I N T R O D U C T I O N T O V O L U M E 1 2 l v i i
22 December, he reported to Weyl that the “canal-ray experiment had a negative
outcome, which ultimately means a refutation of the field theory of electricity”
(Doc. 336). Einstein’s perplexity upon learning this news arose from his firm
belief, at that time, that the experimental design would, in fact, provide a clear
empirical decision between the two fundamentally opposite conceptions. It also
bears evidence to his belief in the possible significance of empirical data for the
solution of foundational questions. Faced with what he perceived to be an experi-
mental decision about classical field theory, he closed his postcard to Weyl with the
words: “Now what?”
[1]See, e.g., Clark 1971, pp. 382–392; Fölsing 1997, pp. 494–509; Frank 1953, pp. 176–187; Her-
mann 1994, pp. 261–266; Isaacson 2007, pp. 289–301. For an annotated edition of newspaper reports
of the tour, see Illy 2006.
[2]See, e.g., Adelson 1978; Barnard 1974, pp. 269–283; Berlin 1970; Halpern 1987, pp. 221–232;
Panitz 1978, pp. 77–94; Reinharz 1993, pp. 346–348 and 363–364; Rose 1986, pp. 206–213; Weiz-
mann 1949, pp. 265–269; Urofsky 1974.
[3]See Luther P. Eisenhart to Einstein, 1 October 1920 (Vol. 10, Doc. 160), and Albert G. Schme-
deman to Einstein, 30 October 1920 (Vol. 10, Calendar).
[4]Einstein to Paul Ehrenfest, 26 November 1920 (Vol. 10, Doc. 209).
[5]See Paul Ehrenfest to Einstein, 7 November 1920 (Vol. 10, Doc. 191), and Einstein to Paul
Ehrenfest, 26 November 1920 (Vol. 10, Doc. 209).
[6]See John G. Hibben to Einstein, 24 December 1920 (Vol. 10, Doc. 243).
[7]Charles S. Slichter to A. L. Barrows, 12 January 1921, and Charles S. Slichter to Paul M. War-
burg, 31 January 1921 (University of Wisconsin Madison Archives, Dean Slichter Papers).
[8]See Chaim Weizmann to Kurt Blumenfeld, 16 February 1921 [33 345].
[9]“Keren Hayesod Manifesto-1920, London,” The Jewish Chronicle, 24 December 1920.
[10]Wasserstein 1977a, pp. xiii–xiv.
[11]Lipstadt 1978, p. 55.
[12]The other three U.S. institutions were Columbia, Yale, and the National Research Council (see
also Einstein to Fritz Haber, 6 October 1920 [Vol. 10, Doc. 162]; Einstein to Max Warburg, 8 Decem-
ber 1920 [Vol. 10, Doc. 223]).
[13]“Einstein bereit, mit Ihnen Amerika reisen Brief folgt.” Kurt Blumenfeld to Chaim Weiz-
mann, 19 February 1921 (Weizmann Archives, Weizmann Institute).
[14]For Lorentz’s official invitation as president of the congress’s International Scientific Commit-
tee, see Hendrik A. Lorentz to Einstein, 9 June 1920 (Vol. 10, Doc. 49).
[15]On the relationship between Einstein and Lorentz, see Kox 1993.
[16]See, e.g., Ernest Rutherford to Bertram B. Boltwood, 28 February 1921, Badash 1969, p. 342.
Even though Einstein himself repeatedly claimed to hold Swiss citizenship, the Berlin Educa-
tion Ministry and the Academy of Sciences eventually concluded that Einstein had become a
Prussian citizen upon his employment there in 1913/1914. For the published versions of the rel-
evant documents, see Kirsten and Treder 1979a, pp. 112–120.
[17]For the relationship between Einstein and Haber, and their differing views on Germans and
Jews, see Stern 1999, ch. 3.
[18]See Vol. 10, Introduction, sec. II. Einstein was probably displeased with Roethe’s position in
regard to the issue of whether the Academy should take an open stance on Einstein’s public dispute
with the anti-relativity movement. Roethe had informed Planck that he was opposed to the Academy
publicly expressing its support for Einstein (see Gustav Roethe to Max Planck, 10 September 1920
[GyBAW-LA, Hist. Abt. II. Tit. Personalia II-III, 38, Fo. 80]).