Mindscape Ask Me Anything, Sean Carroll | August 2026

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1:01Hello, everyone. Welcome to the August 2026 Ask Me Anything edition of the Mindscape podcast. I'm your host, Sean Carroll. I know the news that is on everyone's mind, and it's certainly on mine. Maybe it's not on yours, but you think it's on mine, and you're correct. But LeBron James, who is in the conversation for one of the best basketball players of all time, has agreed to join the Philadelphia 76ers, who are by acclamation the greatest basketball team of all time, and at least my personal favorites.

1:31So this is big news, and everyone wants to know. There's been several mentions in the AMA questions this month. You know, what do you think about LeBron joining the Sixers? And the answer is, I am thrilled. I think that this is amazing. I think he's basically a perfect fit for the team. I think the team is basically a perfect fit for him. LeBron, you know, is getting up there. He is dead-ass old. There's just no question about that. LeBron is pushing 42, I think he'll be, this season.

2:02But he was super productive last year, playing at an all-star level, and no reason to think that he can't do that again this year. And there's been some moaning out there in the internet corners that I listen to for basketball news and gossip that there's almost too many good players on the Sixers right now. Literally, if all the players that they have, now they also have Jalen Brown, who they acquired in a trade from the Celtics, with Joel Embiid, Tyrese Maxey, Vijay Edgecombe.

2:36In pure talent terms, this is one of the best starting fives in the history of the NBA. Now, pure talent terms don't matter if they don't gel, if they get injured, if their styles get in the way, if there's personality conflicts. There's many things that could go wrong. But for the moment, I'm going to choose to be optimistic. I think that what a lot of people miss is that LeBron, even though he has scored more points than any other NBA basketball player ever, takes some of his greatest joy from being a facilitator and a passer.

3:07When he joined the NBA, he said he wanted to be more like Magic Johnson than Michael Jordan. And that is exactly what the Sixers need. And he plays a position, which was by far the Sixers' weakest position. He'll have multiple great players to pass to on any one night, any one of the starting five can score 30 points. Everyone can take turns, and I see no reason why everything won't be great. But I don't want to bore the people who are listening who are not basketball fans. I just want to say one little philosophical point about this.

3:37I was visiting Santa Fe Institute and talking to Jeffrey West, former Mindscape guest, and I didn't know this, but Jeffrey is a huge football fan in the sense of he's British. Soccer is what we would call it here in the United States. He was following very carefully. England's journey in the World Cup this year, and he kind of had very strong feelings for how they were actually playing better. No, they were playing worse than they were able to, but doing better than they should have just through sort of luck and randomness,

4:08and then their luck ran out in the semifinals when they lost to Argentina. But anyway, so we were bonding about this because, you know, we both agreed, like, people don't know how much of our lives are spent thinking and caring about sports. He's a fan of Tottenham Hotspur. I am not very knowledgeable about football slash soccer, but, and I know nothing about Tottenham Hotspur. I know who they are, but I don't know any of their history or anything like that. But nevertheless, I could feel and appreciate all the emotions that he was expressing

4:38in thinking about how his fandom expressed itself over the years. Look, Jeffrey is getting up there in years himself. We were talking about basketball a little bit. He says, I know nothing about basketball, but I do remember, you know, watching once and seeing this huge guy just dominating and being very impressed with him. And I was trying to guess. I'm like, was it Shaquille O'Neal? And he goes, oh, no, before that. And then someone says, Wilt Chamberlain. Yes, that was it. So that was a while ago, since Wilt retired in the early 70s.

5:09The point is that I didn't need to know details about Tottenham Hotspur to get where Jeffrey was coming from any more than he needed to know details about the Philadelphia 76ers. And we agreed, you know, it's irrational. Maybe irrational is not the word. It's non-rational to love a sports franchise in this way. If you had been born in different circumstances, you would have loved some other sports franchise, and that's fine. But the irrationality or non-rationality

5:40is part of it, I think. This is the place I've come to in thinking about it. When people ask me how I feel about LeBron James joining the Sixers, it could be amazing, right? They could be one of the best NBA teams of all time, or it could all fall apart, as I've already said. But here's the thing. We don't know. None of us is Laplace's demon, right? What LeBron James joining the Philadelphia 76ers represents is hope. It's the prospect of something amazing happening.

6:14You know, when you watch a TV show or watch a movie, you don't know what's going to happen, but someone does. Someone made the movie, right? But when you watch a sporting event, you don't know what is going to happen out there, and that is part of the joy. I think a lot of modern sports fans sort of miss the point of the experience by trying to pretend that they're general managers and coaches rather than just rooting for their teams and hoping for the best. If your team plays in a league where there's only going to be one champion at the end of the year,

6:45most teams' fans are going to end up the season disappointed in some sense. But you're allowed to begin the season very optimistic, and that is how I choose to approach things. So LeBron represents hope to us, hope that the Sixers can finally get over the hump and win one, that Joel Embiid's career will be vindicated, or who knows? We just don't know for sure, but we can root for them. We can take pleasure in the anticipation of victory,

7:18and then we'll have to deal with it if we don't get it. So non-rational or not, I think that the more I think about it, the happier I am that there exists something like sports fandom, and there's different versions of that for different people. That's fine. There's nothing special about sports. But the stakes are low. It doesn't really matter who wins, right? But the emotional investment is very, very high, and that's a good kind of situation to have. Speaking of emotional investments being high, the Ask Me Anything questions

7:49here for the Mindscape podcast are offered up by our Patreon supporters. If you want to be a Patreon supporter, you can join up by coming to patreon.com slash Sean M. Carroll and pledging a little bit of support. And then you get to ask the questions. Once in your life, you get a priority question that I will do my best to answer. And you also get ad-free versions of the podcast, and you get to chat with other Patreon supporters in the Patreon comment section, which is a lot of fun. So I always appreciate that.

8:19Appreciate everyone who listens to Mindscape. Let's go. Anonymous says, My recently five-year-old son is a curious soul and frequently asks me questions about almost everything he sees. One of the common patterns of questioning is,

8:50What is that? Followed by, Why is it that thing? After I answer. I don't want to discourage him by pointing out the category error, so I usually either describe what the thing in question does or how it got there. However, this happens often enough that I wonder if there are any other ways I might be able to answer, to approach this type of question. Do you have any ideas? You know, I don't think that you want to be overly philosophically fastidious when you're talking to five-year-olds. When someone says, Why is something this rather than that,

9:20especially when they're a five-year-old and they haven't understood the basic map of reality, what you want to do is not give the answer that is most technically correct, but rather the answer that is most satisfying the particular itch that they're attempting to scratch by asking the question in the first place. I mean, they might just be being annoying. Kids do that sometimes, right? Like, they just want to keep asking the question. But what is it that would make them happy? You know, why is a tree a tree?

9:54You know, what even possible answer could you get for that? But you could use that as an excuse to talk about the ecosystem and why there are plants and animals and what it means to be that way. Eventually, if you really do have someone who is just pushing you and won't let go, you will bottom out and you just have to say things are like that and everyone eventually learns to put up with that kind of answer. Philip Rissius says, How is the damage on academia by political institutions panned out so far?

10:26Is it still a slow-moving car wreck waiting to happen or are effects becoming visible? The car wreck is not at all slow-moving and the effects are super visible and have been visible for a while now. You know, I hope people understand this. You know, sometimes you have complaints politically or whatever because you think something bad is going to happen, but maybe you can avoid it. This is already happening. There has been absolutely devastating and irreversible damage to science

10:58in the United States and to academia in the United States. And again, it's been happening for two years now. As soon as cuts came in to overhead, as I described in a sort of bonus podcast a year and a half ago or whatever, you know, the government decided that universities were just taking too much money for their own use rather than putting them to the purposes of the grants that were being offered, etc. What that means is that every university

11:30suddenly has a huge budget cut, okay? And that's real and that's happened. And what does that mean? Well, they're not going to fire professors or things like that, but they're going to let other people go. So administrative help throughout the university has been decreased. People retire and don't get replaced. Universities are looking everywhere they can for places to save money, which is not always an encouraging environment to be in. You know, this year I hired a postdoc

12:00through what is usually a fairly standard procedure. I had money to do it and it took forever. We didn't get the official offer letter out until July, even though the offer was made back in December or January. And it's just because our administration has been cut to the bone, okay?

12:20Students and postdocs and faculty members from other countries who ordinarily would look at it as a wonderful opportunity to come to the United States are saying, no, we don't want to do that now because the United States is a disaster area. We don't want to go. We had a search for a new theoretical physicist at Johns Hopkins last year that we went through all of it. I was on the committee to find the person, etc. We got a great candidate canceled at the end because we don't have the money to do that. And it's just getting worse.

12:51People's NSF grants and DOE grants are just being cut or slow-played so that, you know, you are supposed to get money but the money just never appears. So, of course, there is momentum and people are trying to be resilient so people try to keep things going but there's no question. It is absolutely hurting very badly already. And I do think that despite the fact that things are happening right now and it's hurting badly already, the real effects will be very long-lasting.

13:21There's a loss of trust like why would you think that you could keep up a research program here in the United States if every four years you might elect a crazy person who would just cut it to the bone? There's weird political worries that, you know, if you as a faculty member say the wrong things, the government will target you. It's just terrible. The whole wonderful thing that we've built up over a couple hundred years in making the United States a leader in the world of research and scholarship

13:51has been more or less undone and the effects are going to be felt for many, many, many years to come.

13:59Allen, A-L-E-N, says, can you clarify why Boltzmann brain blindness constitutes a genuine problem for cosmology rather than simply an epistemic dead end? It seems to me that from every angle the only rational way to pursue science is to assume that we are ordinary observers produced by the universe's original low-entropy evolution. If we use empirical evidence or logical reasoning to conclude that we are probably Boltzmann brains, that conclusion immediately undermines the reliability of the entire evidentiary and reasoning chain that produced it. The proposition, therefore,

14:31seems cognitively self-defeating. There is no stable standpoint from which we can both accept the Boltzmann brain conclusion and continue treating scientific reasoning as truth tracking. Even if our eventual best model, whether lambda CDM or otherwise, implied that fluctuation observers vastly outnumber ordinary observers, wouldn't the only rational response still be to assume that we are among the ordinary observers? Under the alternative assumption, doing science seems futile by definition. I'm with you there right up until the end. I just don't think

15:02that you're dealing with the problem correctly. You're diagnosing the problem in a perfectly fair way. If we were Boltzmann brains, we would have all these epistemic issues. We would not be able to justify our beliefs in the conclusions we were reaching. That does not mean that if our best conclusion that we reached was a prediction that people like us, literally like us, forget about the brains floating in space, okay? People exactly like you are overwhelmingly likely

15:33to be random fluctuations from an initially higher entropy state. You can't just say, but I'm not one of them. That's not a loud move. That's a God's eye view that you don't have any access to. The best you can do in that situation is to accept what your theory tells you and understand and understand that you have been led to a theory that is self-undermining and you are screwed. There's really nothing you can do. You should, if you're playing fair,

16:04you should take at face value the predictions of your theory. You're not allowed to say, well, I've developed a really good theory. It makes this prediction, but I don't like it, so I'm going to just sort of pretend that I'm not one of the ones who is susceptible to that prediction. Happily, there is a perfectly good way out, which is to develop a better theory. If it were the case that the universe was set up so as to be inevitably self-undermining or unintelligible to human beings,

16:35that would be too bad, right? That would absolutely be a disaster and, you know, we couldn't do science anymore. But there's no reason to think that. There's no reason to think that we have to live in a universe where most people like us are random fluctuations out of the random chaos around us. We can do better. That's what I do. That's what we try to do as scientists. Build models of the universe that are compatible with the data and do not have this problem.

17:05That is the way out. Build cosmologies where Boltzmann brains are not dominating the set of people who are consistent with the data that we have.

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20:02Karmaria says, Do you think that shows like Barry and Breaking Bad are realistic in terms of how far people will go given a set of conditions? Has your research in philosophy, physics, and other fields led you to believe that there is a set of human behaviors that are good versus bad? You know, I don't know about my research, but, you know, I don't, even when I do philosophy, I don't do moral philosophy or psychology. But I, one of the reasons why shows like Barry and Breaking Bad are good and interesting

20:32is that they are entirely realistic. I mean, look at history. Look at the set of people who've done things throughout history. A lot of them have broken bad. A lot of them have done really, really terrible things. And usually it's not like the comic books, right? It's not like they're self-proclaimed supervillains. People don't think of themselves as evil or doing bad. They have justifications for what they're doing. And I think that, I know a lot more people have seen Breaking Bad than seen Barry, but Breaking Bad

21:03is a great example of, you know, the protagonist, Walter White, is bad, okay? Some people, some people root for him, but he is bad. He's also sympathetic. That's one of the brilliant things about the show is that it makes you understand why he would become bad. You understand his motivations. I think that this is what is happening with Barry also. For people who haven't seen it,

21:34Bill Hader, who is most famous as a comedian on Saturday Night Live, started this show which was supposed to mix comedy and drama, okay? And my suspicion, and this is not based on any inside information whatsoever, I'm just guessing that what happened is, you know, they started this show with the idea that it would be kind of a fish-out-of-water comedy show with some dramatic elements where this guy who was a hired assassin, ex-military, hitman for hire, decides he doesn't want

22:04to live that life anymore and he starts taking acting lessons and, you know, moves to Hollywood, okay? There's a lot of rich material you could mine for comedy in there, but I suspect that what happened is they just got interested in the question of but, okay, what would really happen? Like, forget about the comedy. The comedy is still there, but in the later seasons it gets really dark, this show, because the character of Barry, who is brilliantly played by Bill Hader, is very self-justifying,

22:37right? Like, he kills a lot of people and he always thinks he has a good reason to do it. Sometimes he thinks the reason is just he's earning a living, but other times, you know, he's like, well, I had to kill that person, otherwise they would have told on me and would have gone to jail. And, you know, to him, that's a perfectly good justification for what he does and it's fascinating for those reasons. So, I don't think that there is objectively out there in the world criteria by which we judge things to be good or bad, but subjectively in the world of human beings, yeah, there absolutely are

23:07sets of human behaviors that I'm very happy, willing to label good versus bad and both of these shows are examples of sympathetic characters doing really, really bad things. Stephen Slayton says, Star formation 101. We're told that the primordial plasma condensed into hydrogen about 400,000 years ago. Old, sorry, not ago. And also that the iron nucleus is at the bottom of the energy curve. You can get energy by splitting a large nucleus like an atomic bomb

23:38or fusing small ones like a hydrogen bomb, but there's no iron bomb. So why isn't the universe made of iron? Just wait. That's the direction we're moving in, right? You know, it is true. So if you don't think about gravity, don't think about cosmology, just think about atoms and nuclei. What is the lowest energy state that you can take some set of baryons, right? Baryons are the protons and the neutrons that we use to make atomic nuclei.

24:09Their lowest energy state is iron. That's the highest point in the curve of binding energy. The most binding energy, which means the lowest total energy for the nucleus itself. But it takes work to get there, right? Like, I can't just take, I don't know, a jar of hydrogen and smush it together and make iron. It turns out to be harder than you think. We can't even make helium very effectively, right? This is the barrier that we find when we try to do nuclear fusion.

24:39hydrogen as an energy source. We would love to be able to do it. Turns out to be harder than it looks, right? Because there are potential barriers. It's hard to squeeze two protons close enough to fuse to make a deuteron. And that's perfectly consistent with the laws of physics. Just because something is the ultimate state that you will eventually get to doesn't tell you anything about how long it will take to get there. And you have to actually ask about the specific

25:10conditions the universe is in and how the processes go. The universe came out of its early stages almost all hydrogen and helium, at least in terms of the ordinary matter. Forget about the dark matter. It doesn't really matter for this. Now you might seriously ask why the early universe didn't make more heavy elements all the way up to iron. And this is a fascinating story and you know any cosmology student learns about the story of Big Bang nucleosynthesis

25:41which is exactly this story. There's something that you learn about called nuclear statistical equilibrium which says okay not just the fact that iron is the lowest energy state but what about the state at some fixed temperature? What if you just had a box of gas with a completely indestructible material that the box is made out of and I can turn the temperature up to whatever I want? At very high temperatures iron is not the ground state because the iron keeps bumping into other things and dissociating

26:12and you know photons break it apart and so forth. At very very high energies protons and neutrons and electrons are the ground state of that high temperature gas and then as you lower the temperature you can make more and more of these heavy elements and they can become at least temporarily stable but the point is you need time you need time to turn all those light elements into heavier ones and the early universe doesn't give you time by the time the universe is three minutes old

26:42it's become sufficiently dilute that you don't get a lot of collisions between the protons and neutrons and helium atoms enough to make heavier elements than that you make a little bit right you make trace amounts of lithium and beryllium but you don't have nearly enough time the universe just cools off and dilutes away so fast that you don't have time to go all the way to iron if the universe expanded much much more slowly it would have been a different story

27:13Scott Ferris says as LLMs are progressing with their ability to do complex math do you utilize any AI in your personal research if so which ones have you found most useful are there strengths or weaknesses with the LLMs mathematical abilities that you found interesting or surprising I do use LLMs all the time but not to do anything complicated like real math if I want to make a little plot like I did in the recent paper that we had about the cyclic universe you know we had a very well

27:43posed set of equations I just want to plot the solution to the equations okay like it's much easier I could have written some routine in Python or Mathematica to do that it's much faster to ask the LLM to do it and they make very pretty plots out of it right and I can check it it's a short program and it's reliable because I'm not asking it to do anything that's outside it's wheelhouse right when you want an LLM to make a plot for you it's very very helpful to know that you're not trying to do something crazy you're trying to do

28:15something that has definitely sort of seen similar things to in the past but most of my research isn't solving tricky high-level math problems right most of my research is much more conceptual