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The universe represents itself, but no part of the universe is able to predicts its own future in detail, and is as such no simulation, at least not of itself.

The universe represents itself, but no part of the universe is able to predicts its own future in detail, and is as such no simulation, at least not of itself. It just exists. The reason I said "a Newtonian universe", is precisely because quantum physics represents a discretization, which Newtonian physics does not, and the Planck length is a part of this discretization. The simulator would have to be bigger than the system it simulates to be able to represent its state, but the Cantor diagonalization argument would no longer apply.

harshreality 12y ago
But we don't live in a Newtonian universe, do we? If the universe requires infinite computation to "go", it's doing that computation somehow, isn't it? If the universe at perceivable scale is not capable of infinite computation, but infinite computation is required, perhaps it's spawning infinite universes that do computations instantly with respect to our universe's arrow of time? I don't understand the difference in computational requirements between predicting (in "advance") a future (entropic future) state of the universe, and predicting it JIT. A functioning Newtonian universe must be capable of infinite computation, therefore Laplace's demon can exist (for that universe), even if only by being a copy of the universe, right?
- seabee 12y ago
  There are two outcomes of your argument: 1) a functioning Newtonian universe is impossible 2) functioning Newtonian universes are infinitely complex The laws of physics already established 1, making 2 a moot point.
  - deleted 12y ago
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- d--b 12y ago
  That's exactly the point of the metaphysical problem. And you could rephrase as: if we could make an exact replica of the universe, would it behave just as ours or would it diverge away? Laplace says it would behave just as ours, but it's not obvious. It's not a question about chaos or the computability of the universe, it's a question about whether true randomness exists in the laws of nature.

harshreality 12y ago

But we don't live in a Newtonian universe, do we? If the universe requires infinite computation to "go", it's doing that computation somehow, isn't it? If the universe at perceivable scale is not capable of infinite computation, but infinite computation is required, perhaps it's spawning infinite universes that do computations instantly with respect to our universe's arrow of time? I don't understand the difference in computational requirements between predicting (in "advance") a future (entropic future) state of the universe, and predicting it JIT. A functioning Newtonian universe must be capable of infinite computation, therefore Laplace's demon can exist (for that universe), even if only by being a copy of the universe, right?

seabee 12y ago
There are two outcomes of your argument: 1) a functioning Newtonian universe is impossible 2) functioning Newtonian universes are infinitely complex The laws of physics already established 1, making 2 a moot point.
- deleted 12y ago
  [deleted]
d--b 12y ago
That's exactly the point of the metaphysical problem. And you could rephrase as: if we could make an exact replica of the universe, would it behave just as ours or would it diverge away? Laplace says it would behave just as ours, but it's not obvious. It's not a question about chaos or the computability of the universe, it's a question about whether true randomness exists in the laws of nature.