“A Serious Man” is the story of an ordinary man’s search for clarity in a universe where Jefferson Airplane is on the radio and “F-Troop” is on TV. It is 1967, and Larry Gopnik, a physics professor at a quiet Midwestern university, has just been informed by his wife Judith that she is leaving him. She has fallen in love with one of his more pompous colleagues, Sy Ableman, who seems to her a more substantial person than the feckless Larry. Larry’s unemployable brother Arthur is sleeping on the couch, his son Danny is a discipline problem and a shirker at Hebrew school, and his daughter Sarah is filching money from his wallet in order to save up for a nose job. While his wife and Sy Ableman blithely make new domestic arrangements, and his brother becomes more and more of a burden, an anonymous hostile letter-writer is trying to sabotage Larry’s chances for tenure at the university.