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Louis de Broglie
Broglie in 1929
Louis Victor Pierre Raymond

(1892-08-15)15 August 1892
Dieppe, France
Died19 March 1987(1987-03-19) (aged 94)
Louveciennes, France
EducationUniversity of Paris
(BA in History, 1910; BA in Sciences, 1913; PhD in physics, 1924)
Known forWave nature of electrons
De Broglie–Bohm theory
De Broglie waves
AwardsNobel Prize in Physics (1929)
Henri Poincaré Medal (1929)
Albert I of Monaco Prize (1932)
Max Planck Medal (1938)
Kalinga Prize (1952)
Scientific career
InstitutionsUniversity of Paris (Sorbonne)
ThesisRecherches sur la théorie des quanta ("Research on Quantum Theory") (1924)
Doctoral advisorPaul Langevin
Doctoral studentsCécile DeWitt-Morette
Bernard d'Espagnat
Jean-Pierre Vigier
Alexandru Proca
Marie-Antoinette Tonnelat

Louis Victor Pierre Raymond, 7th Duc de Broglie (/də ˈbrɡli/,[1] also US: /də brˈɡl, də ˈbrɔɪ/,[2][3] French: [də bʁɔj][4][5] or [də bʁœj] ; 15 August 1892 – 19 March 1987)[6] was a French aristocrat and physicist who made groundbreaking contributions to quantum theory. In his 1924 PhD thesis, he postulated the wave nature of electrons and suggested that all matter has wave properties. This concept is known as the de Broglie hypothesis, an example of wave–particle duality, and forms a central part of the theory of quantum mechanics.

De Broglie won the Nobel Prize for Physics in 1929, after the wave-like behaviour of matter was first experimentally demonstrated in 1927.

The 1925 pilot-wave model,[7] and the wave-like behaviour of particles discovered by de Broglie was used by Erwin Schrödinger in his formulation of wave mechanics.[8] The pilot-wave model and interpretation was then abandoned, in favor of the quantum formalism, until 1952 when it was rediscovered and enhanced by David Bohm.[9]

Louis de Broglie was the sixteenth member elected to occupy seat 1 of the Académie française in 1944, and served as Perpetual Secretary of the French Academy of Sciences.[10][11] De Broglie became the first high-level scientist to call for establishment of a multi-national laboratory, a proposal that led to the establishment of the European Organization for Nuclear Research (CERN).[12]


Origin and education

François-Marie, 1st duc de Broglie (1671–1745) ancestor of Louis de Broglie and Marshal of France under Louis XV of France

Louis de Broglie belonged to the famous aristocratic family of Broglie, whose representatives for several centuries occupied important military and political posts in France. The father of the future physicist, Louis-Alphonse-Victor, 5th duc de Broglie, was married to Pauline d’Armaille, the granddaughter of the Napoleonic General Philippe Paul, comte de Ségur and his wife, the biographer, Marie Célestine Amélie d'Armaillé. They had five children; in addition to Louis, these were: Albertina (1872–1946), subsequently the Marquise de Luppé; Maurice (1875–1960), subsequently a famous experimental physicist; Philip (1881–1890), who died two years before the birth of Louis, and Pauline, Comtesse de Pange (1888–1972), subsequently a famous writer.[13] Louis was born in Dieppe, Seine-Maritime. As the youngest child in the family, Louis grew up in relative loneliness, read a lot, and was fond of history, especially political. From early childhood, he had a good memory and could accurately read an excerpt from a theatrical production or give a complete list of ministers of the Third Republic of France. For this, he was predicted to become a great statesman in the future.[14]

De Broglie had intended a career in humanities, and received his first degree (licence ès lettres) in history. Afterwards he turned his attention toward mathematics and physics and received a degree (licence ès sciences) in physics. With the outbreak of the First World War in 1914, he offered his services to the army in the development of radio communications.

Military service

After graduation, Louis de Broglie joined the engineering forces to undergo compulsory service. It began at Fort Mont Valérien, but soon, on the initiative of his brother, he was seconded to the Wireless Communications Service and worked on the Eiffel Tower, where the radio transmitter was located. Louis de Broglie remained in military service throughout the First World War, dealing with purely technical issues. In particular, together with Léon Brillouin and brother Maurice, he participated in establishing wireless communications with submarines. Louis de Broglie was demobilized in August 1919 with the rank of adjudant. Later, the scientist regretted that he had to spend about six years away from the fundamental problems of science that interested him.[14][15]

Scientific and pedagogical career

His 1924 thesis Recherches sur la théorie des quanta[16] (Research on the Theory of the Quanta) introduced his theory of electron waves. This included the wave–particle duality theory of matter, based on the work of Max Planck and Albert Einstein on light. This research culminated in the de Broglie hypothesis stating that any moving particle or object had an associated wave. De Broglie thus created a new field in physics, the mécanique ondulatoire, or wave mechanics, uniting the physics of energy (wave) and matter (particle). He won the Nobel Prize in Physics in 1929 "for his discovery of the wave nature of electrons".[17]

In his later career, de Broglie worked to develop a causal explanation of wave mechanics, in opposition to the wholly probabilistic models which dominate quantum mechanical theory; it was refined by David Bohm in the 1950s. The theory has since been known as the De Broglie–Bohm theory.

In addition to strictly scientific work, de Broglie thought and wrote about the philosophy of science, including the value of modern scientific discoveries. In 1930 he founded the book series Actualités scientifiques et industrielles published by Éditions Hermann.[18]

De Broglie became a member of the Académie des sciences in 1933, and was the academy's perpetual secretary from 1942. He was asked to join Le Conseil de l'Union Catholique des Scientifiques Francais, but declined because he was non-religious.[19][20] In 1941, he was made a member of the National Council of Vichy France.[21] On 12 October 1944, he was elected to the Académie Française, replacing mathematician Émile Picard. Because of the deaths and imprisonments of Académie members during the occupation and other effects of the war, the Académie was unable to meet the quorum of twenty members for his election; due to the exceptional circumstances, however, his unanimous election by the seventeen members present was accepted. In an event unique in the history of the Académie, he was received as a member by his own brother Maurice, who had been elected in 1934. UNESCO awarded him the first Kalinga Prize in 1952 for his work in popularizing scientific knowledge, and he was elected a Foreign Member of the Royal Society on 23 April 1953.

Louis became the 7th duc de Broglie in 1960 upon the death without heir of his elder brother, Maurice, 6th duc de Broglie, also a physicist.

In 1961, he received the title of Knight of the Grand Cross in the Légion d'honneur. De Broglie was awarded a post as counselor to the French High Commission of Atomic Energy in 1945 for his efforts to bring industry and science closer together. He established a center for applied mechanics at the Henri Poincaré Institute, where research into optics, cybernetics, and atomic energy were carried out. He inspired the formation of the International Academy of Quantum Molecular Science and was an early member.[22]

Louis never married. When he died on 19 March 1987 in Louveciennes at the age of 94,[6] he was succeeded as duke by a distant cousin, Victor-François, 8th duc de Broglie. His funeral was held 23 March 1987 at the Church of Saint-Pierre-de-Neuilly.[23]

Scientific activity

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Physics of X-ray and photoelectric effect

The first works of Louis de Broglie (early 1920s) were performed in the laboratory of his older brother Maurice and dealt with the features of the photoelectric effect and the properties of x-rays. These publications examined the absorption of X-rays and described this phenomenon using the Bohr theory, applied quantum principles to the interpretation of photoelectron spectra, and gave a systematic classification of X-ray spectra.[14] The studies of X-ray spectra were important for elucidating the structure of the internal electron shells of atoms (optical spectra are determined by the outer shells). Thus, the results of experiments conducted together with Alexandre Dauvillier, revealed the shortcomings of the existing schemes for the distribution of electrons in atoms; these difficulties were eliminated by Edmund Stoner.[24] Another result was the elucidation of the insufficiency of the Sommerfeld formula for determining the position of lines in X-ray spectra; this discrepancy was eliminated after the discovery of the electron spin. In 1925 and 1926, Leningrad physicist Orest Khvolson nominated the de Broglie brothers for the Nobel Prize for their work in the field of X-rays.[13]

Matter and wave–particle duality

Main article: De Broglie hypothesis

Studying the nature of X-ray radiation and discussing its properties with his brother Maurice, who considered these rays to be some kind of combination of waves and particles, contributed to Louis de Broglie's awareness of the need to build a theory linking particle and wave representations. In addition, he was familiar with the works (1919–1922) of Marcel Brillouin, which proposed a hydrodynamic model of an atom and attempted to relate it to the results of Bohr's theory. The starting point in the work of Louis de Broglie was the idea of Einstein about the quanta of light. In his first article on this subject, published in 1922, the French scientist considered blackbody radiation as a gas of light quanta and, using classical statistical mechanics, derived the Wien radiation law in the framework of such a representation. In his next publication, he tried to reconcile the concept of light quanta with the phenomena of interference and diffraction and came to the conclusion that it was necessary to associate a certain periodicity with quanta. In this case, light quanta were interpreted by him as relativistic particles of very small mass.[25]

It remained to extend the wave considerations to any massive particles, and in the summer of 1923 a decisive breakthrough occurred. De Broglie outlined his ideas in a short note "Waves and quanta" (French: Ondes et quanta, presented at a meeting of the Paris Academy of Sciences on September 10, 1923),[26] which marked the beginning of the creation of wave mechanics. In this paper and his subsequent PhD thesis,[16] the scientist suggested that a moving particle with energy E and velocity v is characterized by some internal periodic process with a frequency (later known as Compton frequency), where is Planck's constant. To reconcile these considerations, based on the quantum principle, with the ideas of special relativity, de Broglie associated wave he called a "phase wave" with a moving body, which propagates with the phase velocity . Such a wave, which later received the name matter wave, or de Broglie wave, in the process of body movement remains in phase with the internal periodic process. Having then examined the motion of an electron in a closed orbit, the scientist showed that the requirement for phase matching directly leads to the quantum Bohr-Sommerfeld condition, that is, to quantize the angular momentum. In the next two notes (reported at the meetings on September 24 and October 8, respectively), de Broglie came to the conclusion that the particle velocity is equal to the group velocity of phase waves, and the particle moves along the normal to surfaces of equal phase. In the general case, the trajectory of a particle can be determined using Fermat's principle (for waves) or the principle of least action (for particles), which indicates a connection between geometric optics and classical mechanics.[27]

This theory set the basis of wave mechanics. It was supported by Einstein, confirmed by the electron diffraction experiments of G P Thomson and Davisson and Germer, and generalized by the work of Erwin Schrödinger.

From a philosophical viewpoint, this theory of matter-waves has contributed greatly to the ruin of the atomism of the past. Originally, de Broglie thought that real wave (i.e., having a direct physical interpretation) was associated with particles. In fact, the wave aspect of matter was formalized by a wavefunction defined by the Schrödinger equation, which is a pure mathematical entity having a probabilistic interpretation, without the support of real physical elements. This wavefunction gives an appearance of wave behavior to matter, without making real physical waves appear. However, until the end of his life de Broglie returned to a direct and real physical interpretation of matter-waves, following the work of David Bohm.

Conjecture of an internal clock of the electron

In his 1924 thesis, de Broglie conjectured that the electron has an internal clock that constitutes part of the mechanism by which a pilot wave guides a particle.[28] Subsequently, David Hestenes has proposed a link to the zitterbewegung that was suggested by Schrödinger.[29]

While attempts at verifying the internal clock hypothesis and measuring clock frequency are so far not conclusive,[30] recent experimental data is at least compatible with de Broglie's conjecture.[31]

Non-nullity and variability of mass

According to de Broglie, the neutrino and the photon have rest masses that are non-zero, though very low. That a photon is not quite massless is imposed by the coherence of his theory. Incidentally, this rejection of the hypothesis of a massless photon enabled him to doubt the hypothesis of the expansion of the universe.

In addition, he believed that the true mass of particles is not constant, but variable, and that each particle can be represented as a thermodynamic machine equivalent to a cyclic integral of action.

Generalization of the principle of least action

See also: Hamilton's optico-mechanical analogy

In the second part of his 1924 thesis, de Broglie used the equivalence of the mechanical principle of least action with Fermat's optical principle: "Fermat's principle applied to phase waves is identical to Maupertuis' principle applied to the moving body; the possible dynamic trajectories of the moving body are identical to the possible rays of the wave." This latter equivalence had been pointed out by William Rowan Hamilton a century earlier, and published by him around 1830, for the case of light.

Duality of the laws of nature

Far from claiming to make "the contradiction disappear" which Max Born thought could be achieved with a statistical approach, de Broglie extended wave–particle duality to all particles (and to crystals which revealed the effects of diffraction) and extended the principle of duality to the laws of nature.

His last work made a single system of laws from the two large systems of thermodynamics and of mechanics:[citation needed]

When Boltzmann and his continuators developed their statistical interpretation of Thermodynamics, one could have considered Thermodynamics to be a complicated branch of Dynamics. But, with my actual ideas, it's Dynamics that appear to be a simplified branch of Thermodynamics. I think that, of all the ideas that I've introduced in quantum theory in these past years, it's that idea that is, by far, the most important and the most profound.

That idea seems to match the continuous–discontinuous duality, since its dynamics could be the limit of its thermodynamics when transitions to continuous limits are postulated. It is also close to that of Gottfried Wilhelm Leibniz, who posited the necessity of "architectonic principles" to complete the system of mechanical laws.[citation needed]

However, according to him, there is less duality, in the sense of opposition, than synthesis (one is the limit of the other)[citation needed] and the effort of synthesis is constant according to him, like in his first formula, in which the first member pertains to mechanics and the second to optics:

Neutrino theory of light

Main article: Neutrino theory of light

This theory, which dates from 1934, introduces the idea that the photon is equivalent to the fusion of two Dirac neutrinos. It is not currently accepted by the majority of physicists.

Hidden thermodynamics

De Broglie's final idea was the hidden thermodynamics of isolated particles. It is an attempt to bring together the three furthest principles of physics: the principles of Fermat, Maupertuis, and Carnot.

In this work, action becomes a sort of opposite to entropy, through an equation that relates the only two universal dimensions of the form:

As a consequence of its great impact, this theory brings back the uncertainty principle to distances around extrema of action, distances corresponding to reductions in entropy.

Honors and awards


Ondes et mouvements, 1926


  1. ^ "de Broglie, Louis-Victor". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 4 December 2020.
  2. ^ "de Broglie". The American Heritage Dictionary of the English Language (5th ed.). HarperCollins. Retrieved 10 August 2019.
  3. ^ "De Broglie". Collins English Dictionary. HarperCollins. Retrieved 10 August 2019.
  4. ^ Léon Warnant (1987). Dictionnaire de la prononciation française dans sa norme actuelle (in French) (3rd ed.). Gembloux: J. Duculot, S. A. ISBN 978-2-8011-0581-8.
  5. ^ Jean-Marie Pierret (1994). Phonétique historique du français et notions de phonétique générale (in French). Louvain-la-Neuve: Peeters. p. 102. ISBN 978-9-0683-1608-7.
  6. ^ a b Leroy, Francis (2003). A Century of Nobel Prize Recipients: Chemistry, Physics, and Medicine (illustrated ed.). CRC Press. p. 141. ISBN 0-8247-0876-8. Extract of page 141
  7. ^ The final pilot-wave model was presented in Solvay Conferences and later published, in "Ondes et mouvements" of 1926.
  8. ^ Antony Valentini: On the Pilot-Wave Theory of Classical, Quantum and Subquantum Physics, Ph.D. Thesis, ISAS, Trieste 1992
  9. ^ "de Broglie vs Bohm". Excerpts from 1960 book published by Elsevier Pub.Co. Retrieved 30 June 2015.
  10. ^ O'Connor, John J.; Robertson, Edmund F., "Louis de Broglie", MacTutor History of Mathematics Archive, University of St Andrews
  11. ^ "History of International Academy of Quantum Molecular Science". IAQMS. Retrieved 8 March 2010.
  12. ^ "Louis de Broglie". Soylent Communications. Retrieved 12 June 2015.
  13. ^ a b M. J. Nye. (1997). "Aristocratic Culture and the Pursuit of Science: The De Broglies in Modern France". Isis. 88 (3) (Isis ed.): 397–421. doi:10.1086/383768. JSTOR 236150. S2CID 143439041.
  14. ^ a b c A. Abragam. (1988). "Louis Victor Pierre Raymond de Broglie". 34 (Biographical Memoirs of Fellows of the Royal Society ed.): 22–41. doi:10.1098/rsbm.1988.0002. ((cite journal)): Cite journal requires |journal= (help)
  15. ^ J. Lacki. (2008). "Louis de Broglie". 1 (New Dictionary of Scientific Biography ed.). Detroit: Charles Scribner's Sons: 409–415. ((cite journal)): Cite journal requires |journal= (help)
  16. ^ a b de Broglie, Louis Victor. "On the Theory of Quanta" (PDF). Foundation of Louis de Broglie (English translation by A.F. Kracklauer, 2004. ed.). Retrieved 2 January 2020.
  17. ^ "The Nobel Prize in Physics 1929". Nobel Foundation. Archived from the original on 24 October 2008. Retrieved 9 October 2008.
  18. ^ Recherche (PPN) 01331081X: Actualités scientifiques et industrielles, Retrieved 11 December 2021.
  19. ^ Evans, James; Thorndike, Alan S. (2007). Quantum Mechanics at the Crossroads: New Perspectives From History, Philosophy And Physics. Springer. p. 71. ISBN 9783540326632. Asked to join Le Conseil de l'Union Catholique des Scientifiques Français, Louis declined because, he said, he had ceased the religious practices of his youth.
  20. ^ Kimball, John (2015). Physics Curiosities, Oddities, and Novelties. CRC Press. p. 323. ISBN 978-1-4665-7636-0.
  21. ^ Les professeurs de la Faculté des sciences de Paris [1]
  22. ^ Piotr Piecuch; Jean Maruani; Gerardo Delgado-Barrio; Stephen Wilson (30 September 2009). Advances in the Theory of Atomic and Molecular Systems: Conceptual and Computational Advances in Quantum Chemistry. Springer Science & Business Media. p. 4. ISBN 978-90-481-2596-8.
  23. ^ Louis Néel; Fondation Louis de Broglie; Conservatoire national des arts et métiers (France) (1988). Louis de Broglie que nous avons connu. Fondation Louis de Broglie, Conservatoire national des arts et métiers.
  24. ^ The Philosophy of Quantum Mechanics: The Interpretations of Quantum Mechanics in Historical Perspective. New York: Wiley-Interscience, 1974. ISBN 0-471-43958-4
  25. ^ J. Mehra. (2001). J. Mehra. (ed.). "Louis de Broglie and the phase waves associated with matter" (The Golden Age of Theoretical Physics ed.). World Scientific: 546–570. ((cite journal)): Cite journal requires |journal= (help)
  26. ^ "Membres de l'Académie des sciences depuis sa création: Louis de Broglie Ondes et quanta" (PDF). (in French). 1923.
  27. ^ Max Jammer The Conceptual Development of Quantum Mechanics. New York: McGraw-Hill, 1966 2nd ed: New York: American Institute of Physics, 1989. ISBN 0-88318-617-9. Olivier Darrigol, "Strangeness and soundness in Louis de Broglie's early works," Physis, 30 (1993): 303–372.
  28. ^ See for example the description of de Broglie's view in: David Bohm, Basil Hiley: The de Broglie pilot wave theory and the further development and new insights arising out of it, Foundations of Physics, volume 12, number 10, 1982, Appendix: On the background of the papers on trajectories interpretation, by D. Bohm, (PDF Archived 19 August 2011 at the Wayback Machine)
  29. ^ D. Hestenes, October 1990, The Zitterbewegung interpretation of quantum mechanics, Foundations of Physics, vol. 20, no. 10, pp. 1213–1232
  30. ^ See for example G.R. Osche, Electron channeling resonance and de Broglie's internal clock, Annales de la Fondation Louis de Broglie, vol. 36, 2001, pp. 61–71 (full text)
  31. ^ Catillon, Foundations of Physics, July 2001, vol. 38, no. 7, pp. 659–664
  32. ^ "APS Member History". Retrieved 10 May 2023.
  33. ^ "Duc L. De Broglie". Retrieved 10 May 2023.
  34. ^ Abragam, A. (1988). "Louis Victor Pierre Raymond de Broglie. 15 August 1892-19 March 1987". Biographical Memoirs of Fellows of the Royal Society. 34: 22–26. doi:10.1098/rsbm.1988.0002. JSTOR 770045.
  35. ^ "Louis Victor Pierre Raymond de Broglie". American Academy of Arts & Sciences. 9 February 2023. Retrieved 10 May 2023.
  36. ^ "Review of Einstein by Louis de Broglie and others". Bulletin of the Atomic Scientists. 36 (3): 50. March 1980.