I'm on to time travel already

Wow. After watching Harry Potter last night I have come to the conclusion that time travel is completely plausible, but in the fashion depicted in the movie implies teleportation, which may or may not be desirable. The fact that they disappeared when they went back in time was the key. I always figured time travel was inherently illogical because it involved making a permanent clone of yourself (eg. go back in time and see yourself, then there's two of you forever). It has to, of course, be perfectly consistent (no killing your parents), but is completely logical - one's 'local time' (what your consciousness experiences) just follows a bit of a wonky route through the 'world time', sometimes going in the wrong direction.

I don't like the idea of teleportation. I don't know why. Instead of teleporting back in time (and also space), I would rather it be possible to move back in time, but this creates two immediately apparent issues:

• Physics. I haven't really thought about it, but watching people do things quickly and slowly and interacting with them would destroy the laws of physics, I think.

• When you started moving backward, you would be in the same position as the forward-moving person you that you were just being - two overlapping physical bodies. It could either be just dealt with (yes, they do overlap), or something else happens. I just don't know what the something else could be though.