[tehwalrus]

Energy, though.

I mean, the host universe may have completely different laws of nature, but assuming that the 2nd law exists in it...

Organising information (storing it in RAM, carving it on a rock...) decreases entropy and thus takes work (entropy overall increases, because you had to get the energy to do your work by increasing entropy somewhere else by more.)

The cost of accurately simulating an entire universe, down to atoms, would be extreme, like you'd need galaxys worth of stars' to even begin.

At which point, the question becomes, why not just observe the real universe?

[delinka]

You assume that our [observable, hypothesized] universe isn't a pittance of matter and energy in a larger universe. Suppose your Conway's Game of Life simulation gained what it considered sentience, and with this sentience contemplated whether this world it inhabits was the universe or a simulation. Now suppose that it deduced that it would take universes of energy to simulate its own universe. Well, it'd be right.

That doesn't mean it's not.

[tehwalrus]

Indeed, if the D&D universe is the real one, we may all be in some elven wizard's toy universe, with "simple" rules and no magic, where she goes to meditate... I did try to caveat in my original answer.

[doktrin]

> At which point, the question becomes, why not just observe the real universe?

I don't think the 'why' is the right question to ponder. It's really a matter of 'if'.

We lack the context to adequately answer 'why' one might decide to create a simulation of a universe. Any(one/thing) capable of putting such a simulation together is about as different from us as we are from bacteria. Therefore, considering motivation is a bit of a dead end.

The 'if' is a question we can at least theorize about. Is a simulated universe possible? If we accept that it is, then we also accept that we are most likely currently in one.

[tehwalrus]

> Is a simulated universe possible? If we accept that it is, then we also accept that we are most likely currently in one.

I'm sorry, I never was one for philosophy. How does that follow?

[doktrin]

The reasoning is essentially that if it's possible, then it's been done. If it's been done, then the odds that we are in the original universe become extremely low and the chance we are in one of the turtles-all-the-way-down simulations conversely high.