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Solvay  Conferences
© 2008-2012, Gérard P. Michon, Ph.D.

Ernest Solvay (1838-1922) was a Belgian chemist and industrialist whose patents brought him considerable wealth, which he used to bankroll several philanthropic endeavors.  In 1894 he founded a sociology institute at the University of Brussels, called "Institut des Sciences Sociales" (ISS).  In 1903, he founded the  Solvay Business School,  also at the University of Brussels.  Finally, in 1911, he established the prestigious meetings of top scientists known as  Solvay Conferences.  The first and the fifth of these (1911 and 1927) are particularly noteworthy, as they helped define the foundations for the first and second incarnations of quantum theory.

The First Solvay Conference  (1911)

In his letter of invitation dated June 15, 1911, Ernest Solvay explained that he conceived the first meeting as a  Conseil scientifique international pour élucider quelques questions d'actualité des théories moléculaires et cinétiques.  Arthur Schuster, Joseph Larmor, J.D. van der Waals and Lord Rayleigh were originally invited but could not come.  They were replaced by Edouard Herzen, Georges Hostelet, Martin Knudsen and Frederick A. Lindemann.  Poincaré had been omitted from the list drafted in May by Walther Nernst but this was soon corrected.  The meetings took place from Sunday, October 29 to Saturday, November 4, 1911,  but the conference itself lasted only from Monday to Friday.  The proceedings were published in 1912 by Maurice de Broglie and Paul Langevin.  Each participant received 1000 francs from Solvay for travel expenses.

 First Solvay Conference, 1911
Left-to right:   Standing:   Robert Goldschmidt, Max Planck, Heinrich Rubens, Arnold Sommerfeld,
Frederick Lindemann, Maurice de Broglie, Martin Knudsen, Fritz Hasenöhrl,
Georges Hostelet, Edouard Herzen, James Hopwood Jeans, Ernest Rutherford,
Heike Kamerlingh Onnes, Albert Einstein, Paul Langevin.
Seated:   Walther Nernst, Marcel Brillouin, Ernest Solvay, Hendrik Lorentz, Emil Warburg,
Jean-Baptiste Perrin (reading), Wilhelm Wien (upright), Marie Curie, Henri Poincaré.

Ernest Solvay himself was not present when the above group photo was taken.  This is why his head appears noticeably larger than it ought to...  His portrait was crudely pasted on before the picture was released.  There may have been a stand-in for Solvay when the photo was shot and whoever did this clumsy doctoring made absolutely sure that Solvay's head was larger than the face it had to hide!

Albert Einstein  was the youngest in attendance.  Although  Louis de Broglie  was not among the invitees, he did accompany his older brother Maurice who was acting as scientific secretary.  Legend has it that the 1911  Solvay conference  helped Louis de Broglie decide to start a career in theoretical physics.  He would become one of the rising stars at the Solvay conference of 1927...

The Fifth Solvay Conference  (1927)
"Electrons and Photons"

 Fifth Solvay Conference, 1927
Left-to right:   Top row:   A. Piccard, E. Henriot, P. Ehrenfest, Ed. Herzen, Th. De Donder, E. Schrödinger, E. Verschaffelt, W. Pauli, W. Heisenberg, R.H. Fowler, Léon Brillouin.   Middle:   P. Debye, M. Knudsen, W.L. Bragg, H.A. Kramers, P.A.M. Dirac, A.H. Compton, Louis de Broglie, Max Born, Niel Bohr.   Front row:   I. Langmuir, Max Planck, Marie Curie, H.A. Lorentz, A. Einstein, P. Langevin, Ch. E. Guye, C.T.R. Wilson, O.W. Richardson.

Langmuir's Movie  (intermissions at the 1927 Solvay conference)
[ RealPlayer | Flash | Google | YouTube | FreeScienceLectures ]
Voice-over by  Nancy Thorndike Greenspan  (biographer of Max Born)

21 attendees (out of 29) are seen...  In order of appearance :  Erwin Schrödinger, Niels Bohr, Auguste Piccard, Werner Heisenberg, Paul Ehrenfest, Peter Debye, Wolfgang Pauli, Léon Brillouin, Hendrik Kramers, Paul Dirac, Max Born, Louis de Broglie, Irving Langmuir, Marie Curie, William Lawrence Bragg, Arthur Holly Compton, Owen Richardson, H.A. Lorentz, Paul Langevin, Albert Einstein and Max Planck.

The  45  Participants
in chronological order of birth

 Emil Warburg 
 (1846-1931) Emil Gabriel Warburg   (1846-1931)

Emil Warburg  was president of the Deutsche Physikalische Gesellschaft  (DPG)  from 1899 to 1905.  He had distinguished himself  (with Kundt, in Strassburg)  in the  kinetic theory of gases, which was a key topic of the first Solvay conference.

1867 doctorate   |   Wikipedia

 Hendrik Antoon Lorentz Hendrik A. Lorentz   (1853-1928)       Chairman

Among the  many  contributions of  H.A. Lorentz  is the coordinate transformation which is the cornerstone of  Special Relativity.  In 1892, Lorentz proposed a theory of the  electron  (discovered by Perrin in 1895 and J.J. Thomson in 1898).

Nobel 1902   |   MacTutor   |   Wikipedia   |   Weisstein

 Heike Kamerlingh Onnes Heike Kamerlingh Onnes   (1853-1926)

In 1908, the cryogenic work of  Kamerlingh Onnes  culminated in the  liquefaction of helium.  He reached a temperature of  0.9 K.  In 1911, he discovered the  superconductivity,  at very low temperatures, of pure metals such as mercury, tin and lead.

Nobel 1913   |   Scientists of the Dutch School   |   Virial Coefficients   |   Wikipedia   |   Weisstein

 Jules Henri Poincare J. Henri Poincaré   (1854-1912; X1873)

Poincaré was the last  universal  genius and quintessential absent-minded professor  (cf.  Savant Cosinus  comic strip).  Poincaré conceived Special Relativity before Einstein did.   Signature of 
 Henri Poincare His mathematical legacy includes  chaos theory  and  topology.  Ecole Polytechnique (X)

MacTutor   |   Wikipedia   |   Weisstein   |   Bruce Medal 1911  

 Marcel Brillouin (1854-1948) 
 in 1895 (by A. Gerschel et fils) Louis "Marcel" Brillouin   (1854-1948)

Marcel Brillouin attended the 1911 conference and his son  Léon Brillouin (1889-1969) attended the 1927 conference.  Both of them were educated at the  Ecole Normale Supérieure  and held professorships at the  Sorbonne  and  Collège de France.  He was the teacher of Pierre Weiss.

Wikipedia   |   MacTutor

 Paternal coat-of-arms of Max Planck

 Max Planck 
 (1858-1947) Max Planck   (1858-1947)

Planck combined the formulas of Wien (UV) and Rayleigh (IR) to obtain a single expression for the whole blackbody spectrum.  On Dec. 14, 1900, he justified it by proposing that exchanges of energy only occur in discrete lumps, which he dubbed  quanta.
 Signature of Max Planck 
 at 10 years of age

Nobel 1918   |   Wikipedia   |   MacTutor   |   Facebook Fans

 Wilhelm Wien
 (1864-1928) Wilhelm Wien   (1864-1928)

In 1893,  Wilhelm Wien  formulated the  Wien displacement law  which describes how the shape of the blackbody spectrum is scaled with temperature.  This helped Planck devise the precise expression which led to the theory of quanta.

Nobel 1911   |   Wikipedia   |   Wien's distribution law (UV)   |   Wien's displacement law

 Walther Nernst (1864-1941) 
 in 1906 (by Nicola Perscheid) Walther Nernst   (1864-1941)

In 1906, Nernst  stated the  third law of thermodynamics :  In an isothermal reversible transformation between two stable states of a system, the change in entropy vanishes as the temperature tends to zero.  In 1911, Planck proposed to put  S=0 at T=0.

Nernst equation   |   Nobel 1920   |   Wikipedia

 Heinrich Rubens 
 (1865-1922) Heinrich Rubens   (1865-1922)

In 1889, Heinrich Rubens  wrote his doctoral dissertation on the spectrum of the light reflected by metals.  His experimental results suggested to Max Planck the form of the law of blackbody radiation which led him to propose the idea of  quanta.


 Charles-Eugene Guye 
 (1866-1942) Charles-Eugène Guye   (1866-1942)

The Swiss mathematician  Charles-Eugène Guye  succeeded Charles Soret as Professor of Physics at the  University of Geneva  (Guye had been Soret's first Ph.D. student).  For Guye, any  phenomenon  could only exist at certain observation scales.

Genève et ses savants   |   Rues de Genève


 Marie Curie 
 (1867-1934) Marie Curie, physical chemist  (1867-1934)

Marie Sklodowska-Curie was the first woman to earn a Nobel prize and the first person to earn two.  In 1898, she isolated two new elements (polonium and radium) by tracking their  ionizing radiation,  using the electrometer of Jacques and Pierre Curie.

Nobel 1903 (Physics)   |   Nobel 1911 (Chemistry)   |   Wikipedia   |   AIP   |   Facebook Fans

 Arnold Sommerfeld 
 (1868-1951) Arnold Sommerfeld   (1868-1951)

In 1916, he extended Bohr's model to elliptical orbits, introducing the azimuthal quantum number (L) and the  fine-structure constant  a = 1 / 137.036.  In 1920, he added the magnetic quantum number (m) paving the way for the discovery of  spin.

MacTutor   |   Wikipedia   |   Weisstein

 C.T.R. Wilson 
 (1869-1959) Charles Thomson Rees Wilson   (1869-1959)

In 1895,  the meteorologist  C.T.R. Wilson  reproduced cloud formation in a box.  Ultimately, in 1911, supersaturated dust-free ion-free air was seen to condense along the tracks of ionizing particles.  The  Wilson cloud chamber  detector was born.

Nobel 1927   |   Wikipedia

 Emile Verschaffelt 
 (1870-1955) Jules Emile Verschaffelt   (1870-1955)

The Flemish physicist  Emile Verschaffelt  had received a French education and his wife was Dutch.  He got his doctorate under Kamerlingh Onnes in 1899.  For years, he was Science secretary for the  Institut International de Physique Solvay.

Scientists of the Dutch School   |   Wikipedia

 Jean Perrin 
 (1870-1942) Jean-Baptiste Perrin   (1870-1942)

In 1895, Jean Perrin  showed that cathode rays consist of negatively charged particles.  In 1908, he accurately determined Avogadro's number and confirmed the atomic nature of matter, based on Einstein's explanation of Brownian motion (1905).

Nobel 1926   |   French Physicists   |   Wikipedia   |   NNDB

 Martin Knudsen 
 (1871-1949) Martin Hans Christian Knudsen   (1871-1949)

The Danish physicist  Martin Knudsen  was very active in hydrography.  He revived Maxwell's kinetic theory of gases, especially at low pressure:  Knudsen flow, Knudsen number, etc.  The  Knudsen cell  is used in molecular beam epitaxy.



 Ernest Rutherford 
 (1871-1937) Ernest Rutherford   (1871-1937)

The  gold-foil experiment (1909)  suggested to Rutherford an atom consisting of a heavy nucleus orbited by electrons.  Such a system ought to collapse, as accelerated charges radiate energy away.  Bohr's quantized model  would explain why it doesn't.

Nobel 1908   |   Encyclopedia of New Zealand   |   Wikipedia

 Paul Langevin 
 (1872-1946) Paul Langevin   (1872-1946)

Langevin made his mark in many fields of physics, including magnetism.  It is said that he had an affair with Madame Curie...  Two of their respective grandchildren are physicists married to each other  (Michel Langevin & Irène Langevin-Joliot).

Biography   |   Wikipedia   |   Weisstein

 Th. de Donder 
 (1872-1957) Théophile de Donder   (1872-1957)

In 1922, he defined  chemical affinity  in terms of the change in the  free enthalpy  (DG).  He founded the thermodynamics of irreversible processes, which led his student Ilya Prigogine (1917-2006) to a Nobel prize.  He was a friend of Einstein.

1899 doctorate   |   Wikipedia   |   Weisstein

 Fritz Hasenohrl  
 (1874-1915) Friedrich "Fritz" Hasenöhrl   (1874-1915)

Fritz Hasenöhrl had been a student of Boltzmann and Stefan at the University of Vienna,  where he suceeded Boltzmann as head of theoretical physics in 1907.  He had a profound influence on his student  Erwin Schrödinger.  He was killed in action in 1915.

University of Vienna   |   Wikipedia

 de Broglie

 Maurice de Broglie
 (1875-1960) Maurice de Broglie   (1875-1960)

He resigned his French navy commission in 1904 and worked under Paul Langevin.  He opened a private  X-ray laboratory  in 1908 and mentored successful physicists like Louis de Broglie and Louis Leprince-Ringuet (1901-2000; X1920n).

Académie Française   |   Wikipedia   |   EXAFS

 Georges Hostelet 
 (1875-1960) Georges Hostelet   (1875-1960)

Hostelet  obtained a scientific doctorate in 1905 and became a collaborator of  Ernest Solvay.  In 1915 he fought against the Germans occupying Brussels and was deported.  After the war, he became a renowned statistician and social scientist.

French Wikipedia

 Robert Goldschmidt 
 (1877-1935) Robert B. Goldschmidt, chemist   (1877-1935)

Robert Goldschmidt was a Belgian enthusiast for technological innovations.  He proposed standardized microfiche (microfilm) in 1906.  He launched the dirigible  Belgique  in 1907 and started the first regular radio broadcasts of concerts in 1914.

Brussels Cemetery   |   Wikipedia

 Edouard Herzen 
 (1877-1936) Edouard Herzen, Belgian chemist   (1877-1936)

Edouard Herzen  is one of only  7  people who participated in the two Solvay conferences of 1911 and 1927.  The others are:  H.A. Lorentz, Max Planck, Marie Curie, Martin Knudsen, Paul Langevin and Albert Einstein (the youngest participant in 1911).

New York Times (1923)

 James Hopwood Jeans 
 (1877-1946) Sir James Jeans   (1877-1946)

James Hopwood Jeans  was the first to propose  steady-state cosmology  (which had to be abandoned in 1965, when the Cosmic Microwave Background was discovered).  He became famous for popularizing Science after his retirement, in 1929.

Mnemonics for Pi   |   Rayleigh-Jeans distribution law (IR)   |   MacTutor   |   Wikipedia

 Albert Einstein 
 (1876-1955) Albert Einstein, physicist   (1879-1955)

In 1905, Einstein published on Brownian motion (existence of atoms) the photoelectric effect (discovery of the photon) and his own Special Theory of Relativity, which he would unify with gravity in 1915 by formulating the General Theory of Relativity.  In 1916, he discovered what led to  lasers.
 Signature of 
 Albert Einstein

Nobel 1921   |   MacTutor   |   Wikipedia   |   Bonn   |   Weisstein   |   AIP

 Owen Willans Richardson 
 (1879-1959) Sir Owen Willans Richardson   (1879-1959)

In 1901, he formulated what would become (in 1923) the  Richardson-Dushman law  of thermionics  ("vacuum tubes")  whereby the current density is  J = A T2 exp(-W/kT)  where A = 4pmqk2/h3 = 1201735 A/m2/K2  (Richardson's constant).

Nobel 1928   |   Wikipedia   |   The Electron Theory of Matter

 Paul Ehrenfest 
 (1880-1933) Paul Ehrenfest, physicist   (1880-1933)

In 1909, he remarked that  Special Relativity  makes the rim of a spinning disk shrink but not its diameter.  This contradiction with Euclidean geometry inspired Einstein's  General Relativity.  Ehrenfest was a great teacher and a pioneer of quantum theory.

MacTutor   |   Wikipedia   |   Weisstein

 Irving Langmuir 
 (1881-1957) Irving Langmuir, chemist   (1881-1957)

In 1906,  Irving Langmuir  obtained his doctorate under Walther Nernst  (who had devised an incandescent lamp a few years earlier).  He joined the  General Electric Research Lab  in 1909 and came up with the  gas-filled, coiled tungsten lamp.

Nobel 1932   |   Wikipedia

 Max Born
 (1882-1970) Max Born, mathematical physicist   (1882-1970)

Born's probabilistic interpretation of Schrödinger's  wave function  ended determinism in physics but provided a firm ground for  quantum theory.  Irene Born, the eldest of his 3 children, is the mother of Olivia Newton-John.
 Signature of Max Born (Bodensee, 1962)

Nobel 1954   |   Biography (2005)   |   MacTutor   |   Wikipedia   |   Weisstein

 Tryphon Tournesol 
 (a.k.a. Cuthbert Calculus)

 Auguste Piccard (1884-1962)
 1932 portrait by Robert Kastor Auguste Piccard, physicist   (1884-1962)

Swiss-born Belgian physicist who designed ships to explore the upper stratosphere and the deep seas (bathyscaphe, 1948).  He inspired  Hergé  for the character of  Tryphon Tournesol,  who debuted in 1944, as the inventor of a shark-shaped submarine.
 Signature of 
 Auguste Piccard

Auguste & Jean Piccard   |   Wikipedia

 Peter Debye 
 (1884-1966) Peter Debye, chemist   (1884-1966)

In 1912, Debye pioneered the use of dipole moments for asymmetrical molecules and extended Einstein's theory of specific heat to low temperatures by including low-energy  phonons.  He analyzed thermal attenuation in X-ray scattering (1914/1915).

Nobel 1936   |   Wikipedia

 Emile Henriot 
 (1885-1961) Emile Henriot   (1885-1961)

Emile Henriot  was born in Besançon, obtained his doctorate under Marie Curie  (in 1912)  and taught at ULB.  He detected the natural radioactivity of potassium and rubidium.  He made ultracentrifuges possible and pioneered the electron microscope.



 Niels Bohr 
 (1885-1962) Niels Bohr, physicist   (1885-1962)

In 1913, Bohr started the quantum revolution with a model where the  orbital angular momentum  of an electron only has discrete values.  He spearheaded the  Copenhagen Interpretation  which holds that quantum phenomena are inherently probabilistic.
 Signature of Niels Bohr

Nobel 1922   |   Wikipedia   |   Coat of Arms

 Frederick Alexander Lindemann, 
 Viscount Cherwell (1886-1957) Frederick Alexander Lindemann   (1886-1957)

Frederick Lindemann  confirmed Einstein's basic predictions concerning heat capacities at low temperatures.  He would later become a scientific advisor to  Winston Curchill.  He was made  Lord Cherwell  in 1941 and  Viscount Cherwell  in 1956.

Wikipedia   |   NNDB

 Erwin Schroedinger 
 (1887-1961) Erwin Schrödinger, physicist   (1887-1961)

In 1926, Schrödinger matched observed quantum behavior with the properties of a continuous nonrelativistic wave obeying the Schrödinger Equation.  In 1935, he challenged the  Copenhagen Interpretation,  with the famous tale of Schrödinger's cat.
 Signature of 
 Erwin Schroedinger

Dublin  |  Nobel 1933 (lecture)  |  Wikipedia  |  MacTutor  |  FB

 Ralph H. Fowler  
 (1889-1944) Sir Ralph Howard Fowler   (1889-1944)

From 1922 to 1939,  Ralph H. Fowler  (FRS 1925, knighted in 1942)  supervised 15 FRS and 3 Nobel laureates.  In 1923, he introduced Dirac to quantum theory.  He held the Chair of Theoretical Physics at the  Cavendish Laboratory  (1932).

MacTutor   |   Wikipedia

 Leon Brillouin  
 (1889-1969) Léon Nicolas Brillouin   (1889-1969)

In 1926,  Léon Brillouin  discovered the solid-state Brillouin zones.  He was a great-grandson of Charles Briot (1817-1882) a grandson of Éleuthère Mascart (1837-1908)  and the son of  Marcel Brillouin (1854-1948) who had been invited in 1911.

Biography   |   Wikipedia

 William Lawrence Bragg  
 (1890-1971) William Lawrence Bragg   (1890-1971)

In 1915,  Lawrence Bragg  was awarded the Nobel prize for physics jointly with his father  Sir William Henry Bragg  for their work on the analysis of the structure of crystals using X-ray diffraction, as pioneered by  Max von Laue  (Nobel 1914).

Nobel 1915   |   Wikipedia

 de Broglie

 Louis de Broglie
 (1892-1987) Louis de Broglie, physicist   (1892-1987)

In 1923, de Broglie proposed that any particle has wavelike properties, with a  wavelength  inversely proportional to its momentum  (this helps justify Schrödinger's equation).  He predicted  interferences  for an electron beam hitting a crystal.
 Signature of Louis de Broglie (1970)

Nobel 1929   |   Wikipedia   |   MacTutor

 Arthur Holly Compton
 (1892-1962) Arthur Holly Compton   (1892-1962)

Compton was professor of physics at Washington University  (St. Louis, MO).  In 1922, he figured that X-rays collide with electrons as if they were relativistic particles, so their frequency shifts according to the angle of deflection  (Compton scattering).

Nobel 1927   |   St. Louis Walk of Fame   |   Wikipedia   |   AIP   |   Time Cover (1936-01-13)

 Hans Kramers
 (1894-1952) Hendrik A. "Hans" Kramers   (1894-1952)

In 1916, as a young Dutchman on a trip to Copenhagen, Hans Kramers was the first foreign scholar to seek out Niels Bohr.  He became his assistant and helped develop what became known as  Bohr's Institute, where he worked on  dispersion theory.

NNDB   |   Academic Genealogy   |   Dirk ter Haar   |   Wikipedia

 Wolfgang Pauli 
 (1900-1958) Wolfgang [Ernst] Pauli, physicist   (1900-1958)

In 1925, Wolfgang Pauli formulated the  exclusion principle  which explains the entire table of elements.  His Godfather was Ernst Mach.  Pauli's sharp tongue was legendary; he once said about a bad paper:  "This isn't right; this isn't even wrong."

Nobel 1945   |   Wikipedia   |   Video Tribute

 Werner Heisenberg 
 (1901-1976) Werner Heisenberg   (1901-1976)

In 1925, Werner Heisenberg replaced Bohr's semi-classical orbits by a new quantum logic which became known  as matrix mechanics  (with the help of Born and Jordan).  The relevant noncommutativity entails  Heisenberg's uncertainty principle.

Nobel 1932   |   Wikipedia   |   MacTutor

 Paul Adrien Maurice 

 Paul Dirac 
 (1885-1962) Paul Adrien Maurice Dirac   (1902-1984)

In 1925, Paul Dirac came up with the formalism on which quantum mechanics is now based.  In 1928, he discovered a relativistic wave function for the electron which predicted the existence of  antimatter,  before it was actually observed.
 Signature of P.A.M. Dirac (Bodensee, 1962)

Nobel 1933   |   Wikipedia   |   MacTutor

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