I N T R O D U C T I O N T O V O L U M E 1 6 l x x x v i i [1] Einstein traveled to the Congress by train, occupying himself on the journey with Reichenbach’s new book, Reichenbach 1928 (see Doc. 74). He also took the opportunity to visit his maternal uncle, Caesar Koch, in Liège after the end of the conference (see Doc. 78). [2] See Bacciagaluppi and Valentini 2009, p. 18. [3] See in particular Bacciagaluppi and Valentini 2009. [4] Though Einstein requested not to present a report at the second meeting, he was again active in the discussion periods (see Vol. 4, Doc. 22). [5] Einstein’s decision to go to the United States instead of the Third Solvay Congress was a diffi- cult one for him to make. For some discussion, see Introduction to Vol. 12, sec. I. [6] See “Rapport au Ve Conseil de Physique Solvay sur la nouvelle dynamique des quanta” (Broglie 1928), in Solvay 1928, p. 105. [7] See Introduction to Vol. 15, sec. IX. [8] See Bacciagaluppi and Valentini 2009, chaps. 11.1 and 11.2 for a discussion of the historical mistreatment of De Broglie’s original work [9] For some of the problems facing Einstein’s hidden variable theory, see Holland 2005, Belousek 1996, Bacciagaluppi and Valentini 2009, and the Introduction to Vol. 15, sec. IX. [10] Einstein had time to think through these remarks before submitting the written version on 21 November (see Abs. 277). With the exception of the first page (Doc. 76), the original manuscript in Einstein’s hand has been lost. [11] Einstein may well have regarded the first conception as tied to wave functions defined in ordi- nary, three-dimensional, space rather than in high-dimensional configuration space, which may account for the failings of the first conception that Einstein lists here (see Bacciagaluppi and Valentini 2009, p. 204.) [12] For further discussion of Einstein’s remarks at the Fifth Solvay Congress and the 1935 EPR argument, as well as a precursor of that argument as early as 1909, see Howard 1990, Hardy 1995, Norsen 2005, and Bacciagaluppi and Valentini 2009, chap. 7. [13] Not all of Einstein’s contributions are reflected in the published proceedings. In particular, it is evident from the working notes of Jules Émile Verschaffelt—then secretary of the Solvay Institute’s Scientific Committee—that Einstein also contributed to the discussion following Compton’s report (see Bacciagaluppi and Valentini 2009, pp. 483, 485). [14] See, for example, Heisenberg 1929, Jammer 1974, and Mehra and Rechenberg 2000. For crit- icism of the tendency to emphasize the importance of the Bohr-Einstein debate, see Bacciagaluppi and Valentini 2009, chap. 12. [15] See Heisenberg 1967, p. 107. The main account of the Bohr-Einstein debate is Bohr’s own rec- ollection from more than two decades later, Bohr 1949. Although Bohr saw Einstein as aiming to dis- prove the uncertainty relations, Howard 1990 argues that Einstein was always fundamentally motivated by the issue of nonseparability. [16] See Winkler 1993, pp. 330–331, and Schulze 1982, pp. 303–308. [17] See Winkler 1993, p. 342, and Weitz 2018, p. 109. [18] See Winkler 1993, pp. 342–343, and Schulze 1982, p. 308. [19] See Schulze 1982, pp. 309–312. [20] See Winkler 1993, pp. 329–330, and Schulze 1982, p. 309. [21] See “Correct Understanding of Punishment,” 22 January 1927 (Vol. 15, Doc. 462). [22] See Paucker 1968, p. 18, Wigoder 1994, p. 482, Wistrich 1998, p. 75, and Niewyk 2001, pp. 159–161. [23] See Ruppin 1930, p. 54, and Bennathan 1966, p. 93. [24] See Curti 1988, p. 373, and Rozett and Spector 2000, pp. 5–6, 9. [25] See Weizmann 1978, p. xi. [26] See Weizmann 1978, pp. ix–xvii, and Wigoder 1994, pp. 700, 751. [27] See Vol. 15, Introduction, p. lxxix.