1 0 4 G E R M A N A N T I - R E L AT I V I S T S
superficial,”[14]
and that he had no intention of answering the charges. Nor did anyone else
immediately refute Gehrcke’s allegations in Germany’s most prestigious physics journal.
The following year, Gehrcke persisted by republishing Gerber’s lengthier analysis of plan-
etary perihelia in the same journal (Gerber 1902).
Gehrcke took a traditional stance with respect to optics, promoting a modified version
of Stokes’s approach to the ether, in which fast-moving bodies such as the earth completely
drag along the
ether.[15]
He tried to salvage Stokes’s earlier theory while polemicizing
against
relativity.[16]
He continued to promote his ideas on ether physics in Gehrcke 1918,
which led to Einstein’s brief and critical response in Einstein 1918l (Doc.
15).[17]
III
Gehrcke’s resurrection of Gerber’s work encouraged Philipp Lenard to unveil his own in-
dependent version of an ether-based gravitational theory in a paper submitted to Johannes
Stark’s Jahrbuch für Radioaktivität und
Elektronik.[18]
As Lenard wrote to Stark on 16 July
1917, his work was intended (1) to support the claims for an ether theory, (2) to do the same
for Gerber’s results, (3) to locate the Achilles’ heel of the principle of general relativity, and
(4) to give an account of gravitation based on the
ether.[19]
A few months later Lenard’s
equanimity was shaken after reading the criticism of Gerber’s work leveled by Max von
Laue and Hugo von
Seeliger.[20]
Lenard withheld publication in order to revise his manu-
script and later resubmitted a paper in which he toned down his praise for
Gerber.[21]
Lenard’s main aim in Lenard 1918 was to demonstrate that the principle of general rel-
ativity could not be upheld, and that a theory of gravitation based on ether physics offered
a more plausible alternative. He also criticized one of Einstein’s best-known thought exper-
iments, in which relativistic effects inside a moving train car illustrate the equivalence prin-
ciple (Einstein 1917a [Vol. 6, Doc. 42], pp. 464–466). One imagines that the train suddenly
brakes, causing objects within it to be thrown about. According to Einstein’s theory, the
passengers inside the car are not entitled to conclude that these effects are necessarily due
to a change in the train’s state of motion. Such an assertion would be tantamount to regard-
[14]“Geschmacklosen und oberflächlichen Angriffe Gehrkes.” Einstein to Wilhelm Wien, 17 Oc-
tober 1916 (Vol. 8, Doc. 267). Wilhelm Wien (1864–1928) was Professor of Physics at the University
of Würzburg.
[15]Stokes 1845. For historical discussion, see Whittaker 195153, Vol. 1, pp. 386–387.
[16]Drude 1912, pp. 470–476.
[17]Commenting earlier and in private also on Lenard’s conception of ether physics in Lenard 1910,
Einstein called it “abstruse Aetherei” and “almost infantile” (“fast infantil”; Einstein to Jakob Laub,
27 August 1910 [Vol. 5, Doc. 224]).
[18]The manuscript was published in a revised form as Lenard 1918. Johannes Stark (1874–1957)
was then Professor of Physics at the University of Greifswald.
[19]See Kleinert and Schönbeck 1978, p. 323.
[20]Laue 1917, Seeliger 1918. Laue had been a supporter of the theory of relativity, but Seeliger
had shown no such leanings. Laue pointed out that Gerber drew on Wilhelm Weber’s treatment of
electromagnetic forces based on action at a distance. This model, however, was inconsistent with Ger-
ber’s claim that gravitational forces propagated with the speed of light rather than instantaneously.
[21]Philipp Lenard to Johannes Stark, 16 July 1917; 20 October 1917; 9 February 1918 (quoted in
Kleinert and Schönbeck 1978, pp. 323–324).