art & culture
1935-39 Frank Lloyd Wright Fallingwater

Douglas DC-3
Douglas DC-3

Blick aus Rot
1937 Paul Klee Blick aus Rot

Dive Bomber with Tank
1940 -- Jose Clemente Orozco -- Dive Bomber with Tank

  Physics in World War II

1937 Lester Beall Wash Day Throughout the nineteen thirties, while America struggled with the Great Depression and Adolf Hitler's Nazis rose to absolute power in Germany, physicists quietly continued to collaborate across national boundaries. Quantum mechanics proved to be a reliable framework for the study of solid matter, of molecules, and of atoms. The discovery of the neutron and the invention of particle accelerators launched the new science of nuclear physics. Although the size of the nucleus is 100,000 times smaller than that of an atom, and its internal energy higher by the same factor, quantum mechanics continued to work perfectly. The future of physics looked promising. But in 1939, World War II broke out and swept the whole world, including the physics community, into its wake. Physicists and engineers helped to win the air-borne Battle of Britain by developing Radar, and their German counterparts designed the V-2 rockets that terrorized London. Of greater historical significance, though, was the construction of the atomic bomb.

As soon as nuclear fission was discovered in Europe, it became apparent that if a way could be found to release its energy in a bomb, the course of the war would be altered. In America a number of physicists, many of European origin, worried that Hitler might acquire such a weapon and persuaded the normally pacifistic Albert Einstein to warn President Franklin D. Roosevelt. In an urgent letter dated August 2, 1939, he explained the danger by writing: "It is conceivable ... that extremely powerful bombs of a new type may thus be constructed." Einstein's letter did not have an immediate effect, but eventually helped to persuade the United States to begin the monumental task of building an atom bomb.

Robert Oppenheimer The man chosen to direct the project was the theoretical physicist Robert Oppenheimer (right). Although he had no industrial or even experimental experience, he proved to be a remarkably effective leader. His team on a remote mesa in New Mexico, and smaller groups in other secret laboratories, included most of the nation's best physicists. By the force of his towering intellect Oppenheimer managed to unite this diverse group in a common effort to design and build a bomb, and to test it successfully in July 1945. By then, Germany had already surrendered, but its ally Japan was still at war.

In August 1945, two atomic bombs dropped on the Japanese cities of Hiroshima and Nagasaki contributed to a quick end of World War II. Their chief legacy, however, was to be felt for a long time. For almost half a century the Cold War's nuclear stand-off between the United States and the Soviet Union held the world in its grip.

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