The question I always end up with - how many simulations deep are we? Universe A builds a simulator to see how it works, it then builds a simulator and so on. We can never communicate with the original universe, so we build our own simulation.
As always if simulating universes is possible then the probability we're in level 0 tends to 0.
The could be no original universe. Just consider infinite sequence of simulations. Or universe A can be simulating universe B which is in turn simulates A. This is not possible with finite systems, but the moment one considers infinite ones, all bets are off.
"Eventually in the progress of a technologically advanced society, occasionally after some sort of limited access to hyperspace, more usually after theoretical work, it was realized that the soap bubble was not alone. The expanding universe lay inside a larger one, which in turn was entirely enclosed by a bubble of space-time with a still greater diameter. The same applied within the universe you happened to find yourself on/in; there were smaller, younger universes inside it, nested within like layers of paper round a much-wrapped spherical present."
"In the very centre of all the concentric, inflating universes lay the place they had each originated from, where every now and again a cosmic fireball blinked into existence, detonating once more to produce another universe, its successive outpourings of creation like the explosions of some vast combustion engine, and the universes its pulsing exhaust."
"There was more; complications in seven dimensions and beyond that involved a giant torus on which the 3-D universe could be described as a circle, contained and containing other nested tori, with further implications of whole populations of such meta-Realities… but the implications of multiple, concentric, sequential universes was generally considered enough to be going on with for the moment."
As always if simulating universes is possible then the probability we're in level 0 tends to 0.