Space quantization: Otto Stern's Lucky Star

Daedalus

Volumn 127, Issue 1, 1998, Pages 165-191

  Friedrich, Bretislav ^a   Herschbach, Dudley ^b  

^a HARVARD UNIVERSITY   (United States)

^b HARVARD UNIVERSITY   (United States)

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[No Author keywords available]

Indexed keywords

EID: 0041931435     PISSN: 00115266     EISSN: 15486192     Source Type: Journal    
DOI: None     Document Type: Article

References (46)

1. Gerald Holton, The Advancement of Science, and Its Burdens: The Jefferson Lecture and Other Essays (Cambridge University Press, 1986), 197.
2. Unless otherwise cited, quotations from Bohr or Einstein and literature references to papers mentioned can readily be found in one or another of three splendid books by Abraham Pais (all published by Oxford University Press): "Subtle is the Lord. . .": The Science and the Life of Albert Einstein (1982);
3. Inward Bound: Of Matter and Forces in the Physical World (1986);
4. or Niels Bohr's Times (1991). Curiously, Pais makes only glancing reference to the Stern-Gerlach experiment, in a couple of footnotes.
5. Emilo Segre, "Otto Stern," in Bibliographical Memoirs of the National Academy of Sciences 43 (1973), 215-236. References for quotations and Stern's work not otherwise cited can be found in this article.
6. K. Mendelssohn, The World of Walther Nernst (London: MacMillan Press, 1973), 95.
7. F. Hund, Geschichte der Quantentheorie (Bibliographisches Institut, Mannheim, 1975). According to Hund, Pauli dubbed this vow the "Ütli Schwur," a nod to the legendary "Rütli Schwur" of Wilhelm Tell, which bound together some of the Swiss cantons. Yet von Laue, a Nobel laureate in 1912, was among the first (from 1919 on) and most persistent to nominate Bohr for the Nobel Prize, which Bohr received in 1922;
8. Bohr did likewise for Stern, who received the prize in 1943. See Pais, Niels Bohr's Times, 213-216.
9. Pais, Niels Bohr's Times, 146.
10. For a pertinent analysis, see Arthur I. Miller, Imagery in Scientific Thought: Creating 20th-century Physics (Boston: Birkhaüser Boston, 1984); cf. 132-133.
11. Peter Galison, How Experiments End (Chicago: University of Chicago Press, 1987), 50.
12. Wolfgang Pauli, "Remarks on the History of the Exclusion Principle," Science 103 (1946): 213.
13. A volume commemorating the centennial of Stern's birth contains an English translation of his 1921 paper. See Zeitschrift für Physik D 10 (1988): 114-116.
14. In 1960, Otto Stern was retired and living in Berkeley, where one of the authors (D. H.) had the opportunity to hear Stern reminisce about his career. This is not an actual quotation from Stern but is cast in a first-person, "as told to" form in an attempt to capture his way of telling stones. Fuller versions are given in Dudley Herschbach, "Molecular Dynamics of Elementary Chemical Reactions," Angewandte Chemie International Edition in English 26 (1987): 1225.
15. J. Mehra and H. Rechenberg, The Historical Development of Quantum Theory (New York: Springer, 1982), 435.
16. J. Mehra and H. Rechenberg, The Historical Development of Quantum Theory (Ibid. The "very good mechanic" was Mr. A. Schmidt.
17. Walther Gerlach, "Otto Stern zum Gedenken," Physikalische Blätter 25 (1969): 412;
18. "Zur entdeckung des 'Stern-Gerlach-Effektes,'" Physikalische Blätter 25 (1969): 472.
19. Stern, "as told to Herschbach" (see note 11), 1225.
20. Gerlach, "Zur entdeckung . . . ," 473.
21. W. Schütz, "Persönliche Erinnerung an die Entdeckung des Stern-Gerlach-Effektes," Phys. Blätter 25 (1969): 343.
22. Max Born, My Life: Recollections of a Nobel Laureate, (London: Taylor & Francis, 1978), 195.
23. Gerlach also sent in early 1922 a photograph of the collector plate showing the beam splitting to Niels Bohr as a postcard, with the message: ". . . attached [is] the experimental proof of directional quantization. We congratulate [you] on the confirmation of your theory." Front and back views of the postcard are shown in A. P. French and E. F. Taylor, An Introduction to Quantum Physics (New York: Norton, 1978), 437.
24. In the Stern centennial volume, Isidor Rabi (as told to John Rigden) recalls, "As a beginning graduate student back in 1923, I . . . hoped with ingenuity and inventiveness I could find ways to fit the atomic phenomena into some kind of mechanical system. . . . My hope to [do that] died when I read about the Stern-Gerlach experiment. . . . The results were astounding, although they were hinted at by quantum theory. The separation of the beam of silver atoms into two components occurred as if these moments pointed either one way or the opposite way. There was no mechanism that would orient them in one way or another since on leaving the source they were arranged quite statistically . . . the whole thing was a mystery. . . . This convinced me once and for all that an ingenious classical mechanism was out and that we had to face the fact that the quantum phenomena required a completely new orientation."
25. See Zeitschrift für Physik D 10 (1988): 119.
26. Since Stern was Einstein's "first pupil," it seems apt to note here that magnetism and spin are both consequences of relativity. For magnetism this was shown in 1912 (the year Stern joined Einstein) by Leigh Page, a young Yale professor; a lovely discussion of Page's paper is given by Edward M. Purcell, in H. Woolf, ed., Some Strangeness in the Proportions: A Centennial Symposium to Celebrate the Achievements of Albert Einstein (Reading, Mass: Addison-Wesley, 1980). The relativistic origin of spin was shown in 1928 by Paul Dirac; his awesome work is well described by Pais. For a delightfully attractive, nontechnical treatment of all things magnetic,
27. see James D. Livingston, Driving Force: The Natural Magic of Magnets (Cambridge, Mass: Harvard University Press, 1996).
28. Furthermore, while Stern selected silver because it had a single valence electron, in 1921 he could not be certain that its inner electrons form a "closed shell," i.e., are paired up with all the spins and orbital angular momentum projections adding up to zero.
29. Magnetically induced birefringence in gases, known as the Voight or Cotton-Mouton effect, does in fact occur. It is a very weak, secondary effect (quite different in origin and magnitude from that implied by the Bohr model). See, for example, A. D. Buckingham, W. H. Prichard, and D. H. Whiffen, Transactions of the Faraday Society 63 (1967): 1057
30. and R. Cameron, et al, Physics Letters A 157 (1991): 125.
31. Ronald G. J. Fraser, "The Effective Cross Section of the Oriented Hydrogen Atom," Proceedings of the Royal Society A114 (1927): 212. This paper summarizes experimental evidence that the ground state of several atoms, including hydrogen, sodium, and silver, are isotropic, contrary to the Bohr-Sommerfleld model. These results agree with the 1926 wave mechanics of Schrödinger, according to which for these atoms the ground-state orbital angular momentum and associated magnetic moment are zero. Fraser concludes "that which orients" and thereby produces Stern-Gerlach splitting is "apparently" the spin magnetic moment.
32. Norman F. Ramsey, "Molecular Beams: Our Legacy from Otto Stern," Zeitschrift für Physik D 10 (1988): 121.
33. John S. Rigden, Rabi: Scientist and Citizen (New York: Basic Books, 1987). This superb biography has much material about Stern and the impact of the Stern-Gerlach experiment; see especially 46-65.
34. Gerald Holton, Thematic Origins of Scientific Thought: Kepler to Einstein, rev. ed. (Cambridge, Mass.: Harvard University Press, 1988).
35. Another American physicist luckily influenced by Stern was Ernest Lawrence. They met in 1929, on coincident visits to Harvard during Christmas time. Unaccustomed to Prohibition, Stern asked Lawrence to take him to a speakeasy. While contemplating the circular rings left by their wine glasses, Lawrence diagrammed an idea he had been mulling over for months, a means to accelerate ions in a magnetic field. Stern urged him to stop talking about it, get back to his lab at Berkeley, and work on the idea; Lawrence took the advice and soon developed his cyclotron. This story comes from interviews by Nuel Pharr Davis, Lawrence & Oppenheimer (New York: Simon & Schuster, 1968), 27-28.
36. A recent survey, entirely nontechnical, is given by Dudley Herschbach, "The Shape of Molecular Collisions," in Martin Moskovits, ed., Science and Society (Concord, Ontario: House of Anansi Press, 1995), 11-28.
37. The volume honors John C. Polanyi. Key references can be found in a recent festschrift issue (honoring Yuan T. Lee) of the Journal of Physical Chemistry A 101 (1997): 6339-6820.
38. As yet, the only nontechnical account is by Bretislav Friedrich and Dudley Herschbach, "Spatial Orientation of Molecules," Physics News (1992): 14-15.
39. References to research papers can be found in Hansjurgen Loesch, Annual Review of Physical Chemistry 46 (1995): 1147.
40. Especially pertinent is recent work related to the Voigt effect; see Alkwin Slenczka. Journal of Physical Chemistry A 101 (1997): 7657.
41. Mendelssohn, The World of Walther Nernst, 124.
42. Although Pauli "in effect" was invoking electron spin (with his fourth quantum number specifying its two projections), nonetheless he adamantly rejected the idea that the electron could have an intrinsic angular momentum. He also dissuaded others, prior to Uhlenbeck and Goudsmit. This was doubly ironic. Despite his opposition to the notion of electron spin, he had been the first to suggest that nuclei might have spin. Also, although Pauli had a deep grasp of relativity, his error had to do with the relativistic description of the electron motion. See George F. Uhlenbeck, "Personal Reminiscences," Physics Today 29 (1976): 43.
43. We are unable to resist noting an appealing coincidence. In Kyoto, Japan, the Ryoanji Temple has a garden facing the abbot's quarters which consists solely of four groups of rocks set on white sand: 1, 3, 5, 7; the garden dates from the Muromachi Period but its origin and any intended symbolism is not known. Matsuki Kokichi, ed., The Gardens of Kyoto, (Kyoto: Kyoto Shoin Co, 1987), 102.
44. Gerald Holton, Einstein, History, and Other Passions (Reading, Mass.: Addison-Wesley, 1996).
45. Gerald Holton, Science and Anti-Science (Cambridge, Mass.: Harvard University Press, 1993).
46. For a sprightly survey and (in our opinion) sensible perspective, see Jay A. Labinger, "The Science Wars and the Future of the American Academic Profession," Dædalus 126 (4) (Fall 1997): 201-220.