Yes, but I think we need to be clear here on what we mean by theory, and what information we're taking as a given. The proposition, "steel bars in this lab fal

Yes, but I think we need to be clear here on what we mean by theory, and what information we're taking as a given. The proposition, "steel bars in this lab fall to the earth" being /false/ doesn't impact essentially any theory of physics if there are magnets in the lab. If you exclude every possible alternative, leaving gravity, then the proposition being false invalidates basically all of physics. Including the fundamental assumption that the laws of the universe are universal. So the question is what theories *require* a proposition to be true, in that, they logically entail it. When this is made clear it should be obvious that "maybe the maximum speed of the universe is different" is very very different to the claim, "maybe mars is habitable". Many lay people, entirely ignorant of the best theories we have, do not understand that the former requires extraordinary levels of evidence to take seriously; while the latter requires almost none. This type of "unknown unknown" argument often fails to make this distinction for the sake of making some fantasy as plausible as some possible reality.