First offprint of 2 papers by Einstein on Theodor Kaluza, 1927
Albert EINSTEIN: ZU KALUZAS THEORIE DES ZUSAMMENHANGES VON GRAVITATION UND ELEKTRIZITÄT. Sonderabdruck [Offprint]). Berlin: 1927.
Albert EINSTEIN: ZU KALUZAS THEORIE DES ZUSAMMENHANGES VON GRAVITATION UND ELEKTRIZITÄT. [Kalzuza's Theory on the Connection between Gravity and Electricity.] Erste Mitteilung. Zweite Mitteilung. [2 parts.] Sitzungsberichte der Preussischen Akademie der Wissenschaften, VI (1927). Sitzung der physikalisch-mathematischen Klasse vom 17 Februar. Sonderabdruck [Offprint]). Berlin: Verlag der Akademie der Wissenschaften (in commission at Georg Reimer [Reichsdruckerei]), 14th March 1927.
Imperial 8vo (25,4:18,2 cm). 8 pages, numbered 23-30. Letterpress on machine paper, in original publisher’s brochure on orange stock with black title printing.
First offprint in the original wrappers, of Einstein's paper on the important findings of German mathematician and physicist Theodor Kaluza about gravitation and electricity.
Content: Kaluza "attempted to unify Einstein's theory of gravity with Maxwell's theory of light by mixing them in a fifth dimension". Together with the Swedish theoretical physicist Oskar Klein Kaluza produced the „Kaluza-Klein field equations" (Calaprice, Einstein Almanac, 135). Their insights, however, were "neglected for many years as attention was directed towards quantum mechanics. [Their] idea that fundamental forces can be explained by additional dimensions did not re-emerge until string theory was developed" (Wikipedia).
Reference: Boni-Russ-L. 170; Schilpp-Shields 212; Weil 156.