2. Sample Outlines for Interviews
The two outlines which follow, the first complete and the second represented by a fragment, illustrate the-preparatory material sent, whenever possible, to a potential informant in advance of an interview. For the role of these outlines in the project's work, see the discussion in Chapter I, Section 3.
OUTLINE OF SUBJECTS FOR DISCUSSION WITH R. L. KRONIG
- Early Life and Education (1904-19)
We are much interested in discovering how you became involved with science, how you first began to pursue it, and what encouragement you received. In particular:
- How was your interest in science first awakened? Who encouraged your interest and how? When did you determine on a career in science ? What were the opportunities for such a career in the United States at the time? What sort of support was available (in the way of scholarships, etc.) to a capable student?
- How much mathematics and science were you taught at the Gymnasium in Dresden? How well prepared were you in these subjects when you entered the University?
- Columbia University (1919-24)
- Curricula: What course of study did you follow at the University, i.e., what subjects did you take and what textbooks did you use? What topics and problems in modern physics were particularly emphasized? Who were the most influential teachers? How did you choose your thesis topic?
- General Work: During your Universit3r training there occurred many developments which in retrospect have been of the greatest importance in the growth of modem physics. We are very much interested to learn of the immediate reactions of people to the first announcements of these discoveries. What can you tell us about the reactions of yourself, fellow students and teachers to events such as:
- The Stern-Gerlach experiment
- The Compton effect
- de Broglie's thesis
- The Bohr-Kramers-Slater theory
- Kratners Dispersion theory
- The Burger-Dorgelo sum rule
- III. Traveling Fellow (1924-25)
- The various institutions you visited during your post-doctoral year must have been rather different from Columbia and different from one another. What differences in approach to physics, emphasis on specific problems, etc., particularly struck you?
- How were you received by both staff and students at these institutions? What was your position, e.g., did you attend lectures and seminars, participate in colloquial etc.? How did you arrange for your visits?
- General WorkAs in II, B. we are much interested in your recollections of reactions to the great developments of 1925-26.
- What can you tell us about responses to Heisenberg's initial paper, and the subsequent elaborations of Born and Jordan? In particular, how did you feel about the letter from Heisenberg you quoted in "The Turning Point?" Were you able to make much sense out of it? You must also have discussed it with Fermi on your skiing expedition in the winter of 1925-what did he then think about it? How did people in Copenhagen react?
- How was Pauli's paper on the "exclusion principle" received? Was everyone as enthusiastic as yourself?
- Your Own Work
- When and how did you first become interested in spectral intensity problems? How did you happen to collaborate with Goudsmit on them ? What did you think of the extension of the sum rules by Ornstein and Burger [Zs. f. Phys. 31 (1925): pp. 355-361] in which they claim that there is a "Nichtübereinstimmung" between experiment (the sum rules) and theory (the requirements of the Correspondence Principle) ? Was this conclusion accepted by many?
- In your own important work on the extension of the sum rules [Zs. f. Phys. 31 (1925) : pp. 885-897; 33 (1925): pp. 261-272] you rely on vector models to apply the Correspondence Principle results of Sommerfeld and Heisenberg [Zs. f. Phys. 11 (1922): pp. 131] to the intensity problem. In the first of these you use Landé's version of the Rumpf model, and in the second, Heisenberg's new "third scheme" [Zs. f. Phys. 32 (1925) : pp. 841 ]. Did you think Heisenberg's explanation of the different term-systems convincing? In both cases you are obliged to assign a quantum number to the Rumpf. Was Pauli's observation that all quantum numbers must refer to the electron then not considered a serious objection, or was the Rumpf retained only as a pis aller? Did you make any effort to express either model in terms of your idea of the spinning electron?
- Your very full and balanced account of the history of the discovery of electron spin in "The Turning Point" leaves us with only a few questions on this subject. First of all is the question of the effective nuclear charge-dependence of the optical doublet separation. Was it generally considered to be a serious objection against the foundations of the old quantum theory? Was Sommerfeld's relativistic explanation at all maintained after Landé's thorough criticism? Presumably it was your success in deriving the Z4 dependence on the basis of the spin-orbit interaction that impressed Landé.
Had you also worked out an application to the anomalous Zeeman effect? Did Pauli succeed in talking you out of the idea mainly on the basis of the celebrated "factor of two?" What did Landé think about your publishing your idea after the talk with Pauli? What had he thought before? What objections were raised in Copenhagen? When you spoke on the subject in Copenhagen in November, after the appearance of the Goudsmit-Uhlenbeck paper, you say you were received with "indifference." Did your talk cause no comment at all, or were the old objections again advanced?
Your experience in this matter also suggests questions of a more general nature. For example, how much "approval" (in the form of conversations and letters with authorities) did one seek before publishing a new idea? How limited a circle were the "authorities ?" What was the refereeing policy of the leading journals? Were new ideas fairly well known to most physicists before ever reaching print? Is the present situation significantly different in these respects from the 1920s?
- First Academic Positions (1926-31)
- What was your position in the physics department at Columbia? What courses did you teach? What problems in modern physics did you emphasize? When you left Columbia on your first European fellowship was it expected that you would return?
- How had the curriculum, especially with respect to modern physics, changed in your absence? Did you have any influence in determining the material offered? Was there a general conviction of the need to "modernize?" How did the situation at Columbia compare in this respect with that in other important American Universities? How quickly was the change achieved and how was it accomplished?
- How did you feel about Schrödinger's theory when it first appeared? Did you think it more fundamental than matrix mechanics? What did you think of the appeal to Hamilton's optical-mechanical analogy? Did you think then that a mechanical explanation of quantum phenomena was possible? Do you recall the opinions of others?
- What was the origin of your interest in band spectra? Where did you acquire the mathematics necessary to handle such applications of the Schr6dinger equation?
- How did it happen that Pauli offered you the position as his assistant? Had you already decided to leave Columbia permanently? Why did you decide to pursue your academic career in Europe ?
- Apparently you returned to Copenhagen before going to Zurich, and were there during the period when complementarity was developed. What can you tell us about the genesis and reception of this concept? Was everyone at Copenhagen convinced?
- You indicate in "The Turning Point" that you, Pauli and Scherrer frequently discussed "subjects from physics" together. Can you give us some idea of the content of these discussions? For instance, what was said about the uncertainty principle and complementarity? How was Dirac's theory of the electron received, and what was thought of the idea of "holes?" What were then considered to be the most important questions in contemporary physics?
OUTLINE OF TOPICS FOR DISCUSSION WITH W. HEISENBERG FEBRUARY, 1963
- University of Munich (1920-22)
- Student Life and Curriculum: I should like to get as full a picture as possible of what it was like to be a student of physics at Munich in these years. Inevitably we shall overlap a few topics already discussed, but there must be far more to say. Among the sorts of questions which I hope you will illuminate with concrete episodes and anecdotes are:
- What subjects in physics and related sciences (e.g., mathematics, astronomy, chemistry, geology) was a prospective physicist expected to master, and how did he go about acquiring them?
- What was the relative role of lectures, colloquial independent reading, individual work with teachers, and conversations with other students in this preparation? Where, how, and for how long did these various forms of preparation go on?
- What subjects did you yourself particularly prepare, and how did you work them up? This is especially difficult for us to estimate because your independent work starts so nearly simultaneously with your study of physics.
- Who were the leading teachers among the professors and docents? What was their relationship to each other and to what extent did students have to choose between them? Was there any resulting fragmentation among the student group?
- How many students of physics (at the various levels) were there at Munich? Who were the leaders among the advanced students, and what form, if any, did their leadership take?
- What can you tell us of Pauli's interests working habits, and mode of life in these formative years? What was his relation to Sommerfeld and others? Was he already deeply interested in quantum problems when you first knew him, or did relativity still dominate?
- What can you tell us of the interests and activities of other students at this time, e.g., Nordheim and Wentzel?
- The State of Physics:
- How much research on non-quantum topics was carried on at Munich in these years, and what problems did it mainly deal with? How much did these problems impinge on the Sommerfeld group? (Your first published paper and your thesis -- items 1 and 7 on the attached bibliography -- both fall in this non-quantum category!)
- In quantum mechanics itself what problems were mainly worked on? To what extent did these emanate from Sommerfeld? How much did he encourage work on problems outside his own fields of interest? Were people still concerned with cubical and other similar atom models?
- To what extent did quantum mechanics already seem to be facing an impasse which would force a fundamental reformulation? (Here it may be important to distinguish 1920 from 1922 as it is surely important to distinguish Munich from other institutions.) If there was already a sense of crisis, what problems and what aspects of the general situation in physics (e.g., conflict with classical radiation theory, wave-particle duality) were particularly responsible? In any case, what attitudes were taken towards the various unresolved problems and paradoxes of quantum physics?
- In particular, what attitude was taken towards the Stern-Gerlach experiment? Presumably the result was pleasing, since space-quantization was an idea of Sommerfeld's. But were the problems that bothered Einstein and Ehrenfest (and Stem himself) of much concern to people in Munich?
- The same sort of question can be asked about the Compton effect.
- How did the news of new discoveries like the preceding first get to Munich; in published articles, letters, or by word of mouth? In any case, how was it then propagated and discussed? In particular, what was the role of colloquia, and what colloquia were there?
- What journals, particularly foreign journals, did physicists regularly follow? To what extent did Sommerfeld or others emphasize keeping abreast of the literature as a responsibility for physicists?
- What journals were considered the best ones in which to publish and why? How did they differ in rigidity of editorial policy, speed of publication, and so on?
- Your own Work (and Sommerfeld's):
The questions that follow deal with areas in which I have reason to know you were interested. But in at least one significant case, dispersion, I would have no question to ask except for a remark of yours in our last interview. Please add other such topics where you can. Because we can only hear of it in this way, your unpublished work is at least as important to us as your actual public contributions.
- Early Investigations of the Anomalous Zeeman Effect:
You have told me about your first problem in Sommerfeld's seminar (magnetic energy levels which led you to half-integral quantum numbers), and I should be glad to hear more about this. But it is even more important to see whether and how you and Sommerfeld followed up these investigations. For example:
- You must have worked with doublets to get half-integral quantum numbers. Did you deal with triplets as well ? How much of what appears on this topic in the 3rd edition of Atombau waited for the work of Landé in 1921 [Zs. f. Phys. 5 (1921): pp. 231-241, and 7 (1921) : pp. 398-405)]?
- You told me of Sommerfeld's resistance to the idea of half quantum numbers, and indeed in Atombau, (3rd ed., 1922) he lets m change by ± 2,0 in order to avoid them. But, meanwhile, your own work on the Rumpf and Landé's papers must have shaken this conviction. Can you tell us of conversations on this subject? Also, did the problems of zero-point energy and of rotational spectra (which can point in the same direction) play a role here?
- What was the reaction at Munich to Landé's 1921 papers ? In particular, how was the idea of inner quantum number as total angular momentum received? (The identification is scarcely mentioned in Atombau, 1922.) Was the problem of the anomalous gyromagnetic ratio taken as central from the start?
- Generally, what were the relations with Landé? Was there much correspondence between him and Sommerfeld as well as with you?
- How involved was Pauli with these problems before his departure for Copenhagen?
- Sommerfeld's paper on the Voigt Formula [Zs. f. Phys. 8 (1922): pp. 257-269]: What can you tell us of the way this paper originated? For example, had the Voigt-formula been well known before Sommerfeld retrieved it? How did you and Sommerfeld react to this strangely classical treatment of the atom ? Was any attempt made to develop a similar technique for triplets?
- The Rumpf Model (paper 2 in attached bibliography) :
- How did this model come into being, and with what other forms did you experiment in the course if its development? For example, in the presence of a field did you try to space-quantize the total angular momentum instead of electron angular momentum, and in the absence of field did you consider quantizing Rumpf orientation relative to electron angular momentum instead of vice versa Would not the latter treatment have simultaneously avoided mathematical difficulties and improved the fit to physics?
- How did you feel about the model? In particular, were you particularly concerned by getting a total angular momentum different from the inner quantum number for triplets, by the non-quantum mechanical behavior of the Rumpf, and so on? Were you aware of the problem of the Aufbauprinzip?
- I particularly hope you will say as much as you can about the genesis, reception, and development of the idea that angular momentum is only statistically conserved in quantum jumps and of the consequences that you draw from it. (This is in equation 10 of the paper, which in retrospect appears an early Permanenzgesetz.)
- How closely was Sommerfeld involved in this work, and how did he react to it? What role did his apparent distrust of models play?
- What other reactions both before and after publication do you recall?
- Multiplet and Zeeman Component Intensities (paper 4) : This paper raises fewer technical problems than the preceding, but the questions about genesis and reception still apply. In
- This is Sommerfeld's first use of the correspondence principle, of half-integral quantum numbers, and of the inner quantum number as total angular momentum. Do controversies or conversions provide some part of the background?
- How did you and Sommerfeld feel this paper related to the Rumpf model? (The two are incompatible in the relation between total angular momentum and inner quantum number; nevertheless the Rumpf model is used to correct angles of space quantization in the closing section. Was the correction forced upon you by the data?)
- In general, how did you and Sommerfeld work together on a paper? What determined whether authorship was joint or single?
- Higher Multiplets: What role did these play in your and Sommerfeld's thought during the Munich period? Were you still there when Catalan's manuscript was received by Sommerfeld? What impression did it make?
- Paper 3, dealing with relativistic fine structure, is one of your rare involvements with X-ray spectra. How expert did you -become in this area, and how important was a knowledge of X-rays in your own work on visible spectra? Did you or did Sommerfeld at all concern yourselves with the source of the energy difference that produces "irregular" doublets and for which Sommerfeld invented the Grundquantenzahl?
- Dispersion: You mention having thought deeply about this problem before going to Göttingen for the meetings in summer, 1922. What had brought it to your attention? (Did you know Ladenburg's 1921 paper, and, if so, how did you react to it?) More generally, were people at Munich much concerned with this problem during your time there? Was it recognized as a key difficulty for quantum theory?
- Sommerfeld: This is a residual category. He is too important a figure not to as ask you once more for anything else you can tell us about him as a teacher, investigator, and human being.
- The Göttingen Meeting: For a number of physicists Bohr's lectures were clearly a turning, point. We should therefore be grateful for anything about the meeting that you can tell us. For example:
- People who were there and your personal impressions of them and of the atmosphere.
- Extent to which people understood the lecturers, their reactions, and responses, both private and public.
- Your own talks with Bohr and with others.
- The extent to which these lectures changed your impression of the state of quantum mechanics.
(The following is a list of important articles covering subjects and periods with which we are most concerned and familiar.)
- 1922. "Die absoluten Dimensionen der Kármánschen Wirbelbewegung," Phys. Zs. 23 (1922), 4 pp.
- 1922. "Quantentheorie der Linienstruktur und die anomalen Zeemaneffekte," Zs. f. Phys. 8 (1922), 25 pp.
- 1922. "Eine Bemerkung über relativistische Röntgen Dublefts und Linienscharfe," Zs. f. Phys. 10 (1922): pp. 393-398; with A. Sommerfeld. (Munich, 3 Aug 1922.)
- 1922. "Die Intensität der Mehrfachlinien und ihrer Zeemankomponenten," Zs. f. Phys. 11 (1922): pp. 131-154; with A. Sommerfeld.
- 1923. "Phasenbeziehungen bei den Bohrschen Modellen von Atomen und Molekeln," Zs. 1. Phys. 14 (1923): pp. 44-66; with M. Born. (Göttingen, 16 Jan 1923.)
- 1923. "Elektronenbahnen in angeregten Heliumatom," Zs. f. Phys. 16 (1923): pp. 229-243; with M. Born. (Munich and Göttingen, 11 May 1923.)