> Also, speaking of going back in time, it would be impossible. Because, say, you go back in time to save yourself from some tragedy (Maybe you get in a car accident when you were young or something). You go back in time, save yourself, fine and dandy. You go back to your time, but the past you that needed to go back in time to save yourself won't, because they were never in the car accident. Therefore, the car accident would happen, so they would need to go back in time, but then they solve it, so the car accident didn't happen, so they don't need to go back in time, but then they don't go back in time and the car accident happens, and on and on. Now, if you went back in time and just looked around, that might work.

I think the only way this could work is if time is two-dimensional. I'm sure someone has come out with a much more refined theory along these lines, but I haven't heard it so here's my shaky and still-to-be-fully-thought-out version: Imagine two parallel time streams (really there's an infinite number, but two is confusing enough.) They are identical (for the moment). Now imagine Simon, a young scientist. When he is 19, he is involved in a tragic car accident, killing his girlfriend and leaving him paralyzed. He perseveres, driven by grief and a desire to overcome his handicap. Finally, at the age of 39 (not that he would admit to being older), he invents a time machine, and goes back to when he is 19; except that he goes back to the 19-year-old in the *other* time stream, which up till now has been identical to his. The Simon of that time stream is merrily going about his business. The 39-year-old Simon manages to stop the car accident. Now the Simon of this time stream can go on to have a very different life, without affecting the past-future of 39-year-old Simon.

The only question here is, why would Simon want to do this, since he himself is not affected by the change? This bit I still have to work out. Other theories or systems of time travel that anyone has heard about which might relate to this... oh dear, I left that sentence with nowhere coherent to go and I'm too lazy to recast it. Anyway, I'd be happy to hear about them.

Lire"looking forward immensely to the Guy Pearce movie this weekend, by the way"lyn