Allgemeine Relativitätstheorie und Bewegungsgesetz. Offprint from Sitzungsbericht der Preussischen Akademie der Wissenschaften. (THE PROBLEM OF MOTION IN GENERAL RELATIVITY). 6 January 1927, pp. 2-13

Berlin: Verlag der Akademie der Wiss, 1927. 1st Edition. FIRST EDITION, OFFPRINT ISSUE IN ORIGINAL PAPER WRAPS, VERY GOOD CONDITION. "Einstein and Grommer's work [treats] the particle as a singularity in the field, and attempts[s] to obtain the equations of motion by imposing conditions on the exterior field in the neighborhood of the singularity" (Stachel, Einstein from ‘B' to'Z', pp. 507). Weil 155.

In 1927, Einstein's research "concentrated on a new approach to the problem of the motion of particles in a general field theory" (Mehra, The Golden Age of Theoretical Physics, 997). He presented his work, conducted with Jakob Grommer in this report.

Einstein and Grommer here show that ‘in the case of a pure gravitational field the mechanical behavior of singularities can be derived,' a result which in Einstein's opinion ‘opened the possibility to obtain, on the basis of the field equations, a theory of matter characterized as discontinuities in space' (ibid, 997; Einstein and Grommer, 1927).

"After Einstein had tried for years to obtain a theory of material particles in a generalized field theory by describing these objects with the help of continuous functions, Einstein and Grommer now proposed ‘to consider elementary particles as singular points or singular world lines, respectively,' motivated by the observation ‘that both the equations of the pure gravitational field and the equations augmented by Maxwell's electromagnetic field possess simple spherically-symmetric solutions which contain a singularity' (ibid).

Finally they arrived at the result: In the approximation of the gravitational field obtained by solving linearized equations, the equation of motion for a singularity is completely determined - at least in the case of equilibrium - and corresponds to the law of a geodetic line" (ibid). CONDITION & DETAILS: Berlin: Verlag der Akademie der Wiss. Pp. 2-13. Offprint in original wraps. (10 x 7.25 inches; 250 x 181mm). Toning at the edges & bearing the ownership stamp of "Friedrich Wilhelm Ritter" (W. F. Ritter) 1839-1929. Ritter had a large library. Very good condition.