Sean Carroll's Mindscape: Science, Society, Philosophy, Culture, Arts, and Ideas - AMA | November 2022

Episode Date: November 7, 2022

Welcome to the November 2022 Ask Me Anything episode of Mindscape! These monthly excursions are funded by Patreon supporters (who are also the ones asking the questions). We take questions asked by Patreons, whittle them down to a more manageable number — based primarily on whether I have anything interesting to say about them, not whether the questions themselves are good — and sometimes group them together if they are about a similar topic. Enjoy! Support Mindscape on Patreon.

Hello, everyone. Welcome to the November 22, Ask Me Anything Edition of the Mindscape podcast. I'm your host, Sean Carroll. So I don't know what's going on in your infosphere these days, but in the corners where I hang out, people are kind of obsessed with the idea of what's happening to Twitter, with Elon Musk buying it. I'm very active on Twitter, pretty active, you know, a couple of tweets a day, maybe on average. Not even every day do I do it. I know there's some people who do dozens or hundreds a day. I'm not in that super level, but it's a valuable to. You know, a couple of tweets a day. I'm not in that super level. But it's a valuable. to me, Twitter. It's valuable to a lot of people who are journalists and writers, especially. I've met friends on Twitter. It's an important thing. It's also a bit of a mess, right? It's completely unmoderated. I don't, it's not completely unmoderated. That's not true, but it's largely unmoderated. I'm not thinking about hate speech and things like that. I'm thinking about just dumb, goofy comments that people leave. Anyone can come in to your Twitter thread and say something, which doesn't always lead to the best conversations. So I've always thought of Twitter. as extremely useful, but useful not for debating deep issues, but for pointing out interesting things,

making a wry comment or a joke, having some fun. Sharing pointers to the rest of the world is the most important thing that Twitter does. And people complain that it's not a better discussion for them, and it was just never meant for that in my mind. But anyway, with Elon buying it, people are worried that it's going to change somehow, and I honestly don't know whether it will or not. I think it certainly will change somehow. I don't know whether it will be dramatic or whether we will, you know, a year from now left that we were all worried about it. But it just reminds me that there's a certain effemorality to these kinds of things. There's a lot of people who are saying, well, I'm leaving Twitter. I'm going to Mastodon or something like that. And it could very well

happen. There's nothing keeping everyone using Twitter all the time. There's certainly been other social media sites or other things on the internet that people have left. I've basically left Facebook years ago, and I didn't mind that at all. You know, there's some sadness because I don't get to see pictures of my friends or reminders of their birthdays and so forth, but you move on and you find other things. So Twitter could die. And again, regardless of your feelings about whether Elon will bring that about, it's a reminder that these things that become very important don't last forever. And that in turn is a reminder of the fact that we are living in a time in history where we're really not.

nowhere near equilibrium, right? Things are changing very, very rapidly. And that makes it very, very hard to predict the future because it's always hard, but especially hard because today is different than yesterday. And it's very hard to extrapolate or think that anything about the current state is typical or permanent or anything like that. And it's hard to wrap our minds around that. The human brain is just not quite built for coping with changes on such a grand scale.

on such a rapid time scale and thinking about what they will mean for timescales beyond our actual human lives. So I wanted to point to that, and I remembered that there was a question in today's AMA that actually got to this. So I'm going to do something I don't usually do, which is to ask the question here in the intro, and then we'll move on. But Johann Falk says, I can't get rid of the feeling that we're living in a time when a lot is at stake. Like what we do now has huge implications for the future of humanity. I'm thinking of global warming, AI, increasing weak against them mentality, China becoming the next new superpower, things like that. This gives me some anxiety, but also makes me want to do things that help us move in the right direction, whatever that is. So, number one, do you think that we're at some kind of crucial point in history?

Number two, do you think that most people throughout history have felt that they're at some kind of crucial point? And number three, do you have any thoughts on how such a feeling can be harnessed into something good instead of mostly feeling despair? Well, on the third one, the feeling good, I'm not so sure that I have any good thoughts. I think that it can. Different people will react differently to this feeling that things are at a crisis point or at an inflection point or something like that. Some people will be energized by that, leap into the fray and try to make things better. Some people will be overwhelmed by it and retreat and try to find a safe place. And I can't criticize either way. I think that's a difficult question that individuals are going to approach differently. I do have opinions about the first two versions of the question. Do I think that we're at some kind of crucial point in history? I would say yes and no. Well, actually, let me group that together with the second one, which is do you think that most people throughout history

have felt that they're at some kind of crucial point? You know, maybe they have, but I would argue that there is something different about the present time. For two reasons. One is because, like I just said, things are changing rapidly. You know, think about just the recent podcast with Will McCaskill or Brad DeLong, really impressing upon us the rapidity of rates of change, and we've had plenty of podcasts in the past few years

that make this point in one way or the other. But the other point is that we're more powerful than we used to be. You know, the physical world is full of tremendously large and potentially destructive or constructive energies, and technology has given us the ability to harness some of those energies in ways that we haven't before. Part of this is as simple as we're much more consistent, If you're on Twitter, it's much easier to know what is going on in Iran at an up-the-date

minute-by-minute basis than it would have been back in the day just a few decades ago, right? But another part of it is that we can do tremendous damage to the planet, whether it's nuclear war or climate change or potential biological hazards one way or another, right? Whether or not you are of the belief that the COVID-19 virus had something to do with testing in a when it originated, there's no question that something like that could happen, that human beings could engineer something that could be way more devastating than COVID-19 has been. So I think we have a lot more leverage now over the whole globe than we ever used to. And so I think we are justified in thinking of our current point in time as a crucial point. Now, having said that,

it might seem much less crucial than a point 100 years from now seems once we get to a hundred years from now because presumably our ability to affect the world is just going to go up. But certainly compared to what was going on 500 years ago, you can easily imagine human beings changing our future history in a dramatic way now compared to 500 years ago or 5,000 years ago or whatever. So I do think it's right to take this seriously. You know, in a very, very localized sense, for those of you here in the U.S., you know that we're right next to our, election day, midterm elections. I go on all the time here about democracy and how democracy is under threat and how people don't really appreciate it. And one of the ways it's under threat is that there's a

lot of people on the ballot, even though there's not a presidential race. There's a lot of races for things like secretary of state of some individual state, the person who is in charge of counting the ballots and sending the results forward to Congress or to whatever. So a lot of the mess that we had two years ago was eventually brought up short by good-hearted bureaucrats, good-hearted people in positions of responsibility saying, no, we are not going to let this election result be overturned. If the election results this week go a certain way, that might no longer be the case two years from now. And the United States is one of the longest operating, continuously operating democracies in the world right now. There's no reason why that has to keep going, right? So that's just yet another way in which things can change very dramatically.

So I think it's perfectly legit to think that we are in a historically crucial time. Now, what are we going to do about it? Well, I think there's a bunch of things to do about it. None of them, you know, whenever you say, what are we going to do about it, the question is, who's this we we're talking about. I mean, like literally you and me, we're not going to do that much. You know, I can come on my podcast and complain about threats to democracy or biological terrorism or whatever. And the world is not going to change that much because of my thoughts on that being spread throughout the various podcast apps. But collectively, we could do a lot. You know, the thing that is most depressing to me about the democracy side of things is that democracy isn't that.

popular, you know? I mean, this is literally true in the sense that political operators who are doing polling for candidates are saying, you know, what are the big themes that would resonate with you this election season? And safeguarding democracy is always near the bottom for both Democrats and Republicans. And it's in a more abstract way if you ask people about, you know, would it be better if we just had one really good person in charge rather than this messy having people vote and have their say thing, there's a lot of people who would just rather have one competent person in charge. Deep down, democracy is not that popular, and it's almost a miracle. It's lasted this long. So what can we do about that? You know, education. You know, we take a lot of

things for granted. When I grew up, you know, democracy was just a good thing. We knew that was a good thing, and we didn't really dig that deeply into it. You know, look, I'm always, I'm always afraid when someone says, what should we do about it, that I'm just going to say, we should do all the things I like doing. That's generally the way that people go. But one of the things I like doing is being careful about ideas, digging into them very, very carefully. You know, on Twitter, I pointed out that free speech, the phrase free speech is being used as a cudgel on this side and that side and whatever. And what it does is it just dumbs down the discourse. Free speech is crucially important. but it's also not simple. It's complicated. And you can listen to various podcasts I've done. Teresa Bejohn is probably the most on point here. But we all agree when push comes to shove that certain kind of speech should not just be spread all over the place and certain kinds should be unfettered. And drawing the line is very difficult. And understanding the philosophical justifications for there being a line and for there being a value to free speech,

it's all very difficult and nuanced. And so I think we should not take it for granted. I should think we should talk about it and think about it and decide why we think this is such a big idea. If we had a better idea why we thought the free speech was so important, which I do, we do a better job of understanding how to protect it in ways that are compatible with other values that we would also like to protect. There's no absolutism here. There's many values that we care about, and we want to balance them off against each other, and that's hard and requires thinking.

So I don't know, Johan, if that's a helpful answer. or not, but I think that each of us individually can take the responsibility to be a little bit less simplistic, be a little bit less glib. You know, I'm always going back to the podcast they did with T. Wen, who was a really, really, that was a very influential podcast for me, where he points out the seductiveness of simplicity and clarity and gamification and how that leads into conspiracy theories and things like that. But even if you're not in a cult or a conspiracy theory, everyone wants simplicity. They want clarity. And the world doesn't always provide it. And values like free speech versus other values is a situation where it's not simple. And you have to embrace that and honor that.

But then again, I'm just saying that people should be more like me, which is sort of a cheap and easy thing to do. So anyway, I'm not in charge. No one is putting me in charge of Twitter or nuclear war or climate change or anything. like that. But at least we can keep the conversation going, maybe make everyone's thoughts about these issues a little bit more clear and helpful and do our little tiny part in that way. With that, quasi-crypto-optimistic note, let's go. The Cyber Monk says, I'm currently reading Volume 1 of the biggest ideas in the universe. Good for you, Cyber Monk. I hope everyone is out there reading the book. You know, it's November. So there's a whole bunch of gift-giving oriented holidays coming up. The biggest ideas in the universe makes a great gift for anyone in your

family. So anyway, the question continues. That was my little editorial comment. I borrowed the e-book from my local public library, which is how I get practically all the books I read. As a software engineer, I easily make enough money to buy them instead. Assuming that would be financially favorable to the author, do I have an obligation to do so. More generally, can one be so well off that one has an obligation to stop using certain public goods or to provide additional support above and beyond what is otherwise expected of a good citizen. So, you know, as an author, I often joke that what I really care about is not people reading my books, but just people buying my books. That's what helps. But guess what? It is a joke. I'm just kidding. I hope that

comes through very clearly. I think it is completely fine with me if you or anyone else reads the book at public libraries. I'm a huge fan. A public library. I'm a huge fan. A public. public libraries, my initial inspiration to fall in love with science came from hanging out of my own local public library. So by doing that in some way, you're supporting. I mean, maybe even better if you, like, turned it in late, so you could pay a little late fine. And in that way, give a little cash to your local public library. I appreciate the inclination here that you're sort of pointing to, you know, are you doing the best good for the world by getting an e-book from the local public library. And maybe arguably not. You know, again, I'm also someone who makes enough money. I have a job,

a full-time job. I'm pretty comfortable in that way. I like money. I like making more money, and I do things to make more money, and those things incentivize me doing things that make other people happy. But I'm not, you know, struggling near the poverty line or anything like that. So among all of the authors who you could support by buying their books, I should be low on the priority list. If you are someone, I think, who is living comfortably enough that you can, in some sense, afford to give a little bit more of your income than is absolutely necessary, then I think that's a good thing to do. I don't think you're under the obligation to not use the public library, but maybe the money you would have spent on a book, give to some charity or something like that, give to some worthy cause. You know, we've talked about that also on the podcast. And I have, I think at the beginning of next month's AMA, I'll do a little update on the state of we had a, if you remember back, we had, when Joshua Green was on the podcast, he promised to give a sort of matching donation kind of thing to Mindscape listeners who donated to giving multiplier.

And that actually worked out really, really well. So I'll have some good news to share with the community there. So something like that. I'm not going to judge people on whether or not. not they give to the charities that I think they should be giving to. I think that we're all trying our best here. If you want to give to your local puppy shelter, that's perfectly also okay with me. Brandon Wheeler says, has anything discovered by the James Webb Space Telescope altered your credence on physics fundamentals? So no, and my credence is that is extremely unlikely that anything

discovered by the James Webb Space Telescope will alter my credence on physics fundamentals. That's just not what the telescope was designed to try to do. You know, when you look at the universe in a new way, you can always be surprised and we frequently are surprised. But the kinds of things that Webb is looking at, whether it's early galaxy formation or searching for evidence, you know, looking at atmospheres of exoplanets or something like that, none of these are going to change physics fundamentals. There's other kinds of science that we're going to learn about. But that's okay. Just because something is big and exciting doesn't mean it's going to give us new information about the fundamental laws of physics.

I'm going to group two questions together. One is by John B. Wyman, who says, Do you think it is possible in principle for the human brain to discover the theory of everything? I think not because the brain is part of the theory. It's like the so-called paradox, does the set of all sets contain itself? And then Tim Giannizos says, do you agree with Thomas Kuhn that there will never be, a final or definitive scientific account of nature. He gives the analogy that scientific theories are like organisms and evolution. There is not a final organism that evolution is driving toward. He

argues similarly that there is not a terminal scientific paradigm, but simply those which better allow us to frame certain puzzles. So they're not the same question. Tim is asking, do you think there is a definitive final account theory of everything, if you want to put it that way? And John is asking, do you think that we could ever find it if it were there, I presume? And so I do think that there is a theory of everything because there's the universe. The universe exists. There is something that the universe does. And whatever that is, there's a description of that that would be the theory of everything. That's it. You know, I see zero reason to doubt that. I think it'd be much, much harder to imagine sort of a metaphysical stance in which you literally could not

frame or describe what the universe does with perfect accuracy than one in which you can, you can, we're just not there yet. The fact that we're not there yet is the least surprising thing in the world. The surprising thing is how much progress we've made toward it. So I absolutely think that there is some final definitive scientific account of nature. Do I think that the human brain can discover it? There, maybe, maybe not, but I would, if I were forced to, I would lean toward probably. And I don't find, I get the worry that you say, you know, the brain is the part of the theory, therefore we're trying to describe it. But that's a little bit, off the mark here in terms of what we're trying to do here, because a theory of everything is not,

or a scientific theory of everything, is not supposed to be a complete and precise specification of the world. It's supposed to be a complete specification of the patterns, the laws that the world obeys. So when I say F equals M.A. Force equals mass times acceleration by I'm Isaac Newton. That is a pattern that is obeyed by every planet in the solar system and every star in the galaxy, etc. I don't need to rediscover it or restate it every time. That's the great thing about the laws of physics. That's something I dwell upon at great length in the biggest ideas in the universe, the universality of these laws.

So we would think that the human brain obeys the theory of everything, whatever it is, but that's no obstacle at all to the human brain discovering it. Moshe Fader says Ligo's success in detecting gravity waves was one of the great physics achievements of our lifetime. So I understand that Ligo will now be followed by the LESA project. It will employ three spacecraft orbiting the sun in an equilateral triangle formation,

with sides about 1.5 million miles long. But I'm unclear how Lisa will work. Surely it can't be by the subtle length variation in laser beams used by Ligo. Can you explain the method they'll be using? Well, I can explain it at the level of a theoretical physicist, which is not very deep. You know, there's an enormous amount of technology, delicate, highly advanced design development going on in Lisa that this is a project that is years in the future, not one that's going to happen anytime soon, but it will be a great way to look for gravitational waves in a completely different wavelength regime than LIGO is able to do. But the short answer is it is the same thing that LIGO does.

Because LIGO doesn't put down a meter stick and then compare the length of those meter sticks to the time it takes light to travel or anything like that. What LIGO is doing is firing lasers in two different directions, firing them in one direction and then another perpendicular direction, and then tuning it in such a way so that if there's no gravitational wave passing by, the two returning laser beams, interfere with each other. So this is a feature about waves, right, where you can have one wave and another wave, and then you combine them, and you get zero wave, at least at a particular point in space, because where one wave is going up, the other wave's going down, and vice versa. And what that means,

what that technique means, is that you don't even really need to know the actual distance that the light beam travels to a great precision, because all you're looking for are slight variations of that distance. Because if the distance varies in one direction versus the other direction, that complete perfect cancellation of the laser beams will go out of whack a little bit.

And that's exactly what LIGO looks for. That's also basically, roughly speaking, what Lisa will do. You have three spacecraft, and you're bouncing from one of them. You're bouncing lasers at one and the other one, and you're bouncing them back.

And then you're trying to look for that sort of interferometry. interferometry, the interference of the laser beams, right? So LIGO stands for laser interferometer gravitational wave observatory. Lisa stands for Laser Interferometer Space Array. I don't know what the A stands for, to be honest. But the point is they're both interferometers using lasers. That's why they both have L-I in them.

So it's basically the same idea. Jacob Jongsma says, Would you be surprised if a new physical theory with a similar impact as relativity or quantum mechanics turns up? Well, that's a very good question, actually, because it depends precisely on what you mean by surprised. In the long term, I would be not at all surprised that there lurks out there a better theory than either relativity or quantum mechanics that will be similarly revolutionary. But in the short term, if, you know, in my lifetime, that's what I mean by the short term, I would be pretty surprised. And the reason is basically just that relativity in quantum mechanics do really well, right? There's no like lingering anomalies or anything like that.

There are puzzles. There's the puzzle of the origin of the universe. There's the puzzle of the cosmontical constant value, the hierarchy problem in quantum mechanics, in the Electro Week theory of particle physics and so forth. There's little puzzles and we need better physics to account for them. There's no really strong evidence that the better physics we need to account for them is completely new and outside the realm of relativity and quantum mechanics. It might be.

But that's a different situation than we had, circa 1900, where we had things like the structure of the atom and black body radiation and so forth were just strictly incompatible with what we thought we knew about classical mechanics. And so that led to a revolution. Maxwell's equations and Newton's equations for gravity were strictly incompatible, and so relativity had to be invented. So usually the way that physics or other sciences actually make progress is by trying to explain observational or experimental anomalies. And right now, in fundamental physics, we don't know. of that many such anomalies. I mean, you can say, well, there's dark matter. Sure, but it's so easy

to explain dark matter within the current paradigm. We don't know what the right explanation is, but that's very different than saying we don't have any way of explaining it. So I think that if there is a better theory, it might take a while to figure it out, but I'm willing to be surprised and would certainly be very happy if I were. Sandro Stuckey says, at the beginning of the latest Mindscape episode, Barry Lower credits from Eternity to Hear, as one, of the two books that introduced philosophers to the idea that statistical mechanics is at the root of all the special sciences, causality, and the arrow of time. When you wrote that book, did you hope to get philosophers thinking about this connection? Did you already think of yourself as a natural philosopher back then? So Barry did say that, and, you know, part of it maybe is him being polite. I don't want to know, I don't want to sort of speculate as to exactly how influential my book was in the philosophy community. Barry liked it. He's one person. But whether or not that's true, I did certainly have in mind addressing questions that are of interest to both physicists and philosophers. That was already true.

In fact, the arrow of time was basically what got me into foundations of physics and natural philosophy. I liked philosophy from back when I was an undergraduate in college, but I liked moral and political philosophy. That's what I actually studied. The philosophy of science stuff was too much about, you know, theory, change, and methodology. which was interesting, but not anything I wanted to do for a living. When I started thinking about inflation and the Arrow of Time and Roger Penrose's critiques of inflation and things like that, and I wrote my paper with Jennifer Chen about the Arrow of Time,

that's the first time when I was really introduced to the whole community of people working on foundations of physics in a serious way, most of whom are philosophers, but some of whom are absolutely physicists. So it's absolutely intentional. that the book that I wrote was one that addresses issues that are of common interest to physicists and philosophers. I'm glad that some of them read it and got something out of it. Kathy Seeger says, in the October AMA, you answered a question regarding societal problems. You mentioned, among other things, social injustice, and how this could lead to less faith in democracy.

Following up on that, I think it's a huge flaw in the U.S. system to link health care, child care, and college university education, to one's financial possibilities. And I don't think this how could eventually, I don't see how this could eventually change because of the aim for freedom with very low involvement of the state in people's personal lives and the economy. How is it that the American way of life is such a strong narrative that so many U.S. people are willing to accept the aforementioned circumstances, although so many inequalities are created? You know, to the actual question you were asking, Kathy, I don't know. I don't know how it is that so many people are willing to accept this. So the question being begged here is, could we change the U.S. system without too much trouble

in ways that would be much more equitable to people in terms of health care, child care, university education, et cetera? It seems like the answer to that is obviously yes. You know, the idea that your health insurance is tied to your employment status is just bizarre. And it is a big part of why the United States has similar health care outcomes to other developed countries, but spends twice as much money per person as other developed countries do, because we just have a wildly inefficient system. And also, I think, although this is a tougher cell, I do think that it's wildly unfair that the education you get is so dependent on the income of your parents, where you were born, things like that. It would be very, very hard to justify any of that from a well-balanced

moral perspective, right? I mean, you're a baby and you're going to start going to school someday, but why should you get wildly different educational circumstances depending on who your parents are? It's kind of hard to come up with a justification for that. And so I don't think it would be very hard to change. I mean, but it would be, so it's very easy to imagine changes, let's put it that way, that would make things better. Not perfect. There's always, there's always imperfections in the system, but it's sort of, there's like obvious room for improvement, right? But there's also huge amounts of resistance to improvement in that way. And some of it is a little bit sensible because I do think that when it comes to public policy, one should be conservative.

in the old school lowercase C sense, that if we have a system that works pretty well, there is sort of reluctance to change it dramatically because we know our system works pretty well. Maybe the new system will work better, but maybe it will have unintended consequences we don't know about. So I think a tie goes to the present system

in those kinds of circumstances. But like I said, I don't think that this is a very difficult change to make. So I don't think that's the reason why people are reluctant to make it. I do think that part of exactly what you said, there is sort of a resistance to let the government control too much of the flow of money through the country's economy. Anyone who knows anything about the actual economy knows that an enormous amount of money in the United States flows through the government one way or the other already. So that doesn't seem like a very legitimate worry to me.

I think that ultimately it's a sort of psychological slash political problem or state of affairs. Let's put it in that more value neutral term. There's a certain image that people have that may or may not be accurate of what government is and what government's supposed to do. There are other images that people have about what it means to be fair and what it means to be just. And like I said, you know, we don't always think these things through very logically. We don't spend a lot of time educating ourselves about them. But I don't know why it's so different in the United States than in other developed countries. Other developed countries have their own problems, of course, and the United States has its own good things about it.

You know, the higher education in the United States, even though it's super duper expensive and that's going to be a crisis, the research structures that it supports are the best in the world by a pretty large margin. And I don't think that's because our health care system is so screwed up. But I'm just saying that I'm not here just to bash the U.S. up and down, I do think that there's some specific ways in which you could obviously better, and I'm not completely sure why everyone doesn't agree with me about that. The winning ticket says, if I understand correctly, Einstein learned about Riemannian geometry from a friend whilst looking for mathematics to aid his general relativity quest.

Is this a common practice, i.e. a physicist has an idea and seeks out mathematical friends, colleagues, or literature, for unfamiliar maths to interrogate their idea further. Could you conceive of a time when you may be writing out ideas for a paper where an AI program could suggest relevant mathematical theories? So I think that you sneaked in two questions there, but that's okay, because they're very related and good questions. Yes, it is a completely common thing to seek out help with math problems. You know, I literally, as I'm recording this, I gave a colloquium, my first physics colloquium at Johns Hopkins at my new university. and I mentioned to them that in some of our work on emergent space time, we needed to use something called the radon transform. The radon transform is a mathematical technique that is actually closely related to what you do in a CAT scan.

When you're looking for an image of your brain, you basically integrate along some slice. You don't literally slice it, but along some plane passing through your brain. And if you do that for many, many different planes, you can reconstruct the whole three-dimensional image. We do a similar thing for space time. I didn't know anything about radon transforms when we started doing this. So yeah, we had to look it up. We had to figure out how to do it. It's great when you can just ask a colleague about it.

Usually you're going to start with Wikipedia or Quora or something like that. Or maybe if you're lucky enough, you have the right textbook on your shelves. Can we imagine a day when it's AI? Sure, absolutely. I think that for the conceivable future, I would imagine treating AI in a way that I, very similar to how I treat Wikipedia. Namely, it's not the definitive answer. I wouldn't trust it.

I use Wikipedia all the time. And sometimes non-academics are sort of shocked. Like, why do professors use Wikipedia? It's so unreliable. Well, you don't rely on it. That's the answer. You use it to find a pointer to somewhere else. Or, you know, if you just see a formula

that you can redraw it for yourself, that's fine. I think AI is exactly the same way in its current incarnations. I would not trust it to do a calculation, but if it laid out a calculation, I could certainly check it, right? So I'm very, I do think that AI is capable of doing things like that that will change how theoretical and experimental, for that matter, physics gets done in ways that are interesting and hard to predict.

Herb Berkowitz says, when the term spin is used in relation to an elementary particle, does it mean spin in the same sense as a planet or a baseball. Does the particle turn on an axis or create centrifugal force? So this is a subtle question. It is spin. You will read in textbooks on quantum field theory, etc., that it is, that the spin of an elementary particle is not really anything spinning. But I don't think that's quite right. And my former collaborator, Charles Siebens, who is at Caltech in the philosophy department, has done a lot of work on the quantum field theory of spin in exactly this context. The reason why they say it, it's not, you know, they just, you know, made it up and were wrong. It's kind of implicit in the way that you ask the question, right? Does the particle turn on an axis? The reality is there's no particles. Particles are a convenient way of talking about certain things that we observe when we measure quantum fields in the right way. So the reason why in textbooks, they'll say it's not really a little spinning particle is because

it's not really a little spinning particle, but it is a field with angular momentum. Fields can have angular momentum. And that's why the angular momentum that is contained in what we call particle spin is part of the overall conserved angular momentum for a larger system. So it's not that there's a little dot or a little baseball that is spinning. It's the field that has angular momentum. And then when you quantize it and look at it, it's a certain quantum amount that is what we think of as elementary particle spin. Okay, two questions, grouping together. Dom says, NERD's theorem says time symmetry leads to conservation of energy. However, in general relativity, energy is not conserved.

Is it therefore the case that general relativity is necessarily time asymmetric? And Jim Watson says there are various conserved quantities, energy, momentum, angular, charge, etc. And it is explained that these quantities aren't really conserved under certain conditions or properties of the universe, e.g. in an expanding universe, conservation of energy doesn't hold. What would be the properties or conditions of the universe if the conservation of momentum or the conservation of charge or other conserved quantities didn't hold.

So these are tricky questions, but good ones. The energy one is the easiest one to explain. So it's not that general relativity is necessarily time asymmetric. It's that the specific solution to the equations of general relativity corresponding to our real world in cosmology is time asymmetric. It's an expanding universe. things used to be closer together and denser, things will in the future be further apart and lower density. That's the time asymmetry that leads to energy not being conserved.

In general relativity, if the background, if the space-time metric is completely stationary, as we say, that is to say, if it's completely the same from moment to moment, then energy would be conserved. But that's not true in the expanding universe. For Jim's question about angular momentum and charge and things like that, you can always find places where you have violated this symmetry. That's pretty easy to do. This is the whole subject, roughly speaking, of spontaneous symmetry breaking. People will argue over what exactly the definition of spontaneous symmetry breaking is, but let's put it this way. The Higgs field, which has a non-zero value in empty space, and therefore breaks the symmetry of the electric week theory, leads to a

non-conservation of charge of the electric week part of the charge, essentially because that background field can absorb the charge or change it in some ways, depending on what interactions are going on within it. Likewise, with the expanding universe, we say energy is not conserved, but it's not that all hell has broken loose. There is a very definite equation, sometimes called the equation, the covariant equation for conservation of energy, which relates what space time is doing to what the energy is doing. So if space time is stationary, energy is conserved, if space time, space time is not stationary, you can say exactly what the energy is doing. You can say exactly how it changes. Likewise for these other things. For conservation of momentum, for example, conservation of momentum,

comes from the fact that the universe is spatially translationally invariant. It's the same from place to place. So if you live on a hill, that is not true. If you live on a hill, then there's a direction going down and direction going up. And guess what? If you put a ball on the hill, its momentum will not be conserved, right? Now, there's a whole momentum that it's conserved for the ball and the earth that it's on, et cetera, and indeed, that's because that whole thing is embedded in a situation

where there is no gradient in space and everything is spatially translational invariant. But if you just zoom in on the ball on the hill, its momentum is not conserved because it's in an environment where spatial translations are not asymmetry. Michael says, you mentioned in a previous AMA that among your idea,

of what makes someone an intellectual is someone who is in pursuit of trying to find truth, pointing out that politicians may be intelligent but not intellectuals, since as politicians they're not trying to figure out what is true and so forth. I'm wondering if living in search of truth is what makes someone an intellectual, does that mean QAnon conspiracy theorists are intellectuals? Since it seems that as erroneous as they are, they seem to believe they're in some pursuit, some sort of pursuit of the truth, uncovering what is really true, et cetera.

Or is it more the case that, using the scientific means, method in the search for what is true is what makes someone an intellectual. I think this is a good slash fair question because I think I was a little too simplistic when I talked about what makes someone intellectual for exactly the point, the reasons that you are indicating here. So, but also I think that defining words can be a little bit tedious, right? So it's not that there is some correct notion out there that is called what it means to be an intellectual and it is our job as scientist to find it. We are defining the word to be what we want it to be. So I think for things like this, there's two ways to go. One is you can try to restrict your definition of intellectual to someone

who finds truth using certain techniques or methodologies. For example, you would want them to be fallibilistic, right? You would want them to be capable of understanding when they've made a mistake and therefore fixing the mistake. You might demand that as part of your definition of what it means to be intellectual. Not necessarily the scientific method. We would want, you know, logicians and mathematicians to be intellectuals, even though they don't use the scientific method, but you do want to be able to understand that you've made a mistake. And maybe even more importantly, but less obviously or less quantifiably, to me, what would be important is that you are, I want to say, sincere in your search for truth. So it's true that conspiracy theorists,

think they have the truth. But they're not especially open-minded about looking for reasons to change their minds. They're not especially careful or thorough or honest in trying to make sure that their worldview is holding together the right way. So I do think that's a crucially important part of being an intellectual, understanding that we don't have the final answers, that if new data comes in, we have to change our minds, things like that. On the other hand, And it would be perfectly okay with me if you just said, sure, they are intellectuals. They're just not very good at it. I think we can agree they're not very good at it.

And I don't really think that it makes much of a difference which of those two directions we go for our definition. You know, back in the early days of the blogosphere in the early 2000s, when there's a lot of debate in the science blogosphere about creationism versus natural selection and evolution. and a very common move that is still made today was to say the creationists aren't science because it's not falsifiable or because they are not naturalistic or whatever. I always thought that was a mistake. I was perfectly happy to say that they're doing science.

They're just doing it badly. You know, they have a hypothesis. It's just obviously refuted by the data. I think that it's okay to admit that. You know, a lot of people want to sort of win a battle by making sure the rules are delineated very, very carefully so that their opponent is not fair, is not included in the game, you know? Sometimes you just got to play the game.

You just got to say, like, the Q&ON person, yeah, okay, you're searching for truth, but who are you bad at it? Have you done a terrible job? And if you're upset that there's no arbiter of truth, no court of final deciding for what is true and what is not true, welcome to reality. That's just how things are. We have to be able to accept the fact that those of us who do work in good faith and understand that we can make mistakes are going to have to do our best in the face of other

people who think they have all the answers figured out and are not going to change their minds about it. I mean, I've told the story before, maybe even recently, I hated my retell stories. But when you talk on the podcast for a long time, you're going to end up retelling the stories. But there is a famous story of a woman who was a new story. age spiritualist, and, you know, she would talk to her friends who were, you know, sciencey or whatever, or skeptics, and she would explain. But then what she eventually sort of converted or deconverted, whatever way you want to put it, she went to being a complete skeptic from being

a new age person. And the thing that was the crystallizing moment for her was when she would ask certain kinds of questions, deep questions, about why is there a universe at all, what happened at the beginning or whatever. There are some questions. It wasn't that hard. to formulate for which the scientists or the skeptics would say, I don't know. And her new age friends would always have an answer. They thought they could answer every single possible question. If you think you can answer every single possible question, that's not a sign you're super smart. That's a sign you might have gone wrong somewhere, right? That's a sign that you might be oversimplifying things a wee bit. And I think that's an important tool to use to remember as we

try to do our best, all of us, to get more truth in our lives. Anthony Rubbo says, In the last AMA, you expressed disinterest in the explanatory differences between your notion of many worlds and that of David Deutsch's. You were really just content with everyone agreeing on the math. It was a bit startling. It felt like, in something deeply hidden, you were championing human-friendly explanations and analogs, and did so in several instances. Has the zeal for uncovering greater descriptive methods around many worlds truly waned? Was it just an off day?

or have I mischaracterized? Well, it could be my fault for expressing things badly, but I think at the end of the day, you have mischaracterized what I was trying to say. I mean, I'm certainly never just content with everyone agreeing on the math. But I think that when it comes to physics in many ways or science more broadly,

there are some ways of talking about the underlying system that are either right or wrong, and there are some that are optional, right? So, I mean, a classic example that everyone is going to agree on, I can talk about the box of gas as a fluid with a temperature and a pressure and a density, or I can talk about it as a collection of molecules with positions and momentum,

two different ways of talking about the same thing. That's the kind of distinction that is between how we divide up the world in many worlds. In many worlds, the common thing that everyone agrees on is there is a wave function, a quantum state of the universe, and that quantum state evolves always and entirely by obeying the Schrodinger equation. Okay. That's the theory. That's what you have to agree on if you believe in many worlds. You notice that the world, many worlds, never appeared in that characterization. That's because how we take the quantum state of the universe and divide it up into worlds is a human convenience. It is a human convenience in exactly the same way that talking about the box of gas as a fluid or a gas with a temperature and a density is a human convenience. We don't have to do it.

There's not even as comprehensive and detailed description as talking about all the individual molecules, but it is still true. Okay. It's a higher level emergent description. And there's a reason why David Wallace, who is the leading many worlds guy, former podcast guest, his book on Ever-Reiting Quantum Mechanics is called The Emergent Multiverse. Because that multiverse description, that dividing the wave function in. into branches is an emergent thing. And in that case, the whole thing about emergent phenomena is they provide a true handle on what is going on, but at an approximate level, right, at a way that you ignore some information or don't need to know all the information and can still get some

truth about what is going on. But because it's approximate, different people might actually disagree about the best way to divide it up. And I think that David Deutsch and I disagree about the best way to divide up the wave function of the universe in cases before decoherence has happened. I don't think it has anything to do with ignoring the fact that there's descriptions or just saying it should be just math or anything like that. It's just a matter of where you decide what kind of higher level description you find most convenient for your point of view. Zach McKinney says, in your conversation with Will McCaskill, you two discussed how the plurality and evolution of values is essential to the survival and future well.

well-being of humanity? What would you hypothesize to be the core values that enable human societies to survive and thrive in increasingly hazardous times? How might you approach the problem of quantifying and modeling the spread of ideas and evolution of values at different scales within and across cultures? So I don't want to disappoint you here, Zach, but these are way more ambitious questions that I could possibly answer maybe in my lifetime, much less in this AMA. The core values that enable human societies to survive and thrive and quantifying and modeling, the spread of ideas and evolution of values,

great things to think about. My thoughts on those are going to be exactly as valuable as anyone else who is sort of not thought about them very deeply, but a little bit, okay? So I have no deep, special expert level insights here. I do kind of pause a little bit at the idea of the core values that enable human societies to survive and thrive.

I'm not sure there are such things. There are values that I think are good. You know, values are things that are hard to make lists of because they're not sort of discrete units. A lot of the values, like if you say justice is a value and fairness is a value. There's a lot of overlap between justice and fairness. John Rawls famously tried to portray what we mean by justice as a version of fairness, but other people portray it differently.

But anyway, there's a lot of overlap. So I don't think that you're ever going to find the list of the core values. Having said that, you know, I think that we kind of mostly know, right? Or at least, maybe not. I always wonder about this because I worry that, you know, I'm stuck in some kind of bubble where I think that the people who I talk to mostly agree about these things. But if you go throughout history, whether you're secular or religious thinkers and you want to think about human values,

different systems of values often disagree about this or that thing, as is very evident out there in the world, but there's other things you see over and over again, right? Some version of the golden rule. Treat people as ends, not means. Do unto others as you would have them do unto yourself. Act in such a way so that your actions would be part of a universal maxim. Whatever you want to call it, different ideas of treating other people with dignity, okay? I think that's a core human value. It's a human value that gets in the way sometimes of a simplistic utilitarian notion of greatest good for the greatest number because sometimes maybe you can convince yourself

that you can get a great good by undervaluing the dignity of somebody and that's why it's hard to write down the fundamentalist of values because I think the greatest good is also a pretty good value. Let's try to get as much good as we can, right? I think that at a detailed person to person level, the idea of treating other people, not necessarily as you would like to be treated.

I think it's a little bit simplistic because other people might be different than you, right? That's why Kant, when he was formulating the categorical imperative, was trying to be a little bit more sophisticated about it. It's hard to put exactly into words what is going on here. But the basic idea is that we should act as if there is some inherent dignity in other human beings. That sounds right, you know, and you say it and people are going to nod along. Then you can get into edge cases. What counts as a human being?

You know, does an unborn baby count as a human being? Does a chimpanzee count as a human being? Does a smart computer count as a human being? And yeah, that's fun and we can think about it. But that's why it's not rigorously done. So I think that kind of, and that's also, you know, it goes back to the podcast conversation I had with Paul Bloom about empathy. I think that at a more practical level, not just sort of an airy-fairy, what-of-ary, what-the-values kind of level, but at a down in the grit, what actions do we take kind of level, Paul wanted to argue that rationality is sort of a better guide to doing good things than empathy is. And his argument, which psychologically makes sense, is that people are just much. better at empathizing with people who are like themselves. Whereas if we are rational and universalist, we can say in a more clear-cut, focused way, that we should be good to everybody in the world,

not just people like ourselves. But I think that, again, at the actual implementation level, there's a huge failure mode for that kind of thinking, which is that it's really easy to think you're being rational when you're not. That's not to say, we shouldn't try to be rational, but I think that we cannot pay attention to everything in the world. We're going to take in certain information. We're going to ignore other information. And we might very well be being rational on the basis of the information we're paying attention to, but that's falling short of being perfectly rational. And that's why I think the empathy is important, because one way of opening our eyes to other kinds of information and concerns and considerations that we might. might not otherwise take seriously is to imagine putting ourselves in the shoes of other people. So one way or another, that kind of idea, however you want to parse it, is what I think should be

the core value of human societies, taking other people seriously, thinking about their needs, what if I were in their shoes? There's no simple way of putting it, but something along those lines. As far as quantifying and modeling spread of ideas and evolution of values, I have no idea how to do that. That's something that I'm not even sure if that's a well-posed question. Maybe if we could hack it down into some well-posed questions, we could make some progress on it. Okay, I'm going to group two questions together. James Maddox says, at the end of the podcast with Antonio Padilla, you were discussing if the universe is finite or infinite. As someone who agreed with your arguments on the naturalness of infinity, I was shaken by his rebuttal of, well, which infinity then?

Is there any lifeline you can throw to those of us disturbed by the prospect of living in a finite universe? And then Eric Chen says, what's your own take on the last question you asked Tony Padilla? Is reality finite or infinite? What are the best reasons for taking either view on this question? So I think Eric's question is very straightforward, and I'll take a step at answering it. James's question is sort of throws in the interesting, you know, personal feeling kind of aspect to it, you know, being disturbed by the prospect of living in a finite universe. So my real advice would be, don't be disturbed by anything like that. You're asking for trouble if you're, in some sense,

hooking your own sense of well-being to any large-scale features of the universe as a whole. Because we don't know what they are. The universe could be finite. It could be infinite. We just don't know. So don't be disturbed one way or the other. That I would say very strongly. So as to whether it is finite or infinite,

I'm actually open-minded about this. I'm more open-minded than I used to be. I used to think it was just infinite for basically arrow of time type questions. I think that if the universe lasts forever, then it better have an infinite number of things that can possibly do because otherwise it will just do some subset of things over and over and over again. If there's only a finite number of states that universe can be in and an infinite amount of time, you're going to be repeating yourself an awful lot. and that gets into various problems that are essentially variations on the theme of Boltzman brains,

one way or the other. So a universe that has an infinite number of possibilities and the last forever in time is one way out of that. And that's sort of the idea that I put forward with Jennifer Chen back in her 2004 paper. But there is another thing that you can say that is completely legit on the table if the universe is finite in both the number of states it can take on and in time, right? So if the universe has a boundary in time or a cyclic in time or something like that, then in principle, we could imagine a well-posed arrow of time within that finite period of time. I just don't know how to make that work, right? I don't even have a suggestion as to how that might work, but it's completely possible. I do have a half-written paper that I should finish

writing someday on a completely finite, discrete version of quantum mechanics, which is both a little bit harder to make than you think, and still possible, still not that hard. So I think it's worth pointing out there. But it's not because I think the universe is like that. It's just because it's important to keep open all the possibilities as to what we should. Well, we should be contemplating when we ask these big questions. I'm in favor of asking the questions. I just don't have strong feelings about what the answers are. Derek Bain says, I'm really enjoying the new book, and for what it's worth, I think, exceeds in making physics accessible to a total novice like myself. Thank you, Derek. Now the question, have you dressed up for Halloween in the past? And if so,

which of your costumes are you most proud of? Yeah, you know, I like the buttering up approach to asking the question, gets me more likely to answer it. I'm happy to do that. And I haven't dressed up for Halloween in a while, to be honest. Like, it's just not one of the holidays that I do anything special for usually. When I as a kid, of course. Yeah, we'd go trick-or-treating, dress up for Halloween. Probably the best costume was one that we made to look like a robot. So I had a big cardboard box, spray painted it silver, and like every electronic gizmo and gadget that we had in the garage was temporarily attached to the box. So I don't know. An amp meter, something like that, various bells and whistles. There wasn't a lot of stuff. We weren't a very highly

technologically advanced household when I was a youngster, but we did our best. And I thought that was, you know, at least a time when I showed some creativity there. Usually store-bought costumes were perfectly fine for me. Go to group two questions together here. One is from Ken Wolfe, who says, presuming such things exist, if we found there was a primordial black hole near enough to send an orbiter, what experiment would you most like to see done, and what question would you be hoping to answer? and Rue Phillips says, if a black hole were able to come close enough to our solar system that we can send spacecraft out to it in our lifetime, what questions would you want to try and answer that we aren't able to get at easily

with black holes too far to reach with a spacecraft? Well, you know, black holes are actually not actually probably that mysterious in terms of how they behave. You know, again, it goes to the fact that our current understanding of the laws of physics seems to be pretty good. So if you have a medium-sized black hole, good old Einstein's classical general relativity should be super good at explaining what it is like.

We should have already a pretty good picture. There's not like mysteries of black holes that we need to observe them to figure out. Of course, the theory could be wrong, right? General relativity could be wrong. So there could be deviations from real black holes to what is predicted by general relativity, so far we haven't seen that. The best chance to have seen that so far was in the LIGO detection of gravitational waves. It's a little

bit crude because you're only seeing a tiny little bit of the last part of the in spiral of two black holes, but still you can try very hard, and they do try very hard, to match the predictions of general relativity to precisely the kind of gravitational waves that they observe. And the answer is it's smack on. It's exactly right. So it would be enormously exciting to find out that the gravitational field of a black hole was somehow not quite what was predicted by general relativity, but that's, you know, I wouldn't bet on it if I were there. Now, if it's a tiny black hole, then we have a chance of seeing hawking radiation. The thing about hawking radiation is that the temperature at which the black hole's emitting is higher when the black hole is smaller. So if it's a big black hole, it'll be

essentially invisible as far as hawking radiation is concerned. If it's a smaller black hole, there will be a point depending on what your instrumental sensitivity is where you can actually observe the hawking radiation. You don't want to observe it being too hot because that means it's about to explode and you don't want to get too close by. But certainly observing hawking radiation would be fascinating. Again, there's a very good chance that it will just look like what the theory predicts. We have a theory. Hawking wrote down the theory that predicts it. So it would be enormously interesting and well, you know, revolutionary if we saw either no hawking radiation where we should or we saw hawking radiation, but it was a different kind of thing that we expected.

Any one of those would be super, super interesting. So the two big questions I want to know the answer to that we could test if we were near a black hole are, what is the gravitational field and what does the hawking radiation look like? We have very good predictions for what they should be, but any deviations from those predictions would be very, very, very important. Robert Ruxendrescue says, I had a bunch of scientific questions on my mind, and I'm going to change the topic and ask something else,

something that is important for me, bullying. When I was little, I was bullied a lot, both in elementary school and in high school, the main reason that I was considered the school's nerd. Have you personally had to deal with bullying? If so, what did you do and what was the reason? I guess I experienced a little bit. You know, I was a pretty nerdy kid as a youngster also,

but I mostly managed to stay away from it, maybe because there were other kids who were even more fun targets to pick on than I was. I was pick on a bull, but not very fun to pick on. I didn't respond in the way that they were hoping maybe. But I don't know. Maybe I'm just misremembering, or maybe there were other things going on. I went to a big public high school.

There are plenty of kids to be picked on. I do think it's bad. I mean, I don't think that there's a strong pro-bullying lobby out there. So it's not something that should be very controversial. I presume, I mean, I guess that there are probably people who think that maybe it toughens you up. Certainly there are kids who are pro-bullying because they are bullies, right? But, you know, Jennifer, my wife always points out this scientific study that was done about bullying. but it was a weird kind of study where they took kids and, you know, they had some independent way of judging, you know, who were the popular ones, who were the bullies, who were the nerds, who were picked on, who were the outcasts, whatever.

And they had them watch the Disney movie Dumbo. And you know, Dumbo is an outcast. Dumbo is picked on by everybody else until, you know, he learns to fly and then he's a star, right? But early on, he's bullied. That's exactly what happens to Dumbo. And so they asked the kids, some of whom were super socially popular and some were bullies and others of whom were outcast or whatever, they said, you know, who do you identify with in this movie? And the answer is, everyone thinks they're dumber. Everyone thinks that they're the ones at the end of the day who are picked on.

Even the ones who you might have thought were picking on you, they thought that someone else, maybe it was a teacher, maybe it was bigger kids, maybe it was someone at home, someone was picking on them. So I don't think anyone would stand up very much in favor of bullying. So the question is what to do about it. And there I don't have any great suggestions. You know, I do think that maybe one tiny suggestion is just acknowledging the problem, right? To be sensitive to the fact that things that happen to people when they're very young can affect how they turn out when they grow older and not just imagine that kids should tough it out. and put up with misbehavior on the part of their peers or whatever, to be a little bit more sensitive to how kids treat each other.

You know, kids can be super-duper kind and generous, and they can also be super-duper nasty and selfish. They haven't learned. You know, they haven't always learned to separate one from the other and learn that it's okay to be generous and that it's not okay to be a bully and whatever. And I think that these are things that we should be teaching our kids. And there are some teachers who are super-duper good,

and are able to do that. And there are other teachers who don't have that training or don't have that empathy or that ability or whatever. There are other teachers who are bullies, right? And we probably have all had them along the way. So maybe the simple thing to do is just to remind ourselves that we don't do a great job in valuing the job that is done by teachers, whether it's in terms of social respect or how much they get paid

or the education we give them. it's not necessarily considered a high status occupation in our society. So if we had teachers who were better equipped, not only the training, but also just class sizes, resources, things like that, then maybe they'd be better able to make sure things like that doesn't happen in their schools. But I don't know. I'm not an expert there. I have not spent a lot of time recently in my life in secondary schools or anything like that or elementary schools. Sheldon Silliman says, I'm guessing you might consider evolution as an emergent phenomenon.

And if so, would you then say that this emergence implies a strong possibility that evolution would operate throughout the universe? Is emergence universal? And how does that work for such fuzzy concepts like culture and agency? So I absolutely think that evolution could be universal. You know, evolution is a little bit misunderstood sometimes. There's always a stage in a young scientific kid's life where they hit a problem. upon the idea that evolution is basically tautological, right? Survival of the fittest, well, you know, who else is going to survive?

You're going to define the fittest as the ones who survive, and they're going to pass down their genes, and that's how it's going to work. The reality is more subtle than that. The reality of biological evolution is specifically that there is random variation, tiny random variation in mature species, but there's random variations from generation to generation. So in some sense, the genome is doing a search through parameter space, right? It's a very inefficient search in a whole bunch of ways, but that's because it was not designed to be efficient. It was what is naturally happens in some sense. So it doesn't count as evolution if you simply

have progeny. It only counts as evolution if you have some information in one generation that is passed on with the possibility of slight variations to the next generation. But that's not that hard. to imagine happening, right? I mean, if you have any life form that is based on genetic information, it's never going to be passed on 100% perfectly all the time. So I think it would be very natural for evolution to happen on other planets, other places, other biospheres or whatever. And yes, it's an emergent phenomenon, but in the very weak sense.

It's not fundamental, right? It's real, but it's not fundamental. Things that are real but are not part of our most comprehensive description. to physical reality are emergent, whether it's tables and chairs, pressure and temperature, evolution, and culture. All those things are higher level and therefore emergent. As long as you believe the world is fundamentally physical, which I do. Michael Monhoft says, which individual steps are happening when two particles become entangled or disentangled, and how long does this process from not entangled to entangled approximately take?

oops, I'm going to combine this together with the next question, which is from Jay Peters, a priority question. Remember, everyone gets one priority question to ask in their lifetime, and I will do my best to answer it. What is the nature of the interaction among particles that is said to give rise to quantum entanglement? Is it just a matter of spatial proximity, such that the closer together they are, the greater the level of entanglement, or does it have to be some sort of event that includes both and that establishes their entanglement? Well, it's there is a difference between an interaction as such and an interaction that causes entanglement. Some interactions do not cause entanglement. Basically, what you have to imagine is that at least

one of the quantum mechanical systems is in a superposition, okay? And that's, I'm slowing down here because there's technicalities here that I don't want to get into. Every system is in a superposition in some vague sense. But if I, if I can just get away with saying, you know what I mean. mean, if you have like a spinning particle along one axis and it's spin up plus spin down, then it's in a superposition. Or if I have a particle with a superposition of being in this position and also in some other position over there, that's what I mean by a system in a superposition. And then entanglement happens when that system interacts with some other system in such a way

that the different parts of the superposition interact differently. Okay, so the example I usually use is if I have a spinning particle, spin up and spin down, some superposition of spin up and spin down, and I drop the particle. Then it is interacting with the Earth, because it is interacting with the gravitational field of the Earth. But it does not become entangled with the Earth because both the spin up and the spin down parts of the superposition evolve in the gravitational field in the same way to an extraordinarily good approximation. So there's an interaction, but it's the same interaction for all the different parts of the superimposed quantum system, so there's no entanglement going on. Whereas, if you have something like Schrodinger's cat, the superposition is between an awake cat and a sleep cat, and they are in two different locations. The awake cat is up and walking around. The sleep cat is lying on the ground,

sleeping, and a photon can very easily be absorbed, let's say, by the awake cat, and completely non-interacting with the asleep cat. So that's an example where the particle interacts, the photon interacts differently with the awake part of the cat and the asleep part of the cat, and therefore they will become entangled. Okay. So that's what you need to become entangled. when one quantum system interacts with another quantum system in superposition differently with the different parts of the superposition. So spinning particles do this all the time. There can be interactions, there are generally interactions,

between particles that depend on the spin. So if you have one particle simply passing by another one, two neutrons, for example, let's say, and they're in a superposition of different spin states, the upspin parts of the neutrons will interact with each other differently than the downspin parts. And something like that for electrons rather than neutrons is very often what is used in designs for quantum computers or something like that. Another way to do it is to create particles that are entangled from the start. So when the Higgs boson decays, the Higgs boson decays, the Higgs boson has zero spin.

So when it decays into two spinning particles, those two spinning particles have to be spinning in opposite direction. so that angular momentum is conserved. So we don't necessarily know which direction, either one of them is spinning in, but we know it's entangled with the other particle that the Higgs is decaying into because the two different parts of the superposition

are connected to each other in the way that we identify as entanglement. So Cooper says, when you talk about other universes with different laws of physics, do you just mean their fundamental constants have different values? Do you mean completely different

underlying equations like different terms in GR or different gauge symmetries in QFT. Well, that depends on the context in which you're talking about universes with different laws of physics. Specifically in the context of something like the string theory landscape. Okay. So the string theory landscape comes about because we think there are extra dimensions of space in string theory. They can be curled up and hidden from our view in various ways in a large number of

different ways. And those ways all give rise to different. low-energy laws of physics, different local, visible laws of physics. And in that sense, the basic laws of quantum field theory, relativity, et cetera, are still 100% the same from universe to universe. But the set of particles can be different. You know, we have quarks and leptons and higgs in our universe. So maybe they only have leptons or don't have anything that you'd recognize as quarks or leptons. Or maybe you only have spin-zero particles or whatever. There's a whole bunch of different possibilities. Even if you have the same particles, you can have different

interactions between them, either different actual forces, so different gauge symmetries, or different strengths of forces, different values of the cosmological constant. You can even have different numbers of dimensions of space. Okay, you can have some regions have six-dimensional space, some have three-dimensional space, etc. But still all under the general rubric of quantum field theory and relativity, because the underlying theory is string theory, which has in the low-energy limit quantum field theory and relativity as part of its description of physics. Now, if you're not thinking of the string theory landscape, if you're thinking more generally, I can imagine all sorts of things, right? I don't necessarily have a physical mechanism for making them. So whenever I talk about

the multiverse, I try to emphasize the fact that it's not just saying there's a whole bunch of universes out there. There are physical mechanisms that can bring these different universes into existence. In cosmology, we have eternal inflation and we have string theory, and these arguably, anyway, give rise to a multiverse with different laws of physics in different places. And so in that case, they would still be under the quantum field theory rubric, but with very different particles, forces, et cetera. Anonymous says, the standard model is called the most successful theory ever. Well, isn't it like the most successfully tuned theory ever? Every time a result comes in, some parameters are tuned to produce that value, and ranges for other parameters may further be constrained.

No wonder the standard model agrees with experiment. So I don't know where you've been picking up your physics, anonymous, but that is completely not true. It is very, very much not the case that every time a result comes in, some parameters are tuned to produce that value. The number of parameters, the number of experiments, I should say, that are done on standard model particles is enormously larger than the number of parameters that we have in the theory. It is highly, highly, highly constrained because we want to find a mistake in it, right? We want to find that it somehow deviates from the predictions that we make. For example, for the Higgs boson, we discovered the Higgs boson, mostly looking at it decaying into two photons, right? And that basically fixed the one undetermined parameter of the model, namely the mass of the Higgs. And then we said,

okay, now we know what the mass of the Higgs is. And then once you know that, you know the rate of decay of the Higgs boson into electrons and into top quarks and into W bosons and all those things. There's no extra free parameters. Those are all predictable in terms of the known parameters. And then we go out and test them. That's what people at the LHC actually do. So it is quite a bit of wonder that the standard model agrees with experiment. It is highly, highly over-constrained and remarkably resilient at agreeing with experiment.

Keith says, I happen to see the 76ers are playing the Wizards tonight in your neck of the woods as they saying. Any particular fun in-person 76 or game memories you feel like sharing as a kid or whenever? I got to tell you, Keith, the sixers are not doing well to start the year, and I have had, I had very high hopes and continue to have very high hopes, because I'm generally an optimistic sports fan, despite originating from the Philadelphia area. So I hope they get their act together. But, you know, right now, I have to say, like, I have different ways, for example, of going online and and reading things and reading Twitter or whatever. And when things are going well in basketball and with the Sixers,

reading about the Sixers is like my happy place. And I can ignore the rest of the problems the world has. And then when the Sixers keep losing, I'm like, geez, there's just no more happy places on the Internet. I'm not quite sure what to do about that. When I was a kid, you know, we didn't go very often to the Sixers games. We'd go maybe once a year or something like that. And I do remember going to a game.

I don't remember what year it was, but it was before they won the championship in 1983, but not too long before, so early 80s, watching the Sixers play the Boston Celtics, their hated rivals. And it was in the spectrum, the previously existing building, which when it was built in the 60s or 70s or whatever was state-of-the-art facility. But by later standards was quite a small little building. And the joint was rocking.

Man, when the Sixers would play the Celtics, it would be sold out, everyone would be shouting, and they were pretty well-informed fans, you know, like Larry Bird on the Celtics would always cheat and not play man-to-man defense, and the Sixers fans would start chanting, who's bird guarding? Because there were rules against illegal defense back in those days. And, you know, whenever anyone got fouled,

which happened a lot back in those days, you know, everyone would jump to their feet and either boo or cheer, depending on how it went. And it was really, you know, it was a nice, painless, relatively harm-free way of feeling some common emotional bond with your friends in the fandom of the Sixers. So I, and it was all because not only was basketball fun, but that that particular rivalry was so amazing and so emotional.

And I hope it comes back. I know that Boston did very, very well last year. Hopefully the Sixers can live up to their end of the bargain one of these days. and the rivalry will be rejoined with gusto. Andrew Jay says, keeping in line with your thinking about social systems using ideas from physical systems. What role, if any, do you think entropy has to play

in macro societal actions? Is human progress doomed to simply shift disorder to whatever system we have the few as problems with, be it the environment, international trade, etc.? Well, I think that you need to be a little bit more careful when we think about these big, complicated, macro complex systems when you invoke ideas like entropy. I think there is a place for ideas like entropy,

but it's a lot more subtle than mixing cream into coffee, right? When you mix cream into coffee, entropy goes up, but that statement that entropy is going up is pretty comprehensive. That basically tells you what you need to know. There's not a lot of nuances along the way. Once you get to biology and psychology and sociology, or even things like weather or plate tectonics, Just saying entropy increases doesn't come anywhere close to capturing everything that is going on.

But I think that's an interesting part of the problem, not a reason not to think about it. Entropy does go up, but entropy goes up in closed systems, which the usual way that we think of human systems, they're not closed, right? We interact with the rest of the universe in very important ways. The biosphere on the earth is dramatically not closed. The entropy of the biosphere is not going up in any obvious way. We get low entropy radiation from the sun. We give it back to the universe in a high entropy form, so the entropy of the universe is going up.

But here on Earth, the entropy is pretty low and stays that way. Nevertheless, within some particular system, you can go beyond just saying entropy goes up in closed systems, and you can think about how different degrees of freedom relax and locally increase their entropy, while entropy might be going down or being exchanged or heat is flowing in some way somewhere else. So I don't think it's simple. I don't think that human progress is doomed to shift disorder around.

I think that's way oversimplifying what is actually a very, very complex situation. You know, one way to put it is the timescales for things like, I don't know, biology, like all of biology, like the history of human life or the history of the sun or something like that, the time scales for these large-scale systems we're talking about to come to equilibrium are enormously larger than the lifetime of a human being. So even though there is some overall sense in which entropy is going up, the details of the way in which it goes up matter a lot. And maybe that's, you know, room for coming up with new and important principles of physics

or of sociophysics or political physics or something like that. I'm not quite sure. Certainly complex systems researchers care about. about problems like that. Okay, Brendan says, do you think your deep understanding of math and physics enables you to quickly or easily comprehend other technical fields such as computer science? For example, are you able to understand machine learning and or computer programming with little difficulty?

Well, I certainly wouldn't say little difficulty. I can't even understand other areas of physics that I don't already understand with little difficulty. There's always difficulty involved. But also, of course, there is a familiarity with certain ways of manipulating symbols, ways of reasoning or whatever, I think that my ability to pick up something in computer programming is much better now than it would be if I had no physics training, but I was otherwise the same person. But it's very, very far away from saying little difficulty.

Okay, Brian Mapes says, here's some numerology. Is there anything fundamental about 10, beyond four fingers plus supposable thumbs being biomechanically successful? And even spookier, what is up with 10 to the 10? Bits in the genome, neurons in the brain, stars in the galaxy, galaxies in the universe, enough data for machine learning, etc. Well, no, there's nothing fundamental about that at all.

Even in biological life forms here on Earth, they don't all have 10 fingers and toes, right? I've known plenty of cats who don't have 10 fingers and toes. So, and 10 to the 10, certainly there's no relationship there. I mean, for one thing, it's not even true that

that's the number of galaxies in the universe. It's closer to 10 to the 12. And if we're starting to ignore differences like 10 to the 12 versus 10 to the 10, you're going to find a lot of coincidences out there because you're just being quite forgiving when you say the numbers are similar to each other. So I wouldn't draw too much conclusions from that little bit of numerology. Henry Jacobs says, lottery voting is an election system wherein a single voter is randomly selected and their vote decides the election.

Here are some positives. Number one, it's a proportionate representation system. Number two, voters have more power than in a plurality-based system. If you model the voters as biased coins, the mutual information between a voter and the election outcome decays quadratically with population size. In plurality systems, the decay is exponential. And then Henry lists a whole bunch of other positives. And he says, as you can tell him, a fan of this system, there are issues. Nonetheless, do you think this is a good starting point?

So just to say again, for those of you who are not familiar with this, The idea is that rather than letting everyone vote on a candidate or a some kind of plebiscite or whatever to actually pass a ballot resolution or whatever, rather than doing that and just counting the votes and doing the majority, lottery voting says, let's pick a random person within the electorate and just let them decide. It is easier. It's cheaper to do that than have everyone vote, but otherwise, no, I am not a fan of this. So I'll tell you why I'm a fan, but even though I'm very much not a fan of this system, I get it. You know, I'm not super-duper happy with any voting system, and I think that there is a problem. And the basic problem of voting systems, before I answer your question, the basic problem of voting systems is how much should we care about representing minority viewpoints, right? So let's imagine we have an election between three people.

Three people are running for president or something like that. And roughly speaking, half the people are very, very happy with one candidate, almost as happy with the second candidate, and cannot stand the third candidate. Roughly speaking, the other half of the people are really, really happy with the ones who the other one hate, are almost as happy with the other. ones the other ones put second and really, really hate the ones the other ones put first. Okay? So in other words, there's one candidate that gets a lot of preference or a lot of hate.

There's one candidate gets a lot of preference or a lot of hate. And there's a third candidate who everyone would be happy with. Under the current system, that person who everyone would be happy with gets zero votes because there's another candidate that is better than them. So this is a good reason to say that we might not in our current system be taking and do account all the preferences that people have, okay? And you can actually, even though, even, there's even, you know, rules about, there's, there's principles that people put forward that are supposed to be things we would want to have be true in any given voting system. And you can almost always find a voting

system that seems reasonable that violates some of these rules. So it's a very complex and nuanced kind of thing that I'm learning a lot about in the physics of democracy class. Having said that, the problem with the lottery voting is the following. Imagine that you have a system where 90% of the people think one thing and 10% of the people think something really, really different. Like you're voting for a candidate and there's like some 10% crazy fascist racist party, right? And then the other 90% of the people are voting for the regular parties. In the current kind of system or in any ranked choice system or any range voting system, the people, the 10% crazy racist fascist would never win. and that's taken to be an advantage of the system because the crazy fringes are not supposed to win.

But in a lottery voting system, the crazy fringes would win 10% of the time. And 10% things happen a lot, quite a bit, right? And so there is actually, it is thought to be something of a virtue of voting systems if they can sort of smooth out the rough edges and, you know, take more or less the average, rather than taking a representative sample. So as Henry says, mutual information between a voter and the election outcome decays quadratically with population size and plurality systems decay is exponential. That's a feature, not a bug. We're not trying to necessarily exactly represent the will of the people, including the crazy fringe people, right? Now, you can debate that. That's why I said at the beginning. This is all very debatable. You might

to make the point of view that, sure, there could be a 10% crazy fringe group, but there also could be a 10% like really, really good group that also never gets its voice heard. But I do think that there is something to be said that if you're going to live in a democracy, it's not only that most of the people should get their way, but we should do our best to get a situation where most of the people aren't too dissatisfied. So it should be more than just majority rules in my view. There should be a way in which people who don't get 100% of what they want are nevertheless not trampled over. And the worry in a lottery voting system like that is when those 10% win, the 90% are going to be trampled over. And that could be bad.

So some smoothing out of the extremes, I think, is actually intentional and good in a voting system. Having said that, I don't know what my favorite voting system actually is. So further thought and further persuasion is welcome. Dory Vinett says, Not a question, but I think you'd like knowing that my cat associates your voice with treats. I often listen to Minescape while making dinner, and now when Bastet hears your voice at other times,

she runs to the kitchen. So I am very pleased to hear that, Dory, and I'm glad that you have a positive association with my voice, Bastet, and I hope that you get all the treats because you're a good kitty who deserves all the treats. Johann Falk says, What mathematics do you think everyone should learn in school, regardless of career path?

I mean, these are some of the questions that I don't know. I don't have strong opinions about because these are hard questions, and I don't think we should be too glib about them. I would like everyone to know basic algebra, trigonometry, geometry, right? The things that we actually do try to teach to our students. I think you should be able to plot a function. In fact, I think you should be able to know the concepts of a derivative and an integral. even if you can't do them, and this is part of the idea behind the biggest ideas books, is that you should be able to understand what it means.

If someone says, oh, look, the maximum value of this function is where its derivative vanishes. That's not that hard to understand, and everyone should understand that. And I think that we do try to teach those basic things. As John Allen Powell said, and I completely agree with, there are plenty of things in statistics and probability that absolutely should be taught more. I mean, just the idea of probability, the axioms for probability, basic ideas about how to use it, marginal probabilities, conditional probabilities, things like that, some applications to the real world.

You know, it's not that hard to understand Bays' theorem. I think that everyone should understand Bases theorem when they come out of high school. So that would be nice, but, you know, a lot of things are nice. I don't know what else would have to go to do that, which is why I can't really claim to have a sweeping program for fixing math in schools. Michael Kramer says, concerning the past hypothesis, the hypothesis that the universe was initially in a state of extremely or maximally low entropy, is there a way that that might be tested

experimentally? So yes and no is the answer here. We make observations, like we take a map of the cosmic microwave background. From those observations, we infer what the early universe was like. It was hot and dense and very smooth. from that in our knowledge of physics, we can calculate the entropy, and it was very low, okay? So in all that chain of logic, we have made an observation that the early universe had a very low entropy. The problem with that logic and with all logic like that is that it assumes the past hypothesis,

because we don't actually see the early universe. We see photons landing at our telescope. The connection between the photons landing in our telescope and what's the moment. the early universe was like, is made on the basis of assuming that entropy has been increasing the whole way. So that's why it was dubbed by David Albert, correctly, the past hypothesis, rather than the past fact, even though we can observe it. But what we observe is that it is consistent. It is a self-consistent set of assumptions to imagine that the early universe had low entropy that is compatible with what we see. But it's also always possible the

universe had high entropy, and we just randomly fluctuated into example. It's just randomly fluctuated into existence, and there's no experiment you can do that can rule out that possibility. Roy Thompson says, priority question. When black holes merge, how is the mass converted to gravitational waves? Any implication for the black hole information paradox? Well, remember, mass is just a form of energy. When you talk about the mass of a black hole, you're using E equals MC squared. There's energy in the black hole, and the black hole in its rest frame is stationary, and it has a mass, divided by C squared. So really the question is what is happening to the energy. And, you know, there's also energy contained in the orbits of the black holes, right? Black holes are not going

to merge unless they're moving. So there's some kinetic energy also. And it's all in, contained in the curvature of space time, all of that energy, right? That's the only thing that exists. You know, you don't need any solid material in the black hole. If you had any, it would crunch to the singularity. The black hole is. a region of space time. And outside the black hole is a region of space time. And so all of the energy in the black holes and in the gravitational waves is all contained in the curvature of space time. So there's no real conversion from mass of the black hole to gravitational waves. It's one configuration of curved space time evolving smoothly according to Einstein's equation into another

configuration of curved space time where the energy is the same, but now some of it is moving away in the form of gravitational waves. And I don't think it has any implication for the black hole information paradox because you don't need to talk about black holes merging or gravitational waves to talk about the information paradox. Schleyer says, you've said that you take the universe to be a closed system thermodynamically. I know some other physicists don't, though I think they are outliers. Can you describe the status of our knowledge here? Being unbounded, expanding, and maybe infinite, the universe doesn't seem much like a piston chamber. Well, our knowledge is very minimal here, right?

Because we're talking about the universe as a whole, about which we know very little. Now, I think I'm missing something when you say the universe doesn't seem like a piston chamber. That's true. It does not seem much like a piston chamber. A piston chamber is a paradigmatic, not closed system. There is an external thing that pulls or pushes on the piston, and the walls of the pistons move in response to that, and therefore,

the system inside can increase or decrease in heat or entropy or whatever. It is not a closed system by any usual way of thinking. The universe is usually thought up to be a closed system for two reasons. Number one, we see no reason why it shouldn't. There's no either theoretical argument or experimental evidence that the universe is not closed. Number two, it's not even clear what it would mean for the universe to not be a closed system. Unless you have some weird definition of universe, a closed system, an open system is one that is exchanging energy and information with another system. So if our universe was exchanging energy and information with another system, I would just redefine universe to include that other system too, right? I don't know what it would be.

Again, there's no need for any such system on the basis of theory or experiment, but my usual philosophy about these things is to admit that lots of things. things are possible in cosmology, et cetera, but to try to keep things as simple and as close to what we already know is true and work out what would happen in those cases. So I think that just treating the universe as a closed system is perfectly simple and compatible with everything we know, so I'm going to go with that. Martha Henrichs says, what sociocultural rituals and ceremonies do you or have you ever participated in, i.e. were you married by a religious officiant? Do you watch fireworks in the 4th of July, fast during Ramadan. Do not fast during Ramadan. Do not watch

fireworks on the 4th of July. We were married, I guess, by a religious officiant, namely a friend of ours who got one of those online religious order, you know, $25, you're now a holy man kind of thing. In California, that's all you need to marry somebody, but not really very religious, honestly. But we did have a ceremony, right? We got married. there was a ceremony. You know, we modified our wedding vows from other wedding vows and the whole thing. And I take that very seriously. I think that's very, I don't want to say it's important.

It's important to me. It may or may not be important to someone else. I think that rituals and ceremonies are very important, but I have no special attachment to other people's favorite rituals and ceremonies, okay? So, you know, Jennifer and I would never go out for a romantic dinner on Valentine's Day. That just seems like asking for trouble. Everyone else is out, and they're all, you know, crowding the restaurants and whatever. And we can very easily go out on some other day and have a very nice dinner.

Likewise, neither one of us are big fans of the traditional Thanksgiving turkey dinner. But we did replace the traditional Thanksgiving turkey dinner with a ritual of going to Las Vegas every Thanksgiving. and having Peking Duck at the restaurant Jasmine in the Bellagio. That was easier to do when we could drive there from L.A., so we're not going to be doing that this year. We need to establish a new tradition. We have various traditions for Thanksgiving, for New Year's, for birthdays, and things like that. So I think that they're, that my personal traditions and rituals and ceremonies are important.

But if you're asking about the commonly shared sociocultural ones, no, I don't have any special attachment to those, except, of course, like sports and things like that, which I'm a big fan of. I think, again, it's a sort of harmless fun way to get swept up in the crowd and enjoy their enthusiasm together. As I record this, the Philadelphia Phillies are still in the World Series. They may have lost by the time you're listening to it, or they may have won by the time you're listening to it. So the city of Philadelphia will be very, very happy. I'm not a huge baseball fan, so I'll be, like, mildly happy, but I'm not going to go crazy like many. my fellow Philadelphians.

Brent Meeker says, in Mindscape 63, the solo episode on finding gravity within quantum mechanics, you speculated that there are only finitely many degrees of freedom in a given volume. Wouldn't this imply that there are also

only finitely many possible states? And so there would be a smallest non-zero probability of any possible event. The basic answer is no, because quantum mechanics just doesn't quite work that way. To say there's a finite number of degrees of freedom

means there's a finite number of completely independent states. But in quantum mechanics, states are continuous. States are any superposition of any set of basis states, as we call them. So you can have a particle spin up, a particle spinning that is spin down. So that single particle is literally one degree of freedom, right? It's either up or down. There's only one particle doing the thing. But how many states are there an infinite number of possible states? Because any superposition of alpha times spin up plus square root of one minus alpha squared spin down is a perfectly good state. There's a smooth, continuous spectrum of them. And that is why there's no relationship to anything like a smallest non-zero probability. The probability does not come from

the number of states. It comes from those coefficients, the amplitudes. And the amplitudes are complex numbers. They're complex numbers between zero and one in magnitude. So it's a smooth continuum of possibilities, even if there's a finite number of states. Sean Bentley says, Loved your episode on large numbers with Tony Padilla. I'm not as studied on the holographic principle as I could be, so apologize for the pedestrian question. When removing gravity, why do we go from three dimensions of space down to two, and not four dimensions of space time down to three?

Well, we do. Sorry if that wasn't clear. So we have space and time. Time didn't go away when we do the holographic. principle, but time is just time. It didn't change when you did the holographic principle either. So when someone says, you know, there's different versions of holography, and in the ADS-CFD correspondence in particular, there's a boundary and a bulk, and the bulk has one more dimension of space than the boundary does. But it has the same number of dimensions of time, namely

one. So we don't need to keep saying that over and over again. We can just say five-dimensional space in the bulk, four-dimensional space in the boundary, or, or or whatever, and space-time just goes along for the ride. Roman Leventov says, In the context of the show with Barry Lower, specifically when you discuss how the laws of physics can explain anything, do I understand correctly that Deutsche and Marletto's philosophy of science and constructor theory is in the middle between humian and anti-humian views?

That is, counterfactual principles are event-producing, real, and serve as explanations, whereas dynamical laws, which can, as Deutsch and Marletto conjecture, be derived from fundamental counterfactual principles are mere descriptions. I think this is probably a super interesting question, and I don't know the answer to it. Sometimes I'll just read off the question because I think that the question is interesting, even though I have nothing interesting to say about it. In this case, I don't understand enough about what Deutsche Marletto would say. Kiara Marletto was, of course, a guest on the podcast, and you can go back and listen to that.

She's a proponent with David Deutsch of what is called Constructor Theory. where instead of thinking of the laws of physics as saying, from one moment and all the information of that moment, I will tell you what will happen at the next moment. They speak the language of what is possible and impossible. I suspect that, so a constructor is something that can, that would make something possible from a pre-existing possible thing. I suspect that it could go either way. You know, the humian view is that the laws are just convenient ways of talking about the world. The anti-humian views that the laws have an independent existence of their own, and they have some sort of generative role in bringing the world into existence.

So I'm not sure I understand constructor theory well enough to answer this question, but to the extent that I do, I could imagine playing that either way, that you could imagine that the space of or the division of things into things that can happen things that cannot happen, itself has an independent existence and brings things into existence by its continual enforcement of what is allowed to happen and what is not allowed to happen. Or that certain things just happen and that we speak about possible and impossible as a convenient way of summarizing what it is that happens. So I don't think that there is a clean connection there, but maybe one of them would say something different there.

Simon Leubinus says. Various spiritual and philosophical traditions claim that the universe has a non-dualistic nature, that ultimately the universe and everything in it is one indivisible thing, and that the apparent diversity we see is mere illusion. I'm not suggesting that ancient philosophers actually discovered quantum field theory, but theology aside, is it scientifically valid to think of the wave function of the universe as the only one thing that actually exists? Can we even think of individual objects as being separate from each,

other if ultimately everything is a manifestation of a single field. Well, I think this is a slightly tricky question because we come to it with pre-existing baggage about what it means for things to be separate or connected from our everyday life. And when we talk about fundamental physics or the ultimate nature of reality, that intuition is going to fail us, right? It's just not going to quite count. So, I mean, think of it in a trivial way. If I have a red block and a blue block, Now I have two blocks, right? But also I have one thing, the set of those two blocks. So is it one thing or is it two things? Well, it's certainly both. It's not like it isn't one thing. I have a set of things and that is a one set, okay? But it's also clearly divisible in an easy way. And the world is like that. You know, the world is clearly divisible in a pretty clear way. We do it all the time. It is certainly at the emergent higher level that we do it, but it's still. something that we do. I suspect the universe is just like that. I suspect that indeed, the wave function of the universe is a way of talking about the universe as a single unified monistic thing,

but that it is also very useful to divide it up into subfactors. In fact, I wrote a whole paper about it with Ashmeet Singh called quantum myriology. So I think that the categories of being fundamentally one or being fundamentally multiple, don't fit very easily onto the question of what the universe really is, would be my take. Christoph Pironsky says, I love my cats. I enjoy their unique characters and admire their ingenuity, but at the same time, I see their intellectual limitations. As they can't grasp complex concepts, it seems that the jump from a cat to human intelligence is a qualitative one. then there are quantitative differences between individual people's intellectual abilities.

Do you think that there is another level, a qualitative jump above human intelligence, or do you think that for some reason, language, ability to generalize, being universal touring machines, we are at the most general level already, and any progress from there is just scaling? I don't know. It's a very good question for a couple of reasons. One is, I am not 100% sure that there is a qualitative jump from cat to human intelligence. There definitely is a jump, but I guess if I were really pressed, I might think that a really, really, really noticeable, big, obvious quantitative jump

is indistinguishable from a qualitative jump. If cats have an ability to reason abstractly or imagine the future, but that ability is just very, very, very, very primitive and limited. And we have those abilities that are just much more developed, then it's not a qualitative difference. It's just a difference of degree. So I'm not 100% sure that I buy the premise of the question. There is a qualitative difference between human intelligence

and the intelligence of a water molecule. I think that that is true, because the water molecule has zero intelligence. But I can imagine that there are higher forms of intelligence that really, once you get down to it, are just capacities that we have, but enormously stronger capacities, right? I mean, we're not very logical. We're not very rational. We're not very good at math. There's a whole bunch of ways in which you could easily imagine improving on human intelligence. Now, if there is a way to be intelligent that is qualitatively different, then I guess I, I, might have a difficult time imagining what that is. So on the one hand, I can't rule it out, but on the other hand, I don't know what it would be. So my suspicion is that it's just not there, but that I can imagine ways that we could be more intelligent and so much more so that it would seem like a completely different kind of thing from our point of view. Chris A. says,

somewhat moot now, as he's thankfully been voted out, but had Bolsonaro been re-elected in Brazil, would it have been ethical to assassinate him, to prevent his continued wanton destruction of the Brazilian rainforest on which so much of the world's biological diversity depends? I think there's two ways to think about a question like this. One is in some abstract philosophy land and the other one is in the real world.

In the real world, no, it would not have been ethical to do that. Because if you have a principle that says that elected officials who you think are going to do terrible things can be assassinated, then a lot of people are going to take that principle and run with it to assassinate people you don't think should have been assassinated. It's not a matter of deserving or not deserving to continue living. It's a matter of who gets to decide, right? And the idea that an individual should just take it upon themselves to make that determination is one we do not want

to spread around commonly. You know, if I can imagine, I don't think there's a lot of of hard and fast rules in situations like this. I can imagine literally a end of the world scenario where you have to assassinate somebody to prevent the end of the world and nobody else thinks that they don't see it clearly so they don't get that and you have to do it yourself. Fine. I don't think that any current leader of a country is quite in that category. In abstract philosophy land, I should say the other thing is, of course, you could be wrong. You could be sure that this person is going to cause tremendous harm to the world, but maybe you're wrong. So that's why we have institutions and mechanisms for doing things like this.

And it would also be different if the person were a dictator and an autocrat versus someone who was elected. You can argue about whether or not the election is fair, et cetera, et cetera. But in principle, if the people vote somebody in in a democracy, then I would not be in favor of people in the minority who lost. assassinating that person if they thought that their policies were going to be disastrous. But then again, yeah, so to get to perfect philosophy land where we grant ourselves the ability to know with certainty that this person really would lead to the destruction of the world, then, sure, go ahead and assassinate them. But I think that the difference between abstract philosophy land and the real world in this

kind of example is really, really big and important. so I don't think that the in-principle conclusion carries much weight in real-world deliberations here. John Perry says, I've just been catching up and listened to your Secrets of Einstein's Equation podcast. It seems inconceivable to me that Euclidean geometry was considered to be the answer without serious question for so long. The sphere, for example, would have been a well-known object Euclid himself. With the obvious level of historical intellect available, why do you think is survived as the single solution for someone? so long. Well, I would recommend that in addition to listening to the podcast, you buy the new book,

the biggest ideas in the universe where I discuss exactly this. So sure, in three-dimensional Euclidean geometry, you could imagine or even construct a two-dimensional sphere embedded in that three-dimensional Euclidian geometry. You construct the set of all points, fixed distance from some single point. There you go, a two-dimensional sphere. And you could talk about the geometry of the But that's exactly the point. The point is you don't need a new set of axioms for geometry to discuss two-dimensional spheres, right? You have Euclidean geometry, and the two-dimensional sphere is a subset of the three-dimensional Euclidean geometry.

That was the difference when people finally stumbled across hyperbolic geometry, because hyperbolic geometry, negatively curved geometry, if you have a, I don't know, I mean, there's different mathematical terms for this, but if you have a maximally symmetric, hyperbolic, negatively curved, two-dimensional geometry, you know, we always say it looks like a pringle or a saddle, but those are not, those are just sort of gesturing at the actual geometry, which is supposed to be completely uniform. That geometry, a uniform negatively curved three-dimensional surface, cannot be embedded in three-dimensional Euclidean space, but it still does have a geometry of its own. So this was an example, not just of a geometry that you derived from looking at a subset of Euclidean geometry, but a wholly new kind of thing.

That's why it took a long time to do it. And then, of course, once you do it, you realize, oh, I could have done this with spherical geometry also. So in other words, sure, people knew about spheres, but they didn't think that you needed a separate kind of geometry to talk about them. Paul Cousin says, how many back and forth do your papers have to make on average between you and your reviewers?

On which parameter does this depend the most? Topic, length of paper, prestige of the journal, etc. It's very different. You know, it's not like there is some median that you stick pretty close to.

I've had plenty of papers just get accepted right away. I've had papers get rejected. Happily, more accepted than rejected. But sometimes they're rejected in such a way that clearly the referees misunderstood something, or you made a mistake and you can fix it and then resubmit the paper. So it's usually not that many back and forth. Like, I don't want to engage

in seven rounds of revising and resubmitting. I would just pick another journal and try again, or even like not even bother. Like in these days, when you have the archive, when you have online dissemination of papers, to me, as an author, getting the paper in a journal is much less important than it used to be. There's better ways. Even when I want to look at at my own papers. It's easier for me to find them on archives than to find them on my own computer. So certainly that's also true for other people as well. But in terms of the parameter that matters the most, in terms of getting rejected, there's some higher criterion in physics for certain journals like nature or physical review letters. But honestly, physics has a much

flatter notion of journals than many other academic fields do. In many academic fields, your papers are just evaluated by which journals they appear in. Certain journals are really, really hard to get into, and getting a paper in there is awesome. Others, anyone can get a paper in. Whereas in physics, like the main journals, like Physical Review D, have super really good papers and also extremely boring run-of-the-mill papers in them. So it's less important to go for those prestige journals in physics than in other fields. It does matter how imaginative, let's say, I'm trying to think about value-neutral terminology here, how creative or non-mainstream your paper is. In many ways, interesting papers are more likely to get rejected. And that sounds bad, but it's actually completely

sensible. If I just come up with a model of dark matter or inflation or whatever, that is not super It just plays by the rules. It does the usual thing. I show that it fits all the constraints and blah, blah, blah. That paper's not going to get rejected. That's going to get accepted. It's super boring, but it's also correct in its assumptions. Under its assumptions, the conclusions follow. They're going to publish it in a regular old journal. Whereas if I try to be dramatically different and I say, well, what about this brand new idea? A lot of people are going to look at it and go, no, I don't like that brand new idea. And just read. So this is actually, and not just me sour graping, there's, there are studies that have shown that highly, highly influential papers are more likely to have been rejected the very first time they went to a journal than boring dull papers. So, and I'm not even sure how to fix that, but I think that it's something we need to keep in mind when we think about the role of the refereeing system. Declan Brennan says, does history have a direct.

Some people looking at the Ukraine situation think that Russia doesn't realize the era of colonization is over. Others feel that history has no more of a direction than does evolution. If it doesn't have a direction, does it at least move through phases? If it has a direction, can individuals influence it, or are we all just flotsam on the tides of historical necessity? I don't think that history has a direction in any especially useful sense. No, I mean, sort of like evolution. You know, if you follow the evolution of the whole biosphere, there are certain patterns that emerge, and you can call those directions. I mean, there's sort of increasing diversity of species, maybe up until a big collapse, right?

A disaster hits, and a lot of species die off, and then it starts growing again. So do you want to call that a direction? I mean, I don't really know. I don't really – I think that the idea of a direction implies that either there is something directing it, or that there's some inevitability about what is going on because there's a direction, right? Like if you say, oh, colonization used to be all over the place, now we don't do that anymore, there's a direction of getting rid of colonies. Well, you know, that might be an empirically true fact, but it doesn't have any control, right?

It doesn't actually have any influence if one country wants to have a colony and no one stops them, then they're going to get a colony, no matter what the rest of history is doing. So does it move through phases? You know, it's absolutely crucial to history that we can simplify it a little bit. A history book is not simply a list of every event that happens during some period of human history. Like that would not be sensible. We extract from that. Remember, when I talked to Brad DeLong on the podcast, he's extremely upfront that he has a grand narrative that he is trying to use as a lens to view the economic history.

of the long 20th century. And that's perfectly good. That's why historians have a job, because they can notice different trends, different phases that things go through. But it's usually hard to predict ahead of time what that's going to be. We can say after the fact, oh yes, here is a single historical era or something like that. Malta Ubel says, given the assumption that the world was created as a random quantum fluctuation, what is the probability that it just now happened rather than happen in the past, and from there dynamically evolved to the current state. Well, I don't think this is quite a well-posed question. I'm not sure what it means to say the assumption that the world was created as a random quantum fluctuation. I know of no such

assumption. There might be random quantum fluctuations within the world, but I don't know of any way to have the world be created as that. I know that people sometimes talk that way, but that's because people are really sloppy. We don't. know what happened at the creation of the world. And to say that it was a random quantum fluctuation seems to imply that it was a fluctuation from something to something else. But if it's literally the creation of the world, then there was nothing pre-existing for it to fluctuate from. So that's not what it is. I mean, how long was it non-existent before it randomly fluctuated into existence? That's not a sensible question because there was not even time

before that moment happened. So I don't think that that's an idea that is really on the market. The world was created as random quantum fluctuation. There's absolutely an idea on the market that the world had a beginning. But if the world had a beginning, the world, in terms of the whole universe, that just means that there's a first moment of time. It doesn't mean that that first moment of time fluctuated out of a pre-existing nothingness. That is literally the wrong way of thinking about it. it's no more or less than the statement that the universe had a beginning. Just say that. Don't say it came out of nothing or anything like that.

As far as the probability is concerned, yeah, I don't know. I could easily imagine a whole bunch of different quantum states that give rise to different probabilities. In the quantum mechanics that we know and love, there is a probability associated with different measurement outcomes given any one particular quantum state. but if you don't know what the state is, you have no idea what the probability of different possibilities are. So again, I think it's a little bit of an ill-formed question.

Connor Schaffrin says, Unless I've miscounted, you've only had three episodes that discuss climate change as a main topic, with the most recent being three years ago. It seems like there are a lot of smart people with expertise in climate science who are saying the climate change is the most urgent issue facing humanity at the moment. Is there a reason you don't talk about it more these days? Well, there's zero connection between what I think is the most urgent issue facing humanity and what I need to have on the podcast. Otherwise, you know, I wouldn't have podcasts about music and wine tasting and things like that.

There are far more urgent issues facing humanity. That is not the decision procedure I go through. It's more like, is there an interesting thing to talk about? Is there something we can learn from having this conversation? And obviously, climate change is super duper important and super duper interesting. but I'm not going to do a podcast just to sort of reassure ourselves that we're virtuous about it, just to say, you know, I've never believed in the therapeutic value of complaining. When Donald Trump won the election in 2016, you know, there was a period where, like,

you couldn't have dinner with people without it just being like, oh, no, the world is ending. Donald Trump is president, things are bad. And I agreed that things were really bad. But my response was always, okay, well, what are you going to do about it? Like, why are we having this conversation? Is it just to get it off our chests? Like, we just feel bad. We want to kind of yap about it, ineffectually.

And I just never saw the point in doing that. I will talk about democracy a lot. And I think that democracy is in trouble. But I don't just have a whole bunch of podcasts saying democracy is in trouble. This is bad. I try to analyze the ways in which democracy is in trouble. whether democracy could be improved, whether it can work better. There's a whole bunch of intellectually interesting questions there.

When it comes to climate change, there's a whole bunch of intellectually interesting questions about climate science and atmospheric science and so forth. I'm not especially an expert on those myself, and I'm not quite sure which ones would make good podcasts. But I don't want to just have a podcast saying, climate change is coming and it's bad. I assume that over 95% of my listeners already know that.

and I have zero interest in just telling them something they already know. That's not what we're here to do. Tarun says, in your recent discussion with Barry Lower, you seem to agree that the humian view in relation to the laws of nature is the correct one, in comparison to what you called the God view. However, I was then surprised to see that in the last Phil papers survey, the majority of philosophers stated that they accept or lean toward the non-humian view. This is despite the majority having atheistic views and subscribing to naturalism.

Why do you think that is? So I think that I didn't want to call the anti-humian view, the God view. That was Barry's terminology, and he was being a little cheeky in doing it, because we're both humians. You know, we're all humians here, just have a good slight poke at our anti-humian friends. I don't know of any anti-humans who call it the God view. There is, you know, a family resemblance behind the idea that the laws of physics have a separate identity to the physical universe and the idea that God has a separate existence in addition to the physical universe, but they're not necessarily connected in any way.

There's plenty of atheists who are anti-humians, okay? So don't take the phrase God view too literally, is what I would say. James Allen says, briefly in your debate with William Lane Craig, you mentioned that modern physics doesn't use Aristotelian notions of cause and effect. Is there a place in the literature that clearly expressed that view? Such a citation would be valuable in the corners of the interwebs where atheists hang out. Yes, it is the book The Big Picture by Sean Carroll.

I can highly recommend it. With one footnote, I talk a lot about cause and effect in that book, and I talk about Aristotelian notions as well. But because people continually misunderstand this, let me be very clear. I am not an expert on what Aristotle himself actually said, nor do I really care what Aristotle himself actually said. That's not the point. I am using Aristotle as an exemplar of a tradition that puts cause and effect front and center in our understanding of the dynamical evolution of the world. And furthermore, in front and center in our explanatory framework of the world.

I mean, this tradition goes all the way up at least to Leibniz and the principle of sufficient reason, right? So it's not Aristotle himself that is really, really important here. What's important here is the idea that causes our forenizabeth, fundamental in the universe rather than higher-level emergent phenomena. That's really the distinction that is important to me in that book. Jimmy, J-I-M-I, says, is there an asymmetry between position and momentum in the Hamiltonian? If so, doesn't that mean that there aren't as practically,

they aren't as practically equivalent as it sometimes seems? So, yeah, if you think about Hamiltonians in physics, the Hamiltonian is at some level, just a simple way of saying what the energy of the system is. But there's a specific way in which the Hamiltonian comes about, namely when you're using as your coordinates on the space of all possible states, positions and momentum. Okay?

So the Hamiltonian is a function of position and momentum, and it's the function that says, here is what the energy of the system would be if it had this position and this momentum. Read more about it in the biggest ideas in the universe where I talk about Hamiltonian mechanics. As far as there being an asymmetry in there, it depends on what you mean by the Hamiltonian. In Hamiltonian mechanics, you're allowed to write down any Hamiltonian you want, and position

momentum are perfectly symmetric. You can write down any function of X and P or any function of P and X just as well. Those could be Hamiltonians. In the real world, the Hamiltonians we actually use to describe physical systems are not arbitrary. They're kind of specific. And in those specific Hamiltonians, there is an asymmetry between position and momentum. One simple way of saying it is particles will interact with each other, more strongly at least, when they are nearby in position, right? They bump into each other or they have an electromagnetic or gravitational effect on each other, et cetera, as a function of position. The interaction there has nothing to do with whether their momenta are close to each other, right? There's no principle in the real world that says if two particles

have the same momentum, they will interact in some strong way. That's just not a thing. And that difference can be traced to the fact that P and Q, momentum and position, appear differently in the Hamiltonian of the real world. Joshua Hillerup says, do you think poetic naturalism could be applied to ethics? For instance, could there be some sort of fundamental consequentialism that's about as useful for making actual ethical decisions as the standard model is for engineering a building? But it could be used to build up other ethical theories more specific to given domains in a similar chain to what we see in science. I think that's very possible. You know, I think that Joshua Green actually gestured in this direction where he tried to say that he didn't proceed as much of a difference between

utilitarianism and deontological theories as some people do. And even Will McCaskill, you know, said that we can sort of consider the median or some superposition of consequentialism and deontology. However, I don't necessarily know that the fundamental level would be consequentialism. I mean, I think the way that I would put it is, what you could say is, is there some fundamental moral theory? And it doesn't need to be objective. It can be something constructed. That's fine. But is it supposed to apply to all situations, all circumstances, and be universal in some sense, even if not everyone agrees with it, but some people do?

If there were such a theory, but that theory were so wickedly. complicated in practice that we would, you know, get in trouble if we had to sit down and work out what the consequences of that theory were in any particular circumstance. So instead, we used rules of thumb and approximations at higher levels. I think that's extremely possible, whatever that fundamental level actually is, and probably something like that is what we actually aspire to do in the real world. Paul C. Conti says, I was wondering now that you're at Johns Hopkins, if you would be given any preference in submitting an observation proposal for the JWST? If you could submit an observation proposal to the committee,

what cosmological or astrophysical question would you consider investigating? Well, I'm allowed to submit observation proposals. As far as I know, there is no preference for Hopkins faculty for JWST. I don't know if you're an astronomer yourself, but very often universities or research, institutes will buy a fraction of a telescope, right? So you have a big telescope that has many institutions using it, but, you know, like the Keck telescopes in Hawaii, were joint between Caltech and the University of California. So there's different University of California campuses,

and there's Caltech, and the professors at those institutions absolutely get preference when it comes to submitting proposals. But the JWST is a NASA facility. So, If anyone is going to get preference, it's going to be NASA employees. I don't even think that they get preference, to be honest. I think it is supposed to be a national or even an international good, the space telescope, and so anyone can apply to it. I myself have zero plans on proposing anything like that. I'm going to leave that to the experts.

You know, it's the kind of thing where you've got to know what you're doing. It's one thing to say, I would like to observe something, but there's a lot of real, knowledge of how it is done, practical knowledge, right, that you need to learn the hard way by training with someone who knows what they're doing and learning and stuff like that. And as a theorist, I haven't done any of that. So I'm going to leave that to the experts. If I have a theory, I want tested, I'm not going to put in a JWST proposal. I'm going to go to my friends who are good at this and say, you should test my theory.

That I might very well do. Nalita S says, what is from your perspective preventing us from finding dark matter given its immense influence? Do you think we will ever be able to spot it like we did other elementary particles? Well, that's certainly the hope. You know, there's no, as Martin Rees has said, former Minescape guest now that I think about it, it's not surprising that there is dark matter in the universe in the sense that all dark matter is, is some particle that has a substantial abundance of mass in the universe that doesn't interact either through the strong interactions or the electromagnetic interactions.

How hard is that? That's not, it's very, very easy to come up with ideas or particles like that. Indeed, neutrinos are absolutely particles like that. They are not the dark matter that we know about in cosmology, at least we don't think that they are, because they move too fast. Okay, they're too low mass and high velocity to fit the detailed properties that we think dark matter has. They would be hot or warm dark matter, whereas cold dark matter is what fits the data, but they are an example of particles that are dark and are matter, so there you go.

And we've detected them also. So we absolutely hope to spot it. We've talked about that on the podcast with people like Lina Nasib, if you want to go back in the archives. But we haven't spotted them yet. So we're still looking, I don't know. You'll know. If we find it, you'll definitely know. Brent Jones says, I teach AP chemistry and AP physics at a rural high school in West Virginia, and I absolutely love going to work every day. Now that you're teaching again, I'm curious to know what you love most about teaching. Oh, it's probably the wrong time to ask me that, as I'm kind of swamped with teaching right now. There's a lot of work involved in teaching, apparently. Who knew about that? But, you know, there's so many things that I also love about it, and I can't deny that. You know, I love it when I may be to say something that suddenly makes a little light bulb go off in a student's head, especially when that light bulb is, oh, no, I've been misinformed about something my whole life. You know, I'm teaching an upper-level undergraduate seminar on the philosophy of physics, and there's plenty of places where you can point out that, you know, here's what we get taught in

our physics classes, and here is the completely different truth. And you see the students go like, oh, my goodness, yes, I was taught that. You're right. And so that's always fun. It's also just fun to talk individually to the students. You know, to me, the years of your undergraduate education are, in many cases, the most important and formative of your life because, you know, you go from having been in the same environment or very, very similar environments for most of your growing up,

and then suddenly you're in a completely different environment with completely different friends, learning new things at a high level, doing different things, and then that sort of sets you on the trajectory of the rest of your life. So I worry a little bit. You know, you talk to students, and you always worry that you're going to say something that will turn out to be really crucial for their life, and you were just, you know, saying it kind of randomly. So there's a responsibility there,

but I do like the idea that I can help students navigate this very, very important and fraught period of their life. lives. I have usually, in my teaching past, been teaching upper-level physics classes, where students were more or less on a trajectory already, you know, either graduate students or very upper-level undergrads. Now I'm teaching a more diverse set of undergraduate students at different levels of their career, and so a lot of it is like, yeah, I have no idea what I want to major in yet, right? And there are a couple words here and there can have a big impact, so it's something to be to take very seriously.

says, according to Black Hole Hullography, does Hawking radiation convey information about the state of an object when it hit the event horizon only, or rather, a history of all of its states inside the event horizon until it hits the singularity? Well, you know, technically, there's no difference

between those two things. If you believe that information is conserved, which is one of the motivating ideas behind holography, etc., the information from one moment to the next is the same information, just sort of scrambled by the historical evolution. So knowing the whole universe, a laplace's demon at one moment of time, is equivalent

to knowing it at any other one, and that goes also for objects falling into black holes. So we talk about the quantum state of the black hole, as if it was a constant thing. But even if it's evolving, it goes from one state to another in a way that is strictly determined by the equations. So that set of information, whatever it is, however you want to present that set of information, that is what is supposed to be taken away by the hawking radiation, if information is conserved. Redmond says, on atheism does a strict materialist who rejects not only traditional concepts of a deity, but any higher organizing principle whatsoever, assume the burden of proof? Well, short answer, no. Longer answer is, what do you mean, the burden of proof?

Burdens of proof are an idea that that's a concept that applies in a legal proceeding, okay? Prosecutors have the burden of proving that the guilty person really did it beyond reasonable doubt in a civil proceedings. The burden of proof will be different and so forth. If you're just talking to someone and you are mutually trying to find the truth, no one has the burden of proof. You should be working together, okay? It's very, very, using legal proceedings as a paradigm for finding the truth is a very, very bad way of finding the truth. Let's put it that way. There's much better ways of doing it as an intellectual endeavor. If what you mean is, does rejecting traditional concepts of a deity and of high organizing principles somehow deserve less a priori credence than assuming a deity or whatever, then no, that doesn't seem at all right to me. If anything, assuming a deity is one extra thing to assume, and therefore you should have a reason for doing it. But I wouldn't call that reason a burden of proof.

Jeff B. says, imagine that a simple object like a paperclip is floating in empty space. For the sake of arguments, suppose that the paperclip is shielded from interacting with the environment in any way. Now we could imagine waiting some amount of time and observing the paperclip. Am I correct in saying that the longer we wait, the more branches will be created when the paperclip is observed. If so, is this mostly due to the larger number of radioactive decays the paperclip has undergone, or is it mostly due to the paperclip gradually spreading out over Hilbert space? You know, I'm always a little leery of questions involving counting number of branches. If the number of branches is infinite, there's no way to count.

You can integrate over certain sets of branches and get a weight that you can apply to them, but the total number is infinite, so it's not like there are two more branches in some period of time or anything like that. The interesting part of your question, the quantitative part, I mean, I do think that in some sense, you know, at least morally, yes,

more branches are created the longer you wait to observe it. You don't have to put it in a box to make that true. You don't have to shield it from interacting with the environment. Just let it interact with the environment and branches will be created all along.

And the number of branches created are not any different if you're just looking at the paperclip the whole time than if you're letting it float freely in space. And both of the effects that you mention, a spreading of the wave function of the paperclip itself, and the fact that there are radioactive elements within the paper clip, they will both contribute to branching the wave function of the universe. How many of them? Yeah, I have no idea. As I said, I truly don't care about these questions about counting the number of branches. That's just not where the interest to me lies. Maybe that's an answerable question, but I just don't know what it is.

Chris Murray says, in a closed universe, if you put many black holes close together in a straight line, all the way around the universe, could they merge to become a black tube with a stable cylindrical horizon? And what would that be like? This is a very interesting question, because the short answer is no. They would not be a black tube with a stable cylindrical horizon. But it turns out that that answer depends on the number. of dimensions of the universe and also on the size of the universe. So there are called, there are things called black strings. So, you know, a black hole, but rather than

being a sphere, it's like a one-dimensional tube, just like you say, not in our three-plus-one dimensional space time, but maybe in compact dimensions of space, you could have such a thing. And the reason why I would not be stable is you can increase the area just by beating it off into individual black holes, and that increases the entropy, and that's what you want to do in terms of what black holes tend to do. You always want to increase your entropy. Casey Mahone says, experiences of aesthetic beauty can sometimes feel transcendent and divine, but from a materialist standpoint, these experiences must be rooted in our evolution. What do you speculate is the evolutionary basis for these sorts of overwhelming mystical or

artistic experiences? Well, I don't know, is the short answer, But I can at least say that it's completely unsurprising to me that there are such mystical or artistic experiences. You know, the human brain is a complicated place. Evolution is a complicated process, right? It's not a straight line design in order to fulfill some goal. The shifting demands of our environment and the situation we're in put different evolutionary pressures on our brains at different times. And also, because it's not designed, we have to work. as previously mentioned, with this framework of looking at random fluctuations in the underlying

blueprint from the DNA and seeing how they play out in the real world, which is a very hit or miss way of doing things. So we end up with systems in biology, whether it's the brain or otherwise, that are, you know, in many ways not well designed, like enormously powerful, but a lot of redundancy in some places, fragility in other places, inexplicable wiring choices in yet other places and so forth. So it's not that we are evolutionarily chosen to have transcendent experiences, but maybe there is some reason, or even maybe it was just random, that transcendent-like experiences played a good role, you know, being happy, not being drawn down or depressed by the moment, sort of being able to think more widely about big questions. These are all

things that I can imagine have a good evolutionary purpose to them. So I don't know the specific answers to this question, but the brain is a complicated place and it makes zero difficulty in my mind to imagine that something like that could evolve. Floyd Aldrich says, could you explain how a dragon would breathe fire in the fantasy world? So this is another one. I think I'm getting more and more interested in picking questions to which the answer is, I don't know. Or you shouldn't ask that question. But for this one, you know, this is, I don't want to read too much, Floyd, into your

asking of the question, but there's a whole genre of discussions that I'm very familiar with having worked as a consultant on Hollywood movies and so forth, which is taking something that appears in a fantasy or not very grounded science fiction story, and ex post facto, trying to come up with a sciencey plausible explanation for it. Okay? The real answer is because the author wanted them to. That's how a dragon can breathe fire. Dragons don't really exist.

They couldn't be able to fly if they did exist. And so why not have them breathe fire? It's kind of fun, right? That's the actual real answer. Now, if what you mean instead is, what is the most biologically, physically plausible way to get a biological creature to breathe fire that I also don't know the answer to,

but it's actually not that difficult to believe. I mean, probably, just for safety considerations, what you would want is not to actually be able to breathe fire, but to belch some sort of highly flammable gas in an environment where things light on fire all the time by themselves because there are sparks or electrical currents, currents or something like that, right? That seems to be a little bit more safe than actually starting a fire inside you and then

breathing it out. That doesn't sound very safe at all. And if that's the way you're doing, if you're just belching out gas, we belch out gas all the time. There's no special evolutionary reason why the gas should be highly flammable, but if you really, really, really wanted it, I could imagine that an organism could do that. So that would be my guess. There's probably other ways to do it.

An even better way, if you were able to design, rather than just build it biologically, what you might want is to have two gases, which are separately perfectly stable, but then when they're combined, they become highly flammable. That happens all the time. It happens in rocket ships, right? Hydrogen and oxygen can be kept separate, but then when you put them in the same region of space, they burn very, very easily. So that might be another way for dragons to do this. I don't know how dragons get a large collection of hydrogen in them, but it is a fantasy world after all. Christopher Bax says,

I recently read a New York Times article about a German heiress, leading a movement to have massive inheritances go almost completely to taxes and redistributed by the government. The thought being that redistribution versus philanthropy reinforces existing power structures by allowing the ultra-wealthy to decide where the money goes. I like the spirit, but feel like it puts a lot of faith in government to use this money well and actually reinforces international power dynamics by keeping money in countries with more ultra-rich people.

Well, it's always, you know, compared to what? Okay, so I presume that what you're imagining or contemplating is comparing some very severe kind of inheritance tax that when people die, their fortunes are heavily taxed, versus letting the wealthy family keep it and decide how best to philanthropically spread it around. And I think that, you know, I don't want to eat the rich or kill the rich or anything like that. As I've often said, I'm in favor of rich people. I wish I were a rich person. And I'm okay with allowing rich people to enjoy their money to some extent. At the same time, I do think that there should be inheritance taxes.

And I think they probably should be a lot more than the... there are. And I think that the argument that, well, then the government has to use that money well is pretty easily defeated by just looking at how the government would typically use that money versus how a wealthy individual might use that money. Many wealthy individuals are very good at doing philanthropic good to the world, but it certainly has the failure mode that you have someone with quirky interests, right? They have a lot of money. and they're going to spend on things that they think are interesting, and that's their right to do so.

I'm not against that, but the government has different interests. The government has the duty of thinking about how best to spend all of the money on all of the needs that people have and do so in a responsible way. Does the government always do a good job at that? No. But at least that it's their job, and we can try to make them do a better job at it. So I'd be very much in favor of all sorts of higher taxes on richer people, and then separately work to make the government spend the money as well as we can.

It's a very down-to-earth kind of boring policy proposal, but I'm in favor of that. Peter Solfest says, In episode 200, you seem to make the argument that considering yourself as a Boltzman brain is cognitively unstable. So we shouldn't think of ourselves as Boltzman brains and thus should assign lower credences to theories that predict there are a lot more Boltzman brains than other observers. I follow the logic to not thinking of myself as a Boltzmann brain, but why should that give me the leverage to lower my credence about cosmological theories that predict them? In other words, I get that I should behave as if I'm not a Boltzman brain for practical reasons, but why should that give me theoretical grounds to make any statements about which theory is better? Well, I'm not sure I quite buy the difference between the two things.

Behaving as if you're not a Boltzman brain for practical reasons, but not theoretically accepting it. I think that you should behave in accordance with whatever view of the world you actually accept as likely to be true. And the point about the cognitive instability of Boltzmann brains is it's no way to go through life accepting that because you can draw no conclusions. You do not know anything about the world if that's the cosmological scenario you accept. I don't think there's a difference being saying, I think this is true, but I'm going to act as if something else is true. I can't imagine a principal justification for doing that. You might be in trouble if we lived in a world where there was no better theory, right? There was no way to assume that we're not Boltzmann brains and get a coherent picture of the world.

But there is. It's pretty clear that we can assume we're not Boltzman brains that there is actual regularity in the world. There's a low entropy pass that we evolved from and all that stuff. All that fits the data really, really well. So you do have the ability to construct cosmological models that are both potentially true and sensible and fit all the data. I'm going to advocate doing that. FIRAS says, I've noticed that whenever scientists talk about the state of the universe and associated big theories, they never really add the small asterisk that it's all from the perspective of humans and from our location in space.

Do you think this creates a form of scientific absolutism, where we fail to recognize that the rules that govern our reality, only really makes sense from our observer status from our perspective? Well, yes and no. I wouldn't put it that way. I mean, the short answer there is no, but it is absolutely true that we are highly conditioned on what we are able to observe. Sure. There are some things that are easier for us to observe, easier for us to notice than other things, and that guides our scientific theorizing. There was a reason why Aristotle and Galileo and Newton came up with their theories before we came up with quantum mechanics and the standard model and general relativity and things like that. Our knowledge of the world was much more limited back then. But it's not a

kind of absolutism. Newton, I don't know what Newton thought, but he should have thought that, you know, maybe someday we'll know more and change our minds, right? That's what we do as scientists. We do our best to understand the universe, to uncover the patterns, the laws that it obeys. and we imagine that maybe those patterns and laws continue to be true elsewhere, and then we test that idea. We say, if that's true, what would we predict? What would we observe? And we go looking for it.

That's how science works. And we need to be careful of our biases, et cetera, but we got to work with what we can work with. There's no absolutism about it. Crather-Luca says, why do you think many worlds is still not the consensus view for the foundations of quantum mechanics? Well, I do think that there's perfectly good reasons why many worlds should not be the consensus view. I don't think if they're right, but there are decent reasons.

I think the basic reason is the simple fact that the metaphysics, the underlying view of the world presented by many worlds, is radically different than the view of the world that we're familiar with from our everyday experience. And on the one hand, you should expect something like that? I mean, who's to say that the true underlying theory of reality should, in any sense, map in any easy way onto our everyday experience. But on the other hand, when you actually have a proposal for the underlying structure of reality, you should be cautious, right? The thing about many worlds is it's a very easy theory to state. There's a vector in Hilbert space and evolves under the Schrodinger equation.

But there's a lot of work to be done in connecting that simple underlying theory to our observatory. and our experiences. And there's an obvious way to go wrong if we think we know already what our observations and experiences are. Look, I wrote a paper about deriving the Bourne Rule from the many world's interpretation of quantum mechanics with Chip Siemens, we've already mentioned. And I think that I agree with the logic we put forward there. But I have to be honest in that we knew the board rule ahead of time. So we weren't going to write a paper deriving a different rule, right? So it's easy to fool yourself in those situations. And exactly because the fundamental structure of reality suggested by many worlds is so different than the world we observe, it's perfectly okay to be

cautious, to be tentative about it. And other theories map on more directly to the world. In a hidden variable theory, the reason why you see particles is because there are particles. That's very basic. In an objective collapse theory, the reason why wave functions seem to collapse is because they collapse. And that makes the theory uglier and more complicated and harder to generalize, but also easier to understand in a very direct way. So that's okay. Eventually, everyone will be on the side of the angels and agree that many worlds is right. Steve Glor says, do you have any anecdotes about your interactions with William Lane Craig? I've seen quite a few WLC debates, and yours is probably the one that has challenged his scripted talking points the most

effectively. You had some help from Alan Gooth, as I recall. What are your recollections of the times you have debated him? Any chit-chat before or after? Thinking back, are there any additional things you wish you had said or things you would now put differently? You know, we didn't chit-chat that much. We chich-chat a little bit. We didn't like pre-plan anything for the debate. He's debated many times. He has a system, you know, we're not going to deviate from the system. It's either when I get invited, is he's like, do you want to do this or not? You know, there's no negotiations. And we only debated that once. So I don't have repeated interactions. We did go out to dinner afterward, but we got to dinner with like 20 people. So even there, there was not a lot of chit chat. He's very

gracious. You know, he complimented me on my debating at the end of the whole thing. I didn't convince him of anything. You know, he later wrote a bunch of blog posts and did interviews explaining why I was wrong, which is not surprising. As far as what I would have done differently, I didn't don't think I would have done that much differently, but I would do it differently, were we to do it again? I don't think we will. We have no plans. You know, life is short, and I did that once. I'm not planning on doing it again. But if I change my mind and the world changes, then we do do it again, I would approach it very differently, not because I think I shouldn't have approached it the way I did, but because I already did that. So there's a different way to approach it. And the approach I took in the actual debate was

I'm not interested in winning the debate in the sense of, you know, a high school or college debate competition. I was on the debate team in high school. I know what it means to win, you know, to go point by point by an argument and refute the arguments, et cetera. But that's a very, very stylized way of discussing things. It has nothing to do, as we already said previously with the burden of proof and legal proceedings. It's not about the search for truth, right? So my goal in that debate, was less to sort of score points and more to explain myself, more to be understood, given that there is an audience. And some of those, I mean, it was literally at the New Orleans Baptist Theological Seminary, right? So the audience was stacked against me.

But as long as they're young people, I don't mind. Young people will always listen. Old people are a whole different story. But I wanted to help them understand why someone would be an atheist and yet be rational and even maybe a good person, right? That was my goal. And so I hope that I succeeded at that. You know, like why the arguments from William Wayne Craig were not logically airtight because they are not. And also why there is an alternative that works very, very well. So in the, you know, we each like he spoke and then I spoke and then I spoke, then he spoke, then I spoke, then he spoke, then I

spoke. And by the last of my three little speaking slots, it was short, but I had already said everything I wanted to say, right? I mean, I'd refuted his argument and his most recent, in his final speech, I don't think that he said anything new or rebutted any of my arguments. So I didn't even try in the third part of the debate to refute anything he'd previously said. I think that I had done that already. So I just gave my sales pitch for why naturalism is a very full and rewarding way of thinking about the world. And I think that's exactly what I should have done. And I'm very happy that I did that.

If we were to do it again, maybe I would actually try to win the debate in the sense that I would, having given my sales pitch for naturalism, maybe I would just focus in more on why his pro-theism arguments aren't that compelling. Or maybe not, I don't know. But that would be a different style, which could be equally effective depending on what your goals were. Claudio says, I lived 32 years in a country with mandatory voting and 20 in a country where voting is not mandatory. I strongly favor making voting mandatory. My rationale is that for proper democracy, the government must be representative. This is, its composition should be as proportional to the people as possible. What's your position on mandatory voting? You know, I don't have a strong feeling. This is a case where I think that the whatever feeling you do have should be informed by the, you know, the data. In other words, I don't think that there's any philosophical or moral argument that would

completely persuade me to be either for or against mandatory voting. But if it actually in the world led to better results, then I'd be in favor of it. I don't actually know any sort of unbiased systematic survey of whether or not it leads to better results or even what it means to say that it leads to better results. So therefore, I'm agnostic on that one. Brian says, Antonio Padilla said that we can't picture Graham's number because it contains too much information. But then I wondered, can you picture Pi? There aren't enough atoms in the universe to do that in your head either, but we have it defined, same for Graham's number. Maybe the question is, what is the significance or are there any implications from the fact that we can't hold it fully in our heads? So you're right, then in the case of both Pi and in Graham's number, we have a definition of it, okay?

and we can write down that definition in a finite number of bits, a finite number of instructions, to calculate the number. But if we were to actually write out the number, the story changes a lot. Graeme's number is very, very, very long. Pi is literally infinite, okay? If you write out the entire decimal expansion of pie, it never ends. So there was never any question of holding the decimal expansion of pi in your head. It's just infinity is bigger than a finite number, so you can't do it.

It's sort of not an interesting conjecture. The thing that Tony was making, the point he was making about Graham's number is that it is a finite number. You might think you could hold it in your head, right? No one ever thought you could hold all the digits of pie in your head, but you might think you could hold all the digits of Graham number in your head, but you can't. Because the storage capacity of the brain that would be necessary to do that would collapse into a black hole. That is the implication. So it's a little bit different just because Graham number, Graham's number is long, but still has a finite length.

I'm going to group two questions together. James Swift says, I sometimes struggle with how mathematicians use the phrase, solve the equation. It's easy to understand when someone says solve F for X, but when just generally stated statements, I'm sorry, I'm reading this with a bad inflection here, but when just generally stated,

statements like Schwarzschild solved Einstein's equation, I feel a little lost. Can you give guidance about how to understand such statements? What is being solved? And Billy Westam says, I'm trying to learn some basics

about Einstein's field equations and I feel I am missing something simple in my understanding of the significance of them before and after they were solved. Where Einstein's equations in 1915 simply incomplete

but still obviously important, what does it mean for an equation to be revolutionary without solutions yet found? Yeah, so I, I mean, I wanted very much to answer this question, but you're kind of making me feel bad because I'm realizing that this notion of having an equation and solving it is perfectly clear to me, but maybe I didn't make it clear in the book or elsewhere. And it's not fair to think of it as an obvious notion because it's not an obvious notion. The notion is, if you have an equation like 2 plus 2 equals 4, that's an equation.

There's nothing to do with it. You can't solve that equation. it just is the equation. But when you have algebraic or analytical equations, you have equations with undetermined parameters in them. You have not just numbers, but symbols, to put it very basically, right? You've elevated your mathematical technique from numbers to letters. So let's say you have x squared equals 4.

X squared equals 4 is also a perfectly good equation, but you're not done when someone hands you that equation. Here's x squared equals 4. That's the equation. The question is, what is X, right? And you know the answer, X is 2, except also X equals minus 2. So there's two solutions, and that's a little bit of a subtlety that you can talk about. But finding the actual value of X that satisfies that equation is what we mean by solving it.

And Einstein's equation in general relativity is exactly the same structure, except what you're solving for is the metric, the geometric quantity that tells us the curvature of the. space time. So we have a metric. It's G. Mu. New, if you're reading the book. And what we do is we write an equation containing Gmuneu in various forms, but the equation itself doesn't instantly tell us what the solution is, what the actual value of Gmuneu is. So when Carl Schwarzschild solves Einstein's equation, we had the equation, but we didn't know that there was a solution of the form GmU new equals the shortchild solution. Okay. So I'm When Einstein, when he wrote down his equation in 1915, the equation was complete. It was done.

And he instantly solved it in various approximations. In fact, honestly, he had essentially solved it before he wrote it down because he had approximate versions of the equation itself. But he didn't have any interesting exact solutions. Those came later. So you can propose an equation and have a very good reason to believe that it is correct. You can't be sure because you're never sure in science. but you think it's correct

without yet knowing what the solutions are. Einstein's method was to find approximate solutions and that's why he could still explain things like the deflection

or the procession of the orbit of Mercury, for example. He could show that that was a prediction of his equation without solving it exactly

because he was solving it approximately. Brendan Hall says, do you ever do do problems or exercises from a textbook when you're learning, when you're trying

to learn a new subject these days? You know, sometimes, I'm not that devoted to it. But I guess the reason I want to answer the question is to emphasize that there is a part of learning which one way or the other is the equivalent of solving exercises from a textbook. And this is precisely what we don't do in the biggest ideas in the universe. That's what makes it possible to fit all that information to such a short space. In the book,

we don't tickle that part of your brain. We do not teach you how to solve exercises or solve the equation, et cetera. So I'm a very firm belief. that if you truly want to learn something, you can't just know the equations, but you have to know techniques for solving them, for doing the problems, for doing the exercises. And that's really how you learn it, as unpleasant as it is in your student days. So if I, you know, my, I don't have a good example right now off the top of my hat, but I have, well, here's an example. I have a book on the bookshelf next to me that seems to me like it'll be an amazingly good book as a textbook for a course in a physics course on complex systems.

It's by Stefan Thurner and collaborators called Introduction to the Theory of Complex Systems from Oxford University Press. So I have an aspiration of someday teaching a course on the theory of complex systems, which is something that I only know a little bit about. So if that ever happens, I will certainly go through this book and try to do exercises in it. But I haven't done that yet, so that's why it's not a great example. Eric Stromquist says On the question of probability in the Everett interpretation,

the leading ideas from you and Siemens, from Wallace, earlier Deutsch, all successfully explain why the Boren Rule should work, but they don't explain the mechanism. How is it that the great majority of, or the greatest measure of, observer moments with their memories of a series of measurement results, end up distributed in the wave function

so that an observer chosen at random has usually observed just about the right quantum statistics. So I kind of want to unask this question. I don't buy the presumption of the question, the underlying philosophy of it. I mean, it's cheating when you say, and let me read it again, how is it the great majority of observer moments end up distributing the wave function so that an observer chosen at random has usually observed just about the right quantum statistics? That completely begs the question.

What do you mean by chosen at random? In many worlds, there's going to be many different. observers, and the whole question is, what do you mean by choosing at random? The thing about many worlds is, like, let's not overcomplicate this. It is crystal 100% super duper clear that if you think that the theory implies any probability rule at all, that probability rule is going to be the born rule. There was never any chance it was going to be the probability is like equal to the wave function or the wave function to the fourth power or whatever. It's just Pythagoras' theorem. The The hypotenuse squared is the sum of the squares of the sides.

That's where the born rule comes from. The right thing to do is to justify why there is a probability measure at all. And I think that that's what Chip Stevens and I did. We told you why there is a probability measure and why it acts like the born rule, because there is self-locating uncertainty. So I don't think there's anything more to be done in the cause of explaining the mechanism. I think we did explain the mechanism. Self-locating uncertainty when the wave function branches. That's the mechanism.

I suspect that your thought that we haven't explained the mechanism is a relic of the thought that if you have probabilities, they have to reduce at some point to literally counting, counting a certain fraction of things. If you think that there's a 30% chance that X and a 70% chance that Y, then somewhere in some abstract space, there are 30 Ys and 70 Xs or something like that. That's just not how many worlds works. And so I don't feel that need to satisfy that itch in order to say that I have the mechanism.

I think I know exactly what the mechanism is. Andrew Goldstein says, I read things like the October 30th Washington Post editorial, which tried to provide some insight into the volatile activity of the stock market and the fortunes of the mega wealthy. It leaves me even more confused. Therefore, I wonder whether you see any potential for more sophisticated understanding that would give us better knowledge how to forecast the complex social behaviors and interactions observed in humans but poorly understood. Well, you know, sure. I mean, I do see the potential for that in the sense that I believe there is a potential. If I knew how to do it, I could be much more specific, but I don't, okay? There was interestingly, very recently, something I tweeted about, a post on the blog Marginal Revolution, which is shared by Tyler Cowan, previous Minescape guest, but his co-author, Alex Tarabock, was the one who posted it, who was pointing to a new paper by McDonald and Shalizi, I believe, it's them, which basically took some of the most commonly accepted,

economic models, D-S-D-S-G-E, I'm going to get it wrong, dynamic, general system, equilibrium, some combination of those words. These models that everyone uses in economics, are very, very popular. And roughly speaking, it is only a slight exaggeration to say that they said they are completely nonsense. And here is how they show that they are nonsense. They used the model. So what the model means is there's certain parameters, right?

certain parameters for different economic things. This thing is producing this. There's a certain volatility over here, et cetera. And you can change the parameters and get different predictions for economic output, GDP, unemployment, whatever you want to get. Okay? So parameters lead into predictions from these models. So basically they, but there's also randomness in them.

So you don't predict deterministically because you predict a probability distribution. So they use the model to make a prediction, to sort of predict. a future history, given some parameters. And then they took that history and they fed it back into the model and asked, okay, what are the values of the parameters? And there was essentially no relationship between the values of the parameters that they derived and the ones they had put in. In fact, they said you could even like change the labels on the variables. So what they called the inflation rate, they took the actual values of the inflation rate and switched them for the values of the unemployment rate. And the model found just as good a fit.

even though that makes no sense whatsoever. I haven't read this paper, so I don't know whether they're right or they make some assumptions or they make some mistakes. I mean, they're good people. But it speaks to the difficulty of modeling and forecasting these complex social behaviors. So I guess what I'm saying is, yes, I think we can do better, but we're not doing very well right now. And that's okay. It's completely okay to not do very well right now. We're young and not very good at this yet, but we're learning.

We're learning about the whole idea of something called a complex system. There are some regularities in complex systems, even if they're only statistical. So I remain optimistic that we can do better, but it's hard and it's going to take a long time. Jim Murphy says, I've developed a hobby of creating cellular automata and watching the emergent results of various rules. This is a good hobby. I wish more people had hobbies like this. what you need to do, Jim, by the way, is convert it into a social hobby, right? Like somehow make a website that crowdsources cellular automata and see who's best at finding out the rules.

Anyway, the question is, the vast majority of the rules seem to produce a chaotic static without any, I think it's a typo here, a chaotic situation without any obvious complexity emerging. However, I wonder how much this is a result of my limited computational power and world size versus the inherent properties of, the automata? Do you have any intuition for how often rules that appear chaotic at a small scale will create emerging complexity on a larger scale? I have intuition, but I don't know whether my intuition is very good here. I do think the question is super duper interesting. So for those of you who don't know, in the game of life, for example, this was invented by the mathematician John Conway, famous checkerboard kind of set up and you put some squares down and then let them evolve according to certain rules. And you can see,

see patterns. You can see things that look like gliders, and you can even see things that are what are called glider guns. They're like a fixed configuration that will spit out a series of gliders that move away, and you can even show that you can do calculations using this whole kind of setup. Similarly, Stephen Wolffrom, former Minescape guest, I keep needing to say, was able to show that you could do similar things with one-dimensional cellular automata rather than two-dimensional ones. So there are these examples of emergence. Now, maybe Jim, you should actually look at Wolfram's book on a new kind of science because he's kind of interested in this question. In the world of very, very simple one-dimensional cellular automata, as long as you have the idea that three sites at one time step predict the one site below them at the next time step, you can literally write down every possible rule.

okay? And then you can literally say, here's the subset of rules that lead to emergent behavior. So you can count. But what you're asking is how does that scale with more dimensions, more complexity, etc.? My intuition is that even as things get bigger and higher computational power, it will still be generically not true that you see simple emergent behavior. I think that most things will just be a chaotic. mess, depending on what you allow yourself to put in. So for our world, for our real world universe, we certainly have emergent behavior in the world. You and I are examples of emergent features, emergent systems. But that relies kind of heavily on two things. Number one, there is a hierarchy of scales. So there are atoms that are made of different masses.

there are particles that are made of different masses, and crucially, there are photons which have no mass at all. So what this means is that the atoms and the electrons and so forth bumping into each other can dissipate by giving off photons. And so it's not very easy to model that in a cellular automaton because you're keeping track of everything, right? And what astrophysicists do, when they want to think about the formation of a star, you don't keep track of every photon, right? The sun is, the star is giving off heat or whatever, and that's dissipation. And that sort of brings you down into a subspace of all the possible configurations and gives you a handle on what's going on and helps explain emergent phenomena. So that's one thing, the hierarchy of scales. The other thing is, of course, the past hypothesis.

The fact that we began in a very, very, very special initial state, and that, allowed complexity to arise, as I've talked about before, along the way, and as I talk about in the big picture. So without those two very special features, I think that generically you would not expect simple, coherent, large-scale structures. But this is, again, something I'm totally happy to be wrong about because I don't know of any systematic exploration of the space of possibilities there. Okay. The final question was a long. long one. Terrible Turnip, not the question, the AMA has been long. But I like it. I like doing these AMAs. If I had more time, I would do them more. I do not have more time. I don't even have

time to do this, but I'm glad I'm doing it. Terrible Turnip says, what is your view on how specific a fundamental theory should be to feel right? It seems there is a paradox of sorts. If one finds a theory such that there is only one viable, self-consistent possibility, that would seem very strange. On the other hand, if there are a huge range of possibilities, that would seem to make people uncomfortable. In that case, you would end up using anthropic principle-type arguments to justify one's observation of this particular universe. You know, I don't think that it's a matter of feeling right in this sense. I mean, some theories, there is something called feeling right. I get that. You're on the right track there. But the feeling right has to do

more with how simple and elegant the theory is, the ways in which you either directly or indirectly connected with observations, the scope and fruitfulness of the theory, the compatibility of the theory with other existing ideas that we think are true, things like that. That's what goes into making a theory feel right. You're focusing in on a very important idea, which is how accepting or not accepting the theory is of different kinds of solutions. Right? If we were talking about solving equations, if you have a set of equations where there's only one solution versus if you have a set of equations that have many, many solutions, and both are perfectly plausible. I don't think that you should really judge the feel of theories along that particular dimension.

I can't imagine a theory that only had one solution and also fit the data. But if you had it, if you had a theory that only had one solution and. it was a perfectly good fit to the universe, I think people would be ecstatic about that. The fact that it can't fit other things that didn't happen should not count as a strike against it, is what I would say. On the other hand, like you say, when there are a huge range of possibilities, you feel like it's almost a shame. You know, someone like David Gross, the famous string theorist, is very upfront about the fact that throughout his life, he has been hoping to find the one theory that uniquely predicted our world. That's why he's very sad at the current popularity of more anthropic explanations.

I don't quite feel that way. Like, I'm perfectly happy if the fundamental theory predicts a whole bunch of things and we're just a statistical prediction within it. Maybe it would have been nicer to be more specific, but, you know, I always, always say that we don't get to make demands of the universe and how it operates. I want to figure out how the universe operates. I don't want to tell it how to operate.

The very, very good news is that the universe operates in such a way, seemingly, that we can figure it out. And that's a non-trivial fact about the universe with respect to Jim's question on the previous one. It's the laws of physics had been different. Maybe we would have no hope of figuring it out. But not only can we figure out something about the laws of the universe, but we can do it piecemeal. We can get better and better at it. We can get, you know, one regime under control and then get more and more. And that's just the best way.

That's like the most fruitful way to figure out. these very, very, very, very wide-ranging principles that make the universe run. So in all ways, I would say, count our blessings that the universe is so nice to us to help us figure it out. And don't tell the universe what to do, would be my advice. All right, thanks everyone for hanging in there, for the AMA. Happy beginning of fall. Like, it's fall here in Baltimore. It's been a long time. So I lived in the Northeast. I lived in a region of the country where they didn't really have seasons in any noticeable way. So it's very, very nice to see the beautiful colors of the trees and all that. And don't imagine that I don't know that the niceness will not last forever because that's,

it's coming. There's going to be winter. It already gets dark very early around here. So happy November, happy Halloween. I guess Halloween's already passed. Happy Thanksgiving. Happy all the various holidays that happen between December and January. Talk to you soon.