FIRST PRINTING IN ORIGINAL WRAPPERS of Poincaré's famous St. Louis speech on “relativity,” anticipating Einstein’s discovery the following year.
In 1904, Poincaré delivered a lecture “to the International Congress of Arts and Science at St. Louis. ‘What is the aether, how are its molecules arrayed, do they attract or repel each other?’ He expressed his unease with the idea of an absolute velocity: ‘If we succeed in measuring something we will always have the freedom to say that it is not the absolute velocity, and if it is not the velocity relative to the aether, it can always be the velocity relative to a new unknown fluid with which we would fill space.’ He gently chides Lorentz for his accumulation hypotheses, and then he goes beyond Lorentz in treating local time as a physical concept. He considers two observers in uniform relative motion who wish to synchronize their clocks by means of light signals. ‘Clocks regulated in this way will not mark the true time, rather they mark what one may call local time.’ All phenomena seen by one observer are retarded relative to the other, but they are all retarded equally (Poincaré points out) and ‘as demanded by the relativity principle [the observer] cannot know whether he is at rest or in absolute motion.’ Poincaré is getting close...
“Poincaré concluded this lecture with another of his marvelous visions: ‘Perhaps we must construct a new mechanics, of which we can only catch a glimpse,... in which the velocity of light would become an unpassable limit.’ But, he added, ‘I hasten to say that we are not yet there and that nothing yet proves that [the old principles] will not emerge victoriously and intact from this struggle’” (Pais, Subtle is the Lord, 127-8).
In: Bulletin des Sciences Mathematiques, Vol. 28, pp. 302-324. Paris: Gauthier-Villars, 1904. Octavo, original wrappers. Spine mostly perished, chipping to wrappers edges. Housed in custom box. Extremely rare in fragile original wrappers.