Hedy Lamarr co-invented frequency hopping technology, which is the basis for modern communication systems like Wi-Fi, Bluetooth, and GPS. This invention was initially developed during World War II to help guide torpedoes and prevent enemy jamming.
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Mathematician Emma Noether’s theorem describes the relation between the symmetries of a physical system and its conservation laws (e.g., conservation of energy). This is one of the most important theoretical bases of modern physics.
On a more concrete level, Stephanie Kwolek invented Kevlar while at DuPont.