I read this on Wikipedia via a message board talking about a top 10 geek girl article. Someone was asking why Hedy wasn't on the list. I nearly fell off my chair after learning this:
Hedy Lamarr and composer George Antheil received U.S. patent #2,292,387 for their Secret Communication System. This early version of frequency hopping used a piano roll to change between 88 frequencies and was intended to make radio-guided torpedoes harder for enemies to detect or jam. The patent was little-known until recently because Lamarr applied for it under her then-married name of Hedy Kiesler Markey... Lamarr's frequency-hopping idea served as the basis for modern spread-spectrum communication technology used in devices ranging from cordless telephones to WiFi Internet connections...
So you want to get negative?
6 hours ago