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Interview of Philip Morrison by Charles Weiner on 1967 February 7, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/4343
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Early interest in radio; Carnegie Institute of Technology's physics department, 1932-1936; first department research program; summer research experience, 1932-1936; graduate work at University at Berkeley under J. Robert Oppenheimer, 1936-1940; sources of fellowship support; Berkeley journal club; interactions of theorists and experimentalists at Berkeley, and with Stanford University and Caltech, late 1930s; reactions to fission; nuclear physics at University of Illinois, 1941-1942; sources of funds for accelerators to 1941; recruitment to University of Chicago Metallurgical Laboratory, 1942; Los Alamos Scientific Laboratory, 1944-1946, personnel, research, plans and expectations for peacetime work; scale and financing of physics at Cornell University in immediate postwar period; rise of particle physics after 1949; differences between pre- and postwar physics, job expectations, style of research; evolution of accelerating and detecting methods, 1920s to 1950s; connections between physics and astronomy. Also prominently mentioned are: Paul Aebersold, Luis Walter Alvarez, Hans Albrecht Bethe, Raymond Thayer Birge, Niels Henrik David Bohr, Kevin Burns, Robert F. Christy, Immanuel Estermann, Enrico Fermi, Richard Phillips Feynman, William Alfred Fowler, Otto Robert Frisch, Maurice Goldhaber, Harry Hower, Fred Hoyle, Donald W. Kerst, Charles Christian Lauritsen, Ernest Orlando Lawrence, Philip A. Morrison, J. Robert Oppenheimer, Isidor Isaac Rabi, Ernest Rutherford, Emilio Gino Segrè, Otto Stern, Leo Szilard, Robert Rathbun Wilson; Allegheny Observatory, California Institute of Technology, Cavendish Laboratory, Columbia University, Cornell University, International Conference on High Energy Physics, Los Alamos National Laboratory, Massachusetts Institute of Technology, Princeton University, United States Army, United States Navy, United States Office of Naval Research, University of Birmingham, University of California at San Diego, University of Chicago Metallurgical Laboratory, and University of Illinois at Urbana-Champaign Nuclear Engineering Program.
Today is February 7th. This is an interview with Professor Philip Morrison. Questions are being asked occasionally by Charles Weiner. We’re sitting in Professor Morrison’s office at MIT. I know that you were at Carnegie Tech. I think you left there in 1936. That means you probably started there —
In 1932. I’d like to know what your impression was of the field of physics at the time, what the hot things were in the field, what motivated you. I’m not at all sure if you went there to study physics, and if not, how you became interested in physics, which aspects of it appealed to you, and what you knew about nuclear physics.
1932, of course, is a very long time ago. And at that time, I was a young high school graduate. I’d taken physics in high school and I liked it very much. I regarded it as an indispensable help to design radio equipment, which I was really interested in, and I entered Carnegie Tech as an electrical engineering student. My dream was to go into electrical engineering, become a radio engineer and design radio equipment. And I had been an amateur radio operator, and was interested in these matters. In the course of the first year, it became clear to me that the courses in physics, and especially the people in physics, were much more the sort of people that I had wanted to work with. They were interested in how things worked, whereas the engineering department seemed much less interested in that and much more routinized and concerned with details of operations in which I wasn’t interested.
Who were the people in physics?
Well, the most impressive figure at that time, the only one I knew, who taught freshman physics and was the head of the department was a man named Harry Hower, by no means a distinguished physicist, but a man who had been a quite well-known optical designer. That was his great forte. He designed lenses and lighthouse equipment, and he was always talking about his experiences as a lighthouse equipment designer for Panama Canal lights, and a few things of this sort. And he was an energetic, cheerful, witty lecturer. I don’t think he had any particular connection with modern physics. At that time, in ‘32, I would say there was almost no research at Carnegie Tech.
In any field?
In physics. In chemistry, and especially metallurgy, in mining engineering, metallurgical engineering, there was a lot of work. The Bureau of Mines was a large federal establishment halfway connected to Carnegie Tech, and this was quite useful. But at the time I think it would probably not be a great deal different here. Probably here at MIT it would be ten years earlier when the same statement would have applied. Then it was regarded primarily as an engineering center, and research in anything—development, yes, certainly; design, by all means—but the main emphasis was on skillful maintenance and choice for operating engineering accomplishments. Bridge design by picking the right things out of the handbook. This was the sort of thing that you worked on.
With a lot of industry interest and industry support of projects?
Well, there had been. There was not—this was the height of the Depression. There was no industry interest whatever. It was all very tight. There was no use for the engineers. Graduate engineers were not getting jobs.
How large was the Physics Department, do you remember?
The number of persons?
The number of faculty.
Faculty? A dozen at least. It was a pretty good-sized department, because, like all engineering schools, the department had the task of teaching freshman physics to every student in the school, 2500 students or so. And then what happened was that in ‘33-‘34, because of—I don’t remember the name of the man who did it, but one of the administrators at Carnegie Tech, it was either the dean or the vice president, I don’t think it was the president—by the way, the president changed about that time, so there was a general new spirit coming—succeeded, about ‘33 or ‘34, in attracting Otto Stern, to come to Carnegie Tech and begin a molecular beams laboratory. And Stern and Estermann came in ’33—
— from Europe?
From Germany. Maybe they had spent a half year in England as refugees. This was the time, of course—this was very clear—when the refugee market was booming, and every respectable American institution could try to get some. I think in the case of Carnegie, it was hot so much that they had a close connection or much concern about research, but whoever this man was—I think it was a man called Hammerschlag—this administrator had a long social connection with Germany. He knew the German universities. He was himself trained in a German university. And he knew that good German professors were going, and he was going to get some of those good German professors, come what may. And he probably had a feeling that he was helping save people, refugees, from the Nazis, who were in terrible shape. Of course Otto Stern was a Nobel laureate at that time and had been a famous man for many years, and his assistant, Estermann, who’s now an elder statesman of some consequence, came with him, and they began a laboratory in the halls of Carnegie Tech. I remember very clearly seeing them for the first time. It was quite a shock—very different from anybody. They looked really marvelous!
In what way? Did it fit the stereotype that you had in your mind of the European?
Well, a little bit—they were two completely opposite types. They controlled your stereotypes. There was Professor Stern, a great beer-drinking fellow with a big, black, bushy moustache, and Estermann, very thin ascetic-looking fellow, following him around. It was altogether—clearly, these were men of character, and there was no doubt about that. And they were known to be, you know, prodigiously able. And we never saw them, except passing in the hall, I literally never exchanged a word with Otto Stern in the three or four years that I was there when he was.
Did they have any interaction with anyone else in the department?
No, not with any of the undergraduates. They brought in a few graduate students, and there were a couple of young men in the department who began to work in the molecular beams lab. One of them was Leberknight, whom the undergraduates knew quite well, who was an infra-red man from Hopkins, and I think—I am not quite sure—he began to work in that field. But by and large they were an enclave in the Physics Department. The Physics Department was rather proud of it, but didn’t know quite how to manage it. Perhaps Stern gave us a colloquium once, I’m not quite sure. I’m sure I didn’t understand it, but perhaps he did. But I would say, in ‘32, ‘33, I was absolutely ignorant of the existence of neutrons, and the fact that they’d recently discovered—I had no idea about that at all. By ‘36, I vaguely knew it. I had taken a course in modern physics. We had two or three very able people, I remember quite well. Leberknight was one, Nathanson was the man who taught modern physics—again, a physicist of modest reputation—and T.L. Smith of the Mathematics Department taught theoretical physics. So from people like this, one would hear occasional things dropping, novelties and so on. But I never—I was innocent of quantum theory or anything of this kind.
And it didn’t show up in any of the courses?
No. We used Crowther’s book. I remember that. That was the most advanced book.
The same Crowther who subsequently wrote history of science?
That’s right, and it was called, what? Production to Modern Physics or Atomic Physics or Atoms and so we learned whatever was in that book. We learned about the DeBroglie Wave, I expect. I’m guessing, but I’m pretty sure we learned lambda equals h over mv [Z = h/mv], but that’s about it.
To get back to the molecular beams lab, did this exist before Stern came?
Oh, no, no. He came and established it.
In the height of the Depression?
Refugee or not, where did the money come from?
I don’t know, but it wasn’t much money. They just—I don’t know. I suppose the Institute had an endowment, and I suppose they managed to say that this was an expansion they could make if they didn’t do something else that year. They just took on another professor of physics. Or they might have gotten foundation support somewhere, I don’t know.
I don’t remember if you told me specifically when you became a physics major.
At the end of my freshman year. At the end of the freshman year, there was a scheme in which the prospective— Well, the freshman had the opportunity of going and hearing recruiting talks by each of the departments, and of course I was a confirmed electrical engineer, but you recognize that freshmen all had a uniform program. That’s quite typical. So you didn’t have to make up your mind, you just had these intentions. And I listened to the electrical engineering department, I listened to the physics department man, and there was no question that physics was exactly what I wanted to do—even if I wanted to stay in radio, which I think at the time I did think of, it was clear that the best training for a radio career of design and making new things was clearly much better in physics than in electrical engineering.
Did you have in mind continuing in graduate school at the time?
I didn’t know about it.
But you had some sort of a career goal in mind.
Yes, I definitely wanted to become a radio engineer. I wanted to design radio equipment and do propagation experiments and do all sorts of things with radio of a novel sort.
Then you didn’t hear, or weren’t aware of the developments in nuclear physics until your senior year?
That’s right, till about my senior year.
Why is that? Because you weren’t interested, or because it wasn’t being talked about there?
It wasn’t being talked about.
Did you read any journals at the time? Was this common to do?
No. No. Physical Review, one could see. I think I maybe saw the first copies of Physical Review when I was a junior or something. Looking up some circuitry. I remember, I did a lot of work outside the curriculum, helping people in the lab and so on, tried very hard to make a—I remember three or four jobs I had, sort of apprentice research jobs. I tried very hard to make a scale of two, a Wynn-Williams thyrotron circuit scale of two work, which was about the level that we could manage then, and it was not easy for me. I’ve forgotten the name of the man I worked for. It was one of the people in the Physics Department. I tried hard to make it work. It didn’t work very well; but he had gotten the idea, and he wanted to make a flip-flop. I remember also seeing a demonstration from some people at Westinghouse Laboratories. We knew about Westinghouse Laboratories. That was perhaps the most advanced technology that we had ever heard of. He came around and showed us a big box, circuitry, the size of a file cabinet, a ‘scope, that he could display a W on the ‘scope as a consequence of this. We thought that was pretty grand, to have a W. That was the first sort of television idea. Then, I went to work one summer for the observatory, Allegheny Observatory in Pittsburgh, for a man called Smith, if I’m not mistaken—no, Burns, Kevin Burns.
He was still there?
You know Kevin Burns?
I know of him—sure. He was…
A fine old spectroscopic gentleman, and he was the man who established precision comparison wavelengths, of iron and mercury. He worked for 30 years doing that.
He worked with Meggers at one time,
That’s exactly right. And I spent a lot of hours sitting there with a measuring microscope, putting the cross-hairs on lines, and carefully measuring everything and computing everything. I had a Millionaire computer, one of the greatest computers the world has ever seen, desk computer, which has a streetcar controller, for multiplying. It’s a lever like your arm, with the elbow on the desk, and turn this back and forth to 1. You go, 2—it goes, achoo, achoo, achug, achug! Oh, it was marvelous. It was great fun. Took a lot of hours.
One summer, you spent.
This was one summer, yes. Free. Everything was free, I mean, I think I tried, once or twice—I got carfare out of him, because it was a long way to go.
No. No. Never had a chance. No observing was being done, as I recall. I don’t think—they might have bean very rarely doing something, but, about two people were working in the whole place. They couldn’t afford—they could hardly afford to pay the light bill. We had to be very careful about the lights. It was really very, very low level. And of course, the work was exactly the work that could have been done 50 years before. There was no difference. The Millionaire was made in 1892, and the microscope was made in l892, and the plates were fine glass plates, and everything was just—
Was the Millionaire the name of this [desk calculator]?
The Millionaire was the brand name. I know, because if you look in the Encyclopedia Britannica, 1911 edition, you’ll see it illustrated as the, you know, highest accomplishment in contemporary computing art.
So this is how you occupied yourself one summer anyway, prior to ‘36. When you were approaching your senior year, you began to hear then of things in nuclear physics.
Yes. Of nuclear physics.
How did this come to pass?
I can’t really recall, but just I think it was more or less, by now, by osmosis. In the first place, I knew more about physics, and I could understand, I could appreciate that there was a history of these points and that there were things happening. Second, the influence of Stern made it clear that there was a possible connection. (It wasn’t that we hadn’t heard of the Nobel Prize before, I suppose we had. But the notion that there was a real person who had won a Nobel Prize, you know—this was different.) It was all very different, but it’s very hard to put myself back. I haven’t thought about this for thirty years. It’s very hard to put myself back in that place. And then, I think Pitt was a little more sophisticated than Tech, in some ways. I worked one summer at Pitt, again doing a standard job with Worthing, A. G. Worthing, a very well-known man. I guess I worked with the assistant of one of these. I can’t remember who it was. I think it was Worthing who came in once in a while. And I did pyrometry. I made some—I don’t remember what it was any more, but some calibrations, with his optical pyrometer, and some carefully made tungsten lamps that had blackbody holes on the filament, things of that sort. Again, as a volunteer.
This was good practical work.
It was all extracurricular, in a sense.
All extracurricular. All free. I mean, I would go around and say “I’m a student at Carnegie Tech and I’d like to get some experience in the research lab, have you got anything interesting to do?” I wouldn’t be quite that bold, but that was the…
When did you start considering going on to graduate school?
I think by the time I was a junior or senior, I had pretty clearly in mind that this was a possible thing to do. In fact, it was easier than getting a job at this time, and more attractive, so...
Did you have in mind getting some kind of fellowship?
Assistant, yes. It was indispensable.
Your grades were good enough, you had good recommendations?
My grades were good: I had good recommendations. I thought I had a good chance. I remember very clearly deciding between Harvard and Berkeley, because the assistantship at Berkeley was $50 or $80 more per year. It was a big difference. It was 20 per cent, I think. That’s why I went to Berkeley. It was nothing fancy, I didn’t...
Well, were there any other reasons? Did you consider Harvard one kind of physics place, Berkeley another kind of physics place?
No. No. I knew they were good places. I’d consulted with people who said, “Oh, yes, Harvard is a good place. Berkeley is a good place. Princeton is a good place. Cal Tech is a good place.” And I applied to all of them. I applied to all the places I could think of that were said to be good places, actually five or six places, and I was pretty sure I’d get one of them. And I actually chose. I got three or four offers, and I picked the one that had the best assistantship, and I didn’t care in the least what else happened there.
So what about the question of who was doing what kind of physics?
I hadn’t the least idea who was doing what kind of physics.
What kind of physics did you think you wanted to do?
Theoretical physics, by that time.
Ah, and this transition occurred sooner?
Yes, between the junior and senior years.
Now, theoretical physics in different periods usually has different meanings for a person. At that time, did theoretical physics mean theories of matter? Did it mean the structure of the nucleus? I’m curious to know what you thought [theory was].
Well, I think I believed that it had something to do with nuclei and the atoms and the ultimate structure of matter, but nothing more specific than that. I don’t think I was that sophisticated. I can’t remember for sure, but I don’t think so.
Did many of the people go on to graduate school, many of the people in your physics class?
In my class? Let’s see, the class had about fifteen members, twelve or fifteen members. I think about three or four went on to graduate school. About three or four went into industry, and the other three or four just drifted away and did something else. One man—I remember him very well, fellow called Prescott who was my lab partner for many years, eccentric sort of fellow, I haven’t heard of him since really—was building an organ in his home, a gigantic baroque organ with hundreds of pipes and hundreds of—all by hand from the beginning, and he was on that, a couple of years doing that.
I had a friend who did that; I thought there was only one nut in the world like that.
No, there’s more than one. (Laughter).
Then you were accepted at Berkeley, and you had a choice. You decided on Berkeley. You went there in ‘36?
In the fall of ‘36, together with another student a couple of years older than I but much more sophisticated from Pitt named Dancoff, who was a Pittsburgher, of course, and he was also accepted at Berkeley. We roomed together. Sidney Dancoff—was a strong influence.
This is the Dancoff who died a number of years ago?
Yes. That’s correct.
And what happened at Berkeley? Because I’m curious to know your reaction. Once you had decided on it...
Yes. Well, then of course I found out a little more about Berkeley, and I knew then that there was Lawrence and cyclotrons. Probably I knew that anyway in a vague way. I knew there was Robert Oppenheimer, and it was all very interesting, to see what would happen. And of course, the reality transcended the imagination. The charismatic effect of Robert Oppenheimer was very great on all his students, and there was a complete development of a coterie.
And Birge was there.
Birge was the head of the department, yes, I remember it very well. Personalities at Berkeley who interacted with students strongly were Lawrence, Birge, Lenzen, Oppenheimer and Williams—that’s about it. And these were the people who were responsible for teaching graduate courses. Their interaction—you began to appraise them individually. Birge, of course...Birge, as you know, is a man of great fastidiousness, “fussiness” is less polite and a more accurate word, so seeing him one always experienced it.
He has just completed the first section of the history of the physics department at Berkeley.
Yes—it must be a glorious thing to see.
Well—fantastic, that is all I can say.
Well, I wish I could remember. I fell into some, not exactly controversy, but I shocked Birge in some way, which I can’t recall any longer, at the departmental picnic, by some remark. And I never can recall, I can’t recall it.
Was it a question of violation of social etiquette?
No, no, it was just—it was perfectly polite and funny and appropriate and all that, but it was just so out of character that he never quite got over it. He wasn’t really—he wasn’t opposed to it. That is, when I say shocked, I literally mean that. He jumped, he was startled, he always referred to it. For twenty years afterwards, whenever I saw him he referred to it. But he didn’t—he was pleased, he smiled. It was some kind of remark about the nature of the department, but I can’t remember what it was. I wish I could. It’s too bad. Every student had to get up and say something, that was the story. At the picnic, every new graduate student, you see. And I said something, and caused a reaction. I don’t know what it was any more. And Birge never forgot that.
What did you study at Berkeley?
You studied him.
I studied the work that Robert Oppenheimer did, very hard.
Weren’t you at some disadvantage, coming from Carnegie Tech, with general physics courses, and not very close involvement in research?
You were able to keep up?
Well, nobody kept up very easily.
They moved pretty rapidly?
They moved very rapidly. Well, I still have those notebooks, somewhere in that mess. We took notes on Oppie’s very rapid lectures. Robert Oppenheimer gave himself the task of teaching all of theoretical physics to the students in two or three years. We took other courses too, but they were much less interesting and important for us. They were not bad. Lawrence had a good course, when he was there, which was not frequent. He was always away. That was my first sight of a professor who was never there. It was proverbial. Robert Wilson was in my class. A very good class. The number of distinguished physicists who were in that class is really quite large. They’ll come out as I talk. But Robert Wilson was the outstanding one, I think. And Wilson couldn’t do the problems. He didn’t want to take the time. They were very hard, onerous calculational problems. But he decided to measure—one of the problems had to do with the behavior of the cyclotron, the dees, and Wilson was working with the cyclotron. He decided to measure that, and in the course of these measurements, he not only solved that problem but became the first person to really understand the dynamics of the cyclotron, which was the work he did as a graduate student. Extremely good work. And none of us showed that flair, but we were all hard working students and didn’t...
In the theoretical courses taught by Oppenheimer, did he take into account much what was going on down the hall with the cyclotron?
He didn’t take into account much of the new work in experimental nuclear physics.
No. I mean, it was a systematic course. He began by teaching mechanics and the Lagrangian,—the Hamiltonian—the sort of things you would have today—it was not a very bad outline of what’s now done. This is the course that, the course lectures that he thought were appropriate, after Ehrenfest, and Born and so on had lectured in Gottingen and Leyden five years or ten years before.
Then the experimentalists took it too? It didn’t matter what your...
Oh, it didn’t matter what it was.
Every graduate student?
No, you had a choice, but the better graduate students took this, and they dropped off. That is, the people who were going into theory and working with Oppenheimer stayed on the longest number of courses, maybe six courses, while others took only one or only two. And then there was the standard course. At that time we had examinations, so-called preliminary examinations which were oral examinations: given by a committee of the department, and the oral examination was set for each student in each of four or five subjects—mechanics, electrodynamics, modern physics and so on. So you tended to take the course which was appropriate to that examination, mainly to learn what that professor was going to ask. For example, you had to take physical optics, which Birge taught, or you would have been through. Everybody took it but nobody learned anything. It was not very…it was a very…it was a course submerged in minutia. But you took it and you did the problems, because you had to establish a good relationship with Birge—at least a tolerable relationship with Birge. And I have no doubt the experimental people would have a different history, but those of us who wanted to do theory worked with Oppenheimer’s course, and just spent all our time in very hard work. I would say—I don’t think I exaggerate when I say that we worked 50 hours a week for Robert Oppenheimer.
When you were working for him, were you doing anything else at the same time? Or did you have just a solid dose of him?
Yes, we had regular courses, but the other courses were a third the load of Oppenheimer’s.
I see, yet you had an assistantship, so what duties were required of you on the assistantship?
Oh, three hours of laboratory a week, something like that. A section. Freshman physics section was the principal thing. I got a fellowship, I guess, in the second year. The first year I was an assistant.
Do you know the source of the fellowship?
Yes, it was the Rosenberg Fellowship.
The Rosenberg Fellowship. Was that a foundation there?
A well-to-do family in California who were very important in the fruit industry, the packing industry, and they had given money to the University to establish fellowships.
I think in many, in a number of fields. Perhaps it was a University-wide fellowship. There were several good University-wide fellowships, I applied for those and got one. I remember, I had to go and see one of the family, when I got the fellowship. It was considered polite. I met and saw Mrs. Rosenberg, thanked her, told her what I was doing. She didn’t understand, of course. Neither did I.
The reason I ask that is because it’s interesting to find out what the sources of support were for physics, and what the motivations were, and so you find new names popping up. This one may not be relevant because it’s university-wide.
I suspect it was university-wide. I had it for a couple of years, and on the strength of it I got married. I mean, it was a big increase in my income.
This was in 1938?
You’d been there a couple of years. Did you ever stick your nose into the cyclotron work?
Oh, yes. By this time…
As an observer, or did you…?
Well, I had friends. I had no particular thing, no action.
By this time, Livingston was gone.
Yes. Oh, the 36 inch was working and the 60 inch was in active construction. And it was a big laboratory, and one knew that. It was quite exciting. And the theorists were—the most important influence, I’d say, from this point of view was the Journal Club. That’s probably worth mentioning. I don’t know its origin, it was just there. It met every Monday evening at 7 o’clock for two hours, perhaps an hour and a half, and it is an institution which everybody who’s been at Berkeley since that I know of, all these elderly professors, still maintain in some form. There’s one in Cornell, I know, which Bob Wilson runs. There’s one here which I started when I got here a couple of years ago, and so on. The institution is of the following sort. Nowadays, unfortunately, it’s more limited. Then it was all of physics, but it centered on the cyclotron and nuclear work. Here we have one in astronomy. The Journal Club was distinguished from a colloquium by not having outside speakers, by not having essentially large synoptic talks, but the norm, which may be deviated from in any way—it’s usually done very informally—the norm is a 20 minute, half-hour account of some work in progress, either just published or being done by someone that you know about. And graduate students are expected to contribute those. Graduate students give the seminar, as well as senior staff members, and they alternate.
This brought together Lawrence and Oppenheimer, let’s say, in one room?
Yes, Lawrence and Oppenheimer and McMillan and so on. As I say, Lawrence was a man who was not there very much, but McMillan and Alvarez were always there. They were the hard working reliable people.
Was there much interaction within the faculty—Alvarez, McMillan, Oppenheimer?
Yes, there was.
They did communicate very regularly?
Oppenheimer was fully aware of what was going on in their work? Did they bring problems to him?
Well, you know, at one remove. My thesis, for example—I don’t know, it’s a complicated mixture. We didn’t work closely with the laboratory, as some groups of theorists do in some circumstances, where you really help design experiments and so on. We rarely did that, but there was a kind of parallelism, if there were some interesting topics, we would look into it and see what was going on and what was new. I think I must say that that relationship is also rather common nowadays. It’s not so very different. For example, I mean, I did a thesis on—one part of my thesis was on internal conversion with Dancoff, and the people there had built electron spectrographs in which they were finding these lines. It wasn’t that we were directly computing what one of their lines was, but they grew interested in this problem, and somebody came out with a paper which was quite incomplete, and so we said, “Now look, it would be a nice topic to generalize this and make it work for all cases, and then you could use it, and maybe someday you’ll be able to select it.” I remember getting a piece of zinc which had been irradiated, which was giving out these internal conversion electrons, and I just had it as a kind of a souvenir, because I liked—I was trying to calculate what was the origin of this process. But it wasn’t a very direct thing. That is, we didn’t concern ourselves only with their experiments or mainly with their experiments. We’d look at anybody’s experiments. But the general direction of work was to some extent influenced by the presence of the radiation laboratory. Though Robert Oppenheimer himself was more interested in cosmic rays at that time.
Yes, throughout this period. In the Journal Club, what was the tendency? Where were the good articles published?
Nature. Well, the usual vehicles—Nature was considered because it was up-to-date, a weekly, and…
How about the Physical Review?
Yes, “Letters” in the Physical Review particularly, and occasional papers in the Physical Review. The Physical Review and the Zeitschrift fur Physik, of course, though that was sharply down. It was older papers that we used that for. In ‘38 there was nothing in the Zeitschrift.
Yes, by that time things had changed. How about refugees or émigrés at Berkeley? Anyone there?
Of course, there was a large group, quite an international group at the Radiation Lab. I don’t recall any dominant input from those people. Segrè, I guess, came there about that time, ‘38, maybe ‘39.
Was this the period of the joint Berkeley-Stanford Colloquium? Morrison. Yes, it was exactly that period. There was Bloch, of course, at Stanford.
Yes, he was a relatively early arrival for a European.
Great. Now, where were they held? I’ve heard a lot about it but I haven’t heard specifics. I knew they were held but I didn’t know if they were held at Berkeley or at Stanford, or if they rotated. I don’t know how often. I had heard that they were very exciting things, that there were often debates between Oppenheimer and Bloch.
Yes. That’s right. That was quite typical. On issues which were mostly connected with the behavior, as I recall, the behavior of interactions at high energy, the electrodynamics of high energy. That’s the main topic, plus the problem of the divergences, the infra-red divergences, which came up very often. They were held at Berkeley and at Stanford, I don’t remember how often, but certainly they were rotated. A few times a year. (Pause in recording) Of course, the other interesting interaction was—Robert Oppenheimer was a member of the Faculty jointly at Berkeley and Cal Tech. The terms differ sharply. Berkeley then, perhaps even now, begins in late August and the year ends sometime in May. Cal Tech has a more normal schedule, late September to June sometime. So there’s always a month or a month and a half, maybe even more, at the end of the year when you can pretty much complete a Berkeley term, and then go down to Cal Tech for a sizeable part of the term, which Robert Oppenheimer always did, I think by agreement—and many of us would arrange to go down with him.
You’d go for that extra session.
Interesting. You were in a position, then, to observe differences between the two institutions.
Of course, you were following Oppenheimer.
That’s right. It wasn’t so different.
And at the same time, I guess you had the feeling of what was going on at the other institution.
Yes, we did.
And what was that like? At Cal Tech, I mean?
Well, as I say, there we got to know Lauritsen and Fowler. It wasn’t the cyclotron style, but it was a little bit like that. It was the Kellogg High Voltage Laboratory. And experimentally it represented a somewhat different point of view, but on the whole, since we were mostly working with Oppenheimer, it didn’t seem very different to us. I was very much influenced by Richard Tolman, who was there. I took his courses, in fact. I found them very stimulating. Tolman and Robert Oppenheimer were very close personal friends. Formed…a group.
Yes, Epstein was there. I don’t recall meeting him. Zwicky was there. I saw Zwicky. I don’t know these people at all well. We knew Lauritsen and Fowler, and—
Anderson was there.
Anderson we didn’t know well. The relationships really followed the social lines very much. The people Robert Oppenheimer was friendly with, and the ones the graduate students came to know were the people we heard a lot of and went to hear lectures by and so on.
Was there much difference in age in this group?
You were pretty close. It was within ten years?
Yes, certainly. Certainly within ten years.
So when you say social, it’s in the sense that you liked each other’s company, in addition…
…In addition to the intellectual exchange, the lecture or Colloquium.
That’s right. You go to the same restaurants and so on. You liked desert walks, or whatever it was. But we never, for example, saw Millikan. Great gulf. He was university president anyway. I don’t suppose he was much interested then. I remember seeing him once. I was quite impressed by seeing him—you know, red face, white hair—
And the Nobel Prize.
Yes. Well, by that time it wasn’t so glamorous. We knew plenty of Nobel Prize winners.
At Cal Tech—you knew Lauritsen and Fowler, did you probe much into the experimental work, into their own High Voltage Lab?
Yes. Yes, we sort of knew what was going on there pretty well. But I think that nobody that I know of in Berkeley actually worked in anything that was very close, did theory that was very close to the kind of work that Lauritsen and Fowler were in fact doing.
How would you characterize that sort of work that they were doing?
Well, I think it was—there were a couple of other centers of the same work—it was an effort to do rather more precise work than cyclotron work on the spectroscopy of nuclei. That was pretty much what it was, I would say.
Was this idea of energy level...
Energy level work, spectroscopy.
By this time, when you followed. Oppenheimer down there, it was already in the late ‘30’s? It was after you were married, so it was ‘39 or something?
Yes, ‘38, ‘39, ‘40 probably.
In your Journal Club, had you discussed the Bethe articles much?
Oh, yes. We studied them.
What effect did they have and how were they regarded?
They were very highly regarded and very much thought of. They were considered compendious works, where you could find the answers to most questions if you worked hard enough. Bethe was always—there were a great many jokes about Bethe, because he was always such a hard working, such a productive person. There was a joke going around that some English physicist’s wife, who typed out his papers, was asked once, since Bethe was coming, did she know who Bethe was? “Oh yes”, she said, “Bethe’s the person who writes the Physical Review.”
Very good. Did he come at all [to Berkeley] during that period?
No, I’d never met him before the war.
How about other visiting people? Weisskopf, did he come?
No. Placzek—I knew Placzek quite well. I’m trying to recall about Weisskopf. I’m uncertain. I don’t think I met Weisskopf before the war.
At Berkeley, was there any sort of a feeling in the group there that this was some sort of a Mecca for physics, some sort of a center of nuclear physics? Or is this only a historical reconstruction? I just wondered if people had this self—consciousness.
Well, I think it was clear that the Radiation Laboratory was becoming a center. Yes, it was sort of clear. The plans, the increasing size of machines, the future projections of still larger ones, the financial support which Lawrence had attracted meant that the Radiation Laboratory was going to become an increasing center of experimental work in that domain, and we felt, the theorists did, that we had a very good group too. But I don’t think we regarded it as being the center of interest from our point of view. We were just as interested in Cal Tech or Cambridge University.
What about the announcements of fission in ‘39?
I remember those very clearly, yes. Lots of discussion about it.
How did you hear about it? If you can reconstruct that, I think it would [be] helpful.
Well, I think I could, because I’ve talked about it several times since. It’s naturally the sort of thing one does try to remember. I remember very well hearing the rumors that it was being talked about in the East, and that Pegram had, or somebody, Dunning, found the ‘scope traces, at the same time that the Nature letter came through from Frisch and Meitner. That’s the week when I first remember it. I remembered McMillan reported on that paper, gave a very clear account of it.
In the Journal Club?
In the Journal Club.
And how long after the paper came out did he report on it?
I couldn’t say, but I would say not longer than a week after it appeared in California, I just couldn’t give the date, but it was very fresh. And I remember that we began talking about all the implications. It was interesting that months before that, Paul Aebersold, who was an experimenter getting his degree at the lab maybe a post-doctoral student, had developed a beta-ray spectrograph of a simple and new sort which he was using to study converted X-rays from radioactive materials. And he reported that in looking at uranium bombardment, he had found the X-rays which fitted very closely to the values for barium and lanthanum. And this was a great puzzle, because how could you possibly have barium and lanthanum? And Robert Oppenheimer said, in the Journal Club, in answer to this, he figured out, he said, “Well, I’ll bet that’s the L X-ray of element 95”, or something like that, and he calculated this on the board. And by shifting numbers a little bit, and the fact that Aebersold’s data were not all that good, it was possible to get agreement. But now of course if the L X-rays of this transuranic were so strong, then the K X-rays must have been ten times stronger. But they were not seen. The reason was that Aebersold’s spectrograph didn’t quite have that additional range. He was going to go back and some day extend that and look for it. That’s one of the famous stories of how fission was missed. But then he never did, because he had something else to do, and six months later, this was something like, between, maybe four and six months before the discovery of fission.
You mentioned about one of the famous stories. The fact that there were so many close calls on this indicates that people were working along very similar lines.
As if the discovery of fission was the next logical step, it just had to fall out of the data somehow.
No question that sooner or later it would have been found. It had to—it was found, in fact, by one of the most indirect means you can possibly think of. You know, there are at least two or three people who looked for fission in uranium under slow neutrons, looked for reactions in uranium under slow neutron bombardment, with an ionization chamber and pulse height recorder, looking at the oscilloscope trace, and when they did that, of course, they got a tremendous background from the alpha particles, because it’s very alpha active—so to get rid of that background, they almost always covered their sample with scotch tape.
Which cases are you thinking of?
Segre and Goldhaber have both done this.
Those were the two I was thinking of.
That’s right. They were very clever. And of course, this killed the fission tracks, if they’d just watched, they would have seen a very dense track occur, in the midst of all the other.
This was four or five years earlier, wasn’t it—not four or five, maybe—
Three or four years, anyway. There are many people who had almost seen it.
Now, when you say you were discussing, you know, seriously discussing the implications, what had you in mind? Did you see the energy potential?
You saw the bombs. Now, this meant that you were sufficiently conscious of the war situation.
Well, it was after Munich. I remember that much more clearly than I remember anything else I remember at Berkeley, staying up all night listening to Hitler on the radio. Everybody remembers that who lived during that time, practically. You know, it was fantastically crucial, and the air of drama and suspense and terror was very great. The difference in time, 8 hours, between California and Europe meant that whenever something happened in Europe, we were always up in the middle of the night listening to it.
You mean in general, in political events.
Then when this came, when the announcement of fission came, it was against this background.
It was against the background of imminent war. And so the fact that energy was very great here, and that probably neutrons came off, was quite clear and implied a chain reaction, and everyone said, something very serious is going to happen.
Did you think of the next step, of the idea of actually organizing something on it, or that government should be involved?
This is generally attributed…
We assumed that somebody would.
This is generally attributed to physicists trained in Europe (in the popular sense, it’s attributed to them) who were more amenable to government involvements in physics, and therefore Szilard and others made this proposal, and saw the definite link with the government. But I don’t know if that story holds up, and that’s why I ask.
I don’t know either. I think it is attributable to Szilard, but I don’t think it’s so much his European training as his own particular contribution. Ever since ‘33, he had anticipated this. You know, he bought that gram of radium. He cut all his savings into it, and travelled with it. You know the story of St. Bartholomew’s Hospital, where he did the Szilard-Chalmers reactions—all those things. He was obsessed with this idea, and he was determined to get someone to take it on, and I think it was sort of faintly felt that it would be people like that. I remember drawing on the board—several of us worked half a day—drawing a diagram of a bomb on the board, in Oppie’s office, the room we all used as a seminar room, you know, on the second floor of Le Conte Hall. That was either early in 1939, January or February, or January 1940, I don’t know which. I think it was ‘39, but maybe it was a whole year later, I can’t tell. But in any case, you know, it had heavy water, and it had things moving together, and it had all the machinery, not very sensible, but sort of—it would make a good science fiction equivalent to the Bomb. And then I sat down and wrote an article, which I sent off to the Saturday Evening Post, hoping to make some money, describing this whole thing.
Was this published?
It was never published, it was rejected.
Oh, rejected—not censored, but rejected.
I don’t know. It was rejected, yes.
The self-imposed censorship wasn’t yet in force then?
Oh, no. No.
There were still things being published in 1940. Turner wrote his review. Did you discuss his Review article on fission? He had an article in Reviews of Modern Physics in January, 1940.
Yes. We would have seen that, probably, in early 1940. Yes. Well, I guess at that time I was just—I was no longer a full time student at Berkeley. In February of ‘40 I went—am I right about that? No, I guess I wasn’t, I just remember—I remember reading the article. I don’t remember the Journal Club discussion. I left Berkeley, as a full time student, in the fall of ‘40.
I have here—I don’t know why the date is so precise—that you got your Ph.D. on April 23, 1940.
Oh, very good. 1940? Very good.
Yes. Now, I don’t know what the date means, whether it was the awarding of the degree…
It was the date of—it’s the formal date. In Berkeley there was a little printed form, with your name and the examiners and so on. Yes, but then I stayed on at Berkeley for half a year.
And then in the fall you went to San Francisco State?
In the fall I went to San Francisco State, that’s right. I was still at Berkeley, but I was sort of employed by San Francisco State, but trying to do some work at Berkeley.
What had you in mind for the future?
I was trying to get a job on a university faculty, and was having a hard time doing that.
Why? A hard time in what sense? Was it the times—?
The dissertation itself is broken into three problems in atomic electrodynamics. One was “Internal Conversion of Gamma Rays of Arbitrary Multiple Order.”
Another was “Internal Scattering of Gamma Rays”, and then the third was “Energy Fluctuations in the Electromagnetic Field”. How long had you been working on this? How did this idea develop of taking the three problems and putting them together?
Well, I think that it was just that we were working away. One of those was with Dancoff. One of those was with Cooper and one of those was my own. It was by myself. We had just been working away doing those things that were interesting, and we got progress and it was substantial, so we published them. And then Oppenheimer had the idea, a very sensible idea, not to write another thesis, which was just a tedious task—to sit down and write a thesis incorporating all these or any one of these papers. He said, “Why don’t we just take the published papers?” So I never wrote a thesis, actually, in that sense. I just took the three published papers and bound them together and presented it. There was nothing against that.
Were they published in Physical Review, do you remember?
They were I think, all published in Physical Review, yes.
Now, then you stayed at San Francisco State for—until sometime in 1941?
And after that you connected with the University of Illinois.
By that time had it become apparent the way physics would go, as far as the developing war situation was concerned, and the implications of fission—you were aware probably, that work was proceeding on fission? Or maybe you weren’t?
I wasn’t particularly. No, I don’t think so I think if anybody had asked me, I would have said very probably, “Somebody is doing it, but just who, I don’t know.”
But you didn’t see the whole physics community involved in it?
It didn’t affect your career?
No, it didn’t seem remarkable at that time. Not until Pearl Harbor. But, of course, as soon as the Americans were directly involved in the war—especially the West Coast, where you didn’t have the feeling of the war being as close as was the case in Massachusetts.
Until Pearl Harbor.
Until Pearl Harbor.
But by that time you were not on the West Coast?
Yes, but I say, by Pearl Harbor it was perfectly clear that the United States was at war. I’d been sort of hoping for some time that the United States would go to war, but it finally did so. And then it was clear that physicists had a lot to do. Then in Illinois, I had begun working on neutrons with Goldhaber, just in a purely academic way. But then when the war broke out, quite a few people left for the Radiation Laboratory. After all Loomis himself, the head of the department, was there already, working for the Radiation Laboratory. That was how I got a job actually. There was a vacancy in Illinois, because somebody went off into the war effort Dancoff, I think.
You and Dancoff sort of followed each other?
That’s right, yes. Then what happened was that in that year, Serber also was at Illinois, you see, and Serber was Robert Oppenheimer’s closest associate for some years when I was at Berkeley, and so we were all, we were very good friends. So—I mean Serber was the person who graded my papers when I was a student. So Serber and Dancoff being there, and there being a vacancy, it was pretty clear that I was going to get the job, and I got a job as an instructor there. I was very happy about that, and went off. The first term, as I got into teaching, I got involved in doing some neutron research. I didn’t know a thing about neutrons, hardly knew they existed. I remember that. I remember feeling how foolish I was to have done all this work and not know anything about neutrons. They were such an interesting specialized subject. I began learning them from Fermi’s papers, and trying to read some Italian, things like that. And it turned out to be very useful later on. Then the war broke out, and I remember, even within a week or two, as I recall it, with great speed Kerst...
Donald Kerst, who had, with Serber—well, Serber doing some theory in support of him, Kerst’s ideas of ingenious design, had just developed the betatron. It was clear the betatron would be a very useful radiographic device, for large sections of steel. And so I stopped doing whatever I was doing, I kept teaching, but I did research with Kerst’s little group of a few people, and I tried to work out—and I believe we were the first people to work out, in fact—what would happen to radiography above the critical energy in lead. That means 10, 20 MeV in lead, in steel, heavy elements. This was quite nice, sort of an application, because there was pair production, and the cosmic-ray cascade theory, all that for the first time being applied sort of in the industrial domain, not just to see how it worked. And that was quite interesting, and we thought it was quite helpful. As a matter of fact, I think we published a paper on that.
Kerst and you?
No, I don’t think it was Kerst. It was somebody else, I can’t remember who it was. The paper appeared in Radiology in those early years, but I’ve forgotten. It was actually to do with radiotherapy, rather. Radiography was sort of quiet, but radiotherapy was closely related. So we could really publish [in a medical journal].
Just to take off on that point, part of the tradition at Berkeley and at Cal Tech was the tie-in of the work there with medical therapy.
Yes, that’s quite right.
That shows up in the records of the period.
So was anyone there in physics actually very much involved in that, or was it just a way of paying the bills? By this, I mean, intellectually involved.
There were people, but I don’t know, I couldn’t tell you who they were. We knew a man…In fact, the first husband of Mrs. Robert Oppenheimer was a rather well-known young radiologist who got involved, I think, on this side. It’s a rather complicated story. I myself was interested in it, not in a deep, not in a serious way, but perhaps I would have gone to two or three lectures by some radiologist in the course of my career.
That’s a real interesting blend there, of…
That is an interesting point, that’s quite true, I hadn’t thought of that, there was always some connection with radiotherapy. Charlie Lauritsen, of course, had begun as a hospital radiologist.
He was an electrical engineer or something, I thought?
Well, but I think the way he got into physics was, he designed X-ray equipment for hospitals or something of this sort.
Well, I know that the bills at Cal Tech were paid by a medical group, and Milliken spent a good deal of his time setting up medical boards in order to pay the bills for physics.
Well, you see, of course, I think both elements play a role. Partly it’s a fake. And partly it’s real. How to tease them out, I wouldn’t like to say. That is, partly it’s a subterfuge. It’s taking advantage of people’s desire to have quick cures, by promising them that physics has something to say to that. That’s not entirely false, because it does have something to say. At the same time, there were always a few persons who were cut out for—for example, John Lawrence came to Berkeley to begin isotope and radiological work, under Ernest Lawrence, in this time, and they built that big new building in Berkeley, the Radiation Lab’s building, for biology—oh, perhaps in 1940. I remember it going up.
There was a similar thing at Cal Tech.
I think part of it was that the expectations came from the medical people, and all the physicists ever offered, from the material I saw, was “We’ve got the skill to build this machine, and if you let us have it for part of the time…”
“We will be happy to make it work and see what it does”—yes, that’s right.
I don’t think there was any—I think there’s more gimmick—
—today, than there was then.
Yes, I think that’s quite true. It is true that we did this same thing in Berkeley—and then, of course, the whole situation during ‘42 (I was still at Urbana, Illinois)—the situation worsened. That is to say, the United States was heavily mobilized. Physicists were drained out, everywhere—they disappeared, we knew they were going to strange places. We knew very well that something was going on in Chicago in fission. And a lot was going on in Boston about microwaves. That’s what we knew. And then in December, ‘42, Bob Christy, who’d been in my class in Berkeley—another student of Robert Oppenheimer’s—was working on the Metallurgical Laboratory project, in Chicago. I think he had probably already made commitments to go to Los Alamos, which was just being formed then. It was formed actually in the early months of ‘43, and Christy asked me to come to Chicago, essentially to replace him, which I did, to the Metallurgical Laboratory. I arrived there the day the chain reaction was first carried through.
Oh, you arrived there then?
Yes. I wasn’t at that event, but I was just in the laboratory that day, so people were rather preoccupied. I noticed that.
I’d like to get to that in detail, but let me ask you something else about the betatron at Illinois. This was a result, in theory this was known many years before—in some form or other, in the ‘20’s—but the theoretical…
The so-called betatron condition was known by then. Wideroe had suggested it. But to make it really work required a lot of insight and ingenuity.
Did Breit and Tuve play any role in the theory on this?
Not that I know of. I wouldn’t say they didn’t, but not that I know of.
I just wondered if their names came up on campus. Whether they did it or not is another story.
I just don’t know.
And Kerst and Serber, and then—you mentioned one application. What else did they use it for? Did they use it for nuclear physics research?
Oh, yes. I think in wartime they were interested in it for radiographic and radiologic uses. You know, at Los Alamos it was then used for high speed radiography of explosives, a couple of years later.
But what I’m trying to establish here is, when did the transition occur, when people stopped doing the physics of their instincts and started doing things that they knew had an immediate and pressing...?
Well, many people, as I say, were called off to these projects, which were secret, in the years 1940-41. And they were certainly people who had stopped. That’s why there were holes in all the faculties. That’s why I got a job, back in this business. But for me, for the working faculties at a certain time, T, the whole thing changed at Pearl Harbor. Then it was quite clear. Everyone felt that the United States was involved and much more ought to be done, and I suppose the OSRD had begun to organize the thing better in no time at all. We felt we were part of the real project. We had people.
So you just put other problems on the shelf.
That’s right. Now, I was still selective. That is to say, somebody else would be sitting in my office at the next desk might well have not been doing it at all. He might have been doing exactly the same thing he was doing before. He wasn’t yet—it was just the business of, there was a spreading personal involvement. But there’s no question, if you were to plot it, I’m sure there’d be a slow rise and then a big peaking at Pearl harbor, then a plateau.
I think it also depended on where you were professionally. If you’re just winding up your dissertation, you don’t want too many things to get in the way of it.
Yes, of course.
But if you were beyond it, looking around for new fields of inquiry, then you’d be tempted...
That’s why I say, it was always a personal negotiation with every individual, would he or would he not do this job?
Yes. Now, is there anything else specifically?
Of course, we were also—I must say, it would be unfair not to say that I was very anxious to do something about the war. I felt very personally involved and emotionally concerned about the nature of the war, and I didn’t want to be not doing something while other people were doing a lot. So I would have done anything to get into war work.
You had this feeling at Illinois. Is there anything else, before we get to Chicago, about the situation at Illinois that you think might be of interest, as an indicator of the state of nuclear physics research? For example, the comparison between Illinois and Berkeley?
Well, I must say it was very favorable. Illinois was a strong place. I remember being very much impressed with the great range of knowledge which Goldhaber displayed, on all parts of nuclear physics.
Experimental and theoretical?
He was a very learned person. He really knew everything extremely well.
Was he the main, the strongest person there in that group? By that I don’t mean on any ranking scale, but as far as a dominant personality goes?
I think so. I would like to see a list before I’d be sure. At least he was the one who meant most for me. Maybe he wasn’t for everybody—but I felt so. Yes, he seemed altogether the best person. He was thoughtful and influential, he was full of ideas and so on.
By this time you had gotten over your initial reaction to a real live physicist from Europe?
Oh, yes. I became much more sophisticated between 1936 and 1941.
You hadn’t been to Europe, though?
Oh, no. No.
Was there any special thing about the reaction of Americans trained in this country, coming in contact with this group of European physicists? Maybe at Los Alamos it’s fair to ask that question, because there was real interaction with a large group.
But I was just curious, you know, in a particular situation, either at Berkeley or at Illinois, were you conscious that there was a difference in style? Or by that time had certain Americans become very sophisticated in their approach?
Yes, we thought so.
So he was just a colleague, in a sense.
Yes. Well, of course, we knew, say, Heisenberg. I was quite impressed when Heisenberg came to Berkeley. Well, why should I talk about Heisenberg? The most impressive visit was of course that of Bohr. Bohr came to Berkeley and gave splendid lectures, on which I took careful notes. I still have them somewhere, no doubt—God knows where they are.
Did you save them?
Yes, you’ll never find them. But they were splendid, deep, not very easy to understand. Bohr spent a whole year there, as far as I recall. He gave a series of popular lectures, philosophical lectures. Sat in the seminar. Bohr was very impressive. I suppose Bohr was the greatest person that I’d ever met—you know, the biggest, the most prodigious reputation, had done the most at that time. And he lived up to all of that. Berkeley wasn’t...
Did you know him in any sense personally, in this group at Berkeley?
I knew him quite well at Los Alamos, and I suppose I knew him enough to say hello, and he knew my name or something, because we had a small seminar at Berkeley which he came to very often. That must be the basis for how I started to get—But I can’t recall that. It’s only by logic that I—I don’t recall any relationships, though I do in the wartime, and can tell lots of stories about Bohr, we spent a lot of time together.
You mention that you got to Chicago aid were in the lab on the day—I guess December 2—
December 2, 1942. The one day we all know.
This was 25 years ago. What was the reaction? First of all, you were a new arrival, so were you aware of what was going on?
Oh, I was not—I don’t know what happened that day. No one told me.
Not that day, except that it was your first day—
Well, I knew. No. I misled you. I didn’t join the project until the first of January, but I went there to be recruited, to be hired, on December 2nd. But having been hired, I was in no position to know what was going on. They didn’t tell me, so I was just around, during this day, when something suppressed was going on, of great excitement. I could see that. People were pretty preoccupied. But there I was, sort of an outsider, and I guessed that something important had gone on, but what it was, I didn’t know.
Who did you talk with there?
Wigner, Christy, and I think Bacher, but I’m not sure. Those are the persons. I know, Wigner and Christy for sure. Christy was the one who explained the project to me. He was the one who was, so to speak, soliciting my hiring. Tried to recruit me. And I think he did so—I haven’t asked him, but looking back I now see—because they were forming Los Alamos at that time, and the people had already agreed to go, so he knew there would be a big drop at the people in Chicago, and they needed—in fact they had to grow, so they needed to get everybody they could. And Christy, we were old friends and he knew that I would be a reasonable person. It would only be fair to say—I am not anxious to talk about all these matters—but you realize that Robert Oppenheimer and most of his students were in very bad odor with the government, because of being extremely left wing, and I myself never believed I would work on a classified project. Therefore I was most reluctant to get involved in one of these things.
You had the desire, and yet there was this frustration, in a sense, not knowing whether you would be, not wanting to get into a situation that—
Sure, that’s right, that would be impossible and frustrating. That’s why I very much liked the Kerst thing. It was quite an informal affair, not particularly secret nobody cared about, you know, keeping radiology secret from the Germans. And yet on the other end it was quite useful, clearly, so it was a very nice thing to work on, you see, doing something worthwhile with special expertise, and yet it didn’t involve too much of the red tape, and so it was quite—I was very concerned that it would be hard to get into a secret project. But of course, Christy knew this. Christy was sort of a more sober person, of Canadian background, conservative in thought, a very friendly person, and he knew the whole situation very well, I didn’t realize—I learned then immediately, in fact [that] Robert Oppenheimer was organizing the most secret project of all. So then I knew that the whole situation had changed, which was due to General Groves. It has this whole history, it’s now tied up in—Well, as soon as I learned that—I remember having dinner with Oppie. Oppie wouldn’t tell me what he was doing, but there was somebody else he was recruiting, and so he was willing to pass photographs around, to show what the place was like.
This was in Chicago.
When you came to Chicago, you had already joined this staff.
This can get to be a completely separate story, and I do think that someday it should be. I was talking with Weisskopf and he made the general point that nobody has ever really explored properly the whole Los Alamos story, in terms of the social relationships environment. But for our purposes, I think, we have to look at it—in only a couple of senses—the general effect of this on the development of nuclear physics, and that leads to some of the general questions we can get to later. Was it a retarding influence? Was it just a sort of putting things on the shelf? Or in fact did the end result lead to great acceleration for various reasons—research support, new technology, whatever? These are the questions that we want to explore about it. And also the social effect of bringing people together, and then dividing up the pie again in a little different way after the war, and having people go to different places, which did have a very important effect on physics. But I’m at a loss right now to see just how we can—well, let’s follow you some more. Yes, let’s do this. You stayed at Chicago until ‘44.
Yes, until the middle of ‘44.
And you were completely involved in the war work?
This was a full-time thing?
Then you went to Los Alamos some time in ‘44. When was this?
Well, in July of ‘44, or August, perhaps. This was a time of the general increase in the Los Alamos Laboratory because of the crisis about the implosion, about the plutonium and the necessity of developing implosion, which made the job look much carder and much longer. At the same time, the work in the Metallurgical Laboratory was declining, since the production piles were already started up, and therefore it was natural to chase the personnel from Chicago to Los Alamos.
So this transfer was made. I’d like to know your reaction to the environment at Los Alamos. Did you meet a lot of new people? In other words, did your physics community, did it really change?
Yes, I think so—especially the Europeans, whom I had not met, particularly the English. I’d met a lot of émigrés—I knew them much better than the English. (Pause In Recording) I’d met Fermi. I worked for Fermi in Chicago, before he went to Los Alamos.
But then you came in contact with a lot of people of your own age, or even younger then, from the East that you might not have been in contact with before.
That’s true. There were some I met at Chicago. For example, the whole Columbia group I knew at Chicago, the first time, Herbert Anderson.
Some of the Princeton people, Feynman…
Feynman, I met Feynman in Chicago.
Oh, I didn’t know he was in Chicago.
Well, he just—he wasn’t for long. He just passed through Chicago, from somewhere to somewhere. I remember being much impressed by Feynman the first time I saw him.
In what way?
He had a great reputation. He was already heralded as this very clever fellow from Princeton who knew everything. And he did know everything, you know. He did solve some problem for us, just like that.
Yes, I think he told the story of that to me—I can vaguely remember. He just happened to be there at a particular time.
Yes, that’s right.
And he felt it did contribute to his reputation.
It certainly did.
I’ve forgotten the circumstances of it. Well, how much physics was discussed, in terms of trying to develop the theory? There are various assessments on the role of the whole Los Alamos project, in regard to the development of theories of the nucleus. Were there any contributions made during that period?
Well, I would say, not very much. I mean, from my point of view, no. I had very little to do with nuclei.
You were a group leader of what group?
The critical assemblies group. We were chain reaction specialists.
If some change did come, it might have come from a theoretical group.
Weisskopf’s group or something like that.
Yes, though I don’t know so, but possibly—
No, in other words, I know that you’d look for it in certain areas more than others.
A lot of diffusion and transport theory. That’s the main thing. But that’s easy—that’s a useful subject, but it’s not the main line of things. Relatively little came from nuclear structure. On the other hand, the techniques developed were very powerful, and the main techniques meant spending a lot of money. That was really very powerful.
I’d like to examine that. You mean it gave you a new sense of knowing how to deal with big sums?
Yes, and planning projects on a scale quite unprecedented beforehand, and only faintly dreamed of by Ernest Lawrence. But doing war work, through millions of dollars—spent millions of dollars for, to gain an end—that was unprecedented.
Didn’t this imply a certain change of how one does physics?
And did people begin to think about this in terms of their personal interests, about what they wanted to do?
Yes, I think that’s quite true. On the one hand, we realized that a scale change had occurred, that a first class place would have a very difficult time without spending millions of dollars a year, whereas before certainly 50 or 150 thousand would be plenty for a first class place, and at the same time it would require large numbers of persons, teamwork and so on, and this all looked troublesome—I think that was fairly generally seen.
And at Los Alamos, before the end of the war?
Was there much active discussion, either formal or informal, on the postwar period, on what you’d do? What’s on the agenda for physics?
No. The place was obsessed by bombs, and probably quite correctly, and during, before August, before July of ‘45, when the first test was made, the talk was almost entirely about the bomb, and whether it would work and what it would mean. Then afterwards there was a great involvement in international politics, and how to handle the bomb, the first year, and I think the physics discussion didn’t enter too much until we got back out of Los Alamos, and onto university campuses, dealing with all those problems. For example, how should the government be supporting research? What about the formation of the Office of Naval Research, the National Science Foundation, and those things? Those were issues which began to…
The various bills, McMahon, May, Johnson and so forth.
That’s right. That’s right. And of course the new political appeal of the scientist.
But at the same time, there was this consciousness of the scale that peacetime physics could be done on. Was there any talk of what problems one would tackle, with all this? I’m thinking of the OPA days, and talk of pent-up buying power. In physics, there was a pent-up demand, I’m sure.
Sure. It was quite clear. High energy was guaranteed. In fact, this was where the—before the periodization of a subject, it’s very hard to see, but I suppose it does happen just at that time. It’s quite clear that after the war hundreds of MeVs will be available, and one will have to see what happens then. Which is not—otherwise it was only cosmic rays, and sort of passing. The cosmic rays alone were the high energy field, and now people said that machines are ging to make artificial cosmic rays of some sort.
But Kerst I think got 300 MeV.
Not before the war—
No? I thought he got—
Oh. The figure is there in my mind. He must have achieved it later, ultimately.
Yes, ultimately, yes.
Yeah, that makes sense.
The synchrotron was developed of course at Los Alamos. I remember McMillan inventing it. I remember the day or two afterwards.
This had nothing to do with the work there.
That was after the close of the war.
I see, after ‘45. You stayed on a while, and many others did…
For a year.
Until ‘46. This must have been a period of job negotiating, job swapping and so forth?
Yes, great re-assessment of the world and so forth.
And how did the Cornell position come about?
Well, Bethe—Bethe had of course been at Cornell, Bethe and Bacher. I worked for Bacher. I worked for both of them quite intimately at Los Alamos, first for Bethe and then for Bacher, so I knew Bethe and he knew me quite well. At that time everybody who was setting up a new laboratory was going around looking for people they knew during the war as good people. And of course, I was also persuaded—Lawrence and Alvarez tried to persuade me to go to Berkeley. But I just made the decision not to go to Berkeley but to go to Cornell instead. Mostly on the grounds that Berkeley was dominated by Lawrence, and that the whole style of work there was not really what I would really like to do.
Because of the scale?
No, just because of the personalities.
The dictator. The autocracy. And the political climate.
What did you expect though at Cornell? I’m sure one of the attractions was Bethe himself.
You knew he was going there already?
Well, certainly. It was all done that way, by joint agreement.
Did you follow him? He left in early ‘46, it seems—
Feynman left earlier, yes. I left much later.
But it was ‘46 he left there?
He left Los Alamos in February. He taught the February ‘46 term at Cornell, Feynman did. Probably also Bethe. I’m not sure of Bethe.
Maybe he left before Bethe, I’m not sure.
I see. In any case, he was certainly there February, ‘46.
And you arrived in the fall?
September of ‘46, right.
What happened then at Cornell? Here you have a group of Bethe, Bacher—and Wilson was there at the end of the war?
No, we hired Wilson, he’d gone to Harvard—
He had been at Cornell before?
No, he had never been there. He was at Harvard. He’d come from Princeton to Los Alamos, and then he went back to—he was taken on at Harvard.
I see. But you went there, and Feynman, who was a new arrival, and Bethe was there and Bacher. I can’t think of others, but evidently...
Quite a few...
And all of them prepared to work on the new physics.
In Feynman’s case, it worked out to be electrodynamics, but still it was the hot fields. How did these things jell at Cornell, as compared to the other institutions? By this I mean, was there something peculiarly postwar about what was done there, something that was different in style?
Well, it was completely different from the prewar situation, that’s the best way to—have you ever been at Cornell? Yes, you have. Well, again, it’s an order of magnitude change, in number of students, number of faculty, liveliness and so on. Cornell was quite a lively place, because it had always been a leading place in American physics, in spite of its isolation. Started the Physical Review and so on. It had Bethe. But the whole scale was different. This was the guarantee the university had to make, to get people like Bethe back after the war. They guaranteed they would raise more money, raise the budget, push for a million dollars a year. And then what happened was that Bacher become Atomic Energy Commissioner, and Bacher was sort of an administrative boss, and since he did this, they had to get someone else, and at the same time we’d become committed to building a big machine, and we knew there was just one person suitable for that, and that was Robert Wilson. So we persuaded Wilson to come to Cornell, to leave Harvard, which he then did. Much to the dismay of Harvard.
What was the source of support then for research at Cornell after the war?
It was the Office of Naval Research, primarily.
Do you have any feeling on what the justification was from the proposer’s point of view? Now did you justify the need for support? What arguments were advanced?
Oh, the ONR had established a very clear policy. After the war, one of its great accomplishments was to say that the Office of Naval Research was interested in supporting scientific development for its own sake in the field, because it brings us—Their justification had to be made to the Navy Department: It brings them in contact with new people, and people in new fields, and trains the personnel of the future: therefore they’re going to spend a certain number of millions of dollars in supporting physics. I think they had to do so because of the Army’s strong involvement in the atomic bomb, and from the point of view of the Navy Department, that was ruinous. Here the Army had made the atomic bomb, what had the Navy done? So it was very easy for the ONR to get departmental support for a policy of supporting non-secret, non-classified, non-naval connected research. That was the way it was said right from the beginning. It had nothing to do with the Navy, except that the strength of research development has fallout, as we now say. You know, it’s going to do something eventually. Just as public health—And I remember writing an article in the Bulletin attacking this principle very strongly. I was very worried about it, because it seemed like an unsafe principle. I couldn’t exactly oppose it, but—That is to say, if the Navy had said, “We’re interested in public health”, they could have made exactly the same arguments. Let’s have an anti-tuberculosis campaign. I suppose even that I can easily imagine the Navy Department doing that, if the right things came up, to spend a small part of their money on anti-tuberculosis, on the grounds that that would help them to be able to recruit people. It was no different, and I think it was consciously so.
Was there any special field that they desired to support more than another, or was it just a question that some fields took more money?
The latter. Some fields took more money.
And that field would be nuclear physics.
That’s clear. It was obviously attractive to everyone. They, for example, were very important supporting psychology and mathematics at Cornell.
You think Cornell was typical in its grant-getting abilities?
No, I think Cornell was les connected with the AEC than many places.
Because of taste? Was this their own decision?
Yes, I think it’s just the way things started, it had to do with timing more than anything else. Also, MIT for example, and the whole Boston area was affected by the existence of the Radiation laboratory and the connections it made with government. Cornell had not gotten any of those. Its connection with Los Alamos—it was so remote that it wouldn’t really—
There was no wartime research on the campus at Cornell, really? (Crosstalk) Nothing basic? But there was at Harvard with the underwater Sound Lab, and there was at MIT with the Radiation Lab. (Crosstalk).
That’s right, and there was at Berkeley and Columbia also had it. So I think that’s why Cornell and ONR got together so well, because there was no existing connection, and ONR had no existing clientele, and these two needs found each other.
That’s an interesting point that hasn’t emerged before, that the patterns at a particular university may very well have been established by what had happened there during the war. The thing that was different about World War II, and World War I, in the involvement of science, was that a conscious decision was made wherever possible, except for the Manhattan Project, to keep science on the campus, not to bring everyone to Washington.
This was the conscious decision of ORSD. I think it’s time to get some sweeping overviews of periodization.
And I think in the course of that we can return to specifics. I think that the closer we get to the present on personal specifics, the more it blends into you as you are today, in a sense, so it’s harder for me to pick out specific questions. But if you were to look at the overall development of nuclear physics, as a defined field, in other words a man saying “My specialty is nuclear physics”, could you put a starting date on it? And then how did you see this field subdividing, if you want to put it that way, as it went on in time?
Well, let me say something else, because I thought about this a little last night, when I knew you were coming. I feel that there are two strands, which are clearly separated but are not always seen to be separated, and sometimes therefore there’s a confusion, I don’t mean just looking at it but also within the minds of the people who are doing it, but I think if they were asked they would have to say there are two strands. One is the strand which I would call the ultimate structure of matter, the ultimate analysis of matter, and the other strand is the physics of nuclei. These are not the same thing at all, but at a given time they were the same thing, and that time is transient. And that’s what I think makes one of the troubles. Within nuclear physics, you can see two things, two big issues, certainly in the pre-war period. One is the nuclear forces, and the other is the dynamics and the statics of nuclei. These are clearly related, but not at all the same thing. The most theoretical, the most philosophical part of it is clearly the ultimate structure problem, which means nuclear forces.
I see the distinction, and I think it explains the careers of many people that we know follow certain trends, because it took them closer to understanding, they hoped, of the ultimate structure, the ultimate nature of matter.
So if it was quantum mechanics at one time, and then nuclear physics the next time, and then cosmic rays—
—And then quantum electrodynamics, and now elementary particles… Morrison; That’s right. It’s the same thing.
And you can trace that group, and you can watch their tracks.
Yes, and that I think is a very useful thing to observe. And in nuclear physics, what you call nuclear physics, the role of the deuteron problem and the precision work with the Van de Graff generators, Herb and Tuve and a number of people of this sort, represents quite a different school from the cyclotron and the nuclear reactions and fission and stellar energy, which is quite a different collection of phenomena.
Can they be studied independently, bringing it down historically?
Well, I think probably not. The interaction is very strong. But I think if one doesn’t isolate these two things, and looks at each one to see how much of a mixture each event is, one is in some trouble. And I think that’s the point. I must say, I’m not one of those people who do ultimate structure of matter. I’m always interested more or less in phenomena. But a theoretical physicist has to have the point of view which encompasses both of these things, because the theorist, I think, probably wants to believe most of all the unity of the theory and of the method. There can’t be anything left out. If anything’s left out, that represents a challenge. Therefore, you worry on the one hand, you try to get to these more and more elementary, and analyzed events like the deuteron problem where there are just two particles. You should be able to understand that completely. At the same time, does that mean that you can understand all the phenomena that go on in the big nuclei, or internal conversion or something of the sort? Well, as long as you don’t have some line to do that, you’re worried. You don’t know, is there something new about 3 that isn’t present about 2? This might be fundamentally quite important. So you always keep some eye going toward interpreting all the complex phenomena that arise out of heavy nuclei. Even though they probably don’t have any close bearing on the details. They represent sort of another subject. We would nowadays, sophisticated people, say “These are many-body problems” you see. There’s a theory of doing many-body quantum mechanics. You put in any kind of particles and any kind of forces, and they’ll tell you want you get. They’ll tell you about solids. They’ll tell you about nuclei… See, that’s one domain—to infer, to deduce by logical means from fundamental premises, mechanical premises, what a complicated system will do. That’s one. And the other is, what is the right description, the most fundamental description, of the ultimate structure of that you’re looking at. And these are two quite distinct things. And nuclear physics sort of had both for a moment, but no longer has, I would say. Not much. It’s high-energy physics now.
Can you try to trace this attraction and intertwining and separation over a period of time? It would be very helpful, even if you’re wrong.
Well, I’m probably wrong.
Just as a model, you know, to see how this stands up with what else we’re going to be getting from a lot of different sources. I think it’s a very useful way of putting it.
Yes, I think it is a helpful way of putting it. Well, you can see these things very clearly. Consider, say, such a thing as a shell structure. The shell structure nuclei was pointed out by Elsasser in the early 30’s, and quite ignored, because every attention was paid, mostly because of Bohr’s influence, on the other aspect of the nucleus, which is the strong interaction of many particles and nuclear reactions and so forth, and on that side, shell structure was quite isolated, lost, until 1948 or something like that. Ten or fifteen years of neglect. It seems very curious. And in those days there was no very powerful theory of the many-body problem, which nowadays people tend to have, and there’s much greater clarification of how nuclear structure turns out. But the idea of nuclear forces, first at very low energy, using the deuteron, and then at higher and higher energy, to try to straighten them out and see what their forms are, was a theme that goes way back, certainly to 1930 or ‘32, to Heisenberg’s early papers. And that theme was never lost sight of. One always had it. One had those, so to speak, what people call phenomenological fits to the forces, like the Wigner force, the Majorana force, the Serber force, the Butler force, all these mixtures named by people. Ingenious mathematical tricks, more or less ingenious, to represent some feature of the forces. And then the other domain, you see, began with Yukawa. Yukawa comes through in 1935 with an explanation, evidently, broadly speaking, right, that the nuclear forces are an analogue to the electrodynamics, which was the only thing understood very well, and there must be an analogue to the photons, and those photons are mesons, those new photons are mesons. So then you look at cosmic rays—are there real mesons? And there seem to be real mesons. Of course, it is a great puzzle, because there are two kinds. The kind you see are the kind that are not important. And that’s the pre-war situation, clearly. There are these three strands. Well, then there is one more strand, which is worthwhile putting out—quantum electrodynamics, which is the development from 1928 to ‘32 of the group of Gottingen, has now been applied brilliantly by many people. And it works beautifully. It tells you about pair production, it tells you about all those things, it tells you about cosmic ray cascades. But at the very highest energies, one doesn’t know if it’s right or wrong, at energies of 137 MC2 it was usually thought. It turns out to be a bad misunderstanding, but that was the pre-war point of view. So that strand is there, too. Here is the one theoretical method we have, the method of field theory, electrodynamics is that right? So you test it at higher and higher energies and apparently it breaks down. This is very worrisome. Can you apply it? Second, can you then generalize this to discuss the forces between nuclei, which we don’t know very well but are trying to work out by phenomenological means. But if you do work them out, can you describe them by theory? Third, if both of these things are right, can you then put these together and get the complicated phenomena of real nuclei by working some fancy dynamics of many-body problems on the forces and the particles presented to you by these other things? And those three issues are all together, and usually the same people are involved in them, at one level or another.
Roughly speaking, simultaneously. I think so. Now, if you look at Bethe’s compendium, for example, which is a very good thing for ‘38, he does discuss nuclear forces. He does discuss it on a two-body level, and then he’ll discuss neutron physics, and then he’ll go on and discuss physics of nuclei and so on. And the whole thing is there. He does not discuss any meson theory. And even when he wrote the little textbook after the war—which is probably an even better [account]; that’s the pre-war—postwar guide, if you take Bethe’s two works—even then, he does a little bit, but very little, about meson physics, not very good, and even when we wrote the second edition of it, which I did…
‘53, or ‘56, something like that. Even then we didn’t do very much on masons. It still isn’t very good. Now, of course, one could do better. The one meson approximation works for the long range forces.
Well, let me ask if this group…
Yes, since ‘56, I would say, all the people who were involved in this other business are not following nuclear physics any more. The ultimate structure people are not in nuclear physics… Nuclear physics has a very specialized attraction, first, to people interested in the phenomena and working out the level structure, and then applying this to many-body problems. But the notion that some deeply fundamental thing is going to arise out of nuclear physics itself is mostly not present.
People seem to regard this as, not a dead field, but one that doesn’t have quite the challenges.
Yes, I think there’s a certain snobbery about that, but I agree with you, and I somewhat share it. I think that’s quite true, I think it’s fair.
Let me ask this. The size of the group of people who were concerned with these three strands you mention, these three issues, has that changed over time? Now, the physics community, you know, has changed; the number of people involved in each of the strands and each of the subspecialties. But this group really capable of dealing with the three strands—have they changed in time, in terms of size? Has this group drawn new recruits? Does this represent a special, what do you want to call it, trouble shooting group within physics?
I think it’s just broken apart. I may be wrong. There are about 2000 people, I understand, in the world who work in particle physics. Something like 2000.
I thought there was that many in this country alone.
Yes. Well, I don’t know—I felt—
Oh, really? As much as that? I wouldn’t have thought so. Well, perhaps it’s 4000—not much different from that. This must be half. So, these few thousand persons, I think, they are people interested in ultimate structure in some sense, either—maybe not, but they’re supposed to be. They might just do some technology on particle counting. But I think this is the same domain. Now, I think those people don’t know much about nuclear physics anymore, or care. At the most they’re interested in proton-proton forces. Even that they probably wouldn’t be much interested in. So I think there’s a great deal of specialization. The point is that there’s now a level of analysis below the nucleus and the nucleus no longer has—it’s exactly if you asked them to study chemistry, they would say. I mean, chemistry too is a very complex consequence of certain forces which have to be understood. But that’s not their job. So I really feel that this multi-strand has broken apart.
When did you see it really taking place, the break?
With the manufacture of man-made mesons, and large machines.
In the ‘50’s?
Late ‘49. I see. And coinciding, let’s say, with the first Rochester Conferences, a symptom of this. Do you think this is a good way to put it?
Isn’t it really a symptom of the change?
Oh, absolutely. I think it is. Yes.
Let’s pursue that for a minute. If it was a symptom, then what were the Shelter Island Conferences? What did they represent? A few years earlier than that. They were concerned with quantum electrodynamics, they were concerned with a number of issues, and then they sort of gave way, these small intimate conferences, the way Oppenheimer described them, gave way.
Yes. I think those were exactly parallel to the Solvay Congress conferences of the past, where a lot of very able people brought with them whatever concerns were theirs, were brought together. I don’t know enough about the organization—There were a couple or three of them, weren’t there?
Yes. So they were really not a continuing thing.
And yet, the first Rochester Conference was already much larger than any of these.
I mean any of these conferences. And you feel that that was a consequence of the big machines producing results in the late ‘40’s and ‘50’s?
…particles, barely mentioned particles. And they were defined very well, this old mixture which was nuclear physics.
So you take the Review articles in ‘37, approximately.
Yeah, That’s everything, you see.
Right. That represents the state of knowledge of that period, and its unified state. Although he doesn’t talk about cosmic rays.
True, and he doesn’t talk about high energy.
So already there’s a branching off.
Yes, but you see, remember what I said was, the high energy was interesting only, or mainly, in that—of course, it was unknown and therefore interesting—but mainly in that the idea that quantum electrodynamics would have a limitation could be found there. So the foundations of your theory of mesons rested upon the ability to extrapolate quantum electrodynamics. So it was a kind of second order. That’s why I say, the Bloch-Oppenheimer arguments, that’s what they’re interested in. Is quantum electrodynamics consistent, sensible, will it work, can it be carried on to higher energy? Or do we see signs of its direct failure? That wouldn’t be very much related to the nucleus. It’s related only to the surety with which we can apply a theory to understand the nuclear forces. Bethe was sort of taking nuclear forces—doesn’t mention mesons, I guess. They were certainly known. I mean, Yukawa had published his paper. But they were not experimentally known, and I don’t think he—I don’t remember in the first two, but I know in the ‘48 book he refers to it, but not very much; in the ‘56 book, he refers to it but not very much. We say that meson theory is still not a sure guide. That’s what it says in the foreword. We can’t rely on it. [We have to] take the phenomenon, have to take experimental forces, and from that we make the story of nuclei.
We went over with him, by the way, in detail the three papers, pointing out what was old, what was new…
The RMP papers?
Yes. It was tedious but it was worth it, to go over them point by point. He indicated what was new, how they had to re-run that experiment to make sure that the data was right, and he sort of relived the writing of those papers.
That’s very good, yes.
Describing the circumstances under which they were written. And I’ve talked with Bacher and gotten sort of the background from him—sort of a case history of these papers. I would like to ask a bit about the book, the Morrison-Bethe book.
Yeah. The only copy I seem to have here is the Italian one.
The first edition was in ‘47.
Yes, July, l947.
And then the second was April, ‘56.
And thinking back, how would you characterize the differences in your understanding of the field and in what has happened historically in that nine-year period, based on your recollections of your approach to the book, your changed approach.
Well, I would say that the book is very early. It’s ‘47, strongly just post-war. There wasn’t much time between the end of the war and the book, and not much went on there. Therefore I would say the epoch that I would understand is maybe ‘50 or so, so there’s really five or six years. The three years there is sort of—In other words, this first edition could have been dated much earlier without surprise. It doesn’t happen to be (we were busy) but it could have been written in 1943 or ‘44. It’s really in some ways even an older period—I don’t know, there’s not much difference...
And yet, what is the difference, between this and the ‘38 articles?
Not much difference.
Well, that’s something that we can perhaps study, you know, systematically.
Let’s look—(leafing through book) It’s not much longer. I think there are a lot of detailed differences, but nothing very grand. Let’s see what it says about mesons. Pseudo-scalar mesons. Of course, that’s a main...that’s a principal difference.
‘47 was before Powell’s discovery, wasn’t it?
Before. It wasn’t included. Of course, this was meant to be introductory, you understand, so it would not have [the latest research in it].
They [textbooks] are an indicator of the packed-down knowledge.
That’s right, but not the fringe at all. But you see, there is a chapter on meson theory. I don’t think the earlier book had as much as a chapter; it had two pages. Something in the foreword, I remember that phrase. I can’t find it. A little space is used, has been dedicated here, on the other hand, to the great developments, recent developments in experimental physics with mesons, theory of the meson field, but only a small amount of space, because as far as the theory of the field, it still doesn’t give in nuclear physics results without the shadow of a doubt.
That’s something we can explore another time. I just thought of another thing, another change, and this is in the physics community. I remember the book review—was it of Alice Smith’s book?
Alice Smith’s book, yes.
I enjoyed that review very much. And you commented about the change in the generations, a new generation of physicists has grown up. And I think it has some bearing on our subject, too, because it has to do with the motivations of an individual, with the expectations in the field, and his choice of problems, with what horizons he sees open to him. And you indicated that in fact the postwar generation had quite different expectations, motivations and horizons. How can you characterize the differences—in the social and political sense in which you meant it, I think, in the book review, but also as relates to physics, the actual science?
Well, there are two things to say. In the first place, people distribute quite widely in respect to all these variables, so it doesn’t characterize everyone at all. But it is certainly true that the role of the physicist in society, the salary he can expect, the general choice of opportunity and career opportunities, are very much larger now or ten years ago than it was 20 or 30 years ago. There was simply no doubt, when you went to graduate school in physics, that you were going to end up being a university professor, or with rare exceptions you might go work in the Bureau of Standards, which didn’t seem terribly attractive. You had to have some very special interest in precision or something like that. And there was no other possibility. Bell Telephone [Laboratories] perhaps had a few physicists—you knew that—but it was a very rare place. So it was a highly academic profession. And now, it’s quite clear, I think not as many as a third of the physicists work for universities.
They work for industry and private...
Industry and government labs, yes.
How does this affect the type of physics that is done? Of course there are other factors that affect it.
Yes. Well, as I said, I feel there is a type of physics that is done, that has remained unchanged with the same traditional motives, but done by different techniques. And then on top of it there’s superposed a lot else. Now, maybe that’s wrong. You know, maybe some has been taken away from that peak. But I see a peak, which is one of the peaks directed toward the philosophical question of the ultimate analysis of matter, and that attracts a lot of the best people, and I think that has remained that way ever since the days it was organized. Certainly for the past hundred years. That continues. A lot of people grow up and read about these things, and want to make some contribution or are interested in this problem. It gets harder. Their contribution gets more and more remote. They have to go farther and farther away, but I think there is this trend. And it’s a philosophical question, a metaphysical question if you like, which has always been pursued, and is likely to continue. Now, what people argue about nowadays, and I think quite sensibly, is whether this will continue to be that way, if the analysis becomes so remote, so expensive, so cumbersome as to require, on the one hand, prodigious mathematical preparation [and], on the other hand, very large laboratories operating big machines, 300 GeV machines. It gets harder and harder to see yourself doing that.
The nature of the tools, to answer certain questions, changes the nature of the inquiry, in a sense.
Yes. At least there’s—you see, people—you must have heard this discussed very often, and I can’t say anything very wise about it, but just to raise the question—Is the individual contribution, which was so sort of manifest in Maxwell, Newton or Maxwell, pretty strong in the case of Einstein—is this going to be dominant in the future? Will it always be dominant? It always has been, perhaps till now—but when you begin to raise the question, maybe not. You see these papers which have 30, 40 authors. It’s a very different situation from what it was before.
I don’t know if I’d say so, maybe not. I’d say that the individual contribution would just be more difficult to recognize.
All right. But it may not be as dominant as it was. I don’t mean not any more difficult to recognize, any more difficult to isolate. That is, there actually won’t be such individual contribution, I think it’s quite—I believe myself that’s the case. I believe that science by the individual may be a romantic notion of the l9th century which like all 19th century romanticism has many attractive, many unattractive features, but it is dying out.
So scientists are alienated, too.
That’s right. Exactly so.
Let me change the subject, on a very practical question, and that is the comment that you made about the practical—you were criticizing us in our suggestion of people to talk with because we hadn’t included enough practical men.
And you characterized this as a peculiarly American development. Evidently this is connected with—it’s reflected in your own career, in the sense of being interested in radio and going into physics because you had electrical engineering and radio work in mind. It has something to do with the availability of supporting technology. Don Kerst said in a casual conversation that the—in our work, no shouldn’t overlook the fact that you could walk down the street and buy a condenser or a spare tube or something at a retail store.
And I’d like you to expand on that, and for you to really say what you mean on that, and what evidence you saw of this as being a contributing factor to the development of instrumentation, and the type of research that was characteristic of this country. Morrison This is a big subject. Also, that it is characteristic of this country I think is fair, but it’s characteristic of this country not in a peculiar way but because of time. That is to say, it’s now equally characteristic of Japan. It’s the same thing. It’s this development of a large industrial technology, and I don’t think it especially has to do with the frontier—[or with the Constitution]—unless those things could be shown to have to do with the presence of a large-scale repetitive industry making highly technical goods. That’s what it amounts to, I see the same thing now in Europe or Japan as [it is]in the United States. But consider this—let me give a couple of examples. I think the best example is given by very clever people, the best possible minds in the field, not only for theory, for deep understanding, but also for experimental design and for ingenuity with mechanical things. Enrico Fermi and Otto Frisch. But these people are obsolete and they know it. If Fermi were alive today, he would know he was obsolete. He said it before he died. He would not be doing the same thing he was doing when he died, if he were still here, I believe. Not that he’s obsolete in every way. He’s not, because he was so brilliant, he could do everything better than anybody else. But he could not compete on this scale of big machine building and computer scanned cloud-chamber output; I think he would not compete with the people who are better at organizing large labs and computer programs. And O. R. Frisch was really sort of ruined by the postwar world. Maybe there are many reasons, but he went to Cambridge, and I think the feeling was that he was going to carry [on]the main nuclear physics experimental tradition of Cambridge, which was going sharply downhill. And he has not done so, and one of the reasons is that he’s not able to work with the electronic world, so to speak. He’s very ingenious, yet he can’t manage that. He invented a kick-sorter, a pulse height analyzer, which stored information by having little ball bearings, like a pinball machine, that get hit by a spring and jump into one channel, hit them a little harder and they jump to another channel, and so on. Beautiful! You can see how simple it is, how cheap—
. —like a Fermi trolley—
Exactly. The Fermi trolley—I want to mention that too. The Fermi trolley and the Frisch kick-sorter are exactly the two signs of the kind of physics which I think is brilliant and beautiful, but which has a very hard time in the world of today. And if it’s to be maintained, I think it’s very important, because I think it’s out of this same attitude that the best things grow, new things. But there has to be a place for it, and the place for it is not in direct competition with these other very elaborate machines. Now, the question is, in all the discussion you’re talking about, it’s all going to be talking about “Where did the idea come from?” of mesons and how did we find out about quantum electrodynamics. The question is, are you getting people to talk about why the kick-sorter and the trolley (a) are good, and (b) are inadequate? What made them inadequate? They were the product of the best minds in the tradition of physics. Now, that’s what I think we don’t—you know, that’s why I say you don’t have quite enough—that’s the same thing Kerst dropped, exactly the same statement to you.
(crosstalk) —This is an interesting subject: If we can cover it all, it would be good. I’d be in a lot better shape next week for my talks with these other people.
Yes. Well, one thing of course is social division of labor, really, is what it amounts to—large laboratories. Because Fermi can design a little trolley, but Fermi just is not going to make transistors and so on. Now, if he learns enough about it, he can start assembling transistors from other people’s catalogues, but even that’s not enough. Because now you don’t do that. Somebody else does that, puts out modules, you know. Alvarez once said, incautiously, I think, but with very great poignancy, that the best experimental physicists in the next five years would be the people who were the best writers of computer programs. You see, and that’s what experimental physics has been reduced to, in many ways, in the large, in the high energy business. When you look at their papers, the experiment is always exactly the same. It consists of having a beam and a hydrogen bubble chamber. And the only thing that differs is, which events you sort out of that mess. (This is a little bit of a caricature, it’s not strictly true.) And that’s done by computer anyhow, so you design that program, and then you get these resonances, which Alvarez really did. To his great credit, he formed the whole experimental style of experimental physics for the past ten years, eight years, by building this huge hydrogen bubble chamber, and getting the idea of scanning it mechanically. He didn’t just have the idea but he pushed all this through, and he forced everybody else to do the same thing. I don’t think it’s very good, but he has the credit and the blame for it.
Not knowing the quality and the high level of the work, but aren’t many of these things engineering problems? They’ve always been—the Fermi trolley was an engineering problem.
And these giant bubble chambers are engineering problems too.
Well, no, you want to be very careful about this, because this is an extremely troublesome point. There’s no question that if you talk to someone I think even as sensible and practical as Bethe, to make a dividing line, but say anyone to the left of Bethe in this sense, anyone more ethereal than Bethe, will take the view that this is all just engineering problems and it really isn’t very important, it has to be done by other people, and physics is really conceptual. But I don’t think this is at all true. I think that the interaction of experimental design and materials with conceptual things is the essence of physics, and it’s lost at anyone’s peril. And the fact that Einstein could develop magnificent things from a rather epistemological point of view is remarkable, but I think it’s not typical at all. It happened to be in the present, but it’s quite atypical. Rutherford’s work is much more typical of what one—of what physics has been in the past. And the trouble is, it was not just engineering when Rutherford directed alpha particles—you see, it’s so simple that you don’t think of it as engineering, but it is.
I was taking that point of view as a probe, but let’s explore the interaction…
I’m not trying to—but I think this is the problem. And just where to put the interaction of experiment and its technique with theory and its technique—also it has a technique—just how to place that is very difficult. The sharp separation of these which has come about in physics is probably not a very good thing. It’s probably just an inevitable thing. And if it separates more and more, there’s trouble, and if one has the feeling, when the experimental physicists design experiments not in terms of some new arrangement of physical systems, but so to speak some new program from systems already made by other people, it represents a loss which might be serious. I don’t know that it will be, I just feel uneasy. And I do feel it loses—well, of course, I’m negative on this point. I’m not—I think you have to have big machines, there’s no question about that. Bob Wilson is building the American big machine. It probably is a very good thing, but he’ll do it in a different way from more routine people. But still the question remains, if you do experiments that are always the same experiment, only you do it faster or with more channels or with bigger magnets, something is lost. Because if you look at the richness of solid state physics or classical nuclear physics of the past, it wasn’t that way. You put magnetic fields there, and you made resonances with rf, and you do it at low temperature, you do it at high temperature—all kinds of things to combine. The combinatory richness is very much greater. But in high energy physics we have no hold on the whole thing. It’s always just the same experiment. You throw something in, you see what comes out.
This raises an interesting question which is a way of exploring the interaction between experimental work and the conceptual ideas, and that is to ask if in a particular period the experimentalists were working under a particular model, if they had a particular model in mind, and even though they didn’t contribute perhaps to the development of that model, but was it—does the shell model motivate an experimental researcher?
And in what sense? I think there may have been a period where an experimentalist could have taken two or three models, taken his pick, because none of them really dominated the field. And we’ve had this in the responses of some people.
I think these are the kinds of questions that we’re going to have to ask, to get into this point. It’s a very difficult point. What you’re saying is, we can’t treat it separately, and yet—
Well, you can treat it separately, perhaps, I just don’t know. But I’m just saying, one can’t ignore it, and I don’t understand—the only way not to ignore it is to bring in people who are familiar with what happened—that I can think of. You see, large-scale equipment and fact electronics are the characteristic things of the present day. Now, as you go back, when do these become possible and when do they suggest new experiments, new techniques? The cyclotron had really neither of these. Well, the cyclotron had a large-scale experiment. That’s what it was, it was bound to be large-scale, with many people involved, lots of—And it gave you intensities which were unheard of in other applications. You see, originally nuclear physics began with radioactive substances, after all. And you could accumulate a small amount of those. In a sense, that was a large-scale operation. The one thing that you had was $10,000 worth of radium which had been put together by some chemical firm. Many people worked to purify tat, but it was so remote from you—you just transferred the money and you got the thing. But you had captured the work of ten chemists or a chemical engineer or two. And that’s the difference. Now—you have to build the stuff yourself. Maybe, we turn more to that. You buy computers. You buy that whole computer technology—that’s sort of a thousand people in a factory. You don’t see them, you see the computer. It’s a little bit like that. Anyway, the Rutherford thing was a tenth of a gram of radium, let’s say, and the cyclotron is like a thousand grams of radium. That’s just what it represents. Now you can look for unusual events. You can classify things very carefully, and still have something to happen, which you couldn’t do before. And that was the whole—that was the contribution of the cyclotron, speaking technically. It was not useful for precision work, it was useful for rare events, for details of a process, because you now can see things that happen only once in a while. They had lots of intensity. And of course it extended the energy. The other main point is, it gave higher energy than natural radioactivity. And this trend, begun by the cyclotron, has never stopped. We now go to higher and higher and higher and higher energy, and it demands bigger groups. What it’s also beginning to demand is fast electronics, which was not the case in the cyclotron days. You used radio technique it was good enough. But row radio technique is no longer good enough.
But when people were building the cyclotrons, in the early stages, they were very much concerned with using it for specific experiments related not to an existing theory, but they too were exploring the nucleus. They weren’t just trying to prove someone else’s theory and get the first results. Morrison. No, no—in detail they were, but in general they were not. That is, the machine—that’s another way of putting it. Physicists built apparatus which was on a table top, on a bench too like this. It was made for one experiment. The experiment was done, and then the apparatus was junked. But the cyclotron was built not for one experiment or one experimenter, but for many experiments for a long time, so it must have been conceived as having much more general use. It had to be seen that way. Of course, it was seen as a source, like 1000 grams of radium, which many people could use, because it was clear that somebody had made a lot of experiments with just one-tenth of a gram of radium. With a thousand grams of radium, probably—many people using it at once, etc. And it was all true. So that’s really what—I mean, that’s a part of what’s involved in this business. So they built the cyclotron to have a look, to have 1000 grams of radium, and also to have high energies, which everyone recognized would be important for the eventual analysis, both of matter in the ultimate and also the larger nuclei. You see, you could say, directly we knew there was a Coulomb barrier, so to shoot charged particles at the nucleus, you must have high energy to get in. The cyclotron people saw that, so they could make you lots of particles at high energy, and this just started a progression that has risen exponentially ever since.
We’ve reached some sort of critical point in this, where the function of change—in other words, where the creative efforts went into better detection techniques, rather than merely into higher energies. Or was this simultaneous?
I don’t think so. I think it was always that way. You have to have both together. Now, maybe at any given time they go back and forth. But you see, the cloud chamber (C.T.R. Wilson, 60 years ago, 70 years ago) became a very valuable instrument 20 or 30 years later. All of nuclear physics, all of this kind of physics that we’re talking about, from 1920 to 1950, about, was dominated by the cloud chamber, the most important single results. And since then there have been many other detectors. And I think at any time there were always people working on detectors appropriate to the sources that were available.
It would be very interesting to really trace the relationship of the detector to the source, to see in fact what the chain of events was, and then to take it one step further back, or maybe one step ahead, depending on how it comes out, the relationship to theory—whether a machine was built because of developments in theory, and we have instances of this—
And in another case, where a machine was built because this was what would make theory possible. The early cyclotron, this is one way of characterizing it. I think—you know, for our purposes—we’re going to have to develop some of these things independently, and look for the points of interaction.
Yes. I think that’s reasonable.
Because the story just falls into those patterns. Let me ask this, for the people in California, what do you think some of the most fruitful questions would be? I’m going to see Segre and Alvarez the first two days. Keeping in mind these comments and our general weakness in this area, how can we beef up our understanding of this by directing certain types of questions to them?
Well, I think one should ask them how they saw the role of the cyclotron in the first—how this changed as time went on. What was it for? What was it good for?
How about something specific to their own work which gets them in a sense to open up? I mean, you think of Alvarez and you think of time of flight measurements, and a number of other specific things. For example, in ‘46 the first proton linear accelerator, ‘46.
Of course the linear accelerator is a straightforward accelerator development. I mean, he was thinking of a source, of a high energy source.
What I’m getting at is that I don’t want to ask the questions that will give me answers which reminds me of someone at MIT (Woodbury) who does technological history—you know, strictly one part fits into the next, and one gear fits into the next, and it sort of becomes a chronology. It’s hard, and I’ve learned this from talking with Cyril Smith, how hard it is to do, but when you’re dealing with history of technology and you’re talking about hardware and the role of instruments, it’s very hard to pose questions that are perceptive, because you can phrase the obvious questions and get answers that are not very helpful.
Well, the historical background, the detectors and instrumentation, is all either photographic plate, cloud chamber,—electroscope and geiger counter. Now, photographic plate and cloud chamber and electroscope are prehistoric. I mean, there’s no use discussing them in this context. Geiger counter is literally so, but it was developed much better in the late ‘20’s and early ‘30’s. So I think you might ask Alvarez what he thought the contribution of electronics, especially radio frequency technique, had made to the whole field, beginning with the familiar self-quenching geiger counter. That’s where he would probably have started. And I think that’s useful to ask him.
Not only, what was the contribution of electronics and radio frequency techniques, but the background for it. How it was introduced and why? What were the motivations?
I think that the questions with him—if we start off on this thing, I think the rest of it can flow on a good track.
See, the ionization chamber was used for a very long time. It goes back also to the prehistoric days. But it was used in the old days with an electrometer or galvanometer, and sometimes the whole thing turned over to using a linear amplifier, using an electronic amplifier, and that is the beginning of more appropriate style. Remember, it’s in Fermi somewhere—in Fermi? I was reading this…Fermi, anyway, happened to come upon a radio transmitting tube in the laboratory somewhere, and this made possible a very interesting experiment he did, this was in the ‘20’s. There weren’t so many radio tubes. He just came upon one, luckily.
I have a lot of interesting questions for Segre based on things that he’s written, on research support in Italy and so forth, and the whole background of this, and so there are leads to questions that we didn’t discuss, which open up some very interesting areas. What about—you may think of more on Alvarez, but let’s just go from him for a minute to Fowler and Lauritsen. That’s a different story, it seems.
Yes. Well, here I think it’s quite clear that you’d like to hear something about the development of how they would regard the Van de Graaff, the electrostatic beam, as being—was it in a different domain from the cyclotron? How did it get started and what did they think the aims of it were and so on? You see, in Fowler’s case in particular, the interesting thing is—Lauritsen, of course, you can certainly—this is Tommie—you can get started on the transition to discussing energy levels in detail, from the shell model, because you will find that quite interesting, I’m sure. Fowler did something—is connected, correctly and also popularly, with something which is quite interesting, and that’s the application of nuclear physics, which is one of the things that made nuclear physics very attractive, I think, which is not clearly the case for particle physics. I think I told you about ultimate analysis of structure as being a theme. But another thing is, suppose you do learn some structure, does it help you to do anything else, or is it just itself? Nuclear physics does, because nuclear physics tells you how the stars work.
Distribution of the elements sort of thing?
Yes. That’s right. And Fowler, more than anyone else, is connected with that development.
Well, I know a little something about that. One of the things that got me interested in many of these things was hearing Hoyle describe some of this work with Fowler, and I’ve been following that. And we’ve talked with Bethe about that, too, he’s given us the background of this. We are not wearing blinders, we are going into these applications, because in turn there’s some—I see more and more, especially in that field, an enrichment coming back into the main stream of nuclear physics, and in elementary particles. Fowler was talking informally at this press conference before his talk, and he was commenting on Dicke’s papers, and saying he thinks perhaps a more fundamental test of general relativity would be in relation to the quasars. And this was in relation to some of his own work that he was developing. So these things hang together.
But that’s all very remote and difficult, I would say.
See, in general astronomical matters—not for 300 years has physics learned anything from astronomy.
There was an input in spectroscopy, I think.
I guess it’s true that the first, the helium spectrum was shown by Bohr, but it was a trivial matter. With him it was just a confirmation of his theory.
You think it’s all been the other way around? Application of physics to astronomy?
Sure. Physics to astronomy, that’s right. You see an astronomical result that suggested it—Hoyle’s very fond of making an exception to that. He’ll snow you immediately because he did it. He predicted a certain energy level in carbon 13, and if there weren’t that level, then the cross section would be small. It had to be some augmentation or the cross section to make things work well, or there’d be too much of the stuff. So he predicted it and it was found. It may be true. But, you know, there are thousands of levels known, and exactly one of them may have come out of astronomy. That’s the way it now stands. So I don’t—I’m worried. I don’t think you’ll learn much about general relativity. You might, by studying quasars, but I’m skeptical. It’s the other way around—if you understand general relativity, maybe you can understand quasars. It gives an incentive. Perhaps that’s the best way to put it. I think there’s a lot of interest in general relativity today, because of quasars, which there wouldn’t have been.
Let’s apply this to what you said before, about people concerned with the ultimate structure of matter. Do you think that there’s another group, first cousins let’s say to that group, who are interested in cosmology for much the same reasons?
Yes, but I would say this was the same interest. I mean, these are metaphysical questions, two different metaphysical questions. For a long time people have thought they might be related. If there were found a relationship, if they are related, then everything would be happier again. And I think many people feel that relation, it’s enough to cause them to look in one direction or another. They have very different social backgrounds and milieus and so on, but I think broadly speaking, this is the same. But this is not a question of having anything whatever to do with a particular physical phenomenon, or with the practical application, or with mathematical elegance. They’re primarily philosophical questions, metaphysical questions, to which people want answers, traditionally. I think they may come together or not. I agree with you.
These types of areas have always been the frontiers, the leading edges in science, I think.
But, you see, there’s another approach, another question. I think the 19th century people were much more concerned with what is electricity and magnetism, you see. What were these forces.
They were looking for…
They were looking for unity, more than they were looking for…
…nature, they wanted the “unity of the imponderables”.
I think that’s another metaphysical—but I mean, that’s a different one from these again. I would not exclude it. I agree. I’m trying to say that whether it is the ultimate structure, in terms of small size or in terms of large size, or whether it’s the nature of interactions, these are a search for some sort of metaphysical unity. That’s what was involved.
This is the thing that motivates science, always has, I think.
This search for metaphysical unity. What I was getting at, though, in this experiment to see what can be done as a first approximation in mapping out the development of the field—we’ve chosen nuclear physics—we are committed to proceed to solid state. Then it’s a question there are altogether different problems involved in that.
And then I’m very anxious to get into some hyphenated fields. There’s another experiment, you see. Meanwhile, hopefully we’ll be digging deeper in each of these that we started. I can see biophysics and astrophysics. That’s two of them developing along this line. I think we can learn a lot of good technique, historical technique, because they’re sufficiently different. Well, let me just see if there’s anything major that I wanted to ask. Let me just ask this. Over a period of time, the centers of research change, and if you could characterize several different periods—let’s say, before the war, the period when you were at Berkeley—and look around on a world scale, and in historical retrospect. Then take another look at the immediately postwar period, then ‘56, and then, maybe now, and find out where the clustering of activity in nuclear physics is. You may get in trouble when you go beyond ‘56, because you’re going to have difficulty defining nuclear physics after that. For example, take the period of the late ‘30’s just before the war. Where would you feel the real centers of activity were?
Just before the war?
Well, it depends on how broadly you want to look at it. Do you want to look at it experimentally or theoretically or both or in terms of size? Because now I see the subject so differentiated. There is no doubt that Berkeley first and maybe secondly Cal Tech were very important, and Columbia and Princeton were important, for somewhat different reasons. Harvard was important. Cambridge University was still quite important, but the death of Rutherford was pretty hard on it. But I guess we’ll have to say it was still very important. And there was a school in Paris, the Joliot-Curie school, which has to be reckoned with. The Rome school was about to die, and the German schools as a whole were dead. Copenhagen was still existing. There was not much in Japan or anywhere else that I can think of; not much, a little bit in Russia. Landau and Kapitza in low-temperature physics.
Looking at all these different centers, can you put them in categories, different types? Without finding the idiosyncratic differences between them, but you know, this group represented a certain approach, that group represented a certain approach…
Yes. Well, I think Berkeley represented the machine approach, the big cyclotron approach, lots of people working on big beams but not very much precision, a lot of activity, strong neutron sources and things like that. And that was the model, perhaps not quite duplicated, by a number of other American places. And I think that was unique, there were no other—no non-American places like that. But then the other American places which were good, as I mentioned, were Harvard and Princeton and Columbia.
What made them good, do you think?
Well, good people, large groups, both of those things. They were similar to Berkeley but just lesser than Berkeley, I would say, in some ways. And in the case of Columbia and Princeton they had outstanding individuals who, for particular matters, were better than Berkeley. Columbia was especially interesting because it had the very strong school of Rabi, the molecular beams business—this was very precise work, which is connected with nuclear physics in a very curious way, you see—studying with great delicacy the properties of nuclei at zero frequency, so to speak, DC at lowest energies, but they did that so well. I mean, with such precision that they made many definitive experiments that were valuable for nuclear physics—mostly, not exclusively, mostly on the problem of the interaction, the deuteron problem, the interaction of the proton…fundamental sort of interactions.
—in the period?
Oh, yes, certainly, Rabi and Kellogg, Zacharias, Ramsey, Schwinger.
Yes, there was a whole school.
Yes. And of course Fermi had just come there, perhaps we should not count that. Before the arrival of Fermi, and after the death of Rutherford, six months apart or something like that. Cambridge University would have, you know, powerful people like Dirac who were not close to the work but gave a kind of aura to the thing, plus a very strong tradition of people working in cloud chamber, and Blackett, Cockcroft and Walton. But clearly it was fading. Clearly it was not the dominant place that it had been from 1900 to 1935, where the center of every experimental work and influence came from Cambridge.
You think of this as a center experimentally. Columbia would have been in this experimental category?
Berkeley, mostly experimental again.
Well, what would fit now with theoretical, going back to your—this group? Of the centers of research that you mentioned, which would primarily be characterized as theoretical?
Copenhagen and Zurich.
How about in this country?
Princeton, I suppose, but it wouldn’t be particularly strong. Yes, I mean, Wigner and Wheeler were certainly both working. Individual persons. Theoretical physics doesn’t require a group so much, so this was more individual people, wherever they happened to be.
That’s an interesting point. How about centers of teaching? In other words, I wanted the centers, but now I’m asking you to produce a reason. You’ll probably say Berkeley because there were so many graduate students.
Yes, that’s right.
And where else? Columbia, would you think?
Yes, I suppose so, Columbia and Cambridge and Copenhagen.
That’s something I probably can take a good look at too. I’d like to look at the figures, you know, the number of students at a place, source of support, and then ask people why they were attracted. That’s why I asked you why you went to Berkeley, rather than other places. That’s the period before the war. How did this change just in the immediate postwar period?
Well, I suppose the dominance of America was now even stronger. It was sort of 50-50 before the war, I would say, where it had been 1 to 10 five or eight years previously. But after the war, its dominance was even clearer. Now it was 2 to 1 or 3 to 1. And then the European laboratories got rehabilitated, and the Russians and the Japanese began to play a role.
Not on the same scale?
Not in the immediate postwar period, but—OK, so the immediate postwar period, the European laboratories, Cambridge is still less interesting than it was. And I suppose it would be a mistake to forget Birmingham, which was now stronger than Cambridge. We think of Birmingham first.
Manchester was strong for a while too, in the early ‘30’s?
Oh—before the First War, when Rutherford was at Manchester. And then it had some residual glory, but it wasn’t very much. I guess they had Blackett. Blackett was trained at the Cavendish, and went to Manchester. Then, Birmingham had Peierls and Oliphant, and even before the war—Birmingham was beginning to come up before the war. I don’t remember for sure whether it was ‘37, ‘38, that Birmingham was equal to Cambridge, or maybe not. But after the war, Birmingham was better than Cambridge.
Bethe and Peierls were at Manchester, I know, for a while.
Blackett brought them there. But for a very short time. A year?
And how about the redistribution? Was there a major redistribution within this country, then?
Yes, there was, and of course the national laboratories began to play an important role. Berkeley was important, Los Alamos was of some importance, Oak Ridge was of some importance, Chicago was of some importance. The big laboratories got going, like Brookhaven. The whole thing, of course, was now multiplying.
But Berkeley’s role wasn’t reduced.
Well, I suppose relatively it was.
Oh, yes, but…
Absolutely, no, it was even stronger. It was much larger.
Did any new places come into existence other than the national laboratories that weren’t in existence before the war? For example, you said that Cornell had a tradition, so it expanded and they got a certain type of research support.
We know that Harvard had beginnings before the war, I think that’s correct, and Berkeley and Cal Tech, and Illinois, we’ve talked of that, and Chicago and Columbia. Where were the newcomers? Or was it just a strengthening?
There aren’t any.
It has remained the same. It would be interesting to think about it.
It’s still true. The universities, the number of distinguished universities doesn’t change.
Maybe, the number doesn’t change, but it doesn’t always have to be the same ones.
The same ones are still—the list doesn’t change. Now, is this strictly true? There may be many exceptions. There probably is an exception somewhere, but we haven’t found it. What I think of right away is La Jolla. It hasn’t got—but in its own special interests, it’s very very good in astronomy, and that sort of thing. This is now quite recent, only the last two or three years. But again, it sort of trades upon the University of California as a going concern. It isn’t a brand new place.
You know what this suggests, this continuity suggests that it’s not so much due to the presence of a single individual, but to—or example, Cavendish Lab changed substantially in the period after Rutherford’s death.
But by the time of Lawrence’s death, Berkeley didn’t change. In fact, there was a facility there and the very momentum of this facility created a drive for more facility.
But I think that’s exactly what I was saying, too, that there was a time when the Cavendish Laboratory was Rutherford. There was a scale on which the Cavendish Laboratory was Rutherford. After Rutherford’s death, in spite of tradition, the great university was never to acquire that strength again. But there’s a scale on which it doesn’t matter if there’s Lawrence or not. It’s just so big. In other words, the influence of the individual, the 19th century romantic, is going down, and now it’s the organization which counts. Now, Berkeley or course has not been the leading place now, in high energy physics, this business—it has not been the leading place for ten years now. It’s been one of the leaders, but earlier it was unquestionably the leading place. Now, Brookhaven and CERN have systematically been doing better things than Berkeley, for the last eight or ten years. Though Berkeley’s input—Alvarez’s invention of this style of doing things—really made CERN and Brookhaven work.
Elementary Nuclear Theory (John Wiley & Sons, New York)
A Peril and a Hope (University of Chicago Press, Chicago, 1965)