interesting thought: Time travel into the future is known to be possible, but time travel into the past is a lot sketchier, and most likely impossible....say some genius figures out how to do it,& for some reason wanted to go back and try to kill his grandfather, one might think that in doing so, he'd cancel out his own existance, right?...NOPE...Something would get in his way to stop him, because of what is called The Grandfather Paradox - if he killed his grandfather, the time traveler would of never been born, and so would of never been able to build the time machine in the first place, and he would of never been able to go back into the past to begin with - crazy stuff