How, without information on the "real" world, could you make a determination as to the fidelity of the simulation? Heck, a simulation doesn't even have to attem

How, without information on the "real" world, could you make a determination as to the fidelity of the simulation? Heck, a simulation doesn't even have to attempt to have the same natural laws as its host reality. If you're on an emulated x86, and you know a lot about x86 architecture, you may detect that you're on an emulator. But if all you get is information on the one single instance you're running on right now, no references, no documentation, no comparison with bare metal... at that point what's the difference?