She was once called “undoubtedly…the most beautiful woman on earth.” But Austrian-American Hollywood actress Hedy Lamarr (November 9, 1913 – January 19, 2000) was also one of the most important mathematical minds of the 20th century.

In 1940, shortly after leaving her arms-dealer husband and escaping to Hollywood from Nazi Europe, Lamarr befriended composer George Antheil and his wife. With her knowledge of munitions and interest in mathematics, she came up with the idea for a radio that hopped frequencies, allowing for torpedoes to be controlled remotely without detection. Antheil envisioned a way to do this with a coded ribbon reminiscent of a player piano strip. The two spent a year in phone calls, napkin sketches, and prototypes scrapped together on Hedy’s living room floor, until they finally perfected the concept and filed a patent for a “secret communication system” in 1941.

Hedy was only 28.

Her frequency-hopping invention laid the foundation for wireless communication long before computers and provided the basis for modern-day technologies like WiFi and Bluetooth. Lamarr went on to make 18 films between 1940 and 1949, including Hollywood’s highest-grossing movie of 1949, in addition to mothering two children.