I don't really get how they "change" the past in the show. I mean, when they try to change something big the result is that Okabe changes timeline and nothing else, so it doesn't differ for anyone else. for an example when Ruka wanted to change gender, the one that wanted to change still remains after Okabe changing timeline right? because if so, then it doesn't change anything just creat a new timeline were Okabe will live, the Ruka who wanted to become a girl still remains as a boy. Hope someone can explain Psy el Congooro.