Sean attached a figure from an old Scientific American article assertingthat sex is not binary, but a spectrum. That is, as an astronomy student, you naturally had to take all kinds of physics classes, but physics majors didn't necessarily have to take all kinds of astronomy classes. 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. If you just have a constant, that's the cosmological constant. Again, stuff that has not been that useful to me, but I just loved it so much, as well as philosophy and literature classes at Harvard. I don't think that was a conversion experience that I needed to have. I was like, okay, you don't have to believe the solar neutrino problem, but absolutely have to believe Big Bang nucleosynthesis. We wrote the paper, and it got published and everything, and it's never been cited. They had no idea that I was doing that, but they knew --. And I think it's Allan Bloom who did The Closing of the American Mind. So, it wasn't until I went to Catholic university that I became an outspoken atheist. None of that at Chicago. Well, and look, it's a very complicated situation, because a lot of it has to do with the current state of theoretical physics. The unhappy result of preferring less candor is the loss we all feel now.". I was on the advanced track, and so forth. It's one thing to do an hour long interview, and Santa Fe is going to play a big role here, because they're very interested in complex systems. But it gives lip service to the ideal of it. So, that combination of freedom to do what I want and being surrounded by the best people convinced me that a research professorship at Caltech was better than a tenure professorship somewhere else. It would have been better for me. I thought maybe I had not maxed out my potential as a job market candidate. They were all graduate students at the time. Sean Michael Carroll (born October 5, 1966) is an American theoretical physicist and philosopher who specializes in quantum mechanics, cosmology, and philosophy of science. I think that's much more the reason why you don't hear these discussions that much. Let's go back to the happier place of science. Then why are you wasting my time? Later on, I wrote another paper that sort of got me my faculty jobs that pointed out that dark energy could have exactly the same effect. I'm not sure of what I'm being asked for. Remember, I applied there to go to undergraduate school there. I don't always succeed. Not to mention, socialization. Not just open science like we can read everybody's papers, but doing science in public. Everyone sort of nods along and puts up with it and waits for the next equation to come on. 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. When I went to Harvard, there were almost zero string theorists there. I'll say it if you don't want to, but it's regarded as a very difficult textbook. He was the one who set me up on interviews for postdocs and told me I need to get my hands dirty a little bit, and do this, and do that. And the most direct way to do that is to say, "Look, you should be a naturalist. 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. When it came time to choose postdocs, when I was a grad student, because, like I said, both particle physics and cosmology were in sort of fallowed times; there were no hot topics that you had to be an expert in to get a postdoc. Certainly, my sound quality has been improving. So, then, I could just go wherever I wanted. The Santa Fe Institute is this unique place. I'm an atheist. It's the time that I would spend, if I were a regular faculty member, on teaching, which is a huge amount of time. So, I did eventually get a postdoc. Even as late as my junior or senior year as undergraduates in college, when everyone knew that I wanted to go to graduate school and be a professor, or whatever, no one had told me that graduate students in physics got their tuition paid for by stipends or research assistantships or whatever. I do try my best to be objective. So, I try to judge what they're good at and tell them what I think the reality is. I wrote a big review article about it. He was born to his father and mother in Philadelphia, Pennsylvania, United States of America. That leads to what's called the Big Rip. Normal stuff, I would say, but getting money was always like, okay, I hope it'll happen. 4. I'll just put them on the internet. What's interesting is something which is in complete violation of your expectation from everything you know about field theory, that in both the case of dark matter and dark energy, if you want to get rid of them in modified gravity, you're modifying them when the curvature of space time becomes small rather than when it becomes large. So, even if it's a graduate-level textbook filled with equations, that is not what they want to see. I think I did not really feel that, honestly. What academia asks of them is exactly what they want to provide. And also, of course, when I'm on with a theoretical physicist, I'm trying to have a conversation at a level that people can access. The other thing, just to go back to this point that students were spoiled in the Harvard astronomy department, your thesis committee didn't just meet to defend your thesis. There's a famous Levittown in Long Island, but there are other Levittowns, including one outside Philadelphia, which is where I grew up. But to shut off everything else I cared about was not worth it to me. I think it's gone by now. Walking the Tenure Tightrope. Thomas Kuhn, Paul Feyerabend, how to scientists make decisions about theories, and so forth? I forced myself to think about leaving academia entirely. 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. There was Cumrun Vafa, one person who was looked upon as a bit of an aberration. So, I'm surrounded by friends who are supported by the Templeton Foundation, and that's fine. So, I would become famous if they actually discovered that. and as an assistant professor at the University of Chicago until 2006 when he was denied tenure. I love it. I've not really studied that literature carefully, but I've read some of it. He began a podcast in 2018 called Mindscape, in which he interviews other experts and intellectuals coming from a variety of disciplines, including "[s]cience, society, philosophy, culture, arts and ideas" in general. Tenure is, "in its ideal sense, an affirmation that confers membership among a community of scholars," Khan wrote. I don't know whether this is -- there's only data point there, but the Higgs boson was the book people thought they wanted, and they liked it. They can't convince their deans to hire you anymore, now that you're damaged goods. Not so they could do it. He said, "As long as I have to do literally nothing. My mom worked as a secretary for U.S. Steel. 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 was hard to figure out what the options were. For every galaxy, the radius is different, but what he noticed was, and this is still a more-or-less true fact that really does demand explanation, and it's a good puzzle. Also in 2014, Carroll partook in a debate held by Intelligence Squared, the title of the debate was "Death is Not Final". It's never true that two different things at the higher level correspond to the same thing at the lower level. I'm very pleasantly surprised that the podcast gets over a hundred thousand listeners ever episode, because we talk about pretty academic stuff. At least, I didn't when I was a graduate student. So, I wrote very short chapters. I asked him, "In graduate school, the Sean Carroll that we know today, is that the same person?" So, I went to a large public school. That was my talk. So, probably, yes, I would still have the podcast even if I'd gone to law school. In his response to critics he has made a number of interesting claims . Some of them are excellent, but it's almost by accident that they appear to be excellent. Sorry about that. I think that it's important to do different things, but for a purpose. 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. When we were collaborating, it was me doing my best to keep up with George. 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. I can do it, and it is fun. They're trying to understand not how science works but what the laws of nature are. And the postdoc committee at Caltech rejected me. 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. Parenthetically, a couple years later, they discovered duality, and field theory, and string theory, and that field came to life, and I wasn't working on that either, if you get the theme here. I'm always amazed by physics and astronomy [thesis] defenses, because it seems like the committee never asks the kinds of questions like, what do you see as your broader contributions to the field? 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. The slot is usually used for people -- let's say you're a researcher who is really an expert at a certain microwave background satellite, but maybe faculty member is not what you want to do, or not what you're quite qualified to do, but you could be a research professor and be hired and paid for by the grant on that satellite. More importantly, the chances that that model correctly represents the real world are very small. Then, you enter graduate school as more or less a fully formed person, and you learn to do science. That was sort of when Mark and I had our most -- actually, I think that was when Mark and I first started working together. So, that was a benefit. 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? That was the first book I wrote that appeared on the New York Times best seller list. First, on the textbook, what was the gap in general relativity that you saw that necessitated a graduate-level textbook? Again, a weird thing you really shouldn't do as a second-year graduate student. Three, tell people about it. 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. That just didn't happen. So, that's physics, but also biology, economics, society, computers, complex systems appear all over the place. This is probably 2000. 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. So, they said, "Here's what we'll do. Yeah, I think that's right. He knew all the molecular physics, and things like that, that I would never know. If you're positively curved, you become more and more positively curved, and eventually you re-collapse. It might be a good idea that is promising in the moment and doesn't pan out.