YouSaid · the spoken record

Adam Brown

lines on the record: 215
first: 2024-12-26
most recent: 2024-12-26
sittings or episodes: 1
sources: podcast

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“I'm squirming somewhat uncomfortably in answer to that question because I'm not totally sure. I could certainly imagine a scenario in which it's five years.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Oh, good question. Many of the tasks that I might have performed in the past I think are already automated at some level until I am totally out of the picture and no longer necessary. That's probably pretty close to ASI complete. So whatever your timeline for ASI is.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Well, it might be because the sort of analog of the classical fact that flops are not the only thing you care about. You also care about bandwidth and interconnects and things like that. So perhaps the same would be true. I mean, here we're getting into pretty speculative. But you could imagine either configuration, either on which you have a huge number of different quantum computers that are talking to each other via entanglement networks or in which you just have one big central computer.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Eevee would need to be co located or you'd need to send the quantum coherence out. That's actually not that hard to do. It's a property of photons that they do tend to maintain when they're propagating in the vacuum. They basically maintain their coherence for a very long way. In fiber optic cables, you reach trouble because they start getting absorbed by the fiber optics after tens of miles. But in the vacuum, you could, in principle, share quantum entanglement across the universe if you did it right.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Even paying the cost of the redshift and all these other questions, we'll feed all of the energy and free energy back into one central quantum computer and we'll all be about making that central quantum computer as big as possibly can, even at the cost of inefficiency. On the other hand, there are other kinds of Tasks for which actually having twice as big computer is not that much better or certainly not more than twice as better and is having two smaller computers. In that scenario, it'll be a more distributed setup.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Yeah, I think this is a super interesting question. So it returns to the question we were asking before. With quantum computers, we know, for example, that the Amount of quantum computation you can do in terms of the The equivalent amount of classical computation and trying to do some factoring algorithm or something grows superlinearly with the number of qubits. In fact, it grows almost exponentially with the number of qubits. So a 200 qubit quantum computer is much more than twice as good as 100 qubit quantum computer for certain tasks, but for the tasks that we try and use quantum computers for, that's true. line of reasoning might lead you to believe that in the distant future we will just try and”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Because it may prove to be so much more efficient to do things in simulation than to do them in the real world, my guess would be a high percentage of that. But I... Maybe that's wrong.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Light and beaming the light back in a laser and then having a big photos here PV here collected or for whatever mechanism. By the time it reached me there would be a massive redshift and so keeping it in place is maybe better than just disassembling it and all and bringing it back home. But there's another question which is what is the is the plan to these are all unknowns to do with both physics and the nature of technology is the most important thing that all of the value will be created here on earth and we just need to get as many resources back here on earth and it's you know the there are superlinear returns to scale of having accumulated resources in one place so we just want to make earth an absolute paradise or do we want to spread is in fact sublinear and we want to spread civilization all the way throughout all of these galaxies I think questions like that are going to be important in addressing your question of what the returns to scale are and returns to”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“So maybe the same thing would be true in the universe. I think there are a number of questions in there. For starters, not all energy is equally useful in different places in the universe. If there's a galaxy over there and a galaxy here on this side of the universe, because of the expansion of the universe, Either by literally sending it on starships or converting it to”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“I mean, so in economics, the theory of comparative advantage. Only applies if Not all resources can be transported. Like, if you can just go in and just disassemble whoever you're doing the comparative advantage with, you might as well just turn them into apply it all to the app, the party with the absolute advantage.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“But what the minimum error rate is is not, I think, a clear, I don't have a clear answer to that question. Physics doesn't have a clear answer to that question.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“It is a very interesting question about the fundamental limits on errors are in a computer. How far down can they be pushed? In terms of never making errors, I think that's very unlikely. If for no other reason than there is a minimum background temperature caused by the expansion of our universe, again, it all coming back to the cosmological constant that gives a very small but non-zero temperature to our universe that I think will inevitably mean that we make errors. You might imagine we could just set up some kind of perpetual motion machine that's just like thinking happy thoughts over and over again in a quantum computer that never tires and never stops. I think that inevitably there would be the universe would leak in and there would be errors.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Energy limits. We've talked about early efficiency of batteries and extracting energy. Embassy squared is the Highly confident that the most energy you can extract from a given piece of matter is MC squared, at least until you start getting cosmology involved. Other limits will be land hours limit, or in other words, with a given amount of energy, how useful is a given amount of energy to you. We wouldn't care about having as huge amounts of energy if you could get an arbitrary amount of value out of a fixed unit of energy. We think that that's not true. We think that the... In particular, if we're going to do computations with it, for example, that there's going to, and that computation makes errors, that there is a fixed cost of a bit, basically a bit of free energy, in order to correct those errors.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Is a tricky one. That is a really tricky one. We've only thought it's only a century that we thought you can't communicate faster than the speed of light. A million years are such a radical time that maybe we've sort of dissolved the question into some greater question and we understand it doesn't even really make sense. I would be pretty surprised if you make me make a number. I think that there is a Greater than 90% chance that in 100 years we are still limited by the speed point. There's a 98% chance if you make me be precise.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Yeah, I think that's a good question. Certainly some of the possibilities we've discussed so far have different epistemic statuses about how confident we are or not confident. And as we also discussed, some of these bounds are somewhat fragile. Can you communicate faster than the speed of light, for example? Let's just take that as an example bound. We think you can't, according to the laws of science as we understand it. Most physicists will be pretty surprised if it turned out that you could, even though you're”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Yeah, so again, we only really properly know how to do quantum gravity and do the counting when there's a negative cosmological constant, as we discussed with ADSCFT. In these bubble universes where there's a positive cosmological constant, it's still somewhat an open question how to do the accounting of what happens and where and how much it should count. Is to say we don't know the answer to that question, and your opinion is not ruled out.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Talking about the two kinds of multiverse, the sort of cosmological multiverse and the quantum mechanical multiverse. Yeah, they get very bound up if you try and write down a theory that has both of them. Whether there's a bubble there, you're trying to make a bubble universes, but what gives rise to bubble universes is often quantum processes. So often you end up in superpositions over there being a bubble universe and there not being a bubble universe there. And that means that these two kinds of multiverse, the sort of quantum mechanical multiverse and the cosmological multiverse, end up getting totally intermeshed with each other.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“It's also the case that this is a pretty, like Born's rule narrowly defined does not really have anything to say about this, how one should calculate the total utility. It's just more of a sort of the natural utility measure that would come out of this. Particularly when you get to the cosmological multiverse, I think that these are very difficult questions to answer. Your intuition that two may perhaps two different universes in which how we calculate those, do we just add together the utility in both, or is there some nonlinearity to do with it? Basically, for the cosmological multiverse, Isn't a particularly good way to decide what the weighting factor should be. We don't have the same equivalent of Born's rule in quantum mechanics. And I think it's at least open for opinions like yours to be.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Yeah, I think there's a number of ways to think about this. I think in part, people's intuition is maybe formed in cases like extinction, where if you have an animal that's going extinct, if half of the animals get wiped out, that's somehow less bad than if both halfs of the animals get wiped out. But that's because they really aren't going to interact in the future. And there's the possibility of those don't have non-overlapping future lake cones, the two populations of some possibly extinct animal.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Seems to be inconsistent with Born's rule, but is somehow intuitive in which somehow it's not just a linear function on these universes.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Correct way to calculate the expectation value of anything is to calculate its value in each branch and wait those branches by the square of the amplitude or wave function, which is some particular quantity, and then add together all of those different answers. So that's a linear answer, which is to say that the total utility of the universe is the sum of the utility in each of these branches appropriately weighted by Born's rule. So if that's true, You should hope to make our branch as good as possible just because whatever is going on in the other branch, the total utility is just the sum of what's going on in that branch and what's going on in our branch. And so you should try as hard as you can to make our branches as great as possible. Nevertheless, I do kind of understand that you might have a portfolio theory that”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Rule, which is one of the foundational rules in quantum mechanics, tells you how much to care about each branch. You don't care about them equally, and it says that”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“And you might say, you know, maybe I don't care about existential risk in our universe because we blow each other up or turn into goo or whatever. Okay, that's sad for us. Maybe our world has vacuum decay, but there are some other branches of the wave function where it's not. And so I'm kind of, you know, some other branches will have made different choices in the past and they're sort of guaranteed to somewhere in the branches of the wave function to be a flourishing world. And so I'm not so bothered. I would say that that's... I'm not going to tell you what utility function you should place on the wave function. But Born is, you know, there's the Born rule in quantum mechanics. And that tells you that you shouldn't just say... It's there in one branch. That's just as good as anything else.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Good question. I think I'm going to say yes and no. I mean, it's clearly if correct, let's just take the quantum case, which is perhaps even more secure than the cosmological multiverse case. In the quantum case, it really does look like the default expectation, given everything we understand about quantum mechanics, should be the many worlds interpretation in which the universe keeps branching off and there'd be more and more branches. And every time, or almost every time you come to a Point of quantum A measurement we might colloquially say is made that the universe branches, and then there's every possibility is represented still in the grander wave function. That's a pretty profound thing to learn about the ontology of the world, if correct, it seems like it should be the default expectation”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Absolutely. So a cosmological horizon is very different from a black hole horizon in this regard. A black hole horizon And it's everybody can agree where that is. For cosmology, there is a point of no return, but there's no point of no return is returned to a given person. And so for each person, there is a different point of no return. And as you say, we live on the boundary just as much as we live on the boundary of those people live on our cosmological horizon. We may live on their”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Five billion light years, you can send information to that point and have it return to you. But on the other hand, there are things that are 100 billion light years away that will never be able to communicate with. And there's a boundary between those two, between some things that we could in principle communicate with and things that we couldn't in principle communicate with. That is the cosmological horizon. And some people who are trying to do a version of holography that works in universities of the postmodern positive cosmosal constant like to put the second theory there. Other people like to put it in the distant future and the sort of infinitely distant future. And that's part of the problem is that where do you even put that theory? It's not like in these universe where you can just put it spatially infinitely far away and be done with it.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Separately asked what would it look like? What would a version of where is the boundary theory in the sitterspace since there's no boundary? That is a great question that people who are trying to generalize ADS CFT to a universe like ours that has a positive square model constant, that they wrestle with. And there's more than one proposal, some of which is that the place one example of a proposal is that the dual theory should live on the cosmic horizon. So there's a if you go”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“So there are two components to that question. You have an intuition that if something is real, it needs to be spatially localized and things that are delocalized in space somehow can't be real. I would say that that's not my intuition. My intuition is that there can be two completely different descriptions of the same physics. And if it's precise, neither of those is any more real than the other. Do not need to be spatially localized”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“I think this is more of a philosophical question. My answer would be if the isomorphism was just an approximation, like it was really one thing and you were just pretending it was the other thing and that approximation worked in some region of validity and not others, then I would say that one was right and the other one was just a alternative fanciful description. That is not our understanding of ADS CFT as we understand it today. Our understanding is that this is a precise isomorphism. It's not a analogy. It's not a metaphor. It is not an approximation that is valid in some domain and not another. It really is the case that these two theories are exactly equivalent to each other. And if that's correct, then as a matter of philosophy, I would say those are both equally real. So it's not the case that one is more real than the other. They're perfect simulations of each other. Yeah, are you an ADS triving you're a CFT or a CFT dreaming you're an ADS?”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Yeah, okay, that's a good question. This duality idea where you have two different descriptions of the same thing is not, the ADS CFT was not the first such example in physics. It's a common trope in physics that you can have two different descriptions of the same thing, some of which are more useful in one scenario, some of which are more useful in the other scenario, but which are both exactly correct. And there are non-gravitational examples in physics that go back a long way. You may then ask, you know, which one is right and which one is not right? Is it actually a CFT that's pretending to be, that has this weird alternative description as a gravitational theory? Or is the gravitational theory correct and the other one's not correct?”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Goes all the way back to Archimedes. You need a, it is easiest to formulate a theory if you have a fixed point on which to stand and observe things from a distance. In a universe with a positive cosmological constant that you don't have that. You don't have that. You're necessarily mixed up with the system because you live in a universe that has only a finite amount of entropy, you finite amount of free energy, there is inherent limitation to the precision of the experiments you can do. That just makes things way trickier. So for that and related reasons, it's a much harder project, but for sure people are working on that.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Yeah, people are working on that as an open area of research. Ever since the original ADS CFT was written down, people have been trying to formulate versions of it which have a positive cosmoshore constant. It's difficult, and part of the difficulty is.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Are these plasma physics itself extremely complicated? And there are these big collisions that we do at RIC in Brookhaven where we smash two gold atoms together and make big fireballs of quark gluon plasma. And it's extremely challenging to calculate what would happen there. And yet people use this duality in the opposite direction to say, even though it looks super complicated with this weird plasma physics in the non-gravitational theory, it's actually can simply be understood as some simple black hole property in the gravitational theory.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“But what maybe looks very simple in one theory, like you and I chatting back and forth to each other would look like some complicated plasma physics in the lower dimensional boundary theory. And so the sort of complexity of how it looks like, which is a better description, does not need to be conserved across the isomorphism.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“But at the same time, it doesn't describe our universe. In particular, in ADS CFT, there is a negative cosmosal constant in the gravitational theory, and our universe, as we discussed before, has a positive cosmosal constant. So it's great because it provides an existence proof of a well-defined theory of quantum gravity, not alas in the universe in which we live in. Okay, but having said that, yeah, it's extremely confusing and was a very impressive result, precisely because you might think, how could it possibly be the case that two different theories and two different dimensions could turn out to be equivalent? And the answer to your question is if you have two people who are living in this negatively curved space and talking to each other, what does that look like in this other theory? I say that there's some, you know, there's this process going on in the gravitational theory that's dual is which...”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Yeah, so maybe I should just lead with some disappointing news, which is that ADS CFT was a tremendous conceptual breakthrough in our understanding of quantum gravity and embodied the holographic principle.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“So, this was a very influential paper, as I said, and really becomes a tremendous theoretical laboratory for trying to understand the connection between gravity and quantum mechanics. One problem it solves is gravity is mysterious, particularly once we improve quantum mechanics in various ways that we could go into. This is why it's hard to quantize gravity. If you can say that this theory of that involves both quantum mechanics and gravity is exactly dual is in some sense the same theory as just an alternative description of a theory in one fewer dimensions that doesn't involve gravity. Well, that's great because we have much better grasp on how to understand theories that don't have gravity than we do on theories that do have gravity. So it puts everything on a much clearer footing to have this non-gravitational description because then you can just use the”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Of the holographic principle. It's like gravity eats information. There's less information than you thought there was that you naively thought there was if you didn't include information. And so the holographic principle says that maybe that's not just a neat observation. Maybe it in fact is the case that for every for some quantum gravitational theories, there is another theory that is exactly equivalent to it in one fewer dimension. And so this led to Maldesena's ADS CFT correspondence with gay gravity duality, which was the most cited paper in Hengey Theoretical Physics ever, I think maybe, at this stage. And in the late 90s, he wrote down. He took that as a hint and it wrote down an exact, we believe, an exact duality between a particular theory of quantum gravity, some particular flavor of string theory.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Whereas, in fact, it scales like the area. Or another way to say that is if you take a three dimensional Previous one dimensional theory in which you have both quantum mechanics and gravity. The information storage scales like R squared rather than R cubed, i.e. it scales as though you had a non-gravitational system in one few dimension. So if you had a two-dimensional theory in which there was no gravity, the information stored in a given region would also scale like r squared because the information would be just the two-dimensional volume as in the area. So in other words, it's at least as far as information density, the information capacity is concerned, a gravitational theory in three dimensions is like a non-gravitational theory in two dimensions. Or more generally, a gravitational theory in n dimensions is like a nongvational theory in 2 minus 1 minus 1 dimensions. That is a big hint that forms the base.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“It's been extremely important for our understanding of quantum gravity. It's perhaps the central fact that we know about quantum gravity is that the information scales with the area. And that is a hint. That fact that was known since the 70s was a big hint that became very influential later on. As understood by Beck and Simon Hawking, it's just a weird fact about black holes perhaps, but we now understand it as a strong indication of what we call the holographic principle. The holographic principle has been a sort of powerful idea in quantum gravity, and it's the following. So if you took a non-gravitational system in which you ignored gravity, like the pile of hard drives, the information storage would scale like the volume, as we discussed.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Yeah, so that's the information storage in black holes. The reason you know that's also the information storage bound for anything, not just black holes, is that if you had something that wasn't a black hole that had more information than that in a given region, and you just added matter, eventually that thing itself would collapse to form a black hole. And so it couldn't be the case just logically that there had more information than the black hole it'll tend to.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“They aren't just balance each other out. If I take a online shopping website and I buy a bunch of whistened little hard drives and I calculate the information storage capacity of those and compare”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“You can have to run that calculation. But if you do run the calculation, it turns out that it's nowhere near it, it wasn't close. Isn't that one of those things where they just...”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“That thought experiment. Is that eventually, if I make a big enough pile of hard drives, the whole pile of hard drives will undergo gravitational collapse and form a black hole.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“You might think that that can't possibly be right. And you might give the following argument. Okay, so there's some region. And I'm just going to keep adding more and more hard drives to that region. And as I make that region bigger and bigger and bigger, the amount of information on those hard drives, scales like the number of those hard drives, goes like the radius of that region cubed. And the thing about the radius of the region cubed is it grows faster at large radius than the radius of that region squared. So I just told you that the amount of information you can store in a region is given by the surface area. And yet I also gave you a way to make it scale like the volume. So eventually if I make the region big enough, the amount of information in that volume will be bigger than the bound that I just said. Therefore, I've ruled out Hawking's and Penrose and Beckenstein's bound. What goes wrong?”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Goes like the volume. And yet, this is like the most surprising fact that is incredibly generative is that once you add gravity to the picture, once you combine quantum mechanics and gravity, the amount of information you can store in a given region, a given sphere goes like the surface area of that region, not like the volume in that region. And you might think that that's...”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“So, if I have a hard drive and I take another hard drive and another hard drive and another hard drive and I keep piling them up, the amount of information I can store on those hard drives scales like the number of those hard drives. And that means it scales like the volume of the region in which I'm storing the hard drives. That everything we know about classical thermodynamics tells us that the amount of information should scale like the volume. Everything we know about non-gravitational physics tends to tell us to point in the direction of the amount of information you can store.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“Meaning surface area exactly. So the reason that that's such a wild answer and an answer that's led to all sorts of thought experiments to do with quantum gravity ever since then is that you might naively think that the amount of information you can store in a region is given not by its surface area but by its volume.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“There was a physicist called Bekenstein who figured out that that should be the answer, the area divided by GH bar. And then Hawking's great contribution to physics was figuring out that it was the area divided by GH bar, but he also got the prefactor. And the prefactor was a quarter. So this is Hawking figured out that it's a quarter. The area divided by four GH bar. And this is a super interesting answer. How much information can you store in a given region is given by the area. And in fact, black holes maximize that. Black holes store that amount of information in a given area.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source
“That is not the only situation. No, anytime you have quantum gravity, they'll tend to be in the same place. And sometimes even when you don't have Quantum gravity, but you have the interplay of gravitational forces and quantum degeneracy pressures. Those will also that'll end up in those. But it's in some sense the simplest situation in which it occurs, which is why so much time has been thinking spent thinking about thought experiments to do with black holes.”
2024-12-26 · Dwarkesh Podcast · Adam Brown — Bubble universes, space elevators, & AdS/CFT · IDENTIFIED FROM THE TRANSCRIPT · source