Well, that proves it. Given our present state of knowledge his assurances about what must be the case seem pretty convincing. Of course that has been the situation before and, gosh, new things were discovered, by scientists, by the way, that opened new doors to new phenomena or explanations of what seemed like impossible phenomena. I'll keep a running duh on this one. If his theories had not been about something most scientists are very skeptical about, they would take his assumption that he had proved it was impossible with a large grain of salt. Given what we know now, it looks pretty solid. But that should not be confused with what we may realize later is possible.