Louis, 7Louis, 7thth duc de Broglie, duc de Broglie,Nobel Laureate.Nobel Laureate.

BiographyBiography●He was born in Dieppe(Siene), younger son of Victor, Duc de He was born in Dieppe(Siene), younger son of Victor, Duc de Broglie, and Pauline d'Armaillé.Broglie, and Pauline d'Armaillé.●Louis studied at the Lyceé Janson de Sailly in Paris. He Louis studied at the Lyceé Janson de Sailly in Paris. He completed his secondary school education in 1909.completed his secondary school education in 1909.●In the first years of his life in university, he studied history and In the first years of his life in university, he studied history and intended to be a humanist. intended to be a humanist. At the age of 18 he graduated with At the age of 18 he graduated with an arts degree.an arts degree.

BiographyBiography●Afterwards, he became interested in mathematical physics.Afterwards, he became interested in mathematical physics.●During World War 1, he served in the station at the Eiffel Tower During World War 1, he served in the station at the Eiffel Tower (wireless telegraphy section).(wireless telegraphy section).●During these years, he spent his spare time to think about technical During these years, he spent his spare time to think about technical problems. “problems. “When in 1920 I resumed my studies ... what attracted me ... to theoretical physics When in 1920 I resumed my studies ... what attracted me ... to theoretical physics was ... the mystery in which the structure of matter and of radiation was becoming more and more was ... the mystery in which the structure of matter and of radiation was becoming more and more enveloped as the strange concept of the quantum, introduced by enveloped as the strange concept of the quantum, introduced by PlacnkPlacnk in 1900 in his researches in 1900 in his researches into black-body radiation, daily penetrated further into the whole of physics. “into black-body radiation, daily penetrated further into the whole of physics. “

●In 1924, he introduced his theory of electron waves (Recherches sur la théorie des quanta - Research on Quantum Theory) . This included the wave-particle duality theory of matter, based on the work of Einstein and Planck.

BiographyBiography

He created the new field of physics, He created the new field of physics, mécanique ondulatoire, - mécanique ondulatoire, - wave mechanics. He united physics of light and matter.wave mechanics. He united physics of light and matter.

For this work, he won the 1929 Nobel Prize.For this work, he won the 1929 Nobel Prize. Between 1930 and 1950, Louis de Broglie's work has been chiefly Between 1930 and 1950, Louis de Broglie's work has been chiefly

devoted to the study of the various extensions of wave mechanics.devoted to the study of the various extensions of wave mechanics. Since 1951, together with young colleagues, Louis de Broglie Since 1951, together with young colleagues, Louis de Broglie

resumed the study of an the resumed the study of an the theory of the double solutiontheory of the double solution to give a to give a causal interpretation to wave mechanics in the classical terms of causal interpretation to wave mechanics in the classical terms of space and time.space and time.

Back again in this his former field of research, he has obtained a Back again in this his former field of research, he has obtained a certain number of new and encouraging results which he has certain number of new and encouraging results which he has published in notes to published in notes to Comptes Rendus de l'Académie des SciencesComptes Rendus de l'Académie des Sciences and in various expositions.and in various expositions.

BiographyBiography

Louis de Broglie became a member of the Académie des sciences in 1933, and was the academy's perpetual secretary from 1942. On 12 October 1944, he was elected to the Académie française, replacing mathematician Émile Picard

He was also awarded the Henri Poincaré medal and the Albert I of Monaco prize.

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.

He never married. Louis de Broglie died on March 19, 1987.

ContributionContribution

The wave nature of electron.The wave nature of electron. De Broglie hypothesis: every moving particle or object had De Broglie hypothesis: every moving particle or object had

an associated wave.an associated wave. Started a new field of physics: wave mechanics.Started a new field of physics: wave mechanics. Most important publications: Most important publications: Recherches sur la théorie des Recherches sur la théorie des

quanta (Researches on the quantum theory) (1924), Ondes quanta (Researches on the quantum theory) (1924), Ondes et mouvementset mouvements (Waves and motions) (1926), (Waves and motions) (1926), La La mécanique ondulatoiremécanique ondulatoire (Wave mechanics) (1928) (Wave mechanics) (1928)……

Wave-particle dualityWave-particle duality

In physics, In physics, wave-particle dualitywave-particle duality holds that light holds that light and matter can exhibit properties of both waves and matter can exhibit properties of both waves and of particles. It is a central concept of quantum and of particles. It is a central concept of quantum mechanics. mechanics.

Through the work of Through the work of Albert EinsteinAlbert Einstein, , Louis de BroglieLouis de Broglie and many others, it is now and many others, it is now established that small objects, such as established that small objects, such as atomsatoms, , have both wave and particle nature, and that have both wave and particle nature, and that quantum mechanics provides the over-arching quantum mechanics provides the over-arching theory resolving this apparent theory resolving this apparent paradoxparadox

HistoryHistory

In 19In 19thth century, light was believed to be a century, light was believed to be a wave because of its property: diffraction and wave because of its property: diffraction and interference. interference.

By 20By 20thth century, Albert Einstein analysed the century, Albert Einstein analysed the photoelectric effect. He explained that light photoelectric effect. He explained that light has both particle-like and wave-like has both particle-like and wave-like properties.properties.

HistoryHistory

In 1924 De Broglie hypothesis, predicts that In 1924 De Broglie hypothesis, predicts that every particles also behave as waves:every particles also behave as waves:

hh is Planck's constant and is Planck's constant and pp the momentum the momentum of the electron, giving the wavelength of any of the electron, giving the wavelength of any particle.particle.

De Broglie HypothesisDe Broglie Hypothesis

HistoryHistory

Later, 2 independent experiments showed the Later, 2 independent experiments showed the diffraction of electrons which had been thought to diffraction of electrons which had been thought to only have particle-like property.only have particle-like property.

At the University of Aberdeen George Paget At the University of Aberdeen George Paget Thomson passed a beam of electrons through a Thomson passed a beam of electrons through a thin metal film and observed the predicted thin metal film and observed the predicted interference patterns. interference patterns.

At Bell Labs Clinton Joseph Davisson and Lester At Bell Labs Clinton Joseph Davisson and Lester Halbert Germer guided their beam through a Halbert Germer guided their beam through a crystalline grid. crystalline grid.

HistoryHistory

Acceleration of electron:Acceleration of electron:

U is electric potential, m0 is the mass of U is electric potential, m0 is the mass of electron and e is the elementary charge.electron and e is the elementary charge.

Nobel Stamp (1987)Nobel Stamp (1987)

The 1982 Nobel Stamps issue illustrates the theme nuclear physics The 1982 Nobel Stamps issue illustrates the theme nuclear physics and honours five winners of the Nobel Prize in Physics. They were and honours five winners of the Nobel Prize in Physics. They were rewarded for their work in developing a new atomic theory--rewarded for their work in developing a new atomic theory--quantum mechanics. The Laureates are: quantum mechanics. The Laureates are: NIELS BOHRNIELS BOHR, Denmark , Denmark (1922), (1922), ERWIN SCHRöDINGERERWIN SCHRöDINGER, Austria (1933), , Austria (1933), LOUIS DE BROGLIELOUIS DE BROGLIE, France (1929), , France (1929), PAUL DIRACPAUL DIRAC, England , England (1933) and (1933) and WERNER HEISENBERGWERNER HEISENBERG, Germany (1932)., Germany (1932).

Do you know that?Do you know that?

Louis, 7th Duc de Broglie came from a noble family in France. The family counts among its members three marshals of France, a

Nobel Prize laureate, and several members of the Institut de France.

Thank you for your Thank you for your listening.listening.