Parallel universe

Parallel universe or alternate reality in science fiction and fantasy is a self-contained separate reality coexisting with our own. This separate reality can range in size from a small geographic region to an entire new universe, or several universes forming a multiverse.

While at first blush these stories might all seem, necessarily, to be total fantasy, the great majority are considered instead within the hard science fiction subgenre of science fiction as their derivation is seen as a literary interpretation normally instead rooted in scientific subfields of cosmology intersecting quantum mechanics. These give rise to certain mathematical necessities which are broadly grouped in what is known as the Copenhagen school, and specifically one particular opposed alternative-school which postulates a Many Worlds Theory. See science articles: Many-worlds school and multiverse (science). Several other less widely accepted theories within the science of physics are listed the disambiguation article: multiverse.

Introduction

Fantasy has long borrowed the idea of “another world” from myth, legend and religion. Heaven, Hell, Olympus, Valhalla are all “alternate universes” different from the familiar material realm. Modern fantasy often presents the concept as a series of planes of existence where the laws of nature differ, allowing magical phenomena of some sort on some planes. In other cases, in both fantasy and science fiction, a parallel universe is a single other material reality, and its co-existence with ours is a rationale to bring a protagonist from the author's reality into the fantasy's reality, such as in The Chronicles of Narnia by C.S. Lewis. Or this single other reality can invade our own, as when Margaret Cavendish's English heroine sends submarines and "birdmen" armed with "fire stones" back through the portal from the Blazing World to Earth and wreaks havoc on England's enemies. In dark fantasy or horror the parallel world is often a hiding place for unpleasant things, and often the protagonist is forced to confront effects of this other world leaking into his own, as in most of the work of H.P. Lovecraft and the Doom computer game series. In such stories, the nature of this other reality is often left mysterious, known only by its effect on our own world.

Often the alternate worlds theme in science fiction is framed by the "many worlds" interpretation of quantum mechanics, postulating that every historical event spawns a new universe for every possible outcome, resulting in a number of alternate histories. This kind of alternate universe is often the backdrop of stories involving time travel and is often used to rationalize the logical paradoxes that arise when an author allows characters to travel backward in time. (see: grandfather paradox) The concept also arises outside the framework of quantum mechanics, as is found in Jorge Luis Borges' short story El jardín de senderos que se bifurcan ("The Garden of Forking Paths"). In the story, a Sinologist discovers a manuscript by a Chinese writer where the same tale is recounted in several ways, often contradictory, and then explains to his visitor (the writer's grandson) that his relative conceived time as a "garden of forking paths", where things happen in parallel in infinitely branching ways. While this is a common treatment in SF, it is by no means the only presentation of the idea, even in hard science fiction. Sometimes the parallel universe bears no historical relationship to any other world; as in the novel Raft by Stephen Baxter, which posits a reality where the gravitational constant is much larger than in our universe.

It should be noted that the division between science fiction and fantasy becomes fuzzier than usual when dealing with stories that explicitly leave the universe we are familiar with, especially when our familiar universe is portrayed as a subset of a multiverse. Picking a genre becomes less a matter of setting, and more a matter of theme and emphasis; the parts of the story the author wishes to explain and how they are explained. Narnia is clearly a fantasy, and the TV series Sliders is clearly science fiction, but works like the World of Tiers series tend to occupy a much broader middle ground.

Uses in science fiction

Other dimensions

While technically incorrect, and looked down upon by hard science-fiction fans and authors, the idea of another “dimension” has become synonymous with the term “parallel universe”. The usage is particularly common in movies, television and comic books and much less so in modern prose science fiction.

In written science fiction, “new dimensions” more commonly — and more accurately — refer to additional coordinate axes, beyond the three spatial axes we are familiar with. By proposing travel along these extra axes, which are not normally perceptible, the traveler can reach worlds that are otherwise unreachable and invisible. One of the first works of modern science fiction, The Time Machine by H. G. Wells used time as an additional “dimension” in this sense, taking the four-dimensional model of classical physics and interpreting time as a spatial dimension in which humans could travel with the right equipment.

There are many examples where authors have explicitly created additional spatial dimensions for their characters to travel in, to reach parallel universes. Douglas Adams, in the last book of the Hitchhiker's Guide to the Galaxy series, Mostly Harmless, uses the idea of probability as an extra axis in addition to the classical four dimensions of space and time. Though, according to the novel, they're not really parallel universes at all but only a model to capture the continuity of space, time and probability. Robert A. Heinlein, in The Number of the Beast, postulated a six-dimensional universe. In addition to the three spatial dimensions, he invoked symmetry to add two new temporal dimensions, so there would be two sets of three. Like the fourth dimension of H. G. Wells’ time traveler, these extra dimensions can be traveled by persons using the right equipment.

Hyperspace

Perhaps the most common use of the concept of a parallel universe in science fiction is the concept of hyperspace. Used in science fiction, the concept of “hyperspace” often refers to a parallel universe that can be used as a faster-than-light shortcut for interstellar travel. Rationales for this form of hyperspace vary from work to work, but the two common elements are:

1. at least some (if not all) locations in the hyperspace universe map to locations in our universe, providing the “entry” and “exit” points for travelers.
2. the travel time between two points in the hyperspace universe is much shorter than the time to travel to the analogous points in our universe. This can be because of a different speed of light, different speed at which time passes, or the analogous points in the hyperspace universe are just much closer to each other.

Sometimes "hyperspace" is used to refer to the concept of additional coordinate axes. In this model, the universe is thought to be "crumpled" in some higher spatial dimension and that traveling in this higher spatial dimension, a ship can move vast distances in the common spatial dimensions. An analogy is to crumple a newspaper into a ball and stick a needle straight through, the needle will make widely spaced holes in the two-dimensional surface of the paper. While this idea invokes a "new dimension", it is not an example of a parallel universe. It is a more scientifically plausible use of hyperspace. (See wormhole.)

While use of hyperspace is common, it is mostly used as a plot device and thus of secondary importance. While a parallel universe may be invoked by the concept, the nature of the universe is not often explored. So, while stories involving hyperspace might be the most common use of the parallel universe concept in fiction, it is not the most common source of fiction about parallel universes.

Time travel and alternate history

The most common use of parallel universes in science fiction, when the concept is central to the story, is as a backdrop and/or consequence of time travel. A seminal example of this idea is in Fritz Lieber’s novel, The Big Time where there’s a war across time between two alternate futures each side manipulating history to create a timeline that results into their own world. Time-travelers in fiction often accidentally or deliberately create alternate histories, such as in The Guns of the South by Harry Turtledove where the Confederate Army is given the technology to produce AK-47 rifles and ends up winning the American Civil War. The alternate history novel 1632 by Eric Flint explicitly states, albeit briefly in a prologue, that the time travelers in the novel (an entire town from West Virginia) have created a new and separate universe when they're transported into the midst of the thirty years war in 17th Century Germany.

The concept of "sideways" time travel is often used to allow characters to pass through many different alternate histories, all descendant from some common branch point. Often worlds that are similar to each other are considered closer to each other in terms of this sideways travel. ie. A universe where WWII ended differently would be “closer” to us than one where Imperial China colonized the New World in the 15th century. H. Beam Piper used this concept, naming it "paratime" and writing a series of stories involving the Paratime Police who regulated travel between these alternate realities as well as the technology to do so. Keith Laumer used the same concept of "sideways" time travel in his 1962 novel Worlds of the Imperium. More recently, Frederik Pohl used the idea in his novel The Coming of the Quantum Cats which is explicitly based on upon a human-scale reading of the "many worlds" interpretation of quantum mechanics, postulating that every historical event spawns a new universe for every possible outcome.

It can be argued that most modern alternate histories implicitly refer to parallel universes, based on the above reading of quantum theory. However, many of these works are presented as self-contained worlds in and of themselves, and can be read without resort to additional universes being present. For example, outside The Guns of the South, the large part of Turtledove’s work in alternate history makes no reference to any other universes other than the ones in which the stories take place. And Philip K. Dick's classic novel The Man in the High Castle features a universe in which the Axis won World War II, and the only other universe "present" is fictional, in a book whose author imagines an alternate world (different from our own) in which the Allies won.

Uses in fantasy

Stranger in a strange land

Fantasy authors often want to bring characters from the author's (and the reader's) reality into their created world. Before the mid-20th Century, this was most often done by hiding fantastic worlds within hidden parts of the author's own universe. Characters in the author's world could board a ship and find themselves on a fantastic island, as Jonathan Swift does in Gulliver's Travels or in the 1949 novel Silverlock by John Myers Myers, or be sucked up into a tornado and land in Oz, or go down a rabbit hole and end up in Wonderland. These "lost world" stories can be seen as geographic equivalents of a "parallel universe," as the worlds portrayed are separate from our own, and hidden to everyone except those who take the difficult journey there. The geographic "lost world" can blur into a more explicit "parallel universe" when the fantasy realm overlaps a section of the "real" world, but is much larger inside than out, as in Robert Holdstock's novel Mythago Wood.

After the mid-20th Century, perhaps influenced by ideas from science fiction, many fantasy worlds became completely separate from the author's world. A common trope is a portal or artifact that connects worlds together, prototypical examples being the wardrobe in C.S. Lewis' The Lion, the Witch, and the Wardrobe or the sigil in James Branch Cabell's The Cream of the Jest. The main difference between this type of story and the "lost world" above, is that the fantasy realm can only be reached by certain people, or at certain times, or after following certain rituals, or with the proper artifact.

In some cases, physical travel is not even possible, and the character in our reality travels in a dream or some other altered state of consciousness. Examples include the Dream Cycle stories by H. P. Lovecraft or the Thomas Covenant stories of Stephen R. Donaldson. Often, stories of this type have as a major theme the nature of reality itself, questioning if the dream-world can have the same "reality" as the waking world. Science fiction often employes this theme (usually without the dream-world being "another" universe) in the ideas of cyberspace and virtual reality.

Between the Worlds

The most common use is to transport a character from the real world into the fantasy world where the bulk of the action takes place, as when Norton Juster takes his protagonist through The Phantom Tollbooth to the Kingdom of Wisdom. Whatever gate is used is left behind for the duration of the story, until the end, and then only if the protagonists will return, and along the way, the wonders they encounter belong to the world they traveled to.

A writer may also make the interaction between the worlds an important element, so that the focus is not on one world or the other, but on both, and their interaction. After Rick Cook introduced a computer programer into a high fantasy world, his wizardry series steadily acquired more interactions between this world and ours, including dealing an invader from ours. In Aaron Allston's Doc Sidhe — where our "grim world" is paralleled by a "fair world" where the elves live but their history still echoes ours, fifty years late — a major portion of the plot dealt with preventing a change in interactions between the worlds. Margaret Ball depicted in her No Earthly Sunne interaction of our world with Faerie; although Faerie itself is the setting for very few scenes, Faerie, and the efforts of the Queen of Faerie to deal with the slow drifting apart of Earth and Faerie, is the motive force of the plot.

Multiple worlds, rather than a pair, increase the importance of the relationships. In The Lion, the Witch, and the Wardrobe, there are only our world and Narnia, but in other of C. S. Lewis's works, there are hints of other worlds, and in The Magician's Nephew, the Wood between the Worlds shows many possibilities, and the plot is governed by transportation between worlds, and the effort to right problems stemming from them. In Andre Norton's Witch World, begun with a man from Earth being transported to this world, gates frequently lead to other worlds — or come from them. While an abundance of illusions, disguises, and magic that repells attention make certain parts of Witch World look like parallel worlds, some are clearly parallel in that time runs differently in them, and such gate pose a repeated problem in Witch World.

When the worlds are multiplied and no longer hinted at but visibly structured, the fantasy work takes place in a multiverse.

Fantasy multiverses

The idea of a multiverse is as fertile a subject for fantasy as it is for science fiction, allowing for epic settings and godlike protagonists. Among the most epic and far-ranging fantasy "multiverses" is that of Michael Moorcock. Like many authors after him, Moorcock was inspired by the many worlds interpretation of quantum mechanics, saying:

It was an idea in the air, as most of these are, and I would have come across a reference to it in New Scientist (one of my best friends was then editor) ... [or] physicist friends would have been talking about it. ... Sometimes what happens is that you are imagining these things in the context of fiction while the physicists and mathematicians are imagining them in terms of science. I suspect it is the romantic imagination working, as it often does, perfectly efficiently in both the arts and the sciences.

Unlike many science-fiction interpretations, Moorcock's Eternal Champion stories go far beyond alternate history to include mythic and sword and sorcery settings as well as some worlds more similar to our own. However, the Eternal Champion himself is incarnate in all of them.

Roger Zelazny used a mythic cosmology in his Chronicles of Amber series. His protagonist is a member of the royal family of Amber, whose members represent a godlike pantheon ruling over a prototypical universe that represents Order. All other universes are increasingly distorted "shadows" of it, ending finally at the other extreme, Chaos, which is the complete negation of the prototype. Travel between these "shadow" universes is only possible by beings descended from the blood of this pantheon. Those "of the blood" can walk through Shadow, imagining any possible reality and then walk to it, making their environment more similar to their desire as they go. It is argued between the characters whether these "shadows" even exist before they're imagined by a member of the royal family of Amber, or if the "shadows'" existence can be seen as an act of godlike creation.

In the World of Tiers novels by Philip José Farmer, the idea of godlike protagonists is even more explicit. The background of the stories is a multiverse where godlike beings have created a number of pocket universes that represent their own desires. Our own world is part of this series, but interestingly our own universe is revealed to be much smaller than it appears, ending at the edge of the solar system.

But even works that deal with lesser beings, the structure of the multiverse may be significiant. Piers Anthony depicts two worlds in the Apprentice Adept series, the SF Proton and the fantasy Phaze, such that every person born in either world has a physical duplicate on the other world. Only when one duplicate has died can the other cross between the worlds.

Fictional universe as alternate universe

There are many examples of the meta-fictional idea of having the author's created universe (or any author's universe) rise to the same level of "reality" as the universe we're familiar with. The theme is present in works as diverse as Myers' Silverlock and Heinlein’s Number of the Beast. Fletcher Pratt and L. Sprague de Camp took the character Harold Shea in the Incompleat Enchanter series through the worlds of Norse myth, Edmund Spenser's Faerie Queene, Ludovico Ariosto's Orlando Furioso, and the Kalevala— without ever quite settling whether writers created these parallel worlds by writing these works, or received impressions from the worlds and wrote them down. In an interlude set in "Xanadu", a character claims that the universe is dangerous because the poem went unfinished, but whether this was his misapprehension or not is not established.

Some fictional approaches definitively establish the independence of the parallel world, sometimes by having the world differ from the book's account; other approaches have works of fiction create and affect the parallel world: L. Sprague de Camp's Solomon's Stone, taking place on an astral plane, is populated by the daydreams of mundane people, and in Rebecca Lickiss's Eccentric Circles, an elf is grateful to Tolkien for transforming elves from dainty little creatures. These stories often place the author, or authors in general, in the same position as Zelazny's characters in Amber. Questioning, in a literal fashion, if writing is an act of creating a new world, or an act of discovery of a pre-existing world.

Occasionally, this approach becomes self-referential, treating the literary universe of the work itself as explicitly parallel to the universe where the work was created. Stephen King's seven-volume Dark Tower series hinges upon the existence of multiple parallel worlds, many of which are King's own literary creations. Ultimately the characters become aware that they are only "real" in King's literary universe, and even travel to a world — twice — in which (again, within the novel) they meet Stephen King and alter events in the real Stephen King's world outside of the books.

Elfland

Elfland, or Faerie, the otherworldly home not only of elves and fairies but goblins, trolls, and other folkloric creatures, has an ambiguous appearance in folklore.

On one hand, the land often appears to be continuous to ordinary land. Thomas the Rhymer might, on being taken by the Queen of Faerie, be taken on a road like one leading to Heaven or Hell:

'O see ye not yon narrow road,
So think beset with thorns and briers?
That is that path of righteousness,
Tho after it but few enquires.

'And see not ye that briad braid road
That lies across the lily leven?
That is the path of wickedness,
Tho some call it the road to heaven.

'And see not ye that bonny road,
That winds about the fernie brae?
That is the road to fair Elfland,
Where thou and I this night maun gae.

but many others have found fairies and elves with greater ease. Sir Orfeo discovered the king who had kidnapped his wife by wandering in wilderness, and others have found them in elf hills near the homes, which digging could violate; in fairy circles, dancing in apparently ordinary woods; or riding through ordinary lands. While sometimes these could fairy intrusions into human lands — "Tam Lin" does not show any otherworldly aspects about the land the confrontation takes place — at other times the otherworldly aspects are clear. Most frequently, time can flow differently for those trapped by the fairy dance than in the lands they come from — although, in an additional complication, it may only be an appearance, as many returning from Faerie, such as Oisín, have found that time "catches up" with them as soon as they have contact with ordinary lands.

Fantasy writers have taken up the ambiguity. Some writers depict the land of the elves as a full-blown parallel universe, with portals the only entry — as in Josepha Sherman's Prince of the Sidhe series or Esther Friesner's Elf Defense — and others have depicted it as the next land over, possibly difficult to reach for magical reasons — Robin McKinley's "The Stolen Princess" in The Door in the Hedge or Lord Dunsany's The King of Elfland's Daughter. In some cases, the boundary between Elfland and more ordinary lands is not fixed. Not only the inhabitants but Faerie itself can pour into more mundane regions.

Other media

Television

The idea of parallel universes have received treatment in a number of television series, usually as a single story or episode in a more general science fiction or fantasy storyline.

The most widely known and imitated example is the original Star Trek episode entitled Mirror, Mirror. The episode introduced an alternate version of the Star Trek universe where the main characters were barbaric and cruel to the point of being evil.

The concept of an "evil" alternate universe has been a subject ripe for parody, even featured in the series South Park in the episode "Spookyfish" where the "evil" universe double of Cartman, the most obnoxious character, is pleasant and agreeable.

A more fantasy-oriented example is from the 1960s fantasy/horror soap opera Dark Shadows, which introduced the concept of "parallel time" when the main character, Barnabas, witnesses unexplainable changes in a closed off part of his family's house. During one of these changes, he becomes trapped for a time in a parallel world. A humorous take on the multiverse concept comes from an episode of the animated series Futurama where the cast travels between "Universe A" and "Universe 1" via boxes containing each universe, and then travel to numerous other parallel universes for brief periods, such as "Hippie Universe", "Robot Universe", and "Eyeless Universe". The BBC TV Series, Red Dwarf, also frequently includes parallel universes, including one episode where women are the dominant gender (Nellie Armstrong was the first person on the moon), and another where Arnold Rimmer becomes the far more dashing and debonaire Ace Rimmer.

Less commonly, television series will use parallel universes as an on-going subplot. This happened as Star Trek: Deep Space Nine and Star Trek: Enterprise elaborated on the premise of the original series' "Mirror" universe and developed multi-episode story arcs based on the premise. Other examples are the science fiction series Stargate SG-1 and the fantasy/horror series Buffy the Vampire Slayer. Interestingly, many of these alternate realities show humankind in desperate peril; in Stargate SG-1 the first encountered parallel reality featured Earth being overwhelmed by an unstoppable Goa'uld onslaught, while in Buffy, the vampires had overrun Sunnydale and Buffy and Angel were both killed trying to prevent them from massacring the human populace. When used as a subplot like this, the parallel/alternate realities often are worse than the "main" storyline's universe. This can be seen as influence from Star Trek, establishing the idea of an "evil" mirror universe, or as the writers using the device to show what is at stake in the main universe by portraying the worst that could happen or the consequences if the protagonists fail. The latter could also be seen as the point of the alternate reality portrayed in the movie It's a Wonderful Life (see below).

Examples of series using a parallel universe or universes as a central element of the series itself; the short-lived 1980s series Otherworld which transported a family from our world to an alternate Earth; and Sliders, where the characters travel across a series of "alternate" Earths, each different from their own in some way, trying to get back to their home universe. Doctor Who occasionally features parallel worlds: Inferno (1970), where Great Britain has been a republic since 1943 (the Royal Family having been executed) and is ruled by a totalitarian regime; and most recently, in Rise of the Cybermen and The Age of Steel, where Britain also has republican status and is run by a President.

Movies

The most famous treatment of the alternate universe concept in film could be considered the The Wizard of Oz, which portrays a parallel world, famously separating the magical realm of the Land of Oz from the mundane world by filming it in Technicolor while filming the scenes set in Kansas in sepia. A later example is the Frank Capra movie, It's a Wonderful Life where the main character George Bailey is shown by a guardian angel the city of Pottersville, which was George Bailey's hometown of Bedford Falls as it would have been if he had never existed.

Another notable film (actually is a trilogy) is Back to the future (1985) by Robert Zemeckis with Micheal J. Fox. The 1st film is a perfect example of so-called Grandfather paradox, and in the 2nd is a good example of divergence timeline.

More recent films that have explored parallel universes are the 2001 cult movie Donnie Darko, which deals with what it terms a "tangent universe" that erupts from our own universe. The 1993 film Super Mario Bros. has the eponymous heroes crossing over into a parallel universe ruled by humanoids who evolved from dinosaurs. Despite its title, The Adventures of Buckaroo Banzai Across the 8th Dimension, the film only has a few scenes showing the parallel universe that imprisoned the villainous leader of the Red Lectroids. In the film 'The One' starring Jason Statham and Jet Li, there is a complex system of realities in which Jet Li is a serial killer in one universe and a police officer in another, who travels to other universes to destroy versions of himself, so that he can become 'the one'. In the 2004 film FAQ: Frequently Asked Questions, the main character runs away from a totalitarian nightmare, and he enters in a cyber-afterlife alternative reality.

Comic books

Parallel universes in modern comics have become particularly rich and complex, in large part due to the continual problem of continuity faced by the major two publishers, Marvel Comics and DC Comics. The two publishers have used the multiverse concept to fix problems arising from integrating characters from other publishers into their own canon, and from having major serial protagonists having continuous histories lasting, as in the case of Superman, up to 60 years. Additionally, both publishers have used new alternate universes to re-imagine their own characters. (See Multiverse (DC Comics) and Multiverse (Marvel Comics))

Games

The Dungeons & Dragons role-playing game has a thoroughly developed system of planes of existence. A popular campaign setting for the game, Planescape, centres around travelling between these planes. Ravenloft, a gothic horror setting for Dungeons & Dragons, is based entirely in a single demiplane.

In the Magic: The Gathering trading card game, every plane is part of a multiverse. What effects one plane, may ultimately affect others, such as what happened when a great devastation occurred on the main plane, Dominaria. All the planes around were locked in a bubble, called the Shard, where no one could get in or out.

In the computer game Myst a people known as D'ni colonized Earth from another universe, and kept traveling to other universes (known as Ages) through Books. According to their cosmology, each universe is a leaf of the Terokh Jeruth, the Tree of Possibilities.

The Kingdom Hearts series also implements the idea of multiple worlds, ranging from the Destiny Islands to Halloween Town (from The Nightmare Before Christmas) to Port Royal (from Pirates of the Caribbean: The Curse of the Black Pearl).

The Squaresoft game Chrono Cross involves the world being split into two different dimensions, due to an accident involving the fate of a boy named Serge.

List of fiction employing parallel universes/alternate realities

Books

• H. Beam Piper, the author of the Paratime series, wrote several stories dealing with alternate realities based on points of divergence far in the past. The stories are usually written from the perspective of a law-enforcement outfit from a parallel reality which is charged to protect the secret of temporal transposition.

• Murray Leinster's story "Sidewise in Time" (1933), showing different parts of the Earth somehow occupied by different parallel universes, was influential in science fiction.

• Fredric Brown's "What Mad Universe" recounts the adventures of a science-fiction editor of the late 1940s who is thrown into a parallel universe that reflects the fantasies of his most annoying letter-to-the-editor writer (an adolescent male, naturally).

• Isaac Asimov's novel The Gods Themselves depicts scientists in our universe who find a way to "import" small amounts of matter from a universe having different physical laws, with unforeseen consequences.

• K.A. Applegate's series, Everworld.

• Margaret Cavendish, Duchess of Newcastle, wrote The Blazing World (1666), a book way ahead of its time, in which the heroine passes through a portal near the North Pole to a world with different stars in the sky and talking animals. Although Cavendish never came up with the idea of a multiverse, she did have the idea of a single alternate world down pat.

• Robert A. Heinlein's novel The Number of the Beast is focused around a 'time machine' that also proves to be able to travel sideways and other directions in time, allowing for crossing into other realities, even ones previously considered fictional by the protagonists.

• S. M. Stirling has written several series using the idea of alternate realities. The Domination of the Draka series features an aggressively expansionistic nation, based on a slave economy, that eventually takes over the world. The novel The Peshawar Lancers is an alternate history novel where western Europe and North America were devastated by meteorite strikes in the 19th century and the Brisith Empire, based from India, is the dominant world power in the 23rd century. The novel Conquistador is based on travel between parallel universes, with a group of 20th century Americans having found a means to secretly colonize a world where civilization never advanced past the classical era.

• Globus Cassus is a book describing a utopian project for a universe contrary to ours, it describes an antipode to the 'real' world.

• The Wheel of Time series features not only one cyclic universe, but many. All but one of these universes loses the Last Battle because the main protagonist, Rand al'Thor, dies.

• Michael Crichton delved into the possibility of travel between other realities in the multiverse in his novel Timeline.

• John DeChancie's Castle Perilous series tells of a huge magical castle containing portals to 144,000 worlds, including Earth.

• Stephen R. Donaldson's Mordant's Need series, which includes The Mirror of Her Dreams and A Man Rides Through, follows a heroine who can pass into another world through mirrors.

• H.G. Wells wrote what is apparently the first explicit paratime novel, Men Like Gods (1923), complete with a multiverse theory and a paratime machine.

• C.S. Lewis' classic Chronicles of Narnia series tells the story of four children who stumble into a world enslaved by the White Witch.

• Phillip Pullman's His Dark Materials series deals with two children who wander through multiple worlds together

Television

• Sliders dealt with a group of mostly-unwilling travellers who ended up "sliding" between various parallel Earths in an attempt to find their way back to their own universe. Plots included an Earth in which the population is controlled through a lottery, an Earth where most of the males were killed by germ warfare, an Earth where dinosaurs are still alive, and an Earth in which the population have been turned into flesh-eating zombies. According to a main character Quinn, there were an infinate number of universes where different single decisions were different and even a world where the Earth formed differently and rotated around the Sun slower, slowing down that timeline.

• Star Trek featured the recurring mirror universe, a dark reflection of the normal universe in which the regular characters are twisted, self-serving and more than willing to resort to murder. The mirror universe was introduced in the original Star Trek, and it also appeared in Enterprise, but was mainly featured in Deep Space Nine.

• The Doctor Who serial Inferno features the Doctor travelling to a parallel universe. There, the Doctor finds his friend the Brigadier is part of a despotic government that violently overthrew the monarchy. The episode Rise of the Cybermen involves the TARDIS getting stuck in a parallel London in which a dying genius has created the emotionless Cybermen as a means of prolonging human life.

• Joss Whedon's cult television series, Buffy the Vampire Slayer and Angel, have featured a number of parallel universes — including a world in which most of the regular cast were either dead or vampires, as well as the often-mentioned but never-seen World Without Shrimp — bridging the gap with magic.

• The anime Digimon features an alternative perceived reality called the Digital World. The Digital World is created as a result of the Earth's electronic network, with everything being made up of data instead of matter. Also, certain seasons, games, and manga are set in a different parallel Earth, with its own version of a Digital World.

• The television series Code Lyoko in which the main characters travel to an alternate universe called Lyoko to help a virtual friend. In another episode, it is revealed there is another alternate universe to the Lyoko universe created by the villain.

• The show Stargate SG1 has had several episodes dealing with parallel universes. The first had Daniel Jackson finding a mirror looking device, known as the Quantum Mirror, where by touching the "mirror" he was taken to an a parallel universe in which things hadn't gone so well compared to his reality. Another Episode has a Samantha Carter and a character killed off in the second episode of the show come through the mirror to request help from the shows normal reality. With the end of that show the Quantum Mirror was destroyed. The latest episode, "Ripple Effect," dealing with alternate realities has a lot of different SG1 teams coming through the same Gate.

Movies

• One of the main characters from The One transports between parallel universes and kills his counterparts.

• C.S.A.: The Confederate States of America (2004) - A satirically humorous and, sometimes, disturbing look at the history of an America where the South won the Civil War, told in the form of a British "documentary."

• Fatherland (1994) - Set in the 1960's in a world where Germany won WW II and occupied Britain, the story is that of an American journalist and a German SS homicide cop who stumble onto a plot to destroy all evidence of the genocide the Nazis practiced during the war.

Comics

• The main character in François Schuiten and Benoît Peeters' comic book L'enfant penchée lives on our Earth, but comes from a parallel universe. She is attached to this other universe's gravitational pull and therefore stands inclined.

• The Caste of the Metabarons comics by Alejandro Jodorowsky features two wars between our universe and alternate ones.

• In Zenith: Phase Three, superheroes from many parallels must band together to defend their worlds.

• The British comic book series The Adventures of Luther Arkwright is based around the concept of parallel universes.

• Alternate universes are often used as an explanation for crossovers between different companies' characters.

Games

• The video game Metroid Prime 2: Echoes features the planet Aether, which is struck by a meteor. The strange, energetic substance (called Phazon) within the meteor, along with the force of the impact, split the planet's reality into light and dark dimensions. Samus, the heroine, must travel between the two dimensions, transferring energy back to the light dimension before the two competing worlds destroy one another.

• At one point in the video game Crash Twinsanity, the main protagonists (Crash Bandicoot and Doctor Neo Cortex) travel to the mysterious 10th Dimension, where everything that is good in their dimension is evil, and vice versa.

• In the videogame Chrono Cross (2001), the main character must travel between two dimensions, known as "Home World" (the world from which the main character originates) and "Another World".

• In the video game Star Ocean: Till the End of Time the characters live in a "video game" unknowingly created by people in another universe called 4D Space. The "video game" world later becomes its own universe parallel to 4D Space.

• In the Spyro the Dragon series, an evil sorcerer sends all of the inhabitants of the three realms to their Shadow Realm counterparts, leaving the normal realms empty save for Spyro.

   

References

• Clifford A. Pickover (August, 2005). Sex, Drugs, Einstein, and Elves: Sushi, Psychedelics, Parallel Universes, and the Quest for Transcendence (Discusses parallel universes in a variety of settings, from physics to psychedelic visions to Proust parallel worlds to Bonnet syndrome). Smart Publications. ISBN 1890572179.

• Michio Kaku (2004). Parallel Worlds: A Journey Through Creation, Higher Dimensions, and the Future of the Cosmos. Doubleday. ISBN 0385509863.