The famous picture of the fifth Solvay Conference 1927

The above was the famous picture from the historic fifth Solvay Conference in 1927. The twenty nine personalities in the picture are of general interest to public and in particular to science enthusiasts; seventeen of these participants obtained Nobel Prize, the greatest honour for a scientist, and with the exception of few, rest were nominated several times for the Prize. Below, a short description of these personalities are given. But, before that a few words about the Solvay Conference.

Ernest Solvay (16 April 1838 – 26 May 1922) was a Belgian Chemist and industrialist. In 1861 he developed a method to produce soda-ash (sodium bicarbonate) in large scale. By 1872, he perfected the process and patented it. Soda ash was used in soap as well in glass making and was in great demand. He built a factory to produce soda ash and by the end of 1800, most of the soda ash of the world was being produced using his process (Solvay process). As a result, he acquired considerable wealth, which he used for philanthropic purpose. In 1894 he established the “Institut des Sciences Sociales” (ISS) or Institute for Sociology, in 1903 “Solvay Business School,” both at the Free University of Brussels. Theoretical physics was Solvay’s hobby and he developed a mechanistic type model of gravity. While his model gave no new results, but he was greatly interested to draw attention of reputed scientists to his theory. Walther Nernst, the German physicist and chemist, most noted for formulating the third law of thermodynamics, and who received 1920 Nobel Prize for chemistry “in recognition of his work in thermochemistry,” was in social contact with Solvay. He thought of utilising Solvay’s hobby to benefit science in general, at the same time, fulfilling Solvay’s desire, i.e. bringing his theory to the attention of leading scientists. He proposed to organise a conference of leading scientists to discuss the present difficulties in their science and to whom Solvay can present his ideas. Thus began the famous series of Solvay Congress or Solvay Conferences. The first conference was held in October, 1911 in Brussels. Nernst selected only twenty five scientists to invite to the conference. Sir Ernest Rutherford, Henri Poincare, Paul Langevin, Max Plank, Hendrik Lorentz, Marie Curie and Albert Einstein (youngest invitee) among others attended the conference. The costs of the conference, including the traveling expenses to Brussels, living expenses and a remuneration of 1000 francs to the participants was borne by Solvay. In the opening address, Solvay presented a summary of his theory. Conferees then discussed new developments in physics, out of modesty, none made any comments on Solvay’s theory. Nevertheless, Solvay was happy to present his ideas to leading scientist and later funded few more conferences.

The 1927 Solvay conference “On Electrons and Photons” was the fifth in the series and possibly was the most important conference in the series. The conference established Quantum Mechanics as valid investigating method of physics, culminitating a long drawn struggle between ‘scientific realists’ and ‘instrumentalists.’ Realists, represent by Einstein in the conference, believed that reality can be known without experience, ‘instrumentalists,’ represented by Neils Bohr, took the opposite view, without experience reality cannot be known. The conference witnessed the great debate between Einstein and Bohr, Einstein, disenchanted with Heisenberg’s uncertainty principle, remarked “God does not play dice”. Bohr replied: “Einstein, stop telling God what to do.” Einstein declined to talk at the conference and during the sessions, he kept mostly silent, but the formal meetings were not the only place of discussion. All the participants were staying in the same hotel, and there in the dining hall Einstein was much livelier. Otto Stern gave a first-hand report, “Einstein came down to breakfast and expressed his misgivings about the new quantum theory, every time [he] had invented some beautiful experiment from which one saw that [the theory] did not work… Pauli and Heisenberg, who were there, did not pay much attention, “ah, well, it will be all right, it will be all right.’ Bohr on the otherhand, reflected on it with great care and in the evening, at dinner, we were all together and he cleared up the matter in detail

With this background to the fifth Solvay conference, let us know the personalities in the picture;

The back row (standing) from left:

(1) Auguste Piccard (28 January 1884 – 24 March 1962), Swiss physicist and inventor. Known for designing helium filled balloon. On 27 May 1931, he and his friend reached a record altitude of 51,775 ft in his designed balloon. Nominated for Nobel Prize in Physics in 1932 and 1933 but didn’t get it.

(2) Emile Henriot (2 July 1885 – 1 February 1961) was a French chemist, but spent his entire scientific career in Belgium. He first showed definitively that potassium and rubidium are naturally radioactive.

(3) Paul Ehrenfest (18 January 1880 – 25 September 1933), Austrian-Dutch theoretical physicist. Made major contributions in statistical and quantum physics. He was a close friend of Albert Einstein. He used to suffer from depression and killed himself. In 1929, he nominated Paul Langevin and Pierre Weiss for physics Nobel. Himself was never nominated for the Prize.

(4) Edouard Herzen (1877–1936) was a Belgian chemist. He collaborated with industrialist Ernest Solvay, and participated in the first, second, fourth, fifth, sixth and seventh Solvay Conferences. Nominated Paul Langevin for Physics Nobel in 1929, he himself however was not ever nominated for Nobel.

(5) Theophile de Donder (19 August 1872 – 11 May 1957) was a Belgian mathematician and physicist famous for his work (published in 1923) in developing correlations between the Newtonian concept of chemical affinity and the Gibbsian concept of free energy. Considered father of irreversible thermodynamics. Strong supporter of Einstein’s relativity and in 1922 nominated Einstein for Nobel Prize. He himself was never nominated.

(6) Erwin Schrödinger (12 August 1887 – 4 January 1961), Austrian Physicist. Made fundamental contribution in Quantum physics and won Nobel Prize for physics in 1933, “for the discovery of new productive forms of atomic theory.” He shared the prize with P. A. M. Dirac.

(7) Jues Emile Verschaffelt (27 January 1870, – 22 December 1955) was a Belgian physicist. Was not a nominator or nominee.

(8) Wolfgang Pauli (25 April 1900 – 15 December 1958) was an Austrian-born Swiss and American theoretical physicist. One of the pioneers of quantum physics, formulated Pauli’s exclusion principle. In 1945, after having been nominated by Albert Einstein, Pauli received the Nobel Prize in Physics, “for the discovery of the Exclusion Principle, also called the Pauli Principle.”

(9) Werner Heisenberg (5 December 1901 – 1 February 1976) was a German theoretical physicist and one of the key pioneers of quantum mechanics. Formulated the uncertainty principle. In 1933, obtained the 1932 Nobel Prize for physics “for the creation of quantum mechanics, the application of which has, inter alia, led to the discovery of the allotropic forms of hydrogen”

(10) Ralph Howard Fowler (January 1889 – 28 July 1944) was a British physicist and astronomer.

(11) Leon Brillouin (August 7, 1889 – October 4, 1969) was a French physicist. Brillouin is a well known name to a physics students. He made important contributions to quantum mechanics, and solid state physics; WKB approximation, Brillouin zone, Brillouin function etc. Nominated five times for Physics Nobel prize, in 1955, 1957, 1960, 1965 (by two persons).

The Middle row from left:

(12) Peter Debye (March 24, 1884 – November 2, 1966) was a Dutch-American physicist and physical chemist. In 1912 he developed a method to determine the electrical charge distribution in a molecule, which became important in the mapping of molecular structures. In 1936, awarded Nobel Prize in Chemistry “for his contributions to our knowledge of molecular structure through his investigations on dipole moments and on the diffraction of X-rays and electrons in gases”

(13) Martin Knudsen (February 15, 1871 – May 27, 1949) was a Danish physicist. He is primarily known for his study of molecular gas flow and the development of the Knudsen cell. From 1914 to 1937, he was nominated 13 times for Nobel Prize in Physics.

(14) William Lawrence Bragg (31 March 1890 – 1 July 1971) was an Australian-born British physicist and X-ray crystallographer. In 1912 discovered Bragg’s law of X-ray diffraction, which is basic for the determination of crystal structure. He and his father William Henry Bragg, jointly won the 1915 Nobel Prize in Physics, “for their services in the analysis of crystal structure by means of X-ray.”

(15) Hendrik Anthony Kramers (2 February 1894 – 24 April 1952) was a Dutch physicist who worked with Niels Bohr to understand how electromagnetic waves interact with matter. Between 1949-1952, he was nominated for physics Nobel Prize six times.

(16) Paul Adrien Maurice Dirac (8 August 1902 – 20 October 1984) was an English theoretical physicist who is regarded as one of the most significant physicists of the 20th century. In 1928 Dirac formulated a fully relativistic quantum theory. The equation gave solutions that he interpreted as being caused by a particle equivalent to the electron, but with a positive charge. This particle, the positron, was later confirmed through experiments. In 1933, he obtained Nobel Prize for Physics “for the discovery of new productive forms of atomic theory.”

(17) Arthur Holly Compton (10 Sept. 1892-15 March 1962) was an American physicist. In 1922 in an experiment he discovered “Compton effect” which confirmed particle nature of electromagnetic radiation. In 1927, awarded Nobel Prize for Physics “for his discovery of the effect named after him.”

(18) Louis de Broglie (15 August 1892 – 19 March 1987) was a French physicist who made groundbreaking contributions to quantum theory. In his 1924 PhD thesis Louis de Broglie introduced the idea that particles, such as electrons, could be described not only as particles but also as waves, which was subsequently verified. The idea had great significance for the continued evolution of quantum mechanics. In 1929, he was awarded Nobel Prize for Physics “for his discovery of the wave nature of electrons.”

(19) Max Born (11 December 1882 – 5 January 1970) was a German physicist. He made important contribution in the development of quantum mechanics. He proved that Erwin Schrödinger’s wave equation could be interpreted as giving statistical (rather than exact) predictions of variables. In 1954, he was awarded Nobel Prize for Physics “for his fundamental research in quantum mechanics, especially for his statistical interpretation of the wave function.”

(20) Niels Henrik Bohr (7 October 1885 – 18 November 1962) was a Danish physicist. In 1913, Niels Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted. Bohr’s theory could explain why atoms emitted light in fixed wavelengths. In 1922, he was awarded Nobel Prize for Physics “for his services in the investigation of the structure of atoms and of the radiation emanating from them.”

The Front row from left:

(21) Irving Langmuir (January 31, 1881 – August 16, 1957) was an American physicist and chemist. Chemical reactions often take place more easily next to surfaces where substances in different phases, such as solids and gases, come in contact. In studies of incandescent light bulbs with rarefied hydrogen gas, Irving Langmuir discovered that a layer of hydrogen atoms only one atom thick formed on the inside of the incandescent light bulb. Further studies of oil films and other materials led him in 1917 to a theory postulating that surfaces resemble a chessboard on which every square can be occupied by only one atom or molecule. As a result, atoms or molecules that wind up next to each other can more easily react with one another. Langmuir is also known for inventing gas-filled incandescent lamp and the hydrogen welding technique. He was awarded the Nobel Prize in Chemistry in 1932 for “for his discoveries and investigations in surface chemistry”

(22) Max Planck (23 April 1858 – 4 October 1947) was a German theoretical physicist. When a black body is heated, electromagnetic radiation is emitted with a spectrum corresponding to the temperature of the body, and not to its composition. Existing theories could not explain the spectrum. Max Planck solved this problem in 1900 by introducing the theory of “quanta”, that is, that radiation consists of quanta with specific energies determined by a new fundamental constant, thereafter called Planck’s constant. In 1919 he received Nobel Prize in Physics “in recognition of the services he rendered to the advancement of Physics by his discovery of energy quanta.”

(23) Marie Sklodowska Curie (7 November 1867 – 4 July 1934) was a Polish and French physicist and chemist who conducted pioneering research on radioactivity. In 1903 she, her husband Pierre Curie and Henry Becquerel was awarded Physics Nobel prize “in recognition of the extraordinary services they have rendered by their joint researches on the radiation phenomena discovered by Professor Henri Becquerel.” In 1911 she obtained her second Nobel in chemistry “in recognition of her services to the advancement of chemistry by the discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element.” She was the first woman to win a Nobel Prize, the first person and only woman to win twice and the only person to win a Nobel Prize in two different sciences (Physics and Chemistry), and was part of the Curie family legacy of five Nobel Prizes (her daughter Irene Joliot Curie and son in law Frederic Joliot Curie won Nobel Prize in chemistry in 1935.

(24) Hendrik Antoon Lorentz (18 July 1853 – 4 February 1928) was a Dutch physicist. In 1892, Lorentz developed his electron theory, which posited that in matter there are charged particles, electrons, that conduct electric current and whose oscillations give rise to light. Hendrik Lorentz’s electron theory could explain Zeeman effect discovered by ieter Zeeman in 1896 that the spectral lines corresponding to different wavelengths split up into several lines under the influence of a magnetic field. In 1892. Lorentz also derived the transformation equations underpinning Albert Einstein’s theory of special relativity. In 1902, Lorentz and Pieter Zeeman were awarded Nobel Prize in Physics “in recognition of the extraordinary service they rendered by their researches into the influence of magnetism upon radiation phenomena.”

(25) Albert Einstein (14 March 1879 – 18 April 1955) the German-born theoretical physicist is possibly the most well-known personality in the world. Times magazine selected him as the person of the twentieth century. He greatly influenced modern science; altered our views on space-time, matter and energy, gave new interpretation to gravity etc. World’s most well known equation E=mc² was authored by him. He received the 1921 Nobel Prize in Physics “for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect.”

(26) Paul Langevin (23 January 1872 – 19 December 1946) was a French Physicist. He developed Langevin dynamics and Langevin equation. He was a prominent scientist and between 1910 to 1946, nominated for Nobel 25 times, but unfortunately, he did not get the prize.

(27) Charles-Eugene Guye (15 October 1866 – 15 July 1942) was a Swiss experimental physicist. Starting from 1907, for about a decade he studied motion of charged particles in electromagnetic fields, to test the FitzGerald-Lorentz contraction hypothesis and Lorentz transformation equations. In 1916 and 1921 Guye published his results which favored of the Lorentzian formulas and Einstein theory. Thereafter he gained prominence. He was nominated four times for the Nobel prize.

(28) Charles Thomson Rees Wilson (14 February 1869 – 15 November 1959) was a Scottish physicist. He was most noted for his invention of cloud chamber. He shared awarded 1927 Nobel prize for Physics with Arthur Compton. Wilson was awarded the prize “for his method of making the paths of electrically charged particles visible by condensation of vapour.”

(29) Owen Willans Richardson (26 April 1879 – 15 February 1959) was a British physicist. He is mostly known for his work on thermionic emission. When a metal wire is heated, the surrounding become electrically charged. In 1901 Richardson explained the phenomenon, declaring that when metal becomes hot, the electrons in the metal become so agitated that they are liberated from their atoms and cast into the air where they act as free charged particles. Richardson also formulated a law that describes the relationship between emissions of electrons and temperature. In 1929, he won the 1928 Nobel Prize in Physics “for his work on the thermionic phenomenon and especially for the discovery of the law named after him.”