Niels Bohr Dies: Father of Quantum Theory Passes

Niels Bohr escaped Nazi-occupied Denmark in a fishing boat on the night of September 29, 1943, crossing the Oresund strait to Sweden. From there, he was flown to Britain in a de Havilland Mosquito bomber. The flight nearly killed him: the aircraft was unpressurized, and at high altitude the oxygen mask failed. He lost consciousness. The pilot descended, and Bohr survived. He was 58 years old, a Nobel laureate, and about to become a secret advisor to the Manhattan Project. Born in Copenhagen on October 7, 1885, Bohr had revolutionized physics before he turned thirty. His 1913 model of the atom, which proposed that electrons occupy only specific energy levels and emit light when jumping between them, was the first successful application of quantum theory to atomic structure. He won the Nobel Prize in Physics in 1922. He founded the Institute for Theoretical Physics in Copenhagen in 1921, which became the intellectual capital of quantum mechanics. Heisenberg, Pauli, Dirac, and scores of other physicists worked there. The Copenhagen interpretation of quantum mechanics, which holds that a quantum system exists in a superposition of states until observed, emerged from discussions at the institute. Einstein spent years arguing against it. Bohr spent years arguing back. When the Nazis occupied Denmark in 1940, Bohr initially remained in Copenhagen, using his international reputation to protect Jewish scientists and colleagues. By September 1943, with the Germans planning to deport Denmark's Jewish population, he was warned that his arrest was imminent. The Danish resistance smuggled him out. In the United States, he advised the Manhattan Project under the alias Nicholas Baker. He contributed to the bomb's development but spent much of his time thinking about what would happen after it was used. He argued passionately for international control of nuclear energy and for sharing nuclear information with the Soviet Union to prevent an arms race. Churchill considered the idea dangerous. Roosevelt listened politely and did nothing. He returned to Copenhagen after the war and spent the rest of his life working on nuclear physics and advocating for peaceful uses of atomic energy. He died on November 18, 1962, at 77.