THE "GRANDFATHER PARADOX" ISN'T REAL!
Contrary to the way it’s most often portrayed in the movies, time travel, while definitely possible, is never to a place on your own time line. When you travel back to the “past,” it can only be to a parallel line of reality, even if it is one that very, very closely resembles the current one you’re in. Or on. The so-called “Grandfather Paradox,” a staple of science fiction, where you go back into the past and kill your grandfather, thereby eliminating the possibility that you would ever have been born and been able to eventually go back in time to kill your grandfather, is in fact, a fictional dilemma. Why? Because the grandfather you would be killing would be in a parallel line of reality, and therefore a different version of himself, which means that the you that would never be born would be, or would have been, a different version of you. (Likewise, the “Marty” that was disappearing in “Back To The Future” because he was inadvertently preventing his parents from ever meeting, couldn’t be the Marty who went back to the past, because that past was a parallel line of reality, and that disappearing Marty was a different version of himself.)