Ctrl+F Hitler, ah, there it is. I feel like the xkcd comic missed an opportunity to have a 1932-1945 segment in there about the biggest cause of death for time travelers being OTHER time travelers killing them before they can successfully go back in time and kill Hitler, lol.

Re: conservation of reality, I feel like if I went back and shot Hitler, I would miss, or be stopped by security, or bad weather, or even if I managed to actually do it, he’d be replaced by a look alike, and then it would turn out the guy we always thought was Hitler was actually just an actor, or something. Whatever happened happened and can’t be undone, not through magic resuscitation of a corpse, but through smooth and natural intervention of reality itself, if that makes sense…