1 2 2 D O C . 1 3 D I A L O G U E A B O U T R E L A T I V I T Y
claimed that with this modification the theory satisfies what he called “Mach’s principle,” the require-
ment that the metric field be fully determined by matter.
Hentschel 1990, pp. 74–91, discusses various arguments against the theory of relativity invok-
ing common sense, and also gives examples from the French, British, and American literature.
The quoted passage is from Lenard 1918, pp. 6–7. Einstein’s direct but pithy reply to Lenard’s
train-crash query appears in footnote 1 on p. 701. Lenard posed the same rhetorical question to Ein-
stein at Bad Nauheim (see Einstein et al. 1920 [Doc. 46]). Already in his Vienna lecture, Einstein
1913c (Vol. 4, Doc. 17), pp. 1254–1255, Einstein had appealed to the effects in a moving train car.
Much like Lenard would do later, Gustav Mie tried to turn Einstein’s argument against him in the dis-
cussion that followed this lecture (Einstein et al. 1913 [Vol. 4, Doc. 18], p. 1264. See also Gustav Mie
to Einstein, 21 March 1918 [Vol. 8, Doc. 488]).
Lenard conceded that “[t]his original, so-called special principle of relativity is well supported
by experience” (“Dieses ursprüngliche, sogenannte ‘spezielles’ Relativitätsprinzip wird gut von der
Erfahrung gestützt.” Lenard 1918, p. 4). Lenard’s objections focused exclusively on the general prin-
ciple of relativity which, he argued, needed to be restricted (Lenard 1918, pp. 2–3).
Einstein elaborated on the status of the ether in Einstein 1920j (Doc. 38).