Weimar culture and quantum causality

History of Science

Volumn 18, Issue 3, 1980, Pages 155-180

  Hendry, John ^a  

^a IMPERIAL COLLEGE LONDON   (United Kingdom)

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EID: 84965874352     PISSN: 00732753     EISSN: 17538564     Source Type: Journal    
DOI: 10.1177/007327538001800301     Document Type: Article

References (110)

1. Forman Paul, “Weimar culture, causality, and quantum theory, 1918–1927: Adaptation by German physicists and mathematicians to a hostile intellectual environment”. Historical studies in the physical sciences, iii (1971), 1–116, p. 3. I shall refer to this paper as Weimar. I should like to thank Paul Forman for discussing his work in correspondence with me, and Jon Dorling, John Schuster, Bob Westman and seminar groups in Cambridge and at the Open University for many stimulating discussions.
2. Dorling J. challenged Forman's claims in an address to the British Society for the History of Science in July 1976, but this has not been published. Laqueur W., Weimar, a cultural history 1918–1933 (London, 1974), ch. 6, rejects Forman's thesis on the grounds that the physicists did not split along clear ideological lines.
3. Forman Paul, “The reception of an acausal quantum mechanics in Germany and Britain”, to be published in the proceedings of the symposium on “The reception of unconventional science by the scientific community”, American Academy for the Advancement of Science, February 1978. See ref. 115 below.
4. Forman, Weimar, 4.
5. For a clarification of this point of the argument I am indebted to a private communication from Paul Forman.
6. This picture of the milieu, which is in fundamental agreement with Forman's, is based largely on the historical studies he cites: Lukács G., Die Zerstörung der Vernunft (Berlin, 1954); Sontheimer K., Antidemokratisches Denken in der Weimarer Republik (Munich, 1952); Gay P., Weimar culture (New York, 1968); and especially Ringer F., The decline of the German mandarins (Cambridge, Mass., 1969). See also Lebovics H., Social conservatism and the middle class in Germany, 1914–1933 (Princeton, 1969), and Laqueur W., op. cit. (ref. 2).
7. In Spengler's The decline of the West, the term ‘Western’ is ambiguous, relating on one hand to the overall decline of Western civilization, in which Germany is included, and on the other hand to the decline of Western, or non-German, ideals within that civilization. In general usage, however, it had simply the latter, derogatory meaning, and it was on this meaning that the polemic value of Spengler's work rested; indeed the rejection of ‘Western’ in favour of German values was perhaps the central feature of the Weimar milieu.
8. See Ringer, op. cit. (ref. 10). Mathematics had become established in the school curriculum only toward the end of the nineteenth century.
9. See especially Troeltsch E., “Die Revolution in der Wissenschaft”, Schmollers Jahrbuch, xlv (1921), 1001–30.
10. There would appear to be some scope for a sociological study of the life sciences in Weimar Germany, but such a study has not, so far as I know, been undertaken.
11. Forman, Weimar, 60–61, 76–77; Spiegelberg H., The phenomenological movement (The Hague, 1965).
12. Reid C., Hilbert (New York, 1969).
13. Only the style of the debate may be put down with some confidence to the milieu: See Forman, Weimar, 61.
14. Troeltsch, op. cit. (ref. 13); Spengler O., Der Untergang des Abendlandes. Umrisse einer Morphologie der Weltgeschichte, Gestalt und Wirklichkeit (Munich, 1918; revised edition (33rd) 1923; translation of revised edition. The decline of the West, vol. i: Form and actuality (New York, 1926)).
15. See Forman, Weimar, 18.
16. See Forman, Weimar, 30–37; Spengler, op. cit. (ref. 18), esp. sect. xi.
17. ibid., sect, xi, esp. pp. 380 ff. of translation.
18. It is noticeable that the historians of the Weimar milieu (op. cit. (ref. 10)) all exclude science from their considerations; Gay, Weimar culture (preface) and Laqueur, Weimar (ch. 6) treat it explicitly as isolated from the milieu.
19. Forman, Weimar, 47–58.
20. This was true, moreover, for the staunchest of determinists, Einstein and Planck among them, as much as for anyone else: It always had been true, and still is so.
21. The exception here would appear to be Doetsch: See Forman, Weimar, 52.
22. ibid., 49–50. Concerning the repercussions, see for example Pauli to Bohr, 31 December 1924, where Sommerfeld's department is referred to jokingly as an institute for number mysticism: Pauli W., Wissenschaftlicher Briefwechsel, i, ed. by Herman A., (New York, 1979), letter no. 79.
23. Forman, Weimar, 71–72; Einstein to Born, 27 January 1920; English translation in Born M. & Einstein, The Born-Einstein letters (New York, 1971), letter no. 13.
24. This conviction was apparently shared then by Born: See Born M., Physics in my generation (New York, 1956), and Einstein to Mrs Born, 1 September 1919, letter no. 9 of op. cit. (ref. 27).
25. See Born's notes to the letter in op. cit. (ref. 27), and Jammer M., The conceptual development of quantum mechanics (New York, 1966), 133–4, for the technical background to this work.
26. The German original of Einstein's statement is, however, “Ich verzichte aber sehr sehr ungern auf die vollständige Kausalität”, and this appears to allow for no such ambiguity.
27. Forman, op. cit. (ref. 3). Sommerfeld's name is simply included among those of the “converts” in a summary of Forman's previous conclusions.
28. Though highly relevant to the general problem of the interaction between physicists and the milieu, they cannot be claimed to support his strong thesis, that physicists rejected causality in response to the pressures of that milieu.
29. Exner F., Vorlesungen über die physikalischen Grundlagen der Naturwissenschaften (Vienna, 1919); Forman, Weimar, 74–76; Hanle P., “Indeterminacy before Heisenberg: The case of Franz Exner and Erwin Schrödinger”, Historical studies in the physical sciences, x (1979), 225–70.
30. Nernst W., Zum Gültigheitsbereich der Naturgesetze (Berlin, 1921); Forman, Weimar, 84–85.
31. Nernst W., “Zum Gültigkeitsbereich der Naturgestze”, Die Naturwissenschaften, x (1922), 489–495, pp. 494–5; Forman, Weimar, 85–86.
32. Jeans J. H., “Non-Newtonian mechanical systems and Planck's theory of radiation”, Philosophical magazine, xx (1910), 943–954; Poincaré H., “L'hypothèse des quanta”, in his Dernières pensées (Paris, 1913), 75–76.
33. Jammer, op. cit. (ref. 28), 171. Poincaré had thought his suggestion would be acceptable to the determinist Planck and there can be no doubt that he, like Jeans, intended no challenge to the causality principle. Jammer supports his assertion by citing Poincaré's discussion of the role of chance in physics in 1904, but we should note that Poincaré then defined chance as a “complex assemblage of causes”, Poincaré H., La valeur de science (Paris, 1904), 110.
34. Planck M., “Ueber die Begründung des Gesetzes der schwarzen Strahlung”, Annalen der Physik, xxxvii (1912), 642–656, p. 644.
35. Bohr N., “On the constitution of atoms and molecules”. Philosophical magazine, xxvi (1913), 1–25, 476–502, 857–75.
36. Langevin P. & de Broglie M., (eds), La théorie du rayonnement et les quanta: Rapports et discussions de la réunion tenue à Bruxelles, du 30 octobre au 3 novembre 1911 sous les auspices de M. E. Solvay (Paris, 1912), 436.
37. Einstein A., “Zur Quantentheorie der Strahlung”, Physikalische Zeitschrift, xviii (1917), 121–8.
38. Despite considerable evidence in support of the need for discrete and localized absorption of light—and hence for the existence of light-quanta—the evidence in support of the wave theory was overwhelming, and rather than incorporating a fundamental contradiction in their theories physicists naturally preferred to stick to the established theory: This may have been limited in application, but it was at least consistent. On this and the wave-particle issue in general see Hendry J., “The development of attitudes to the wave-particle duality of light and quantum theory, 1900–1920”, Annals of science, xxvii (1980), 59–79.
39. While making it clear that causality was retained, Einstein did in fact adopt the terminology of “chance”.
40. The situation was fundamentally different from that in statistical mechanics, for example, where the probabilities were derived from an assumed causal behaviour. In this case all attempts to specify an underlying causal behaviour had failed—and were to continue to do so.
41. Interview with Heisenberg W., 1963, Sources for history of quantum physics archive: See Kuhn T., Sources for history of quantum physics (American Philosophical Society, Philadelphia, 1967), 10, 101. Heisenberg's reference was to the physicists at Munich (under Sommerfeld) and later at Göttingen (under Born and Frank).
42. Darwin C. G., manuscript draft of a critique on the foundations of physics (July 1919), Sources for history of quantum physics (op. cit. (ref. 45)), microfilm 36, 3. See also Darwin to Bohr, 20 July 1919, and Bohr to Darwin, July 1919, ibid., bsc 1, 4.
43. Writing to Bohr, 20 July 1919, ibid., Darwin found the “case against energy conservation quite overwhelming”.
44. Bohr to Darwin, July 1919, ibid.
45. Bohr N., “On the quantum theory of line spectra, part I”, Kongelige Danske Videnskabernes Selkabs Skrifter, ser. 8, iv, i (1918–1922), 1–118, p. 7. Jammer op. cit. (ref. 29), 114, found the terminology sufficiently provocative to interpret “spontaneous” as “acausal”, but Bohr himself later defined it as “without any assignable external stimulation”, leaving plenty of room for causes internal or as yet unknown: Bohr N., “On the application of the quantum theory to atomic structure: Part I, The fundamental postulates”, Supplement to Proceedings of the Cambridge Philosophical Society (1924), 24.
46. For full discussion of the development of Bohr's ideas see Meyer-Abich K. M., Korrespondenz, Individualität, und Komplementarität (Wiesbaden, 1965).
47. Forman, Weimar, 76–80; Weyl H., “Das Verhältnis der kausalen zur statistischen Betrachtungsweise in der Physik”, Schweizerische Medizinische Wochenschrift, 1 (1920), 737–41, and Raum-Zeit-Materie, 4th ed. (Berlin, 1921), 283–4.
48. See Forman, Weimar, 76, footnote 176. Weyl was primarily a mathematician, using philosophical ideas for inspiration (on the foundations of mathematics) and for connecting mathematical results (of his unified theory) to the properties actually found in the physical world. See ref. 61 below.
49. Weyl H., “Reine Infinitessimalgeometrie”, Mathematische Zeitschrift, ii (1918), 384–411; idem, “Gravitation und Elektrizität”, Sitzungsberichte der Preussischen Akademie der Wissenschaften (1918), 465–80; idem, “Eine neue Erweiterung der Relativitätstheorie”, Annalen der Physik, lix (1919), 101–33; idem, Raum-Zeit-Materie (Berlin, 1918). In progressing from the special to the general theory of relativity, Einstein had abandoned the assumption of Euclidean geometry that the directions of vectors at different points in space-time could be directly compared; in the Riemannian geometry that resulted, the relative direction of vectors at two points became dependent on the choice of paths joining the points, and the parameters defining this choice associated with those of the gravitational field. In Weyl's theory, the same argument was applied also to the lengths of the vectors, and the parameters appropriate to this further degree of freedom were identified with those of the electromagnetic field.
50. Pauli W., “Zur Theorie der Gravitation und der Elektrizität von Hermann Weyl”, Physikalische Zeitschrift, xx (1919), 457–67; see also Pauli W., Theory of relativity (London, 1958), 206. For other responses to Weyl's theory, all of which combine criticism of his physical conclusions with extravagant praise of the underlying mathematical theory, see the letters from Mie to Weyl, 26 October 1918, Einstein to Weyl, 8 March 1918, Sommerfeld to Weyl, 3 July 1918, and Eddington to Weyl, 18 August 1918, all in the archive of the Eigener Technische Hochschule, Zürich.
51. This criticism no longer held after the discovery of the positron, but it appeared to be valid at the time.
52. “The continuum theories make direct use of the ordinary concept of electric field strength, even for fields in the interior of the electron. This field strength is however defined as the force acting on a test particle, and since there are no test particles smaller than an electron or a hydrogen nucleus, the field strength at a given point in the interior of such a particle would appear to be unobservable by definition, and thus be fictitious and without physical meaning.” This argument, cited from Pauli, op. cit. (ref. 54, 1958), 206, was included among Pauli's original criticisms and was referred to by Einstein, writing to Born on 27 January 1920, op. cit. (ref. 27).
53. Weyl to Pauli, 10 May 1919, op. cit. (ref. 26), letter no. 1.
54. Weyl to Pauli, 9 December 1919, ibid., letter no. 2.
55. ibid. (my translation): “That modern physics which finds no place in ‘lawful’ or ‘field physics’ can still be right. For I am quite convinced that Statistics is something independent, opposed in principle to Causality, to ‘Law’; because it is in general paradoxical to introduce a field as some kind of prior existent. I imagine that the field physics really plays only the role of ‘world geometry’; in matter there is something else different, real which is not causally comprehended, but which is perhaps to be thought of in terms of independent decisions, which we treat in physics through statistical calculation. It is quite possible that we must attribute to this the nature of the difference between past and future, between positive and negative electricity.”
56. Weyl H., “Was ist Materie?”, Die Naturwissenschaften, xii (1924), 561–9, 585–93, 604–11; Forman, Weimar, 79.
57. In broad terms we may say that Weyl saw his mathematical field theory as being of prime importance. This, however, offered no reason as to why the real (Einstein) world should be preferred to any other world consistent with the theory, and it was this gap that Weyl's philosophical arguments were intended to fill.
58. For a full statement of Pauli's philosophical position, which was close to that later adopted by Eddington, see Pauli to Eddington, 20 September 1923, op. cit. (ref. 26), letter no. 45. We should note also that Weyl's concern with the unidirectionality of time was itself rooted in an internal problem raised by Pauli's analysis, op. cit. (ref. 54), of the covariance properties of electrically asymmetric solutions in Weyl's theory under time reversal.
59. See Hendry J., “The search for a unified field theory and the conceptual origins of quantum mechanics” (typescript in circulation). A hint of Pauli's role is also to be found in Serwer D., “Unmechanischer Zwang: Pauli, Heisenberg, and the rejection of the mechanical atom, 1923–25”, Historical studies in the physical sciences, viii (1977), 189–256.
60. Forman, Weimar, 80–84; von Mises R., “Ueber die gegenwärtige Krise der Mechanik”, Zeitschrift für angewandte Mathematik und Mechanik, i (1921), 425–31, and Naturwissenschaft und Technik der Gegenwart (Leipzig, 1922); Schottky W., “Das Kausalproblem der Quantentheorie als eine Grundfrage der modernen Naturforschung überhaupt. Versuch einer gemeinverständlichen Darstellung”, Die Naturwissenschaften, ix (1921), 492–6, 506–11.
61. See Hendry, op. cit. (ref. 42).
62. Institut International de Physique Solvay, Atoms et electrons: Rapports et discussions du troisième conseil de physique tenue à Bruxelles du I au 6 avril 1921 (Paris, 1921), 80–100.
63. ibid., 120–130. For Millikan's earlier views see Hendry, op. cit. (ref. 42).
64. ibid., 228–47; the original English version of Bohr's paper is reproduced in Bohr N., Collected works, iii (Amsterdam, 1976): See esp. pp. 373–5.
65. For Einstein's views on non-conservation and acausality see Klein M. J., “The first phase of the Bohr–Einstein dialogue”, Historical studies in the physical sciences, ii (1970), 1–39.
66. It was shared at this time by Pauli, Bohr, Born, Heisenberg, Schrödinger, Weyl and Sommerfeld, to name only the most important.
67. Bohr N., “The effect of electric and magnetic fields on spectral lines”, Proceedings of the Physical Society of London, xxxv (1923), 275–302 (lecture delivered March 1922), and op. cit. (ref. 49, 1924), completed in November 1922 and originally published in Zeitschrift für Physik, xiii (1923), 117–65. Darwin C. G., “A quantum theory of optical dispersion”, Nature, cx (1922), 841, and “The wave theory and the quantum theory”, Nature, cxi (1923), 771–3.
68. Sommerfeld A., Atombau und Spektrallinien, 2nd ed. (Munich, 1922), translated as Atomic structure and spectral lines (London, 1923), 253. Although many physicists held fast to energy conservation (and Sommerfeld himself was to vacillate on the issue), it should be noted that the writings of Bohr and Sommerfeld were the prime authorities for quantum theory during this period.
69. Born M. & Heisenberg W., “Die Elektronenbahnen im angeregten Heliumatom”, Zeitschrift für Physik, xvi (1923), 229–243; Einstein A. & Ehrenfest P., “Quantentheoretische Bemerkung zum Experiment von Stern und Gerlach”, Zeitschrift für Physik, xi (1922), 31–34.
70. Schrödinger E., notebook, “Kausalität”, 10 September 1918, Sources for history of quantum physics (op. cit. (ref. 45)), 39, 7.
71. Schrödinger E., “Ueber eine Bemerkenswerte Eigenschaft der Quantenbahnen eines einzelnen Elektrons”, Zeitschrift für Physik, xii (1922), 13–23.
72. Schrödinger E., “Dopplerprinzip und Bohrsche Frequenzbedingung”, Physikalische Zeitschrift, xxiii (1922), 301–3.
73. Schrödinger to Pauli, 8 November 1922, op. cit. (ref. 26), letter no. 29.
74. The basic idea was to re-emerge later when, combined with Heisenberg's rejection of mechanical electron orbits in the atom, it was a fundamental feature of Schrödinger's wave mechanics.
75. Schrödinger E., “Was ist ein Naturgesetz?”, Die Naturwissenschaften, xvii (1929), 9–11: Inaugural lecture at Zürich, December 1922; Forman, Weimar, 87–88.
76. Bohr N., op. cit. (ref. 71), 279, and op. cit. (ref. 49, 1924), 20. In both cases the qualification, “in the present state of science” was given in respect of the absence of causality.
77. Senftleben H. A., “Zur Grundlagen der Quantentheorie”, Zeitschrift für Physik, xxii (1923), 127–56, quotation following from p. 127.
78. For Planck's views see op. cit. (ref. 66), 93–114.
79. What Forman means exactly by the phrase “quasi-crank” (Weimar, 98) is unclear, but the “crank” seems to refer to a minor mental breakdown that he suffered in 1924—a common enough occurrence that does not merit the nomenclature. As for the “quasi”, this may be related to the fact that a letter, cited by Forman as being written by Hans Albrecht Senftleben, is catalogued and indexed (incorrectly) in the Sources for history of quantum physics as being by someone completely different, namely Hermann Senftleben, an experimentalist. To make up for this unfairness, a paper by Hermann is indexed in van der Waerden's book, Sources of quantum mechanics (Amsterdam, 1967), as being by Hans Albrecht, while, to return to the catalogue, the letter catalogued as by Hermann and in fact by Hans Albrecht is cross-referenced as being by one H. R. Senftleben, who does not, mercifully, exist.
80. Bohr N., “Problems of the atomic theory”, reproduced in op. cit. (ref. 68), quotation from p. 571.
81. Bohr N. Kramers H. A. & Slater J. C., “The quantum theory of radiation”, Philosophical magazine, xlvii (1924), 785–802, p. 791.
82. The abandonment of causality followed from the decision to apply the already existing virtual oscillator theory to a single atom rather than to a large number of atoms; this had strong heuristic advantages and was a natural response to Slater's suggestion of a virtual field guiding light-quanta, in the light of Bohr's rejection of light-quanta.
83. Schrödinger E., “Bohrs neue Strahlungshypothese und der Energiesatz”, Die Naturwissenschaften, xii (1924), 720–4, and Schrödinger to Bohr, 24 May 1924, Sources for history of quantum physics (ref. 45), bsc 16.
84. Einstein to Born, 29 April 1924, op. cit. (ref. 27); see also Einstein to Ehrenfest, 31st May 1924, 12 June 1924, discussed by Klein, op. cit. (ref. 69), 33.
85. Pauli to Bohr, 2 October 1924, and see also Pauli to Sommerfeld, November 1924, 6 December 1924; op. cit. (ref. 26), letters nos 66, 70, 72. Compton A. H., “The scattering of X-rays”, Journal of the Franklin Institute, cxcviii (1924), 61–71, p. 70. van Vleck J. H., “Quantum principles and line spectra”. Bulletin of the National Research Council, liv (1926), 270. Stoner E. C., “The structure of radiation”, Proceedings of the Cambridge Philosophical Society, xxii (1925), 577–94, p. 582. Ehrenfest to Einstein, 9 January 1925, quoted and translated by Klein, op. cit. (ref. 69), 31. Slater J. C., “The nature of radiation”, Nature, cxvi (1925), 278. Sommerfeld's views are contained in the work cited by Compton.
86. Heisenberg first reported that “I do not really see it as an essential progress”: Heisenberg to Pauli, 4 March 1924, op. cit. (ref. 26), letter no. 57. He came round to it only after Born had linked it up with a difference equation approach that they (Born and Heisenberg) had been pursuing since the previous autumn, and had taken its technique “independent of the critically important and still disputed framework of that theory”: Born M., “Ueber Quantenmechanik”, Zeitschrift für Physik, xxvi (1924), 379–395, p. 379. For the difference equation approach see Serwer, op. cit. (ref. 63).
87. Kramers H. A., “The law of dispersion and Bohr's theory of spectra”, Nature, cxiii (1924), 673–674, and “The quantum theory of dispersion”, Nature, cxiv (1924), 310. Born, op. cit. (ref. 90). Heisenberg to Pauli, 8 June 1924, op. cit. (ref. 26), letter no. 62. Ladenburg to Kramers, 31 May 1924, Sources for history of quantum physics (ref. 45), bsc 9, 2 and bsc 10, and see also Ladenburg to Kramers, 8 June 1924, ibid., where Einstein's reaction to the new theory is described as “not unfavourable” (nicht ungünstig).
88. Kramers, Ladenberg, and Reiche were between them responsible for the development of the Bohr dispersion theory prior to the introduction to the new technique, while Born and Heisenberg were able to incorporate this technique into their existing research programme, with considerable effect. Pauli had concerned himself, privately, with the dispersion theory, but had already hinted at innovations more fundamental than those suggested by Bohr: Pauli to Sommerfeld, 6 June 1923, op. cit. (ref. 26), letter no. 37.
89. Bothe W. & Geiger H., “Experimentelles zur Theorie von Bohr, Kramers und Slater”, Die Naturwissenschaften, xiii (1925), 440–1. Born was already trying to develop de Broglie's theory before the experimental results were known, while even Bohr had prepared himself for an unfavourable result: Bohr to Heisenberg, 18 April 1925, and Born to Bohr, 24 April 1925, Sources for history of quantum physics (ref. 45).
90. See Hendry J., “The mathematical formulation of quantum theory and its physical interpretation, 1900–1927” (Ph.D. thesis, University of London, 1978), ch. 3.
91. Reichenbach H., “Die Kausalstruktur der Welt und der Unterschied von Vergangenheit und Zukunft”, Bayerische Akademie der Wissenschaften, München, Mathematisch-naturwissenschaftliche Abteilung, Sitzungsberichte (1925), 133–175; Forman, Weimar, 88–91.
92. Born M., “Zur Quantenmechanik der Stossvorgänge”, Zeitschrift für Physik, xxxvii (1926), 863–7.
93. ibid., 865 (my translation).
94. Ref. 28.
95. Reichenbach H., “Wahrscheinlichkeitsgesetze und Kausalgesetze”, Die Umschau, lxxx (1925), 789–92.
96. Spengler, op. cit. (ref. 18), 419 of translation.
97. Born M., “Das Adiabatenprinzip in der Quantenmechanik”, Zeitschrift für Physik, xl (1927), 167–192, p. 192.
98. Weyl's assistance was acknowledged by Schrödinger in his first paper on wave mechanics; for his involvement in the development of matrix mechanics see Weyl to Jordan, 13 November 1925, 23 November 1925, and 25 November 1925, Sources for history of quantum physics (ref. 45), 18, 10 and Born to Weyl, 3 October 1925, archive of the Eigener Technische Hochschule, Zürich. Despite their intellectual differences, Weyl was at this time virtually an honorary member of the mathematics department at Göttingen, and he may have seen Born there when the latter returned from America in the spring of 1926: See Courant to Weyl, 19 February 1926 and 14 June 1926, ETH Zürich.
99. This attitude is clearest in his second paper on the subject, Born M., “Quantenmechanik und Stossvorgänge”, Zeitschrift für Physik, xxxviii (1926), 803–27.
100. For a detailed discussion of Born's work and a discussion of this aspect of its background see Hendry J., op. cit. (ref. 94), 125–31.
101. Forman, Weimar, 63–70.
102. For an idea as to the complexity of the causality issue see Bunge M., Causality (Cambridge, Mass., 1959).
103. Hence the confusion over the Bohr–Kramers–Slater theory.
104. Ref. 63 above.
105. Heisenberg W., “Ueber den anschaulichen Inhalt der quantentheoretisch Kinematik und Mechanik”, Zeitschrift für Physik, xliii (1927), 172–198; Bohr N., “The quantum postulate and the recent development of atomic theory”, Atti del Congresso Internazionale dei Fisica (Bologna, 1928), ii, 565–88, and Nature, cxxi (1928), 580–90. The same position was also taken early on by Jordan P., “Kausalität und Statistisch in der modernen Physik”, Die Naturwissenschaften, xv (1927), 105–7, and “Philosophical foundation of quantum theory”, Nature, cxix (1927), 566; it was also soon accepted by Born: Born M. “Ueber den Sinn der physikalischen Theorien”, Die Naturwissenschaften, xvii (1928), 109.
106. In a work that claims to be objective history, Forman's continued use of emotive language is most striking. One is even tempted to ask whether extrinsic influences led Paul Forman to ardently hope for, actively search for, and willingly embrace the theses he puts forward.
107. One might imagine that religious attitudes would constitute an important element of the milieu, but despite the importance generally attributed by historians to the role of anti-semitism in Weimar attitudes, Forman makes no mention of this, or of any other religious matter.
108. Yet another problem omitted by Forman concerns the isolation of intellectuals in general—even those adopting the views of the milieu—from the milieu. This is mentioned by Ringer and emphasized by Laqueur, op. cit. (ref. 10).
109. In this respect as in others, the role of the observer in quantum theory would appear to be a far more promising subject of study than that of causality.
110. There does appear, on the other hand, to be a degree of social determination on the explicit level in respect of the reception (as opposed to the creation) of science theories. Forman's second paper on the causality issue (ref. 3), is concerned with the more promising area of reception, and though it again runs into problems by leaving out of consideration differing degrees of familiarity with the internal background, it does suggest a strong social element to the short-term reception of the new quantum mechanics.