"Couldn’t a quantum computer simulate a Universe that appears (to any simulated observers within) to be impossible to be simulated on a quantum computer?" Give

"Couldn’t a quantum computer simulate a Universe that appears (to any simulated observers within) to be impossible to be simulated on a quantum computer?" Given the Church-Turing thesis, what would that look like, though? How would we even identify it? We ask "hey, universe, what's 2 + 3" and it says "C'thulu"? Even the quantumness of the simulation is an efficiency argument, not a possibility argument. A classical computer can simulate our quantum universe, it just has even worse resource requirements that simulating the universe seems to. But there would be no experiment you could run from within that would show you're running on a classical computer or a quantum one. You might be able to create experiments that consume yet vaster amounts of computation time, but you couldn't tell from the inside. And it's not as if I can just stroll down to my kitchen and perform an experiment that will go one way if the universe is computing to a 10^-20 accuracy, and another if it's using 10^-23 accuracy. Most of your personal experience could be simulated with a classical approach with ad-hoc minor quantum fixups here and there.