When old Biff goes back to 1955 and creates a timeline B (which is reality now), he started to fade in 1955 of timeline A after handing the magazine to his younger self. So the answer is the greater the change made to time the longer it takes to affect it especially if there is a possibility of correction to the original time stream. The further it branches off from the original time stream the longer it takes for changes to catch up to current time. It can branch and make new futures but those are eventually absorbed into the one time stream. In other words there is one time stream in Back to the Future. Marty was able to travel to an alternative 1985 instantly in the first Back to the Future because it was so close to his current 1985. So Old Biff would not have been able to travel to future Biff ruled 1985 or even 2015 because he is such a completely different individual in those times as well as the world around him has changed so drastically. My belief is that the Flux Capacitor creates a temporary bubble around time travelers that allow them to be absorbed into a changed time line rather than sudden disruption. This is because you are traveling down the time stream rather than in static time waiting for events to catch up.Īt first this may seem like a contradiction but it really isn't. If you travel back into time from an altered future point (from 2015 to Biff altered 1985) the transition is instantaneous. Even if he had jumped in the time machine and traveled back to 1985 Hill Valley he would have had to wait a week. An example of this is when Marty saves his dad he alters history but it takes about a week to catch up to his present and erase him from time. If the change you made in time affects the future you have to wait for it to catch up to you. I explained something similar to this over on the Sci-fi/Fantasy site, but this one is actually easier to answer. I took some screenshots from a YouTube clip: These events are never depicted in the trilogy, although Robert Zemeckis and Bob Gale suggest this theory as a way of explaining Biff's "disappearance." Having created an alternate timeline by giving his younger self the almanac, the old Biff from 2015 no longer existed, once 2015A became part of the 1985A timeline.Īnother possibility is that Lorraine, in 1996 of the alternate timeline, shot and killed Biff. This can be explained for two different reasons:įirst, these events created a time paradox.
In scenes deleted from the film, Biff Tannen of 2015 fades out of existence (much like Marty was in the original movie when interfering with his parents' meeting) once arriving in the future, having been erased from existence in that time period. After they restored the timeline Jennifer was still sleeping on the porch.* Why didn't they notice? Maybe because they were out on the street when it happened and Hilldale looks the same in 2015A.īTW, time travelers "transitioning" between changed timelines is implied by Doc Brow when he tells Marty not to worry about leaving Jennifer on the porch in "alternate 1985". Doc and Marty "transitioned" to 2015A without noticing.
Speculation: Old Biff returns to the changed 2015 (designated 2015A).