Ripple effect
From Futurepedia, the Back to the Future Wiki
- "It's the ripple effect!"
- —Doc to Marty
The ripple effect was 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.
The first example of the alteration of a future item was the family photograph that Marty McFly carried in his wallet. The photo was taken in 1984 or 1985, and Marty carried it with him to 1955. After Marty accidentally interfered with an event that brought his parents together, the McFly children began to disappear from the photo, with 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. By contrast, when Marty fixed the timeline (by prolonging the high school dance long enough for his parents' first kiss), the ripple reversed, and the photo 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 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.
Yet another appearance of the ripple effect took place in Part III. This was when Marty saved Doc from being shot by Buford Tannen, and the Doc's name faded from the tombstone (but the picture of the tombstone remained, indicating that someone was still going to die. In addition, when Clara was saved from falling into the ravine, the name was still "Shonash Ravine". When Marty returned to 1985, the ravine was now called Eastwood Ravine, supposedly because of Clint Eastwood (Marty) had fallen into the ravine along with the locomotive.
