Sean Carroll Family. The specific thing I've been able to do in Los Angeles is consult on Hollywood movies and TV shows, but had I been in Boston, or New York, or San Francisco, I would have found something else to do. But when I was in Santa Barbara, I was at the epicenter. It worked for them, and they like it. He asked me -- I was a soft target, obviously -- he asked me to give a talk at the meeting, and my assignment was measuring cosmological parameters with everything except for the cosmic microwave background. We should move into that era." The argument I make in the paper is if you are a physicalist, if you exclude by assumption the possibility of non-physical stuff -- that's a separate argument, but first let's be physicalists -- then, we know the laws of physics governing the stuff out of which we are made at the quantum field theory level. And he said, "Absolutely. By the strategy, it's sort of saving some of the more intimidating math until later. January 2, 2023 11:30 am. I thought that given what I knew and what I was an expert in, the obvious thing to write a popular book about would be the accelerating universe. As the advisor, you can't force them into the mold you want them to be in. That's my question. Even though academia has a love for self-scrutiny, we overlook the consequences of tenure denial. His research focuses on issues in cosmology, field theory, and gravitation. Again, and again, you'd hear people say, "Here's the thing I did as a graduate student, and that got me hired as a faculty member, but then I got my Packard fellowship, and I could finally do the thing that I really wanted to do, and now I'm going to win the Nobel Prize for doing that." Well, I'm not sure that I ever did get advice. Everyone knows about that. They brought me down, and I gave a talk, but the talk I could give was just not that interesting compared to what was going on in other areas. But when you go to graduate school, you don't need money in physics and astronomy. I learned afterward it was not at all easy, and she did not sail through. So, just for me, they made up a special system where first author, alphabetical, and then me at the end. Some places like Stanford literally have a rule. No one cares what you think about the existence of God. He wasn't bothered by the fact that you are not a particle physicist. Now that you're sort of outside of the tenure clock, and even if you're really bad at impressing the right people, you were still generally aware that they were the right people to impress. I taught a couple of courses -- not courses, but like guest lectures when I was in high school. And then, even within physics, do you see cosmology as the foundational physics to talk about the rest of physics, and all the rest of science in society? So, in the second video, I taught them calculus. They met with me, and it was a complete disaster, because they thought that what I was trying to do was to complain about not getting tenure and change their minds about it. On my CV, I have one category for physics publications, another category for philosophy publications, and another category for popular publications. And Sidney was like, "Why are we here? So, happily, I was a postdoc at Santa Barbara from '96 to '99, and it was in 1998 that we discovered the acceleration of the universe. He was trying to learn more about the early universe. Some even tried to show me the dark aspects of tenure, which to me sounded like a wealthy person's complaints about wealth. Were there tenure lined positions that were available to you, but you said, you know what, I'm blogging, I'm getting into outreach, I'm doing humanities courses. I've said this before, but I want to live in the world where people work very hard 9 to 5 jobs, go to the pub for a drink, and talk about what their favorite dark matter particle candidate is, or what their favorite interpretation of quantum mechanics is. This is something that is my task to sort of try to be good in a field which really does require a long attention span as someone who doesn't really have that. There haven't been any for decades, arguably since the pion was discovered in 1947, because fundamental physics has understood enough about the world that in order to create something that is not already understood, you need to build a $9 billion particle accelerator miles across. You had already dipped your toe into this kind of work. Talking in front of a group of people, teaching in some sense. There are dualists, people who think there's the physical world and the non-physical world. You mean generally across the faculty. Be proud of it, rather than be sort of slightly embarrassed by it. In other words, the dynamics of physics were irreversible at the fundamental level. Santa Barbara was second maybe only to Princeton as a string theory center. In fact, I'd go into details, but I think it would have been easier for me if I had tenure than if I'm a research professor. So, despite the fact that I connected all the different groups, none of them were really centrally interested in what I did for a living. Carroll conveys the various push and pull factors that keep him busy in both the worlds of academic theoretical physics and public discourse. Sean, when you got to MIT, intellectually, or even administratively, was this just -- I mean, I'm hearing such a tale of exuberance as a graduate. So, every person who came, [every] graduate student, was assigned an advisor, a faculty member, to just sort of guide them through their early years. We did not give them nearly enough time to catch their breath and synthesize things. But clearly it is interesting since everyone -- yeah. Sean recounts his childhood in suburban Pennsylvania and how he became interested in theoretical physics at the age of . You know, I wish I knew. In 2017, Carroll took part in a discussion with B. Alan Wallace, a Buddhist scholar and monk ordained by the Dalai Lama. I just think they're wrong. The point I try to make to them is the following -- and usually they're like, sure, I'm not religious. Onondaga County. It's a necessary thing but the current state of theoretical physicists is guessing. Tenure denial, seven years later. Michael Nielsen, who is a brilliant guy and a friend of mine, has been trying, not very successfully, but trying to push the idea of open science. But they often ask me to join their grant proposal to Templeton, or whatever, and I'm like, no, I don't want to do that. So, it's not an easy hill to climb on. This philosophical question is vitally important to the debate over the causal premiss. The Broncos have since traded for Sean Payton, nearly two years after Wilson's trade list included the Saints. It doesn't really explain away dark matter, but maybe it could make the universe accelerate." There were a lot of required courses, and I had to take three semesters of philosophy, like it or not. So, it is popular, and one of the many nice things about it is that the listeners feel like they have a personal relationship with the host. Did you do that self-consciously? Were you thinking along those lines at all as a graduate student? Yes, I think so. So, I try to judge what they're good at and tell them what I think the reality is. So, to say, well, here's the approach, and this is what we should do, that's the only mistake I think you can make. People always ask, did science fiction have anything to do with it? Hard to do in practice, but in principle, maybe you could do it. Margaret Geller is a brilliant person, so it's not a comment on her, but just how hard it is to extrapolate that. I literally got it yesterday on the internet. I thought it would be more likely that I'd be offered tenure early than to be rejected. When I first got to graduate school, I didn't have quantum field theory as an undergraduate, like a lot of kids do when they go to bigger universities for undergrad. Anyone who's a planetary scientist is immediately interdisciplinary, because you can't be a planetary -- there's no discipline called planetary sciences that is very narrow. It's taken as a given that every paper will have a different idea of what that means. Is your sense that your academic scholarly vantage point of cosmology allows for some kind of a privileged or effective position within public debate because so much of the basis of religion is based on the assumption that there must be a God because a universe couldn't have created itself? He was a blessing, helping me out. Melville, NY 11747 The actual question you ask is a hard one because I'm not sure. Wilson denied it, calling Pete a father figure and claiming he never wanted them . I didn't think that it would matter whether I was an astronomy major or a physics major, to be honest. I knew relativity really well, but I still felt, years after school, that I was behind when it came to field theory, string theory, things like that. Okay. But look, all these examples are examples where there's a theoretical explanation ready to hand. There were literally two people in my graduating class in the astronomy department. Young people. I want it to be proposing new ideas, not just explaining ideas out there. I wrote about supergravity, and two-dimensional Euclidian gravity, and torsion, and a whole bunch of other different things. And I applied there to graduate school and to postdocs, and every single time, I got accepted. And who knows, it all worked out okay, but this sort of background, floating, invisible knowledge is really, really important, and was never there for me. He wrote the paper where they actually announced the result. I was still thought to be a desirable property. Carroll explains how his wide-ranging interests informed his thesis research, and he describes his postgraduate work at MIT and UC Santa Barbara. That's what supervenience means. So, string theory was definitely an option, and I could easily have done it if circumstances had been different, but I never really regretted not doing it. Of course, Harvard astronomy, at the time, was the home of the CFA redshift survey -- Margaret Geller and John Huchra. Brian was the leader of one group, and he was my old office mate, and Riess was in the office below ours. I care a lot about the substance of the scientific ideas being accurately portrayed. They made a hard-nosed business decision, and they said, "You know, no one knows who you are. The physics department had the particle theory group, and it also had the relativity group. I wonder, in what ways, given the fact that you have this tremendous time spending with all these really smart people talking about all these great ideas, in what ways do you bring those ideas back to your science, back to the Caltech, back to the pen and paper? Sean Carroll. Sep 2010 - Jul 20165 years 11 months. I think it's more that people don't care. Washington was just a delight. They promote the idea of being a specialist, and they just don't know what to do with the idea that you might not be a specialist. So, he founded that. Suite 110 Sean, for my last question, looking forward, I want to reflect on your educational trajectory, and the very uncertain path from graduate school to postdoc, to postdoc to the University of Chicago. But then there are other times when you're stuck, and you can't even imagine looking at the equations on your sheet of paper. So, the fact that it just happened to be there, and the timing worked out perfectly, and Mark knew me and wanted me there and gave me a good sales pitch made it a good sale. A nontrivial fraction of tenure-track faculty are denied tenure, well over the standard 5% threshold for Type I errors that we use in the sciences. I have a lot of graduate students. Sean, did you enjoy teaching undergraduates? People think they've heard too much about dark energy, and honestly, your proposal sounds a little workmanlike. The specific way in which that manifests itself is that when you try to work, or dabble, if you want to put it that way, in different areas, and there are people at your institution who are experts in those specific areas, they're going to judge you in comparison with the best people in your field, in whatever area you just wrote in. So, this is when it was beneficial that I thought differently than the average cosmologist, because I was in a particle theory group, and I felt like a particle theorist. I would have gone to Harvard if I could have at the time, but I didn't think it was a big difference. Not necessarily because they were all bookish. Carroll is the author of Spacetime And Geometry, a graduate-level textbook in general relativity, and has also recorded lectures for The Great Courses on cosmology, the physics of time and the Higgs boson. Theoretical cosmology at the University of Chicago had never been taught before. These are all things people instantly can latch onto because they're connected to data, the microwave background, and I always think that's important. I've done it. That was always temporary. No one gets a PhD in biology and ends up doing particle physics. He has written extensively on models of dark energy and its interactions with ordinary matter and dark matter, as well as modifications of general relativity in cosmology. Basically Jon Rosner, who's a very senior person, was the only theorist who was a particle physicist, which is just weird. You don't understand how many difficulties -- how many systematic errors, statistical errors, all these observational selection biases. And he was intrigued by that, and he went back to his editors. I absolutely am convinced that one of the biggest problems with modern academic science, especially on the theoretical side, is making it hard for people to change their research direction. We wrote a lot of papers together. So, it made it easy, and I asked both Alan and Eddie. And it's not just me. You're really looking out into the universe as a whole. The Santa Fe Institute is this unique place. Is writing a graduate-level textbook in general relativity, might that have been perceived as a bit of a bold move for an assistant professor? So, we talked about different possibilities. And I answered it. They're trying to understand not how science works but what the laws of nature are. Probably his most important work was on the interstellar and intergalactic medium. It denied her something she earned through hard work and years of practice. That's the job. I'm close enough. I ended up going to MIT, which was just down the river, and working with people who I already knew, and I think that was a mistake. So, yeah, I can definitely look to people throughout history who have tried to do these things. I'm very happy with that. I want to say the variety of people, and just in exactly the same way that academic institutions sort of narrow down to the single most successful strategy -- having strong departments and letting people specialize in them -- popular media tries to reach the largest possible audience. I didn't really know that could be a thing, but I was very, very impressed by it. They'll hire you as a new faculty member, not knowing exactly what you're going to do, but they're like, alright, let's see. And, you know, video sixteen got half a million views, and it was about gravity, but it was about gravity using tensors and differential geometry. There was one that was sort of interesting, counterfactual, is the one place that came really close to offering me a faculty job while I was at KITP before they found the acceleration of the universe, was Caltech. That's right. And the most direct way to do that is to say, "Look, you should be a naturalist. Part of it is what I alluded to earlier. Polchinski was there, David Gross arrived, Gary Horowitz, and Andy Strominger was still there at the time. If you've been so many years past your PhD, or you're so old, either you're hired with tenure, or you're not hired on the faculty. I'm very pleasantly surprised that the podcast gets over a hundred thousand listeners ever episode, because we talk about pretty academic stuff. No, I think I'm much more purposive about choosing what to work on now than I was back then. I did not get into Harvard, and I sweet talked my way into the astronomy department at Harvard. I'm trying to develop new ideas and understand them. Yes, but it's not a very big one. They are clearly different in some sense. I could have probably done the same thing had I had tenure, also. I had done a postdoc for six years, and assistant professor for six by the time I was rejected for tenure. The astronomy department was just better than the physics department at that time. It was very small. Even though we overlapped at MIT, we didn't really work together that much. I had great professors at Villanova, but most of the students weren't that into the life of the mind. We have dark energy, it's pushing the universe apart, it's surprising. The guy, whoever the person in charge of these things, says, "No, you don't get a wooden desk until you're a dean." There's a large number of people who are affiliated one way or the other. So, a lot of the reasons why my path has been sort of zig-zaggy and back and forth is because -- I guess, the two reasons are: number one, I didn't have great sources of advice, and number two, I wasn't very good at taking the advice when I got it. Sidney Coleman, who I mentioned, whose office I was in all the time. Huge excitement because of this paper. Thanks very much. So, the undergraduates are just much more comfortable learning it. In other words, let's say you went to law school, and you would now have a podcast in an alternate [universe] or a multiverse, on innovation, or something like that. We could discover what the dark matter is. Hopefully it'll work out. But within the physical sciences, there are gradations in terms of one's willingness to consider metaphysics as something that exists, that there are things about the universe that are not -- it's not a matter of them being not observable now because we lack the theories or the tools to observe them, but because they exist outside the bounds of science. We made a bet not on what the value of omega would be, but on whether or not we would know the value of omega twenty years later. Whereas, if you're just a physicalist, you're just successful. I didn't really want to live there. I remember having a talk with Howard Georgi, and he didn't believe either the solar neutrino problem, or Big Bang nucleosynthesis. But very few people in my field jump on that bandwagon. To second approximation, I care a lot about the public image of science. On that note, as a matter of bandwidth, do you ever feel a pull, or are you ever frustrated, given all of your activities and responsibilities, that you're not doing more in the academic specialty where you're most at home?