Time Travel in fiction

[Miller]

@Just_Asking_Questions

Just being there could (and most certainly did) create any number of small changes that may “ripple” through to the Future, or be dampened by the “weight” of time.

Explicit in the movie - when he first arrives in the '50s, he crashes into and knocks over a pine tree. This changes the name of the mall in his future, from Twin Pines Mall, to Lone Pine Mall.

Responding to a post on this topic from the other thread:

@solost

But part of @Just_Asking_Questions’ point, I think, is not just ‘there should be two Martys, where did the other one go?’, but the fact that ‘cool family Marty’ probably never befriended a much older recluse scientist and never traveled to the past. But if no version of Marty ever traveled to the past, ‘cool family Marty’ would not exist. Paradox.

We know for a fact that “cool” Marty was still friends with Doc, because at the end of the movie, we see that Marty get in the Delorean and disappear after Doc gets shot. How they ended up friends is, almost certainly, vastly different from how they ended up friends in the original timeline, but it’s not impossible for it to have happened. Particularly since Doc knows he and Marty are going to be friends in the future, and can take steps to make sure he’s in Marty’s life somehow to make sure that happens.