The technical problem he had confronted in composing Ballet Mécanique — specifically the problem of synchronizing multiple player pianos so that they advanced through their paper rolls at exactly the same rate — was not trivially solved. Player pianos ran on pneumatic mechanisms: a roll of perforated paper passed over a suction bar, and wherever a perforation aligned with a hole in the bar, air pressure changed and a hammer struck a key. The rhythm of the music depended on the perforations’ spacing. But two pianos running independently would drift out of synchronization over time. Antheil’s solution involved precise calibration of the mechanisms driving each roll, so that both advanced at exactly the same constant speed. You could not control one piano from the other; you could only make both machines run so accurately that they stayed together.
He married Elizabeth Markus, the niece of a Viennese novelist, and they settled in Hollywood in 1936, where Antheil found work as a film composer. He was good at it. He wrote the score for The Buccaneer (1938), In a Lonely Place (1951), The Pride and the Passion (1957), and many others, and he composed the theme for the CBS television series The Twentieth Century, which ran from 1957 to 1970 — probably the piece most Americans heard without knowing his name. He also wrote a candid, funny memoir called Bad Boy of Music, published by Doubleday in 1945, which gave an account of his Paris years, his European reputation, and his relationship with the more orderly world of Hollywood commercial work.