[prng2021]

"The argument assumes that given one state of human existence, it is possible to calculate a distinct next state. And then a state after that. That is, if we had a powerful enough computer to store the state of every single atom, and calculate their interactions, we could play through time in that existence."

Why are you assuming this to be true? Due to the Heisenberg Uncertainty Principle, it's impossible to perfectly know "one state of human existence". So the rest of the thought experiment seems moot.

[nntwozz]

It's also naive to think that everything can be calculated by a computer, at some point the calculations become so enormous that the energy requirement approaches infinity.

[Karellen]

> at some point the calculations become so enormous that the energy requirement approaches infinity.

No, they really don't. You might say that the energy requirement approaches Graham's Number, or TREE(3), and maybe that's somewhat plausible, but Graham's Number and TREE(3) are both minisculely insignificant compared to infinity. If you ever counted that high, you'd be no closer to reaching infinity than you were when you started.

But who says that Graham's Number or TREE(3) are large numbers in the universe doing the simulating? Why would the simulating universe be as incomprehensibly tiny and simple as ours is?

Oh sure, our universe looks big to us. But who are we to judge its size?

[iahwrites]

Is it moot though? The uncertainty principle makes it impossible for us to _measure_ both speed and position, but if you're simulating it that's not necessary.