Discovering alternate realities
Imagine a world where WWII never happened? Where the South won the Civil War? Where your parents never met and you were never born? This could all be possible if the theory of the multiverses could be confirmed.
Even scientists are thinking it's possible...
While there are some suspicions that there are more than one universe out there, there is no way to confirm the theory as of now because of the risks that may occur to those that should try to travel to the ends of space, where supplies would be impossible to get.
It's A Wonderful Life
I really liked this movie when I first saw it. During the movie, a man, after trying to commit suicide but being stopped by a mysterious man, is shown an alternate reality in which he was not born. His savior, which turns out to be an angel, shows him how throughout the course of his life, he had affected many people and how different their lives would be if they had never met him. Though there isn't a lot of explaining of how is it that someone can travel to an alternative reality, there have been many times in films and tv shows were characters have met their alter egos that, although sharing some characteristics and personal experiences, can have drastic differences. This concept is for me very interesting, because it points out the fact that our experiences and outcomes of events affect our life radically. If I had acted differently in a situation, I would probably be a different person than who I am today.