In order to get around the time travelling paradox, you know the one where you travel back in time and kill yourself, and then you don’t exists any more and therefor can’t travel back in time and kill yourself. Leaving the younger you alive and growing up to become the one that travels back in time and kills yourself… Well I think I have came up with a solution to this. It’s so brilliantly simple I actually believe some one else all ready has thought of it: you can change the future of the past, but you can’t change the history of the present. What this means is you can go back in time and kill yourself, but you won’t, like, disappear, or something. What will happen is that the younger you will be dead, and you won’t be in that timestreams future. But you will be in your own timestreams history. What has happened in your history, has happened, since you can’t step out of your own timstream.
Say for instances if you go back in time and kills Hitler. Come on, admit it, it’d be the first thing you’d do if you’d get chance. Well maybe after you go back and had a magic night of dirty sex with that high school beauty you never dared to date, or after you went back and planted the winning lotto numbers on your own desk, or… Well after you made all those things you go back in time and kills Hitler. So there now, he is dead, the second world war wont happen, the concentration camps are just whiped of existance, and the world takes a whole new turn. I wont go into what might be the outcome, what could happen to the middle east without Isreal, what could happen to the development of nuclear power without the A-bomb science, let’s just say you stay in that timestream and the world takes what ever turns it do without Hitler. Everyone knows Hitler got killed, or deosn’t even know who he was depending on when you do kill him. Nothing strange, really, just another world. If you, on the other hand, where to go back, or front, or… I all ways get stuck on what to call it when a time traveller from the future returns to his own time. Any way, when you return to your own time, nothing has changed; Hitler where still living, the WWII is a historical fact, all those people where killed, and everything else has developed just as you remember it from history class.
You could look at these two different timestreams as alternative universes. Which is another, not very original, idea I have: when you travel in time, what you really do is you travel into a alternative universe. The trick isn’t so much to travel in time, but to hit the right universe. What if you turn up in a universe where Hitler is this really great, altruistic, humanistic guy who will come up with a cure for cancer and end world hunger and you cold bloodily shoot him? Not to mention the troubles you will have going back to you own version of the universe. What if the world you end up in is the one where you is that dictator shouting at mass meetings? Now, that could actually turn into a quite interesting episode of Doctor Who.