In the past few years, TV shows and movies like Flash and other superheroes have changed the way we perceive the world. One of the core elements of the Flash TV show is the multiverse, or the belief that there are many different universes in the world. And you can exist in all of them.
Thanks to popularity of Flash and other superheroes, some science theories have also gained on popularity. One of those is the actual theory of multiverse and parallel universes.