While this theory doesn't improve the quality of the movies themselves, it certainly adds an interesting spin to them - and that theory is that Back To The Future is a metaphor for sexual reproduction. It's quite convincing, given that it's based on a number of things; the flux capacitor itself looks like a uterus, the time machine needs to be entered by a virile young man in order to function, the product of the activity is the "birth" of a number of different timelines/versions of people and all of it is being overseen by a "doctor". It could just be a huge coincidence, but fans may have just discovered what the movies' creators were going for (although why they would actually do this is a complete mystery).