Enrico Fermi Born: Architect of the Nuclear Age

Enrico Fermi built the world's first nuclear reactor under the stands of an abandoned football stadium in Chicago. Squash courts, actually. On December 2, 1942, with no remote controls, no radiation shielding to speak of, and only cadmium-coated control rods standing between a controlled chain reaction and an uncontrolled one, Fermi gave the order and Chicago Pile-1 went critical. Nobody had told the city. The reaction was self-sustaining for 28 minutes before Fermi ordered the rods reinserted. Born in Rome on September 29, 1901, Fermi showed exceptional mathematical talent from childhood. He earned his doctorate in physics at 21 and became a full professor at the University of Rome at 26. In the 1930s, he conducted pioneering experiments on neutron bombardment, discovering that slowing neutrons down with a moderator made them more effective at splitting atomic nuclei. This discovery was the theoretical key to the nuclear chain reaction. He left Italy in 1938 when Mussolini's government enacted racial laws targeting Jews. His wife, Laura Capon, was Jewish. The family used the Nobel Prize ceremony in Stockholm as a one-way exit: they traveled to Sweden for the award, then went directly to New York instead of returning to Rome. At the University of Chicago, Fermi led the team that designed and built Chicago Pile-1, a lattice of uranium and graphite blocks stacked in layers. The experiment proved that a sustained, controlled nuclear chain reaction was possible, the fundamental prerequisite for both nuclear power and nuclear weapons. He joined the Manhattan Project at Los Alamos, where he calculated bomb yields on a slide rule. At the Trinity test on July 16, 1945, he dropped pieces of paper during the blast wave and estimated the yield from how far they blew, arriving at a figure close to the instrument readings. His students called him "The Pope" because his pronouncements on physics were always right. He was equally skilled as a theorist and an experimentalist, a combination so rare that it defined a category: Fermi problems, back-of-the-envelope calculations that produce surprisingly accurate estimates from minimal data. He died of stomach cancer on November 28, 1954, at 53. The element fermium was named after him.