https://twitter.com/elonmusk/status/1530516552084234244?
In the comics, Osterman's father was a watchmaker, and it is heavily implied that his father's tutelage gave Jonathan the knowledge of how things are put together, and is what helped him reconstruct himself after being split apart. This becomes more clear when the "Stranger Things" audience realizes that as One describes his backstory to Eleven and Nancy, it is during a montage scored by Philip Glass' "Pruit Igoe and Prophecies" — the same song Zack Snyder used in his 2009 "Watchmen" feature film adaptation. This means that the clock is a reference to both Doctor Manhattan (as One seems to be an evil version of the character, with a similar origin) … but also, to the Doomsday Clock referenced throughout the comic.