D O C . 4 5 A N T I - R E L AT I V I T Y C O M PA N Y 3 4 9
Paul Gerber (1854–before 1917) was a high school teacher in Stargard, Pomerania. His formula
for the precession of planetary perihelia was first published in Gerber 1898; Gehrcke republished
Gerber’s lengthier study, Gerber 1902, in Annalen der Physik. In Gehrcke 1916, he compared Ger-
ber’s formula with Einstein’s, showing that they were identical.
Gerber’s derivation was based on a formalism similar to the action-at-a-distance approach
adopted by Wilhelm Weber for electromagnetic forces (see Laue 1917). This undercut Gerber’s main
idea that gravitational forces propagated with the speed of light rather than instantaneously. Laue later
showed that Gerber’s approach was well known, going back to work that was published in the 1870s
(see Laue 1920b). Gerber had merely introduced a factor of three without any clear reason for doing
so, and this led to the “correct” quantitative result. Einstein was thus certainly justified in asserting
that his derivation in Einstein 1915h (Vol. 6, Doc. 24) constituted the first “explanation” of the anom-
aly in the perihelion motion of Mercury based on first principles rather than ad hoc arguments like
those advanced in Seeliger 1906.
Gerber’s derivation was criticized in Laue 1917, as well as in Seeliger 1917. Lenard afterwards
suggested that the arguments brought by Laue and Seeliger against Gerber’s results were overly crit-
ical; see Lenard 1918, pp. 1–2, and the editorial note, “Einstein’s Encounters with German Anti-Rel-
ativists,” pp. 101–113.
This refers to Gehrcke’s charge of plagiarism in Gehrcke 1916 and Lenard’s efforts to legitimate
Gerber’s work in Lenard 1918. Einstein had informed Wilhelm Wien, co-editor of Annalen der
Physik, that he had no intention of answering Gehrcke’s charges (Einstein to Wilhelm Wien, October
17, 1916 [Vol. 8, Doc. 267]).
On the English expeditions and their results, see Einstein 1919d (Doc. 23), notes 2–4.
Gehrcke referred to work by Karl Schwarzschild and Charles E. St. John in which the predicted
gravitational redshift was not detected. He failed to mention the positive findings reported in Grebe
and Bachem 1919, 1920a, and 1920b, only indicating that the entire corpus of experimental results
would soon be analyzed by Ludwig C. Glaser. Indeed, on 2 September Glaser was the only speaker
at the second (and last) evening of anti-relativity lectures hosted by Weyland’s organization at the
Philharmonic Hall. Glaser’s critique was directed mainly at the work of Leonhard Ch. Grebe and
Albert J. Bachem, but not that of Alfred Perot. Perot (1863–1925) was Professor of Physics at the
École Polytechnique, Paris. On his contribution before the present document to measuring the gravi-
tational redshift, see Perot 1920a and 1920b. It was Arnold Berliner who called Einstein’s attention
to Perot’s new results (Arnold Berliner to Einstein, 19 August 1920). For further discussion, see
Hentschel 1992, and 1998, pp. 227–229, 514–535.
These discussions took place at the meeting of the Gesellschaft Deutscher Naturforscher und
Ärzte in Bad Nauheim on 23 September 1920 (see Einstein et al. 1920 [Doc. 46]).
For reactions from abroad, see Hendrik A. Lorentz to Einstein, 3 September 1920; Paul Ehren-
fest to Einstein, 28 August 1920 and 2 September 1920; Einstein to Paul Ehrenfest, before 10 Sep-