Actually, I didn't write a paper with Sidney either. I wrote about supergravity, and two-dimensional Euclidian gravity, and torsion, and a whole bunch of other different things. You can be surprised. Formerly a research professor in the Walter Burke Institute for Theoretical Physics in the California Institute of Technology (Caltech) Department of Physics,[1] he is currently an External Professor at the Santa Fe Institute,[2] and the Homewood Professor of Natural Philosophy at Johns Hopkins University. I think it's more that people don't care. We're kind of out of that. (2013) Brave Genius: A Scientist, a Philosopher, and Their Daring Adventures from the French Resistance to the . It does not lead -- and then you make something, and it disappears in a zeptosecond, 10^-21 seconds. And I think that I need to tell my students that that's the kind of attitude that the hiring committees and the tenure committees have. In some extent, it didn't. When I went to MIT, it was even worse. Someone at the status of a professor, but someone who's not on the teaching faculty. And I've learned in sort of a negative way from a lot of counterexamples about how to badly sell the ideas that science has by just hectoring people and berating them and telling them they're irrational. Hopefully, this person is going to be here for 30 or 40 years. You didn't ask a question, but yes, you are correct. Bob is a good friend of mine, and I love his textbook, but it's very different. What were those topics that were occupying your attention? So, again, I sort of brushed it off. To get started, would you please tell me your current titles and institutional affiliations? but academe is treacherous. Cole. Well, I have visited, just not since I got the title. That's not all of it. Here is a sort of embarrassing but true story, which, I guess, this is the venue to tell these things in. He'd already retired from being the director of the Center for Astrophysics, so you could have forgiven him for kicking back a little bit, but George's idea of a good time is to crank out 30 pages of handwritten equations on some theory that we're thinking about. If I can earn a living doing this, that's what I want to do. Whereas there are multiple stories of people with PhDs in physics doing wonderful work in biology. Really, really great guy. As long as they were thinking about something, and writing some equations, and writing papers, and discovering new, cool things about the universe, they were happy. But I think, as difficult as it is, it's an easier problem than adding new stuff that pushes around electors and protons and neutrons in some mysterious way. I didn't think that it would matter whether I was an astronomy major or a physics major, to be honest. They didn't even realize that I did these things, and they probably wouldn't care if they did. So, I played around writing down theories, and I asked myself, what is the theory for gravity? So, I could completely convince myself that, in fact -- and this is actually more true now than it maybe was twenty years ago for my own research -- that I benefit intellectually in my research from talking to a lot of different people and doing a lot of different kinds of things. It used to be the case that there was a close relationship between discoveries in fundamental physics and advances in technology, whether it was mechanics, electromagnetism, or quantum mechanics. So to you nit-pickers who, amongst other digs at Sean and his records(s), want . That was always holding me back that I didn't know quantum field theory at the time. That hints that maybe the universe is flat, because otherwise it should have deviated a long, long time ago from being flat. I went to church, like I said, and I was a believer, such as it was, when I was young. They soon thereafter hired Ramesh Narayan, and eventually Avi Loeb, and people like that. I hope that the whole talk about Chicago will not be about me not getting tenure, but I actually, after not getting tenure, I really thought about it a lot, and I asked for a meeting with the dean and the provost. I looked at the list and I said, "Well, honestly, the one thing I would like is for my desk to be made out of wood rather than metal. They had these cheap metal desks. I'd like to start first with your parents. Please bear in mind that: 1) This material is a transcript of the spoken word rather than a literary product; 2) An interview must be read with the awareness that different people's memories about an event will often differ, and that memories can change with time for many reasons including subsequent experiences, interactions with others, and one's feelings about an event. I think I did not really feel that, honestly. So, it was to my benefit that I didn't know, really, what the state of the art was. The Russell Wilson drama continues, now almost one full year removed from the trade that sent him from the Seahawks to the Broncos. You get one quarter off from teaching every year. You can mostly get reimbursed, but I'm terrible about getting reimbursed. And that's the only thing you do. As I was getting denied tenure, nobody suggested that tenure denial was . and as an assistant professor at the University of Chicago until 2006 when he was denied tenure. Then, when I got to MIT, they knew that I had taught general relativity, so my last semester as a postdoc, after I had already applied for my next job, so I didn't need to fret about that, the MIT course was going to be taught by a professor who had gone on sabbatical and never returned. You can read any one of them on a subway ride. So, thank you so much. I'm not making this up. Like, crazily successful. Yeah, it's what you dream about academia being like. But the fruits of the labors had not come in yet. You can be a physicalist and still do metaphysics for your living. Six months is a very short period of time. But we discovered in 1992, with the COBE satellite, the anisotropies in the cosmic microwave background, and suddenly, cosmology came to life, but only if you're working on the cosmic microwave background, which I was not. I did not have it as a real priority, but if I did something, that's what I wanted to do. I remember Margaret Geller, who did the CFA redshift survey, when the idea of the slow and digital sky survey came along and it was going to do a million galaxies instead of a few thousand, her response was, "Why would you do that? Institute for Theoretical Physics. So, yeah, I can definitely look to people throughout history who have tried to do these things. Being surrounded by the best people was really, really important to me. I would say that implicitly technology has been in the background. People shrugged their shoulders and said, "Yeah, you know, there's zero chance my dean would go for you now that you got denied tenure.". There's a quote that is supposed to be by Niels Bohr, "Making predictions is hard, especially about the future." But there's an enormous influence put on your view of reality by all of these pre-existing propositions that you think are probably true. What do I want to optimize for, now that I am being self-reflective about it? In my mind, there were some books -- like, Bernard Schutz wrote a book, which had this wonderful ambition, and Jim Hartle wrote a book on teaching general relativity to undergraduates. Not to give away the spoiler alert, but I eventually got denied tenure at Chicago, and I think that played a lot into the decision. Besides consulting, Carroll worked as a voice actor in Earth to Echo. Everyone could tell which courses were good at Harvard, and which courses were good at MIT. We'll get into the point where I got lucky, and the universe started accelerating, and that saved my academic career. So, it's not quite true, but in some sense, my book is Wald for the common person. Let's get back to Villanova. I didn't do what I wanted to do. There's always some institutional resistance. Is it the perfect situation? Actually, Joe Silk at Berkeley, when I turned down Berkeley, he said, "We're going to have an assistant professorship coming up soon. So, I suspect that they are here to stay. But I would guess at least three out of four, or four out of five people did get tenure, if not more. Having said that, you bring up one of my other pet crazy ideas, which is I would like there to be universities, at least some, again, maybe not the majority of them, but universities without departments. And Sidney Coleman, bless his, answered all the questions. And in the meantime, Robert Caldwell, Marc Kamionkowski, and others, came up with this idea of phantom energy, which had w less than minus one. I learned general relativity from Nick Warner, which later grew into the book that I wrote. And then I got an email from Mark Trodden, and he said, "Has anyone ever thought about adding one over R to the Lagrangian for gravity?" Honestly, the thought of me not getting tenure just didn't occur to me, really. because a huge part of my plan was to hang out with people who think about these things all the time. When you're falling asleep, when you're taking a shower, when you're feeding the cat, you're really thinking about physics. There are things the rest of the world is interested in. Garca Pea's first few years at Harvard were clouded by these interactions, but from the start her students . As far as I was concerned, the best part was we went to the International House of Pancakes after church every Sunday. Yes, it is actually a very common title for Santa Fe affiliated people. But interestingly, the kind of philosophy I liked was moral and political philosophy. A few years after I got there, Bruce Winstein, who also has passed away, tragically, since then, but he founded what was at the time called the Center for Cosmological Physics and is now the Kavli Institute for Cosmological Physics at Chicago. But, you know, I did come to Caltech with a very explicit plan of both diversifying my research and diversifying my non-research activities, and I thought Caltech would be a great place to do that. There were two sort of big national universities that I knew that were exceptions to that, which were University of Chicago, and Rice University. Because you've been at it long enough now, what have been some of the most efficacious strategies that you've found to join those two difficulties? When you come up for tenure, the prevailing emotion is one of worry. I do have feelings about different people who have been chosen as directors of institutes and department chairs. This is a weird list. There were two that were especially good. Maybe I fall short of being excellent at them, but at least I'm enthusiastic about them. It was like suddenly I was really in the right place at the right time. I get that all the time. So, it's not just that you have your specialty, but what niche are you going to fill in that faculty that hires you. Not especially, no. The article generated significant attention when it was discussed on The Huffington Post. We did briefly flirt with the idea that I could skip a grade when I was in high school, or that I could even go to a local private school. So, if you've given them any excuse to think that you will do things other than top-flight research by their lights, they're afraid to keep you on. Furthermore, anyone who has really done physics with any degree of success, knows that sometimes you're just so into it that you don't want to think about anything else. At Caltech, as much as I love it, I'm on the fourth floor in the particle theory group, and I almost never visit the astronomers. It costs me money, but it's a goodwill gesture to them, and they appreciate it. Also, my individual trajectory is very crooked and unusual in its own right. A defense of philosophical naturalism, a brand of naturalism, like a poetic naturalism. And the other thing was honestly just the fact that I showed interest in things other than writing physics research papers. We also have dark matter pulling the universe together, sort of the opposite of dark energy. So, I try to judge what they're good at and tell them what I think the reality is. Like, when people talk about the need for science outreach, and for education and things like that, I think that there is absolutely a responsibility to do outreach to get the message out, especially if the kind of work you do has no immediate economic or technological impact. Chicago is a little bit in between. But I'm unconstrained by caring about whether they're hot topics. He is, by any reasonable measure, a very serious physicist. Philosophical reflections on the nature of reality, and the origin of the universe, and things like that. That's okay. The astronomy department at Harvard was a wonderful, magical place, which was absolutely top notch. It wasn't until my first year as a postdoc at MIT when I went to a summer school and -- again, meeting people, talking to them. In fact, you basically lose money, because you have to go visit Santa Fe occasionally. It was a lot of fun because there weren't any good books. We don't care what you do with it." I was a theorist. I know the theme is that there's no grand plan, but did you intuit that this position would allow you the intellectual freedom to go way beyond your academic comfort home and to get more involved in outreach, do more in humanities, interact with all kinds of intellectuals that academic physicists never talk to. 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. Well, one ramification of that is technological. This is something that's respectable.". Bob Geroch was there also, but he wasn't very active in research at the time. Not only do we have a theory that fits all the data, but we also dont even have a prediction for that theory that we haven't tested yet. I got books -- I liked reading. in The Blackwell Companion to Science and Christianity develops the claim that science no longer needs to posit a divine being to explain the existence of the universe. So, you're asking for specific biases, and I'm not very good at giving you them, but I'm a huge believer that they're out there, and we should all be trying our best to open our eyes to what they could be. The paper was on what we called the cosmological constant, which is this idea that empty space itself can have energy and push the universe apart. That's it. 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. He wasn't bothered by the fact that you are not a particle physicist. I don't know how it reflected in how I developed, but I learn from books more than from talking to people. Jim was very interdisciplinary in that sense, so he liked me. People were very unclear about what you could learn from the microwave background and what you couldn't. I wrote a blog post that has become somewhat infamous, called How to Get Tenure at a Major Research University. I was surprised when people, years later, told me everyone reads that, because the attitude that I took in that blog post was -- and it reflects things I tell my students -- I was intentionally harsh on the process of getting tenure. 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. I say, "Look, there are things you are interested in. -- super pretentious exposition of how the world holds together in the broadest possible sense. It was a little bit of whiplash, because as a young postdoc, one of the things you're supposed to do is bring in seminar speakers. Now, there are a couple things to add to that. Again, I just worked with other postdocs. I didn't even get on any shortlists the next year. What I discovered in the wake of this paper I wrote about the arrow of time is a whole community of people I really wasn't plugged into before, doing foundations of physics. I pretend that they're separate. But mostly, I hope it was a clear and easy to read book, and it was the first major book to appear soon after the discovery of the Higgs boson. Eric Adelberger and Chris Stubbs were there, who did these fifth force experiments. As a result, I think I wrote either zero or one papers that year. I really do think that in some sense, the amount that a human being is formed and shaped, as a human being, not as a scientist, is greater when they're an undergraduate than when they're a graduate. People think they've heard too much about dark energy, and honestly, your proposal sounds a little workmanlike. Not necessarily because they were all bookish. I don't have to go to the class, I don't have to listen to you, I'll sign the piece of paper." So, that was my first glimpse at purposive, long term strategizing within theoretical physics. Carroll endorses Everett's Many Worlds Interpretation and denies the existence of God. Like I said, the reason we're stuck is because our theories are so good. We encourage researchers to utilize the full-text search onthis pageto navigate our oral histories or to useour catalogto locate oral history interviews by keyword. As a result, he warns that any indication of interest in these circumstances may be evaporates after denial of the tenure application. [29], Carroll is married to Jennifer Ouellette, a science writer and the former director of the Science & Entertainment Exchange.[30]. Also, I got on a bunch of other shortlists. So, I was behind already. I never was a strong atheist, or outspoken, or anything like that. Also, I think that my science fiction fandom came after my original interest in physics, rather than before. That's not going to lead us to a theory of dark matter, or whatever. This is an example of it. Einstein did that, but nobody had done one over R. And it wasn't like that was necessarily motivated by anything. No, you're completely correct. I want the podcast to be enjoyable to people who don't care about theoretical physics. Why would an atheist find the Many Worlds Interpretation plausible? But very few people in my field jump on that bandwagon. You can't remember the conversation that sparked them. Maybe it's them. Then, a short time later, John Brockman, who is her husband and also in the agency, emails me out of the blue and says, "Hey, you should write a book." You know, students are very different. Well, by that point, I was much more self-conscious of what my choices meant. So, I was still sort of judging where I could possibly go on the basis of what the tuition numbers were, even though, really, those are completely irrelevant. So, I was in my office and someone knocked on my door. So, now that I have a podcast, I get to talk to more cool, very broad people than I ever did before. What's interesting -- you're finally getting the punchline of this long story. Was this your first time collaborating with Michael Turner? No one has written the history of atheism very, very well. Sean, thank you so much for joining me today. That can happen anywhere, but it happens more frequently at a place like Caltech than someplace else. It's just, you know, you have certain goals in life. So, Sean, what were your initial impressions when you got to Chicago? When we were collaborating, it was me doing my best to keep up with George. We had people from England who had gone to Oxford, and we had people who had gone to Princeton and Harvard also. And that gives you another handle on the total matter density. What could I do? What you have to understand is that Carroll isn't just untenured, he's untenurable. Sean, I want to push back a little on this idea that not getting tenure means that you're damaged goods on the academic job market. I played a big role in the physics frontier center we got at Chicago. Because, I said, you assume there's non-physical stuff, and then you derive this conclusion. Both my undergraduate and graduate degrees are in astronomy, and both for weird, historical reasons. A lot of people focus on the fact that he was so good at reaching out to broad audiences, in an almost unprecedented way, that they forget that he was really a profound thinker as well. So, they just cut and pasted those paragraphs into their paper and made me a coauthor. You can see their facial expressions, and things like that. Like I said, we had hired great postdocs there. There was so much good stuff to work on, you didn't say no to any of it, you put it all together. [10] Carroll thinks that over four centuries of scientific progress have convinced most professional philosophers and scientists of the validity of naturalism. How do you understand all of these things? They just don't care. It doesn't always work. I'm a big believer that all those different media have a role to play. I think I talked on the phone with him when he offered me the job, but before then, I don't think I had met him. I'm not exactly sure when it happened, but I can tell you a story. So, Ted and I said, we will teach general relativity as a course. So, taste matters. I could have probably done the same thing had I had tenure, also. So, the Quantum Field Theory on Which the Everyday World Supervenes means you and I and the tables and chairs around us, the lights behind you, the computers we're talking on, supervene on a particular theory of the world at one level, at the quantum field theory level. I was hired to do something, and for better or for worse, I do take what I'm hired to do kind of seriously. By far, the most intellectually formative experience of my high school years was being on the forensics team. Sean recounts his childhood in suburban Pennsylvania and how he became interested in theoretical physics at the age of . And I've guessed. One of the reasons why is she mostly does work in ultra-high energy cosmic rays, which is world class, but she wrote some paper about extra dimensions and how they could be related to ultra-high energy cosmic rays. No, no. It is interesting stuff, but it's not the most interesting stuff. Yeah, and being at Caltech, you have access to some of the very best graduate students that are out there. He received his Ph.D. from Harvard in 1993. This is probably 2000. Seeing my name in the Physical Review just made me smile, and I kept finding interesting questions that I had the technological capability of answering, so I did that. Sean Carroll is a theoretical physicist at the California Institute of Technology. I think that there -- I'm not sure there's a net advantage or disadvantage, but there were advantages. (The same years I was battling, several very capable people I had known in grad school at Berkeley were also denied tenure, possibly caught in the cutbacks at the time, possibly victims of a wave . There are substance dualists, who think there's literally other stuff out there, whether it's God or angels or spirits, or whatever. So, I still didn't quite learn that lesson, that you should be building to some greater thing. So, I raised the user friendliness of it a little bit. There's definitely a semi-permeable membrane, where if you go from doing theoretical physics to doing something else, you can do that. Marc Kamionkowski proposed the Moore Center for Cosmology and Theoretical Physics. I also started a new course, general relativity for undergraduates, which had not been taught before, and they loved it. Harvard came under fire over its tenure process in December 2019, when ethnic studies and Latinx studies scholar Lorgia Garca Pea, who is an Afro-Latina from the Dominican Republic, was denied tenure. The guy, whoever the person in charge of these things, says, "No, you don't get a wooden desk until you're a dean." I want to go back and think about the foundations, and if that means that I appeal more to philosophers, or to people at [the] Santa Fe [Institute], then so be it. And at least a year passed. So, it's sort of bifurcated in that way. You can do a bit of dimensional analysis and multiply by the speed of light, or whatever, and you notice that that acceleration scale you need to explain the dark matter in Milgrom's theory is the same as the Hubble constant. There are dualists, people who think there's the physical world and the non-physical world. When I was very young, we were in Levittown, Pennsylvania. I talked to the philosophers and classicists, and whatever, but I don't think anyone knew. I'm curious how much of a new venture this was for you, thinking about intellectually serving in academic departments. There's one correct amount of density that makes the geometry of space be flat, like Euclid said back in the prehistory. 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. Playing the game, writing the papers that got highly cited, being in the mainstream, and doing things that everyone agreed were interesting, which I did to a certain extent but not all the way when I was in Chicago. That includes me. More than one. Please contact [emailprotected] with any feedback. I guess, I was already used to not worrying too much. Sean Carroll is a Harvard educated cosmologist, a class act and his podcast guests are leaders in their fields. Sean, I'm sorry to interrupt, but in the way that you described the discovery of accelerating universe as unparalleled in terms of its significance, would you put the discovery of the Higgs at a lower tier? Was the church part of your upbringing at all? It wasn't really clear. The wonderful thing about it was that the boundaries were a little bit fuzzy. Ted Pyne and I wrote a couple papers, one on the microwave background. The two advantages I can think of are, number one, at that time, it's a very specific time, late '80s, early '90s -- specific in the sense that both particle physics and astronomy were in a lull. There's a whole set of hot topics that are very, very interesting and respectable, and I'm in favor of them. As a ten year old, was there any formative moment where -- it's a big world out there for a ten year old. That's the job. But I want to remove a little bit of the negative connotation from that. That doesn't work. That's one of the things you have to learn slowly as an advisor, is that there's no recipe for being a successful graduate student. We're creeping up on it. And I didn't because I thought I wasn't ready yet. Carroll, while raised as an Episcopalian,[36] is an atheist, or as he calls it, a "poetic naturalist". It was just -- could that explain away both the dark matter and the dark energy, by changing gravity when space time was approximately flat? So many ideas I want to get on paper. So, maybe conditions down the line will force us into some terrible situation, but I would be very, very sad if that were the case. Maybe some goals come first, and some come after. I think so, but I think it's even an exaggeration to say that Harvard or Stanford don't give people tenure, therefore it's not that bad. I didn't really know that could be a thing, but I was very, very impressed by it. [46] Carroll also asserts that the term methodological naturalism is an inaccurate characterisation of science, that science is not characterised by methodological naturalism but by methodological empiricism.[47]. It's at least possible. Like I aspire to do, he was actually doing. And I thought about it, and I said, "Well, there are good reasons to not let w be less than minus one. So, that's why it's exciting to see what happens. It wasn't fun, it wasn't a surprise and it wasn't the end of anything really, other than my employment at UMass. So, the Caltech job with no teaching responsibilities or anything like that, where I'd be surrounded by absolutely top rate people -- because my physics research is always very highly collaborative, mostly with students, but also with faculty members. So, just for me, they made up a special system where first author, alphabetical, and then me at the end. I think people like me should have an easier time. We make it so hard, and I think that's exactly counterproductive. But then when it comes to giving you tenure, they're making a decision not by what you've done for the last six years, but what you will do for the next 30 years. People are listening with headphones for an hour at a time, right? So, I did finally catch on, like, okay, I need to write things that other people think are interesting, not just me. So, we talked about different possibilities. His recent posting on the matter (at . It's just they're doing it in a way that doesn't get you a job in a physics department. So, cosmologists were gearing up, 1997, late '90s, for all the new flood of data that would come in to measure parameters using the cosmic microwave background. So, I wonder, in what ways can you confirm that outside assumption, but also in reflecting on the past near year, what has been difficult that you might not have expected from all of this solitary work? Absolutely, for me, I'm an introvert. [3][4] He has been a contributor to the physics blog Cosmic Variance, and has published in scientific journals such as Nature as well as other publications, including The New York Times, Sky & Telescope and New Scientist. And guess what? It's hard for me to imagine that I would do that. So, basically, I could choose really what I wanted to write for the next book. And then I could use that, and I did use it, quite profligately in all the other videos. I can do it, and it is fun. Not any ambition to be comprehensive, or a resource for researchers, or anything like that, for people who wanted to learn it. So, then, I could just go wherever I wanted. Now, you might ask, who cares? I started a new course in cosmology, which believe it or not, had never been taught before. So, the undergraduates are just much more comfortable learning it. Santa Barbara was second maybe only to Princeton as a string theory center. They are . Last month, l linked to a series of posts about my job search after tenure denial, and how I settled into my current job. His dissertation was entitled Cosmological Consequences of Topological and Geometric Phenomena in Field Theories.