was obviously our music, our food, and how our food and how our music gets integrated with the greater – so, the Jamaican beef patty finds a home in the Italian oven with mozzarella cheese and tomato sauce. That's what that looks like, right?
Was your first exposure to jazz in New York, or you were aware of this in Trinidad?
No, yeah, definitely in New York City. My first exposure to jazz was really funny. I had one of those little cheap radio station things, and I remember it could only go between one station and another. There's noise. So, one time I was doing that late at night in my room, and I came across what I thought was noise, but actually, I'm looking – wait, is this noise, or is this a radio station? And I was so captured by what was going on, and then it was like, "This is the music of Ornette Coleman." And that was my first introduction to jazz music. My ears were just like, what's going on here? And therefore, this is where I learned about improvisational music. I think this is kind of interesting. I think, fundamentally, let's go back to what I was saying about – let's talk about NSBP about places of opportunity zones for physicists of color. I think at the heart of it for me is improvisation. And I think great physics is done when people are empowered, enabled, and supported in being themselves. As human beings, part of what we do is that we improvise. We may not call it that, but we're improvising. We improvise best when we are our true selves. Whoever you are, in your bones, you improvise best if you're not trying to follow all the time somebody else or impress all the time. We have to navigate that, of course. We're social beings as well.
And I think that one of the things that the African American tradition I think really has perfected is the spirit and the practice and performance, but also the innovation of improvisation as a science. As a scientific act, as a theoretical thing as well. Not just only as an artistic form. Definitely, where African Americans had space, or had a little bit of elbow room to express that was in entertainment and those fields. In sports, entertainment – but I think now, with science and technology, I strongly believe we can import this art, this perfection – or this that we've perfected, this craft, into science. Improvisation. That's kind of what I wanted to make sure I got into this conversation. We talk about Black Lives – all this stuff – that's fine and dandy, but hey, can we get a chance to improvise now? Can we show you all some stuff? That's what I feel strongly. And I feel strongly about that because I think the hardest that I've had to do is not learn differential geometry but learn how to play John Coltrane. Learn how to improvise in real time over John's steps.
So, this is to say sequentially that you brought your sensibilities from music into science, and not the other way around.
For the most part, yeah. I think that's the case because science is still my day job. It's my profession, so I have to be productive. I have to perform. I think if I were a professional – if I was playing music for a living, it would be the other way around.
When did science really first start to click for you?
I think my high school science teacher, who was Daniel Kaplan. You know, it's the kind of thing – when adults, when we're in the act of conditioning young people, this was a piece of conditioning that I think Mr. Kaplan, who was the first adult, the first person I really looked up to and said, "This guy is really brilliant. I want to be like him. He's so smart." And he was. He was definitely one of those people. He just really wanted to teach and wanted to teach in the Bronx. He was also a master composer as well. Mr. Kaplan really instilled in my mind, and it still lives with me today, that what drives a physicist is our intuition. Period. Everything is tools that we use. Mathematics, you need it. You should learn as much of it as you can. How to build circuitry, how to design that, all that stuff, all the skillsets. But those are skills. But Mr. Kaplan was about, look man, you got intuition? How do you sharpen that intuition? So, despite all the fancy education I got, whatever, I was always able to keep my eye on that ball. Okay, let's go back to the intuition. Let's go back to that picture in my mind. Let's go back to the thought experiments. So, it was Mr. Daniel Kaplan who really kind of said it was all about the intuition.
Why, of all places, Haverford? How did you get there?
Good. Well, aside from the fact that it's fairly close to New York City, but far enough away from my parents –
Right. Because, I mean, Oberlin and Wellesley, but I definitely was looking for a smaller liberal arts kind of college. I only applied to those kind of places. You know, I mean, I got into a handful of Ivies and big schools, but my high school had 6,000 students in the Bronx, so I definitely wanted to run away from that big school experience. And I wanted to get out of New York City. So, aside from those things, Haverford – when I went to Haverford, Jerry Gollub, who was this great physicist, it blew me away that you had this small liberal arts college with some of the top physicists in the world. Bruce Partridge and Jerry Gollub to name a few, who were all people with
Nobel nominated abilities – whatever. And they were there at a small place with like 12 physics majors. [01:00:32] one, Jerry Gollub shows up on the student tour and takes us into the lab to show us the groundbreaking experiment he did to establish chaos theory through fluid dynamics. That blew me away. But I think also – they took us on a tour of the Underground Railroad. Haverford is the first Quaker institution in America, and I was really moved by what Haverford stood for historically as an organization. Its integrity as a Quaker organization that stood up against slavery when all the other smart institutions did not. So, how smart are you then? So, Haverford, I really felt like I wanted to be part of this legacy.
So, that's to say, with your appreciation for how good the physics department was, despite it being such a small school, you came in fully intending to pursue physics.
Oh, yeah, yeah. I always knew, ever since that interaction with Mr. Kaplan, this is what I want to be.
What kind of adjustments were there coming from such a multicultural place like the Bronx to a much more white environments like Haverford?
You know, I had a great time at Haverford. Looking back on it, we had a lot of fun. I think maybe the tenor of things have changed a lot in current college climates, but back then, while we were – you know, I'm taking about the white students and the Black students, and the northerners and the southerners, and what have you – the inner-city kids and the rural Black kids – while we were engaged in heated debates, a lot of us were friends with each other. So, Haverford was a good four-year experiment where we were kind of engaged in these debates, both in the classroom and outside of the classroom, in friendships, in relationships, where these things are happening. I mean, I was made an honorary member – I used to give examples of such a beautiful thing that then I was – I didn't really – even though I was in the Bronx, and I knew a little bit about Jewish history, it was only when I was at Haverford that I learned, through my college roommate Noah Pines, we would have these late-night conversations about his family being Holocaust survivors, and what that meant for him. I once went to a [01:02:59] thing, and he was pissed off at me. You know, there were all these things going on, and just the fact that despite all these debates, despite I was wearing an African medallion, I was made an honorary member of Hillel, so I could go and have their meals.
And it's like, these things – I hope that this generation are not losing out on those opportunities for us to still forge these friendships and relationships while we continue these much-needed debates. So, Haverford kind of – you know, I think it was successful back then at having that. Of course, I could always look at it through a negative lens, and say, "Oh, well, it was all screwed, and it's a racist institution." No. I really felt that there were some people in positions of leadership, some professors, that really took us under their wings and mentored us. Think of Bill Hohenstein, Mark Gould, Ashok Gangadean, Lyle Rudolphs, Suzanne Amador Kane – I mean, there were all these amazing people there that I'm still in touch with. Bruce Partridge. Can't forget Bruce Partridge.
As an undergraduate, did you appreciate the binary in physics between theory and experimentation?
Yeah, well, Jerry Gollub, man. I mean, one of things that, regardless of what your orientation was at Haverford, when Jerry was a chairperson, the curriculum was such that we – as a sophomore and a junior, we were doing some of the original experiments. We did the Millikan oil drop experiment. We did the Brownian motion, where we measured the order correlation function between, oh god, between like very tiny particles submersed in a liquid. We measured the electron, the orbit, to confirm the bar radius. I mean, we did some of the original experiments, regardless of what your orientation was as a physics major. So, by the time I went to grad school, I found that a lot of my theory friends never did an experiment. So, I thank the Haverford physics department for doing that. I think that really – I still think like, not an experimentalist, but I definitely have these – a lot of times when I'm working on a problem, I go back to that experiment of the electron going around an orbit, and its proportionality to a magnetic field.
What kind of advice did you get about graduate school?
Well, you know, again, it was only until the end of my junior year I actually had the courage to say I wanted to go to grad school. I didn't think I had really what it took to be that, a PhD in physics. But I still fell in love with research. I did a summer REU program with Mark Kryder, the great Mark Kryder, and it was like – it was experimental, actually. It was like, this is what research looks like? I don't have to check in and put a timestamp? I just walk into a lab, and there I go, and there's nobody huffing over me? I get paid to do this? But in terms of grad school, I was just basically trying to get into a grad school. I was getting rejected left and right, and then Brown bit back and gave me a chance. Even as an undergraduate, I didn't really reach my peak in terms of performance as an undergraduate. So, I was very much a late bloomer, a very late bloomer.
Do you think maybe part of the issue was that you weren't articulating what it was that you wanted to accomplish in graduate school, what your research might be?
Yes, absolutely. I was clueless. I mean, I look back at my graduate essay, now that I sit on graduate committees. I should have never gotten into graduate school based on the standards that we hold now, which is that you need to have a clear sense of what you want to do and maybe who you might want to work with. I was just like; I'm just so interested and in love with physics that I could do anything. Oh, really? You're not getting in anywhere.
Who did you connect with at Brown initially?
Yeah, it was amazing. I think the two professors that I really connected with originally was Michael Kosterlitz, who now, as you know, got the Nobel recently, but back then he was just Mike. And Leon Cooper. Leon Cooper, we would take the same elevator ride, and I didn't know who he was. He was this guy who would come in with really fancy shades, very well-groomed hair, nice suits, and it's like the Matrix. It's like Morpheus coming in, and he'd go, "So, what are you thinking about these days?" And I'm like, who is this weirdo in an elevator? And then I'd be like, "Well, I'm thinking about this crazy thing." And he goes, "Well, have you considered this?" And this would be happening for a couple years. Then I realized, oh, it's Leon Cooper. So, both Michael Kosterlitz and Leon Cooper, back then when I was a graduate student – this was more than 20 years ago – they were like people – I could just walk into their office and download all the crazy ideas that I had, including quantum consciousness and the origins of life. And they'd be like, "Sit down. Engage me."
Who ultimately would be your graduate advisor?
That became Robert Brandenberger. I took general relativity with him, and that was a class where I said, "Oh, shoot. Wow, okay. This is where I want to live."
What was Robert working on right at the time you connected with him? Was he already onto string gas cosmology?
Yes, Robert had already developed string gas cosmology in '89. I was with Robert from '94 onwards to 2000. So, he was working on string gas cosmology. He was working on cosmic strings, topological defects as well. One idea that Robert worked on that I think really stuck with me and continued on in my research was by bringing in IBS and condensed matter physics into cosmology. The Cooper pair mechanism in superconductivity – I've still, in work with David Spergel – we worked on a new model of dark matter that can import some of those intuitions that Robert was one of the first people to import condensed matter. So, some of these things stuck with me. A lot of my work with Robert also became numerical. I was doing a lot of numerical computational physics stuff, which I run away from these days and have a grad student do that. Yeah, so that's what Robert was working on. Robert was definitely of the impression that the early universe is the best high energy lab, so if we want to ask questions about fundamental and particle physics, we have go to the high energy early universe and ask those questions, and also enhance those models to accommodate those questions and inform the next generations of observations, which I played a role in because my friend Brian Keating, who is somebody you should interview – he was my best friend in grad school. He was in the basement working on the first polarimeters to detect polarization in the CMB. So, that was an opportunity for me at that time to also start thinking about that maybe the theories in early universe would say something new about polarization of gravitational waves, actually.
Would you say that it was Robert's influence that you were part of that large community of people that had a particle physics background that applied it to things like astrophysics and cosmology?
Yeah, absolutely. Robert, when he was a PhD student, there were a lot of – he was under the Sidney Coleman camp, training as a particle physicist and a field theorist. So, Robert imported a lot of that stuff into quantum field theory and curved spaces and particle physic and inter cosmology. He's part of that generation. So, yeah, that definitely still impacts me. I'm trying to liberate myself from the particles.
Intellectually, how did you go about developing your thesis research?
Yeah, my thesis research was centered around, actually, solitons and topological defects, and its role both in string cosmology, string theory – because you know, at an effective field theory level, strings and D-branes are basically solitons. Nonlinear, basically, stable field configurations, such as a vortex. That's an example of a soliton. A domain wall. These things. So, at one level, at a level of field theory, I was simulating the interactions of things like magnetic monopoles, one type of soliton or topological defect, with domain walls to address an early universe cosmology problem called a monopole problem. And at the other level, I was looking at string theory solitons, something called D-branes, pioneered by Joseph Polchinski, and string theory to understand the emergence in the context of string gas cosmology. Basically, we were building on the string gas cosmology framework to include these other states in string theory, which were solitonic, to ask questions of, does the emergence of three large spatial dimensions persist? My thesis established that the answer is yes.
Were you aware of what Abhay Ashtekar was doing? Was loop quantum gravity on your radar as a graduate student?
No. I was aware of loop quantum gravity, but I was aware of it as basically a failed theory of quantum gravity, because that was the thing that was, in my generation, like the only game in town, and if you're really a smart physicist, the only thing to do is string theory. So, I was definitely sheltered, or shielded, or filtered from loop quantum gravity. That only happened when I was a postdoc, and I met Lee Smolin.
Right, right. And what about what would become the second or third, depending on how you count these things, the Superstring Revolution, and Ed Witten's M-theory? Was that on your radar?
Oh, big time. So, when I went to Imperial as my first postdoc, it was all about M-theory. In fact, a week after joining Imperial, I had to go to a three-month M-theory workshop in Paris that brought together all these theorists from Europe to one central institute, where we basically attended lectures every day, workshops, calculations, working groups, and all the founders of M-theory that were involved in that were there. A big part of my research was to figure out how to integrate M-theory, which is a unification of string theories, into the early universe framework. That paper was my very first paper that integrated the modern formulation of string theory with cosmic inflation.
And did you consider cosmic inflation very much a toy model at that point, or were there things that could verify it observationally?
Yeah, for me, I was convinced that inflation was the paradigm. I still believe that it is the paradigm, even though I've worked on alternatives, that it is a big part of the paradigm. Whatever replaces inflation will have to still have some elements of inflation in it. So, it was enough to convince me that we have to – and also, the problems that inflation had – it was mostly focusing on, like, here are the successes of inflation, and made the correct predictions for the fluctuations in a CMB. But if you look at the theoretical problems, you could look at these problems as a guide for how string theory, or how the problems also in string theory, do they have a common overlap? So, that was more of a research strategy to try to break new ground. Look at the problems of string theory, look at the problems of inflation. Do they overlap in any way, and can I address both of those problems in the same framework?
Now, of course, inflation is not singular. There are lots of different approaches to inflation. So, just to throw out some big names – Alan Guth, Andreas Albrecht, Andrei Linde – was there a particular avenue of inflation that was most intellectually stimulating for you?
Yes, absolutely. Definitely, Alan. Alan played a big role in my career as well. I met Alan as an undergraduate. These are the small things that I think we should always pay attention to. Alan came to give a very fancy talk in the Philadelphia area, and I was a student sitting in the back of the room with all these fancy physicists. And I was compelled to ask this question. It was a dumb question; it was a naive question. And then, this Alan Guth goes, "That's a really good question." And I got stuck. I mean, I think it's important that there's a bit of truth to that. It's like, wow, look at this great physicist that just validated me in a very genuine way. So, Alan, I met Alan many years later. I'm in his sacred office at MIT, and I was wandering around the infinite corridor, or whatever they call it at MIT, and I chanced into Alan's office, and we started talking physics. And Alan had an idea of like inflation as sort of like a quantum gravitational induced tunneling process. Because inflation is driven by false vacuum energy in like a phase transition. That's one way of thinking about inflation. Not the only way. So, when I realized that string theory, you can also have configurations or states that contract false vacuum energy, I was able to marry those two ideas together to create one of the first ideas of string inspired inflation. That's a big part of what's at the heart of inflation, these D-branes. These solitonic degrees of freedom in string theory. And you can think of these D-branes as basically containing false vacuum energy and driving inflation. So, definitely, that take on inflation, meaning inflation could be driven at the core of a topological defect –
Now, Alan always remained aloof from string theory. Did you ever try to evangelize at all? Did you ever try to get him more involved in string theory?
No, because I had so much field theory to still learn from Alan.
What about people like Henry Tye or Joe Polchinski who did merge those fields?
Yeah, yeah. So, both Henry and Joe, and especially Joe, were very supportive of me. When I did my D-brane driven inflation, Joe was the one – I was a postdoc trying to find my way professionally, but Joe invited me out to give a seminar where I held court with some important players in the field of string cosmology. So, that was very useful professionally, that Joe basically gave me credit for being one of the people that pioneered this field.
What were Robert's impressions of all of this, given that string gas cosmology really positions itself as an alternative way of understanding the very early universe?
Yeah, in this sense, amazing. Robert is one of the great scientists, you know, because while he was doing that, he still continued writing papers on inflation. I think it was more like, let's populate the theory landscape, no pun intended, with ideas out there, and see which one does the best at making contact with experiment, and which one is theoretically most sound. Fine, but that should not be the only order here. Which one is making the best predictions? Which one is most consistent with observations? Which one could actually – this is the other thing. In terms of theory, it's a two-way street for me. It's like, you want to inspire experimentalists and observationalists, right? So, when I have a new theory, it's not only for my theory friends. It's a way of – it can give a new perspective or a new way of thinking about how I'm going to design an experiment, or what blind spots I might have in designing the experiment or imagining new experimental innovation. So, I think in developing new theories, it's important to think about our experimental colleagues when we're doing that. It's not just, oh, my theory is better than yours. It's about, how could this also be useful in inspiring experimentalists?
How did the opportunity at Imperial in London come up for you?
Yeah, that's a good question. A man called João Magueijo, brilliant cosmologist who came out to Brown University to give some lectures on the wave functions of the universe. He gave this crazy talk called Photographing the Wave Function of the Universe. The reason why that's funny is that even though – when he came out to Imperial, he came up with this idea called the variable speed of light idea. And I at the time was working on the string theoretical way of thinking about that. And I think, I guess, over some coffee and some napkins doing some calculations, I maybe have impressed him enough that he convinced the group at Imperial that they should hire me as a joint cosmology/string theory hire. So, that was the main reason I was at Imperial. It's João Magueijo's fault.
How was it in London, particularly the music scene?
Oh, I mean, so Brian Green offered me a position at Columbia, which was amazing and was a tough choice, but I knew I wanted to go to London. You see, I also grew up listening to a lot of music that comes from a place called the Africa Center, and a group called Soul II Soul. I had this fantasy that I was going to one day be in London hanging out with Soul II Soul and Massive Attack and all of the underground music in London. I was very much a student of ethnomusicology, and just so interested in the ways that different cultures could come together to form new forms of music. And London was the epicenter of how all these different types of music from around the world in that city comes together to make new types of music. I wanted to explore that, just even as a listener, to be in London to explore that. So, going to Imperial was also a ticket to that. And once I got to London, that was definitely – one of the first things I did was I paired up with this underground drum and bass producer called Wizard, and I was working in the underground recording studios making new types of beats with him, and doing all that stuff with DJ Chemist, and later on became friends with Brian Eno. So, I had this dual life, in a sense. The Imperial days and my colleagues at Imperial really encouraged me to embrace that part of myself, and later on, of course, embrace even more – integrating those two worlds together.
Did being in London broaden your horizons about race relations at all?
Big time, yeah. One of the times I remember that was so empowering to me was a few months into my thing at Imperial, the head of the group very informally – we were having dinner and he was very – he and I were having dinner, and he goes – because Imperial was one of the inner sanctums of theoretical physics. It's considered within the European scene like one of the top places in theoretical – some people say the top place, but anyway, let Abdus Salam argue it out. He founded the group. But it was really interesting. I'm there sitting eating my dinner. I had long dreadlocks at the time. And this guy guys, he's a British guy, he goes, "I wanted to let you know we selected two postdocs out of hundreds of applicants. We selected you because you're the best. You're not here for – we don't do affirmative action in this country. So, we expect you to really do something big here." That blew me away. Because I had been living in the shadows in America where I think there was this unspoken – there's a word for this, when something is subconscious or inferred. There's a word for that. You'll find a place filler for that word, where yeah, I'm at Brown University, but somebody in that room is thinking, he doesn't belong here. Not knowing a thing about me. They're just seeing my skin color, and they know something maybe about affirmative action policy. And I immediately get written off as not being good enough because I benefited from that. I did not earn – and especially, I mean, I definitely experienced that when I came back to the States at my second postdocs where some of my cohort who work – in their experience, they work so hard and were number one at all these places to get to this place, but they really did believe that I had a hall pass. I got in easy, and therefore, I don't deserve to part of their club. That was not my experience at Imperial. They're like, we don't do that. You must be crazy smart, man, the fact that you got in here. And because of that, that really empowered me. It gave me a sort of emotional superpower, where I was like, yo, I can just go and do this calculation. I'm going to ask this big question here. How does string theory give me cosmic inflation? I'm going to do that, because when I did do it, everybody was ready to hear the lecture, and they were ready to read that paper. I remember when I first wrote that paper, it was a jumbled-up piece of mess, and I sent it to [01:27:35], who was like, no one argues, one of the top string theorists in the world. It went through his hands and sent me the draft back and goes, "Go for it. Put it out. This is great stuff." And I think that definitely informed a lot of how I was going to function as a teacher, as an educator, and as someone who's going to be mentoring people – not only Black students, but people from other groups where those sentiments may still be present.
Stephon, what I'm hearing is a lot of reasons to stay in London and make a life for yourself there. Did you consider it?
I definitely did. One conversation that still sticks in my mind – and you know, it's funny, it's still unresolved – was Brian Eno and I became very good friends. Brian Eno, right when I was deciding to leave, because I had other job opportunities in Europe, but I decided to go back to the States to then go SLAC in Stanford. He was very almost teary eyed, and goes, "I think you're making a mistake to go back there. You should remain here in London. We will appreciate you here more than the United Sates." That's what he told me.
And why SLAC? Were you specifically looking to work with Michael Peskin?
I mean, you know, SLAC – a lot of my heroes went through SLAC. Of course, yeah, I think this opportunity to – I knew there were some things – I just had this impulse that I needed to learn some more things. I needed to be under the guidance of the master. Michael Peskin is the master in my book. So, it just worked out that way. I was just like; this guy knows some stuff that I need to learn. I need to download some of this stuff. And this stuff, you're not going to get it in his textbook. You have to collide with him. I have to be in his presence.
Now, the duality there is that by the time you land at SLAC, it has fully embraced its post-particle physic identity in cosmology and astrophysics, and yet Mike Peskin is still right there in the trenches in the most important areas of particle theory. So, how did you navigate that?
I didn't. I didn't. Any type of string theory related to cosmology paper I wrote – that's the thing. Michael knows that stuff. That's what's crazy about Michael. He knows that stuff. We call him the oracle for a reason. Any time I had a string theory, I would go to Michael too, and he'd be like, you know. So, the thing with Michael that I think is important is because he knows everything, a big part of my education was to really engage seriously with Michael, technically with Michael, to then get to a point to see what he didn't know. Like, what Michael didn't know was informative in terms of how I was going to proceed in my research. But the other way was Michael, it was Helen Quinn, it was Marvin Weinstein, it was BJ Bjorken. These individuals were also very present in my training that I engaged with a lot. Especially BJ Bjorken and Helen Quinn. I mean, imagine sitting down and learning the axion from Helen Quinn.
Was being in the environment that you were close to the world of experimentation valuable to you intellectually?
Say that one more time. I think I –
Just being in SLAC, where there's all this exciting experimentation that's happening, even if you're ensconced in the theory group and that's your world, I'm just curious if being in that larger environment was intellectually valuable.
Yes, yes. I mean, being in that space, yes. Just the idea that first of all, we were a minority, this theory group on the third floor. It like, wait a minute. This is real. You couldn't help but feel like – there were days I'm walking in, and I'm like okay, this is – yeah, it informed the kind of projects that I chose to work on. I was like, wait a minute. Am I still living in ten dimensions here? What about baryogenesis? What about that stuff? Things that do real physics. The standards I have for myself as a theorist changed. It was like, I felt like I wasn't doing real theory unless I was doing something that was like what BJ Bjorken did. The quark structure, or deep inelastic scattering. It was more like, what are you doing and how can you contribute to that? Can your theory make contact to the real world? Because otherwise you're not doing high level theory.
What specifically did you learn from Mike, more than anything else?
Oh, that's a – that it's possible that it's necessary to continue on the path of mastering your chops, and at the same time, keeping an open mind for other people's ideas. So, Michael, you can be the craziest person, and you'll come to Michael with an idea, and he will actually really, really listen to this idea. He's not going to cancel you out because he's married to a particular philosophy or theoretical orientation. But he's going to throw something back at you, though, and it's going to come at you. So, I think, that to me, that dialectic is something I learned from him. Knowing a whole bunch of stuff does not excuse you from really engaging with an open mind when other people bring ideas to you. Obviously, sometimes we don't have the capacity or the bandwidth to do that, because we're so involved with the daily happenings of life, and doing your job, or writing your grant proposal, or whatever. But I definitely saw a lot of that with Michael. I saw open-mindedness and sharp intellectual chops that unprecedented amongst any physicist that I've known.
Wow, wow, wow.
He was a great mentor.
Was there anything going on observationally in cosmology or astrophysics that was really interesting to you around that time, 2004-2005?
I take for granted now, but when the bullet cluster was seen, that was definitely – I didn't pay enough attention to it back then, but yeah, the bullet cluster. Definitely the release – David Spergel came out to Stanford, who remained, again, another important person in my career. When he came onboard, came to Stanford, he released the new WMAP data, and that data really confirmed the amount of baryons we see today in galaxies were measured at the CMB 14 billion years ago. That to me was like, okay, therefore the origins of baryons in the universe, so called matter of antimatter, is a real question to ask not of the contemporary universe, but in the early universe. And that inspired me in my research with Michael Peskin on looking at inflationary gravitational waves as a way of generating the matter-antimatter asymmetry.
Stephon, I wonder, when you finished up your postdoc at SLAC, given how expansive your research agenda was – I mean, you have everything there – cosmology, particle theory, string theory – what kinds of jobs were you applying to? How were you positioning yourself to fill a niche on a faculty?
Say that one more time.
Given the breadth of your research, that there were so many different kinds of faculty positions that you could have been competitive for, how did you identify yourself in terms of marketing, or in terms of applicability for particular jobs? What was attractive or most relevant for you at that point?
That's a really good question. I mean, I think throughout my especially postdoc years, even though I really dreamt of and tried hard to position myself to get a faculty job one day, I actually didn't believe I was going to get a job. I didn't have that expectation that I was going to get a job.
But wait a minute, Alan Guth already told you that you asked a great question. That should have been the confidence that you needed right there.
No, I didn't have that. I didn't have it. I was first of all so engrossed in the research problems. That's the other thing. I was so seduced by the problems I was working on, and I was like I still have more to learn. I have this thing to learn, and this idea, and why is it that the Wilson loop is a diversion of loop quantum gravity? I mean, there were all these things I was still trying to figure out, that I didn't even – shoot, my three years are up. I need to get a job. So, there was that. So, I didn't. And I also felt like I was a theoretical mess. I mean, I had bastardized maybe string theory. I'd tried to combine ideas in loop quantum gravity and string theory. Maybe that pissed people off. I was a charlatan in a lot of ways. I was learning how to embrace that and how to be okay with that. I am okay with it, finally, after 30 years. But having said that, it's kind of ironic that the person that hired me was Abhay Ashtekar, who would remain a force in how I think about theory. I mean, what a tremendous theorist.
Did you stop thinking that loop quantum gravity was a failed theory at that point?
No, no, no, I definitely realized that when I started to get into loop quantum gravity that it was actually quite conservative. It married Ken Wilson's idea, the idea of Wilson loops as non-perturbative objects in quantum field theory, in non-Abelian quantum field theories. It married that idea, and lattice gauge theories, which we know works, with Paul Dirac's way of thinking about quantization, of how to quantize constraint systems. So, in its approach to quantizing gravity, basically – and then took Wheeler and DeWitt's idea. These are all – I mean, these individuals – Dirac, Wilson, John Wheeler, and Bryce DeWitt – these are the players at the foundations of loop quantum gravity. So, there were some things for me to learn, and given my years at Penn State, I definitely learned some of that stuff. It was an exciting time to be a junior faculty. They did a great job of mentoring me. I spoke a lot to the condensed matter people, like Jainedra Jain, Jayanth Banavar, who I still talk to today. So, the condensed matter people as well as theorists. Péter Mészáros in astrophysics department. We wrote a paper together. So, again, going back to the loop quantum gravity thing, I started learning some of the things about loop quantum gravity, and it still informs. So, I think there are versions of loop quantum gravity that's problematic, but some of the key ideas of loop quantum gravity and questions I think are here to stay. And I still do believe that there is some space where some ideas in string theory – and I do believe some of the things in string theory are going to remain. It's going to be part of our answer to quantum gravity and unification. If unification does exist, there's no doubt that string theory is going to be playing an essential role there, as well as loop quantum gravity. They both involve one-dimensional objects.
Right, right. Where is Lee Smolin in all of this?
Yeah, I think Lee has moved on. Lee thinks deeply about how quantum mechanics itself emerges. Where does quantum mechanics come from? If we don't assume quantum mechanics, that somehow there's a more fundamental framework, and I think Lee is looking at things like non-locality. If you give up space as an arena all together, but keep time as fundamental, what happens? I think that – again, string theory has that framework. Matrix mechanics, for example, is an example where you don't a priori have space, but you have time, potentially. So, the point is that Lee is open minded about all these approaches to quantum gravity, but he's thinking about non-local structures and the emergence of quantum mechanics in spacetime.
Did you take on graduate students right away?
Yes. It's funny, one of my grad students is still – Nico Yunes, great Argentinian physicist that you should also interview, he's now the head of APS. He has some leadership role on the gravitational side of APS, and he now is the inaugural director for the Center of Gravity – the whatever – at University of Illinois Urbana Champagne. So, it's like, yay, look at that! I helped to create such a person.
What about undergraduates? Was it challenging given that there's such a wide range of students and background and aptitudes at a big public university?
Oh, man, that was part of the dream for me at Penn State. Penn State was my most enjoyable job precisely because I felt like I was – when I was in the classroom, I was seeing students like myself, from middle- and working-class backgrounds.
Which is obviously not the case at a place like Brown.
IT's not as much the case at a place like Brown. And it was really a joy, a pleasure, and I felt a sense of purpose being in that classroom, seeing younger versions of myself, and then here I am. And they were so wide-eyed, and they were so brilliant and appreciative. One time, two students took me out for ice cream just simply to – yeah, so Penn State, that – and I think that's kind of what drives me with NSBP and my work for the Harlem Gallery of Science, and the Presidential Scholars Program that I was a founding faculty director of, and the E. E. Just program at Dartmouth – these engagements with that population of students that come to places like Brown and Dartmouth, I've always gotten a lot of joy. It's really a selfish act of engaging with that population of students.
What were the circumstances of taking the position at Haverford? Was that just too delicious of an opportunity to come home, so to speak?
Yeah, a lot of people thought I was destroying my – I was committing academic suicide to leave this big research position at Penn State and go to a small liberal arts college with no grad students. Literally, a colleague called me and said, "What are you thinking? You're committing suicide here." I guess, again, when you don't think that you're in the club anyway, you just move by your own – again, this is important. My sense that I wasn't in anybody's club, and my behavior, wasn't an act of defiance. I was kind of indifferent. I was like, well, I might as well just do what I want to and need to do here. This feels right. This is more fun. I'm enjoying this. I get to go back to my college and teach. That's going to be a lot of fun. It's kind of sophomoric, yeah, but how cool would that be? To be that professor for a young Stephon Alexander that's coming from the Bronx, or Philadelphia.
How did you get involved Horava-Lifshitz theory?
Oh, yeah. I got involved with that because Petr Horava was one of the key architects in M-theory, Horava-Witten theory. So, for him to then come up with his own theory of quantum gravity was like, yeah, dude. This is great. You're your own person, too. So, that really just – and actually, he was inspired by IBS from Landau, and how this idea of anisotropic scaling in condensed matter systems. So, yeah, that was very inspirational. Also, I respected him. So, I was like, I want to understand what this is about, because I respect him and had a high opinion. So, it was mostly coming because it was Petr Horava.
Did you stay in touch with Abhay during this time?
Yeah, Abhay and I have always been in touch. We've been in touch over the years.
I wonder if you've ever reflected on the importance of visibility as an African American professor. Some of the distinctions where you're more likely to interact with students who look like you at a big place like Penn State rather than a small place like Haverford.
Yeah, there is that, but from my experience, places like Haverford and Brown and Dartmouth, there were still African American students, students of color at these places – there were definitely far less, but I was also looking at the quality of the interaction, not only just the quantity.
And these were so important to you that you wrote about the for the New York Times. You wanted to get this out to a really brand audience. What kind of feedback did you get from that article?
I got great feedback. I got great feedback from all facets of the community. I think many people agreed with what I was saying. And anybody that tried to attack me got attacked. I didn't have to do anything. I just spoke my truth, and –
So, how do you know on something like this whether you're on the right track? You're a scientist, you're well attuned to the data, you look for feedback mechanisms. How do you measure the extent to which the responsibility that you think Black academics have – how do you measure if things are on the right track, that they're meeting those expectations?
I think for me, at this level, it's like – I think that if a Black academic is actively involved in the bread and butter of – given that we're swimming in a sea of resistance towards progress, and some of that resistance is simply that if you're a Black independent, you can be a threat actually. That can threaten people's psychological issues. I think that not only if I'm, I don't know, your pet or something like that – if you're a Black academic, you understand that despite all that, we have to still – we're in the business of promoting and enhancing and enabling quality, intellectual integrity, skill, elegance, brilliant, innovation in our students, white and Black, but especially, younger versions of ourselves – to me, this is not rocket science. I know what I experienced. I know that a brilliant Black student with all this potential could be crushed because they're threatening, because they're so brilliant. It's my job to protect that student. When I say protect them, to carve out space so that they can continue growing and doing great work. So, for me, that's part of the responsibility, and an integral part of the responsibility in that tradition where we're also – you know, let's go do this calculation together. No, you need to come back right here and show me the 20th line of this thing her. What were you thinking here? Let's go at it. Let's argue about this. Let's respect each other here.
Was the idea for The Jazz of Physics like a lightbulb moment, or were these things that were always in the back of your mind?
Yeah, that thing was more like – I keep saying this crap. I keep going and giving talks about this. But come on, man, are you a fake, or is this something here? It was really the actual writing of the book, just like when we write physics papers, the actual act of doing that is an opportunity to clarify confusions that you were afraid to really be honest about, rather than speaking about it in a sort of cosmetic way. The Jazz of Physics was like, let's go there. Let me try to understand myself and understand these things that I claim to be saying about jazz and physics. What is there? What are the links? And how much of it is metaphor? How much of this is analogy? How much is literal? And also, how could this empower how you do your physics and how you play your jazz? What kind of conversations could spawn from this?
Now, in terms of your motivations and what different kinds of readers would have gotten out of the book, would you be more excited to know that a jazz musician learned something about physics, or a physicist learned something about jazz?
A physicist learns something about jazz.
Because I think that the thing that – so, physicists – I'm talking about now theoretical physics. Inherently, a big part of how we do what we do, and how breakthroughs are made, and how we think is actually when people improvise. So, showing that, okay, if we do this in a more intentional way – and we can learn from jazz. They've perfected what that looks like, how to be the best improviser. Can we learn some of this? And part of how to do that is how to truly be inclusive. Being inclusive means respecting this idea of antagonistic cooperation, that the only way I can bring you in my conversation is to also critique you, but critique from a place of respect, and that you are part of who we are. And that's part of being in the club, that I'm going to critique you, and I'm going to throw some fire back at you. Rather than, oh, you know, I'm just going to pretend what you're saying is correct because it's the PC thing to do. No. Full membership comes with – in jazz, you can go and play with the greats, and you're going to be playing right there with them. It's your time to improvise, but that person will be the first-person backstage to say, "Listen, by the way, you might need to go check out these scales, and listen to some Thelonious Monk, or listen to some Art Tatum here. I hear what you're trying to do." But that's coming from a place of respect, and a place of like, you're part of this. So, let's move on with the business.
I'll share with you something really deep my dad, who loves jazz, taught me about improvisation. He explained to me, the greatness of Oscar Peterson is that he can do what Vladimir Horowitz does, but Vladimir Horowitz cannot do what Oscar Peterson does.
Say no more. And I think that is thinking about physics. We've made a lot of progress in physics, but if it ain't broke – we have this history of having done it this way. What I said in my book is, yes, and if we look at some of the elements of what made that happen was inherent. Maybe it wasn't at first – there was a lot of group improvisation going on there. Group improvisation means that I support you when you're soloing, and you support me, and there's a back and forth when this is happening, and together they're creating this music in real time. So, that's right. So, we can do that better, I believe.
Where do you see that improvisation in physics that has led to fundamental discovery? I mean, somebody like a Ray Weiss, for example, who was toiling essentially all by himself for so many years. And then, look what he created. Is that what improvisation is to you? Is that the kind of idea, the kind of achievement that comes to mind when you think about the value of improvisation in physics?
Yeah, I mean, one of the essential elements of improvisation is embracing mistakes, and actually, the extent to which you are fearful or you're afraid of being wrong or making a mistake or playing that wrong note is a function of the consequences of that mistake. Are you going to be the laughingstock? Are you going to be kicked out of the club? If these are the consequences of making a mistake, I say, that's not – the essence of improvisation is go there. Miles Davis, play that wrong note. It's a question of what do you do about it? What do you see once you – you only know once you do that wrong thing, because now you're in a situation where you can look around and see, okay, this is where I'm at. What do I do about this? How do I correct this? Sometimes that can lead to new directions that you otherwise wouldn't know about had you not been exactly in that situation. Improvisation is a way of navigating through mistakes and learning how to fall properly, like an elegant acrobat. You trip up, how do you fall once that mistake is made? Some great ideas in physics, some great experiments, not all, come from actually going in what you thought to be a wrong direction, taking stock of where you're at in real time, and then being informed by that to go into a new territory that leads to a breakthrough. Paul Dirac had to improvise when he found out that the probability was negative, and they had negative energy. What do you do? Do you throw away the theory? Is it wrong? No, he came up with the antiparticle. Maxwell, that was an improvisation with a dire – when he had to complete his equations he realized that the displacement current had to be invented. That's an improvisation because you could at that point put your hands up and say, that was a mistake. That's wrong. You know, the theory is sick. It's not unitary. It's divergent. All these criticisms. There's a moment for improvisation. What do you do when you fall? What do you do when you trip up? What do you do when you're wrong and make a mistake? That's kind of the essence of good improvisation.
Did you think you would be at Dartmouth for longer than you were? Did Brown sort of recruit you, and you weren't expecting that?
Yeah, it was unexpected, and I was having such a good time at Dartmouth. It was a great place to work. A lot of support from President Hamlin and Dean Coates and the physics department. Grateful. Eternally grateful to Marcelo Gleiser for recruiting me. That's another person that I hope you're going to engage. A great Brazilian theorist and philosopher. If you do, make sure you pin him on David Bohm.
Yeah, but that was unexpected.
What was attractive to you about coming back home, so to speak?
Well, New York was closer. The idea I could come back to the institution that basically made me who I am and be a part of that tradition – so many great people. Gerry Guralnik, Leon Cooper, Mike Kosterlitz, Tony Houghton – all these guys – Robert Brandenberger. To be part of that tradition, and to come back and contribute in that way to the place that made me a big part of the physicist that I am. Why say no to that? And I love Providence. I love that small little city.
Tell me about the intellectual influence of David Finkelstein, and why you were moved to write about him.
Oh, David Finkelstein. Lenny Susskind once told me when I asked – I said, "Lenny, what do you think about David Finkelstein?" He paused, as if he were in very deep thought, and he goes, "You know, the thing about David is that he always ends up being right at the end of the day. What can I say about David Finkelstein? He is the one physicist that really encapsulates everything that I would want to be as a human being and a physicist. I mean, he was a civil rights activist. Didn't speak much about it. He wasn't beating his chest and putting up picket signs. He was in the Deep South helping African Americans vote when he was in physical danger. There was nothing performative about David Finkelstein in terms of his engagement as a person involved in social justice. As a physicist, he founded the physics department at Yeshiva. He told me that back in the days, their offices were separated by cardboard boxes. Sort of like – he kind of also resonates with me as what it means to be an immigrant, working class, that kind of thing. There was something – being sort of like a working-class immigrant in New York City, there was that humility in David Finkelstein. So, there was that – sort of a place that we connected. But that's intellectually. I mean, Jesus Christ, his ideas are so transcendent – this idea of chronons in quantum gravity. Ted Jacobson and I say we're still in the Finkelstein jungle trying to figure our way out. He led us into this jungle, and now we're trying to figure it out. I do believe that fundamentally, though, once we find some – whatever the kernel of truth is about quantum gravity, it's going to look very close to what David Finkelstein has been telling us for decades.
Wow. Wow, wow, wow.
Yeah. I mean, even some of the ideas we're dealing with now I'm quantum computation and artificial intelligence and how it interacts with physics. David was saying that in like the '60s.
A real visionary.
What is the selection process like at NSBP for the presidency? Is this something that you were actively seeking? Was it your turn as a kind of heir apparent? Did a lot of people come together and say you've got to do this? How did all of that come together?
There was some of that. I mean, I owe a lot to Jami Valentine, who is one of their people – again, NSBP, a lot of it is about the people who are not at the forefront, doing the hard work, and Jami Valentine was one of those people. She was the first African American woman to get her PhD at Johns Hopkins, and one of the founders of the African American Women in Physics. So, Jamie was one of the people that was an officer for many years working with NSBP. She was kind of the first person to put in my ear that it was time for me to work with the board to take us to the next level. Shirley Jackson – when I went to RPI, I gave a university-wide talk, and I had the opportunity to speak with her and clarify my thinking about whether or not it's appropriate for me to run, and I also got her blessings in terms of what that would entail and making sure that my intentions are correct. Is it about beating my chest and having the title of the president, or is it about really trying to do something productive, and whether or not there's something productive to do? So, yeah, I think Jim Gates, talking to Jim, who is one of my lifetime mentors as well. That was useful. So, it was a combination of people saying, hey, we'd like for you to run, and also, me making the decision – I was I think a confluence of like, the timing was right for me to do it. NSBP is an organization that is all about – we have a culture of service. It's really all about – everybody at NSBP land is volunteer. Completely volunteer. It's a lot of work, and it's generative on the idea that the students who are now being mentored one day will be the presidents and the board people and the treasurers who are now doing that for the next generation. It was my time. I feel like I benefited so much that now it's my turn.
I'm so proud to be a part of an institute that created the TEAM-UP report. I wonder if you had anything to do with that, and in what ways it might be valuable for the broader things you're looking to accomplish.
Yeah, I think it was great work that the TEAM-UP report was done. Kudos. I wasn't directly involved, but a handful of my colleagues, including NSBP members, were involved. And I was able to use some of those findings to make the case for this STEM initiative that I'm helping to forge in New York City called Universal Museum of Hip Hop in the Bronx. I was able to use exactly – just a clear finding that's obvious to a lot of us, but it was important that the research was done to establish that. If you don't meet young people at the level of science where they feel like – if you don't feel like you identify with the community, or identify as being a scientist because who you are inherently is not representative of being a scientist, you could be as talented as you want, but you're swimming up a stream, right? Also, if you don't feel welcome and you don't feel like you're a part of this whole thing, again – you know? So, I was able to use some of that finding in a narrative to make the case for, how do we bring in physics and science into a hip hop museum?
I can't wait to read it when it comes out, but perhaps as some coming attractions, do you deal with the nomenclature that could be construed as racially tinged of dark matter and dark energy in Fear of a Black Universe?
Say that one more time. That's a good question, so you've got to say that one more time.
So, like, the way that in colonial times, Africa was referred to as the "dark continent," which obviously had negative racial connotations. Dark matter a dark energy could – obviously, I'm not saying that the people who came up with those terms had those intentions, but there could be some connection there with the terminology that might have a racial component to it. I wonder if you ever reflected on that, and if that was something that you saw as something obvious to deal with in Fear of a Black Universe.
Yeah, yeah, it was deliberate actually. So, the title itself was a play on that which we don't understand, that which we ignore, that which we stigmatize, that which we are afraid of. We tag it with the name black, or dark, including dark energy and dark matter. And if you want to say that applies to people from the dark continent, you can say that too. But also, the flip side is that if you jump into the darkness and you embrace it, actually you might discover new things. It also has a spiritual tone to it because the book begins with a quote from Isha Upanishad, which begins with – in our quest for maybe spiritual enlightenment, it goes, "Into blind and darkness enter those who worship ignorance. Into, as if still, greater darkness, enter those who delight in knowledge." That's one of the main texts, verses in Upanishads. So, yeah, the book has fun with that and uses that basically as a device. You know how Stephen Hawking wants to know the mind of God? This is a device that basically surveys some of the cutting-edge ideas in modern physics and cosmology, including dark energy and what have you. Dark matter, and black holes, and things like that, to sort of – also look at, what are the ideas that we're most afraid of? These dark ideas, these ideas that we want to stigmatize, maybe it's time for us to start embracing them and not be afraid of them because of the consequences of being stigmatized, of being Michael Faraday and being kicked out of the club or being Carl Wu because of invisible lines of force. Well, it turned out to be the fundamental paradigm of physics, the field idea. That's Michael Faraday, but he was called idiotic when he had that idea.
And I wonder if you see long-term scientific value in just having different cultural perspectives applied to such fundamentally mysterious things like dark energy and dark matter, because the way things are, we don't know what either of them are.
That's right. I think there's value. I think there's a lot of value in that, in the same way that if we think of it as yet another tool in our toolbox – we have language as a tool, we have mathematics as a tool, we have computers now. These are all tools. It's not going to kill us to widen our toolbox, and it doesn't mean that we give up the other tools that we have. They shouldn't threaten the other ones. I look at it like that. So, let's put them all on the table and see which ones and how they are combined that leads us to – let experiment be the god.
I'll just play devil's advocate a little bit on this concept of being an outsider. I assume you're the personal narrator to an Outsider's Guide to the Future of Physics. So, Professor Alexander, right? You're a professor of physics at an Ivy League university, you're on speaking terms with all the eminent physicists out there, you're super well-regarded in the field. Are you really an outsider?
Yes, yes, yes, I see your question, and part of this book was exploring that. It was actually a meditation on who – I have all this stuff that if you look at the face of it makes me look like an insider. But my internal perspective, my internal feeling on a day-to-day basis is that sometimes I find myself in a room with other physicists where I'm usually in the corner of the room sitting and drinking that glass of wine by myself. So, I think that would be a certain experience that I still have where I don't feel completely on the inside, even though on paper it looks as if I'm on the inside. But there's another perspective that I want to say. And the other one is a willful – that actually there's a part of me that embraces I always want to keep one foot on the outside, because I see the value of always having a foot on the outside, and my ear to the ground with the outsiders. I think there's value there, and if I ever completely jump on the inside, I will lose that. So, I look at graffiti artists, who even though their art ended up from the subway stations and the building – whatever – they were vandals into high institutes of art, and into galleries and selling for millions of dollars. A lot of them still kept a foot on the outside. So, for me that's kind of – the outside thing for me is it's more like me making that choice to keep a foot on the outside and be one of those people that act as a conduit from the outside to the inside.
I wonder, as a jazz musician, if by necessity you have to be an outsider to some degree.
That's right. That's a good point. There are these other things that just make me – as I said, I write books now. I'm a jazz musician. Maybe some of my colleagues are like, this guy's not serious now. He's writing books and playing music on the side. He's not really one of us – kind of stuff. So, all of these things I engage in, there is a sense in which maybe that stuff, to the insiders, make me an outsider. But if you look at the language of this, "An outsider's guide," it's written for outsiders too. So, it's not clear who the outsider is. There's some ambiguity there.
Just to bring the conversation right up to the present, what are some of the things that you're thinking about now that will have long-term implications for your research agenda five, ten, twenty years into the future?
Oh, that's a good one. I think the work I'm doing now on quantum gravity, that general relativity with a cosmological constant in four dimensions can be encoded by an exactly soluble three-dimensional quantum gravity thing, in terms of topological information. I'm not saying that's going to be the final, but this is starting to smell like maybe how we should think about quantum gravity. There is a sense in which that connects up to the Hartle-Hawking wave function of the universe, so that the universe can be entire a quantum mechanical system. I hope that will make a contribution. The other thing is I did play – I do have the credit for being the first person to propose using machine learning in cosmology way back in 1997. I never pursued it back then. I went straight into cosmology. But I think that idea of using machine learning in fundamental physics – when I say using, the idea that the universe and the laws can be a self-learning system, this is some work I did recently with colleagues at Microsoft. Jaron Lanier, Lee Smolin, Dave Wecker and some students, the idea that we can think about the laws themselves as a machine learning architecture. I think that's crazy, but it'll be interesting to see if there is some semblance that the laws themselves evolve as some kind of machine learning, artificial intelligent architecture. The laws themselves look like that architecture.
Where do you see quantum computing's role in helping us to figure out some of these fundamental mysteries?
Hm. I still remain skeptical about really building a full laptop, tabletop quantum computer. But if we are to do it, definitely the quantum mechanics exists to say that, yeah, I think it'll play a big role because we'll be able to simulate, just on its own terms, quantum computation with the quantum computers. Now, we're trying to simulate quantum computation with classical computers, and that's already – it'll be a whole different world. Let me just leave it at that. It'll be a whole different world.
Well, Stephon, now that we've worked our way right up to the present, for the last part of our talk, I'd like to ask a few broadly retrospective questions about your career, and then we'll end looking to the future. So, one is, just an observation, from your publication list, you almost always have coauthors. I wonder if you've ever reflected on the similarity between collaborators on a paper, and improvisers in a jazz trio or quartet.
Oh, big time. Yes, yes. Yeah, I think one place where that was very evident was the work I did with Michael Peskin and Mohammad Sheikh-Jabbari on our idea of baryogenesis from inflation. That was definitely more like group improvisation, where somebody throws an idea, and the other person takes the idea and solos with it a little it. The other one is playing the rhythm section and holding the fort and making sure that the calculations are stable and correct. So, the answer is yes. But now my research group is – unfortunately, with the pandemic it can't be, but when we hang out in person, it's very much like that. Someone goes to the blackboard, they just go. You are encouraged to start doing some crazy, what have you, speculations, with the expectation that the rest of the group is basically on the lookout for something interesting because you don't know where it's going to come from. And then, now, let's actually go and willfully play some sheet music. Let's actually do a formal calculation now. So, different stages.
Of all of the projects you've worked on in all of your collaborations, what's been the most intellectually satisfying moment for you? Either a discovery, either a eureka moment, either when something just clicked for you in terms of understanding something that you didn't understand before.
Say it one more time.
Of all the things that you've worked on, when you just have that moment where you understand something that you didn't before, either that led to a major discovery or just filled a gap in your own personal knowledge. What stands out in your memory as being most intellectually satisfying?
Yeah, I think when I did D-brane inflation, I was in Morocco, in Casablanca, and combination of both being in Paris, it was one of those moments where – maybe it was Paris – where, like, I was at a jazz club and doodling on a napkin while there was some solo going on. The saxophonist was soloing, and I was doodling around with some new stuff I had just learned at the M-theory workshop earlier on that day, or maybe earlier in the week. And then people were clapping, and these two things clashed, and I thought about these D-branes colliding. Next thing you know, there are some calculations with a published paper.
What have you learned in improvisation that tells you, on those difficult problems, where no matter what you do you hit a wall – what have you learned that tells you when to switch direction and do something new, and when to stick at it until you break down that wall?
That's actually an interesting thing. In terms of jazz improvisation, but also practice, and when do you keep beating yourself over the head with something and move on? I think some of it is also with – in both cases, in both jazz practice and development and theoretical physics, there is a sense in which – some of the greatest physicists I know are so persistent, they just will not let up on something. They're obsessed, and there's this delicate dance between knowing when to – as you said – this is clearly wrong. When do I switch gears? I'm actually struggling with this right now with a postdoc of mine. He wants to be so mathematically correct, but to not realize that even the math itself is – the math you're using, the theoretical framework you're using that you want to stay strict with requires sometimes – sometimes you have to create new directions and maybe modify the math a bit and be driven – let the process driving your car not be the math but be the intuition. So, that to me is where, like, okay, this is not making sense. Let me just back up and throw away the equations. What's going on intuitively? So, yeah, the answer for that is that I always jump back and take stock of, what's the physics saying here? Does this physically make sense that this is happening? Maybe let's go back to a simple physical idea. Or what am I assuming here where these rules might need to be modified to accommodate the answer that I want? So, that to me is a delicate dance. You're walking a tightrope.
Stephon, last question, looking to the immediate future, as we're just starting to peek beyond the pandemic and getting back to life as normal, as a musician, as a physicist with an inherent appreciation of the value of physical interaction, either at the seminar table at the white board, or onstage with your fellow musicians, what are you most excited about getting back to?
I want to get back to my group, and just hang out with my group in my little theory space and our little blackboard, and just jumping in and continuing our in person – there's a lot of things that are going on that are nonverbal that are essential for research. There are all these little intricacies and subtleties. You look at somebody's face, and it looks confused. Like, what are you confused about? Just let me know. Please tell me. That kind of stuff. You're not going to get that nuance in the current situation that we're in.
And that's also going to be true for music. You really can't do that over Zoom.
You can't do that over Zoom at all. Yeah, I mean, it's not clear to me that – I mean, the music side of things, it'll be interesting to see if I continue playing with the save fervor. I'm interested now in this connection between music and cognitive science and how some of the ideas of physics can be imported into that. So, I'm looking forward also to that research direction.
Well, that sounds exciting. We'll stay tuned for that. Stephon, this has been a fantastic conversation. Thank you so much for doing this. I'm so glad we were able to spend this time together.
Okay, thank you.