The Multiverse / Literature

• Anathem by Neil Stephenson combines this with of all things Platonic Epistemology to very severely deconstruct many aspects of the multiverse. For example, atomic nuclei are subtly different between universes so any reaction between molecules from different universes is retarded (i.e. breathing).
• Astral Dawn by Adam R. Brown tackles this in a somewhat different way, as the multiverse is referred to as the Nursery of Dimensions. A race of extradimensional aliens called the Aash Ra are charged with safeguarding the Nursery. A single universe out of the multitude lies at the heart of the Astral Dawn saga. Because of its nature, it is called the anomalous dimension.
• Bazil Broketail: The books' universe has many different worlds and planes of existence over which the battle between good vs evil is waged.
• The Beyond Reality series has this as its main setting, with a wide variety of locales and one-shot universes that appear throughout each story. The series also discusses and explores the idea more in depth with acknowledgements about the differences between reality and fiction, the differences and similarities between dimensions, universes, and timelines, various afterlives and pantheons, as well as concepts like the megaverse and omniverse.
• Variation: Timothy Zahn's Cascade Point stories feature a faster than light drive system which has the side effect of showing you alternate versions of yourself whenever you activate it, based on different possible outcomes of your life. At least one story features a Phlebotinum Breakdown that drops the ship into one of those universes. It is a Multiverse, but it's not one where you can easily travel between worlds.
• Kate in Choices by Deborah Lynn Jacobs. After her brother dies, she starts traveling between new universes with only slight changes from her own. For example, in one she was a pushover. In another she was a Perky Goth. She would usually go to sleep and wake up in a new universe.
• Roger Zelazny's The Chronicles of Amber has one reality, Amber, which casts an infinite number of Shadows, each one a full world (with Earth among them). The Princes of Amber can travel at will to these worlds by using Tarot cards as portals, or by walking the shadows and altering them until they stand in the world they desire.
• The Coming Of The Quantum Cats, while generally forgettable, has some fun with this trope. The great scientist Dominic Desota invents a machine for traveling between universes, but in one universe it's stolen by General Desota, who aims to become a Multiversal Conqueror. Opposing him are the heroes, Senator Desota and Nicky Desota.
• Harry Turtledove's Crosstime Traffic series posits that a technology has been developed to allow inhabitants of the "main timeline" (Earth as we know it) to go into alternate "timelines" and return to this one, including bringing items between the worlds (everything from blue jeans to agricultural products) and the opportunity for experiences not possible in this timeline, such as birdwatching in a world where passenger pigeons still exist.
• Colin Kapp's The Dark Mind (also published as The Transfinite Man) uses this. The alternate universes were originally empty until mankind (in the form of the evil Failway Company) discovered them and, basically, turned them into vice dens.
• Stephen King's The Dark Tower series and the numerous books that feed into it (or got sucked into it) is based on the notion that all of the weird alternate realities visited by the Gunslinger, plus all of the alternate continuities of King's earlier books are part of a Multiverse that are all connected by the eponymous tower. All these worlds are apparently subservient to the world in which the fictionalized version of King lives, and the characters discover that they are all in fact being channeled by King the novelist, a la Stranger Than Fiction.
• In the Darwath series by Barbara Hambly, master wizard Ingold Inglorion crosses from Darwath to Earth via "the Void." He later describes the Void as a sort of super-universe that contains many separate, more or less parallel universes. When protagonists Gil Patterson and Rudy Solis are in Darwath, Gil notices that the stellar constellations look similar to Earth's, suggesting that Darwath is a parallel Earth. All of the animals and plants of Darwath are also analogs of known Earth animals, save for a few that were obviously created by magic.
• Diana Wynne Jones's series, standalones and short stories often feature Multiverses or at least two different alternate realities. Count them:
  • The Chrestomanci Chronicles
  • Dark Lord of Derkholm
  • Howl's Moving Castle
  • The Magids series
  • The Homeward Bounders
  • A Sudden Wild Magic
  • The Game
  • Everard's Ride (this one's a novella)
  • "Dragon Reserve, Home Eight" (this is a short story)
  • One might theoretically consider A Tale of Time City as well. Time City is not technically another world per se, but it runs along the much of the same ideas.
• The Discworld novels often allude to a multiverse. Since all libraries, everywhere, in every space, universe and time are connected, you can reach this L-space in the Library of Unseen University. If the Librarian lets you in, of course.
  • Also, in The Colour of Magic, Rincewind and Twoflower briefly find themselves occupying/incarnated in/deluded into thinking they are alternate universe versions of themselves, sitting next to each other on an airplane in a world that appears to be our normal Earth.
  • Our Earth plays a greater role in the Science of Discworld series, where the wizards know it as "Roundworld".
  • Moreover, the existence of alternate worlds (i.e. different legs of the Trousers of Time) is a given in several novels. Granny Weatherwax starts picking up random memories from these alternate worlds in Lords and Ladies, and Sam Vimes accidentally swaps P.D.A.s with his ill-fated counterpart from an alternate world in Jingo.
  • Also in Lords and Ladies Ponder Stibbons (a wizard version of a physicist) tries to explain the "many worlds'' principle to the Archchancellor (chief Wizard). Of course this goes badly as the Archchancellor is mainly concerned about why his trousers have anything to do with it, and why his parallel self never sent him a wedding invite...
• Isaac Asimov's The Gods Themselves is about the discovery of a way to transport materials from our universe to another one^note Or rather, aliens from the other Universe discovered the technology, and began sending us materials in the hope that we'd figure out what was going on and exploit it where the Laws of Physics operate slightly differently than they do here. The practical upshot of this is that the difference in physical law can be harnessed to create free, unlimited power. It's eventually discovered that continued use of this power source will result in the Solar System collapsing into a quasar. Worse yet, the aliens from the other dimension who created this transdimensional transportation technology are fully aware of this, and are taking advantage of our desire for free energy to prolong the life of their own star.
• His Dark Materials features many an Alternate Universe, with a few powerful items allowing one to travel between them. There may be no limit to the number of separate worlds and universes.
• The world of INVADERS of the ROKUJYOUMA!? was created by the series Goddess awakening after she meets the hero, Satomi Koutarou, when an attacker accidentally throws him - and herself - out of the timeline to before creation. She falls in love with him and creates an entire multiverse - including multiple copies/versions of the titular Invaders, to give him infinite opportunities to fall in love with her on her own terms. That said, characters from only one alternate universe have appeared in canon through Volume 41, and travel between universes is very difficult.
• In The Invisible Library, Irene is a Librarian for the Library, a mysterious Magical Library that collects rare books from every different version of reality (referred to as "alternates").
• The core premise of the Lafayette O'Leary series. In The Time Bender, O'Leary finds himself transported to the kingdom of Artesia in an alternate universe. In The World Shuffler, he is transported to another world, Melange, which is a close parallel to Artesia, and even has alternate versions of several of the people he knows from Artesia, including his wife.
• The Lensman novels of E. E. "Doc" Smith take place in a multiverse with the features that most universes within the multiverse contain very few planets. The megalomaniac but highly advanced Eddorian race develop a hyper-spatial tube to travel between universes until they find one teaming with new planets to conquer. The equally-advanced native race of Arisians conduct an eons-long program of uplift to ensure the races evolving on the newly formed planets can fight the Eddorians alongside them.
• From a collaboration of Terry Pratchett and Stephen Baxter, the titular Long Earth is a series of alternate Earths, each different, though the amount and type of difference between one and the next varies. Because of peculiarities of evolution, only one Earth (that we know of) spawned humans and the vast majority never developed intelligent hominids of any kind, leaving the whole set in the care of one Earth's-worth of humans, and their alternate-universe cousins, named after common fairy-tale creatures like elves and trolls. There are two unique wrinkles in the alternate-earth system presented in this series:
  Firstly, the Earths are linked in a chain, and you can only "step" from one Earth to one of the two adjacent ones; even stepping at high speed, it takes quite a while to get from one Earth to a radically different one, although there are short-cuts that make long-distance "travel" more feasible. The chain might be infinite, or might be a closed loop. Secondly, each planet has its own chain of alternates; if you go to Mars, as occurs in the third book, none of the alternate Marses you can step to will correlate with any alternate Earths in the chain you came from.
• The trope's name, and, indeed, the basic modern concept for The Multiverse as its used in fiction, comes from Michael Moorcock's books. His many books range a vast array of worlds yet a sizable proportion of them are connected via Canon Welding. Robert A. Heinlein used this name in The Number of the Beast (see below) as well.
• Introduced as the Whole Sort of General Mish-Mash in Mostly Harmless. As explained, any random slice of the Mish-Mash, at any angle, is seen by the inhabitants a functional 4-dimensional universe. This means that parallel universes a) aren't parallel, and b) aren't universes.
• The Chronicles of Narnia mainly feature travel to and from Narnia, but in The Magician's Nephew it's explained that our world and Narnia are only two of a Multiverse of worlds. We only ever see three, though. Five, if you count the Wood Between the Worlds, and Heaven, although this it is portrayed as being as clearly and obviously different from the rest as a cube is from a square.
• Briefly touched upon in The Neverending Story: Gmork's conversation with Atreyu in Spook City implies that Fantastica and the human world are part of one.
• The entire point of the Paratime series by H. Beam Piper was that the main character's culture had exhausted its resources and was sponging off the entire Multiverse.
• Perry Rhodan is explicitly set in a multiverse, but deliberate travel between different universes isn't easy or necessarily safe. Problems involve the (at Galactic tech levels) largely unsolved issue of trans-universal navigation and the problem of adapting to the new physical laws of the destination, which has resulted in "strangeness shock" rendering entire starship crews comatose for months on arrival in the past. The focus of the action thus remains on the default 'main' universe, though interaction with others (including one in which time runs much more slowly, one that consists entirely of antimatter, and one that was and presumably still is heading for an artificially accelerated 'big crunch') has occurred in the past.
• From some point of the series onward, Hatou in Qualia the Purple can interact with all the parallel worlds. Each of these is one of the infinite possibilities for the flow of events that didn't get determined in her world.
• The Quantum Enchantment trilogy and its sequel by Kim Falconer uses the 'many-worlds' concept as a plot device. Working from memory, there is a dystopian Earth a few hundred years in the future, and a completely separate world where magic and the like are common place. Throughout the series, the characters manage to get themselves lost in the 'corridors' between the worlds, often returning to what would be their home but for some sort of twist — a battle was won instead of lost, time flows in a different direction, person X never existed. It gets somewhat confusing after a while.
• Reign of the Seven Spellblades: In volume 5, Professor Demitrio Aristedes explains the Constructed World's cosmology by introducing the concept of a "tír": a world distinct from our own that obeys different physical laws, with different environments and ecosystems, many of them controlled by a God-Emperor of sorts. The earth the protagonists live on is an "atheosphere" because God Is Dead, and what mages call magic was originally the authority invested in a god until an alliance of humans and demihumans killed it. Every star in the sky is said to be "a glimpse of a tír", and the brighter the star, the easier it is to reach. Eight tír in particular come into conflict with our world on a cyclical basis, allowing alien creatures to migrate to it and "apostles" of the tír gods to come and try to establish cults among humans and demihumans, called Gnostics. The Magocracy, in turn, created the Gnostic Hunters to defend against such incursions.
• The Riftwar Cycle, by Raymond E. Feist involved several universes with magical travel between them. It's always dangerous though, because opening a hole in your universe may attract the attention of beings who were (barely) defeated once by gods...
• The Rising of the Shield Hero: It's revealed early on that each of the four Cardinal Heroes including protagonist Naofumi Iwatani is from a slightly different version of Earth: each compares the RPG Mechanics 'Verse they've been summoned into to a different MMORPG, none of which exists in the others' home worlds (except for Naofumi, who isn't a gamer and compares it to Light Novels instead). We later learn that the fantasy world is also one of many: the Cardinal Heroes clash with a different set of Cardinal Heroes from an Alternate Universe, and Naofumi later pursues an Arc Villain into their universe.
• Robert A. Heinlein has written about Multiverses more than once. The novel Glory Road has magical inter-universe travel, and several of his later novels (starting with The Number of the Beast) involve the Burroughs drive, an invention that lets you travel to other universes; but because of how the Multiverse works, those nearby universes will be the favorite fictions of the users of the drive. So you can leave Earth and the next universe over will turn out to be Oz... As a side effect, Heinlein managed to tie together practically everything he ever wrote into a single setting. He called his concept of fiction tied together through mankind's infinite imagination and the multiverse The World as Myth, and would use it to tie together not only every universe he ever created, but those of several other authors who wrote during his era as well.
• Sergey Lukyanenko's Rough Draft-Final Draft duology is set in a multiverse where travel between universes is accomplished using the seemingly magical Towers which in reality were created through highly advanced technology developed by the natives of a universe that suffered a devastating nuclear war. It's initially assumed that there are about a dozen worlds, but it's later revealed that the number is much higher, possible infinite.
• Vasili Golovachov's The Saviors Of The Fan duology (made up of The Envoy and The Deliverer) has a myriad parallel worlds some of which are similar to ours, while others vary wildly. And that's just those organized into a linked structure called the Worldfan, of which our world is a part, with the implication that there are countless other worlds. According to the protagonist's half-Japanese friend, some of these worlds may be familiar from folk tales or science fiction/fantasy novels, as information has a tendency to "leak" between the worlds, meaning all those stories are actually true in other worlds. There is a world where the mere act of moving alters the surrounding reality (making finding your way back extremely difficult), or a world made up of a gigantic tree.
• The Schizogenic Man: Every time Heron undergoes Mental Time Travel, his mind jumps from one timeline to another. He can only travel to timelines where some version of himself exists, so even when he makes major changes like saving Cleopatra's son Kaisarion, he comes back to find the world relatively unchanged. He eventually learns that MEQMAT, the supercomputer that allows him to time travel, is doing this in an unsuccessful attempt to find a timeline where it will not be destroyed in a nuclear war with Texas.
• Sherlock Holmes and Doctor Was Not. In "The Final Prologue", Professor Moriarty has discovered The Multiverse and is exploiting it for criminal gain. He brings over alternate counterparts to impersonate himself, and arranges for Evil Counterparts to Kill and Replace their counterparts in this world—his Evil Plan in the tale is to do this to Holmes and Watson.
• The setting of A Tale of the Unwithering Realm. Each version of Earth (called an "Aeon") in the Multiverse is an Earth where some Christian miracle never happened, which turns out to have major consequences, as each Earth is inhabited by various beings from mythology. The world of Cainem is one where humans were never exiled from Eden, and thus all are immortal (and not enjoying it at all); Thalassa is a world where Noah's flood never ended, and so it's inhabited by mermaids; Sidon is where David failed to kill Goliath, who begat a race of giants, and so on. The main villains, the empire of the Dark Tower, come from Ur, where the construction of the Tower of Babel was successfully completed.
• The world of The Traitor Son Cycle is eventually revealed to be only one of multitude of "spheres", each sphere being its own universe. Various Wild creatures — as well as, apparently, humans — have arrived in it from other worlds, and the Powers That Be are fighting over this sphere because it contains gates that lead to seven others.
• Sharon Farber's "Trans Dimensional Imports" (1980). Contact between universes is difficult because the necessary equipment has to be operating in both at the same time, but one scientist has succeeded in contacting her alternate self. They've build a minor business, trading literary works that exist in one world but not the other. With expanded bandwidth, they're considering other art forms. E.g. in one universe, Ronald Reagan went into politics, becoming governor of California. In the other, he had starred in a B-movie called Casablanca. So they agree to a swap — "You get a classic; we get a joke."
• Transition by Iain Banks
• In The Wheel of Time, there is a multitude of possible other 'verses, called the 'Worlds That Might Be', which are basically Alternate Universes. The less likely they are, the more faded they look. A channeler can be transported to one of these by using a Portal Stone and the One Power.
• Andrey Livadny has decided to link his Long-Running Book Series The History of the Galaxy with several other works in order to create a new setting called The History of Worlds, which features five distinct parallel realities that make contact with one another. Each of those worlds has humanity go through radically different histories and, possibly, meet different alien races (apparently, humans are the only race that exists in all five realities). In one world (The History of the Galaxy universe), humanity has spread out into the galaxy, settling hundreds of worlds and encountering half a dozen alien races. In another world (Another Mind universe), humanity is still at the level of development of the early 21st century, when it comes under alien attack. In the Life Form universe, humans are busy settling the Solar System, planning to explore the galaxy using STL ships, when alien artifacts are discovered on some of the planets. In the Contact universe, humanity is exploring the stars using hyperspace with Earth becoming a City Planet and AIs everywhere. Then an archaeological dig on Ganymede finds evidence of multiple alien races. Finally, in the Omni universe, Earth is a radioactive wasteland following a mutually-destructive war between humans and Insectoid Aliens, whose homeworld was destroyed in retaliation for them nuking Earth. The remains of both races struggle to survive, while another race schemes to end them.
• Worlds of Shadow: The story reveals alternate universes exist, and are nearly infinite in number. However only two others are actually shown: one is a sci fi style universe with an interstellar empire, the other a fantasy world. It's explained the universes you can visit must have features in common.

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