It could mean that that point in time inherently contains some sort of cosmic significance, almost as if it were the temporal junction point, for the entire space-time continuum. On the other hand, it could just be an amazing coincidence.
— Dr. Emmett Brown (Christopher Lloyd)
11 seconds sound clip from the Back to the Future Part II movie soundboard.
You can hear this line at 01:01:36.316 in the Blu-ray version of the movie.
