V O L . 8 , D O C U M E N T 2 2 2 a M AY 1 9 1 6 2 3 ALS. [95 879]. Written on letterhead “Prof. Dr. H. F. Weber Elektrotechnisches Laboratorium des Eidgenöss. Polytechnikums Zürich.” [1]This is the complete text of Vol. 5, Doc. 429, where only an extract was published. [2]Bredig (1868–1944) was Professor of Physical Chemistry and Electrochemistry at the Tech- nische Hochschule in Karlsruhe and director of its institute of physical chemistry. [3]“Donnerstag” is in Einstein’s hand at the top of the page. “Febr. 13” is entered below it, possibly in another hand. [4]Michael Polanyi (1891–1976) was a student of chemistry at the Technische Hochschule in Karlsruhe (see Adressbuch Fridericiana 1913, p. 30). [5]The analogy between zero temperature and infinite pressure is developed in the framework of quantum theory in Polanyi 1913,which was received 15 March 1913. [6]See Debye 1912. [7]Einstein had been appointed Professor of Theoretical Physics at the ETH beginning in fall 1912, and moved from Prague to Zurich in early August 1912. [8]Einstein had started a significant collaboration with Marcel Grossmann (1878–1936), Professor of Mathematics at the ETH, who drew Einstein’s attention to the work of mathematicians Riemann, Christoffel, Ricci, and Levi-Civita, and who assisted Einstein in his search for gravitational field equations based on tensor calculus. Their Entwurf theory, a preliminary but comprehensive version of a generalized theory of relativity and gravitation, was published in May 1913 (see Vol. 4, Introduc- tion and Doc. 13, Einstein and Grossmann 1913). Vol. 8, 222a. To Gunnar Nordström[1] [Berlin, 28 May 1916] Lieber Nordström! Ich freute mich sehr über Ihr Lebenszeichen sowie darüber, dass Ihnen der ge- genwärtige Zustand die Unternehmungslust nicht gebrochen hat. Wenn ich kann, komme ich in Sommer auch nach Holland aber die deutsche Grenze ist schwer zu überschreiten.[2] Ich sende Ihnen meine zusammenfassende Arbeit über die Gra- vitation nach Kopenhagen.[3] Indem ich Ihnen eine frohen Sommer wünsche, bin ich mit herzlichen Grüssen Ihr A. Einstein. AKS (FI-Abo, Manuscript Department, Ejnar Collection). [86 043]. The postcard is addressed “Prof. Dr. G. Nordström, Poste Restante Kopenhagen Dänemark,” with a correction in another hand “Faydenlund Gl Konegwig 178” and postmarked “Berlin-Wilmersdorf 28 5 16 1–2 N.” [1]Nordström (1881–1923), Privatdozent in theoretical physics at the University of Helsinki, was going to work with Paul Ehrenfest in Leyden (see Nordström to Einstein, 3 August 1916 [Vol. 8., Doc. 247]). Ehrenfest (1880–1933) was Professor of Theoretical Physics at the University of Leyden. [2]Einstein would travel to Holland September 27–October 12, 1916. See Vol. 8, Calendar, entry of 27 September 1916. [3]See Einstein 1916e, published 11 May 1916.