Part of Einstein’s charm was his disheveled look. In addition to his uncombed hair, one of Einstein’s peculiar habits was to never wear socks. To Einstein, socks were a pain because they often would get holes in them.

Einstein himself did not create the atomic bomb or even work on the Manhattan Project (he was denied the security clearance by the U.S. Army, which looked askance at his left-leaning politics). But both Einstein’s letters to then-U.S. President Franklin D. Roosevelt outlining the theory of a uranium fission bomb and his famous formula, E=mc², linking mass and energy, helped spur the development of nuclear weapons. Einstein later regretted his involvement, telling Newsweek that “had I known that the Germans would not succeed in developing an atomic bomb, I would have done nothing.”

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