ReneeLouvier said:
I mean...geezus, if you've got DeLorean, and Marty from 1985 takes it back to 1955, and 1955 Doc sees the Flux Capacitor, how do you know he invented it and didnt' just copy from his future self?
Because in the beginning of the first movie, Doc told Marty that he got the idea for the Flux Capacitor from a vision he had after slipping and hitting his head on the bathroom sink.
So, Marty goes back in time to 1955, and the date set for arrival is the date of Doc's accident. What I don't think most people realize is that he arrives there VERY EARLY IN THE MORNING, and spends most of his day wandering around 1950s Hill Valley (not to mention meeting his future father, getting hit by his future grandfather's car and having his future mother fall in love with him) before he finally gets out to 1955!Doc's house. In fact, it's evening/nightfall by the time he gets out there.
When Doc of 1955 answers the door, there's a white bandage on his head. Which means Doc's accident in the bathroom and the vision of the Flux Capacitor that resulted from it
had already happened that day. Marty even pointed it out, which was one of the factors that made 1955!Doc believe his story about being from the future. Probably the only thing that seeing the Flux Capacitor in real life, inside the time machine, did for Doc was give him a confidence boost about his abilities as an inventor.
-Kim