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National Museum of Nuclear Science & History

Dieter Gruen’s Interview (2015)

Manhattan Project Locations:

Dieter Gruen joined the Manhattan Project at Oak Ridge in September of 1944, shortly after his graduation from Northwestern University. His work primarily focused on the chemical problems related to the separation of uranium isotopes. In response to difficulties determining the difference between uranium nitrate and uranium peroxide in the final stages of separation, Gruen created an entirely new material: sulfonated copper phthalocyanine. This indicator maintained stability in nitric acid, allowing for the easy identification and eventual extraction of uranium nitrate. Immediately after the war, he helped form Oak Ridge Scientists and Engineers, a group dedicated to ensuring the future prevention of the use of nuclear weapons in war. In this interview, Gruen discusses the secrecy related to the project, the relatively lax safety standards of the period, and the differences between government support for science in the 1950s and government support today.

Date of Interview:
February 16, 2015
Location of the Interview:


Cindy Kelly: I’m Cindy Kelly, Atomic Heritage Foundation. This is Monday, February 16, 2015. We are in Pompano Beach, Florida with Dieter Gruen. I’m going to ask him to please say his name and spell it.

Dieter Gruen: I am Dieter Martin Gruen. D-I-E-T-E-R, M-A-R-T-I-N, G-R-U-E-N.

Kelly: Very good. Anyway, this is an interview about your life but with a focus on the Manhattan Project Experience. In that spirit can you tell us when and where you were born?

Gruen: I was born on November 21, 1922 in Walldorf, Germany.

Kelly: Where is Walldorf?

Gruen: Walldorf is a small village near the town of Meiningen and Thuringia, which is near the better-known town of Weimar. It is just south of Weimer.

Kelly: What was your childhood like?

Gruen: My childhood was very, very pleasant. My father was principle of the school. My mother and father had a devoted marriage. I had one brother older than I. I grew up in that village. I went to primary school there and did all of the things that small children, little boys, do, including using a roller skater on a steep hill and scaring my mother out of her skull with my daring.

Kelly: It was mountainous, and you were roller skating on a steep hill?

Gruen: No, no. This was a hill in the village. On the top of the hill there was an old medieval church. The countryside is hilly, not mountainous, but a very beautiful region where my family and I did a good deal of hiking on the weekends. It’s a very, very pleasant countryside, rural at that time.

Kelly: How did you happen to end up in the United States in the Manhattan Project?

Gruen: Well, you ask a very interesting question. The short answer is that I was no longer able to go to school because the Hitlerjugend would beat me up after school, and so it became clear that if I wanted to survive, I would have to leave. Fortunately I had relatives in Little Rock, Arkansas who took me into their home.

There’s an interesting sideline connected with that. My uncle was a personal friend of Senator Joseph Taylor Robinson who was the Majority Leader of the Senate during the first Roosevelt and helped to pass, for example, the Glass-Steagall Act and many other important pieces of legislation. My uncle had approached him on my behalf, and he wrote a letter to the American ambassador in Berlin. When I arrived there in the summer of 1937 to pick up my visa, they rolled out the red carpet for me. I was a fourteen-year-old unimportant person.

I came to this country, went to high school in Little Rock, and then my parents were also able to get a visa and left early 1939, just before war was declared in Europe. We reunited in Chicago, and so I’ve been a Chicagoan every since.

How did I get on the Manhattan Project? I began via student at Northwestern University in 1941, just before Berlin. It was the policy of the United States government, enunciated by President Franklin Delano Roosevelt, to recognize that this war would depend on America’s industrial might and would require the best scientific and engineering talent that would be available. [It] encouraged students who were within a couple of years of graduation to continue their studies. I was able to continue studying science—chemistry and physics—and received the baccalaureate degree cum laude in 1944. I was supposed to go to work at the Metallurgical Laboratories at the University of Chicago, which was part of the Manhattan Project, but in 1944 the “Met Labs” as they were called had already achieved their primary objectives. The first one, under the leadership of Enrico Fermi, was to build the first self-sustaining chain reaction, and that was done in 1942.

The second objective was to develop a separations process for the separation of plutonium that had been discovered in 1940 by Glenn Seaborg at Berkeley—to develop a separations process that could be scaled out to be used at Hanford for a kilogram quantity separation of plutonium. That too had been accomplished by about 1943. When I had finished my studies, the Met Labs were not in need of manpower any more, so I was asked to go to Oak Ridge to work on the uranium project. I got on a train and went from Chicago to Knoxville and then took a bus to Oak Ridge in September of 1944. That’s how I got on the Manhattan project.

Kelly: Wow! Did any of your colleagues also get swept up in the Manhattan Project, or were you just singled out among your classmates to go?

Gruen: At Northwestern, as far as I know, I was the only one to go on the Manhattan Project. My mentor, Professor Irving Klotz, was a consultant to the Manhattan Project, but he did important war work on biological materials at Northwestern. As far as I know, I’m the only one who actually went to work on the Manhattan Project from Northwestern.

Kelly: Do you remember what they told you were going to be working on? It was top secret. How did they recruit you?

Gruen: Well, when I got to Oak Ridge, I said that I wanted to be in the research division rather than in the engineering aspects of the work. I was assigned to work with a man who later actually became director of the Oak Ridge National Laboratory, but when I worked for him, he was director of the chemistry part of the research program at Oak Ridge. I went into his office, and he went to a safe. He opened the safe and pulled out a handbook of Physics and Chemistry. He opened it up to a table of the elements and pointed to uranium, and he said, this is what we’re working on.

Well, uranium had a codename, which had been invented by the British. It was called “tube alloy” because the uranium that was produced in Great Britain was produced by the Tube Alloy Company. We were not allowed to use uranium in our conversation about the work we were doing. It was “tube alloy”. I have reports that I wrote in those days with “tube alloy” in the title. That’s what I was working on.

Kelly: What was your boss’s name?

Gruen: I can’t bring it up at the moment. It’ll occur to me.

Kelly: Eugene Wigner?

Gruen: No, no, no. Not Eugene Wigner.

Kelly: Did you know him there?

Gruen: I did not know Wigner. No, I didn’t know him.

Kelly: He [Wigner] had a laboratory, but it was at the Y-12 campus.

Gruen: I was at the Y-12 campus.

Kelly: You were at the Y-12?

Gruen: Yeah, but Eugene Wigner was a theorist of it. He was a famous mathematician. I met him many years later actually on a visit to Israel. It turned out that he and I were both visiting Beersheba University and we were staying at the same hotel. We knew each other just very, very casually. That was my only contact with Eugene Wigner.

Kelly: So you worked in Y-12—in what aspects of the research were you involved in? The chemistry?

Gruen: In the chemistry parts of the project—in several different areas of the chemical aspect of that project. For example, the ion beams and the calutrons of uranium ions began as uranium tetrachloride. We developed processes for the syntheses of large quantities of very pure uranium tetrachloride. These were encapsulated and heated, and then the vapor of uranium tetrachloride was ionized by anagetic electron and particle beams to make uranium ion beams that were then separated into uranium-235 and uranium-238.

Then it became another chemical project to separate the uranium from the graphite collectors. At the ends of the spectrometers there were collectors made of graphite to which the uranium ions were injected. About the only way you could recover the uranium, was to burn the graphite in oxygen, and then you’re left with uranium oxide. One of the tasks that I was given was to synthesize an indicator, a colored dye, that would be stable in very concentrated nitric acid. The reason for this is that in the final stages of separation, uranium oxide was dissolved or uranium peroxide was dissolved in nitric acid, and then the uranium nitrate was extracted into an organic solvent. One had to determine in these columns the interface between the aqueous phase and the organic phase. I succeeded and produced an entirely new material: sulfonated copper phthalocyanine, which is a very brilliantly blue-colored material. One microgram was sufficient to cover a liter of solution, and it was perfectly stable in nitric acid solution.

I did a number of different projects. Most people don’t think about chemical problems related to the separation of uranium isotopes in calutrons. It’s a physical thing, but it turns out there were a number of chemical problems that had to be worked out. When I got to a bridge in September of 1944, the place was in uproar because the calutron magnets had burned out. There was a short developed in the magnets, and they had to be shipped back to Allis-Chalmers [Manufacturing Company] and so the production was delayed. When I arrived those magnets were back and the calutrons had been reassembled for the Alpha and the Beta process.

We made kilogram quantities of uranium-235 between September of 1944 and about April or May of 1945. This was shipped to Los Alamos, found itself into what became the Hiroshima bomb, [which] was a uranium bomb and had never been tested. In fact Hiroshima was the test for that first atomic bomb. The Nagasaki bomb was a plutonium bomb, which had been tested in Alamogordo, but the uranium bomb had never been tested. That was the end result of our labors.

Kelly: It’s interesting that you mentioned the chemistry as an important part of this whole process of extracting U-235, but the Smyth Report that was written at the end of the war doesn’t talk about chemists or chemistry. It was still classified.

Gruen: It was still classified, the chemistry part?

Kelly: Yes, so you guys were heroes but you didn’t get the credit. All of the credit goes to the physicists because that’s what they could talk about, but the chemists have for years been kind of unsung heroes here.

Gruen: Well, these reports that I wrote were declassified. I was able to get them many years later from Oak Ridge and if you were interested, I could make those available to you. There was some chemistry involved in doing all of this. That’s one of the untold parts of the story.

Kelly: Tell me a little bit more about your inventions. You talked about inventing this dye, a very unique dye. We’re you told by a supervisor to figure out some dye that will work, and then you figured that out by yourself? How did that happen?

Gruen: Well, My group leader said that we need such a thing. I went by bus from Oak Ridge to Knoxville several times, to the University of Knoxville library. As an undergraduate, I had synthesized copper phthalocyanine in an organic chemistry lab. That’s one of the experiments that we had done in a chemistry lab, an organic chemistry lab.

I had the idea if one could attach certain hydrophilic groups to this molecule, it should be possible to make it water-soluble. There were hints in the literature that this could be done using fuming sulfuric acid and so on. I went into the lab and tried it, and it worked, so that was how it came to be. I did it on my own without guidance. This was a good thing. It was used at Oak Ridge. The people who had this problem were pretty happy with the result.

Kelly: Why don’t you explain again what different it made in the process?

Gruen: If you have two liquids in touch with each other and they’re colorless liquids, you can’t tell where one ends and the other begins. So if I put a dye in one of the liquids then it’s very clear where the interface is. If you were extracting something from one liquid into the other liquid, you want to know where the separation occurs so that you can make the actual separation. That’s just a visual sensor of the interface of the two liquids.

Kelly: One of the things that the National Park Service wants to do in interpreting the Manhattan Project is to mine it for all of the science and technology lessons. This would be a good example for students to try to understand—high-school chemistry students or college chemistry students.

Gruen: That’s a good idea because there are lots of things that were developed there that have been lost. This happens in all technology and things around that are rediscovered years later very laboriously when it’s already been done.

Kelly: Did you get the sense that there was a lot of innovation going on in the Manhattan project?

Gruen: Oh, the whole thing was innovation. The calutrons had been invented by Ernest Orlando Lawrence who then got the Nobel Prize for inventing the cyclotron. He was one of the great scientists. Glen Seaborg, whom I got to know later and became very good friends with, was one of the great scientists. He influenced my life in a very profound way. These were great men, yes. They had lots of innovation; they were an amazing generation of scientists!

Kelly: It didn’t take just a Nobel Prize winner; it was young people like yourself. How did they empower you to be innovators?

Gruen: Well, in my experience, I’m just talking very subjectively, that kind of empowerment comes from the individual largely. You either have it, or you don’t. You can’t make somebody do something new. A scientist is a man or a women who does or says something new. Not everyone can do that. You can encourage people to work and to study, but to get real innovation, it’s a good question. I don’t know how to answer it really.

Kelly: Well, the Manhattan certainly was a crucible for innovation. [It yielded] something like 6,500 patents that were patented in secret. That probably understates how many new gadgets and approaches [were created].

Gruen: Only 6,000? [Laughter]

Kelly: Yeah, 6,000 it seems like—of course this was all in less than three years.

Gruen: Well, it’s a new field of course. It was a totally new field, and it released a tremendous scientific effort and scientific creativity. If you have an environment in which you tell people there’s a certain goal we want to achieve, we’ll give you the resources to do it and the manpower. Then you can get a lot accomplished, particularly if you don’t insist that every experiment has to be written according to a certain safety standard, every chemical has to be indexed, and you need material science safety datasheets.

I’m all in favor of safety. I’ve never had a laboratory accident. The emphasis that is put on safety today, I think exceeds what is required to do laboratory. It’s gotten to the point where it inhibits laboratory work I think. It’s just my opinion. I’m not advocating unsafe practices by any means. I’ve always been conscious of safety, but I think today that aspect is a little overdone. If we had had to do that in those days, we couldn’t have achieved what we did in a short period of time.

Kelly: How much did you know about what was going on in the Y-12 Plant? Did you know that u-235 was going to be used for the atomic bomb? How much did you understand?

Gruen: I knew that it was going to be used for an atomic bomb, but the work that was done at Los Alamos, I knew nothing about. I knew nothing about bomb design or any of the problems associated with nuclear weapons. We knew what we had to do to make kilogram quantities of uranium-235, and that was about the extent of our knowledge about the project. We certainly didn’t have an overall grasp of what was going on.

Kelly: Did someone explain and say, here’s what the end goal is, or did you just figure that our on your own?

Gruen: [We] figured it out on our own; no one told us. No one. It was just in conversations with colleagues and on long hikes through the Smokies wondering what we were doing and why we were doing it. We had to come to certain conclusions, but on our own. There was no discussion from management about what was going on.

Kelly: What did you think at the time? Had you a sense for how explosive or destructive this weapon would be? Did you ever question whether this was the right thing to do?

Gruen: Before the bomb was dropped?

Kelly: Yeah.

Gruen: No. That’s the short answer. I did not think about it, and none of my colleagues, at least none with whom I spoke, talked about it. The atmosphere at Oak Ridge was we were under pressure to get something done. My personal feeling was that we have to win the war for obvious reason, but the consequences of what we were doing was something I thought about only after the bomb was dropped, and then I became very involved in that.

Kelly: You did become after the war?

Gruen: After the war, yeah.

Kelly: Do you want to talk about that?

Gruen: Yes. After the Hiroshima and Nagasaki bombs were dropped and the war was over, it’s very hard to reconstruct the feeling that existed in this country about atomic work. People talked about atoms as if that was something totally new and totally unexpected and mysterious and secret. You talked to a person on the street about atoms, and they were all a thither. It’s very hard to reconstruct the intense feeling people had from one day to the next about atoms and atomic science.

One of the messages that we had was that there are no secrets about atoms and that there’s no defense against atomic weapons. So we started an organization called The Oak Ridge Engineers and Scientists. We wanted to create public awareness of what urgency there is in preventing anything like this from happening again. Together with two colleagues John Balderstone and David Waymire, I sent a letter to more than 100 of the outstanding personalities of the time, people who had been involved in the bomb project, like James Brian Conant and others, and to the scientists, including Albert Einstein. In that letter we raised the question, “What would have to be done to prevent nuclear weapons from being used in war?”

We received replies to almost every letter that we had sent out, very thoughtful replies. There was one from Albert Einstein in which he said the only solution would be a world government. I’m still waiting for that [laughter], but one of the things that I did was follow the hearings that were taking place on Capitol Hill on the McMahon Act that advocated civilian control and the May Act that advocated military control. I don’t know how this happened, but at the conclusion to every day’s hearings on these bills, we got the transcripts of those hearings. I stayed up for hours condensing these into a newspaper article.

The following day I would drive to Knoxville and deliver it to the Knoxville Journal, and they printed it the following day. They had summaries of these hearings. I think the McMahon Bill actually established the national labs. I think they nationally were established as a result of the passage of the McMahon Act. In a way, my entire life has been involved with work on Argonne National Laboratory. The Manhattan Project was a really very formative experience for me. It led to the place where I did all of the work that I continued for so many years.

Kelly: When the war was over, you went from Oak Ridge back to Chicago? Argonne National Laboratory was formed as a result of the McMahon Act, which would have been ’48?

Gruen: Argonne was established in April of 1946. I went back to Chicago from Oak Ridge. I left Oak Ridge in April of ’46, and I went back to Northwestern to start graduate work with my former mentor. I was doing that when I was approached to join Argonne, but I wanted to finish what I had started. I got a master’s degree from Northwestern, and went to work at Argonne.

While I was working at Argonne, it was also possible for me to continue graduate work at the University of Chicago. I did my dissertation on the magnetic susceptibilities of neptunium compounds—that’s element ninety-three. I got to know Glenn Seaborg at that time. He made frequent visits to Argonne and was very interested in my work because I was able to show in very great detail that Seaborg’s Actinide Hypothesis was the correct picture for the electronic structure of the actinides. That was a very fruitful period.

I worked at Argonne on chemical problems associated with the building of a nuclear submarine. Argonne became the national center for the development of nuclear power reactors for peaceful uses of atomic energy. The first power reactor was Rickover’s [Admiral Hyman Rickover] Nuclear Submarine Reactor. There was a very, very important chemical problem that had to be solved for that reactor to work. That was one of the first things I did.

Kelly: What was that problem?

Gruen: That problem had to do with the zirconium cladding of the uranium fuel elements for the submarine reactor. The zirconium, when it is mined, always contains ten or fifteen percent of hafnium. Hafnium had been found to have a very high neutron capture cross section. So in order for zirconium to be used as a cladding, hafnium had to be removed. I developed the process, and it was actually put into pilot plan—there was a pilot plan constructed remove hafnium from zirconium by foot mineral.

Then zirconium, very resistant to corrosion, was and still is a very useful cladding material for uranium. All of the zirconium that is used does not contain any hafnium. There had to be chemical process to remove that, which is chemically very similar to zirconium, so it’s not an easy thing.

Kelly: They say that one of the problems of the German effort to make an atomic bomb was that the physicists didn’t consult with the chemists about the impurities in the graphite.

Gruen: The Germans did not realize that all graphite contains boron, and yes, you’re absolutely right! Fermi [Enrico] and Szilard [Leo] did recognize that, and so they were able to get the manufacturers of the graphite used in Chicago to be boron free. There’s a story that when the truck arrived with the graphite blocks to build the reactor, Fermi himself unloaded them. He knew how precious they were.

Kelly: They’re pretty heavy too.

Gruen: The blocks?

Kelly: Yes. I thought they got the football team or some such thing involved.

Gruen: The football team?

Kelly: Yeah, in setting up the lattice.

Gruen: Well Cindy, are you sure it was the football team?

Kelly: I’m not sure because maybe they’d banned football at that time.

Gruen: Yeah. Football was banned, and that’s why it was built under the west stands of the football stadium because they weren’t using it for football games.

Kelly: Right. I think it was at Columbia [University]; they had built some graphite stuff there.

Gruen: Yeah, there are lots of stories around.

Kelly: Yes. There are.

Gruen: There was a very famous lady involved in the early work. She was a very close associate of Enrico Fermi and Leona Woods. When I was a graduate student of the University of Chicago, Leona Woods and Enrico Fermi came walking into our lab one time because my mentor there was using a new technique of spin resonance spectroscopy. Fermi wanted to know how it worked, so he looked around for about five minutes, and said, “Oh, I see. I see how that works.”

Kelly: That was a quick study! I didn’t realize that they were together after the war as well, that is, Fermi and Leona Woods.

Gruen: Leona, yeah. Fermi unfortunately, of course, passed away in 1954 of cancer. When I was a student there starting in 1947 and 1948, our apartment was on 53rd Street and University Avenue. Fermi would ride his bike past our apartment every morning at eight o’clock. I would look out my window and see him, and know it was time to get up and go and listen to his lecture. He was a professor at the university after the war until he died.

Kelly: Was he a good professor?

Gruen: Oh, he was the most marvelous teacher. I mean. I’d listen to his lecture, and understood everything he said until I left the room. Great lecturer and a great teacher. He would have lunch with his undergraduates every day in the commons. You’d see him there talking to students.

Kelly: He certainly encouraged Leona. I think it wasn’t so common to have women scientists. He took her into his confidence, and she was his right-hand man.

Gruen: She was. She was very close to him. Well, those were great days at the University of Chicago. You had Edward Teller as a professor and Harold Urey and Willard Libby. Leona finally married Willard Libby.

Kelly: What was Teller like?

Gruen: I didn’t know him personally. He lived very close to where we were. I used to see him, but I didn’t know him personally. I don’t really know very much about his personality except what I found out from other people who did know him.

Kelly: Did you ever meet Szilard?

Gruen: I have met Szilard, yeah. I have met him, but again, I didn’t really know him. I knew Urey quite well. He was actually my graduate advisor at the University, Harold Urey and Libby I knew.

Kelly: Well, you were in good hands as a student.

Gruen: The best. I was very fortunate.

Kelly: We talked about your work at Oak Ridge. You mentioned on the side, hiking and the Great Smokies. Can you tell us a little more about your life in Oak Ridge and what it was like in those days?

Gruen: I lived in a dormitory with construction workers of K-25. K-25 had not been completed—it was just being built when I arrived there. That was quite an experience.

Kelly: Where was this dormitory?

Gruen: West Village 54, I think it was called. It was sort of on the outskirts of “town”. We had a very interesting group of young scientists. Several of us sort of became addicted to the Smokies. We would go whenever we had a chance. The park was dedicated by President Roosevelt in 1937 I believe.

We were there just a few years later when it was not the tourist attraction that it is now, but there was a place called Cades Cove, which was a valley surrounded by hills that housed a community of early English settlers. They still sort of spoke Elizabethan speech. They had been isolated for 100 years. They were a functioning community with a church and school and a mill, and they had not been evicted even though that was part of the Great Smoky Mountain National Park. They were still there sort of at the tail end. It was a fascinating experience, and on these hikes we talked about every subject under the sun. It was a very, as I said before, a very formative period in many ways.

Kelly: Now, were you single during this time?

Gruen: Yes, I was single.

Kelly: How were the numbers in terms of single women and single men? Was that in your favor? There were a lot of women, weren’t there?

Gruen: Well, many of the people there were married fortunately. They invited me over for dinner and that was good. Food was horrible. There was nothing to drink. Oak Ridge was dry, and you had to go to Corbin, Kentucky to get some liquor.

The number of uncommitted ladies was not that large. The calutrons were manned by women. These were mostly high-school girls, totally untrained. They manned the control panels, and they did a good job. Even though they were uneducated, they were very faithful workers.

Kelly: So you had fun on the weekends. Did you work hard during the week?

Gruen: Yeah.

Kelly: Were there shifts or did you have a normal—

Gruen: Well, in what I was doing, the research part of the lab, we had just normal eight to five hours. We didn’t burn the midnight oil; it was not that kind of environment. We worked during the day and we had free time in the evening and on the weekends, so it was a normal kind of work environment. It was intense but not frenetic.

Kelly: When did you meet your wife?

Gruen: I met my wife in the fall of 1947. We were both graduate students at the University of Chicago. She was in psychology, I was in science, and that’s how we met.

Kelly: You were then employed by Argonne National Laboratory. What did she do?

Gruen: After she got her degree, she became Director of Psychological Services in our school system in a suburb of Chicago. She had a career there, and then later she went into private practice. She was at private practice for about twenty years. 

My work at Argonne was strongly influenced by my experiences on the Manhattan Project. On reflecting back on what I did during most of my life, I would have to say that my scientific work had its origins in the realization that nuclear power was something really new and important, that there were two sides to it: one destructive and the other constructive, and that that power could be used as a non-polluting alternative source energy. So for the rest of my scientific life, I devoted myself to the solution of this very daunting and challenging problem of how to create a sustainable, non-polluting global energy source.

Over the years, that has become a very, very important and a very, very pressing problem because we are now in a situation where our polluting the planet with greenhouse gasses could lead to making the planet uninhabitable. It is absolutely essential if we are to continue living a civilized life that requires a lot of energy, and there are seven billion of us now, that we do whatever we can as quickly as possible to find the new energy source.

I spent many, many years studying nuclear fission power reactors. I was a U.S. delegate at the Second International Conference on Peaceful Uses of Atomic Energy. It took place in Geneva, Switzerland. I have maintained that interest all of my life and later on began to be interested in problems associated with practical use of fusion energy and did a lot of fundamental work associated with problems that are encountered when you try to operate plasma machines like Torquemax. It became clear as the years went on and worldwide efforts were mounted both for fission reactors and fusion reactors that to find such an alternative source is maybe the most challenge task that faces science of technology today, extremely challenging.

I have finally come to the conclusion that because of the problems that are encountered with fission reactors—Chernobyl, Three Mile Island, Fukushima—problems associated not only with operating these machines, but also with storing of these vast amounts of radioactivity long-lived products—there has been no nuclear reactor built in this country in forty years. You have to ask yourself why that is.

Fusion reactors have been under serious development for over fifty years now. None have achieved breakeven condition. “Breakeven” means that you get as much energy out as you put in, that is, to get a self-sustaining plasma that gives you back as much energy as you put into make the plasma. That has not yet been achieved in any of these machines. That’s only the beginning. It is not clear, at least it’s not clear to me, that fusion power reactors can be built.

Basically what you’re trying to do is to produce conditions that exist in the sun here on earth. I have come to the conclusion that we do have alternative energy source available to us, and that is the sun. It has been there forever. It has given us life. It nourishes us today. It has produced all of the fossil fuels that we’re now burning up very, very quickly. It took a hundred or million years to produce them, and we’re burning it up in a couple of hundred years. The sun has been around, the sun will be around, and we have to learn how to use it more efficiently in order for solar power to be able to compete with fossil fuel or nuclear power.

In my opinion, the large-scale use of solar power depends on making it cheaper, making it economically competitive with the conventional, let’s say, coal-fired power plants. I’m spending my retirement years developing a new approach to using solar power more efficiently. [My goal is to] to make it twice as efficient—to make the conversion of light to electricity twice as efficient as it is now, to double the power from sunshine. That is what I am working on. If I trace the connections of those interests back, then I end up with a Manhattan Project. I think there is a direct connection between what I’m doing now and what I did all of those many years ago. That’s kind of amusing.

Kelly: That’s a great story. I hope you succeed.

Gruen: Yes. I hope so too. Well, I mean. It’s a difficult situation for someone in my position. There is such competition for funding these days to get something done. To set up experiments and to follow these ideas at my age is not an easy task.

Kelly: You have to have some young graduate students who can work with you.

Gruen: Well, I [would] have no problem finding graduate students, postdoctoral students, faculty members, or even people at a national laboratory to work on this problem if I could pay them. They’d be glad to work on it, but first they have to support their families before they can do this.

Kelly: That’s true.

Gruen: I find that that is something that has changed in a fundamental way. It’s my perception that today people are focused on short-term gain. It used to be much easier to get funding. I have a feeling from what you said earlier that it’s not so easy to get funding for what you’re involved in either. Getting people excited about a project [where] they don’t see an immediate financial gain is a difficult thing. It used to be easier I think. At least there was a period after World War II when science was being supported at a much higher level than it is today.

I’m concerned that this country, by not focusing more on basic scientific research, will going to fall behind. I hope I’m wrong, but I don’t know. Vannevar Bush used to say, “Science: the endless frontier.” I think he was right, and it’s not going to stop. If we don’t push the envelope in this country, there are other people who are going to do it, and they will develop the technologies of the future. I think that’s the inevitable result of the lack of concern in funding science. I don’t know how to change that. 

People like me [Manhattan Project veterans], you say there are others, are in a unique position to contribute to a national debate about these issues because we span a large fraction of what one might call the modern scientific and technological age. Much of what has happened theoretically, from quantum physics to cosmology to material science to nanoscience, has happened in the last seventy years. When you have the kind of perspective that you can get when you’ve lived through it and been active in it all of these years, you may be able to contribute something, but that resource is not being tapped.

There is nobody who has ever asked me for an opinion about these matters. I don’t know how you view that from your perspective. The fact that you have to persuade people to support the project that you’re involved in [shows] they don’t immediately recognize this as a very important period in this country’s history, a defining period. [It is important] to increase public awareness of where we are now compared to where we were then [in order] to gain some insight and wisdom from the way things have developed.

People hold in their palms more computing power than existed for the astronauts on the moon. They don’t even think about the fact that when they use the Smartphone, they have to recharge it every night. You just plug it into the wall, but suppose the wall didn’t recharge the battery. They don’t make the connection between the energy you’re using when you use a cell phone and the enormous amounts of power that are required to do the computing that’s done in the world today. People talk lively about the electric automobile. If we had 100 million electric automobiles in this country, and you plugged them all in at the same time, you’d blow the national fuse. They’re non-polluting, and you don’t make the connection to the power that is required on it to run these automobiles. There’s been an information-technology revolution. What we need now, I think, is an energy-technology revolution. We have to think about how to bring that about.

Kelly: That’s right.

Gruen: Your friends at the Department of Energy, I’m sure they want to do something, but they don’t have the wherewithal. They keep cutting back on the budgets at the Department of Energy. That’s my message for today.

Scientific research is basically not being funded anymore because of the industrial research labs. I read just the other day that General Electric has put $30 million into a company called Quirky. Quirky takes inventors’ ideas and selects them very carefully and translates them into products. What I takeaway, General Electric is supporting a company that commercializes inventions that they should be making in their own labs.

They must find it economically advantageous to outsource innovation and commercialization of innovation rather than doing it in house. That’s what’s happened in industrial research. Many companies that had research labs in the Fifties and Sixties have closed them down. They’re not supporting basic research anymore. I used to be on the editorial boards of the Journal of Applied Physics and Applied Physics Letters. They still invite me to the lunches. The number of scientific manuscripts coming out of China to these journalists, American journalists, is larger than the number of papers submitted by U.S. authors.

Kelly: By what?

Gruen: Chinese papers are submitted in larger numbers than U.S. papers to U.S. journalism. 

Gruen: I was in the heyday of science. I feel very fortunate to have experienced that, but I wish other people could have too. That’s just the way it is. We need another Manhattan Project. I kid you not. We could do it. If we had another Manhattan Project for solar power, we could do it. I have no doubt we could make solar power economical compatible in two or three years, 

Kelly: Are you concerned that there’s so much information in the public domain about how the bomb was built and the ingredients for the bombs produced back during the Manhattan Project that other countries can now use that information to build bombs?

Gruen: Well, the technology that Iran is using, centrifuges, was just in its infancy during the Manhattan Project. It was just a very small effort. That technology has come along to such an extent that it’s now the way of making uranium-235. I doubt if there’s anything in the Manhattan Project secret literature that would have any bearing on that centrifuge technology, but I don’t know. It could be, but I doubt it. They’re going to get a nuclear weapon, that’s for sure. If they don’t already have it.

Kelly: How do you feel about the use of the atomic bomb on Japan?

Gruen: There’s a story that J. Robert Oppenheimer walked into Truman’s office and said to him, “Mr. President, I have blood on my hands.” That’s the last time Truman ever spoke to him. What choice did the Commander in Chief have at that moment in history except to authorize dropping the atomic bomb? He didn’t have a choice. As gruesome as it was, and as horrified as I and my colleagues were at that time, I feel today that it was the correct decision. It brought an end to the most horrible war. It saved millions of lives, American soldiers and Japanese soldiers

Do I feel a personal responsibility? Of course. I took part in that, but was it the correct decision? I think so. I’ve talked to quite a few men who were fighting in Europe. At the end of the European war they were loaded on boats, sent to New York, and shipped to San Francisco, and they were on their way to Japan, to the invasion of Japan. When the bombs were dropped, they were very happy they didn’t have to fight in the Pacific. I know several guys who were in that position, but we must not let it happen again. If Iran gets the bomb and drops it on Israel that will be World War III, and that’ll be the end of all of us. That’s my feeling.

Kelly: If the Manhattan Project hadn’t succeeded in producing the bomb, how long do you suppose it would have been until somebody else would have figured it out?

Gruen: Well, the fear of course was that Germany would get the bomb first because fission had been discovered at the Kaiser Wilhelm Institute in 1938. Everybody thought that if anybody gets the bomb, it would be Germany. The fact that you now have almost a dozen nations that have nuclear weapons shows that if a technology is possible and has been demonstrated, it will be replicated. There’s no way of stopping it.

If the United States had not done it, instead of five years, it would have taken ten or fifteen years, but by now we would have a nuclear armed world, even without the Manhattan Project. Don’t you think so? A nuclear weapon is no harder to make than a Smartphone. I’ve been out to the Intel Plant. I’ve seen how they make chips. That’s a pretty sophisticated operation. That’s at least as sophisticated as making an atomic bomb.

Kelly: What should the next generation do to prevent Iran or prevent other people from getting and using this technology?

Gruen: That’s a good question. We asked that question, as I told you in 1945. Albert Einstein told us that we need a world government. Well, we have got the genie out of the bottle, and we can’t put it back.

Kelly: To what do you credit the fact that we haven’t had an Armageddon in the last seventy years?

Gruen: Well, we’ve not had any leader crazy enough to pull the trigger. You’d have to be insane to do it. I shutter to think what would happen if terrorists got a hold of it.

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