Hedy Lamarr, once voted the most beautiful woman, invented a torpedo navigation system!

Hedy was born in Austria and began her acting career as a teenager after dropping out of school. She was in over 30 films. She chose her stage surname in homage to Barbara La Marr, a beautiful silent film actress who died of tuberculosis in 1926. 

She played Delilah in the 1949 film Samson and Delilah. The film was the highest grossing film of the year. Lamarr went to her composer neighbor, George Antheil, with her idea and together they submitted the idea of a secret communication system. 

Lamarr and Antheil patented the idea in 1942. It was the early version of frequency hopping and used a piano roll to change between 88 frequencies. It was intended to make radio guided torpedoes harder for enemies to detect and jam. It wasn’t used in the military until 1962, though. 

Their idea is the basis for modern spread-spectrum communication technology such as Bluetooth. 

(Source)