YouSaid · the spoken record

Sean Carroll

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2024-04-22
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2024-04-22
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  1. “I think it is, and I think we don't. Possible to have it. I don't think we yet have it. Because in part because complexity is not a univalent thing. There's different ideas that go under the rubric of complexity. One version is just Kamalgarov of complexity, right? If you have a configuration or a string of numbers or whatever, can you compress it so that you have a small program that will output that? That's Komolog of complexity. But that's the complexity of a string of numbers. It's not like the complexity of a problem. Computational complexity. The traveling salesman problem or factoring large numbers. That's a whole different kind of question that is also about complexity. So we don't have a sort of unified view of it.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  2. “Sometimes people mistakenly think that complexity or life or whatever is fighting against the second law of thermodynamics, fighting against the increase of entropy. That is precisely the wrong way to think about it. We are surfers riding the wave of increasing entropy. We rely on increasing entropy to survive. That is part of what makes us special. This table maintains its stability mechanically, by which I mean there's molecules, there have forces on each other, and it holds up. You and I aren't like that. We maintain our stability dynamically by ingesting food, fuel, right? Food and water and air and so forth, burning it, increasing its entropy. We are non-equilibrium quasi-steady state systems. We are using the fuel the universe gives us in the form of low entropy energy. To maintain our stability.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  3. “The interesting thing to me is that if you start with a system that is isolated from the rest of the universe and you start it at low entropy, there's almost a theorem that says if you're very, very, very low entropy, then the system looks pretty simple because there's low entropy means there's only a small number of ways that you can rearrange the parts to look like that. So if there's not that many ways, the answer is going to look simple. But it's also almost a theorem that says when you're at maximum entropy, the system is going to look simple because it's all smeared out. If it had interesting structure, then it would be complicated, right? So entropy in this isolated system only goes up. That's the second law of thermodynamics. But complexity starts low, goes up, and then goes down again.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  4. “Well, entropy is hard to localize. It's a property of systems, not of parts of systems, right? Having said that, we can do approximate answers to the question. The answer is black holes are huge in entropy. Most of, let's put it this way. The whole observable universe that we're in had a certain amount of entropy before stars and planets and black holes started to form. 10 to the 88th. I can even tell you the number. The single black hole at the center of our galaxy has entropy, 10 to the 90. Single black holes out of our galaxy has more entropy than the whole universe used to have not too long ago. So most of the entropy in the universe today is in the form of black holes.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  5. “Because as we said, physics conserves information. You can go forward or backwards. These cellular automata do not. They are not reversible in any sense. You've built in an arrow of time. You have a starting point, and then you evolve. So what I'm interested in is seeing how, in the real world, with the real laws of physics and underlying reversibility, but macroscopic irreversibility from entropy in the arrow time, etc. How does that lead to complexity? I think that that's an answerable question. I don't think that Seller Automata are really helping us in that one.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  6. “So for those of the listeners who don't know, viewers, cellular automata come from imagining a very simple configuration. For example, a set of ones and zeros along a line. And then you met a rule that says, okay, I'm going to evolve this in time. And generally, the simplest ones start with just each block of three, ones and zeros, have a rule that they will determinously go to either one or a zero. And you can actually classify all the different possibilities, a small number of possible cellular automata of that form. And what was discovered by various people, including Steven Wolfram, is some of these cellular automata have the feature that you start from almost nothing, like 00001, 0000, and you let it rip and it becomes wildly complex. So this is very provocative, very interesting. It's also not how physics works at all.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  7. “Into important systems, but still there's a lot of the basics I think are not understood. And so searching for the general principles is what I like to do. And I think it's absolutely possible that To be a little bit more substantive than that, I think this is kind of a cliche. I think the key is information. And I think that what we see through the history of the universe, as you go from simple to more and more complex, is really subsystems of the universe figuring out how to use information. To do whatever to survive or to thrive or to reproduce. I mean, that's the sort of fuel, the leverage, the resource that we have. For a while, anyway, until the heat death, but that's where the complexity is really driven by.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  8. “All of those papers I described to you before. Our guesses. Like, what if the laws of physics are different in the following way? And then you can work out the consequences. At some point in my life, I said, What is the chance I'm going to guess right? You know, Einstein guessed right, Stephen Weinberg guessed right, but there's A very small number of times that people guessed right. Whereas with this emergence of complexity from simplicity, I really do think that we haven't understood the basics yet. I think we're still kind of pre-paradigmatic. There have been some spectacular”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  9. “I think it's a fascinating topic. I mean, that's why I'm thinking about these things these days rather than the papers that I was describing to you before.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  10. “Look, I'm with you between nuclear and bioweapons. It is a little bit surprising that we haven't caused enormous devastation. Of course, we did drop to atomic bombs on Japan, but compared to what could have happened or could happen tomorrow. It could be much worse, yeah.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  11. “Are constraints, right? You know, there's a certain amount of energy, certain amount of damage we can do to the environment before it does not. It anymore. So, yeah, I think that's a new question. In fact, it's kind of frustrating because we get better and better at doing things efficiently, but we invent more things we want to do faster than we get good at doing them efficiently. So we're continuing to make things worse in various ways.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  12. “Cautiously optimistic, excited to be too strong. I mean, it'd be great, right? But if we really tried solar power, it would also be great.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  13. “Yeah, 100%. I think this is like one of the biggest. Things that physics can help with, and it's an obvious kind of low hanging fruit situation where. The heat generation, the inefficiency, the waste of existing high-level computers is nowhere near the efficiency of our brains. Hilariously worse. And we kind of haven't tried to optimize that hard on that frontier. I mean, your laptop heats up when you're sitting on your lap, right? It doesn't need to, your brain doesn't heat up like that. So clearly there exists in the world of physics the capability of doing these computations with much less waste heat being generated. And I look forward to people doing that.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  14. “And I think that's perfectly fair. I also was, I almost say pleasantly, I don't know whether it's pleasantly or unpleasantly, but factually surprised. By the recent rate of progress, clearly some kind of phase transition percolation has happened, and the improvement has been remarkable, absolutely amazing. That I have no arguments with. That doesn't yet tell me the mechanism by which that improvement happened. Constructing a model much like a human being would have is clearly one possible mechanism, but part of the intellectual humility is to say maybe there are others.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  15. “What they found was like at least half of the improvement was built into the probe, you know, not all of it, right? And look, Othello board is way simpler than the world. So that's why I just think it's an open question whether or not the, I mean, it would be remarkable either way to learn that large language models that are good at doing what we train them to do are good because they've built the same kind of model of the world that we have in our minds or that they're good despite not having that model. Either one of these is an amazing thing. I just don't think the data are clear on which one is true.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  16. “So they said there's some tentative evidence that this neural network has discovered the Othello board just out of data, raw data, right? But then Melanie's group asked the question, okay, are you sure that that understanding of the Othello board wasn't built into your probe?”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  17. “Next move from not a legitimate next move. It in its brain, in its little large language model brain. I don't even know if it's technically large language model, but a deep learning network. Did it come up with a representation of the Othello board? Well, how do you know? And so they construct a little probe network that they insert and you ask it, what is it doing right at this moment, right? And the answer is that the little probe network can ask would this be legitimate or is this token white or black or whatever? Things that in practice would amount to it's invented the Othello board. And it found that the probe got the right answer, not 100% of the time, but more than by chance, substantially more than by chance.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  18. “The open question in my mind is the easiest, most efficient, best way to act human to do the same things that human beings do, or are there other ways? And I think that's an open question. I just heard a talk by Melanie Mitchell at Santa Fe Institute, an artificial intelligence researcher, and she told two stories about two different papers, one that someone else wrote and one that her group is following up on. And they were modeling Othello. Othello, the game with a little rectangular board, white and black squares. So the experiment was the following. They fed a neural network, the moves that were being made in the most symbolic form, like E5, which means that, okay, you put a token down E5. So it gives a long string. It does this for millions of games, right? Real legitimate games, and then it asks the question, the paper asks the question, okay, you've trained it to tell what would be a legitimate.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  19. “So that's why I think there's a set of hugely interesting questions to be asked about the ways in which large language models actually do represent the world. Because what is clear is that they're very good at acting human.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  20. “Well, I don't think it will happen naturally. I think it could happen. Again, I'm not against the principle. But again, the way that large language models came to be and what they are optimized for is wildly different than the way that human beings came to be and what they're optimized for. So I think we're missing a chance to be much more clear-headed about what large language models are by judging them against human beings. Again, both in positive ways and negative ways.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  21. “Do I went around a block that it didn't like? And so it gets annoyed, right? It says like, no, why are you doing it? It doesn't say exactly in this, but you know what I mean? It's like, no, turn left, turn left, and you turn right. It is impossible as a human being not to feel a little bit sad that Google Maps is getting mad at you. It's not. It's not even trying to. It's not a large language model. It's not no aspirations to intentionality. But we attribute that all the time. Dan Dennett, the philosopher, wrote a very influential paper on the intentional stance. The fact that it's the most natural thing in the world for we human beings to attribute more intentionality to artificial things than are really there, which is not to say it can't be really there. But if you're trying to be rational and clear thinking about this, the first step is to recognize our huge bias.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  22. “I don't think that there are many limits in principle. I'm a physicalist about consciousness and awareness and things like that. I see no obstacle to, in principle, building an artificial machine that is indistinguishable in thought and cognition from a human being. But we're not trying to do that, right? What a large language model is trying to do is to predict text. That's what it does. And it is leveraging the fact that we human beings, for very good evolutionary biology reasons, attribute intentionality and intelligence and agency to things that act like human beings. As I was driving here to get to this podcast space, I was using Google Maps. And Google Maps was talking to me, but I wanted to stop to get a cup of coffee. So I didn't do what Google Maps told me to do.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  23. “My intuition is basically that artificial intelligence is different than human intelligence. And so the mistake that is being made by intelliging on AGI among those who do is an artificial agent, as we can make them now or in the near future, might be way better than human beings at some things, way worse than human beings at other things, and rather than trying to ask how close is it to being a human-like intelligence, we should appreciate it for what its capabilities are. And that will both be more accurate and help us put it to work and protect us from the dangers better rather than always anthropological.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  24. “Yeah, I think they will create better and better simulations. I think the philosopher David Chalmers has done what I consider to be a good job of arguing that we should treat things that happen in virtual reality and in simulated realities as just as real as the reality that we experience. I also think that as a practical matter, people will realize how much harder it is to simulate a realistic world than we naively believe. So this is not a my lifetime kind of worry.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  25. “You want to know whether it's plausible. You want to know if there's a plausible. Reasonable non zero credence to attach to this. I don't think that there's any. Philosophical knockout objection to the simulation hypothesis. I also think that there's absolutely no reason to take it seriously”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  26. “My own podcast listeners, Mindscape listeners, tease me because they know from my AMA episodes that if you ever Start a question by asking Do you think it's possible that? Answer is going to be yes That might not be the answer that you care about, but it's possible, sure, as long as you're not, you know, adding two even numbers together and getting an odd number.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  27. “Yes, I think that specifically the question why is there something rather than nothing? Not have the kind of answer that we would ordinarily attribute to why questions. Because a typical Y questions are embedded in the universe. And when we answer them, we take advantage of the features of the universe that we know and love. But the universe itself, as far as we know, is not embedded in anything. Bigger or stronger, and therefore it can just be.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  28. “There's one pitfall that I'll just mention because there's a move that is made in these theoretical edges of cosmology that I think is a little bit mistaken, which is to say, I'm going to think about the universe on the basis of imagining that I am a typical observer. This is called the principle of typicality or the principle of mediocrity or even the Copernican principle. Nothing special about me. I'm just typical in the universe. But then you draw some conclusions from this. And what you end up realizing is you've been hilariously presumptuous because by saying I'm a typical observer in the universe, you're saying typical observers in the universe are like me. And that is completely unjustified by anything. So I'm not telling you what the right way to do it is, but these kinds of questions that are not quite grounded in experimental verification or falsification are ones you”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  29. “It's absolutely legit to ask questions, but you have to be comfortable with the possibility that the answer is there's no such thing as outside our universe. That's absolutely on the table. In fact, that is the simplest. Most likely to be correct answer that we know of.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  30. “Well, I think that if there is a first moment of time, that would be very good evidence or that would fit hand in glove with the idea that time is emergent. If time is fundamental, then it tends to go forever, because it's fundamental.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  31. “When the universe had infinite curvature, infinite energy, infinite expansion rate, the whole bend. That's just a fancy way of saying the theory has broken down and classical general relativity is not up to the task of what saying what really happened at that moment. So it is completely possible there was in some sense a moment of time before which there were no other moments. And that would be the Big Bang. Even if it's not a classical general relativity kind of thing, even if quantum mechanics is involved, maybe that's what happened. It's also completely possible. There was time before that, space and time, and they evolved into our hot Big Bang by some procedure that we don't really understand.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  32. “Not that much. Quantum gravity will help, and maybe black holes will help us figure out quantum gravity so indirectly, yes, but we have the situation where general relativity, Einstein's theory, unambiguously predicts there was a singularity in the past. There was a moment of time.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  33. “We had no idea. I think that's a super important question that I can imagine making progress on But right now I'm more or less maximally uncertain about what the answer is.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  34. “Well, it depends on again exactly what you're asking. Like, there are some simple questions. What was the temperature of the universe 30 seconds after the Big Bang? We can answer that, right? That's kind of amazing that we can answer that to pretty high precision. But if you want to know where every atom was, then no.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  35. “It depends on the level of precision you're trying to ask that question. You know, the universe contains the information about where the universe was, but you and I don't. We're nowhere close.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  36. “We can, but the act of forming a memory increases the entropy of the universe. It is an irreversible process also, right? You can walk on a beach and leave your footprints there. That's a record of your passing. It will eventually be erased by the ever-increasing entropy of the universe.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  37. “As far as we know, so according to many worlds, the wave function of the universe, all the branches of the universe at once, all the worlds, does contain all the information. Calling it a memory is a little bit Dangerous because it's not the same kind of memory that you and I have in our brains our memories rely on the arrow of time. And the whole point of the Schr ⁇ dinger equation or Newton's laws is they don't have an arrow of time built in. They're reversible. state of the universe not only remembers where it came from but also determines where it's going to go in a way that our memories don't do that”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  38. “That's right, all of quantum mechanics, all different versions require a kind of arrow of time. It might be different in every kind. The quantum measurement process is irreversible. You could measure something, it collapses, you can't go backwards. If someone tells you the outcome, if I say, I've measured an electron, it spin is clockwise. And they say, what was it before I measured it? You know there was some part of it that was clockwise, but you don't know how much, right? And many worlds is no different. But the nice thing is that the kind of arrow of time you need in many worlds is exactly the kind of arrow of time you need anyway for entropy and thermodynamics and so forth. You need a simple low entropy initial state. That's what you need in both cases.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  39. “To make that extrapolation, to take seriously the equation that we know is correct in other regimes requires new philosophy, requires a new way of thinking about identity, about probability, about prediction, a whole bunch of things. And it's work to do that philosophy, and I've been doing it, and others have done it, and I think it's very, very doable. But it's not straightforward. It's not a simple extrapolation front we already know. It's a grand extrapolation very far away. And if you just wanted to be sort of methodologically conservative and say, that's a step too far, I don't want to buy it, I'm sympathetic to that. I think that you're just wimping out. I think that you should have more courage, but I get the impulse.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  40. “Yes, in fact, let me put it this way the single best reason in my mind to be skeptical about many worlds is not because it doesn't make sense or it doesn't fit the data, or I don't know where the worlds are going or whatever, it's because”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  41. “Many worlds comes about by taking the Schr ⁇ dinger equation seriously. The Schr ⁇ dinger equation was invented to fit the data, to fit the spectrum of different atoms and different emission and absorption experiments. And it's perfectly legitimate to say, well, okay, you're taking this Schr ⁇ dinger equation, you're extrapolating it, you're trusting it, believing it beyond what we can observe. I don't want to do that, right? That's perfectly legit, except then what do you believe? Come up with a better theory. You're saying you don't believe that Schr ⁇ dinger equation. Tell me the equation that you believe in. Turns out, and people have done that, turns out it's super hard to do that in a legitimate way that fits the data.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  42. “You know, I don't think it's that hard. Those are that hard for me. I don't mind the idea that when I make a quantum mechanical measurement, there is later on in the universe multiple descendants of my present self who got different answers for that measurement. I can't interact with them. Hilbert space, the spaceball quantum wave functions was always big enough to include all of them. I'm going to worry about the parts of the universe I can observe. So let's put it this way.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  43. “So the short answer is The worlds don't exist in space. Space exists separately in each world. So, I mean, there's a technical answer to your question, which is Hilbert space, the space of all possible quantum mechanical states. But physically, you know, we want to put these worlds somewhere. That's just a wrong intuition that we have. There is no such thing as the physical spatial location of the worlds because space is inside the worlds.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  44. “In which the spin was clockwise, once that exists, it is completely unaffected by the part of the wave function that says the spin was counterclockwise. They are apart from each other. They are uninteracting. They have no influence. What happens in one part has no influence in the other part. So Everett says the simple resolution is to identify yourself as either the one who saw spin clockwise or the one who saw spin counterclockwise. There are now two people once you've done that experiment. The Schrodinger equation doesn't have to be messed with. All you have to do is locate yourself correctly in the wave function. That's many worlds.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  45. “Everett's move, which was kind of genius, was to say the problem is not the Schr ⁇ dinger equation. The problem is you have misidentified yourself in the Schr ⁇ dinger equation. You have said, oh, look, there's a person who saw counterclockwise. There's a person who saw clockwise, I should be that superposition of both. I never says, no, no, no, you're not. Because the part of the wave function...”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  46. “Hugh Everett, who was a graduate student in the 1950s, was thinking about this, says, I have a better idea. Part of the wave function does not magically disappear. It stays there. The reason why that idea, Everett's idea, that the whole wave function always sticks around and just obeys the Schr ⁇ dinger equation, was not thought of years before, is because naively you look at it and you go, okay, this is predicting that I will be in a superposition, that I will be in a superposition of having seen the electron be clockwise and having seen it be counterclockwise. No experimenter has ever felt like they were in a superposition. You always see an outcome, okay?”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  47. “What will happen is that you and the electron will entangle with each other. And by that I mean that the state of the universe evolves into parts saying the electron was spinning clockwise and I saw it clockwise and part of the state is it's in a superposition with the part that says the electron was spinning counterclockwise and I saw it counterclockwise. Everyone agrees with this, entirely uncontroversial, straightforward consequence of the Schr ⁇ dinger equation. And then Niels Bohr would say, and then part of that wave function disappears. And we're in the other part. And you can't predict which part it will be, only the probability.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  48. “What does it mean to measure the spin of the electron We don't need to go into details, but we want the following thing to be true. If the electron were in a state that was 100% spinning clockwise, then we want the measurement to tell us it was spinning clockwise. We want your brain to go, yes, the electron was spinning clockwise, right? Likewise, if it was 100% counterclockwise, we want to see that, to measure that. The rules of quantum mechanics, the Schr ⁇ dinger equation of quantum mechanics, is 100% clear that if you want to measure it clockwise when it's clockwise and measure it counterclockwise when it's counterclockwise, then when it starts out in a superposition,”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  49. “What caused it to happen? Why it's happening, none of that. That's all called the measurement problem of quantum mechanics. Many worlds just says, Look, I just told you a minute ago that there's only one way function for the whole universe. And that means that you can't take too seriously just describing the electron. You have to include everything else in the universe. In particular, you clearly have to interact with the electron in order to measure it. So whatever is interacting with the electron should be included in the wave function that you're describing. And look, maybe it's just you. Maybe your eyeballs are able to perceive it. But okay, I'm going to include you in the wave function. And if you do that, let's be, since you have a very sophisticated listenership, I'll be a little bit more careful than average.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source

  50. “According to the rules of quantum mechanics, I can set up an electron, let's say, in a state where it is neither purely clockwise or counterclockwise, but a superposition of both. And that's not just because we don't know the answer. It's because it truly is both until we measure it. And then when we measure it, we see one or the other. So this is the fundamental mystery of quantum mechanics, is that how we describe the system when we're not looking at it is different from what we see when we look at it. So we teach our students in the Copenhagen way of thinking is that the act of measuring, the spin of the electron, causes a radical change in the physical state. It spontaneously collapses from being a superposition of clockwise and counterclockwise to being one or the other. And you can tell me the probability that that happens, but that's all you can tell me. And I can't be very specific about when it happens.”

    2024-04-22 · Lex Fridman Podcast · #428 – Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens · IDENTIFIED FROM THE TRANSCRIPT · source