Steven A. Moszkowski

[Editor’s note: Prior to his death on Dec.11, 2020, Prof. Moszkowski generously took the time to provide extensive written edits to this interview transcript to clarify and expand on points discussed in the spoken interview.]

[Part 1]

Behrman:

April 30, 2020. My name is Joanna Behrman, and I’m conducting an oral history interview with Dr. Steven Moszkowski. Thank you very much for talking with me today.

Moszkowski:

You're welcome!

Behrman:

So perhaps we could start with your childhood and then move forward. I know you were born in 1927, but I don't know much else.

Moszkowski:

Looking over the questions, I noticed that you're going to ask about my parents, their own education, and so I’m prepared to do that. Then, of course, I’ll start with my own childhood.

My father and mother were both born in Germany. I think I might actually start with my grandfather. His name was Alexander Moszkowski. He was a writer, a semi-popular writer. He was the editor of a magazine in Berlin, the Lustige Blätter, and he got to know about Einstein. As I will mention, Einstein actually played a big, if indirect, role in my education.

Behrman:

Right.

Moszkowski:

As you probably know, Einstein came to Berlin in 1914. He had already become very noteworthy and well-established in the community of physicists because of his development of special relativity and the photoelectric effect and Brownian motion. But his wife, Mileva Maric, was very unhappy in Berlin. Their marriage had been sort of breaking up, and then it did, later in 1914. Now Einstein was alone. In Berlin some of the intellectuals were interested in Einstein, so he gave semi-popular lectures on special relativity and probably also the photoelectric effect. My grandfather came to some of these lectures. So Alexander Moszkowski and Einstein became friends.

Now World War I broke out, and their lives were of course, somewhat disrupted, but not that drastically. However, one crucial effect of the war was that the British Royal Navy implemented a blockade of Germany. This led to food shortages in the country. One of the consequence was that Einstein’s health deteriorated. When the war broke out, Einstein was working on general relativity, but his early version of general relativity was not complete, There had been predicted an eclipse of the sun in 1914 in the Crimea. So an expedition was sent from Germany to Crimea to observe it. With the war on, the folks in the expedition were interned by the Russians, and so this expedition didn't come to anything, which is just as well because, number one, it was very cloudy on the day of the maximum eclipse. Number two, even if they had observed it, they would have found a deflection of light by the Sun about twice what Einstein had predicted as of 1914. He would not have become world famous. But a year or two later, Einstein fixed up the theory. So when in May 1919 another solar eclipse occurred, this time over Brazil and West Africa, teams were were prepared to observe it, and the results, announced in the New York Times 6 months later, made Einstein world famous, essentially a scientific saint. That’s why we’re talking about Einstein today, even a century later.

In World War I, Einstein was a pacifist. He did not share in the war hysteria that overcame much of Europe and in United States when the country entered the war “To make the world safe for Democracy.” So what happened to Einstein? Actually, he was pretty much ignored by the Kaiser and company. He was not arrested and was able to do his research.

One other thing which I better mention here was that Einstein, being alone, did not take very good care of his own health because he was absorbed in working out general relativity, and he became quite sick. Some of his fellow scientists helped him get well, but in addition, there were a number of people who knew he was ill. My grandmother, Alexander’s wife Bertha, had a butler who knew somebody, a relative up in the northern part of Germany and they were able to get some food from there to Berlin. This was one of the things that helped Einstein get well. My grandparents helped, but other people did, as well. But Einstein was thankful to my grandparents for their efforts, and that is how my grandfather was able to write a biography of Einstein, “Einstein: Einblicke in seine Gedankenwelt”, which was published in 1921, and later published in English as “ Conversations with Einstein”.

What does this have to do with me? Well, the friendship was passed down to his son, Richard (my father). But also Einstein also had gotten to be friends with a man, Emanuel Lasker, who was the chess champion of the world from 1894 till 1921. Now Martha, Lasker’s wife by marriage, had a niece, Ruth Bamberger. One day in November 1924, the Laskers had a party where Richard was invited. So Richard and Ruth, my mother, were introduced. They got engaged three weeks later and married in April 1925. I believe that Einstein even sent them a wedding present. In any event, Einstein was a personal friend and we’re very proud of it. I was fortunate to have inherited this friendship.

Concerning education, my father studied law. He got his degree in Heidelberg, and during World War I, he was a lawyer working in the German raw materials division because the Germans did not have an easy time getting raw materials with the British blockade.

Behrman:

Right.

Moszkowski:

He worked under a man named Walther Rathenau, who was a famous industrialist and who later became the foreign minister in the Weimar Republic before he was assassinated in 1922, by some proto-Nazis. Rathenau helped my father get a position as lawyer with the German Reichskreditbank. Also, through Rathenau we got our apartment in the Kurfürstendamm in Berlin, so all that is part of the history.

My mother, by the way, had a quite difficult childhood. She had a brother, Hans. Both of them had it quite rough, even before World War I, because their parents’ marriage, (my grandparents, Ludwig and Gertrud) had broken up. There were somewhat scandalous circumstances which I don't have to get into here. So my mother had it quite rough. She had to go to Switzerland during the war because of the food shortages. I don't know how much of a formal education she was able to get, but later she was raised also by an outfit called the Mosse- stift which helped orphans. The situation was quite tragic, but Ruth survived. After the war, she got a job as secretary, and then, after marrying my father, she was a wonderful mother and she really arranged the house beautifully. She was an amateur interior decorator, and later, when we came to America, she built up a business making lampshades.

So would it be okay if I start now talking about my own childhood?

Behrman:

Absolutely, and if you do recall something that you wanted to have said, we can certainly add that in.

Moszkowski:

Good! Now before we go on, I would like to ask: How are you going to handle this? How is this going to be transcribed? Can you tell me a little bit about that?

Behrman:

Certainly. So I will send the recording to a professional transcriber. Then that transcriber will write everything down essentially verbatim. I will do a first pass through it to correct some basic spelling mistakes, things of that nature. Then the transcript will go to you, and that’s your opportunity to add things that you would have liked to have said, or correct anything. The final transcript will have essentially your approval of it as it looks before it is published or deposited at the library.

Moszkowski:

Okay. Let me ask you something that I noted about the AIP policy. The material which you're going to send me—namely, basically a written transcript—of course I have to go over it, and hopefully any simple spelling mistakes you will have caught. But there are inevitably going to be some words where it isn't quite clear what they mean, But the question is how confidential is this material? Now obviously, this is not going to be, in the old expression, shouted from the rooftops. I’d never dream of doing that. However, I would like to be able to go over this with my spouse, Esther, whom you have recently talked to this morning, because she catches things. Esther used to be a copywriter in San Francisco.

Behrman:

No. When it comes time for you to edit the transcript, you may show it to whomever you wish to get their suggestions and feedback on it.

Moszkowski:

Glad to hear that. I thought so, but I wanted to confirm it. So let’s go to Steve Moszkowski. I was born in 1927. I’m an only child, and this was Berlin 1927 during the era of the Weimar Republic. I don't remember my first couple of years. Probably my life was pretty normal. I remember—maybe not directly, but in retrospect---that when I was three or four I didn't mind walking on the streets. I went to school myself and did not need an escort. It was a Montessori school. Montessori had methods of learning that were a little more advanced than some others, allowing the student to develop on his/her own. Have you heard of Montessori yourself?

Behrman:

Yes, I have. It’s become popular in the United States.

Moszkowski:

Excellent! We all know what happened in 1933. However, my life was not disrupted even then. Things for me were OK until 1938, the Kristallnacht. I was not afraid to walk on the streets. The only time, in fact, that I remember having some unpleasantries with the police had nothing to do with politics. I think I was in 1932. I was riding a bicycle. My balance was not very good. In fact. it’s gotten worse over the years. So I fell down on a big street, interrupting traffic. The police were not very friendly about this. I could have been endangering others. But I did not get hurt.

You may wonder how did we do in the Third Reich. My family and I were highly assimilated Jews. In fact, my father had been baptized as a young man. I was baptized at age six, and this was arranged by my family. Of course by Nazi law we were declared Jewish. But my father and I considered ourselves Christian. My mother was a totally non-practicing Jew. Berlin was more enlightened than some other parts of Germany, especially the rural areas. Most of our friends also were highly assimilated Jews. So my life was actually quite normal. We lived on Kurfürstendamm. The building where we lived (#35), was destroyed during World War II, Later, it was rebuilt and it became the Hotel California, quite expensive.

The Nuremburg Laws came into effect in 1935. The Nazis gradually increased the pressure on people they deemed Jewish. So my father, for instance, had to retire in 1936 on a pension. But as far as I know, we did not have financial distress. In fact, my parents and I took trips to other countries. All of us took a vacation in Holland once in 1936, and during the following year, my parents visited Italy. On that occasion, I was very jealous being left alone in Berlin with our maid, who was very loyal. But my life was not disrupted, at least to the extent that I was aware of. Obviously, my parents, and especially my mother shielded me from learning some of the unpleasant things that were going on, and I was not very curious about these matters. In fact, politics and sex were subjects that were just off-limits. That meant I didn't think about them, at least consciously. It wasn’t like “Oh no, you're not supposed to think about ….” Obviously, I was quite naïve. I didn't even know a number of things like, for example the F word. I didn't even know what it was until I came to the States. Number two, I did not know till coming to the US what the word Nazi means. Of course, Nazi is now an extremely derogatory word, but the Nazis didn't like this word even then. They called themselves National Socialists. I remember being at a public school from 1933 to about 1936, where there were the usual discipline problems. It was only boys in the class. There was the usual naughtiness. But there is one story I would like to mention, about the legend of the The Pied Piper of Hamelin. I recall that the teacher talked in some detail about that story. In retrospect I wonder, if just perhaps the teacher was trying to send a message “between the lines” to the students: Be careful of the Pied Piper. One can make an excellent case that there actually was a Pied Piper around who was in fact the dictator of the country. As history shows, in 1941, with the attack on Russia, the Germans were, in a sense, led over the cliff Of course, the story was a German folktale and so a teacher under investigation for subversion could claim that the folktale has nothing to do with modern times. That might or might not convince a suspicious Gestapo questioner.

In 1936, I believe that this school I went to was basically aryanized. Jews were required to get education elsewhere, so there was a school set up in Berlin, the Goldschmidschule for non-Aryan Christians. I went to that school, which was quite good, from 1936 to 1939. I should add that when I left, on the certificate it stated that I am a very religious person. I’ve always believed in God, and to me, the difference between Christianity and Judaism is not worth fighting about. Clearly many people stress the differences much more. One other thing I remember about Berlin is that I used to collect stamps and had a lot of them. I think the stamp shop was in a different part of Berlin than where we lived.

In 1935 or 1936, we moved from Kurfürstendamm to a nice villa in the Grunewald, not far away. That’s where a lot of wealthy, assimilated Jews lived. The Grunewald was a very peaceful place, but over time the Nazi rule tightened and the anti-Semitic policies became worse.

We had a maid, who was not Jewish, and because she was 45, was still allowed to work for us. After the Kristallnacht in 1938, things deteriorated drastically. I recall on the day of the Kristallnacht, our maid met my mother and me on the street when we were coming home. She was in tears and said my father had been arrested. Soon afterwards, my mother went to her lawyer and told him that yes, we are now ready to sell our house to the Nazi Labor Front that had a big building across the street and wanted to expand, but that she (my mother) didn't know anything about finances and needs her husband to sell the house. This may or may not have been the reason my father was discharged two weeks later from the KZ where he had been taken. His health, his physical health was not negatively affected as far as we could tell, but it did really, in a sense, break him psychologically for a while. He recovered later, but it was a really traumatic experience, the two weeks in the camp, Sachsenhausen. So we had to get out of Germany and luckily we were able to do this in 1939 and come to America.

Now let me mention a couple of things. I have always been interested in numbers and still am. I used to keep notebooks with very high numbers. I was quite one-sided and not athletic or that sociable. My mother was quite worried about my not “fitting in”, and she actually wrote Albert Einstein, who by then was in Princeton, and asked him:. “What shall we do with Stefan?” Einstein wrote her back: “Leave him alone! He’ll develop.” That, I think, got my mother to push me a little bit less on fitting in and helped to legitimize my own way of doing things. I never became a dean or administrator. So, Einstein had a big effect on me even then.

Also very important for the fate of my family was that Ruth’s brother John (who was called Hans before) and his wife Ilse had already immigrated to America, in 1933. Aunt Ilse had worked for the Ullstein publishing company. One of the first things the Nazis did when they came to power was to purge media that were not friendly. The Ullstein company was quite liberal, and was owned by Jews. So Ilse Bamberger had a taste of what some of the Nazis did right away. In fact, they literally kicked her out of her office. I still recall when John and Ilse got married. He had been a bartender on the Hamburg-America line even before the 1930s. So when they got married in Berlin on October 23, 1933, I wrote a little poem for them, and it was quite an occasion. Shortly afterwards they left for America. At first, John had to struggle quite a lot to manage. But he became a very successful automobile insurance salesman, and when it came time for us to leave Germany, he actually was able to write an affidavit for us. This really helped when we went to the American consulate in Berlin shortly after Kristallnacht to get a visum for immigration to U.S. But we had to go to Holland first to wait. There we stayed with friends.

After nine months, we finally got the visa and came to America in January 1940. In retrospect, we were very lucky to get out of Europe in time. Visas were hard to get, However, after the Kristallnacht, people in Western Europe and America were outraged at what had happened. There were photos taken of synagogues burning and grisly things like that. There were a lot of protests. President Roosevelt withdrew the U.S. ambassador and so on. But basically, the West didn't really take any specific meaningful action against Germany on that occasion. But one good thing the U.S. did was to increase the quota of Germans that would be able to come to America and cut down the waiting time. We were in Holland when World War II broke out, but we were able to take a ship, the Noordam, to America and arrived in New York on January 4, 1940. My parents and I stayed in New York, with my great-aunt Martha and her husband Emanuel Lasker, for the month. We also had a chance to visit Albert Einstein. Einstein explained to me about the curvature of space-time, like a membrane that stretches. And he autographed a mathematics book for me. Well, I went to a summer camp later that year, I made a belt for Einstein. And we had quite a bit of correspondence with Einstein during the 1940’s.

After a month in New York, we came to Chicago where my uncle and aunt lived, and that’s how I continued with my education. I went at Hyde Park High School, a very good high school on the South Side. Then in 1942 I was given an opportunity to go to the University of Chicago. Have you heard of Robert Hutchens?

Behrman:

Yes.

Moszkowski:

Ah. He had the idea of a four-year college where students enter as juniors in high school and they finish the two years of high school and the normal four years of college all in four years instead of six years. So in 1942 I was able to start studying at the University of Chicago. I was living at home. The fact that there was a war on did not affect us that much directly. There was, of course, rationing. We followed the news avidly, but although we were officially considered as enemy aliens, the treatment of folks who had come from Germany was radically different than what happened to Japanese Americans. We did have to give up our camera for the duration, but got it back in 1945. I don't really recall any really serious deprivation.

I must have gotten a pretty good education. I was always very good in mathematics, numbers, and also in physics. Mathematics was my primary field, but I wasn’t so good in English and even social sciences and so on. There was one experience in 1944 which I want to share because it tells something about my Dad. There was a take-home exam in the English class, and they give you three passages. You were informed that two of these passages are written by the same author. Discuss which they are and your reasons for concluding this. So I took the exam home and started looking at the literature. By pure accident I discovered which two passages had been written by the same author. I did not have to figure it out. I discussed the matter with my parents, and my father absolutely insisted that I must definitely mention that I had found the answer by accident, not by research, which were the two correct passages. I reluctantly did so, but still got a D in the class. Fortunately, because of my good record in mathematics, physics, and sciences, I did okay. I wasn’t a top student, but my overall academic standing was quite good.

I recall one other even more notable experience: The first quarter for me at the U. of Chicago was fall 1942, and, of course, like other students, I had gym lessons which were in Stagg Field. Some places were blocked off, but I didn't ask questions about it. Of course, now we know what was going on there.

Behrman:

[Laughs] Yes!

Moszkowski:

I was lucky to be at a top school, but I didn't fully really appreciate this at the time. Also I would not rule out the possibility that my admission to the four-year college program was positively influenced by our having coming from Germany as refugees. Now, any questions so far?

Behrman:

Did you have any teachers that made a particularly large impression on you in high school or college?

Moszkowski:

Well, I cannot really say that there were teachers like that. Not at that time. I think that the teachers that had a big influence on me that I remember came later.

Moszkowski:

Let me now tell you how my parents fared before and after coming to the U.S. I was very lucky. Immigrating to the United States and the circumstances before did not hurt my education (that I know of), but my parents had it somewhat rougher, although both of them managed. My mother, even shortly before immigrating, figured she would have to be able to earn some money, so she learned something about making lampshades. When we came to America, shortly after coming to Chicago, she started a lampshade business. She rented a shop close to where we lived and she built up a business that was fairly successful. That helped us quite a bit, financially.

My father had a rougher time. He had been a lawyer at the Reichskreditbank in Berlin, and he was able to keep his position there for three years after the Nazis came to power. He had served in a civilian capacity under Walther Rathenau in World War I, his work having to do with making sure that Germany had enough raw materials, which was crucial to be able to maintain things in Germany.

In 1936, he was retired on a pension, and that was the end of his career as a lawyer in Germany. Now as far as I know, while we were in Germany, we did not suffer financial deprivation—at least I didn't. Obviously if we had stayed any longer, that would have been totally different.

Behrman:

Right.

Moszkowski:

In the United States there was a terrible depression, but President Franklin Delano Roosevelt accomplished an extremely important thing: He gave the American people hope that things would get better. He tried to do a lot of different things, of some of which actually worked, but others did not. The whole venture is known as the New Deal. Although unemployment went down from the catastrophic 25% level of 1932, it was still above 14% as late as 1940. It was difficult to find work even then. My father was not able to get a job immediately, and although he had been a lawyer, law is a profession that depends to a large extent on the practices of the country where you are living. He was already 55 and he did not really try to make it again as a lawyer. But in 1941, more than a year after we came to America, he did get a job as accountant for a well-known law firm in downtown Chicago, Sonnenschein and company, and he worked there until he died in 1959. He finally established himself, but it took a long time. That’s how bad the Depression was. By 1941, World War II was coming, and the country was mobilizing, which freed up certain jobs.

Now one other thing. After World War II, my father got restitution from the successor to the Reichskreditbank. Also, the postwar German government under Konrad Adenauer did in fact make restitution to German Jewish refugees. There was a huge amount of paperwork that my father had to deal with, but he did get a good restitution, both from the Government and the Reichskreditbank, both possibly part of the same package. When my father died in 1959, my mother still had the lampshade business, but that alone would not have been enough to support her. She did get a good pension from Germany.

The payments from Germany were rather unique. I don't believe that generally refugees get restitution from the country from which they had fled. Germany was a kind of special case for a number of reasons. First of all, the Allied victory in 1945 was complete. There was no ambiguity, unlike what had happened after World War I. The Germans knew they had been defeated. I recall that many years later, when I was at a conference in Germany, I stayed at a hotel near the train station in Frankfurt-an-Main, and the hotel owner told me that 40 years before, they could see all the way to the Main River, which was about a mile distant. That’s how heavy the Allied bombing had been.

Behrman:

Wow.

Moszkowski:

Practically all Germans did not want anything like that to happen again, and that made the country a little more receptive to certain things because the restitution programs of Adenauer were not universally accepted in Germany. It was a complicated story, but he got it done. The regime also made restitution to the state of Israel, and Israel became a good diplomatic friend of Germany; it still is.

Behrman:

Right.

Moszkowski:

One of the less savory things that happened was that de-Nazification was basically stopped somewhere around 1947 when the Cold War broke out. It was seen that Germany would be an ally of the West against the Soviet Union. The community of German Jewish refugees was extremely unhappy about this, but probably in retrospect, it was the best thing to do. Of the former Nazis who were now integrated into the Bundesrepublik, the vast majority of them saw the error of their ways and did not try anything like what had happened again, and Germany was really rebuilt. So that’s the story about my parents. Any questions?

Back to my own development. In 1945, World War II ended. The U.S. and its allies had won but now what? There was some worry that with the demobilization, we might get unemployment, like what had happened after WWI. Fortunately, that did not happen this time, but there was a general public letdown, such as often happens after a big event.

That applied especially to me, but also for more personal reasons. For example, at the time, I had problems relating to girls. Some of that was pure immaturity. A lot of boys have problems of this kind. I started getting somewhat depressed. So to make a long story short, early in 1946 I got a notice from the draft board. I was almost 19 at the time. Some of my friends got deferments. Deferments for scientific reasons were not that hard to get, but I reacted differently. I went to the draft board one day in February 1946 and told them, “Take me immediately. I want to get out of Chicago.”

Behrman:

Ah! [Laughs]

Moszkowski:

They obliged. Nine days later, I was inducted, and after a couple of days deciding where they would send me, I was assigned to Camp Lee, Virginia. I actually survived basic training, and a little bit later I was in the Quartermaster Corps and learned typing. It turns out decades later that knowing typing is a great help in the computer age.

Meanwhile, my mother was upset that I had so abruptly decided to go into the Army. She was not sure I could make it through basic training. One day during summer 1946, I was called into the commanding officer’s quarters and told that I would be transferred to Chicago. So who was the person who had arranged this? I never learned the entire story, but what I can piece together was this: My mother, unbeknownst to me, had contacted a chemist friend, also from Germany, Mel Freedman, who was working on the secret Manhattan Project. Freedman knew Robert Sachs, who was a big shot in Washington. Sachs had worked on nuclear physics, In fact, he had taught the subject to Hyman Rickover of nuclear submarines fame, but I don't know details of that. During WWII, Sachs worked on ballistics in Maryland, but after the war ended he became involved with the Manhattan Project, in particular, the Metallurgical Lab at the University of Chicago. Robert Sachs had me transferred to Chicago. He picked me up and gave me a ride to the lab every day. I got to know him quite well.

One incident I remember was that one day, shortly after coming back to Chicago, I had a terrible toothache. In the Army, they used to line you up often and give you an exam, but a lot of the exams, including dental, were pretty cursory. I must have developed an abscess, but didn't really notice it that much except that this one day it really got bad. So I went to a dentist and he promptly extracted the tooth. I didn't have bad effects from it. Robert Sachs was going to pick me up. But he wouldn't take me. He said, “You’ve got to go home.” I was feeling good enough to have gone. Even the next day he was concerned, but I had no bad effects from the extraction of the abscessed tooth.

Moszkowski:

So, I was in Chicago living at home in a uniform, and every day I went to the Metallurgical Laboratory to work on things there. That meant pounding the calculator. (Mechanical at the time, like Monroe or Marchant.) It took me some time to really learn what I was doing and how this fit into the bigger picture. Robert Sachs had been the first student of Maria Mayer back in Baltimore at Johns Hopkins University in the 1930s, and had written a paper on the triton with Maria Mayer back in 1938. So to make a long story short, that’s how I got interested in nuclear physics.

Robert Sachs also knew Edward Teller, with whom I interacted later. Sachs was instrumental in helping to set up Argonne Lab, around 1947, and left Chicago for the U. of Wisconsin in 1948. Sachs wrote a classic book on nuclear theory in 1953, and a little later he became a particle theorist, making important contributions on form factors.

I didn't really stay that much in touch with him later, but I do remember going to a party for him in Chicago. It was in honor of his 65th birthday in 1981. I first went to a computer expo in downtown Chicago and then went to the party for Sachs at his home. I remember Eugene Wigner gave a talk on his recollections. Then in 1996 on the occasion of Sachs’ 80th birthday, I attended an event, also at his home, after I had been at the APS meeting, at a session on Women in Physics where I talked about Maria Mayer. So those are some of my memories of Robert Sachs. They were very pleasant. It’s clear that Robert Sachs had an enormous influence on my own career. By the way, the first paper I ever wrote was with Sachs in 1948: “The Deuteron with Gaussian Potentials.”

Behrman:

Your first paper, very interestingly you worked with Robert Sachs on it, so I was wondering if you could describe Robert Sachs as a researcher, especially given that you were able to work with him on a paper?

Moszkowski:

I wasn’t familiar enough in a detailed way how he did things, but he was my boss, we got along, and it worked out fine. So it’s a little hard for me to answer that question.

One little detail: I don't believe that Albert Einstein ever knew that I had been drafted, much less the idea that I had asked them to take me because Albert Einstein was definitely against militarism in any form, not just the Nazi version. It is true he recognized that the world could not do business with Adolf Hitler and he had to be fought, but in general, Einstein was on the side of non-violence. So joining the US Army after the war was over would be problematic for him. But we never talked about this.

Moszkowski:

It is interesting that Maria Mayer herself emigrated from Germany. She came from a family of academics. They had to leave Silesia after World War I, or even maybe a little before. There were unpleasantries of different types. I think it is fair to say that Maria Mayer considered herself a German patriot. She had contempt for the Nazis, but she was German and she surely knew that I had come from Germany, too. So there probably was some bond between us. This is not insignificant for my memoirs. For some reason, probably in my upbringing, I sort of needed a mother figure at different stages of my life. Maria Mayer was an intellectual mother figure. Right after the Basic, Edward Teller kindly had me visit Los Alamos. Also, Maria Mayer arranged for me to get a part-time job at Argonne Laboratory about 20 miles west of Chicago, where I did some work on opacities. These activities were classified. I don't think the work was all that significant, but both were interesting experiences.

Later in 1950 Maria Mayer sent me to visit Duke University in Durham, North Carolina where Lothar Nordheim was on the faculty. He had also independently worked on the nuclear shell model, but it was Maria Mayer who uncovered the spin-orbit coupling origin of the magic numbers. Nordheim was very interested in applying the model to nuclear structure problems. All three of us, Mayer, Nordheim, and I wrote an article in Reviews of Modern Physics on applications of the shell model to beta and gamma decay. The visit to Durham was a very pleasant experience for me. Anyway, to make a long story short, in 1952 I got my PhD from University of Chicago.

I think one of the questions that’s listed regarding preparation for the interview was what did you have to do to apply for a job. My answer is that I was enormously lucky and did not have to struggle to get a position. Somehow these things were arranged. Probably, because of Maria Mayer’s discovery of the shell model, she had enough prestige that she could recommend someone and they had a good chance at an academic job. It is not like that now, but that’s the way it was then. So I got a post-doc at Columbia.

Behrman:

Would you like to take a break now? We’ve been talking for approximately an hour. I would like to ask you more about your impressions of Maria Mayer, Edward Teller, and others whom you interacted with then. What, for example, was Maria Mayer like as a mentor? How did she mentor you?

Moszkowski:

That is an interesting question. I don't think we talked that much about matters other than the thesis. She made some suggestions, I guess she just guided me. I might have asked questions and she would explain how to deal with them.

So both Maria Mayer and Edward Teller had a big influence on me. The fact is that Edward Teller came from Hungary, and the role of Hungary in physics is a very interesting subject itself. I may say a little more about that later. I think it’s very good that today we got up to about 1952, which was when I got my PhD, which also happens to be when I got married, on August 29, 1952. This was, of course, a major transition in my life, going to Columbia and then later to UCLA.

[Part 2]

Moszkowski:

I had done very well at the University of Chicago, but the others at Columbia were in a similar position as mine; they had also done very well wherever they went. It was a little bit like a class where all the people had been valedictorians in their own high school. So for some time it was not that clear to me what to work on. Columbia was more into field theory, which I did not know anything about, and not really that much into the nuclear shell model. Thus I was floundering somewhat at the beginning of my Post-Doc. But I was asked to give a lot of seminars on the shell model,

It took a little time for me to find my footing. One person who was of great help to me in this respect was Madame Chien-Shiung Wu, who was at Columbia. She took an interest in me because I had worked on beta decay. She was an expert in the field doing landmark experiments. So in some sense, she took me under her wing. Mme Wu had had the idea of writing a book on beta decay. She figured that I would be a good coauthor and I agreed, and, in fact, Madame Wu and I actually wrote the book on beta decay. After long delays, it was published in 1966. Writing the theoretical part of that book really helped me later, because of the modern developments with the weak interactions and now with neutrinos. This is not my field of specialization now, but at least I know a little bit about what is going on there. By the way, Madame Wu—that’s what she’s called generally was very conscientious and worked hard. She also expected people that worked with her to work hard. Not everybody was so happy about this. Well, maybe what I should do is jump ahead on this thing and then I’ll go back to ’52. In 1957, of course, parity nonconservation came on the scene. Madame Wu directed the cobalt 60 experiment that put it on the map. That’s, of course, quite a story. I was already at UCLA, when I got a call from somebody from the New York Times asking me about it because I was associated with her.

The other thing was that at Columbia, actually, there was beginning to be some interest in deformed nuclei, as had been first suggested by Rainwater there. Bohr and Mottelson, from Copenhagen, improved on the shell model by allowing for deformations and collective motions. That turned out to be a tremendous advance, and later in 1975 they got the Nobel Prize for it. So the whole field of nuclear theory was under a very active development, While Columbia probably wasn’t at the center of all that, there still was a lot of interest in these developments.

One other thing I would like to mention here. My family knew one physicist who had come to America in 1941. His name was Fritz Reiche. He was an old-timer, having done lots of work on atomic physics back in the early 20th century. He had developed the Thomas-Reiche-Kuhn sum rule in the old quantum mechanics before Schrödinger. He was a highly assimilated Jew, but being of Jewish blood was enough for the Nazis. He was able to get out of Germany just in time, before the Nazi authorities forbade any more emigration On the way out from Breslau, in Berlin, he talked to a an astrophysicist, Houtermans, which is an interesting story in itself. Basically, when he came to America, he communicated what he had heard from Houtermans, which was that in Germany, they were thinking about using plutonium in a nuclear weapon. Houtermans was trying to send an alarm to the West, but apparently people didn't really pay that much attention to Reiche, though they did get serious about the Manhattan Project. Reiche had memorized what Houtermans told him in Berlin. All this is not really about my own memoirs, except that we knew Fritz Reiche. I visited him a number of times in New York. My parents and I remained good friends with him and his wife. We have photos with them. So this is a nice memory.

Moszkowski:

Let me mention a couple of new ideas. One has been extensively covered in the literature, the backstory of the Einstein-Eddington contributions. Eddington understood the value of getting a report into the news of the success of the 1919 expedition to observe the solar eclipse, confirming Einstein’s theory of relativity. By late 1919 society was very disillusioned. The War had not made “the world safe for democracy” as President Woodrow Wilson had hoped, and the flu epidemic had killed more than half a million Americans. The good news about the expedition results would be just the thing to lift people’s spirits. The success of the expedition could be seen as one way to help reconcile Germany and England. Einstein had been a pacifist in Germany, and Eddington had been a conscientious objector in England

Regarding my problem of figuring out what to work on, one of my colleagues suggested that I look at a recent book by Arthur Eddington on Fundamental Theory. Eddington had greatly helped to popularize Albert Einstein and had led one of the expeditions to the 1919 eclipse. He was a highly opinionated person, like many of us are, and one of the opinions was that he really believed in general relativity before other people did. History proved him right on that one. However, about 20 years later, he got hooked on an idea about fundamental theory to see if people could unify the interactions in some way. It happened that I got somewhat interested in Eddington’s fundamental theory. But if I had pursued that interest, I wouldn't be talking with you now because my career would have been wrecked. Eddington’s theory had to do with developing an explanation of how you could get the fine-structure constant, a number we now know is 1/137.06. This is a very important quantity, of course, in atomic physics and more generally. Eddington thought he had developed a theory of how to get that number, except at the time, the number wasn’t known that precisely. He thought it was 1/136, and when he worked on it, that was the closest accepted value. What he did was, to some extent, to use numerology. He was quite charismatic also in his book. So, someone a little naïve like me, and anxious to find something to really get excited about, latched onto this for a short time. Which takes me to my last visit to Albert Einstein in early 1953. Einstein was very unhappy about what was going on in the world. Also, McCarthyism was intimidating a lot of people. But when I mentioned my own interest in Eddington, Einstein practically ordered me to stop working on this and I obliged. I didn't work on this anymore. More recently, I learned that a few years previously, Einstein had some correspondence with Schrödinger. To Einstein it looked like Schrödinger might be going off the deep end. In any case, Schroedinger straightened out. Later he wrote a book “What is Life?” that became very important in genetics. But probably dropping Eddington’s ideas saved my career. .

The last thing I want to mention, at Columbia was there was a physicist, Charles Townes, who later shared the Nobel Prize for his work on lasers. Townes had broad interests in Physics, and in particular, on how his work related to nuclei. By the early 1950’s it had become clear that many nuclei were not spherically symmetric, but deformed, and also that there was a preponderance of positive quadrupole moments. Nuclei tended to be prolate (football-shaped) rather than oblate (disk-shaped). Townes and I wrote a little paper on the tendency for positive Q. This got me involved in real nuclear theory again. So the point is that at Columbia, at first I was floundering around, but later I worked on different things that looked and turned out to be promising.

A very important development for me was this: One day in early 1953, Bob Finkelstein, a young Physics professor at UCLA, visited me at my office at Columbia. I had known him back in the Manhattan Project days. He mentioned that at UCLA, they were looking for an assistant professor in nuclear theory. I turned out to be one of the candidates, and was fortunate to get the position. That summarizes my stay at Columbia.

Behrman:

Were you also consulting for the Rand Corporation at this point in time?

Moszkowski:

That was when I came to UCLA. I began to consult with them, and although it required a secret clearance, I don't recall doing classified work at Rand. My work was on different little projects. I wrote a short report on the Tietz potential, which is a good approximation to the Thomas-Fermi potential for atoms, and also one on the Mossbauer effect. This work was interesting, and it helped with the finances.. I met several well-known physicists, and learned some new things.

After 1970, my work at Rand ended, but I started to consult at Livermore National Lab, thanks to Stewart Bloom who had also graduated from the University of Chicago, a couple of years ahead of me, and was now working at LLNL. (The first L is for Lawrence, who had been instrumental in setting up the labs both at UC Berkeley and at Livermore.) Bloom had a small group of theorists working with him, and I consulted with them doing nuclear shell model calculations using different effective interactions. One example was a set of Skyrme interactions with a finite range density dependence. This work, which lasted until 1998, was quite stimulating.

Behrman:

Right. So yes, go on, please, with what it was like to begin work at UCLA.

Moszkowski:

So I came to UCLA in the fall of 1953. We settled in West LA. At that time, the rents were very low, $75/month for an apartment. It was a nice atmosphere. One of the first developments was that I was asked to write a chapter for a book on alpha, beta and gamma decay, reviewing the theoretical status of gamma decay, which had been the subject of my thesis. So I got a fast start at UCLA, which was very nice. Also, Bob Finkelstein would often take me along when he drove to Cal Tech for a colloquium. He and l Iater wrote a paper on the difference between the Fermi and Gamow-Teller coupling constants in beta-day. (Bob Finkelstein passed away in August 2020 at age 104).

Shortly after my arriving at UCLA, Teller briefly came back into my life. In December 1953, there was an APS meeting at Stanford. A couple of my colleagues and I drove up there, and it was a nice meeting. Edward Teller was there. He was very enthusiastic about an idea that he was working on with a colleague, Montgomery Johnson, on a kind of mean field theory of nuclei. Are you familiar with the Walecka model that came out in 1970?

Behrman:

I’m not. Could you tell me about it?

Moszkowski:

Okay. Well, no. That’s not the start. It’s a mean field description, relativistic mean field theory of the nuclear potential.

Behrman:

Okay.

Moszkowski:

The relativistic mean field model has evolved quite a bit in the meantime. What Teller did was sort of a predecessor of models that would come along a little bit later. Anyway, Teller was very excited about it, and communicated that excitement to me. The shell model was was working well, but there were questions. How do you get a strong spin-orbit coupling? You can make a good argument, I mean in details, that if you take nucleons and the relativistic mean field and scalar and vector potential, you can get some of the features of the nuclear potential, including a strong spin-orbit coupling. So this was something to get excited about. At the meeting Teller and I had discussed that perhaps in a short time we could start a collaboration working out some of these things. But it never happened, and here’s one reason why. Four months later, there was a meeting of the American Physical Society in Washington, D.C., the annual meeting, and I had been starting to work on deformed nuclei. I presented an abstract there on deformed nuclei, but found out that Hill and Wheeler had gotten some of the same results a little bit earlier. So when I got back to UCLA, I developed a different method for treating spheroidal nuclei and published a paper on this in 1955. A more important development which was also disappointing for me was that Teller had gotten involved in the Oppenheimer case.

Behrman:

Ah, yes.

Moszkowski:

I feel that whole Oppenheimer matter was a tragedy for a lot of the people connected with it. It is a matter of record that Hans Bethe attempted to persuade Edward Teller not to testify against Oppenheimer. Oppenheimer would have been relieved from Government service anyway for other reasons.

The policies of the United States in the Eisenhower administration had changed in a direction which Oppenheimer opposed. But for a number of reasons Teller felt he had to testify and he did. That made him basically an outcast among many, maybe even the majority of theorists in the community. The point was that Teller did not work on the nuclear mean field anymore, so nothing came of these dreams from December of 1953. Later around 1980, I started to do serious work on mean field theory. In my opinion, the history of nuclear theory might have been different and better if Teller had not testified against Oppenheimer and had stuck with nuclear physics. That’s my own opinion. Let me put this another way here. Physics is not everything, and sometimes, you have to put other things ahead of physics. Different people have different views about matters like this. Later I want to mention Teller again in connection with the SDI.

At UCLA, I also started to work on other aspects of the nuclear shell model. One topic that I pursued, in particular, was deformed nuclei, which I had gotten started on at Columbia with Townes. In fact, within a couple of years, I began to take on graduate students. They worked on different aspects of the nuclear shell model. including deformed nuclei. And in 1957, I was able to hire a postdoctoral scholar for a year from Japan, Taro Tamura, an expert on deformed nuclei. In 1958, he published a paper on residual delta interactions, in deformed nuclei. The field producing part of the interactions leads to the deformed average potential, while the delta interactions can be taken as an approximation to the residual interactions. Tamura’s paper may have been an important stimulus for me to start work on the surface delta interaction. Also, Charles Gallagher, a post-doc at Cal Tech, and I had a paper on odd-odd deformed nuclei, in which we applied the Nordheim coupling rules which he had published a decade earlier for spherical nuclei.

Did Maria Mayer derive the shell model from fundamental principles? Absolutely not. Modern nuclear physics starts about 1932 with the discovery of the neutron, and then neutrons and protons were considered the fundamental particles in nuclei, Now we all know about the atomic shell model, so some folks thought that perhaps something like this happens in nuclei. Even without knowing about the forces, you get some kind of shell model, and at least some closed shells like for Z= 2 and 8, that were apparent even in the early days. On the other hand, it didn't take very long for folks to learn that the nuclear forces are quite strong, even though they did not know the details. There were some major false leads. For example, in 1936, Yukawa came up with the idea of nuclear forces being mediated by meson exchange. That could account for their short range. Sure enough, a meson was discovered the following year. But the more people learned about the properties of this meson (now known as a muon), the more they realized that the muon couldn't be the carrier. There was something wrong with that meson. It was simply a massive electron. Then World War II intervened and the physicists had to work on higher priority subjects for some years. But in 1946, nuclear theory got started again. In 1948, the pion was discovered. So that was the carrier of the nuclear forces. However, Yukawa had gotten very famous for proposing the idea of meson exchange, which turned out to be crucial to the field.

The other point, of course, was this. Does the nuclear shell model make sense? How can you have a shell model when you have strongly interacting nucleons? In the middle 1930s, Niels Bohr developed a different model—basically, a liquid drop where nucleons are strongly coupled, like molecules in a liquid, and you do not have independent particle motion. This model was not inconsistent with what was known about nuclear masses. Indeed, such a model was used to derive, first, the Bethe-Weizsacker semiemipirical mass formula, and slightly later, a theory of nuclear fission. So the liquid drop model was more or less the standard, at least up till 1949. While Maria Mayer did not derive the shell model, she found strong empirical evidence for it, in particular for closed shells at proton and neutron numbers 50, 82 and 126. And shortly afterwards, she was able to explain these numbers by invoking a strong spin orbit potential, to supplement the more standard central nuclear potential felt by each nucleon. However, to this day, there are still some problems in deriving these results from more fundamental principles.

When Maria Mayer gave evidence for the magic numbers, the evidence was so convincing that people could not argue that it was just a coincidence. Then Mayer, and Jensen independently, showed that if you have a strong spin-orbit coupling, you could explain how you get magic numbers 50 and 82. Of course, that part of the story is widely known. When I was a graduate student at Chicago, I accepted it without hesitation. In fact, I was only dimly aware of the arguments that Niels Bohr and company had made against independent particle motion. For me the nuclear shell model was the answer.

It is well known that Maria Mayer wrote three classic papers on the shell model in 1948 and 1949. The first spelled out the evidence for the magic numbers, and the second gave the spin-orbit explanation. The third paper deals with pairing—the fact that even A nuclei are a little bit more bound than odd A nuclei. This, of course, plays a huge role in nuclear fission. Thus slow neutrons absorbed by the odd A nucleus uranium 235 can lead to fission. But getting uranium 238 to fission requires fast neutrons. The reason for needing this extra energy is due to the pairing effect. In 1949, Maria Mayer wrote the third paper on the shell model about pairing, and she used a really simple model for this, namely, delta, i..e., zero range, interactions between nucleons. She got some very nice results, and the reason I mention it is because that some years later, when I got interested in the problem, it changed my life. If you assume a zero-range interaction between nucleons—and never mind where it comes from, you just assume it—then you find that for two particles in the shell, you get a certain pairing energy. That’s fine. But what got Maria Mayer very excited was what she told another student and me in her office: She took three nucleons—say, in the f_7/2 shell—and calculated the energies of different J levels with a delta interaction, and in particular the J = 7/2 state of three particles. She used the old-fashioned Slater method, rather then modern group theory for the calculations, which were quite tedious. I won’t go into details here, but she found that that the energy for the J=7/2 state of a three-particle system in that shell f_7/2, can be expressed as the fraction which after tedious calculations comes out as 4004/1001 = 4. This happens to be the same as for two particles, namely j+1/2. So with this model, adding a third particle does not have any effect on the energy. No wonder she was very excited about this and similar results. In fact, a couple of years later, Racah and Talmi proved how you get these results as a consequence of the seniority group holding for delta interactions. They were able to give a group theoretical explanation for this. The reason I mention it is because this was something that stuck in my own mind, and I wanted to understand better what was going on here. I didn't really get seriously involved in this problem until about 1958. Yet, I was wondering all along, like I’m sure many other people were wondering, how do you get independent particle motion when your nuclear forces are so strong?

Unfortunately, Racah died in a freak accident some years later. But Igal Talmi became an one of the top nuclear theorists in the world. He pioneered in providing firm evidence for the j-j coupling shell model in nuclei, and in developing effective interactions.

Maria Mayer and, independently, Jensen, Haxel and Suess, (all of whom I met on at least one occasion at different times and places) put the nuclear shell model on the map because of the spin-orbit coupling and the fact that it is not that crazy to postulate that nucleons do in fact move somewhat independently in nuclei, in spite of the fact that the interactions are strong. This was quite a puzzle, and in some respects it still is a little bit of a puzzle, but we can now understand it better. Yet there still are questions. How do you get some mean field when you have strong interactions? I continued to wonder about it and am sure that other people did as well. In 1957, Weisskopf, together with Gomes and Walecka, wrote a paper where they showed that because of the Pauli principle, you could have strong forces between nucleons and still get something like independent particle motion. To some extent, that makes sense. That paper made a big impression on me. But intuitively I felt that it did not go far enough, that it was part of, but not the full story, In fact, that was probably one of the things that really drove my own interest during the late 1950’s. My family and I used to work jigsaw puzzles, and I joked with them about the shell model puzzle.

I have to confess that, at the time, I did not really know all that much about nuclear forces, especially all the refinements. I had had a nuclear physics course at Chicago, but at that point, my knowledge was pretty primitive. I had learned nucleons move independently in orbits, and I wasn’t worried too much about the details, at the time. For example, how does it make sense to have orbits when you have strong interactions? Maybe it’s just as well because if I had worried about it, I might not have been able to concentrate that much on learning all about the orbits. Sometimes knowing too much makes it hard to go on. Apparently, Maria Mayer, while an expert on atomic problems and statistical mechanics, was not all that familiar with the details of nuclear physics when she developed the nuclear shell model. I don’t know to what extent she had been influenced towards accepting the liquid drop model, but I suspect not all that much. Do you understand what I’m trying to drive at here?

Behrman:

Yes, about creativity and sort of thinking outside the box.

Moszkowski:

Eugene Wigner had pioneered in nuclear physics already during the early 1930’s. He was the first one to show, for instance, that if you just have an ordinary attractive interaction between nucleons, that cannot be the answer because the nucleus will collapse! You need something else to give you nuclear saturation. So some theoretical physicists started to wrestle with the problem of how you get nuclei not to collapse, but to have more or less the same central density and binding energy per nucleon. That’s a whole story in itself. Wigner was perhaps the world expert in applying group theory to atomic and nuclear problems. During the later 1930’s he investigated nuclear symmetries and generalized neutron proton isospin, SU(2), to supermultiplet symmetry, SU(4). The nuclear spin-orbit coupling violates this symmetry, and Wigner was originally somewhat skeptical. (He might have coined the term “magic numbers” with a not entirely positive meaning.) So when the j-j coupling model became established, Wigner was not. at first, too happy about it. It is interesting that Mayer, Jensen and Wigner shared the 1963 Physics Nobel Prize. But, in some respects Wigner’s ideas based on symmetry might have something of a last laugh. A cluster model such as the alpha particle model works quite well, and some aspects of j-j coupling might have been overdone, even though the basic idea has stood the test of time. The long standing problem of the 5700 year half-life for 14 C may be a case in point, as was shown some years ago by Don Robson.

By the late 1940’s a number of important results had been discovered, for instance, that at short distances there seemed to be a repulsion between nucleons (in addition to the well-known Coulomb interaction) . The repulsion was first proposed by Jastrow. So by the early 1950’s nuclear structure started to look like a complicated many-body problem. quite complicated, in fact. Then Brueckner theory came along, and Hans Bethe got interested in this problem.

I had a lucky break here. I started getting interested in the nuclear many-body problem myself and stumbled on something which is pretty nice. We know that the nuclear interactions are overall attractive. That’s how you get binding. But you have to have some repulsion at short distances. So you’ve got at least two components in the interaction: the repulsion and the attraction.

Most physicists handled the problem by splitting the potential into a short-range repulsion, especially if you have a hard but not infinite core, and the remaining attraction, and then worked with those two components. But I figured that this may not be the best choice for handling this problem so I came up with a little different idea. Namely that you take the short-range repulsion and a part of the attraction just so that the two together result in zero scattering length. Then you take the remaining attraction as the long-range part. If you make the separation between the two components in this manner, then the calculation converges much faster. This makes more sense, provided you’ve got central interactions. Now why do I mention central interactions? Because already early in 1939, it was discovered that the deuteron, the simplest two-nucleon system known, is not spherical. It’s got a finite particle moment. So the interaction must contain some non-central components like a dipole-dipole interaction which is not central. By itself, such an interaction would lead to heavy nuclei being extremely deformed, like a kind of giant deuteron.

Moszkowski:

That put a different spin on things later as I will discuss. Returning to the 1950’s, there was great progress in learning about how to handle nuclear forces, and the Brueckner theory was a very good way to try to deal with this. The method that I had mentioned about separating the potential into short-range and long-range part properly is a subset of Brueckner theory which makes things simpler. I’ll skip the details here. But when Hans Bethe learned about the role of my work on the separation method, he was rather impressed. Later he improved on the method with the so called reference spectrum. And it didn't hurt my career to have Hans Bethe sort of pulling for me when it came time for promotion.

Altogether, Hans Bethe had a big influence on me in wanting to understand the nuclear many body problem, and that’s how I developed the so-called separation method. He was, and still is, for me a wonderful role model. There is also the issue of safe nuclear power, which just may become important again during the 2020’s and 2030’s, as fossil fuels get phased out. Bethe expressed himself as being against nuclear weapons, but for nuclear power.

A photo of Bethe and me, is on the wall of my home office. The year was 1964, when he visited UCLA to give a talk. We had a friendly discussion at a coffee break, and in the photo, it looks like he’s sort of sizing me up.

Let me go back for a minute, and this is not strictly in chronological order. In the early 1930s, there were a few very talented physicists working on nuclear forces. It was a subject on the frontiers of Physics. But it was also at the very depth of the Depression, when it was by no means clear that democracy could survive. So for anyone to do research work in this or any other field was tough because we all have to make a living. Academic (and other) positions were very hard to obtain. So those who were inclined to go into nuclear physics had to be really good to be able to make a career in the field. Only those who had a really driving interest to learn about the subject, even if they had personal deprivation, could really manage it at that time. Bethe, Wigner, Teller were examples of a few dedicated folks who succeeded.

As we learned more about nuclear forces, it became more and more apparent that they were pretty complicated. Already in the middle 1930s, there was a beginning of, what you might call, a cultural split between a. those people who believed that even with things looking complex, there was some underlying simplicity going on if you could just get at it and b. other physicicists who believed that the nuclear forces are complicated and we’ll have to learn how to handle them even with all their problems. Those two philosophies reflected different approaches in dealing with the problem. The former group who thought there was an underlying simplicity later mostly became particle theorists. Those people who believed that the forces are complicated but we can handle them with better technology -- and later, of course, with big computers and then personal computers -- generally became nuclear theorists. Hans Bethe was a quintessential nuclear theorist. Of course, in the 1930s and for a couple of decades afterwards, nobody knew anything about quarks Until the 1960s, neutrons and protons were considered as fundamental particles.

Behrman:

Right

Moszkowski:

Nuclear forces were studied already in the 1930s, and in 1939, it was discovered that the deuteron, the simplest nucleon system, has a quadrupole moment. So the nuclear forces, in addition to all their complexity, also are non-central, and that has to be taken into account. Folks did try to do so, and they could, but then of course, especially since the discovery of the shell model, you also have the problem of the nuclear medium. I think I mentioned this last time. So you have to take both the effect of other nucleons and the complexities of the nucleon-nucleon force into account, both if you want to describe things exactly. But even the use of bigger computing power available today doesn't always solve the problem. You have to understand what you're doing. You have to set priorities.

I have a question for you. Does the term low-momentum interaction mean anything to you?

Behrman:

I’ve certainly heard of it, but my physics education didn't cover it.

Moszkowski:

Okay. It turns out, and I’ll come back to it later, that in the year 2002, Thomas Kuo, who was one of the key inventors of the low-momentum interaction, came to UCLA for a short visit, and he got me interested in it. It turns out that the low-momentum interaction is actually very closely related to the long-range part of the interaction as defined by the separation method. That is a recent development.

So, clearly, during the 1950’s, considerable progress was made in handling the nuclear many-body problem, and I’m glad to have been able to participate in this effort. In 1960, a nuclear theorist from Sweden, Sigurd Kohler, came to UCLA for a couple of years, and later became a Professor at the University of Arizona in Tucson. He got interested in the separation method, and actually improved the treatment of nuclear medium effects to get more rapid convergence. Later, he also got interested in the low momentum interaction. Over the years, we have kept in touch.

During the early 1950’s, I also began to work on other aspects of the nuclear shell model, which is how I got involved with the surface delta interaction later. One topic that I pursued, in particular, was deformed nuclei, (which I had gotten started on at Columbia with Townes). In fact, within a couple of years, I began to take on graduate students. They worked on different aspects of the nuclear shell model. including deformed nuclei. And in 1957, I was able to hire a postdoctoral scholar for a year from Japan, Taro Tamura, who was an expert on deformed nuclei. In 1958, he published a paper on residual delta interactions, in deformed nuclei. The field producing part of the interactions leads to the deformed average potential, while the delta interactions can be taken as an approximation to the residual interactions. Tamura’s paper may have been an important stimulus for me to start work on the surface delta interaction. Also, Charles Gallagher (a post-doc at Cal Tech) and I had a paper on odd-odd deformed nuclei, in which we applied the Nordheim coupling rules which he had published a decade earlier for spherical nuclei.

Another thing that occurred in the late 1950s was that I again took a look at the ideas implied by Maria Mayer’s paper on pairing. I wondered how you can generalize Maria Mayer’s results when you have nucleons in different configurations and there’s mixing between them, because the nucleon doesn't stay in one shell model orbit. The nuclear forces can move nucleons to other orbits. How can this be handled properly? I will skip details here, but I found a method, a way, to generalize Maria Mayer’s delta interaction. This acquired the name surface delta interaction.

Now look at a nucleus with neutrons and protons moving around. What is the potential that each nucleon feels? You get a deep potential inside a potential well, and then it falls off to zero at the surface. That idea is all the textbooks. In the interior, the potential is attractive, and pretty much constant. The dynamics of what happens to a nucleon in the interior is determined by the force, which is a gradient of the potential. In the interior, the single particle potential doesn't change, so the force vanishes, and nothing would happen. But in the real world, the single particle potential is due to all the interactions between two nucleons. Thus nucleons can collide with each other. If you take the surface delta interaction seriously, then, except at the nuclear surface, the repulsive and the attractive contributions to the interaction really do cancel to a very good approximation.

Let me put it this way. Nuclear forces are very strong. But we know that there’s a nuclear mean field which gives you orbits in which nucleons move, and the nuclear mean field gives you a relatively constant, but large, potential inside the nucleus. Strictly speaking, the nuclear forces, being the gradient of the potential (with a minus sign) will be small in the nuclear interior. Of course, the nuclear mean field is not the whole story. Some parts of the nuclear interactions must show up as residual interactions not included in the mean field. An example is Maria Mayer’s delta interaction. Another is Tamura’s delta interaction in odd-odd deformed nuclei. Neither of them, nor anyone else ever claimed that this is all there is to the nuclear interactions. But the point is that when you take into account the mean field and then you want to see what’s left over, then these residual interactions may be a good approximation to what is left over. So basically what the surface delta interaction was a generalization of what Maria Mayer had done back around 1949, and I got very excited about it, not immediately, but a few years later.

I would like to say a few words about excitement. Most of us humans get excited about some things sometimes, and (many times) that’s very good. Getting excited about a cause or an idea can lead to dedication to doing something about it. Einstein got really excited about relativity, and that probably helped him develop it. And I got excited about the separation method, this technical shortcut that helps in the many body problem. On one occasion, at an APS meeting I talked to some folks about it so much that I got hoarse! It took me several days to get my voice back. I am sure things like that happen all the time.

Behrman:

Sure.

Moszkowski:

But that is nothing compared to what happened when I got excited about the surface delta interaction. I started to believe that one of our cats in our household had some magic powers to make things work. I called it (to myself and family) “Snoopy Coupling”. This was crazy, but for a time in late 1965 and early 1966 I actually believed it!

Now the other point was the following: If you do Brueckner theory properly, you know what you're doing. You have a model you start with. The problem may be very complicated, but you can at least deal with it. On the other hand, invoking something like the surface delta interaction as a residual interaction is quite a stretch. How do you justify it? That is another story. By the 1950s and especially, during the following decade, our understanding of nuclear forces had evolved quite substantially. The fact that they contain a non-central part cannot be swept under the rug. For a complete theory you have to take them into account, even though they are complicated. When you take two nucleons, there are certain interactions between them, and if you scatter two nucleons in free space, of course, you learn something about the nucleon-nucleon interaction. Measuring nucleon-nucleon cross sections is indispensable. But in the nucleus you’ve got other nucleons around so there is a nuclear medium in which the nucleons move. The effect of the nuclear medium has to be taken into account. All nuclear theorists know this. But my point is that to do the problem properly, you have to consider both the nuclear medium and also the non-central nature of some of the nuclear force. But then the problem is complicated, and in the real world, folks are forced to make approximations in order to get the problem done in a finite time. So, the task here is: What is the best approximation to make so that you get into the right ball park? The fact that in the 1950s computing power expanded exponentially gave some folks the idea that with increasing computing power, we’re able to handle the nuclear many body problem without having to make serious approximations. Experience has shown that when you use computers, you are able to do things that you couldn't possibly have accomplished by only pen and paper. On the other hand, doing things using computers does exact a price, namely that often, really understanding what is going on can suffer. Do you get my point?

Behrman:

Yes, I think.

Moszkowski:

My point is that from what was known about the nuclear forces in the 1960s—not later, not when quarks came in, the idea of a delta interaction looked quite strange. It would be difficult to derive a delta interaction from what was at the time the realistic nucleon-nucleon interaction, which included a strong tensor force. As mentioned, I had personally been involved in two contributions to the nuclear many body problem. When someone does something personally, they are likely to feel a stake in it, and often get excited about it. That’s normal. I had these two things. One was the separation method which handles the nuclear forces, a nice shortcut, and then this idea of the surface delta interaction. But as I learned more about the details of the nuclear forces, I got the increasing feeling that something was not adding up. Sometimes when something doesn't add up, you may not fully realize in detail just what is wrong. Of course, theorists were well aware of the fact that computing power even in the 1960’s, while large, was not infinite. People had to make approximations. In practice, that means making choices. It appears that the majority, including Hans Bethe, believed that the tensor force should be treated in as much detail as possible, even at the expense of being a little cruder in the treatment of nuclear medium effects. I think that history shows that this might not have been the optimum choice for the nuclear many body problem.

Behrman:

I will want to ask you about your work in the ’50s.: So in ’51 you became a Guggenheim Fellow. How did that happen?

Moszkowski:

Actually it was 1961. I was doing pretty well. I applied for a Guggenheim Fellowship and did get it. But there was one complication. In my family, we had cats and liked them. My going a little overboard and believing in magic powers of a cat came later. I got cured of that quickly in 1966, but that’s another story, and it was no issue in 1961. It was normal for fellowship recipients to travel to one or more academic institutions for the year, like Copenhagen, for example. Now I have never been all that sociable. I tend to work by myself or maybe with a few people, not in a group. I don't think I feel comfortable in a big group, just speaking up, making suggestions and having someone else comment. That’s probably not where I feel most comfortable, which may have to do with my upbringing. But there was another problem concerning the cats. If you travel to many parts of Europe, any animals you bring along have to be quarantined for a while. My spouse was absolutely against subjecting our pets to anything like that, so she did not want to come with me to Europe. Therefore, I went by myself, and it didn't cause any serious problems in the family. In 1961, I visited several universities and labs, first in Europe, and later in Israel. The trip was very nice, but I don't recall anything super-special associated with it. It was an honor to get the fellowship, certainly, but I wouldn't consider it to have been a life-changing experience.

Behrman:

How did you feel working in different kinds of environments, because you had spent time at universities and then national labs by that point.

Moszkowski:

Well, I didn't really feel a lot of difference. I’m a theorist, so I work with a few people who have very similar interests, but a lot of the things I do by myself. So I don't think it made such a big impression on me. I am not one who naturally gathers a group around him and works that way. I’m a little bit more of a loner. Actually, so was my father. This may explain why right now, and actually for a number of years, I’ve been doing work mainly from home. I have not generally done much of my work at the office, although of course I did at one time, and there were certain things, like teaching, that could only be done at UCLA. If I was an experimentalist, I would have worked in a lab, and all this would have been quite different.

Behrman:

Right.

Moszkowski:

Or if there were no personal computers, it would be also be very different. But, as I said, I am somewhat of a loner. I work with people at different times, and that’s indispensable. But I’m not really, and never was, an organization man. I think that Einstein’s advice to my mother may have solidified my tendencies in this direction.

Behrman:

Well, in the ’60s as well was when your textbook with Wu came out.

Moszkowski:

That’s right! It finally came out after more than a decade.

Behrman:

What was the reaction to it? You said it was quite popular, actually.

Moszkowski:

Well, I think it was pretty good though I probably wasn’t aware of that much reaction. But I suspect that Madame Wu probably got more. She was the senior author, after all. I’m very glad that I became familiar with the part of the field that goes beyond nuclear structure. I can relate to some of the more modern things going on like, for instance, the still open question (as of 2020), where you have the normal or the inverted sequence of the three neutrinos. The strong interaction is what I really specialize in, but I’m very glad to have learned more about the weak interactions. There are definite parallels to the strong interactions but also big differences.

I always had very good relations with Hans Bethe and admire him. He was a genius, with encyclopedic knowledge. He knew all areas of physics. His two Classic Reviews, published in Reviews of Modern Physics, 1936 and 1937 were studied by most physicists at that time, and also reprinted. That’s why it is generally called “Bethe’s Bible”, but you're probably familiar with that.

Behrman:

Yes

Moszkowski:

So if you want to make an analogy between nuclei and atoms, in atoms the interactions between the electrons and the nucleus are not all that strong and have long range. So the idea of an atomic shell model makes perfect sense. You can show in detail why it makes sense that electrons move in orbits, but this analogy becomes questionable when you look at the fact that the nucleon forces are quite strong. This is why during the late 1930’s, physicists did not believe that you could have nucleons moving independently in the nucleus. The liquid drop model in the simplest form seemed to be more realistic. You don't have the water molecules moving independently. They keep bumping into each other, etc., and that’s a picture that people had who worked on the Manhattan Project used. This model was quite adequate, as one component among many, for building an atomic bomb during the early 1940’s. The Bethe-Weizsäcker mass formula does not demand independent particle motion.

Behrman:

Okay.

Moszkowski:

Then Brueckner and collaborators developed a mathematical theory which is now known as the Brueckner theory, to deal with what happens when you have strong interactions, including short-range repulsions, in particular, how you treat the many-body problem. This was a great theoretical advance. I remember once at an APS meeting I asked Brueckner what he was going to look at because Brueckner and collaborators really investigated the thing very extensively, including of course also other many-body systems where the forces were better known like liquid helium and things like that. He suggested that in this way, many body and shell model problems could be completely solved. He may have had a point, actually. Also Bethe and Goldstone worked out in more detail some aspects of the Brueckner theory.Anyway, I was wondering, how do you get independent particle motion when you have strong forces? Wavefunctions get perturbed, etc., i.e. give rise to correlations.

There are, indeed, alternative methods for handling correlations. One such method is that of Correlated Basis Functions, developed by John Clark and collaborators. Clark visited UCLA once in 1960, and we have many photos from that occasion. And I have been to numerous workshops at Washington University in St. Louis that he has organized. In recent decades Clark has also gotten very interested in neural networks, and in application of Artificial Intelligence to help solve many body problems.

Behrman:

Right.

Moszkowski:

Specifically what must happen is that to some extent the effect of the repulsive forces and attractive forces have to cancel. Do some partially cancel and what is left isn't that strong, and that’s how you can get it? That is the essence of what’s going on, but it’s not the whole story. I think I mentioned this last time. In my own opinion, a good fraction of the community did not optimize their priorities in the best way.They knew, of course, you have to include the fact of the medium. That’s what Brueckner theory is about. But you also have to take into account the aspects of the nucleon-nucleon force, like the tensor force. In the real world, people have to make compromises to get things done. Most of the nuclear theorists working on this problem at the time tried to handle the known tensor force as exactly, even at the expense of making compromises regarding nuclear medium effects. That may not have been the best tradeoff. The reason I mention that is because right now in 2020, we’re facing a different, more serious problem involving real human lives, where we also have to make tradeoffs and compromises. How do you deal with health problems and the economy in the era of COVID? You will have to make compromises. But here, making the wrong guesses costs lives. Getting things wrong with the tensor force or nuclear medium, didn't kill anybody. [Chuckles] Do you get my point?

Behrman:

Mm-hmm [yes].

Moszkowski:

Let me ask you something, Joanna. I checked some of the oral histories which have been published by AIP. There are lots of them, and I looked at a couple of them. One was Hans Bethe’s own memoirs, which I found very instructive. When Bethe was young, he was very interested in numbers, just like me, but was probably much better at it than I am. He has done far more, covered more fields, etc, than I have. But at least on one little thing, the separation method in the nuclear many-body problem, I may have achieved what Bethe was trying to do. However, Bethe worked much harder than I ever did. He was that sort of genius.

I also, going to more modern times, noticed what Hans Bethe had to say in his memoirs about the status of the nuclear many-body problem as of 1967. In fact, I think he was interviewed in both that and the previous year. You can check that. So his view, as expressed there, which is consistent with what I had sort of figured out, was that with what was known about the nuclear forces at that time, you could pretty much understand not only nuclear saturation, but the details of the Bethe-Weizsäcker mass formula. You could pretty much give a microscopic derivation of it which involved, of course, quite strong tensor forces, but you could make sense of that. That could explain things known at the time. There were a lot of little details that had to be sorted out, but basically the picture was pretty much in shape.

I recall in 1971 I met Hans Bethe at a conference and we had a short talk. He said something like, “Well, that’s the long and the short of it”. He was referring to long-range and short-range interactions, implying that the problem had been solved. Bethe also had a review article in 1971 where he expressed similar views, that saturation is due to a number of things, the tensor force being very high up on the list. Based on what was known in the late 1960s, the conventional wisdom would support this. But my experience with the surface delta interaction told me that this wasn’t quite the case. So there was a conflict in my own mind about these matters. Understand?

Behrman:

Yes.

Moszkowski:

Back to 1966. I had gotten super excited about the surface delta interaction. In fact, it’s probably safe to say that I was in a kind of manic state about it. Something was needed to bring me down to earth. There was a meeting at the American Physical Society in Washington in April of 1966, and I attended. I raved to people about the surface delta interaction, and I think some of the people I had talked to sort of were trying to delicately restrain me, but they didn't want to insult me. Hans Bethe invited me to join him for tea. We talked and I started to expound on my excitement about the surface delta interaction. I should add that, I did not talk to most people about my really nutty ideas about that cat with magic powers. I wasn’t that crazy. But I was pretty gung ho about that surface delta interaction.

Behrman:

Of course.

Moszkowski:

Hans Bethe was not particularly impressed by the surface delta interaction, but he was very diplomatic, and changed the subject to the nuclear three body problem, a topic of mutual interest that both of us had done some recent work on. I found that discussion enjoyable. But then Bethe had to leave.

With Bethe at the tea break there was a very talented physicist, Judit Nemeth, from Hungary, who was at Cornell U. working for the academic year with Bethe as a post-doc, on different problems in nuclear structure. She had been quiet during our chat about the three body problem. So, Dr. Nemeth and I agreed to meet the next day and continue the discussion. This was a chance for me, for instance, to explain what I’m doing and she could talk about her activities.

The next morning, we met as planned and had a nice conversation. One of the things that had happened in the 1960s was that the Cold War was beginning to look like it might be easing up a bit. It became possible for scientists from some East European countries, especially Poland and Hungary, to come to the West for visits and work. It was much harder for people from other East European countries, like East Germany, to do the same. The other point of concern with Hungary was that in 1956, of course, there had been a revolution there, but we did not discuss this directly, neither then or later. The Soviets did not want a repetition of 1956, so basically János Kádár’s regime was able to get certain reforms, like in agriculture and so on. Travel policies were beginning to be eased. That’s why Dr. Nemeth now was able to travel outside the bloc.

After telling me about her experiences, and her work with Bethe, Dr. Nemeth asked me, “What exciting things are you doing?”. Naturally, I started to expound about the surface delta interaction. Finally, she mentioned a wish to come to UCLA for a brief visit in July. I enthusiastically agreed. And soon we said good-bye.

A few minutes later, I started feeling as if I was back in Europe or something like that. Of course, I knew I was in Washington, but here is what must have probably happened. At the end of World War II, the Allies discovered the concentration camps and the grisly things that had occurred there, and a lot of corpses. The Western Allies did not get to Auschwitz which had been liberated by the Russians, and where things had been even worse, e.g. with gas chambers. Terrible atrocities had happened in World War II, and many people found this to be too much to handle. In 1945-46 there were the Nuremberg trials and some of the worst Nazis were brought to justice or had already done themselves in. But then the Cold War broke out, and it was recognized that Germany would be needed as an ally against the Soviet Union, which was definitely no longer an ally of the West. So most people didn't talk about WWII at length any more. When I worked with Maria Mayer, we never talked much about the past. So some of my old memories of coming from Europe were sort of submerged. This phenomenon is called the “Sleep Cure”, a chapter in a book by Frederick Taylor on the history of Germany after WWII.

You see, I, like many others, may have had my own “Sleep Cure” during the 1950’s and early 1960’s. Meeting Judit in 1966 sort of woke me up. Something like this on a much bigger scale also happened in Germany. I conjecture that questions from children like “Papa, what did you do during the War?” during the 1950’s might lead to Mama replying: “Hans, we don’t talk about these matters. But you must be hungry. I will make a nice snack for you”. And in a typical course on European history, the teacher only had time to get to Otto Bismarck. By the 1960’s things were beginning to be quite different. A new generation was growing up. And also the Eichmann trials (1961) and Auschwitz trials (1963) got many people asking questions, and not being satisfied with the answers. History courses started to cover difficult materials, like the Third Reich, and the Holocaust. Does that make sense to you, Joanna?

Behrman:

Yeah, it does.

Moszkowski:

By the way, Laszlo Nemeth, the father of Judit was a very distinguished writer. He was famous all over Hungary, and in 1993, long after he died, the Hungarian Government issued a stamp in his honor.

My own memories were not grisly, since my parents and I had gotten out of Europe before the Holocaust. Still, certain things from my youth in Berlin came flashing back. I somehow felt that I was back in Europe somewhere, perhaps in Vienna or in Prague—not Budapest. I couldn't quite understand all this. For all I know, it might have been some kind of PTSD. In any case, I was in a very unstable mood.

The project,which Hans Bethe spelled out when I phoned him a month later, was for Dr. Nemeth and me to sort out some questions in nuclear theory based on what was known. However, something in my subconscious told me that this could not be done satisfactorily.

In July Judit visited UCLA as planned. We had a nice time in Los Angeles. My wife, Lena, and Judit got along very well, but shortly afterwards I started getting rather depressed. Some of it was due to the sedatives I had been prescribed, hurting my ability to concentrate. Also, I was getting worried about being able to teach classes in the coming Fall quarter. To make a long story short, something put me out of commission for a little while. Actually, there was some similarity between this and what had happened 20 years before when I was drafted, because also at that occasion I felt unable to handle the situation in Chicago. I had wanted to get away, and in the Army I gained a lot of weight. Both in 1946 and 1966 it was great for my physical condition. (People can talk about these matters more freely than 50 years ago!) So I spent three weeks in August of 1966 at the Veterans Administration in West Los Angeles. Some of the folks who visited me from UCLA were surprised how healthy I looked. It was little like some imaginary military force in my own brain figured that I couldn't handle this situation on my own, and put things into recess for a short while. Does that make any sense to you?

Behrman:

Yeah.

Moszkowski:

I had a lot of lucky breaks, which were, number one, that some of my colleagues at UCLA sympathized with me. They didn't really know what had happened. Let me mention one other thing: There was a noted theoretical physicist, Gerry Brown, who visited UCLA during the same time Judit was there, and a little afterwards too. Gerry was pretty outspoken. He liked Bethe and also my separation method, but he didn't think that highly of the surface delta interaction. Being in the kind of state that I was in at the time, I was rather hurt by this. That may have also contributed to my getting depressed.

However, somehow I was able to manage at UCLA. It happened that there were several physicists visiting UCLA just at that time. One was Amand Faessler who had been a post-doc in our group during the year 1965-66. He had gotten quite interested in the surface delta interaction, and wrote a couple of papers clarifying its significance. But I did not talk about my own problems with the visitors with one exception. Georges Ripka, a theorist from Saclay, who was an expert on the Random Phase approximation. We had gotten acquainted a couple of years earlier when he visited UCLA. He was as encouraging as possible, and that helped quite a bit. Also, another nuclear theorist, Vincent Gillet, working at Saclay, had been invited to spend the coming academic year at UCLA. The Physics Department made arrangements for him and me to split a course teaching nuclear physics. He would teach some classes and so would I. That arrangement worked out very well. And in a few months, I more or less recovered my equilibrium. I did not work on the surface delta interaction for a while, but got interested in more traditional nuclear structure topics. I was even able to travel, to the APS meeting in New York in January 1967, and to a meeting in Gainesville, Fl. in March, where I gave an invited talk on the NN interaction.

Altogether, I am sure that 1966 was a life-changing experience for me. And unfortunately, our cat Snoopy, to whom I had attributed magic powers, died at the end of 1966.

Now let me come to the Skyrme interaction, which was one important subject that helped me greatly in getting back to something like normal. Bethe and Nemeth had studied the nuclear surface, and in early 1967, I started looking at this problem, using a simpler nucleon-nucleon interaction that had been developed by Tony Skyrme some years previously. I remember he visited us at UCLA once, in 1962. Actually the Skyrme interaction, while important, was probably not his best known discovery. That was his proposal of skyrmions, which is a method of simulating subnucleonic degrees of freedom in a very clever way. but I have not worked on Skyrmions and don't have anything more to add about them here.

The Skyrme interaction is a different story. It is basically an expansion of the NN interaction in powers of the range. The first term is a contact, i.e., delta, term. The second term is something like p², where p is the relative momentum. For a conventional finite range interaction you need higher terms as well. But in the Skyrme interaction you stop at p², i.e., you take only the first couple of terms. What I used in early 1967 was a very slightly modified form of the Skyrme interaction, which I called Modified Delta Interaction, but that is not an important point. I used the interaction, together with the Thomas Fermi approximation, to get ideas about what happens at the nuclear surface. Other people then independently took up similar ideas and some did much more than I had, but the point was that I got very interested in the Skyrme interaction.

My colleagues Harold Ticho and Bill Slater in Experimental Particle Physics were most helpful. I was able to use one of their computers, which still required punched cards, but it worked and in 1970 I was able to publish a paper on the results.

Another development which occurred in 1967, and did wonders for my morale, was that the first millisecond (1.33 ms) pulsar was discovered. For some time it was not clear what was going on. In fact, there were half-joking speculations about Little Green Men being involved. But after a second pulsar, with a different period, was found in another part of the sky, it was realized that we were dealing with rapidly rotating neutron stars. The discoverer, Joselyn Burnell Bell probably did not get enough credit for her work at the time, and her boss, Anthony Hewish, who figured out the neutron star explanation, got the Nobel Prize in 1974. These developments got me interested in neutron stars. (I might add that a sugar cube of neutron star matter weighs as much as the human population of the earth, something I learned from Mel Ruderman, who had been a fellow post doc at Columbia University.)

As a postscript, my present collaborator, Jirina Stone, once shared an office with Joselyn Bell at Oxford.

A third piece of good luck for me was that a physicist from India, Asoke Mitra, who had done pioneering work on the three body problem, visited us at UCLA, and we wrote a short paper on quarks. (We also went to the Los Angeles County Fair.)

The entry of quarks into physics during the 1960’s was a radical and somewhat unexpected development. I had previously gotten a brief introduction to the subject. The physicist, Benjamin Lee, had visited UCLA in 1964, and he gave a talk on how, with the assumption of constituent quarks, you could explain the magnetic moments of the neutron and the proton to a good approximation. You get 3 for the proton; the value is 2.79, which is very close. You get –2 for the neutron; experimental value is –1.91. This had been a mystery ever since the first discovery of protons and neutrons. Why do the neutron and proton have magnetic moments so far from the Dirac values? This could, of course, be explained with meson exchange. And it should be noted that, back in 1932, when Otto Stern got ready to measure the proton magnetic moment for the first time, some of his colleagues felt that he was wasting his time. Was it not obvious that it should be just 1 Bohr Magneton, as the Dirac theory would predict?

Back to the 1960’s. With constituent quarks one has a much neater way than with meson exchange, to get really close to the empirical 2.79. All this made a big impression on me, though it didn't change what I worked on at the time. Unfortunately, Benjamin Lee died in a traffic accident a few years later. How quarks got into the game, including the discovery of partons a little later is a whole saga itself. I’m sure at AIP they have part of the history describing the controversies and the whole exciting story.

But basically, nuclear theory, as it had been conducted until then, didn't take into account quarks. It was as if quarks had never been discovered. In the 1970s, people tried to bring in quarks, but there were technical problems in doing this, as there are, even now. So the question is to what extent does the fact that nucleons are made of quarks really change nuclear theory? Actually, it does change it somewhat, but not all that much. One of the main things about the fact that there are quarks is that the nuclear forces are not purely local. They do not depend only on relative positions, but also involve relative momenta.

Now fast forward to 1968. Vincent Gillet, my French colleague with whom I shared a nuclear physics course in 1966-67, had asked me to give lectures on the nuclear many body problem at the well known summer school in Les Houches in August 1968. Also, I was invited to give a talk at a conference in Dubna near Moscow. Due to these invitations, my family and I traveled to Europe. At the Dubna conference, I gave my talk on the nuclear surface. Judit Nemeth was also at the Dubna conference. I remember going with her to a park nearby, where we discussed what we might be doing on the project Bethe had suggested. While I was talking with Judit, one of the other physicists came up and said to me: "You are scheduled to give the keynote speech.” That turned out not to be the case, as he had been joking, but it shook up both of us, and essentially ended our conversation. This man, a very well-known physicist, was a joker and liked playing games, not entirely of a positive nature. In retrospect, as mentioned before, if we had actually pursued the project the way that Bethe and, presumably Judit, had in mind, we probably could not have succeeded, due largely to strong tensor forces. Incidentally, Lena and I, coming from America, had better accommodations at this conference than Judit had. In other words, Americans were treated better than those coming from Warsaw Pact countries, allies of the USSR.

During the conference at Dubna, I took a photo of Lena, Judit, and Madame Wu. I noticed that Lena and Judit, who had met once before in 1966 got along very well. It can be said that all the three women in my photo were very strong women, and perhaps even domineering. Not long ago, a colleague asked me for a photo of Madame Wu. The one from Dubna was the only one I could find.

The year 1968 was a time of political upheaval in much of the world. One more benign aspect of it was the Prague Spring. That was the attempt by Alexander Dubcek of Czchoslovakia to implement “Socialism with a Human Face.” Actually the country had been liberalizing somewhat already during the early 1960’s. This was quite unlike the Hungarian Revolution which had happened 12 years before. There was little or no violence, and also Dubcek made no attempt to pull the country out of the Warsaw Pact. Naïve folks like me thought that since there were no direct threats against the Soviet Union, there would be no problem. But I was wrong. On August 20, shortly after we returned to the U.S., Russia and other Warsaw Pact countries invaded, and crushed the Prague Spring. My conjecture about this is that plans to reform the economy (in Hungary it was called the New Economic Mechanism) would have threatend the one-party control in East Germany, which was still ruled by Walter Ulbricht along more or less Stalinist lines, so Brezhnev was persuaded to quash all this. As we learned later, the Russians had considerable logistic difficulties with their tanks breaking down, etc, Fortunately, Alexander Dubcek was not jailed or worse, but was basically exiled to a remote part of the country. And he managed to survive. But Czechoslovakia underwent a period of severe repression. Many people lost their jobs, for example, in academia. From what we know, there were few, if any, executions, unlike what had happened in Hungary after the suppression of the 1956 revolution. However, for a decade after 1968, there was more freedom in Hungary than in Czechoslovakia.

Now back to nuclear theory. While a lot was known by 1968, one important quantity, the incompressibility (i.e., stiffness) of nuclear matter denoted by K_NM was not precisely known. This is very different from the situation in atomic and molecular physics. But that did not seem to bother most nuclear theorists very much. With what was then the accepted picture, namely a key role for pion exchange, including a strong tensor interaction, and, in addition, heavy meson exchange to generate the short range interactions, the calculated incompressibility of nuclear matter was not much larger than about 100 MeV. By now it is generally accepted that K_NM is much larger, as I plan to mention later.

[Part 3]

Moszkowski:

Let’s move to the 1970’s. I had resumed normal activities at the university, teaching and working on different things in nuclear structure. Also, a new faculty member, Chun Wa Wong, joined the UCLA nuclear theory group He had previously worked in England and had a reputation for being a one man research team. Later that decade, we wrote several papers on aspects of the nuclear many body problem.

One day in 1972, I received an invitation from Judit Nemeth to talk at a workshop that she was organizing in Balatonfured, Hungary in September 1973. I went (after a little hesitation, where one of my sons reminded me that I had to do my Judyduty!) I think that from what I said before about my experience in 1966, some people might argue what had happened was that at the APS meeting I had fallen in love with Judit. That does happen sometimes, but I doubt that was the case with me. However, I can say with more certainty that I did get infatuated with the country of Hungary.

So in 1973, I visited Hungary for the first time. It was a very nice workshop, and Dr. Nemeth, did a superb job organizing it, down to every little detail. I spent a few days in Budapest, both before and after the conference. The city looked vaguely familiar to me, though I had never been there before. It must have reminded me of my days in Berlin when I was a young boy. Evidently, in all the communist countries there was something of a time warp because certain things involving maintainance simply did not get done, like work on non-priority buildings. Thus many buildings looked a bit like they had before WWII.

The title of the Balatonfured conference was “Correlations in Nuclei,” but that wasn’t what I talked about. Instead I talked about my (and a couple of students’) work using the Skyrme interactions, mentioned previously.

The Budapest visit also was very nice, and Judit took me sightseeing to a number of places, including the famous castle. Also, I was, and still am, quite fascinated by the many bridges over the Danube. Perhaps the famous of these is the Chain Bridge, one of the first suspension bridges, completed in 1849, which linked the two parts Buda and Pest to make the city now known by that name. This bridge and all the others were destroyed by the Germans near the end of WWII. One of the first acts of the new regime, was to rebuild them. The new Chain Bridge was completed in 1949, by which time Hungary was under Stalin’s rule, through Bela Rakosi. This may have been one of the few projects which enjoyed popular support. The collectivizations certainly did not.

After leaving Hungary, I spent a few days in Zagreb, where Ivo Slaus, a frequent visitor to UCLA was. Then there was a workshop in Trieste. Here I met Georges Ripka, who took me on a nice tour of Venice, which, with all its famous canals, is a world by itself. Afterwards, I spent several weeks in Julich, and worked with Amand Faessler’s group there. Both Ripka and Faessler are still active, and I keep in touch with them, at least at the holiday card level.

In 1975, I again visited Hungary for a workshop at Balatonfured. organized by Dr. Fodor. In addition, there was a workshop at the Masurian Lakes in Poland where I talked on some ideas regarding a proposed long range effective NN interaction. That work did lead to one paper, but not to much progress.

Moszkowski:

Let me now briefly mention my personal life during the 1970’s. Unfortunately, my first marriage was coming apart. It was mainly over financial matters. My midlife crisis of 1966 had probably postponed the disintegration of my marriage for several years, until 1975; I can make a case that it actually stabilized things for a while. Lena had been extremely supportive during a time when I basically had a nervous breakdown. She and Judit got along well, and they probably had similar personality traits. Supportive, but also very concerned about being in control. To make a long story short, in January 1978, Lena and I filed for divorce. So I was somewhat at loose ends. I was not used to being by myself, (though, of course, on trips, I was.)

Now it happens that there was a conference at UCLA celebrating the 60th birthday of Julian Schwinger, who had recently joined the UCLA faculty. I went to a nice luncheon in his honor. All the faculty members were there. Here’s why I mention this: because the wife of the chairman of the department at that time, George Igo, was Nancy Igo. She (but not George) was present. I started talking with Nancy and discussed my situation, including that I had recently split up with Lena. She was quite interested to hear what had transpired and we talked quite a bit. A couple of weeks later, I got a letter from her, saying, “You might want to meet a friend of mine, Esther Kleitman. Give her a call sometime.” She and Nancy Igo had been friends for a number of years, and so a short time later I phoned Esther and we made a date to meet. I remember that we went out to eat at a place that happens to be really close to where we’re living now, except the restaurant itself has long been closed and superseded by other things. We really hit it off. I didn't learn, until a couple of weeks later, who Esther’s father, Nathaniel Kleitman, was, though I had briefly met him when I picked up Esther the first time! [Laughs] He had been the co-discoverer of rapid eye movements (REM) in sleep. He was a pioneer in sleep research.

Behrman:

How interesting!

Moszkowski:

It’s a whole story itself. Now I do not want to pretend that everything went smoothly. The world doesn't work that way. Esther had not been married before, and she wasn’t quite sure whether she could take that step. You know, I’m a pretty eccentric character. Let me mention something here which, half a year later, would be crucial. A couple of months before I met Esther, I had arranged with a colleague in Hungary by the name of István Lovas, who was a quite noted theoretical physicist, to spend a month, September 1978, at the Central Research Institute in Budapest. That was really a lucky break for me. It’s not clear whether without me being away from Los Angeles for a while that things would have worked out with Esther. As it turned out, I spent a month in Budapest. The visit was very nice and instructive. In addition to work on physics questions and seminars in Budapest and Debrecen, there was sightseeing in Budapest and elsewhere. When I came back to Los Angeles, any tensions Esther and I had had that summer (I had lost hundreds of hours of sleep!) had vanished. We got married a month later and fortunately, we’ve been happily married ever since.

Behrman:

Very nice.

Moszkowski:

Now I want to point out one thing here. Some physicists and some scientists figure that if you can't measure something, it doesn't exist. The idea that there are some things that you can't really get your arms around is difficult for some people to accept. Of course, our knowledge is increasing with time. We’re learning more and more, but there are some things where it’s not clear whetheror or not they’ll be discovered. Esther was, and is, very supportive of ideas, such as ESP or synchronicity. Some things happen where you can't exactly figure out cause and effect. Her support was very reassuring because, you see, during my earlier phase when I was much more unstable, some of my ideas about someday visiting Hungary sounded sort of crazy. People who have crazy ideas sometimes go over the edge and do bad things. So the question is how do people deal with that possibility? I never went over the edge, but who could be sure I wouldn’t? To make a long story short, one can make a case that meeting Esther when I did, saved the Moszkowski family.

Esther and I got married at the Sinai Temple in Los Angeles, on Nov. 5, 1978. I continued my regular activities of teaching and research. But also, we (and in some cases, I alone) took a lot of trips. A couple of these deserve a few words at this time, because they intersect strongly with my research, or because they have a special personal significance.

The first such trip was in March 1979, when I went to Indiana on the occasion of the Centenary of Albert Einstein's birth. And in later years I gave a number of talks on Einstein, most at UCLA, but some elsewhere as well. In these talks I showed copies of Einstein’s letters to my family.

During summer 1979, there was a workshop in Buenos Aires, organized by Angel Plastino (who had been a post-doc at UCLA during 1965-66, and had done crucial work on the surface delta interaction), and James Vary (who later started ab initio nuclear shell model calculations). When we arrived, no one there was there to meet us, and the airport personnel asked us to wait in a room. I recall that the room had lots of nice paintings. Now, as you may remember, during the 1970’s Argentina had gotten caught up in what was known as the Dirty War. About 30,000 people, including at least one physicist, Pasquino, had disappeared. So, when we had waited about an hour, we started wondering if, perhaps, something could happen to us. But I figured that this would not be too likely. If we didn't show up at the workshop, the organizers would probably inquire at the American consulate, and there could be consequences. We had no trouble leaving the airport to get to our hotel. As we learned later, the organizers had sent out three different groups to pick us up, but somehow all of them were delayed, by traffic, etc. But the workshop was very enjoyable and stimulating. And there were several nice tours and excursions. The following year, Hans Bethe came to UCLA to give a seminar. On that occasion, at dinner, he told me a crucial fact: The U.S. was now the biggest energy producer in the world. That remains the case even in 2020, and the U.S. has benefitted from being less dependent on unstable countries for its oil supply. Of course, at present, there is a new existential challenge, namely dealing with climate change. This is making it urgent to get as much of our energy supply as possible from renewables, and possibly also (safe!) nuclear reactors.

In early 1981, Esther and I visited Santa Barbara for a workshop. One of the people I remember talking with on that occasion was Arkadi Migdal, a pioneer, with Landau, on many-body physics. I was somewhat familiar with his work on the effective NN interaction in nuclei. When I mentioned the surface delta interaction, he commented that this was “A special case of my interaction”. His remark is correct, and I found it encouraging. The general Landau-Migdal interaction is a density dependent delta interaction, and not necessarily restricted to acting at the nuclear surface.

In July of that year, I visited my son Ben in Palo Alto, where he was working for his PhD in Computer Science at Stanford University. Ben took me to a very interesting lab, the Xerox PARC in Palo Alto, where I learned about a lot of pioneering work that was being done. It was the beginning of the personal computer age. Writing, editing, sending messages are now, of course, commonplace. This was the first time I had ever used computer graphics. Ben has played a crucial role in bringing me into the computer age, also earlier at UCLA, and at other times.

During early 1983, I attended a workshop at Argonne Lab. Just during that time, Stan Brodsky from Stanford gave a talk at UCLA, in which he suggested that nuclear physics should be completely redone to conform with modern QCD. Indeed, traditional nuclear theory is not compatible with anything like the asymptotic limit of QCD. I regret having missed this talk. Brodsky is not only one of the best particle theorists around, but also extremely charismatic. A decade later when he visited UCLA again, he expounded for more than two hours, but the audience was spell-bound, quite unlike what they would have been for most speakers after more than one hour. I should add, however, that the nuclear theorists who had been at his 1983 talk were quite skeptical about his message, from what I learned later. And history has shown that the approach of QCD to the asymptotic limit is as fast as Brodsky might have thought. Indeed, as Amand Faessler once put it poetically: “Nuclear Physics lives under Infrared slavery”.

Later in 1983, we traveled to Europe. One of the first things we did was to visit Ben in Cambridge, where he had a post doc position. He took us sightseeing in the city. I remember we did a lot of walking. That was the last of what we call the "Old Ben," before he was introduced to Orthodox Judaism and became observant.

After England, we went to a many-body conference in Altenberg, Germany, and also visited numerous places in Germany. One of the highlights of this trip was a short visit to our old house in the Grunewald part of Berlin (Kasper-Theys Str. 5). 1983 was the first time after the war that I saw the house again. Around 1950, the German Bundesrepublik passed legislation that made it possible for German Jewish refugees to get their property returned to them. My father could have done so, but we were now well settled in the U.S. So, unlike in 1939, my family got a very good price for the house. On our visit, when we knocked on the door of the house, the woman who answered kindly invited us to come in. She gave us a tour, introduced us to her daughter who also lived there, and could not have been nicer. This woman apparently had bought the house when the Berlin family who purchased it from us after the War had moved.

During the last part of our stay in Germany, we dropped in on a conference in Karlsruhe where Wolfram Weise gave a very nice talk on the NJL model, which intrigued me quite a bit. I’m sure it intrigued some other folks, too. You can use the model to get some interesting relations between certain particle energies, but I won't discuss the details here. I did not pursue the NJL model at the time, but did with enthusiasm a few years afterwards, as I plan to mention later.

In 1984, I paid a visit to a colleague, Manuel de Llano, at Southern Illinois University, Carbondale, Il. Later, we coauthored several papers. On that occasion, I gave two talks, both of which I remember vividly. One was the story of the surface delta interaction. The other was on the information revolution. A few years before, the famous futurists Alvin and Heidi Toeffler had written a book, “The Third Wave”, which tried to make sense of the things which were happening in society, starting in the U.S. but now world-wide. The first wave was the transition from hunting to agriculture, the second was the industrial one which had started in England around 1800. The third wave was the information age which had gotten underway around 1970, and was proceeding much faster than the first two. And the change is being accelerated considerably during 2020, thanks to the Covid-19 pandemic.

Later that year, there was a conference in Philadelphia. It was mainly about nuclear theory. but I want to concentrate on one of the sessions there, which was on arms control. Hans Bethe, who had gotten interested in arms control issues, gave a talk at this session. Bethe talked about the Strategic Defense Initiative (SDI), a program lunched by President Reagan the previous year, using various methods to intercept and destroy incoming missiles carrying nuclear warheads. The stated goal of this program was “to render nuclear weapons impotent and obsolete”. I think, by that time, in America and Europe it was understood that nuclear war must never happen as the consequences would be catastrophic. In Russia, it took a little bit longer to adapt to the reality that a nuclear war would be infinitely worse than what they had experienced in WWII. The idea of using lasers to shoot down enemy missiles had some degree of plausibility. But was it technically feasible? According to Bethe, the SDI program had been grossly oversold. In the highly competitive present world, in order to secure funding, a proposal may exaggerate somewhat the prospects of success. However, in Bethe's opinion, SDI had been oversold by orders of magnitude. He knew what he was talking about, having worked on some aspects concerning the program himself. I am talking here about the excitement for an updated version of StarWars during the early 1980’s. Are you familiar with the history of the Strategic Defense Initiative?

Behrman:

Yes, somewhat.

Moszkowski:

I want to mention in advance, that this might get a little weird. If you look at the papers which folks working with me and I had published in 1966 on the surface delta interaction, you will see the initials SDI. That is its proper abbreviation. But it happens that the Star Wars of the 1980’s. called the Strategic Defense Initiative had exactly the same initials, SDI. (The original StarWars movie trilogy had been produced around 1980, and became a box office hit).

Behrman:

Ooooh!

Moszkowski:

Was that a coincidence? Of course it was. But there were weird similarities. For example, the gleam in the eyes of the chief proponents. To Ronald Reagan, here was a way to end nuclear war, to stop it before it started. Hans Bethe played a big role here in attempting to cool off some of the enthusiasm. Things that get a little bit crazy sometimes can be very inspiring, but you have to keep your head, too. But in any case, thinking outside the box can help. In any case, the Star Wars program was not a total failure. The Iron Dome now protecting Israel from rockets is an outgrowth of some of the more realistic aspects of the program using antiballistic missiles.

When I heard Bethe’s talk, I saw myself in 1966, with my own SDI, the surface delta interaction, when I sort of had stars in my eyes. In 1984, on television, I saw people who had similar stars in their eyes, about the new SDI. The program, as it actually developed, was a kind of welfare program for some physicists, as there was a great deal of funding for it. Some colleagues joking told me, "You should have tried to get 50 million dollars for your SDI!" The same Hans Bethe had brought me down to earth on my own SDI in 1966. I had gotten the message right away. But it took a little longer, till about 1990, for advocates of the new SDI to adjust to reality.

One important lesson I got from both my SDI and Reagan’s was that even a good idea is bad, if overdone. “Zuviel ist Ungesund”. This maxim is not universally accepted, but I take it seriously. I generally support the path of moderation.

Behrman:

Mention your other two sons, because you said several things about Ben.

Moszkowski:

I should mention that I had three sons, one of whom unfortunately passed away 25 years ago, but we talk to my other two sons very frequently. They live in England, and I have to add that they became very observant. Both sons and their families are Haredi Orthodox Jews. Also we now have a dozen grandchildren. Esther is, of course, Jewish. She told me she would not have married me if I had not had a Jewish background, that is, a non-Jew by blood. We have good relations with my sons and families, even though their religious practices are different from ours. Esther and I are pretty secular, and don’t attend religious services. In fact, I (and my sons) used to celebrate Christmas until the 1970s, but not more recently. This interview is not primarily about religious matters, but this is a part of my overall memoirs because these things are intertwined in my world.

In 1985, my mother passed away, some 26 years after the death of my father. Esther and I made several trips to Chicago to go over the contents of her apartment. Ben could not come, as he was in England. But Esther’s sister, Horty, and both Richard and Ron came to help us. Ron was quite impressed with the portrait of the Baron he saw in the living room. That was Wolf Adlersthal, the great-grandfather of my paternal grandmother Bertha. He never formally received the nobility title, as he declined to convert to Christianity, but nevertheless he was widely known as “The Baron” and he did not seriously try to squelch such talk. As it turned out, in 1987, we found out Wolf’s father was the the famous Rabbi Yonason Eybeschutz. Ron became very proficient in computer graphics, at a time when it was being developed. Ron followed Ben in becoming Orthodox. More recently, he set up his own business making custom designed invitations to weddings and other occasions in the Orthodox community.

Moszkowski:

A very important nuclear theory question is the nature of the nucleon-nucleon interaction. Vladimir Kukulin, a Russian physicist has done some pioneering work on the subject. The idea is that two nucleons can form a virtual state, called a dibaryon. This can very much influence the nuclear forces, introducing nonlocality, and may be a way of virtually, but not explicitly, including the quarks. I had a little different way of formulating the same thing, which is having two intermediate delta states, a double delta. These approaches are fairly similar, though they differ in detail.

Let me come to the late 1980’s. At some seminars at the time, I started talking about the cultural wall between quark and nuclear physics. On one occasion in 1987, a fellow in the audience interjected, “It’s like the Berlin Wall.” In 1987, it was not at all clear when the Berlin Wall would actually come down. And I remember asking some folks what their opinion was; generally it ranged from 20 to 50 years. I remember Esther once, when we discussed this, saying, “It may come down sooner than you think.”

Indeed, in 1989 some brave Hungarians decided to cut the barbed wire fence to Austria. It was costing the Hungarian government a great deal to maintain that border, with all the guards, etc. By that time only about ten people per year were escaping illegally. Shortly after the fence was cut, on Sep 11, 1989, Hungary formally opened the border with Austria. Now during the cold war, travel between Western and satellite countries was severely restricted. However, East Bloc citizens could travel relatively freely to other Bloc countries. So, lo and behold, immediately after the Hungary-Austria border was opened, many folks from Czechoslovakia and then East Germany traveled to Hungary and then to Austria. And a couple of months later, the Berlin Wall came down! The general opinion of some people like the author Fukiyama was this is “The end of history”. Capitalism has defeated communism, etc.

Well, we now know that this assessment turned out to be a rather oversimplified version of history. For example, unfortunately, the country of Hungary is now an illiberal democracy. The fate of liberal democracy is uncertain. But it helps greatly to remember that the fate of liberal democracy was even more uncertain during the 1930’s.

During the 1980’s, I got quite concerned, and still am, about the fact that the particle theory community and the nuclear theory community have really sort of grown apart. The cultural split developed for at least two reasons: 1.) when you have a big field like nuclear theory, physicists who work in nuclear theory tend to be more (small c) conservative. They want to make models work, without necessarily understanding all the underlying fundamentals. Bethe is a quintessential example of this. Now, some people contribute more than others, and any large group will try to maintain itself. That is human nature. But some of the folks get, let’s say, less imaginative, and that can have negative consequences for the field. Keep in mind that I am a nuclear theorist. Still it is necessary for people like me to have some familiarity with particle theory. 2.) The people who go into particle theory generally are people who have, you might say, a little more utopian mind frame, not necessarily extreme. They want to get to the fundamentals of things. So there is a tendency of some particle physicists to look down on nuclear physicists. This resembles the tendency of physicists to look down on engineers.

During the 1930s only very dedicated people could afford to work in nuclear physics because everyone has to earn a living. But in the 1940s, in the aftermath of World War II, nuclear theory became a big industry. At that time people had high hopes for nuclear power. And let me put in a little plug here for nuclear power, Our society needs lots of energy. Solar and wind will likely play an increasing role, but this may not be enough in the short run. So nuclear power just might make a comeback, though, of course, there will be challenges. What about safely storing nuclear waste? There won’t be the kind of nuclear reactors we’ve had, big ones, but smaller ones based on techniques, like molten sodium, which make it impossible to have another Chernobyl or Fukushima. Democratic societies cannot survive with serious brownouts over an extended period of time. We need energy, and the coal industry is already dying. Especially now with COVID and various other things, it remains to be seen how the fossil fuel industry (oil and natural gas) does in the near future.

Moszkowski:

In June 1988, I was in Hungary for an informal meeting on heavy ion physics, and two things happened there. One was that one of the people there, Jozef Zimanyi, had been developing a model which is a generalization of the Walecka model with a derivative coupling. He had some very interesting ideas along these lines, and we wrote a paper on that a couple of years later, basically an extension of the Waleckea model, but I will not say more about it here. But there’s one other thing that occurred, which is a little bit weird. At this 1988 workshop, Judit Nemeth gave me a present which was the proceedings of another Balaton conference in 1987, that I had not attended. It was very kind of her to give me that present. Later, when I studied it, one of the talks listed was on applications of the Nambu–Jona-Lasinio model. Because this model related to things I was interested in and had worked on, I got nterested in the NJL model.

Then, during Nov 1989, Madhusree Mukerjee, a post-doc working with Steve Koonin at Cal Tech, and a former student of Nambu at the University of Chicago, gave a talk at UCLA on application of essentially the NJL model to nuclei. I realized that what she was referring to was a greatly glorified version of the surface delta interaction. So I paid very serious attention to her talk. This brings me back to identical bands. In 1990 there was a conference in Santa Fe, NM in honor of Akito Arima’s 60th birthday, and Ben Mottelson gave a invited talk on recent developments in rotational spectra. He described the identical band phenomenon, which had been discovered a couple of years before in Daresbury. That was the first I had heard about these developments. So Mottelson started to describe what this was about. He presented a Nilsson diagram which showed the relevant orbits. For a superdeformed prolate nucleus with a large axis ratio of 1 to 2, the closed shell numbers are, of course, quite different from the spherical case. When spin-orbit coupling is included, one of them occurs at Z = 66, Dysprosium. In fact, around 152Dy66 there are several identical bands. Because of my own experience in 1966, I paid closer attention to what Mottelson was saying than if it had been some other number. Then he started talking about the details and pointed out that that normally, the rotational moment of inertia would be close to the value for rigid body rotation. (That is for high enough values of the angular momentum so that pairing effects, which tend to lower the moment of inertia, have disappeared.) This would imply that I is proportional to A^5/3. So adding a nucleon should increase I by about 1 %, But also, the deformation could change, and if it decreases with A, then this would be a countervailing effect. In addition not all orbits contribute equally the MoI. So, to get two nuclear decay schemes with the same MoI, which means identical bands, several effects, each of which would contribute of the order of 1 %, would have to cancel. As of 1990, it was not clear what was going on, but there were several possibilities. One of them was that the cancellation was accidental. If you throw dice, some small fraction of the time, you will get all sixes, just by chance.

Behrman:

Right.

Moszkowski:

In any case, IdB occur only in about 15-20 % of the decays of superdeformed nuclei. So the IdB might just be due to accidental cancellations. That is certainly one possibility. The other possibility is that there was some symmetry, something underneath that makes it happen occasionally. Ben Mottelson described these two possibilities as “non-heroic” and “heroic” explanations of the Identical Bands. Altogether, I paid close attention to Mottelson’s talk. Later when the proceedings were published, there was not one word about the heroic or non-heroic explanation. Also, at least in the official version of his talk, there was no diagram that singled out the number 66, although such Nilsson diagrams did appear elsewhere in the literature. But there is a symmetry called pseudospin symmetry which can actually help to make the identical bands work, and that was in the published proceedings of the conference. Shortly after Mottelson’s talk, Mukerjee came up to me in the hall. She was working on identical bands herself, and expressed the wish to work with me on the subject. That was perfectly reasonable. In fact, she and I started doing just that later in the year and continued through 1992. This included short talks by her and by me at a workshop at Oak Ridge, arranged by Nazarewicz, Draayer and Bengstrom in March 1992. Unfortunately, however, these things never came to real fruition because time ran out. Her post-doc at Cal Tech expired, and in spite of Nambu’s best efforts (I also tried to help), Mukerjee was not able to secure another academic position in the United States. She started to work for Scientific American, and later she wrote a very instructive book about Winston Churchill as regards India, which is a whole other story.

Moszkowski:

Back in early 1991, I had started working on identical bands with Mukerjee and visited Cal Tech occasionally to discuss things. On one occasion, we were sort of joking, about our effort to save nuclear physics and ideas like that. The reason I mention this joking is because of what happened after I got back to West LA that day and looked at my email. I had a collaboration going with some folks in England, and one of them, Mark Kermode, had sent an SOS email to me and to hundreds of other Americans, which was along the following lines: Daresbury Lab, in England, the place where a couple of years before identical bands had been discovered, was going to be closed. Kermode and others were sending the alarm about this unwelcome news to as many physicists as possible.

Behrman:

Oh, dear!

Moszkowski:

Naturally I was extremely upset on hearing about this. What could we do about it? Normally, unlike some of my colleagues, I, Steve Moszkowski, stay out of politics. I was brought up that way and it is not my style. But on this particular occasion, I felt that this was so important that I had to do something. Esther, my spouse, helped me write a diplomatic letter. She composed the first part “It has come to my attention that…” followed by an attempt to explain why it would be a bad idea to close the lab. Also, I looked a little further into the circumstances of how this “Death Sentence” had been decided. We all known that there are finite resources. Not every lab can be kept going indefinitely. It took me a few days to get to the bottom of it, but here is what seems to have happened. The exchange rate between the British pound and the Swiss franc had changed, and the British had, of course, a financial commitment to CERN. They were members of it, and they had to come up with the extra money which was 6 million British pounds, to cover the change in exchange rates. So they established a committee to decide what to cut so as to save this amount. This is never pleasant. I believe that on this committee, there were no nuclear physicists at all, and apparently, there were no people who really understood what was going on at Daresbury Lab. But they knew that the budget for the lab was 6 million British pounds per year, which just happened to match what was needed to fix things with CERN. Thanks to the culture war, nuclear physics had been downgraded to the extent that it wasn’t even adequately represented on major committees that would decide allocation of funds. This was part of a general pattern. Many particle theorists look down on nuclear theorists, and that shows up in allocations of funds, positions, etc.

Behrman:

Wow.

Moszkowski:

It turned out that hundreds of other American and other countries’ physicists also protested this decision to close Daresbury, and the execution was postponed for a couple of years. So the efforts of Kermode and others did at least ameliorate things a little.

Now let me go on about my later interactions with Robert Sachs. In 1982, Sachs had written a biographical article about Maria Mayer for Physics Today how she was a twofold pioneer. I mean the great discovery, the rediscovery of the nuclear shell model and the fact that she was the second woman to win the Nobel Prize in physics.

Around 1990, Sachs was still working on the biography of Maria Mayer, and he wrote me asking if I could help. I don’t remember too much about this, but recently, checking my old correspondence with Sachs, I came across a long letter, actually about myself, which I had sent you in preparation for our first interview. This letter goes into details regarding some of the things I mentioned last week.

In 1991, I visited both Robert Sachs and Yoichiro Nambu, who also was a good friend of Sachs. Both were now at the U. of Chicago. In fact I have photos of both from that pleasant occasion. One of the photos is right in my home office near the computer. My association with Nambu, which I’ll come to a little bit later, was a very important development in my later career. It is nice to have that reminder of my visit with both Sachs and Nambu. I also have photos of my visit to the Fermi Lab accelerator on that occasion, where I first met David Saltzberg, the current chairman of the UCLA Physics and Astronomy Department.

Nambu was a very nice person, and one of his admirable qualities is that he was quite modest. He did not allow his fame to go to his head. I asked him, “What was it that got you inspired to try to develop the Nambu–Jona-Lasinio model?” and here’s what he told me. We all know that the deuteron is barely bound. The two-proton and two-neutron systems are barely unbound. So the two-nucleon system is close to the border between bound and unbound, which can be called, semi-bound. But why? The semi-binding is not obvious. If you look at this from the standpoint of meson exchange, you’ve got the meson-nucleon coupling constant and the meson masses. You can get semi-binding, by having the right relation between, say scalar meson and scalar meson-nucleon coupling constants. That you can do, but what is behind it? The Nambu–Jona-Lasinio model actually is able to, not exactly, but approximately—reproduce something like this to get the semi-bound system without simply saying, “We choose the parameters to have these values.” Semi-binding comes out organically as an aspect of the model.

Behrman:

Oh, interesting!

Moszkowski:

Nambu thought up the NJL model in 1960, before it became clear that nucleons are made of three entities. Nucleons are not fundamental particles. That came even later, so the NJL model is even a little bit more general than Nambu’s original formulation. That was extremely interesting itself, but even more striking is that the strength of the nuclear forces given by NJL can actually be derived. You have, of course, to trust the physics. All this made quite an impression on me, and I enjoyed the visit to the University where I spent a decade.

Moszkowski:

My next stop after Chicago was a Gordon Conference in New Hampshire. The first evening, at dinner, sitting across from me, was a physicist, Nancy Schmeing, with a gleam in her eye. She started telling me about her idea, concerning identical bands, the same phenomenon I had recently gotten interested in, but with a different viewpoint.

Behrman:

Okay.

Moszkowski:

Imagine that you are in some big hall and there’s a huge rotating football and you are inside the football, an egg shape. It is rotating. Now suppose you're close to the outer edge, i.e, the surface, When the ball rotates, it will bump into you. But if you are way in the interior, near the center, then the rotating wall won’t hit you, and you won’t feel anything. All this is considerably oversimplified, but it gives the idea. In superdeformed nuclei where the identical bands occur, if you're dealing with a system where the valence nucleons, the last ones, happen to be such that they are localized in the interior, so they never get to surface, then the orbit will not feel any rotation. Thus the moment of inertia will not change. You can look at this whole thing in more detail, in particular, at Nilsson orbits, etc. and it can make sense to some extent. That was Nancy Schmeing’s idea and I worked with her on it during 1991 and 92. She had me come up to Chalk River for a short visit during the next summer, and we talked a lot about her idea. But again, we were not able to reach a successful conclusion to this, because time ran out. There were budget cuts and she lost her position. I believe that now she reestablished herself as a translator, but it’s not in physics any more.

At this point, I would like to mention Peter Ring, a German nuclear theorist, who has done pioneering work on relativistic mean field theory of nuclei. Relativistic theory provides a simple mechanism that can explain a number of nuclear properties. One of them is the very strong average potential felt by nucleons, and the other is the existence of the famous spin-orbit coupling which played such an important role for the establishment of the modern shell model. In the language of relativistic theory, the average potential is the sum of a Lorentz scalar and a Lorentz vector potential. The spin-orbit coupling is proportional to the gradient of the scalar potential. With this mechanism we can understand why the spin-orbit effect is so large.

This effect applied to the NN interaction itself was extensively studied during the 1980’s and 1990’s by a number of groups. One particular pioneer in this project is Ruprecht Machleidt who played a leading role in developing the Bonn potential. A notable difference between more traditional theory and relativistic theory is that the latter generally leads to a larger value of the nuclear incompressibility. This is exemplified by the Bonn A potential, which fits NN scattering phase shifts quite well, but also leads to a rather stiff nuclear EoS. with K_NM close to 300 MeV. This may be a way of simulating quark effects more accurately than some non-relativistic models do. The latter tend to be local, like traditional Yukawa meson exchange, but relativistic theory leads to non-locality, which can be traced to the finite nucleon size. In the quark model, the nucleon is, of course, very naturally of finite size, due to the quarks. It is the latter which are points.

Especially during the 1980’s, the value of K_NM was a subject of some controversy. Giant Monopole Resonances can, in principle, shed much light on this question, except for uncertainty of surface effects. With simple assumptions about these, Blaizot and others concluded that K_NM is a little more than 200 MeV, much larger than the previous conventional wisdom, which had been based largely on one pion exchange potentials. However, at this time there were also experiments using Heavy Ion Collisions, from which it was concluded that K_NM was much larger, as much as 400 MeV. At the seme time, it was found that relativistic mean field theory generally lead to values close to 300 MeV. And a paper I had published in 1983 with Boguta using a simple version of RMF gave essentially this value. So this subject, the stiffness of symmetric nuclear matter, became quite controversional during the 1980’s, and is still an open question. I recall one time when a fan of the relativistic theory whispered in my ear: “Nuclear matter is stiff”. I rather suspect that history will prove him right, but who knows?

Ring had gotten interested in identical bands himself and published a paper on the subject in 1993, and I heard him gave an invited paper at a conference in 1994 on the subject. During the following year, there appeared a review article on identical bands, written by Witek Nazarewicz and some of his collaborators at Oak Ridge, who had done a lot of theoretical work on the subject. They discussed in detail the available evidence, and labeled the two possibilities, accidental or significant cancellations as “Non-heroic” and “Novel”. Unfortunately, by this time, Daresbury lab was no more, and the community, including Peter Ring, had lost interest in the whole subject of identical bands, but fortunately, not in the NJL model.

Behrman:

Right.

Moszkowski:

I’m not discussing here all my professional trips over the years. But there are some places which made a special impression on me, and I want to mention two, in particular, here. The first is the European Center for Theoretical Studies in Nuclear Physics and Related Areas (ECT*) in Trento. I have very pleasant memories of my visits there. The first one was in 1993 for a workshop. When I arrived at the station, David Brink from Oxford, who was in charge of the workshop, was there to meet me. I recall there’s a stairway underneath which is used to go from the train tracks to the street, but I had heavy baggage. So I just walked across the tracks with my bags. However, David reminded me of a little sign which was there: “È vietato attraversare i binari”, i.e. “You are forbidden to cross the tracks.”. [Laughter] That is, after I had crossed them. He kidded me about this. During the meeting, I had very nice conversations with a number of people, but I just mention Brink, who was a pioneer in a number of topics, for example, clustering, reactions, and also the Skyrme interaction that I’ll come to a little bit later.

Now a few words about collective models of nuclei, which played an important role in our discussions at Trento. There were two versions of collective models that were used in the 1970’s. One of them was, of course, the older Copenhagen model developed by Bohr and Mottelson and with many associates. This was the the geometric model where nucleons move in a nucleus that can get deformed, so you have to take into account the deformations. The other approach was that, because of pairing, you look at nucleon pairs outside closed shells as bosons, and you regard the nucleus, or at least the valence nucleons, as assemblies of bosons. That is for even-even nuclei. This is called the interacting boson model, and most of it was developed during the 1970’s. These two approaches are not exclusive. In fact, you can describe a lot of physics in terms of either one. But both models had constituencies of people who worked on them, resulting in competition for influence.

Behrman:

Right.

Moszkowski:

It turns out if you take the surface delta interaction really seriously, you can relate it to both the Copenhagen geometric model and the interacting boson model. Thus, I did not have to take sides between these two competing views of things. During the 1970’s and 80’s I coauthored a number of papers on the interacting boson model, the relation to surface delta interaction, etc., and this turned out to be quite interesting. I talked quite a bit at that ECT* workshop with Ben Mottelson, who had received the Nobel Prize already in 1975. We got along very well. We discussed the turf fight between the geometric model and the interacting boson model, and also the identical bands problem. It was quite a serious matter, While Mottelson’s sympathies were on the geometric side, he understood the interacting boson model as well. But he complained to me about some of the methods used in the discussion of the two models. Herman Feshbach told me once that he had tried to mediate this dispute, but he found that his efforts were a total failure.

By that time, by 1993, I had gotten interested in the Nambu–Jona-Lasinio model and in some of the tentative approaches which Nambu and Mukerjee had made to try to relate these things to nuclear structure. These, apparently, were not that easy to understand from the papers, and Ben Mottelson and I both had difficulty in that regard. But I expressed to him the view that these things could someday be understood, and that we’ll understand something about the identical bands which derive from this. I remember Ben Mottelson told me, “When you do, people are going to come out of the woodwork.” Also, it was a coincidence that the first train station on the way to Munich, half an hour away from Trento, is a nice town named Bolzano. Unofficially, it still is known by German speakers as Bozen, There is a funicular up to UberBozen from which one gets a beautiful view of the Tyrolean Alps. (To myself, I called it the Boson Heights). On my visits to Trento, I often used to go there for inspiration (and a nice Margarita pizza). Another of my fond memories is when I left Trento the first time after a couple of weeks. Quite a number of the physicists, including Mottelson, came to the train station to see me off. And I recall several of them walking with the train for a few seconds before it speeded up and us waving to each other. I just wanted to mention this particular trip, because it is one of my fondest memories.

During an ECT* workshop in 1997, Ben Mottelson gave a talk in which he emphasized that while normal nuclear matter is a Fermi liquid, it is quite close to the critical density where . crystallization occurs, i.e. it becomes a Fermi solid. This near criticality holds even more sensitively for liquid He4 at T = 0. The criterion for criticality involves the a of kinetic to potential energy, a “quantality” parameter. It is thus no surprise that, for zero temperature, He3 is definitely on the liquid side, while He6 becomes a solid. It probably is not a coincidence that both the 1S0 NN interaction and the interaction between two He4 atoms are slightly too weak to bind a two body system, for the latter case, just barely so. And finally, the interaction between two alpha particles is very slightly (less so than for the T = 1 NN system) too weak for binding 8Be. It is tempting to speculate that the near criticalities of these two-particle and many- particle systems are connected, but this has never been proven.

There have been many other interesting workshops at ECT* and I attended several of them during the 1990’s and 2000’s. These stimulated my interest in the nuclear three body problem. One famous kind of three body system is that of Borromean rings. Here the three possible two body subunits are not bound, but the three body system is. On one occasion, Esther and I actually made a trip to the Borromean islands which, like Trento, are in northern Italy, and have a fascinating history.

A little later, I started a collaboration with Jean Marc Richard, who also frequently spent time at ECT*, on the critical stabilities of 3 and 4 nucleon systems with simple interactions. Critical means zero binding. Later on, I started a collaboration with Zoltan Papp, whom I had first met in Debrecen back in 1988, and who later became a professor at Cal State Long Beach. We worked on two and three alpha systems. Here non-locality of the NN interaction seems to play a significant role.

The second place that I remember vividly is the University of Coimbra in Portugal. My interest in the Nambu--Jona-Lasinio model was shared by Joao da Providencia, a Professor of Physics at University of Coimbra. I had met him on a couple of occasions previously, and he kindly invited me to visit the University and give lectures on the subject, and also one lecture on my connection with Einstein. In subsequent years, I occasionally visited the University, including a conference in 2002, where I discussed the “taming” of the nucleon-nucleon tensor interaction at short distances. Later both of us got interested in the application of the Quark-Meson coupling model to dense matter.

I should add that the QMC model (not be confused with Quantum Monte Carlo) had first been proposed by Pierre Guichon in 1988, but somehow I did not learn about the model until I visited CERN and Magda Ericson explained it to me. The QMC model is a way to generate a finite constituent quark mass, which has both chiral symmetry breaking and confinement. (The Nambu—Jona-Lasinio model has chiral symmetry built in, but not confinement. So it cannot, without modification, yield reasonable nuclear saturation properties.) The original version of QMC uses the MIT bag model, but there is an alternative developed by Boguliubov which uses a Dirac oscillator model. For the last few years I have been working with Providencia’s group, using Bogoliubuv QMC to investigate dense matter, and especially neutron stars.

Let me come back to the question of the nuclear matter incompressibility. K_NM. There have been more recent developments on the nuclear Equation of State, somewhere between 200 and 350 MeV. But to this day, it has not been reliably pinned down experimentally. Of course, different theoretical models give much more precise predictions. However, a lot of what is known about low-energy nuclear physics does not depend all that sensitively on the exact value of K_NM. I should add that neutron stars, in the center of which density is close to that in nuclei, could, in principle, provide more of a constraint on K_NM. However, that is by no means certain, since neutron stars are generally closer to pure neutron matter than to symmetric nuclear matter, and the incompressibility of neutron matter has not been pinned down even as well as for SNM.

It is very good that I developed some familiarity with particle theory due to my interest in the NJL model. My interaction with Mukerjee and with Nambu certainly helped. But there are also two other famous particle theorists that I interacted with, starting at the University of Chicago, Murph Goldberger and Murray Gell-Mann.

I think I always had good relations with Goldberger. During my work at the University of Chicago in 1946-47, I shared an office with Mildred Goldberger, Murph’s spouse, and we were on friendly terms. Later, Goldberger was on my Ph D committee. He made numerous important advances in particle theory, such as his work with Gell-Mann on crossing relations, and the celebrated Goldberg-Treimann relations involving axial vector couplings. After that I did not see him for a long time. I read, however, that in the middle 1950’s he was instrumental in bringing Yoishiro Nambu to the University of Chicago. However, Goldberger evidently was unimpressed with the progress of nuclear theory. and at a conference in 1960 he commented that “Never have so many owed so little to so many.” What he meant was the inverse of what Winston Churchill had said about the folk heroes in England during the dicey time in 1940, when it was not clear that England could survive Hitler’s aggression. What he felt was that the way in which nuclear theory was being advanced around 1960 was not satisfactory. We were not really making good progress on understanding things. Murph Goldberger had a good case, but of course it got exaggerated. Many years later, from 1991 to 1993, he joined the UCLA Physics Department and at one stage his office was next to mine, and we often went to dinner after colloquia. So it appears that his attitude concerning nuclear theory did not affect our personal relations. When he left to join the UC San Diego Physics Department in 1993, he gave me a very interesting book on Sociobiology.

Moszkowski:

Now let me tell you about my encounters with Murray Gell-Mann, which were somewhat less positive, though they ended on a good note. Murray Gell-Mann, like Goldberger, had been on my PhD oral committee at the University of Chicago. He was much smarter than I am, and it is understandable that he probably did not have such an extremely high regard for my own intellectual abilities. By the 1950s, you could see clear signs of the more imaginative theorists choosing to go into particle physics, which was now at the frontier. Nuclear physics was no longer the frontier in the sense of getting to higher energies. Gell-Mann shared the Nobel Prize in 1969 for his pioneering work in the classification of nucleon states, and of course his role in the discovery of quarks. In particular, he played a leading role in developing current algebra during the 1960’s. This helped greatly in understanding quark dynamics even before the development of modern Quantum Chromodynamics. But Gell-Mann also had many interests besides physics, and one of them was bird watching and other environmental things. One day in 1970 he visited UCLA and gave a talk on bird watching. After the talk, I came up to him and asked him “What do you think of the state of nuclear theory today?” That may not have been the smartest way for me to initiate a conversation with him. Anyway, Gell-Mann looked at me very coldly and said, “Nuclear theory should be shut down.” I think those were his exact words. Obviously this reply did not make my day at all. However, I found out years later that the same Murray Gell-Mann was expressing similar sentiments in Washington to big shots at the DOE, at the NSF in Washington. [Chuckles] Now this would obviously make some nuclear theorists like Steve Koonin at Caltech and others extremely unhappy!

Behrman:

Yes!

Moszkowski:

That is another story. It was a reminder that, to some extent, intellectual questions also became a turf fight, a power fight because we all know, money doesn't flow from heaven. Things have to be funded. There are choices that have to be made, priorities have to be set. And you would expect that people in any field will try defend their turf. That’s the way things work in the real world. Now let me now fast forward to 1994. Julian Schwinger had just passed away, and there were symposia in his honor in a lot of different places. We had one at UCLA and there was a memorial session in Philadelphia. I just happened to be on the East Coast at that time, so I decided to take a trip to Philadelphia to drop in on that meeting and just hear what was going on. As I checked into the hotel, there was Murray Gell-Mann checking out! [Laughing] Now obviously I had never forgotten my conversation with him 24 years before, so this time I said something like “Murray, glad to see you. You might be interested to learn that recently I have gotten involved in the Nambu--Jona-Lasinio model”. At this, his eyes lit up, Gell-Mann was so happy about what I had told him, and he also mentioned what a nice name Yoichiro is. Gell-Man really admired Yoichiro Nambu, and they were good friends. This was a totally different conversation than what had happened a quarter century previously. Now I cannot read people’s minds. But I conjecture that, at least in Murray Gell-Man’s mind, I, Steve Moszkowski, had been redeemed.

Nambu was a pioneering genius. His ideas of spontaneous symmetry breaking, basically proposing color before it became fashionable, anticipating quarks and developing the Nambu–Jona-Lasinio model—these were pioneering things. In some real sense, it’s quite possible that my association with Nambu did in fact redeem me and keep me active, which is why I’m talking with you now.

Let me now go to the 1990s. My colleague Nina Byers, who unfortunately passed away in 2014, organized a project, “Contributions of Twentieth-Century Women to Physics”, first on the web, and then for a book. The web site is still up. The idea was to study a number of women who made important contributions to physics during the 20th century. There was a deliberate cutoff date. Nina Byers used 1975, as she figured that because if you bring in more recent work, it could cause problems with some of the women still active.

In 1996, very shortly after I got involved in the CWP project, there was an APS meeting in Indianapolis, and I was invited to talk about Maria Mayer, and was happy to accept. In the talk, I of course, focussed on her great contributions. Still, Mayer, like other woman scientists, had not so long ago been discriminated against, and I mentioned that, as well. But Maria Mayer was defined by her great contributions, not by the discrimination against her. Fortunately, this manifestation of sexism has been gradually decreasing, perhaps a little faster in astronomy than in physics.

I can understand that to ever get anything done in politics, you have to exaggerate things somewhat, or else it does not get attention. However, there are limits to this. I think that these days women are well represented in some areas, for example, as I said, astronomy. Physics still has to do more work to attain something like true equality. But what do you think here?

Behrman:

Well, I have different impressions, different experiences, but it’s not… This is your interview, not mine.

Moszkowski:

I had gotten my PhD with Maria Mayer, and had written a book with Madame Wu, so I knew something about both women physicists. And, in connection with the CWP project, I got familiar with the lives of some other famous women physicists. I branched out a little bit, and put some things about the history of nuclear physics on the web. There is a real danger that some folks may forget history, and the CWP project is meant to combat that.

Forty of the women on the website were included in the book, Out of the Shadows, edited by Nina Byers and Gary Williams, a professor at UCLA. I wrote the chapter on Maria Mayer. This book was published in 2006. I recall that we sent a copy of it to Germany by courier for chancellor Angela Merkel. She actually looked at the book and thanked us for it.

Behrman:

How nice!

Moszkowski:

Let me mention that neither Maria Mayer and Chien-Shiung Wu fitted what you would call the classic definition of a modern feminist. Neither of them was politically correct in the modern sense. But they both made outstanding contributions to their field. Neither of them was defined by gender discrimination, although both of them encountered it. I am very glad to have had the chance to work with both of them. I think both were kind of mother figures to me.

Behrman:

I guess on the topic of women in physics, what have been your impressions over the course of your career as to women in the profession?

Moszkowski:

Women in the labor force are necessary for our economy. It wasn’t like that 100 years ago. In those days, you were excluding half of the population from the labor force. You can think of it in that way. That situation had to be corrected, and, actually, has improved. at least to some extent. However, there is a caveat here. Men and women are constructed differently. Women, but not men, can have children, and this is not the only difference. The fact that Maria Mayer was the one who basically rediscovered the shell model should give us an important lesson here. The nuclear shell model was a tremendous advance in our understanding of nature. But it does not alter the fact that men and women are not identical. The difference has to be respected. But in no way does it justify feelings of superiority on the part of men. Still, this whole subject can be quite touchy.

If nuclear power ever makes a comeback—and I think there’s a significant chance that’s going to happen in the not too distant future, then it is essential that there should be some nuclear physicists around. I’m digressing here, but around 1990, I visited the University of Washington, and I talked to Vitaly Efimov, a very noted theorist who had just emigrated from Russia. He had pioneered in the few-body problem with his Efimov states. He told me a little more about what had happened at Chernobyl in 1986 than I known before. One important thing was that the people who ran Chernobyl did not know any nuclear physics. As we all know by now, they mishandled things in a number of ways. I hope that in the future, there will still be some talented nuclear physicists in our society. Roughly half of them should be women, we will need them in the labor force. All this is, of course, projecting to the future.

While Maria Mayer was the most crucial pioneer in developing the nuclear shell model, others as well contributed in important ways. For example, Hans Jensen, who independently figured out the role of spin-orbit coupling in the magic numbers. By the way, the story of Hans Jensen during WWII is a fascinating story itself. Did you ever see the play Copenhagen?

Behrman:

I have not been able to, unfortunately.

Moszkowski:

It is about the visit of Heisenberg to Copenhagen in 1941. What is less well known is that Jensen also visited Copenhagen in 1942, and talked with Niels Bohr. Also, it is part of history that Jensen was a member of the Nazi party. Apparently, he had to join to get ahead, but he also may have had some indirect connections with the Norwegian underground. While I met Jensen several times, we never discussed these matters. However, on one occasion he told me that he had figured out just how the spin-orbit coupling can stabilize those magic numbers, 50 and 82, one morning while shaving. .

You know, I’m not that young anymore. You can easily check that I’m 93 years old. Most people at that age are no longer active, but thanks to a number of circumstances, especially the existence of personal computer and the Internet, I consider myself still active. I am currently working with a physicist at Oak Ridge, Jirina Stone, who is studying applications of the Quark Meson Coupling model to various nuclear problems.

[Part 4]

Behrman:

All right. So this is the second series of interviews with Dr. Steven Moszkowski. My name is Joanna Behrman, and he has very helpfully agreed to sit down with me for another oral history on May 8, 2020.

Moszkowski:

Let me say something about my recollections of Enrico Fermi. I did not work directly with Fermi on research. I suspect that Fermi looked me over and figured correctly that I should go into theory. I would not have been a very good candidate for doing experiments. But I remember a very enjoyable party at the Fermis’ home in 1947. Also, I took several of his classes, and as is well known, he was a superb teacher. We are not likely to see another Fermi again. He was a superb theorist, experimentalist, and teacher, all three, and he knew physics backwards and forwards. So the University of Chicago was lucky to get him. And I was fortunate to have been at that University at the right time, though Fermi’s influence on me was probably indirect. There have been books written about Fermi. A very nice one, The Last Man Who Knew Everything: came out a couple of years ago.

Behrman:

It’s on my stack to be read.

Moszkowski:

Great! But I do want to mention something that’s related to Fermi. The physicist (actually, perhaps more a chemist) Leo Szilard, was a great guy in his own way. But we all have eccentricities and he certainly had them. I did not know him personally, but the reason I bring up Leo Szilard is because Enrico Fermi and Leo Szilard had a rather peculiar relationship. They had, in fact, more or less collaborated in 1939 on the number of neutrons emitted in fission. But their style was very different and they had difficulty communicating with each other. The reason I mention this here is because of Nina Byers—the same Byers who later directed the Contributions of Twentieth-Century Women to Physics which I talked about. During the early 1940’s, she was the unofficial middleman between Fermi and Szilard at the University of Chicago. Fermi and Szilard had different styles, and they were in some sense complementary. We all may see ourselves in someone. Obviously, I don't compare with Fermi. However, my style of doing things is probably closer to Fermi’s, being a little bit cautious. You might say conservative with a small c. Leo Szilard had a different style. Leo Szilard focused on the universe as he would like it to be, so he thought outside the box more than Fermi did. That’s why, for instance, he figured that he had to leave Germany well before most other Jews did. And he did leave in 1933. Of course, there is a famous story of how he thought of a possibility of a chain reaction while he was waiting for a traffic light on Southampton Road in London. And he took out a patent on the idea. This idea was definitely outside the box, though history proved it right. Measurements of atomic masses, as made by Aston were off by enough that it was not clear that it would be energetically favorable for heavy nuclei (that famous 200 MeV which is now taken for granted!) to fission into light ones. Szliard thought of a possible chain reaction involving Beryllium, but that hit a dead end when atomic masses were determined more precisely. Fermi was more of a builder. You build on what you have and extend it, and of course that’s what he did on many fronts. So there were sort of quite complementary elements in these two men. In the real world, you need both the Fermis and the Szilards.

Moszkowski:

It is no accident that I related well to Fermi to the extent that I interacted with him. I’m not so sure I would have gotten along that well with Szilard, but you never know. I’m not sure that I ever actually met him. Szilard contributed in his own unconventional way, in connection with Einstein’s famous 1939 letter to FDR. And he pushed the secrecy of the U.S. nuclear project, so the Germans never were able to figure out just what the U.S. was doing on the nuclear project. On the other hand, because of his background and utterances, Szilard was considered a security risk. I believe he was not even allowed into Los Alamos.

[Part 5]

Moszkowski:

Now, I would like to mention one aspect of Heisenberg’s life, which is relevant to my own memoirs. Let me give you my own perspective. Heisenberg is one of the people about whom movies and plays have been written. There’s Copenhagen and also the movie The Catcher Was a Spy and The Spy Behind Home Plate. Have you seen either one?

Behrman:

I haven't, not that play and those movies.

Moszkowski:

I’m not discussing the whole story here, but one of Heisenberg’s roles. In December 1944, Heisenberg was invited to Scherrer’s Institute in Zurich, Switzerland to give a talk. Switzerland was a neutral country, and the German authorities allowed him to go there. He gave the talk and in the audience was a man, Moe Berg, who had been a baseball star before, and was now working for the predecessor of the CIA. He was not a physicist, although he had now been trained in preparation for his own trip to Switzerland. His assignment there was the following; You see, the Allies were really worried, even in 1944, about Germany building an atomic bomb, or developing some weapon that could deprive the Allies of victory. (Goebbels was threathening to unleash a secret weapon to turn the tide against the Allies.) So Moe Berg had a gun in his pocket. He was prepared, under instructions, to kill Heisenberg right then and there, if necessary, if Heisenberg mentioned anything about fission or other hint of a secret weapon. Fortunately, it never even got close to this. Heisenberg had been working quite a bit on his own ideas about the S-matrix theory and a nonlinear spinor theory which not too many people understood, but that was one of the things exciting him. I suspect that some of the people in Los Alamos had sleepless nights, because they were desperate to get that bomb before Germany did. Of course, Heisenberg worked on reactors, but he was trying to develop a unified theory of forces even during WWII. But he talked about nonlinear spinor and S-matrix theory on that occasion in Switzerland. Probably not too many people in the audience understood what he was talking about. Moe Berg certainly didn't, but fortunately it had nothing to do with any atomic bomb.

Behrman:

Right.

Moszkowski:

The reason I mention all is is the following: After the war, Heisenberg continued to work on his ideas. These turned out to be not all that successful, but they were at least partially on the right track. When Yoichiro Nambu developed his model with Jona-Lasinio, one of the elements that got him started was Heisenberg’s nonlinear spinor theory. So Heisenberg’s model was at least part of the story. But another even more important element was the Bardeen-Cooper-Schrieffer theory of superconductivity which had been developed more recently, in 1957. Nambu combined the right elements of both of these ideas with original thoughts of his own to construct the Nambu–Jona-Lasinio model. The point I’m making is that Heisenberg’s efforts, even during the 1940s, may have helped in further developments, including the NJL model. As noted before, during the 1990’s I got (and still am) very interested in this model.

Moszkowski:

I want to come back to my pet idea: the surface delta interaction. The idea was basically driven originally by a desire to generalize Maria Mayer’s model of pairing. However, after the shock of 1966, I dropped it for a few years. I heard later that some of my colleagues were wondering, “Why isn't Steve Moszkowski pushing the surface delta interaction?” But, as mentioned before, I got interested in other aspects of the nuclear surface, like the Skyrme interaction, though later, during the late 1970’s, I again started to work on the surface delta interaction.

I think I had previously said something about my visits to Hungary during the 1970’s. The first occasion, in 1973, was for a conference in Balatonfured, and the title of the conference was “Correlations in Nuclei,” but my talk on Skyrme interactions was not about correlations. Neverthess, I talked about that anyway, since that’s what I had been working on. Now why do I mention this here? Because other people, maybe not the ones at that conference, like David Brink and Dominique Vautherin, also started to work on the Skyrme interaction and then many others started to do it, but with different values of the parameters. So, over a few years, many different Skyrme interactions appeared. To make a long story short, it became like a sorcerer’s apprentice story where an idea, a tool, gets out of control.

Moszkowski:

Now, why do I mention this? Because fast forwarding to the year 2004, when I first met my present collaborator Jirina Stone, I remember her telling me about her displeasure about all this huge variety of Skyrme interactions, by that time, more than 200. This was not the best way to do things. It didn't mean that the Skyrme interaction was wrong, but that some folks were overdoing it.

Behrman:

Right.

Moszkowski:

Surface delta means that in the interior, things cancel out, but not at the surface. Although this is only an approximation to what is going on in real nuclei, it may not be far from the truth. So, it is possible that the existence of identical bands might be a window of something like this occurring in some nuclei, although this is by no means assured. But it is why I regard the identical band problem as an unfinished story. And I also have some reason for optimism that we can, to some extent, explain the IB and relate them to the fact that we actually do have independent particle motion inside nuclei. With some luck, the story can perhaps be finished satisfactorily.

Have I left anything out?

Behrman:

No, you’ve covered everything.

Moszkowski:

Well, let me talk about Bethe and Nambu. Both were geniuses. They did things that I could never do, but they worked in different ways. Bethe had an encyclopedic knowledge about all aspects of physics. Also Bethe was much more sociable than I am. You might say that he had an an empire of people who were in his orbit.

Nambu was different. He had brilliant ideas. But he was not all that familiar with some details of nuclear physics. In some ways he was a bit like Einstein, with his inspirational ideas, way outside the box. The Nambu--Jona-Lasinio model was only one thing, and that’s what I got particularly involved in. He also was a pioneer in elementary particle physics, and he anticipated the vector meson, PCAC (Partially conserved axial vector current). Nambu won the Nobel Prize in 2008, and one can make a good argument that it was long overdue, Generally, there is a great deal of lobbying preceding these awards. These matters are not totally devoid of scientific politics.

Behrman:

Right.

Moszkowski:

With Nambu, the award came more organically. There was, probably not as big a lobbying campaign. If there had been, he would likely have gotten the award earlier. But he did finally receive it and that’s great. In an alternative world with a Nambu lobby, Mukerjee’s career might have been different, and for all I know, we might have made some real progress on the identical band problem. But in any case, Bethe and Nambu were both geniuses of different types. The world needs both types.

Let me finish with a short story illustrating this: In 1996, there was a celebration in honor of Ben Mottelson’s 70th birthday somewhere near Trento, which I attended. I got into a discussion with one of the people there, a very talented and well known nuclear theorist. We discussed my opinion about Bethe and Nambu as complementary type geniuses. To the physicist I was talking to, Bethe was a great genius and we agreed on that. However, the man I was talking with couldn't quite relate to Nambu. In the real world you need the analogy of nuclear people who know how to get things done, who may not in all cases be the most imaginative, but who, in a sense build the infrastructure. But you also need people who can think outside the box, and sometimes this includes utopian ideas, most of which will not work out, even if they provide great inspiration and motivation. But a few such ideas are successful, and very occasionally an idea comes long which changes the world. You need both kinds of people in the real world, both builders and geniuses.

I am very lucky to have been inspired at different parts of my career by both types of genius, by Hans Bethe and by Yoichiro Nambu. I appreciate that they, like Fermi and Szilard, were somewhat complementary. As I said, it is necessary to have both types This applies also to other areas besides physics. But some people have trouble understanding this. People who get really hooked on something may tend to think that “This is the answer”. They find it hard to relate to the fact that some other folks with different views, even if some of these views are not totally correct, could also have something useful to offer.

The fact is that I’ve encountered this situation in my own field of physics where at least theoretically you learn in books and otherwise that you are supposed to be open-minded, look at all viewpoints, and so on. Even in the physics community, the reality is often far from this ideal. So it is completely understandable to me that in the larger community, often you do not have open-mindedness, and it’s probably unrealistic to expect it. Still all of us can contribute, in our own way, to making this world, including science, a little better place!

[End of Interview]