History Main / TimeDilation

* GPS has a small correction for time dilation between the surface of the earth and up in space. A satellite in space experiences 0.6 nanoseconds more for every second on Earth. This is actually how GPS works - by knowing what time each satellite the receiver is getting data from thinks it is, it can use the time dilation to calculate the distance from the receiver to each satellite, which can be used to triangulate the receiver's position.

* The ''[[AllThereInTheManual Colonial Marines Technical Manual]]'' for the ''{{Franchise/Alien}}'' universe indicates that starships undergo "time expansion" during FTLTravel – [[SleeperStarship hence the need for hibernation pods]].

* In ''Webcomic/{{Homestuck}}'', at one point two characters travel between two [[LeaningOnTheFourthWall windows in the fourth wall]], taking what is explicitly stated as three nanoseconds (the time it takes light to travel one yard) to do so from an outside perspective. It is stated to take ''three years'' from their own perspective, which is actually not how time dilation works.

Time dilation is a scientific concept related to UsefulNotes/{{relativity}} which states, basically, that for an observer aboard a spaceship travelling at any speed at all (though only noticeable at appreciable fractions of the speed of light) with respect to Earth (or any inertial reference frame of your choice), time passes more slowly than it would for an observer on Earth. When near-lightspeed travel becomes involved, the effects become quite drastic: A person might go on a space journey that seems to him to last one year and, on returning, find that 10 years have passed on Earth. It is, in effect, TimeTravel, most effectively to the future, but since this can also make time be experienced faster by someone faster than everyone else, it can provide a way to go to a relative past.

* ''Series/TheTwilightZone1985'': In "Quarantine", although 304 years have passed on Earth, Joshua estimates that it has only been five or ten years for the 1,000 people aboard the American spacecraft launched during the [[WorldWarIII nuclear war]] in 2043.

* In ''Webcomic/QuentynQuinnSpaceRanger'', it's stated that Rangers are given extremely long vacations to catch back up with current events and family, as well as debreif their superiors on a year-long mission (for the ranger) that took 2-10 (for the brass). The title character misses three years without realizing it while on a long mission through largely uncharted space.

* In ''Webcomic/QuentynQuinnSpaceRanger'', the title character misses three years without realizing it while on a long mission through largely uncharted space.

* It's stated that Rangers are given extremely long vacations to catch back up with current events and family, as well as debreif their superiors on a year-long mission (for the ranger) that took 2-10 (for the brass).

** It's stated that Rangers are given extremely long vacations to catch back up with current events and family, as well as debreif their superiors on a year-long mission (for the ranger) that took 2-10 (for the brass).

-->It's stated that Rangers are given extremely long vacations to catch back up with current events and family, as well as debreif their superiors on a year-long mission (for the ranger) that took 2-10 (for the brass).

It's stated that Rangers are given extremely long vacations to catch back up with current events and family, as well as debreif their superiors on a year-long mission (for the ranger) that took 2-10 (for the brass).

'''Delivery guy:''' Oh no. The Mark III came out ''last'' year. The Mark IV just hit the shelves last month!\\

* Used to Justify a TimeSkip in ''WebComic/LancersTheKnightsOfFenris.'' A squadron of fighter pilots attempts a HyperspeedEscape through a black hole without adequate power for their "Relativity Compensators," and it looks like they abandoned their post for two entire years. During which the war went badly.

'''Delivery guy:''' Oh no. The Mark III came out ''last'' year. The Mark IV just hit the shelves last month!

* ''WebOriginal/OrionsArm'' has relativistic space travel at speeds in excess of .9c, but it's usually requires a Transapient tech ReactionlessDrive. But it's not much of an issue because people can have essentially unlimited lifespans (average Nearbaseline lifespan is about 3000 years). Also the setting's PortalNetwork requires the two mouths of the wormhole to be towed into position at sub-relativistic speeds (~.77c).

This is sometimes extrapolated by science fiction authors to apply to FTLTravel as well, though this does not make much sense physically. Many writers extend this so traveling faster than light means aging backwards, but that isn't how the math says it works. The time scale factor for speeds faster than ''c'' is imaginary, not negative. If an object is travelling faster-than-light, though, that means there is always some slower-than-light frame reference that sees the object travelling backwards in time -- or possibly moving in the opposite direction, with events on the object occurring backwards.[[note]]This, contrary to popular belief, would not imply TimeTravel: an observer still exists that sees events happening in the "proper" order. Trouble is, both types of observers -- those that see our superluminal buddy going forwards and those that see him going backwards -- can simultaneously exist. And they do not agree on the relative order of events. Woe and behold, causality is thrown out the window in a much harsher way than any Grandfather Paradox ever dared attempt.[[/note]] Website/TheOtherWiki has [[http://en.wikipedia.org/wiki/Tachyon an article]] on tachyons, theoretical objects that move faster than the speed of light, and explains how this works.

* This is ''[[Literature/GiantsSeries The Gentle Giants of Ganymede]]''[='s=] premise, when humanity runs into a shipload of AncientAstronauts who had been forced to circle around the solar system for the last several million years due to an emergency hyperspace jump gone wrong, until their engines finally ran out of fuel.
* In the Creator/StrugatskyBrothers' Literature/NoonUniverse, FTL travel is impossible. All ships travel at near-light speeds and return centuries later (objective time). This all changes when the crew of a starship decides to try something new. Normally, constant or slowly-increasing acceleration is maintained for most of the voyage. The captain of the ship decides to try high acceleration for most of the trip (about 10g) in order to ''reverse the effects'' of time dilation, as this would fall outside of the Special Theory of Relativity. According to the captain, General Theory of Relativity allows for this. This works, and the ship returns to Earth six months later; however, several years pass for the crew.

* Discussed in ''Film/BattleForThePlanetOfTheApes'' where characters wonder if human astronauts from before the apocalypse could travel through time in faster than light ships. A scenario is presented where a musician could do a broadcast in London, [=FTL=] travel to New York and listen to it live and then go back in time to cancel the performance if he didn't like it.

* In ''Literature/CaptainFrenchOrTheQuestForParadise'' by Creator/MikhailAkhmanov and Christopher Nicholas Gilmore, the only way to travel between the stars is with the use of a relativistic drive system. It does not require any acceleration (i.e., works like the lightspeed in ''Franchise/StarWars'', only with STL) and takes only seconds for the crew. However, decades, if not centuries, pass in the outside universe. It still takes months of travel to and from the edges of star systems in order to minimize the risk of CriticalExistenceFailure. For this reason, space travel is only done by colonists and space traders and no interstellar government is possible.
** The titular protagonist mentions once intercepting a message sent out from one world about a scientist claiming to have proven UsefulNotes/FermatsLastTheorem. While French admits that this is probably a big deal for a mathematician, the message has no commercial value to him as a space trader. In fact, in all his millennia of travel, he has only intercepted about two dozen interstellar messages, as sending them requires putting up a powerful relay satellite in orbit as well as maintaining it for little or no return. As such, the various human worlds are isolated with an occasional space trader passing through every half-a-century or so. Of course, given that aging has been eliminated in this 'verse, it's entirely possible for a planetbound person to meet the same space trader who comes back 200 years later.

* In Creator/FrederikPohl's ''Literature/{{Gateway}}'', a major shocker in the ending is that [[spoiler:the protagonist's friends, whom he betrayed, are still at the edge of a black hole, still just having realized that he's betrayed them, still just having realized that they're going to die there -- and they'll be in that state until long, long after he's dead.]]
* This is the central premise of the novel ''Literature/TheWorldAtTheEndOfTime'', also by Creator/FrederikPohl. Everything starts when Wan-To, a [[EnergyBeings plasma-based lifeform]] that's at war with some other such entities, sends out some [[MesACrowd copies of itself]] to decoy its enemies by [[SufficientlyAdvancedAlien moving some stars around]]. [[spoiler:One such copy winds up in the star of a human colony. Since this particular copy had no instructions on when to stop, it accelerates the stars and everything in orbit around them to ''really relativistic'' speeds. When it finally decides to decelerate, after about 4,000 years or so, ''ten duodecillion''[[note]]That's a one followed by forty zeroes[[/note]] years have passed in the outside universe, more than enough for the rest of the stars to all die]].

* In ''Film/TheFlash2023'', Barry learns he can travel anywhere in time by running faster than the speed of light.

* Creator/UrsulaKLeGuin's Hainish Cycle:
** This effect is present in ''Literature/TheLeftHandOfDarkness''; the [[TheFederation Ekumenical]] diplomats consider it a good thing, since if their mission on a particular planet fails, they can hop over to the nearest planet, then turn around and come right back and have a whole new generation of leaders with which to try again.
** In the prologue to ''Rocannon's World'', a young woman named Semley left her low-tech native planet to reclaim a family heirloom that had wound up being traded off-world. By the time she returns from a journey that was very short for her, her daughter is a grown woman. In the main story, Rocannon, who returned the necklace, meets Semley's granddaughter but has aged very little due to traveling.

* Creator/UrsulaKLeGuin's "[[Literature/SemleysNecklace The Dowry Of Angyar]]": This story (later incorporated into the novel ''[[Literature/RocannonsWorld Rocannon's World]]'') features Semley going on a quest to recover the lost heirloom of the title, and meeting a group of dwarf-like creatures who promise to help her get it back. What she doesn't realise is that they've taken it to another planet, eight light-years away, and thanks to relativity, what seems like a short trip to her is actually 16 years.

* ''Fanfic/WanderingMoon'': A serious one between Wasteland time and Equestrian time. Sometimes a few days in the Wasteland equals a week or a year in Equestria or in more extreme cases, a single day in the Wastes can be equal to several hundred years of Equestrian time. It really just moves at the speed of plot.

* ''ComicBook/InvaderZimOni'': Issue 28 is built around an experimental Irken device called the Time Accelerator (or the "Time Thingy" as it's nicknamed). It generates a field which causes time to move faster the closer you get to it. And when it ends up exploding near the end of the issue, it causes Zim to age into an elderly state.

* ''Franchise/{{Superman}}'':
** During the Pre-[[ComicBook/CrisisOnInfiniteEarths Crisis]] era, Superman and ComicBook/{{Supergirl}} were able to travel through time by flying faster than light.

* According to her backstory from ''VideoGame/SuperMarioGalaxy'', Rosalina was whisked into outer space by several Lumas, which she then befriended, but even though she spent a few days traveling through space on the Lumas' spaceship, by the time she returned to Earth, [[spoiler:a hundred years have already gone by, and Rosalina's family is now long dead (it's implied that she returned at the same time when the Mario Bros., Peach, and Bowser are all still children).]]

* One episode of the ''Literature/DirtyPair'' TV anime had a space travel magnate try to separate his son from a lover he disapproved of by launching her on the prototype of a slower-than-light "Time Dilation Tour" ship he had handy. The plan was that she'd only return after the son had aged the fifty years of the trip. The Lovely Angels can't stop the launch, but free the son in time for him to follow his love on another of the ships. The father finally gets on the final ship because he can't live without his son.

* In Creator/FrederikPohl's ''Literature/{{Gateway}}'', a major shocker in the ending is that [[spoiler: the protagonist's friends, whom he betrayed, are still at the edge of a black hole, still just having realized that he's betrayed them, still just having realized that they're going to die there -- and they'll be in that state until long, long after he's dead.]]

* A non-relativistic example in ''Literature/TheAlloyOfLaw'' with Cadmium Allomancy, which creates a bubble about the size of a small room within which time passes more slowly. [[spoiler: Used to freeze TheDragon in place while a small army was summoned to capture him.]]

* According to her backstory from ''VideoGame/SuperMarioGalaxy'', Rosalina was whisked into outer space by several Lumas, which she then befriended, but even though she spent a few days traveling through space on the Lumas' spaceship, by the time she returned to Earth, [[spoiler: a hundred years have already gone by, and Rosalina's family is now long dead (it's implied that she returned at the same time when the Mario Bros., Peach, and Bowser are all still children).]]

* Comes up several times in ''VideoGame/GravityRush'' and ''VideoGame/GravityRush2''. The entire world is located along a massive World Pillar which extends infinitely up and down. At the bottom is a massive black hole, and localized black holes called gravity storms appear randomly. Going up or down the pillar can mess with people's personal times, so when main character Kat goes down the pillar, she thinks she is only gone for a week from her home town when she is actually gone for [[spoiler: one year]].