(1892-1987) French Theoretical Physicist
Louis-Victor-Pierre-Raymond de Broglie’s significance in the development of human understanding of reality cannot be overstated. Physicists acknowledge him as the father of wave mechanics. De Broglie was the first to apply the notion of the dual nature of particle properties and wave properties to matter. At the time experiments showed that both properties applied to light, but it was a vast leap to posit that matter can behave in two different ways. The wave properties of matter apply at the subatomic level, invisible to the eye, so this duality of matter is not apparent. However, the fact that particle properties and wave properties do not always coincide opens the door to the possibility of randomness and unpredictability in matter, a proposition that disturbed de Broglie himself, though he could not find a scientific solution to this conundrum.
De Broglie was born on August 15, 1892, in Dieppe, France. His father, who died when de Broglie was 14, was Due Victor, and his mother was Pauline d’Armaille. The family carried two titles of distinction—in 1740 Louis XIV granted the title of due to the family and in the Seven Years War the family earned the title of prinz from the Holy Roman Empire. De Broglie inherited both titles in 1960, when his older brother and scientific collaborator, Maurice, died.
After the traditional familial education de Broglie matriculated at the Sorbonne, where he earned dual baccalaureates in philosophy and mathematics in 1909. He then earned his Licencie es Sciences from the Faculty of Science at the University of Paris in 1913. He spent the entirety of World War I in the military as a radio operator at the Eiffel Tower. After the war he resumed his scientific research, focusing his doctoral investigation on the question of whether matter might exhibit the same dual properties of waves and particles that light exhibits. De Broglie presented his dissertation, “Investigations into the Quantum Theory,” to an advisory committee befuddled by the complexity of the theory. On their advice he sent a copy to ALBERT EINSTEIN, who recognized that de Broglie’s theory solved one of the basic mysteries of science. The journal Annales de Physique published the paper in its entirety in 1925.
Proof of the theory’s validity came from two fronts. Clinton Davisson and Lester Germer located what became known as de Broglie waves by using slow electrons, and George Paget Thomson did the same with fast electrons in 1927. ERWIN SCHRODINGER proceeded to formulate the mathematical function known as the Schrodinger equation by which these properties worked, thus helping to establish quantum mechanics. In 1927 de Broglie attended the seventh Solvay conference, where prominent physicists took up the question posed by his theory—Is there determinacy in quantum mechanics? De Broglie defended the position that there must be some organizing principle behind quantum mechanics, proposing his “double solution” of a “pilot wave” as an answer. Further investigation revealed holes in this solution, leaving no option but to accept the random nature of the probabilistic theory.
The Faculty of Science at the University of Paris appointed de Broglie as a professor of theoretical physics in 1928, and in 1933 a special chair in theoretical physics was created for him at the Henri Poincare Institute. He won the 1929 Nobel Prize in physics. Subsequently many distinguished societies included him in their membership, including the Academy of Sciences in 1933, the Academie Francaise in 1944, the National Academy in the United States in 1947, and the Royal Society of London in 1953. De Broglie died of natural causes on March 19, 1987.
