Two weeks before death, Hawking submitted a paper on parallel universes
Something I've never understood and would greatly appreciate understanding: could someone ELI"5" how the concept of "parallel universes" will not always be a metaphysical instead of a scientific question?If there are truly separate "universes", then by definition wouldn't it be the case that there would be no way to test (or falsify) whether they exist or not, so would the question of their existence not be in the realm of philosophy and metaphysics rather than the sciences? What am I missing (I assume it has to do with my understanding of the word "universe")?