A parallel universe, also known as a parallel dimension, alternate universe, or alternate reality, is a hypothetical self-contained plane of existence, co-existing with one's own. The sum of all potential parallel universes that constitute

reality Reality is the sum or aggregate of all that is real or existent within a system, as opposed to that which is only imaginary. The term is also used to refer to the ontological status of things, indicating their existence. In physical terms, r ...

is often called a " multiverse". While the four terms are generally synonymous and can be used interchangeably in most cases, there is sometimes an additional connotation implied with the term "alternate universe/reality" that implies that the reality is a variant of our own, with some overlap with the similarly named alternate history. Fiction has long borrowed an idea of "another world" from

myth Myth is a folklore genre consisting of Narrative, narratives that play a fundamental role in a society, such as foundational tales or Origin myth, origin myths. Since "myth" is widely used to imply that a story is not Objectivity (philosophy), ...

legend A legend is a Folklore genre, genre of folklore that consists of a narrative featuring human actions, believed or perceived, both by teller and listeners, to have taken place in human history. Narratives in this genre may demonstrate human valu ...

and

religion Religion is usually defined as a social- cultural system of designated behaviors and practices, morals, beliefs, worldviews, texts, sanctified places, prophecies, ethics, or organizations, that generally relates humanity to supernatural, ...

. Heaven, Hell, Olympus, and

Valhalla In Norse mythology Valhalla (;) is the anglicised name for non, Valhǫll ("hall of the slain").Orchard (1997:171–172) It is described as a majestic hall located in Asgard and presided over by the god Odin. Half of those who die in combat e ...

are all "alternative universes" different from the familiar material realm.

Plato Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...

reflected deeply on the parallel realities, resulting in

Platonism Platonism is the philosophy of Plato and philosophical systems closely derived from it, though contemporary platonists do not necessarily accept all of the doctrines of Plato. Platonism had a profound effect on Western thought. Platonism at le ...

, in which the upper reality is perfect while the lower earthly reality is an imperfect shadow of the heavenly. The concept is also found in ancient Hindu mythology, in texts such as the Puranas, which expressed an infinite number of universes, each with its own gods. Similarly in

Persian literature Persian literature ( fa, ادبیات فارسی, Adabiyâte fârsi, ) comprises oral compositions and written texts in the Persian language and is one of the world's oldest literatures. It spans over two-and-a-half millennia. Its sources h ...

, "The Adventures of Bulukiya," a tale in the '' One Thousand and One Nights'', describes the

protagonist A protagonist () is the main character of a story. The protagonist makes key decisions that affect the plot, primarily influencing the story and propelling it forward, and is often the character who faces the most significant obstacles. If a st ...

Bulukiya learning of alternative worlds/universes that are similar to but still distinct from his own. One of the first

science fiction Science fiction (sometimes shortened to Sci-Fi or SF) is a genre of speculative fiction which typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel unive ...

examples is

Murray Leinster Murray Leinster (June 16, 1896 – June 8, 1975) was a pen name of William Fitzgerald Jenkins, an American writer of genre fiction, particularly of science fiction. He wrote and published more than 1,500 short stories and articles, 14 movie ...

's short story, ''Sidewise in Time'', in which portions of alternative universes replace corresponding geographical regions in this universe. ''Sidewise in Time'' describes it in the manner that similar to requiring both

longitude Longitude (, ) is a geographic coordinate that specifies the east– west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek lette ...

and

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...

coordinates in order to mark your location on Earth, so too does time: traveling along latitude is akin to

time travel Time travel is the concept of movement between certain points in time, analogous to movement between different points in space by an object or a person, typically with the use of a hypothetical device known as a time machine. Time travel is a ...

moving through past, present and future, while traveling along longitude is to travel perpendicular to time and to other realities, hence the name of the short story. Thus, another common term for a parallel universe is "another dimension," stemming from the idea that if the 4th

dimension In physics and mathematics, the dimension of a mathematical 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 (1D) because only one coor ...

is time, the 5th dimension—a direction at a right angle to the fourth—is an alternate reality. In modern literature, parallel universes can be roughly divided into two categories: to allow for stories where elements that would ordinarily violate the laws of nature; and to serve as a starting point for speculative fiction, asking oneself "What if

vent Vent or vents may refer to: Science and technology Biology *Vent, the cloaca region of an animal * Vent DNA polymerase, a thermostable DNA polymerase Geology *Hydrothermal vent, a fissure in a planet's surface from which geothermally heated wate ...

turned out differently?". Examples of the former include

Terry Pratchett Sir Terence David John Pratchett (28 April 1948 – 12 March 2015) was an English humourist, satirist, and author of fantasy novels, especially comical works. He is best known for his '' Discworld'' series of 41 novels. Pratchett's first no ...

's ''

Discworld ''Discworld'' is a comic fantasy"Humorous Fantasy" in David Pringle, ed., ''The Ultimate Encyclopedia of Fantasy'' (pp.31-33). London, Carlton,2006. book series written by the English author Terry Pratchett, set on the Discworld, a flat ...

'' and

C. S. Lewis Clive Staples Lewis (29 November 1898 – 22 November 1963) was a British writer and Anglican lay theologian. He held academic positions in English literature at both Oxford University (Magdalen College, 1925–1954) and Cambridge Univers ...

's ''The Chronicles of Narnia'', while examples of the latter include

Harry Turtledove Harry Norman Turtledove (born June 14, 1949) is an American author who is best known for his work in the genres of alternate history, historical fiction, fantasy, science fiction, and mystery fiction. He is a student of history and completed ...

's ''Worldwar'' series. A parallel universe—or more specifically, continued interaction between the parallel universe and our own—may serve as a central plot point, or it may simply be mentioned and quickly dismissed, having served its purpose of establishing a realm unconstrained by realism. The aforementioned ''Discworld'', for example, only very rarely mentions our world or any other worlds, as Pratchett set the books in a parallel universe instead of "our" reality to allow for

magic Magic or Magick most commonly refers to: * Magic (supernatural), beliefs and actions employed to influence supernatural beings and forces * Ceremonial magic, encompasses a wide variety of rituals of magic * Magical thinking, the belief that unrela ...

on the Disc. ''The Chronicles of Narnia'' also utilizes to a lesser extent the idea of parallel universes is brought up but only briefly mentioned in the introduction and ending, its main purpose to bring the

from "our" reality to the setting of the books.

Science fiction

While technically incorrect, and looked down upon by hard science-fiction fans and authors, the idea of another "

" has become synonymous with the term "parallel universe". The usage is particularly common in

movies A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, feelings, beauty, or atmosphere ...

, television and comic books and much less so in modern prose science fiction. The idea of a parallel world was popularized in comic books with the publication of ''The Flash'' #123, ''Flash of Two Worlds'' in 1961. In written science fiction, "new dimension" more commonly—and more accurately—refer to additional

coordinate axes A Cartesian coordinate system (, ) in a plane is a coordinate system that specifies each point uniquely by a pair of numerical coordinates, which are the signed distances to the point from two fixed perpendicular oriented lines, measured i ...

, 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. Flatland cover detail

In 1884,

Edwin A. Abbott Edwin Abbott Abbott (20 December 1838 – 12 October 1926) was an English schoolmaster, theologian, and Anglican priest, best known as the author of the novella ''Flatland'' (1884). Biography Edwin Abbott Abbott was the eldest son of ...

wrote the seminal novel exploring this concept called '' Flatland: A Romance of Many Dimensions''. 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 yi, יצחק אזימאװ , birth_date = , birth_place = Petrovichi, Russian SFSR , spouse = , relatives = , children = 2 , death_date = , death_place = Manhattan, New York City, U.S. , nationality = Russian (1920–1922)Soviet (192 ...

, in his foreword to the Signet Classics 1984 edition, described ''Flatland'' as "The best introduction one can find into the manner of perceiving dimensions". In 1895, ''

The Time Machine ''The Time Machine'' is a science fiction novella by H. G. Wells, published in 1895. The work is generally credited with the popularization of the concept of time travel by using a vehicle or device to travel purposely and selectively for ...

'' by

H. G. Wells Herbert George Wells"Wells, H. G."
Revised 18 May 2015. ''

four-dimensional A four-dimensional space (4D) is a mathematical extension of the concept of three-dimensional or 3D space. Three-dimensional space is the simplest possible abstraction of the observation that one only needs three numbers, called ''dimensions'', ...

model of classical physics 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'' is an 1895 novel by H. G. Wells. With an angel—a creature of fantasy unlike a religious angel—as protagonist and taking place in contemporary England, the book could be classified as contemporary fantasy, although t ...

'' and '' Men Like Gods'', an idea proposed by the astronomer

Simon Newcomb Simon Newcomb (March 12, 1835 – July 11, 1909) was a Canadian–American astronomer, applied mathematician, and autodidactic polymath. He served as Professor of Mathematics in the United States Navy and at Johns Hopkins University. Born in N ...

, 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'' is a British science fiction television series broadcast by the BBC since 1963. The series depicts the adventures of a Time Lord called the Doctor, an extraterrestrial being who appears to be human. The Doctor explores the u ...

'', the Doctor accidentally enters a parallel universe while attempting to repair the

TARDIS The TARDIS (; acronym for "Time And Relative Dimension In Space") is a fictional hybrid of the time machine and spacecraft that appears in the British science fiction television series ''Doctor Who'' and its various spin-offs. Its exterior a ...

console in "

Inferno Inferno may refer to: * Hell, an afterlife place of suffering * Conflagration, a large uncontrolled fire Film * ''L'Inferno'', a 1911 Italian film * Inferno (1953 film), ''Inferno'' (1953 film), a film noir by Roy Ward Baker * Inferno (1973 fi ...

Douglas Adams Douglas Noel Adams (11 March 1952 – 11 May 2001) was an English author and screenwriter, best known for ''The Hitchhiker's Guide to the Galaxy''. Originally a 1978 The Hitchhiker's Guide to the Galaxy (radio series), BBC radio comedy, ''The H ...

, in the last book of the ''

Hitchhiker's Guide to the Galaxy ''The Hitchhiker's Guide to the Galaxy'' (sometimes referred to as ''HG2G'', ''HHGTTG'', ''H2G2'', or ''tHGttG'') is a comedy science fiction franchise created by Douglas Adams. Originally a 1978 radio comedy broadcast on BBC Radio 4, it w ...

'' series, ''

Mostly Harmless ''Mostly Harmless'' is a 1992 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 edition as "The fifth book in the increasingly inaccurately named Hitchhikers ...

'', uses the idea of

probability Probability is the branch of mathematics concerning numerical descriptions of how likely an Event (probability theory), event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and ...

as an extra

axis An axis (plural ''axes'') is an imaginary line around which an object rotates or is symmetrical. Axis may also refer to: Mathematics * Axis of rotation: see rotation around a fixed axis * Axis (mathematics), a designator for a Cartesian-coordinat ...

in addition to the classical four dimensions of space and time similar to the

many-worlds interpretation The many-worlds interpretation (MWI) is an interpretation of quantum mechanics that asserts that the universal wavefunction is objectively real, and that there is no wave function collapse. This implies that all possible outcomes of quantum ...

quantum physics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, qua ...

, although according to the novel they were more a model to capture the continuity of space, time and probability.

Robert A. Heinlein Robert Anson Heinlein (; July 7, 1907 – May 8, 1988) was an American science fiction author, aeronautical engineer, and naval officer. Sometimes called the "dean of science fiction writers", he was among the first to emphasize scientific accu ...

, in '' The Number of the Beast'', postulated a six-dimensional universe. In addition to the three spatial dimensions, he invoked

symmetry Symmetry (from grc, συμμετρία "agreement in dimensions, due proportion, arrangement") in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, "symmetry" has a more precise definit ...

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 In science fiction, hyperspace (also known as nulspace, subspace, overspace, jumpspace and similar terms) is a concept relating to higher dimensions as well as parallel universes and a faster-than-light (FTL) method of interstellar travel. ...

. 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 (also FTL, superluminal or supercausal) travel and communication are the conjectural propagation of matter or information faster than the speed of light (). The special theory of relativity implies that only particles with zero ...

shortcut for

interstellar travel Interstellar travel is the hypothetical travel of spacecraft from one star system, solitary star, or planetary system to another. Interstellar travel is expected to prove much more difficult than interplanetary spaceflight due to the vast diffe ...

. Rationales for this form of hyperspace vary from work to work, but the two common elements are: #It is possible to enter and exit from this hyperspace with reasonable ease. #There is reason to enter and exit hyperspace rather than travel conventionally (in most settings, 'hyperspace' is considered a faster form of travel). Sometimes "hyperspace" is used to refer to the concept of additional

. 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 A wormhole ( Einstein-Rosen bridge) is a hypothetical structure connecting disparate points in spacetime, and is based on a special solution of the Einstein field equations. A wormhole can be visualized as a tunnel with two ends at separate p ...

.) While the use of hyperspace is common, it is mostly used as a

plot device A plot device or plot mechanism is any technique in a narrative used to move the plot forward. A clichéd plot device may annoy the reader and a contrived or arbitrary device may confuse the reader, causing a loss of the suspension of disbelie ...

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

Time travel Time travel is the concept of movement between certain points in time, analogous to movement between different points in space by an object or a person, typically with the use of a hypothetical device known as a time machine. Time travel is a ...

can result in multiple universes if a time traveller can change the past. In one interpretation, alternative histories as a result of time travel are not parallel universes: while multiple parallel universes can co-exist simultaneously, only one history or alternative history can exist at any one moment, as alternative history usually involves, in essence, overriding the original timeline with a new one. As a result, travel between alternative histories is not possible without reverting the timeline back to the original. There are exceptions to the above, and an alternate history doesn't necessarily overwrite the old one. There are no rules written in stone regarding this. Modern ideas of time travel pose the idea of branching timelines, such as the 2009 '' Star Trek'' reboot and '' Avengers: Endgame''. Technically, if a timeline is not explicitly stated to have been erased, it is still there. Parallel universes as a result of time travel can serve simply as the backdrop, or it may be a central plot point. ''

The Guns of the South ''The Guns of the South'' is an alternate history novel set during the American Civil War by Harry Turtledove. It was released in the United States on September 22, 1992. The story deals with a group of time-traveling white supremacist member ...

'' by

, where the Confederate Army is given thousands of

AK-47 The AK-47, officially known as the ''Avtomat Kalashnikova'' (; also known as the Kalashnikov or just AK), is a gas-operated assault rifle that is chambered for the 7.62×39mm cartridge. Developed in the Soviet Union by Russian small-arms d ...

rifles and ends up winning the

American Civil War The American Civil War (April 12, 1861 – May 26, 1865; also known by other names) was a civil war in the United States. It was fought between the Union ("the North") and the Confederacy ("the South"), the latter formed by states th ...

, is a good example of the former, while

Fritz Leiber Fritz Reuter Leiber Jr. ( ; December 24, 1910 – September 5, 1992) was an American writer of fantasy, horror, and science fiction. He was also a poet, actor in theater and films, playwright, and chess expert. With writers such as Rober ...

's novel '' The Big Time'' where a war between two

alternative future Time travel is a common theme in fiction, mainly since the late 19th century, and has been depicted in a variety of media, such as literature, television, film, and advertisements. The concept of time travel by mechanical means was popularized ...

s manipulating history to create a timeline that results in or realizes their own world is a good example of the latter.

Multiple worlds and time travel

Subscribing to the

, alternative histories in fiction can arise as a natural phenomenon of the universe. In these works, the idea is that each choice every person makes, each leading to a different result, both occur, so when a person decides between

jam Jam is a type of fruit preserve. Jam or Jammed may also refer to: Other common meanings * A firearm malfunction * Block signals ** Radio jamming ** Radar jamming and deception ** Mobile phone jammer ** Echolocation jamming Arts and ente ...

butter Butter is a dairy product made from the fat and protein components of churned cream. It is a semi-solid emulsion at room temperature, consisting of approximately 80% butterfat. It is used at room temperature as a spread, melted as a condimen ...

on his

toast Toast most commonly refers to: * Toast (food), bread browned with dry heat * Toast (honor), a ritual in which a drink is taken Toast may also refer to: Places * Toast, North Carolina, a census-designated place in the United States Books * '' ...

, two universes are created: one where that person chose jam, and another where that person chose butter. The concept of "sidewise" time travel, a term taken from Murray Leinster's "

Sidewise in Time "Sidewise in Time" is a science fiction short story by American writer Murray Leinster that was first published in the June 1934 issue of ''Astounding Stories''. "Sidewise in Time" served as the title story for Leinster's second story collection ...

", is used to allow characters to pass through many different alternative histories, all descendant from some common branch point. Often, worlds that are more 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 Henry Beam Piper (March 23, 1904 – ) was an American science fiction writer. 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" alt ...

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 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 diplomat in the United States Foreign Service. His older brother March Laumer was ...

used the same concept of "sideways" time travel in his 1962 novel ''

Worlds of the Imperium ''Worlds of the Imperium'' is a science fiction novel by American writer Keith Laumer. It originally appeared in ''Fantastic (magazine), Fantastic Stories of the Imagination'' between February and April 1961. The following year it was published b ...

''. More recently, novels such as Frederik Pohl's ''

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 The novel proposes invasions from al ...

'' and Neal Stephenson's ''

Anathem ''Anathem'' is a science fiction novel by American writer Neal Stephenson, published in 2008. Major themes include the many-worlds interpretation of quantum mechanics and the philosophical debate between Platonic realism and nominalism. Plot sum ...

'' explore human-scale readings of the "many worlds" interpretation, postulating that historical events or human consciousness spawns or allows "travel" among alternative universes. Universe 'types' frequently explored in sidewise and alternative history works include worlds whose Nazis won the Second World War, as in ''

The Man in the High Castle ''The Man in the High Castle'' (1962), by Philip K. Dick, is an alternative history novel wherein the Axis Powers won World War II. The story occurs in 1962, fifteen years after the end of the war in 1947, and depicts the political intrigues b ...

'' by Philip K. Dick, '' SS-GB'' by

Len Deighton Leonard Cyril Deighton (; born 18 February 1929) is a British author. His publications have included cookery books, history and military history, but he is best known for his spy novels. After completing his national service in the Royal Air Fo ...

, and ''

Fatherland A homeland is a place where a cultural, national, or racial identity has formed. The definition can also mean simply one's country of birth. When used as a proper noun, the Homeland, as well as its equivalents in other languages, often has ethn ...

'' by Robert Harris, and worlds whose Roman Empire never fell, as in ''

Roma Eterna ''Roma Eterna'' is a science fiction fixup novel by American writer Robert Silverberg, published in 2003, which presents an alternative history in which the Roman Empire survives to the present day. Each of the ten chapters was first published as ...

'' by

Robert Silverberg Robert Silverberg (born January 15, 1935) is an American author and editor, best known for writing science fiction. He is a multiple winner of both Hugo and Nebula Awards, a member of the Science Fiction and Fantasy Hall of Fame, and a Gr ...

. '' Romanitas'' by

Sophia McDougall Sophia McDougall (born 1979) is a British novelist, playwright, and poet. Life and career McDougall is best known internationally as the author of alternate history novels published by Orion Publishing Group and based on the premise that the R ...

, and ''

Warlords of Utopia ''Warlords of Utopia'' is an original novel by Lance Parkin set in the Faction Paradox universe. Parkin developed the idea for a '' Doctor Who'' book that was not published. The published version is his second attempt to write it for Faction Par ...

'' by

Lance Parkin Lance Parkin is a British author. He is best known for writing fiction and reference books for television series, in particular '' Doctor Who'' (and spin-offs including the Virgin New Adventures and Faction Paradox) and as a storyliner on ''Emmerd ...

Similar concepts

Counter-Earth

The concept of counter-Earth might seem similar to a parallel universe but is actually a distinct idea. A counter-earth is a planet that shares Earth's orbit but is on the opposition side of the sun, therefore, cannot be seen from Earth. There would be no necessity that such a planet would be like

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

in any way, although typically in fiction it is practically identical to Earth. Since Counter-Earth is not only within our universe but within our own

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

, reaching it can be accomplished with ordinary space travel.

Convergent evolution and parallel evolution

Convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

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. Again, this is not a true parallel universe since such planets exist within the same universe as our own, but the stories are similar in some respects. '' Star Trek'' frequently explored such worlds, in episodes including "

Bread and Circuses "Bread and circuses" (or bread and games; from Latin: ''panem et circenses'') is a metonymic phrase referring to superficial appeasement. It is attributed to Juvenal, a Roman poet active in the late first and early second century CE, and is used ...

", "

The Omega Glory "The Omega Glory" is the twenty-third episode of the second season of the American science fiction television series '' Star Trek''. Written by Gene Roddenberry and directed by Vincent McEveety, it was first broadcast March 1, 1968. In the epis ...

", and "

Miri ) , subdivision_type = Country , subdivision_name = , subdivision_type1 = State , subdivision_name1 = , subdivision_type2 = Division , subdivision_name2 ...

". The 2017 episode of British

science fiction television Science fiction first appeared in television programming in the late 1930s, during what is called the Golden Age of Science Fiction. Special effects and other production techniques allow creators to present a living visual image of an imaginary ...

programme ''

'', "

The Doctor Falls "The Doctor Falls" is the twelfth and final episode of the tenth series of the British science fiction television series ''Doctor Who''. It was written by Steven Moffat, directed by Rachel Talalay, and was broadcast on 1 July 2017 on BBC One. I ...

", explains the different origins of the

Cybermen The Cybermen are a fictional race of cyborgs principally portrayed in the British science fiction television programme ''Doctor Who''. The Cybermen are a species of space-faring cyborgs who often forcefully and painfully convert human beings ( ...

parallel evolution Parallel evolution is the similar development of a trait in distinct species that are not closely related, but share a similar original trait in response to similar evolutionary pressure.Zhang, J. and Kumar, S. 1997Detection of convergent and paral ...

, due to the inevitability of humans and human-like species attempting to upgrade themselves through technology; this perspective resolves continuity differences in the Cybermen's history. Convergent evolution may also be due to contamination. In this case, a planet may start out differently from Earth, but due to the influence of Earth's culture, the planet comes to resemble Earth in some way. ''Star Trek'' also frequently used this theory as well, for example, in " Patterns of Force" and " A Piece of the Action".

Simulated reality

Simulated realities are digital constructs featured in science fiction such as ''

The Matrix ''The Matrix'' is a 1999 science fiction action film written and directed by the Wachowskis. It is the first installment in ''The Matrix'' film series, starring Keanu Reeves, Laurence Fishburne, Carrie-Anne Moss, Hugo Weaving, and Joe Pantolia ...

''.

Parallel Universe Theory

In 1954,

Princeton University Princeton University is a private university, private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial Colleges, fourth-oldest ins ...

doctoral applicant

Hugh Everett III Hugh Everett III (; November 11, 1930 – July 19, 1982) was an American physicist who first proposed the many-worlds interpretation (MWI) of quantum physics, which he termed his "relative state" formulation. In contrast to the then-dominant Cop ...

proposed that parallel universes co-exist with and diverge from our own universe. Everett's Many-Worlds Theory, as it came to be known, wanted to respond to some unanswered inquiries raised in the developing field of quantum material science. In 2012 two quantum physicists, Dr S.Haroche and Dr D. Worland, received a Nobel Prize for their experiments which showed that "a particle can be at two locations at the same time."

Fantasy

Transportation of modern characters to fantasy universe

It is common in fantasy for authors to find ways to bring a protagonist from "our" world to the fantasy world. Before the mid-20th century, this was most often done by hiding fantastic worlds within unknown, distant locations on Earth; peasants who seldom, if ever, traveled far from their villages could not conclusively say that it was impossible that an

ogre An ogre (feminine: ogress) is a legendary monster depicted as a large, hideous, man-like being that eats ordinary human beings, especially infants and children. Ogres frequently feature in mythology, folklore, and fiction throughout the world ...

or other fantastical beings could live an hour away. Characters in the author's world could board a ship and find themselves on a fantastic island, as

Jonathan Swift Jonathan Swift (30 November 1667 – 19 October 1745) was an Anglo-Irish satirist, author, essayist, political pamphleteer (first for the Whigs, then for the Tories), poet, and Anglican cleric who became Dean of St Patrick's Cathedral, Dubl ...

does in '' Gulliver's Travels'' or in the 1949 novel ''

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. In 1981, ''The Moon's Fire-Eating Daughter' ...

'' by

John Myers Myers John Myers Myers (January 11, 1906 – October 30, 1988) was an American writer. He is known best for the fantasy novel '' Silverlock'' (1949), in which a man with a Master of Business Administration travels through a fantasy land, meeting dozens ...

, or be sucked up into a

tornado A tornado is a violently 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. It is often referred to as a twister, whirlwind or cyclone, altho ...

and land in Oz. These "

lost world The lost world is a subgenre of the fantasy or science fiction genres that involves the discovery of an unknown Earth civilization. It began as a subgenre of the late- Victorian adventure romance and remains popular into the 21st century. The ...

" 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 Paul Holdstock (2 August 1948 – 29 November 2009) 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. Holds ...

's novel ''

Mythago Wood ''Mythago Wood'' is a fantasy novel by British writer Robert Holdstock, published in the United Kingdom in 1984. ''Mythago Wood'' is set in Herefordshire, England, in and around a stand of ancient woodland, known as Ryhope Wood. The story invo ...

''. However, increasing geographical knowledge meant that such locations had to be farther and farther off. Perhaps influenced by ideas from science fiction, many works chose a setting that takes place in another, separate reality. As it is now not possible to reach these worlds via conventional travel, a common

trope Trope or tropes may refer to: Arts, entertainment, and media * Trope (cinema), a cinematic convention for conveying a concept * Trope (literature), a figure of speech or common literary device * Trope (music), any of a variety of different things ...

is a portal or artifact that connects our world and the fantasy world together, examples being the wardrobe in

' '' The Lion, the Witch and the Wardrobe'' or the sigil in

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, Edmund Wilson, and Sinclair Lewis. His work ...

's ''

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 mai ...

''. 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 An altered state of consciousness (ASC), also called altered state of mind or mind alteration, is any condition which is significantly different from a normal waking state. By 1892, the expression was in use in relation to hypnosis, though there ...

. Examples include the ''

Dream Cycle The Dream Cycle is a series of short stories and novellas by author H. P. Lovecraft (1890–1937). Written between 1918 and 1932, they are about the "Dreamlands", a vast alternate dimension that can only be entered via dreams. Geography The D ...

'' stories by H. P. Lovecraft or the ''

Thomas Covenant ''The Chronicles of Thomas Covenant'' is a series of ten high fantasy novels written by American author Stephen R. Donaldson. The series began as a trilogy, entitled ''The Chronicles of Thomas Covenant, the Unbeliever''. This was followed by ano ...

'' stories of Stephen R. Donaldson. Often, stories of this type have as a major theme the nature of reality itself, questioning whether the dream-world is as real as the waking world. Science fiction often employs this theme in the ideas of cyberspace and

virtual reality Virtual reality (VR) is a simulated experience that employs pose tracking and 3D near-eye displays to give the user an immersive feel of a virtual world. Applications of virtual reality include entertainment (particularly video games), e ...

Between the worlds

In a few cases, the interaction between the worlds is an important element, so that the focus is not on simply the fantasy world, but on ours as well. Sometimes the intent is to let them mingle and see what would happen, such as introducing a computer programmer into a

high fantasy High fantasy, or epic fantasy, is a subgenre of fantasy defined by the epic nature of its setting or by the epic stature of its characters, themes, or plot.Brian Stableford, ''The A to Z of Fantasy Literature'', (p. 198), Scarecrow Press, ...

world as seen in Rick Cook's ''

Wizardry ''Wizardry'' is a series of role-playing video games, developed by Sir-Tech, that were highly influential in the evolution of modern role-playing video games. The original ''Wizardry'' was a significant influence on early console role-playing ...

'' series, while other times an attempt to keep them from mingling becomes a major plot point, such as in

Aaron Allston Aaron Dale Allston (December 8, 1960 – February 27, 2014) was an American game designer and author of many science fiction books, notably ''Star Wars'' novels. His works as a game designer include game supplements for role-playing games, severa ...

's '' Doc Sidhe.'' In that story, our "grim world" is paralleled by a "fair world" where the elves live and history echoes ours, where a major portion of the plot deals with preventing a change in interactions between the worlds.

Fantasy multiverses

The idea of a multiverse is as fertile a subject for fantasy as it is for science fiction, allowing for epic settings and godlike protagonists. One example of an epic and far-ranging fantasy "multiverse" is that of

Michael Moorcock Michael John Moorcock (born 18 December 1939) is an English writer, best-known for science fiction and fantasy, who has published a number of well-received literary novels as well as comic thrillers, graphic novels and non-fiction. He has work ...

, who actually named the concept in a 1963 science fiction novel ''The Sundered Worlds''. Like many authors after him, Moorcock was inspired by the many worlds interpretation of

quantum mechanics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, ...

, 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) ... rphysicist 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 The Eternal Champion is a fictional character created by British author Michael Moorcock and is a recurrent feature in many of his speculative fiction works. General overview Many of Moorcock's novels and short stories take place in a shared M ...

'' stories go far beyond alternative history to include mythic and sword and sorcery settings as well as worlds more similar to, or the same as, our own. The term 'polycosmos' was coined as an alternative to 'multiverse' by the author and editor

Paul le Page Barnett Paul le Page Barnett (22 November 1949 – 3 February 2020), known by the pen name of John Grant, was a Scottish writer and editor of science fiction, fantasy, and non-fiction. Biography Born Paul le Page Barnett in Aberdeen, Scotland, Grant ...

(also known by the pseudonym John Grant), and is built from

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

rather than

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

morpheme A morpheme is the smallest meaningful Constituent (linguistics), constituent of a linguistic expression. The field of linguistics, linguistic study dedicated to morphemes is called morphology (linguistics), morphology. In English, morphemes are ...

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."

Fictional universe as alternative universe

There are many examples of the

meta-fiction Metafiction is a form of fiction which emphasises its own narrative structure in a way that continually reminds the audience that they are reading or viewing a fictional work. Metafiction is self-conscious about language, literary form, and stor ...

al 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 H.G. Wells' '' Men Like Gods'', Myers' ''Silverlock'', and Heinlein's ''Number of the Beast''.

Fletcher Pratt Murray Fletcher Pratt (25 April 1897 – 10 June 1956) was an American writer of history, science fiction, and fantasy. He is best known for his works on naval history and the American Civil War and for fiction written with L. Sprague de Camp. ...

and

L. Sprague de Camp Lyon Sprague de Camp (; November 27, 1907 – November 6, 2000) was an American writer of science fiction, fantasy and non-fiction. In a career spanning 60 years, he wrote over 100 books, including novels and works of non-fiction, including biog ...

took the protagonist of the

Harold Shea The "Harold Shea" Stories is a name given to a series of five science fantasy stories by the collaborative team of L. Sprague de Camp and Fletcher Pratt and to its later continuation by de Camp alone, Christopher Stasheff, Holly Lisle, John Mad ...

series through the worlds of Norse myth, Edmund Spenser's ''

The Faerie Queene ''The Faerie Queene'' is an English epic poem by Edmund Spenser. Books IIII were first published in 1590, then republished in 1596 together with books IVVI. ''The Faerie Queene'' is notable for its form: at over 36,000 lines and over 4,000 sta ...

'', Ludovico Ariosto's '' Orlando Furioso'', and the ''

Kalevala The ''Kalevala'' ( fi, Kalevala, ) is a 19th-century work of epic poetry compiled by Elias Lönnrot from Karelian and Finnish oral folklore and mythology, telling an epic story about the Creation of the Earth, describing the controversies and ...

'' – without ever quite settling whether writers created these parallel worlds by writing these works, or received impressions from the worlds and wrote them down. In an interlude set in " Xanadu", a character claims that the universe is dangerous because the poem went unfinished, but whether this was his misapprehension or not is not established. Some fictional approaches definitively establish the independence of the parallel world, sometimes by having the world differ from the book's account; other approaches have works of fiction create and affect the parallel world:

's '' Solomon's Stone'', taking place on an astral plane, is populated by the daydreams of mundane people, and in Rebecca Lickiss's ''Eccentric Circles'', an elf is grateful to

Tolkien John Ronald Reuel Tolkien (, ; 3 January 1892 – 2 September 1973) was an English writer and philologist. He was the author of the high fantasy works '' The Hobbit'' and ''The Lord of the Rings''. From 1925 to 1945, Tolkien was the Rawl ...

for transforming elves from dainty little creatures. These stories often place the author, or authors in general, in the same position as Zelazny's characters in Amber. Questioning, in a literal fashion, if writing is an act of creating a new world, or an act of discovery of a pre-existing world. Occasionally, this approach becomes self-referential, treating the literary universe of the work itself as explicitly parallel to the universe where the work was created. Stephen King's seven-volume '' Dark Tower'' series hinges upon the existence of multiple parallel worlds, many of which are King's own literary creations. Ultimately the characters become aware that they are only "real" in King's literary universe (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 Francis Cooper Fox (May 20, 1911 – December 24, 1986) was an American writer known best for creating numerous comic book characters for DC Comics. He is estimated to have written more than 4,000 comics stories, including 1,500 for DC ...

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.

Robert Heinlein Robert Anson Heinlein (; July 7, 1907 – May 8, 1988) was an American science fiction author, aeronautical engineer, and naval officer. Sometimes called the "dean of science fiction writers", he was among the first to emphasize scientific accu ...

, in '' The Number of the Beast'', quantizes the many parallel fictional universes - in terms of ''fictions''. A number of fictional universes are accessible along one of the three axes of time which Dr. Jacob Burroughs' "time twister" can access. Each quantum level change - a ''fiction'' - along this time axis corresponds to a different universe from one of several bodies of fiction known to all four travelers in the inter-universal, time traveling vehicle ''Gay Deceiver''. Heinlein also "

breaks the fourth wall The fourth wall is a performance convention in which an invisible, imaginary wall separates actors from the audience. While the audience can see through this ''wall'', the convention assumes the actors act as if they cannot. From the 16th cen ...

" by having "both Heinleins" (Robert and his wife

Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...

) visit an inter-universal science-fiction and fantasy convention in the book's last chapter. The convention was convened on Heinlein character

Lazarus Long Lazarus Long is a fictional character featured in a number of science fiction novels by Robert A. Heinlein. Born in 1912 in the third generation of a selective breeding experiment run by the Ira Howard Foundation, Lazarus (birth name Woodrow Wi ...

's estate on the planet "Tertius" to attract the evil "Black Hats" who pursued the main characters of ''The Number of the Beast'' through space and time in order to destroy Dr. Burroughs and his invention. Heinlein continues this literary conceit in ''

The Cat Who Walks Through Walls ''The Cat Who Walks Through Walls'' is a science fiction novel by American writer Robert A. Heinlein, published in 1985. Like many of his later novels, it features Lazarus Long and Jubal Harshaw as supporting characters. Plot summary A writer s ...

'' and ''

To Sail Beyond the Sunset ''To Sail Beyond the Sunset'' is a science fiction novel by American writer Robert A. Heinlein, published in 1987. It was the last novel published before his death in 1988. The title is taken from the poem " Ulysses", by Alfred Tennyson. The stan ...

'', using characters from throughout his science-fictional career, hauled forth from their own "fictions" to unite in the war against the "Black Hats". Heinlein also wrote a stand-alone novel, '' Job: A Comedy of Justice'', whose two protagonists fall from alternative universe into alternative universe (often naked), and after a number of such adventures die and enter a stereotypically

Fundamentalist Christian Christian fundamentalism, also known as fundamental Christianity or fundamentalist Christianity, is a religious movement emphasizing biblical literalism. In its modern form, it began in the late 19th and early 20th centuries among British and ...

Heaven (with many of its internal contradictions explored in the novel). Their harrowing adventures through the universes are then revealed to have been "destruction testing" of their souls by Loki, sanctioned by the Creator person of the Christian God (

Yahweh Yahweh *''Yahwe'', was the national god of ancient Israel and Judah. The origins of his worship reach at least to the early Iron Age, and likely to the Late Bronze Age if not somewhat earlier, and in the oldest biblical literature he posse ...

). The Devil appears as the most sympathetic of the gods in the story, who expresses contempt for the other gods' cavalier treatment of the story's main characters. Thus, '' Job: A Comedy of Justice'' rings in the theological dimension (if only for the purpose of satirizing evangelical Christianity) of parallel universes, that their existence can be used by God (or a number of gods, Loki seems to have made himself available to do Yahweh's dirty work in this novel). It manages also to have a fictional multiverse angle in that references are made to Heinlein's early SF/fantasy short story "

They In Modern English, ''they'' is a third-person pronoun relating to a grammatical subject. Morphology In Standard Modern English, ''they'' has five distinct word forms: * ''they'': the nominative (subjective) form * ''them'': the accusat ...

", a solipsistic tale in which reality is constantly being transmogrified behind the scenes to throw the central character off his guard and keep him from seeing reality as it is, which was set in the same Heinlein fictional universe as ''

The Moon is a Harsh Mistress ''The Moon Is a Harsh Mistress'' is a 1966 science fiction novel by American writer Robert A. Heinlein about a lunar colony's revolt against absentee rule from Earth. The novel illustrates and discusses libertarian ideals. It is respected for i ...

''.

Elfland

Elfland, or Faerie, the otherworldly home not only of

elves An elf () is a type of humanoid supernatural being in Germanic mythology and folklore. Elves appear especially in North Germanic mythology. They are subsequently mentioned in Snorri Sturluson's Icelandic Prose Edda. He distinguishes " ...

and fairies but

goblin A goblin is a small, grotesque, monstrous creature that appears in the folklore of multiple European cultures. First attested in stories from the Middle Ages, they are ascribed conflicting abilities, temperaments, and appearances depending on ...

troll A troll is a being in Nordic folklore, including Norse mythology. In Old Norse sources, beings described as trolls dwell in isolated areas of rocks, mountains, or caves, live together in small family units, and are rarely helpful to human be ...

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 Sir Thomas de Ercildoun, better remembered as Thomas the Rhymer (fl. c. 1220 – 1298), also known as Thomas Learmont or True Thomas, was a Scottish laird and reputed prophet from Earlston (then called "Erceldoune") in the Borders. Thomas ...

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, Nordic, or Scandinavian mythology is the body of myths belonging to the North Germanic peoples, stemming from Old Norse religion and continuing after the Christianization of Scandinavia, and into the Nordic folklore of the modern period ...

, Elfland ( Alfheim) was also the name of what today is the Swedish province of Bohuslän. In the sagas, it said that the people of this petty kingdom were more beautiful than other people, as they were related to the

, 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 (or Tamas) Lin (also called Tamlane, Tamlin, Tambling, Tomlin, Tam Lien, Tam-a-Line, Tam Lyn, or Tam Lane) is a character in a legendary ballad originating from the Scottish Borders. It is also associated with a reel of the same name, also ...

" 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 ( ), Osian, Ossian ( ), or anglicized as Osheen ( ) was regarded in legend as the greatest poet of Ireland, a warrior of the Fianna in the Ossianic or Fenian Cycle of Irish mythology. He is the demigod son of Fionn mac Cumhaill and of ...

, 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 (December 12, 1946 – August 23, 2012) was an American author, folklorist, and anthologist. In 1990 she won the Compton Crook Award for the novel ''The Shining Falcon''. Works Series Buffyverse *''Visitors'' (1999) (with ...

's Prince of the Sidhe series or

Esther Friesner Esther Mona Friesner-Stutzman, née Friesner (born July 16, 1951) is an American science fiction and fantasy author. She is also a poet and playwright. She is best known for her humorous style of writing, both in the titles and the works themsel ...

's ''

Elf Defense An elf () is a type of humanoid supernatural being in Germanic mythology and folklore. Elves appear especially in Norse mythology, North Germanic mythology. They are subsequently mentioned in Snorri Sturluson's Icelandic Prose Edda. He dis ...

'' – and others have depicted it as the next land over, possibly difficult to reach for magical reasons –

Hope Mirrlees (Helen) Hope Mirrlees (8 April 1887 – 1 August 1978) was a British poet, novelist, and translator. She is best known for the 1926 ''Lud-in-the-Mist'', a fantasy novel and influential classic,David Langford and Mike Ashley, "Mirrlees, Hope", i ...

's ''

Lud-in-the-Mist ''Lud-in-the-Mist'' (1926) is the third and final novel by British writer Hope Mirrlees. 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 Lo ...

'', or Lord Dunsany's ''

The King of Elfland's Daughter ''The King of Elfland's Daughter'' is a 1924 fantasy novel by Anglo-Irish writer Lord Dunsany. It is widely recognized as one of the most influential and acclaimed works in all of fantasy literature.; pp 1124 Although the novel faded into rela ...

''. 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.

's ''

'' 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). In the young teenage book '' Mist'' by Kathryn James, the Elven world lies through a patch of mist in the woods. It was constructed when the Elven were thrown out of our world. Travel to and fro is possible by those in the know, but can have lethal consequences.

Isekai

Isekai is a Japanese genre of speculative fiction—both portal fantasy and science fiction are included. It includes novels, light novels, films, manga, anime and video games that revolve around a person or people who are transported to and have to ...

, is a subgenre of Japanese fantasy light novels, manga, anime, and video games revolving around a normal person being transported to or trapped in a parallel universe. Often, this universe already exists in the protagonist's world as a fictional universe, but it may also be unbeknownst to them.

Films

The most famous treatment of the alternative universe concept in film could be considered '' The Wizard of Oz'', which portrays a parallel world, famously separating the magical realm of the

Land of Oz The Land of Oz is a fantasy world, magical country introduced in the 1900 children's novel ''The Wonderful Wizard of Oz'' written by L. Frank Baum and illustrated by William Wallace Denslow, W. W. Denslow. Oz consists of four vast quadrants, th ...

from the mundane world by filming it in

Technicolor Technicolor is a series of Color motion picture film, color motion picture processes, the first version dating back to 1916, and followed by improved versions over several decades. Definitive Technicolor movies using three black and white films ...

while filming the scenes set in

Kansas Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the ...

sepia Sepia may refer to: Biology * ''Sepia'' (genus), a genus of cuttlefish Color * Sepia (color), a reddish-brown color * Sepia tone, a photography technique Music * ''Sepia'', a 2001 album by Coco Mbassi * ''Sepia'' (album) by Yu Takahashi * " ...

. At times, alternative universes have been featured in small scale independent productions such as Kevin Brownlow and Andrew Mollo's ''

It Happened Here ''It Happened Here'' (also known as ''It Happened Here: The Story of Hitler's England'') is a 1964 British black-and-white film written, produced and directed by Kevin Brownlow and Andrew Mollo, who began work on the film as teenagers. The film ...

'' (1964), featuring an alternative United Kingdom which had undergone

Operation Sea Lion Operation Sea Lion, also written as Operation Sealion (german: Unternehmen Seelöwe), was Nazi Germany's code name for the plan for an invasion of the United Kingdom during the Battle of Britain in the Second World War. Following the Battle o ...

in 1940 and had been defeated and occupied by

Nazi Germany Nazi Germany (lit. "National Socialist State"), ' (lit. "Nazi State") for short; also ' (lit. "National Socialist Germany") (officially known as the German Reich from 1933 until 1943, and the Greater German Reich from 1943 to 1945) was ...

. It focused on moral questions related to the professional ethics of Pauline, a nurse forced into Nazi collaboration. Another common use of the theme is as a prison for

villain A villain (also known as a " black hat" or "bad guy"; the feminine form is villainess) is a stock character, whether based on a historical narrative or one of literary fiction. ''Random House Unabridged Dictionary'' defines such a character ...

s or demons. The idea is used in the first two ''

Superman Superman is a superhero who appears in American comic books published by DC Comics. The character was created by writer Jerry Siegel and artist Joe Shuster, and debuted in the comic book ''Action Comics'' #1 (cover-dated June 1938 and publi ...

'' movies starring

Christopher Reeve Christopher D'Olier Reeve (September 25, 1952 – October 10, 2004) was an American actor, best known for playing the title character in the film '' Superman'' (1978) and three sequels. Born in New York City and raised in Princeton, New Jersey ...

where Krypton (comics), Kryptonian villains were sentenced to the Phantom Zone from where they eventually escaped. An almost exactly parallel use of the idea is presented in the film ''The Adventures of Buckaroo Banzai Across the 8th Dimension'', 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 (film), From Beyond'' (based on the H. P. Lovecraft From Beyond (short story), story of the same name) where a scientific experiment induces the experimenters to perceive extraterrestrial life in popular culture, aliens from a parallel universe, with bad results. The 1987 John Carpenter film ''Prince of Darkness (film), Prince of Darkness'' is based on the premise that the essence of a being described as Satan, trapped in a glass canister and found in an abandoned church in Los Angeles, 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 mirror. 1997 film Event Horizon (film) directed by Paul W. S. Anderson tells about a crew of eponymous space ship who are accidentally travelled to another dimension (implied to be hell), turning them insane and ended up killing each other. 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's ''Rashomon''. Conversely, often in film noir and crime film, crime dramas, the alternative narrative is a fiction created by a central character, intentionally – as in ''The Usual Suspects'' – or unintentionally – as in ''Angel Heart''. Less often, the alternative narratives are given equal weight in the story, making them truly alternative universes, such as in the Germany, German film ''Run Lola Run'', the short-lived British West End theatre, West End musical ''Our House (musical), Our House'' and the Great Britain, British film ''Sliding Doors''. More recent films that have explicitly explored parallel universes are: the 2000 film ''The Family Man'', the 2001 cult film ''Donnie Darko'', which deals with what it terms a "tangent universe" that erupts from our own universe; ''Super Mario Bros. (film), Super Mario Bros.'' (1993) has the eponymous heroes cross over into a parallel universe ruled by humanoids who evolved from dinosaurs; ''The One (2001 film), The One'' (2001) starring Jet Li, 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'' (2004), the main character runs away from a totalitarian nightmare, and he enters into a cyber-afterlife alternative reality. The current '' Star Trek'' films are set in an alternative universe created by the first film's villain traveling back in time, thus allowing the franchise to be reboot (fiction), rebooted without affecting the continuity of any other ''Star Trek'' film or show. The 2011 science-fiction thriller ''Source Code'' employs the concepts of quantum reality and parallel universes. The characters in ''The Cloverfield Paradox'', the third installment of the Cloverfield (franchise), franchise, accidentally create a ripple in the time-space continuum and travel into an alternative universe, where the Clover (creature), monster and the events in the Cloverfield (film), first film transpired. This concept has been also been passively depicted in the view of a romantic couple in the Indian Tamil Film Irandam Ulagam. In the 2000 film ''The Beach (film), The Beach,'' Leonardo DiCaprio's character Richard, while sitting on the beach with love interest Françoís (Virginie Ledoyen). describes the utopia they have found in Thailand as their own parallel universe. The Marvel Cinematic Universe heavily features the Multiverse (Marvel Cinematic Universe), multiverse. ''Doctor Strange (2016 film), Doctor Strange'' features the Dark Dimension and the Masters of the Mystic Arts, who draw upon mystical energies from other realities. In '' Avengers: Endgame'', the 2023 Avengers (Marvel Cinematic Universe), Avengers create alternate timelines during the Time Heist. The ramifications of these actions are explored in the television series ''Loki (TV series), Loki'', which focuses on the 2012 variant of Loki (Marvel Cinematic Universe), Loki and the Time Variance Authority. A female variant of Loki, Sylvie (Marvel Cinematic Universe), Sylvie, kills the mastermind behind the TVA who kept the Sacred Timeline in order, which leads to the rebirth of the Multiverse. The animated series ''What If...? (TV series), What If...?'' follows multiple variants of MCU characters and timelines guided by Uatu, The Watcher. ''Shang-Chi and the Legend of the Ten Rings'' features Ta-Lo, Ta Lo, a mythical village also set in an alternate universe that houses many Chinese mythological creatures and where the climax of the film takes place. ''Spider-Man: No Way Home'' has Peter Parker (Marvel Cinematic Universe), Spider-Man encounter villains from the ''Spider-Man (2002 film series), Spider-Man trilogy'' and ''The Amazing Spider-Man (film series), The Amazing Spider-Man series'' and prevents their original deaths with help of other variants of himself. ''Doctor Strange in the Multiverse of Madness'' features Doctor Strange travelling throughout the multiverse trying to protect America Chavez (Marvel Cinematic Universe), America Chavez from the Wanda Maximoff (Marvel Cinematic Universe), Scarlet Witch, who seeks her power. Along the way, they encounter other variants of Strange, Christine Palmer, and the Illuminati (comics), Illuminati. The DC Extended Universe will also bring in the multiverse with its upcoming film The Flash (film), ''The Flash'' (2023), when the title character, played by Ezra Miller, goes back in time to prevent his mother's murder, thus opening the multiverse. The film will feature both Michael Keaton and Ben Affleck both reprising their versions of Batman, with the film also introducing the DCEU version of Supergirl, portrayed by Sasha Calle, and Miller portraying an alternate version of the character from the Keaton Batman universe.

Television

The idea of parallel universes has received treatment in a number of television series, usually as a single story or episode in a more general

or fantasy storyline. * The 1990s TV series ''Sliders (TV series), Sliders'' depicts a group of adventurers visiting assorted parallel universes, as they attempt to find their "home" universe. Included in the 1st season is a universe where the world is stuck in the ice age, with no life anywhere. Another episode includes 'Honest Abe' never to be president, in which the United States loses World War I and World War II, and they are controlled by a senator, and technology is at an all-time low. * One of the earliest television plots to feature parallel time (outside of the Twilight Zone) was a 1970 storyline on the soap opera ''Dark Shadows''. Vampire Barnabas Collins found a room in Collinwood which served as a portal to parallel time, and he entered the room in an attempt 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'' episode entitled "Mirror, Mirror (Star Trek: The Original Series), Mirror, Mirror". The episode introduced an Mirror Universe, alternative version of the ''Star Trek'' universe where the main characters were barbaric and cruel to the point of being evil. When the parallel universe concept is parody, parodied, 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-comprised continuum. His counterpart, in a state of paranoia, claims the double threatens his and the very cosmos' existence. With help from Captain James T. Kirk, Kirk, A traps B along with him in a "anti"-universe, for eternity, thus bringing balance to both matter-oriented realms. A similar plot was used in the ''Codename: Kids Next Door'' episode Operation: P.O.O.L.. * The mirror universe of ''Star Trek'' was further developed by later series in the franchise. In several episodes of ''Star Trek: Deep Space Nine'', the later evolution of the mirror universe is explored. A two-part episode of ''Star Trek: Enterprise'', entitled "In a Mirror, Darkly", serves as a prequel, introducing the early developments of the Mirror Universe. * In the 1970s young adult British SF series The Tomorrow People, its second-season episode, ''A Rift in Time'' (March–April 1974) pitted the three telepath core characters and allies against time travelling interlopers from an alternative history where the Roman Empire developed the steam engine in the first century CE, had a technological head start, did not fragment during the fifth century and underwent accelerated technological development. The Roman eagle standard was planted on the Moon in the fifth century and by its alternative twentieth century, it had mastered interstellar travel, had a galactic empire and time travel. Consequently, the Tomorrow People had to rectify this aberrant timeline by dismantling and disabling the anomalous steam engine. * Multiple episodes of ''Red Dwarf'' 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 alternative is a dog. "Dimension Jump" introduces a heroic alternative Ace Rimmer, 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 alternative Kochanski then joins the crew for the remaining episodes. * ''Buffy the Vampire Slayer (TV series), 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. In The Wish (Buffy the Vampire Slayer), Cordelia Chase inadvertently created a dystopian alternative reality in which Buffy had never moved from LA to Sunnydale. Her core-universe allies Xander Harris and Willow Rosenberg had become vampires in that timeline. * The plot of the Charmed (season 4), season four episode of ''Charmed'', entitled "Brain Drain", features The Source (Charmed), The Source of All Evil kidnapping Piper Halliwell and forcing her into a deep coma, where she experiences an alternative reality in which the Halliwell manor is actually a mental institution. She and her sisters serve as patients in this universe, their powers only a manifestation of their minds, a ruse put up to trick Piper into willingly relinquishing the sisters' magic. * The Stargate, ''Stargate'' franchise includes many stories in which alternate timelines, alternate dimensions and alternate realities are explored. These include the ''Stargate SG-1'' episodes "There But For the Grace of God", "Point of View", "Crystal Skull", "2010", "Moebius (Stargate SG-1), Moebius" parts 1 and 2, "Babylon", "Ripple Effect", "Arthur's Mantle", "The Road Not Taken", "Unending" and the direct-to-DVD movie ''Stargate: Continuum'', the ''Stargate Atlantis'' episodes "Before I Sleep", "McKay and Mrs. Miller", "The Last Man", "The Daedalus Variations", "Vegas" and "Enemy at the Gate (Stargate Atlantis), Enemy at the Gate", and the ''Stargate Universe'' episodes "Time", "Twin Destinies", "Common Descent" and "Epilogue". * The animated series, ''Futurama'', had The Farnsworth Parabox, an episode where the characters travel between "Universe 1" and "Universe A (also known as universe Γ)" 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. They also had another episode where they travel to the edge of the universe and in the distance was the cowboy universe where everyone was dressed as cowboys. It was accidentally invented by Professor Farnsworth. * The idea of a parallel universe and the concept of déjà vu was a major plot line of the first-season finale of ''Fringe (TV series), Fringe'', guest-starring Leonard Nimoy of '' Star Trek''. The show has gone on to feature the parallel universe prominently. * In the 2010 season of ''Lost (TV series), Lost'', 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. * In the anime and manga series of ''Dragon Ball Z'', in the Androids Saga, Future Trunks returns to the past to give Goku medicine to prevent him from dying of a heart disease and warns him of the Androids, in the process creating a timeline split of parallel realities. This event leads to the appearance of Cell, who kills the same Future Trunks after he originally returns from the past of and kills the Androids via a remote control in his own timeline. Cell does this in order to go to the main timeline of the series when the Androids are still alive for him to absorb. Back in the same past the series follows, Future Trunks discovers the existence of the time machine Cell stole in the original future reality, leading him to make the decision to stay in past instead. This creates a parallel reality for his own future timeline where he is physically capable of killing both the Androids and Cell once he returns after the events of the Cell Saga. ** Its sequel, ''Dragon Ball Super'', later features separate universes that are in pairs whose numbers add up to the total number of the universe: 12 in this case. Previously there were 18 universes, but Zeno (the supreme ruler of the Dragon Ball Multiverse) destroyed 6 of them in a fit of rage. Previously, Daizenshuu 7 stated that the typical Dragon Ball Universe had only 4 galaxies, but ''Dragon Ball Super'' effectively retcons this, where Whis says that the universe contains endless galaxies. **The spin-off series ''Super Dragon Ball Heroes'' features alternate versions of the main characters who protect the flow of time as part of the "Time Patrol". They usually have the "Xeno" moniker in addition to their names (e.g. Goku Xeno, Vegeta Xeno, Trunks Xeno, etc.). * The anime ''Turn A Gundam'' attempted to combine all the parallel 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 into one single reality. * The anime and manga series ''Eureka Seven: AO'' takes place in a parallel universe that is different from the one in the series' predecessor ''Eureka Seven''. The ''E7'' series started off in the year 12005, and the ''AO'' world, which takes place in the year 2025, would be the home of the two main characters' son. * The anime and manga series ''Katekyo Hitman Reborn!'' by Akira Amano features this idea in its third main arc, known as Future arc. * The anime ''Neon Genesis Evangelion'' 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 ''Neon Genesis Evangelion: Angelic Days, Angelic Days''. * The anime series ''Bakugan'' features a parallel universe called Vestroia and is the homeworld of fantastic creatures called Bakugan. The series' hero Dan Kuso alongside his friends and teammates must save Earth and Vestroia from total destruction. Season 2 & 3 feature another universe where Dan and his team save the day. They go to another dimension or universe through a pathway. The other universe has also other life forms and other types of technology. * In another anime series, ''Digimon'', there is a parallel universe called "digital world". The show's child protagonists meet digital monsters, or digimon, from this world and become partners and friends. In the third story arc of ''Digimon Fusion'', the Clockmaker (who is later revealed to be Bagramon) and his partner Clockmon travel through space-time to recruit heroes from previous series so they can help the Fusion Fighters to defeat Quartzmon before DigiQuartz can absorb each human and digital world in the multiverse. * In the anime series ''Umineko no Naku Koro ni'' the rounds of the battle between Battler and Beatrice take place in different dimensions, in order to show all kinds of possibilities (much to Battler's dismay) also the character Bernkastel is known for her ability to travel into different worlds by the usage of "fragments". * In the ''Star Trek: The Next Generation'' episode "Parallels (Star Trek: The Next Generation), Parallels", Lt. Worf traveled to several parallel universes when his shuttlecraft went through a time space fissure. * The ''Community (TV series), Community'' episode Remedial Chaos Theory, six different timelines and one "prime" timeline are explored, each having a different outcome based on which member of the study group goes to get the pizza. One timeline, dubbed the "Darkest Timeline", results in the greatest amount of terrible incidents and ends with Abed donning a felt goatee bearing resemblance to Spock's in "Mirror, Mirror". * In the 2003 anime series of ''Fullmetal Alchemist (TV series), Fullmetal Alchemist'', there exists a gateway that can be conjured by alchemists that acts as a source of all knowledge and energy; towards the end of the series, it is revealed that this gateway connects the world of the anime with the real world, set during the first decades of the 20th century. It is revealed that the two worlds shared a common history until their histories Point of divergence, diverged, apparently due to the success of alchemy in one world and that of modern physics in the other.

As an ongoing subplot

Sometimes a television series will use parallel universes as an ongoing subplot. ''Star Trek: Deep Space Nine'', ''Star Trek: Enterprise'' and ''Star Trek: Discovery'' 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'', the fantasy/horror series ''Buffy the Vampire Slayer (TV series), Buffy the Vampire Slayer'', ''Supernatural (U.S. TV series), Supernatural'' and the romance/fantasy ''Lois & Clark: The New Adventures of Superman''. 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 onslaught; in ''Buffy'', two episodes concern a timeline in which Buffy came to Sunnydale too late to stop the vampires from taking control; ''Lois & Clark'' repeatedly visits an alternative universe where Clark Kent's adoptive parents, Jonathan and Martha Kent, died when he was ten years of age, and Lois Lane 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. ''Once Upon a Time (TV series), Once Upon a Time'' often talks about alternative realms or universes in which all different forms of magic, and non-magic may occur, depending on the realm. According to the Mad Hatter (Sebastian Stan), they "touch each other in a long line of lands, each just as real as the last". He referred to our world's tendency to deny such things as arrogant. In the season 1 finale of ''The Flash (2014 TV series), The Flash'', the Eobard Thawne, Reverse-Flash opens a singularity that connects his world to a parallel universe called Earth-2. In the second season, Barry Allen (Arrowverse), The Flash starts facing villains from that earth who also have doppelgangers on Earth-1 sent by Zoom (comics), Zoom. The array of Earth-2 villains consists of Albert Rothstein, Atom Smasher, Sand Demon, King Shark, and Doctor Light (Kimiyo Hoshi), Dr. Light; all are sent by Zoom to kill The Flash with the assurance of being taken back home. However, they are not the only ones who arrive from the singularity; this also includes the Flash (Jay Garrick), Earth-2 Flash after a close death and loss of speed from a confrontation with Zoom. When the Earth-2 Flash (called Jay Garrick) introduces himself to Team Flash, Barry (The Flash) distrusts him at first and places him in the metahuman pipeline at S.T.A.R. Labs. When The Flash starts having a hard time facing off against Sand Demon, he frees Jay so that he could help him as well as train him in his speed. With a new trick taught by Jay, Barry defeats Sand Demon. Later on, the Earth-2 counterpart of Harrison Wells, arrives on Earth-1 as well. He steals a weapon from Mercury Labs and saves Barry from the Earth-2 King Shark. When Jay confronts and sees Wells again, the argument gets heated between them before Barry intercedes. Up until season 7, a new version of Wells was featured every season. The "Alf Stewart Rape Dungeon" series, created by artist Mr Doodleburger, uses footage from the Australian TV drama show Home and Away, but through the use of clever overlaid audio tracks, casts one of the main characters of the show, long running character Alf Stewart as a vicious violent character in a parallel version of Home and Away. ''see main article'' Alf Stewart#In popular culture, Alf Stewart Rape Dungeon Series

Television series involving parallel universes

There have been a few series where parallel universes were central to the series itself. * ''The Fantastic Journey'', in which several travellers lost in the Bermuda Triangle find themselves in another world * ''Otherworld (TV series), Otherworld'', in which a family gets trapped in an alternative world * ''Sliders (TV series), Sliders'', 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 * ''Parallax (TV series), Parallax'', in which a boy discovers portals to multiple parallel universes in his home town * ''The Midnight Gospel'', in which Clancy Gilroy, a spacecaster travelling through planets to interview guests for his spacecast within his simulator. * ''Charlie Jade'', 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 * ''Awake (TV series), Awake'', where a man switches between realities whenever he goes to sleep: one in which his wife survived a car accident that killed their son, and one in which his son survived but his wife died * In the TV series ''Fringe (TV series), Fringe'', a main element of the series is the loss of balance and the eventual collision of two universes and the moral ramifications of it. Most main characters have a doppelganger who is usually slightly different from their prime selves. * In the South Korean Drama ''Dr. Jin'' (2012), the concept of parallel universes was used. A doctor travels into the past, specifically, the Joseon era, and this results in major changes in history. * ''Rick and Morty'', in which there is an infinite number of realities and universes. * ''Stranger Things'', in which a small town becomes home to a gateway between dimensions. * ''The Flash (2014 TV series), The Flash'', in which Barry Allen travels to multiple parallel universes in the multiverse with the help of his super speed. * ''Supernatural (U.S. TV series), Supernatural'', in which several episodes deal with parallel universes, particularly Supernatural (season 13), the thirteenth season which features storylines centering around parallel universes known as Apocalypse World and The Bad Place which appears in the backdoor pilot to the proposed spinoff ''Supernatural: Wayward Sisters''. Apocalypse World is depicted as a dark post-apocalyptic universe where ''Supernatural's'' main protagonists Sam Winchester, Sam and Dean Winchester were never born and thus could not stop the end of the world. * ''

'', in which a crack between two parallel universes opens up during the Rose Tyler plot. In which her Father still lives, however, the Cybermen control the parallel earth and pass through to ours. * ''The Man in the High Castle (TV series), The Man in the High Castle'', where in a parallel universe Nazism, Nazis have won World War II, based on the novel by Philip K. Dick. * ''The King: Eternal Monarch'', in which the country of Korea is unified as a single kingdom in a parallel reality to the Koreas being separated. The two lead characters travel between their respective realities, one from the Republic of South Korea, the other being the aforementioned king. * ''Dark (TV series), Dark'', where (previous) existence of an original world was revealed only in the last (third) season. Original world there was destroyed/split into two parallel ones by a genius scientist in pain, because his son's family was lost in an accident and he desperately wanted them back alive. Each of two worlds has their own protagonists group (Sic Mundus Creatus Est vs Erit Lux) fighting for a supremacy of time travel, available in three flavours: via a local cave, swirling blob of God Particle, God particles and portable drones. * ''The OA'', in which characters discover parallel universes and attempt to travel to them. * ''Amphibia (TV series), Amphibia'', the main character Anne Boonchuy along with her friends Sasha Waybright and Marcy Wu are transported to the kingdom of Amphibia. ''The Owl House'', where the main character Luz Noceda follows a magic door to the Boiling Isles, is confirmed to share the same universe and multiverse as ''Amphibia'' in the Season 2 finale, "King's Tide". * ''What If...? (TV series), What If...?'', based on the Marvel Comics What If (comics), series of the same name, which explores how the Marvel Cinematic Universe might have unfolded if key moments in its history had occurred differently.

Books

''Time Echoes Trilogy'' by Bryan Davis addresses the idea of parallel worlds as it delves into a plot in which the main character travels between three different "earths" each moving at a different speed of time so one earth is 20 years in the past while another one is 10 minutes into the future when compared to the earth from which the character exists. ''Overstrike'' by C. M. Angus features high-functioning schizophrenics with the ability to simultaneously perceive multiple realities.

Comic books

Parallel universes in modern comics have become particularly rich and complex, in large part due to the continual problem of continuity (fiction), continuity faced by the major two publishers, Marvel Comics and DC Comics. The two publishers have used the multiverse concept to fix problems arising from integrating characters from other publishers into their own canon, and from having major Serial (literature), serial protagonists with continuous histories lasting, as in the case of Superman, over 70 years. Additionally, both publishers have used new alternative universes to re-imagine their own characters. (See ''Multiverse (DC Comics)'' and ''Multiverse (Marvel Comics)'') DC's ''Michael Moorcock's Multiverse'' collected 12 issues in 1999 with an introduction by Moorcock which offered a sophisticated description of his rationale. DC Comics inaugurated its multiverse in the early 1960s, with the reintroduction of Golden Age superheroes the Justice Society of America now located on Earth-Two, and devised a "mirror universe" scenario of inverted morality and supervillain domination of Earth-Three shortly afterwards, several years before '' Star Trek'' devised its own darker alternative universe. There was a lull before DC inaugurated additional alternative universes in the seventies, such as Earth-X, where there was an Axis victory in World War II, Earth-S, home to the Fawcett Comics superheroes of the forties and fifties, such as Captain Marvel (DC Comics), Captain Marvel, and Earth-Prime, where superheroes only existed in fictional forms. Therefore, 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 Fictional crossover, crossover storylines, such as ''Crisis on Infinite Earths'' and ''Infinite Crisis'', where Marvel has a series called ''What If (comics), What If...'' 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. DC Comics series ''52 (comics), 52'' 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 (comic book), Kingdom Come'', DC's imprint (trade name), imprint WildStorm and an Earth devoted to the Charlton Comics heroes of DC. ''Countdown (DC Comics), Countdown'' and ''Countdown Presents: The Search for Atom (Ray Palmer), Ray Palmer'' and the ''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 books, such as 1981's ''Days of Future Past'', 1995's ''Age of Apocalypse'', and 2006's ''House of M'' and 2014's ''Spider-Verse'' storyline involving Alternative versions of Spider-Man, alternate versions of Spider-Man. In addition, the Squadron Supreme is a DC inspired Marvel Universe that has been used several times, often crossing over into the mainstream Universe in the Avengers (comics), Avengers comic. Exiles (Marvel Comics), Exiles is an offshoot of the ''X-Men'' franchise that allows characters to hop from one alternative reality to another, leaving the original, main Marvel Universe intact. The Marvel UK line has long had multiverse stories including the Jaspers' Warp storyline of Captain Britain's first series (it was here that the designation Earth-616 was first applied to the mainstream Marvel Universe). Marvel Comics, as of 2000, launched their most popular parallel universe, the Ultimate Marvel, Ultimate Universe. It is a smaller subline to the mainstream titles and features Ultimate Spider-Man, Ultimate X-Men, Ultimate Fantastic Four and the Ultimates (their "Avengers"). The graphic novel Watchmen is set in an alternative history, in 1985 where superheroes exist, the Vietnam War was won by the United States, and Richard Nixon is in his fifth term as President of the United States. The Soviet Union and the United States are still locked in an escalating "Cold War" as in our own world, but as the Soviet Union invades Afghanistan in this world and threatens Pakistan, nuclear war may be imminent. In 1973, Tammy (comics), Tammy published ''The Clock and Cluny Jones'', where a mysterious grandfather clock hurls bully Cluny Jones into a harsh alternative reality where she becomes the bullied. This story was reprinted in Misty (comics), Misty annual 1985 as ''Grandfather's Clock.'' In 1978, Misty (comics), Misty published ''The Sentinels''. The Sentinels were two crumbling apartment blocks that connected the mainstream world with an alternative reality where Adolf Hitler, Hitler conquered Britain in 1940. In 1981, Jinty (comics), Jinty published ''Worlds Apart.'' Six girls experience alternative 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. The parallel universe concept has also appeared prominently in the ''Sonic the Hedgehog (series), Sonic the Hedgehog'' Sonic the Hedgehog (Archie Comics), comic series from Archie Comics. The first and most oft-recurring case of this is another "mirror universe" where Sonic and his various allies are evil or anti-heroic while the counterpart of the evil Dr. Robotnik is good. Another recurring universe featured in the series is a perpendicular dimension that runs through all others, known as the No Zone. The inhabitants of this universe monitor travel between the others, often stepping in with their Zone Cop police force to punish those who travel without authorization between worlds. In more recent years, the comic has adapted the alternative dimension from the video games Sonic Rush and Sonic Rush Adventure, home to Sonic's ally Blaze the Cat. The continuities seen in various other Sonic franchises also exist in the comic, most notably those based on the cartoon series Sonic Underground and Sonic X. For some years, a number of other universes were also featured that parodied various popular franchises, such as Sailor Moon, Godzilla, and various titles from Marvel Comics. Archie has also used this concept as the basis for crossovers between Sonic and other titles that they publish, including Sabrina the Teenage Witch and Mega Man. The various Transformers comics also feature the parallel universe concept, and feature the various continuities from different branches of the franchise as parallel worlds that occasionally make contact with each other. Quite notably, the annual Botcon fan convention introduced a comic storyline that featured Cliffjumper, an Autobot from the original Transformers series, entering an alternative universe where his fellow Autobots are evil and the Decepticons are good. This universe is known as the "Shattered Glass" universe, and continued on in comics and text based stories after its initial release.

Audio drama

Within the Wires takes place in a parallel universe in which family structures and countries have been abolished after a "Great Reckoning" has killed a large share of the world population. In The Gray Area, the seven part serial "Paths Not Taken" takes place in an alternative universe in which Donald Trump has won a second presidential term, gay people are criminalized and arrested, and a violent authoritarian movement known as the "Thanksgiving Cleanse" has swept the nation. In addition, the main universe of the series takes place in a timeline in which Hillary Clinton won the 2016 presidential election. Victoriocity takes place in an alternative 1887 London, where "Queen Victoria is a cyborg and a real-life architect is worshipped by a legion of laborers."

Video games

* In the adventure game ''9: The Last Resort'' (1996), after resolving several mind-blowing and unique puzzles, the player gets past "The Tiki Guards"; and a door opens up to "The Void" - actually a room to another universe, which houses the entirety of space. * ''Banjo-Kazooie (video game), Banjo-Kazooie'' (1998) features a world called "Click Clock Wood", which has spring, summer, autumn and winter variants. The environment develops between the seasons making some areas accessible or inaccessible, and actions taken in one season affect the outcome in others. * The first-person shooter ''BioShock Infinite'' (2013) features the many worlds interpretation of quantum mechanics. The main character is named Booker Dewitt, an homage to physicist ''Bryce DeWitt''. * The 2018 fighting game ''BlazBlue: Cross Tag Battle'' brings together the universes in a ''BlazBlue'', ''Persona 4 Arena'', ''Under Night In-Birth'', and ''RWBY'' in a singularity called the “Phantom Field” where the characters fight over the “Keystones”. * The story of ''Chrono Cross'' (1999) centers around travel between two alternative timelines, the original or "Another World" and "Home World" which is a Many-worlds interpretation, branch created by the actions of the heroes of the game's predecessor, ''Chrono Trigger''. *''City of Heroes'' (2004), a massively multiplayer online role-playing game, features a Player vs Player (PvP) zone called Recluse's Victory. It is an alternative future in a constant state of flux, as heroes and villains battle for the future of Earth. * ''Crash Twinsanity'' (2004) features Crash, Cortex, and Nina traveling to the "10th dimension", which could also be a parallel universe (suggested by the theme and how everything seems to be opposite, with the presence of an "Evil Crash", and also planned to have "Good Cortex" and "Evil Coco", but they were cut during development). * In the psychological horror point-and-click adventure game ''Dark Seed (video game), Dark Seed'' (1992), the main character Mike Dawson discovers a parallel universe by going through his living room mirror. * ''The Darkness (video game), The Darkness'' (2007) pivots around a world of darkness you travel to when you die, which is occupied by World War 1 soldiers. * ''EarthBound'' (1994) features many areas of the game that can be considered alternative dimensions. The first is an illusion created by the Mani Mani Statue that transforms the metropolis of Fourside into a bizarre neon metropolis called Moonside, filled with unusual characters and enemies. The second is Magicant, the world of Ness's subconscious that is accessed after obtaining the Eight Melodies. Finally, toward the end of the game, the protagonists arrive at the Cave to the Past, where they travel back in time to the haunting past dimension of the cave to face Giygas. * ''The Elder Scrolls IV: Oblivion'' (2006) 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. *''Fallout (series), Fallout'' series (1997– ) takes place in a subtly different universe. For example, the ship that landed the first men on the moon in 1969 is called ''Valiant 11'', rather than Apollo 11. This universe diverged from ours after World War II, which resulted in a lack of advanced computers, the Cold War, VHS, etc. * In Freedom Force (2002 video game), ''Freedom Force'' (2002), most of the story is set in Patriot City, but a number of other locations and time periods are used, including magical realms, prehistoric times, and realms entirely removed from time and space. *''Half-Life (series), Half-Life'' series (1998– ) revolves heavily around alternative universes. Xen is a location in the first ''Half-Life'' game, accidentally discovered by scientists and described as a border world between dimensions, where the player must travel to stop an alien invasion. Half-Life 2 features a multidimensional empire called Combine (Half-Life), The Combine which has successfully conquered Earth and subdued humanity, among countless other universes and species. *''Heroes of the Storm'' (2015) takes place in the Nexus, a strange limbo of clashing universes, which collide from across space, time, and dimensions. The Nexus exists in the center of a trans-dimensional cosmic storm, which can rip worlds and universes in and out of existence, and it can also pull worlds into stability. Some of the central realms in the Nexus are examples of these points of stability. Every Realm within the Nexus has one stone called "Singularity", and only the one who achieves it through conquest can become the Realm Lord. Many powerful warriors have been sucked into the Nexus, including combatants from ''Warcraft'', ''StarCraft (series), StarCraft'', ''Diablo (series), Diablo'', and Overwatch (video game), ''Overwatch'' universes. New combatants are constantly arriving, some of them are chosen after they died in their original reality. *''Kingdom Hearts'' series (2002– ) features a Disney/Square Enix's ''Final Fantasy'' multiverse, in which various worlds are based on Disney films or concepts from the ''Final Fantasy'' line. The series also introduces the concept of different "Realms" corresponding to Light, Darkness, and In-Between where all of the worlds take place. * The series ''Legacy of Kain'' (1996– ) is played through several realms and timelines. * ''The Legend of Zelda: A Link to the Past'' (1991) features a dark and twisted parallel version of Hyrule called the "Dark World". In the ''The Legend of Zelda: Ocarina of Time, Ocarina of Time'' (1998) after the main protagonist, Link, defeats the dark lord, Ganon, he travels back in time to his childhood. This results in two alternative histories for Hyrule. In one a younger version Link travels to the land of Termina in ''The Legend of Zelda: Majora's Mask, Majora's Mask'' (2000). In the other Link is no longer present allowing Ganon to return to go on a rampage that forced the gods of Hyrule to flood the world in ''The Legend of Zelda: The Wind Waker, The Wind Waker'' (2002). There is also a scenario in which Link is killed by Ganon in the final battle, resulting in an alternative history in which Hyrule is put in an era of decline, leading to the events of ''The Legend of Zelda: A Link to the Past, A Link to the Past''. The ''The Legend of Zelda: Majora's Mask, Majora's Mask'' takes place in Termina, a parallel world to Hyrule. Almost all of the characters from ''The Legend of Zelda: Ocarina of Time, Ocarina of Time'' reappear in the game. The ''The Legend of Zelda: Oracle of Seasons and Oracle of Ages, Oracle of Seasons and Oracle of Ages'' (2001) use a similar concept to that which is used in ''The Legend of Zelda: A Link to the Past, A Link to the Past''. In those games, the player must switch between the parallel past and present worlds (Ages) and between spring, summer, autumn and winter (Seasons) to progress through the game. In the first half of ''The Legend of Zelda: Twilight Princess, Twilight Princess'' (2006), areas of Hyrule are veiled by the Twilight Realm. These areas are dusky and brooding in appearance, Link cannot transform out of wolf form, characters only appear as spirits that cannot be communicated with, and enemies are twilight variations of their regular forms. Otherwise, the Twilight Realm is identical to regular Hyrule. * The world of the classic cult adventure games of ''The Longest Journey'' (1999) created by Ragnar Thornqast, along with its sequels, deals with the existence of two parallel universes – technological (Stark) and magical (Arcadia). * ''Metroid Prime 2: Echoes'' (2004) involves a world, "Aether", having an alternative self in the, "Dark" realm, universe, or dimension. The protagonist, Samus, finds out that she just dropped into 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. * In the adventure PC game ''Myst'' (1993), the unnamed protagonist travels to multiple alternative 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 ''OtherSpace'' (1998), a text-based science fiction MMORPG, refugees from Earth's universe were forced to migrate to a parallel universe called "Hiverspace", whose quantum divergence occurred billions of years in the past, after damage to the time/space continuum began to tear their own universe apart. Eventually, they were able to find a means back to a past universe whose quantum divergence from their original ones was relatively minor. * In the role-playing game ''Outcast (video game), Outcast'' (1999), 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 in order to retrieve and repair the damaged probe before the earth is consumed by a black hole. * ''Persona 2: Eternal Punishment'' (2000) takes place in an alternative universe called "This Side" where in the events of Innocent Sin did not take place and the characters have never met in the past. * ''Persona 4'' (2008) features the main cast entering an alternate dimension called the TV World, which exists as part of the Collective Unconscious in the larger ''Megami Tensei'' multiverse, to find a serial killer in the town of Inaba. *''Portal 2'' (2011), an action-adventure video game, features a game-mode entitled "Perpetual Testing Initiative" (PeTI), where a plot item features protagonist "Bendy" through thousands of different worlds of which character Cave Johnson exist in different roles entitled "The Multiverse", and the PeTI's parallel universes are different from the main ''Half-Life''/''Portal'' timeline. * ''Resistance: Fall of Man'' (2006) is set in alternative universe where Tsarist Russia never experienced the Russian Revolution but instead became the bridgehead for an aggressive alien invasion from a species known as the "Chimera", who then proceed to overrun Western Europe, Great Britain, Canada and much of the United States, and where there has been no Second World War as a result. The events of the game and its sequels begin in its alternative 1951. * In the survival horror video game series ''Silent Hill'' (1999– ), the town of Silent Hill fluctuates between the real world, where ''Silent Hill'' is seemingly just an ordinary tourist town, the Fog World, which is like the real world, except the town is shrouded in thick fog and is nearly uninhabited except for monsters and a few people, and a dark and dilapidated version of the town called the "Other World". * Each Zone in ''Sonic CD'' (1993) has four variations: Past, Present, Bad Future and Good Future, each displaying some subtle and not-so subtle alterations. The series has also seen alternative dimensions, and parallel universes in the case of the ''Sonic Rush'' (2005), in which Sonic the Hedgehog (character), Sonic encounters a hero from another world named Blaze the Cat whose nemesis is an alternative counterpart of his own foe, Dr. Eggman. The ''Sonic'' series of Sonic The Hedgehog 2006, Generations And Rivals also makes use of the concept of Wormholes, and alternative timelines. * ''Sudeki'' (2004) is set in a realm of light and a parallel realm of darkness. * ''Super Mario 64'' (1996) features a world called "Tiny Huge Island" which has two variants: one scaled up, the other scaled down. The player can only access certain parts of the level to obtain certain stars depending on which variant they are into. The two variants can be switched between via portals in the world. * ''Super Mario Bros. 2'' (1988) features a "Magic Potion" item that when used, creates a doorway allowing the player to temporarily access "Subspace"; a mirrored silhouette version of the world where items can be found. * After the completion of the Special World in ''Super Mario World'' (1990), the overworld transforms from a green-colored springtime to an orange-colored autumnal setting. Many enemies encountered in the game are transformed into bizarre counterparts. * In ''Super Paper Mario'' (2007), the town "Flipside" (which acts as the game's central hub) has an alternative mirrored version called "Flopside". While Flipside appears pristine and the residents there are typically cheerful, Flopside appears somewhat dilapidated and is populated by surly characters. * Both titles of the ''When They Cry'' visual novel series (''Higurashi no Naku Koro ni, Higurashi'' and ''Umineko'' for short) contain the concept of parallel worlds. These series both involve some kind of murder mystery. 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 visual novel/puzzle video game series ''Zero Escape'' heavily uses the concept of multiple realities as the basis for its plot as well as its central gameplay mechanic of traversing through realities and altering history. In this fictional universe, characters use a method of travelling between different timelines called "SHIFT" (short for "Spacetime Human Internal Fluctuating Travel"). * In the Kirby (series), Kirby series, some of the most prominent locations are other dimensions in the form of Another Dimension, The Mirror World, Cyberspace, Dreamscape, and much more. * The survival video game Don't Starve (2013) involves the many playable characters efforts to survive in a semi-nightmarish parallel world of wilderness known as the Constant, the story reveals that much of the world was once ruled by a race of sentient and technologically advanced arthropodal creatures, who destroyed themselves with the overuse of nightmare fuel, the Constant appears to change according to how afraid the characters are feeling, and is now controlled by mysterious shadow creatures that appear to those who are afraid and is also somewhat controlled by whoever is trapped on the "nightmare throne". * ''Agents of Mayhem'' is set in an alternative universe to the Saints Row series in which the Third Street Saints never forms, which leads up to Vice Kings, Los Carnales and Westside Rollerz uniting into one gang. * In ''Left 4 Dead 2'' The Last Stand Update (2020), release The Last Stand map where all players case that the survivors took a different path leading to the Death Toll Finale. Instead of going to the Boathouse, players choose to go to the Lighthouse by a truck. Players must light the long-disused lighthouse and fight against a lot of infected to wait a rescue boat.

Fan fiction

References

External links

*
Parallel Universe: is there any other life?

Bibliography

* * {{Film genres Parallel universes in fiction, Fiction Science fiction themes Setting

Science fiction

Hyperspace

Time travel

Multiple worlds and time travel

Similar concepts

Counter-Earth

Convergent evolution and parallel evolution

Simulated reality

Parallel Universe Theory

Fantasy

Transportation of modern characters to fantasy universe

Between the worlds

Fantasy multiverses

Fictional universe as alternative universe

Elfland

Isekai

Films

Television

As an ongoing subplot

Television series involving parallel universes

Books

Comic books

Audio drama

Video games

Fan fiction

See also

References

External links

Bibliography