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Bob Carter’s Interview (2018)

Manhattan Project Locations:

Robert Carter spent a year and a half as a graduate student at Purdue University before being recruited to work for the Manhattan Project. At Los Alamos, Carter’s team, which included his close friend Joan Hinton, worked on the research reactor. Eventually, Carter and Hinton came to work closely with Enrico Fermi, who became a mentor and friend to the two of them. Carter fondly recounts his dinners and hikes with Hinton and Fermi, both at Los Alamos and after. After the war, Carter enrolled in graduate courses at University of Illinois before returning to Los Alamos for fifteen years. For the rest of his career, Carter worked for various government agencies before retiring. Carter also discusses his friend Harry Daghlian and advising prominent physicist George Gamow on a project.

Date of Interview:
May 22, 2018
Location of the Interview:


Alexandra Levy: This is Alexandra Levy. I am here today on May 22, 2018, with Robert Carter. My first question for you is to please say your name and to spell it.

Robert Carter: Robert Carter, R-o-b-e-r-t C-a-r-t-e-r.

Levy: Great. Can you tell us when and where you were born, and a little bit about your childhood?

Carter: I was born in Philadelphia, Pennsylvania. My parents both grew up in Philadelphia. They were married there, and I was born there, but we did not live there hardly at all. I grew up mostly in small towns in southern/eastern Pennsylvania or New Jersey.

When I was a teenager, we moved to Maryland, the Eastern Shore of Maryland, near the ocean. I sort of claim I grew up there, because I was just thirteen years old. We continued living there until long after I went to college, even, my family still lived there.

Levy: Do you mind telling me your birthday?

Carter: February 3, 1920. 

Levy: What kind of an education did you receive, and were you always interested in science?

Carter: I went to public schools and, as I mentioned, we lived in small towns and so they were mostly small schools. Not very large enrollments in them, including my high school. The high school was in Berlin, Maryland, where we lived during my high school years.

My high school graduating class was less than 100 people. Probably a few more girls than boys at that stage, but I don’t remember exactly. I took a program in high school that would these days be considered a college preparatory program.

However, I had no thoughts or expectations that I would ever go to college, because my family’s income was miniscule, almost, and there was no expectation that I would ever be able to go to college. I had an older sister, and she did not go to college. She married shortly after she graduated from high school. 

In fact, I was one of two of my high school graduating class who did go to college. The vast majority were from farming areas around where we lived, and they had no plan or intention or money to go to college. The tradition at the high school was not even to think and talk about college. In contrast to what goes on these days at a lot of the high schools, I don’t remember any teacher ever mentioning the possibility of going to college while I was in high school.

Mostly, I did pretty well in my classes. There was one girl and I who took exactly the same program over our high school years—not by intent, but because they were the better courses and the more challenging courses. She and I took all the same courses, and we basically got all the same grades.

Towards graduation from high school, the principal called her and me into his office and he said, “You two have tied in your academic records for your whole high school program. We need to pick a valedictorian for the class.” He said, “You two both qualify, but the faculty don’t want to start a tradition of more than one valedictorian. They’ve asked me to come up with some scheme to distinguish between you, and see if there is a way to choose which of you is valedictorian.”

He got out the class books for all of the teachers and all of the classes we had taken in our four years of high school. She and I were good buddies. We dated a little bit—not much, but we went to senior prom together, for instance, and things like that.

The three of us, the principal and this young woman and I, went through all of the class books for all of our teachers for the whole four years. In many cases, the teacher would give “A,” but that doesn’t have a numerical value that you can quantify in a way. What we agreed on was, for different letter grades, we would assign a number, so that we could add up these numbers at the end and figure out who had the highest total number over the four years.

We did that, we went through it all. I remember the teacher of the physics class, which she and I both took, had put on the final report card “A++” for my grade. Because we were trying to assign a numerical value for letter grades, the principal asked me, “Bob, what do you think this means? What number can we assign to it?”

I said, “I don’t know what it means. You have to ask the teacher.”

The next day, the principal came back and said, “He says you know more physics than he does, and so this was about the only way he could figure to characterize that.” 

The principal and this young lady and I agreed that that qualified for a 100 on the numerical scale. Whereas, we had not been giving 100 for “A” previously. I forget the number we chose, like 96 or something like that, as a sort of an average quantifier number for a letter grade.

We added all these things up. I don’t remember the final numbers, but they were sort of typically like—I got 10,000 points and this young lady got 10,002. After going through all these things for a couple of days—and all day for two days, the three of us, the principal and this young woman and I, went through these books—we came out with numbers like that. I remember the principal looked at the two of us when we came out with these numbers. The difference was so insignificant that I’m sure the principal was wondering if any of this had been worthwhile.

I reached over and shook the hands of the girl, and I said, “Congratulations.” 

The principal said, “Wow. Thank you, Bob.” He said, “I don’t know how to thank you.” That’s the way the valedictorian of our high school graduation class was chosen.

Then I went to a small liberal arts college in Maryland, on the Eastern Shore of Maryland, in Chestertown. Our first year there I was not allowed to take physics. I took chemistry, which was allowed. Towards the end of the first year, we were required to pick a major and I picked chemistry. But I told the head of the chemistry department, “I don’t really want to major in chemistry. I want to major in physics. But I don’t want to sign up for physics until I’ve taken a physics course here in college and get to know the teacher, so that I’m convinced that I really want to be a physics major.”

The head of the [chemistry] department agreed with me. He said, “Okay, whatever you choose. I’d like you to be a chem major, but that’s okay.”

My sophomore year, I did take my first college physics course. I was satisfied that I really did want to major in physics, and that the physics teacher was an adequate sort of mentor and guide. I talked to him towards the end of my sophomore year, and we agreed I would be his physics major.

I was the only one in my college class who became a physics major. My college graduating class was also less than 100 people. The total college was small, and my class was actually one of the bigger classes, historically, through the college.

But I was the only physics major in my class. There was a physics major in the class ahead of me. But it turned out that during the summer between his junior and senior years, he enlisted in the military, because he wanted to become an Army Air Force pilot and he had the opportunity to do that. Instead of coming back to graduate from college, he went off into the Army.

Even in the beginning of my junior year, it turned out I was kind of the senior physics student of the physics teacher. In fact, he asked me to be his lab assistant. Typically at a small college, where there are no graduate students, undergraduates in their senior year are often asked to be lab assistants for the earlier grades. He asked me to be his lab assistant. Now, typically a junior is not asked to do that. But because there was no senior physics major by that time, he asked me. Both my junior and senior years, I was the lab assistant for the physics professor.

Towards the middle of my senior year in college, the physics professor developed some visual problem. I never fully understood it, the physiology or the medical terminology, but it turned out that he couldn’t do very much reading. It ended up that I did a large fraction of running the physics department my senior year in college.

For instance, there was an agreement between the local high school and the college that occasionally, if a high school teacher had to be absent for some reason—like being sick, and couldn’t hold the class—the professor from the college might be willing and able to fill in at the high school level, for just one class or two classes or so. Two or three times during the spring of my senior year in college, the high school physics teacher had to be absent and I was asked to fill in and teach the high school physics class, two or three times during my senior year.

Then, I finally graduated and ended up—the story is complicated, so I won’t elaborate very much on it—but I ended up going to Purdue University in Indiana as a graduate student, as a teacher in a program that taught Navy-enlisted men electricity concepts and electrical wiring, so that they could become electricians, practicing electricians in the Navy.  After they finished our sixteen-week program at Purdue, they were assigned to shipboard somewhere in the world on a U.S. Navy ship.

I taught there for about a year and a half, and also took a few graduate courses in physics and math. I also worked—part-time as a volunteer to start—at one of the major research facilities in the physics department, which operated a machine called a cyclotron. I worked there as a volunteer for a couple of months.

Then, they took on a classified project for the government that was, I learned later, one of the forerunner experiments for the Manhattan Project. Before the Manhattan Project was established in the Defense Department, there were quite a few universities around the United States where research was done related to the fission of uranium and the possibilities of having a fast, major chain reaction that could lead to a lot of energy and maybe a bomb. That was all before the Manhattan Project was started. When sufficient data were acquired at these various universities primarily, to warrant a big program, then the Manhattan Project was set up.

One of the principal laboratories, actually the final laboratory where the bomb tests would be made, was at Los Alamos. The team of research people at Purdue, with whom I worked, four research professors all as a group moved from Purdue to Los Alamos. Two of those men wrote back and invited me to come and join the program at Los Alamos, which I did.

Levy: What year did you graduate college, and then what year did you get involved with the cyclotron at Purdue?

Carter: I graduated in May 1942, graduated from undergraduate college. I moved to Purdue in early June, and then this classified project at the cyclotron started the first of October. The federal government’s fiscal year goes from October 1 to October 1. It was a one-year contract starting and running during the fiscal year 1942 to 1943.

Levy: What kind of work were you doing on the cyclotron at Purdue?

Carter: There was another graduate student, too, who accompanied me; we went together on the program. We did simple little things. We were graduate students without much experience, so we did simple repairing of little pieces of equipment.

 We did operate the cyclotron, we were both qualified operators of the cyclotron, which was a complicated device. We did that, and we helped make little parts and big parts, and put things together and take things apart. The experiment was fairly elaborate and required a lot of special equipment, specially designed and built equipment to do the actual measurements. We worked on these things.

But we didn’t know a whole lot about the concepts of what we were working on, of the physics, the basic physics. We knew a little bit, but we were not very experienced or knowledgeable about nuclear physics, and so we didn’t know a whole lot about it.

When we were invited—he also went to Los Alamos with me at the same time—we didn’t know very much nuclear physics. We knew that there was a fission of uranium. We knew that neutrons were emitted in the fission process. We knew that a relatively lot of energy was developed as heat energy in the fission process. We didn’t know much about the chain reaction process. We had sort of heard about it, but we didn’t understand it very well. It was not until we went to Los Alamos that we really were indoctrinated and educated about the physics related to the chain reaction, nuclear chain reaction and the fission process of uranium.

Levy: What was the name of the other graduate student who went with you?

Carter: His name was Harry Daghlian. After we moved to Los Alamos, we worked together in the same group for about six months. The group we were in pretty much completed its project in about five or six months. Then, there was a reorganization and Harry moved to a different group that occupied the same building we were in, but was a separate administrative group and had different scientific and technological problems and projects from the one I was continuing with.

Levy: How did you feel when you were invited to go to Los Alamos? Were you excited to keep working on the project, or just eager to work on a wartime project?

Carter: When the research team of professors left Purdue, they simply told us, “Hey, guys, we’re leaving, we’re going west. We can’t tell you why, where, or what the purpose is. But we think it’s important, so we’re all moving west.”

It was about two or so weeks later that I got letters from two of the men inviting me to come and join. They both said, “We think you could make good contributions here. We think you’d enjoy it, and we think it’d be worthwhile for you to come.” That’s about all I knew before I went there.

I had worked with these men for about a year—more than a year, with a couple of them—so I trusted them. I trusted their judgement and evaluation of my abilities and my interests. And so I moved to Los Alamos. My friend, Harry, felt the same way pretty much, so he moved with me at the same time.

Levy: How did you get to Los Alamos? Did you take the train, or drive?

Carter: We took a train. Purdue University is in West Lafayette, Indiana, and there was a train from Lafayette, which is a somewhat bigger piece of countryside—West Lafayette is primarily where the university is. It’s sort of an attachment to Lafayette, which is a bigger city. There was a train from Lafayette to Chicago, and then we changed trains and went on a train from Chicago, which ended up in Los Angeles, that train. It went through New Mexico, and so we took that train and disembarked from it in New Mexico, near Santa Fe. 

Levy: What did you think when you first got to Santa Fe? It must look a little different—

Carter: It was quite different. Actually, the train station was just a bar, and a big barn kind of building, as I recall, and not much more.

We were met there at that station. That was a little settlement called Lamy, New Mexico, and it was maybe twenty or thirty miles from Santa Fe. We disembarked from the train there, and we were met by a Women’s Army Corps employee in the Army. She was an enlisted woman in the Army. She was driving, and was our taxi driver and our guide.

She picked us up at Lamy, took us into Santa Fe, where we went to the headquarters office of the Los Alamos project in Santa Fe and we signed in there. She gave us some papers, and then this young WAC woman drove us up to Los Alamos and took people to finish signing in and get housing assignments, and things like that.

We were unmarried, and so we were assigned rooms in a dormitory space. There were a couple of men’s dormitories, and there were a couple of women’s dormitories. Those were set aside for unmarried employees, which we all were.

Levy: Was that 109 East Palace in Santa Fe with Dorothy McKibbin, where you went first to sign in?

Carter: That’s where we went first to get signed in, yes.

Levy: Did you get to meet Dorothy McKibbin?

Carter: Oh, yes. She was kind of the office person. There was no one else. She had no assistant, as I recall. She just ran the whole office, and apparently very effectively.

Levy: What was she like? Do you remember?

Carter: I don’t quite know how to describe her. She was a pleasant young woman. I don’t know how to describe her better than that.

Levy: Okay. That’s great. After you started working, when did you find out that the goal of Los Alamos was to design and build an atomic bomb?

Carter: As I recall, we got signed in the day we arrived, and then the next day, we went to work right away. The team of professors with whom we’d worked at Purdue were all there, and we greeted each other and talked for a while. Then, they gave us piles of documents that had already been written and assembled at Los Alamos, describing the nuclear chain reaction in detail, and how it could lead to a bomb if proper conditions were provided.

So, within a few hours, they had informed us of what the project was pretty much all about. There were no evident restrictions, because of security classification, on what they told us. They told us everything that we needed to know and that we were authorized—well, we were authorized full disclosure of all information, but some of it was pretty technical and involved. But they told us the whole project right away.

The group that we were assigned to, which was really primarily the set of people who had been at Purdue, they constituted most of the group we were assigned to work with at Los Alamos. The project that they had was to design and build and operate and make measurements on the operating conditions of a special nuclear chain-reacting system, called the water boiler and was a called a research reactor. With modifications, it was turned into what was called a research reactor.

A research reactor is one where basically there’s uranium in a form that can lead to a self-sustained chain reaction, and emit neutrons and gamma rays. Those neutrons and gamma rays can be controlled and led to do experiments of the interaction of those radiations with materials, with nuclei of other materials. That’s basically what it was about. We completed that project, pretty much, by about early May of the spring of 1944.

Levy: Were you there when the water boiler reactor went critical for the first time?

Carter: Yes. It turned out that during the winter—well, before we got there at Los Alamos, we got there in December of 1943, Harry and I. The team from Purdue had already pretty much designed the final configuration of the water boiler reactor, and all of its controls and readout devices for getting information.

But the equipment was being made in the shops, in the mechanical shops and the electronics shops. Then, as these components came out, the professor in our group who had designed it and planned it generally came to me and said, “Bob, help me test this, so we make sure it meets all the specifications and does what it’s supposed to do.” These four men who had been at Purdue, each one successively came and asked me to help them test the equipment, which I did. Harry helped some, but not as much as I did.

After a while, by about March of 1944, all of the equipment was available. I helped assemble it, and I helped run through all the tests to verify that the equipment met all the specifications and requirements. By early April, it turned out I was about the only person in the group who had worked with all of the equipment, just by chance of working with each individual leader of the project. When we got the whole thing assembled I was, by default, the operator of the system, of the whole reactor system.

The fuel for that reactor was enriched uranium that was produced at Oak Ridge, Tennessee. That was going to be the first self-sustained nuclear chain reaction with enriched uranium. It was kind of a step towards a fission bomb. There were a lot of differences, but it was a step towards a fission bomb. A lot of the data that we acquired was applicable to the design of the bomb physics.

It turned out that when we got to the point of our system going critical, I was at the controls. Each project at Los Alamos at that time—and there were lots of projects, all aimed towards the final bomb configuration and success—when each one was getting towards the finish of their project, there was a seminar. Usually, the group leader would give the seminar, describing his project and its implications. But my group leader of the group I was working in came to me and he said, “Hey, Bob, why don’t you give our seminar this time?” Instead of his doing it, he asked me to do it.

I asked him, “Well, what should I talk about?” 

He said something like, “Whatever you want. You choose.”

I gave the seminar, and as I recall, Enrico Fermi and Dick Feynman and Emilio Segre and some other people—Hans Bethe, probably—were all in the audience of my seminar. I remember one of them, a man called Emilio Segre—who had been a student of Enrico Fermi in Italy before the war, and who in the 1960s got the Nobel Prize for some later work he did—he asked me a question. It was a fundamental important question, but it was one that I hadn’t seriously considered.

I hesitated, I remember, up at the chalkboard; I was talking and drawing things on the chalkboard. I remember I hesitated a little bit, and Enrico Fermi spoke up. He was in the audience, and he spoke up and turned to this man, and he said, “Well, you know, the way I would see that—” and then he went on and explained.

I sort of nodded towards Enrico Fermi and sort of smiled to him, and he smiled back at me. Afterwards, I talked to him and I said, “Thanks so much for answering that question.” I said, “Thanks for guessing that I didn’t know the right answer.”

He said, “Oh, well. That’s the way it is.” 

By that time, Enrico Fermi and I had gotten to know each other fairly well. In fact, when our system first went critical, I was at the controls. Based on previous measurements we were able to predict when it was going to go critical, under what conditions. I was starting to approach those conditions with the controls, and my group leader, who was sitting next to me, he and I were at the controls and Enrico Fermi was sitting beside me. 

This project was his idea to start with, and so he was very interested in the results. He was actually living and working in Chicago still at the time, but he had come to Los Alamos frequently as a consultant during the spring while we were assembling the system, so I had met him and gotten to know him fairly well.

Anyway, as I was approaching this criticality condition with the controls, my group leader leaned over and he said, “Bob, why don’t you let Enrico take it critical?”

I didn’t hesitate to think or consider it, and I turned to Enrico Fermi and I said, “Would you like to take it critical?”

He said, “Oh, yes!”

I had already showed him at a previous time the manipulation of the controls. He was very, very interested in all the details of what our project was like and how it was going. The controls were very well designed, so it was simple to take it critical. It was just a matter of doing it carefully. And so, Enrico Fermi took it critical.   

Afterwards, I thought, “Now, doggone it, I could have been an historical figure if I had kept it going, instead of turning it over to Enrico Fermi.” But, that’s the way it was.

Levy: Who was the group leader that you mentioned?

Carter: His name was Donald Kerst, and his regular life was as a professor of physics at the University of Illinois. He and one of the Purdue professors had been office mates in graduate school several years before. I think that was part of the reason our team from Purdue was assigned to this man. 

Kerst was already at Los Alamos before these other people came. I think because they knew each other, our set of people joined Donald Kerst on this project. He was just starting to assemble a group of workers, so our team was the appropriate group to start working on it. We had no experience with that kind of thing. None of us did. But we were all quick learners, I guess.

Levy: Did you stay in the water boiler reactor group through 1945?

Carter: Yes. In fact, at the end of the spring work, when we completed the first set of measurements and pretty much wrapped up the use of that first water boiler reactor, about that time Enrico Fermi and his family moved from Chicago to Los Alamos. Enrico Fermi was going to be there full-time, rather than just an occasional consultant. The laboratory management, [J. Robert Oppenheimer] Oppenheimer and whomever, had to give Fermi a high-level job of some sort. He couldn’t just walk in and say, “I’m doing it.”

Enrico Fermi was made a division leader, and he chose our group as being in his division. He started coming to our laboratories frequently, and he planned that we would build a bigger and better water boiler-type reactor to use for additional research.

During the summer and the early fall of 1944, he was living in Los Alamos and coming to our laboratory to work, quite frequently working with us. He liked to get into the laboratory and get his hands on things. Even though he was also an excellent theoretician, one of his real loves was to get his hands on pieces of equipment and work with them. So, he came frequently to our lab.

I guess almost by default, he chose me and a young woman, Joan Hinton, to be his lab assistants. When he would come and have an idea of what he would like to work on, he would come over to me or to Joan Hinton and say, “Here, this is what we’re going to do,” and start laying out a plan for doing some measurements or experiments.

Joan Hinton and I eventually became his more-or-less full-time lab assistants. Later on, in late 1944 and early 1945, he came to the lab almost on a daily basis to work with us. We became pretty well enmeshed in things together.

He also liked to be outdoors, and the Los Alamos general environment was excellent for being out hiking, skiing, camping, things like that. I had done a lot of that while I was in high school—not skiing, but other things, hiking and camping—so I enjoyed doing that at Los Alamos, too. Joan Hinton liked that. She had grown up in Vermont, basically on a school-farm that her mother ran, so she liked the outdoors. And Enrico Fermi liked to get out hiking and skiing.

Generally, the three of us on Sundays—we worked six days a week—but on Sundays we would very frequently get together and go someplace up in the hills, or the mountains, or on the ski slopes or whatever. Sometimes it was just Enrico Fermi and Joan Hinton and I, just the three of us, who went out hiking or skiing. He had his car. I had a motorcycle, but you couldn’t take skis on a motorcycle very easily. I did it once, but never again. Anyway, Enrico Fermi had his car, he liked to drive, and the three of us sometimes would end up going together on a Sunday.

I remember one time, when the three of us went out on a Sunday hike. In those days, Joan and I, among others, would eat our meals in an Army mess hall. That was the way the Army provided some of the services for us. The unmarried people didn’t have a restaurant or a variety of places to go for meals, and pretty much all of us ate in the Army mess hall.

They had specific schedules of when they served. A few times, when we got back from a Sunday outing, it was after the mess hall had closed for the evening. I remember one time in particular that Joan and I were out with Fermi, just the three of us, and we came back to his house. It was after the mess hall had closed, so he invited us to stay for dinner.

He had two children, about a thirteen-year-old daughter and about a ten-year-old son. At their house, they had a simple little rectangular table in a little alcove in the corner of one room. That was their only eating table surface. I crawled back to get in the corner, and Joan and Mrs. Fermi sat on one side of the table and the two children sat on the other side. Enrico was at the head of the table.

They decided to have waffles, I remember, and Enrico insisted on making the waffles. I remember he made a waffle, and dug it out of the waffle iron very nicely. He tossed it to me at the other end of the table, without warning or anything. He just got it out of the waffle iron and said, “Bob, catch!” Here came this waffle to me, and I was able to catch it and divided it up among the four people, Joan and Mrs. Fermi and the two children. Then he went on and made more waffles, but the first one came to me by air. But that was kind of an illustration of our relationship, I think.

Levy: It sounds like Fermi was quite a good mentor to you then.

Carter: Yeah. He was able to relax. There was no outward indicator that he was a Nobel Prize physicist, one of the world’s wisest and best physicists. He was just an ordinary guy with a waffle, as far as I was concerned.

Levy: Can you tell us a little bit about Joan Hinton? She had such a fascinating career—and your friendship with her.

Carter: Yes. Joan’s family—her father was not living with them, I don’t know the story about that—but her mother started a private school in Vermont. Joan grew up on this. It was a farm, but it was a school also. There were some fairly famous people who apparently attended that school, some movie stars’ children and so forth. But Joan grew up on that farm and that school, and then went to Bennington College in Vermont. Partway through her program at Bennington College, she went to Cornell on a summer internship and worked in the physics department.

One of the men she worked with there was one of the ones who came to Purdue to work on our project there. Then, he was one of the ones in our group at Los Alamos. I don’t know all the ramifications, but he hired Joan Hinton to join our group in Los Alamos.

When she arrived—about a month or so after I arrived at Los Alamos—my group leader took her around, introduced her around, and then he brought her to me. He said, “Bob, why don’t you help Joan learn more about what’s going on in our group, and help her get some work to do.”

She and I started working together, and we enjoyed each other’s company at work. We sort of complemented each other as far as ideas. She was a very good physics student and worker, and liked to work with her hands also. She was a good skier. She liked hiking and things, and so she joined with us doing that. Eventually, she and I spent a large fraction of our time together during 1944 and 1945, until after the war was over.

Among other things, we went to the Trinity Test shot on my motorcycle, she and I, the two of us went there and hiked across the desert in the dark, pushing the motorcycle and climbing a hill. There was another couple from Los Alamos who also met us there, but they had their own car and went their separate way. Joan and I went down and back between Alamogordo and Los Alamos on my motorcycle.

Levy: What was it like for you both to witness the Trinity test?

Carter: We didn’t know what to expect. None of us had ever really seen a big explosion, and had no feeling for what one would be like.

We were sitting on a hillside, and we didn’t know for sure when it was going to be detonated or what would we see. One of our leaders had told me very clearly where to sit, what part of the desert to climb across, and things like that. He was going to be at the test site as one of the working team, but Joan and didn’t need to be there for the actual test, so we weren’t invited. We went uninvited, but with the full knowledge about where to go, but never having seen the place before. She and I and this other couple went and were sitting on the hillside, waiting for it to be detonated. We had known it was going to be early morning before it was detonated.

Then, all of a sudden, the whole world lighted up, it seemed. The cloud formed, this typical mushroom cloud developed. The sound wave—or the shockwave, I call it—sound travels a lot slower through the atmosphere than light does. The light shows up almost immediately. This huge cloud of molten material, which is emitting many, many photons of visible light, shows up almost immediately at the detonation. But the sound takes quite a while to get through several miles away.

We were about fifteen miles, I think, from the detonation point, and the shockwave took about a minute to get to us after we saw the light. We didn’t think ahead to time how long it might take the shockwave to get to us, so we could judge how far we were from the detonation point. It must have been about a minute that it took the shock and the sound wave to get to us.

By that time, we were sort of just awestruck by the visual things. When the shockwave came, it was surprising and startling to us, and it was very, very loud. It was sort of a valley many miles wide with hills around, and the sound echoed back and forth around in this, between these hills and the valley. It rumbled on for quite a while. It wasn’t just one bang. It just rumbled back and forth around in this big valley. The sound kept coming for quite a while.

I never saw anything like it before. Later on, after the war, I did attend some bomb tests in Nevada, so I got accustomed to the idea, eventually. But that first shot was just awe-inspiring, both the visual and the audible aspects of it all. It was bigger and more impressive than I had guessed it might be.

Levy: Did you and Joan stay in touch after the war ended?

Carter: Yes. After the war ended, people started leaving Los Alamos because the project was completed. Enrico Fermi moved to the University of Chicago. An institute was set up in his name at the University of Chicago, and he moved there. Joan went there as a graduate student. For various reasons, I decided to go to the University of Illinois and do graduate work with Donald Kerst as the professor.

Joan and I kept in touch. We were still good friends. I went to visit her in Chicago from the University of Illinois in Urbana-Champaign a few times while she was in Chicago. I would write, tell her I was coming on a certain time. There was a train that went from Champaign to Chicago. I wrote, and told her I was coming.

Evidently, she told Enrico Fermi that I was going to be coming. When I arrived there in Chicago and she met me at the train, we walked over to Enrico Fermi’s office and just wandered into his office. In hindsight, I thought, “That’s kind of crazy. Here’s this Nobel Prize-winning physicist with this institute in his name just sitting there relaxing, and we walk in without any announcement, with no checking by a secretary even, or anything like that.” We just wandered in and started talking. I did that about three, maybe four times.

One time I had arrived, and we were in his office, and he was sitting behind his desk in a chair. Joan and I were sitting in front of his desk, like this. He stood up and he said, “Bob, would you mind looking at my throat?”

I was sort of startled, but I got up and the two of us stood there together and I said, “Open your mouth.” When he opened his mouth, his tongue was sort of in the way and I couldn’t see his throat. I remember, I reached over and picked up an ordinary pencil from his desk and depressed his tongue, so I could see his throat.

I remember Joan laughed, and she said, “You guys are crazy.”

But his throat was quite red and sore-looking, and so I told him this. He said, “You know, Bob, other than a doctor, you’re the only one I would think to ask to look at my throat.” I felt good about that.

One of the times when I went up to visit, the three of us, Joan and Enrico and I, decided we were going to go for a hike someplace in the Chicago area the next day. He said, “Why don’t you come over to my house after dinner, and we’ll make a plan.”

Joan and I went to his house, and he got out a big map of the Chicago area and laid it out on the floor of the living room. The three of us, Enrico and Joan and I, lay on the floor like spokes of a wheel looking at this map, trying to decide what kind of a place we could go hiking in. I remember, we were still lying there looking at it and talking about it when Mrs. Fermi came through the living room from the kitchen. She had been in the kitchen doing stuff, and she came through. I remember she looked at us and said, “Well, when you three kids finish doing that, be sure you turn out the lights and lock the door.” Then she went on, presumably into the bedroom. But we made a plan.

The next day, Joan and I went over to his house. He drove us out to a little park that we had picked out on the map out on the outskirts of Chicago, and went for a nice hike out in the woods. There were occasions like that that.

Eventually, I met a woman at Illinois that I decided I wanted to marry. The thought, I guess, between Joan and me was—she was much more of a social person, in a way, than I was. She, even at Los Alamos, would occasionally talk about going to China and helping the peasants of China get out of their rut and become real citizens.

I didn’t want to go to China, and I also didn’t feel it was right for me to interfere with her life if she was so intent on doing that. I guess I felt, “I don’t have a right to change her life, and I don’t want to go to China, so we don’t have a future together as a couple.” But I thought we would continue to be good friends. I guess I was kind of naïve, that a man and woman can be good friends and not married or something. I didn’t think in terms of marriage because I didn’t want to go to China, and I didn’t want to prevent her from going.

I met a fellow graduate student at the University of Illinois who was in most ways compatible with my ideal of a wife. We dated and married.

I guess Joan probably had different expectations than I did. We didn’t really talk about it. But shortly after I got married at the University of Illinois, Joan left the University of Chicago and moved to China.

She had an older brother who had also gone to China, and that had influenced her thinking, I’m sure. Her older brother had a roommate in college who had gone to China as part of what’s called UNESCO, United Nations Educational, Scientific and something or other [United Nations Educational, Scientific and Cultural Organization], I forget. He was a farmer, he had studied farming at college, and he had been Joan’s brother’s roommate in college. Joan and he had become friends, and so when she moved to China in 1948, she met up with him and eventually married him over there and had a family, and lived there the rest of her life.

After my wife died—not because of anything, except just coincidence—about a year after my wife died, one of my daughters-in-law set up a group tour to China, and I joined them and went to China. I met up with Joan and some of her family in China, and spent a day and an evening with them. I had dinner at their house, and things like that.

Among other things, one of her sons and her daughter and a grandson all happened to be there. Her husband was still alive, but he was not well. Joan was fairly healthy, but the rest of her family, her husband and her son and her daughter, all had some kind of illnesses, chronic kind of illnesses, of various kinds. They all went off and took a nap in the afternoon.

Joan and her husband were living on and running a dairy farm outside of Beijing, China. Joan took me around and showed me all the ins and outs of an experimental dairy farm, while the rest of her family were off taking their siesta, or early afternoon nap. I stayed through dinner, and then went back to my hotel in Beijing. They provided transportation for me, took me back.

Among other things, I remember while we were eating dinner, Joan announced to her family, she said, “You know, for two years, Bob and I did everything together.”

I sat there and thought, “Now, I wonder what they’re thinking.” I said, “Well, you know, everything we did, we did together, but there were some things we didn’t do.” Her daughter sort of nodded at me, I guess. She had about a six or seven-year-old son by her marriage at that time.

 There are a couple of little stories about Enrico Fermi that I wanted to mention. After I got married, I stayed at Illinois for about another year, and then moved back to work at Los Alamos. I did not finish my PhD, but I had finished most of the coursework for a PhD. But for various reasons, I was getting disgruntled with graduate work and moved back to work at Los Alamos.

Enrico Fermi knew I was back there. He was still consulting at Los Alamos frequently after the war. He had a graduate student who spent a summer at Los Alamos working in a different group, not the group I was working in. He was working on his PhD thesis at the University of Chicago under Fermi, and apparently this graduate student was having some problems with an experiment he was trying to do.

Evidently, Fermi told him, “Well, while you’re at Los Alamos, go talk to Bob Carter. He can probably help you solve it.”

The graduate student came to me and said, “Have you worked on this kind of stuff?”

I said, “No, but Fermi knows I can think about things.” We talked about it, and I guess I helped him solve a little bit of it.

A year or two later, one time, a man named George Gamow—I don’t know if you’ve heard that name—Gamow was a very clever physicist, but he was from Russia. He was not allowed to work on the atomic bomb, the Manhattan Project. But he was at a university by that time in the United States.

Then, after the war, when the secret of the bomb was out and everything, he was allowed to come and work at Los Alamos. He did, and he came there, and he had ideas galore. He was always thinking of new things. Apparently, he mentioned to Enrico Fermi one time that he was thinking of a physics-type experiment, and he asked Fermi if he thought it would be possible to do it with a research reactor. I was working at the research reactor in Los Alamos by that time. This was maybe 1951 or so.

George Gamow called me and asked if he could come talk to me about his experiment. I agreed, because he was a world-famous guy. He came to our lab, came to my office. He said, “I talked to Enrico and he said he thought it might be possible to do this with a reactor, and that if it was possible, you would be able to do it. That’s why he sent me to talk to you.”

That was nice to hear. I let Gamow explain to me what his idea was. There was a fundamental flaw in it, as far as I was concerned, as far as doing it with a reactor. It could be done with an accelerator of some kind, but not well with a reactor. I got back up to the chalkboard and showed him where the difficulty would be. We talked for a while longer, and he thanked me and went away. In hindsight, I thought, “Oh, golly, I just snubbed George Gamow and his clever idea. Why am I doing this sort of thing?”

Anyway, that was my little interaction with George Gamow. But in both of those cases, Enrico Fermi had suggested they come talk to me, and that I could perhaps help them solve their problem. I felt good about his thoughts.

Levy: Were you at Los Alamos for most of your career, then?

Carter: I stayed there from the end of 1948, when I left the University of Illinois, until the fall of 1963. Then I moved to Maryland to work at a special laboratory there. The laboratory I moved to in Maryland was a result of the Department of Defense thinking about an atomic bomb war.

Even though nobody wanted a war, there was a lot of worry that there might be a war, because the Cold War between the Soviet Union and the United States was sort of at its peak in those days. Both the United States and the Soviet Union had been testing various atomic bombs in the 1950s and the early ‘60s. They had been testing them primarily in the atmosphere, and were contaminating the atmosphere with radioactive isotopes of various kinds. People realized that this was not a good thing.

John Kennedy in 1962 was President of the U.S., and he made an edict: “No more atmospheric testing of atomic bombs by the United States. If you do any more testing, it’s going to have to be controlled and confined in some way.” 

The U.S. military services, the medical departments of the U.S. military services—the Army, Navy and Air Force—had been doing animal tests. Each time there was an atmospheric test of a bomb, they had been doing animal tests to try to understand better the radiobiological responses of animals to the radiation. If there were not going to be any more atmospheric tests, the military medical services were no longer going to be able to do studies of radiation biological effects. They decided to build a laboratory to try to simulate nuclear bomb radiations in a laboratory environment.

That’s the laboratory I went to work at. I was hired to simulate the radiation fields of a detonating bomb within the laboratory space. The laboratory I went to work at in Bethesda was called the Armed Forces Radiobiology Research Institute. Its objective was to try to design and build and operate facilities that could simulate radiations from atomic bombs. I was the head of the Physical Sciences Department, and I was the one responsible for doing that, making these devices that would simulate the radiations from an atomic bomb. 

Then, the Cold War changed, and the whole aspect of atomic war changed. The basic ideas of the laboratory no longer were important. I left and went to work for other agencies in about 1975, I guess. I worked at different organizations of the government from 1975 until I retired.

Levy: Do you have any final story you want to wrap up with, something we haven’t gotten to yet?

Carter: Well, one little thing, I guess.  Again, it’s a personal thing with Enrico Fermi.

While I was still at the University of Illinois, but after Joan Hinton had left Chicago and gone away, my dad died of a sudden heart attack. My wife was expecting our first child, and so she could not go with me to the funeral. My dad lived in Maryland still, and we were living in Illinois.

I got this message that my dad had died, so I was on my way from Chicago to Philadelphia for my dad’s funeral services. I was waiting in the airport in Chicago for my plane to come. I remember I had just learned an hour or two before that my dad had died, and so I remember I was sitting there in the waiting room pretty glum about life in general.

Enrico Fermi walked up to me. I looked up, and there was Enrico Fermi. He said, “Bob, you look awful. What’s wrong?” I told him briefly. He sat down beside me, put his arm around my shoulder, and tried to comfort me. That was one of the last times I saw him. Although, I saw him later once at Los Alamos in about 1952.

After Joan Hinton moved to China, she wrote letters back to her family about what she was doing and her activities. She sent a copy of several letters to Enrico Fermi, because they had become really pretty good friends—the three of us. She had sent copies of the letters to Enrico Fermi, but not to me.

Fermi brought them to Los Alamos on one of his trips out there in about 1952, or something of that sort. He brought them to me and he said, “Here, Bob, you’re probably the appropriate person to have these letters.” He gave me this pile of letters that Joan Hinton had written to her family, primarily, but copies to him.

I guess that was the last time I saw him. He died two or three years later of a stomach ulcer, I guess, or stomach cancer. That was probably the last time I saw him, although I did talk to him on the phone one other time. My little conversation with him on the phone was, two of the other workers at Los Alamos had an idea to try to measure neutrinos. Neutrinos were almost a figment of somebody’s imagination to solve an energy balance problem. Gradually, everybody started believing they were real. But they didn’t interact with matter very well, so it was not easy to measure them and actually detect them.

Then this pair of men, both of whom were friends of mine at Los Alamos, came up with an experiment to do it. They had come to me and asked me if I would do some work at our research reactor to help calibrate their systems, because they needed an independent way of calibrating their detecting systems.

I was skeptical that they were really going to get data for me to make any experiment worthwhile for me to do. It was going to be a fairly elaborate experiment, as far as I could see. I asked them, “Are you convinced you’re really going to get data?” I said, “I don’t want to do a big elaborate experiment, and then not have it be useful for anything.”

They sort of tried to convince me. I said, “Have you talked to Enrico Fermi about this experiment?” Because Enrico had done some theoretical work related to neutrinos and things.

 They said, “No, of course not.”

I picked up the phone, and I called Enrico Fermi. He was at Los Alamos for a consulting visit. I called him and I asked him what he thought of their experiment. Did he think they were really going to get data?

He said, “Bob, I think it’s a 50/50 chance that they will get data.” Then we talked a little bit more, and then I hung up.

These other two men, they both were PhD physicists with quite a lot of experience. They looked at me and said, “Who did you really call?”

I said, “I called Fermi. Why?”

“You mean you called Enrico Fermi? Just like that?”

“Well, yeah, he and I are buddies, and I trusted his answer.”

Eventually, they did go on and do the experiment, they got data, and I did the experiment they hoped for and calibrated their systems as we had expected. Eventually—one of them died early, unfortunately. But the other one shared a Nobel Prize because of the work.

Over the years, I’ve co-authored papers with three or four Nobel Prize-winning physicists, but never got there myself, of course, nowhere near.


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