Adam Brown — Bubble universes, space elevators, & AdS/CFT

1. 0:00 – 26:53

   Changing the laws of physics

   1. ABAdam Brown0:00

      You could imagine our descendants deciding that they're not gonna just suffer the heat death, that they're gonna try and trigger a vacuum decay event to another vacuum with a lower cosmological constant. If it is possible for people just to wipe out their entire future light cone, libertarian fantasies can't really happen. Is it possible that 50% of all of the nuclear weapons ever dropped in combat were in fact dropped against direct orders? Take an exam I gave years ago in my graduate general activity class at Stanford, and give it to these models. Three years ago, zero. A year ago, a weak student. And now they essentially ace the test. These are the two most beautiful theories of 20th century physics. These two theories seem to be inconsistent with each other. There is, however, one fact about that merger that we are most confident about, and the answer to that involves black holes.

   2. DPDwarkesh Patel0:48

      Today, I'm chatting with Adam Brown, who is a founder and lead of the Blue Chip team, which is cracking mass and reasoning at Google DeepMind, and a theoretical physicist at Stanford. Adam, welcome.

   3. ABAdam Brown1:00

      Delighted to be here. Let's do this.

   4. DPDwarkesh Patel1:01

      Okay. We'll talk about AI in a second, but first, let's talk about physics.

   5. ABAdam Brown1:04

      Okay.

   6. DPDwarkesh Patel1:05

      Um, first question, what is gonna be the ultimate fate of the universe and, h- how, you know, how much confidence should we have?

   7. ABAdam Brown1:12

      The ultimate fate is a really long time in the future, so you sh- probably shouldn't be that confident about the answer to that question.

   8. DPDwarkesh Patel1:19

      Uh-huh.

   9. ABAdam Brown1:19

      Uh, in fact, our idea of the answer to what the ultimate fate is has changed a lot, uh, in the last 100 years. Ab- about 100 years ago, we thought that the universe was just static, wasn't growing or shrinking, was just sitting there statically. And then in the late '20s, Hubble and friends looked up at massive telescopes in the sky and noticed that distant galaxies were moving away from us and the universe is expanding. So, that's like big discovery number one. There was then, you know, a learned debate for many years about, you know, the universe is expanding, but is it expanding sufficiently slowly that it'll then recollapse in a big crunch, like a time reverse of the Big Bang, and that'll, that'll be super bad for us? Or is it gonna keep expanding forever, but just sort of ever more slowly, uh, as, as, you know, gravity pulls it back, but it, it keeps... it's fast enough that it keeps expanding? And there was a big debate around this question, and it turns out the answer to that question is, is neither. Neither of them is correct. In possibly the worst day in human history, sometime in the 1990s, we discovered that, in fact, not only is the universe expanding, it's expanding faster and faster and faster. It's what we call dark energy, or the cosmological constant is this, uh, you know, just a word for uncertainty, is making the universe expand, uh, at an ever faster rate, accelerated expansion, uh, as the universe grows. So, that's, that's a radical change in our understanding of the, the fate of the universe, and if true, is super-duper bad news.

   10. DPDwarkesh Patel2:41

       (laughs)

   11. ABAdam Brown2:41

       It's really bad news, uh, because the accelerated expansion of the universe is dragging away from us lots of distant galaxies, and we really wanna use those galaxies. We have, we have big plans to go and grab them and turn them into vacation destinations or computronium or in any w- other ways extract utility from them, and we can't if, if the cosmological constant is really constant, uh, if, you know, this picture is correct. Because, uh, anything close enough, we can go out and grab it, obviously. But if it's further away than about a dozen billion light years, the e- expansion of the universe is dragging it away sufficiently rapidly that even if we send probes out at almost the speed of light, they, they will never make it. They will never make it there and make it back. Uh, they'll never even make it there if it's sufficiently far away. And that means that there's a finite amount of free energy in our future, and that's bad. I mean, that means we, we're doomed to a heat death if that's true. Um, but is it true? Is it... I mean, that was the second half to your question, and, you know, first of all, we keep changing our minds about these things over the last century or so. So, on first principles grounds, you may be somewhat suspicious that we'll change our minds again and, and none of this is settled physics. And indeed, it may be that the cosmological constant is not constant, and you should, you should hope with all your heart that it's not. Um, it may be that it naturally bleeds away. It may be, in fact, that our fate is in our hands and that our distant descendants will go and bleed the cosmological constant away, will force it to go to zero. They will be strongly incentivized to do it if, if they can, because otherwise, we're doomed to a heat death.

   12. DPDwarkesh Patel4:13

       (laughs) How would they bleed this away?

   13. ABAdam Brown4:15

       Oh. Um, well, okay. This, this obviously depends on physics that we're not totally sure about yet. Um, but it seems pretty consistent with the known laws of physics that the cosmological constant, uh, what we perceive it as being a constant, this, this, this dark energy quantity that, that's pushing the universe apart from each other, uh, in many very natural extensions of the known laws of physics, uh, that is something that we have the ability to change. In fact, it can change, can take different values. Uh, it is not just totally fixed once and for all. That in fact, uh, you have what's called different vacuum, different, uh, regions of parameter space that you can transition between in which the cosmological constant can take different values. And if that's true, then well, you could either sort of wait around and hope to get lucky, hope that the universe just sort of spontaneously moves from one of these vacuums to another, one with a lower cosmological constant, uh, t- tending towards zero asymptotically, or, uh, you could take matters into your own hand. Or you could imagine our descendants deciding that they're not gonna just suffer the heat death, that they're gonna try and trigger a, a vacuum decay event to get us from one vacuum we're in to another vacuum with a lower cosmological constant. Uh, and our distant descendants will be forced to basically to do that if they don't want to suffer a heat death.

   14. DPDwarkesh Patel5:37

       Yeah. Proceed with caution? (laughs) How is this-

   15. ABAdam Brown5:40

       Definitely, definitely proceed with caution. You know, in these theories where there's lots and lots of vacuums out there, uh, and, uh, most of those vacuums are incredibly inhospitable to life as we know it. In fact, seemingly they're just completely inhospitable to all forms of intelligence, uh, so you really, really don't want to end up in them. However, again, if our best theories are correct, it, it seems as though there should be some of them that are much like our own in many ways, but have a-... a lower value of the cosmological constant. And so what we'd want to do is, is engineer, uh, that we end up in one of those vacuums.

   16. DPDwarkesh Patel6:14

       Mm. Sorry, what, what is a vacuum?

   17. ABAdam Brown6:17

       Ah, uh, great question. Uh, a vacuum is like a, a possible, well, what we would perceive as a possible set of laws of physics, of, uh, as we s- see them. Um, so it's... What it really is, is a, you know, minima in some higher-dimensional, uh, abstract laws of physics space-

   18. DPDwarkesh Patel6:36

       Mm.

   19. ABAdam Brown6:37

       ... uh, in which you can find yourself in a minima. But these minima may just be local minima. In fact, according to our understanding, uh, the minima in which we live today is... that gives us all of the laws of physics that we see around us is in fact just a local minimum. And there's a lower minima. In fact, there's many lower minima out there to which we can transition spontaneously or 'cause of our own deliberate action.

   20. DPDwarkesh Patel6:57

       Okay. I- I- I'm just gonna throw all my confusion at you (laughs) . And you (laughs) , you figure out which one is, like, worth dealing with first. Um, what is the nature of, um, the loss function that makes one value a minimum and one higher up? You know, w-what is exactly the ball rolling up on when it gets out or into a, a valley here? Um, and then you were hinting at the possibility that there are other sp- other places in... I'm not s- sure if you're suggesting in the physical universe or in some hypothetical universe where the vacuum could be different. As in, in reality, there are other pockets with different vacuums, or that, um, hypothetically they could exist, or that no, our universe counterfactually could be, have one of these? Um, I don't know (laughs) . This is the kinda thing I'd, like, throw into, like, uh, cl- cl- you know, just, like, put everything I can into, like, a Claude prompt-

   21. ABAdam Brown7:51

       (laughs)

   22. DPDwarkesh Patel7:51

       ... and see what comes out the other end (laughs) .

   23. ABAdam Brown7:53

       Good. Well, I'm, um, happy to be your, your, your Claude. Um, the loss function is the energy density. Um, and so maybe a good analogy would be water. Um, water can exist in many phases.

   24. DPDwarkesh Patel8:07

       Mm-hmm.

   25. ABAdam Brown8:07

       It can be steam. It can be water. It can be ice. And, uh, even if it's in a cloud, let's say, it would rather, rather be water than be water vapor. But it's having a tough time getting there because in, in the middle, there's a, there's a barrier. And so you know that just spontaneously, it can, you know, eventually choose a sort of thermal process, turn from steam into, to water. Th- these will be, like, the two minima in this, in this lost landscape. And... Or you can go and do cloud seeding to turn it from water, uh, from water vapor into water. And so those would be the equivalent of the, the minima here. The existence of different minima in general is a very well-established part of physics. The possibility that we could engineer going from one minima to another in a controlled way is a more speculative branch of, uh, physics speculation. Uh, but it seems totally consistent with everything we know, that our distanced descendants would try to attempt it.

   26. DPDwarkesh Patel9:06

       What would it take to do this?

   27. ABAdam Brown9:08

       Probably you'd want a, uh, something that would look a bit like a particle accelerator, but it would be, uh, considerably more controlled. You'd need a s- very controlled way to sort of collapse a field and, and make a bubble of this new vacuum that was big enough that it would continue to expand, uh, rather than just recollapse under its own surface tension. You'd have to do that in a very careful way, uh, both to make sure that you didn't, you know, accidentally make a black hole instead by the time you've concentrated all those energies. And also, you know, worse than making a black hole would be ending up in a vacuum that you didn't want to end up in, would be ending up in a vacuum in which you had not only bled off the cosmological constant in some way, but that you had, uh, changed, let's say, the electromagnetic constant or the strong nuclear force or the, any of these other forces, which would be seriously bad news. 'Cause if you did that, you know, your, your life, uh, as you know it, uh, is extremely well-attuned to the value of the electromagnetic constant in your evolutionary environment. It'll be very, very bad indeed if we changed those constants as well. The, the... We'd really just try and target the cosmological constant and nothing else, and that would require a lot of engineering prowess.

   28. DPDwarkesh Patel10:17

       So sorry, it, it sounds like you're saying that, um, changing the laws of physics is like... I- i- it's not, like, some cra- it's not even like Dyson sphere level crazy. It's like (laughs) -

   29. ABAdam Brown10:28

       (laughs)

   30. DPDwarkesh Patel10:28

       ... you know, somebody could do it on, like, some planet in the middle of, uh, uh-
2. 26:53 – 38:22

   Why is our universe the way it is

   1. DPDwarkesh Patel26:53

      i- if we lived in a world with intelligent design and these were the laws we f- found ourselves with, at a high level what is the creator trying to maximize? Like i- i- i- what is the... I mean, other than maybe h- us existing? Um, uh, does there seem like something that is being, uh, optimized for? What, what is, what's, what's going on here?

   2. ABAdam Brown27:14

      Um, if you just throw a dart in laws of physics space in some sense, uh, you would not... There are some properties of our universe that would be somewhat surprising, um, including the fact that our life seems to be incredibly hospitable for complexity and interesting, uh, interestingness, and, uh, the possibility of intelligent, uh, life. Um, which is an interesting fact. You know, everything is just tuned just so that chemistry is possible. Um, and perhaps in most places you would throw the dart, in possibility space, chemistry would be impossible. Th- the universe as we look around us is incredibly rich. There's, there's structure at the scale of viruses all the way to structure at the scale of galaxies. There's interesting structure at all levels. This is, this is a very interesting fact. Now, some people think that actually interesting structure is a very generic property, and if we threw a dart, uh, somewhere in possibility space there would be interesting structure no matter where it hit. Maybe it wouldn't look like ours, but there'd be some different structure. But really if you look at the laws of physics, it does seem like they're very well attuned for life. So in your scenario where there's an intelligent creator, uh, then they would probably be, uh, you'd have to say they'd optimized for that. It's also the case that you can imagine explanations for why it's so well tuned for life that don't involve a intelligent creator.

   3. DPDwarkesh Patel28:40

      Is there any explanation other than the anthropic principle for why, uh, we find ourselves in such a universe?

   4. ABAdam Brown28:45

      Well, you suggested one with an intelligent creator, but yeah, the, the usual one that people like to talk about is the anthropic principle.

   5. DPDwarkesh Patel28:50

      So is it like, uh, 99% that basically the reason we find ourselves in a universe like this is the anthropic principle? Like what probability do you put-

   6. ABAdam Brown28:58

      Well, 99% is a pretty high number.

   7. DPDwarkesh Patel28:59

      What probability do you put on like anthropic principle is, a key to explaining why we find ourselves in the kind of universe we find ourselves in?

   8. ABAdam Brown29:06

      I think it's gonna depend on what quantity you're asking me about.

   9. DPDwarkesh Patel29:10

      Yeah.

   10. ABAdam Brown29:11

       So if you ask me, you know, 99% of the matter in the solar system lives in the sun-

   11. DPDwarkesh Patel29:17

       (laughs) Right, right.

   12. ABAdam Brown29:18

       ... or on Jupiter, and yet we live-

   13. DPDwarkesh Patel29:19

       Right.

   14. ABAdam Brown29:19

       ... seem to live in this like really weird corner of the solar system. Why is that? I'm pretty confident that the answer to that is anthropic.

   15. DPDwarkesh Patel29:26

       Yeah. (laughs)

   16. ABAdam Brown29:26

       That if we lived in the center of the sun we'd be dead, and so one should expect intelligent life to like live in this weird place in parameter space.

   17. DPDwarkesh Patel29:32

       Yeah.

   18. ABAdam Brown29:32

       Uh, so that's perhaps, you know, my most confident answer to that question, why do we live where we live. Then if we start talking about different constants of nature we start getting different answers to that question. Why is the universe tuned such that the proton is just a tiny bit more stable than the neutron? You know, just, uh, that seems like that's begging for a anthropic answer. Of course, if that's true, that demands that there be different places somewhere in the multiverse where in fact the neutron is slightly heavier than the, uh-

   19. DPDwarkesh Patel30:06

       Yeah.

   20. ABAdam Brown30:06

       ... that the protons decay to neutrons rather than vice versa, and people just don't live there.

   21. DPDwarkesh Patel30:10

       Yeah.

   22. ABAdam Brown30:10

       Um, so that, i- if you want to go down that road, you end up being naturally drawn to the existence of a, of these variables scanning over space.

   23. DPDwarkesh Patel30:20

       Is, is there some way for the anthropic principle to exist that doesn't involve these bubble universes?

   24. ABAdam Brown30:26

       Yes. All you need is that there is different places in some larger possibility space where these, where these quantities scan, where they take different values. Bubble universe is just one way to do that.... we could just be different experiments, uh, simulations-

   25. DPDwarkesh Patel30:40

       (laughs)

   26. ABAdam Brown30:40

       ... in some me- meta universe somewhere.

   27. DPDwarkesh Patel30:42

       Um, what part of this is the least sort of logically inevitable, right? Like some f- some theories seem to have this, uh, uh, uh, feeling of like it had to be this way, and then some are just like wa- why are there these like s- 16 fields and hundreds of particles and so forth? What part of the, oh, the, the, our understanding of the univ-

   28. ABAdam Brown31:00

       Of physics?

   29. DPDwarkesh Patel31:01

       Yeah.

   30. ABAdam Brown31:01

       I would say that there's three categories. There's things like quantum mechanics and general relativity that are not logically inevitable, but do seem to be a- attractors in, in, in some sense. Um, then there are things like the standard model has 20 fields and it has a mass of the neutrino. You know, why do those masses of the neutrino have the values that they have? That seems... The standard model was just fine before we discovered that the neutrinos have mass in the 1990s, and those just seem to be just totally kind of out of nowhere. "Who, who ordered that?" was what a famous Nobel Prize-winning physicist said about the muon. In fact, uh-
3. 38:22 – 1:01:19

   Making Einstein level AGI

   1. DPDwarkesh Patel38:22

      general relativity so beautiful?

   2. ABAdam Brown38:25

      I think general relativity is really an extraordinary story. Um, it's pretty unusual in the history of physics that you, to first approximation, just have one guy who sits down and thinks really, really hard with lots of thought experiments about jumping up and down in elevators, and beetles moving on the surface of planets, and all the rest of it, and at the end of that time writes down a theory that completely reconceptualizes nature's most familiar force, and also speaks not just to that, but is... you know, speaks to the origin and fate of the universe, and almost immediately achieves decisive experimental confirmation in the orbits of astronomical observations, or the orbits of planets, and the deflections of, of light during eclipses and stuff like that. It's a pretty beautiful theory. Um, and it completely changed our idea of gravity from being a force to just being a artifact of the curvature of space-time.

   3. DPDwarkesh Patel39:27

      Hmm. Actually, so this is actually a good point to, uh, chat about your actual day job. (laughs)

   4. ABAdam Brown39:34

      Okay. (laughs)

   5. DPDwarkesh Patel39:34

      So, so there's these de- open debates about the kind of reasoning that these LLMs do. Does it correspond to, quote-unquote, "true reasoning," or is it something more procedural? And, and sometimes it gets into a definition game. But this is maybe a good way to test our intuitions here. Um, the kind of thing that Einstein was doing, uh, where you start off with some, uh, thought experiments, you start off with some seeming conceptual inconsistencies in existing models, and you trace them through to some beautiful unified theory at the end, and you make incredibly productive use of these intuition pumps. Um, that kind of reasoning, how far are, are AIs from that?

   6. ABAdam Brown40:18

      I have heard it said, and I kind of agree with this, that maybe the very last thing that these systems will be able to do, these LLMs will be able to do, is given the laws of physics, as we understood them at the turn of the last century, invent general relativity-

   7. DPDwarkesh Patel40:32

      Yeah.

   8. ABAdam Brown40:33

      ... from that. Uh, so I think that's probably the terminal step, and then once, once it can do that, if it can do that, then there won't be much else to do as far as-

   9. DPDwarkesh Patel40:42

      Yeah.

   10. ABAdam Brown40:43

       ... uh, humans are concerned. It's pretty extraordinary, I mean, particularly coming from a physics background in which progress is pretty slow, uh, to come to the AI field and see progress being so extraordinarily rapid day by day, uh, week by week, year by year. Um, looking at it, it certainly looks like these LLMs, uh, and, and these AI systems, in some sense, they're just interpolators, but the level of abstraction at which they're interpolating keeps going up, and up, and up. Uh, and we keep sort of riding up that chain of abstractions. And then presumably, from a sufficiently elevated point of view, the invention of general relativity, uh, from Newtonian physics is just interpolation at some sufficiently grandiose level of ab- abstraction that perhaps tells us something about the nature of intelligence, human intelligence, as well as, uh, as well as about these large language models. If you ask me how many years until we can do that, uh, that is not totally clear. But, um, in some sense, general re- general relativity was the greatest leap that humanity ever made. And, uh, once we can do that, perhaps in 10 years, uh, then, then we will have fully encompassed human intelligence. Will it have the same... Will it be of the same character as what Einstein did? Clearly, there's some... there are many disanalogies between human intelligence and these large language models. But I think at, at the right level of abstraction it, it may be the same.

   11. DPDwarkesh Patel42:24

       Uh, do you see early examples of the kind of thing it was? Obviously, not at that level of difficulty, but you just start off with, like, "Hey, here's, here's something funny. Uh, go think about it for a while." Um, w- w- what, like, what's the... is there, is there something especially impressive you see when you kind of run that kind of experiment?

   12. ABAdam Brown42:41

       At the moment, these tend to be, you know, these systems tend to be doing-... uh, more elementary material than that, they tend to be doing undergraduate-level material. Um, yes, I haven't seen anything that jumps out to me, like inventing gene- generative TV or even a toy version of that. But there is, in some sense, creativity or interpolation required to answer any of these problems, where you, you start with some science problem, you need to recognize that it's analogous-

   13. DPDwarkesh Patel43:12

       Yes.

   14. ABAdam Brown43:12

       ... to some other thing that you know, uh, and then sort of combine them, uh, and then make a mathematical-

   15. DPDwarkesh Patel43:17

       Right.

   16. ABAdam Brown43:17

       ... uh, problem out of it and, and solve that problem.

   17. DPDwarkesh Patel43:19

       D- do you think AI mathematicians, AI physicists will have, uh, advantages over humans just because they can, by default, think in terms of weird dimensions and manifolds in a way that doesn't natively come to humans?

   18. ABAdam Brown43:34

       Ah. Um, you know, I think maybe we need to back up to, in what sense do humans do or don't think natively in higher dimensions? Obviously it's not our natural space.

   19. DPDwarkesh Patel43:45

       Yeah.

   20. ABAdam Brown43:45

       There was a technology that was invented to think about these things, which was, you know, notation, tensor notation, various other things, that allows you to much... using just even writing as, as Einstein-

   21. DPDwarkesh Patel43:57

       Yeah.

   22. ABAdam Brown43:57

       ... did 100 years ago, allows you to sort of naturally move between dimensions. Uh, and then you're thinking more about manipulating these mathematical objects than you are about thinking in higher dimensions. I don't think there's any sense, I mean, in which large language models naturally think in higher dimensions more than humans do. You could say, "Well, these large language models have billions of parameters, that's like a billion-dimensional space." But you could say the same about the human brain, that it has all of these billions of parameters, and s- is therefore billion dimensional. Whether that, that fact translates into thinking in, uh, billions of spatial dimensions, I don't really, I don't really see that in the human, and I don't think that applies to an LLM either.

   23. DPDwarkesh Patel44:37

       Yeah, I guess you could imagine that, um, you know, if you were just seeing like a million different problems that rely on, uh, doing this w- w- uh, uh, w- weird tensor math, then in the same way that maybe even a human i- gets trained up through that to build better intuitions, the same thing would happen to A- AI, it just sees more problems and can de- develop better representations of these kinds of weird geometries or something.

   24. ABAdam Brown45:01

       I think that's certainly true, that, you know, it is definitely seeing more examples than any of us will ever see in our life, and it is perhaps gonna build more sophisticated representations than we have.

   25. DPDwarkesh Patel45:12

       Yeah.

   26. ABAdam Brown45:12

       Often in the history of physics, a breakthrough is just, you know, how you think about it, what representation you do. It is sometimes jokingly said that Einstein's greatest contribution to physics was his, uh, certain notation he invented called the Einstein summation convention, which allowed you to more easily express and think about these things in a more compact way that strips aw- strips away-

   27. DPDwarkesh Patel45:33

       Yeah.

   28. ABAdam Brown45:33

       ... some of the other things. You know, Penrose, one of his great contributions was just inventing a new notation for thinking about, uh, some of these space times and how they work that made certain other things clear. So clearly, coming up with the right representation has been an incredibly powerful tool in the history of physics, and, and many, uh, incredibly large developments. Somewhat analogous to coming up with a new experimental technique in some of the more applied physic- uh, applied scientific domains. And yeah, one would hope that, uh, as these large language models get better, they come up with better representations, at least better representations for them that may not be the same as a good representation for us.

   29. DPDwarkesh Patel46:15

       You, we'll, we'll be getting somewhere when, uh, you ask, uh, (laughs) you ask Gemini a question and it says, "Ah, g- good question. You know, in order to better think about this, let me just, let me," (laughs) -

   30. ABAdam Brown46:24

       (laughs) .
4. 1:01:19 – 1:12:07

   Physics stagnation and particle colliders

   1. ABAdam Brown1:01:19

   2. DPDwarkesh Patel1:01:19

      So this actually raises an interesting question, which is, look, in some sense we have the same problem with human scientists, right? And so there's always people who claim to have a new theory of everything, and I guess there's not an easy verifier that everybody agrees to because some people call them cranks, other people think they're geniuses. Um, uh, but somehow we've so- solved this problem, right? Uh-

   3. ABAdam Brown1:01:41

      Well, we've sort of solved it. I mean, we haven't solved it in the same way that in if you have some new sort algorithm that you claim is faster than everybody else's-

   4. DPDwarkesh Patel1:01:48

      Sure.

   5. ABAdam Brown1:01:48

      ... sort algorithm, there doesn't need to be any dispute about that. We can just run it and see if it... Physics is not the same way. It is definitely the case that there's a number of people who think they have great theories.

   6. DPDwarkesh Patel1:01:57

      Yeah.

   7. ABAdam Brown1:01:58

      And, uh, there are even perfectly respectable, you know, people who are professors at prestigious universities who have very different opinions about what is and isn't a worthwhile, uh, direction to be exploring. Eventually, you hope that this gets grounded in experiment and various other things. But the distance between starting the research program and, uh, the community reaching consensus based on data and, and other, other considerations, uh, can be a long time. So yeah. We- we ha- we definitely don't have a good verifier in physics.

   8. DPDwarkesh Patel1:02:31

      Even if we did some- s- someday get superhuman intelligence that could do... that could try to find all the remaining sort of, like, high-level, uh, conceptual breakthroughs-

   9. ABAdam Brown1:02:40

      Yeah.

   10. DPDwarkesh Patel1:02:40

       ... how much more room is there for that? Uh, basically have... And was it just, like, 50 years of, like, here's all the really advanced great physics and now we just bog through, like, uh, additions to the standard model? Um, you know, if you look at Nobel Prizes year after year, they get less and less... At least in physics, they tend to get, like, less and less significant. And in fact this year, the Nobel Prize in physics was awarded to-

   11. ABAdam Brown1:03:04

       (laughs) Yeah.

   12. DPDwarkesh Patel1:03:04

       ... um, Hopfield and Hinton for their work in AI. So apparently- (laughs)

   13. ABAdam Brown1:03:08

       Yeah, maybe a taste, a taste of things to come.

   14. DPDwarkesh Patel1:03:10

       Yeah.

   15. ABAdam Brown1:03:11

       I don't think there's reason... I don't think we should be pessimistic about that. I think there could easily be room for completely new conceptualizations that change things. I don't think it's just turning the crank going forward. Um, I think new ways to think about things have always been extremely powerful. Sometimes they're fundamental breakthroughs. Sometimes they are, uh, breakthroughs in which you even take regular physics. This is a story to do with renormalization that maybe is a little too technical to get into, but there was a, sort of, uh, amazing understanding in the 1970s about the nature of theories that have been around for forever, or for, for years at that stage, that allowed us to sort of better understand and conceptualize them. Um, so I think there's good reason to think that there's still room for new ideas and completely new ways of understanding, understanding the universe.

   16. DPDwarkesh Patel1:04:03

       Do- do- do you have some, uh, hot take about why the current physics community hasn't... Uh, I mean, I get... The cosmology is maybe a very notable exception, where, like, it- it does seem (laughs) like the expected value of the (laughs) light cone keeps on switching back and forth.

   17. ABAdam Brown1:04:16

       Yeah.

   18. DPDwarkesh Patel1:04:17

       Um-

   19. ABAdam Brown1:04:17

       Well, if you take particle physics, I think it's 'cause we were a victim of our own success-

   20. DPDwarkesh Patel1:04:20

       Mm.

   21. ABAdam Brown1:04:20

       ... is that we wrote down theories in the 1970s, uh, and those theories were what is called standard model, and those theories were too good, uh, in the sense that, uh, we won, um, in the sense that we could predict everything that would come out of a particle accelerator and every particle accelerator that's ever been built, and every particle accelerator that's likely to be built, uh, given our current budgetary constraints. Uh, so particle physics, I mean there were some questions around the edges, but this model that we wrote down in the, in the '70s and into the '80s basically completely cleaned up that field.

   22. DPDwarkesh Patel1:04:59

       Mm.

   23. ABAdam Brown1:05:00

       We wish to build bigger, more powerful particle accelerators to find stuff that, that goes beyond that, but basically we, we won, and, uh, that makes it difficult to immed- you know, to- to- to immediately... Uh, if you, if you get too good, then it's hard to know, know where to push from there.

   24. DPDwarkesh Patel1:05:20

       Is- is-

   25. ABAdam Brown1:05:20

       That's as far as particle con- physics is concerned.

   26. DPDwarkesh Patel1:05:21

       Um, is there some... So it sounds like the problem with these colliders is that the entr- like, the expected entropy is, like, not that high of, like, yeah, we... bec- the reason it's not that useful is because, like, we kind of have some sense of what we'd get on the other side. Is there some experimental apparatus that we should build where we in fact do have great uncertainty about what would happen and so we would learn a lot by what the result ends up being?

   27. ABAdam Brown1:05:45

       Well, the problem with particle colliders is in some sense that they got too expensive. Um, and CERN is, is tens of billions of dollars, a small number of tens of billions of dollars to, to run this thing. Um-

   28. DPDwarkesh Patel1:05:57

       You could build AGI with that money. (laughs)

   29. ABAdam Brown1:05:58

       Right? Yeah. I mean, it's super interesting how everybody talks about how academics can't possibly compete with the big labs-

   30. DPDwarkesh Patel1:06:04

       Yeah.
5. 1:12:07 – 1:29:48

   Hitchhiking

   1. DPDwarkesh Patel1:12:07

      All right, Adam, what are your tips for hitchhiking?

   2. ABAdam Brown1:12:09

      Oh, good question.

   3. DPDwarkesh Patel1:12:10

      (laughs)

   4. ABAdam Brown1:12:11

      (laughs) Uh, so I, I hitchhiked, uh, a bunch around, around America and, and Europe. I've done, you know, Oxford to Morocco. Uh, when I moved from Princeton out to Stanford I hitchhiked. A bunch of other times down to New Orleans, various other places. Um, I think the, probably the biggest tip for hitchhiking is to stand in a good place. Some counterparty modeling. Imagine the person who's picking you up, they need time to see you, to evaluate you, and to decide they're gonna pick you up, and then to safely stop. And that all needs to happen. So stand somewhere where people can see you, possibly at a stoplight, and where there's a place for them to safely pull over.

   5. DPDwarkesh Patel1:12:50

      How do you model the, uh, motivations of people who pick you up? W- what are they getting out of this?

   6. ABAdam Brown1:12:56

      Um, I think it's different for different people. I think about 20% of people will just always pick up hitchhikers no matter what. Even if I'd...... you know, was dressed very differently and presented very different. I think some people will just pick, pick people up no matter what. I basically fall into that category now. Well, it's hardcoded into my brain that I will 100% pick up hitchhikers, always, under all circumstances, just because enough people have generously picked me up down the years that I just feel as though it's my, my duty and sort of not, not subject to a cost-benefit analysis. Just, it's in there. Um, many other people are evaluating you and just, you know, trying to decide what, what you're in for. Some people are lonely and want somebody to talk to. Some people have a, just a spirit of adventure and find it exciting to pick, pick people up. Certainly, it's not a representative cross-section of people, I would say. There's definitely a selection bias in who picks you up. They tend to be more open and more risk-tolerant.

   7. DPDwarkesh Patel1:13:52

      Hmm. And what did, what was your motivation for...

   8. ABAdam Brown1:13:55

      (laughs) Did you-

   9. DPDwarkesh Patel1:13:57

      A- were you just in need of a car or what was going on?

   10. ABAdam Brown1:13:58

       No. I, um, enjoy meeting people.

   11. DPDwarkesh Patel1:14:02

       Yeah.

   12. ABAdam Brown1:14:02

       And it's, I enjoy the experience of meeting people and weird episodic, uh, s- sense of which just you never know what's gonna happen. I think I have a very high tolerance for ambiguity, and I enjoy that.

   13. DPDwarkesh Patel1:14:15

       What, what was the percentage of, "We just had a normal conversation, they went in the general direction I was going, and that was that," versus, "I've got a crazy story to tell about X incident." Uh, uh, what percentages each?

   14. ABAdam Brown1:14:27

       Hmm. I think some people are just totally normal people, families moving their child to college, and you get-

   15. DPDwarkesh Patel1:14:36

       Yeah.

   16. ABAdam Brown1:14:36

       ... there and you help them, you know-

   17. DPDwarkesh Patel1:14:37

       (laughs)

   18. ABAdam Brown1:14:38

       ... move some stuff into the dorm room just to, just to thank you, all the way through to absolutely wild, uh, cases. Probably 20% are just like, "This is one of the craziest things that ever happened," uh, in one way or another.

   19. DPDwarkesh Patel1:14:52

       Yeah. W- what, any particular examples you know about, of the wild things?

   20. ABAdam Brown1:14:55

       Oh, yeah. Huge. I mean, it's just, a- absolutely fire hose of, of wild things-

   21. DPDwarkesh Patel1:15:00

       (laughs)

   22. ABAdam Brown1:15:00

       ... uh, happening. Um, I could tell so many stories. Like, I remember once there was a, a trucker who picked me up in the, the desert outside Salt Lake City and who, who drove me to Battle Station, Nevada. And who, as we were talking... Uh, the truckers are always, in fact, the most interesting of all.

   23. DPDwarkesh Patel1:15:20

       Ah.

   24. ABAdam Brown1:15:20

       Um, it's, it's typically illegal or anyway in violation of their employment contract for them to pick people up. So, th- those guys are really, um, and in... It's always guys, are, are really pushing the envelope-

   25. DPDwarkesh Patel1:15:33

       Yeah.

   26. ABAdam Brown1:15:33

       ... um, in terms of picking you up. The truckers often will say, "You're the first person I've had in my cab in 20 years of trucking," or something, and then they tell you about 20 years worth of-

   27. DPDwarkesh Patel1:15:45

       Mm-hmm.

   28. ABAdam Brown1:15:45

       ... things that have been on their mind. Uh, so I'd say that those are often, uh, the really interesting ones. As I said, there was this one in, in Utah who was just, just talked from the moment I got into the cab, um, until we got to Nevada. And I kinda got the feeling that he had sort of excess mental capacity and that this was his, you know, he was now just gonna dump it, uh, on me. And, uh, he was telling me all about his life. Um, and I f- remember this very well. How his brother-in-law thought he was a loser, his, his sister's husband, but like now he had the hot fiance, so who was the loser? And then just sort of gradually, over the course of the six hours, it just suddenly occurred to me that his fiance was doing advanced fee fraud on him. And the whole thing was some ginormous... And he was being scammed, uh, by his fiance. And very unfortunately for them, they tried to execute the scam while he had me in the cab. And he never had anyone in his cab, so now he had me in his cab, and they were trying to do some fraud on him. And I was able to... They had some wheat factory in Wales, uh, Uni- United Kingdom, that they had some British High Court document saying that he was entitled to if he paid off the lien on it. There was some long complicated story that was totally, flagrantly false. And I kind of felt like I had a moral obligation to him, to break the news to him. On the other hand, we were in the middle of nowhere-

   29. DPDwarkesh Patel1:17:08

       (laughs)

   30. ABAdam Brown1:17:08

       ... in Nevada and it was clearly a very important part of his personality that this was so.

Episode duration: 2:44:25