Pauli, Wolfgang (1900-1958)

Wolfgang Pauli was one of the twentieth century's most brilliant theoretical physicists. Born in Vienna, he studied at Munich University under the physicist Arnold Sommerfeld where he produced, at the age of 20, a comprehensive review of relativity that even Einstein admired. In the 1920s observations of the fine structure in certain spectra suggested that the quantum model of atoms developed by Bohr and Sommerfeld (in which electron states were described by three quantum numbers) might be incorrect. Pauli explained that these observations could be attributed to a fourth quantum number representing the spin (i.e. intrinsic angular momentum) of the electron. He also proposed in 1925 that no two electrons in the same atom can have the same values for their four quantum numbers this is know known as the Pauli exclusion principle and is one of the cornerstones of atomic science (its discovery won him the Nobel Prize for Physics in 1945). In 1928 Pauli moved to Zurich and began studying radioactive beta-decay in 1931. The production of this emitted beta-radiation in a continuous spectrum seemed to defy the law of conservation of energy. Pauli proposed that energy could be conserved if the missing energy were transferred to a particle with no mass or charge this particle had not been observed at that time. This view was supported by Enrico Fermi in 1934 who named the particle the neutrino (Italian for 'little neutron'); it was discovered in 1956. Pauli was noted among physicists as a severe and sometimes cruel critic of theories that were not, in his view, rigorous. As he said towards the end of his life 'I was nasty'.