Is the universe a computer simulation? This question first arose as a thought experiment by Nick Bostrom in 2003. The argument is that if a computer simulation of reality is possible, then increases in computational power mean that a universe will contain far more simulations of beings than real beings. So it would be overwhelmingly likely that any particular consciousness is a simulation.
Recently, researcher’s propose that that current understandings of physics make any simulation of reality impossible.
See Consequences of Undecidability in Physics on the Theory of Everything
I think this misses the point entirely. There is no need to simulate everything, and Nick Bostrom never called for it. It is only necessary to simulate you and your sensory inputs. This is nearly within reach already.
So imagine some process that cannot be simulated within the rules of physics. That is fine, but who cares? All you need to do is to simulate the sensor data that would result from any experiment or measurement on the process.
That is much easier than you think, because there is no need for the simulation to be limited by the notional speed of light or even by causality. The simulation can easily backtrack and correct any earlier “results” that are made impossible by any future developments. The simulation does not need to run in real time, or indeed in sequence. It only needs to be ex post facto consistent.
It might take more compute cycles to provide sensory data to a quantum physicist than to, say, me, but that is fine. The physicist will run slower.
Any discussion of the Simulation Hypothesis is incomplete without a link to XKCD