The grandfather paradox is a paradox of time travel, first described by the science fiction writer René Barjavel in his 1943 book "Le Voyageur Imprudent" ("The Imprudent Traveller").^[1] The paradox is this: Suppose a man traveled back in time and killed his biological grandfather before the latter met the traveller's grandmother. As a result, one of the traveller's parents (and by extension, the traveller himself) would never have been conceived. This would imply that he could not have travelled back in time after all, which in turn implies the grandfather would still be alive, and the traveller would have been conceived, allowing him to travel back in time and kill his grandfather. Thus each possibility seems to imply its own negation, a type of logical paradox. A physical paradox is an apparent contradiction relating to physical descriptions of the universe. ... Time travel is a concept that has long fascinated humanity—whether it is Merlin experiencing time backwards, or religious traditions like Mohammeds trip to Jerusalem and ascent to heaven, returning before a glass knocked over had spilt its contents. ... René Barjavel (January 24, 1911 - November 24, 1985) was a French author, journalist and critic who supposedly was the first to think of the Grandfather paradox. ... Year 1943 (MCMXLIII) was a common year starting on Friday (the link will display full 1943 calendar) of the Gregorian calendar. ...

An equivalent paradox is known (in philosophy) as autoinfanticide — that is, going back in time and killing oneself as a baby — though when the word was first coined in a paper by Paul Horwich it was in the malformed version autofanticide. ^[2] The philosopher Socrates about to take poison hemlock as ordered by the court. ... Paul Horwich (born 1947) is a British analytic philosopher at New York University, whose work includes writings on causality, truth and meaning. ...

The grandfather paradox has been used to argue that backwards time travel must be impossible. However, other resolutions have also been advanced.

Scientific theories

Complementary time travel

Since quantum mechanics is governed by probabilities, an unmeasured entity (in this case, your historical grandfather) has numerous probable states. When that entity is measured, the number of its probable states singularises, resulting in a single outcome (in this case, ultimately, you). Therefore, since the outcome of your grandfather is known, you killing your grandfather would be incompatible with that outcome. Thus, the outcome of one's trip backwards in time must be complementary with the state from which one left.^[3] Fig. ... In physics, the term state is used in several related senses, each of which expresses something about the way a physical system is. ... The framework of quantum mechanics requires a careful definition of measurement, and a thorough discussion of its practical and philosophical implications. ... // In physics, complementarity is a basic principle of quantum theory closely identified with the Copenhagen interpretation, and refers to effects such as the wave-particle duality, in which different measurements made on a system reveal it to have either particle-like or wave-like properties. ...

Novikov self-consistency principle

See the Novikov self-consistency principle and Kip S. Thorne for one view on how backwards time travel could be possible without a danger of paradoxes. According to this hypothesis, the only possible timelines are those which are entirely self-consistent, so that anything a time traveler does in the past must have been part of history all along, and the time traveler can never do anything to prevent the trip back in time from being made since this would represent an inconsistency. This article or section does not cite its references or sources. ... Kip S. Thorne Professor Kip Stephen Thorne, Ph. ...

Parallel universes/alternate timelines

There could be "an ensemble of parallel universes" such that when the traveller kills the grandfather, the act took place in (or resulted in the creation of) a parallel universe in which the traveller's counterpart will never be conceived as a result. However, his prior existence in the original universe is unaltered. Parallel universe or alternate reality in science fiction and fantasy is a self-contained separate reality coexisting with our own. ...

Examples of parallel universes postulated in physics are:

• In quantum mechanics, the many-worlds interpretation suggests that every seemingly random quantum event with a non-zero probability actually occurs in all possible ways in different "worlds", so that history is constantly branching into different alternatives. The physicist David Deutsch has argued that if backwards time travel is possible, it should result in the traveler ending up in a different branch of history than the one he departed from.^[4] See also quantum suicide and quantum immortality.

• M-theory is put forward as a hypothetical master theory that unifies the five superstring theories, although at present it is largely incomplete. One possible consequence of ideas drawn from M-theory is that multiple universes in the form of 3-dimensional membranes known as branes could exist side-by-side in a fourth large spatial dimension (which is distinct from the concept of time as a fourth dimension) - see Brane cosmology. It is theorized that when two branes collide it sends a massive ripple of heat and energy throughout the two. This is a possible explanation of what caused the big bang according to the ekpyrotic scenario and the cyclic model. However, there is currently no argument from physics that there would be one brane for each physically possible version of history as in the many-worlds interpretation, nor is there any argument that time travel would take one to a different brane.

Fig. ... The many-worlds interpretation or MWI (also known as relative state formulation, theory of the universal wavefunction, many-universes interpretation, Oxford interpretation or many worlds), is an interpretation of quantum mechanics that claims to resolve all the paradoxes of quantum theory by allowing every possible outcome to every event to... David Deutsch (born 1953) is a physicist at Oxford University. ... In quantum mechanics, quantum suicide is a thought experiment which was independently proposed in 1987 by Hans Moravec and in 1988 by Bruno Marchal, and further developed by Max Tegmark in 1998, that attempts to distinguish between the Copenhagen interpretation of quantum mechanics and the Everett many-worlds interpretation by... It has been suggested that Quantum suicide be merged into this article or section. ... M-theory is a solution proposed for the unknown theory of everything which would combine all five superstring theories and 11-dimensional supergravity together. ... Superstring theory is an attempt to explain all of the particles and fundamental forces of nature in one theory by modeling them as vibrations of tiny supersymmetric strings. ... For other uses, see Multiverse (disambiguation). ... This article or section is in need of attention from an expert on the subject. ... Brane cosmology is a protoscience motivated by, but not rigorously derived from, superstring theory and M-theory. ... For other uses, see Big Bang (disambiguation). ... The ekpyrotic universe or ekpyrotic scenario is a cosmological theory of the origin of the universe. ... The cyclic model is a brane cosmology model of the creation of the universe, derived from the earlier ekpyrotic model. ...

Theories in science fiction

Parallel universes resolution

The idea of preventing paradoxes by supposing that the time traveler is taken to a parallel universe while his original history remains intact, which is discussed above in the context of science, is also common in science fiction - see Time travel as a means of creating historical divergences. Some examples of this type of story: Alternate history (fiction) - Wikipedia, the free encyclopedia /**/ @import /skins-1. ...

• Michael Crichton's novel Timeline. However, unlike most time travel stories based on parallel universes, Crichton's novel seems to imply that changes to universes which resemble our own past can affect the universe we live in. The example given is when a professor trapped in the past sends a message to his graduate students at a medieval monastery.

• In the Marvel Universe comic books, any change made to the timeline results in an alternate timeline (for example, Professor X's son Legion attempted to kill Magneto, he accidentally killed Professor X, creating the Age of Apocalypse Timeline). Some characters know this and use it to their advantage (such as Vance Astro of the Guardians of the Galaxy, whose timeline shift allowed an alternate self to become Justice.)

• In L. Sprague de Camp's Lest Darkness Fall, a modern historian is thrown back in time to the period immediately after the fall of the Roman Empire, and introduces many anachronistic technical innovations and especially printing - thus creating a timeline where the dark ages do not happen and the achievements of Classical civilization are to a great degree preserved, and boosted by many inventions appearing a millennium or more ahead of schedule. This does not, however, change the original timeline he came from, in which world culture and society are still the result of Classical civilization having collapsed and a new civilization gradually taking its place.

• In Dragon Ball Z, Trunks travels to a parallel universe's past and saves the heroes while they remain dead in his own world several years in the future. Later, in the universe in which Trunks saves the heroes, Cell travels from a different universe in which Trunks had been killed by him.

• In Primer, the characters Abe and Aaron are able to go back in time and affect their previous selves (by either drugging them or locking them away somewhere). They had arguments about continuity and the like, but besides that "The only thing that matters is what is happening right now."

• In Donnie Darko, the entire movie takes place within a Tangent Universe that occurs because of a rip in the space-time continuum. Within the Tangent Universe, Donnie's girlfriend dies, leading him to travel backwards in time to return to the normal universe, where he has died instead.

• In Metal Gear Solid 3: Snake Eater, if Naked Snake does an action which would prevent situations in the future Metal Gear timeline, such as killing Revolver Ocelot or he himself being killed, the mission becomes a failure, and Roy Campbell informs him of the "Time Paradox" that he created with his actions. This is humorously explored in "Metal Gear Raiden: Snake Eraser", where Raiden interferes with many events in the game.

• In The Legend Of Zelda: Ocarina of Time, the entire second half of the game is based on time travelling. The main character of the game (Link) uses the Ocarina of Time to travel through 2 specific points in time seven years apart. This creates a paradox in which Link learns a song in the future, then returns to the past and teaches it to the man who taught it to him.

Michael Crichton, pronounced [1], (born October 23, 1942) is an American author, film producer, film director, and television producer. ... Timeline is a science fiction novel by Michael Crichton that was published in November 1999. ... Monastery of St. ... This does not cite any references or sources. ... Legion (David Charles Haller) was the Marvel Comics character responsible for creating the alternate timeline known as the Age of Apocalypse. ... Magneto (Eric Magnus Lensherr) is a fictional character in the Marvel Comics universe. ... The Age of Apocalypse is a popular X-Men story arc. ... Vance Astrovik, aka Justice, is a fictional mutant superhero in the Marvel Comics universe. ... The Guardians of the Galaxy are a fictional superhero team active in the 31st century in an alternate timeline that is a version of the Marvel Universe. ... Lyon Sprague de Camp, (November 27, 1907 – November 6, 2000) was an American science fiction and fantasy author. ... Lest Darkness Fall is an alternate history science fiction novel written in 1939 by author L. Sprague de Camp. ... For other uses, see Roman Empire (disambiguation). ... For other uses, see Print. ... Petrarch, who conceived the idea of a European Dark Age. From Cycle of Famous Men and Women, Andrea di Bartolo di Bargillac, c. ... Classical antiquity is a broad term for a long period of cultural history centered on the Mediterranean Sea, which begins roughly with the earliest-recorded Greek poetry of Homer (7th century BC), and continues through the rise of Christianity and the fall of the Western Roman Empire (5th century AD... “DBZ” redirects here. ... For the same Dragon Ball Z character from an alternate timeline, see Future Trunks. ... Primer is a 2004 independent film written, directed, produced by and starring Shane Carruth. ... For the fictional character, see Donald Darko. ... Metal Gear Solid 3: Snake Eater (commonly abbreviated MGS3) is a stealth-based game directed by Hideo Kojima, developed and published by Konami for the PlayStation 2. ... This article or section contains a plot summary that is overly long. ... For the original video game titled Metal Gear, see Metal Gear. ... Revolver Ocelot ) is an antagonist in the Metal Gear video game series created by game designer Hideo Kojima. ... Colonel Roy Campbell is Solid Snakes commanding officer throughout the majority of the Metal Gear series. ... Raiden (real name Jack) is a character in the Metal Gear series. ... The Legend of Zelda: Ocarina of Time was a video game released in 1998, and the first Zelda game for the Nintendo 64. ... Link ) is the protagonist of Nintendos The Legend of Zelda video game series, created by Shigeru Miyamoto. ...

Restricted action resolution

See also: Predestination paradoxes in fiction

Another resolution, of which the Novikov self-consistency principle can be taken as an example, holds that if one were to travel back in time, the laws of nature (or other intervening cause) would simply forbid the traveller from doing anything that could later result in their time travel not occurring. For example, a shot fired at the traveller's grandfather will miss, or the gun will jam, or misfire, or the grandfather will be injured but not killed, or the person killed will turn out to be not the real grandfather, or some other event will occur to prevent the attempt from succeeding. No action the traveller takes to affect change will ever succeed, as there will always be some form of "bad luck" or coincidence preventing the outcome. In effect, the traveller will be unable to change history from the state they found it. Very commonly in fiction, the time traveller does not merely fail to prevent the actions he seeks to prevent; he in fact precipitates them (see predestination paradox), usually by accident. Many fictional and mythological works have dealt with various circumstances that can logically arise from time travel, usually dealing with paradoxes. ... This article or section does not cite its references or sources. ... A predestination paradox, also called either a causal loop, or a causality loop and (less frequently) either a closed loop or closed time loop, is a paradox of time travel that is often used as a convention in science fiction. ...

This theory might lead to concerns about the existence of free will (in this model, free will may be an illusion). This theory also assumes that causality must be constant: i.e. that nothing can occur in the absence of cause, whereas some theories hold that an event may remain constant even if its initial cause was subsequently eliminated. Free-Will is a Japanese independent record label founded in 1986. ...

Closely related but distinct is the notion of the time line as self-healing. The time-traveler's actions are like throwing a stone in a large lake; the ripples spread, but are soon swamped by the effect of the existing waves. For instance, a time traveller could assassinate a politician who led his country into a disastrous war, but the politician's followers would then use his murder as a pretext for the war, and the emotional effect of that would cancel out the loss of the politician's charisma. Or the traveller could prevent a car crash from killing a loved one, only to have the loved one killed by a mugger, or fall down the stairs, choke on a meal, killed by a stray bullet, etc. In some stories it is only the event that precipitated the time traveler's decision to travel back in time that cannot be substantially changed, in others all attempted changes will be "healed" in this way, and in still others the universe can heal most changes but not sufficiently drastic ones. This is also the explanation advanced by the Dr. Who roleplaying game, which supposes that Time is like a stream; you can dam it, divert it, or block it, but the overall direction it is headed will resume after a period of conflict.

It also may not be clear whether the time traveller altered the past or precipitated the future he remembers, such as a time traveller who goes back in time to persuade an artist -- whose single surviving work is famous -- to hide the rest of the works to protect them. If, on returning to his time, he finds that these works are now well-known, he knows he has changed the past. On the other hand, he may return to a future exactly as he remembers, except that a week after his return, the works are found. Were they actually destroyed, as he believed when he travelled in time, and has he preserved them? Or was their disappearance occasioned by the artist's hiding them at his urging, and the skill with which they were hidden, and so the long time to find them, stemmed from his urgency?

Examples of this set of theories include:

• Oedipus Rex, where the actions undertaken to thwart a prophecy bring it about: Cronus' swallowing of his children to prevent their usurping his power is what encouraged Zeus to overthrow him, and Oedipus's being abandoned led him to meet his mother without being aware of her identity. This, and other folk tales involving prophecies (wherein the 'time travel' is of information), form the oldest known occurrences of the predestination paradox.
• The 2002 movie version of The Time Machine, in which the main character cannot save his girlfriend by going back in time, as he only started building the time machine out of frustration at her death. This loop is not present in the original book.
• In the films Twelve Monkeys and La Jetee, the main character not only is unable to prevent a tragic past event from occurring, but even realizes that, as a child, he witnessed his adult self failing in the attempt. Moreover the perpetrator of some of the related events was inspired to bring them about as a result of speaking to the protagonist.
• Douglas Adams's Hitchhiker Series makes use of this resolution for light-hearted and comic plots; for instance, an Infinite Improbability Drive, designed by life-forms, travels back in time and rearranges a group of atoms, thereby creating life.^{[citation needed]}
• Harry Harrison's The Technicolor Time Machine uses this resolution for light-hearted and comic plots; when a film-maker goes back in time to make a film of the Viking colonization of America, it proves, in the end, to be the cause of the Vikings' colonization of America, with the film-maker himself appearing in the sagas they used as their source.
• In Castle Roogna, Piers Anthony has the magician Murphy persuade the time-traveler Dor to remain out of a conflict, because he might tamper with the past, but Dor's subsequent actions did affect it, and in his own time, while everything appears unaltered, a discussion points out that later disasters may have made his beneficial effect appear to have disappeared.
• In the 1969 science fiction novel Behold the Man by Michael Moorcock,the protagonist Karl Glogauer builds a time machine in order to travel back to the Holy Land 2000 years in the past. His intention is to prove the existence of Jesus Christ. When he discovers that in fact Christ actually suffered from severe physical and learning disabilities, Glogauer decides to act out his role as recorded in the Bible, faking the miracles and finally being crucified. This implies that the person called "Jesus Christ" that Glogauer had read about in the Bible, and that spurred his decision to travel back in time, was actually himself all along, an example of a predestination paradox.
• An especially vicious example is Eric Norden's novella "The Primal Solution". An elderly Jewish scientist - Holocaust survivor, who had lost his entire family - discovers a way of "mental time travel", which enables him to project his mind into the past and take over the body of the young Adolf Hitler in the Vienna of the early 1910s. Resolved to force Hitler into suicide, the vengeful professor can't resist humiliating him first and forcing him to drink sewer water in front of surprised passers by, before making him jump into the Danube - but in the moment before drowning, Hilter regains control of his body and returns home shaken. The Professor is trapped inside Hitler's mind, but is able to "hear" him think "The Jews? Why did the Jews do this to me? I have never harmed them!". Being able to access Hitler's memories, the trapped Professor suddenly realizes that until this moment the young Hitler had not at all been an Antisemite and was in fact on good terms with some Jews. Only because something inexplicable had entered Hitler's mind - something which totally hates him and is implacably bent on his destruction, and which identifies itself as being Jewish and acting on behalf of all Jews - that he would become the genocidal Hitler known to history. Never daring to tell anybody of this presence in his mind, for fear of being considered insane, Hitler would gradually develop the idea that only by killing all Jews would he be free of that haunting presence. In short - the very act intended to avert the Holocaust ends up being its direct cause.
• A similar example was featured in Cradle of Darkness, a modern episode of The Twilight Zone, in which a young woman goes back in time and is employed as a nanny for the infant Hitler. She abducts the baby jumps into the Danube, killing them both. However, the family maid has chased her and witnesses their deaths. Fearing that the news will send her mistress, already frail from the loss of her previous children,over the edge, she pays a homeless Gypsy mother for her child. This infant is brought back home and presented as the original. It is he, and not the actual baby Hitler who will grow into the monstrous dictator.
• In the Futurama episode "Roswell That Ends Well," the crew travels back in time, and Fry tries to protect Enos, his grandfather, from being killed, but only causes him to die in a nuclear explosion. Fry, reasoning that the woman he thought to be his grandmother cannot be his grandmother (since Fry still exists after Enos's death), has sex with her and impregnates her, thus becoming his own grandfather.
• In the Star Trek: The Next Generation episode Time's Arrow, Data's head is found at the bottom of a nineteenth century mineshaft in San Francisco. Data concludes that at some point in the future, he will travel back in time and mislay his head. This indeed occurs. At the conclusion of the episode, the head recovered from the mineshaft is placed on Data's body, which returned to the 24th century with the crew. Data's head is therefore five hundred years older than his body, but the past has not been altered. Time's Arrow is highly unusual amongst Star Trek episodes, which generally permit alterations of the timeline.
• In the Simpsons Halloween Special "Treehouse of Horror V" segment Time and Punishment, Homer breaks the toaster when he gets his hand caught in it. He uses strange and unusual methods to fix it, so that by the time it is fixed, it has all sorts of new wiring and odd flashing lights. He tests it and it takes him through time to the dinosaurs. He remembers some unusual advice his father gave him at his wedding, "If you ever go back in time, don't step on anything. Because even the tiniest change can alter the future in ways you can't imagine". A mosquito buzzes around Homer's head and is annoying him so he squashes it and then when he arrives back in the present, the world is controlled by his neighbor Ned Flanders. He goes back in time to sort it out but accidentally sits on a fish that has evolved to walk on land. When he goes back to the present the human race is a race of giants and Bart and Lisa see Homer and Bart says "Hey, there's a bug that looks like Dad, let's kill it!". Homer flees back in time again and sneezes which kills every single dinosaur nearby. When he goes back to the present his family are extremely rich and well behaved but when he thinks nothing could be better, he asks for a dough nut and there appears to be no such thing. He screams and flees, but unknown to him it has just started raining dough nuts. Back in dinosaur times he decides that he doesn't care and starts killing anything in sight. Back in the present, the Simpsons house undergoes various changes, as Homer kills different animals, at one time looking like The Flintstones' house. After he returns to the "present," all seems normal but when the family sit down to eat they have lizard tongues. Homer shrugs and says "Close enough".
• In Stargate SG1 the crew goes multiple time back and forth through time by doing a slingshot around the sun at the same moment a solar flare occurs
• in the Invader Zim episode "bad bad rubber piggy" zim plans on destroying his enemy, Dib in the past. Gir points out that if Zim destroys Dib in the past, then he wont have to go back and destroy him in the future, and therefore the process will be cancelled out. This parodox makes Girs head explode.

Greek Wikisource has original text related to this article: Oedipus the King Oedipus the King (Greek , Oedipus Tyrannos), also known as Oedipus Rex, is a Greek tragedy, written by Sophocles and first performed in 428 BC. The play was the second of Sophocles three Theban plays to be produced, but... This article needs additional references or sources for verification. ... The Statue of Zeus at Olympia Phidias created the 12-m (40-ft) tall statue of Zeus at Olympia about 435 BC. The statue was perhaps the most famous sculpture in Ancient Greece, imagined here in a 16th century engraving Zeus (in Greek: nominative: Zeús, genitive: Diós), is... The Time Machine is a 2002 science fiction film directed by Simon Wells as a remake of The Time Machine (1960), and starring Guy Pearce, Jeremy Irons, Orlando Jones, Samantha Mumba, Mark Addy, Sienna Guillory, and Phyllida Law with a cameo by Alan Young from the earlier film. ... The Time Machine is a novel by H. G. Wells, first published in 1895, later made into two films of the same title. ... Twelve Monkeys is a 1995 science fiction film written by David and Janet Peoples and directed by Terry Gilliam. ... La Jetée (1962 or 1963) (literally The Jetty or The Pier, but in this case idiomatically meaning The Terminal, as in an airport terminal) is a black and white 28-minute science fiction film by Chris Marker. ... Douglas Noël Adams (11 March 1952 – 11 May 2001) was an English author, comic radio dramatist, and musician. ... The cover of the first novel in the Hitchhikers series, from a late 1990s printing. ... The Infinite Improbability Drive is a fictional faster-than-light drive in Douglas Adams The Hitchhikers Guide to the Galaxy series of books. ... At the 63rd World Science Fiction Convention in Glasgow, August 2005 Harry Harrison (born Henry Maxwell Dempsey, March 12, 1925 in Stamford, Connecticut) is an American science fiction author who has lived in many parts of the world including Mexico, England, Denmark and Italy. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The third Xanth novel by Piers Anthony. ... Piers Anthony Dillingham Jacob (born August 6, 1934 in Oxford, England) is a writer in the science fiction and fantasy genres, publishing under the name Piers Anthony. ... Spoiler warning: // Aeolus The eighteenth king of Xanth The Magician of Storms, King of Xanth prior to King Trent. ... Spoiler warning: // Aeolus The eighteenth king of Xanth The Magician of Storms, King of Xanth prior to King Trent. ... Behold the Man is a novella by Michael Moorcock, first published in 1966 by New Worlds S.F. It is the story of one Karl Glogauer who travels back in time in a time machine constructed by one Sir James Headington (physicist and wartime inventor) to the year 28 of... Michael John Moorcock (born December 18, 1939, in London, England) is a prolific English writer primarily of science fiction and fantasy who has also published a number of literary novels. ... Karl Glogauer is the protagonist of several novels by Michael Moorcock, and a secondary character in multiple short stories. ... It has been suggested that this article or section be merged with Holy Land (Biblical). ... Wikipedia does not yet have an article with this exact name. ... In the United States and Canada, the term learning disability (LD) is used to refer to a range of neurological conditions that affect one or more of the ways that a person takes in, stores, or uses information. ... This Gutenberg Bible is displayed by the United States Library. ... A predestination paradox, also called either a causal loop, or a causality loop and (less frequently) either a closed loop or closed time loop, is a paradox of time travel that is often used as a convention in science fiction. ... For other uses, see Holocaust (disambiguation) and Shoah (disambiguation). ... Hitler redirects here. ... “Wien” redirects here. ... This article is about the Danube River. ... Anti-Semitism (alternatively spelled antisemitism) is hostility towards Jews (not: Semites - see the Misnomer section further on). ... The Twilight Zone title. ... Adolf Hitler Adolf Hitler (April 20, 1889 – April 30, 1945, standard German pronunciation in the IPA) was the Führer (leader) of the National Socialist German Workers Party (Nazi Party) and of Nazi Germany from 1933 to 1945. ... This article is about the television series. ... Roswell That Ends Well is the nineteenth episode of the third production season of the TV show Futurama. ... Philip J. Fry is the protagonist of the animated television series Futurama and is voiced by Billy West. ... The title as it appeared in most episodes opening credits. ... Data[1] is a character, portrayed by Brent Spiner, in the Star Trek fictional universe. ... Simpsons redirects here. ... Treehouse of Horror V is the sixth episode of The Simpsons sixth season, which originally aired October 30, 1994. ... Homer Simpson is also a character in the book and film The Day of the Locust. ... For other uses, see Mosquito (disambiguation). ... Nedward Ned Flanders is a fictional character on The Simpsons, based on the real life Donald Macmillan, heir to the Alcan Fortune, voiced by Harry Shearer. ... For the comic book series of the same name, see Bart Simpson comics. ... Lisa Marie Simpson is a character in the animated television series The Simpsons, voiced by Yeardley Smith; Lisa is the only character Smith voices on a regular basis. ... The Flintstones is an American animated television series produced by Hanna-Barbera Productions. ... Stargate SG-1 Cast Stargate SG-1 is a television series based upon the 1994 science fiction movie Stargate. ... Invader Zim is an American animated television series created by comic book writer/artist Jhonen Vasquez and aired on Nickelodeon. ...

Relative timelines resolution

It could be that the universe does not have an absolute timeline that is permanently written after events happen (or, in the deterministic view, at the start of time). Instead, each particle has its own timeline and therefore, humans have their own timeline. This might be considered similar to the theory of relativity, except that it deals with a particle's history, rather than its velocity. Two-dimensional analogy of space-time curvature described in General Relativity. ...

Physical forces affect physical particles. If your body's physical particles go back in time, you will be able to kill your grandfather (no physical forces will mystically stop you), and nothing will physically happen to you as a result, because there are no physical forces that can "figure out" what happened and this new timeline develops, because the universe simply has no mechanism for unmaking it. Your younger self does not need to be born in order to fulfill a destiny of going back in time, because there is no written-in-stone absolute timeline that needs to be followed. If you were able to find and observe the younger versions of the particles that make you up, they too would follow physical laws and hence wouldn't form into a younger version of you (because one of your parents wouldn't be there to form you).

This theory is similar to the parallel universes theory, except that it happens within one universe. If parallel universes cannot interact again after time travel occurs, then essentially the parallel universe resolution and the relative timelines resolution are the same as there is no way of proving a parallel universe still exists or ever did exist.

Examples include:

• Alfred Bester's short story The Men Who Murdered Mohammed, posits that, once you change the past, you create a solipsistic universe where you can make whatever changes you like, including preventing your own birth. Each time traveller has their own solipsistic time line.

• Orson Scott Card used this theory to allow his characters to travel back in time and change the history of European colonization in the New World in his novel Pastwatch: The Redemption of Christopher Columbus.
• Similarly, this model also appears in James P. Hogan's novel Thrice Upon a Time, although Hogan confusingly uses the term "universes" to describe different moments on the same timeline rather than separate timelines.
• In Poul Anderson's Time Patrol, the Patrol's purpose is to prevent such changes in time, and when they have occurred, undo the changes as neatly as possible, to revert to the "normal" timeline. Such a Time Patrol, under one name or another, is a common feature in stories using this resolution.
• In the film, The Lake House, Kate Forster communicates with Alex Wyler by means of a mysterious mail box even though she lives in 2006 and he lives in 2004. She can send information back through time and he can send it forward. Kate finds out that he died in an automobile accident and warns him not to cross the street that day. Thus forewarned, Alex does not cross the street and is able to join Kate at the mailbox shortly after she delivers the warning. Thus the past that Kate remembers has been changed (Alex hasn't died), and no harmful consequences seem to ensue from this paradox.
• In the television series Seven Days, NSA Agent Frank Parker uses a device called the chronosphere to go back in time, usually one week, to "undo" catastrophic events. This would only be possible if the relative timelines resolution holds, because if Parker succeeds, there would never have been any reason to send him back in time.
• In the essay The Theory and Practice of Time Travel, Larry Niven proposes that, after some unknown number of revisions of history, the effect of some episode of time travel will be to create a universe where time travel, although possible, is simply never discovered. Such a timeline is stable, and in it no paradoxes occur, and so need no resolution.
• In the television series Quantum Leap, Sam is able to use his knowledge of the future to change the past. Sam's actions cause an immediate and noticeable effect on the future, but he and Al remember the past as it happened in the original timeline.

In some works, the replacement is not complete. Characters may "remember" their lives in the original timeline, and more drastic effects may occur. In Jasper Fforde's Thursday Next books, time travelers caused Thursday's husband to drown as a child, but Thursday remained pregnant with his child. Alfred Bester Alfred Bester (born December 18, 1913 in New York City, died September 30, 1987) was a science fiction author and the winner of the first Hugo Award in 1953 for his novel The Demolished Man. ... Solipsism is the philosophical idea that My mind is the only thing that exists. Solipsism (Latin: solus, alone + ipse, self) is an epistemological or metaphysical position that knowledge of anything outside the mind is unjustified. ... The tone or style of this article or section may not be appropriate for Wikipedia. ... Territories in the Americas colonized or claimed by a European great power in 1750. ... Frontispiece of Peter Martyr dAnghieras De orbe novo (On the New World). Carte dAmérique, Guillaume Delisle, 1722. ... At the 63rd World Science Fiction Convention in Glasgow, August 2005 James Patrick Hogan (born June 27, 1941, London) is a science fiction author. ... Thrice Upon A Time is a book by James_P._Hogan_(writer), first published in 1980. ... Poul William Anderson (November 25, 1926–July 31, 2001) was an American science fiction author of the genres Golden Age. ... The Lake House is a 2006 romantic drama film remake of the Korean motion picture Il Mare (2000). ... For other meanings of Seven Days, see Seven Days (disambiguation). ... “NSA” redirects here. ... This article is about a television series. ... This article is about the TV show. ... Information Nickname(s) Al Gender Male Date of birth June 15 1934 Occupation Pilot Companion/Assistant to Samuel Beckett Title Rear Admiral Relationships Beth Children Four daughters Portrayed by Dean Stockwell Created by Donald P. Bellisario Rear Admiral Albert Calavicci is a fictional character on the sci-fi/drama Quantum... Jasper Fforde (born in London on 11 January 1961) is a novelist and aviator living in Wales. ... Thursday Next is the protagonist in the series of novels by Jasper Fforde. ...

Destruction resolution

Some science fiction stories suggest that causing any paradox will cause the destruction of the universe, or at least the parts of space and time affected by the paradox. The plots of such stories tend to revolve around preventing paradoxes.

Examples include:

• In the Back to the Future trilogy, it is speculated by Doc Brown that an encounter between a person and their former self "could create a time paradox, the results of which could cause a chain reaction that would unravel the very fabric of the space-time continuum and destroy the entire universe. Granted, that's a worst-case scenario. The destruction might, in fact, be very localized, limited merely to our own galaxy." However, actual paradoxes are generally averted in the films, so it is never shown if Doc's speculations are correct(he also speculates that one may pass out if encountering ones self in a different timeline, however the latter occurs in the movie.). The filmmakers, in their commentary on the second film of the series, say that they avoided showing one full grandfather paradox, fearing that many viewers would not comprehend what was happening; however, when the character Biff returns from the year 1955 to 2015, he suddenly appears very ill, the camera stops focusing on him, and we never see him again in that time period. This is because his interference in his own past led to his death before 2015. In a deleted scene, he is shown disappearing as the Delorean time machine goes back to the altered past. Presumably, had Doc Brown and Marty found Biff's cane, and stopped to fix the timeline, Biff would have faded back into existence. Marty preventing his parents from meeting has the same ultimate effect of the grandfather paradox. He starts to be "erased from existence", and had he not reversed the effect by getting his parents back together, he would not have been in existence to go back in time and disrupt his parents' meeting in the first place.
• The 2005 Doctor Who series episode "Father's Day" provided a unique version of the destruction resolution. A paradox causes a wound in space-time, which attracts flying chronovorous monsters, Reapers. The Reapers act like bacteria around a real wound, devouring everything, starting with the youngest people and objects, until the wound is "sterilized" and the paradox resolved by its destruction. The deadly rift would have normally been prevented by the Gallifreyians, the Time Lords, but except for the Doctor they had all been destroyed in a war with the Daleks, and the monsters were the universe's own way of preventing the event.
• John Cramer's novel Einstein's Bridge depicts a multiverse consisting of individual Bubbles, normally isolated one from another, except that certain high-energy activities can send signals between Bubbles. The calibration runs of the Superconducting Super Collider (which was built in that timeline) generate a signal which is detected by two civilizations in other Bubbles, one benevolent and one hostile. Transmission of matter between Bubbles is impossible, but information and small amounts of energy can be transferred; the hostile civilization invades our universe in this way, constructing nanomachines by remote control and proceeding to assimilate our world and remake it in their image. To halt and undo the destruction of our civilization, members of the benevolent civilization and two humans construct a "time vortex," an impossible condition which induces our entire universe to unravel itself back a distance of seventeen years, before the SSC brought attention to us. The two humans are somehow pushed back into the past by the vortex, and they use their knowledge of the general course of events to acquire wealth and power and make sure the SSC is not built.

This article is about the first film in the Back to the Future trilogy. ... Doctor Emmett Lathrop Doc Brown is a fictional character, one of the lead characters in the Back to the Future motion picture trilogy, played by actor Christopher Lloyd in the three films and the live action sequences of the animated series. ... A chain reaction is a sequence of reactions where a reactive product or by-product causes additional reactions. ... For other uses of this term, see Spacetime (disambiguation). ... For other uses, see Universe (disambiguation). ... For other uses, see Galaxy (disambiguation). ... For other uses, see Doctor Who (disambiguation). ... Fathers Day is an episode in the British science fiction television series Doctor Who, which was first broadcast on May 14, 2005. ... In special relativity and general relativity, time and three-dimensional space are treated together as a single four-dimensional pseudo-Riemannian manifold called spacetime. ... This is a list of monsters and aliens from the television series Doctor Who. ... John Cramer is a Professor of Physics at the University of Washington in Seattle, United States. ... Einsteins Bridge is a novel written by John Cramer. ... A multiverse (or meta-universe) is the hypothetical set of multiple possible universes (including our universe) that together comprise all of physical reality. ... A multiverse (or meta-universe) is the hypothetical set of multiple possible universes (including our universe) that together comprise all of physical reality. ... The Superconducting Super Collider (SSC) was a ring particle accelerator which was planned to be built in the area around Waxahachie, TX. It was planned to have a ring circumference of 87 km (54 miles) and an energy of 20 TeV per beam, potentially enough energy to create a Higgs...

Observation resolution

Some speculations suggest that, under no circumstances whatsoever you would be able to "kill your grandfather". The only result of the time travel would be your knowledge that you've caused some event in the past. For example, if a protagonist kills his grandfather, it would turn out that the victim is not his grandfather at all.

Other examples

The Grandfather Paradox, or similar, is also used in the following:

• A well known, typical example of the paradox is the first Back to the Future film: Marty McFly travels to 1955 and accidentally prevents his mother's romantic attraction to his father. While trying to find out a way to return to his own year, he observes that his siblings begin to fade out from a picture he was carrying with him since he averted their own birth. Towards the end of the film, he starts to fade from reality as well, until he manages to make his parents fall in love "again".
• In the 2007 Doctor Who series episode Last of the Time Lords The Toclafane (humans from the year 100 trillion who have cannibalised themselves into spheres) are brought back in time to 2008 by the Master. They can kill their ancestors because the Master has converted the TARDIS into a Paradox Machine, that holds the paradox in place. The paradox is broken when the machine is destroyed, trapping the Toclafane 100 trillion years in the future.
• Robert A. Heinlein's short story "—All You Zombies—" in which a time travel agent becomes his own father - and his own mother, as well as bringing the two of them together. This does not invoke the normal paradox dynamics ("if X happened, then Y cannot have happened; and if Y did not happen then X must have happened"). Instead something is created from nothing (a person with no ancestors but himself) but the final outcome is self consistent.
• Spider Robinson's short story Father Paradox
• Connie Willis's novel To Say Nothing of the Dog
• The Terminator series of movies
• The Butterfly Effect films
• Star Trek episode The City On The Edge Of Forever - McCoy, with an accidental overdose on medicine, went through a time portal and saved the life of a woman, altering history in such a way that the Federation was never created. Kirk and Spock must find the point at which McCoy altered time and reverse the change, by allowing the woman to die. In the Star Trek: Deep Space Nine episode "Trials and Tribble-ations", which used footage from the original series to create a time travel episode with Kirk and crew in it, Julian Bashir flirts with a girl he later realizes may be his ancestor and, in a spoof of the paradox, begins to worry that he may be faced with the choice of becoming his own progeny or ceasing to exist.
• A similar paradox is mentioned in The Simpson's episode: Smart and Smarter. Homer thinks that each time he has a kid they are smarter then the last, so if he had one more, that child could build a time machine to take him back in time so he doesn't have any children. He never tests his 'Theory'.
• The online machinima comedy series Red vs. Blue - The character Church travels back in time to prevent his own death, and to avert the events and disasters that put the characters into their current situation. He ends up causing all of the problems and situations of the first 48 episodes — including his own death — entirely by accident. The first example of this was to save his late superior Butch Flowers from a suspected heart attack by injecting him with a chemical to prevent it from happening. The injection causes him to die from an allergic reaction. Church hears the present Tucker & Church coming in and runs away. Upon seeing him, present Church suspects a heart attack.
• The Red Dwarf episode, "Tikka To Ride", episode 7.1, in which the future version of the crew destroy the present crew; therefore, the future crew no longer exist and therefore are unable to go back in time and kill themselves, hence they survive. Also in this episode, the crew accidentally kill Lee Harvey Oswald, preventing the JFK assassination, and causing changes to the timeline which lead to Russia winning the space race. Ultimately, they convince a slightly older and politically destroyed JFK to go back in time to assassinate himself from the Grassy Knoll, to ensure the timeline and his own legacy are restored.
• The Red Dwarf episode, "Ouroboros", episode 7.3, in which Lister discovers he is his own father and travels back in time to place his son, aka himself, under the pool table where his adoptive parents first found him.
• In Metal Gear Solid 3: Snake Eater (a prequel to the entire Metal Gear series), after Revolver Ocelot and the Ocelot Unit are knocked out, it is possible to shoot Ocelot. This, however, results in an instant game over screen, with the words "TIME PARADOX" replacing "GAME OVER". This occurs due to the fact that Ocelot is a vital factor in the series, and that none of them would have happened if Ocelot died. Also, if the main character, Naked Snake, dies in any way, the "TIME PARADOX" message also replaces the "SNAKE IS DEAD" screen. This is due to the fact that Naked Snake is actually Big Boss, the father of Solid Snake, who is the most critical character in the series.
• The Invader Zim episode, Bad, Bad Rubber Piggy, in which Zim tries to use a space-time object replacement device to send a Hunter-Destroyer robot to destroy Dib before he becomes Zim's enemy. GIR warns Zim that if Dib doesn't become Zim's enemy, Zim won't send the robot, and then Dib won't be destroyed and will become Zim's enemy, and then Zim will send the robot, Dib will be destroyed and won't become Zim's enemy (Gir keeps telling it until his head explodes). The paradox never occurs because Zim had failed at destroying Dib.
• K. A. Applegate's Megamorphs #3: Elfangor's Secret (of the Animorphs series) featured a storyline wherein the Animorphs are shown an alternate universe where slavery and disease are rampant, which will become reality unless they can follow a certain alien foe, Visser Four, through time in order to stop him. Visser Four travels to world events such as Washington's crossing of the Delaware and D-Day attempting and succeeding in altering the timeline with the Time Matrix to make it favorable for the invading Yeerks. The successful Yeerk abandons his host, and the Animorphs take that opportunity to ask the dying human when his parents met with the intention of preventing his birth to save the timeline, which they do.
• In Lost Highway the main character Fred seems to be stuck in endless "grandfather paradox" in which he kills his wife, her "friends" and lover.
• In The Legend of Zelda: Oracle of Ages, when Link gets possessed Impa to the area where Nayru is singing, Veran emerges from Impa and possesses Nayru. After Ralph puts away his sword and steps away from possessed Nayru, possessed Nayru goes back in time and turns almost everyone into stones and possesses Queen Ambi to make the Black Tower, thus causing a paradox to change the future. Link goes back in time to fix the paradox.
• In The Legend of Zelda: Ocarina of Time, Link learns the Song of Storms from the man in the windmill in Kakariko Village. Later, he must teach this song to the Windmill man in the past, for a certain event to happen, an event that occurred because of Link's meddling, but what the player hasn't been able to do yet, because the player didn't know the Song of Storms. The event is triggered by teaching the Windmill Guy the Song of Storms. The song is in fact spawned by a time paradox. This could alternately be explained with the sequel The Legend of Zelda: Majora's Mask, in which the song is learned again through another source.
• Prince of Persia - The Sands of Time Trilogy: In the first game (The Sands of Time), the Prince releases the Sands of Time, only to reverse time to a point before he released them. The second game (Warrior Within) reveals that whoever releases the Sands must die, and since the Prince is not dead, he is pursued by an invincible monster known as the Dahaka. To rid himself of the monster, the Prince travels back in time to prevent the creation of the sands, only to create them himself by accident. Using the Mask of the Wraith, which turns the Prince into the Sandwraith, the Prince is able to travel back in time again while simultaneously being outside of the timeline, thus existing as a separate person from his original incarnation. This culminates in the Prince killing his other self by means of the Dahaka; the first time this happens, it is the Sandwraith that perishes. Since he is separated from the timeline by the mask, he is saved from any potential paradoxes and retains his memories of the past. He goes on to prevent the creation of the sands, killing the Dahaka in the process. In the last game of the trilogy (The Two Thrones), the Prince finds that the evil Vizier he killed in the first game is still alive, having negated that timeline by not allowing the sands to come to be. The Vizier, still having his reckless ambitions of immortality, creates the sands once more, only to be killed by the Prince, fulfilling the "death sentence" the Prince avoided.
• In Chuck Palahniuk's novel, Rant (novel), the grandfather paradox is presented as being misinformation for people to not doing what said paradox entails. It suggests that there are two forms of time, real time and liminal time, the former being one essentially outside of time that has no beginning and consequently no end like that of a god. The novel describes that the murder of one's grandfather destroys your beginning, thus destroying your end, entering you into liminal time and becoming immortal.
• In The Day before Tomorrow by Gerard Klein. 'Temporal commandos', who are supposed to correct other civilization's future, kill themselves coming from the future in order to stop 'Federation' from destroying a better, more humane world. In this case less probable version of commandos, which defends the planet and its civilization, takes over the more probable one, which executes the will of 'Federation'.
• In the 2000 video game Dino Crisis 2, it is mentioned that a Third Energy accident in 2055 would stop the human race from ever existing. And so Creatures existing from 300-64 MYA are sent to the year 3,000,000 to stop the catastrophy happening. Due to Timeline being repaired, Humans still exist. but Third Energy would exist to cause the accident in 2055 anyway, creating a loop.
• In the Fairly Odd Parents episode Father Time, Timmy prevents his dad from winning a race, and thus, preventing him from winning the love of Timmy's mother. As a result, Timmy is never born, and when he travels back to the present to see what is going on, neither his "dad" (who is now dictator of the world), nor his friends Chester and A.J. recognize him, and furthermore, his GodParents Cosmo and Wanda are not his (although Cosmo and Wandas' past selves seem to be able to travel with him), because he has no ties to that time period.

This article is about the first film in the Back to the Future trilogy. ... This article does not cite any references or sources. ... Year 1955 (MCMLV) was a common year starting on Saturday (link displays the 1955 Gregorian calendar). ... For other uses, see Doctor Who (disambiguation). ... Last of the Time Lords is an episode of the British science fiction television series Doctor Who. ... This is a list of monsters and aliens from the television series Doctor Who. ... This article is about the character. ... The current TARDIS prop as seen at the BBC Wales reception in 2005. ... This is a list of items from the BBC television series Doctor Who. ... Robert Anson Heinlein (July 7, 1907 – May 8, 1988) was one of the most popular, influential, and controversial authors of hard science fiction. ... —All You Zombies— (the title includes the quotation marks) is a science fiction short story by Robert A. Heinlein that was first published in Fantasy and Science Fiction magazine in 1959. ... Spider Robinson (born November 24, 1948 in New York City) is a Canadian science fiction writer. ... Connie Willis at Clarion West, 1998 Constance Elaine Trimmer Willis (born 31 December 1945) is an American science fiction writer. ... To Say Nothing of the Dog is a 1997 comedic science fiction novel by Connie Willis. ... The Terminator (also known as Terminator in some early trailers and posters) is a 1984 science fiction/action film featuring former bodybuilder Arnold Schwarzenegger in what would become his best-known role, and also starred Linda Hamilton and Michael Biehn. ... This article or section contains a plot summary that is overly long or excessively detailed compared to the rest of the article. ... The current Star Trek franchise logo Star Trek is an American science fiction entertainment series and media franchise. ... The City on the Edge of Forever is a first season episode of Star Trek: The Original Series. ... Space station Star Trek: Deep Space Nine (ST:DS9 or STDS9 or DS9 for short) is a science fiction television series produced by Paramount and set in the Star Trek universe. ... Trials and Tribble-ations is a fifth season episode of Star Trek: Deep Space Nine that was written as a tribute to the original series of Star Trek. ... Julian Subatoi Bashir, M.D., (played by Alexander Siddig) is a character in the fictional Star Trek universe. ... Homer, a safety inspector at the Springfield Nuclear Power Plant, is a generally well-meaning buffoon whose short attention span often draws him into outrageous schemes and adventures. ... For the The Suite Life of Zack & Cody episode, see Smart & Smarterer Smart and Smarter is the thirteenth episode of The Simpsons fifteenth season. ... A scene from the popular machinima series Red vs. ... For divisions in United States politics, see Red states and blue states. ... For the type of star, see Red dwarf. ... For the type of star, see Red dwarf. ... Metal Gear Solid 3: Snake Eater (commonly abbreviated MGS3) is a stealth-based game directed by Hideo Kojima, developed and published by Konami for the PlayStation 2. ... For the original video game titled Metal Gear, see Metal Gear. ... Revolver Ocelot ) is an antagonist in the Metal Gear video game series created by game designer Hideo Kojima. ... It has been suggested that this article or section be merged into Big Boss. ... This article or section contains a plot summary that is overly long. ... Solid Snake ) is the protagonist of the Metal Gear video game series. ... Invader Zim is an American animated television series created by comic book writer/artist Jhonen Vasquez and aired on Nickelodeon. ... Bad, Bad Rubber Piggy is an episode of Invader Zim originally produced as episode 7B, but aired as episode 8B on August 24, 2001. ... Zim is the title character from the Nickelodeon animated series, Invader Zim. ... The Hunter-Destroyer Machine The Hunter-Destroyer Machine is a fictional military weapon in the Television Series Invader Zim. ... Dib is a fictional character from the Nickelodeon animated television series, Invader ZIM. He is Zims rival and is highly unpopular at school (where he shares a class with Zim) and at home for his broken record obsession with aliens, Bigfoot, the Loch Ness Monster, and other paranormal phenomena. ... GIR is one of the main characters from the animated television series Invader ZIM. He is Zims robotic slave, constructed from scrap parts and given to Zim by the Almighty Tallest instead of a regular SIR (Standard-issue Information Retrieval) unit. ... Look up paradox in Wiktionary, the free dictionary. ... Katherine Alice Applegate is the credited author of the Animorphs, Remnants, and Everworld book series, although many of these books are ghostwritten by other authors. ... Megamorphs #3: Elfangors Secret is the third book in the Megamorphs series, a spinoff of the Animorphs series. ... This page is about the book series. ... Land on Normandy In military parlance, D-Day is a term often used to denote the day on which a combat attack or operation is to be initiated. ... The Time Matrix is a fictional device from the book series, the Animorphs, by K.A. Applegate. ... A Yeerk is a fictional extraterrestrial species from the book and television series Animorphs. ... Lost Highway is a 1997 psychological thriller directed by David Lynch. ... This article or section should include material from Like like ring, Moblin ring Oracle of Ages title screen (GBC original) The Legend of Zelda: Oracle of Ages (also known as OoA) is a video game published by Nintendo and developed by Nintendo in conjunction with Capcom. ... Impa, Sage of Shadow and last of the Sheikah (Ocarina of Time) Impa ) is a fictional character in the Legend of Zelda series of video games. ... This article does not cite any references or sources. ... Look up paradox in Wiktionary, the free dictionary. ... The Legend of Zelda: Ocarina of Time was a video game released in 1998, and the first Zelda game for the Nintendo 64. ... Kakariko Village is a fictional village in the Legend of Zelda series. ... It has been suggested that Mask of the Wraith be merged into this article or section. ... It has been suggested that Mask of the Wraith be merged into this article or section. ... It has been suggested that Mask of the Wraith be merged into this article or section. ... It has been suggested that Mask of the Wraith be merged into this article or section. ... Charles Michael Chuck Palahniuk (IPA: )[1] (born February 21, 1962) is an American satirical novelist and freelance journalist of Ukrainian ancestry born in Pasco, Washington. ... Rant: An Oral Biography of Buster Casey is a novel by Chuck Palahniuk released on May 1, 2007. ... Gérard Klein is a French science-fiction writer with sociological training. ... This article or section contains a plot summary that is too long or excessively detailed. ... It has been suggested that this article or section be merged with Dino Crisis. ... The Fairly OddParents is one of the most popular cartoons on Nickelodeon The Fairly OddParents is an animated series created by Butch Hartman and was first aired in March 30, 2001. ...

Other considerations

Consideration of the grandfather paradox has led some to the idea that time travel is by its very nature paradoxical and therefore logically impossible, on the same order as round squares. For example, the philosopher Bradley Dowden made this sort of argument in the textbook Logical Reasoning, where he wrote: Squaring the circle: the areas of this square and this circle are equal. ...

Nobody has ever built a time machine that could take a person back to an earlier time. Nobody should be seriously trying to build one, either, because a good argument exists for why the machine can never be built. The argument goes like this. Suppose you did have a time machine right now, and you could step into it and travel back to some earlier time. Your actions in that time might then prevent your grandparents from ever having met one another. This would make you not born, and thus not step into the time machine. So, the claim that there could be a time machine is self-contradictory.

However, most philosophers and scientists agree that time travel into the past need not be logically impossible as long as there is no possibility of changing the past, as suggested, for example, by the Novikov self-consistency principle. Bradley Dowden himself revised the view above after being convinced of this in an exchange with the philosopher Norman Swartz.^[5] This article or section does not cite its references or sources. ...

Consideration of the possibility of backwards time travel in a hypothetical universe described by a Gödel metric led famed logician Kurt Gödel to assert that time might itself be a sort of illusion.^[6][7] He seems to have been suggesting something along the lines of the block time view in which time does not really "flow" but is just another dimension like space, with all events at all times being fixed within this 4-dimensional "block". The Gödel solution is an exact solution of the Einstein field equation in which the stress-energy tensor contains two terms, the first representing the matter density of a homogeneous distribution of swirling dust particles, and the second associated with a nonzero cosmological constant (see lambdavacuum solution). ... Kurt Gödel (IPA: ) (April 28, 1906 Brünn, Austria-Hungary (now Brno, Czech Republic) – January 14, 1978 Princeton, New Jersey) was an Austrian American mathematician and philosopher. ... Block time is one way of approaching the problem of the nature of time. ...

In the Stephen King novel The Langoliers, small cannonball-like creatures eat all matter left in the past, making travel, other than a few hours, impossible, since the past no longer exists. Stephen Edwin King (born September 21, 1947) is an American author of over 200 stories including over 50 bestselling horror novels. ... The Langoliers is one of four novellas published in the Stephen King book Four Past Midnight in 1990. ...

See also

• Causality
• Chronology protection conjecture
• Time loop
• Predestination paradox
• Ontological paradox
• Time travel in fiction
• I'm My Own Grandpa (song)
• The chicken or the egg

It has been suggested that this article be split into multiple articles accessible from a disambiguation page. ... The chronology protection conjecture is a conjecture by the physicist Professor Stephen Hawking that the laws of physics are such as to prevent time travel (closed timelike curves) on all but sub-microscopic scales. ... A time loop is a fictional situation in which time runs normally for a set period (usually a day or a few hours) but then skips back like a broken record. ... A predestination paradox, also called either a causal loop, or a causality loop and (less frequently) either a closed loop or closed time loop, is a paradox of time travel that is often used as a convention in science fiction. ... An ontological paradox is a paradox of time travel that questions the existence and creation of information and objects that travel in time. ... Poster for the 1960 adaptation of HG Wellss The Time Machine. ... Im My Own Grandpa (sometimes rendered as Im My Own Grandpaw) is a novelty song written by Dwight Latham and Moe Jaffe, performed by Lonzo and Oscar in 1948, about a man who becomes his own step-grandfather-in-law due to a series of bizarre but legal... The chicken or the egg is a reference to the causality dilemma which arises from the expression which came first, the chicken or the egg? Since the chicken emerges from an egg, and the egg is laid by a chicken, it is ambiguous which originally gave rise to the other. ...

References