I'm reluctant jump on the bandwagon singing the praises of Back to the Future, as its overcrowded, and I think there's not enough discourse mentioning the ways it's aged a bit poorly. But it struck me watching that opening sequence how it reflects the theme of the story. All these mechanical apparatuses work in perfect harmony, but there' one missing piece: life, as represented by the absent Einstein. Without life, not only does the whole process lose its elegant perfection, but its purpose as well. Without life, it just makes a mess. I think this feeds into the larger theme around the mechanics of the universe, and Doc Brown's relationship to it. He thinks the machinery flowing smoothly is the highest good, and is even willing to potentially sacrifice his own life to ensure that flow. But without life, the universe is just rocks and gasses moving around one another in curves through nothing. Why does that clockwork entropy matter more than Doc's life? Without life, it's like the machines built to feed Einstein, without Einstien. It just makes a mess. Life matters more than mechanics. I took that as the theme of the film.
