In the fall of 1945, the U.S. Army completed its work on ENIAC, the world's first vacuum-tube computer. All told, ENIAC weighed more than 30 tons (27 metric tons), had the footprint of a small house and cost nearly half a million dollars to create [source: Weik]. Fortunately, by the time ENIAC was built, Bell Laboratories was already well on its way to developing a replacement for power-hungry, space-consuming vacuum tubes: the transistor. Transistors act as both an amplifier and a switch for electronic signals, functions essential to virtually all modern electronic equipment, and without quantum mechanics, they likely wouldn't exist.
That's because transistors rely on the unique properties of semiconductors -- materials that can act as either a conductor or an insulator -- to operate. Thanks to groundbreaking discoveries in quantum mechanics, Stanford researcher Eugene Wigner and his student, Frederick Seitz, were the first to manipulate the properties of semiconductors in the 1930s. Armed with their research, scientists from Bell Laboratories developed the first rudimentary transistors over the next decade, and by 1954, the United States military had constructed TRIDAC, the first transistor-based computer. Unlike the monstrous, unreliable vacuum-tube computers that preceded it, TRIDAC occupied only 3 cubic feet (0.08 cubic meters) and needed only 100 watts of power to operate [source: PBS]. Today, companies like Intel and AMD fabricate cutting-edge microprocessors containing billions of microprocessors, and we have quantum mechanics to thank.
