Searching for the Ether
In 1932 Courvoisier obtained new results, taking into account in this new paper some effects due to temperature and humidity. The new results obtained by him were
A = 50° ± 7°; D = +45° ± 18°; v = 498 ± 78 km/s
For the first time, Courvoisier's results were criticized and checked. In 1932, Rudolf Tomaschek and Walter Schaffernicht reported gravity measurements made with a new kind of gravimeter that was able to detect _0
changes Ag/g of 10 . The instrument was placed inside a cave in a mountain, where the temperature was constant to 0.001° C. No effect of the order of magnitude predicted by Courvoisier was observed.31
Eclipses of Jupiter’s satellites
It is well known that in 1879 James Clerk Maxwell wrote to David Peck Todd asking him about the possibility of computing the velocity of the solar system through the ether using available data on occultation of Jupiter’s satellites.32 Maxwell supposed that the motion of the solar system would produce an anisotropy of the speed of light that could be detected as a fluctuation of the times of occultation of Jupiter's satellites, observed from the Earth, with a period of about 12 years. Todd answered, however, that the measurements available at that time were not precise enough for such computations.
In 1930 Courvoisier published a paper where he presented an analysis of available observations of Jupiter's satellites and claimed that they led to a new determination of the velocity of the solar system relative to the ether.33 He used data relative to the three inner Galilean satellites published by the Johannesbourg observatory (1908-1926), comparing those measurements to those of the observatories of Cape Town, Greenwich and Leyden (1913-1924). He confirmed Maxwell's anticipation of a fluctuation with a period of about 12 years and obtained the following results:
A = 126° ± 10°; D = +20°; v = 885 ± 100 km/s Secular aberration of light
According to the theory of ether accepted by Courvoisier, the speed of light is constant relative to the ether, but could not be constant relative to the
31 Rudolf Tomaschek and Walter Schaffernicht, “Zu den gravimetrischen Bestimmungsversuchen der absoluten Erdbewegung”, Astronomische Nachrichten, ccxliv (1932), 257-66.
32 James Clerk Maxwell, “On a possible mode of detecting a motion of the solar system through the luminiferous ether”, Proceedings of the royal society ofLondon, xxx (1879-1880), 108-10.
33 Leopold Courvoisier, “Ableitung der ‘absoluten’ Erdbewegung aus beobachteten Längen der Jupiter-Satelliten”, Astronomische Nachrichten, ccxxxix (1930), 33-38.
Roberto Martins Searching for the Ether DIO 17
Earth: there should be an observable anisotropy of the speed of light due to the absolute motion of the Earth. He assumed that this would produce an observable difference in measurements of stellar aberration observed in different directions.34 Using the available data, Courvoisier obtained the following results:
A = 112° ± 20°; D = +47° ± 20°; v = 600 ± 305 km/s Final comments
Courvoisier's measurements of the absolute velocity of the Earth belong to the same group of Dayton Miller’s and Ernest Esclangon’s works.35 However, Courvoisier's work embodied a much wider and impressive group of measurements than those of his contemporaries.
Courvoisier measured the velocity of the Earth relative to the ether using several different methods. The effects he was searching for were very small (second order in v/c) but the results presented were significantly larger than the estimated experimental error. The measured values of the right ascension of the Earth's motion apex varied from 52° to 126°, with a strong concentration of values between 60° and 90°. The measured declination varied between +27° and +55°, most values falling between +34° and +46°. The values obtained for the speed of the Earth varied between 300 km/s and 927 km/s, most results falling between 500 km/s and 810 km/s.
What impact did Courvoisier’s work have? His researches were seldom cited. Miller and Esclangon did refer to some of his researches, because they were also reporting positive effects ascribed to the motion of the Earth through the ether. Besides those citations, there were just a few other references. General Gerold von Gleich, a well-known anti-relativist,36 did refer to Courvoisier’s results in two papers. In a short note, von Gleich mentioned fluctuations of the aberration constant that could be an indirect confirmation of Courvoisier’s results.37 In a second paper, von Gleich presented several independent confirmations of Courvoisier’s measurements of the motion of the solar system.38 He reported that Carl Wilhelm Wirtz and Gustaf Strömberg had evaluated this motion analyzing the velocities of spiral nebulae, obtaining speeds compatible with
34 Leopold Courvoisier, “Bestimmung der absoluten Translation der Erde aus der säkularen Aberration”, Astronomische Nachrichten, ccxli (1932), 201-12.
35 There is a detailed historical study of Miller’s work: Loyd S. Swenson, Jr., The ethereal aether. A history of the Michelson-Morley-Miller aether-drift experiments, 1880-1930 (Austin, 1972).
36 Joseph Wodetsky, “Gerold von Gleich”, Astronomische Nachrichten, cclxvi (1938), 63-4.
37 Gerold von Gleich, “Translation des Fixstemsystems und Aberrationskonstante”,
Astronomische Nachrichten, ccxli (1931), 201-02.
38 Gerold von Gleich, “Bemerkung zur absoluten Translation unseres lokalen Fixsternsystems”, Astronomische Nachrichten, ccxlii (1931), 273-8.