(1900-1958) Austrian-born Swiss physicist who originated the exclusion principle: in a given system no two fermions (electrons, protons, neutrons, or other elementary particles of half-integral spin) can be characterized by the same set of quantum numbers. He also predicted the existence of neutrinos. Nobel prize 1945.
The exclusion principle, announced 1925, involved adding a fourth quantum number to the three already used (n, l, and m). This number, s, would represent the spin of the electron and would have two possible values. The principle also gave a means of determining the arrangement of electrons into shells around the nucleus, which explained the classification of elements into related groups by their atomic number.
Pauli was born in Vienna and studied in Germany at Munich. He then went to Göttingen as an assistant to German physicist Max Born, moving on to Copenhagen to study with Danish physicist Niels Bohr. From 1928 Pauli was professor of Experimental Physics at the Eidgenössische Technische Hochschule, Zürich, though he spent World War II in the US at the Institute for Advanced Study, Princeton.
The neutrino was proposed in 1930 to explain the production of beta radiation in a continuous spectrum; it was eventually detected 1956.