the smallest reproduction of the periodic table: You can watch this feat on YouTube at www.geek.com/articles/geek-cetera/periodic-tablet-etched-on-a-single-hair-as-birthday-gift-20101230. See also Science 334, no. 7 (October 2011), p. 24.

the English chemist William Prout: For a brief biography of Prout (1785–1850), see Rosenfeld 2003.

Eddington proposed in 1920: Eddington 1920. At the time he still considered annihilation, too, as a possible source of energy. Eddington discussed the source of stellar energy in Eddington 1926.

the French physicist Jean-Baptiste Perrin: Wesemael 2009 described nicely the contributions of Perrin (1870–1942), and of the American physical chemist William Draper Harkins (1873–1951). See also Shaviv 2009, chapter 4.

“go and find a hotter place”: Eddington 1926, p. 301.