Parallel universe (fiction)

A parallel universe is a world or universe that exists outside of the observable universe but has a lot of the same things that it has. The trope of parallel universes is often used in fiction.

History

In 1884, Edwin Abbot Abbot wrote a book called Flatland about a world of flat which finds out about a world of round shapes.

In 1905, H. G. Wells wrote a book called A Modern Utopia. In the book, two people from Earth go to a world which is a utopia. Each of them has a doppelgänger there. Wells also wrote books where time travel changed history and created different worlds.

In 1934, Murray Leinster wrote a science fiction short story called "Sidewise in Time". In it, time changes, so people switch places from people in worlds whose history is different from what they know. Some people go to a world where the Roman Empire still exists. There’s a world where the Vikings took over North America. One person ends up in a world where the Confederate States of America won the American Civil War.

In 1961, DC Comics published a comic book called Flash of Two Worlds, where Flash runs so fast that he goes to another world. Because of this, the original version of Flash called Jay Garrick and the new version of Flash called Barry Allen meet each other. Barry Allen’s world is called Earth-One, and Jay Garrick’s is called Earth-Two.

In 1967, Star Trek had an episode called "Mirror, Mirror", in which Captain Kirk changes places with another version of himself from a Mirror Universe where he and all his crew (except Spock) are evil.

In the 1970s, a show called The Tomorrow People involved time travel being used to change history and create new worlds.

Terry Pratchett’s Discworld books are set in a parallel universe. In Lords and Ladies, the characters talk about the idea of a multiverse.

The 1993 movie Super Mario Bros has Mario and Luigi go to a world where the dinosaurs never went extinct.

The 2009 movie Star Trek is about Spock and his enemy going back in time, changing the past, and creating a new universe.

In the television show Once Upon a Time, all fairy tales are true, but they happened in their world called The Enchanted Forest. The only people from our world who can go to the Enchanted Forest are people who write stories about what happens in it for people in the real world to read. It later turns out that not only are all fairy tales true, but all fictional stories are true, including Frankenstein, Dr. Jekyll and Mr. Hyde, Twenty Thousand Leagues Under the Sea and Moby-Dick. When Emma Swan wishes she were never the Chosen One, it creates a new world where she never was called The Wish Realm. And then it turns out that not only every fairy tale is true, but every different version of the same fairy tale is true, so if there’s an Italian version of Snow White and a French version of Snow White, then each one is real and exists as its world.

Since then, the Arrowverse superhero television shows and the Marvel Cinematic Universe have both used parallel universes a lot.