History Main / TimeDilation

* ''The Dark Wheel'' TieInNovel that came with ''VideoGame/{{Elite}}'' says that accident ls in hyperspace can strand a ship millions of years in the past but it's treated more like an urban legend.

* Time dilation works both ways. To the guy standing on Earth, you're whizzing past him at 90% of the speed of light, so to him your clock seems to only be running at half normal speed. But to you, you're standing still and ''the Earth'' is whizzing past ''you'' at 90% of the speed of light, so to you the clocks on Earth seem to be running at half normal speed. To you, the people back ''on Earth'' are the ones aging more slowly. This seeming paradox is only resolved upon carefully examining the path taken by both observers -- or, in this example, by you and your friend back on Earth -- and realizing that you had to decelerate and turn back, tracing a path in 4-dimensional spacetime that is not a straight line. According the [[AlienGeometries odd notion of distance]] defined in 4-d spacetime, a straight line actually has the longest possible distance, corresponding to the longest possible time. Then you, the traveler, will experience a smaller subjective amount of time than your buddy on Earth.[[labelnote:*]]You may now let YourHeadAsplode.[[/labelnote]]

-->-- ''Series/StargateSG1'', "A Matter of Time"

* One episode of the ''LightNovel/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.

* ''Series/{{Battlestar Galactica|2003}}'': [[spoiler: The "Final Five"]] went on a sublight journey that took 2000 years from an outside perspective, but a lot less to them.

** Our page quote comes from the aptly titled ''Series/StargateSG1'' episode "A Matter of Time". Opening an outgoing wormhole to a planet near a black hole caused the gate to lock up due to the differences in the speed of time on either side of the wormhole, time to slow down immensely inside the mountain, and the black hole's gravity to start sucking everything in the vicinity into the stargate. [[spoiler:They solved it by detonating a bomb near the gate, causing an overload that made the wormhole jump to another receiving gate, whereupon they disengaged normally.]] Gen. Hammond sums it up quite well:

** Prior to "Unnatural Selection", the Asgard used a time dilation device to try and [[SealedEvilInACan lock away the Replicators]] in a "bubble" where [[YearOutsideHourInside "one year to the Replicators would be about ten thousand years to the rest of us."]] The replicators managed to reverse the device's function, [[YearInsideHourOutside allowing them to eperience hundreds of years while less than one years went by outside]]. SG-1 had to go in and correct the problem.
** Briefly mentioned as a problem in "Memento" if the ''Prometheus'', stranded in deep space hundreds of light-years from Earth after hyperdrive failure, tried to hoof it home. Of course, relativity was kinda secondary to the fact that they didn't have enough supplies for that anyway.
** In the series finale "Unending", Carter uses the time dilation device from "Unnatural Selection" to trigger YearInsideHourOutside and give her enough time to develop a plan to save the ''Odyssey'' from the three Ori warships pursuing it.

* In ''WesternAnimation/TwelveForever'' the ep "Spring Break Forever", Todd and Esther visit Endless Island without Reggie (Due to RupturedAppendix) for what felt like 20 minutes, but in reality, was actually 5 days (This is partially due to the fact that Endless Island has EndlessDaytime).

%%Belongs in YearOutsideHourInside or NarniaTime * This trope is played straight in Adam R. Brown's ''Literature/AstralDawn'' series. Time passes much more quickly on the astral plane than it does on the physical plane. Caspian learns an entire month can pass by in Celestial City while only 8 hours passes by on the physical plane.

[[folder:Radio]]
* Creator/TheBBC {{Radio}} series ''Radio/{{Earthsearch}}'' uses time dilation as a major plot point. The children of a starship's second-generation crew, the sole survivors of a disaster that killed the crew and erased a huge amount of scientific data (including the concept of time dilation itself), return the ship to their home solar system 115 years after it set out, only to find that a million years have passed outside. Oh, and the Earth is missing.
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* ''Unidentified Flying Oddball'' is about an astronaut whonends up in Arthurian times after travelling faster than light.

%%Its a sublight example* In ''Film/FlightOfTheNavigator'', this is theorized as the reason David didn't age beyond the age of twelve in spite of being missing for eight years: he was aboard a spaceship travelling at FTL speeds, so only a few hours would've passed for him.

In general relativity, an additional time dilation effect is caused by gravity. Time passes more slowly nearer to the bottom of a gravitational potential well (e.g. on the surface of a planet) than higher up in one (e.g. in an airplane). This dilation, in addition to the dilation due to differences in velocity, needs to be compensated for by clocks on satellites.

* DiscussedTrope in ''Film/CloseEncountersOfTheThirdKind'' when the aliens return the abductees, some of whom have been gone for decades, but don't look any older.

* 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.

* ''Wiki/SCPFoundation'':

* ''Series/UltramanMebius'':[[spoiler:This is the reason why Captain Sakomizu is OlderThanTheyLook. He was originally a space patrol office in Science Patrol, but the effects of travelling at lightspeed have caused him to age more slowly.]]

* The Slingshot Maneuver in ''Franchise/StarTrek'' involves doing a GravitationalSlingshot around a star at warp speed and arriving at a chosen time period.

* ''Wiki/SCPFoundation'', [[http://www.scp-wiki.net/scp-1272 SCP-1272 ("Slow-Motion Catastrophe")]]. SCP-1272 is a nongravitational singularity (similar to that of a black hole/hypermass) that tremendously slows down the passage of time inside its area.

* Gravitational time dilation is a ''miniscule'' effect - so miniscule that it would only be perceivable by a human exposed to incomprehensibly strong gravity (at which case, they would obviously be dead many times over.) As Wiki/TheOtherWiki [[https://en.wikipedia.org/wiki/Gravitational_time_dilation#Outside_a_non-rotating_sphere helpfully points out,]] even on the surface of the Sun where gravity is 28 times stronger than Earth, a clock would only accumulate a completely negligible 66 fewer seconds over the course of an entire year.

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]] Wiki/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.

* The Aratrum takes millennia to get from Tau Ceri back to Earth due to relativistic effects in ''Anime/GodzillaPlanetOfTheMonsters''.

** Zurg has worked out how to use it to go back in time but could only travel so far back and wanted Buzz's help to perfect it.

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* Is used in an interesting way in the 2002 sci-fi action adventure family film ''Film/{{Clockstoppers}}'', where since a watch that allows the users or those touching them to move faster in time than everyone else, time appears to slow down for those moving faster.

[[folder:Films - Animation]]

* ''Film/TimeTrap'' involves a cave where a second inside is equal to a year outside.

[[folder:Films - Animation]]
* This is a recurring element in ''WesternAnimation/{{Lightyear}}''. Attempts to reach hyperspeed involve approaching increasing fractions of the speed of light (approaching hyperspeed is expressed as decimals of ''c''), so time dilation kicks in as one uses it. During the first act of the movie, each attempt Buzz makes to reach hyperspeed takes four subjective minutes for him, but just over four ''years'' on the planet below. [[spoiler:When he finally reaches hyperspeed and returns to the planet, he learns that ''twenty-two'' years have passed.]]
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** In ''ComicBook/AllStarSuperman'', Superman shoots the now superpowered ComicBook/LexLuthor with a gravity gun that makes him dense enough to warp time and make his powers run out quicker.

* This trope is played straight in Adam R. Brown's ''Literature/AstralDawn'' series. Time passes much more quickly on the astral plane than it does on the physical plane. Caspian learns an entire month can pass by in Celestial City while only 8 hours passes by on the physical plane.

* In Creator/PoulAnderson's "Literature/TimeLag", the dilation effect is enough that Elva uses it to persuade Bors to bring her during the second attack -- she will be old when he returns -- and make her contemplate how she is a FishOutOfTemporalWater at the ending.

* The sequels to ''Literature/EndersGame'' take place 3,000 years after it, but involve many of the same characters as they've spent most of their life on spaceships traveling at relativistic speeds. However, he got the bit about this trope working both ways wrong. UsefulNotes/{{Relativity}} and [[spoiler:[[SubspaceAnsible Subspace Ansibles]]]] don't mix well.
** The IF in ''Ender's Game'' relied on this trope specifically. [[spoiler:Mazer Rackham, the last great military leader Earth had in the wake of the Second Invasion, was needed to train the genius who would lead Earth's counterattack, so they put him in a spaceship, got him up to a relativistic speed for 25 years, and then he turned around and came home. Only about eight years passed for him, 50 for everyone else. ]]

Compare YearOutsideHourInside and LudicrousSpeed. RipVanWinkle is a related trope in more fantastical works. YearInsideHourOutside is the inverse, and tends to show up in [[MohsScaleOfSciFiHardness softer]] works or those using magic rather than physics.