Niels Bohr Timeline

Martin Knudsen put Bohr's name forward for a docentship, which was approved in July 1913, and Bohr then began teaching medical students.

The First World War broke out while Bohr was in Tyrol, complicating his voyage with Margrethe to England, where he arrived in October 1914. They stayed until July 1916.

By July 1916 Bohr had been appointed to the Chair of Theoretical Physics at the University of Copenhagen, a position created especially for him.

Image source: University of Copenhagen

In April 1917, Bohr began a campaign to establish an Institute of Theoretical Physics, and legislation establishing the institute was passed in November 1918.

Image source: Niels Bohr Institute

By 1919, Bohr was moving away from the idea that electrons orbited the nucleus and developed heuristics to describe their behavior instead.

Image source: Old quantum theory

The Institute of Theoretical Physics at the University of Copenhagen opened on 3 March 1921, with Bohr as its director. It is now known as the Niels Bohr Institute.

The Bohr Festival was a series of seven lectures given by Bohr from 12 to 22 June 1922 at the Institute of Theoretical Physics in Göttingen.

Image source: Niels Bohr

The discovery of Compton scattering by Arthur Holly Compton in 1923 convinced most physicists that light was composed of photons and that energy and momentum were conserved in collisions between electrons and photons.

Image source: Compton scattering

An important development came in 1924 with Wolfgang Pauli's discovery of the exclusion principle, which put Bohr's models on a firm theoretical footing.

Image source: Pauli exclusion principle

Heisenberg first came to Copenhagen in 1924, developed the mathematical foundations of quantum mechanics after returning to Göttingen in June 1925, and worked in Copenhagen as lecturer and assistant to Bohr from 1926 to 1927, taking Kramers's place when Kramers left for Utrecht in 1926.

Image source: Werner Heisenberg

The introduction of spin by George Uhlenbeck and Samuel Goudsmit in November 1925 was a milestone in the development of quantum theory.

Image source: Spin (physics)

British physicist Paul Dirac came to Copenhagen for six months beginning in September 1926, attracted by the new quantum mechanics. Austrian physicist Erwin Schrödinger also visited in 1926.

Image source: Paul Dirac

In February 1927, Heisenberg developed the uncertainty principle. In September 1927, at the Como Conference, Bohr emphasised that Heisenberg's uncertainty relations could be derived from classical considerations about optical resolving power, part of his complementarity framework after experiments confirmed wave behavior of matter.

Image source: Uncertainty principle

In 1933, the Rockefeller Foundation created a fund to help support refugee academics, and Bohr discussed this programme with its president, Max Mason, in May 1933 during a visit to the United States.

Image source: Rockefeller Foundation

Prompted by beta decay puzzles and the 1932 discovery of the neutron, Bohr created a new theory of the compound nucleus in 1936 explaining how neutrons could be captured by the nucleus, working with collaborator Fritz Kalckar, who died suddenly in 1938.

Image source: Nuclear reaction

After Otto Hahn's December 1938 discovery of nuclear fission and Lise Meitner's explanation, Bohr brought the news to the United States, opening the fifth Washington Conference on Theoretical Physics with Fermi on 26 January 1939. With Wheeler, he published "The Mechanism of Nuclear Fission" in September 1939.

Image source: Nuclear fission

After long debate, Bohr pledged his support to CERN in February 1952, and Geneva was chosen as the site in October. The CERN Theory Group was based in Copenhagen until new accommodation in Geneva was ready in 1957.

Image source: CERN

Bohr served as first chairman of the Research Establishment Risø of the Danish Atomic Energy Commission from February 1956, and became the first chairman of the Nordic Institute for Theoretical Physics (Nordita) in 1957.