Chronology of Milestone Events in Particle Physics - POINCARE 1905
Chronology of Milestone Events in Particle Physics

POINCARE 1905

Poincare, H.;
Sur la Dynamique de l'Électron / On the Dynamics of the Electron
Compt. Ren. 140 (1905) 1504; Rend. del Circ. Mat. di Palermo 21, 129 (1906);

Reprinted in
(translation into English) A. A. Logunov, On the articles by Henri Poincare. JINR Publishing Department, Dubna (1995).

Motivation
It would seem at first sight that the aberration of light and the optical and electrical effects related thereto should afford a means of determining the absolute motion of the Earth, or rather its motion relative to the ether instead of relative to the other celestial bodies. An attempt at this was made, indeed, by Fresnel, but he soon perceived that the Earth's notion does not affect the laws of refraction and reflection. Similar experiments, such as that using a waterfilled telescope, or any in which only the first-order terms relative to the aberration were considered, likewise yielded only negative results. The explanation of this was soon found; but Michelson, who devised an experiment where in the terms involving the square of the aberration should be detectable, was equally unsuccessful.
This impossibility of experimentally demonstrating the absolute motion of the earth appears to be a general law of Nature; it is reasonable to assume the existence of this law, which we shall call the relativity postulate, and to assume that it is universally valid. Whether this postulate, which so far is in agreement with experiment, be later confirmed or disproved by more accurate tests, it is, in any case, of interest to see what consequences follow from it. (Extracted from the introductory part of the paper.).

Related references
See also
H. A. Lorentz, Proceedings of the Section of Sciences, Koninklijke Akademie van Wetenschappen te Amsterdam 6 (1904) 809-831;

Record comments
Introduction of the relativity principle as an overall law of nature valid for all forces including the gravitational one. Formulation of the equation of the relativistic mechanics and transformation laws for electromagnetic field and current. Establishing of the Lorentz group as a symmetry group of nature. First proposal to modify Newtonian theory of gravity on the basis of the relativity principle. Prediction of the gravitational waves propagating with the speed of light.
    
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