In the Golden Age of cinema, Hedy Lamarr was revered as “the most beautiful woman in the world” but the dazzling actress was also an inventor who would change the future of telecommunications. During World War II, Hedy Lamarr and the avant-garde composer, George Antheil, developed a frequency-hopping mechanism which contributed to the development of spread-spectrum communication technology now used in WiFi, Bluetooth, and GPS. But, how and why did a Hollywood star and a film composer invent a new method of secret communication?
Hedy was passionate about both acting and inventing, but it was on the silver screen that she found her first success. She appeared in her first film at the age of 15 and was a rather risqué star of German cinema at the age of 18. She soon married her first husband, Fritz Mandl, who was a leading Austrian arms dealer, with close links to various fascist regimes. During their marriage in the 1930s, Hedy acquired a great deal of knowledge about munitions and torpedoes by listening to dinner conversations between her husband and his business associates. ‘Fascist arms dealer’ doesn’t sound like the makings of a dream husband and indeed it wasn’t a particularly happy marriage, but these conversations would later inspire her greatest invention.
Hedy escaped her controlling spouse in 1937 and made her way to the USA where she worked for Metro-Goldwyn-Mayer studios. Between movies, Hedy spent much of her time inventing. One of her early (and less successful) projects was a cola-flavoured stock cube for homemade soft drinks, which I’m sure tasted better than it sounds. She had a room devoted to drafting designs for inventions and she turned down many invitations to Hollywood parties because she was too busy with her hobby. Chocolate fountains didn’t exist back then though, so she probably wasn’t missing much.
During World War II, Hedy turned her inventive mind towards helping her newly adopted country in the war effort. Hedy met George Antheil in the summer of 1940, and they discussed the problem of remote-controlled torpedoes being ‘jammed’ by the enemy. Radio signals from a plane or boat to a torpedo were transmitted at a fixed frequency. The enemy could transmit signals at the same frequency, which decreased the signal-to-noise ratio, effectively blocking the signal. This was known as radio ‘jamming’.
Hedy’s idea was to prevent enemy jamming by changing the frequency being used to transmit the radio signal to the torpedo during transmission. This is like the BBC broadcasting the start of a song on Radio 1, then playing the chorus on Radio 4, and the end on Radio 2. The person listening to the song has to change the channel to catch the song. She imagined a radio transmitter and receiver which were synchronised to change their tuning simultaneously, switching randomly between different frequencies. Precisely synchronising these changes in frequency was a difficult challenge.
Together Hedy and George developed a mechanism for synchronising the frequency-hopping between the torpedo receiver and the transmitter. George had worked extensively with self-playing pianos. These instruments had music recorded as holes in a roll of paper. The paper would scroll down, not unlike Guitar Hero, and air blowing through a hole led to the striking of the corresponding note. The pair used a similar mechanism, designing two identical ribbons of information, one in the torpedo and one in the transmitter, which would encode the frequency of transmission. To start the two ribbons simultaneously upon release of the torpedo, they used electromagnets to hold the starting pins in position on springs. Both electromagnets were connected in a circuit to the same battery, so when the torpedo launched, the circuit broke and the pins were released in sync. To further confound the enemy, Hedy and George included seven transmitting channels in their design with three of these sending false signals.
In December of 1940, Hedy and George took their ‘Secret Communication System’ to the National Inventors Council, an organisation established to identify inventions with possible military use. Hedy and George’s submission was warmly received and it was soon sent on to the U.S. Navy. They submitted their idea to the U.S. Patent Office and in 1942 the pair were awarded U.S. Patent 2,292,387.
The Navy rejected the idea during the war, saying the device was “too bulky to be incorporated in the average torpedo” – the piano metaphor seemed to confuse them! However, they kept the invention classified as secret. The patent was rediscovered in the 1950s when companies were developing non-frequency-hopping spread-spectrum, and it was finally implemented in the 1960s.
Along with other inventors, Hedy Lamarr and George Antheil laid the groundwork for modern spread-spectrum technologies. In the 1990s the two inventors were finally recognised for their achievement, receiving the Electronic Frontier Foundation Pioneers Award, and, in 2014, Hedy and George were inducted into the National Inventors Hall of Fame. If you’re feeling really inspired you can visit the National Inventors Hall of Fame in Alexandria, VA on the U.S. Patent and Trademark Office campus, they’ve even got a gift shop!
Hedy famously said, “Any girl can look glamorous. All you have to do is stand still and look stupid.” This cutting remark might reveal that Hedy was frustrated that her intellect was so often underestimated because of her looks, something that still happens to women today. But Hedy showed everyone that you can have brains and beauty!
Thanks to @KHerpoldt for suggesting Hedy Lamarr. Who would you like the next ‘Women in Science’ post to be about? Leave a comment or tweet @labcoatlucy
‘Hedy’s Folly: The Life and Breakthrough Inventions of Hedy Lemarr, the Most Beautiful Woman in the World’ by Pulitzer prize-winner Richard Rhodes.
‘Hedy Lamarr: The Most Beautiful Woman in Film’ by Ruth Barton.
‘Beautiful: The Life of Hedy Lamarr’ by Stephen Shearer.