At the Metropole,´ a “Witches’ Sabbath” Autumn 1911, Brussels. A mythic congress, a phe- nomenal cast: Albert Einstein, Marie Curie, Henri Poincare,´ Max Planck, Paul Langevin, Maurice de Broglie and others reinvent science during the Solvay Congress, in the most beautiful hotel in the city. “Well, here it is!” Patrick Wielmans Was it really in this small room AN “ACT OF DESPAIR” opens the door of the Salon Einstein. that everything happened? In reality, On the first floor of the M´etropole, to Patrick Wielmans is not completely In reality the story started eleven the right of the monumental staircase certain. He inherited the informa- years earlier. In 1900, Max Planck traversing the imposing building on tion from his father, who himself in- formulated a theory based on a rev- the place de Brouck`ere, in the historic herited it from his grandparents, the olutionary idea: radiation and mat- centre of Brussels, the meeting room founders of the Metropole,` who were ter can only change their energies in is not very impressive. About forty also the hosts of the famous congress. the form of little indivisible packets. square metres, a bit of marble on the “Let us say that we are perhaps 90% cer- The idea of “quanta of energy” was wall, a long table in the middle. Com- tain”, he suggests. Opposite, in the born. The German physicist had not pared to the splendour of the grand same corridor, the Salon Langevin is found any alternative to describe cer- hˆotel, nothing very spectacular. Nev- also a possible candidate. tain experiments. But his theory, a ertheless, this place is the pride of complete break with the classical ap- both the establishment and its chief. proach, seemed to him so unreason- In was in this room, recalls Patrick The single image of the Solvay able, that he described it himself as Wielmans, that one of the most fa- Congress, which will be the first in an“Act of Despair.” mous pages in the history of science a long series, is a celebrated group Initially, it aroused little attention. was written. During the four days photograph. It does not let us de- But five years later, a young engi- between 30 October and 3 Novem- cide with certainty between the two neer in the Bern patent office, a cer- ber 1911, at the invitation of the in- salons: However it is not the place tain Albert Einstein, took up and fur- dustrialist and philanthropist Ernest which one wishes to immortalise, but ther radicalised Planck’s idea: it was Solvay, a score of the most brilliant the phenomenal casting of the event. not only the energy exchanges which spirits of the twentieth century filled Twenty four scholars, whose names were granular, but the very nature of these walls with esoteric reflections form, a century later, a major part radiation. Light itself should be com- on the profound nature of matter and of scientific textbooks: Albert Ein- posed of small granules of energy, the energy, opening the way to mod- stein, Marie Curie, Paul Langevin, famous quanta, which would not be ern physics—that which has given Henri Poincare,´ Max Planck, Hendrik called “photons” until much later. electronics, informatics, the internet, Lorentz, Arnold Sommerfeld, Mar- A third person, much less famous atomic fission and so on, which, for cel Brioullin1, Ernest Rutherford, Jean than Einstein or Planck, then played better or for worse, have moulded Perrin, James Jeans. Almost half of a key role in the genesis of the Solvay our epoch, and will mould future the participants have, or will have, a Congress. In 1906, a German physi- epochs. This meeting, which has Nobel Prize. Marie Curie will have cist and chemist, Walther Nernst, for achieved a mythic status, the first two of them. his part had established a “heat theo- Solvay Congress, was not only where rem”, which he was trying to validate a new physics was launched. Accord- by means of an ambitious series of ex- ing to the physicist and philosopher What are the greatest scholars of periments. Very rapidly, Nernst re- Etienne Klein (CEA), “It profoundly their time doing in a luxury hotel in alised that his work achieved its full changed the way in which science was Brussels? Who called them together, significance only within the frame- done”. and why? work of quanta. 1The father of Leon´ Brillouin, inventor of Brillouin zones 1 “Walther Nernst was very ambi- accepted, and thus consolidate his cal industry. tious”, recounts Franklin Lambert own works? “Nernst understood well Solvay was above all in spirit him- (Vrije Universiteit Brussel, Instituts that this would be too obvious” says self a scholar, the author of some Solvay), physicist, historian of sci- Franklin Lambert. “He knew he had to remarkable intuitions, such as the ence, and passionate exegist of this find another solution.” idea of the equivalence between mat- key moment in physics. “He wanted Nernst’s “solution” was called ter and energy, which he would for- the Nobel Prize. But he knew that, for Ernest Solvay. This man, a wealthy mulate in 1887, eighteen years be- this, quantum theory, at that stage very chemical-industrialist, a social and fore a certain Albert Einstein would controversial, had to be validated at the humane philanthropist, was one of establish it, incarnating it in the highest level.” For his own genius to the great patrons of his times. A bril- most celebrated formula of physics be recognised, it was necessary that liant self-taught man, he had discov- (E = mc2). Loving knowledge, and the ideas of Planck and Einstein be ered a method for the synthesis of strongly wishing to advance learn- recognised beforehand. soda, and in 1863 founded the soci- ing, he founded an institute for phys- Organise a conference at his place, ety which carries his name. It is still, iology at the Universit´elibre de Brux- in his institute in Berlin, to make a century and a half later, one of the elles in 1894, then a school of com- the theory of another German be finest jewels of the European chemi- merce, an institute for sociology.. 2 The first Solvay conference met in November 1911 in the Hotel M´etropole in Brussels. 24 scholars. Seated, from left to right: Walther Nernst, Marcel Brioullin, Ernest Solvay, Hendrik Lorentz, Emil Warburg, Jean-Baptiste Perrin, Wilhelm Wien, Marie Curie, Henri Poincare.´ Standing: Robert Goldschmidt, Max Planck, Heinrich Rubens, Arnold Sommerfeld, Frederick Lindemann, Maurice de Broglie, Martin Knudsen, Friedrich Hasenohrl,¨ Georges Hostelet, Edouard´ Herzen, James Jeans, Ernest Rutherford, Heike Kamerlingh Onnes, Albert Einstein, Paul Langevin. NEUTRAL TERRITORY Nernst and added several French sci- mans, a major family of brewers, who entists who had not originally been at the turn of the century were invest- Walther Nernst went to see Ernest on the programme: On the insis- ing in restaurants and hotels, the es- Solvay with a proposal to help in tence of the patron, Marie Curie, tablishment was a jewel of Art Nou- the resolution of the crisis then be- Marcel Brioullin and above all Henri veau. In 1891 the Wielemans broth- ing experienced within physics. The Poincare´ were to participate. This ers had purchased the grand build- crisis was real: Classical theory no choice would be decisive. ing with an imposing white facade in longer permitted any explanation of the style of Haussman on 31 Place de certain phenomena, and there was no As to the location, this decision was automatic. Solvay was Bel- Brouckere,` in which was located the consensus in favour of quantum the- General Bank for Savings and Pen- ory. “Ernest Solvay himself understood gian, the meeting would take place in Belgium, neutral territory, the cross- sions. They entrusted the transfor- the reality of this crisis, and wanted to mation into a hˆotelde luxe to the archi- participate in its resolution”, explains roads of Europe, frontier between the germanic and latin cultures. Brussels, tect Ged´ eon´ Bordiaux, and the dec- Jean-Marie Solvay, his great-great- oration and interior design to Alban grandson, who to this day continues capital of developing international- ism, would be the the city of the con- Chambon. They gave them complete to organise these “summit meetings” freedom in their tasks. on physics and chemistry. ference. And if Brussels was the con- Solvay enthusiastically adopted ference city, then the Metropole´ was The result was a cathedral—but Nernst’s idea: Bring together the the obvious choice of venue. a cathedral illuminated by electric- great scholars, let them confront each “At that time there was simply no ity and heated by steam. Columns, others’ ideas, and come to agree- other luxury hotel in Brussels”, com- arcades, stained glass, mirrors and ment about the reality of the famous ments Patrick Wielemans. In 1911 the gilding throughout, domed ceilings, quanta. But he amended the list establishment was already an institu- huge chandeliers; bronze, stucco, of invited participants proposed by tion. Founded in 1894 by the Wiele- rare woods, wrought iron, br`eche 2 de 2In English Numidian breccia, a highly decorative North African stone 3 Numidie.... ference: “Yesterday evening I had a plored Planck’s persistence in reject- Chambon drew inspiration from Frenchman on my right and an English- ing the idea of light quanta, be- the French Renaissance for the man on my left, and I was speaking to cause this would lead to the reform vestibule, from the Italian for the them both, one after the other!” Som- of Maxwell’s and Lorentz’s theory grand ballroom, from Hindu art for merfeld’s astonishment in the face of of electromagnetism. He was also the reception area, from the English what is today commonplace shows disappointed with Poincare’s´ skepti- style for the office and its lengthy that here Solvay invented a new way cism.