Niels Bohr had insisted in 1939 that U235 could be separated from U238 only by turning the country into a gigantic factory. “Years later,” writes Edward Teller, “when Bohr came to Los Alamos, I was prepared to say, ‘You see . . .’ But before I could open my mouth, he said, ‘You see, I told you it couldn’t be done without turning the whole country into a factory. You have done just that.’ ”
