The movie star who helped invent Wi-Fi

One of Hollywood's most famous actresses patented, in 1942, an idea that makes Wi-Fi and Bluetooth work today.

Hedy Lamarr was not just a face for the posters: in her spare time she invented. Together with the composer George Antheil she devised a communication system that hopped from frequency to frequency so it could not be intercepted, designed to guide torpedoes without the enemy diverting them.

The military shelved it. Decades later, that "frequency hopping" became one of the foundations of the Wi-Fi, GPS and Bluetooth you carry in your pocket.