But how can you decide what's going to have an influence and what will be without effect if you don't simulate everything? If tomorrow we receive a transmissio

But how can you decide what's going to have an influence and what will be without effect if you don't simulate everything? If tomorrow we receive a transmission from a form of life that lived thousands of years ago thousands of light years away from us it's going to change a lot of things. You can't ignore that. You can only simulate a small part of the universe if you can simulate correctly what happens at the boundaries of the region. Otherwise it "contaminates" the simulation inwards at the speed of light. if you want to simulate what will happen on earth for the next year you at least need to know the full state of the universe in a sphere one light year in radius, or at least that's my understanding. I think these concepts somewhat overlap with the "Holographic principle" although I might be mistaken, I'm way out of my depth: https://en.wikipedia.org/wiki/Holographic_principle https://en.wikipedia.org/wiki/Holographic_principle