Shannon summarized his war work on secret communications in a 114-page opus, “A Mathematical Theory of Cryptography,” which he finished in 1945. The paper was immediately deemed classified and too sensitive for publication, but those who read it found a long treatise exploring the histories and methodologies of various secrecy systems. Moreover, he had offered … Read more

Semiconductors—as their name implies, neither conductors nor insulators—are a curious case. In their outer band, atoms that comprise these substances have somewhere between three and five electrons, and they seem to exhibit qualities that are different from those of either a conductor or an insulator. Early in the twentieth century, physicists noted that these materials … Read more

Contrary to its gentle image of later years, created largely through one of the great public relations machines in corporate history, Ma Bell in its first few decades was close to a public menace—a ruthless, rapacious, grasping “Bell Octopus,” as its enemies would describe it to the press. “The Bell Company has had a monopoly … Read more

Though Edison became rich and famous for his phonograph and his filament for the electric light bulb, some of his less heralded inventions were arguably as influential on the course of modern life. One of those was a new use for a compressed carbon “button,” which he discovered in 1877 could be placed inside the … Read more