> I certainly do not assume that they're inside our universe at the time! I'm not sure what you mean by that, but if the simulating universe is not qualitative

> I certainly do not assume that they're inside our universe at the time! I'm not sure what you mean by that, but if the simulating universe is not qualitatively identical to the simulated universe, you lose the mathematical properties that make the simulation argument interesting. > it may work if you assume that most of the universe at the moment is computationally "dead" and can be optimized out. Our universe is chaotic and is largely defined by its edge cases sometimes leading to a global phase change (e.g. evolution). If one wishes to preserve these properties, I would argue it is not optimizable at all. If you are willing to lose these edge cases, maybe you can optimize certain things away, but it's quite possible you will lose more than you bargain for (basically nothing is computationally inert in a chaotic system). Your system will be bottlenecked by the most demanding parts of the simulation anyway. > But IMO, this sort of theory makes a lot more sense in a "large" cosmology like Tegmark IV. I tried to work it out mathematically a while ago, but I don't think it really works out (I forget the details, I should dig it up sometime). If the infinity of possible mathematical structures actually exist, there's still an infinity of possible mathematical structures to simulate. And if, to simplify, 1% of mathematical structures are conformant with our universe, by default you would expect 1% of simulations (across the multiverse) to be simulations of our universe (unless you think we are somehow special and other universes specifically want to simulate us). So you would need over 50% of the multiverse to be simulation fodder in order for a given observer to probably be in a simulation, and that seems... kinda really high?