**Louis de Broglie** was a French mathematician best known for his description of the dual particle-wave properties of the electron.

- Louis studied at the Lycée Janson de Sailly in Paris completing his secondary school education in 1909.
- At the age of 18 he graduated with an arts degree but he was already becoming interested in mathematics and physics.
- After being assigned a research topic in history he chose, after worrying greatly about the decision, to study for a degree in theoretical physics.
- During the War de Broglie served in the army.
- Taking up research in mathematical physics, de Broglie nevertheless maintained an interest in experimental physics.
- De Broglie's doctoral thesis Recherches sur la théorie des quanta Ⓣ(Researches on the quantum theory) of 1924 put forward this theory of electron waves, based on the work of Einstein and Planck.
- the physics of matter, based on the concepts of particles and atoms which were supposed to obey the laws of classical Newtonian mechanics, and the physics of radiation, based on the idea of wave propagation in a hypothetical continuous medium, the luminous and electromagnetic ether.
- But these two systems of physics could not remain detached from each other: they had to be united by the formulation of a theory of exchanges of energy between matter and radiation.
- The success of Planck's ideas has been accompanied by serious consequences.
- De Broglie's theory of electron matter waves was later used by Schrödinger, Dirac and others to develop wave mechanics.
- After his doctorate, de Broglie remained at the Sorbonne where he taught for two years, becoming professor of theoretical physics at the Henri Poincaré Institute in 1928.
- From 1932 he was also professor of theoretical physics at the Faculté des Sciences at the Sorbonne.
- De Broglie taught there until he retired in 1962.
- From 1944 he was a member of the Bureau des Longitudes.
- His greatest honour was being awarded the Nobel Prize in 1929.
- But corpuscles and waves cannot be independent, since, according to Bohr, they are complementary to each other; consequently it must be possible to establish a certain parallelism between the motion of a corpuscle and the propagation of the wave which is associated with it.
- After receiving the Nobel Prize in 1929 De Broglie worked on extensions of wave mechanics.
- He wrote at least twenty-five books including Ondes et mouvements Ⓣ(Waves and motions) (1926), La mécanique ondulatoire Ⓣ(Wave mechanics) (1928), Une tentative d'interprétation causale et non linéaire de la mécanique ondulatoire: la théorie de la double solution Ⓣ(An causal interpretation of nonlinear wave mechanics: the theory of the double solution) (1956), Introduction à la nouvelle théorie des particules de M Jean-Pierre Vigier et de ses collaborateurs Ⓣ(Introduction to the new theory of particle of Jean-Pierre Vigier and his collaborators) (1961), Étude critique des bases de l'interprétation actuelle de la mécanique ondulatoire Ⓣ(Critical study of the bases of the current interpretation of wave mechanics) (1963).
- He wrote many popular works which demonstrate his interest in the philosophical implications of modern physics, including Matter and Light: The New Physics (1939); The Revolution in Physics (1953); Physics and Microphysics (1960); and New Perspectives in Physics (1962).
- In 1933 de Broglie was elected to the Académie des Sciences becoming Permanent Secretary for the mathematical sciences in 1942.
- Other honours which he received included the Kalinga Prize which was awarded to him by UNESCO in 1952 for his efforts towards the understanding of modern physics by the general public.
- The French National Scientific Research Centre awarded him its gold medal in 1956.
- Further honours included the awarding of the Grand Cross of the Légion d'Honneur and Belgium made him an Officer of the Order of Leopold.
- He was elected to honorary membership of eighteen academies and learned societies in Europe, India, and the United States.
- The central question in de Broglie's life was whether the statistical nature of atomic physics reflects an ignorance of the underlying theory or whether statistics is all that can be known.
- For most of his life he believed the former although as a young researcher he had at first believed that the statistics hide our ignorance.
- the statistical theories hide a completely determined and ascertainable reality behind variables which elude our experimental techniques.

Born 15 August 1892, Dieppe, France. Died 19 March 1987, Paris, France.

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Prize Nobel, Physics

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive