So you invent a time machine, and what’s the first thing you do? You go back in time and kill Hitler, of course! Except you can’t (TVTropes), because either it doesn’t work or it screws up the timeline even more. Thus resolving one of the burning questions surrounding time travel: if it’s possible, why do we still have Hitler? Stephen Fry tackles this in a best-of-all-possible worlds way in Making History, where his protagonist…