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If you consider that the latest human technology humans created is capable of spawning nearly infinite numbers of "simulated universes", then the probability th

• rendall 3y ago
  No. A computer is no more capable of simulating a Universe than is a book. The same arguments apply to books: If a super advanced race were capable of writing such vivid fiction that it created a Universe, then our Universe must be fictional!! It's an absurd idea that has gotten way too much traction.
  • FeepingCreature 3y ago
    The laws of physics are computable; why would a sufficiently large computer not be capable of simulating a universe?
    • rendall 3y ago
      You make an unwarranted logical leap, there. Some laws of physics are computable given sufficient simplifying constraints. It does not follow that a large enough computer therefore can simulate the Universe.
      • vidarh 3y ago
        You're making the assumption that our universe 1) is the universe, 2) is as computationally complex as the universe, 3) that all, or any, of our universe exists outside of simulated minds, or a simulated mind, 4) that time passes and that we exist as more than a single moment with memories of a non-existent past. In other words, we have no basis for saying our universe exists, that we have physical existence, that anyone but ourselves exist, or that we exists in time.
        • rendall 3y ago
          > In other words, we have no basis for saying our universe exists, that we have physical existence, that anyone but ourselves exist, or that we exists in time. Sure, I will grant that. This does not warrant a leap from we don't actually know what the Universe is to therefore definitely simulation.
          • vidarh 3y ago
            No, the more convincing argument for that is the prevalence of computation in the universe. Given the extreme prevalence of computation, in a universe large enough it'd be surprising if there weren't simulations. In an infinite universe, it'd be surprising if there weren't infinite simulations of universes just like ours. There only need to be two for it to be more likely we're in a simulation. There are lots of unknowns there we can't quantify very well, but unless the universe is firmly finite in both time and space, I find it increasingly difficult to see a way around simulation in some form or other. Especially because the threshold for us to find ourselves in an apparent simulated universe might well be the barest sliver of simulation: One mind, a single moment. Even assuming we one day try to run a large simulation, I'd expect we before then will have run huge number of simulations of minds for brief slivers of time to try to figure out if we get it right. It seems likely that if we're in a simulation, we're even more likely to be in a brief, constrained simulation rather than a full blown universe simulation. That of course doesn't mean we definitely are - like the Fermi paradox it's more question of "why don't we have a better answer?"
            • rendall 3y ago
              > In an infinite universe, it'd be surprising if there weren't infinite simulations of universes just like ours. I disagree. Physical laws hold throughout the Universe - or, that is the consensus null hypothesis anyway. In even an infinite Universe, assuming it is infinite, there are limits to that which is possible, and it is not yet demonstrated to my satisfaction that a computer could even theoretically simulate a Universe. That's leaving aside my fundamental objection that the space of what the Universe can possibly be is infinitely vast compared to the singular assertion that it's a simulation. In other words, that this is the correct view is exceedingly unlikely simply because it has been thought of. Imagine that I generate a random complex number of arbitrary precision and ask you to guess it. It could be `0.46451453499412721134961376996+5.275644069844024487293819737719i` for example. It's my view that you have a far, far higher chance of guessing that complex number than we humans do of coming up with a simple, correct cosmology. > the prevalence of computation in the universe I also disagree that it's certain that computation or even mathematics are universal or fundamental. I suspect that these both are based in a very human outlook and perspective. Their apparent universality is an illusion deriving from our inability to see outside of our human perspective. > In other words, we have no basis for saying our universe exists, that we have physical existence, that anyone but ourselves exist, or that we exists in time While true, I'm not sure what this has to do with the simulation hypothesis. Really, given this premise, the Universe could be anything at all.
    • breuleux 3y ago
      I suppose it could in theory, but it probably wouldn't do so very well. In general, you can't simulate physics on physics faster than physics, so non-approximate simulation of the universe would probably run several orders of magnitude slower than the universe does. You would have to approximate massively, but that means a lot of things that are physically possible in the universe would become impossible in the simulation, especially systems that require a lot of precision and optimal behavior such as computers. Honestly, even if you simplified everything to the max except for conscious agents in the simulation, it's not even clear to me that we could simulate human brains faster than actual human brains.
      • vidarh 3y ago
        > In general, you can't simulate physics on physics faster than physics You assume that the physics of the simulation are equivalent to the physics outside it. We simulate simpler environments than our own all the time. Maybe the constraints of our universe are the way they are because it reflects the tradeoffs required to be able to simulate it given the conditions the simulation runs in.
        • breuleux 3y ago
          Maybe, but that's not interesting. It is possible that the physics inside are different from the physics outside, but that tells us absolutely nothing of value about whether we are in a simulation or not. If we do assume that an observer cannot differentiate the simulation from the outside world, then we can make an interesting argument: if the rules of physics in some universe entails that this universe will simulate many other universes with the same apparent rules, then an observer of these rules is probably simulated regardless of what the root universe happens to be. This is the only way you can ground the probability calculation. A lot of things are possible. Not many things are probable.
          • vidarh 3y ago
            For an observer to be unable to differentiate the simulation from the outside world if put in the simulation is a very low bar, and the one that matters. It's a low bar because you don't need to presume the simulated entity gets the benefit of the passage of time. For it to be likely for us to be in a simulation, it's sufficient for it to be likely for the total runtime of "simulated us" to be higher than "real us", and our only knowledge of the passage of time are the momentary memories and sensory inputs right now, and we can't validate their truthfulness. In other words: you don't need to simulate any physics to prevent a mind from differentiating. You just need to limit the scope of your simulation to a sufficiently narrow slice of time. Personally, I tend to think that if simulations become widespread, test runs, debugging and development, research runs, or application specific runs of small slices are likely to far outpace full scale simulations in runtime, and so if simulations are probable, I'd be inclined to think we're most likely in a (very) short-lived, scope-limited simulation in a horrible groundhog day like setting.
  • dinkleberg 3y ago
    That seems to be making some bold assumptions about the power of future technologies. We have no idea what the future might hold. And we have no idea about the true reality of our existence. All of these conversations delve into the same uncertainties as faith. We’re trying to understand things we can’t truly ever understand or comprehend.
    • rendall 3y ago
      From your statement, I'm not sure which position you believe is the bold assumption. The null hypothesis in my view is The Universe is not whatever latest technology we humans have created like a simulation or a quantum computer or clock or steam locomotive. The extraordinary claim that requires extraordinary evidence for me would be Yes, the Universe is one of those. If you agree, then we agree.
  • esperent 3y ago
    False equivalence: books are static once printed. Computers use energy to perform calculations. They are not at all static, and fully capable of creating emergent behavior, where a book is not. A book can create emergent behavior in a mind that reads it (or a computer that processes it). But without those, it does nothing. A computer doesn't need to be observed to run. You can press a button, walk away for a few minutes, and come back to find an entirely novel image generated by Stable Diffusion, for example. Sure, all computers currently require an external person to push the button, perform maintenance, provide electricity, and so on. But that doesn't mean that all computers will always need this. Meanwhile, all books will always just be static words, because that's what books are.
    • rendall 3y ago
      Your list of how a computer is more like a Universe than a book has three or four items. Now enumerate all the traits that the Universe has that neither a book nor a computer has. Qualia, consciousness, time, gravity, electromagnetism, life, among infinite other differences. The list is literally infinite. The gulf between the Universe and a book is the same magnitude as that between the Universe and a computer. And sure, books are static once printed and need an observer to run, but that doesn't mean books will always need this.
      • esperent 3y ago
        > books are static once printed and need an observer to run, but that doesn't mean books will always need this. You've lost me here. Books don't run. A book is a large amount of organized text. That's the definition of a book. If you changed into into something that could also read the text, it would no longer be just a book.
        • rendall 3y ago
          > You've lost me here. That is disappointing.
  • earthboundkid 3y ago
    It also shows total ignorance of what we've learned about computing, namely that P vs NP and various Big O challenges mean it is not feasible to simulate some physical space without either cutting corners and not doing a complete simulation or using a computer in some sense "larger" (or slower) than the physical space.
    • wongarsu 3y ago
      What makes you confident that no corners were cut, that the simulation is complete, or that the world simulating us isn't larger or slower? Physical laws might be greatly simplified, anything you can't observe might not be simulated at all until necessary, the simulation might not be real-time, and the world running the simulation might have 6-dimensional spacetime (after all we love simulating 2d worlds).
      • vidarh 3y ago
        Indeed, one of the reasons for speculating about this is that looking at physics through the lense of "does this make sense as an implementation artefact" is fairly interesting. E.g. a system might apply a computational "budget" per entity per time step in terms of "in universe operations", in which case time dilation could naturally fall out (more time spent simulating motion translating into less time available to simulate local subjective time) That doesn't prove that is how our universe works, but it's fascinating all the same.
      • rendall 3y ago
        Why would you apply the word "simulation" to the activities of 6th-dimensional (or 67th-dimensional or googolplexth-dimensional) entities? Assuming you could even apply human concepts to them like intention, consciousness, or research, why would these proposed creatures be "simulating". Why couldn't the Universe just be some by-product of some kind of industrial process? Or something else? At what remove do you start to say "yeah that's too weird to be called a simulation"?
        • wongarsu 3y ago
  • wongarsu 3y ago
    Conveniently, you don't need to simulate the entire universe, just a single human's experience of it. That cuts computing costs tremendously. If a tree falls in the forest and nobody is around to observe it, do you need to simulate it down to the quantum level? Or do you just do coarse-grained simulation, with fine-grained steps reserved to where it causes observable differences? If later somebody comes around to observe the fallen tree in too much detail you can always just simulate that part in more detail, and hide the difference behind what we call "inherent randomness at the quantum level".
    • rendall 3y ago
      Ok, but then why is a computer needed at all? Put a brain in a vat and stimulate it with chemicals and electricity to hallucinate that it is in a consistent, coherent Universe.
      • wongarsu 3y ago
        Sure, you could do that. But that sounds mostly useful for psychology or brain research. The number of institutions that would even consider doing that is dwarfed by the number of simcity players. In a theoretical future where simulating a world in sufficient detail is viable on a smallish hardware budget, you are much more likely to be in a simulation than in a research lab.
      • vidarh 3y ago
        So, a computer.
    • breuleux 3y ago
      I think this is a much harder problem than you make it seem. A tree no one is looking at, sure, you can take shortcuts, but if I'm not looking at my computer, it still has to run my programs and you cannot approximate its answers. If I, a being in your simulation, was to hypothetically build a simulator of the kind that you use to simulate me, it is obvious that it could not work: if it could approximate the running of itself to a sufficient level of detail, it already would be doing that. So the question is: what else wouldn't work? The closer the technology I build gets to physical optimality, the more it will act as a bottleneck in the simulation. If I build a physically optimal circuit to perform any useful calculation that I can verify, for example, the simulation speed will have to drop below one second per second. What this means is that modern times are probably too expensive to simulate, so you would likely stick to simulating medieval times (we may also have to eschew simulating the brains themselves, if it turns out the biological ones are too close to optimality for what they do). At least that's what we would have to do. You can imagine that the universe that simulates us works differently, but hypothesizing a world that has different laws of physics doesn't really help us to understand ours. It's fun to think about, but nothing more than that.
  • trey-jones 3y ago
    The problem is about probability not capability.
• esperent 3y ago
  This is kind of like the Boltzmann Brain idea. https://en.m.wikipedia.org/wiki/Boltzmann_brain https://en.m.wikipedia.org/wiki/Boltzmann_brain