i hadnt seen that about george mcFly and Doc Brown.Doc Brown = George McFly
Here's a red-letter date in the history of science: November 5, 1955. Yes! Of course! November 5, 1955! That was the day I invented time-travel. I remember it vividly. I was standing on the edge of my toilet hanging a clock, the porcelain was wet, I slipped, hit my head on the sink, and when I came to I had a revelation! A vision! A picture in my head! A picture of this! This is what makes time travel possible: the flux capacitor! It's taken me nearly thirty years and my entire family fortune to realize the vision of that day.
nov 5 1955 is when George fell and hit his head
and I finally see how the future was changed.
Bif spends the whole movie trying to make George angry but George is so docile that he can't do it. It's only when he pushes Lorraine down that he finally succeeded in making George angry. George does some weightlifting and voilà new George.
it's a perfectly legitimate moral of the story but the movie does a bad job of making it clear.