Roberto Martins Searching for the Ether
Fig. 1. Leopold Courvoisier (about 30 years old).4
The papers describing those researches were published in several scientific journals - especially Astronomische Nachrichten, Physikalische Zeitschrift and Zeitschrift für Physik. His work was largely ignored and had a small impact. A few authors (e.g. Ernest Esclangon and Dayton Miller) who also claimed they had observed effects due to the ether have cited his works.
4 Portrait painted by Alexander Perandin Moreira, from a photo published in Carl V. Charlier and Folke Engström (eds.), Porträtgallerie der astronomischen Gesellschaft (Stockholm, 1904). 17.
Searching for the Ether
Historians of science have also neglected those researches,5 although they present the largest set of empirical results that was ever published against the theory of relativity by a professional scientist. Courvoisier exhibited an outstanding theoretical and experimental skill, and his results can be regarded as one of the strangest puzzles in the history of relativity.
Courvoisier and relativity
Courvoisier's earliest involvement with relativity was an outcome of his routine measurements of star positions. In the beginning of the twentieth century, Courvoisier had noticed that the right ascension and declination of fixed stars suffered a small influence when they are observed close to the Sun. As this influence had a period of one year, he called it “annual refraction”. His first work on the subject was published in 1905,6 that is, much earlier than the development of the general theory of relativity. In 1911, after the publication of Einstein’s early thoughts on the gravitational deflection of light rays, Erwin Freundlich recalled that Courvoisier's work had exhibited an effect that was qualitatively similar to the one predicted by Einstein.7 Courvoisier interpreted the effect he had measured as due to refraction of light by a denser medium around the Sun, not as a consequence of relativity. It seems that Courvoisier’s opposition to Einstein's work grew steadily from this time onward and he became one of the most intransigent supporters of ether theory after the theory of general relativity received strong confirmation (the eclipse measurements), in 1919. Courvoisier's main anti-relativistic work, however, is not directly linked to “annual refraction”.8
Courvoisier accepted the existence of a static ether, similar to the medium proposed in the early eighteenth century by Augustin Fresnel. That theory led to the conclusion that there could be no first-order influence of the motion through the ether upon optical experiments performed in the Earth. Besides that, the negative outcome of the Michelson-Morley experiment required an additional hypothesis, and Courvoisier accepted that motion
5 Klaus Hentschel studied some of Courvoisier's works but he did not analyse the researches described in this paper. See Klaus Hentschel, “Freundlich, Erwin, Finlay and testing Einstein’s theory of relativity”, Archive for history of exact sciences, xlvii (1994), 143-201; Klaus Hentschel, The Einstein tower. An intertexture of dynamic construction, relativity theory, and astronomy (Stanford, 1997).
6 Leopold Courvoisier, “Kinemara's Phänomen und die ‘jährliche Refraktion’ der Fixsterne”, Astronomische Nachrichten, clxvii (1905), 81-106.
7 Hentschel, The Einstein tower (reí. 5), 10-11.
8 Klaus Hentschel, The Einstein tower (ref. 5), 11, claimed that Courvoisier derived the speed of the Earth’s motion through the ether from his data on annual refraction, but his data for the computation of the speed of the Earth was taken from completely independent sources, as will be shown in this paper.