Cosmic Queries – Living in a Simulation with Nick Bostrom

0:00Hey, StarTalkians, Neil here. You're about to listen to an episode specially drawn from our archives to serve your cosmic curiosities. The archives run deep. If you enjoy this, take a peek at the full catalog on your favorite podcast platform. There's a lot there to tickle your geek underbelly. Check it out. Welcome to StarTalk. Your place in the universe where science and pop culture collide. StarTalk begins right now. This is StarTalk. Cosmic Queries edition. Neil deGrasse Tyson here. You're a personal astrophysicist. I got Chuck Nice with me, of course. Chuck, my... What's up, Neil? Faithful co-host.

0:50You know, we need you for the Cosmic Queries so that you can mispronounce everyone's name. Well, that's my purpose in life, Neil. That's right. I live to butcher names. No. Those poor questioners. How would you attack my name? Oh, my goodness. So, Nick Bostrom? Is that how it's? It's pretty good. That's all right. Is that all right? In Swedish, it would be Niklas Bostrom, but that was close. All right. And listen, I'll take close. As far as I'm concerned, names are like a game. Close is better than it. Yeah, that's like a game of horseshoes for me. Close? Is good enough. Good enough. So that was indeed Nick Bostrom chiming in.

1:40Nick, welcome to StarTalk. Dude, you started something that has got the whole world, you know, spinning in a tizzy for birthing the concern that we all live in a simulation. And let me just give a fast bio on you. You're a professor at University of Oxford. and the Future of Humanity Institute. Oh, that doesn't look very bright. It doesn't look very bright. Sorry, Nicholas. Not a lot of job security in that, buddy. No future for humanity. Looking at the future of humanity, yo. So you think about artificial intelligence, the ethics of artificial intelligence, change, biosecurity, macro strategy.

2:33We'll ask you what that is in a moment. Just policy, ethics, foundational questions about serious challenges that civilization faces, not in the distant future, but in the very near future. I like the fact that you have a background in theoretical physics. So put you in the physics club here. That's good. Also computational neuroscience. We have some of those at my home institution at the American Museum of Natural History. That's quite the frontier as well. And you had a rather influential paper, research paper, titled, Are You Living in a Computer Simulation? And for me, also, I remembered your book, Superintelligence, which all of these got people thinking, as any good philosopher should do, is to get people thinking.

3:24And so could you just start us off? Why do you think we might be living in a simulation? Well, I have this thing called the simulation argument, which doesn't actually prove that we're in a simulation, but it tries to show that at least one of three propositions is true. So we want to hear your line of reasoning, which ought to be good given your sort of logical background in this universe. So let's hear what you've got. um well i mean you probably would be able to explain it better but yeah my story is that um the simulation argument tries to show that one of three propositions is true so let's let's first look at what the conclusion is and then we can see how we get there so the conclusion is that either almost all civilizations at our current stage of technological development go extinct before they become technologically mature so that's like one alternative right the second is that amongst civilizations that do become technologically mature, there is a very strong convergence.

4:24They all lose interest in creating a certain kind of computer simulation. I call them ancestor simulations. These would be detailed simulations of people with the kind of experiences that their historical forebears had. So that's the second alternative. And then the third alternative is that we are almost certainly living in a computer simulation. So that's the kind of conclusion. Now, how does one get to that? Well, suppose that the first of these alternatives does not obtain. So that means it's not true that almost all civilizations at our stage fail to reach technological maturity. Some non-trivial fraction make it through.

5:06Then let's suppose that the second alternative is also false. So amongst those who do become technologically mature, some non-trivial fraction remain interested in using some of the resources to create these kinds of ancestor simulations. Then you can show that the kind of computational resources a mature civilization would have would suffice to create millions and billions of detailed simulations, ancestor simulations, runs of human history. And so that if the first two alternatives are false, then there would be many, many more simulated versions of people with our kinds of experiences, then that would be original, implemented in basic physical reality, people with our experiences.

5:54And conditional on that, if almost all people with our experiences are simulated, we should think we are probably one of the simulated ones rather than one of the rare non-simulated ones. So that means that if you reject the first two alternatives, you would then have to accept the third one. and then that shows that it's not the case that all three of them are false. So hence, at least one of them is true. So that's the structure. Why can't there be a fourth other truth that no one gives a rat's ass about simulating anything anywhere? Well, so that's the second, right? I mean, so if all of these technologically mature civilizations are completely uninterested in simulating, then that would be possibility number two.

6:38But note that for the second alternative to hold, it's not sufficient that most of them are not very interested. Because even if it were just, say, 1 % of these mature civilizations that were even a little bit interesting, they still could produce millions of them. And so that would have to be this extremely strong convergence. Like, almost all of them would completely have to lose any interest in doing this in order for the second alternative to be the true. Okay, so I have publicly, mildly butchered your line of argument there. So let me first apologize. What I had been noting is that we do not have the power yet to create a perfect simulation of a world such as the one we're living in.

7:26And so I wasn't thinking that everyone would make these ancestor simulations, which we would be. And so an ancestor civilization in a cinematic parallel would be a movie about Spartacus or Cleopatra. Just something, a movie, which is modern technology, telling a story set in a time when they didn't have movies, right? So that would be like an, I'm guessing that's what you mean by an ancestor simulation. And so I was thinking that every simulation would ultimately be able to duplicate themselves as a natural evolutionary arc. If that's the case, then we would either be the original universe that hasn't yet simulated anybody yet, or we'd be sort of the last one simulated still working our way towards the power of simulating ourselves, which would be slightly better odds, well, a lot better odds than throwing a dart and landing in all the simulations that had enough power to create simulations of themselves.

8:37Yeah, well, I... Did any of that make sense? Well, so first of all, I don't claim that the only simulations that might be made are ancestor simulations. I mean, if you imagine you're a technological material of civilizations, you might simulate all kinds of things like real histories as close as you can get, fantasy worlds, counterfactual histories, imaginary alien civilizations. I mean, you could maybe there are like lots of all of these kinds of simulations. The argument focuses on ancestor simulations just because that's the easiest way to get to the conclusion that one of these three is true.

9:11But it doesn't imply that there wouldn't be lots of other simulations as well. Okay, so we have some data with our own history of cinema and it's some very small percent of movies are set in a time before movies were invented, which, again, I would classify as sort of ancestor storytelling. Yeah, so I mean, I guess when we extrapolate to these technologically mature, presumably post-human civilizations, well, first of all, I'm not sure how much we can infer from the kinds of movies we create to what types of simulations they would run. But let's suppose for the sake of the argument that the majority of simulations they run are of people in their contemporary society.

9:53So I don't know, some super advanced space colonizing thing with super intelligence or whatnot. And that's maybe the majority of what they do, but that they assign some smaller fraction of their computational resources to doing these ancestry simulations. Let's assume that. I still don't think that would defeat the simulation argument or indeed even the alternative that we are in a simulation because we kind of already know that we are not one of the post-humans. I mean, you just look around, you don't see a lot of starships whizzing outside your window and we are not currently running any simulations ourselves.

10:35So we can kind of cross those out. Like all the actual post-humans, we know we're not one of those and we also know we are not in a simulation of the post-humans. That's not the world we experience. then that leaves only, A, the people in original history at the human level of development, and also whatever ancestor simulations are at that level of development. And so my claim would then be that, you know, if the first two alternatives of the simulation argument are false, the simulated ones at our current level of development would still vastly outnumber the original ones at our stage of development.

11:10So what is the likelihood that, not likelihood, because that's the wrong word, Is it possible that it could just be the way that we create with our limited technology what we feel are simulations of our lives, okay? And that's computer games and video games and things like that. Could it be that a civilization so advanced that they have the computational power to create all of this just for the hell of it? Just because, like, the same way we do it. We do it for entertainment. Could it just be that? Or is that just not a part of the philosophy? It could be. I mean, so the simulation argument itself is agnostic as to what the motivation would be of the simulators.

11:55And you could indeed imagine many possible motivations. One would be just entertainment, right? And you could imagine other, like maybe some kind of research, like historically, maybe it would be interesting to explore counterfactuals of history. Or you could imagine art projects. So you could imagine moral reasons for, I think we know rather a little about the psychology and motivations of these hypothetical post-human civilizations and why they would make simulations. Okay, so Nick, I guess you're allowed to say all this like from your armchair, but at some point somebody wants to walk into a lab and make a measurement that says, here's the evidence that supports Nick's argument.

12:39Is there such a, anything we can look for? Is there a sign? Is there some experiment we can conduct and say, yep, we're not in charge of what's happening here. This is a simulation. There certainly is sort of empirical premises that flow into the simulation argument. And so evidence for or against the truth of those assumptions, would be relevant to evaluating the argument. So one empirical premise is that a technologically mature civilization would indeed have the capability of creating ancestor simulations and indeed to create lots of them. And so the kinds of evidence that would be relevant for that is evidence, say, of the kinds of computational performance you could get from physically possible systems.

13:32We're not able to build them currently, but we can kind of do first principle modeling of different computational systems based on nanotechnology and so forth. And we can place lower bounds on the kind of compute power that they would unlock. So that would be one element that would flow into this. Another would be some estimate of the computational cost of running an ancestor simulation. I think the largest part of that cost is the cost of simulating human brains at the sufficient level of detail that the simulation would be conscious. And we can obviously not precisely determine what the computational expense of simulating a human brain is, but we can place some upper bound on that.

14:16We have various views about what computational tasks the human brain is capable of performing. We know how many neurons there are, how many synapses, how often they fire. We can roughly estimate that. Now, it turns out that if you estimate the amount of compute power available, even if you make rather conservative assumptions about that and then you make conservative assumptions about how much it takes to simulate one human brain and therefore how much to simulate all of the human brains. You just multiply that by 100 billion or something to all of the human brains in history. There are a number of orders of magnitude gap between these two.

14:51So even if you are off a little bit in these estimates, it still seems like the argument holds. So those would be empirical premises that we could theoretically obtain evidence against. Like if we discover the human brain uses some kind of weird quantum computation that is a lot more expensive and that would flow into it. Then if in addition you want to conclude not just that one of these three alternatives is true, which is all the simulation argument itself says, but if more specifically you want to conclude that we are in a simulation, that the third alternative is true, then there is an additional range of empirical questions that become relevant.

15:23Like anything that gives you evidence against the first two or in favor of the first two would be then relevant evidence for evaluating the third, right? So if we discover that there is some kind of big risk, some doomsday mechanism that we can, ah, now we realize this, all sufficiently advanced civilizations will stumble on this new technology and destroy themselves, that would be argument against the simulation hypothesis because it would make the first alternative more likely. So that, I think, is actually the main kind of evidence. That would be a really sad argument. But that'd be a really sad argument against it because it would say, here's our proof we're not simulated.

15:57We're going to blow everything up. Now, Nick, let me ask you this. Let me ask you this, Nick. Is it possible that you are so smart that you are constantly high and you don't know it?

16:17I think in some more or less metaphorical sense, I think that's very likely to be true. It's kind of the pessimistic meta-induction. So if you look at all humans who have ever been alive, all eras going back in time, we can now see from our current vantage point, And basically, they were all very wrong about some big thing. I mean, like starting with simple physics, they thought Earth was in the center. And then like, basically, we can see if we look back more than 100 years, we see that they all got a whole bunch of really core things wrong. And it would kind of maybe be a little bit presumptuous to think that now, finally, we've gotten all of these basic things right.

16:58It seems more likely that if people a thousand years from now look back at 2021, they will probably also see big, not just gaps in our understanding, but like things we were fundamentally confused about. And so... Yeah, they'll laugh their ass off at everything we're talking about. Yeah, or Christ, they're out, or whatever. So I do think we are, in a fundamental sense, very much in the dark about the really biggest picture.

17:40Hey, this is Kevin the Sommelier, and I support StarTalk on Patreon. You're listening to StarTalk with Neil deGrasse Tyson.

17:57Before we get to the questions that Chuck has collected, Nick, it's one thing to simulate all the brains. I get that. But it's another thing, the fact that I can go into a garden and then look at a flower or dig through the soils and keep digging and reach the mantle of the earth. Whoever is simulating us has to simulate not only what my brain is doing, but it has to simulate all the things my brain is experiencing. And that's not just for me. Someone else could dig that same hole and they should be finding the same thing. So isn't the total complexity of the world, doesn't that have to be part of this simulation?

18:37Even the fact that I, as an astrophysicist, look out to the edge of the universe, decoding the nature of the Big Bang and all time and space that followed it. So why just limit your estimates to the power of the human brain if everything and the unfolding of the great cosmic story has to also happen alongside it? Yeah, I think you do need some computation assigned to simulating relevant parts of the environment. I think the biggest part will be the brains, but certainly if you had to simulate all of the environment at subatomic detail continuously, I mean, like quantum simulation of the entire universe would be completely infeasible if the simulators have anything comparable to the compute power that we could realize in this universe.

19:27You know what? I'm going to disagree. I'm sorry. I know you're a genius, but here's the deal. Here's why I'm going to disagree, Nick. Because when movie makers make movies, they do not render the detail in every single little thing. What they have, he didn't get there yet. That was the next thing he was going to talk about. Oh, man. You're ahead of me. See, you already thought of this. Like I said. No, man. Jesus Christ. Here I am making a discovery, man. All right, Chuck. Okay, continue. Wait, Chuck, finish the point. And then we'll pick it up there. Well, you got, both of you already knew where I was going.

20:10But the deal is this. If you actually create a background, that background will pretty much be the same for all the characters that are mapped onto that background. So that's the way, that's all I was saying. No, I mean, I think that's the key to understand this whole simulation argument stuff. that if you had to simulate all of the environment in subatomic detail continuously, it probably would be completely infeasible to do that. But I claim that's not needed. All you would need to do is to simulate enough of the parts that we are observing, when we are observing them, that to the simulated creatures, it looks real and that they can't tell the difference.

20:43And that's a lot less. All right, wait a minute. I just thought of something else in support. So what that would mean, Chuck, Chuck, check what that would mean. Whole sections of the Pacific Ocean where there isn't a boat, right? then no one has... So it doesn't exist until someone has to then see it and process it. So procedural content generation. So we use it in our computer games today a lot. Like you often only render the parts that some character in the game are observing. And maybe you have some very coarse-grained simulation of the whole thing continuously, but you may fill in details if and when is needed.

21:21So if, like right now, I don't have any idea what the atoms in this desk in front of me are doing, right? But if I took, in principle, an electron microscope or something, I could look and I better see atoms there, right? The programmer would know you're about to bring out an electron microscope. Right. So they could see that. The calculation right in the beam right there. And if necessary, I mean, they could even pause the simulation or edit it or erase memories if they really screwed it up. But yeah, I think the kind of capability you would need to even create anything resembling this kind of simulation is very advanced.

21:59And I think with that advanced capability would also come the ability to edit and to monitor human thoughts and intentions and then kind of be able to do this kind of procedural generation that even we do in our computer games today. That could explain why I've heard Neil say this, that we are terrible data takers. Like, as human beings, we are awful at taking in information. Well, if I'm programming a simulation, I would certainly want to program the people in that simulation to be like that, because that way I wouldn't have to program all this detail into stuff. It protects the integrity of my simulation.

22:46yeah although i think to be fair i think the difference between one human and another from the point of view of the simulators it's like well there is one and it's got a few more neurons it's this genius ant but i mean we all like ants i think uh so i don't think the difference in cost is that big uh cool very cool uh all right all right chuck bring up bring on a question let's All right, here we go. Let's jump into this. This is Dennis Gislein. And Dennis says this. Wait, spell that? G-H-I-S-L-A-I-N. I say Gislein. Yeah, it's probably Gislein. Gislein. Okay. Gislein. My minute would be Denis Gislein.

23:33Okay. Gislein. Denis Gislein. We'd like to know. He says, in his papers, Dr. Bostrom talks about post-human stage civilization. Could you please develop on that and situate it in, listen, Kardashev scale. Now, I don't know what any of that means. Okay, I can tell you what the Kardashev scale is. What is the Kardashev scale? Yeah, why don't I lead off with that, and I'll hand the baton over to you, Nick. Nick, so the Kardashev scale is a scale of how much energy you have access to and can exploit. Oh, okay. Okay, so I think there are five levels. So one of them is, do you have access to all of the energy sources in your host planet?

24:25And if you do and you can exploit them, you're civilization level one. So that means you can go into a volcano and tap the volcano the way you tap a cake. You could use the energy in the crust of the Earth that would otherwise make earthquakes. You can tap that and use that for your own means. Storm systems, this sort of thing. So a level two civilization would control all of the energy that comes from its host star. Okay. Okay. So it's way more energy than what is embedded in your planet. A level three civilization would control all the energy of your galaxy that you happen to live in. So the massive black hole at the center of the galaxy, you could use that.

25:11Yeah, exactly, exactly. And you wield this. And the history of civilization reveals that the nations or the nation states that had the most power, power, political power, cultural power, were those that actually wielded the most energy per capita in the world at that time. So when people say, United States, we're such energy hogs. We use, you know, four times, they have five times the energy as anybody else. Well, that correlates with other measures of power that exist in it. So let's keep going. So one more, level four, level five, if you control all the energy of the universe, and then you're indistinguishable from a god that anyone would have suggested.

25:59Now, so what are we? We're digging fossil fuels out of the earth. So we're level 0.5. We're level 0.3. No, we're level zero, okay? We're level zero. Okay, so Nick, if there's a super intelligence, presumably they have better access to energy, especially the kind of energy you're talking about that might need this simulation. So have you thought about where a super intelligence might fit on the Kardashev scale? Yeah, I mean, I think that would be higher up just because at that level, you would be able to run a lot more of these simulations. and so even if there were some simulations run by I don't know, a Kardashev scale one civilization like with the Dyson sphere around their south and that's all they did you know, once the civilization expands beyond that they could run billions of times more and there would be plenty of time for them to expand beyond that so you could imagine almost all simulations that are run are being run by civilizations that have reached the limits of whatever space they have to expand into.

27:07That would presumably be Kardashev 4 or something, unless the universe is so crowded that each one only manages to get the sort of galactic level volume before it bumps up against its neighbors. Yeah, that's a good point because you can only have one galactic, Kardashev-scale civilization because anyone else who wants it too bad, we're using all the energy. It's like in the United States right now, there's fights over the Colorado River Basin because it's a water source That river flows through multiple states, and each state has a pact with the other state, how much water they're supposed to use.

27:42And there'll be future fights on access to this one source of fresh water. And so that's an interesting point. You can't have a universe filled with high Kardashian-level civilization because they would implode rapidly, it seems to me. And what level is Death Star? What level is Death Star on the Kardashian scale? Oh! Well, in Star Wars Episode VII, it controlled the energy of a star. So that would be, I guess, level two. That's only level two. Wow. Awesome. Okay. Here we go. Let's jump right back in here. By the way, in Star Trek, the Borg, that's a super intelligence that was cosmic in its influence.

28:29And so that would be even higher here. Right, yeah. Just to put that in context. That's cool. So Chuck, give me another one. Okay, this is William D.A. Quite easy. Nothing but letters. Here we go. He says, where do you stand on the concept of consciousness and where do you draw the line? Would a simulated reality change your definition of what possesses consciousness? I like that. So Nick, is panpsychic? I presume that means that somehow consciousness is a shared entity that we all participate in as one organism. There are different sort of definitions, but it's broadly the view that everything is conscious.