Hence, in May 1905, Poincaré and Einstein both had drafts of papers pertaining to the principle of relativity. Poincaré's draft led to a space-time mathematical theory of groups at the basis of which stood the postulate of relativity, and Einstein's draft led to a kinematical theory of relativity.She then goes on to give an assortment of reasons for crediting Einstein and not Poincare.
Like Einstein Poincaré adopted a definition of distant simultaneity. However, unlike Einstein, Poincaré did not discover the relativity of simultaneity. In 1902, Poincaré wrote a letter to the Royal Academy of Sciences in Stockholm recommending the candidacy of Lorentz for a Nobel Prize in Physics. In trying to persuade the Nobel committee about Lorentz's achievements, Poincaré wrote the following, 31I should have put this quote in my book. Lorentz got that 1902 Nobel Prize, and Poincare evidently understood the relativity of time, long before Einstein wrote his first paper in 1905. People sometimes argue that Lorentz and Poincare had the relativity formulas but did not take them seriously or appreciate the significance. This quote shows the opposite -- that the work was worthy of a prize for the best advance in physics.
"Why for example all the experiments devoted to demonstrating the Earth’s motion gave negative results? Evidently, there was one general reason behind this; this reason was discovered by Mr. Lorentz and he put it in a striking form with his ingenious invention of 'reduced time'. Two phenomena taking place in two different places can appear simultaneous even though they are not: everything happens as if the clock in one of these places retards with respect to that of the other, and as if no conceivable experiment could show evidence of this discordance. Now, according to Mr. Lorentz, the effect of the Earth’s motion would be only to give rise to a similar discordance that no experiment could reveal".
Weinstein has a lot of material showing Poincare's priority over Einstein, but makes comments like this:
In his 1905 Dynamics of the Electron Poincaré did not formulate the constancy of the speed of light as a postulate. He very likely objected to such a postulate, and he only accepted the relativity principle as a postulate.She says this as if Poincare somehow did not understand that the speed of light was constant. But his long 1905 relativity starts section 1 with:
Lorentz had adopted a particular system of units, so as to eliminate the factors 4pi in the formulas. I'll do the same, plus I choose the units of length and time so that the speed of light is equal to 1.Somehow she concludes, with the assistance and direction of Einstein editor John Stachel:
Poincaré's draft led to a space-time mathematical theory of groups at the basis of which stood the postulate of relativity, and Einstein's draft led to a kinematical theory of relativity. Poincaré did not renounce the ether. He wrote a new law of addition of velocities, but he did not abandon the tacit assumptions made about the nature of time, simultaneity, and space measurements implicit in Newtonian kinematics. Although he questioned absolute time and absolute simultaneity, he did not make new kinematical tacit assumptions about space and time. He also did not require reciprocity of the appearances, and therefore did not discover relativity of simultaneity: these are the main hallmarks of Einstein's special theory of relativity. Nevertheless, as shown by other writers, Poincaré's theory had influenced later scientists especially Hermann Minkowski.I don't know how she can say that Poincare did not have the new understanding of time when he cited that to get Lorentz a Nobel Prize in 1902.
Poincare certainly did require reciprocity of the appearances. He proved that there was a symmetry group making those appearances the same. Einstein did not do that.
She seems to understand that it was Poincare, not Einstein, that influenced Minkowski, and it was Minkowski's 1908 relativity formulation that was quickly adopted.
Weinstein also posted a paper on Did Poincaré explore the inertial mass-energy equivalence? She says:
Einstein was the first to explore the inertial mass-energy equivalence. ... In 1908 Einstein wrote the German physicist Johannes Stark, "I was a little surprised to see that you did not acknowledge my priority regarding the relationship between inertial mass and energy".Lorentz predicted relativistic masses in his 1899 paper:
this must take place in such a way that the same ion will have different masses for vibrations parallel and perpendicular to the velocity of translation. Such a hypothesis seems very startling at first sight.She acknowledges that Poincare wrote a 1900 paper on E=mc2 and says:
Einstein mentioned Poincaré's 1900 paper in this regard. He wrote that the simple formal considerations he had used were already contained in Poincaré's work, but he had preferred not to base himself on that work for the sake of clarity. 41If Einstein were honest, that letter to Stark would have credited Lorentz and Poincare.