with enough computing power you can simulate any experiment. (Just simulate the entire universe, run it back, simulate it a different way

I may be losing the thread here, but (1) for a universe to simulate itself requires actually unlimited computing power, not just nigh-unlimited, and (2) infinities aside, to simulate a physics experiment requires knowing the true laws of physics in order to build the simulation in the first place, unless you search for yourself in the space of all programs or something like that, and then you still potentially need experiment to resolve your indexical uncertainty.