While in Melle, Marcel Brillouin read his grandfather's philosophy books. When France surrendered to Prussia in early 1871 the war was over and peace was finalised at the Treaty of Frankfurt on 10 May 1871. Brillouin was able to return to Paris in 1872 and, having spent the intervening time well, excelled at his studies. He entered the École Normale Supérieure in 1874 graduating in 1878.
Brillouin was a physics assistant at the Collège de France while he worked for his doctorate in mathematics and physics which was awarded in 1881. He then held posts as assistant professor of physics at Nancy, Dijon and Toulouse before returning to Paris to the École Normale Supérieure in 1888.
From 1900 to 1931 Brillouin was Professor of Mathematical Physics at the Collège de France. He was elected to the Académie des Sciences in 1921.
Brillouin wrote over 200 papers on theory and experiment. The topics Brillouin wrote on were the kinetic theory of gases, viscosity, thermodynamics, melting conditions and electricity. Around 1900 he built a new model of the Eötvös balance. He wrote on Helmholtz flow and the stability of aircraft.
An early worker on atomic structure he studied the Bohr model of the atom. His results here were used by de Broglie and Schrödinger. Another topic which he worked on was the theory of the tides, a topic which he began to work on around 1925.
In  Brillouin is described as follows:-
The interests of this wide-ranging, open minded scientist extended from history of science to the physics of the earth and the atom.Brillouin was friends with most of the top scientists of his day. In particular he was friends with Lord Kelvin (William Thomson), Lorentz, Planck and Sommerfeld. His son was the physicist Léon Brillouin (1889-1969) after whom the Brillouin zones of solid state physics are named.
Article by: J J O'Connor and E F Robertson