G E R M A N A N T I - R E L AT I V I S T S 1 0 9
The session convened at nine o’clock on the morning of 23 September with Max Planck
presiding, a delicate undertaking given the pre-conference publicity. Crowds thronged out-
side the doors, and some tussling for seats took place once these
were scheduled, but time constraints left room for just four speakers during the morning
While some left the packed hall because the lectures resembled “a hailstorm of
differentials, coordinate invariants, elementary quanta of action, transformations, vectorial
waited in anticipation of the battle to come. Finally, with just fifteen
minutes remaining, Planck opened the floor to general discussion, at which point the long-
awaited showdown between Lenard and Einstein took place.
While much has been written about this encounter, extant documentary evidence pro-
vides only a partial and approximate record of what was actually said on this
A transcript of the lectures and ensuing discussions at Bad Nauheim was prepared by Peter
Debye (1884–1966), Professor of Theoretical and Experimental Physics at the University
of Göttingen (Einstein et al. 1920 [Doc. 46]). Although this is the most complete account
available, contemporaries noticed that it was
Arnold Berliner called the account
“fragmentary” and “worthless,” but blamed the Hirzel publishing house for its
One obvious problem with Einstein et al. 1920 (Doc. 46) is that it contains a gap in the
Lenard-Einstein exchange. According to Lenard’s later
he had posed two main
questions to Einstein. The first involved his long-standing train-crash query, whereas the
second dealt with an alleged “contradiction” in general relativity due to the relativity of ro-
tational motion. Lenard noted that if the earth were considered as at rest and the whole uni-
verse as rotating around it, then this implies the admissibility of superluminal velocities, an
issue nowhere mentioned in Einstein et al. 1920 (Doc. 46). In answering this question, Ein-
stein explained that the principle of the constancy of the velocity of light no longer holds
See Berliner Tageblatt, 24 September 1920, Morning Edition, p. .
Hugo Dingler (1881–1954), Assistant Professor of Mathematics at the University of Munich,
and Franz P. Liesegang (1873–1949), a partner in the firm Ed. Liesegang Düsseldorf, spoke the fol-
lowing day, when Einstein was no longer present. Dingler was the only opponent of relativity on the
program. For accounts of these lectures, see Physikalische Zeitschrift 21 (1920): 649–675 and Weyl
“Es hagelt jetzt Differentiale, Koordinateninvarianz, elementare Wirkungsquanten, Transfor-
mationen, Vectorialsysteme usw.” Berliner Tageblatt, 24 September 1920, Evening Edition, p. .
Recent accounts include Beyerchen 1977, pp. 85–91; Fölsing 1993, pp. 526–528; Goenner
1993, pp. 123–127. Max Born recalled Lenard’s behavior: “[He] directed sharp, nasty attacks against
Einstein, with a blatantly anti-Semitic tendency. Einstein became agitated and answered him sharply,
and I believe I remember that I supported him” (“[er] richtete scharfe, bösartige Angriffe gegen Ein-
stein, mit unverhüllt anti-semitischer Tendenz. Einstein ließ sich dazu hinreißen, scharf zu antworten,
und ich glaube mich zu erinnern, daß ich ihm sekundierte.” Born 1969, p. 60). As pointed out in Föl-
sing 1993, p. 793, note 56, Born’s recollections are not supported by contemporary evidence. Despite
the tense atmosphere, Einstein and the rest of the participants conducted themselves “with an objec-
tivity and calm that were truly exemplary” (“mit einer geradezu vorbildlichen Sachlichkeit und Ruhe”;
Deutsche Allgemeine Zeitung, 25 September 1920, Morning Edition, p. 2).
This probably explains why Hermann Weyl decided to publish another version in Weyl 1922b.
Arnold Berliner to Einstein, 17 January 1921. In his letter of 21 January 1921, he also promised
Einstein that he would try to obtain Debye’s text and then consult with Lenard about correcting the
Lenard 1921a, pp. 38–41.