Albert Einstein | Autograph letter signed, to Alfred Bucherer, on electrons and Special Relativity, 25 November 1908

Albert Einstein

Autograph letter signed ("A. Einstein"), to Alfred Bucherer, expressing his admiration for the precision of Bucherer’s experiments on the deflection of beta-rays, answering questions on the properties of electrons and Special Relativity (“…Der Unterschied zwischen der kinetischen Energie des Elektrons und seiner elektromagnetischen Energie muss nach der Relativitätstheorie darin gesucht werden, dass ein Kräften unterworfener starren Körper eine seiner Kraftbeanspruchungen entspr. (positive oder negative) Masse besitzt… […According to the theory of relativity, the difference between the kinetic energy of the electron and its electromagnetic energy must be sought in the fact that a rigid body subjected to forces has a mass (positive or negative) corresponding to the forces exerted on it…]), and concluding by noting where his theory remains incomplete, in German, on graph paper, 3 pages, 8vo (210 x 122mm), Bern, 25 November 1908, slight splitting at folds, fraying at outer edge, light creasing, remains of mount

“…Wir müssen ein theoretisches Bild fordern, welches nicht dazu zwingt, für jedes Element der Materie ein relatio zu ihm reichendes Koordinatensystem einzuführen….” [We must demand a theoretical picture that does not compel us to introduce a relative coordinate system for each element of matter.]

AN IMPORTANT AND UNPUBLISHED LETTER DISCUSSING ASPECTS OF SPECIAL RELATIVITY.

Following Alfred Bucherer’s successful demonstration that electrons behaved in a manner consistent with Einstein’s theory of Special Relativity (see previous lot), Einstein and Bucherer maintained a continued correspondence. In this letter, Einstein elaborates on his theory of the nature of electrons their transfer of mass. He lists theoretical difficulties in the model of electrons as rigid spheres; according to Einstein’s theories, they contracted in the direction of motion. Bucherer’s reply the following day (Einstein, Collected Papers, vol. 5, no. 128) shows that he was not fully convinced by Einstein’s arguments and provides his own hypothesis on how mass operated on electrons. He also responded to Einstein’s insistence that Special Relativity still needed to be fitted into a broader theoretical framework with his belief that “the ether-vortex theory of matter, in which ether and matter are of an identical nature, is most likely to lead to success.”