Fritz London (7.03.1900-30.03.1954) was a theoretical physicist. He was born in Breslau (now Wrocław, the Polish People's Republic). He was the brother of H. London. He graduated from the University of Munich (1921). In 1928-33 he worked at the University of Berlin, in 1933—36 at Oxford, and in 1936—38 at the Poincaré Institute (Paris). From 1939 he was professor at the university in Durham (USA).
His research concerned spectroscopy, quantum mechanics, low-temperature physics and the theory of superconductivity and of superfluidity in liquid helium, in particular the quantum theory of atomic and molecular forces and of chemical valence. In 1927, together with W. Heitler, he carried out the first approximate calculation of the hydrogen molecule, and so laid the foundations of quantum chemistry. In 1929 he developed the theory of the van der Waals forces of attraction between molecules. In 1935, together with H. London, he proposed a phenomenological theory of superconductivity to explain the electrodynamic properties of superconductors. He introduced (1935) the idea that the energy gap determines the superconducting properties of metals. He postulated the macroscopic coherence of the superconducting state for homogeneous superconductors. In 1950 he predicted the quantisation of magnetic flux. He introduced the concept of the depth of penetration of a field into a superconductor and derived an equation for it.