D O C U M E N T 4 8 F E B R U A R Y 1 9 2 1 8 3
to segregate thermal radiation by frequency, and therefore temperature (in violation of the second law
Einstein had described this proposed experiment in Doc. 37. For Born’s later reflections on this
proposal, see Einstein and Born 2005, p. 49.
In Doc. 37, Einstein had drawn Born’s attention to a paper by Alfred Byk, Byk 1921a. Otto Stern
(1888–1969) was Extraordinary Professor at the University of Frankfurt.
Erwin Madelung (1881–1972), Professor of Theoretical Physics at the University of Münster,
was appointed as Born’s successor in Frankfurt (see Physikalische Zeitschrift 22 (1921): 160).
On Born’s attempts to get Stern appointed as his successor, see Max Born to Einstein, 8 Decem-
ber 1920 (Vol. 10, Doc. 224).
Niels Bohr had been invited in November 1920 by the Wolfskehl Foundation to lecture in Göt-
tingen in June 1921. However, due to Bohr’s ill health, the visit was eventually postponed until June
1922 (see Mehra and Rechenberg 1982, p. 344).
Born’s attempts to measure the elasticity constants of diamond did not succeed (see Einstein
and Born 2005, p. 53).
Otto Heinrich Wiener (1862–1927) was Professor of Physics at the University of Leipzig. He
was a pioneer of color photography, and did work on crystallography and polarization of light. Born
made use of a Carl Zeiss microinterferometer for these experiments (see Einstein and Born 2005,
Woldemar Voigt (1850–1919) had been Professor of Physics at the University of Göttingen and
was well known for his work on the physics of crystals.
Paul Oppenheim (1885–1955) was a chemist with N. M. Oppenheim Nachfolger.
Constantin Carathéodory (1873–1950) was Professor of Mathematics at the University of
Smyrna. For his work on the foundations of thermodynamics, see Carathéodory 1909.
Born 1921c; see also Born 1923a, pp. 730–733.
A second edition of Born 1915 appeared both as Born 1923a and as a contribution to the Ency-
clopedia of the Mathematical Sciences (Born 1923b). Imre Bródy (1891–1944), Assistent at the Uni-
versity of Göttingen, was a native of Hungary.
Walther Gerlach (1889–1979) was Extraordinary Professor of Physics at the University of
On James Franck’s call to Göttingen, see Max Born to Einstein, 16 July 1920 (Vol. 10, Doc. 75).
From Carl Still, an industrialist in Recklinghausen (see Einstein and Born 2005, p. 53).
Wilhelm Wien (1864–1928) was Professor of Physics at the University of Munich.
Wolfgang Pauli (1900–1958) was a student at the University of Munich (see Doc. 98). His arti-
cle, Pauli 1921, consists of 237 pages.
For Einstein’s views on the question of German reparations, see Doc. 37.
48. To Paul Ehrenfest
Berlin Sonntag Abend. [13 February
Einer abenteuerlichen politischen Idee wegen hab ich rasch mit einigen Genos-
sen nach Amsterdam fahren
habe aber nicht Zeit, Euch zu
Die Schritte für die russischen Kollegen habe ich damals unmittelbar nach