There's a short entry in the first pages of a book, the title and author of which I can't remember but whose concept is awesome enough for me to want to find it again. The short version is, "This story is a work of fiction. It did not really happen. However, for those within the story itself, the fiction is real. In this way, perhaps all works of fiction are also real. Thus, all worlds exist, even if the only evidence of their existence in ours is fiction."