Niels Bohr

Origins and early life

Niels Henrik David Bohr was born in Copenhagen on 7 October 1885, the son of Christian Bohr, a professor of physiology, and of Ellen Adler, the daughter of the Danish Jewish banker David Baruch Adler.

Work and career

His father was a Lutheran and Niels was baptised, then left the Church of Denmark in 1912 and thought of himself as a free thinker; his place in this directory rests on descent, through his Jewish mother. He took his master's degree in 1909 and his doctorate in 1911 in Copenhagen, then went to England, first to Cambridge and then to Ernest Rutherford's laboratory in Manchester. In three papers published in 1913 he joined Rutherford's nuclear atom to Max Planck's quantum theory: electrons move only in fixed orbits, and when one drops to a lower orbit the difference in energy leaves as light of a fixed wavelength.

Professor of theoretical physics in Copenhagen from 1916, he headed until his death the Institute for Theoretical Physics founded for him there, now the Niels Bohr Institute, which became a centre of quantum physics. He received the Nobel Prize in Physics for 1922, alone, for his services in the investigation of the structure of atoms and of the radiation emanating from them. From 1933 he gave scholars driven out by the Nazis temporary posts at his institute, found them fellowships and then places at institutions around the world.

In September 1943, warned that the Nazis counted his family as Jewish because his mother had been Jewish, he escaped by sea to Sweden with the Danish resistance and persuaded King Gustaf V to make public that Sweden would shelter Jewish refugees. He spent the rest of the war in Britain and the United States with the atomic project, then called for openness between nations, in an open letter to the United Nations of 9 June 1950. He died of heart failure at his home in Copenhagen on 18 November 1962, at the age of seventy-seven.