Tjalling Koopmans

It’s the birthday of Tjalling Koopmans, who was born in 1910 in ‘s-Graveland, the Netherlands. Koopmans studied at Leiden University, where his initial field was theoretical physics. In 1934 he published what became known as Koopmans’ theorem, which equates the first ionization energy of a molecule to the energy of the molecule’s highest occupied orbital. By the time Koopmans undertook his PhD, he had switched to economics. After moving to Washington DC in 1940, he worked on the efficient distribution of resources, a vital problem during wartime. Koopman’s theoretical analyses proved influential and important. In 1976 he was awarded the Nobel Memorial Prize in Economic Sciences. Relating his first and second fields, Koopmans wrote in 1949: “While it was long possible and sometimes tempting for physicists to deny the usefulness of the molecular hypothesis, we economists have the good luck of being some of the ‘molecules’ of economic life ourselves, and of having the possibility through human contacts to study the behavior of other ‘molecules.’”

Date in History: 28 August 1910