//Desmond knowing he's jumping creates alternate time lines which = alternate universes. In the episode when Des went back in time it was pretty clearly shown that no matter how much he tries to change the future, the universe works around him to make stuff happen anyway. eg He saved Charlie lots of times but in the end Charlie died. So no matter what Des does in the past, it doesn't change that he ends up on the island. And no matter what happens next on lost, no amount of time travel is going to prevent Jack from growning a...