(Prince) Louis de Broglie (1892-1987), the French theoretical physicist. He took a doctorate at the Sorbonne and taught there, as the professor of theoretical physics at the newly founded Henri Poincaire Institute (1928-1968). He established that all subatomic particles can be described by either particle equations or by wave equations, thus laying the foundation of wave mechanics. In 1927 his theory was proved experimentally with the measurement of the wavelength of the electron. This wave-particle duality was used by Schrodinger in his formulation of quantum mechanics. In 1929 de Broglie received the Nobel prize for physics.