In many Time Travel stories in which a character in the past is changing the future, there will be an object, or sometimes a person, from the future that is directly affected as a specific consequence of the Time Traveler's actions.
The main effect is that this object, or if it's a photograph, the subjects on the photo, will vanish or reappear as changes are made to the timeline. This is done typically to show whether what the protagonist in the past is doing the right or wrong thing.
In short, a Ripple Effect Indicator is an object, originally from the future, that fades away or otherwise changes based on actions in the present changing the timeline.
- In the first story arc of Booster Gold Vol 2, Booster's JLA membership certificate changed to reveal alterations to the timeline, for instance becoming The Flash's death certificate.
- In Detective Comics Rebirth, Tim Drake meets a future version of himself who's a brutal Batman who kills. Future!Tim thinks he's in a Stable Time Loop (saying "I've had this conversation with myself already") and that nothing can be changed. But when he mentions Connor Kent, Tim has no idea who he's talking about. Checking the records, Future!Tim realizes the timeline has been altered. He suddenly slashes Tim's arm, causing a huge cut. Future!Tim then pulls off his glove to see a long-healed scar that wasn't there before and realizes this is a new timeline that he can alter...by any means necessary.
- Marty's photo of himself and his siblings in 1985 serves as this in the original Back to the Future. As the time to get his parents falling in love draws closer, his siblings from the eldest on down vanish from the photo and reappear once he succeeds. Variations of this trope occur throughout the series enough that by Back to the Future Part III, Marty has gotten savvy about it, taking a photo of the grave of the person whose death he's trying to prevent before going to the past.
- In Frequency, Frank (John's father) needs to give an indication to John that he is still alive, and so burns a few words into his desk in the past. In the present, John sees these words appearing on the desk at the same speed at which Frank is seen burning them, as if they're being burned in the present. Other examples include events in the past triggering sudden, sometimes disorienting changes in John's memories and that of his peers, averting or causing people's deaths that would have been avoided before, and giving a new, nicer appearance to the decorations in the house.
- Meet The Robinsons had a giant sky vortex that would suck things that ceased to exist in, or spit them back out.
- In Men in Black 3, when K is "erased" from history, his apartment shifts to a regular apartment (no secret stash of alien weapons) and a different family is living there when Jay comes by the following morning.
- In Looper, when Joe (as well as one other looper that we get to see) 'writes' on his arm with a knife in the main time of the film (when he's still young) so that the resulting wounds, after healing, show up on his older self's arm. The message told his older self where to meet to settle the situation. Later when young Joe sees that old Joe won't quit, he kills himself to prevent his old self from killing a child he's grown to care about; old Joe disappears, just like that.
- Cable keeps his daughter's charred teddy bear on his belt in Deadpool 2. When a Delayed Ripple Effect makes it look new, he knows he's succeeded in saving his family.
- In Timecop, Walker finds himself in 1994 with both the past and 2004 versions of villain Aaron McComb. Walker kicks the 1994 McComb across the face, opening up a huge cut. Instantly, a scar materializes in the same spot on the face of the 2004 MComb
- In one of the Charmed tie-in merchandising novels the sisters battle an ancient goddess that's not restricted to a single time so she can hop from era to era, dimension to dimension. She starts messing with a few of the Halliwell Family's ancestors and the effects in the present are changes to the family house's interior decoration, changes in Phoebe's appearance (her hair becomes long and dark) and Piper's son, Wyatt disappears because he was never born. Phoebe also passes out after getting a barrage of visions of her family in the future and the past being attacked by the ancient god.
- In the short story "Abe Lincoln in McDonald's" by James Morrow, the titular American president visits a version of the 20th century in which slavery remains legal in the South. His decision to sign the Emancipation Proclamation, made at the moment a slave is shot to death, causes that slave's body to be replaced by a robot.
- In TimeRiders, three teenagers police the timeline, living through the same two days (10/09/01 through 11/09/01) in a loop. One of them, Sal, is responsible for walking around the city of New York during the days before and of 9/11 attacks, checking everything for changes caused by the Ripple Effect. Due to them living in a time bubble, they all have Ripple-Effect-Proof Memory.
- Al often served this role in Quantum Leap. For the most part, he merely reported the timeline changes to Sam as relayed by Ziggy, however, one episode, "A Leap for Lisa," in which Sam had leaped into a young Al shows changes such as Al being temporarily replaced by another person entirely.
- In Voyagers! Phineas Bogg's device showed a red light when history had to be changed and showed a green light when it was set right.
- Another example would be the premise of Early Edition, in which a man literally receives tomorrow's newspaper today, and is expected to change the negative headline/lead story into something more positive before it happens. When he is successful, the headline/story changes accordingly.
- The third season episode of Star Trek: The Next Generation "Yesterday's Enterprise" pulled off a clever example: The Enterprise encounters a Negative Space Wedgie, and Worf is called to the bridge. The camera shows Worf at Tactical, beginning a step to Picard. Camera pans to Picard, Time Ripple happens, and then the camera pans back to reveal Tasha Yar at Tactical, just as she's always been. Once the timeline is corrected, the camera pans back to reveal Worf at Tactical.
- Star Trek: Voyager. In "Year of Hell", a Krenim scientist is using a temporal weapon to change history for his race's benefit. Voyager is being harassed by a poorly-armed Krenim vessel commanded by a weaselly xenophobe who rather pathetically demands that Voyager leave their space (which they don't even own). When the temporal shift occurs, he's suddenly a Smug Snake commanding a powerful warship with temporal torpedoes that can pass right through Voyager's forcefields. When the timeline is finally restored to normal, the Krenim commander has a professional demeanor, politely but firmly insisting that Voyager take another course around the disputed area.
- In MythQuest, it's possible for the characters to travel into a myth and act it out, including a different ending. If they change a myth, storybooks and textbooks in the real world change.
- 12 Monkeys: Cassandra's wristwatch. Cole finds the 2043 version of it and brings it back to the past with him. When he scratches the present-day version of the watch, a scratch simultaneously appears on the future version.
- In Frequency, whenever Frank changes something in the past, Raimy gets to see the changes apply to her present timeline in real time. E.g., Frank's burn mark on the ham radio, the changes to Maya's Police file on screen as she gets rescued, or the vanishing of Goff in front of Raimy's eyes once he commits suicide in the past.
- The Flash (2014):
- The secret "time vault" includes a future newspaper article about the Flash written by Iris West (or rather Iris West-Allen). When Barry briefly loses his powers in season one, the vault's records of the Flash temporarily vanish.
- This comes up again in season three. After Barry alters the timeline, he's horrified to see the article is now written by someone else, since Iris is now apparently fated to die at Savitar's hand. It changes back in the season finale when H.R dies in Iris' place.
- Fun example in the Doctor Who story "The Two Doctors": When the Second Doctor is abducted and (temporarily) transformed into a hedonistic, gluttonous Androgum, the Sixth Doctor, who's trying to track him, finds himself increasingly distracted by thoughts of food.
Sixth Doctor: Well, they say there's more than one way to cook a cat. Here, pussy, pussy, puss-puss! Here, little puss. [The cat flees.]Peri: Doctor, what are you doing?Sixth Doctor: They can make quite good eating. Small mammals are quite flavoursome when baked.Peri: What are you saying? I don't understand.Sixth Doctor: I knew it would happen. I'm turning into an Androgum!
- In Mortal Kombat 9, Raiden's medallion cracks when he receives his first visions from the future. As the story progresses, the medallion shows only more signs of damage every time Raiden fails to prevent certain future events from happening...until the very end, when Shao Kahn is finally defeated for good.
- Marle's vanishing and return early in Chrono Trigger is used to demonstrate both how past events are affecting the future and how you know you succeeded in repairing the time line.
- Here's a few more: defeating Magus in the past results in the Mystic village statue of him replaced with Ozzie, and then said village finally not hostile to humans once you defeat Ozzie. Restoring Fiona's forest in the past (it appears, along with a shrine, in the present) and helping an NPC in Porre learn the value of sharing turns their descendant in the present, who is the Mayor, into a generous person.
- A few more indicators are part of ending montages: Marle making a strange frog-like noise if Frog marries the Queen, the opening cinematic happens again but everyone's a Reptite, and Robo crashes into Atropos in a futuristic Millennial Fair.
- In Chrono Cross, the Dead Sea replacing Chronopolis in Home World, reflecting a timeline where Crono did not defeat Lavos.
- Achron uses various symbols on the timeline to indicate various events happening.
- The Journeyman Project games have the Temporal Security Agency, which has one agent on watch at any given moment monitoring history for any ripples. In the first game, once such ripple was detected (which only travel forward in time), an agent was sent back to prehistoric times to retrieve the archive of the "correct" history in order to compare to the new history and determine the time and place of the interference. Later, this is Hand Waved by a new, easier, method of tracking and determining ripple origins. The game cutscenes show a holographic screen with a representation of the timeline on it with an actual ripple (reminiscent of an earthquake representation) spreading into the future. Naturally, the agents must act before the ripple reaches them.
- In Pokémon Mystery Dungeon: Explorers, the hero ceases to exist as a result of preventing the Bad Future they came from. One of special episodes in Sky expands on this by showing the effects on the future, with the sun's rise finally bringing an end to the eternal night, and the denizens of the future ceasing to exist, as well. They all get better.
- In the Back to the Future by Telltale Games, Marty uses newspapers and a photo of George for the same purpose as he did in the movies. In the latter parts of the series, a newspaper from an alternate Hill Valley exclaims that crime is at an all-time low. After Citizen Brown (who by that time was convinced to go with Marty) decides to instead blame Science and try to make Edna Strickland in 1931 to instead live happily with Young Emmet, it instead changes to an article about a rather messy divorce between the two in 1985. Once Citizen Brown realizes Edna will never change and throws himself in the way of Edna in an escaping car and dies/fades out, it instead changes to Doc Brown receiving the Key to The City in 1985, in which the crazy wild-eyed old man scientist Doc we know and love (mostly) arrives at that moment because Marty gave Young Emmet a cryptic message about that article.
- In the My Little Pony: Friendship Is Magic episode "It's About Time", Twilight Sparkle herself is the Ripple Effect Indicator. After being (unsuccessfully) warned by a haggard-looking and supposedly battle-weary version of herself from the following Tuesday, the Twilight of the present day focuses her efforts to avert that outcome. As her exploits show the bad future goes unobstructed because her appearance grows to become that of her future self's until the fateful Tuesday arrives and she looks exactly the same. Ultimately it's all for naught as the "disaster" ends up being her worrying for nothing...so she tries to go back in time to correct her self from one week earlier not to make the same mistake... but can't get the message across, which sets into motion the whole affair and closes the Stable Time Loop.
- Referenced as a joke in the ''Bob's Burgers" episode "My Fuzzy Valentine." Bob and the children are on a mission to find the perfect Valentine's Day gift for Linda: the old "love tester" arcade machine he and his wife used while on a date 15 years ago. When Bob balks at the price, his daughter Tina says, "Come on Dad, you need to get that Testometer for Mom. I'm starting to disappear!"
- In the Lucas Bros. Moving Co. episode "Beeper Beeper", the Lucas Brothers go back to the year 1995 and accidentally prevent their younger selves from buying the same CD, starting a Feud Episode between the kid twins over their new favorite bands. The future Lucas Brothers then begin to experience brief zaps of "disappearing" to remind them that they need to stop their past selves' interests from diverging any further.