Parallel universe (fiction)
Overview
A parallel universe or alternative reality is a hypothetical self-contained separate reality
Reality
In philosophy, reality is the state of things as they actually exist, rather than as they may appear or might be imagined. In a wider definition, reality includes everything that is and has been, whether or not it is observable or comprehensible...

 coexisting with one's own. A specific group of parallel universes is called a "multiverse
Multiverse
The multiverse is the hypothetical set of multiple possible universes that together comprise all of reality.Multiverse may also refer to:-In fiction:* Multiverse , the fictional multiverse used by DC Comics...

", although this term can also be used to describe the possible parallel universes that constitute reality. While the terms "parallel universe" and "alternative reality" are generally synonym
Synonym
Synonyms are different words with almost identical or similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn and onoma . The words car and automobile are synonyms...

ous and can be used interchangeably in most cases, there is sometimes an additional connotation implied with the term "alternative reality" that implies that the reality is a variant of our own.
Encyclopedia
A parallel universe or alternative reality is a hypothetical self-contained separate reality
Reality
In philosophy, reality is the state of things as they actually exist, rather than as they may appear or might be imagined. In a wider definition, reality includes everything that is and has been, whether or not it is observable or comprehensible...

 coexisting with one's own. A specific group of parallel universes is called a "multiverse
Multiverse
The multiverse is the hypothetical set of multiple possible universes that together comprise all of reality.Multiverse may also refer to:-In fiction:* Multiverse , the fictional multiverse used by DC Comics...

", although this term can also be used to describe the possible parallel universes that constitute reality. While the terms "parallel universe" and "alternative reality" are generally synonym
Synonym
Synonyms are different words with almost identical or similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn and onoma . The words car and automobile are synonyms...

ous and can be used interchangeably in most cases, there is sometimes an additional connotation implied with the term "alternative reality" that implies that the reality is a variant of our own. The term "parallel universe" is more general, without any connotations implying a relationship, or lack of relationship, with our own universe. A universe where the very laws of nature
Physical law
A physical law or scientific law is "a theoretical principle deduced from particular facts, applicable to a defined group or class of phenomena, and expressible by the statement that a particular phenomenon always occurs if certain conditions be present." Physical laws are typically conclusions...

 are different – for example, one in which there are no relativistic
Theory of relativity
The theory of relativity, or simply relativity, encompasses two theories of Albert Einstein: special relativity and general relativity. However, the word relativity is sometimes used in reference to Galilean invariance....

 limitations and the speed of light
Speed of light
The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...

 can be exceeded – would in general count as a parallel universe but not an alternative reality.
The correct quantum mechanical
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...

 definition of parallel universes is "universes that are separated from each other by a single quantum event."

Introduction

Fantasy has long borrowed the idea of "another world" from myth
Mythology
The term mythology can refer either to the study of myths, or to a body or collection of myths. As examples, comparative mythology is the study of connections between myths from different cultures, whereas Greek mythology is the body of myths from ancient Greece...

, legend
Legend
A legend is a narrative of human actions that are perceived both by teller and listeners to take place within human history and to possess certain qualities that give the tale verisimilitude...

 and religion
Religion
Religion is a collection of cultural systems, belief systems, and worldviews that establishes symbols that relate humanity to spirituality and, sometimes, to moral values. Many religions have narratives, symbols, traditions and sacred histories that are intended to give meaning to life or to...

. Heaven
Heaven
Heaven, the Heavens or Seven Heavens, is a common religious cosmological or metaphysical term for the physical or transcendent place from which heavenly beings originate, are enthroned or inhabit...

, Hell
Hell
In many religious traditions, a hell is a place of suffering and punishment in the afterlife. Religions with a linear divine history often depict hells as endless. Religions with a cyclic history often depict a hell as an intermediary period between incarnations...

, Olympus
Twelve Olympians
The Twelve Olympians, also known as the Dodekatheon , in Greek mythology, were the principal deities of the Greek pantheon, residing atop Mount Olympus. Zeus, Hera, Poseidon, Demeter, Hestia, and Hades were siblings. Ares, Hermes, Hephaestus, Athena, Apollo, and Artemis were children of Zeus...

, Valhalla
Valhalla
In Norse mythology, Valhalla is a majestic, enormous hall located in Asgard, ruled over by the god Odin. Chosen by Odin, half of those that die in combat travel to Valhalla upon death, led by valkyries, while the other half go to the goddess Freyja's field Fólkvangr...

 are all “alternative universes” different from the familiar material realm. Modern fantasy
Fantasy
Fantasy is a genre of fiction that commonly uses magic and other supernatural phenomena as a primary element of plot, theme, or setting. Many works within the genre take place in imaginary worlds where magic is common...

 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. This concept was also found in ancient Hindu mythology
Hindu mythology
Hindu religious literature is the large body of traditional narratives related to Hinduism, notably as contained in Sanskrit literature, such as the Sanskrit epics and the Puranas. As such, it is a subset of Nepali and Indian culture...

, in texts such as the Puranas
Puranas
The Puranas are a genre of important Hindu, Jain and Buddhist religious texts, notably consisting of narratives of the history of the universe from creation to destruction, genealogies of kings, heroes, sages, and demigods, and descriptions of Hindu cosmology, philosophy, and geography.Puranas...

, which expressed an infinite number of universes, each with its own gods. Similarly in Persian literature
Persian literature
Persian literature spans two-and-a-half millennia, though much of the pre-Islamic material has been lost. Its sources have been within historical Persia including present-day Iran as well as regions of Central Asia where the Persian language has historically been the national language...

, "The Adventures of Bulukiya", a tale in the One Thousand and One Nights, describes the protagonist Bulukiya learning of alternative worlds/universes that are similar to but still distinct from his own. 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
The Chronicles of Narnia
The Chronicles of Narnia is a series of seven fantasy novels for children by C. S. Lewis. It is considered a classic of children's literature and is the author's best-known work, having sold over 100 million copies in 47 languages...

by C. S. Lewis
C. S. Lewis
Clive Staples Lewis , commonly referred to as C. S. Lewis and known to his friends and family as "Jack", was a novelist, academic, medievalist, literary critic, essayist, lay theologian and Christian apologist from Belfast, Ireland...

 or even the beyond-the-reflection travel in the two main works of Lewis Carroll
Lewis Carroll
Charles Lutwidge Dodgson , better known by the pseudonym Lewis Carroll , was an English author, mathematician, logician, Anglican deacon and photographer. His most famous writings are Alice's Adventures in Wonderland and its sequel Through the Looking-Glass, as well as the poems "The Hunting of the...

. Or this single other reality can invade our own, as when Margaret Cavendish
Margaret Cavendish
Margaret Cavendish, Duchess of Newcastle-upon-Tyne was an English aristocrat, a prolific writer, and a scientist. Born Margaret Lucas, she was the youngest sister of prominent royalists Sir John Lucas and Sir Charles Lucas...

's English heroine sends submarines and "birdmen" armed with "fire stones" back through the portal from The Blazing World
The Blazing World
The Description of a New World, Called The Blazing-World, better known as The Blazing World, is a 1666 work of prose fiction by English writer Margaret Cavendish, the Duchess of Newcastle....

to Earth and wreaks havoc on England's enemies. In dark fantasy
Dark fantasy
Dark fantasy is a term used to describe a fantasy story with a pronounced horror element.-Overview:A strict definition for dark fantasy is difficult to pin down. Gertrude Barrows Bennett has been called "the woman who invented dark fantasy". Both Charles L...

 or horror
Horror fiction
Horror fiction also Horror fantasy is a philosophy of literature, which is intended to, or has the capacity to frighten its readers, inducing feelings of horror and terror. It creates an eerie atmosphere. Horror can be either supernatural or non-supernatural...

 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
H. P. Lovecraft
Howard Phillips Lovecraft --often credited as H.P. Lovecraft — was an American author of horror, fantasy and science fiction, especially the subgenre known as weird fiction....

 and the Doom computer game series, or Warhammer/40K miniature and computer games. In such stories, the nature of this other reality is often left mysterious, known only by its effect on our own world.

The concept also arises outside the framework of quantum mechanics, as is found in Jorge Luis Borges
Jorge Luis Borges
Jorge Francisco Isidoro Luis Borges Acevedo , known as Jorge Luis Borges , was an Argentine writer, essayist, poet and translator born in Buenos Aires. In 1914 his family moved to Switzerland where he attended school, receiving his baccalauréat from the Collège de Genève in 1918. The family...

 short story El jardín de senderos que se bifurcan ("The Garden of Forking Paths
The Garden of Forking Paths
"The Garden of Forking Paths" is a 1941 short story by Argentine writer and poet Jorge Luis Borges. It is the title story in the collection El jardín de senderos que se bifurcan , which was republished in its entirety in Ficciones in 1944...

"), published in 1941 before the many-worlds interpretation had been invented. In the story, a Sinologist
Sinology
Sinology in general use is the study of China and things related to China, but, especially in the American academic context, refers more strictly to the study of classical language and literature, and the philological approach...

 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. One of the first Sci-Fi examples is John Wyndham
John Wyndham
John Wyndham Parkes Lucas Beynon Harris was an English science fiction writer who usually used the pen name John Wyndham, although he also used other combinations of his names, such as John Beynon and Lucas Parkes...

's Random Quest
Random Quest
Random Quest is a science fiction short story, which is also a love story, by John Wyndham. It was included in his 1961 collection Consider Her Ways and Others...

 about a man who, on awaking after a laboratory accident, finds himself in a parallel universe where World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 never happened with consequences for his professional and personal life, giving him information he can use on return to his own universe.

While this is a common treatment in Sci-Fi, it is by no means the only presentation of the idea, even in hard science fiction
Hard science fiction
Hard science fiction is a category of science fiction characterized by an emphasis on scientific or technical detail, or on scientific accuracy, or on both. The term was first used in print in 1957 by P. Schuyler Miller in a review of John W. Campbell, Jr.'s Islands of Space in Astounding Science...

. Sometimes the parallel universe bears no historical relationship to any other world; instead, the laws of nature are simply different than those in our own, as in the novel Raft
Raft (novel)
Raft is a 1991 hard science fiction book by author Stephen Baxter. Raft is both Baxter's first novel and first book in the Xeelee Sequence, although the Xeelee are not present. Raft was nominated for the Arthur C. Clarke Award in 1992.-Setting:...

by Stephen Baxter
Stephen Baxter
Stephen Baxter is a prolific British hard science fiction author. He has degrees in mathematics and engineering.- Writing style :...

, which posits a reality where the gravitational constant
Gravitational constant
The gravitational constant, denoted G, is an empirical physical constant involved in the calculation of the gravitational attraction between objects with mass. It appears in Newton's law of universal gravitation and in Einstein's theory of general relativity. It is also known as the universal...

 is much larger than in our universe. (Note, however, that Baxter explains later in Vacuum Diagrams
Vacuum Diagrams
Vacuum Diagrams is a collection of science fiction short stories written by Stephen Baxter. The collection connects the novels of the Xeelee Sequence and also shows the history of mankind in the Xeelee universe, and ultimately the universe...

that the protagonists in Raft are descended from people who came from the Xeelee Sequence
Xeelee Sequence
The Xeelee Sequence is a series of novels and short stories by British science fiction author Stephen Baxter. The novels span several billions of years, describing the future expansion of Mankind, its war with its arch-nemesis , and the Xeelee's own war with dark matter entities called photino birds...

 universe.)

One motif is that the way time flows in a parallel universe may be very different, so that a character returning to one might find the time passed very differently for those he left behind. This is found in folklore: King Herla visited Fairy and returned three centuries later; although only some of his men crumbled to dust on dismounting, Herla and his men who did not dismount were trapped on horseback, this being one folkloric account of the origin of the Wild Hunt
Wild Hunt
The Wild Hunt is an ancient folk myth prevalent across Northern, Western and Central Europe. The fundamental premise in all instances is the same: a phantasmal, spectral group of huntsmen with the accoutrements of hunting, horses, hounds, etc., in mad pursuit across the skies or along the ground,...

. C. S. Lewis
C. S. Lewis
Clive Staples Lewis , commonly referred to as C. S. Lewis and known to his friends and family as "Jack", was a novelist, academic, medievalist, literary critic, essayist, lay theologian and Christian apologist from Belfast, Ireland...

 made use of this in the Chronicles of Narnia; indeed, a character points out to two skeptics that there is no need for the time between the worlds to match up, but it would be very odd for the girl who claims to have visited a parallel universe to have dreamed up such a different time flow.

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
Sliders
Sliders is an American science fiction television series. It was broadcast for five seasons, beginning in 1995 and ending in 2000. The series follows a group of travelers as they use a wormhole to "slide" between different parallel universes. The show was created by Robert K. Weiss and Tracy Tormé...

is clearly science fiction, but works like the World of Tiers
World of Tiers
The World of Tiers is a series of science fiction novels by American writer Philip José Farmer. They are set within a series of artificially-constructed universes, created and ruled by decadent beings who are genetically identical to humans, but who regard themselves as superior, the inheritors of...

series or Glory Road
Glory Road
Glory Road is a fantasy novel by Robert A. Heinlein, originally serialized in The Magazine of Fantasy & Science Fiction and published in hardcover later the same year...

tend to occupy a much broader middle ground.

Parallel universes are considered parallel because there is no way of reaching them. All other dimensions are not parallel, but more than likely most of them are. An Einstein Rosen bridge, or Wormhole, can take you to a different dimension. Note that the journey through space-time continuum could backwards age you, or wipe you from existence. More than likely, if you managed to get to the alternate dimension, then you would have no memory of how you got there. The dangers of time-space travel are still being investigated, and possibilities are growing.

Typically, parallel universes fall into two classifications. The first may be more accurately called a "diverging universe" whereby two versions of Earth share a common history up to a point of divergence
Point of divergence
In discussion of counterfactual history, a divergence point , also referred to as a departure point or point of divergence , is a historical event with two possible postulated outcomes...

. At this point, the outcome of some even happens differently on the two Earths and the histories continue to become more different as time elapses since that point. (E.g. Parallels (Star Trek: The Next Generation). The second type is where despite certain, often large, difference between the two Earths history and/or culture, they maintain strong similarities. In such cases, it is common that every person in one universe will have a counterpart in the other universe with the same name, ancestry, appearance, and frequently occupation but often a very different personality. (e.g. Mirror, Mirror (Star Trek: The Original Series).

Science fiction

While technically incorrect, and looked down upon by hard science-fiction fans and authors, the idea of another “dimension
Dimension
In physics and mathematics, the dimension of a space or object is informally defined as the minimum number of coordinates needed to specify any point within it. Thus a line has a dimension of one because only one coordinate is needed to specify a point on it...

” 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. The idea of a parallel world was first introduced in comic books with the publication of Flash #123 - "Flash of Two Worlds".

In written science fiction, “new dimensions” more commonly — and more accurately — refer to additional coordinate axes, beyond the three spatial axes with which we are familiar. By proposing travel along these extra axes, which are not normally perceptible, the traveler can reach worlds that are otherwise unreachable and invisible.
In 1884, Edwin A. Abbott wrote the seminal novel exploring this concept called Flatland: A Romance of Many Dimensions
Flatland
Flatland: A Romance of Many Dimensions is an 1884 satirical novella by the English schoolmaster Edwin Abbott Abbott. Writing pseudonymously as "A Square", Abbott used the fictional two-dimensional world of Flatland to offer pointed observations on the social hierarchy of Victorian culture...

. It describes a world of two dimensions inhabited by living squares, triangles, and circles, called Flatland, as well as Pointland (0 dimensions), Lineland (1 dimension), and Spaceland (three dimensions) and finally posits the possibilities of even greater dimensions. Isaac Asimov, in his foreword to the Signet Classics 1984 edition, described Flatland
Flatland
Flatland: A Romance of Many Dimensions is an 1884 satirical novella by the English schoolmaster Edwin Abbott Abbott. Writing pseudonymously as "A Square", Abbott used the fictional two-dimensional world of Flatland to offer pointed observations on the social hierarchy of Victorian culture...

 as "The best introduction one can find into the manner of perceiving dimensions."

In 1895, The Time Machine
The Time Machine
The Time Machine is a science fiction novella by H. G. Wells, published in 1895 for the first time and later adapted into at least two feature films of the same name, as well as two television versions, and a large number of comic book adaptations. It indirectly inspired many more works of fiction...

by H. G. Wells
H. G. Wells
Herbert George Wells was an English author, now best known for his work in the science fiction genre. He was also a prolific writer in many other genres, including contemporary novels, history, politics and social commentary, even writing text books and rules for war games...

 used time as an additional “dimension” in this sense, taking the four-dimensional
Spacetime
In physics, spacetime is any mathematical model that combines space and time into a single continuum. Spacetime is usually interpreted with space as being three-dimensional and time playing the role of a fourth dimension that is of a different sort from the spatial dimensions...

 model of classical physics
Classical physics
What "classical physics" refers to depends on the context. When discussing special relativity, it refers to the Newtonian physics which preceded relativity, i.e. the branches of physics based on principles developed before the rise of relativity and quantum mechanics...

 and interpreting time as a space-like dimension in which humans could travel with the right equipment. Wells also used the concept of parallel universes as a consequence of time as the fourth dimension in stories like The Wonderful Visit
The Wonderful Visit
The Wonderful Visit is an 1895 novel written by H. G. Wells. It tells the story of a fallen angel who one night arrives in a small English village called Sidderton, where he faces the struggles of adapting to everyday life, and has to deal with the problem that his pureness and wholesomeness makes...

 and Men Like Gods
Men Like Gods
Men Like Gods is a novel written in 1923 by H. G. Wells. It features a utopian parallel universe.-Plot summary :The hero of the novel, Mr. Barnstaple, is a depressive journalist working for a newspaper called the Liberal. At the beginning of the story, Barnstaple, as well as a few other...

, an idea proposed by the astronomer Simon Newcomb
Simon Newcomb
Simon Newcomb was a Canadian-American astronomer and mathematician. Though he had little conventional schooling, he made important contributions to timekeeping as well as writing on economics and statistics and authoring a science fiction novel.-Early life:Simon Newcomb was born in the town of...

, who talked about both time and parallel universes; "Add a fourth dimension to space, and there is room for an indefinite number of universes, all alongside of each other, as there is for an indefinite number of sheets of paper when we pile them upon each other".

There are many examples where authors have explicitly created additional spatial dimensions for their characters to travel in, to reach parallel universes. In Doctor Who
Doctor Who
Doctor Who is a British science fiction television programme produced by the BBC. The programme depicts the adventures of a time-travelling humanoid alien known as the Doctor who explores the universe in a sentient time machine called the TARDIS that flies through time and space, whose exterior...

, the Doctor accidentally enters a parallel universe while attempting to repair the TARDIS
TARDIS
The TARDISGenerally, TARDIS is written in all upper case letters—this convention was popularised by the Target novelisations of the 1970s...

 console in Inferno
Inferno (Doctor Who)
Don Houghton came to Terrence Dicks with an idea for the story based on the real life Project Mohole. A smaller budget for the serial drove the idea of a parallel world, where the studio could use the same actors in multiple roles...

. The parallel universe was similar to the real universe but with some different aspects. Douglas Adams
Douglas Adams
Douglas Noel Adams was an English writer and dramatist. He is best known as the author of The Hitchhiker's Guide to the Galaxy, which started life in 1978 as a BBC radio comedy before developing into a "trilogy" of five books that sold over 15 million copies in his lifetime, a television...

, in the last book of the Hitchhiker's Guide to the Galaxy
The Hitchhiker's Guide to the Galaxy
The Hitchhiker's Guide to the Galaxy is a science fiction comedy series created by Douglas Adams. Originally a radio comedy broadcast on BBC Radio 4 in 1978, it was later adapted to other formats, and over several years it gradually became an international multi-media phenomenon...

series, Mostly Harmless
Mostly Harmless
Mostly Harmless is a novel by Douglas Adams and the fifth book in the Hitchhiker's Guide to the Galaxy series. It is described on the cover of the first editions as "The fifth book in the increasingly inaccurately named Hitchhikers Trilogy"...

, uses the idea of probability
Probability
Probability is ordinarily used to describe an attitude of mind towards some proposition of whose truth we arenot certain. The proposition of interest is usually of the form "Will a specific event occur?" The attitude of mind is of the form "How certain are we that the event will occur?" The...

 as an extra axis in addition to the classical four dimensions of space and time similar to the many-worlds interpretation
Many-worlds interpretation
The many-worlds interpretation is an interpretation of quantum mechanics that asserts the objective reality of the universal wavefunction, but denies the actuality of wavefunction collapse. Many-worlds implies that all possible alternative histories and futures are real, each representing an...

 of quantum physics. 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
Robert A. Heinlein
Robert Anson Heinlein was an American science fiction writer. Often called the "dean of science fiction writers", he was one of the most influential and controversial authors of the genre. He set a standard for science and engineering plausibility and helped to raise the genre's standards of...

, in The Number of the Beast
The Number of the Beast (novel)
The Number of the Beast is a science fiction novel by Robert A. Heinlein published in 1980. The first edition featured a cover and interior illustrations by Richard M. Powers...

, postulated a six-dimensional universe. In addition to the three spatial dimensions, he invoked symmetry
Symmetry
Symmetry generally conveys two primary meanings. The first is an imprecise sense of harmonious or aesthetically pleasing proportionality and balance; such that it reflects beauty or perfection...

 to add two new temporal dimensions, so there would be two sets of three. Like the fourth dimension of H. G. Wells’ "Time Traveller", 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
Faster-than-light
Faster-than-light communications and travel refer to the propagation of information or matter faster than the speed of light....

 shortcut for interstellar travel
Interstellar travel
Interstellar space travel is manned or unmanned travel between stars. The concept of interstellar travel in starships is a staple of science fiction. Interstellar travel is much more difficult than interplanetary travel. Intergalactic travel, or travel between different galaxies, is even more...

. 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 travellers.
  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
Wormhole
In physics, a wormhole is a hypothetical topological feature of spacetime that would be, fundamentally, a "shortcut" through spacetime. For a simple visual explanation of a wormhole, consider spacetime visualized as a two-dimensional surface. If this surface is folded along a third dimension, it...

.)

Hyperspace may also refer to the entry and exit of subspace, an unproven area of the universe that lies below our own time-space and allows speeds exceeding light speed (not to be confused with faster-than-light travel).

While use of hyperspace is common, it is mostly used as a plot device
Plot device
A plot device is an object or character in a story whose sole purpose is to advance the plot of the story, or alternatively to overcome some difficulty in the plot....

 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
Time travel
Time travel is the concept of moving between different points in time in a manner analogous to moving between different points in space. Time travel could hypothetically involve moving backward in time to a moment earlier than the starting point, or forward to the future of that point without the...

. A seminal example of this idea is in Fritz Leiber
Fritz Leiber
Fritz Reuter Leiber, Jr. was an American writer of fantasy, horror and science fiction. He was also a poet, actor in theatre and films, playwright, expert chess player and a champion fencer. Possibly his greatest chess accomplishment was winning clear first in the 1958 Santa Monica Open.. With...

’s novel, The Big Time
The Big Time
The Big Time is a short science fiction novel by Fritz Leiber. It won the Hugo Award in 1958.The Big Time is a vast, cosmic back story, hidden behind a claustrophobic front story with only a few characters.-Plot:...

where there’s a war across time between two alternate future
Alternate future
In science fiction stories involving time travel, an alternative future or alternate future is a possible future which never comes to pass, typically because someone travels back into the past and alters it so that the events of the alternative future cannot occur.An alternative future differs from...

s 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
The Guns of the South
The Guns of the South is an alternate history novel set during the American Civil War by Harry Turtledove.The story deals with a group of time-travelling Afrikaner Weerstandsbeweging members who supply Robert E...

by Harry Turtledove
Harry Turtledove
Harry Norman Turtledove is an American novelist, who has produced works in several genres including alternate history, historical fiction, fantasy and science fiction.- Life :...

 where the Confederate Army is given the technology to produce AK-47
AK-47
The AK-47 is a selective-fire, gas-operated 7.62×39mm assault rifle, first developed in the Soviet Union by Mikhail Kalashnikov. It is officially known as Avtomat Kalashnikova . It is also known as a Kalashnikov, an "AK", or in Russian slang, Kalash.Design work on the AK-47 began in the last year...

 rifles and ends up winning the American Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

. (However, Ward Moore
Ward Moore
Ward Moore was the working name of American author Joseph Ward Moore. Moore grew up in New York City, and later moved to Chicago, and then to California....

 reversed this staple of alternate history fiction in his Bring the Jubilee
Bring the Jubilee
Bring the Jubilee by Ward Moore is a 1953 novel of alternate history. The point of divergence occurs when the Confederate States of America wins the Battle of Gettysburg and subsequently declares victory in the "War of Southron Independence" on July 4, 1864 after the surrender of the United States...

(1953), where an alternative world where the Confederate States of America
Confederate States of America
The Confederate States of America was a government set up from 1861 to 1865 by 11 Southern slave states of the United States of America that had declared their secession from the U.S...

 won the Battle of Gettysburg
Battle of Gettysburg
The Battle of Gettysburg , was fought July 1–3, 1863, in and around the town of Gettysburg, Pennsylvania. The battle with the largest number of casualties in the American Civil War, it is often described as the war's turning point. Union Maj. Gen. George Gordon Meade's Army of the Potomac...

 and the American Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

 is destroyed after a historian and time traveller from the defeated United States of that world travels back to the scene of the battle and inadvertently changes the result so that the North wins that battle.) The alternate history novel 1632
1632 (novel)
1632 is the initial novel in the best-selling alternate history 1632 book series written by historian, writer and editor Eric Flint. The flagship novel kicked off a collaborative writing effort that has involved hundreds of contributors and dozens of authors...

by Eric Flint
Eric Flint
Eric Flint is an American author, editor, and e-publisher. The majority of his main works are alternate history science fiction, but he also writes humorous fantasy adventures.- Career :...

 explicitly states, albeit briefly in a prologue, that the time travelers in the novel (an entire town from West Virginia
West Virginia
West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...

) have created a new and separate universe when they're transported into the midst of the Thirty Years War in 17th century Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

. (This sort of thing is known as an ISOT among alternate history fans, after S.M. Stirling's Island in the Sea of Time
Island in the Sea of Time
Island in the Sea of Time is the first of the three alternate history novels of the Nantucket series by S. M. Stirling.-Plot summary:An elliptical region, including the island of Nantucket, Massachusetts and the United States Coast Guard ship Eagle, is transported by an unknown phenomenon back in...

: an ISOT is when territory or a large group of people is transported back in time to another historical period or place.

Typically, alternate histories are not technically parallel universes. Though the concepts are similar, there are significant differences. In cases where characters travel to the past, they may cause changes in the timeline (creating a point of divergence) that result in changes to the present. The alternate present will be similar in different degrees to the original present as would be the case with a parallel universe. The main difference is that parallel universes co-exist whereas only one history or alternate history can exist at any one moment. Another difference is that travelling to a parallel universe involves some type of inter-dimensional travel whereas alternative histories involve some type of time travel. (However, since the future is only potential and not actual, it is often conceived that more than one future may exist simultaneously.)

The concept of "sidewise" time travel, a term taken from Murray Leinster's "Sidewise in Time
Sidewise in Time
"Sidewise in Time" is a science fiction short story by Murray Leinster that was first published in the June 1934 issue of Astounding Stories...

", 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 sidewise travel. For example, a universe where World War II ended differently would be “closer” to us than one where Imperial China colonized the New World in the 15th century. H. Beam Piper
H. Beam Piper
Henry Beam Piper was an American science fiction author. He wrote many short stories and several novels. He is best known for his extensive Terro-Human Future History series of stories and a shorter series of "Paratime" alternate history tales.He wrote under the name H. Beam Piper...

 used this concept, naming it "paratime" and writing a series of stories involving the Paratime Police who regulated travel between these alternative realities as well as the technology to do so. Keith Laumer
Keith Laumer
John Keith Laumer was an American science fiction author. Prior to becoming a full-time writer, he was an officer in the United States Air Force and a U.S. diplomat...

 used the same concept of "sideways" time travel in his 1962 novel Worlds of the Imperium
Worlds of the Imperium
Worlds of the Imperium is a science-fiction novel by Keith Laumer. It was originally published in 1962. It is an example of an alternate history novel in which a man from our reality becomes involved with another parallel world in which the American Revolution never happened and the secret of...

. More recently, novels such as Frederik Pohl
Frederik Pohl
Frederik George Pohl, Jr. is an American science fiction writer, editor and fan, with a career spanning over seventy years — from his first published work, "Elegy to a Dead Planet: Luna" , to his most recent novel, All the Lives He Led .He won the National Book Award in 1980 for his novel Jem...

's The Coming of the Quantum Cats
The Coming of the Quantum Cats
The Coming of the Quantum Cats is a 1986 science fiction novel by American writer Frederik Pohl. It was originally serialized in Analog science-fiction magazine, January–April 1986.- Plot introduction :...

and Neal Stephenson
Neal Stephenson
Neal Town Stephenson is an American writer known for his works of speculative fiction.Difficult to categorize, his novels have been variously referred to as science fiction, historical fiction, cyberpunk, and postcyberpunk...

's Anathem
Anathem
Anathem is a speculative fiction novel by Neal Stephenson, published in 2008. Major themes include the many-worlds interpretation of quantum mechanics and the philosophical debate between Platonic realism and formalism.-Plot summary:...

explore human-scale readings of the "many worlds" interpretation of quantum mechanics, postulating that historical events or human consciousness spawns or allows "travel" among alternate universes.

Frequent 'types' of universe explored in sidewise and alternative history works include worlds in which the Nazis won the Second World War, such as in The Man in the High Castle
The Man in the High Castle
The Man in the High Castle is a science fiction alternate history novel by American writer Philip K. Dick. It won a Hugo Award in 1963 and has since been translated into many languages....

by Philip K. Dick
Philip K. Dick
Philip Kindred Dick was an American novelist, short story writer and essayist whose published work is almost entirely in the science fiction genre. Dick explored sociological, political and metaphysical themes in novels dominated by monopolistic corporations, authoritarian governments and altered...

, SS-GB
SS-GB
SS-GB is an alternate history novel by Len Deighton, set in a United Kingdom fictionally conquered and occupied by Germany during World War II. The novel's title refers to the branch of the Nazi SS that controls Britain.-Plot summary:...

by Len Deighton
Len Deighton
Leonard Cyril Deighton is a British military historian, cookery writer, and novelist. He is perhaps most famous for his spy novel The IPCRESS File, which was made into a film starring Michael Caine....

 and Fatherland
Fatherland (novel)
Fatherland is a bestselling 1992 thriller by the English writer and journalist Robert Harris. It takes the form of a high concept alternative history set in a world in which Nazi Germany won World War II.The novel was an immediate bestseller in Britain...

by Robert Harris
Robert Harris (novelist)
Robert Dennis Harris is an English novelist. He is a former journalist and BBC television reporter.-Early life:Born in Nottingham, Harris spent his childhood in a small rented house on a Nottingham council estate. His ambition to become a writer arose at an early age, from visits to the local...

, and worlds in which the Roman Empire never fell, such as in Roma Eterna
Roma Eterna
Roma Eterna is a 2003 novel by Robert Silverberg which presents an alternate history in which the Roman Empire survives to the present day.-Plot introduction:...

by Robert Silverberg
Robert Silverberg
Robert Silverberg is an American author, best known for writing science fiction. He is a multiple nominee of the Hugo Award and a winner of the Nebula Award.-Early years:...

 and Romanitas
Romanitas (novel)
Romanitas is an alternate history novel by Sophia McDougall, published by Orion Books. It is the first of a planned trilogy of novels based on a world where the Roman Empire has survived to contemporary times and now dominates much of the world....

by Sophia McDougall
Sophia McDougall
Sophia McDougall is a British novelist, playwright, and poet.-Novelist:McDougall is best known internationally as the author of alternate history novels published by Orion Publishing Group and based on the premise that the Roman Empire survived to contemporary times.-Books:*Romanitas , Orion Books...

. In his novel Warlords of Utopia
Warlords of Utopia
Warlords of Utopia is an original novel by Lance Parkin set in the Faction Paradox universe. It has been described as 'possibly [Parkin's] finest accomplishment to date'....

, part of the loosely linked Faction Paradox
Faction Paradox
Faction Paradox is a fictional time travelling cult/rebel group/organized crime syndicate, originally created by the author Lawrence Miles. The Faction's belief-system as portrayed has some similarities to voodoo, and is sometimes described as such...

series, Lance Parkin
Lance Parkin
Lance Parkin is a British author, best known for writing fiction and reference books for television series, in particular Doctor Who and Emmerdale...

 explored a multiverse in which every universe in which Rome never fell goes to war with every universe in which the Nazis won WWII. The series was created by Lawrence Miles
Lawrence Miles
Lawrence Miles is a science fiction author known for his work on original Doctor Who novels and the subsequent spin-off Faction Paradox...

, whose earlier work Dead Romance
Dead Romance
Dead Romance is an original novel by Lawrence Miles, originally published as part of the Virgin New Adventures series. The New Adventures were a spin-off from the long-running British science fiction television series Doctor Who...

featured the concept of an artificially created universe existing within another -specifically, within a bottle - and explored the consequences of inhabitants of the 'real' universe entering the Universe-in-a-Bottle.

In the His Dark Materials
His Dark Materials
His Dark Materials is a trilogy of fantasy novels by Philip Pullman comprising Northern Lights , The Subtle Knife , and The Amber Spyglass...

trilogy, the universe the protagonist starts in is a Victorian counterpart to ours, although it takes place at the same time. It also appears that the Protestant Reformation
Protestant Reformation
The Protestant Reformation was a 16th-century split within Western Christianity initiated by Martin Luther, John Calvin and other early Protestants. The efforts of the self-described "reformers", who objected to the doctrines, rituals and ecclesiastical structure of the Roman Catholic Church, led...

 never happened.

In his short story, Rumfuddle, Jack Vance
Jack Vance
John Holbrook Vance is an American mystery, fantasy and science fiction author. Most of his work has been published under the name Jack Vance. Vance has published 11 mysteries as John Holbrook Vance and 3 as Ellery Queen...

 invents a doorway to an infinite number of universes at any given time, so that everyone on the planet can have their own private world. Some are inhabited by humans. On some, man doesn't exist. The trouble comes when some of the Rumfuddlers (a term given to an annual gathering to see who can best mess around with what should be) play pranks on parallel world, such as switching the infant Adolf Hitler with a baby from a Jewish couple, or putting together a football team made up of all of the great men in history.

Counter-Earth

The concept of Counter-Earth
Counter-Earth
The Counter-Earth is a hypothetical body of the Solar system first hypothesized by the presocratic philosopher Philolaus to support his non-geocentric cosmology, in which all objects in the universe revolve around a Central Fire...

 is typically similar to that of parallel universes but is actually a distinct idea. A counter-earth is a planet that shares Earth's orbit but is on the opposite side of the Sun and therefore cannot be seen from Earth. There would be no necessity that such a planet would be like Earth in any way though typically in fiction, it is usually nearly identical to Earth. Since counter-earth is always within our own universe (and our own solar system), travel to it can be accomplished with ordinary space travel.

See Counter-Earth
Counter-Earth
The Counter-Earth is a hypothetical body of the Solar system first hypothesized by the presocratic philosopher Philolaus to support his non-geocentric cosmology, in which all objects in the universe revolve around a Central Fire...

 for literary and film examples.

Convergent evolution

Convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...

 is a biological concept whereby unrelated species acquire similar traits because they adapted to a similar environment and/or played similar roles in their ecosystems. In fiction, the concept is extended whereby similar planets will result in races with similar cultures and/or histories.

Technically this is not a type of parallel universe since such planets can be reached via ordinary space travel, but the stories are similar in some respects.

In "Bread and Circuses (Star Trek: The Original Series)", the enterprise encounters a planet called Magna Roma which has many physical resemblances to Earth such as its atmosphere, land to ocean ratio, and size. The landing party discovers that the planet is at roughly a late 20th-century level of technology but its society is similar to the Roman Empire. It was as if the Roman Empire had not fallen but had continued to that time. There is also a reference to the Roman god Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...

. At the end of the episode, it is discovered that their own version Jesus
Jesus
Jesus of Nazareth , commonly referred to as Jesus Christ or simply as Jesus or Christ, is the central figure of Christianity...

, referred simply as "the son".

In The Omega Glory (Star Trek), the crew visit a planet on which there is a conflict between two peoples called the Yangs and the Kohms. They discover that the Yangs are like Earth's Yankees (i.e. Americans) and the Kohms are like Earth's communists. The Yangs had a constitution that was word for word identical to the American constitution but at some point in the past the Kohms had taken over.

In Miri (Star Trek: The Original Series), the Enterprise crew encounter a planet (later called Onlies) that is physically identical to Earth. History on the two planets were apparently identical until the 20th centuries when scientists on Onlies had accidentally created a deadly virus that killed all the adults but extended the lives of the children.

Convergent Evolution due to contamination

As similar concept in biology is gene flow
Gene flow
In population genetics, gene flow is the transfer of alleles of genes from one population to another.Migration into or out of a population may be responsible for a marked change in allele frequencies...

. In this case, a planet may start as different from Earth, but due to the influence of Earth culture, the planet come to resemble Earth in some way.

Technically this is not a type of parallel universe since such planets can be reached via ordinary space travel, but the stories are similar in some respects.

In Patterns of Force (Star Trek: The Original Series), a planet is discovered that has become very similar to Nazi Germany due to the influence of a professor that came to reside there. In A Piece of the Action (Star Trek: The Original Series), the Enterprise crew visits a planet that resembles mob ruled cities of Earth in the 1920's due to a book titled "Chicago Mobs of the Twenties" that had been left behind by previous Earth craft.

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. Peasants who seldom if ever traveled far from their villages could not conclusively say that it was impossible that an ogre
Ogre
An ogre is a large, cruel, monstrous, and hideous humanoid monster, featured in mythology, folklore, and fiction. Ogres are often depicted in fairy tales and folklore as feeding on human beings, and have appeared in many classic works of literature...

 or other fantastical beings could live an hour away, but increasing geographical knowledge meant that such locations had to be farther and farther off. Characters in the author's world could board a ship and find themselves on a fantastic island, as Jonathan Swift
Jonathan Swift
Jonathan Swift was an Irish satirist, essayist, political pamphleteer , poet and cleric who became Dean of St...

 does in Gulliver's Travels
Gulliver's Travels
Travels into Several Remote Nations of the World, in Four Parts. By Lemuel Gulliver, First a Surgeon, and then a Captain of Several Ships, better known simply as Gulliver's Travels , is a novel by Anglo-Irish writer and clergyman Jonathan Swift that is both a satire on human nature and a parody of...

or in the 1949 novel Silverlock
Silverlock
Silverlock is a novel by John Myers Myers published in 1949. The novel's settings and characters, aside from the protagonist, are all drawn from history, mythology, and other works of literature....

by John Myers Myers
John Myers Myers
John Myers Myers was an American writer, best known for his literary fantasy novel Silverlock.-Life:Myers was born in Northport, Long Island on January 11, 1906 to John Caldwell Myers and Alice MacCorry Myers and grew up in various places in New York, including New Paltz and NYC. He knew from the...

, or be sucked up into a tornado
Tornado
A tornado is a violent, dangerous, rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as a twister or a cyclone, although the word cyclone is used in meteorology in a wider...

 and land in Oz
Land of Oz
Oz is a fantasy region containing four lands under the rule of one monarch.It was first introduced in The Wonderful Wizard of Oz by L. Frank Baum, one of many fantasy countries that he created for his books. It achieved a popularity that none of his other works attained, and after four years, he...

. These "lost world
Lost World (genre)
The Lost World literary genre is a fantasy or science fiction genre that involves the discovery of a new world out of time, place, or both. It began as a subgenre of the late-Victorian imperial romance and remains popular to this day....

" 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
Robert Holdstock
Robert Paul Holdstock was an English novelist and author best known for his works of Celtic, Nordic, Gothic and Pictish fantasy literature, predominantly in the fantasy subgenre of mythic fiction....

's novel Mythago Wood
Mythago Wood
Mythago Wood is a fantasy novel written by Robert Holdstock that was published in the United Kingdom in 1984. The conception began as a short story written for the 1979 Milford Writer's Workshop; next a novella of the same name appeared in the September 1981 edition of The Magazine of Fantasy &...

.

After the mid-20th century, perhaps influenced by ideas from science fiction, perhaps because exploration had made many places on the map too clear to write "Here there be dragons
Here be dragons
"Here be dragons" is a phrase used to denote dangerous or unexplored territories, in imitation of the medieval practice of putting sea serpents and other mythological creatures in uncharted areas of maps.-History:...

", many fantasy worlds became completely separate from the author's world. A common trope
Trope (literature)
A literary trope is the usage of figurative language in literature, or a figure of speech in which words are used in a sense different from their literal meaning...

 is a portal or artifact that connects worlds together, prototypical examples being the wardrobe in C. S. Lewis
C. S. Lewis
Clive Staples Lewis , commonly referred to as C. S. Lewis and known to his friends and family as "Jack", was a novelist, academic, medievalist, literary critic, essayist, lay theologian and Christian apologist from Belfast, Ireland...

' The Lion, the Witch, and the Wardrobe, or the sigil in James Branch Cabell
James Branch Cabell
James Branch Cabell, ; April 14, 1879 – May 5, 1958) was an American author of fantasy fiction and belles lettres. Cabell was well regarded by his contemporaries, including H. L. Mencken and Sinclair Lewis. His works were considered escapist and fit well in the culture of the 1920s, when his...

's The Cream of the Jest
The Cream of the Jest
The Cream of the Jest : A Comedy of Evasions is a comical and philosophical novel with possible fantasy elements, by James Branch Cabell, published in 1917. Much of it consists of the historical dreams and philosophical reflections of the main character, the famous writer Felix Kennaston...

. In Hayao Miyazaki's
Hayao Miyazaki
is a Japanese manga artist and prominent film director and animator of many popular anime feature films. Through a career that has spanned nearly fifty years, Miyazaki has attained international acclaim as a maker of animated feature films and, along with Isao Takahata, co-founded Studio Ghibli,...

 Spirited Away
Spirited Away
is a 2001 Japanese animated fantasy-adventure film written and directed by Hayao Miyazaki and produced by Studio Ghibli. The film tells the story of Chihiro Ogino, a sullen ten-year-old girl who, while moving to a new neighborhood and after her parents are transformed into pigs by the witch Yubaba,...

, Chihiro Ogino and her parents climb over a small stream into the spirit world. 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
Altered state of consciousness
An altered state of consciousness , also named altered state of mind, is any condition which is significantly different from a normal waking beta wave state. The expression was used as early as 1966 by Arnold M. Ludwig and brought into common usage from 1969 by Charles Tart: it describes induced...

. Examples include the Dream Cycle
Dream Cycle
The Dream Cycle refers to a series of stories by author H. P. Lovecraft. These stories concern themselves with "The Dreamlands": a vast, alternate dimension that can be entered via dreams.-Geography:The Dreamlands is apparently divided into four regions:...

stories by H. P. Lovecraft
H. P. Lovecraft
Howard Phillips Lovecraft --often credited as H.P. Lovecraft — was an American author of horror, fantasy and science fiction, especially the subgenre known as weird fiction....

 or the Thomas Covenant stories of Stephen R. Donaldson
Stephen R. Donaldson
Stephen Reeder Donaldson is an American fantasy, science fiction and mystery novelist, most famous for his Thomas Covenant series...

. 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 employs this theme (usually without the dream-world being "another" universe) in the ideas of cyberspace
Cyberspace
Cyberspace is the electronic medium of computer networks, in which online communication takes place.The term "cyberspace" was first used by the cyberpunk science fiction author William Gibson, though the concept was described somewhat earlier, for example in the Vernor Vinge short story "True...

 and virtual reality
Virtual reality
Virtual reality , also known as virtuality, is a term that applies to computer-simulated environments that can simulate physical presence in places in the real world, as well as in imaginary worlds...

.

Between the worlds

Most stories in this mold simply transport a character from the real world into the fantasy world
Fantasy world
A fantasy world is a fictional universe used in fantasy novels and games. Typical worlds involve magic or magical abilities and often, but not always, either a medieval or futuristic theme...

 where the bulk of the action takes place. Whatever gate is used – such as the tollbooth in The Phantom Tollbooth
The Phantom Tollbooth
The Phantom Tollbooth is a children's adventure novel and modern fairy tale published in 1961, written by Norton Juster and illustrated by Jules Feiffer. It tells the story of a bored young boy named Milo who unexpectedly receives a magic tollbooth one afternoon and, having nothing better to do,...

by Norton Juster
Norton Juster
Norton Juster is an American architect and author. He is best known as an author of children's books, including The Phantom Tollbooth and The Dot and the Line.- Biography :...

, or the mirror in Lewis Carroll
Lewis Carroll
Charles Lutwidge Dodgson , better known by the pseudonym Lewis Carroll , was an English author, mathematician, logician, Anglican deacon and photographer. His most famous writings are Alice's Adventures in Wonderland and its sequel Through the Looking-Glass, as well as the poems "The Hunting of the...

's Through the Looking-Glass
Through the Looking-Glass
Through the Looking-Glass, and What Alice Found There is a work of literature by Lewis Carroll . It is the sequel to Alice's Adventures in Wonderland...

– is left behind for the duration of the story, until the end, and then only if the protagonists will return.

However, in a few cases the interaction between the worlds is an important element, so that the focus is not on one world or the other, but on both, and their interaction. After Rick Cook
Rick Cook
Rick Cook is a light fantasy author from the United States, best known for his Wizardry series of books. His writing includes many jokes that are hard to appreciate without having a background in systems-level programming, though the books themselves can easily be enjoyed by readers without such a...

 introduced a computer programmer into a high fantasy
High fantasy
High fantasy or epic fantasy is a subgenre of fantasy that is set in invented or parallel worlds. High fantasy was brought to fruition through the work of authors such as J. R. R. Tolkien and C. S. Lewis, whose major fantasy works were published in the 1950s...

 world, his wizardry series steadily acquired more interactions between this world and ours. In Aaron Allston
Aaron Allston
Aaron Allston is an American game designer and novelist of many science fiction books, notably Star Wars novels. His works as a game designer include game supplements for several role-playing games, several of which served to establish the basis for products and subsequent development of TSR's...

's Doc Sidhe our "grim world" is paralleled by a "fair world" where the elves live and history echoes ours. A major portion of the plot deals with preventing a change in interactions between the worlds. Margaret Ball
Margaret Ball (writer)
Margaret Ball is a science fiction and fantasy author who lives in Austin, Texas. Married and with two kids, she spends time writing, making quilts, embeadery, and taking care of kids at her home. She has a B.A. in mathematics and a Ph.D. in linguistics from the University of Texas...

, in No Earthly Sunne, depicts the interaction of our world with Faerie, and the efforts of the Queen of Faerie to deal with the slow drifting apart of Earth and Faerie. Poul Anderson
Poul Anderson
Poul William Anderson was an American science fiction author who began his career during one of the Golden Ages of the genre and continued to write and remain popular into the 21st century. Anderson also authored several works of fantasy, historical novels, and a prodigious number of short stories...

 depicts Hell as a parallel universe in Operation Chaos, and the need to transfer equivalent amounts of mass between the worlds explains why a changeling
Changeling
A changeling is a creature found in Western European folklore and folk religion. It is typically described as being the offspring of a fairy, troll, elf or other legendary creature that has been secretly left in the place of a human child. Sometimes the term is also used to refer to the child who...

 is left for a kidnapped child. Interactions between magical and scientific universes, and the protagonists' attempts to restore and maintain the balance between them, are major plot points in Piers Anthony
Piers Anthony
Piers Anthony Dillingham Jacob is an English American writer in the science fiction and fantasy genres, publishing under the name Piers Anthony. He is most famous for his long-running novel series set in the fictional realm of Xanth.Many of his books have appeared on the New York Times Best...

's Apprentice Adept
Apprentice Adept
Apprentice Adept is a seven-book fantasy and science fiction novel series by Piers Anthony. The series takes place on Phaze and Proton, two worlds occupying the same space in two different dimensional planes. Phaze is a lush planet of magic, where Proton is a barren mining planet of science...

series; he depicts two worlds, the "SF" planet Proton and the fantasy-based 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. Several of his Xanth
Xanth
Xanth is a fantasy world created by author Piers Anthony for his Xanth series of novels, also known as The Magic of Xanth.-History:The name Xanth is in itself an unintentional pun, which matches the playful tone of the books...

novels also revolve around interactions between the magical realm of Xanth and "Mundania
Mundane
In subcultural and fictional uses, a mundane is a person who does not belong to a particular group, according to the members of that group; the implication is that such persons, lacking imagination, are concerned solely with the mundane: the quotidian and ordinary...

".

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 Magician's Nephew
The Magician's Nephew is a fantasy novel for children written by C. S. Lewis. It was the sixth book published in his The Chronicles of Narnia series, but is the first in the chronology of the Narnia novels' fictional universe. Thus it is an early example of a prequel.The novel is initially set in...

, the Wood between the Worlds
Wood between the Worlds
The Wood between the Worlds is a linking room location in The Magician's Nephew, part of The Chronicles of Narnia series by C. S. Lewis.-The Magician's Nephew:...

 shows many possibilities, and the plot is governed by transportation between worlds, and the effort to right problems stemming from them. In His Dark Materials
His Dark Materials
His Dark Materials is a trilogy of fantasy novels by Philip Pullman comprising Northern Lights , The Subtle Knife , and The Amber Spyglass...

, the two protagonist Lyra and Will find themselves lost amongst many worlds, and travel them looking for the other. In Andre Norton
Andre Norton
Andre Alice Norton, née Alice Mary Norton was an American science fiction and fantasy author under the noms de plume Andre Norton, Andrew North and Allen Weston...

's Witch World
Witch World
The Witch World by Andre Norton is a long series of fantasy novels set in a parallel universe where magic works and, at the beginning of the series, is exclusively performed by women. The series combines many traits of high fantasy and sword and sorcery. It begins with what is now called the...

, 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 repels attention make certain parts of Witch World look like parallel worlds, some are clearly parallel in that time runs differently in them, and such gates pose a repeated problem in Witch World. In the radio sitcom Undone
Undone (radio series)
Undone is a radio comedy broadcast by the BBC on the digital channel BBC 7, written by and starring Ben Moor. It uses a sci-fi theme of parallel universes to poke fun at life and especially the media business in London...

, the main character, Edna Turner, prevents people from a parallel version of London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

 called "Undone" from moving to London and making the city too weird. There are other parallel versions of London, and one of the main plots in the series is the attempt by The Prince to unite all versions of London together.

Linking rooms of various types (not all actual rooms) can hook together any number of worlds. The characters may chose only one, but the choice is all important in determining the worlds.

Fantasy multiverses

The idea of a multiverse
Multiverse (science)
The multiverse is the hypothetical set of multiple possible universes that together comprise everything that exists and can exist: the entirety of space, time, matter, and energy as well as the physical laws and constants that describe them...

 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
Michael Moorcock
Michael John Moorcock is an English writer, primarily of science fiction and fantasy, who has also published a number of literary novels....

. Like many authors after him, Moorcock was inspired by the many worlds interpretation of quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...

, 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
Eternal Champion
The Eternal Champion is a fictional creation of the author Michael Moorcock and is a recurrent feature in many of his novels.-About the Eternal Champion:...

stories go far beyond alternate history to include mythic
Mythology
The term mythology can refer either to the study of myths, or to a body or collection of myths. As examples, comparative mythology is the study of connections between myths from different cultures, whereas Greek mythology is the body of myths from ancient Greece...

 and sword and sorcery
Sword and sorcery
Sword and sorcery is a sub-genre of fantasy and historical fantasy, generally characterized by sword-wielding heroes engaged in exciting and violent conflicts. An element of romance is often present, as is an element of magic and the supernatural...

 settings as well as some worlds more similar to our own. However, the Eternal Champion himself is incarnate in all of them.

Roger Zelazny
Roger Zelazny
Roger Joseph Zelazny was an American writer of fantasy and science fiction short stories and novels, best known for his The Chronicles of Amber series...

 used a mythic cosmology
Cosmology
Cosmology is the discipline that deals with the nature of the Universe as a whole. Cosmologists seek to understand the origin, evolution, structure, and ultimate fate of the Universe at large, as well as the natural laws that keep it in order...

 in his Chronicles of Amber series. His protagonist is a member of the royal family of Amber, whose members represent a godlike pantheon
Pantheon (gods)
A pantheon is a set of all the gods of a particular polytheistic religion or mythology.Max Weber's 1922 opus, Economy and Society discusses the link between a...

 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
World of Tiers
The World of Tiers is a series of science fiction novels by American writer Philip José Farmer. They are set within a series of artificially-constructed universes, created and ruled by decadent beings who are genetically identical to humans, but who regard themselves as superior, the inheritors of...

novels by Philip José Farmer
Philip José Farmer
Philip José Farmer was an American author, principally known for his award-winning science fiction and fantasy novels and short stories....

, 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 universe
Pocket universe
-In science:A pocket universe is a concept in inflationary theory, proposed by Alan Guth. It defines a realm like the one that contains the observable universe as only one of many inflationary zones.-In fiction:...

s 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
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

.

The term 'polycosmos' was coined as an alternative to 'multiverse' by the author and editor Paul le Page Barnett, best known by the pseudonym John Grant, and is built from Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 rather than Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 morpheme
Morpheme
In linguistics, a morpheme is the smallest semantically meaningful unit in a language. The field of study dedicated to morphemes is called morphology. A morpheme is not identical to a word, and the principal difference between the two is that a morpheme may or may not stand alone, whereas a word,...

s. It is used by Barnett to describe a concept binding together a number of his works, its nature meaning that "all characters, real or fictional [...] have to co-exist in all possible real, created or dreamt worlds; [...] they're playing hugely different roles in their various manifestations, and the relationships between them can vary quite dramatically, but the essence of them remains the same."

There are multiverses also in the Warcraft universe
Warcraft Universe
Warcraft is a franchise of video games, novels, and other media originally created by Blizzard Entertainment. The series is made up of Four core games: Warcraft: Orcs & Humans, Warcraft II: Tides of Darkness, Warcraft III: Reign of Chaos, and World of Warcraft...

, The Chronicles of Narnia
The Chronicles of Narnia
The Chronicles of Narnia is a series of seven fantasy novels for children by C. S. Lewis. It is considered a classic of children's literature and is the author's best-known work, having sold over 100 million copies in 47 languages...

, Terry Pratchett
Terry Pratchett
Sir Terence David John "Terry" Pratchett, OBE is an English novelist, known for his frequently comical work in the fantasy genre. He is best known for his popular and long-running Discworld series of comic fantasy novels...

's Discworld
Discworld
Discworld is a comic fantasy book series by English author Sir Terry Pratchett, set on the Discworld, a flat world balanced on the backs of four elephants which, in turn, stand on the back of a giant turtle, Great A'Tuin. The books frequently parody, or at least take inspiration from, J. R. R....

series, and Diana Wynne Jones
Diana Wynne Jones
Diana Wynne Jones was a British writer, principally of fantasy novels for children and adults, as well as a small amount of non-fiction...

's Chrestomanci
Chrestomanci
The Chrestomanci series is a children's fantasy series by Diana Wynne Jones. The word "Chrestomanci" may be derived from the Greek khrestos, meaning "useful," and -mancy, "divination."...

, Howl's Moving Castle
Howl's Moving Castle
Howl's Moving Castle is a young adult fantasy novel by British author Diana Wynne Jones, first published in 1986. It won a Boston Globe-Horn Book Award and was named an ALA Notable Book for both children and young adults. In 2004 it was adapted as an Academy Award-nominated animated film by Hayao...

and Deep Secret
Deep Secret
Deep Secret is a 1997 novel by Diana Wynne Jones. It is the first in the Magid series.-Plot:The multiverse, shaped like a lemniscate, contains Ayeward and Nayward worlds. It is the task of the magids to urge the worlds in an Ayewards direction. In Ayeward worlds, magids can operate openly...

books and standalone book A Sudden Wild Magic.

Fictional universe as alternative 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
Fletcher Pratt
Murray Fletcher Pratt was an American writer of science fiction, fantasy and history, particularly noted for his works on naval history and on the American Civil War.- Life and work :...

 and L. Sprague de Camp
L. Sprague de Camp
Lyon Sprague de Camp was an American author of science fiction and fantasy books, non-fiction and biography. In a writing career spanning 60 years, he wrote over 100 books, including novels and notable works of non-fiction, including biographies of other important fantasy authors...

 took the protagonist of the Harold Shea series through the worlds of Norse myth, Edmund Spenser
Edmund Spenser
Edmund Spenser was an English poet best known for The Faerie Queene, an epic poem and fantastical allegory celebrating the Tudor dynasty and Elizabeth I. He is recognised as one of the premier craftsmen of Modern English verse in its infancy, and one of the greatest poets in the English...

's Faerie Queene, Ludovico Ariosto
Ludovico Ariosto
Ludovico Ariosto was an Italian poet. He is best known as the author of the romance epic Orlando Furioso . The poem, a continuation of Matteo Maria Boiardo's Orlando Innamorato, describes the adventures of Charlemagne, Orlando, and the Franks as they battle against the Saracens with diversions...

's Orlando Furioso
Orlando Furioso
Orlando Furioso is an Italian epic poem by Ludovico Ariosto which has exerted a wide influence on later culture. The earliest version appeared in 1516, although the poem was not published in its complete form until 1532...

, and the Kalevala
Kalevala
The Kalevala is a 19th century work of epic poetry compiled by Elias Lönnrot from Finnish and Karelian oral folklore and mythology.It is regarded as the national epic of Finland and is one of the most significant works of Finnish literature...

— 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
Kubla Khan
Kubla Khan is a poem by Samuel Taylor Coleridge, completed in 1797 and published in Christabel, Kubla Khan, and the Pains of Sleep in 1816...

", 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
L. Sprague de Camp
Lyon Sprague de Camp was an American author of science fiction and fantasy books, non-fiction and biography. In a writing career spanning 60 years, he wrote over 100 books, including novels and notable works of non-fiction, including biographies of other important fantasy authors...

's Solomon's Stone
Solomon's Stone
Solomon's Stone is a fantasy novel written by L. Sprague de Camp. It was first published in the fantasy magazine Unknown Worlds for June, 1942...

, 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
Stephen King
Stephen Edwin King is an American author of contemporary horror, suspense, science fiction and fantasy fiction. His books have sold more than 350 million copies and have been adapted into a number of feature films, television movies and comic books...

's seven-volume Dark Tower
The Dark Tower (series)
The Dark Tower is a series of books written by American author Stephen King, which incorporates themes from multiple genres, including fantasy, science fantasy, horror and western. It describes a "Gunslinger" and his quest toward a tower, the nature of which is both physical and metaphorical. King...

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 (this can be debated as an example of breaking the fourth wall), 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. An early instance of this was in works by Gardner Fox
Gardner Fox
Gardner Francis Cooper Fox was an American writer best known for creating numerous comic book characters for DC Comics. Comic-book historians estimate that he wrote over 4,000 comics stories....

 for DC Comics in the 1960s, in which characters from the Golden Age (which was supposed to be a series of comic books within the DC Comics universe) would cross over into the main DC Comics universe. One comic book did provide an explanation for a fictional universe existing as a parallel universe. The parallel world does "exist" and it resonates into the "real world." Some people in the "real world" pick up on this resonance, gaining information about the parallel world which they then use to write stories.

Elfland

Elfland
Álfheim
Alfheim is one of the Nine Worlds and home of the Light Elves in Norse mythology and appears also in Anglo-Scottish ballads under the form Elfhame as a fairyland, sometimes modernized as Elfland .-In Old Norse texts:Álfheim as an abode of the Elves is mentioned only twice in Old Norse texts.The...

, or Faerie, the otherworldly home not only of elves
Elf
An elf is a being of Germanic mythology. The elves were originally thought of as a race of divine beings endowed with magical powers, which they use both for the benefit and the injury of mankind...

 and fairies
Fairy
A fairy is a type of mythical being or legendary creature, a form of spirit, often described as metaphysical, supernatural or preternatural.Fairies resemble various beings of other mythologies, though even folklore that uses the term...

 but goblin
Goblin
A goblin is a legendary evil or mischievous illiterate creature, a grotesquely evil or evil-like phantom.They are attributed with various abilities, temperaments and appearances depending on the story and country of origin. In some cases, goblins have been classified as constantly annoying little...

s, troll
Troll
A troll is a supernatural being in Norse mythology and Scandinavian folklore. In origin, the term troll was a generally negative synonym for a jötunn , a being in Norse mythology...

s, and other folkloric creatures, has an ambiguous appearance in folklore.

On one hand, the land often appears to be contiguous with 'ordinary' land. Thomas the Rhymer
Thomas the Rhymer
Thomas Learmonth , better known as Thomas the Rhymer or True Thomas, was a 13th century Scottish laird and reputed prophet from Earlston . He is also the protagonist of the ballad "Thomas the Rhymer"...

 might, on being taken by the Queen of Faerie, be taken on a road like one leading to Heaven or Hell.

This is not exclusive to English or French folklore. In Norse mythology
Norse mythology
Norse mythology, a subset of Germanic mythology, is the overall term for the myths, legends and beliefs about supernatural beings of Norse pagans. It flourished prior to the Christianization of Scandinavia, during the Early Middle Ages, and passed into Nordic folklore, with some aspects surviving...

, Elfland (Alfheim
Álfheim
Alfheim is one of the Nine Worlds and home of the Light Elves in Norse mythology and appears also in Anglo-Scottish ballads under the form Elfhame as a fairyland, sometimes modernized as Elfland .-In Old Norse texts:Álfheim as an abode of the Elves is mentioned only twice in Old Norse texts.The...

) was also the name of what today is the Swedish province of Bohuslän
Bohuslän
' is a Swedish traditional province, or landskap, situated in Götaland on the northernmost part of the country's west coast. It is bordered by Dalsland to the northeast, Västergötland to the southeast, the Skagerrak arm of the North Sea to the west, and the county of Østfold in Norway to the north...

. In the sagas, it said that the people of this petty kingdom were more beautiful than other people, as they were related to the elves, showing that not only the territory was associated with elves, but also the race of its people.

While sometimes folklore seems to show fairy intrusion into human lands — "Tam Lin
Tam Lin
Tam Lin is the hero of a legendary ballad originating from the Scottish Borders. The story revolves around the rescue of Tam Lin by his true love from the Queen of the Fairies...

" does not show any otherworldly aspects about the land in which 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
Oisín
Oisín , also spelt in English Ossian or Osheen, was regarded in legend as the greatest poet of Ireland, and is a warrior of the fianna in the Ossianic or Fenian Cycle of Irish mythology...

, 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
Josepha Sherman
Josepha Sherman is an American author. In 1990 she won the Compton Crook Award for the novel The Shining Falcon.-Buffyverse:*Visitors *Deep Water ...

's Prince of the Sidhe series or Esther Friesner
Esther Friesner
Esther Mona Friesner-Stutzman, née Friesner is an American science fiction and fantasy author best known for her humorous pieces.- Life :...

's Elf Defense — and others have depicted it as the next land over, possibly difficult to reach for magical reasons — Hope Mirrlees
Hope Mirrlees
Hope Mirrlees was a British translator, poet and novelist. She is best known for the 1926 Lud-in-the-Mist, a fantasy novel and influential classic, and for Paris: A Poem, a modernist poem which critic Julia Briggs deemed "modernism's lost masterpiece, a work of extraordinary energy and intensity,...

's Lud-in-the-Mist
Lud-in-the-Mist
Lud-in-the-Mist is the third of three novels by Hope Mirrlees, and the only one still in print . It continues the author's exploration of the themes of Life and Art, by a method already described in the preface of her first novel, Madeleine: One of Love's Jansenists : "to turn from time to time...

, or Lord Dunsany's The King of Elfland's Daughter
The King of Elfland's Daughter
The King of Elfland's Daughter is a 1924 fantasy novel written by Lord Dunsany. Written before the genre was named, it is considered to be among the pioneering works of modern fantasy. Its importance was recognized in its later revival in paperback by Ballantine Books as the second volume of the...

. 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. Terry Pratchett
Terry Pratchett
Sir Terence David John "Terry" Pratchett, OBE is an English novelist, known for his frequently comical work in the fantasy genre. He is best known for his popular and long-running Discworld series of comic fantasy novels...

's Discworld
Discworld
Discworld is a comic fantasy book series by English author Sir Terry Pratchett, set on the Discworld, a flat world balanced on the backs of four elephants which, in turn, stand on the back of a giant turtle, Great A'Tuin. The books frequently parody, or at least take inspiration from, J. R. R....

series proposes that the world of the Elves is a "parasite" universe, that drifts between and latches onto others such as Discworld and our own world (referred to as "Roundworld" in the novels).

Films

The most famous treatment of the alternative universe concept in film could be considered The Wizard of Oz
The Wizard of Oz (1939 film)
The Wizard of Oz is a 1939 American musical fantasy film produced by Metro-Goldwyn-Mayer. It was directed primarily by Victor Fleming. Noel Langley, Florence Ryerson and Edgar Allan Woolf received credit for the screenplay, but there were uncredited contributions by others. The lyrics for the songs...

, which portrays a parallel world, famously separating the magical realm of the Land of Oz
Land of Oz
Oz is a fantasy region containing four lands under the rule of one monarch.It was first introduced in The Wonderful Wizard of Oz by L. Frank Baum, one of many fantasy countries that he created for his books. It achieved a popularity that none of his other works attained, and after four years, he...

 from the mundane world by filming it in Technicolor
Technicolor
Technicolor is a color motion picture process invented in 1916 and improved over several decades.It was the second major process, after Britain's Kinemacolor, and the most widely used color process in Hollywood from 1922 to 1952...

 while filming the scenes set in Kansas
Kansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...

 in sepia.

A later example is the Frank Capra
Frank Capra
Frank Russell Capra was a Sicilian-born American film director. He emigrated to the U.S. when he was six, and eventually became a creative force behind major award-winning films during the 1930s and 1940s...

 movie, It's a Wonderful Life
It's a Wonderful Life
It's a Wonderful Life is a 1946 American Christmas drama film produced and directed by Frank Capra and based on the short story "The Greatest Gift" written by Philip Van Doren Stern....

where the main character George Bailey
George Bailey (fictional character)
George Bailey is a fictional character and the main protagonist in Frank Capra's 1946 film It's a Wonderful Life. He is played by James Stewart. He is loosely based on George Pratt, a character in Philip Van Doren Stern's The Greatest Gift....

 is shown by a guardian angel
Guardian angel
A guardian angel is an angel assigned to protect and guide a particular person or group. Belief in guardian angels can be traced throughout all antiquity...

 the city of Pottersville
It's a Wonderful Life
It's a Wonderful Life is a 1946 American Christmas drama film produced and directed by Frank Capra and based on the short story "The Greatest Gift" written by Philip Van Doren Stern....

, which was George Bailey's hometown of Bedford Falls
It's a Wonderful Life
It's a Wonderful Life is a 1946 American Christmas drama film produced and directed by Frank Capra and based on the short story "The Greatest Gift" written by Philip Van Doren Stern....

 as it would have been if he had never existed. Another notable depiction of a parallel universe in movies is in Back to the Future Part II
Back to the Future Part II
Back to the Future Part II is a 1989 American science fiction comedy film and the second installment of the Back to the Future trilogy. It was directed by Robert Zemeckis, written by Zemeckis and Bob Gale, and starred Michael J. Fox, Christopher Lloyd, Thomas F. Wilson and Lea Thompson...

by Robert Zemeckis
Robert Zemeckis
Robert Lee Zemeckis is an American film director, producer and screenwriter. Zemeckis first came to public attention in the 1980s as the director of the comedic time-travel Back to the Future film series, as well as the Academy Award-winning live-action/animation epic Who Framed Roger Rabbit ,...

, starring Michael J. Fox
Michael J. Fox
Michael J. Fox, OC is a Canadian American actor, author, producer, activist and voice-over artist. With a film and television career spanning from the late 1970s, Fox's roles have included Marty McFly from the Back to the Future trilogy ; Alex P...

 and Christopher Lloyd
Christopher Lloyd
Christopher Allen Lloyd is an American actor. He is best known for playing Emmett Brown in the Back to the Future trilogy, Uncle Fester in The Addams Family and Addams Family Values, and Judge Doom in Who Framed Roger Rabbit. He played Reverend Jim Ignatowski in the television series Taxi and more...

, showing an accidentally created
Point of divergence
In discussion of counterfactual history, a divergence point , also referred to as a departure point or point of divergence , is a historical event with two possible postulated outcomes...

 alternative present and future
Alternate future
In science fiction stories involving time travel, an alternative future or alternate future is a possible future which never comes to pass, typically because someone travels back into the past and alters it so that the events of the alternative future cannot occur.An alternative future differs from...

. Like It's a Wonderful Life, The Big Time, and many other time travel stories using this concept, it is clear that these alternative presents/futures are mutually exclusive with the protagonists' own — so, strictly speaking, the universes are not parallel in that they cannot co-exist, rather they oscillate between one or the other.

Another common use of the theme is as a prison for villains or demons. The idea is used in the first two Superman movies starring Christopher Reeve
Christopher Reeve
Christopher D'Olier Reeve was an American actor, film director, producer, screenwriter, author and activist...

 where Kryptonian
Krypton (comics)
Krypton is a fictional planet in the DC Comics universe, and the native world of the super-heroes Superman and, in some tellings, Supergirl and Krypto the Superdog. Krypton has been portrayed consistently as having been destroyed just after Superman's flight from the planet, with exact details of...

 villains were sentenced to the Phantom Zone
Phantom Zone
The Phantom Zone is a fictional prison dimension featured in the Superman comic books and related media published by DC Comics. It first appeared in Adventure Comics #283 , and was created by Robert Bernstein and George Papp...

 from where they eventually escaped. An almost exactly parallel use of the idea is presented in the campy cult film The Adventures of Buckaroo Banzai Across the 8th Dimension
The Adventures of Buckaroo Banzai Across the 8th Dimension
The Adventures of Buckaroo Banzai Across the 8th Dimension!, often shortened to Buckaroo Banzai, is an American spoof science fiction film that was released in 1984. It was directed and produced by W. D. Richter, and concerns the efforts of the multi-talented Dr...

, where the "8th dimension" is essentially a "phantom zone" used to imprison the villainous Red Lectroids. Uses in horror films include the 1986 film From Beyond
From Beyond (film)
From Beyond is a 1986 American science fiction/ body horror film directed by Stuart Gordon, loosely based on the short story of the same title by H. P. Lovecraft, and was written by Dennis Paoli, Gordon and Brian Yuzna...

(based on the H. P. Lovecraft
H. P. Lovecraft
Howard Phillips Lovecraft --often credited as H.P. Lovecraft — was an American author of horror, fantasy and science fiction, especially the subgenre known as weird fiction....

 story
From Beyond (short story)
"From Beyond" is a short story by science fiction and horror fiction writer H. P. Lovecraft. It was written in 1920 and was first published in The Fantasy Fan in June 1934 .-Synopsis:...

 of the same name) where a scientific experiment induces the experimenters to perceive aliens
Extraterrestrial life in popular culture
In popular cultures, "extraterrestrials" are life forms — especially intelligent life forms— that are of extraterrestrial origin .-Historical ideas:-Pre-modern:...

 from a parallel universe, with bad results. The 1987 John Carpenter
John Carpenter
John Howard Carpenter is an American film director, screenwriter, producer, editor, composer, and occasional actor. Although Carpenter has worked in numerous film genres in his four-decade career, his name is most commonly associated with horror and science fiction.- Early life :Carpenter was born...

 film Prince of Darkness
Prince of Darkness (film)
Prince of Darkness is a 1987 horror film directed, written, and scored by John Carpenter. The film is the second installment in what Carpenter calls his "Apocalypse Trilogy", which began with The Thing and concludes with In the Mouth of Madness .-Plot:The movie opens with a dying priest clutching...

is based on the premise that the essence of a being described as Satan
Satan
Satan , "the opposer", is the title of various entities, both human and divine, who challenge the faith of humans in the Hebrew Bible...

, trapped in a glass canister and found in an abandoned church in Los Angeles
Los Ángeles
Los Ángeles is the capital of the province of Biobío, in the commune of the same name, in Region VIII , in the center-south of Chile. It is located between the Laja and Biobío rivers. The population is 123,445 inhabitants...

, is actually an alien being that is the 'son' of something even more evil and powerful, trapped in another universe. The protagonists accidentally free the creature, who then attempts to release his "father" by reaching in through a reflective glass, or mirror
Mirror
A mirror is an object that reflects light or sound in a way that preserves much of its original quality prior to its contact with the mirror. Some mirrors also filter out some wavelengths, while preserving other wavelengths in the reflection...

.

Some films present parallel realities that are actually different contrasting versions of the narrative itself. Commonly this motif is presented as different points of view revolving around a central (but sometimes unknowable) "truth", the seminal example being Akira Kurosawa
Akira Kurosawa
was a Japanese film director, producer, screenwriter and editor. Regarded as one of the most important and influential filmmakers in the history of cinema, Kurosawa directed 30 filmsIn 1946, Kurosawa co-directed, with Hideo Sekigawa and Kajiro Yamamoto, the feature Those Who Make Tomorrow ;...

's Rashomon
Rashomon (film)
The bandit's storyTajōmaru, a notorious brigand , claims that he tricked the samurai to step off the mountain trail with him and look at a cache of ancient swords he discovered. In the grove he tied the samurai to a tree, then brought the woman there. She initially tried to defend herself with a...

. Conversely, often in film noir
Film noir
Film noir is a cinematic term used primarily to describe stylish Hollywood crime dramas, particularly those that emphasize cynical attitudes and sexual motivations. Hollywood's classic film noir period is generally regarded as extending from the early 1940s to the late 1950s...

 and crime dramas
Crime film
Crime films are films which focus on the lives of criminals. The stylistic approach to a crime film varies from realistic portrayals of real-life criminal figures, to the far-fetched evil doings of imaginary arch-villains. Criminal acts are almost always glorified in these movies.- Plays and films...

, the alternative narrative is a fiction created by a central character, intentionally — as in The Usual Suspects
The Usual Suspects
The Usual Suspects is a 1995 American neo-noir film written by Christopher McQuarrie and directed by Bryan Singer. It stars Stephen Baldwin, Gabriel Byrne, Benicio del Toro, Chazz Palminteri, Kevin Pollak, Kevin Spacey and Pete Postlethwaite....

— or unintentionally — as in Angel Heart
Angel Heart
Angel Heart is a 1987 North American/British mystery-thriller film written and directed by Alan Parker, and starring Mickey Rourke, Robert De Niro, and Lisa Bonet...

. Less often, the alternative narratives are given equal weight in the story, making them truly alternative universes, such as in the German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 film Run Lola Run
Run Lola Run
Run Lola Run is a 1998 German crime thriller film written and directed by Tom Tykwer and starring Franka Potente as Lola and Moritz Bleibtreu as Manni. The story follows a woman who needs to obtain 100,000 German marks in 20 minutes to save her boyfriend's life...

, the short-lived British West End
West End theatre
West End theatre is a popular term for mainstream professional theatre staged in the large theatres of London's 'Theatreland', the West End. Along with New York's Broadway theatre, West End theatre is usually considered to represent the highest level of commercial theatre in the English speaking...

 musical Our House
Our House (musical)
Our House is a musical with music and lyrics from Madness and the book by Tim Firth. The show featured songs from the ska/pop band Madness, and was named after one of their popular hit singles, "Our House"...

and the British
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

 film Sliding Doors
Sliding Doors
Sliding Doors is a 1998 British-American romantic comedy-drama film written and directed by Peter Howitt and starring Gwyneth Paltrow and John Hannah, and featured John Lynch, Jeanne Tripplehorn and Virginia McKenna. The music was composed by David Hirschfelder...

.

More recent films that have explicitly explored parallel universes are: the 2000 film The Family Man
The Family Man
The Family Man is a 2000 drama film directed by Brett Ratner and starring Nicolas Cage and Téa Leoni. Cage's production company, Saturn Films, helped produce the film....

, the 2001 cult movie Donnie Darko
Donnie Darko
Donnie Darko is a 2001 American psychological thriller film written and directed by Richard Kelly and starring Jake Gyllenhaal, Drew Barrymore, Patrick Swayze, Maggie Gyllenhaal, Noah Wyle, Jena Malone, and Mary McDonnell...

, which deals with what it terms a "tangent universe" that erupts from our own universe; Super Mario Bros.
Super Mario Bros. (film)
Super Mario Bros. is a 1993 American action film directed by Rocky Morton and Annabel Jankel. Based on the Super Mario Bros.video game and its entire franchise, the film features Bob Hoskins, John Leguizamo, Dennis Hopper and Samantha Mathis. It tells the story of the Mario brothers, Mario and...

(1993) has the eponymous heroes cross over into a parallel universe ruled by humanoids who evolved from dinosaurs; The One (2001) starring Jet Li
Jet Li
The fame gained by his sports winnings led to a career as a martial arts film star, beginning in mainland China and then continuing into Hong Kong. Li acquired his screen name in 1982 in the Philippines when a publicity company thought his real name was too hard to pronounce...

, in which there is a complex system of realities in which Jet Li's character is a police officer in one universe and a serial killer in another, who travels to other universes to destroy versions of himself, so that he can take their energy; and FAQ: Frequently Asked Questions
FAQ: Frequently Asked Questions
FAQ: Frequently Asked Questions is a feature-length dystopia movie, written and directed by Carlos Atanes and released in 2004.-Plot:France, sometime in the near future. The Sisterhood of Metacontrol governs Europe. Angeline, an exemplary and irreproachable citizen has just joined the Order.....

(2004), the main character runs away from a totalitarian nightmare, and he enters into a cyber-afterlife alternative reality. The most recent Star Trek film (2009) had a character create an alternate reality by traveling back in time, thereby rebooting the series' complicated continuity.

The film director
Film director
A film director is a person who directs the actors and film crew in filmmaking. They control a film's artistic and dramatic nathan roach, while guiding the technical crew and actors.-Responsibilities:...

 and screenwriter
Screenwriter
Screenwriters or scriptwriters or scenario writers are people who write/create the short or feature-length screenplays from which mass media such as films, television programs, Comics or video games are based.-Profession:...

 Quentin Tarentino has been known to create his own brand of reality for each of his movies and for his subjects. In his 2009 film Inglorious Basterds, he created his most effective story in showcasing this kind of creation. At the climax of this film his soldiers trap, surround, and then assassinate both Nazi leader Adolf Hitler
Adolf Hitler
Adolf Hitler was an Austrian-born German politician and the leader of the National Socialist German Workers Party , commonly referred to as the Nazi Party). He was Chancellor of Germany from 1933 to 1945, and head of state from 1934 to 1945...

 and all of his entire High Command
Oberkommando der Wehrmacht
The Oberkommando der Wehrmacht was part of the command structure of the armed forces of Nazi Germany during World War II.- Genesis :...

 (the Oberkommando der Wehrmacht
Oberkommando der Wehrmacht
The Oberkommando der Wehrmacht was part of the command structure of the armed forces of Nazi Germany during World War II.- Genesis :...

) in a burning Paris
Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...

, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 movie theater in an alternate 1944, theoretically ending the war.

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
Science fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

 or fantasy
Fantasy
Fantasy is a genre of fiction that commonly uses magic and other supernatural phenomena as a primary element of plot, theme, or setting. Many works within the genre take place in imaginary worlds where magic is common...

 storyline.

One of the earliest television plots to feature parallel time was a 1970 storyline on soap opera Dark Shadows
Dark Shadows
Dark Shadows is a gothic soap opera that originally aired weekdays on the ABC television network, from June 27, 1966 to April 2, 1971. The show was created by Dan Curtis. The story bible, which was written by Art Wallace, does not mention any supernatural elements...

. Vampire Barnabas Collins found a room in Collinwood which served as a portal to parallel time, and he entered the room in order to escape from his current problems. A year later, the show again traveled to parallel time, the setting this time being 1841.

A well known and often imitated example is the original Star Trek
Star Trek: The Original Series
Star Trek is an American science fiction television series created by Gene Roddenberry, produced by Desilu Productions . Star Trek was telecast on NBC from September 8, 1966, through June 3, 1969...

episode entitled "Mirror, Mirror". The episode introduced an alternative version of the Star Trek universe where the main characters were barbaric and cruel to the point of being evil
Evil
Evil is the violation of, or intent to violate, some moral code. Evil is usually seen as the dualistic opposite of good. Definitions of evil vary along with analysis of its root motive causes, however general actions commonly considered evil include: conscious and deliberate wrongdoing,...

. When the parallel universe concept is parodied
Parody
A parody , in current usage, is an imitative work created to mock, comment on, or trivialise an original work, its subject, author, style, or some other target, by means of humorous, satiric or ironic imitation...

, the allusion is often to this Star Trek episode. A previous episode for the Trek series first hinted at the potential of differing reality planes (and their occupants) -titled "The Alternative Factor". A mad scientist from "our" universe, named Lazarus B., hunts down the sane Lazarus A.; resident of an antimatter
Antimatter
In particle physics, antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles...

-comprised continuum. His counterpart, in a state of paranoia, claims the double threatens his and the very cosmos' existence. With help from Captain Kirk
James T. Kirk
James Tiberius "Jim" Kirk is a character in the Star Trek media franchise. Kirk was first played by William Shatner as the principal lead character in the original Star Trek series. Shatner voiced Kirk in the animated Star Trek series and appeared in the first seven Star Trek movies...

, A traps B along with him in a "anti"-universe, for eternity, thus bringing balance to both matter
Matter
Matter is a general term for the substance of which all physical objects consist. Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume...

 oriented realms. A similar plot was used in the Codename: Kids Next Door episode Operation: P.O.O.L..

Multiple episodes of Red Dwarf
Red Dwarf
Red Dwarf is a British comedy franchise which primarily comprises eight series of a television science fiction sitcom that aired on BBC Two between 1988 and 1999 and Dave from 2009–present. It gained cult following. It was created by Rob Grant and Doug Naylor, who also wrote the first six series...

use the concept. In "Parallel Universe" the crew meet alternative versions of themselves: the analogues of Lister, Rimmer and Holly are female, while the Cat's alternate is a dog. "Dimension Jump" introduces a heroic alternate Rimmer, a version of whom reappears in "Stoke Me a Clipper". The next episode, "Ouroboros", makes contact with a timeline in which Kochanski, rather than Lister, was the sole survivor of the original disaster; this alternate Kochanski then joins the crew for the remaining episodes.

Another example is "Spookyfish
Spookyfish
"Spookyfish" is the fifteenth episode of the second season of the animated television series South Park, and the 28th episode of the series overall. "Spookyfish" originally aired in the United States on October 28, 1998 on Comedy Central...

", an episode of South Park
South Park
South Park is an American animated television series created by Trey Parker and Matt Stone for the Comedy Central television network. Intended for mature audiences, the show has become famous for its crude language, surreal, satirical, and dark humor that lampoons a wide range of topics...

, in which the "evil" universe double of Cartman (who is pleasant and agreeable, unlike the home universe's obnoxious Cartman) sports a goatee, like the "mirror" version of Mr. Spock.

Buffy the Vampire Slayer experienced a Parallel universe where she was a mental patient in Normal Again and not really "The Slayer" at all. In the end, she has to choose between a universe where her mother and father are together and alive (mother) or one with her friends and sister in it where she has to fight for her life daily.

The animated series, Futurama
Futurama
Futurama is an American animated science fiction sitcom created by Matt Groening and developed by Groening and David X. Cohen for the Fox Broadcasting Company. The series follows the adventures of a late 20th-century New York City pizza delivery boy, Philip J...

, had an episode
The Farnsworth Parabox
"The Farnsworth Parabox" is the fifteenth episode of the fourth production season of Futurama. It first aired June 8, 2003, as the tenth episode in the fifth broadcast season. The episode was written by Bill Odenkirk and directed by Ron Hughart.- Plot :...

 where the characters travel between "Universe A" and "Universe 1" via boxes containing each universe; and one of the major jokes is an extended argument between the two sets of characters over which set were the "evil" ones.

Doctor Who
Doctor Who
Doctor Who is a British science fiction television programme produced by the BBC. The programme depicts the adventures of a time-travelling humanoid alien known as the Doctor who explores the universe in a sentient time machine called the TARDIS that flies through time and space, whose exterior...

 often features parallel universes as the basis of a plotline. In the episode "Inferno
Inferno (Doctor Who)
Don Houghton came to Terrence Dicks with an idea for the story based on the real life Project Mohole. A smaller budget for the serial drove the idea of a parallel world, where the studio could use the same actors in multiple roles...

", from Doctor Who the Doctor accidentally travels to a parallel universe where Great Britain is a republic under a fascist leader. In "Rise of the Cybermen
Rise of the Cybermen
"Rise of the Cybermen" is an episode in the British science fiction television series Doctor Who. The episode features the return of Cybermen, where they are created on Earth itself. It is the first part of a two-part story, the concluding part being "The Age of Steel"...

", the TARDIS falls out of the Time-Space Continuum, and dies, with the Doctor and his companions inside it. The Doctor believes them to be in the Void, the infinite empty-space between the universes, where no time, space or energy exists. It turns out, however, they fell into another universe; a much more desirable option. In this universe, Britain is a lot more technically advanced, with blimps almost replacing cars. They find a way to revive the TARDIS and travel back to their own universe. According to the Doctor in "Doomsday
Doomsday (Doctor Who)
"Doomsday" is the thirteenth and final episode in the second series of the revival of the British science fiction television series Doctor Who. It was first broadcast on 8 July 2006 and is the conclusion of a two-part story; the first part, "Army of Ghosts", was broadcast on 1 July 2006...

", a new parallel universe is created by every decision made.

The OC had an episode where two main characters fell into a coma, and into an alternate/parallel universe.

Friends had an episode in which the characters wonder how different their lives would be with different choices.

Parallel universes/alternate futures are also featured in Heroes
Heroes (TV series)
Heroes is an American science fiction television drama series created by Tim Kring that appeared on NBC for four seasons from September 25, 2006 through February 8, 2010. The series tells the stories of ordinary people who discover superhuman abilities, and how these abilities take effect in the...

.

The idea of a parallel universe and the concept of deja vu
Déjà vu
Déjà vu is the experience of feeling sure that one has already witnessed or experienced a current situation, even though the exact circumstances of the prior encounter are uncertain and were perhaps imagined...

 was a major plot line of the first season finale of Fringe
Fringe (TV series)
Fringe is an American science fiction television series created by J. J. Abrams, Alex Kurtzman and Roberto Orci. The series follows a Federal Bureau of Investigation "Fringe Division" team based in Boston, Massachusetts under the supervision of Homeland Security...

, guest-starring Leonard Nimoy
Leonard Nimoy
Leonard Simon Nimoy is an American actor, film director, poet, musician and photographer. Nimoy's most famous role is that of Spock in the original Star Trek series , multiple films, television and video game sequels....

 of Star Trek
Star Trek: The Original Series
Star Trek is an American science fiction television series created by Gene Roddenberry, produced by Desilu Productions . Star Trek was telecast on NBC from September 8, 1966, through June 3, 1969...

. The show has gone on to feature the parallel universe prominently.

In the 2010 season of Lost
Lost (TV series)
Lost is an American television series that originally aired on ABC from September 22, 2004 to May 23, 2010, consisting of six seasons. Lost is a drama series that follows the survivors of the crash of a commercial passenger jet flying between Sydney and Los Angeles, on a mysterious tropical island...

, the result of characters traveling back in time to prevent the crash of Oceanic Flight 815 apparently creates a parallel reality in which the Flight never crashed, rather than resetting time itself in the characters' original timeline. The show continued to show two "sets" of the characters following different destinies, until it was revealed in the series finale that there was really only one reality created by the characters themselves to assist themselves in leaving behind the physical world and passing on to an afterlife after their respective deaths.

The anime
Anime
is the Japanese abbreviated pronunciation of "animation". The definition sometimes changes depending on the context. In English-speaking countries, the term most commonly refers to Japanese animated cartoons....

 Turn A Gundam
Turn A Gundam
is a 50 episode anime series that aired between 1999 and 2000 on Japan's FNN networks and on the anime satellite television network, Animax, which was created for the Gundam Big Bang 20th Anniversary celebration...

attempted to combine all the parallel Gundam
Gundam
The is a metaseries of anime created by Sunrise studios that features giant robots called "Mobile Suits" ; usually the protagonist's MS will carry the name Gundam....

 universes (other incarnations of the series, with similar themes but differing stories and characters, that had played out at different times since the debut of the concept in the 1970s) of the metaseries in to one single reality.

The anime Neon Genesis Evangelion
Neon Genesis Evangelion
, commonly referred to as Evangelion, is a commercially and critically successful Japanese anime series that began airing in October 1995. The series was highly influential, and launched the Neon Genesis Evangelion franchise. It garnered several major animation awards...

features a parallel world in one of the final episodes. This parallel world is a sharp contrast to the harsh, dark "reality" of the show and presents a world where all the characters enjoy a much happier life. This parallel world would become the basis for the new Evangelion manga series Angelic Days
Neon Genesis Evangelion: Angelic Days
is a manga by Fumino Hayashi based on an original story by Gainax. It is an adaptation of the video game Girlfriend of Steel 2, and dramatizes the actions of the Instrumentality from the final episode of Neon Genesis Evangelion, which featured the show's cast in a high school romantic comedy in...

.

The anime Bakugan series in season 2 & 3 features another unverses where Dan and his team saves the day.They goes to another dimension or universe through a path way . Another universe has also other life forms and other types of technology.

In another anime Digimon
Digimon
, short for , is a Japanese media franchise encompassing digital toys, anime, manga and video games. The franchise's eponymous creatures are monsters of various forms living in a "Digital World", a parallel universe that originated from Earth's various communication networks.-Conception and...

series there is parallel universe called "digital world". The show's child protagonists meet digital monsters, or digimon, from this world and becomes partners and friends.

In the animated Disney series Darkwing Duck
Darkwing Duck
DarkWing Duck is an American animated television series produced by The Walt Disney Company that ran from 1991–1992 on both the syndicated programming block The Disney Afternoon and Saturday mornings on ABC. It featured the eponymous anthropomorphic duck superhero whose alter ego is mild-mannered...

, the title character's archenemy, Negaduck, comes from a parallel dimension called the Negaverse (not to be confused with the similarly named dimension in the Sailor Moon
Sailor Moon
Sailor Moon, known as , is a media franchise created by manga artist Naoko Takeuchi. Fred Patten credits Takeuchi with popularizing the concept of a team of magical girls, and Paul Gravett credits the series with "revitalizing" the magical-girl genre itself...

series).

In the Family Guy
Family Guy
Family Guy is an American animated television series created by Seth MacFarlane for the Fox Broadcasting Company. The series centers on the Griffins, a dysfunctional family consisting of parents Peter and Lois; their children Meg, Chris, and Stewie; and their anthropomorphic pet dog Brian...

episode, "Road to the Multiverse
Road to the Multiverse
"Road to the Multiverse" is the first episode of the eighth season of the animated comedy series Family Guy. Directed by Greg Colton and written by Wellesley Wild, the episode originally aired on Fox in the United States on September 27, 2009...

", Brian and Stewie get a look at life in other universes that are at the same time and place as Quahog, but under different conditions.

In the Star Trek: The Next Generation
Star Trek: The Next Generation
Star Trek: The Next Generation is an American science fiction television series created by Gene Roddenberry as part of the Star Trek franchise. Roddenberry, Rick Berman, and Michael Piller served as executive producers at different times throughout the production...

episode "Parallels", Lt. Worf
Worf
Worf, played by Michael Dorn, is a main character in Star Trek: The Next Generation and in seasons four to seven of Star Trek: Deep Space Nine. He also appears in the films based on The Next Generation. Worf is the first Klingon main character to appear in Star Trek, and has appeared in more Star...

 traveled to several parallel universes when his shuttlecraft went through a time space fissure.

The movie for Phineas and Ferb
Phineas and Ferb
Phineas and Ferb is an American animated television comedy series. Originally broadcast as a preview on August 17, 2007, on Disney Channel, the series follows Phineas Flynn and his English stepbrother Ferb Fletcher on summer vacation. Every day the boys embark on some grand new project, which...

 involves Phineas, Ferb, and Perry going to an alternate dimension of the Tri-state area.

In the episode "Adventure time
Adventure Time
Adventure Time was a local children's television show on WTAE-TV 4 in Pittsburgh, Pennsylvania, from 1959 to 1975. It was hosted by the late Paul Shannon, with guitarist Joe Negri and puppeteer Jim Martin...

" had a gender swapped universe episode.

As an ongoing subplot

Sometimes a television series will use parallel universes as an ongoing subplot. Star Trek: Deep Space Nine
Star Trek: Deep Space Nine
Star Trek: Deep Space Nine is a science fiction television series set in the Star Trek universe...

and Star Trek: Enterprise
Star Trek: Enterprise
Star Trek: Enterprise is a science fiction television series. It follows the adventures of humanity's first warp 5 starship, the Enterprise, ten years before the United Federation of Planets shown in previous Star Trek series was formed.Enterprise premiered on September 26, 2001...

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
Stargate SG-1
Stargate SG-1 is a Canadian-American adventure and military science fiction television series and part of Metro-Goldwyn-Mayer's Stargate franchise. The show, created by Brad Wright and Jonathan Glassner, is based on the 1994 feature film Stargate by Dean Devlin and Roland Emmerich...

, the fantasy/horror series Buffy the Vampire Slayer, Supernatural
Supernatural
The supernatural or is that which is not subject to the laws of nature, or more figuratively, that which is said to exist above and beyond nature...

and the romance/fantasy Lois & Clark: The New Adventures of Superman
Lois & Clark: The New Adventures of Superman
Lois & Clark: The New Adventures of Superman was a live-action American television series based on the Superman comic books...

.

Following the precedent set by Star Trek, these story arcs show alternative universes that have turned out "worse" than the "original" universe: in Stargate SG-1 the first two encountered parallel realities featured Earth being overwhelmed by an unstoppable Goa'uld
Goa'uld
The Goa'uld are a fictional symbiotic race of ancient astronauts from the American-Canadian military science fiction television franchise Stargate. The Goa'uld are parasites from the planet P3X-888, integrated within a host, most of the time human. The resulting creatures are a powerful race bent...

 onslaught; in Buffy, two episodes concern a timeline in which Buffy came to Sunnydale
Sunnydale
Sunnydale, California is the fictional setting for the U.S. television drama Buffy the Vampire Slayer. Series creator Joss Whedon conceived the town as a representation of a generic California city, as well as a narrative parody of the all-too-serene towns typical in traditional horror...

 too late to stop the vampires from taking control; Lois & Clark repeatedly visits an alternative universe where Clark Kent
Clark Kent
Clark Kent is a fictional character created by Jerry Siegel and Joe Shuster. Appearing regularly in stories published by DC Comics, he debuted in Action Comics #1 and serves as the civilian and secret identity of the superhero Superman....

's adoptive parents, Jonathan and Martha Kent, died when he was ten years of age, and Lois Lane
Lois Lane
Lois Lane is a fictional character, the primary love interest of Superman in the comic books of DC Comics. Created by writer Jerry Siegel and artist Joe Shuster, she first appeared in Action Comics #1 ....

 is also apparently dead. Clark eventually becomes Superman, with help from the "original" Lois Lane, but he is immediately revealed as Clark Kent and so has no life of his own.

In addition to following Star Trek's lead, showing the "evil" variants of the main storyline gives the writers an opportunity to show what is at stake by portraying the worst that could happen and the consequences if the protagonists fail or the importance of a character's presence. The latter could also be seen as the point of the alternative reality portrayed in the movie It's a Wonderful Life
It's a Wonderful Life
It's a Wonderful Life is a 1946 American Christmas drama film produced and directed by Frank Capra and based on the short story "The Greatest Gift" written by Philip Van Doren Stern....

.

Parallel universe-based series

There have been a few series where parallel universes were central to the series itself. Two examples are:
  • Sliders
    Sliders
    Sliders is an American science fiction television series. It was broadcast for five seasons, beginning in 1995 and ending in 2000. The series follows a group of travelers as they use a wormhole to "slide" between different parallel universes. The show was created by Robert K. Weiss and Tracy Tormé...

    , where a young man invents a worm-hole generator that allows travel to "alternative" Earths. Several characters travel across a series of "alternative" Earths, trying to get back to their home universe;
  • Charlie Jade
    Charlie Jade
    Charlie Jade is a science fiction television program filmed mainly in Cape Town, South Africa. It stars Jeffrey Pierce in the title role, as a detective from a parallel universe who finds himself trapped in our universe. This is a Canadian and South African co-production filmed in conjunction with...

    , in which the titular character is accidentally thrown into our universe and is looking for a way back to his own. The series features three universes - alpha, beta and gamma.


In 1986, Disney produced a pilot episode for an animated children's show about interdimensional travel called Fluppy Dogs.

In the TV series Fringe
Fringe (TV series)
Fringe is an American science fiction television series created by J. J. Abrams, Alex Kurtzman and Roberto Orci. The series follows a Federal Bureau of Investigation "Fringe Division" team based in Boston, Massachusetts under the supervision of Homeland Security...

, an ongoing subplot of the series is the loss of balance and the eventual collision of two universes and the moral ramifications of it.

"Source Code", is a 2011 American science fiction-techno-thriller film directed by Duncan Jones, written by Ben Ripley, starring Jake Gyllenhaal, Michelle Monaghan, Vera Farmiga, Russell Peters and Jeffrey Wright which is having the plot of Quantum reality and parallel universe concept.

Comic books

Parallel universes in modern comics have become particularly rich and complex, in large part due to the continual problem of continuity
Continuity (fiction)
In fiction, continuity is consistency of the characteristics of persons, plot, objects, places and events seen by the reader or viewer over some period of time...

 faced by the major two publishers, Marvel Comics
Marvel Comics
Marvel Worldwide, Inc., commonly referred to as Marvel Comics and formerly Marvel Publishing, Inc. and Marvel Comics Group, is an American company that publishes comic books and related media...

 and DC Comics
DC Comics
DC Comics, Inc. is one of the largest and most successful companies operating in the market for American comic books and related media. It is the publishing unit of DC Entertainment a company of Warner Bros. Entertainment, which itself is owned by Time Warner...

. The two publishers have used the multiverse
Multiverse (science)
The multiverse is the hypothetical set of multiple possible universes that together comprise everything that exists and can exist: the entirety of space, time, matter, and energy as well as the physical laws and constants that describe them...

 concept to fix problems arising from integrating characters from other publishers into their own canon, and from having major serial
Serial (literature)
In literature, a serial is a publishing format by which a single large work, most often a work of narrative fiction, is presented in contiguous installments—also known as numbers, parts, or fascicles—either issued as separate publications or appearing in sequential issues of a single periodical...

 protagonists having continuous histories lasting, as in the case of Superman
Superman
Superman is a fictional comic book superhero appearing in publications by DC Comics, widely considered to be an American cultural icon. Created by American writer Jerry Siegel and Canadian-born American artist Joe Shuster in 1932 while both were living in Cleveland, Ohio, and sold to Detective...

, over 70 years. Additionally, both publishers have used new alternative universes to re-imagine their own characters. (See Multiverse (DC Comics)
Multiverse (DC Comics)
The DC Multiverse is a fictional continuity construct that exists in stories published by comic book company DC Comics. The DC Multiverse consists of numerous worlds, most of them outside DC's main continuity, allowing writers the creative freedom to explore alternative versions of characters and...

and Multiverse (Marvel Comics)
Multiverse (Marvel Comics)
Within Marvel Comics, most tales take place within the fictional Marvel Universe, which in turn is part of a larger multiverse. Starting with issues of Captain Britain, the main continuity in which most Marvel storylines take place was designated Earth-616, and the multiverse was established as...

)

Because of this, comic books in general are one of the few entertainment mediums where the concept of parallel universes are a major and ongoing theme. DC in particular periodically revisits the idea in major crossover
Fictional crossover
A fictional crossover is the placement of two or more otherwise discrete fictional characters, settings, or universes into the context of a single story. They can arise from legal agreements between the relevant copyright holders, or because of unauthorized efforts by fans, or even amid common...

 storylines, such as Crisis on Infinite Earths
Crisis on Infinite Earths
Crisis on Infinite Earths is a 12-issue American comic book limited series and crossover event, produced by DC Comics in 1985 to simplify its then 50-year-old continuity...

and Infinite Crisis
Infinite Crisis
Infinite Crisis is a 2005 - 2006 comic book storyline published by DC Comics, consisting of an eponymous, seven-issue comic book limited series written by Geoff Johns and illustrated by Phil Jimenez, George Pérez, Ivan Reis, and Jerry Ordway, and a number of tie-in books...

, where Marvel has a series called What If...
What If (comics)
What If, sometimes rendered as What If...?, is the title of several comic book series published by Marvel Comics, exploring "the road not traveled" by its various characters...

that's devoted to exploring alternative realities, which sometimes impact the "main" universe's continuity. DC's version of "What If..." is the Elseworlds imprint.

Recently DC Comics series 52
52 (comic book)
52 was a weekly American comic book limited series published by DC Comics that debuted on May 10, 2006, one week after the conclusion of the seven-issue Infinite Crisis. The series was written by Geoff Johns, Grant Morrison, Greg Rucka, and Mark Waid with layouts by Keith Giffen...

heralded the return of the Multiverse. 52 was a mega-crossover event tied to Infinite Crisis which was the sequel to the 1980s Crisis on Infinite Earths. The aim was to yet again address many of the problems and confusions brought on by the Multiverse in the DCU. Now 52 Earths exist and including some Elseworld tales such as Kingdom Come
Kingdom Come (comic book)
Kingdom Come is a four-issue comic book mini-series published in 1996 by DC Comics. It was written by Alex Ross and Mark Waid and painted in gouache by Ross, who also developed the concept from an original idea...

, DC's imprint
Imprint
In the publishing industry, an imprint can mean several different things:* As a piece of bibliographic information about a book, it refers to the name and address of the book's publisher and its date of publication as given at the foot or on the verso of its title page.* It can mean a trade name...

 Wildstorm Comics
Wildstorm
WildStorm Productions, or simply WildStorm, published American comic books. Originally an independent company established by Jim Lee and further expanded upon in subsequent years by other creators, WildStorm became a publishing imprint of DC Comics in 1999...

 and an Earth devoted to the Charlton Comics
Charlton Comics
Charlton Comics was an American comic book publishing company that existed from 1946 to 1985, having begun under a different name in 1944. It was based in Derby, Connecticut...

 heroes of DC. Countdown and Countdown Presents: The Search for Ray Palmer and the upcoming Tales of the Multiverse stories expand upon this new Multiverse.

Marvel has also had many large crossover events which depicted an alternative universe, many springing from events in the X-Men
X-Men
The X-Men are a superhero team in the . They were created by writer Stan Lee and artist Jack Kirby, and first appeared in The X-Men #1...

 books, such as Days of Future Past
Days of Future Past
"Days of Future Past" is a popular storyline in the Marvel Comics comic book The Uncanny X-Men issues #141 and #142, published in 1981. It deals with a dystopian alternate future in which mutants are incarcerated in internment camps...

, the seminal Age Of Apocalypse
Age of Apocalypse
"Age of Apocalypse" is a 1995 - 1996 comic book crossover storyline published in the X-Men franchise of books by Marvel Comics. The Age of Apocalypse briefly replaced the universe of Earth-616, although it was later retconned as having occurred in the alternate universe of Earth-295, it had...

, and 2006's House Of M
House of M
House of M is an eight-issue comic book limited series and crossover storyline published by Marvel Comics in 2005. Written by Brian Michael Bendis and illustrated by Olivier Coipel, its first issue debuted in June 2005 as a follow-up to the events of the Planet X and Avengers Disassembled...

. In addition the Squadron Supreme
Squadron Supreme
The Squadron Supreme is a fictional superhero team that appears in comic books published by Marvel Comics. The Squadron Supreme first appeared in Avengers #85 - 86 The Squadron Supreme is a fictional superhero team that appears in comic books published by Marvel Comics. The Squadron Supreme first...

 is a DC inspired Marvel Universe that has been used several times, often crossing over into the mainstream Universe in the Avengers
Avengers (comics)
The Avengers is a fictional team of superheroes, appearing in magazines published by Marvel Comics. The team made its debut in The Avengers #1 The Avengers is a fictional team of superheroes, appearing in magazines published by Marvel Comics. The team made its debut in The Avengers #1 The Avengers...

 comic. Exiles
Exiles (Marvel Comics)
The Exiles are a group of fictional characters that feature in three Marvel Comics series, Exiles, New Exiles, and Exiles vol. 2. The Exiles consists of characters from different dimensions, or realities, which have been removed from time and space in order to correct problems in various alternate...

 is an offshoot of the X-Men
X-Men
The X-Men are a superhero team in the . They were created by writer Stan Lee and artist Jack Kirby, and first appeared in The X-Men #1...

franchsie that allows characters to hop from one alternative reality to another, leaving the original, main Marvel Universe
Marvel Universe
The Marvel Universe is the shared fictional universe where most comic book titles and other media published by Marvel Entertainment take place, including those featuring Marvel's most familiar characters, such as Spider-Man, the Hulk, the X-Men, and the Avengers.The Marvel Universe is further...

 intact. The Marvel UK
Marvel UK
Marvel UK was an imprint of Marvel Comics formed in 1972 to reprint US produced stories for the British weekly comic market, though it later did produce original material by British creators such as Alan Moore, John Wagner, Dave Gibbons, Steve Dillon and Grant Morrison.Panini Comics obtained the...

 line has long had multiverse stories including the Jaspers' Warp
Jaspers' Warp
"Jaspers' Warp", also known as "Crooked World", was a Marvel UK storyline featuring primarily the character Captain Britain. It was originally published between 1982 and 1984 in Marvel Superheroes, #387-388, The Daredevils, #1-11 and The Mighty World Of Marvel, volume 2, #7-13.The story is a...

 storyline of Captain Britain
Captain Britain
Captain Britain , briefly known as Britannic, is a fictional character, a superhero appearing in the comic books published by Marvel Comics. Created by Chris Claremont and Herb Trimpe, he first appeared in Captain Britain Weekly, #1...

's first series (it was here that the designation Earth-616
Earth-616
In the fictional Marvel Comics multiverse, Earth-616 or Earth 616 is the name used to identify the primary continuity in which most Marvel Comics titles take place.-Origin of Earth-616:...

 was first applied to the mainstream Marvel Universe
Marvel Universe
The Marvel Universe is the shared fictional universe where most comic book titles and other media published by Marvel Entertainment take place, including those featuring Marvel's most familiar characters, such as Spider-Man, the Hulk, the X-Men, and the Avengers.The Marvel Universe is further...

).

Marvel Comics, as of 2000, launched their most popular parallel universe, the Ultimate Universe
Ultimate Marvel
Ultimate Marvel is an imprint of comic books published by Marvel Comics, featuring reimagined and updated versions of the company's superhero characters, including Spider-Man, the X-Men, the Avengers, and the Fantastic Four. The imprint was launched in 2000 with the publication of the series...

. It is a smaller subline to the mainstream titles and features Ultimate Spider-Man
Ultimate Spider-Man
Ultimate Spider-Man was a superhero comic book series that was published by Marvel Comics from 2000 to 2009. The series is a modernized re-imagining of Marvel's long-running Spider-Man comic book franchise as part of its Ultimate Marvel imprint...

, Ultimate X-Men
Ultimate X-Men
Ultimate X-Men is a superhero comic book series that was published by Marvel Comics from 2001 to 2009. The series is a modernized re-imagining of Marvel's long-running X-Men comic book franchise as part of its Ultimate Marvel imprint...

, Ultimate Fantastic Four
Ultimate Fantastic Four
Ultimate Fantastic Four is a superhero comic book series published by Marvel Comics. The series is a modernized re-imagining of Marvel's long-running Fantastic Four comic book franchise as part of its Ultimate Marvel imprint...

 and the Ultimates
Ultimates
The Ultimates is a fictional group of superheroes that appear in comic books published by Marvel Comics. The team was created by writer Mark Millar and artist Bryan Hitch, and first appeared in The Ultimates #1 , as part of the company's Ultimate Marvel imprint...

 (their "Avengers"). The line in many ways both inspired and was inspired by aspects of the new movie franchises in addition to creating younger versions of the modern heroes.

The graphic novel Watchmen
Watchmen
Watchmen is a twelve-issue comic book limited series created by writer Alan Moore, artist Dave Gibbons, and colourist John Higgins. The series was published by DC Comics during 1986 and 1987, and has been subsequently reprinted in collected form...

 is set in an alternate history in 1985 where superheroes exist, the Vietnam War was won by the United States, and Richard Nixon
Richard Nixon
Richard Milhous Nixon was the 37th President of the United States, serving from 1969 to 1974. The only president to resign the office, Nixon had previously served as a US representative and senator from California and as the 36th Vice President of the United States from 1953 to 1961 under...

 is in his fifth term as President of the United States. The Soviet Union and the United States are still in a "Cold War" with a threat of a Nuclear War impending.

In 1973 Tammy
Tammy (comics)
Tammy was a weekly British comic for girls published by Fleetway in London from 1971 to 1984, at which point it merged with Girl. Other titles which had merged with Tammy before then include June, Jinty, and Misty ....

 published The Clock and Cluny Jones, where a mysterious grandfather clock hurls bully Cluny Jones into a harsh alternate reality where she becomes the bullied. This story was reprinted in Misty
Misty (comics)
Misty was a British comic for girls published by Fleetway in London from 4th Feb 1978 until 1984, after merging with Tammy on 19 January 1980. It consisted of a collection of many small strips, with the stories themselves normally being three or four pages long...

 annual 1985 as Grandfather's Clock.

In 1978 Misty
Misty (comics)
Misty was a British comic for girls published by Fleetway in London from 4th Feb 1978 until 1984, after merging with Tammy on 19 January 1980. It consisted of a collection of many small strips, with the stories themselves normally being three or four pages long...

 published The Sentinels. The Sentinels were two crumbling apartment blocks that connected the mainstream world with an alternate reality where Hitler
Adolf Hitler
Adolf Hitler was an Austrian-born German politician and the leader of the National Socialist German Workers Party , commonly referred to as the Nazi Party). He was Chancellor of Germany from 1933 to 1945, and head of state from 1934 to 1945...

 conquered Britain in 1940.

In 1981 Jinty published Worlds Apart. Six girls experience alternate worlds ruled by greed, sports-mania, vanity, crime, intellectualism, and fear. These are in fact their dream worlds becoming real after they are knocked out by a mysterious gas from a chemical tanker that crashed into their school. In 1977 Jinty also published Land of No Tears where a lame girl travels to a future world where people with things wrong with them are cruelly treated, and emotions are banned.

Video games

In the 1999 role-playing game Outcast where a probe is sent to a parallel universe and is attacked by an "entity". Cutter Slade must escort a team of scientists across to the other world to retrieve and repair the damaged probe before the earth is consumed by a black hole.

In the survival horror video game series Silent Hill
Silent Hill
is a survival horror video game series consisting of seven installments published by Konami and its subsidiary Konami Digital Entertainment. The first four games in the series, Silent Hill, Silent Hill 2, 3 and 4, have been developed by an internal factor, Team Silent...

, the town of Silent Hill fluctuates between the normal world, a foggy version of the town and a dark and dilapidated version of the town called the "Other World".

In the 1993 adventure PC game Myst
Myst
Myst is a graphic adventure video game designed and directed by the brothers Robyn and Rand Miller. It was developed by Cyan , a Spokane, Washington––based studio, and published and distributed by Brøderbund. The Millers began working on Myst in and released it for the Mac OS computer on September...

, the unnamed protagonist travels to multiple alternate worlds through the use of special books, which describe a world within and transport the user to that world when a window on the front page is touched.

In the 1996 adventure PC game 9: The Last Resort
9: The Last Resort
9: The Last Resort is a 1996 adventure computer game developed by Tribeca Interactive. The game was produced by Robert De Niro and Jane Rosenthal, and sported an all-star cast of voice-artists including Cher, James Belushi, Christopher Reeve, Tress MacNeille, Ellen Degeneres and two members of...

, after resolving several mind-blowing and unique puzzles, the player gets past "The Tiki Guards" and a door to "The Void" opens up - actually a room to another universe which houses the entirety of space.

Both titles of the When They Cry Visual Novel series (Higurashi
Higurashi no Naku Koro ni
, known simply as When They Cry for the North American release of the anime adaptation, is a Japanese murder mystery dōjin soft sound novel series produced by 07th Expansion. The games are built on the NScripter game engine and are playable on Microsoft Windows PCs...

 and Umineko for short) contain the concept of parallel worlds. These series both involve some kind of murder mystery occurring. As soon as the main character has 'lost', another parallel world, called a Fragment, is chosen to be observed. This continues until the entire mystery is solved.

The video game The Legend of Cheese: A Link to the Past features a dark and twisted parallel version of Hyrule
Hyrule
The fictional universe depicted in The Legend of Zelda series of video games consists of a variety of lands, the most commonly appearing of these being , and was created by Japanese video game developer Shigeru Miyamoto.-Hyrule:...

 called the "Dark World".

The story of Chrono Cross
Chrono Cross
is a role-playing video game developed and published by Square for the PlayStation video game console. It is the sequel to Chrono Trigger, which was released in 1995 for the Super Nintendo Entertainment System...

centers around travel between two alternate timelines, the original or "Home" universe and "Another World" which is a branch
Many-worlds interpretation
The many-worlds interpretation is an interpretation of quantum mechanics that asserts the objective reality of the universal wavefunction, but denies the actuality of wavefunction collapse. Many-worlds implies that all possible alternative histories and futures are real, each representing an...

 created by the actions of the heroes of the game's predecessor, Chrono Trigger
Chrono Trigger
is a role-playing video game developed and published by Square for the Super Nintendo Entertainment System in 1995. Chrono Triggers development team included three designers that Square dubbed the "Dream Team": Hironobu Sakaguchi, the creator of Square's Final Fantasy series; Yuji Horii, a...

.

The video game series Legacy of Kain
Legacy of Kain
Legacy of Kain is a series of action-adventure video games developed initially by Silicon Knights in association with Crystal Dynamics. After a legal battle, Crystal Dynamics continued the series without Silicon Knights and Eidos Interactive became the publisher...

is played through several realms and timelines.

The video game Sudeki
Sudeki
Sudeki is an action role-playing game which was first released on the Xbox exclusively and ported later for Microsoft Windows.The game was developed by UK based Climax Group. The PC porting was done as well by Climax and published by Zoo Digital Publishing. The producer of the game was Mark Simmons...

is set in a realm of light and a parallel realm of darkness.

The video game The Elder Scrolls IV: Oblivion
The Elder Scrolls IV: Oblivion
The Elder Scrolls IV: Oblivion is a single-player action role-playing video game developed by Bethesda Game Studios and published by Bethesda Softworks and the Take-Two Interactive subsidiary 2K Games...

features an alternative hellish world called "Oblivion", as well as a painting you can climb into and a quest where you enter a dream world.

The video game The Legend of Zelda: Majora's Mask
The Legend of Zelda: Majora's Mask
is an action-adventure video game developed by Nintendo's Entertainment Analysis and Development division for the Nintendo 64. It was released in Japan on April 27, 2000, North America on October 26, 2000, and Europe on November 17, 2000. The game sold approximately 314,000 copies during its first...

takes place in Termina, a parallel world to Hyrule
Hyrule
The fictional universe depicted in The Legend of Zelda series of video games consists of a variety of lands, the most commonly appearing of these being , and was created by Japanese video game developer Shigeru Miyamoto.-Hyrule:...

.

The video game The Darkness
The Darkness (video game)
The Darkness is a first-person shooter video game, developed by Starbreeze Studios and published by 2K Games for Xbox 360 and Playstation 3. It was released on June 25, 2007 in North America and on June 20, 2007 in Europe. The video game is based on the comic book of the same title...

pivots around a world of darkness you travel to when you die, which is occupied by World War 1 soldiers.

The video game Metroid Prime 2: Echoes
Metroid Prime 2: Echoes
Metroid Prime 2: Echoes, known as in Japan, is a first-person, action-adventure video game developed by Retro Studios and published by Nintendo for the GameCube video game console. It is the seventh game in the Metroid series, a direct sequel to Metroid Prime, and the first game in the series with...

involves a world, "Aether", having an alternate self in the, "Dark" realm, universe, or dimension. The protagonist, Samus, finds out that she just dropped in to a hopeless war for the Luminoth, the dominant species of Light Aether against the Ing, the dominant species of Dark Aether. She also finds her counterpart, Dark Samus or Metroid Prime's essence inside Samus's Phazon Suit.

The video game Crash Twinsanity features Crash,Cortex,and Nina traveling to the "10th dimension" which could also be a parelell universe (suggesting by the theme and how everything seems to be opposite)

The video game Minecraft
Minecraft
Minecraft is a sandbox-building independent video game written in Java originally by Swedish creator Markus "Notch" Persson and now by his company, Mojang, formed from the proceeds of the game. It was released as an alpha on May 17, 2009, with a beta version on December 20, 2010...

features an alternate dimension called "The Nether", that includes a 'hell' like theme. It also contains a second alternate dimension called "The End," home world of the Endermen, a type of monster that spawns rarely in the main world.

The video game Persona 2: Eternal Punishment (The second part of the Persona 2) takes place in an alternate universe called "This Side" where in the events of Innocent Sin did not take place and the characters have never met in the past.

In the video game Epic Mickey
Epic Mickey
Epic Mickey is a 2010 Mickey Mouse action-adventure platforming video game designed by Warren Spector and developed by Junction Point Studios for the Wii console...

you travel through old Mickey Mouse movie reels.

See also

  • Alternative universe (fan fiction)
    Alternative universe (fan fiction)
    An alternative universe , commonly abbreviated as AU, is a type or form of in which canonical facts of setting or characterization in the universe being explored or written about are deliberately changed.Stories that fall into this definition are usually what-ifs, where possibilities arising from...

  • Imaginary world
  • List of fiction employing parallel universes
  • World as Myth
    World as Myth
    The idea of World as Myth was created by science fiction writer Robert A. Heinlein in his book The Number of the Beast. According to this idea, myths and fictional worlds exist as an almost infinite number of universes which are parallel to our own...

  • Multiverse
    Multiverse
    The multiverse is the hypothetical set of multiple possible universes that together comprise all of reality.Multiverse may also refer to:-In fiction:* Multiverse , the fictional multiverse used by DC Comics...


External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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