D O C U M E N T 4 7 9 F E B R U A R Y 1 9 2 7 7 5 1 Published on 10 February 1927 in Forschungen und Fortschritte 3 (1927): 36. [1]Michelson and Morley 1887 [2]See Miller 1925a, 1925b, and 1925c. Einstein had previously commented publicly on Miller’s results in Docs. 13 and 161. [3]Miller invoked the ether-drag theory in interpreting his experiment and received some support from theorists such as Ludwik Silberstein (see Silberstein 1925b), based on the notion that an ether drift could be detected at high altitudes, but not at sea level. Miller, however, had always voiced res- ervations about the hypothesis that his observed effect varied with altitude, preferring to claim that performing the experiment in basements interfered with the sought-for ether drift (see Kennedy 1926 and Miller 1933). One reason for Piccard’s balloon experiments was, in fact, to perform the experi- ment in free-air (apart from the lightweight apparatus of the balloon itself), as discussed in Doc. 74. [4]Kennedy 1926 and Piccard and Stahel 1927. [5]Einstein had privately voiced concerns that Miller’s results were due to errors caused by varia- tions in temperature to Ehrenfest (Doc. 71), Piccard (Doc. 219), and others, including Miller himself. Miller replied in Doc. 289 that he had taken “elaborate precautions” to exclude temperature effects. Later, experts who reanalyzed Miller’s results, shared Einstein’s view (Shankland et al. 1955). 479. To Hendrik A. Lorentz Berlin.16. II. 27 Lieber und verehrter Herr Lorentz! Es wäre sicher ein grosser Gewinn für den Solvay-Kongress, wenn wir Millikan dafür gewinnen könnten.[1] Natürlich würde ich mich auch persönlich sehr freuen, wenn er käme ich bin sehr dafür, dass er eingeladen wird. Die Quanten-Theorie ist ganz verschrödingert und hat viel praktischen Erfolg davon.[2] Aber dies kann doch nicht die Beschreibung des wirklichen Vorganges sein. Es ist ein Mysterium. Es zeigt sich, dass die Vereinigung von Gravitation und Maxwellscher Theorie durch die 5 dimensionale Theorie (Kaluza-Klein-Fock) vollständig befriedigend geleistet wird.[3] Ich bin neugierig, was Sie dazu sagen werden. Herzlich grüsst Sie und Ihre Frau Ihr A. Einstein. ALSX. Kox 2008, p. 649. [16 611]. There are perforations for a loose-leaf binder at the left margin of the document. [1]Robert A. Millikan. Lorentz, who was visiting Pasadena (see Doc. 461), had asked Einstein’s opinion on a possible invitation by Millikan in Abs. 733. [2]A reference to Erwin Schrödinger’s wave mechanics. [3]See Klein, O. 1926, Kaluza 1921, and Fock 1926. See also Einstein’s comments in Einstein 1927i (Doc. 459).