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[[quoteright:300:[[WesternAnimation/RockyAndBullwinkle http://static.tvtropes.org/pmwiki/pub/images/PeabodysImprobableHistory_01_300_7911.jpg]]]]

So, you've got your [[TimeTravel time machine]] and you're merrily having [[AdventureTowns adventures through time and space]]. And, when you arrive in AncientRome, it turns out that a clan of [[HalfHumanHybrid half-werewolf half-vampire]] [[MagicFromTechnology techno-sorcerers]] are attempting to take control of the Senate from within! You have to stop them!

...but wait a minute. The vampirewolf sorcerers didn't get to Italy in 326 BC by TimeTravel; they've apparently been there all along. So, if you interfere, won't you be changing history? Why isn't [[MeaningfulName Romulus]] {{Alucard}} Caesar in the history books you studied?

Well, maybe it's a StableTimeLoop, and the timeline you know only exists because [[YouAlreadyChangedThePast you were there with silver garlic in Rome]]. But wait, weren't you worried about changing history just last week? Didn't your traveling companion [[HitlersTimeTravelExemptionAct prevent you from killing Hitler]] to avoid a TemporalParadox? [[TimeyWimeyBall So what makes]] ''[[TimeyWimeyBall this]]'' [[TimeyWimeyBall any different?]]

When history has changed, and the protagonists must fix it, but there's ''no reason'' for it to have changed, that's a WaybackTrip. Unlike SetRightWhatOnceWentWrong, where the time travelers go back and defeat the villain, and as a result, history is changed for the better, in this trope, the time travelers go back and defeat the villain, and as a result history ''stays the same''. The ultimate result is then either a StableTimeLoop (Rome ''always had'' secret lycanthropires all along) or a CloseEnoughTimeline, perhaps in which the protagonists TrickedOutTime (there were no monsters the "first time around", and the second time, there were but no one will be the wiser).

This trope seems to derive from the AdventureTowns treatment of TimeTravel. Periods of history are treated like places rather than points on a timeline. New York in 1897 isn't the ''cause'' of New York in 2007, it's just 110 years earlier, and is free to have its own history and events.

This could technically be considered a case of MakeWrongWhatOnceWentRight and TerminatorTwosome, in that the protagonists are changing history to make their (that is, ''our'') timeline happen instead of the one with Roman vampire werewolf sorcerers.

Can be {{handwaved}} by having a DelayedRippleEffect.

See also MeanwhileInTheFuture. Compare to FieldTripToThePast.



[[folder: Anime and Manga ]]

* In one episode of ''WandabaStyle'', the girls [[PhlebotinumBreakdown accidently travel to the past]], when TeenGenius Susumu was a mere ChildProdigy. While there, they encourage him to follow his dreams, and even act as guinea pigs for toned down versions of experiments he'll run in the future, yet when they return to the present, nothing at all has changed.

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[[folder: Comic Books ]]

%% * The Dallas arc of ''ComicBook/TheUmbrellaAcademy'' has this going on.


[[folder: Film ]]

* This trope is the basic premise of the ''{{Terminator}}'' movies (even though side effects cause some ontological paradoxes).


[[folder: Live Action Television ]]

* ''Series/DoctorWho'' does this all the time, especially in the new series. It was pointed out by Martha in "The Shakespeare Code". The Doctor explained that it was similar to ''Film/BackToTheFuture''. Except this doesn't make sense either; in ''[=BttF=]'', Marty was the one who altered history, whereas in the episode, the witches existed totally independent of the Doctor's travels. The general HandWave is that things have gotten ''really'' screwy since the Time Lords died off.
** In the original series serial "Pyramids of Mars", Sarah Jane asks why they have to stop the villain destroying the Earth in 1915, when they know it's fine in 1980. In reply, the Doctor takes her to 1980... and it turns out to be a desolate wasteland. Apparently, once the Doctor arrives somewhere, he must complete the StableTimeLoop to maintain the "proper" version of history. (In which case, one wonders... and this question has been voiced in the series... why the heck does the Doctor keep traveling around?! Arguably, if he didn't, the effect would be that 1980 Earth had ''always'' been a desolate wasteland, and there wouldn't be a "real" 1980 for Sarah to come from) In ''Blink'', the Doctor explains that time, rather than being a linear chain of cause and effect, is actually "[[TimeyWimeyBall a big ball of wibbly-wobbly, timey-wimey stuff]]." This apparently explains everything.
** The new series has also introduced the idea of "fixed points", which amounts to there being some things you can change, and some things you can't. Even though several villainous plots would have averted those fixed points if they had come to fruition- OmnicidalManiac plans to destroy the universe / the multiverse / reality itself have shown to have ''succeeded'' because the Doctor had been killed in a ForWantOfANail scenario, but this still did not cause the TimeCrash messing with a fixed point does even though said-points hadn't even happened yet. At least once, a fixed point in time was actually ''engineered''. The rules for them aren't exactly set in stone either.
* Every episode of ''Series/{{Voyagers}}'' The series did mention "the flow of history being tampered with", implying that the changes were caused by ''other'' time travellers.
* The TV series ''Series/QuantumLeap''.
** In one episode, Sam leaps into various points of Lee Harvey Oswald's life. As it turns out, in the "real" history, [[JohnFKennedy Jackie Kennedy]] was killed too.


[[folder: Video Games ]]

* In ''VideoGame/ChronoTrigger'', if you visit the pre-historic time period, and then beat the game without causing the humans to defeat the Reptites, will give you an ending where the Reptites became the dominant species on the planet. However, beating the game before landing in that time period, that future doesn't come to pass, implying that simply landing in the past causes the Reptites to win.
** In fact, the "World of Reptites" ending isn't caused by the landing in the past, but by the fact that to beat Lavos at this moment, you'll have to take Ayla with you; and, since she's the most skilled human fighter and the only one who would attack the Reptite headquarters...
** Also, it is implied that the Gate Key incident may have motivated the Reptites to attack Laruba village and get very serious. If Crono and co. never arrived in 65 million BC, that never would have happened.
* The main plotline of ''VideoGame/MarioAndLuigiPartnersInTime''. Aliens invade the past Mushroom Kingdom, causing mass destruction and taking over the castle... but the only effect this has on the present Mushroom Kingdom is the time portals that suddenly appear in the otherwise-intact castle.
** Technically, the time holes appeared due to an unrelated event that was nonetheless destined to happen so that the bros could travel back in time in the first place. Specifically, from [[LaymansTerms timey machine go boom.]]
* In the various Caverns Of Time instances in ''VideoGame/WorldOfWarcraft'', the players' goal is preserving some event in Azeroth's history the way it should be, by defeating The Infinite.


[[folder: Webcomics ]]

* "The Stormbreaker Saga" in ''Webcomic/SluggyFreelance'' involves Zoe and Torg going back to medieval times and stopping the demon K'Z'K (who they blasted into the past in an earlier arc) from conquering the world. How this works in terms of a StableTimeLoop or DelayedRippleEffect is made more confusing by [[http://www.sluggy.com/daily.php?date=990303 this]] strip, which thankfully invokes BellisariosMaxim to {{lampshade|Hanging}} it.
** Zoe also claims that the answers to her history test changed over night, with the new answers being in line with her experience in the past. The internal consistent theory of time travel is not revealed to the readers. (If there is one.)


[[folder: Western Animation ]]

* The trope name comes from ''Peabody's Improbable History'', a [[ThreeShorts segment]] on ''WesternAnimation/RockyAndBullwinkle''. In every episode, Peabody and Sherman would visit a historical personage with some problem that kept them from doing what they were supposed to do historically, and help them with it.
** In the first appearance of this segment, it is explained that a straight-up TimeMachine is actually rather boring since [[InThePastEveryoneWillBeFamous not everyone in the past is famous.]] So, Mr. Peabody invented a "Should-Have-Been" machine to ensure that his trips will be interesting rather than historically accurate.
* ''WesternAnimation/TimeSquad'' is often thought of as a throw back to Peabody and Sherman; with a time cop and a prissy robot and an orphaned kid to guide them. They go around time traveling and fixing people because in their universe, in the future, time has gotten so old and worn-out that they have to fix glitches constantly.