Dear 100 Hour Board,
The idea of parallel universes, alternate realities, multiverses, etc. is prominent in popular fiction today, even those that would otherwise seemingly fall outside of what one might normally classify as "sci-fi" (e.g. superhero stories, alternate histories, AU fan fiction). Like many sci-fi concepts, though, it feels like it's a relatively recent trope in storytelling. I remember the concept from Star Trek episodes and comic books growing up even before I noticed it being featured prominently in the zeitgeist so it's always felt like a very natural thing for me to accept in fiction. It also fits well with some metaphysical theories like the many worlds interpretation of quantum mechanics and multiverse theory, but these are relatively recent ideas within the scientific community. Even before scientists began writing and lecturing about the theories in the 1950s, Edwin Abbott explored alternate dimensions in Flatland and Wells brought in parallel universes to many of his stories.
I'm interested in how the "alternate reality" concept developed even prior to the late 19th century. It doesn't entirely seem like it came out ex nihilo around that time but I'm not sure how to go about tracing its development in both science/philosophy and fiction. I'm not expecting a writer to do that research for me but I'm having trouble finding which resources to look into. Can you point me to books, etc. that cover this where I can read more?
-My Name Here
Dear My Name Here,
I'm sorry this answer took so long in this universe! I'm sure that in another universe this question was answered in exactly 99 hours by the 99 Hour Board. You are right that the idea of parallel universes didn't just appear out of nothing. Although alternate realities have become quite the fad, books about different realities have been around for more than 100 years. There a so many of them that explaining them all would take way too long. If you're really interested on some deep research I highly recommend the Wikipedia article on parallel universes (thanks Djengo Fett for the suggestion). I'll just attempt to hit some highlights in the history of parallel universes.
- Mythologies and Religions: Many religions and mythologies speak of existences outside of the earthly realm. Depending on your definition Heaven and Hell could be counted as parallel universes. Greek Mythology has Olympus and the Underworld and Norse mythology has Valhalla. Hinduism believes in many different gods and in multiple universes. These might not fit our current definition of parallel universes, but stories about other universes have existed for millennia.
- Mabinogion: The Mabinogion is a collection of Welsh tales. In some of the stories the characters travel between Wales and the Dream Realm. This collection of stories was first compiled around the 12th or 13th century and is one of the earliest recorded stories of humans traveling between multiple realms or dimensions. It also includes some of the earliest accounts of King Arthur and Merlin.
- The Blazing World:The Blazing World was published in 1666 by Margaret Cavandish tells of another world that could be reached by a portal in the North Pole. The other world is similar to our own in many aspects, but has different animals, different stars, and a Utopian society.
- Flatland:Flatland was an amazing book about multiple dimensions written by mathematician Edwin A Abbot. It tells the story about a square in a 2-dimensional world called Flatland. The square makes contact with a 3-dimensional sphere who can see above flatland and travel 3-dimensionally. This book is ground breaking because it is one of the first to suggest the idea of more than 3 dimensions.
- Men Like Gods: Men Like Gods was written by H. G. Wells and involves people from Earth being transported to a Utopian world. This book is notable for being written by the famous pioneer of science fiction, H. G. Wells.
- Sideways in Time: Sideways In Time may be the first book that writes about parallel universes in the way we think of them today. Author Murray Leinster writes about the idea of parallel universes similar to our own (such as a universe where the Confederacy won the Civil War) that can be traveled to by going through the time dimension.
- Chronicles of Narnia: The tales of the Pevensie children and their adventures in the mythical land of Narnia are amazing and wonderful stories. Not only are they amazing books, but they're also notable because time on Earth and time in Narnia pass very differently, which is an important and interesting concept for parallel universes.
- Flash of Two Worlds: Flash of Two Worlds is the first comic to include the crossover between two multiverses. In this comic the Flash accidentally transports himself to another world where he meets Golden Age Flash. The crossover between the two Earths soon became a common occurrence in the comics and has since been used in many super hero stories
- Star Trek: Star Trek regularly explored the idea of worlds similar to our own. Some of these worlds had evolved similarly to Earth independently, and others had similarities due to previous interactions with Earth travelers. Star Trek is one of the most prominent and popular sci-fi series, so the popularity of parallel universe stories certainly owes something to Star Trek.
- Dr. Who: Since it first aired in the 1960's The Doctor has been traveling through time and dimensions with the TARDIS. Although it has been around for a long time, several years ago Dr. Who became immensely popular and even mainstream. When I think of traveling through different dimensions and alternate timelines, Dr. Who is one of the first things to come to mind.
These are just a few of tens and hundreds of books and tv shows about multiple universes. I wish I could cover more, but in my current time line I'm behind on my classes and can no longer spend more time on the answer. If I ever invent time travel in the future I'll come back and fix it. I hope this helps! I'm sure that you will find more than you can ever want just by chasing links on Wikipedia.
Thanks for asking such a great question. Until next time!