Hendrik Casimir (born 15.07.1909) is a Dutch physicist and a member of the Royal Netherlands Academy of Arts and Sciences (1946) and its president (1973). He was born in The Hague. He graduated from the University of Leiden (1931). He worked in Copenhagen under N. Bohr and in Zurich under W. Pauli, and in 1933-42 at the University of Leiden. In 1942-72 he worked in the research laboratories of Philips Gloeilampenfabrieken in Eindhoven (director in 1946).
His work was in the field of quantum mechanics, nuclear physics, low-temperature physics, superconductivity, thermodynamics, magnetism and applied mathematics. In 1934, together with C. Gorter, he developed a phenomenological theory of superconductivity (the Casimir — Gorter model). In 1936 he constructed a quantum theory of the interaction of the nucleus with electric and magnetic fields in atoms and molecules, and in 1942 he developed a detailed theory of magnetic octupole interactions. Together with du Pré he introduced (1938) the concept of spin temperature, separating the spin degrees of freedom into a distinct thermodynamic subsystem.
A member of a number of academies of sciences and scientific societies. In 1972 —75 he was president of the European Physical Society.