The Solvay Conference

The development of quantum theory in the early part of the twentieth century was a major scientific revolution. It brought new ideas to the heart of physics, but it was also a revolution in chemistry. Quantum mechanics proved to be the crucial understanding that sparked the evolution of atomic and molecular spectroscopy. 

By 1927, Heisenberg, Bohr, and Max Born had developed an interpretation of the square of fhe wavefunction as a probability density. Schrodinger never accepted this interpretation, preferring to regard the wavefunction as a vibrational amplitude. Nonetheless, what was called the new quantum theory was now in place. 

1 Evaluate the probability density of fhe n = 0, 2, 4, and 6 (normalized) states of the harmonic oscillator at the point x = 0. Is there an apparent trend in these values  

2 At what value or values of x is the probability density function of the n = 1 wavefunction of the harmonic oscillator at maximum value  

Find the degeneracy of the first four energy levels of a particle in a three-dimensional box with the lengths of the sides related as = 161 = 4/.  

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Jagdish Mehra, The Solvay Conference in Physics Aspects of the Development of Physics since 1911 (Dordrecht Reidel, 1975) xv. 

A few weeks before the first Solvay chemistry conference in 1922, French chemists signed a letter declining to reestablish relations among chemists of Western and Central Europe. A copy of this letter, 3 April 22, is in the Donnan Papers, UCL. On the Solvay conferences, see M. J. Nye, "Chemical Explanation and Physical Dynamics Two Research Schools at the First Solvay Chemistry Conference, 19221928," Annals of Science 46 (1989) 461480. 

The theory of quanta has been a central preoccupation of the Solvay Conference since the first Solvay Conference on Physics, which took place in 1911. On that occasion, the fundamental discrepancies between classical theory and experimental data, which appeared at the beginning of the century, were discussed by major figures of modem science like Marie Curie, Albert Einstein, Max Planck, Henri Poincare, and many others. 

Allow me to express my gratitude for the support that the Belgian Royal Family has always given to the Solvay Institutes. We most regret that the King who has personally always graced the Solvay conferences by his presence cannot attend today as he had previously hoped. 

Einstein became a member of the Scientific Committee and took an active part in the discussions on quantum mechanics, which was the theme of the 1927 Conference. Indeed, the famous Einstein-Bohr discussions on classical determinism versus the quantum statistical causality took place in Brussels at the Solvay Conferences of 1927 and 1930, and continued thereafter. 

The paper by Max Born on Quantummechanik des Stossvorgange, in which he had proposed the statistical interpretation of the wave function, had appeared in 1926.32 Niels Bohr had presented his principle of complementarity at the Como Conference in September 192733 and Heisenberg had formulated the uncertainty principle shortly before the Solvay Conference.34... 

Frederick Joliot and Irene Curie discussed the "/-rays emitted in association with neutrons by berillium irradiated with a particles and reported to have observed under the same conditions also the emission of fast positrons. The origin of these particles was not yet clear at the time of the Solvay Conference. It was understood by the same authors a few months later when they discovered the artificial radioactivity induced by a-particle bombardment which normally takes place by emission of positrons. 

A third and last theoretical item treated by Feynman was Dispersion Theory, discussed in greater detail by other participants in the Solvay Conference. 

Already in 1964 Zweig and Gell-Mann had postulated the existence of quarks as building blocks of hadrons, ihus establishing the premises necessary for a dynamical interpretation of the SU(3) already well-established symmetry.82 At the time of the Solvay conference, however, the quark hypothesis was considered only as a convenient model. 

This is the last of the Solvay Conferences on Physics devoted to sub-nuclear particles in spite of the fact that the progress undergone by this field since 1967 has been amazing. The main reason was that many conferences were held each year on this general subject as well as on various parts of it, so that the Scientific Committee for Physics felt it would be better to turn its attention to other subjects less frequently dealt with in international conferences. 

I am now at the end of my series of flashes on the Solvay Conferences in Physics. I hope that, in spite of its shortness and incompleteness, it may help in stimulating two kinds of considerations. Those of the first kind regard the extraordinary develoment undergone during the last 70 years by our views on the physical world, many parts of which in present days appear to be dominated by a few general concepts, such as those of exact and approximate symmetry, and to be treatable by mathematical procedures such as the application of the renormalization group. The other kind of considerations concerns the role that the Solvay Conferences in Physics have played in the development of physics during the last 70 years, and the unique value they will maintain, even in the future, as sources of information for the historians of science. 

J. Mehra, The Solvay Conferences on Physics, D. Reidel, Dordrecht and Boston, 1975. 

These remarks can be found in the few pages of introduction to the album of photographs of the participants in the Solvay Conferences in Physics, published in 1961, on occasion of the celebration of 50 years after the First Solvay Conference. These pages are based on the unpublished paper Jean Pelseneer, Historique des Instituts Intemationaux de Physique et de Chimie Solvay, depuis leur fondation jusqu it la deuxilme guerre modiale, Bruxelles, 1946. 

On an occasion such as the present, three distinctive aims of the Solvay Conferences on Chemistry warrant special mention. First, as earlier speakers have said, they are international. Second, they are elitist in regard to the small number of invited papers on the chosen theme. Third, their themes have been chosen so far as possible because they have a riverhead character from which hopefully much further flow of chemical knowledge might be foreseen. 

The first part of the Conference was devoted to the historical role of the Solvay Institutes, and in particular of the Solvay Conferences on Physics and Chemistry, in promoting international scientific cooperation. The second part was devoted to some aspects of chemical evolution. This subject comprises an impressive number of different, yet complementary, questions having an interest in their own right. 

Back in Leningrad the following year Gamow received notice from his govermnent that he was officially delegated to the Solvay Conference. I... 

After they had identified the positrons they had missed before, the Joliot-Curies had started up their cloud chamber again and looked for the new particle in other experimental arrangements. They found that if they bombarded medium-weight elements with alpha particles from polonium, the targets ejected protons. Then they noticed that lighter elements, including in particular aluminum and boron, sometimes ejected a neutron and then a positron instead of a proton. That seemed evidence for a compound proton. They presented their evidence with enthusiasm as a report to the Solvay Conference. 

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