who started his career as a philosopher but turned to physics in 1925. Together with Walter Heitler (1904–81), London showed in a classic, fundamental paper (1927) that the then very new quantum mechanics could explain the existence of the chemical bond. London subsequently showed that chemical reactions can be understood in terms of potential-energy surfaces, applied group theory to quantum chemistry, and derived the London formula. In 1938 he showed that the superfluidity of liquid helium could be explained in terms of a Bose–Einstein condensate. In his later years he made important contributions towards an understanding of superconductivity.