If there are multiverses that are in fact coupled — quantum bundles of universes, that sort of thing (which is the basis of my story, it being a bit boring to write about a world where the Lord of the Rings Universe really exists as a parallel Universe, only you can't get there from here or ever prove it — then perhaps we might
one day be able to demonstrate this, but in the meantime the question is more science fiction or fantasy
than something to believe or disbelieve in very
strongly, with the usual rational default: Lack of belief pending
positive evidence!