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During the late 1930s, Lamarr attended arms deals with her then-husband arms dealer Fritz Mandl, "possibly to improve his chances of making a sale".[41] From the meetings, she learned that navies needed "a way to guide a torpedo as it raced through the water." Radio control had been proposed. However, an enemy might be able to jam such a torpedo's guidance system and set it off course.[42] When later discussing this with a new friend, composer and pianist George Antheil, her idea to prevent jamming by frequency hopping met Antheil's previous work in music. In that earlier work, Antheil attempted synchronizing note-hopping in the avant-garde piece written as a score for the film Ballet Mechanique that involved multiple synchronized player pianos. Antheil's idea in the piece was to synchronize the start time of identical player pianos with identical player piano rolls, so the pianos would be playing in time with one another. Together, they realized that radio frequencies could be changed similarly, using the same kind of mechanism, but miniaturized.[4][41]