There were two sort of big national universities that I knew that were exceptions to that, which were University of Chicago, and Rice University. I wonder, for you, that you might not have had that scholarly baggage, if it was easier for you to just sort of jump right in, and say Zoom is the way to do it. There are so many people at Chicago. I'm not quite sure I can tell the difference, but working class is probably more accurate. Carroll received his PhD in astronomy in 1993 from Harvard University, where his advisor was George B. So, my three years at Santa Barbara, every single year, I thought I'll just get a faculty job this year, and my employability plummeted. In retrospect, there's two big things. So, not whether atheism is true or false, but how it developed intellectually. 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. 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. But I want to remove a little bit of the negative connotation from that. Oh, yeah, entirely. All my graduate students were able to get their degrees. But still, way under theorized, really, for the whole operation, if you consider it. We did some extra numerical simulations, and we said some things, and Vikram did some good things, and Mark did too, but I could have done it myself. I really wanted to move that forward. You know, every one [of them] is different, like every child -- they all have their own stories and their own personalities. But it's absolutely true that the system is not constructed to cast people like that int he best possible light. Absolutely the same person.". At the time, . I think there have been people for many, many years who have been excellent at all three of these things individually. So, I was sweet-talked into publishing it without any plans to do it. Literally, it was -- you have to remember, for three years in a row, I'd been applying for faculty jobs and getting the brush off, and now, I would go to the APS meeting, American Physical Society meeting, and when I'd get back to my hotel, there'd be a message on my phone answering machine offering me jobs. You can explain the acceleration of the universe, but you can't explain the dark matter in such a theory. Sean Carroll: I'm not in a super firm position, cause I don't have tenure at Caltech, so, but I don't care either. 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?" We could discover what the dark matter is. That's when I have the most fun. Well, that's not an experimental discovery. The system has benefited them. Then you've come to the right place. So, the year before my midterm evaluation, I spent almost all my time doing two things. I talked to the philosophers and classicists, and whatever, but I don't think anyone knew. So, I gave a lot of thought to that question. Sean, I wonder if you stumbled upon one of the great deals in the astronomy and physics divide. I do a lot of outreach, but if you look closely at what I do, it's all trying to generate new ideas and make arguments. Part of the reason I was able to get as many listeners as I do is because I was early enough -- two and a half years ago, all of the big podcasters were already there. What I mean, of course, is the Standard Model of particle physics plus general relativity, what Frank Wilczek called the core theory. When I applied for my first postdoc, like I said, I was a hot property. I can do cosmology, and I'd already had these lecture notes on relativity. I will confess the error of my ways. But there were postdocs. But I loved science because I hung out at the public library and read a lot of books about blackholes and quarks and the Big Bang. So, I wrote up a little proposal, and I sent it to Katinka Matson, who is an agent with the Brockman Group, and she said something which I think is true, now that I know the business a lot better, which was, "It's true maybe it's not the perfect book, but people have a vague idea that there has been the perfect book. 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. I think I probably took this too far, not worrying too much about what other people thought of my intellectual interests. The four of us wrote a paper. If I could get a million people buy my books, I'd be a really best-selling author. These are all very, very hard questions. Quantum physics is about multiplicity. She could pinpoint it there. I don't know if Plato counts, but he certainly was good at all these different things. I really took the opportunity to think as broadly as possible. But, I mean, I have no shortage of papers I want to write in theoretical physics. w of minus .9 or minus .8 means the density is slowly fading away. Not to put you on the psychologists couch, but there were no experiences early in life that sparked an interest in you to take this stand as a scientist in your debates on religion. And the most direct way to do that is to say, "Look, you should be a naturalist. But Villanova offered me full tuition, and it was closer, so the cost of living would be less. There was a rule in the Harvard astronomy department, someone not from Harvard had to be on your committee. So, there's path dependence and how I got there. Graduate departments of physics or astronomy or whatever are actually much more similar to each other than undergraduate departments are, because they bring people from all these undergraduate departments. So, many of my best classes when I was a graduate student I took at MIT. So, they keep things at a certain level. But the only graduate schools I applied to were in physics because by then I figured out that what I really wanted to do was physics. Carroll provides his perspective on why he did not achieve tenure there, and why his subsequent position at Caltech offered him the pleasure of collaborating with top-flight faculty members and graduate students, while allowing the flexibility to pursue his wide-ranging interests as a public intellectual involved in debates on philosophy . This transcript may not be quoted, reproduced or redistributed in whole or in part by any means except with the written permission of the American Institute of Physics. It's just, you know, you have certain goals in life. Not so they could do it. So, an obvious question arises. The reason is -- I love Caltech. The problem is not that everyone is a specialist, the problem is that because universities are self-sustaining, the people who get hired are picked by the people who are already faculty members there. It just never occurred to me that that would be a strike against me, but apparently it was a huge strike against me. If you found something like a violation of Lorentz invariants, if you found something of the violation of the Schrdinger equation in quantum mechanics, or the fundamental predictions of entanglement, or anything like that. Mark and I continued collaborating when we both became faculty members, and we wrote some very influential papers while we were doing that. But very few people in my field jump on that bandwagon. That would have been a very different conversation if I had. The cosmologists couldn't care, but the philosophers think this paper I wrote is really important. Honestly, the thought of me not getting tenure just didn't occur to me, really. I have graduate students, I can teach courses when I want to, I apply for grants, I write papers. I was a little bit reluctant to do that, but it did definitely seem like the most promising way to go. It won the Royal Society Prize for Best Science Book of the Year, which is a very prestigious thing. In his response to critics he has made a number of interesting claims . The South Pole telescope is his baby. But maybe it could. 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. I think that responsibility is located in the field, not on individuals. I think we only collaborated on two papers. I'm not discounting me. Recent Books. That's my question. I had it. He was born to his father and mother in Philadelphia, Pennsylvania, United States of America. Literally, my math teacher let me teach a little ten minute thing on how to -- sorry, not math teacher. Sean Carroll, bless his physicist's soul, decided to respond to a tweet by Colin Wright (asserting the binary nature of sex) by giving his (Carroll's) own take in on the biological nature of sex. So the bad news is. So, even though these were anticipated, they were also really good benchmarks, really good targets to shoot for. Look at the dynamics of the universe and figure out how much matter there must be in there and compare that to what you would guess the amount of matter should be. My only chance to become famous is if they discovered cosmological birefringence. I didn't stress about that. The topic of debate was "The Existence of God in Light of Contemporary Cosmology". It was funny, because now I have given a lot of talks in my life. But that's okay. So, I went to a large public school. But it's hard to do that measurement for reasons that Brian anticipated. Women are often denied tenure for less obvious reasons, according to studies, even in less gender-biased . And my response to them is what we do, those of us who are interested in the deepest questions about the nature of reality, whether they're physicists, or philosophers, or whoever, like I said before, we're not going to cure cancer. There should be more places like it, more than there are, but it's no replacement for universities. Certainly, I would have loved to go to Harvard, but I didn't even apply. So, it was to my benefit that I didn't know, really, what the state of the art was. Bob Kirshner and his supernova studies were also a big deal. They wanted me, and every single time I turned them down. I literally got it yesterday on the internet. Again, a weird thing you really shouldn't do as a second-year graduate student. You go into it because you're passionate about the ideas, and so forth, and I'm interested in both the research side of academia and the broad picture side of academia. Talking about all of the things I don't understand in public intimidates me. I played a big role in the physics frontier center we got at Chicago. He's a JASON as well, so he has lots of experience in policy and strategizing, and things like that. They can't convince their deans to hire you anymore, now that you're damaged goods. As far as class is concerned, there's no question that I was extremely hampered by not being immersed in an environment where going to Harvard or Princeton was a possibility. I'm not sure, but it was a story about string theory, and the search for the theory of everything. Why is the matter density of the universe approximately similar to the dark energy density, .3 and .7, even though they change rapidly with respect to each other? And there are others who are interested in not necessarily public outreach, but public policy, or activism, or whatever. I said, "Yeah, don't worry. It was mostly, almost exclusively, the former. But I think, that it's often hard for professors to appreciate the difference between hiring a postdoc and hiring a faculty member. It was very long. I think it's fine to do different things, work in different areas, learn different things. I think people like me should have an easier time. I'll just put them on the internet. So, taste matters. Now, you might ask, who cares? I think that I would never get hired by the KITP now, because they're much more into the specialties now. 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. You're not going to get tenure. So, I don't have any obligations to teach students. So, there were these plots that people made of, as you look at larger and larger objects, the implied amount of matter density in the universe comes closer and closer to the critical density. I was thinking of a research project -- here is the thought process. It was a lot of fun because there weren't any good books. The faculty members who were at Harvard, the theorists -- George Field, Bill Press, and others -- they were smart and broad enough to know that some of the best work was being done in this field, so they should hire postdocs working on that stuff. So, they're philosophers mostly, some physicists. And the simplest way to do that is what's called the curvature scalar. I'm very pleasantly surprised that the podcast gets over a hundred thousand listeners ever episode, because we talk about pretty academic stuff. Like you said, it's pencil and paper, and I could do it, and in fact, rather than having a career year in terms of getting publications done, it was a relatively slow year. So, I realized right from the start, I would not be able to do it at all if I assume that the audience didn't understand anything about equations, if I was not allowed to use equations. [8] He occasionally takes part in formal debates and discussions about scientific, religious and philosophical topics with a variety of people. I think all three of those things are valid and important. Remember, I applied there to go to undergraduate school there. Or other things. The discussion with Stuart Bartlett was no exception. So, the idea that I could go there as a faculty member was very exciting to me. You, as the physics department trying to convince the provost and the dean and the president that you should hire this person, that's an uphill battle, always. Reply Insider . If I were really dealing with the nitty gritty of baryon acoustic oscillations or learning about the black hole mass spectrum from LIGO, then I would care a lot more about the individual technological implications, but my interests don't yet quite bump up against any new discoveries right now. Who did you work with? I want to ask, going to Caltech to become a senior research associate, did you self-consciously extricate yourself from the entire tenure world? Everyone sort of nods along and puts up with it and waits for the next equation to come on. If they do, then I'd like to think I will jump back into it. He's the one who edits all my books these days, so it worked out for us. Yeah. So, I think it can't be overemphasized the extent to which the hard detailed work of theoretical physics is done with pencil and paper, and equations, and pictures, little drawings and so forth, but the ideas come from hanging out with people. And that's the only thing you do. I've only lived my life once, and who knows? Again, while I was doing it, I had no idea that it would be anything other than my job, but afterward -- this is the thing. So, basically, giving a sales pitch for the idea that even if we don't know the answers to questions like the origin of the universe, the origin of life, the nature of consciousness, the nature of right and wrong, whatever those answers are going to be, they're going to be found within the framework of naturalism. So, I think that -- again, it got on the best seller list very briefly. They appear, but once every few months, but not every episode. By the way, all these are hard. Be proud of it, rather than be sort of slightly embarrassed by it. It's an honor. I will not reveal who was invited and who was not invited, but you would be surprised at who was invited and who was not invited, to sort of write this proposal to the NSF for a physics frontier center. -- super pretentious exposition of how the world holds together in the broadest possible sense. 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 just didn't know how you would measure it at the time. So, I was a hot property then, and I was nobody when I applied for my second postdoc. We talked about discovering the cosmic microwave background anisotropies. But the anecdote was, because you asked about becoming a cosmologist, one of the first time I felt like I was on the inside in physics at all, was again from Bill Press, I heard the rumor that COBE had discovered the anisotropies of the microwave background, and it was a secret. I was there. So, I said that, and she goes, "Well, propose that as a book. Carroll, while raised as an Episcopalian,[36] is an atheist, or as he calls it, a "poetic naturalist". I'm a big believer that there's no right way to be a physicist. But apparently there are a few of our faculty who don't think much of my research. They don't frame it in exactly those terms, but when I email David Krakauer, president of SFI, and said, "I'm starting this book project. It's the simplest thing you possibly could do. So, basically, I could choose really what I wanted to write for the next book. Also in 2014, Carroll partook in a debate held by Intelligence Squared, the title of the debate was "Death is Not Final". The world has changed a lot. So, this dream of having a truly interdisciplinary conversation at a high intellectual level, I think, we're getting better at it. Recently he started focusing on issues at the foundations of cosmology, statistical mechanics, quantum mechanics and complexity. And they said, "Sure!" That's why I joined the debate and speech team. They claim that the universe is infinitely old but never reaches thermodynamic equilibrium as entropy increases continuously without limit due to the decreasing matter and energy density attributable to recurrent cosmic inflation. And I could double down on that, and just do whatever research I wanted to do, and I could put even more effort into writing books and things like that. So, I made the point that he should judge me not on my absolute amount of knowledge, but by how far I had come since the days he taught me quantum field theory. To my slight credit, I realized it, and I jumped on it, and I actually collaborated with Brian and his friends in the high-z supernova team on one of his early papers, on measuring what we now call w, the equation of state parameter. What you would guess is the universe is expanding, and how fast it's expanding is related to that amount of density of the universe in a very particular way. I had this email from a woman who said, literally, when she was 12 years old, she was at some event, and she was there with her parents, and they happened to sit next to me at a table, and we talked about particle physics, and she wrote just after she got accepted to the PhD program at Oxford in particle physics, and she said it all started with that conversation. Sometimes I get these little, tiny moments when I can even suggest something to the guest that is useful to them, which makes me tickled a little bit. Some people say that's bad, and people don't want that. Doing as much as you could without the intimidating math. And we started talking, and it was great. You'd need to ask a more specific question, because that's just an overwhelming number of simulations that happened when I got there. I could have probably done the same thing had I had tenure, also. I'm going to do what they do and let the chips fall where they may at this point. I think the departments -- the physics department, the English department, whatever -- they serve an obvious purpose in universities, but they also have obvious disadvantages. And he's like, "Sure." It's the same for a whole bunch of different galaxies. There's also the argument from inflationary cosmology, which Alan pioneered back in 1980-'81, which predicted that the universe would be flat. Fast forward to 2011. Hard to do in practice, but in principle, maybe you could do it. We haven't talked about 30-meter telescopes. Of course, Harvard astronomy, at the time, was the home of the CFA redshift survey -- Margaret Geller and John Huchra. So, they actually asked me as a postdoc to teach the GR course. It just came out of the blue. Everyone knows -- Milgrom said many years ago in the case of dark matter, but everyone knows in the case of dark energy -- that maybe you can modify gravity to get rid of the need for dark matter or dark energy. Well, you parameterize gravitational forces by the curvature of space time, right? At Chicago, you hand over your CV, and you suggest some names for them to ask for letters from. But they did know that I wrote a textbook in general relativity, a graduate-level textbook. Polchinski was there, David Gross arrived, Gary Horowitz, and Andy Strominger was still there at the time. Young people. You can't get a non-tenured job. That is, he accept "physical determinism" as totally underlying our behavior (he . Are you particularly excited about an area of physics where you might yet make fundamental contributions, or are you, again, going back to graduate school, are you still exuberantly all over the place that maybe one of them will stick, or maybe one of them won't? Usually the professor has a year to look for another job. You can challenge them if that seems right. Every little discipline, you will be judged compared to the best people, who do nothing but that discipline. The acceleration due to gravity, of the acceleration of the universe, or whatever. So, it would look like I was important, but clearly, I wasn't that important compared to the real observers. That's not data. You go from high school, you're in a college, it's your first exposure to a whole bunch of new things, you get to pick and choose. Yes, I think so. It's rolling admissions in terms of faculty. "The University of Georgia has been . I chose wrongly again. The astronomy department was great, the physics department was great. So, they just cut and pasted those paragraphs into their paper and made me a coauthor. Coincidentally, Wilson's preferred replacement for Carroll was reportedly Sean Payton, who had recently resigned from his role as the head coach of the New Orleans Saints.Almost a year later . The biggest one was actually -- people worry that I was blogging, and things like that. I ended up taking six semesters and getting a minor in philosophy. But it's worked pretty well for me. Hopefully it'll work out. In fact, no one cited it at the time -- people are catching on now -- but it was on the arrow of time in cosmology and why entropy in the universe is smaller in the past than in the future. That group at MIT was one, and then Joe Silk had a similar group at Berkeley at the same time. Author admin Reading 4 min Views 5 Published by 2022. Well, Sean, you can take solace in the fact that many of your colleagues who work in these same areas, they're world class, and you can be sure that they're working on these problems. If the most obvious fact about the candidate you're bringing forward is they just got denied tenure, and the dean doesn't know who this person is, or the provost, or whatever, they're like, why don't you hire someone who was not denied tenure. I think, both, actually. People always ask, did science fiction have anything to do with it? 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. Right. We were sort of in that donut hole where they made enough to not get substantial financial aid, but not enough to be able to pay for me to go to college. [53][third-party source needed]. I say, "Look, there are things you are interested in. 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. Go longer. Everything is going great. 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. Eventually I figured it out, and honestly, I didn't even really appreciate that going to Villanova would be any different than going to Harvard. Give them plenty of room to play with it and learn it, but I think the math is teachable to undergraduates. But the good news was I got to be at CERN when they announced it. Ed would say, "Alright, you do this, you do that, you do that." It had been founded by Chandrasekhar, so there was some momentum there going. Yeah, no, good. This is December 1997. I don't interact with it that strongly personally. There are, of course, counterexamples, or examples, whichever way you want to put it. The Santa Fe Institute is this unique place. 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'm not someone who thinks there's a lone eccentric genius who's going to be idiosyncratic and overthrow the field. Perhaps you'll continue to do this even after the vaccine is completed and the pandemic is over. In some extent, it didn't. 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. Or, maybe I visited there, but just sort of unofficially. Not any ambition to be comprehensive, or a resource for researchers, or anything like that, for people who wanted to learn it. His article "Does the Universe Need God?" And it has changed my research focus, because the thing that I learned -- the idea that you should really write papers that you care about and also other people care about but combined with the idea that you should care about things that matter in some way other than just the rest of the field matters. When you come up for tenure, the prevailing emotion is one of worry. And I didn't. They're like, what is a theory? He's the best graduate student I've ever had. It was -- I don't know. You get dangerous. And the other thing was honestly just the fact that I showed interest in things other than writing physics research papers. 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. And, you know, in other ways, Einstein, Schrdinger, some of the most wonderful people in the history of physics, Boltsman, were broad and did write things for the public, and cared about philosophy, and things like that. If you've ever heard of the Big Rip, that's created by this phantom energy stuff. So, we wrote a paper. They had no idea that I was doing that, but they knew --. It makes perfect sense that most people are specialists within academia. The COBE satellite that was launched on a pretty shoestring budget at the time, and eventually found the CMB anisotropies, that was the second most complicated thing NASA had ever put in orbit after the Hubble space telescope. Someone said it. That leads to what's called the Big Rip. I like the idea of debate. I taught a couple of courses -- not courses, but like guest lectures when I was in high school. As long as it's about interesting ideas, I'm happy to talk about it. 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. I wonder what that says about your sensibilities as a scientist, and perhaps, some uncovered territory in the way that technology, and the rise of computational power, really is useful to the most important questions that are facing you looking into the future. I don't want them to use their built in laptop microphone, so I send them a microphone. We don't care what you do with it." If there's less matter than that, then space has a negative curvature. We used Wald, and it was tough. They were like, how can you not give it to the Higgs boson book, right? Again, I convinced myself that it wouldn't matter that much. 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. Different people are asking different questions: what do you do? But clearly it is interesting since everyone -- yeah. It's a messy thing. How could I modify R so that it acted normal when space time was curved, but when space time became approximately flat, it changed. Theoretical cosmology at the University of Chicago had never been taught before. Well, you could measure the rate at which the universe was accelerating, and compare that at different eras, and you can parameterize it by what's now called the equation of state parameter w. So, w equaling minus one, for various reasons, means the density of the dark energy is absolutely constant. There's nothing like, back fifteen years ago, we all knew we were going to discover the Higgs boson and gravitational ways. There are dualists, people who think there's the physical world and the non-physical world. Both are okay in their different slots, depending on the needs of the institution at the time, but I think that a lot of times the committees choosing the people don't take this into consideration as much as they should.