Did Hedy Lamarr really invent something important?
Yes. She co-patented a frequency-hopping system for torpedo guidance that anticipated techniques underlying modern wireless communication — and the popular framing that she "invented Wi-Fi" overstates a genuine and substantial contribution.
Her background. Born in Vienna in 1914, she became a film star in Europe and then in Hollywood. She had no formal engineering training, and had acquired considerable technical knowledge partly through her first marriage to an Austrian arms manufacturer, whose business discussions about weapons systems she attended.
The invention. Working with composer George Antheil during the Second World War, she addressed a specific problem: radio-guided torpedoes could be jammed by broadcasting interference on the control frequency.
The solution was to have transmitter and receiver change frequency rapidly and in synchrony, following a shared sequence. An enemy could not jam the signal without jamming the entire band, because the signal is never on one frequency long enough to be targeted.
Antheil's contribution was the synchronisation mechanism, using a design based on player piano rolls — he had previously composed for synchronised player pianos, which is how the collaboration made sense.
They were granted a patent in 1942 and assigned it to the US Navy, which did not implement it during the war.
What it actually led to. Frequency hopping spread spectrum became important in secure military communication and later in commercial wireless. Spread spectrum techniques are foundational to Bluetooth, to some Wi-Fi implementations and to mobile telephony.
The honest assessment. The patent was not directly implemented in later systems, and frequency-hopping ideas had appeared earlier in other contexts. The claim that modern wireless derives directly from their patent is too strong. What is fair is that they independently developed and patented a genuine and non-obvious application of an important principle, well ahead of its practical use.
Her recognition came very late. She received awards in the 1990s, shortly before her death in 2000, and was inducted into the National Inventors Hall of Fame posthumously.
She reportedly found being valued for her appearance frustrating, and her inventive work went essentially unacknowledged for most of her life.