Something doesn’t click here. You claim “that we live in an unbelievably computationally expensive universe, and we really don’t need to. We could easily be supplied with a far, far grainier simulation and never know the difference”; but how do we know that we do live in a computationally expensive universe if we can’t recognize the difference between this and a less computationally expensive universe? Almost by definition anything we can measure (or perhaps more accurately have measured) is a necessary component of the simulation.
Something doesn’t click here. You claim “that we live in an unbelievably computationally expensive universe, and we really don’t need to. We could easily be supplied with a far, far grainier simulation and never know the difference”; but how do we know that we do live in a computationally expensive universe if we can’t recognize the difference between this and a less computationally expensive universe? Almost by definition anything we can measure (or perhaps more accurately have measured) is a necessary component of the simulation.