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Interview of Robert Shankland by Loyd S. Swenson, Jr. on 1974 August 21, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/4886-2
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Family life and early childhood environment; undergraduate studies at Case School for Applied Sciences, 1925-1929; M.S., 1933; influence of Dayton C. Miller; reanalysis of Miller’s absolute motion experiments, meetings with Albert Einstein; National Bureau of Standards (NBS) work on ionosphere and standard frequency regulation, 1929-1930; contact with University of Chicago, l930s and 1940s, thesis work on photon scattering under Arthur H. Compton, 1935; World War II sonar work in submarine warfare; architectural acoustics interests; tasks as Chairman of Physics Department at Case Western Reserve University, 1940-1958; consultant to Argonne National Laboratory, neutrino experiments, 1953-1969. Associations with D. C. Miller and A. H. Compton, their experimental style, personalities and influences on others; climate of opinion around relativity and quantum mechanics; the crucial Michelson-Morley experiments and others in relativity; comments on the resistance of the older generation of physicists; reaction to fission and the atomic bomb; problems of modern physics and comments on relation between pure and applied sciences, the existence of a scientific method, physics as related to other sciences, approaches to the history of science. Also prominently mentioned are: Samuel K. Allison, Luis Walter Alvarez, Samuel Austin, Raymond Thayer Birge, R. Blondlot, Niels Henrik David Bohr, C. P. Boner, Bragg, William Lawrence, Sir, Gregory Breit, Karl Taylor Compton, Walter Dale Compton, Karl Kelchner Darrow, R. L. Doan, Saul Dushman, Carl Henry Eckart, Thomas Alva Edison, Enrico Fermi, Armand Hippolyte Fizeau, Lester L. Foldy, Gustav Ludwig Hertz, Oliver Wendell Holmes, F. R. von Horn, J. W. Horton, William Vermillion Houston, Frank Clark Hoyt, Z. Jeffries, Edwin Crawford Kemble, G. Kuerti, Joseph Larmor, Ernest Orlando Lawrence, F. Leone, Hendrik Antoon Lorentz, W. H. Martin, Emanuel Maxwell, Sidney McCuskey, Albert Abraham Michelson, Dayton C. Miller, Robert Andrews Millikan, Jason John Nassau, J. Robert Oppenheimer, Henri Poincare, Baron Rayleigh, John William Strutt, Owen Willans Richardson, Henry A. Rowland, Henry Norris Russell, Ernest Rutherford, Harlow Shapley, John Clarke Slater, G. Szell, John Torrence Tate, Geoffrey Ingram Taylor, Joseph John Thomson, Merle Antony Tuve, John Hasbrouck Van Vleck, M. Walsh, M. Walters, Robert Williams Wood; Bell Telephone Laboratories, Case School of Applied Science, George Washington University Law School, Mount Wilson Observatory, Phillips Petroleum Co., United States Navy New London Laboratory, and United States Office of Scientific Research and Development.
OK, we seem to be recording all right. This is the third tape made by Loyd Swenson with Robert Shankland — August 21, 1974. I would like to begin with a few words about our wonderful meeting together last night and our informal conversation about your hobby, collecting steel traps. I think that’s a most remarkable and unique kind of hobby. You’ve been interested in fur trapping since a boy; how many traps would you say that you have now?
Oh, I’ve probably got 2000 all together. But they’ve been accumulating all my life. I’ve never made any sustained effort to go out and get traps, but whenever I go to the back country and talk to interesting old people, why, I usually end up with a few traps. The big problem now is, what to do with them, and I don’t know just what I’ll do, but I’m not going to give them up for a while because they mean a great deal to me.
And you actually made money as a trapper, as a boy, in and around Ohio.
Trapping you say mink, muskrat primarily?
Muskrat, mink, fox, raccoon, skunk and opossum were the furs we had then. There were no beaver in Ohio in those days, at least none that we could catch. But it was great fun and it got me out of doors, and gave me better health, I’m sure, than as if I’d done some other things in my youth. It’s an amazing story, how the development of this country followed the fur trade, in the northern part at least, and the southern part to a certain extent, too. You see, even in your Texas there were deer and things of that kind that were tremendously important in the fur trade, through Santa Fe in the early days. Far more important than the mining or railroads, in my opinion, in developing the country in the first instance. And in Canada, the fur trade was a central factor in the development of Canada and in the unification of Canada. The Canadian-Pacific Railroad was built by the man [Donald Smith, later Lord Strathcona] who was at the same time the head of the Hudson’s Bay Company. Without the Canadian-Pacific Railroad, it’s questionable whether western Canada would be part of Canada or part of the United States.
Well, that hobby interest, together with your interest in architectural acoustics, has made life very interesting for you, moving around the world and looking at famous old buildings, and looking at nature in the wild.
Oh yes. It certainly has been a wonderful hobby, and I hope I continue it as long as there is some wilderness left in the North American Continent.
Well, we’ve come now to Section III in our proposed agenda or outline, “The advent of nuclear physics.” Before turning on the recorder we talked a little bit about some of the items on here, but the first item was suggested by Roger H. Stuewer, because of his common interest with you in the history of atomic and nuclear physics, in the thirties and forties.
Well, I have some very very sharp memories about those years. The early thirties is when I was a graduate student at the University of Chicago, and when I entered the University of Chicago, nuclear physics was practically unknown, except for the great experiments of Rutherford, which did not have too much impact in this country. However, starting with the year 1932, there were a succession of tremendous discoveries, the neutron, artificial radioactivity, the theory of beta decay, and the whole subject of nuclear physics suddenly moved to the center of the stage. And it had not been, at the University of Chicago, to any degree whatever before that time. Professor Compton shifted his research interest to cosmic rays, but the development of nuclear physics as such occurred elsewhere. I can recall visitors from the University of California at Berkeley coming to Chicago in the summers of the early thirties, and telling us first about Ernest Lawrence’s cyclotron and other high energy accelerators. This was a — like hearing from a new world, to those of us who were working in the Ryerson Laboratory. Some people like Luis Alvarez were set on fire to go and work with Ernest Lawrence as soon as possible. As you well know, he was one of the great collaborators of Lawrence. At the University of Chicago, Professor Samuel K. Allison was the first to undertake nuclear physics. He spent a year at Rutherford’s laboratory in Cambridge, then came back and built a Cockroft-Walton accelerator, the first machine at the University of Chicago. If I remember correctly, Allison had $3000 as the budget to launch a nuclear physics laboratory in 1936 or thereabouts.
There was another development at Chicago, however, Professor W.D. Harkins of the chemistry department, who had done early work with neutrons and was always interested in radioactivity, obtained larger funds, and built a cyclotron. Later on, this cyclotron was placed under the direction of Professor Allison. It would have made significant contributions too, except the war work came along and all the energies of the University of Chicago physics department were diverted toward the Manhattan District and what later became the Argonne National Laboratory. I think the other turning points in nuclear physics that were most significant, in addition to the new approach that Ernest Lawrence brought in at Berkeley in building large machines and’ introducing the team effort in physics on the experimental side, were obscured by the wartime activity of most physicists. The effort in radar went back to exploitation of electromagnetic theory, and the fission work and the nuclear work really depended on the work that (Otto) Hahn and Rutherford had done earlier. There was considerable excitement about the discovery of fission, but the subject became classified so soon that most physicists did not follow it in any detail during the war. As a matter of fact, most physicists were greatly surprised by the atomic bomb, although under cover, there was knowledge that something of that kind was going on. But the magnitude of the effort and the fact that it would produce a tremendous explosion of the magnitude achieved, I think was a surprise to nearly all physicists. A sizeable number of physicists, of course, hoped that it would not be possible, because they did not want this kind of an explosive available to the military. After the war, I think the most striking turning point were the experiments disproving parity, and then, a number of other experiments that were important in nuclear physics. The work of (Edward M.) Purcell and (Felix) Bloch, the great experiments of (Willis) Lamb, and the discoveries in high energy physics, which are still going on and still not completely explained.
Parity, Yang and Lee?
Yang and Lee, and also the experiment which proved parity non-conservation the experiments at the Bureau of Standards and also those of Garwin and Lederman at Columbia. Purcell is at Harvard, and Bloch at Stanford, with their nuclear magnetic resonance. And then the Lamb experiment at Columbia, which forced the development of quantum electrodynamics.
Who is this Lamb?
Any relation to Horace Lamb perchance?
I really don’t think so, oh no, I don’t think he’s any relation to him. For many years, the physics community as a whole has been eagerly awaiting other great discoveries, both experimental and theoretical in physics. But we so far have not found the great turning point that you mentioned here that is hoped for. But it will come. It’s a question of what time it will come. My own personal interests during this period were more concerned with atomic physics, although I did have some interesting summers at Berkeley working in Lawrence’s Radiation Laboratory. I think when the history of this Radiation Laboratory is completely written by Alvarez and people who knew it well will constitute one of the great chapters in the history of physics. Lawrence’s work is well known and well understood, but the complete and deep appreciation of his methods and how he worked and the loyalty and enthusiasm of all the people who worked in his laboratories has never been completely described for physicists in general. I think he [Lawrence] will rate right along with Rutherford, as a great leader in developing physics in our time. Now, let’s see, I’ll stop a minute.
On that subject, do you know Stanley Livingston?
Yes, I know him, not well, but I know Stanley Livingston, yes. What is your question about him?
Well, it seems to me, as a spectator from a distance, there’s a problem with regard to research and development and credits. Was there not a bit of a strain in the relationship between Livingston as a graduate student of Lawrence, and those who saw Lawrence as the great designer and developer and entrepreneur in his own right? Is that a true assessment of the situation?
Well, there has been discussion for a long time as to what was Livingston’s proper share of credit for the cyclotron, and what was Lawrence’s proper share? I certainly don’t know. Livingston built the first cyclotron that really worked well, but it was already worked out by Lawrence himself, and an earlier model by Lawrence and Edelfson had priority in one sense. I think Livingston deserves great credit, but from where I look at it, Lawrence was the real inventor of the cyclotron. I remember once when I was at Berkeley, this was being discussed informally with Professor Raymond Birge, who was the head of the department all during that time. Professor Birge’s comment was simply that, “Well, if Livingston wasn’t given as much credit as he should have been by Lawrence, that’s the only case in my knowledge where Lawrence wasn’t overly generous with everybody.” So I would say Lawrence getting the Nobel Prize for it was proper credit, but Livingston was certainly a very important colleague. Do you want to go on now to reactions to relativity and quantum mechanics? Where are we?
Fine. Before we turned on the recorder I asked about the title of your doctoral dissertation, “The Photon Theory of Scattering” which was completed I guess in ‘35, published in ‘36. I particularly asked about the coinage of the word “photon” as opposed to light-quanta, or other words that have been in use since 1905. You said that by the time you arrived in Chicago, the word “photon” in its modern connotation was generally being used by everyone?
Yes — I think “photon” was generally used in exactly the way we think of it now. Perhaps there were a few more properties that were not appreciated fully at that time, but the word “photon” as a quantum that carried both energy and momentum was a common term used in Professor Compton’s classes and all the other classes at the University of Chicago at that time. Since then, there’s been a fair amount of historical research on the first use of the word “photon.” I believe it’s credited to Gilbert N. Lewis of Berkeley. However, his photon theory, as I understand it, is not accepted today as a meaningful theory. It has too many facets that do not agree with experiment. Professor Compton in later years pointed out that Gilbert Lewis introduced the term “photon,” but in the years at University of Chicago, I never recall Compton having mentioned Lewis or his part in the photon. But I’m sure that by 1931, the photon as we now understand it was an accepted term, and its properties were essentially those that we know today and have known for many years.
Could you say something about your dissertation itself, in terms of its choice? Was it assigned to you or did you choose it freely? Was there experimental data, as well as a theoretical analysis of scattering involved?
Yes, if you’re speaking of my doctor’s thesis with Professor Compton. Professor Compton suggested that I devise an experiment to show the angular relationship between the scattered photon and the recoil electron, and at the same time, demonstrate the time coincidence in the event. The earlier experiments, the Compton-Simon experiment, had shown the angular relationship to a tolerable degree, and the Boethe-Geiger counter experiment had shown the time coincidence within certain limits, but the two together had not been demonstrated. Compton thought that should be done. So I devised an experiment using Geiger-Muller counters to do this. At first we obtained results that seemed inconsistent with the Compton theory, and we were inclined to say that they supported the Bohr-Kramers-Slater theory, which ascribed a statistical view to the Compton interaction. But we found very soon that our counting rates were too high, and that we were experiencing what we now know as the dead time of the counters, and we were missing a number of true coincidences. So when we used weaker sources of gamma rays, better circuits, then we got the coincidences that we reported. And these showed both a time coincidence within 10 seconds, and an angular agreement with the Compton theory to about plus or minus ten degrees. There was a reason why we were inclined to seriously consider the Bohr-Kramers-Slater theory at the time: there was some real concern about some of the bases of nuclear physics, and quantum physics; the neutrino process was not completely understood at that time; and there were feelings among the Chicago physicists at any rate that something more drastic than even the uncertainty principle was needed. Even Professor Dirac of Cambridge got into the discussion. But that all turned out to be unnecessary, and so I for one was glad when we confirmed the Compton experiments and the Compton theory, and we didn’t have to go to some new thing.
May I ask about the status of gamma rays? In ‘37 you published a paper on the scattering of gamma rays, and the Compton effect with gamma rays, at the same time. Is this what you’re talking about? Are there gamma particles now? Were there then? Or were there hopes then that there might be?
I don’t understand your question.
Alpha rays, beta rays, gamma rays — alpha particles, beta particles, but — gamma particles?
Well, we never raised that question. To go back to the photon hypothesis, the gamma ray that we thought about in those terms was basically a quantum particle carrying energy and momentum; there was very little interest in its wave nature in the experiments that most of us carried out. Of course, we realized that it had wave properties too, but we considered it a particle just the same as the alpha or the beta particle. It’s a different animal, to be sure, but if you are really immersed and believe in quantum processes, you don’t make any distinction between the two, because the essential thing is, what does it carry? And not its size or shape or anything like that. So I think, perhaps we were more amazed that the gamma ray could be diffracted by crystals and slits and so on, than we were by anything else. We knew that it should be possible, but it has an extremely short wave length, and those were kind of tour de force experiments. So I think we always thought of the gamma ray as a particle. Not the particle of mechanics, but a quantum particle.
Was the same thing true of cosmic rays? Had you made a distinction between primaries and secondaries?
Of course, at the University of Chicago Professor Compton and his student Luis Alvarez did early experiments that showed pretty clearly that the primary cosmic rays were protons. And we were never of the opinion that they were gamma rays, as Millikan had believed in his experiments. So I think, in the case of the cosmic rays, the particle nature was the dominant thing. Gamma rays that appeared as secondary processes were believed to be regular gamma rays, but they were really not the interesting part of cosmic rays. The interesting part was the mesons and the other particles that were produced. So I would say, cosmic ray physics from the outset as we learned it at the University of Chicago was predominantly a particle phenomenon. The gamma rays were just background or secondary. Now, the view at Cal Tech under Millikan was quite different. We certainly didn’t share that view at the University of Chicago. O.K. You have a question here about reactions to relativity and quantum mechanics. This is an interesting question, because when an entirely new view comes into physics, there are various reactions that come in.
On the side of relativity, personally I was disposed toward relativity at a very early age, because of my father’s enthusiasm for the eclipse work of 1919, and the achievements of Professor Einstein. When I came to college, I found that there were a number of physicists of the older generation who had a contrary view on relativity. The whole thing was obscured by a lot of newspaper talk and arguments by people who didn’t understand the theory of relativity. But I would say that this is nothing peculiar to relativity, that any new subject that comes into physics is viewed with coolness by the older generation, not because they’re old, but because they’ve already attached their thinking in other ways. Just to illustrate this — here’s a famous letter of the great Lord Rayleigh, in which he explains how he would much rather use the elastic solid theory of light than Maxwell’s electromagnetic theory because it was simpler. Now, any student of physics today who attempts to learn anything about the elastic solid theory of light will find difficulty in understanding how Lord Rayleigh thought it was simpler. But the point is, he had grown up with it, he had used it, and he wasn’t about to change just because here was something new.
So I don’t think there’s anything unusual about the gradual change in the acceptance of the theory of relativity. The name itself brings into play a lot of thoughts in people who really know nothing about the physics. I think it would have been much better if Professor Einstein’s original title of “electrodynamics of moving bodies” had been used, and if the word “relativity” had been left out. But of course, that’s not the way it evolved. Now, on quantum mechanics, the situation was a little different. This was a far greater change from earlier thinking than relativity, because after all relativity is sort of the capstone of classical physics, whereas quantum mechanics is an entirely new view of things. The uncertainty principle, wave nature of matter and radiation, wave-corpuscle dualism and all those things represent entirely new ways of thinking about nature. This did not receive a reaction nearly as strong as relativity, because it came gradually on the theoretical side, by a group of young people who had studied in Europe with the developers of quantum mechanics. And they came back to this country and gradually introduced the subject to young people here.
Before long a whole generation of physicists were using quantum mechanics, and the older generation, who did not find any interest in it, did not really have a strong feeling against it — although there was a rather strong feeling among some of the older people about the uncertainty principle. This is the one thing that I heard criticized, Heisenberg’s uncertainty principle, that they didn’t like. As a matter of fact, even Professor Einstein to the end of his days was very strongly opposed to the idea that the uncertainty principle had a central role in physics. But there was never the public clamor about quantum mechanics that there had been about relativity. Its usefulness is so tremendous in physics, chemistry, metallurgy and so on, that it would be almost stupid for anybody to oppose it. One of the things we’ve never been able to understand is why Professor Einstein opposed it so long and so vigorously. He certainly was wrong, if you can judge on any basis of other people’s evaluation. But on the other hand, you can’t dismiss anything that Einstein says that easily. However, there have been experiments recently that showed that some of Einstein’s ideas on this are certainly wrong, and I think it’ll be shown that quantum mechanics comes out on top. The opposition of Einstein, Schrodinger, de Broglie, will fall by the wayside.
The philosophers generally say it’s a question of completeness. Einstein’s perpetual feeling was that too many physicists were beginning to think of quantum mechanics as the final step on the rung of the ladder of understanding Nature. But for him, QM was always an incomplete way station, a temporary means of getting behind the problem of determined causes.
I would respond to that by saying that every aspect of physics is temporary and a way station. There’s nothing complete about any aspect of physics, and quantum mechanics is not subject to criticism because it shares the same limitations as all science does. I don’t think there’s anything complete about any branch of science, relativity or electrodynamics or anything else. Nature is more complicated than our theories. I think, as long as quantum mechanics is extremely useful for its purposes, that’s enough. The ultimate theory is something that I don’t think any of us will ever see, or anybody alive. I think that’s a dream that is a little bit too presumptuous, in my opinion. Not that we shouldn’t strive in that direction, but the idea that you’re going to achieve it in a finite time — and certainly, the idea that you would discard something because it doesn’t fit into a nice unified view that somebody has, is the wrong way to approach science. For instance, the kinetic theory of gases is extremely useful, and has been for a long time, but there are fallacies and inconsistencies and incompletenesses in kinetic theory that everybody learns early in the game. But that doesn’t mean you condemn it. The same is true of the mechanical view of Nature. That is long in the discard, and yet it served a great purpose at the time, and that’s all it should do. If any theory is so good that it’s never modified, why, you can be pretty sure it’s headed for oblivion. That’s my view on the development of physics.
You do assume then an indefinite linear progress in man’s ability to come to learn, to know Nature better?
I don’t know about the word “linear.”
A lot of people are talking now about the limits to growth, even in intellectual affairs.
Well, I think there are limits. But you’ve got to bring in the time scale on that, because certainly striving and trying to understand more about Nature and to have a deeper understanding of it has got to be one of the basic urges of a scientist, or else it becomes a very shallow business. Now, whether it [knowledge] saturates at some time, and you say, “Well, I no longer can find anything more about Nature” — I shudder to think about that, because I think if that happens, it will also be coincident with the collapse of our economic system and its inability to support science. We have examples of achievements in the ancient world which we glorify, and books which are no longer edited or extended. I hope that our physics doesn’t reach that stage for an indefinite period. I think that the advances that are made in the future, both on the experimental side and the theoretical side, are going to be more difficult. What was done in the twenties was a golden age of discoveries by simple means — almost shaking the tree and letting the apples come off, in some cases. That era is probably going to be behind us for a long time. But we’ll certainly make progress, and progress implies abandoning or seriously modifying earlier theories that were considered sacrosanct. That’s one of the things that worries me about the attitude of present day physicists: there’s too defensive an attitude toward certain past achievements. This showed up when the parity business came in.
There were some very distinguished physicists who were horrified with this business. They got over it, but the fact that they had that attitude shows that they were looking at physics as a kind of finished cathedral. If it ever reaches that stage, why, young people will go elsewhere for their careers. No question about it. Well, that’s about all I have to say on that subject. Now, you ask here about “the Copenhagen interpretation.” Of course, this term is one that I never heard until recent years. When we first learned about quantum mechanics at the University of Chicago, principally from Carl Eckart and also from Frank Hoyt, what they taught us was certainly the Copenhagen interpretation, but it was never called that. Everybody went to Copenhagen to study, and that was a fruitful place to go, certainly, as were Munich and Gottingen and Cambridge, but I never heard it called the Copenhagen interpretation. It’s really the Bohr-Heisenberg interpretation, and add to that the names of many other distinguished people. I think it is the interpretation of quantum mechanics that we all learned in our student days, and we’ve all thought of as correct since. There have been serious critics of it, but I for one have never been able to see that the criticisms amounted to a great deal. The criticisms have been made by some very important and distinguished physicists, but it doesn’t seem to me that the quantum mechanics as used and as developed has been seriously modified because of the criticisms. I don’t pretend to know the details of this business, but all this hidden variable business and everything else — what if you find a hidden variable? Then you’ve got to go one step below that to get reality. There’s no stopping, if you insist on a bedrock somewhere. It can’t be the first hidden variable or the second or third, it has to go on and on and on. I’ve never found anything that bothered me philosophically about quantum mechanics or the uncertainty principle or the probability description or anything else. It seems a very good way to explain complex phenomena and important phenomena, and I think that’s enough for a theory. Now, there are other people who have different views, but I certainly don’t get excited about them.
The renormalization process and the psi function and most of all, it seems to me, the principle of complementarity is associated with the Copenhagen interpretation, as I understand it. Is the relationship between Heisenberg’s uncertainty principle or indeterminacy principle, and Bohr’s principle of complementary, the nexus?
Well, the principle of complementarity is, in a sense, an extension of the uncertainty principle, a more general formulation of it. I think that’s the essence of what we now call the Copenhagen interpretation. But I would just call it quantum mechanics. I don’t think any other interpretation has proven itself or been accepted by the workers in the field, to any degree that makes it a serious rival. I would personally leave out the word “Copenhagen” — not that I have any objection to the city or the laboratory, but it seems to me that it’s intruded itself into the discussion in recent years in a way that narrows — the implication is that everything came out of Copenhagen. I don’t think that’s true. Take Dirac’s great work, which is probably the supreme achievement in the business. It doesn’t have any relationship to Copenhagen. But certainly Bohr was a great leader in stimulating young people all during his lifetime, and I think he deserves the greatest single credit for the business — perhaps most of all because he did not cling to his original theory, but demanded of his young people that they find something better. I think that is one of the greatest things in the whole history of science. Here’s a man who won the Nobel Prize for his 1913 theory, and who immediately began to criticize it because of its limitations. He encouraged every young person who worked with him to find something better. In that sense, the quantum mechanics of Heisenberg and the others is properly called the Copenhagen interpretation. But I think that name is limiting it too much. It will take a lot more than anything we’ve seen so far to upset it, in my opinion. The efforts of various people are interesting little journeys into the philosophy of science, but they haven’t really touched the essence of the method. And I don’t think they will. I think when it’s attacked by a man like Einstein, and survives, it’s pretty well going to last a while longer. That’s about all I have to say on that. Now, let’s see, “natural versus artificial subtleties…”
We’ve been talking around about this, but it’s something that I hardly know how to say. “Natural versus artificial subtleties in experimental investigations” — sometimes we create our own superdistinctions [conceptions], that get in the way of recognizing what the apparatus is telling us, or what an experiment is telling us; and sometimes it’s just the complexity of nature that makes it seem perverse [to our perceptions]. Because of your long experience with some of the major experiments of 20th century physics, I wondered if you’d like to talk about this business of the subtle differences between what Nature presents, and what our minds tend to perceive.
Well, I’ll make a few comments. I’m not sure I get the distinction quite the way you make it, but in the first place — any experiment is usually designed to test some specific point. I don’t know of anybody who ever built an experiment just to survey the waterfront in physics. There are exceptions to this. For example, take the case of the Braggs’ work on crystal diffraction with the crystal spectrometer, which is one of the really great achievements. I think if you investigated the early papers, and what Bragg said, that at first their diffraction experiments were designed to tell something about the nature of X-rays. The elder Bragg had a corpuscular theory of X-rays that had some precursors to what we later called the Compton effect, but it was not the same thing. But once they were convinced that the nature of X-rays was known, they then switched, and under the younger Bragg, evolved a long program, a brilliant program of using it as a tool. I think in the case of most physicists, that’s the stage where they begin to lose interest in the subject. It becomes chemistry, or it becomes mineral logy or metallurgy, not that those aren’t equally important.
I’m not one who looks down on any other field. I think the achievement of W. L. Bragg in crystal analysis is tremendous. I think it’s one of the great achievements of physics. But I think there was a subtle change in their attitude, when they realized what the nature of the diffraction process was, then switched to its use as a tool. And I think most physicists, in planning an experiment at the outset, are interested in this first aspect of things: what is the nature of the beast? Another example you can take is one of the early experiments with the cyclotron at Berkeley, that Louis Alvarez and Bloch made, to measure the magnetic moment of the neutron. Now, the magnetic moment of the neutron had been predicted, but whether it was believed or not, or whether they expected to get the simple numerical value or not, they made a very great contribution to physics in measuring the magnetic moment of the neutron, in that early experiment. Later on, their value was greatly refined, and the neutron as a particle having magnetic properties was adapted for many experiments in physics. But I think the key experiment in the whole business, was the Bloch-Alvarez experiment that demonstrated what the number was, that it was not a simple multiple of an elementary magnetic moment, things of that kind. They set up that experiment definitely to measure a quantity. Once the neutron-beam technique had been developed, the chopper method and so on, then it was used everywhere. People in Idaho used it for years to make a lot of very important, very interesting experiments. But the crucial experiment on the thing from my point of view was that first one that came along and demonstrated its usefulness. Of course, if the physics had stopped, if neutron physics had stopped with the Alvarez-Bloch experiment, it wouldn’t have been nearly as important as it is today. But that was a thing that helped make it a central item in physics. And you can take that same view in many other experiments.
Michelson-Morley, for instance, the difference between 1881 and then 1887?
Yes. Well, of course, that was a matter of getting a result that you couldn’t deny. See, the original 1881 experiment of Professor Michelson’s that he performed at Potsdam did not detect the ether drift that he very much hoped to find. However, the uncertainty was such that it could be interpreted as being either a null effect or an experiment that was a failure. Although Michelson announced it as proving that the ether drift didn’t exist, the majority of physicists at that time didn’t believe him. They thought, well, if you do it more carefully you’ll find it. And the great advance made by the Cleveland experiment in 1887 was that their observed fringe shift was only 1/40th what the theory predicted, whereas in Potsdam it was 1/2 what the theory predicted. The difference between being 40 points off and 2 points off is a big difference, so nobody could deny the validity of the Michelson-Morley experiment, although they could deny the validity of the Potsdam experiment. As you know, it took years and years of trying and discussing and arguing about the Michelson-Morley experiment, and it was the thing that set the climate of opinion, if you will, that finally led to relativity. Whether it was a direct stimulus to Poincare or Einstein or Lorentz or Larmor or anybody else, is not the point. The point is, it set the climate of opinion, and it became generally believed that experiments of its kind were not going to reveal the ether. Whether people knew the details of the experiment or even its name is not important. It was generally understood that that experiment had put the kibash on the century-long hunt for the ether.
But then there was the Fizeau water-drag, ether-drag experiment, which seemed to be a contradiction too.
Well, that experiment was extremely important, but at first, the experiment by Fizeau showed that the velocity of light was altered only by about a half of the speed of the water through which it was propagating. And that result could be interpreted by several theories. There were several competing theories, all of which were consistent with a result about a half. As a matter of fact, the great J. J. Thompson published a theory which is rather unknown — that no matter what the medium would be, according to Maxwell’s electromagnetic theory, the drag should be one-half. And that one-half was not inconsistent with Fizeau’s result. There was a theory by Hertz that predicted the drag should be 100 percent. That was pretty well ruled out from the outset, but nevertheless it was not discarded. The theory of Fresnel as elaborated by Lorentz predicted a precise number, related to the index for refraction. So Michelson and Morley, here in Cleveland, as a preliminary to performing this other experiment, made a very precise measurement of the Fresnel drag. And they found a value that excluded J. J. Thompson’s 50 percent and Hertz’s 100 percent and several other theories, and was in very close agreement with the Fresnel theory, the Lorentz electron theory, and also later with the special theory of relativity. When I talked to Professor Einstein, I found he was extremely interested in these experiments. He not only knew about the repetition by Michelson-Morley, of Fizeau’s experiment, but he also was very well acquainted with the Zeeman experiment of 1915, where they made an even more precise determination, and confirmed an additional term due to dispersion that Lorentz had introduced into the theory.
I think one of the reasons that Einstein was so taken with the Fizeau experiment was that it gave a number. You see, these null experiments, important as they are, are always subject to the question: well, was there something missing in the experiment that didn’t reveal it? Michelson to the end of his days was worried about this point. But when you have a number, and the Fizeau experiment had a number. Then the other number that Einstein was so interested in was the aberration constant — those not only would be stimuli to a theory, but they would check against a theory in a way that a null experiment might not. I know when I first visited Einstein, I was rather surprised that he was as much interested in the Fizeau experiment and the Michelson-Morley repetition of it as he was in what we all had considered the great Michelson-Morley experiment. However, he was interested in that too, I can assure you. Some of the statements made that he didn’t even know about it, wasn’t influenced by it, seem to me rather strange. They imply a continuous one-by-one step through to a theory that certainly doesn’t occur in the evolution of science. I’ve expressed myself on that in several publications. I’m sure that the climate of opinion, I use that term again, was set as much by the Michelson-Morley experiment as any other experiment, and for that reason it was important. It certainly was tremendously important in everything Lorentz did, and it was well known to Poincare and Larmor and physicists generally. I’m sure that Einstein knew about it, although he probably didn’t know the details of the experiment. And you wouldn’t expect a theorist to know the details of an experiment.
You mentioned Poincare and Larmor here. Last evening, you said something about a regret that you had not asked Einstein directly about Poincare’s influence or receptiveness.
Well, when I talked to Professor Einstein, he repeatedly brought up the name of H. A. Lorentz. He had greatest admiration and love and respect for him. He always called him — pronounced Lawrence — “the Great Lorentz.” I was confused at first as to whom he meant. There was no question that Professor Einstein had the highest regard for Lorentz and his work, and since then, I’ve regretted I didn’t ask him what he thought about Poincare. Not that I had any specific axe to grind, but he didn’t mention him, and I didn’t bring it up. I’ve since learned from Helen Dukas that there was very little correspondence between them, and that’s not surprising because Poincare was much older. He died rather soon after Einstein became a prominent figure. It’s not superfluous to point out that in those days, the relationships between France and Germany were not good. It was just before the Great War, and the Franco-Prussian war was still remembered. There were tensions there that you can’t ignore. And then of course, Poincare was a cousin I believe of the President of France, and Einstein was a rather unknown worker — it isn’t surprising they weren’t close friends. But there’s nothing more to it than that. What Poincare contributed to the theory of relativity is well known and published. I don’t think there’s any point in arguing about who deserves what credit. There’s plenty of credit for everybody.
Is there enough credit for Joseph Larmor too?
I think any credit you give Larmor is much less, but nevertheless he was one of the people who wrote extensively on the subject, and he did some things that are not trivial. For instance, at first, before the Lorentz transformation in its present form was available, there were several approximations that can be made to the Lorentz transformation. Lorentz himself showed that ether drift experiments to the first power V/C were ruled out by theory, and then he later on showed they were ruled out to the second power, (V/C)2 and if I’m not mistaken, Larmor showed that they were ruled out to the third power (V/C)3. But of course, the simple algebra of the Lorentz transformation, shows that they’re ruled out to all powers. So we don’t think much of Larmor’s achievement at the present time, but I think it must have made an impression then. I think you’d have to put Larmor’s contribution considerably down the scale. However, he did not oppose the general development, as did Oliver Lodge. I think Lodge, I would be inclined to say, was not in this stream of development. He did an experiment that was interesting at the time (1892), but he took a hostile attitude toward the stream of development (after ca. 1910), and I think for that reason you’ve got to give him a much lower place. I don’t think Larmor was one of the big men, but I think he deserves some credit. The greatest credit of course is Einstein’s, there’s no question about that, but I don’t believe that the other men should be forgotten, especially Lorentz and Poincare.
There’s been a recent doctoral dissertation on Larmor [by Barbara Doran] that in essence says he deserves at least coequal credit for the electrodynamic definition of mass, in the period 1894-1904. I think that this electrodynamic definition of mass is pretty central to the problem of ether, electrons and atoms, as conceived around 1900.
Well, I really don’t know about this work. There of course are a lot of people who tackled that problem of where the electron gets its mass. J. J. Thompson did, for example.
Larmor of course was in direct symbiotic relationship with him.
Sure. I really don’t know enough about his specific contribution to this work to comment. I’ve never been terribly concerned with that personally. I know the problem you’re talking about, but of course from the relativity point of view, the relationship comes out very simply. On the other hand, all the precursors that led up to it are not to be dismissed, just because the final statement is more elegant.
Could you say something about the changing interpretations of the Compton effect?
Well, I don’t know exactly what you mean by that. When the Compton effect was first discovered in 1922-23, it certainly required radiation to have corpuscular properties as well as wave properties. And it was such a clean interaction between the electron and the quantum or the photon, that it demanded both properties. You couldn’t take sides on wave or corpuscle after that. It also showed that whatever theory explained it had to be a unified theory that had both wave and corpuscular properties. For that reason, the older Bohr theory and things like that were not accurate. So it was one stimulus, among others, to the development of quantum mechanics. Now, the real picture of the quantum process was given by Dirac in his relativistic theory. I don’t think there’s been too much change in viewpoint on that since. For of the many tremendously high energy actions in accelerators and astrophysical processes, the Compton scattering process is a basic interaction, as developed in its final form by Dirac, Wentzel and others — I don’t think that has changed very much. It is one of the basic interactions. Now, its interpretation is enriched every time there’s a new development of quantum electrodynamics, but — I think the real change in thinking was introduced way back in 1923 by Compton, and then by Dirac, a few years later. Since that time, it’s been pretty generally viewed in the same light by everybody.
Dirac in 1929-30?
Yes. Whatever the dates were for his great papers, using his relativistic quantum mechanics to derive the Klein-Nishina formula, that we mentioned in connection with Millikan’s cosmic ray work and so on, that was a direct result of Dirac’s theory. The earlier non-relativistic theory, before Dirac, was not adequate to explain quantitative features of the scattering — neither the angular dependence of the differential scattering cross section nor the total scattering cross section were correctly predicted by the earlier forms of quantum mechanics. Compton himself devised a theory which was pretty close, but not good enough, but the Klein-Nishina version was completely confirmed by experiment, including a prediction of a small non-polarized component that my good friend Eric Rodgers demonstrated as his doctor’s thesis under Compton in the middle 1930’s. But since that time, I don’t think there’s been any question about the Compton interaction or its theoretical explanation. There’s always the possibility that something at extremely high energies will show up, something that needs to be considered. But so far, quantum electrodynamics and everything connected with it has survived all these tests pretty royally. I don’t really have very much to say about the Richardson-Dushman equations. I’m well aware of their importance, but I’ve not looked into them in detail. I did see Richardson’s apparatus in the Science Museum at South Kensington this summer.
It was very interesting to see the simple but elegant apparatus that he used to make his measurements. But I really have nothing to say on that. My principal interest in Richardson was that he was Arthur Compton’s research advisor for the first semester when Arthur was a graduate student at Princeton in 1913, and I’m sure that much of the inspiration that Compton received to go on and do his early research work came from Richardson. Furthermore, when Richardson went back to England he left Compton a wonderful X-ray laboratory to work with at Princeton, which was really a bonanza for a young man just starting out. And of course Compton always felt very warmly towards Richardson, and Richardson was a great admirer of Compton. They were great friends. It is an interesting thing, that they were both so completely trained and educated in classical electrodynamics that they were reluctant to bring in quantum explanations for either of their experiments until they were forced to. For instance, Compton carried out many very detailed and impressive calculations, using the classical electrodynamics, to try to explain his scattering results, but they all failed in one way or another; then he switched to the quantum explanation, which of course is the correct one.
That’s why Dushman’s name is connected with Richardson’s too, because he was a colleague of Irving Langmuir’s and made the quantum translation of the Richardson thermionics law.
Yes. I’m aware in general of what Dushman did. As a matter of fact, years ago we had Dushman here as a visitor for several summers. We had a General Electric sponsored course for several years, for high school physics teachers; many of the star people from Schenectady came, including Dushman and others, and Dushman was always full of reminiscences about physics. He was an enthusiast. But I never heard him talk about his own specific contributions, but I’ve read about them of course. But I really haven’t had occasion to study them. I’m interested in what you have to say, but I have nothing to contribute to your understanding of it. Next, I see here: “being chairman of the physics department for two decades.” I will say a few things about when I was chairman. Part of the time was before the war, the remaining time was after the war. The two responsibilities were vastly different. Before the war, physics was a small fraternity. You had a few very good colleagues and you had a few excellent students. You helped them get started in professional careers. You provided as much support for their research and study as you could. And that was the main thing that one hoped to do in physics before the war. It was essentially the method that Michelson had started here from the outset.
The only change that was on the horizon before the war was the Ernest Lawrence method at Berkeley, but that was not understood very well at the time; it wasn’t realized that even with his early cyclotrons, he was developing the team method. Only after the war when the full flowering of the Berkeley Radiation Laboratory was visible to everybody did the change that Ernest Lawrence had introduced into running physics departments become evident. Of course, Ernest Lawrence never was burdened with being a department chairman, because Professor Raymond T. Birge supported him in every detail all the time he was there. I think Birge’s support of Lawrence is something that is very important. But after the war, and the fame and publicity that physicists earned for wartime developments, then almost every laboratory expanded and had a bigger budget and bigger staff and bigger ideas. That went right on till recent times, when the budget cuts started to make us evaluate things more carefully. I gave up being department chairman after quite a long time. I think I was one of the first department chairmen who gave up at an early age. Most of them — the usual thing was to keep on until you retired or were senile. I decided that I had done all that I knew how to do to help young people, and I felt somebody else should come in with a different point of view and one that had more completely… (off tape)
On the other side, before we flipped the tape over, you were talking about chairing the physics department over two decades, roughly split by World War II, and were just about to say something with regard to your 50th birthday and decision to step down as chairman.
Well, it’s very simple. I decided that I had done what I was able to do as chairman. It was a very demanding job, and I wanted more time to work at physics. I thought a new and younger person would carry on more effectively than I could at that time. And so I was delighted when we were able to have Fred Reines come here as our leader for a very wonderful period of development and enthusiasm and achievement. Frederick Reines.
You said something yesterday about your actually having been groomed for the chairmanship by Miller even before he stepped down, right after you came back from Chicago.
Well, when I came back from the University of Chicago in 1936, both Dr. Miller and President Wickendon told me that I should begin to plan for the physics department and for the idea of being chairman. So I was effectively chairman from ‘36 to ‘40, but with the closest collaboration of Professor Miller, and I continued to learn a great deal from him. In other words, I was fully as much occupied in those four years as I was in the following 18 as official chairman.
What was the changed nature of the Department, the size? In 1936 how big was the professional staff of the department, and how big was it in 1958?
I don’t have the exact figures in mind, but there was a very major growth. I suppose expansion four to one or something of that kind. I really don’t have those figures in mind, but in common with all departments we expanded a great deal. We introduced work in theory. We introduced quantum mechanics as a vital part, a central part of the operation, whereas before the war, we’d been kind of on the periphery with optics and thermodynamics and things of that kind. So you can — I could look up the numbers for you, but it would take me a little while. It was a major change.
A four-to-one expansion?
I remember one conversation that I had with Dr. Zay Jeffries, who was a Case trustee when I was first asked to look after physics; he was one of the great metallurgists of our era. He would invite me down to the Union Club about once a month to see how I was thinking, and he told me just before the war started that we could all expect the growth in physics during World War II to be comparable to the growth in chemistry in World War I. Jeffries was the first person that I ever heard make that statement. People make it now, but he saw it before anybody else that I talked to. He was a metallurgist, but he was also a great scientist in other areas, including physics. He was very very knowledgeable about physics. But that’s what happened, and has happened everywhere. One of the problems, I think, in present day physics is that we have now a majority of our people in physics who grew up in the postwar era; they did not realize the sudden expansion was abnormal. We have a need for consolidation and deepening of our roots, not just growth per se. That was clear to people who had roots in both pre-war and post-war physics. There’s something more to physics than just a bigger budget every year. And I think this is something we’re going to have to learn more as time goes on, if physics is going to really grow in quality, as against size.
Was there almost an exact parallel four-to-one expansion in budgetary size over those two decades?
Oh, I think it was more than that. The budget was always increased more rapidly than the staff, because not only were there more members of the staff, here and elsewhere, but the kinds of experiments that were done became increasingly complicated and sophisticated, and above all expensive. So I’d say if there was a four-to-one increase in staff, there was a 20 to 1 increase in budget probably, although those are just numbers off the top of my head. Suddenly physics became big research and big science, and leaders like Lawrence knew what to do with it. There were other leaders who didn’t know what to do with it; they have caused some of the problems we have today.
Any special institutions you have in mind?
No. No. We all are guilty of expanding in any direction where there seemed to be money available, without worrying whether there really was quality physics there. That’s got to stop. No question about it, if we’re going to be physicists, we’ve got to be physicists and not contractors. But that’s as far as I want to go on that.
With regard to the status of physics in the academic setting, was there a noticeable change in your view of the history of Case School of Applied Science, to Case Institute of Technology, to Case Western Reserve University?
Well, I don’t think the change had anything to do with the change in the name of the institution. It was a world-wide and nationwide change. But there was a very definite deepening of the understanding of what physics could do, during those periods. I’ll give you just one example of the pre-war business. One of our distinguished graduates of this department was John T. Grebe, who went to the Dow Chemical Company in the middle twenties, with a bachelor of science degree in physics; he was helped into that job by Professor Miller. But all the years that Grebe was in Midland, he was called a physical chemist. They wouldn’t have the name “physicist” on the roles of the Dow Chemical Company, because it was dominated by chemists, and they didn’t want physicists to get their heads above water. After the war, this was reversed almost too much. There were people called physicist, who really weren’t physicists, because the name was popular. There was a dramatic change in the acceptance of physicists. Before the war you were always asked, “Now, what does a physicist do? What is a physicist?” You never hear that question asked anymore. So I would say, in understanding of what physics might accomplish for society and the country and industry and everybody else, there was a dramatic change in the whole business. And that was largely due to the achievements of physicists during the war.
How did you answer the question to the layman before the war, “What do physicists do?”
It depended on who asked the question. You’ve heard the answer that Karl Darrow once gave to that? He came back from France to England, and coming through customs, he was asked what his profession was, and he said he was a physicist. And the man at the immigration stool wanted a little more detail, so Darrow told what physicists did, and when he got through the Englishman said, “Oh, yes, over here we call them chemists.” Well, that’s a thing of the past. We don’t have to explain what physicists do now, although in common with every profession there are misinterpretations of what physicists do, but the same is true of law, medicine and other occupations.
But that fundamental 19th century distinction, that chemists study the ultimate nature of matter and physicists study matter in motion, that kind of distinction…?
I think that’s all past. One of the great things that quantum mechanics has done is to unify physics and chemistry and to some degree metallurgy and other materials sciences. I don’t think that old distinction means anything. I don’t think it meant anything at the time, but it was one of the things that people said. Now, let me see, what we have before us here.
Well, the next item on the agenda we sort of touched on most of the day yesterday. I wanted to ask specifically about your book, and its inception, your feeling of the need for it, and the length of time of the gestation period and so on. Could you tell us something about how Atomic and Nuclear Physics got written and published?
Well, after the war, I found myself teaching courses here in those subjects, as did many other people. It’s always been my policy to prepare classes from as basic material as possible, and not too much from other books, although you have to do that too. So during the summers that I was at Berkeley and visiting various laboratories all over the world, I naturally came into close contact with actual experiments and the physicists involved, and I included as much of this material as I could in my lecture notes. I also realized that what was needed was a course here at Case that did not make such a sharp distinction between atomic and nuclear physics. So I called my courses “atomic and nuclear physics.” For a few years this was adopted elsewhere, although it’s become so specialized recently that we’ve broken away again. Well, to make the story short, I rewrote my lecture notes for a number of years. Then the MacMillan Company came to me and asked to publish a book, so I worked on it some more, and it was published. It went through two editions and was a rather well used text, but it’s now out of print.
I’ve considered rewriting it, but that’s an awful job, and I don’t know whether I want to tackle rewriting it, or whether there’s a need for it any more. I think there was a need for the book when I wrote it, or I wouldn’t have worked on it, but I think now there are dozens of books that you can get, there’s no point in just… Let me give a specific example of the things I tried to include in the book. I of course knew Dr. Polykarp Kusch very well because he had been a student at Case, and I was very much interested in the work at the laboratory at Columbia University, developed by Professor I. I. Rabi, where Professors Kusch and Lamb and others had made such notable discoveries with the molecular beam method. So I included a great deal of material that was not present in other books of this kind in my textbook, and I think it was an important addition to the usual treatment of atomic systems. I of course had available to me the original material from Kusch and his colleagues, and I considered that a very interesting thing to include, and I think a valuable thing. Another feature that I am very proud of is that in my first edition I discussed the Reines-Cohen experiment on the free neutrino, work that they had done at Hanford on this subject.
The same Frederick Reines?
Yes, the same one. I was strongly advised by certain men whom I admired to omit it. But I felt it was correct and I left it in. I had written to Fred Reines and he had told me enough about the experiment that I was sure they were right; later on they did more definitive experiments at Savanna River which proved their point without question. But I take some pride in the fact that I included their first work in my first edition.
The point had to do with plutonium or cross-sections?
No, no, no. It was an experiment that showed the interaction of the free anti-neutrino with the proton. And this is the experiment that is properly considered the discovery of the free neutrino. Of course, the neutrino was introduced by Pauli many years before as an essential theoretical element. Pauli introduced it first, and Fermi used it in his beta decay theory, so they both deserve much credit. But until Reines and Cohen demonstrated that a free neutrino would interact with another particle, there was always the question of whether it really existed or not. Although, as I believe I told you before, ever since I heard Carl Eckart lecture on the Fermi theory of beta decay at Chicago in the early thirties, I had no further doubts about the neutrino. It was just as real to me as the electron. I think that’s true of most physicists. Well, that’s the main thing I have to say about the book. I would say, if anybody wants to write a book, they have a big job on their hands. But I do think, it’s important for books to be written as close to the primary source material as possible. There are too many books that are simply library studies. Things of that kind may have their points but they don’t excite interest very much. Where are we now?
Well, unless you would like to talk about specific people here — Lawrence, Oppenheimer, Vannevar Bush, Harold Urey, Conant, Compton, Edison, or others — or want to say something more about big science, team research, government-industry-academic consortium — we could go on to the question of major figures, people, in the development of solutions to the submarine problem.
Yes, let’s talk about that a little. I worked four years in this field. What we found in the United States, when the submarines began sinking ships along our coast, was that there was very little to combat them. Now, it’s true, the Naval Research Laboratory worked on a system between the two wars, but they had extremely small financial backing. They did a creditable job, but it was not adequate. The British, on the other hand, had a working system when the war started, their so-called “ASDIC.”
Do you know what that acronym stanch for? Do you remember?
Anti-Submarine — I’ll think about it. It has some meaning… I forget.
Was there a British physicist connected with ASDIC’s development or design before 1939?
Well, the British system, to the best of my knowledge, and I visited England in the war and learned about this, was developed by their laboratory at the Isle of Portland on the English Channel. It was developed largely by groups that were in the civil service in England. The British had a distinguished advisory committee after World War I, including Rutherford and the Braggs and people like that, but I don’t think they did much in the development of the ASDIC system, other than to approve the budget and things like that. So I think the designers were people who were in the civil service. The man I would cite as very important for the British was a man named Jock Anderson. Another one was a physicist named Vigereaux, and there were others. People there are rather unknown to the published literature. These people were very good scientists, very good engineers, very good development people, and above all else they were well aware of what the British Navy needed and what was possible, operations-wise, in the ocean. They had a setup which worked very well. We plunged into the problem on a crash basis. The greatest contribution in my judgment was made by the Bell Telephone Laboratories. I noticed in the last issue of the Acoustical Society Journal the death notice of Mr. W. H. Martin. Well, Martin was head of the large group in the Bell Telephone Laboratories that took over the development of antisubmarine sonar and anti-submarine acoustical bombs or torpedoes. For four years during the war, I worked very closely in the OSRD with Martin’s group in the Bell Laboratories, and I would say that they made the greatest single contribution on the technical side of any industrial, government or laboratory group in the United States.
How big was that group?
Well, the group in the Bell Telephone Laboratories was not a fixed group of individuals, and I was very much impressed with the way the Bell Laboratories would attack these problems. If some specific problem came up, like a better way to make the crystal array and a transducer, they would call in from the staff of the Bell Telephone Laboratories half a dozen people who should be knowledgeable in that field, (and they might revise this group two or three times) and they would attack the problem and come up with a solution almost without exception in a short time. Then the group would be demobilized. They didn’t have any fixed organizational structure. This was greatly in contrast to the government laboratories, where a man started on a problem and all during the war, he’d keep working on the same problem. And if a government lab started a new problem, they’d go out and hire new people who took years to learn. I’m not here to advocate the Bell Telephone Laboratories as the greatest organization on earth, but I was tremendously impressed with the way they used their men to the maximum of their ability, and always put the men who knew the most about a job on it. I think if you examine the record of the time-scale involved, from the day they were asked to develop a new sonar set until they were installed on destroyers, it’s a remarkable achievement in the history of development work and research.
You’re talking about a time-scale of one and a half to two years, right?
Or less. And I think Mr. W. K. Martin, who was practically unknown to the physics fraternity and the engineering fraternity, made a great contribution in his leadership. He was a man of unusual abilities. After he retired from the Bell Laboratories and for another five years, he was director of research for the Army in Washington. Then he retired from that, and now he’s gone at age 81. Martin was not an easy man to work with. He was a driver. He wouldn’t tolerate delays or anything else. But that’s what it took. For the underwater sound reference laboratories that I was director of during the war, in Orlando, Florida and Mountain Lakes, New Jersey, I insisted, as a condition of doing the job, that we have a contract with the Bell Telephone Laboratories for continually improving the equipment, and Martin was the man who saw to it that we always got the latest thing that they had for testing. It was a remarkable relationship. Of course behind us, behind all of us were E. H. Colpitts and Frank Jewett, who wanted the same thing.
The word “reference” in the name of those underwater sound reference laboratories, does that have to do with setting physical standards for the calibration and operation of the equipment itself?
Yes. I suppose an alternative name would have been underwater sound standardization laboratories, or underwater sound testing laboratories. A large part of what we did in wartime was actually testing. We did establish standards, or adopt standards that had already been agreed to in committee. You see, you had to have a sound pressure level to measure things against. But the main thing we did during the war was just test new forms of sonar to see if they would work, and how well they would work. The standardization feature was always present, but it was a minor business during the war, because it was so urgent to get equipment at sea. Now, since the war the Orlando Lab continues under the Navy, and I’m sure standardization per se is a much bigger factor in what they do than it ever was with us. But there were standards that had been adopted before the war for acoustical measurements, largely Bell Laboratories standards, and we used them, but we spent little time on that. We did however do one thing. That was a remarkable achievement of my colleague, Professor (L.L.) Foldy. He studied the data, extended it, and really showed the power of the so-called reciprocity method of standardization. Foldy found that there was discrepancy in the thermophone standard developed by the Bell Laboratories which had been considered perfect for a number of years.
It was really a very brilliant study that Foldy made to show this discrepancy. (He is the fellow in the next office here at CWRU). There was a fair amount of reluctance to accept Foldy’s findings in this country, but in 1943 when I went to England, I found that the British, who already had a copy of Foldy’s report, had checked his method thoroughly and found it correct. So when I came back to New York, I was very pleased indeed to announce that Foldy’s reciprocity calculations were the correct ones, and from then on they were adopted by everybody. In this country, I would say that there was very definitely a big team effort on sonar. Professor John T. Tate, University of Minnesota, was the head of the division that was charged with this responsibility, and he was ably supported by Dr. Edwin H. Colpitts, retired vice president of the Bell Telephone Laboratories. But there were also major laboratories under Tate at Harvard, MIT, New London, Mineola, San Diego, and elsewhere that contributed to this problem. Of course great support by industry, especially the telephone company, came in developing this gear, and also important contributions were made by the Submarine Signal Company, the Sangamore Electric Company, the Brush Development Company and others. You see, there was no new scientific principle that could be exploited for anti-submarine work, as had been the case in both radar and the atomic energy business. So the result was, there was no spectacular Nobel Prize winner or anybody like that to suddenly emerge. It was a very, very difficult problem, because the ocean is such a difficult medium to send any kind of signal through. We had to just take advantage of any little improvement you could think of, to even make a system work at all.
May I say something about personal experience as an ASW officer on a destroyer during the Korean War. I found that my sonar operators could be trusted if they had a very sensitive ear to Doppler effects, and the whole Doppler principle, in our sonar gear anyway, seemed to be more important than the three or four different kinds of very fancy gadgets we had to work with. Were you concerned very much with Doppler principles and with the human equation here, in hearing, and operators learning to distinguish between whales and ships?
The Doppler effect was absolutely essential to understand what the sonar signals meant. This was understood early in the war, and the British of course had known this for a long time. Without the Doppler effect, you just had a reverberation coming back from the turbulence of the sea, the bottom of the sea, the surface of the sea; it was incomprehensible. But the Doppler effect would change the pitch, and the echo would stand out spectacularly. Good sonar operators observed this as the prime thing. The signals that you could observe by ear with the Doppler effect were absolutely impossible to record on a meter. One of the false starts that we made in this country was to decide that all this Doppler business could be put on a meter. But we found it impossible to do that, because the ear could go down into the background noise as much as ten decibels, and pick out Doppler effects that were meaningful in terms of submarines, as against whales or rocks or something of that kind. No electronic system available at least during the war could even approximate this. So we over-gadgetized our sonar considerably at the outset. However, the New London laboratory realized this problem rather early in the war. Because of their close association with the submarine skipper at the Navy there at New London, they redesigned our sonar and greatly simplified it. By the end of the war, we had a very good set. But there was a time when it was so complicated that sonar operators could hardly operate the thing. That’s one of the features that we always noticed about the British systems. They were always extremely simple, and sometimes they’d be viewed with contempt by our engineers. But when you went to sea and saw how simple it had to be to work, you realized that they designed from long experience in the Navy, and not just in a development laboratory. The man at New London who did a great deal to simplify the overall design is a man now gone, J. W. Horton. He was one of the leading lights at New London in the overall supervision of this.
Was he a physicist?
No, he’d come from the department of electrical engineering at MIT. I think he was primarily an acoustical engineer, an electronics engineer. He was a civilian. He had had experience as a very young man with rudimentary sonar in World War I, and so he had a head start on the business. I could name other specific individuals who were important. I think Dr. W. V. Houston was very important in coordinating the work that led to the acoustic torpedo; that was decisive in defeating the submarine. But there again, the technical backing of Houston’s work was primarily Bell Telephone Laboratories.
Do you know the military designation, would that be the Mark-27 torpedo?
Mark-24, I think. They called it “Fido” first, then Mark-24, and later versions; I haven’t kept track of the business for years. Lyman Spitzer was very important in his study of the temperature gradients, and correlating the work of Woods Hole and Scripps, and making it available to the Navy. Carl Eckart was a very important man in San Diego, in supervising the research and development work there. Of course, G. P. Harnwell was important as the director. Frederick Hunt at Harvard was influential in the early redesign of sonar, and in starting a part of the acoustic torpedo work at Harvard. They made considerable contributions, but I think Houston and Bell Laboratories did the job that went into service. Eric Walker, who later became president of Penn State, was important in the Harvard work. Harvey Brooks was important, too.
He [Walker] was also the first president of the National Academy of Engineering?
Yes. Harvey Brooks was a very young man but influential in Harvard work. You can go down the list and name many people who were extremely important. But it was certainly a team effort, working on a very important problem without any fancy new discovery to spur you on, as some of the other labs had. Now, where do we go from here?
I’ll leave it up to you, whether to talk any more about the last few items of III or go on to IV.
I don’t think I have anything particular to say about those last two. Let’s go on to IV, shall we?
IV, “ancillary studies in and about physics.” I apologize for the title. I didn’t know what else to call this. But I’m asking first of all for some rather broad generalizations, from where you sit, the people with whom you work—after having risen from several different directions, to an overview of physics. About the role of physics in science, its centrality; the role of optics in physics; the role of acoustics in physics and mechanics; particularly the role of the notions of the perfect vacuum and the perfect plenum, ideas of natural philosophy?
Well, I suppose I respond in a more general way. I’ll say something about some of these items, but not all of them. I think there’s no question but that physics continues to have a central role in all science. Sometimes we’re inclined to over-emphasize the importance, to the annoyance of our colleagues, but after all, the main purpose of physics is to understand the physical world and how it is constructed and what it consists of and how we can make use of it for human purposes. Now, various physicists have different points of view. Some want to study basic physics, without regard to applications, and others are very much concerned with applications. Actually there’s a continuous spectrum of interest in the importance of problems as you go along the line. Some of the greatest work has been applied, and some of the greatest work has been far from applications. But I’ve always been impatient with physicists who want to insist that they’re this kind of a physicist, that kind of a physicist or some other kind of physicist. In my judgment, there are good physicists and bad physicists and that’s the end of it. I remember a very interesting lecture here by Professor J. H. Van Vleck of Harvard, when we gave him the first Michelson prize. He was asked to speak to the students, in addition to the dignitaries who had heard him the night before, and he chose for his talk the title, “Fermi as Engineer; Edison as Scientist.” He pointed out the great contributions that each of these men had made to the other aspect of technology and science that they’re not usually associated with.
I think it was a very great education to the members of the student body and the faculty who listened to Van Vleck, to get over the notion that they had to be specialists and always be labeling themselves as this, that or something else. I think the title that Van Vleck chose here was a very remarkable way of emphasizing the unity of both the fundamental aspects of physics and its applied aspects. Of course, if you consider physics as a central science, that designation has no meaning unless physics is closely related to other sciences, and that immediately implies applications. A great argument goes on at all times about whether physics is too applied, or too theoretical. I’ve never known a really big scientist who ever made this distinction. Men like Lawrence, Compton, Karl Compton and so on — they had interests all along the spectrum of physics. Their particular achievements can only show up in a few places. That’s because life is short. I think Arthur Compton was fully as interested in his work on the fluorescent lamp as he was in the Compton effect. He realized that it wasn’t going to be talked about as much, but that didn’t bother Compton.
One of the reasons I asked this question is because it seems to be part of the counter-culture. It is related to the growth and the new glamour of molecular biology, and to the question of hybrid disciplines, biophysics, biochemistry and so on. The life sciences are attracting many of our best minds now, I think, and rightly so. But this leads I believe to a bigger overview. Historically, I think man has generally looked on Nature more organismically, or organically, than he has according to the assumptions of Newtonian mechanics and Cartesian distinctions between mind and matter and that sort of thing. So, do you see any threat on the horizon to the centrality of physics in science? Do you think biology has a turn now, to come back perhaps to the most central position?
Well, biology is of course extremely important and has always been extremely important, and it has a very great significance, because of its relation to life and disease and health. I think the great interest in molecular biology and in many kinds of science touching on medicine has been increased, by recognition on the part of the medical profession that they’ve got to have something in the way of scientific support other than just instrumentation. When I first was head of the physics department here, I had occasionally a very good student who wanted to go into biophysics or biomedicine because he was generally interested in helping to contribute to medicine and health. But most of them were very disappointed before the war. They were rebuffed by the medical doctors and treated as mechanics, or less than mechanics, and most of them quit it. Now, more recently, the medical professions have realized that they’ve jolly well got to get some help. Physicians must treat these people on an even level with themselves, not as helpers — and they haven’t all agreed to do this yet. There’s still a lot of monkey business in the medical profession. It’s ridiculous. But, if medicine really wants to use chemistry and physics and technology, they can get a lot of help out of us. But they’ll have to treat the people that work with them as colleagues and not as servants. I don’t think that [this conflict of professions] is really solved yet. If that comes, then molecular biology or whatever you want to call it may become a much more critical item in medical education, and in medicine. There are strong movements in that direction, and it’s probably on the way. But I’m not sure how far it will go.
These switches of interest from one kind of science to another continually recur. I’ve seen it swing back and forth, several times, in my lifetime. And it will continue to do so. In a sense, think calling any science the central one is a little presumptuous. Our friends in mathematics always talk of mathematics as the Queen of the Sciences, and they never tell you what they mean. We’re willing to agree without hesitation, it’s basically important, but when they use the royal term for their own personal advantage, then it loses all its significance, and certainly don’t want physics to try to get support on the basis that it’s “central.” If it’s central, it will be treated as a central subject, not because people designate it that way. But we’re in a time of flux. There’s no question that the attraction to various branches of science and technology that young people experience is undergoing profound changes. Appeal isn’t going to be altered by what the professors say or what the college catalogues say. Students actually talk to people who graduate and go to work and contribute to society. How any branch evolves in the future will depend on its achievements. I don’t know just how you evaluate that. I think physics will always be a very important subject, but it may not have the same afflatus that it had right after the war. Many people assumed that everything in physics had been done between 1940 and 1945. A lot of people are not inclined to remember history. Maxwell and Rutherford and others were also important to the wartime achievements.
Well, I think that’s all I have to say about your first item. “Interest in Michelson-Morley” — well, I certainly have been interested in them all my life, and I still am. I’ve written a number of papers in which I tried to write down things that I learned pretty close to first hand here about them and their work. I hope to do a little more of that, before I’ve written everything that I have in my notebooks. They certainly were a great pair, and their contributions to physics and science generally will last as long as we have an interest in the subject, I am sure. I suppose here in Cleveland, we’re a little bit inclined to overemphasize Michelson and Morley, but on the other hand, they made an achievement that we’re very proud of, and I think this is recognized generally. Next, you have here my “conversations with Professor Einstein” — there again, I’ve written that up on two occasions. I hadn’t expected to write up anything about my talks with Professor Einstein at the time that I visited him, because I just considered them as personal privileges which I greatly valued. But after a number of years, I realized that there were younger people who hadn’t had that privilege, and I was persuaded to write them up. The first conversations were written down almost strictly verbatim. I didn’t make any effort to interpret, or try to decide what he really thought about this or that. But the second version, I did put in some of my own interpretations of what I thought he felt, to clarify, I hope, the earlier article. I don’t know whether I’ll write anything more about these conversations or not, but I might have a few more things to say before I drop the subject.
You have several Sigma Xi lectures coming up later this year, do you not?
Yes, I’ve been asked to give two lectures in October, as the so-called National Sigma Xi lecturer, on Einstein. This time, I think I will entitle them “Einstein and the Michelson-Morley Experiment.” I want to clarify the relationship that the experiment had not only with Einstein but with the development of relativity generally. This will give me a new subject to talk on, and if I find the lectures are interesting, why, I may write them up and publish them, but I’ll see how they are received first.
I’m sure they will be welcomed, and I hope you keep me on your mailing list. I wanted to ask at this point for some clarification from your publication list here — What was the difference between the “New Analysis of the Interferometer Observations of Dayton C. Miller” as appeared in Physical Review, vol. 96 in l951i, and the same title in Reviews of Modern Physics, vol. 27 in 1955? There was a new collaborator, Kuerti, who came into the second paper, and I was wondering the nature of the collaboration of the three, then the four of you, on the re-analysis of Miller’s work on “absolute motion.”
The final paper was the second one, of course, which appeared in Reviews of Modern Physics, and it was a complete and detailed study that we had carried through. In working through this analysis of Miller’s very extensive data, first started by myself, and I found it was a big job, so I asked Sid McCuskey to help me. He knew Miller well, and we worked on it together. Fred Leone was brought in because at that time, he was in charge of the computers here. I don’t think Leone ever had any very deep interest in the problem per Se, but he was helpful to us in carrying through the programming for getting the results. In that, he worked closely with Sid McCuskey. But then, after we had reached a certain stage, I became much better acquainted with Gus Kuerti, who was on our faculty; he is a great expert in mechanics, mathematics, theoretical physics, many things. By then, we were interested in the possibility that Miller’s result was due to some vibration or unusual motion of the interferometer as a problem in mechanics, vibration. So Kuerti first tackled that problem, and he did some masterful analyses of the interferometer as a gyroscope, as a vibrating system, and I don’t know what all. He concluded that none of these effects could have explained Miller’s results.
So that part of Kuerti’s work was never published. It’s in his notes, and I’m sure it’s a beautiful example of really sophisticated and expert work in mechanics. But then, along about the same time, our interests, my own interest in the temperature effects deepened, and Kuerti came in on that. As a matter of fact, he came in on all aspects of the problem, so while his name appears last on the list, that’s just an historical accident that he joined the team at the end. But he was a major collaborator in the whole business, and as I said, a large amount of what he did he never published. We even looked into this magneto-striction thing, and Kuerti calculated that and found it was much too small to explain the results. You see, there have been critics of Miller’s work starting with Eddington and going down the roster of physics, critics who pontificated that Miller’s work was due to statistics, or magneto-striction, or something else anomalous — they never calculated anything, they just announced that this was what it was, because they didn’t like the result and they wanted to dispose of it.
But it turned out that the real explanation was the temperature effects. As I said before, we’ve always been very grateful to Professor Einstein for his interest in that aspect of the problem, and his help and criticism. The curious thing is that way back in 1921, Einstein wrote a letter to Ehrenfest, Martin Klein told me about this, suspecting that temperature was at the root of Miller’s results. But Einstein never mentioned that letter to me, in all the times we talked. And I wondered if he forgot it (which is probably what happened) or if he just wanted us to find it our own way without prejudicing us. There again, I would have asked Einstein, but I only found out about the letter after he died. Well, that’s about all I have to say about that. The earlier publication in the Physical Review was a preliminary announcement. The Reviews of Modern Physics article is the one that I hope people will read. OK, what do we come to next –- “inheritance from D. C. Miller”? I’ve talked about Miller a great many times.
We haven’t talked much about the physical machinery, offices, papers, data books. You’re the direct inheritor of the physics department here from the 1880’s.
Yes. Well, a great deal of my early introduction to physics of course came from Miller, and all his life, he was one of my great friends, very cordial, always tried to steer me in new directions that were important for a young fellow to explore. The inheritance from Miller — of course, this building was designed, supervised by Miller. The apparatus that we inherited was from Miller…
This is Rockefeller Hall, in which we’re now sitting?
Rockefeller Hall, yes. The apparatus was finally a little bit out of date. Miller had equipped the laboratory with great care in 1965 and carried it on, but when it came to atomic physics, nuclear physics, things of that kind, it was a different era. So we had to, as any physics laboratory has to do, we had to continually change the equipment and throw things away. I think the main inheritance from Miller was a lifelong devotion to try to make something out of physics here in Cleveland, at Case, in the United States. His overall achievement was very great. He used to be very proud of the number of physics graduates he had in important positions all over the United States. There was a large number of graduates from the physics department during his years who had gone on and had obtained doctors’ degrees and become heads of physics departments, heads of laboratories, positions of that kind. And they all thought the world of Miller. When Philip M. Morse wrote his book on acoustics, he dedicated it to Miller, and when Edwin C. Kemble wrote his book on quantum mechanics, he dedicated it to Miller.
I remember very clearly one morning, coming into the office here, and Miller was ahead of me, as he usually was. He had just received Kemble’s Quantum Mechanics in the mail and opened it and on the first page it said, “Dedicated to Professor Dayton C. Miller,” and Dr. Miller had tears in his eyes. He said to me, “But I didn’t teach any of this to Edwin.” Which was a classic remark. I guess in the case of acoustics, he was willing to admit that Phil Morse had learned some acoustics from him, but not in the case of quantum mechanics. Miller was a great man. I think it’s too bad that he got mixed up into this controversy toward the end of his life. ft distressed him a great deal. On this he was often very unfairly quoted in the newspapers. He was always held up as an opponent of Einstein and all that, which was not the case at all. But he did have or get this small effect which he couldn’t explain, and he refused to shove it under the carpet. And I must say, it took some doing to find out what that small effect was due to. It did have statistical significance, which is all anybody can expect from an experiment. I personally think he worked too long on the problem. I. think it would have been better if he had devoted the same energy to acoustics. But that was his decision, not mine. Certainly he worked hard on everything he undertook.
Re Miller’s absolute motion of the solar system, how do you feel about the renewed astrophysical interest in the 30 Kelvin microwave background radiation, as applied to “big bang” cosmology?
Well, I must say that this is a subject that I know very little about, but I will make one or two comments. It seems to be generally accepted that the 30 radiation is a strong support for the big bang hypothesis. And of course, if directional effects are found, this will add to the understanding of where it originated, perhaps. However, it would seem to me that the secondary scattering processes that have gone on for a long period of time may well obscure any directional effects of significance. But on this, I hesitate to have a firm idea. I might say, in a more personal vein, that at one time I was very much in hopes that the steady state theory would be the one that would prove out, because it seemed to me so much more satisfying in some ways than the other. Why, I can’t explain. It’s just a matter of personal prejudice that perhaps goes back a long way in my consciousness. But at the present time, I believe the steady state theory is out, so it’s only proper that interest in these matters should go to the big bang and microwave studies. That’s about all I have to say on that. Next, you have here, “biographical or sociological approaches to our understanding of history of science.” Well, certainly the biographical part is important, because no scientist can work independently of his background, and his methods of work are largely inherited. I think, however, that approach can go too far, and biographical details of a personal nature often really have nothing to do with a man’s work in science.
But where you draw the line, where you make a distinction between what is pertinent and what is not pertinent, is difficult. I would cite Dorothy Michelson Livingston’s recent biography of her father, The Master of Light, as a very excellent example of largely biographical writing, which nevertheless almost on every page gives insight into physics. This is a rather remarkable achievement, especially when one considers that it’s written by a non-physicist and a member of Michelson’s immediate family, his daughter. But in reading this book, you are never conscious that trivial biographical details are brought in; neither are you conscious of special pleading in favor of Professor Michelson by the daughter. I think it’s a remarkably objective book in that respect, and remarkably accurate as far as the physics is concerned. I think all of us who have had an interest in Professor Michelson have been deeply impressed and greatly helped by studying this book in detail. Many things that Dorothy has made available to us from her intimate knowledge of her father’s work — really bear on his physics. Now, the sociological approaches are a little less familiar to my own interests, but here one needs to have a long term to study the effects of science, as compared to the biographical aspects, which are in one man’s lifetime. Certainly the sociological consequences of our science are coming more and more into prominence. Much of this has been analyzed by people who have a specific ax to grind, or a political objective to further, by using science as a support. But let us discount those people who are not using the approach for scholarly or objective ends. I think as time goes on the sociological aspects will have to become more and more a part of our understanding of science. Of course, it’s clear that just understanding the sociological consequences isn’t going to do any good unless we can get a hold on the political and power aspects to control R&D. There’s a tremendous gap between the people who are studying the sociology, and those who are in positions of power. That gap is far greater than the gap between science and technology. And how you close that gap is a problem that will take a long time to solve. Now. Re Compton’s X-ray papers — well, as you know, I’ve had the privilege of editing Arthur Compton’s X-ray papers for the University of Chicago Press. (1973)
You originally had intended to do the whole corpus of Compton’s works?
Yes. We had originally planned to have two volumes, one on X-rays and one on cosmic rays. My responsibility from the first was primarily for the X-ray papers, although I’m sure I would have become involved in the cosmic ray volume, too. But this is a very expensive time to bring out books of this kind, and the funds that were available were better used to concentrate on the X-ray papers at this time. However, had I known at the outset that the cosmic ray papers would not be published in separate form, I would have included two or three of the Compton cosmic ray papers as appendices. This I couldn’t do at the last minute because it would have necessitated a whole lot of renegotiating of the printing contract and one thing and another. Specifically, I would have included the summary paper of Arthur Compton’s worldwide survey of cosmic ray intensities. I would have included the Alvarez-Compton paper showing the east-west effect at Mexico City, which was very important in proving that the primary cosmic rays are protons. And I would have included the Compton-Turner paper which showed the effect of atmospheric conditions on intensity; this later was a hint for Blackett and Rossi in their realization that the meson component of the cosmic rays was radioactive. I think it would have been very nice to have included those three papers. We did include at the beginning some of his work in aeronautics, astronomy and things like that, and it would have been very easy to have added three or four cosmic ray papers at the end, even though the bulk were X-rays. But it was impossible, once the contract was signed with the printer — University of Chicago Press was very reluctant to raise the question again.
We were just talking about the cosmic ray papers of Arthur Compton that might have been included in the first volume, had it been known that a second volume would not be published.
However, I was able to add a paragraph to the end of my introduction to the book which called attention to these cosmic ray achievements, so that they can be readily referred to by interested readers. One of the most rewarding aspects of this editing job was the correspondence that I carried on with a number of prominent physicists who had been active in physics in the early 1920’s when Arthur Compton made his great discovery of the Compton effect. These included some 60 men in all parts of the world who themselves had contributed to X-ray physics, and who were thoroughly acquainted with the achievements of Arthur Compton, at the time he made them or shortly thereafter. One of the most unusual points of this correspondence was that, of the 60 people to whom I directed my inquiries, all but two answered my letters, and many answered in rather complete detail, so that I have a valuable file of letters from physicists whom I’ve known all my life and respected a great deal. Regarding possible future work coming out of the X-ray experiments of Arthur Compton, I’m sure that the Compton effect will continue to be of central importance to physics, for the indefinite future. For this interaction is one of the most basic we have in science, and one of the simplest. Any theory, to be accepted, must explain all features of the Compton effect in the greatest detail. It will be interesting to see if experiments in electromagnetic processes at the very highest energies give any hint for extensions or refinements of the Compton theories as we now have them. Today, no discrepancies have been found, at least to my knowledge. I think that’s enough on that. Do you have any further questions?
Unfortunately, my ignorance is rising to the surface here. You might say something about who — some of the names of the people involved in your correspondence on this.
Well, Sir W. L. Bragg, Heisenberg, Louis Brillouin, W. D. Coolidge, E. C. Kemble, J. H. Van Vleck, Kirkpatrick, Honi, Wentzel, Louis de Broglie, D. W. Webster, P. P. Ewald, James Chadwick, Blackett, and others — you could go right down the line. I don’t remember all of them, but it would be a list of physicists who were active in the twenties. Carl Eckart was a student of Compton’s at Washington University when he was making his discovery, then a colleague of his at Chicago later on. He was extremely helpful. Now, let’s see –- “physics teaching for engineering,” “scientific education or liberal education” —
Let me make this more pointed by asking you a specific question. Again, this comes from a humanist and historian who’s had a longstanding interest in philosophy: do you believe there’s any such thing as the scientific method?
No, I do not, in the way that’s usually stated, and for this reason: The people who talk about the scientific method imply, and I think believe, that there’s a steady progression from one approach, and one attack, to another, which gradually leads to the final result. And I think all of us who have worked in any kind of science or engineering realize that most of the steps that are taken throughout the investigation do not lead anywhere. They’re in error, they’re down the wrong track, or something of that kind. And it’s only after you’ve worked and labored at a problem for a long time that you get a proper insight, and then the final step is often a very short one. I wouldn’t want to call this process the scientific method. I wouldn’t even call it the process of elimination, because you’re not consciously doing it that way. I remember very vividly what Professor Einstein told me on this point, when I asked him about how long he had worked on the special theory of relativity and how he came to it. I won’t try to remember all that he said to me, but I can tell you that the essence was this. He worked on it for nearly ten years, and everything he tried was a failure, until almost the very end. When he came to the realization that the key to the problem was the velocity of light and its invariance, then he went reasonably quickly to his final statement in the 1905 paper. But he said that the process of thinking through any problem is a very random one, a devious one, and you can’t define it as any logical sequence. Those are not exactly his words, but that’s what he meant. I’ve had a very difficult time to understand what people mean by the scientific method.
It’s merely a pedagogical tool, isn’t it?
I can recall an incident that occurred in this office of mine, many years ago. We had a very outstanding graduate student in physics, Robert Strough, who is now an officer of an industrial company, and he had his final Ph.D. exam in this office. There was a committee of four or five of us asking questions, and the dean thought we ought to have somebody from the humanities on the committee, which was all right with us. But it had an amusing end. Strough performed brilliantly for several hours, telling us everything about his thesis, more than we needed to know. And then at the very end, I asked our visitor from the humanities if he had a question, and he said, “Well, Mr. Strough, I want you to go back over your thesis and show how you used the scientific method step by step to get to your solution.” Well, it completely demoralized the young man. He was all tired out and he’d never heard of the scientific method, so I just dismissed the exam, and we never had that question asked again after that. Seriously, all joking aside, the scientific method is the way scientists work. But it isn’t a scientific method. Every scientist works in a different way, and every scientist I daresay works in a different way on each problem. And when you write up your final result, all you give is the last step, or even less than the last step, to give a nice polished paper for an editor to approve. So the real essence of the process is missing. That of course is a thing you only learn by association with another scientist who has learned how to finish problems. The teacher-student relationship in research, that’s the essence of it. It’s not easy to define, it’s not easy to learn, but close association does it.
Are there then policy differences, or not, in the way in which physics teaching should be presented to undergraduate engineering students as opposed to pure science or liberal arts students?
Well, now, wait a minute — you’ve got three categories there, and don’t think they relate quite the way you said. My experience has been almost exclusively teaching science majors and engineering majors. Of recent years, we’ve had much closer touch with liberal arts students from Western Reserve College, but I personally have not had much experience teaching them — not that I would not like to, but I’ve always had an adequate job to do teaching engineering students and science students. As between science and engineering, I don’t think there’s a great deal of difference. We sometimes divide our students that way, and give the science students a more mathematical approach than the engineering students, but I don’t like that. I think the engineers welcome and use mathematics fully as much as we do, and some of them use rather sophisticated mathematics. Now, when you go to specialized courses, then it’s a different matter. The student engineer is probably not interested in an advanced course in nuclear structure. But he may be very much interested in a general course in nuclear energy, for example. I think the liberal arts approach should be much the same, but the limitation, as see it there, would be in the mathematical background which they lack, and the necessity to teach without too much mathematics. But even that is not an insurmountable barrier. You can teach a course mathematically so to speak or quantitatively without deluging them with details. Some of the most successful teachers of advanced subjects have adopted that method. For example, people who have taken courses from Professor John Slater at MIT, tell me that he was a remarkable lecturer in giving a thoroughly quantitative, theoretical lecture with a minimum of symbolism. He expected the students to do the problems afterwards, but he didn’t hide the physics behind the symbols in the classroom.
Was Richard Feynman that way also?
I don’t know. The only specific example that comes to my mind is John Slater. And Slater is one of the best of our theoretical physicists. I think learning depends on the attitude of the students, more than anything else. A student majoring in humanities who genuinely wants to learn something about physics can do it, and learn just as profoundly as an engineering student. The thing that differs is motivation: where these people are required to take a course in science or physics, if they don’t want to take it, they don’t want to learn anything, they just want to get a passing grade. It’s very difficult to teach them anything of significance. And I don’t know any way to correct that; as long as you have required courses, that are not in a person’s major field, some or most are going to have this attitude. But I would believe that teaching, at least through the undergraduate years, to the senior year at least, does not need to be markedly different. But I must repeat that my experience is limited exclusively to science students and engineering students, and I only know the liberal education side second hand. But a good teacher will make his subject interesting at many levels in a class in the same lecture. That is, he’ll challenge the best students, and he’ll provide something that’s worthwhile for the poorer students. I would say, that’s the mark of a good teacher: can he give a lecture that has something for more than one type of student? Many teachers cannot do that, and that’s a defect in their teaching. Teaching is a very, very subtle art. There’s no sure way of doing it.
Do you believe it’s like pouring into a container, or lighting a candle? That’s a loaded question.
I certainly would take the latter example. But I think it’s a lot more complicated than either. Now, let’s see, “personal satisfaction, most significant work, pure science” and so on…
We need the third category, applied science too.
Does that mean applied science too?
Well, what do you feel in looking back over your career, at this point, it’s by no means over — what do you take greatest pride in, in terms of work, in more purely pure science, or in the more applied way, and finally ancillary studies?
Well, frankly, I’ve never drawn a very sharp line, if any, between these things. The boundaries between what’s called pure science and applied science and related scholarship, like history of science, are not sharp. You are conscious of the other two categories, and perhaps more categories than that, when you’re doing anything, and I would say that I’ve had as much satisfaction from each as from the other. The greatest satisfaction that any teacher has is the stimulus that he can give good students, and I’ve had students here at Case who have gone on and made major contributions in pure science, applied science, engineering, history, education — I wouldn’t say that there was any distinction in my personal sense of satisfaction. For example, I’ve had students who have gone on and become very distinguished theoretical physicists. I’ve had other boys who have asked me in years past if they could take their electives in education so that they could go into high school teaching. And some of the latter have become the most influential people in Cleveland and elsewhere in secondary education. Now, I don’t propose to judge between the two types of achievement. Both of them please me a great deal, and as long as a fellow finds something that he’s capable of doing and does it well, that’s enough. I think when you start rank ordering lines of endeavor, you’re on very shaky ground, especially if you’re a teacher. And most of the rank ordering that I’ve noticed lately is for budgetary purposes, and not for…
I was thinking especially in terms of your papers, publications that you’re especially proud of — which represent tips of icebergs of course.
I’ve taken a great deal of satisfaction in the papers I’ve written about the work of Professor Michelson, and Michelson and Morley, and also the reports that I’ve been privileged to make about my meetings with Einstein. Then I’ve taken a great deal of satisfaction recently in the papers I’ve been able to write on acoustics. Because I’ve been able to write them on aspects of acoustics that interest me in a very personal way. I haven’t been tied to a specific type of effort, like underwater sound for the Navy, or developing a better acoustical tile, or that sort of thing. And I’ve been able to give myself freer rein in the work in acoustics, because I have not been tied down by contracts or commitments of any kind. I’ve been able to do the things I wanted to do on my own, and it’s been a very great privilege and a very great satisfaction to do it. Now, do you want me to comment on the next to last one?
Yes, we talked a little bit at lunch about the nature of the problem of the “crucial experiment,” which is a term like “Copenhagen interpretation,” used very widely by people who are not scientists, by spectators on the sidelines. Philosophers of science since Bacon and Descartes have talked about the experimentum crucis, as being a major fork in the road, a turning point for scientific advance. The Michelson-Morley experiment, of course, as we have discovered, working separately and together, has a reputation that far outdistances or is different from, actual character. Gerald Holton in his recent paper, based partly on your work and a little bit on mine, has a specific kind of interpretation of the role of the Michelson-Morley experiment in relation to the advent of specia relativity. I think it’s important that you be on record, (and I too eventually be on record), about how we feel about Holton’s interpretation.
Well, the term “crucial experiment,” with that emphasis, is one that we understand in physics, but I don’t think it has quite the importance that is implied here. So let me be specific on the group of experiments that you have mentioned. At the beginning of the 19th century, when Thomas Young, Arogo and Fresnel revived and extended the wave theory of light, the question was asked, what is the medium in which light propagates? And it was felt to be a very basic need that this medium, the so-called ether, exist. And so, throughout the 19th century, experiment after experiment after experiment was performed in the hopes of either finding the ether or clarifying its properties. Related to this underlying feeling that there had to be a medium was the search for a crucial experiment. If you glance through the literature of the 19th century, it’s literally full of such experiments. Most of them are optical, because optics was the technique that was most highly advanced at that time. A number of them however were electrical, although they’re not as well known. But for a long time, all these experiments had a certain low sensitivity, and it was agreed that they did not reveal the ether. These were the so-called V over C (V/C) to the first power experiments. And then Maxwell emphasized that the question might be solved if we had a technique that would measure with sufficient sensitivity to show effects depending on the V over C (V/C)2 or the second order. Maxwell assumed that this was impossible. But Michelson devised his interferometer specifically to make measurements that were of this sensitivity.
Then later, working with Morley in 1887, they carried through the experiment that showed that to the sensitivity V over C squared, they still could not detect the ether, or show its effects. Now, the Michelson-Morley experiment had a terrific influence; it was the first experiment that had this (V/C)2, sensitivity. It was by no means the only experiment, however, Trouton and Noble,  working on a suggestion of FitzGerald in Dublin, performed an experiment involving the torques on a charging and discharging condensor, which also theoretically could have shown an effect. It likewise did not. Lord Rayleigh performed an experiment  to try to detect double refraction, produced by the Lorentz contraction of a moving crystal, and this showed no effect. Later, Brace in Nebraska repeated the Rayleigh experiment , and showed that no effect to the third power of V over C was present. And many experiments after that continued the same line, right down until recent times when Charles H. Townes has been performing his experiments with masers and lasers on the subject.
Now, if you forget for a moment that we’re in Cleveland, and near the site of the Michelson-Morley experiment, and you look back at this long progression of experiments, you certainly will have to say that the first experiment that measured to the quantity of V over C squared, V2 over C2, had a new importance in the whole stream of things. However, if the Michelson-Morley experiment had not been performed, then the Trouton-Noble experiment would have taken its place, as the so-called crucial experiment, or the Rayleigh experiment. Indeed, if you were looking for a crucial experiment, the one of Brace that showed a null result to the third power should be considered. But nobody ever talks about Brace’s experiment; it’s much less well known. I would find it difficult to talk to my students about the crucial experiment, in any case. It’s the whole stream of experiments that’s important. You can go back and say, “If this experiment had not been done, we’d still have the same story.” And you can take another one out, it would be the same story. Now, how far back you could go in eliminating experiments, and still have scientists believe that relative motion could not be detected by such means, is a question. If there was only one experiment supporting the idea of relativity, we might not believe it. If there are dozens of than, as there are, then we’ve got to believe it, but whether to call one of them crucial or not I don’t know. Certainly the Michelson-Morley experiment received far more attention in the literature, and in the informal discussions between physicists, than any of the others. I think this was really largely because of the great importance attached to it by Lorentz and Rayleigh and Lord Kelvin at the time.
They were the molders of the climate of opinion?
That’s right, the climate of opinion. Now, whether it’s a crucial experiment in the sense that Professor Holton means, I’m not sure that that has too much significance. It was certainly important in forming the background knowledge upon which further physics developed, and whether any particular individual was influenced by it more or less, Einstein or Poincare, Lorentz or Larmor or anybody else, seems to me beside the point. The point is, it was one of the contributors to the climate of opinion in which physics developed, and that was its importance. It certainly is true that if you remove the Michelson-Morley experiment from the whole group, it probably wouldn’t have made much difference. On the other hand, it was one of the most important experiments in setting the tone of the whole group. And I don’t see how you can separate one from the other, any more than you can take one cyclotron experiment and say, “This is what proved the cyclotron was useful.” In physics there are too many weaving cross-linkages to pick any one thing out as crucial. Now, there are tests that, if they are interpreted in certain ways, are pretty decisive in molding opinion. I think of the Compton effect, for example, in proving once for all that we must have both wave and corpuscular properties of radiation. And it’s a little difficult to conceive that we would have had our present physics without finding the Compton effect — but we could have.
When I was a graduate student, there were many experiments that were recited to us as being decisive for the development of quantum mechanics. There was the photoelectric effect, and the Stern-Gerlach experiment, and electron diffraction, and the Compton effect, and the (Carl) Ramsauer effect — that was a big one when I was a student. It’s true, they were all very important. But there were dozens of other experiments, including everyone which ever measured a spectrum line, that you could call just as decisive an experiment as any one of them. So I don’t personally find the term “crucial experiment” of particular usefulness for my thinking, or even of interest for my thinking. Not that I have any objection to it, but I don’t think things go that way. It’s a little bit like saying that Pickett’s charge at Gettysburg was the crucial moment in the Civil War. This is nonsense. It was the whole Civil War taken together that settled the question. Pickett could have stayed home, the outcome would have been the same. I really think that’s a better analogy than most people may be willing to admit. In talking with Professor Einstein about this experiment — I’ve recorded my thoughts on this — I asked him on each occasion about this experiment, and his answers to me differed in some detail each time, but there’s an overall pattern that in my mind makes me certain that he knew of this experiment. The fact that it did not reveal absolute motion was important background material for his thinking. Whether he was consciously guided by it is another matter. See, it’s a null experiment. It’s pretty hard to use the result of a null experiment in a direct computation. So I think all this business about whether Einstein knew about it or not is a little bit beside the point. I think he knew about it, but I think he could have got along without it, too. It’s that sort of thing.
OK, are we at the end? Have you any estimate of the future — significant problem for the future of acoustics, the future of optics, future of physics, science, history of science?
Well, I would say first, in the case of acoustics, there is a very important need to make first class acoustics available to a larger number of people than is now possible. We will have to have bigger audiences, we’ll have to have bigger congregations in churches, so we’ll have to have better acoustics. And this will mean significant improvements in architectural acoustics and electronic acoustics. I think we’re way behind in the latter. I’ve often said that if we had the same technology applied to public address systems that we have for problems for the military, we’d have much more to show for it. We don’t get anything but second-class products when it comes to the market. However, there have been some excellent contributions recently — the time-delay circuits, and certain advances in loud speaker design — but in my opinion, nothing of what should be done, in order to have really good acoustics for the people as a whole. And this would not only be in buildings where congregations are present, but also over the air. There’s a tremendous need here for really good electronics, getting sound right to the people, and it is not getting there, because everything is determined by cost and other extraneous factors.
There’s no reason why a church should not have as sophisticated electronics as a rocket. I think we’d better change our thinking on this thing, and do it. That applied to applications of science in general. Now, in optics, I’m not so sure I have much to say there. Optics is a very sophisticated and advanced subject. There again, I’ve had a recent experience in trying to find a camera to do certain things on a trip to Europe, and I must say that the cameras that are pushed on the public now are, including a lot of gadgeteering, junk. They are made to sell at a high price rather than to do the job, and I think somebody had better get busy and translate the real advances that have been made in optics available to people on a cheap basis, and not just try to make an expensive gadget. I think I’d make that same criticism of the application of physics and science right through our technology. At a certain stage, ideas are taken over by the bankers and people like that, and the promise of technology is never realized. Anybody who worked in the war and saw what can be done to make a device or instrument really work is truly amazed. And then when you come back after the war, and see what shows up in peacetime products along the same general line — it’s disgusting. This is being said by a very conservative member of society. I’m not interested in political innovations or revolutions. I mean, this as a weakness of our whole setup. I think the promise of science stops right there — when the financial people take over, and begin to cheapen things.
You can take any product that you have and look at it, and you’ll see dozens of places where it could be made better, but it’s been cheapened to make greater profit for somebody who’s only interested in that aspect of it. Re the history of science: I think there’s a lot to be said for studies in the history of science, but without being too critical of the general subject, it’s my general impression that many of the studies in the history of the sciences never get out of a specialized group. There are journals of the history of each science, and they’re very interesting to read. They have very fine articles in them. I’m not too sure how many scientists ever look at them. A few of us do and we’re very interested in them, but it seems to me that’s one of the problems that faces the history of science, just as it faces physics: how do you make this information, this wisdom, available to a large group who really could profit from it? You as a professor of history know the problem better than I can, but I have a feeling that a lot of things that are written on the history of science only get into journals on that subject, would you agree with that?
I don’t know what you do about it, but this is true of all disciplines, we tend to talk to each other. I think in the case of the history of science, the real importance of it is to show how important this is for a broader field than just the specialist. And many of the journals in which these articles appear are completely unknown to the physics community, for example, I think there’s something there that we ought to correct. Well, I think I’m about through with what I have to say to you, sir, and it’s been a great pleasure to talk to you.
Thank you, both for myself personally and for my generation of historians of science and physics, and for future generations. Now comes the hard process of editing and re-listening.
Well, it was very nice of you to come, and I’ve enjoyed talking to you about many other things besides what’s on the tape.
OK, adieu for now.