Delayed Ripple Effect

Marty: Listen, if things don't work out at the dance tonight and my folks don't get back together, when do you think I'll start to fade out? Doc: Beats the shit out of me. —Back to The Future, deleted scene.

Oh, no! After leaving your Time Machine, you stepped on the Butterfly of Doom. This can only mean it's The End of the World as We Know It! But wait... it takes a while for the changes to "catch up" with the present. Looks like it's going to be a Race Against the Clock to Set Right What Once Went Wrong!

In some Time Travel stories it takes a certain amount of San Dimas Time for history to change. Normally, this will be done so that the protagonists can prevent irreversible changes from making it to the present. Or maybe the story is set in a universe where people don't have Ripple-Effect-Proof Memory. Or the filmmakers just didn't have the time or money to create an Alternate Universe. Whatever. The point is that there's a time limit for "fixing" history and you better not pass it! A Ripple Effect Indicator is frequently used to show the Delayed Ripple Effect is happening.

This doesn't make intuitive sense, but then again, time travel generally doesn't. It is fairly common, though, for changes to Travel At The Speed Of Plot—for example, some "bad" change that sets up a crisis to take days or hours to hit the heroes, while the "good" change that resolves it propagates instantly. Sometimes, the ripple is portrayed as propagating through time. For example, the wave hits a certain time. Ten minutes later, the wave hits ten years in the past.

The Trope Namer is from the Back to The Future films.

Examples of Delayed Ripple Effect include:

Anime and Manga

• This is the main plot of the first Tenchi Muyo! movie. Tenchi's mother is somehow killed in the past, and to keep Tenchi from vanishing in a week (when Washuu's technology can't protect him any more), he and the gang travel back to figure out what happened and prevent it.
• Happens in Pokémon: Arceus and the Jewel of Life. After Ash & Co. return from the past, they find that Arceus is still wrecking the place with its Judgment. Only after a delay does Arceus recognize them as the people that helped it in the past and settle out of Unstoppable Rage.
• This occurs in Episode 117 of Yu-Gi-Oh! 5D's when the Three Emperors of Yliaster decide to have Clark Smith and his company, Momentum Express, erased for attempting to kill Yusei (whom they still have use for), and for revealing to him information regarding the Infinity device, which they've been using to alter history. Clark begs them not to do it when Placido returns from the past, having made the changes. Placido tells Clark to disappear and he has a short amount of time to panic before the temporal shockwave reaches him.

Comic Books

• In the Strontium Dog "Max Bubba" story, as Bubba alters the timeline, scientists 1400 years in the future actually measure the rate and degree at which time is changing. It doesn't make any sense.
• In a recent Fantastic Four arc, Franklin and Valeria Richards (Reed and Sue's kids) come back from a Bad Future where all of reality is collapsing to try and change things so that won't happen. Upon their return, they don't know if it worked. Something changed, but the new future is "still 250 years away" and won't get there before Franklin can't keep control any more and everything implodes.

Film

• In Back to The Future, Marty has a week to get his parents together before he will be erased from existence. Over the course of that week, a photograph he carries shows him and his siblings slowly fading away. On the DVD, the filmmakers admitted that this makes very little sense. To complicate matters even further, when he (mostly) restores the timeline, the photo changes back instantly.
• A Sound of Thunder: Giant translucent waves, which they called timewaves, came out of nowhere and knocked people around Matrix-style, altering groups of species with every passing, over and over. Apparently, stepping on a butterfly in the past causes drastic changes in evolution. Fair enough. However, with the use of this trope, apparently simplistic animals species are more prone to having their evolutionary histories altered, and with each wave the environment gets more and more altered. Which means the metropolis got claimed by a fierce jungle, despite the fact that the residents are all still there, and the parks are filled with baboon monsters that are completely bulletproof, unless shot in the throat, and after X number of waves grow wings. The protagonists must hurry to a working time machine to save the butterfly, as they themselves will be altered by the final wave. You Fail Biology Forever indeed.
• Stargate: Continuum includes a Delayed Ripple Effect which Mitchell, Carter and Daniel escape by using the Stargate. Carter later presumes that being in transit between two gates makes you Ripple Effect Proof. That's all the explanation you're going to get it, by the way. This is demonstrated in a visual effect. The normal traveling effects are tinted reddish-purple as the "ripple" is passing them by.
  • This is, of course, purely for the audience, as wormhole travel is instantaneous for travelers (what with them being disassembled into molecules and all).
• In Meet the Robinsons, the changes made by the bowler-hatted man visibly ripple across the future, ditto for when Louis reversed those changes. In fact, an entire scene is devoted to Louis giving the Bowler Hat Guy a tour of the restored timeline, repairing itself at an extraordinarily slow rate.
  • On the other hand, Lewis' decision to never make Doris should have reversed things then and there, but it didn't happen until he faced Doris and told it so. Doris vanishes instantly.
• Star Trek: First Contact. Since the Enterprise is still in the wake of the Borg Sphere's time wake, they aren't affected by the new timeline with the Borg conquering Earth and the rest of the galaxy.
• In Frequency, the effects of the temporally-displaced conversation between father and son don't take place all at once, usually seen as time waves or a sentence written in the past appearing in the present letter-by-letter.
  • This is quite inconstant. The speed of some actions in the past seems synced to the speed of the effects appearing in the present while others can take only a fraction of a second in the past but the effect in the present takes much longer.

Literature

• In the Isaac Asimov short story "The Red Queen's Race" its Hand Waved away that for every hundred years someone travels into the past, it takes a day for the changes to impact on the present (e.g. if someone left on a Monday and travelled 200 years into the past, any changes they made wouldn't be felt until Wednesday).
  • In that story, it turned out that the attempt to change history resulted in a Stable Time Loop instead.
• And something similar happens in Asimov's "The End of Eternity", when the protagonist tries to disrupt a planned Stable Time Loop by not doing what the script says he should. He expects this to alter his present and for everything to wink out of existence, but it turns out the effects won't be felt until he's made the decision not to reverse what he did, and that decision becomes irrevocable. By then, he's trapped in 1939 and can't see the effects anyway.
  • He does see one effect - his time capsule vanishes.
• A variation of this occurs in Mort, with the universe attempting to right itself with a continuously-shrinking dome converging on the princess that was supposed to die. Outside of the dome was the reality in which she had died. Inside she was still alive, though people tended to forget this until she started shouting at them.
• In the second book in the Feline Wizards spin-off of the Young Wizards series, a book on modern-day engineering gets sent back in time to Victorian England, causing drastic changes in the past which haven't yet caught up to the protagonists in the present.
• In the 1983 novel Millennium by John Varley (and the movie based on the book), it takes time for the temporal paradox and catastrophic breakdown of the fabric of time to reach the present (our future), thus giving the hero time to try to avert it. These waves can even be detected, giving the future a chance to buckle down.
• In the Sonic the Hedgehog novel In the Fourth Dimension, after failing to stop some baddies from contaminating the Big Bang with the Chaos Emeralds so the whole of history will be infected by evil, Sonic and Tails have to literally outrun the ripple effect on their treadmill-based time machine in order to change recent history to prevent the villains from getting hold of the Chaos Emeralds in the first place. Which instantly undoes the change at the beginning of time. Mind Screw much?
• Averted in Orson Scott Card's Pastwatch the Redemption of Christopher Columbus, in which temporal changes are revealed to be made the instant something (or someone) travels to the past. While, at first, they aren't sure if this will result in the creation of multiple realities, mathematicians eventually prove that, once the time travelers make their trip, their own timeline will cease to exist. That is the reason why the original "interventionists" sent a holo-recording instead of a streaming message; they'd only be able to get a single syllable out, if that, before the transmission would be cut off by the transmitter no longer existing. They were smart enough to cause the holo-projector to thoroughly self-destruct after delivering the message.

Live Action TV

• As noted, the PBS game show version of Where in Time Is Carmen Sandiego?? is based around this trope.
• An episode of Star Trek: Enterprise involved aliens traveling back to wipe out Earth in the 21st century with Captain Archer and T'Pol being sent back by Daniels to stop them. When they ask why their time hasn't changed, Daniels responds with something that amounts to "It takes time for time to change."
  • Which pretty much contradicts TOS episode, "The City on the Edge of Forever". As soon ad Dr. McCoy stepped through the Guardian of Forever, the Enterprise disappeared. Likewise, TNG film "First Contact" also showed immediate changes. Both also showed that people and ships at the epicenter of such a change are unaffected so they can Set Right What Once Went Wrong.
  • It also contradicts a previous episode in which Daniels pulls Archer from a turbolift into his own time in order to protect him from the Suliban. As soon as Archer is transported to the future, they look around and see total devastation around them. Apparently, The Federation would never exist without Archer being in the right place at the right time.
• An episode of Farscape is particularly odd. John's past self is dying...and he turns ghostly and translucent...so he goes to his mother, who does things like Tarot and believes in the mystic, and pretends to be himself, dying, and asks for her to get help. The "particularly" comes into play in that John almost did die in such an incident at that age, so why would said occurrence cause him to fade? (They end up creating a Stable Time Loop.)
• Red Dwarf was a big fan of this trope. Usually when changes were made in the past, it took time for the timeline to rearrange itself. e.g. White Hole, Timeslides, The Inquisitor
• In Doctor Who episode "The Big Bang", the entire universe has been destroyed retroactively, except for the Earth, which persists at least another 2,000 years. Later on, specific characters start disappearing whenever it's convenient to the story.

Tabletop Games

• In the original "Timemaster" game, temporal changes were immediate, but the "Timetricks" supplement added delayed changes (described as a wave of events moving forward through time).

Video Games

• In The Journeyman Project, shortly after you report for work (as a glorified Timecop), a series of alterations to history occur, and you have five minutes upon their detection to go back to 100 million B.C. before the temporal ripple hits your point in time. Once there, you retrieve a disc containing a record of unchanged history, in order to determine the points in time that have been changed.
  • The Updated Rerelease The Journeyman Project: Pegasus Prime partly fixes the Fridge Logic inherent in this scenario: if history was altered so drastically, then how come there's still a Temporal Security Agency to return to? It turns out that while the TSA still exists in the alternate timeline, it's a much different organization with a militaristic bent and a mandate to actively research history instead of simply protecting it. This is averted entirely in the sequels, where changes to the timeline can be detected from the future without the use of the Journeyman Disc.
• In Chrono Trigger, Marle ends up taking the place of her kidnapped ancestor after being sent back in time. It takes a couple hours (or days... or weeks...) before her existence is negated due to the kidnapped ancestor never being actually found because everyone assumed Marle was her and stopped looking (her own disappearance as a result only looked like someone already killed her, so nobody went looking again). She comes back in sort of an opposite delayed ripple when the timeline is fixed by her friends saving her actual ancestor.
• In the Chzo Mythos, two of these are critical to the Big Bad's plot.
• Achron is a real time strategy game that features the time ripple - you can go back in time and order your units around, but the effects won't catch up with you until after some time. The kicker - your enemy can do the same.
  • This delayed ripple provides a solution to the Grandfather Paradox - each "time wave" that passes switches the timeline between the killer and killee surviving. Since you can only travel back about eight minutes (relative to The Present), once the act of killing "falls off" the eight-minute timeline, it can't be changed in any way, and the paradox stabilises in its current state.
• In Command and Conquer Red Alert 2: Yuri's Revenge, the changes to the timeline only occur AFTER the game is finished (as Einstein shouts "The timelines, zey are MERGING!"). The explanation was that going back in time spun off an alternate timeline, but once the alternate timeline reached the inital departure point, the two timelines recombined and the "new" one took precedence over the "old" one - more or less. To paraphrase Carville, a man can get his head real messed up with all this time travel stuff...
• In Jump Start Adventures 3rd Grade Mystery Mountain, you have to travel through time and Set Right What Once Went Wrong before the Delayed Ripple Effect sets in. Naturally, you can Take Your Time.
  • One of the best examples of this trope displayed in this game involved the first human paintings. Naturally, the first human paintings were cave paintings, but the game's villain chose to change history and turn the first painting into that of a sad clown on black velvet. Your Exposition Fairy complains that this would destroy art history and frets that sad clowns on velvet would fill museums. However, this game does feature a small virtual art collection containing 30 unique art pieces, and take a guess what one of them is. That's right, a simple cave painting of a horse. This option never changes into a sad clown painting at any point during gameplay, even before this mission is solved.

Webcomics

• Bob and George uses this occasionally. This strip was later given commentary by the author questions how that could really work.
• Happens in this Sluggy Freelance strip, along with another delayed time ripple that comes along and reverses the previous one.

Western Animation

• In the X-Men animated series, there was one instance of changes in history causing Negative Space Wedgie-looking whirlwinds—in the words of Apocalypse, a temporal storm—that changed things as they went. Cable had to avoid them long enough to make his trip back to the present to figure out what happened.
  • That's nothing. The same thing happens during a picnic, with a doohickey on the professor's chair identifying it as such by name. How would you design something like that? And why would you have it built into your chair? How often can you be assailed by a tempest of changing history that you need a Time-Change-Geiger-Counter built into your chair?
• In the Justice League episode "Hereafter", Vandal Savage, upon sending Superman back in time to foil an evil scheme of his, has to wait a few minutes to see the changes.