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Louis de Broglie
Born	(1892-08-15)15 August 1892 Dieppe, France
Died	19 March 1987(1987-03-19) (aged 94) Louveciennes, France
Nationality	French
Alma mater	Sorbonne
Known for	Wave nature of electrons De Broglie–Bohm theory de Broglie wavelength
Awards	Nobel Prize in Physics (1929)
Scientific career
Fields	Physics
Institutions	Sorbonne University of Paris
Doctoral advisor	Paul Langevin
Doctoral students	Cécile DeWitt-Morette Bernard d'Espagnat Jean-Pierre Vigier Alexandru Proca

Louis-Victor-Pierre-Raymond, 7th duc de Broglie, (/dəˈbrɔɪ/; Template:IPA-fr, Template:IPA-fr; 15 August 1892 – 19 March 1987) was a French 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 wave-particle duality or the de Broglie hypothesis. He won the Nobel Prize for Physics in 1929. The wave-like behaviour of particles discovered by de Broglie was used by Erwin Schrödinger in his formulation of wave mechanics. 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.

Biography

Louis de Broglie was born to a noble family in Dieppe, Seine-Maritime, younger son of Victor, 5th duc de Broglie. He became the 7th duc de Broglie upon the death without heir in 1960 of his older brother, Maurice, 6th duc de Broglie, also a physicist. He did not marry. When he died in Louveciennes, he was succeeded as duke by a distant cousin, Victor-François, 8th duc de Broglie.

De Broglie and his colleagues had intended a career in humanities, and received his first degree in history. Afterwards, though, he turned his attention toward mathematics and physics and received a degree 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.

His 1924 Recherches sur la théorie des quanta (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. The thesis examiners, unsure of the material, passed his thesis to Einstein for evaluation who endorsed his wave–particle duality proposal wholeheartedly; de Broglie was awarded his doctorate. 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). For this he won the Nobel Prize in Physics in 1929.

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.

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; however, he declined. This was due to the fact that he was non-religious.

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.

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.

Important theories

de Broglie's wave mechanics

When in 1923–1924 I had my first ideas about Wave Mechanics I was looking for a truly concrete physical image, valid for all particles, of the wave and particle coexistence discovered by Albert Einstein in his "Theory of light quanta". I had no doubt whatsoever about the physical reality of waves and particles.
For me, the particle, precisely located in space at every instant, forms on the v wave a small region of high energy concentration, which may be likened in a first approximation, to a moving singularity. —Louis de Broglie

De Broglie's idea for interpreting particle–wave duality was that a particle is a moving singularity with an associated wave.

Any particle, even isolated, has to be imagined as in continuous 'energetic contact' with a hidden medium

In this interpretation, it is the hidden medium which waves. The "energetic contact" can be assumed to be the particle moving through and displacing the hidden medium, analogous to the bow wave of a boat. The hidden medium is analogous to a supersolid as the particle does not slow down and what Robert B. Laughlin describes as a piece of window glass, "Subsequent studies with large particle accelerators have now led us to understand that space is more like a piece of window glass than ideal Newtonian emptiness."

In a double slit experiment the particle travels a well defined path that takes it through one slit. The associated wave in the hidden medium passes through both. As the wave exits the slits it creates wave interference. As the particle exits a single slit the direction it travels is altered by the wave interference. This is the wave piloting the particle. Detecting the particle strongly exiting a single slit destroys the cohesion between the particle and its associated wave and the particle continues on the trajectory it was traveling.

Aephraim Steinberg's experiments on measuring both average position and momentum of photons were described in terms of the pilot-wave theory, in several reviews:

Intriguingly, the trajectories closely match those predicted by an unconventional interpretation of quantum mechanics known as pilot-wave theory, in which each particle has a well-defined trajectory that takes it through one slit while the associated wave passes through both slits.

For his part, Professor Steinberg believes that the result reduces a limitation not on quantum physics but on physicists themselves. "I feel like we're starting to pull back a veil on what nature really is," he said. "The trouble with quantum mechanics is that while we've learned to calculate the outcomes of all sorts of experiments, we've lost much of our ability to describe what is really happening in any natural language. I think that this has really hampered our ability to make progress, to come up with new ideas and see intuitively how new systems ought to behave."

Steinberg's work stood out because it challenges the widely held notion that quantum mechanics forbids us any knowledge of the paths taken by individual photons as they travel through two closely spaced slits to create an interference pattern.

Walking droplets

Yves Couder and co-workers recently discovered a macroscopic pilot wave system in the form of walking droplets. This system exhibits behaviour of a pilot wave, heretofore considered to be reserved to microscopic phenomena.

MIT researchers expand the range of quantum behaviors that can be replicated in fluidic systems, offering a new perspective on wave-particle duality. "Whatever the case may be in quantum mechanics, the statistics are an incomplete description of our fluid system and emerge from an underlying pilot-wave dynamics. This physical picture is remakably similar to an early model of quantum dynamics proposed by Louis de Broglie..."

Matter and wave–particle duality

"The fundamental idea of was the following: The fact that, following Einstein's introduction of photons in light waves, one knew that light contains particles which are concentrations of energy incorporated into the wave, suggests that all particles, like the electron, must be transported by a wave into which it is incorporated... My essential idea was to extend to all particles the coexistence of waves and particles discovered by Einstein in 1905 in the case of light and photons." "With every particle of matter with mass m and velocity v a real wave must be 'associated'", related to the momentum by the equation:

${\displaystyle \lambda ={\frac {h}{p}}={\frac {h}{{m}{v}}}{\sqrt {1-{\frac {v^{2}}{c^{2}}}}}}$

where ${\displaystyle \lambda }$ is the wavelength, ${\displaystyle h}$ is the Planck constant, ${\displaystyle p}$ is the momentum, ${\displaystyle m}$ is the rest mass, ${\displaystyle v}$ is the velocity and ${\displaystyle c}$ is the speed of light in a vacuum."

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

However, this generalization was statistical and was not approved of by de Broglie, who said "that the particle must be the seat of an internal periodic movement and that it must move in a wave in order to remain in phase with it was ignored by the actual physicists wrong to consider a wave propagation without localization of the particle, which was quite contrary to my original ideas."

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. The de Broglie–Bohm theory is today the only interpretation giving real status to matter-waves and representing the predictions of quantum theory.

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. Subsequently David Hestenes has proposed a link to the Zitterbewegung that was suggested by Erwin Schrödinger.

Attempts at verifying the internal clock hypothesis and measuring clock frequency are so far not conclusive; recent experimental data is at least compatible with de Broglie's conjecture.

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

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 equivalence had been pointed out by Hamilton a century earlier, and published by him around 1830, in an era where no experience gave proof of the fundamental principles of physics being involved in the description of atomic phenomena.

Up to his final work, he appeared to be the physicist who most sought that dimension of action which Max Planck, at the beginning of the 20th century, had shown to be the only universal unity (with his dimension of entropy).

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:

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 Leibniz, who posited the necessity of "architectonic principles" to complete the system of mechanical laws.

However, according to him, there is less duality, in the sense of opposition, than synthesis (one is the limit of the other) 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:

${\displaystyle mc^{2}=h\nu }$

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 shows that the movement of the center of gravity of these two particles obeys the Maxwell equations—that implies that the neutrino and the photon both have rest masses that are non-zero, though very low.

Hidden thermodynamics

De Broglie's final great 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:

${\displaystyle {Action \over h}=-{Entropy \over k}}$

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

• 1929 Nobel Prize in Physics
• 1929 Henri Poincaré Medal
• 1932 Albert I of Monaco Prize
• 1938 Max Planck Medal
• 1938 Fellow, Royal Swedish Academy of Sciences
• 1944 Fellow, Académie française
• 1952 Kalinga Prize
• 1953 Fellow, Royal Society

Publications

• Recherches sur la théorie des quanta (Researches on the quantum theory), Thesis, Paris, 1924, Ann. de Physique (10) 3, 22 (1925)
• Ondes et mouvements (Waves and Motions). Paris: Gauthier-Villars, 1926.
• Rapport au 5e Conseil de Physique Solvay. Brussels, 1927.
• La mécanique ondulatoire (Wave Mechanics). Paris: Gauthier-Villars, 1928.
• Matière et lumière (Matter and Light). Paris: Albin Michel, 1937.
• Une tentative d'interprétation causale et non linéaire de la mécanique ondulatoire: la théorie de la double solution. Paris: Gauthier-Villars, 1956.
  • English translation: Non-linear Wave Mechanics: A Causal Interpretation. Amsterdam: Elsevier, 1960.
• Sur les sentiers de la science (On the Paths of Science).
• Introduction à la nouvelle théorie des particules de M. Jean-Pierre Vigier et de ses collaborateurs. Paris: Gauthier-Villars, 1961. Paris: Albin Michel, 1960.
  • English translation: Introduction to the Vigier Theory of elementary particles. Amsterdam: Elsevier, 1963.
• Étude critique des bases de l'interprétation actuelle de la mécanique ondulatoire. Paris: Gauthier-Villars, 1963.
  • English translation: The Current Interpretation of Wave Mechanics: A Critical Study. Amsterdam, Elsevier, 1964.
• Certitudes et incertitudes de la science (Certitudes and Incertitudes of Science). Paris: Albin Michel, 1966.

References

1. 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.
2. 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.
3. O'Connor, John J.; Robertson, Edmund F., "Louis de Broglie", MacTutor History of Mathematics Archive, University of St Andrews
4. "History of International Academy of Quantum Molecular Science". IAQMS. Retrieved 2010-03-08.
5. 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. {{cite book}}: |access-date= requires |url= (help)
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7. de Broglie, Louis. "Interpretation of quantum mechanics by the double solution theory" (PDF). {{cite journal}}: Cite journal requires |journal= (help)
8. L. de Broglie, p. 22.
9. Robert B. Laughlin, "A Different Universe: Reinventing Physics from the Bottom Down"
10. Cartlidge, Edwin. "New 'Double Slit' Experiment Skirts Uncertainty Principle". {{cite journal}}: Cite journal requires |journal= (help)
11. Palmer, Jason. "Team 'sneaks around' quantum rule". {{cite journal}}: Cite journal requires |journal= (help)
12. "Physics World reveals its top 10 breakthroughs for 2011". {{cite journal}}: Cite has empty unknown parameter: |1= (help); Cite journal requires |journal= (help)
13. Y. Couder, A. Boudaoud, S. Protière, Julien Moukhtar, E. Fort: Walking droplets: a form of wave-particle duality at macroscopic level? , doi:10.1051/epn/2010101, (PDF)
14. Hardesty, Larry. "When fluid dynamics mimic quantum mechanics". {{cite journal}}: Cite journal requires |journal= (help)
15. D. Harris, J. Bush. The pilot-wave dynamics of walking droplets - 2:10 mark.
16. D. Harris, J. Bush. The pilot-wave dynamics of walking droplets - 2:35 mark.
17. 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)
18. D. Hestenes, October 1990, The Zitterbewegung interpretation of quantum mechanics, Foundations of Physics, vol. 20, no. 10, pp. 1213–1232
19. 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)
20. Catillon, Foundations of Physics, July 2001, vol. 38, no. 7, pp. 659–664

External links

• Les Immortels: Louis de BROGLIE" (Académie française, in French)
• Louis de Broglie – Biography" (Nobel Foundation)
• Paul Theroff (2005) An Online Gotha: Broglie Genealogy
• Fondation Louis de Broglie
• Louis de Broglie at the Mathematics Genealogy Project
• English translation of his book on hidden thermodynamics by D. H. Delphenich
• The Theory of measurement in wave mechanics (English translation of his book on the subject)
• "A new conception of light" (English translation)

v t e Laureates of the Nobel Prize in Physics
1901–1925	1901: Röntgen 1902: Lorentz / Zeeman 1903: Becquerel / P. Curie / M. Curie 1904: Rayleigh 1905: Lenard 1906: J. J. Thomson 1907: Michelson 1908: Lippmann 1909: Marconi / Braun 1910: Van der Waals 1911: Wien 1912: Dalén 1913: Kamerlingh Onnes 1914: Laue 1915: W. L. Bragg / W. H. Bragg 1916 1917: Barkla 1918: Planck 1919: Stark 1920: Guillaume 1921: Einstein 1922: N. Bohr 1923: Millikan 1924: M. Siegbahn 1925: Franck / Hertz
1926–1950	1926: Perrin 1927: Compton / C. Wilson 1928: O. Richardson 1929: De Broglie 1930: Raman 1931 1932: Heisenberg 1933: Schrödinger / Dirac 1934 1935: Chadwick 1936: Hess / C. D. Anderson 1937: Davisson / G. P. Thomson 1938: Fermi 1939: Lawrence 1940 1941 1942 1943: Stern 1944: Rabi 1945: Pauli 1946: Bridgman 1947: Appleton 1948: Blackett 1949: Yukawa 1950: Powell
1951–1975	1951: Cockcroft / Walton 1952: Bloch / Purcell 1953: Zernike 1954: Born / Bothe 1955: Lamb / Kusch 1956: Shockley / Bardeen / Brattain 1957: C. N. Yang / T. D. Lee 1958: Cherenkov / Frank / Tamm 1959: Segrè / Chamberlain 1960: Glaser 1961: Hofstadter / Mössbauer 1962: Landau 1963: Wigner / Goeppert Mayer / Jensen 1964: Townes / Basov / Prokhorov 1965: Tomonaga / Schwinger / Feynman 1966: Kastler 1967: Bethe 1968: Alvarez 1969: Gell-Mann 1970: Alfvén / Néel 1971: Gabor 1972: Bardeen / Cooper / Schrieffer 1973: Esaki / Giaever / Josephson 1974: Ryle / Hewish 1975: A. Bohr / Mottelson / Rainwater
1976–2000	1976: Richter / Ting 1977: P. W. Anderson / Mott / Van Vleck 1978: Kapitsa / Penzias / R. Wilson 1979: Glashow / Salam / Weinberg 1980: Cronin / Fitch 1981: Bloembergen / Schawlow / K. Siegbahn 1982: K. Wilson 1983: Chandrasekhar / Fowler 1984: Rubbia / Van der Meer 1985: von Klitzing 1986: Ruska / Binnig / Rohrer 1987: Bednorz / Müller 1988: Lederman / Schwartz / Steinberger 1989: Ramsey / Dehmelt / Paul 1990: Friedman / Kendall / R. Taylor 1991: de Gennes 1992: Charpak 1993: Hulse / J. Taylor 1994: Brockhouse / Shull 1995: Perl / Reines 1996: D. Lee / Osheroff / R. Richardson 1997: Chu / Cohen-Tannoudji / Phillips 1998: Laughlin / Störmer / Tsui 1999: 't Hooft / Veltman 2000: Alferov / Kroemer / Kilby
2001– present	2001: Cornell / Ketterle / Wieman 2002: Davis / Koshiba / Giacconi 2003: Abrikosov / Ginzburg / Leggett 2004: Gross / Politzer / Wilczek 2005: Glauber / Hall / Hänsch 2006: Mather / Smoot 2007: Fert / Grünberg 2008: Nambu / Kobayashi / Maskawa 2009: Kao / Boyle / Smith 2010: Geim / Novoselov 2011: Perlmutter / Schmidt / Riess 2012: Wineland / Haroche 2013: Englert / Higgs 2014: Akasaki / Amano / Nakamura 2015: Kajita / McDonald 2016: Thouless / Haldane / Kosterlitz 2017: Weiss / Barish / Thorne 2018: Ashkin / Mourou / Strickland 2019: Peebles / Mayor / Queloz 2020: Penrose / Genzel / Ghez 2021: Parisi / Hasselmann / Manabe 2022: Aspect / Clauser / Zeilinger 2023: Agostini / Krausz / L'Huillier 2024: Hopfield / Hinton

v t e Dukes of Broglie
François-Marie (1742) Victor-François (1745) Achille-Léonce-Victor-Charles (1804) Jacques-Victor-Albert (1870) Louis-Alphonse-Victor (1901) Louis-César-Victor-Maurice (1906) Louis-Victor-Pierre-Raymond (1960) Victor-François Marie Léon (1987) Philippe-Maurice (2012)

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• 1892 births
• 1987 deaths
• People from Dieppe, Seine-Maritime
• Dukes of Broglie
• University of Paris alumni
• Foreign Members of the Royal Society
• French physicists
• International Academy of Quantum Molecular Science members
• Kalinga Prize recipients
• University of Paris faculty
• Members of the Académie française
• Officers of the French Academy of Sciences
• Members of the Royal Swedish Academy of Sciences
• Foreign Members of the USSR Academy of Sciences
• Nobel laureates in Physics
• French Nobel laureates
• Quantum physicists
• Grand Croix of the Légion d'honneur
• French military personnel of World War I
• Theoretical physicists
• Winners of the Max Planck Medal