Planck’s search for a deeper understanding of the second law of thermodynamics led him to a strange and unexpected result—the concept of energy quanta. His conservative attitude toward this revolutionary discovery expressed itself in his attempts to reconcile the quantum with classical electrodynamics.
IN JANUARY 1910 Max Planck sent a paper to Annalen dar Physik on the theory of black‐body radiation. It was his first paper on this subject since the epoch‐making work in which he had introduced the concept of energy quanta almost a decade earlier. Planck had no new results to report, but he felt that it was time he expressed his views on what had been going on in the intervening years. Not that there was so very much to discuss: neither the problems of radiation nor Planck’s startling idea that energy could sometimes vary only in discrete steps had yet seriously caught the attention of most of his colleagues. Planck himself, of course, had thought a great deal about these things, as he remarked in a letter to Walther Nernst a few months later: “I can say without exaggeration that for ten years, without interruption, nothing in physics has so stimulated me, agitated me, and excited me as these quanta of action.” But his approach to the problems did not coincide with those of the relatively few others who had concerned themselves with the theory of radiation, and Planck wanted to point out the path that he considered most sensible and most promising for future success.
2. M. Planck to W. Nernst 11 June 1910. This letter is quoted in full in an unpublished manuscript by Jean Pelseneer entitled “Historique des Instituts Internationaux de Physique et de Chimie Solvay.” The manuscript is part of the archive “Sources for the History of Quantum Physics,” at the Library of the American Philosophical Society in Philadelphia.
3. M. Planck, Scientific Autobiography and Other Papers, translated by F. Gaynor (Philosophical Library, New York, 1949) p. 35.
11. M. Planck, S.‐B. Preuss. Akad. Wiss. (1897), p. 57; Papers I, 493.
12. E. Zermelo, Ann. Phys. (3) 57, 485 (1896), https://doi.org/ANPYA2 E. Zermelo, 59, 793 (1896); https://doi.org/ANPYA2, Ann. Phys. Also see R. Dugas, La théorie physique au sens de Boltzmann (Editions Griffon, Neuchâtel, Suisse, 1959) pp. 206–219.
13. M. Planck, Nobel Prize Address in A Survey of Physical Theory reprinted (Dover, New York, 1960), p. 36. 102; Papers III, 121.
14. L. Boltzmann, S.‐B. Preuss. Akad. Wiss. (1897) pp. 660, 1016, (1898) p. 182.
15. L. Boltzmann, Ann. Phys. (3) 57, 773 (1896). https://doi.org/ANPYA2 Also his Populäre Schriften (Barth, Leipzig; 1905) p. 406.
16. M. Planck, S.‐B. Preuss. Akad. Wiss. (1898), p. 449; Papers I, 532.
17. See, for example, P. and T. Ehrenfest, The Conceptual Foundations of the Statistical Approach in Mechanics, translated by M. J. Moravcsik (Cornell University Press, Ithaca, N.Y., 1959) p. 41.
18. M. Planck, S.‐B. Preuss. Akad. Wiss. (1899), p. 440.; Papers I, 560.
24. M. Planck, Verh. d. Deutsch. Phys. Ges. 2, 202 (1900); Papers I, 687.
25. See M. J. Klein, Archive for History of Exact Sciences 1, 459 (1962), and The Natural Philosopher (Blaisdell Publishing Company, New York) 1, 81 (1963). Also see K. A. G. Mendelssohn in A Physics Anthology, edited by N. Clarke (Chapman and Hall, London, 1960) p. 62 and L. Rosenfeld, Osiris 2, 149 (1936).
26. L. Boltzmann, Wien. Ber. 76, 373 (1877).
27. M. Planck, Verh. d. Deutsch. Phys. Ges. 2, 237 (1900); Papers I, 698; Ann. Phys. (4) 4, 553 (1901); https://doi.org/ANPYA2 Papers I, 717; Also the papers of reference 25.
28. M. Planck to R. W. Wood, 7 October 1931. This letter is part of the collection in the Archives of the Center for the History and Philosophy of Physics of the American Institute of Physics in New York City.
29. See the first article in reference 27 and also M. Planck, Ann. Phys. (4) 4, 564 (1901); https://doi.org/ANPYA2 Papers I, 728.
30. G. Hertz in Max Planck zum Gedenken (Akademie‐Verlag, Berlin, 1959) pp. 33–35.
31. E. Rutherford and H. Geiger, Proc. Roy. Soc. A 81, 162 (1908).
32. M. Planck, Vorlesugen über die Theorie der Wärmestrahlung (Barth, Leipzig, 1906) p. 162.
33. M. Planck to P. Ehrenfest, 6 July 1905. This letter is part of the Ehrenfest collection at the National Museum for the History of Science in Leyden.
35. M. Planck, Verh. d. Deutsch. Phys. Ges. 13, 138 (1911); Papers II, 249.
36. H. A. Lorentz, Phys. Z. 11, 1248 (1910). https://doi.org/PHZTAO This is actually a report by Max Born of Lorentz’s Wolfskehl lectures, “Alte und neue Fragen der Physik.”
44. R. W. James, I. Waller, and D. R. Hartree, Proc. Roy. Soc. A118, 334 (1928). See also Fifty Years of X‐Ray Diffraction, P. P. Ewald, ed. (Oosthoek, Utrecht 1962) pp. 126, 230.
45. M. Planck, S.‐B. Preuss. Akad. Wiss. (1914) p. 918; Papers II, 330.
46. Op. cit. reference 32, pp. 154–156.
47. W. Nernst, Gött. Nachr. (1906), p. 1. See also F. Simon’s Guthrie Lecture in Yearbook of the Physical Society of London 1956, p. 1.
49. M. Planck, The Theory of Heat Radiation, translated by M. Masius 2nd Ed. (1913), reprinted (Dover, New York, 1959), p. vii.
50. See his Wolfskehl Lecture of 1913 in Vorträge über die kinetische Theorie der Materie und der Elektrizität (B. G. Teubner, Leipzig, 1914) p. 3; Papers II, 316. Also see L. Rosenfeld in Max‐Planck‐Festschrift 1958 (Deutcher Verlag der Wissenchaften, Berlin 1959), p. 203.
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