Einstein: His Life and Universe

theories of spatial separability.

54

. Bernstein 1996a, 138.

55

. More precisely, it is the square of the wave function that is proportional to the probability. Holton and Brush, 452.

56

. Einstein to Hedwig Born, Mar. 7, 1926, AEA 8-266; Einstein to Max Born, Dec. 4, 1926, AEA 8-180.

57

. aip.org/history/heisenberg/p07.htm; Born 2005, 85.

58

. Max Born to Einstein, July 15, 1925, AEA 8-177; Einstein to Hedwig Born, Mar. 7, 1926, AEA 8-178; Einstein to Paul Ehrenfest, Sept. 25, 1925, AEA 10-116.

59

. Werner Heisenberg to Einstein, June 10, 1927, AEA 12-174.

60

. Heisenberg 1971, 63; Gerald Holton, “Werner Heisenberg and Albert Einstein,”

Physics Today

(2000), www.aip.org/pt/vol-53/iss-7/p38.html.

61

. Frank 1947, 216.

62

. Aage Petersen, “The Philosophy of Niels Bohr,”

Bulletin of the Atomic Scientists

(Sept. 1963): 12.

63

. Dugald Murdoch,

Niels Bohr’s Philosophy of Physics

(Cambridge, England: Cambridge University Press, 1987), 47, citing the Niels Bohr Archives: Scientific Correspondence, 11: 2.

64

. Einstein, “To the Royal Society on Newton’s Bicentennial,” Mar. 1927.

65

. Einstein to Michele Besso, Apr. 29, 1917; Michele Besso to Einstein, May 5, 1917; Einstein to Michele Besso, May 13, 1917. For a good analysis, see Gerald Holton, “Mach, Einstein, and the Search for Reality,” in Holton 1973, 240.

66

. “Belief in an external world independent of the perceiving subject is the basis of all natural science.” Einstein, “Maxwell’s Influence on the Evolution of the Idea of Physical Reality,” 1931, in Einstein 1954, 266.

67

. Einstein to Max Born, Jan. 27, 1920.

68

. Einstein’s introduction to Rudolf Kayser,

Spinoza

(New York: Philosophical Library, 1946). Kayser was married to Einstein’s stepdaughter and wrote a semi- authorized memoir of Einstein.

69

. Folsing, 703–704; Einstein to Fritz Reiche, Aug. 15, 1942, AEA 20-19.

70

. Einstein to Max Born, Dec. 4, 1926, AEA 8-180.

CHAPTER FIFTEEN: UNIFIED FIELD THEORIES

1

. Einstein, “Ideas and Problems of the Theory of Relativity,” Nobel lecture, July 11, 1923. Available at nobelprize.org/nobel_prizes. This section draws from these papers on Einstein’s unified field quest: van Dongen 2002, courtesy of the author; Tilman Sauer, “Dimensions of Einstein’s Unified Field Theory Program,” forthcoming in