Here's a simple example, Someone travels back into time during their life time. At this point, would that someone double and exist twice in the same plane of existance? They say energy cannot be created or destroyed -- would be possible that maybe doing that -- the person doing so would be themself as they were at the time they went back to (not living 2 seperate planes of existance on 1 plane). maybe the outcome would be that someone remaining exactly the same only aqcuiring any memories, knowledge, etc. of what happens from the point travelled back to up until the point of origin. What do you think?