Transcript for Sean Carroll: The Nature of the Universe, Life, and Intelligence

You know, of course this is a crazy meaning was unanswerable question in some sense because they're both very interesting and there's no absolute scale of interestingness that we can rate them on. There's the glib answers that says the human brain is part of the universe, right? And therefore understanding the universe is more fundamental than understanding the human brain.

No, certainly not. We cannot understand how ice cream works just from understanding how particles work, right? So a big believer in emergence. I'm a big believer that there are different ways of talking about the world. beyond just the most fundamental microscopic one, you know, when we talk about tables and chairs and planets and people, we're not talking the language of particle physics and cosmology. So, but understanding the universe, you didn't say just at the most fundamental level, right? So understanding the universe at all levels is part of that. I do think, you know, to be a little bit more fair to the question, there are probably our general principles of complexity, biology, information processing, memory, knowledge, creativity that go beyond just the human brain, right? And maybe one could count understanding those as part of understanding the universe. The human brain as far as we know is the most complex thing in the universe. So there's certainly absurd to think that by understanding the fundamental laws of particle physics, you get any direct insight on how the brain works.

No, to be like the honest answer there is no. There's a sense in which the universe processes information clearly. There's a sense in which the universe is like a computer clearly. But in some sense, I think I tried to say this once on my blog and no one agreed with me, but the universe is more like a computation. than a computer, because the universe happens once. So a computer is a general purpose machine, right? That you can ask it different questions, even a pocket calculator, right? And it's set up to answer certain kinds of questions. The universe isn't that. So information processing happens in the universe, but it's not what the universe is. Because I know your MIT colleague, Seth Lloyd, feels very differently about this, right?

Do you think of intelligence in this way? Intelligence is tricky. I don't have a definition of it on hand. So I remember this panel discussion that I saw in YouTube I wasn't there, but Seth Lloyd was on the panel and so it was Martin Rees, the famous astrophysicist. And Seth gave his stick for why the universe is a computer and he explained this and Martin Rees said, so what is not a computer? That was like, oh, that's a good question. I'm not sure, or if you have a sufficiently broad definition of what a computer is, then everything is, right? And the similar or the analogy gains force when it excludes some things. You know, is the moon going around the earth performing a computation? I can come up with definitions in which the answer is yes, but it's not a very useful computation. I think it's absolutely helpful to think about the universe in certain situation, certain contexts, as an information processing device. I'm even guilty of writing a paper called Quantum Circuit cosmology, where we modeled the whole universe as a quantum circuit. As a circuit, yeah, and with a few bits basically, right? Yeah. So in Cuba, it's becoming more and more entangled. So do we want to digress a little bit? This is good. Kind of fun. So here's a mystery about the universe that is so deep and profound that nobody talks about it. space expands, right? And we talk about in a certain region of space, a certain number of degrees of freedom, a certain number of ways that the quantum fields and the particles in that region can arrange themselves. That number of degrees of freedom in a region of space is arguably finite. We actually don't know how many there are, but there's a very good argument that says it's a finite number. So as the universe expands and space gets bigger, are there more degrees of freedom if it's an infinite number it doesn't really matter infinity times two is still infinity but if it's a finite number then there's more space so there's more degrees of freedom so where did they come from that would mean the universe is not a closed system there's more degrees of freedom popping into existence So what we suggested was that there are more degrees of freedom, and it's not that they're not there to start, but they're not entangled to start. So the universe that you and I know of, the three dimensions around us that we see, we said those are the entangled degrees of freedom making up space time as the universe expands. There are a whole bunch of qubits in their zero state that become entangled with the rest of space time through the action of these quantum circuits.

Yeah, so this is the universe expands. That's right. So there's more and more degrees of freedom. They're entangled that they're playing the role of parts of the entangled spacetime structure. So the basic, the underlying philosophy is that spacetime itself arises from the entanglement of some fundamental quantum degrees of freedom.

Yeah, so the idea is that at the big bang almost all the degrees of freedom that the universe could have. We're there, but they were unentangled with anything else. And that's a reflection of the fact that the Big Bang had a low entropy. It was very simple, very small place. And as space expands, more and more degrees of freedom become entangled with the rest of the world.

So obviously, we could be living in a simulation. If you just want the physical possibility, then I completely agree that it's physically possible. I don't think that we actually are. So take this one piece of data into consideration. We live in a big universe. There's two trillion galaxies in our observable universe, two hundred billion stars in each galaxy, et cetera. It would seem to be a waste of resources to have a universe that big going on just to do a simulation. So in other words, I want to be a good Bayesian. I want to ask, under this hypothesis, what do I expect? to see. So the first thing I would say is I wouldn't expect to see a universe that was that big, okay? The second thing is I wouldn't expect the resolution of the universe to be as good as it is. So it's always possible that if our superhuman simulators only have finite resources that they don't render the entire universe, right? That the part that is out there, the two trillion galaxies, isn't actually being simulated fully, okay? But then the obvious extrapolation of that, is that only I am being simulated fully. Like the rest of you are just non-player characters, right? I'm the only thing that is real, the rest of you are just chatbots. Beyond this wall, I see the wall, but there is literally nothing on the other side of the wall. That is sort of the Bayesian prediction. That's what it would be like to do an efficient simulation of me. So none of that seems quite realistic. I don't see, I hear the argument that it's just possible and easy to simulate lots of things. I don't see any evidence from what we know about our universe that we look like a simulated universe. Now, maybe you can say, well, we don't know what it would look like, but that's just abandoning your Bayesian responsibilities. Your job is to say, under this theory, here's what you would expect to see.

I wrote a little blog post about this and maybe I'm missing something but there's an argument that says not only that it might be possible to simulate a universe but probably if you imagine that you actually attribute consciousness and agency to the little things we're simulating to our little artificial beings There's probably a lot more of them than there are ordinary organic beings in the universe where there will be in the future, right? So there's an argument that not only is being a simulation possible, it's probable because in the space of all living consciousness is most of them are being simulated, right? Most of them are not at the top level. I think that argument must be wrong, because it falls from that argument that, you know, if we're simulated, but we can also simulate other things. Well, but if we can simulate other things, they can simulate other things, right? If we give them enough power and resolution, and ultimately, we'll reach a bottom, because the laws of physics and our universe have a bottom, or made of atoms and so forth. So there will be the cheapest possible simulations. And if you believe the original argument, you should conclude that we should be in the cheapest possible simulation, because that's where most people are. But we don't look like that. It doesn't look at all, like we're at the edge of resolution, you know, that we're 16 bit, you know, things. It seems much easier to make much lower level things than we are. So, and also, I question the whole approach to the anthropic principle that says we are typical observers in the universe. I think that that's not actually, I think that there's a lot of selection that we can do that we're typical within things we already know, but not typical within all the universe.

My guess is that there is not intelligent life in the observable universe other than us. Simply on the basis of the fact that the likely number of other intelligent species in the observable universe, there's two likely numbers, zero or billions. And if there have been billions, you would have noticed already. for there to be literally like a small number, like, you know, start track. There's, you know, a dozen intelligent civilizations in our galaxy, but not a billion. That's weird. That's sort of bizarre to me. It's easy for me to imagine that there are zero others because there's just a big bottleneck to making multicellular life or technological life or whatever. It's very hard for me to imagine that there's a whole bunch out there that have somehow remained hidden from us.

That's a great possibility because I think we should be humble about what intelligence is, what life is, we don't even agree on what life is, much less what intelligent life is, right? So that's not even for humility saying there could be intelligent life of a very different character, right? You could imagine that dolphins are intelligent but never invent space travel because they live in the ocean and they don't have thumbs, right? So they never invent technology and they never invent smelting. Maybe the universe is full of intelligent species that just don't make technology, right? That's compatible with the data, I think. And I think maybe what you're pointing at is even more out there versions of intelligence, you know, intelligence in intermolecular clouds or on the surface of a neutron star or in between the galaxies and giant things where the equivalent of a heartbeat is 100 million years. On the one hand, yes, we should be very open minded about those things. On the other hand, we all, all of us share the same laws of physics. There might be something about the laws of physics, even though we don't currently know exactly what that thing would be, that makes meters. And years, the right length and time scales for intelligent life. Maybe not. But, you know, we're made of atoms, atoms at a certain size, orbit stars, stars at a certain lifetime. It's not impossible to me that there's a sweet spot for intelligent life that we find ourselves in. So I'm hoping I didn't either way. I'm hoping I didn't either being humble and there's all sorts of different kinds of life. Or, no, there's a reason we just don't know it yet. Why life like ours is the kind of life that's out.

Well, I'm totally open to that, but so here's another argument I would make. We have looked for intelligent life, but we've looked at for it in the dumbest way we can, by turning radio telescopes to the sky. And why in the world would a super advanced civilization randomly beam out radio signals, wastefully, and all directions into the universe. That just doesn't make any sense. Especially because, in order to think that you would actually contact another civilization, you would have to do it forever. You have to keep doing it for millions of years. That sounds like a waste of resources. If you thought that, there were other solar systems with planets around them, where maybe intelligent life didn't yet exist, but might someday. You wouldn't try to talk to it with radio waves. You would send a spacecraft out there. And you would park it around there. And it would be like, from our point of view, we'd be like 2001, or there's a, you know, and monolith, monolith. So there could be an artifact. In fact, the other way works also, right? There could be artifacts in our solar system that have been put there by other technologically advanced civilizations. And that's how we will eventually contact them. We had to just have an explore the solar system well enough yet to find them. The reason why we don't think about that is because we're young and impatient, right? Like it would take more than my lifetime to actually send something to another star system and wait for it and then come back. So, but if we start thinking 100s of thousands of years, we're million year time scales, that's clearly the right thing to do.

Yeah. Now, I do think that space travel is hugely important, long term, even to other star systems. And I think that many people overestimate the difficulty, because they say, look, if you travel 1% of the speed of light to another star system, we'll be dead before we get there, right? And I think that it's much easier. And therefore, when they write their science fiction stories, they imagine we could go faster in the speed of light, because otherwise they're too impatient, right? We're not going to go faster than this beat of light, but we could easily imagine that the human lifespan gets extended to thousands of years. And once you do that, then the stars are much closer, effectively, right? And what's a hundred year trip, right? So I think that that's going to be the future, the far future, not my lifetime once again, but baby steps. And unless your lifetime gets extended, Well, it's in a race against time, right? A friend of mine who actually thinks about these things said, you know, you and I are going to die, but I don't know about our grandchildren. That's it. I don't know for putting the future is hard, but that's at least a plausible scenario. And so, yeah, no, I think that as we discussed earlier, there are threats to the Earth, known and unknown, right? Having spread humanity and biology elsewhere is a really important long-term goal.

I think an obvious one is the origin of life. We don't know how that happened. There's a difficulty in knowing how it happened historically, actually, you know, literally on earth, but starting life from non-life is something I kind of think we're close to, right?

Well, I've talked to people, including on the podcast about this, you know, life requires three things. So the life as we know it. So there's a difference with life, which who knows what it is, and life as we know it, which we can talk about with some intelligence. So life as we know it requires compartmentalization. You need like a little membrane around yourself, metabolism. You need to take in food and eat it and let that make you do things. and then replication. So you need to have some information about who you are that you pass down to future generations. In the lab, compartmentalization seems pretty easy, not hard to make lipid bilayers that come into a little cellular walls pretty easily. Metabolism and replication are hard, but replication we're close to, people have made RNA-like molecules in the lab that I think the state of the art is, they're not able to make one molecule that reproduces itself, but they're able to make two molecules that reproduce each other. Yeah, so that's okay, that's pretty close. Metabolism is harder, believe it or not, even though it's sort of the most obvious thing, but you want some sort of controlled metabolism, and the actual cellular machinery in our bodies is quite complicated. It's hard to see it just popping into existence, I'll buy it myself, and probably took a while. But it's, we're making progress. In fact, I don't think we're spending nearly enough money on it. If I were the NSF, I would flood this area with money because it would change our view of the world if we could actually make life in the lab and understand how it was made originally here on Earth.

That's right. So synthetic biology is a wonderful big frontier where we're making cells. Right now, the best way to do that is to borrow heavily from existing biology. We're Craig Ventner, several years ago, created an artificial cell, but all he did was not all he did. It was a tremendous accomplishment, but all he did was take out the DNA from a cell and put an entirely new DNA and let it boot up and go.

So AI would count in this or you really want life. You want really an organism in some sense.

But let's say artificial consciousness, right? So I do not think we are on the threshold of creating artificial consciousness. I think it's possible. I'm not again very educated about how close we are, but my impression is not that we're really close because we understand how little, how little we understand of consciousness and what it is. So if we don't have any idea what it is, it's hard to imagine we're on the threshold of making it ourselves. But it's doable, it's possible. I don't see any obstacles in principle, so yeah, I would hold out some interest in that happening eventually.

Well good no actually I like this idea that in fact consciousness is way less mysterious than we think because we're all at every time at every moment less conscious than we think we are right we can fool things and I think that plus the idea that you not only have artificial intelligence systems, but you put them in a body right give them a robot body That will help the faking a lot

No, actually, I think that is an extremely good point. And in fact, what it suggests is, you know, so yeah, you refer to Kate K. Darling who I had on the podcast and who does these experiments with very simple robots, but they look like animals and they can look like they're experiencing pain and we human beings react very negatively to these little robots looking like they're experiencing pain. And what you want to say is, yeah, but they're just robots. It's not really pain, right? It's just some electrons going around. But then you realize, you know, you and I are just electrons going around. And that's what pain is also. And so what I would have an easy time imagining is that there is a spectrum. between the simple little robots that Kate works with and a human being, where there are things that sort of by some strict definition, touring test, level thing, are not conscious, but nevertheless, walk and talk, like their conscious. And it could be that the future is, I mean, Siri is close, right? And so it might be that the future has a lot more agents like that. And in fact, rather than some day going, aha, we have consciousness, we'll just creep up on it with more and more at your reflections of what we expect.

Yeah, no, absolutely. Certainly videos are almost to the point where you shouldn't trust them already. Photos you can't trust, right? Videos easier to trust, but we're getting worse. We're getting better at faking them, right? Yeah. So physical embodied people, what's so hard about faking that? So it's very depressing. This conversation we're having right now. So, to me, it's exciting. You're doing it, so it's exciting to you, but it's a sobering thought. We're very bad at imagining what the next 50 years are going to be like when we're in the middle of a phase transition as we are right now.

Okay, you're way more optimistic than I am. I think that goodness and badness are equally distributed among intelligent and unintelligent people. I don't see much of a correlation there.

Well, the obvious one is what is good and bad, you know, what is right and wrong. I think that there are questions that science tells us what happens, what the world is and what it does. It doesn't say what the world should do or what we should do because we're part of the world. But we are part of the world and we have the ability to feel like something's right, something's wrong. And to make a very long story very short, I think that the idea of moral philosophy is systematizing our intuitions of what is right, what is wrong. And science might be able to predict ahead of time what we will do, but it won't ever be able to judge whether we should have done it or not.

It's a good question, but a tough one to answer. I think about, you know, a guy knows a personal trainer, and he was asked on a podcast. How do we, you know, psych ourselves up to do a workout? How do we make that discipline to go and work out? And he's like, why are you asking me? Like, I can't stop working out. Like, I don't need to psych myself up. So, and like, why is, you know, he asked me like, how do you get to, like, have interdisciplinary conversations and all sorts of different things and all sorts of different people? And like, that's, That's what makes me go, right? Like that's I couldn't stop doing that. I did that long before any of them were recorded. In fact, a lot of the motivation for starting recording it was making sure I would read all these books that I had purchased, right? Like I had all these books that I wanted to read, not enough time to read them. And now if I have the motivation because I'm going to, you know, interview Pat Churchill and I'm going to finally read her book, you know? And it's absolutely true that academia is extraordinarily siloed, right? We don't talk to people. We rarely do. And in fact, when we do it's punished, you know, like the people who do it successfully, generally first became very successful within their little siloed. You have to discipline and only then did they start expanding out if you're a young person. You know, I have graduate students. I'd probably be very, very candid with them about this that it's, you know, most graduate students are to not become faculty members, right? It's a tough road. And so, live the life you want to live, but do it with your eyes open about what it does to your job chances. And the more broad you are and the less time you spend hyper specializing in your field, the lower your job chances are. That's just an academic reality. It's terrible, I don't like it, but it's a reality. And for some people, that's fine. Like there's plenty of people who are wonderful scientists who have zero interest in branching out and talking to things to anyone outside their field. But it is disillusioning to me, some of the romantic notion I had with the intellectual academic life is belied by the reality of it. The idea that we should reach out beyond our discipline. And that is a positive good. is just so rare in universities that it may as well not exist at all.

No, thanks. Thank you very much for this conversation. It was great.