In 1801, the year of the discovery of Ceres, Johann Georg von Soldner calculated with classical means the gravitational deflection of a lightray grazing the surface of the Sun as 0.84”. According to General Relativity (GR) and using present-day data the deflection amounts to 1.75”. The formula for the deflection is derived with a classical method, with GR and as done by Soldner. The GR formula gives twice as large a deflection as the classical formula. It is shown that the formula of Soldner is equivalent to the classical one. Soldner’s numerical calculation of the classical deflection by the Earth comes out a factor 6.9 larger than using present-day data. This discrepancy is for a factor 6.25 due to a mistaken value for the velocity of the grazing lightray. This factor 6.25 can numerically be accounted for by assuming Soldner made a conceptual mistake related to the Axial Tilt of the Earth. The remaining discrepancy is due to the use of data less accurate than the present-day data. Soldner’s numerical calculation of the deflection by the Sun comes out correctly to the data of those days. In case of the Sun he did not give any further information regarding the data he used. A reconstruction reveals that for the surface gravity of the Sun he used a value close to the present-day value.
References
[1]
von Soldner, J.G. (1801) über die Ablenkungeines Lichtstrahls von seiner geradlinigen Bewegung, durch die Attraktion eines Weltkorpers, an welchem er nahe vorbei geht. Berliner Astronomisches Jahrbuch, pp. 161-172. An English translation can be found on Wikisource.
McVittie, G.C. (1965) General Relativity and Cosmology. 2nd edition, Chapman and Hall LTD, pp. 91-96.
[4]
Momeni, D. (2010) Bending of Light: A Classical Analysis. http://ui.adsabs.harvard.edu/abs/2009arXiv0903.1031M/abstract
[5]
Huang, F.Y. (2017) Accurate Solution to the Gravitational Bending of Starlight by a Massive Object. Journal of Modern Physics, 8, 1894-1900. https://doi.org/10.4236/jmp.2017.811112
[6]
Mignonat, M. (2018) Soldner Had Found in 1802 the Deflection of the Light of the Sun as General Relativity Shows. Journal of Modern Physics, 9, 1545-1558. https://doi.org/10.4236/jmp.2018.98095
[7]
Sauer, T. (2021) Soldner, Einstein, Gravitational Light Deflection and Factors of Two. Annals of Physics, 533, Article ID: 2100203. https://doi.org/10.1002/andp.202100203
[8]
Lotze, K.-H. and Simionato, S. (2021) Henry Cavendish and the Effect of Gravity on Propagation of Light: A Postscript. The European Physical Journal H, 46, Article No. 24. https://doi.org/10.1140/epjh/s13129-021-00027-4
[9]
Ginoux, J.-M. (2021) Albert Einstein and the Doubling of the Deflection of Light. Foundations of Science. https://doi.org/10.1007/s10699-021-09783-4
[10]
Trumpler, R. (1923) Historical Note on the Problem of Light Deflection in the Sun's Gravitational Field. Publications of the Astronomical Society of the Pacific, 35, No. 206. https://doi.org/10.1086/123302
[11]
Treder, H.-J. and Jackisch, G. (1981) On Soldner’s Value of Newtonian Deflection of Light. Astronomische Nachrichten, 302, 275-278. https://doi.org/10.1002/asna.2103020603
[12]
Stefanini, L. (2017) A Misunderstanding in Soldner’s Interpretation of the Gravitational Deflection of Light. Lettera Matematica, 4, 167-172. https://doi.org/10.1007/s40329-016-0150-4
[13]
Lenard, P. (1921) über die Ablenkung eines Lichtstrahls von seiner geradlinigen Bewegung durch die Attraktion eines Weltkorpers , an welchem er nahe verbeigeht; von J. Soldner, 1801. Mit einer Vorbemerkung von P. Lenard. Annalen der Physik, 65, 593-604.
[14]
Comenius, J.A. (1668) Via Lucis, Chapter 10. University Press, Liverpool, Hodder & Stoughton LTD, London.
[15]
Jaki, S.L. (1978) Johann Georg von Soldner and the Gravitational Bending of Light, with an English Translation of his Essay on It Published in 1801. Foundations of Physics, 8, 927-950. https://doi.org/10.1007/BF00715064