Timey-Wimey Ball in live-action TV.
- 12 Monkeys: Cole is only chosen for the time-travel mission because there is a recording of Cassandra recovered in 2043 where she mentions him by name, implying some kind of Stable Time Loop is involved (Jones herself says that Cole's destiny is "preordained"). Yet, the entire premise of the series (unlike the original film) is that history is mutable and that the past can be re-written (which is clearly demonstrated when Cole scratches Cassandra's watch, causing a scratch to simultaneously appear on its future counterpart).
- Ash vs. Evil Dead: In the Season 2 finale, the heroes go back in time and end up destroying the cabin in the woods, burying the Necronomicon in the process, before the events of the original film, which should logically have triggered a Cosmic Retcon and undone the events of the entire franchise. Yet when they get back to the present, everything seems exactly the same except for Pablo being alive again. Lampshaded in the Season 3 premiere, when Pablo is filling Candace in on all this, and admits that it doesn't make much sense that nothing changed.
- Black Hole High: "Fate": When Vaughn, having traveled back in time to meet his mother, steals her hairclip as a memento, all of history is rewritten so that his parents never meet, his father becomes a familyless loser instead of creating the wormhole, and Professor Z doesn't get a scholarship from his company to go to college. Which is all well and good. What no one attempts to explain is why, in this new history, Josie never attended Blake Holsey High (Though later events suggest that her presence there may have been engineered to keep her close to the wormhole). To complicate matters further, it eventually turns out that both Vaughn's mother and Josie's father are time travelers, so without Pearson's wormhole (the basis for Time Travel), Josie shouldn't exist either.
- In Season 8 of Buffy the Vampire Slayer, Future Dark Willow exploits the time travel confusion for all it's worth to manipulate people to her advantage.
- Charmed has some rather interesting ideas of how time travel works:
- In one episode, Chris is taken 20 years into the future as a prisoner by a bunch of evil dudes. Before he leaves, he manages to slip in a comment about the "creaky floorboard". The witches take the hint and brew a potion for him to use as a weapon, which they hide under said floorboard. The camera goes back and forth, showing what is happening in the future (Chris facing the bad guys) and the present (the girls hurrying to finish the potion). It's strongly implied that, had they not gotten the potion ready in time (i.e. before Chris in the future is shown looking under the floorboard), Chris would have found nothing. In actual fact though, the girls could have relaxed and spent hours making the potion, it would still have been there 20 years into the future, provided it was never removed from under the floorboard at a later time. Speaking of which, the writers may just have assumed the potion would be gone after the episode, rather than continually being under that floorboard for the next 20 years.
- In another episode, a demon steals little 3-year-old Wyatt's magic powers. Next thing, 20-year-old Wyatt and his brother come time-travelling from the future, saying "We were fighting demons when Wyatt suddenly lost his powers, so we thought we'd come to the point in time where the change occurred and see what happened". This makes no sense in any form of time travel. If 3-year-old Wyatt lost his powers, then 4-year-old and 5-year-old Wyatt wouldn't have had any powers either, all the way up to 20-year-old Wyatt. It would make no sense for him to loose his powers only suddenly at the age of twenty. Not to mention, once they fixed the problem in the present, 20-year-old Wyatt should have never lost his powers in his time at all.
- In another, Chris (having time traveled back to the show's present from the future) is corrupted by demonic influence. They make an antidote for it and Piper, who is pregnant with Chris at the time, drinks the potion. Naturally, this cures the adult Chris after she drinks it rather than preventing him from being corrupted in the first place.
- Chousei Kantai Sazer X: Both Sazer-X's allies and the Neo Descal respond to the changes Sazer-X makes in the past as if they're happening in real time for them instead of things that have already happened. A good example would be when, when Sazer-X blows up the Descal pirate ship, the Neo Descal send some of their forces back in time to stop them from changing the past further, even though any future changes Sazer-X would have made would have already happened for them. All of the future characters retain their memories of things in the original timeline even if they're Ret Goned out of existence.
- Continuum has a literal Timey-Wimey ball, since there are eight pieces that magnetically grab onto each other and when they do so in the presence of sufficient power, it activates and zaps anyone within a certain radius to a new destination time. In-narrative, many of the characters spend at least the first two seasons try to establish the "rules" of time travel, such as whether they are in a Stable Time Loop or can actually change history. One early storyline sees the terrorists of Liber8 attempt to deliberately invoke the Grandfather Paradox by killing the grandmother of their main adversary Protector Keira Cameron; after Keira counters by taking the pregnant mother of Liber8's leader hostage, the death of the grandmother of rogue Liber8 member Matthew Kellog seemingly proves that nothing will happen, although it's noted that nothing happening doesn't definitely prove anything as there are alternative explanations ranging from them now being in an alternate timeline to Kellog being wrong that this woman was his grandmother. By the beginning of the third season, it's established that certain actions can make timelines unstable while in other cases they can cope with a paradox; one timeline nearly collapses after Alec Sadler departs that timeline before his future self can invent the relevant time machine, but in another case Matthew Kellog's future self intended to abduct the Kellog of the present to provide organs for himself and seemed certain that he would survive the apparent temporal paradox.
- Dark Shadows:
- Barnabas Collins travels back in time to save Collinwood from the ghost of Quentin. When he returns, Amy and David still remember being tormented by Quentin's ghost, despite the fact that with the change in history, Quentin never died and is still alive.
- Despite the times Barnabas is released from his coffin when he travels back to 1897, and then to 1840, he still has a history with the Collins family in the present era.
- The fact that Quentin, Tad, and Desmond Collins survived in 1840, thanks to Barnabas and Julia, changing the line of inheritance, does not seem to have any impact on the Collins family in the present day.
- The Trope Namer, Doctor Who: As a roughly consistent general rule, Stable Time Loops work, but doing something that will prevent you from going back in the first place has varying degrees of bad consequences. The specifics, however, are complicated enough to warrant their own subpage.
- For its first three seasons Eureka is nice and consistent that any mucking around with the fabric of time is catastrophic, then Season 4 came and dropped the ball. Pilot: using a "tachyon accelerator" to accelerate a particle beyond the speed of light uses a "tachyon collision" that will destroy the town, if not more. Season 1 finale: Mental Time Travel creates an alternate timeline, but the "real" timeline starts to bleed through and destroying both timelines; necessitating time travel again to Make Wrong What Once Went Right. Season 3: slowing a single photon down causes a "Groundhog Day" Loop and if it's not sped back up and the loop broken the town, or more, will be "erased from existence". Season 4: Using a wormhole to travel to the past changes the current timeline, there is no threat of collapse or erasure outside 1 episode which makes it due to "exotic particles quantumly linked across time", the time travelers replace their counterparts when they return to their time yet maintain their memories of the unaltered timeline, and then 2 of them travel to the past again and witness their first visit without changing anything else or creating any more problems (or even replacing themselves in the past from their first visit to the past — or in the case of 1 traveler, he was originally from the past and didn't replace his original past self).
- The Ghosts Of Motley Hall a series told from the point of view of the ghosts from various eras who haunt a derelict stately home in England discover one Christmas that, for no reason ever explained, the house has slipped through time to the Victorian era. The ghost of Sir George meets and talks to a young boy who is excited about his presents. Sir George realizes the boy is himself, and only then recalls a vague memory of having met an elderly man on Christmas Eve, who he had assumed to be some distant relative whom he never saw again.
- The Girl from Tomorrow has a very large one: Tulista travels back through time and retrieves Silverthorn. Taking him out of the timeline should screw with the future, but doesn't, thanks to one very Delayed Ripple Effect. Silverthorn then takes Alana back to 1990, and their presence in the timeline again fails to interfere with the future properly. It's only after Alana takes them both back to the year 3000 that people begin to notice the Delayed Ripple Effect, despite the fact that if anything, it should have interfered with two time periods. They then attempt to resolve this by returning Silverthorn and Jenny to their respective time periods, only to have the capsule somehow U-turn and return to 2500, meaning there are (briefly) duplicates of Alana and Lorien. This is further compounded when Silverthorn builds a Portal to the Past to get some nuclear bombs. This is only resolved when Petey resets the Portal to send Silverthorn and Draco to 70,000,000 BC. Given what Petey says at the end of the series and the events during "Tomorrow's End", it looks like the entire series is actually a Stable Time Loop.
- The Good Place: Parodied. Michael explains that time in the afterlife apparently works like this: while time on Earth moves in a linear fashion that can be represented by a straight line, time in the afterlife curves and loops around until it looks like the name "Jeremy Bearimy" written in cursive letters, and so the denizens of the afterlife call the timeline "Jeremy Bearimy." There's also a dot above the "i" which, described as concisely as possible, is Tuesdays. And also July. And sometimes never. It's the time moment in the Bearimy timeline when nothing never occurs.Chidi: This broke me. The dot over the I. It broke me. I-I'm done.
- Henry Danger: After Drex succeeds in making sure Ray never got his Captain Man powers, he sends both him and Henry back to the present, yet nothing has changed. Schowz explains that as long as the Time Jerker's time machine stays on, nothing will effect the present.
- Heroes can't decide if they are going for Static Time Travelling or a Dynamic Time Travelling. And that's the least problematic thing.
- Strangely, it seems the farther into the future they see, the more pliable time becomes. For example, if Hiro tries to fix something close to the present, for example, saving Charlie's life, or capturing Usutsu, it's impossible. Can't change it no matter how hard they try. However, the apocalyptic future they inevitably go to in every single season so far, they always find a way to avert that. Well, usually, that seems to be changing for Season 3, and even before that, some things were constant across all the alternate futures. Peter's scar, and Hiro being badass with a sword.
- Listen carefully; in the Heroes-verse, time has torsion!
This means that one can Set Right What Once Went Wrong only with "leverage"; only the passage of sufficient time permits time to be altered, thus preventing seers and Time Travel from being a Deus ex Machina! - The Charlie issue was kind of resolved in a "she's already dying" way rather than "time travel won't let me save her" way; this is more or less repeated with his father in the next season (only "it's his time" this time, instead of the already dying thing). As for the random jumps through time... he spends the rest of the season learning to control his ability; it turns out he just needed to get back the self-confidence which he had lost since he realized he couldn't save Charlie. The time jumps are a bit convenient, and that Hiro's explanation makes no sense doesn't help. Not to mention that nothing else they've done with time travel has made any sense. They don't even try to be consistent, it seems. Very comic booky... which is probably the point. Still makes for bad headaches, point or no.
- However, The Heroes novel Saving Charlie took the opposite tactic, implying that Time/God wouldn't let Hiro save Charlie because You Can't Fight Fate. Over the course of the story, Hiro lost control of his powers several times in the past while he was trying to romance Charlie and wound up "jumping" to key locations relating to his quest to save Claire Bennet. Eventually, Charlie figures out what is going on, tells Hiro he must face his destiny even if it doesn't involve her and the two lose their virginity together the evening before Charlie goes into work, meets Hiro for the first time and then gets killed by Sylar.
- THEN HE SAVED CHARLIE. No, really. Seasons later, Hiro goes back in time, and gets none other than Sylar (the Season 1 Sylar who'd never toyed with the idea of a Heel–Face Turn) to repair Charlie's aneurysm telekinetically and leave her brains on the inside in exchange for non-Time Crash-inducing information about his own future. However, she's kidnapped by the Big Bad of that season, and Hiro doesn't see her again until she's an old woman who's lived a happy life that Hiro wasn't going to undo so he could have her. Still, it was pretty awesome to see Hiro turn "You Can't Fight Fate" into "Up yours, fate!"
- According to The Other Wiki, Hiro can change history as long as he doesn't eliminate his own cause for traveling in time. However, while this rule is sometimes played straight (he can't simply teleport Sylar away, as that would prevent him from meeting Charlie in the first place and he couldn't save her) but other times... not so much (his attempts to save the suicidal employee would eliminate his reason for time travel but it never works out that way. Of course, history doesn't actually wind up changing in that case, so it may not be a contradiction after all).
- The Israeli drama The Island's basic premise relies on this and (after the first season) fighting the Big Bad, who keeps trying to Make Wrong What Once Went Right.
- Kamen Rider Den-O spikes the Timey-Wimey Ball like no other:
- When an Imagin wreaks havoc in the past, it's translated into the present oddly. For example, if you were standing next to a bridge support, and an Imagin went to last year and broke it, you would see it vanish into thin air now (as opposed to, say, remembering that time a year ago when they had to fix the bridge 'cause a monster trashed it). But since it was trashed in the past, it had to have been rebuilt at some point, right? Apparently, when an Imagin breaks something, the fix's Ontological Inertia fails shortly after the time the Imagin went back. Now that's the Timey-Wimey Ball at its wibbly-wobbliest.
- When the Imagin is killed, the Timey-Wimey Ball then uses the original memories of people in the future to repair the damage to the past. However, anything or anyone who is not remembered is not restored. So now no-one remembers the bridge getting repaired because as far as the great unwashed masses know, it was never broken in the first place.
- In the crossover movie OOO, Den-O, All Riders: Let's Go Kamen Riders, an elaborate Temporal Paradox was revealed when we learned Naoki is Mitsuru's father. They didn't even try to explain it. This is a paradox because Naoki was stranded in the past after time had already been changed. The version of 1973 that led to the 2010 we know did not have Naoki in it. Therefore, Mitsuru should not exist in the 2010 we know.
- The original Kamen Rider has two friends of Goro's by the names of... Naoki and Mitsuru. We meet them in the latter third of the series. Whether Let's Go Kamen Riders is trying to say that they are the same ones and we didn't know they were time travellers is hard to tell, but if that's what it means, it's certainly interesting. However, this adds another level to the timey-wimey: a 1973 with Let's Go Kamen Riders having happened led to the Kamen Rider universe proceeding in the manner we saw in the older shows, even though the whole movie is that the Den-Liner gang's trip leads to a Bad Future which got a happy ending in the present, but can't ever be erased.
- One major plot point of Kamen Rider Zi-O is how the Monster of the Week, the Another Riders, stole the history of the original Kamen Riders they're based off of. By the midway point of the story, the timeline is under so much strain from the paradoxes and alternate futures that they're not even stealing the histories anymore, and Tsukasa Kadoya notes that time and space are at the edge of collapse because of how everyone is screwing everything up.
- On The Orville, Union officers are taught "temporal law" at the academy specifically so they can spot the dangers and act accordingly should they encounter a space phenomena, science experiment or sufficiently advanced alien trying to do something with time. Both Ed and Kelly have taken the course; Ed hates the topic enough that he'd allegedly eat broken glass rather than talk about it. Kelly still messes up, and creates a doomed timeline until they can fix things.
- Quantum Leap is definitely not a Stable Time Loop, since the entire premise revolves around actively changing the past,note and there are several Ripple Effect Indicators in the future that are observable by the audience (such as "Honeymoon Express", where Sam's changing of the past results in a different senator reviewing the Quantum Leap project in the future). However, there are other instances where Sam is implied to have Been There, Shaped History (such as using the Heimlich maneuver on Dr. Henry Heimlich in "Thou Shalt Not..."), and it's also implied that Sam (as a child) learned his theory of time travel from Moe Stein after Sam (as a time-traveling adult) suggested the "ball the loop" theory to Moe in "Future Boy" note ... which would not be possible if it wasn't a Stable Time Loop.
- Red Dwarf:
- Just about any time travel episode, but most especially the Season 6 cliffhanger in which the Dwarfers' scary future selves blow up Starbug, apparently killing everyone on board. Season 7 opens with Lister explaining direct to camera that, because they'd been killed, their future selves never existed to come back, therefore they hadn't been killed, and this is also why Starbug is suddenly bigger. The intelligent video camera suffers an explosive breakdown trying to understand this.
- Ironically, Rimmer's plan in the cliffhanger episode, which was to destroy the Time Drive so that their future selves couldn't come back to kill them, would have made far more sense as an explanation.
- And later in that same episode, The Boys From the Dwarf violate the same laws that allowed them to survive after they take John F. Kennedy back in time to assassinate his past self!
- In "Future Echoes", Rimmer tries to explain Timey-Wimey to Lister:Lister: Hey, it hasn't happened, has it? It has "will have going to have happened" happened, but it hasn't actually happened happened yet, hactually.
Rimmer: Poppycock! It will be happened; it shall be going to be happening; it will be was an event that could will have been taken place in the future. Simple as that. Your bucket's been kicked, baby. - The first two times time travel came up a Stable Time Loop was established as far as anyone could tell.
- Many descriptions of Sapphire and Steel imply it's a Time Police show. Instead, it uses time travel — and the rules thereto — like a Cop Show uses criminal procedure: arbitrarily.
- Seven Days. It is a rather harsh ground here, since the time machine is alien technology that was badly fixed by humans and due to possibly some screw up (or just plot convenience) it has all kinds of weird side effects. Anyway, when it works like it is supposed to do, it sends you back seven days and your old self and the time machine vanish, either erasing the "bad" timeline or creating an alternate. It is consistent in that. People notice the machine and him vanishing, the episodes are just mostly centered on Parker and until he makes his call they don't know what happened.
- There was an episode where an accident during time travel splits Parker into a good and an evil version. The good version is killed, so the evil version is sent back in time again, creating another good version.
- It's difficult to count the number of times the machine has not worked right. For just a few examples: it brought a person back from the dead (nearly unraveling all of reality), put Parker into the body of Pope John Paul II, created a Mirror Universe (almost literally, since all writing is in mirrored English), etc. It's a wonder the aliens don't show up to tell the humans to stop messing around with technology they don't understand before they destroy the universe. Then again, they probably don't know and have never bothered to look for their missing prison transport (or that other ship that crashed in Siberia).
- Stargate-verse:
- The Stargate SG-1 episode "1969" dealt with a Stable Time Loop. Following that, however, all the Stargate series have just treated time travel as only affecting things after the initial entry point. Time is changed in both "2010" and "Moebius" without creating a stable loop. Same with "Unending". The DVD movie Continuum is a bit more complex, since it added a new element to the mix, but ultimately results in the same thing.
- Stargate Atlantis had two episodes in the vein of "2010" and "Moebius" ("Before I Sleep" and "The Last Man"), following pretty much the exact same conventions in both.
- Stargate Universe also sticks to the formula, first with the episode "Time". A Kino is found, which has a recording of horrible death. This recording shows a way to avert it, but they fail to do so and send a second Kino back. That one, along with the first, does the job. Then comes "Twin Destinies". In this one, a wormhole connected to Earth from inside a star somehow catapults the entire ship back in time. Telford (In the time shifted ship) goes through the gate and makes it back to Earth, while the rest of the crew (except Rush) go through when the gate is unstable and get transported to a local stargate hundreds of years in the past while leaving behind Rush, who stays on the ship. The current timeline crew stripped the time-displaced copy for parts, while the extra Rush and the original Telford on Destiny died. Meanwhile the version of the crew sent into the past establishes the civilization of Novus, leading to the present day crew eventually meeting their own descendents in the following two parter.
- Star Trek: Deep Space Nine:
- The series has the relation between Benjamin Sisko and The Prophets. While it appears to be a Stable Time Loop, there just enough wrong with it that it fits here. In the first episode, Sisko meets The Prophets, who live outside of time, and have great difficulty even conceiving of a 'linear' existence. They and Sisko have a nice chat, and Sisko tells them that the Bajorans revere them as gods, it seems that The Prophets weren't really aware of this. It gets tricky from here... As the Prophets seem to 'get' their position, they then (not that the flow of time should mean anything here...) start doing all the things that they are revered as gods for. Okay, one loop, fairly simple Ontological Paradox. Later on, viewers find out that Sisko was born from a relationship his father had with a woman possessed by a Prophet with the explicit purpose of conceiving Sisko. So, Sisko visiting the Prophets made it possible for him to be born in the first place, so that he could visit the Prophets and tell them that they were gods. Keep in mind that if Sisko didn't tell them they were gods, they wouldn't need Sisko, they would have just kept on being non-linear, not to mention the enormous effect the resulting lack of religion would have on Bajor. Now what really twists the boat is that The Prophets are supposed to exist outside time, yet they clearly change after Sisko's first meeting. So they possess both timelessness (from being able to interact with anytime freely) and their own timeline (Which is clearly affected by Siskos visit) These paradoxes and timey-wimey balls are not really explored in the series (though more 'common' forms of time travel are) and the series can be enjoyed without worrying about the timeline of timeless entities. Still, there's rather a lack of coherency.
- The whole thing gets kind of lampshaded, when two versions of O'Brien try to figure out the paradoxes and give it up, simultaneously saying, "I hate temporal mechanics!" The episode in question, "Visionary", is quite Timey-Wimey in itself, as O'Brien keeps jumping five hours into the future and back, with varying changes once the station reaches that point he jumped to. He even avoids death twice, first by avoiding a booby-trapped surveillance device that killed his future self, then by having Dr. Bashir perform a specific scan on him after finding out the results of his own autopsy. In the final jump, though, Past!O'Brien ends up dying from radiation poisoning, sending Future!O'Brien back 3 1/2 hours to stop the Romulan attack on the station. The resulting O'Brien has issues with his place in the universe for a while afterward.
- Star Trek: Deep Space Nine's Sisko and his companions are visited by the Department of Temporal Investigations in Trials and Tribble-ations. The agents mention that they have an extensive file on captain James T. Kirk. They also hate Predestination Paradoxes and jokes.
- This episode also involves a literal Timey-Wimey Ball, the "Orb of Time"
- Another episode had the Prophets bring a famous Bajoran poet forward in time. After they sent him back, all the copies of his famous unfinished poem suddenly showed it as finished. The characters understand that part, but they never figure out how the Prophets made it so that it still hadn't been complete until after his visit. So there's a timeline where he disappeared into the future, and then after he went back there's a timeline where he went back, but somehow the second doesn't overwrite the first it just picks up where the first left off.
- Also "Past Tense", where a transporter accident throws three of the crew back in time to 2024. At first, Sisko tries to stay as low-profile as possible, but after his very presence indirectly causes the death of a key historical figure, Sisko must take his place in order to preserve history.
- "Children of Time" has the crew meeting their descendants on a planet because they hit an energy barrier that sends them two hundred years in the past. They go back and evade the energy barrier and the colony vanishes — because it was sabotaged by the future version of a character living in the past.
- Star Trek: The Original Series: While we don't get to see all of Captain Kirk's "seventeen separate temporal violations" (as described by the Temporal Investigations detectives in DS9), we do get a few.
- "The City on The Edge of Forever": McCoy is rendered insane after falling on his own hypospray and getting a massive overdose, which causes him to beam down to the planet they were examining and jump unawares through a time portal, changing the past. Kirk and Spock then have to go after him and undo the damage.
- "Tomorrow is Yesterday": An accident with a collapsing star gets the Enterprise thrown back into the 1960s. Unfortunately, in the time it takes them to figure out what's happened, they've already managed to contaminate the timeline, and they spend the rest of the episode trying to fix it, which is complicated by the fact that they have to interact more with the timeline in their efforts to eliminate the original contamination. They manage to do it by, in essence, rewinding time further, which erases the part of the timeline where they caused the contamination. (You think that's weird? They also transport two people into their own past bodies which somehow erases their memories.)
- Star Trek: Enterprise: The whole Xindi arc is a big example. So the Sphere Builders tell the Xindi to go nuke Earth, because they know (through their semi-time-travel) that in the 26th century, Earth will come kick their ass. So the Xindi go do a preliminary Earth nuking, which causes the Humans to come over and kick their ass, now. The Sphere Builders misled the Xindi into believing that humanity will destroy the new Xindi homeworld, because the Sphere Builders knew that, in the 26th Century, the Federation (which by then will include the Xindi) will decisively defeat the Sphere Builders at Procyon V.
- On a smaller scale, "Twilight" depicts a timeline where Archer is infected by neural parasites during the Xindi mission that prevent him from forming any new long-term memories, leading to T'Pol having to take command and Earth being destroyed by the Xindi superweapon. When Phlox devises a treatment to remove the parasites, he realises that since the parasites exist outside of the usual dimensions, removing them from Archer now prevents them ever having infected him in the first place; by completely purging the parasites from Archer, they are able to prevent him ever being infected by them in the first place.
- Star Trek: Voyager
- In the 29th century, The Federation has become a sort of Time Police, making sure no one messes with history. The fact that the previous (chronologically) series have never had a problem with timecops showing up is not addressed. They were even admonished that they ought to have been held to account before. Not to mention, if they did, the audience would never know about it...note
- The episode contained the morally questionable practice of arresting and trying a man for a crime he had yet to commit. The rather profound implications of this are casually handwaved with an assurance that he'll be combined with his future selves somehow before the trial, never mind that said future selves are already part of a Temporal Paradox since it would presumably be impossible for him to carry out the crime once he'd been arrested for it. This might not be so troubling if it weren't clear that his future selves were suffering from some kind of severe psychological breakdown, the present self would not decide to commit the crime for many years and thus could not be said to have intent, and being removed from command at this early point would have prevented said psychological breakdown from occurring in the first place. Given equal apparent opportunity to prevent someone from becoming a criminal before it was too late, or punishing him for merely being capable, under the right circumstances, of going through with it, which would you choose? Apparently The Federation, at least according to Voyager's writers, prefers the latter. And the guy's future self was only mentally unstable because said Time Police had already "somehow combined" him with yet another version from an alternate timeline, who had been stranded for decades as a homeless guy on 20th century Earth. One would think they'd get the hint that "combining" people from different timelines is a bad idea...
- This was actually introduced three seasons earlier, in "Future's End" (in which an accident with the time travel device causes both ships to be thrown back to the late 20th century), but the concept was not elaborated on until "Relativity".
- Star Trek: Voyager also had one of the most illogical time travel plots. They're passing a planet and detect a massive explosion. They investigate the planet and find no life. Janeway and Paris are transported back to before the explosion. It turns out that Voyager's attempts to reclaim them caused the explosion. Janeway stops their next attempt by firing her phaser into the time-portal technobabble thingy, which pushes the Reset Button and they pass the planet without incident. The entire episode ignores that they never intended to go to the planet in the first place, so the whole thing never should have gotten started, since there never would have been an explosion to cause them to investigate. This, and an earlier episode that uses the exact same type of time paradox, both get the ultimate Hand Wave by Captain Janeway as "temporal mechanics means effect can happen before cause".
- Also a major question mark inherent in the finale episode "Endgame". Admiral Janeway from 2404 decides to go back and change the past because three of her favorite crew members did not get happy endings due to Voyager's decades-long journey home. To achieve this she needs help from her old crew (and one of their daughters). The problem of everybody having the last few decades of their lives erased and replaced with an uncertain alternate timeline engineered by Janeway is kind of glossed over, leaving the question of whether she actually changed history or simply created a new timeline.
- Voyager is also a part of two other time travel incidents, in "Year of Hell" and "Timeless". In these two cases, however, the change in the timeline is such that the alternate timeline is erased and no one remembers it.
- Star Trek: The Next Generation:
- No list of Star Trek timey-whatever-things... is complete without Yesterday's Enterprise. The fact that it brought back Tasha and had Klingons fighting the Ent-C aside, it made absolutely no sense.
- A quote from Jonathan Frakes re: Yesterday's Enterprise: "To this day I do not understand Yesterday's Enterprise. I do not know what the fuck happened in that episode. I'm still trying to understand it ... but I liked the look." This would become pretty darn Hilarious in Hindsight, given his Trek cinematic directorial debut featured both time travel and a revamped color scheme for the Enterprise.
- This one isn't all that hard as far as paradoxes go. During the Battle of Narendra III, the Enterprise-C made a Heroic Sacrifice against the Romulans attacking the Klingon outpost. This is exactly the kind of honorable, selfless action that would impress a Proud Warrior Race like the Klingons and eventually led to a peace treaty between them and the Federation. However, during the battle, a massive explosion caused a Negative Space Wedgie to form, sending the Enterprise-C to the present. But without the Enterprise-C's presence at the battle, the peace treaty would have never formed. So once the Enterprise-C arrives in the present, the present almost immediately becomes a Bad Future where the Federation and Klingon Empire have been at war for decades. Guinan, who has some alteration-proof sense of how the timeline is supposed to be, tells them it's wrong, and the two crews realize that the Enterprise C's disappearance at such a critical moment could cause a change of that magnitude. The Enterprise-D helps repair the C enough to send it back through so it can play the role it was meant to play. But Tasha Yar discovers from Guinan that she died a pointless death in the "normal" timeline, so she volunteers to go back with the understaffed C so that in at least one timeline, she can have a death that meant something. The Enterprise-C goes back to the Battle of Narendra III, thus restoring the main series timeline. But the one thing they hadn't counted on is that rather than kill everyone outright, Romulans captured several survivors from the Enterprise-C, including alternate-timeline Tasha. So all in all, a bit complicated, but not all that hard to understand.
- It's much simpler if one looks at from the perspective of the Enterprise-C: in the middle of a battle, they get sucked into a Bad Future, one which hinged on their disappearance mid-battle. The future folks help repair their ship, then send them back in time to avert the bad timeline in favor of one they all hope will be better.
- Also, the Season 7 episode "Parallels" has Worf bouncing between multiple alternate universes (hence the episode title). And as if that weren't enough, when they go to investigate the phenomenon responsible, they get into a battle which weakens the barriers that usually keep parallel universes apart and hundreds of thousands of Enterprises start appearing.Wesley Crusher: Captain...we're receiving 285,000 hails.
- Supernatural:
- "In The Beginning" established that while time travelers can make small changes, they will ultimately lead to the same result because destiny cannot be changed. This is ultimately proven true when Dean's attempt to protect his family from the Yellow-Eyed Demon ends up causing his mother to make the deal with him that eventually kills her.
- There is a bit of confusion after Dean convinces his father, John, to buy the Impala Dean himself will eventually inherit instead of the VW Bug John had initially intended to buy to impress girlfriend Mary, Dean's eventual mother. Would John have bought the VW Bug if Dean had not interrupted with his suggestion?
- "My Heart Will Go On" blatantly contradicts this by having an angel go back in time and stop the Titanic from ever sinking, preventing anyone on board from dying and leading to hundreds of their descendents who originally never existed appearing in the present. However, the angel who un-sinks the Titanic also states that ever since the Apocalypse was averted, the old rules no longer apply (presumably because the Celestial Bureaucracy is in disarray and can't afford to be watching over every minute detail in order to ensure that it all leads up to its supposed "destiny" anymore.)
- "Frontierland" circles back to no major changes, but it's a little unclear whether Sam and Dean's actions are a Stable Time Loop or You Already Changed the Past.
- Much like in "In the Beginning", "The Vessel" presents a confusing question as to whether history stayed the same in spite of Dean's presence, or if Dean's presence inspired the events that become history as he knows it. The boat is sunk by the use of the Hand of God to sink the German sub, but the crew didn't know about the sub or the Hand of God until Dean made them aware of them.
- "In The Beginning" established that while time travelers can make small changes, they will ultimately lead to the same result because destiny cannot be changed. This is ultimately proven true when Dean's attempt to protect his family from the Yellow-Eyed Demon ends up causing his mother to make the deal with him that eventually kills her.
- Timeless for the most part appears to be fairly established in its time-travel rules. It is possible to change the past, though the result is usually a Close-Enough Timeline. And yet, the Butterfly Effect is a very real danger, except when it comes to big historical events (a case in point - the protagonist's sister is inadvertently erased from existence because of small changes to a particular historical event, but the premature death of as important a historical figure as Lord Cornwallis doesn't completely change American history. Ripple-Effect-Proof Memory applies to time-travelers, but there is no Ripple Effect Indicator - objects that are taken to the past in the machine retain their original state irrespective of changes to the timeline. The major contradiction though is despite all this, the series seems to be getting up a Stable Time Loop - one of the main antagonist's is motivated to try to change history based on a journal he received from the protagonist's future self describing some of the events of the series!
- Timeslip, a 1970s British series, presented a form of time travel where the past, not "really" being able to "happen again" is "fixed" — by which they mean that you can interact with the people there, but not alter events, and can be hurt, but not "seriously". In the first serial, a time traveler is shot dead, and collapses, unconscious, leaving blood, but no wound. She wakes up, but still feels the pain of having been shot. You get the first minute of a muddled explanation about it being a sort of shared hallucination before it's dismissed as too complicated to explain.
- Time Trax can't seem to decide if Darien and the fugitives are in their own past or a time-shifted parallel universe. Most episodes appear to take the second option, insisting that their own time remains unchanged no matter what happens in the "past". On the other hand, in some episodes, Darien has SELMA leave coded messages in the classifieds for his boss in the 22nd century, which would only be possible in the first version. No one seems concerned about any temporal paradoxes, though, and Darien's goal is not to prevent any changes but to catch escaped criminals. One episode is notable for having both versions: Darien insists that, due to everything that has already been altered by the time travelers, an aspiring country singer may no longer become the star she was in his own history. At the same time, he accidentally becomes the inspiration for his favorite song.
