Did a Hollywood star really help invent the idea behind Wi-Fi?

Partly, yes, though the popular version is exaggerated. During World War II the film star Hedy Lamarr and the composer George Antheil patented a radio system that hopped between frequencies so enemies could not jam it. That idea, frequency hopping, is related to the spread-spectrum techniques later used by Bluetooth and early Wi-Fi. But Lamarr did not invent Wi-Fi, and frequency hopping existed before her.

The trick is simple to picture. Instead of broadcasting on one radio frequency, the transmitter keeps jumping between many, following a code that only the receiver also knows. Anyone trying to jam or eavesdrop does not know where the signal will be next. Interference on one frequency only spoils a brief moment of the message.

Lamarr, promoted by her studio as the world's most beautiful woman, was a self-taught inventor who sketched ideas on set between takes. At arms-deal meetings with her first husband, she learned that navies wanted to guide torpedoes by radio, and that an enemy could jam them. Antheil had once synchronized four player pianos using matching paper rolls. Together they realized the same mechanism could keep a transmitter and receiver hopping in step. Their 1942 patent used a piano roll to switch among 88 frequencies, as many as the keys on a modern piano.

The US Navy rejected it as too bulky for a torpedo and suggested Lamarr sell war bonds instead. Similar systems only went into service in 1962. Recognition came late: in 2014 she was inducted into the National Inventors Hall of Fame.