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Yes, but a simulated universe would have bounds much lower than that. E.g. the laws of physics say that building a computer of size X is possible. But whenever

Yes, but a simulated universe would have bounds much lower than that. E.g. the laws of physics say that building a computer of size X is possible. But whenever we try to build it, it should mysteriously fail. Because the laws of physics aren't actually being simulated, any more than a video game simulates every particle and photon of light. It's just an approximation, and the computing power isn't there to actually simulate a computer that big.

dragonwriter 10y ago
> Yes, but a simulated universe would have bounds much lower than that. No, it wouldn't. A simulated universe would have exactly the limits of the laws of the simulation, which would be exactly the physical laws of the universe as seen from within. > Because the laws of physics aren't actually being simulated, any more than a video game simulates every particle and photon of light. It's just an approximation The approximation (of some idealized laws of physics conceived in the external realiy) being simulated would be exactly the laws of physics observed in the internal reality of the simulation.
- Houshalter 10y ago
  No, the simulation would not be able to fully simulate physics! It would need to cheat, a lot. A lot of sections would be unsimulated. When you observe the result of a physics experiment, the result would be made up on demand by some caretaker AI. Not by actually simulating physics.
  - dragonwriter 10y ago
    > No, the simulation would not be able to fully simulate physics! Yes, whatever the simulation simulated would be the physics observed within the simulated universe. They may not fully match some idealized physics (perhaps those of the external universe, perhaps some alternative designed for the purpose of the simulation) for which the code of the simulation is an approximation, but from the inside of the simulation the rules by which the simulation determined outcome would be exactly the empirically-discoverable laws of physics of the simulated universe. The only way to observe a discrepancy is to escape the simulation, find out what the creators were intending to approximate, and then compare it to the results of the simulation, but you can't do that from within the simulation.
    - Houshalter 10y ago
      The point is that the physics would be heavily approximated in obvious ways. E.g. you would observe artifacts of 3d rendering, which we shouldn't expect to observe at all. However a sufficiently clever simulator could cover that up a bit. By say altering the results of physics experiments that would detect that. However there is a limit to how far they could go. We couldn't have computers too big, or it would break the simulation. So at some point they would have to intervene and prevent us from building them, or just reset the simulation. Either way, you can't have "turtles all the way down". Each nested simulation would only have a tiny, tiny, fraction of a percent of the computing power required for the parent simulation. After just a few levels it would inevitably reach 0.
      - dragonwriter 10y ago
        > The point is that the physics would be heavily approximated in obvious ways. Whether they would or not depends on the complexity of the computer and software running the simulation, the limits to which are set by the laws of physics of the "real" universe in which the simulator exists (which may not be those of the simulation). Our intuition of what is practical in a simulation based on our own technology and what is practical in our universe simply don't apply. > E.g. you would observe artifacts of 3d rendering, which we shouldn't expect to observe at all. Our universe has a lot of quantization artifacts which defy intuition based on assumptions about continuity of physical quantities. Once we systematically observed and cataloged them, we incorporated models of them into our understanding of physical laws. Whether those are "real" physical laws in a non-simulated universe, intended simulated physical laws of a simulated universe, or simulation artifacts representing limitations of the simulation in a simulated universe are impossible to distinguish from within our universe. > However there is a limit to how far they could go. We couldn't have computers too big, or it would break the simulation. If the simulation is sufficient to model a universe the size of our observable universe at the detail level our universe is observable too, the maximum scale of computer we can have without breaking the simulation is a quantum computer of the complexity of our physical universe. Anything up to that scale is within the capacity of the simulation. Basically, all of the assumed limitations you propose are undetectable from within. You may be making the additional assumption that not only is there a host universe, but that the host universe has a scale and physical laws basically identical to those that we observe in our universe, such that the simulation would need to be substantially less complex. But there is no reason that either the scale or general physical laws of the host universe would have to mirror those in the simulation. > Either way, you can't have "turtles all the way down". If you assume the host universe is infinite in scope and information content (and the assumption that it is infinite in time and that all of that time is available to civilizations, which seems to underlie the conclusions on the that our universe is likely to be a simulation, implies this), then no matter how small of a fraction of its capacity one thinks a simulation can have, it can support an unbounded number of layers of simulation underneath it. If you assume a finite root universe, then (even leaving aside other reasoning flaws in the argument), the conclusion that our universe is likely to be a simulation falls apart rapidly.
  - unprepare 10y ago
    it appears you are insisting that regardless of a simluation existing the laws of physics must be the same for those inside and outside the simulation. that doesnt make any sense to me. If i create a simluation in my computer of a world without gravity, to the inhabitants of that simulation, gravity does not and never has existed. similarly - what we understand to be the laws of physics could have been laws that were designed for our simulation but have no bearing on the laws that govern the world in which the computer simulating us exists.
    - Houshalter 10y ago
      But that's not the simulation argument. That's not related to what Elon Musk is saying at all. The simulation argument is about simulations of our own universe, within our own universe. It's a very specific claim about the parent universe, and the nature of our simulation. As opposed to more general simulations, which can't make any predictions at all and tell us nothing.
      - dragonwriter 10y ago
        > The simulation argument is about simulations of our own universe, within our own universe. The original simulation argument paper is about simulations intended to simulate the historical predecessors of the simulations creators in their own universe, but, even so, any anomalies from the approximation of the physical laws of the root universe used in the simulated universe would only be detectable by reference to the root universe, from the perspective of those within the simulation, the behavior of the simulation would be the physical laws of the universe they live in. (This is equally true in the more general case where the intent of those creating the simulation is not specifically to do an "ancestor simulation" in a universe approximating the physical laws of their own universe, but restricting to the scenario envisioned in the original paper doesn't change it at all.)
        Houshalter 10y ago
        >the behavior of the simulation would be the physical laws of the universe they live in. That's just a tautology. Yes the code of the simulation are the laws of physics for the beings living in the simulation. But the point of a historical simulation is to simulate your own universe. Not a completely different universe. We should expect simulated Earth to be exactly identical to real Earth. Or at least you shouldn't be able to tell the difference. So we should expect the laws of physics to appear the same, but things that require lots of computing power should fail. We shouldn't be able to simulate universes within our own simulation. That would be a pointless waste of computing power.

dragonwriter 10y ago

> Yes, but a simulated universe would have bounds much lower than that. No, it wouldn't. A simulated universe would have exactly the limits of the laws of the simulation, which would be exactly the physical laws of the universe as seen from within. > Because the laws of physics aren't actually being simulated, any more than a video game simulates every particle and photon of light. It's just an approximation The approximation (of some idealized laws of physics conceived in the external realiy) being simulated would be exactly the laws of physics observed in the internal reality of the simulation.

Houshalter 10y ago
No, the simulation would not be able to fully simulate physics! It would need to cheat, a lot. A lot of sections would be unsimulated. When you observe the result of a physics experiment, the result would be made up on demand by some caretaker AI. Not by actually simulating physics.
- dragonwriter 10y ago
  > No, the simulation would not be able to fully simulate physics! Yes, whatever the simulation simulated would be the physics observed within the simulated universe. They may not fully match some idealized physics (perhaps those of the external universe, perhaps some alternative designed for the purpose of the simulation) for which the code of the simulation is an approximation, but from the inside of the simulation the rules by which the simulation determined outcome would be exactly the empirically-discoverable laws of physics of the simulated universe. The only way to observe a discrepancy is to escape the simulation, find out what the creators were intending to approximate, and then compare it to the results of the simulation, but you can't do that from within the simulation.
  - Houshalter 10y ago
    The point is that the physics would be heavily approximated in obvious ways. E.g. you would observe artifacts of 3d rendering, which we shouldn't expect to observe at all. However a sufficiently clever simulator could cover that up a bit. By say altering the results of physics experiments that would detect that. However there is a limit to how far they could go. We couldn't have computers too big, or it would break the simulation. So at some point they would have to intervene and prevent us from building them, or just reset the simulation. Either way, you can't have "turtles all the way down". Each nested simulation would only have a tiny, tiny, fraction of a percent of the computing power required for the parent simulation. After just a few levels it would inevitably reach 0.
    - dragonwriter 10y ago
      > The point is that the physics would be heavily approximated in obvious ways. Whether they would or not depends on the complexity of the computer and software running the simulation, the limits to which are set by the laws of physics of the "real" universe in which the simulator exists (which may not be those of the simulation). Our intuition of what is practical in a simulation based on our own technology and what is practical in our universe simply don't apply. > E.g. you would observe artifacts of 3d rendering, which we shouldn't expect to observe at all. Our universe has a lot of quantization artifacts which defy intuition based on assumptions about continuity of physical quantities. Once we systematically observed and cataloged them, we incorporated models of them into our understanding of physical laws. Whether those are "real" physical laws in a non-simulated universe, intended simulated physical laws of a simulated universe, or simulation artifacts representing limitations of the simulation in a simulated universe are impossible to distinguish from within our universe. > However there is a limit to how far they could go. We couldn't have computers too big, or it would break the simulation. If the simulation is sufficient to model a universe the size of our observable universe at the detail level our universe is observable too, the maximum scale of computer we can have without breaking the simulation is a quantum computer of the complexity of our physical universe. Anything up to that scale is within the capacity of the simulation. Basically, all of the assumed limitations you propose are undetectable from within. You may be making the additional assumption that not only is there a host universe, but that the host universe has a scale and physical laws basically identical to those that we observe in our universe, such that the simulation would need to be substantially less complex. But there is no reason that either the scale or general physical laws of the host universe would have to mirror those in the simulation. > Either way, you can't have "turtles all the way down". If you assume the host universe is infinite in scope and information content (and the assumption that it is infinite in time and that all of that time is available to civilizations, which seems to underlie the conclusions on the that our universe is likely to be a simulation, implies this), then no matter how small of a fraction of its capacity one thinks a simulation can have, it can support an unbounded number of layers of simulation underneath it. If you assume a finite root universe, then (even leaving aside other reasoning flaws in the argument), the conclusion that our universe is likely to be a simulation falls apart rapidly.
- unprepare 10y ago
  it appears you are insisting that regardless of a simluation existing the laws of physics must be the same for those inside and outside the simulation. that doesnt make any sense to me. If i create a simluation in my computer of a world without gravity, to the inhabitants of that simulation, gravity does not and never has existed. similarly - what we understand to be the laws of physics could have been laws that were designed for our simulation but have no bearing on the laws that govern the world in which the computer simulating us exists.
  - Houshalter 10y ago
    But that's not the simulation argument. That's not related to what Elon Musk is saying at all. The simulation argument is about simulations of our own universe, within our own universe. It's a very specific claim about the parent universe, and the nature of our simulation. As opposed to more general simulations, which can't make any predictions at all and tell us nothing.
    - dragonwriter 10y ago
      > The simulation argument is about simulations of our own universe, within our own universe. The original simulation argument paper is about simulations intended to simulate the historical predecessors of the simulations creators in their own universe, but, even so, any anomalies from the approximation of the physical laws of the root universe used in the simulated universe would only be detectable by reference to the root universe, from the perspective of those within the simulation, the behavior of the simulation would be the physical laws of the universe they live in. (This is equally true in the more general case where the intent of those creating the simulation is not specifically to do an "ancestor simulation" in a universe approximating the physical laws of their own universe, but restricting to the scenario envisioned in the original paper doesn't change it at all.)
      - Houshalter 10y ago
        >the behavior of the simulation would be the physical laws of the universe they live in. That's just a tautology. Yes the code of the simulation are the laws of physics for the beings living in the simulation. But the point of a historical simulation is to simulate your own universe. Not a completely different universe. We should expect simulated Earth to be exactly identical to real Earth. Or at least you shouldn't be able to tell the difference. So we should expect the laws of physics to appear the same, but things that require lots of computing power should fail. We shouldn't be able to simulate universes within our own simulation. That would be a pointless waste of computing power.