Zur Affinen Feldtheorie. [Relativity]

Berlin: Berlin: Sitzungsberichte der Preussischen Akademie der Wissenschaften, XVIII, 1923. First Thus. Soft cover. First Thus. Soft cover. Einstein, Albert (1879-1955). Zur affinen Feldtheorie. Offprint from Sitzungsberichten der Preussischen Akademie der Wissenschaften 1923. XVIII. 8vo.,4, [137-140] First edition. Orange wrappers. A fine fresh copy in the rare off-print form marked with an asterisk by Weil, denoting a major paper ("Sonderabdruck") & deemed of sufficient interest that a translation was published in Nature Magazine. "Einstein's attempts to formulate a unified field theory [the theoretical framework to account for the fundamental forces of nature.] stemmed from his dissatisfaction with the general relativity theory, which did not adequately incorporate the electromagnetic field into the geometry of space-time". Einstein's first investigation of Weyl's ideas, published in the present paper which Weyl had begun working on in 1918. Weyl was investigating the possibility of constructing a unified field theory preserving the dimensionality of space-time while formally altering its geometry, making it a special case of the class known as affine geometries*. However Einstein later rejected Weyl's theory. "Weil No. 132*; Schilpp--Shields No. 171; Alicke No.113; Norman Library 698; Boni 141. *Affine Geometry is not concerned with the notions of circle, angle and distance. It's a known dictum that in Affine Geometry all triangles are the same. In this context, the word affine was first used by Euler (affinis). In modern parlance, Affine Geometry is a study of properties of geometric objects that remain invariant under affine transformations (mappings). Affine transformations preserve collinearity of points: if three points belong to the same straight line, their images under affine transformations also belong to the same line and, in addition, the middle point remains between the other two points." The early Offprints from "Sitzungsberichten." are called "Sonderabdruck" up to Weil No.165 (including this). From Weil 166 they are called "Sonderausgabe.". - Before 161 (up to 160) the Offprints do not have separate title and pagination (the pagination follows the numbering in the periodical). From 166 the Offprint has both separate printed title and pagination. - ( So Weil Nos 161-165 is still "Abdruck", but with separate title and pagination).