Science can never prove that it has reached the bottom, but it could hypothetically yield a model that makes predictions that always match the universe to withi

Science can never prove that it has reached the bottom, but it could hypothetically yield a model that makes predictions that always match the universe to within all relevant margins of error. It could be that that model is itself a simulation or that there are yet deeper layers we just can't see, whatever, you know, all that jazz. But if there was a complete model, with no internal contradictions, that matched everything we could see, then at least when someone said "in light of this theory, gravity is X", we would be making a coherent statement. Right now we can't say what gravity is. We know we don't have a complete description of it, because the contradictions between QM and relativity are something explainable to a motivated high school student, as they are pretty fundamental. You don't need to deeply understand either theory to understand enough of the conflict to know we don't have an answer. This isn't a criticism of either theory per se or the scientists involved. They're the best we've got and they're each on their own pretty good. But we are as justified in saying "gravity is definitely a curvature of spacetime because Relativity says so" as we are justified in saying "gravity doesn't exist because it doesn't appear in the standard model at all". Both are basically the same statement relative to the theory they relate to, it is just more obvious the latter is wrong.