Niels Bohr

Niels Bohr proposed in 1913 the model of the atom in which electrons occupy fixed orbits and jump between them, married Planck’s quantum to Rutherford’s nucleus, and made Copenhagen the capital of the new physics, where Heisenberg, Pauli and Dirac worked out quantum mechanics under his questioning. His principle of complementarity, that wave and particle are two descriptions neither of which is complete, is the philosophy of that physics, and Atomic Theory and the Description of Nature collects the essays that state it. He fled the Nazis in a fishing boat, worked on the bomb, and campaigned afterward for an open world.