The Manhattan Project

by Cynthia C. Kelly

  In June, 1942, when the Corps of Engineers came into the picture, the necessary research on plutonium production and recovery had scarcely begun. There was no experimental proof that the hoped-for conversion would actually occur; it was predicated entirely on theoretical reasoning. Not until December 2, 1942, did we have any such proof, and this was weeks after we had decided to go ahead at full speed on the plutonium process, and many days after we had started to prepare the plans for a major plant. On October 5, 1942, I paid my first visit to the Metallurgical Laboratory at the University of Chicago, where Arthur Compton and I spent the morning inspecting the laboratory facilities and discussing with a number of scientists the work on which they were engaged.

  That afternoon I had a meeting with Compton and about fifteen of his senior men. Among them were two other Nobel Prize winners, Enrico Fermi and James Franck, together with the brilliant Hungarian physicists Eugene Wigner and Leo Szilard, and Dr. Norman Hilberry, Compton’s assistant. The purpose of the meeting was to give me an idea of the extent of their knowledge about the plutonium process, and the anticipated explosive power of an atomic bomb, as well as of the amount of fissionable material that a single bomb would require. Of particular importance to me was an understanding of the gaps in knowledge that remained to be filled. I wanted to be sure also that everyone recognized the intermediate goals that had to be achieved before we would attain ultimate success, and that I, too, had a clear understanding of these goals. I was vitally interested in just how much plutonium or how much U-235 would be needed for a reasonably effective bomb. This was all-important, for it would determine the size of our production facilities, not only for plutonium, but also for Uranium-235.

  Compton’s group discussed the problem with me thoroughly, backing up their postulations mathematically and eventually arriving at the answers I needed. In general, our discussion was quite matter-of-fact, although much of it was highly theoretical and based on completely unproven, but quite plausible, hypotheses on which all the other participants seemed to be in complete agreement.

  As the meeting was drawing to a close, I asked the question that is always uppermost in the mind of an engineer: With respect to the amount of fissionable material needed for each bomb, how accurate did they think their estimate was? I expected a reply of “within twenty five or fifty per cent,” and would not have been greatly surprised at an even greater percentage, but I was horrified when they quite blandly replied that they thought it was correct within a factor of ten.

  This meant, for example, that if they estimated that we would need one hundred pounds of plutonium for a bomb, the correct amount could be anywhere from ten to one thousand pounds. Most important of all, it completely destroyed any thought of reasonable planning for the production plants for fissionable materials. My position could well be compared with that of a caterer who is told he must be prepared to serve anywhere between ten and a thousand guests. But after extensive discussion of this point, I concluded that it simply was not possible then to arrive at a more precise answer.

  While I had known that we were proceeding in the dark, this conversation brought it home to me with the impact of a pile driver. There was simply no ready solution to the problem that we faced, except to hope that the factor of error would prove to be not quite so fantastic. This uncertainty surrounding the amount of material needed for a bomb plagued us continuously until shortly before the explosion of the Alamogordo test bomb on July 16, 1945. Even after that we could not be sure that Uranium-235 (used in the Hiroshima bomb) would have the same characteristics as plutonium (used in the test and later against Nagasaki), although we knew of no reason why it should be greatly different.

  BETHE BECOMES A BELIEVER

  Around 1940, I was very doubtful about making an atomic weapon. I thought it couldn’t possibly work and that trying to make one was a waste of time. My mind was changed in 1942 when I saw Enrico Fermi’s work at Chicago, his success in obtaining a chain reaction and plan to use the chain reaction to make plutonium. And so from that moment on I was fairly confident that one way or another, a weapon would be made.

  —HANS BETHE

  “Swimming in syrup”

  As Robert Jungk explains, the path to success in the Manhattan Project was not a smooth, straight road but a “labyrinth of winding streets and blind alleys.” The scientists’ determination, initiative, and obstinacy were critical to overcoming both bureaucratic and technical hurdles.

  From Brighter than a Thousand Suns

  BY ROBERT JUNGK

  The success of American atomic research during the war, which astonished the world, colored later descriptions of the subject. What was seen in retrospect as a difficult but straight road leading to its goal was really a labyrinth of winding streets and blind alleys.

  [Edward] Teller criticizes as follows one of these excessively rosy views of the early history of the American atom bomb: “There is no mention of the futile efforts of the scientists in 1939 to awaken the interest of the military authorities in the atomic bomb. The reader does not learn about the dismay of scientists faced with the necessity of planned research. He does not find out about the indignation of engineers asked to believe in the theory and on such an airy basis to construct a plant.”

  Wigner remembers the resistance. “We often felt as though we were swimming in syrup,” he remarks. Boris Pregel, a radium expert, without whose disinterested loan of uranium the first experiments at Columbia University would have been impossible, comments: “It is a wonder that after so many blunders and mistakes anything was ever accomplished at all.” [Leo] Szilard still believes today that work on the uranium project was delayed for at least a year by the shortsightedness and sluggishness of the authorities. Even Roosevelt’s manifest interest in the plan scarcely accelerated its execution. [Alexander] Sachs knew his way pretty well about the jungle of bureaucratic intrigue. At first he succeeded in preventing the Army or Navy from monopolizing the project. He proposed that [Lyman] Briggs, the director of the National Bureau of Standards, should be put in supreme control of the plan. But Briggs, though able enough, was a sick man, due at the time to undergo a serious operation. He could not take such energetic action as might be necessary. It seemed for a while as though both he and the entire “Project S-I,” as it was provisionally called, would take leave of their precarious lives simultaneously. But Briggs recovered and S-I, too.

  The countless administrative and technical obstacles which blocked the road to the release of atomic energy were finally overcome simply and solely by the determination and obstinacy of the scientists resident in the Anglo-Saxon countries. They did much more than obey orders. They repeatedly took the initiative in bringing that mighty weapon into the world. Their initiative was perhaps the most important “raw material” used in the achievement of atomic power, but their enthusiasm, which surmounted every difficulty and was founded upon a passionate belief in the justice of the Allied cause, did not bring them much appreciation.

  Many scientists were inspired at that time by the honest conviction that this was the best, in fact the only, way to prevent employment of the atomic weapon during the current war. “We must have some countermeasure available to meet any possible threat of atomic warfare by Germany. If we only had such a thing both Hitler and ourselves would be obliged to renounce the use of such a monstrosity.” So said the few who were in on the secret.

  In 1942 the Allied atomic project entered an entirely new phase. Roosevelt and Churchill agreed to concentrate the work of the British and American research teams in Canada and the United States. In the United States supreme control of atomic research was transferred from the scientists to a Military Policy Committee consisting of three members of the Armed Forces: General [Wilhelm] Styer, Admiral [William] Purnell and General Leslie Groves, and only two professional investigators, Dr. Vannevar Bush and Dr. James Conant. After August 13, 1942, the whole plan became known under the code name of either the DSM (development of substitute materials) or the “Manhatt
an Project.” From then on the atomic experts were simply designated “scientific personnel” and obliged to submit to the strict rules of military secrecy.

  It was probably the first time in history that so brilliant a group of minds had voluntarily undertaken to adopt a mode of work and existence so unlike their normal way of life. They accepted as obvious the rule that they were to publish no more of their discoveries until after the war. They had themselves, after all, been the first to propose, even before the war, that secrecy should be maintained. But the military authorities went much further than this prohibition. They erected invisible walls round every branch of research, so that no department ever knew what any other was doing. Barely a dozen of the total number of some 150,000 persons eventually employed on the Manhattan Project were allowed an over-all view of the plan as a whole. In fact only a very small number of the staff knew that they were working on the production of an atom bomb at all.

  The Los Alamos Primer: How to Make an Atomic Bomb

  Nuclear physics was such a new field of study that many of the men and women working on the Manhattan Project had to learn it on the job. At the Los Alamos Laboratory, director J. Robert Oppenheimer asked Robert Serber to present a series of lectures to the employees there. As Serber explains, the lectures comprised “everything we knew in April 1943 on how to make an atomic bomb.”

  From The Los Alamos Primer

  BY ROBERT SERBER

  Report L.A. 1, the Los Alamos Primer, was the first technical document issued by the Los Alamos Laboratory after it opened for business in the spring of 1943. It’s a summary of five lectures I gave early in April to draw a starting line for the work we had moved to the mesa to do: to design and build the first atomic bombs.

  The theoretical physicist Ed Condon served as secretary during the Primer lectures. He took notes, and then the same afternoon or the next morning he’d write them up and bring them over and we’d discuss them back and forth, edit them a little.[…] Everyone had just arrived. Buildings were still under construction. All the apparatus was in crates. People were unpacking it and putting it together and working twelve to sixteen hours a day. Pulling them away from what they were doing and getting them together for a series of lectures wasn’t the easiest thing in the world. The time had to be cut to a minimum. That meant, in planning the lectures, that I had to cut explanations and decide what to leave out, to make a skeleton outline of the information. But within those limitations the Primer is essentially a summary of everything we knew in April 1943 about how to make an atomic bomb.

  By the end of March the army was getting some of the housing in order so that people could move in. We moved into a sort of duplex with the Wilsons on the other side. People were arriving. Oppy straightened things out with the army, making sure that they didn’t interfere with everything. There was a conference with a big crowd of outsiders. The scene was set for telling people in a little more detail what it was about. And that was where I—and the Primer—came in.

  “These were very great men indeed”

  Physicists were engaged in work that was vital to the Manhattan Project and were quickly recruited to join the effort. Richard Feynman relates how, as a doctoral student at Princeton, he joined the undertaking and records some of his early impressions of the “very great men” leading the project.

  From “Los Alamos from Below”

  BY RICHARD FEYNMAN

  I was working in my office one day, when Bob Wilson came in. I was working—[laughter] what the hell, I’ve got lots funnier yet; what are you laughing at?—Bob Wilson came in and said that he had been funded to do a job that was a secret and he wasn’t supposed to tell anybody, but he was going to tell me because he knew that as soon as I knew what he was going to do, I’d see that I had to go along with it.

  So he told me about the problem of separating different isotopes of uranium. He had to ultimately make a bomb, a process for separating the isotopes of uranium, which was different from the one which was ultimately used, and he wanted to try to develop it. He told me about it and he said there’s a meeting… I said I didn’t want to do it. He said all right, there’s a meeting at three o’clock, I’ll see you there. I said it’s all right you told me the secret because I’m not going to tell anybody, but I’m not going to do it. So I went back to work on my thesis, for about three minutes. Then I began to pace the floor and think about this thing.

  The Germans had Hitler and the possibility of developing an atomic bomb was obvious, and the possibility that they would develop it before we did was very much of a fright. So I decided to go to the meeting at three o’clock. By four o’clock I already had a desk in a room and was trying to calculate whether this particular method was limited by the total amount of current that you can get in an ion beam, and so on.

  I won’t go into the details. But I had a desk, and I had paper, and I’m working hard as I could and as fast as I can. The fellows who were building the apparatus planned to do the experiment right there. And it was like those moving pictures where you see a piece of equipment go bruuuup, bruuuup, bruuuup. Every time I’d look up the thing was getting bigger.

  And what was happening, of course, was that all the boys had decided to work on this and to stop their research in science. All the science stopped during the war except the little bit that was done in Los Alamos. It was not much science; it was a lot of engineering. And they were robbing their equipment from their research, and all the equipment from different research was being put together to make the new apparatus to do the experiment, to try to separate the isotopes of uranium.

  I stopped my work also for the same reason. It is true that I did take a six-week vacation after a while from that job and finished writing my thesis. So I did get my degree just before I got to Los Alamos, so I wasn’t quite as far down as I led you to believe.

  One of the first experiences that was very interesting to me in this project at Princeton was to meet great men. I had never met very many great men before. But there was an evaluation committee that had to decide which way we were going and to try to help us along, and to help us ultimately decide which way we were going to separate the uranium. This evaluation committee had men like [Richard] Tolman and [Henry DeWolf] Smyth and [Harold] Urey, [Isidor I.] Rabi and [J. Robert] Oppenheimer and so forth on it. And there was [Arthur] Compton, for example.

  One of the things I saw was a terrible shock. I would sit there because I understood the theory of the process of what we were doing, and so they’d ask me questions and then we’d discuss it. Then one man would make a point and then Compton, for example, would explain a different point of view, and he would be perfectly right, and it was the right idea, and he said it should be this way. Another guy would say well, maybe, there’s this possibility we have to consider against it. There’s another possibility we have to consider. I’m jumping! He should, Compton, he should say it again, he should say it again! So everyone is disagreeing, it went all the way around the table. So finally at the end Tolman, who’s the chairman, says, well, having heard all these arguments, I guess it’s true that Compton’s argument is the best of all and now we have to go ahead.

  And it was such a shock to me to see that a committee of men could present a whole lot of ideas, each one thinking of a new facet, and remembering what the other fellow said, having paid attention, and so that at the end the decision is made as to which idea is the best, summing it all together, without having to say it three times, you see? So that was a shock, and these were very great men indeed.

  This project was ultimately decided not to be the way that they were going to separate uranium. We were told then that we were going to stop and that there would be starting in Los Alamos, New Mexico, the project that would actually make the bomb and that we would all go out there to make it. There would be experiments that we would have to do, and theoretical work to do. I was in the theoretical work; all the rest of the fellows were in experimental work.

  The question then was what to do, b
ecause we had this hiatus of time since we’d just be told to turn off and Los Alamos wasn’t ready yet. Bob Wilson tried to make use of his time by sending me to Chicago to find out all that I could about the bomb and the problems so that we could start to build in our laboratories equipment, counters of various kinds, and so on that would be useful when we got to Los Alamos.

  So no time was wasted. I was sent to Chicago with the instructions to go to each group, tell them I was going to work with them, have them tell me about a problem to the extent that I knew enough detail so that I could actually sit down and start to work on the problem, and as soon as I got that far go to another guy and ask for a problem, and that way I would understand the details of everything. It was a very good idea, although my conscience bothered me a little bit. But it turned out accidentally (I was very lucky) that as one of the guys explained a problem I said why don’t you do it that way and in a half an hour he had it solved, and they’d been working on it for three months. So, I did something!

  When I came back from Chicago I described the situation—how much energy was released, what the bomb was going to be like and so forth to these fellows. I remember a friend of mine who worked with me, Paul Olum, a mathematician, came up to me afterwards and said, “When they make a moving picture about this, they’ll have the guy coming back from Chicago telling the Princeton men all about the bomb, and he’ll be dressed in a suit and carry a briefcase and so on—and you’re in dirty shirtsleeves and just telling us all about it.” But it’s a very serious thing anyway and so he appreciated the difference between the real world and that in the movies.