> [...] but it presupposes that there is a theory of everything that can be used to perfectly simulate the universe, [...]

LLMs are nice here: we don't need a theory of everything to simulate them. You can indeed use pebbles on the beach.

Scott Aaronson said that in theory a finite look-up table can win eg a ten minute Turing test (any finite length is fine). Of course, to borrow his argument further, the naive table would be galactic in size. So the real magic is in being able to compress the responses of that table into something human sized / LLM-server sized.