- "It's the ripple effect!"
- —Doc to Marty
The ripple effect is the gradual changing of the future timeline after the changing of present events. Items brought from the future transformed to become consistent with the alteration of the timeline are changed due to the ripple effect.
Not only objects, but people themselves can experience or knowingly live through the ripple effect itself due to the effects of changing time from someone or someones traveling through time into the past. The experience can be either positive or negative, either altering the time line around time travelers to a more acceptable one upon returning to a future time or being left in a present that is changed in the past by others or endangering one's own existence all together.
Future created objects or people who traveled in time can fade away in the ripple effect or be changed to reflect the new present that now exists due to the occurrence of a ripple effect through the changing of events in a past time period.
Objects and the ripple effect
The first example of the alteration of a future item was the family photograph that Marty McFly carried in his wallet. The photograph was taken in or before October 1985, and Marty carried it with him to 1955. After Marty accidentally interfered with an event that brought his parents together, as pointed out by Dr. Emmett Brown, Marty's siblings, in order of their birth, began to disappear from the photo: the oldest one (Dave) going first, followed by the second oldest (Linda), and ultimately, Marty himself. Since Marty still had one week to bring his parents together for the Enchantment Under the Sea dance, the ripple moved at a relatively slow speed. However, as the time ripple moved ahead from 1955, and the prospects of George and Lorraine's marriage were postponed, the existence of Dave was canceled, followed by Linda. By the end of the week in 1955, the ripple was nearly twelve years ahead, and the possibility that Marty would be born in 1968 was becoming increasingly unlikely. When Marty fixed the timeline (by prolonging the high school dance long enough for his parents' first kiss to occur), the ripple reversed, and the photograph instantly showed the reappearance of Marty, Linda, and Dave in the reverse order of their disappearance.
Other visual examples of the ripple effect were seen in the newspapers brought from the future to the past (1985A to 1955), and the 1955 photograph of the 1885 tombstone. In each case, the speed of the transformation was governed by whether it was still possible to stop the event that defined the path of subsequent happenings. Thus, when Marty burned the Grays Sports Almanac in 1955, making it impossible for Biff to ever get the information, the newspapers and the matchbook brought from 1985A transformed in a matter of seconds. On the other hand, the photograph of the tombstone did not complete its alterations until Buford Tannen was finally defeated in a fight.
The ripple effect also occurred immediately upon Doc being sent back to 1885. In a matter of seconds, history changed, placing a 70-year-old DeLorean inside the Delgado Mine and bringing 1885 Doc's letter into existence to be delivered by the Western Union man at that specific time. One can argue it would have been impossible for these events to happen if the DeLorean had not been struck by lightning just seconds earlier. Another argument could be that the time lagged effect of the ripple is only perceptible from the origin point and that the changes would occur imperceptively when they reached each individual relevant date. In addition, Doc spent a significant amount of time in 1885, long enough that, from his perspective, the ripple would have passed Marty in 1955 by the time he sent the letter.
Yet another appearance of the ripple effect took place in 1885, when Marty saved Doc from being shot by Buford Tannen; Doc's name faded from the tombstone in the 1955 photograph, and subsequently, when Buford was sent to jail, the tombstone itself faded from the photograph.
Time travelers and the ripple effect
The ripple effect doesn't only work on viewed objects but can also affect those brought from one time period and left in alternate versions of said time periods as history and events in the past are changed to alter the events in the present day world they are left behind in.
An example of this is when a fainted and out cold Jennifer Parker is left in 1985A along with Doc's dog Einstein, both of which were brought from the original (yet altered present due to Marty's first trip to the past) 1985 to 2015 and returned from 2015 to what became 1985A due to Old Biff Tannen's tampering with said timeline by stealing the DeLorean time machine, traveling back to 1955 and giving his younger self the Grays Sports Almanac. This nightmarish alternate reality was fixed by Marty destroying the almanac in 1955, preventing it from causing any damage to be done with the future knowledge it would give. The timeline is instantly changed back and rippled around both Jennifer and Einstein who returned to the world around them that they had originally left as if they had never been in an alternate version of the present at all. As Marty notices the changes in the objects brought from the future, he then realizes that this also means that his girlfriend and Doc's dog are now in their regular reality they had left the first time as well even though they weren't with them at that moment in 1955 as said events were undone. Doc confirms that both are OK and fine due to the "ripple effect". Even though the world literally did change around Jennifer, she has no known recognition of the alternate 1985 (most likely due to being out cold for its entire existence), but remembers 2015 that she had traveled to with Marty before and after the ripple effect around her occurred.
Also when Old Biff from 2015 returns in the stolen DeLorean time machine from his trip to November 12, 1955 back to the time he had left from, he starts to feel pain as if he had been shot in the chest. The timeline rippled around him to reflect the new present he was now in due to his tampering with it. A present that his older version no longer existed in due to his being killed off at an earlier date now in the new alternate past he just created.
(It should perhaps be noted that Old Biff's erasure from existence is a deleted scene from Back to the Future Part II. Biff's being in pain and something being definitely wrong upon his return is fully seen, but the actual moment where Biff fades away, which would follow, isn't in the final movie release. This deleted scene appeared in the 1990 behind-the-scenes television show The Secrets of the Back to the Future Trilogy, in which it was used to answer a question about the space-time continuum as seen in the trilogy. Host Kirk Cameron theorizes that Biff may have been shot by his 1985A wife Lorraine "sometime in the mid 1990s".)
Marty experienced a similar situation in 1955, (as stated above) in which he caused his own existence to be in jeopardy due to preventing his own parents from meeting and falling in love in 1955, thus potentially eliminating his own birth from ever occurring. He would have faded away (and even started to for a moment, with one hand becoming transparent) in said ripple effect occurring, if he didn't undo his tampering with time in the past and have his parents fall in love to eventually give birth to him through their marriage and the natural path of time. While some ripple effects can be instant, Marty's was prolonged over time with the use of a picture as an aid of reference for how long he had to fix the damage done in the past by his tampering with events.
After Edna Strickland destroyed the town of Hill Valley in 1876, Marty and Doc saw the buildings and roads vanish, and replaced with hills and grass. Their memories were likely retained due to them being residents of 1986 rather than 1931.
Objects that were viewed as the ripple effect took place
- Hill Valley Edition of USA Today newspaper from 2015.
- Hill Valley Telegraph covers with both Doc Brown- and George McFly-related stories.
- Picture of Marty, his brother Dave and sister Linda.
- Matchbook displaying the name of Biff's Auto Detailing business in 1985.
- Photograph of a tombstone erected in 1885 that shows Emmett Brown's name and death on it, then "Clint Eastwood" 's, and then vanished.
- Faxed printout created in 2015 with huge text saying "YOU'RE FIRED!!!"
- Hill Valley Telegraph detailing the death of Carl Sagan/Doc written on June 13, 1931. It then specifies that Carl Sagan was being transferred to another prison and was killed before reaching the destination. It then changed to cover the death of Arthur McFly. Its final ripple (though not shown) has the newspaper detailing the escape of Carl Sagan.
- Marty's photograph of George shows his dad erasing from existence as Arthur was killed by Kid's gang. After saving Arthur, George starts to reappear in the photo.
- After discovering that Jennifer has changed in 1986B, Marty pulls out a photo from their prom night, only to see her vanishing from the photo.
Living beings who experienced the ripple effect due to time travel
- Back to the Future trilogy
- Back to the Future: The Animated Series
- Back to the Future: The Game