History Main / OntologicalInertia

*** Of course, all that's really important is that he believes she died. [[TakeAThirdOption He could go back in time, fake her death and bring her into the present with him]].

->''Anything in existence will continue to exist until a sufficient force acts against it.''

* In the ''{{Dragonlance}}'' Legends trilogy, the flow of time can't be altered.[[spoiler:..unless one of the Graygem races, like a kender, were to travel back in time. Cue Tasslehoff Burrfoot, the kender Hero of the Lance, who tags along with Caramon on his trip to Istar.]]

* In the first three ''{{Terminator}}'' movies, good terminator androids, bad terminator androids, and one human are sent back in time to either prevent the upcoming apocalypse or kill off the future leader of the human rebellion. As each successive movie shows, attempts to change the future by either side will inevitably fail as long as there exists a demand for more Terminator movies.

* Enforced in ''TabletopGame/{{Continuum}}''. Spanners have a saying: "the universe is". Time is stable, unchanging, and any attempts to change the known result in reality-rending paradoxes that must be repaired. [[spoiler:This is not a natural law of the universe, but rather one that is strenuously enforced by the [[TranshumanAliens Inheritors]], humanity's [[TheSingularity post-Singularity]] descendants that occupy all time from 2400 AD forward and do not take kindly to any change that might affect their own existence.]]

* Enforced in ''TabletopGame/{{Continuum}}''. Spanners have a saying: "the universe is". Time is stable, unchanging, and any attempts to change the known result in reality-rending paradoxes that must be repaired. [[spoiler:This is not a natural law of the universe, but rather one that is strenuously enforced by the [[PosthumanAliens Inheritors]], humanity's [[TheSingularity post-Singularity]] descendants that occupy all time from 2400 AD forward and do not take kindly to any change that might affect their own existence.]]

* In ''[[VideoGame/DragonAgeOrigins Dragon Age: Origins]]'', the Dalish Keeper Zathrian summoned a spirit and bound it to a wolf in order to inflict a werewolf curse on the human barbarians who murdered his son and raped his daughter. Centuries later, the Warden is tasked with killing the wolf — Witherfang — who has spread the curse to Zathrian's clan in a bid to force Zathrian to lift it. Killing Witherfang will not end the curse; it will only enable Zathrian to cure the Dalish elves who have been inflicted. Likewise, killing Zathrian will not end the curse, and those inflicted will remain as werewolves. Only persuading Zathrian to lift the curse himself will cure all those who have been turned into werewolves.

* In [[VideoGame/DragonAgeOrigins]], the Dalish Keeper Zathrian summoned a spirit and bound it to a wolf in order to inflict a werewolf curse on the human barbarians who murdered his son and raped his daughter. Centuries later, the Warden is tasked with killing the wolf — Witherfang — who has spread the curse to Zathrian's clan in a bid to force Zathrian to lift it. Killing Witherfang will not end the curse; it will only enable Zathrian to cure the Dalish elves who have been inflicted. Likewise, killing Zathrian will not end the curse, and those inflicted will remain as werewolves. Only persuading Zathrian to lift the curse himself will cure all those who have been turned into werewolves.

* Used in ''VisualNovel/HigurashiNoNakuKoroNi''.

* A defining trope of ''ShakuganNoShana''. When a person's existence is eaten by a Rinne, they are gone but replaced by a "Torch", who acts as a shock absorber; they look the same, and even have the original's memories. As their flame burns out over time, their presence and impact on the world lessens - they become apathetic and do little, people overlook them - until they disappear completely. When this happens, no one remembers them, and it is as though they never had existed, ever. [[FridgeHorror This happens all the time.]]
* A key point in ''VampirePrincessMiyu'' is that Miyu fights against and defeats monsters but - as a curse she obtained by refusing to become a monster herself - is always unable to reverse any of the evil they have done. For example, when she defeats a ghost who has been luring women travelling on underground trains [[spoiler: to an abandoned station where they are transformed into statues, she can seal the station, but [[DownerEnding can do nothing about the statues already created]] [[NightmareFuel who remain]] [[FateWorseThanDeath imprisoned, petrified and weeping forever]]. ]]

* FlashForward2009 had elements of this. It was possible to change your future but very, very hard. In one case a character kills himself to prevent a future where he causes the death of a woman. In the altered timeline the person who replaces him on the team ends up causing the death instead.
* In the Series/TwilightZone episode "Of Late I Think of Cliffordville," when the protagonist realizes that he is still 70 years old (but looks like 30) and no one believes his ideas of "inventions" that he know will be coming, he asks [[TheDevil Miss Devlin]] to return him to where he started. She says she can but that is will be a time set in motion by events as they are now ''and'' there is a fee. He sells the only thing he has of worth to a the guy who was sweeping the streets, and returns to his "present." Only thing is, now that guy, who has been the janitor in his building now owns the company, and ''he'' is the janitor!
** Also, in "Back There", Russell Johnson finds himself in Washington DC before Lincoln's assassination. He tells a cop, but can't stop the act when he is drugged by John Wilkes Booth. When Johnson's character returns to his present, the man who was butler at his club is now one of the wealthiest members. His great grandfather was the copy and afterwards became famous and rich because he tried to stop the assassination as well.
* A fundamental part of ''BeingErica'' has the title character being able to go back in time to try to fix her regrets about her life. However, inevitably she will discover 1) she is unable to prevent the regrettable action from occurring 2) she is able to prevent the event from occurring, but something else happens that causes the same effect on her in the future or 3) she figures out that her regret had another fundamental cause. Instead, the point of the exercise is to gain perspective on what's going on in her current-timeline life. The few times she does manage to change a major event, the effect is usually erased by the end of the episode.

* The ''{{Dragonlance}}'' Saga even uses the stone in a time-stream example. The world as created by the gods does not allow past events to be changed. Unfortunately, several races have come into existence that were not intended at the time of the world's birth. They more or less are fine in the present, but all the "you can't change anything" rules of time travel don't apply to [[SpannerInTheWorks kender, Dwarves, and Draconians]].

* In the first three ''{{Terminator}}'' movies, good terminator androids, bad terminator androids, and one human are sent back in time to either prevent the upcomming apocalypse or kill off the future leader of the human rebellion. As each successive movie shows, attempts to change the future by either side will inevitably fail as long as there exists a demand for more Terminator movies.

* Used in ''HigurashiNoNakuKoroNi''.

* {{Lost}} plays with this in Season 5. For example, when handling a nuke, Daniel assures them that it can't explode because the island still exists in the future they came from.
* TheLegendaryAdventuresOfHercules had an episode where they were worried about how their time travel might affect the present, but Hercules assured them that Time would correct itself, so nothing would change.

* Strangely used in ''CodeLyoko''. Although there's a ResetButton that the heroes can use to travel into the immediate past and undo most of the damage the BigBad causes, if anyone dies before they use it, they'll stay dead, even after the past is changed; their death still possesses ontological inertia in the new time-line. Presumably they'd just drop dead from no apparent cause, but since the heroes never allowed anyone to die in the course of their adventures, the viewer never really saw how it'd work.

* In CommandAndConquer: Red Alert, Einstein tries to erase Hitler from history to prevent World War II. He succeeds and an even worse war between Russia and the Allies takes the place of World War II.

*** This is thrown out the window in ''Red Alert 3'', where Soviet time travelers kill Einstein in the same manner before he invents ''his'' time machine. When they go back, they immediately see changes. One change? No nuclear weapons. Another change? Japan is now a superpower to rival the Soviets and the Allies. Interestingly, many of Einstein's inventions are still made, but by other people, including the Chronosphere.
* OntologicalInertia is such a strong force in the ''[[LegacyOfKain Legacy of Kain]]'' series that the titular vampire spends most of his immortal life looking for a way to [[SetRightWhatOnceWentWrong thwart it]] at a [[TakeAThirdOption key point]] in his past. It turns out the trick is to have time displaced versions of something interact, for instance the first example in the series involves him fighting an enemy when they're both using the same sword (and another character is completely immune to it because he carries a future version of his own soul around with him). This is the origin of Kain's memorable "[[HeadsTailsEdge edge of the coin]]" speech:

* In PoulAnderson's ''Literature/TimePatrol'' series of short stories/novellas, there is a principle of "temporal inertia" which acts like this. It is very difficult to make substantial changes to the time-line, since most likely subsequent events will coalesce in a way that maintains the overall historical status quo. However, the flip side of the principle is that once changes ''are'' made to the time-line, it is similarly very difficult to undo those changes and return the time-line to its original status.

* OntologicalInertia is such a strong force in the ''[[LegacyOfKain Legacy of Kain]]'' series that the titular vampire spends most of his immortal life looking for a way to [[SetRightWhatOnceWentWrong thwart it]] at a [[TakeAThirdOption key point]] in his past. This is the origin of Kain's memorable "[[HeadsTailsEdge edge of the coin]]" speech:

Simon Hawke's ''Literature/TimeWars'' has a similar Law of Historical Inertia, and any change you make will be like a stone dropped in the river of time: History will simply flow round it and, for the most part, end up exactly where it was before (so if you wanted to actually change it, you'd essentially need a ''really big'' "stone" to divert the river, the consequences of which could be disaster).

*** The Discworld books also bring up the alrady-discussed concept of "steam engine time", which shows that human society tends to avert NoPlansNoPrototypeNoBackup (i.e., if Thomas Savery hadn't invented the steam pump, one of his contemporaries who were working on the same subject would have patented roughly the same thing, and [[InSpiteOfANail history might have been back on track]] just in time for James Watt to make the engine efficient enough to use portably, and no [[ForWantOfANail boiling-over tea kettle]] need be involved).

* OntologicalInertia is such a strong force in the ''[[LegacyOfKain Legacy of Kain]]'' series that the titular vampire spends most of his immortal life looking for a way to [[SetRightWhatOnceWentWrong thwart it]] at a [[TakeAThirdOption key point]] in his past. This is the origin of Kain's memorable "edge of the coin" speech:

* FlashForward2009 had elements of this. It was possible to change your future but very, very hard.

* In the final episode of ''KamenRiderDecade'', when BigBad [[Series/KamenRiderX Apollo Geist]] is defeated, his forcible merger and destruction of the multiverse continues unabated. In fact, if anything it actually speeds up. This leads to Decade receiving a WhatTheHellHero speech from his predecessors.

->'''Gary''': "I think the rule must be… you can’t change your own personal past."

* In the final episode of ''KamenRiderDecade'', when BigBad [[KamenRiderX Apollo Geist]] is defeated, his forcible merger and destruction of the multiverse continues unabated. In fact, if anything it actually speeds up. This leads to Decade receiving a WhatTheHellHero speech from his predecessors.