6 4 V O L U M E 8 , D O C U M E N T 2 8 7 a
Presumably a reference to Hilbert’s variational formulation, in which the Lagrangian density
consists of the sum of a purely gravitational part and an electromagnetic part (see Hilbert 1915). The
assumption is also made in Einstein 1916o (Vol. 6, Doc. 41).
The Wednesday colloquium in Heinrich Rubens’s institute.
Emil Wiechert (1861–1928) was Professor of Geophysics at the University of Göttingen. In
Wiechert 1916 he had advanced an explanation of the anomalous advance of the perihelion of Mer-
cury in which he retained the ether and postulated the existence of a gravitational mass density
associated with the energy density at distance r of the center of a gravitating
central mass M. Here c is the velocity of light, the gravitational constant, and p is a numerical con-
stant which Wiechert found to be equal to 10.7 1.4 in order to account for an anomalous secular
advance of 45 5 .
Arnold Sommerfeld (1868–1951) was Professor of Physics at the University of Munich. In Ger-
ber 1898, an account of the anomalous advance of planetary perihelia was given by assuming a
velocity-dependent gravitational potential. Gerber’s paper was mentioned prominently in Gehrcke
1916 as a classical and successful explanation of the perihelion anomaly and was reprinted posthu-
mously by Gehrcke as Gerber 1917. In response to the reprint, Hugo von Seeliger (1849–1926), Pro-
fessor of Astronomy at the University of Munich, published a critique in Seeliger 1917a, saying that
“it was known to me for 18 years that the whole calculation by Gerber rests on an error. This error can
be recognized so easily that I have refrained so far to point it out” (“mir seit 18 Jahren bekannt ist,
da[ss] die ganze Rechnung Gerbers auf einem Irrtum beruht. Dieser ist so leicht zu erkennen, da[ss]
ich bisher Anstand genommen habe ihn aufzudecken,” p. 31). Seeliger defended his criticism against
Oppenheim 1917 in Seeliger 1917b. Gerber’s erroneous formal treatment was also criticized in Laue
1917. For a historical discussion of the Gerber controversy, see Hentschel 1990, p. 160. For further
discussion of Einstein’s explanation of the Mercury anomaly and alternative explanations of it, see
Earman and Janssen 1993; for a historical discussion of the anti-relativity campaign and Gehrcke’s
role, see Goenner 1993.
A collaboration with Jakob Grommer (1879–1933) on spatially symmetric, static solutions of
the gravitational field equations with degenerate boundary conditions is acknowledged in Einstein
1917b (Vol. 6, Doc. 43), p. 146, submitted 8 February 1917. A few months later Einstein would rec-
ommend Grommer in a letter to Ehrenfest as “Jew and genuine Russian” (“Jude und ächter Russe”)
(Einstein to Paul Ehrenfest, 22 July 1917 [Vol. 8, Doc. 362]).
Since the expression for gravitational stress-energy-momentum that was derived, e.g., in Ein-
stein 1916o (Vol. 6, Doc. 41), eq. (20) is not a proper tensor, it may be made to vanish, e.g. for the
gravitational field of a point mass, an objection raised later by Bauer 1918 and Schrödinger 1918. For
Einstein’s response to this objection, see Einstein 1918b and 1918f (Vol. 7, Docs. 2 and 9).
Einstein 1916g (Vol. 6, Doc. 32), in which Einstein discusses gravitational waves.
Einstein 1917a (Vol. 6, Doc. 42), dated December 1916.
Vol. 8, 287a. To Heinrich Zangger
[Berlin,] Montag, 8. 1.
Lieber Freund Zangger!
Es ist eine ziemliche Kalamität mit dem Gelde. Ich habe soeben auf meiner
Bank erfahren, dass sie meinen an Sie gerichteten Chek, lautend auf 1500 fr noch
nicht hat besorgen
weil sie den Konsens zum Abschicken des Geldes
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