"It surely isn't necessary that we are similar to a host universe, but I wouldn't you say it was a necessary part of this theory?" I don't think it's a necessa

"It surely isn't necessary that we are similar to a host universe, but I wouldn't you say it was a necessary part of this theory?" I don't think it's a necessary part of the theory, but it's a necessary part of the test we would need to conduct. And given that such a test is simply testing for inconsistencies, artifacts and bugs inherent to our own universe/simulation, it's possible to detect whether we're in a simulation without having to test for the precise nature of it (or the nature of the simulators). But our tests are inherently being conducted from our own frame of reference, with our own understanding of what should and shouldn't be found. Ergo, we can prove a simulation by finding artifacts of one as recognizable to us, but we can't necessarily disprove a simulation by not finding artifacts. That being said, the proper way to think about the test wouldn't be "Physicists are testing to determine if we're in a simulation." It would be "Physicists are testing to find evidence that we're in a simulation."