Léon Brillouin
Encyclopedia
Léon Nicolas Brillouin was a French
physicist. He made contributions to quantum mechanics
, radio wave propagation in the atmosphere, solid state physics, and information theory
.
, near Paris, France. His father, Marcel Brillouin
, grandfather, Éleuthère Mascart
, and great-grandfather, Charles Briot, were physicists as well.
, in Paris. From 1911 he studied under Jean Perrin until he left for the Ludwig Maximilians University of Munich
(LMU), in 1912. At LMU, he studied theoretical physics with Arnold Sommerfeld
. Just a few months before Brillouin's arrival at LMU, Max von Laue
had conducted his experiment showing X-ray diffraction in a crystal lattice. In 1913, he went back to France to study at the University of Paris
and it was in this year that Niels Bohr
submitted his first paper on the Bohr model
of the hydrogen atom. From 1914 until 1919, during World War I, he served in the military. At the conclusion of the war, he returned to the University of Paris to continue his studies with Paul Langevin
, and was awarded his Docteur ès science in 1920. Brillouin's thesis jury was composed of Langevin, Marie Curie
, and Jean Perrin and his thesis topic was on the quantum theory
of solids. In his thesis, he proposed an equation of state based on the atomic vibrations (phonons) that propagate through it. He also studied the propagation of monochromatic light waves and their interaction with acoustic waves
, i.e., scattering of light with a frequency change, which became known as Brillouin scattering
.
. In 1926, Gregor Wentzel
, Hendrik Kramers
, and Brillouin independently developed what is known as the Wentzel–Kramers–Brillouin approximation
, also known as the WKB method, classical approach, and phase integral method. In 1928, after the l’Institut Henri Poincaré was established, he was appointed as professor to the Chair for Theoretical Physics. During his work on the propagation of electron waves in a crystal lattice, he introduced the concept of Brillouin zone
s in 1930. Quantum mechanical perturbations techniques by Brillouin and by Eugene Wigner resulted in what is known as the Brillouin–Wigner formula.
Since Brillouin's study with Sommerfeld, he was interested and did pioneering work in the diffraction of electromagnetic radiation in a dispersive media. As a specialist in radio wave propagation, Brillouin was appointed Director General of the French state-run agency, Radiodiffusion Nationale about a month before war with Germany, August 1939. In May 1940, upon the collapse of France, as part of the government, he retired to Vichy
. Six months later, he resigned and went to the United States.
Until 1942, Brillouin was a visiting professor at the University of Wisconsin–Madison
, and then he was a professor at Brown University
, in Providence, Rhode Island
, until 1943. For the next two years, he was a research scientist with the National Defense Research Committee
at Columbia University
, working in the field of RADAR
. From 1947 to 1949, he was professor of applied mathematics at Harvard University
. During the period 1952 to 1954, he was with IBM
Corporation in Poughkeepsie
, New York
, as well as a staff member of the IBM Watson Laboratory at Columbia University. In 1954, he became an adjunct professor at Columbia University. He lived in New York City until he died in 1969.
Brillouin was a founder of modern solid state physics for which he discovered, among other things, Brillouin zone
s. He applied information theory
to physics and the design of computers and coined the concept of negentropy
to demonstrate the similarity between entropy and information.
Brillouin offered a solution to the problem of Maxwell's demon
. In his book, Relativity Reexamined, he called for a "painful and complete re-appraisal" of relativity theory which "is now absolutely necessary."
French people
The French are a nation that share a common French culture and speak the French language as a mother tongue. Historically, the French population are descended from peoples of Celtic, Latin and Germanic origin, and are today a mixture of several ethnic groups...
physicist. He made contributions to quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...
, radio wave propagation in the atmosphere, solid state physics, and information theory
Information theory
Information theory is a branch of applied mathematics and electrical engineering involving the quantification of information. Information theory was developed by Claude E. Shannon to find fundamental limits on signal processing operations such as compressing data and on reliably storing and...
.
Early life
Brillouin was born in SèvresSèvres
Sèvres is a commune in the southwestern suburbs of Paris, France. It is located from the centre of Paris.The town is known for its porcelain manufacture, the Manufacture nationale de Sèvres, making the famous Sèvres porcelain, as well as being the location of the International Bureau of Weights...
, near Paris, France. His father, Marcel Brillouin
Marcel Brillouin
Louis "Marcel" Brillouin was a French physicist and mathematician.Born in Melle, Deux-Sèvres, France, his father was a painter who moved to Paris when Marcel was a boy. There he attended the Lycée Condorcet. The Brillouin family returned to Melle during the Franco-Prussian War of 1870 to escape...
, grandfather, Éleuthère Mascart
Éleuthère Mascart
Éleuthère Élie Nicolas Mascart was a noted French physicist, a researcher in optics and electricity.Mascart was born in Quarouble, Nord. He attended the École normale supérieure...
, and great-grandfather, Charles Briot, were physicists as well.
Education
From 1908 to 1912, Brillouin studied physics at the École Normale SupérieureÉcole Normale Supérieure
The École normale supérieure is one of the most prestigious French grandes écoles...
, in Paris. From 1911 he studied under Jean Perrin until he left for the Ludwig Maximilians University of Munich
Ludwig Maximilians University of Munich
The Ludwig Maximilian University of Munich , commonly known as the University of Munich or LMU, is a university in Munich, Germany...
(LMU), in 1912. At LMU, he studied theoretical physics with Arnold Sommerfeld
Arnold Sommerfeld
Arnold Johannes Wilhelm Sommerfeld was a German theoretical physicist who pioneered developments in atomic and quantum physics, and also educated and groomed a large number of students for the new era of theoretical physics...
. Just a few months before Brillouin's arrival at LMU, Max von Laue
Max von Laue
Max Theodor Felix von Laue was a German physicist who won the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals...
had conducted his experiment showing X-ray diffraction in a crystal lattice. In 1913, he went back to France to study at the University of Paris
University of Paris
The University of Paris was a university located in Paris, France and one of the earliest to be established in Europe. It was founded in the mid 12th century, and officially recognized as a university probably between 1160 and 1250...
and it was in this year that Niels Bohr
Niels Bohr
Niels Henrik David Bohr was a Danish physicist who made foundational contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922. Bohr mentored and collaborated with many of the top physicists of the century at his institute in...
submitted his first paper on the Bohr model
Bohr model
In atomic physics, the Bohr model, introduced by Niels Bohr in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system, but with electrostatic forces providing attraction,...
of the hydrogen atom. From 1914 until 1919, during World War I, he served in the military. At the conclusion of the war, he returned to the University of Paris to continue his studies with Paul Langevin
Paul Langevin
Paul Langevin was a prominent French physicist who developed Langevin dynamics and the Langevin equation. He was one of the founders of the Comité de vigilance des intellectuels antifascistes, an antifascist organization created in the wake of the 6 February 1934 far right riots...
, and was awarded his Docteur ès science in 1920. Brillouin's thesis jury was composed of Langevin, Marie Curie
Marie Curie
Marie Skłodowska-Curie was a physicist and chemist famous for her pioneering research on radioactivity. She was the first person honored with two Nobel Prizes—in physics and chemistry...
, and Jean Perrin and his thesis topic was on the quantum theory
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...
of solids. In his thesis, he proposed an equation of state based on the atomic vibrations (phonons) that propagate through it. He also studied the propagation of monochromatic light waves and their interaction with acoustic waves
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
, i.e., scattering of light with a frequency change, which became known as Brillouin scattering
Brillouin scattering
Brillouin scattering, named after Léon Brillouin, occurs when light in a medium interacts with time dependent optical density variations and changes its energy and path. The density variations may be due to acoustic modes, such as phonons, magnetic modes, such as magnons, or temperature gradients...
.
Career
After receipt of his doctorate, Brillouin became the scientific secretary of the reorganized Journal de Physique et le Radium. In 1923, he became associate director of the physics laboratories at the Collège de FranceCollège de France
The Collège de France is a higher education and research establishment located in Paris, France, in the 5th arrondissement, or Latin Quarter, across the street from the historical campus of La Sorbonne at the intersection of Rue Saint-Jacques and Rue des Écoles...
. In 1926, Gregor Wentzel
Gregor Wentzel
Gregor Wentzel was a German physicist known for development of quantum mechanics. Wentzel, Hendrik Kramers, and Léon Brillouin developed the Wentzel–Kramers–Brillouin approximation in 1926...
, Hendrik Kramers
Hendrik Anthony Kramers
Hendrik Anthony "Hans" Kramers was a Dutch physicist.-Background and education:...
, and Brillouin independently developed what is known as the Wentzel–Kramers–Brillouin approximation
WKB approximation
In mathematical physics, the WKB approximation or WKB method is a method for finding approximate solutions to linear partial differential equations with spatially varying coefficients...
, also known as the WKB method, classical approach, and phase integral method. In 1928, after the l’Institut Henri Poincaré was established, he was appointed as professor to the Chair for Theoretical Physics. During his work on the propagation of electron waves in a crystal lattice, he introduced the concept of Brillouin zone
Brillouin zone
In mathematics and solid state physics, the first Brillouin zone is a uniquely defined primitive cell in reciprocal space. The boundaries of this cell are given by planes related to points on the reciprocal lattice. It is found by the same method as for the Wigner–Seitz cell in the Bravais lattice...
s in 1930. Quantum mechanical perturbations techniques by Brillouin and by Eugene Wigner resulted in what is known as the Brillouin–Wigner formula.
Since Brillouin's study with Sommerfeld, he was interested and did pioneering work in the diffraction of electromagnetic radiation in a dispersive media. As a specialist in radio wave propagation, Brillouin was appointed Director General of the French state-run agency, Radiodiffusion Nationale about a month before war with Germany, August 1939. In May 1940, upon the collapse of France, as part of the government, he retired to Vichy
Vichy
Vichy is a commune in the department of Allier in Auvergne in central France. It belongs to the historic province of Bourbonnais.It is known as a spa and resort town and was the de facto capital of Vichy France during the World War II Nazi German occupation from 1940 to 1944.The town's inhabitants...
. Six months later, he resigned and went to the United States.
Until 1942, Brillouin was a visiting professor at the University of Wisconsin–Madison
University of Wisconsin–Madison
The University of Wisconsin–Madison is a public research university located in Madison, Wisconsin, United States. Founded in 1848, UW–Madison is the flagship campus of the University of Wisconsin System. It became a land-grant institution in 1866...
, and then he was a professor at Brown University
Brown University
Brown University is a private, Ivy League university located in Providence, Rhode Island, United States. Founded in 1764 prior to American independence from the British Empire as the College in the English Colony of Rhode Island and Providence Plantations early in the reign of King George III ,...
, in Providence, Rhode Island
Providence, Rhode Island
Providence is the capital and most populous city of Rhode Island and was one of the first cities established in the United States. Located in Providence County, it is the third largest city in the New England region...
, until 1943. For the next two years, he was a research scientist with the National Defense Research Committee
National Defense Research Committee
The National Defense Research Committee was an organization created "to coordinate, supervise, and conduct scientific research on the problems underlying the development, production, and use of mechanisms and devices of warfare" in the United States from June 27, 1940 until June 28, 1941...
at Columbia University
Columbia University
Columbia University in the City of New York is a private, Ivy League university in Manhattan, New York City. Columbia is the oldest institution of higher learning in the state of New York, the fifth oldest in the United States, and one of the country's nine Colonial Colleges founded before the...
, working in the field of RADAR
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
. From 1947 to 1949, he was professor of applied mathematics at Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
. During the period 1952 to 1954, he was with IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
Corporation in Poughkeepsie
Poughkeepsie (city), New York
Poughkeepsie is a city in the state of New York, United States, which serves as the county seat of Dutchess County. Poughkeepsie is located in the Hudson River Valley midway between New York City and Albany...
, New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
, as well as a staff member of the IBM Watson Laboratory at Columbia University. In 1954, he became an adjunct professor at Columbia University. He lived in New York City until he died in 1969.
Brillouin was a founder of modern solid state physics for which he discovered, among other things, Brillouin zone
Brillouin zone
In mathematics and solid state physics, the first Brillouin zone is a uniquely defined primitive cell in reciprocal space. The boundaries of this cell are given by planes related to points on the reciprocal lattice. It is found by the same method as for the Wigner–Seitz cell in the Bravais lattice...
s. He applied information theory
Information theory
Information theory is a branch of applied mathematics and electrical engineering involving the quantification of information. Information theory was developed by Claude E. Shannon to find fundamental limits on signal processing operations such as compressing data and on reliably storing and...
to physics and the design of computers and coined the concept of negentropy
Negentropy
The negentropy, also negative entropy or syntropy, of a living system is the entropy that it exports to keep its own entropy low; it lies at the intersection of entropy and life...
to demonstrate the similarity between entropy and information.
Brillouin offered a solution to the problem of Maxwell's demon
Maxwell's demon
In the philosophy of thermal and statistical physics, Maxwell's demon is a thought experiment created by the Scottish physicist James Clerk Maxwell to "show that the Second Law of Thermodynamics has only a statistical certainty." It demonstrates Maxwell's point by hypothetically describing how to...
. In his book, Relativity Reexamined, he called for a "painful and complete re-appraisal" of relativity theory which "is now absolutely necessary."
Books
- H. Armagnat and Léon Brillouin Les mesures en haute fréquence (Chiron, 1924)
- Léon Brillouin Les Statistiques Quantiques Et Leurs Applications. 2 Vols. (Presse Universitaires de France, 1930)
- Léon Brillouin La Théorie des Quanta et l'Atome de Bohr (Presse Universitaires de France, 1922, 1931)
- Léon Brillouin Conductibilité électrique et thermique des métaux (Hermann, 1934)
- Léon Brillouin Notions Elementaires de Mathématiques pour les Sciences Expérimentales (Libraires de l'Academie de Médecine, 1939)
- Léon Brillouin The Mathematics of Ultra-High Frequencies Radio (Brown University, 1943)
- Léon Brillouin Wave Propagation in Periodic Structures: Electric Filters and Crystal Lattices (McGraw-Hill, 1946) (Dover, 1953, 2003)
- Léon Brillouin Les Tenseurs en mécanique et en élasticité: Cours de physique théorique (Dover, 1946)
- Léon Brillouin Mathématiques (Masson, 1947)
- Léon Brillouin Notions élémentaires de mathématiques pour les sciences expérimentales (Masson, 1947)
- Léon Brillouin Propagation des ondes dans les milieux périodiques (Masson – Dunod, 1956)
- Léon Brillouin La science et la théorie de l'information (Masson, 1959)
- Léon Brillouin Vie Matière et Observation (Albin Michel, 1959)
- Léon Brillouin Wave Propagation and Group Velocity (Academic Press, 1960)
- Léon Brillouin Science and Information Theory (Academic Press, 1962) (Dover, 2004)
- Léon Brillouin Scientific Uncertainty and Information (Academic Press, 1964)
- Léon Brillouin Tensors in Mechanics and Elasticity. Translated from the French By Robert O. Brennan. (Engineering Physics: An International Series of Monographs, Vol. 2) (Academic Press, 1964)
- Léon Brillouin Relativity Reexamined (Academic Press, 1970)
- Léon Brillouin Tres Vidas Ejemplares en la Física (Madrid, Marzo, 1970)
See also
- Brillouin scatteringBrillouin scatteringBrillouin scattering, named after Léon Brillouin, occurs when light in a medium interacts with time dependent optical density variations and changes its energy and path. The density variations may be due to acoustic modes, such as phonons, magnetic modes, such as magnons, or temperature gradients...
- Brillouin zoneBrillouin zoneIn mathematics and solid state physics, the first Brillouin zone is a uniquely defined primitive cell in reciprocal space. The boundaries of this cell are given by planes related to points on the reciprocal lattice. It is found by the same method as for the Wigner–Seitz cell in the Bravais lattice...
- Brillouin function
- Einstein-Brillouin-Keller methodEinstein-Brillouin-Keller methodThe Einstein–Brillouin–Keller method is a semiclassical method to compute eigenvalues in quantum mechanical systems.-See also:*Quantum mechanics*WKB approximation*Albert Einstein*Léon Brillouin*Joseph B. Keller...
- WKB approximationWKB approximationIn mathematical physics, the WKB approximation or WKB method is a method for finding approximate solutions to linear partial differential equations with spatially varying coefficients...
- NegentropyNegentropyThe negentropy, also negative entropy or syntropy, of a living system is the entropy that it exports to keep its own entropy low; it lies at the intersection of entropy and life...
Further reading
- Mehra, Jagdish, and Helmut Rechenberg The Historical Development of Quantum Theory. Volume 1 Part 2 The Quantum Theory of Planck, Einstein, Bohr and Sommerfeld 1900–1925: Its Foundation and the Rise of Its Difficulties. (Springer, 2001) ISBN 0-387-95175-X
- Mehra, Jagdish, and Helmut Rechenberg The Historical Development of Quantum Theory. Volume 5 Erwin Schrödinger and the Rise of Wave Mechanics. Part 2 Schrödinger in Vienna and Zurich 1887-1925. (Springer, 2001) ISBN 0-387-95180-6
- Schiff, Leonard I. Quantum Mechanics (McGraw-Hill, 3rd edition, 1968)
- Mosseri, Rémy Léon Brillouin à la croisée des ondes (Belin, Paris, 1999) ISBN 2-7011-2299-6