I've heard that unlike Special Relativity, General Relativity claims that you can' say any reference frame is better than another frame, including frames in which Newton's Laws don't hold. I've seen debates about this specifically in the context of geo/helio-centrism. From what I understand, neither is more true than the other in the context of GR, but heliocentrism is still preferred due to its simplicity. What I want to know is: Does GR claim that there is no universal inertial frame, or that there's no way of telling if there is? Meaning, if the latter is true, then maybe one exists but we have no way of telling. This is probably a silly question, since I really don't know much about GR (I've learned SR though), so please correct me if I'm thinking about this incorrectly.