> 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

> 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? At this point it's all theoretical based on our best mathematical modeling of the universe/physics. > 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 By definition? No. Extremely difficult and maybe impossible. Yes. Keep in mind that before powerful telescopes, the outer planets were "guessed" at by mathematical modeling. Astronomers mathematical calculations led them to believe that there should be planetary bodies like uranus and neptune out there. It took further advances in technology/physics to corroborate the mathematical calculations/model. The same thing for hereditary genetics and the proton/electron/etc. When the first theoretical/mathematical models were first made, we had no conceivable way of "seeing" a proton or DNA.