To Fermi ~ with Love (part 2 of 2)

Finally, the decision was made. Build the pile in the west stands. The facilities under Stagg Field included the usual locker room, showers, and four handball or rackets courts. The heavy graphite material began to roll in on large skids the same night. The rackets court was 60 feet long, 30 feet wide, and 26 feet high. It would house the pile, which would take the shape of a sphere or doorknob, flat on top, almost reaching the ceiling. It would be built up of graphite blocks containing lumps of uranium. As work progressed, Carpenter Gus Newth recalls some of the problems. Then the pile went up to 10 foot high, and it started getting wider and wider at the top. Anderson and they come over and want to know what I could do. I says, I can't do anything. I don't know. I says, I haven't got the education. I said, leave it up to you fellas. Well, then they shut it down for a day and a night. I said, let me talk to Dr. Fermi. They had meetings and meetings, and every meeting they had, Fermi says, why don't you call Gus? Maybe he can help us. Ask Gus. Nobody wanted to ask Gus. So Fermi walked down the hallway, and I said, there's Fermi. Call him in. He came in, Fermi was never without his slide rule. It became a trademark of his character. Many recall how often he used it, including Otto Hillig. That's why I call him Great Master. He called me Great Dan, and I called him the Big Master when he come in in the morning. Fermi's slide rule even led to the creation of a humorous law of physics developed by Crawford Greenewalt. Perhaps I should have said this first, because it's the thing that I remember best, and that's Enrico Fermi's complete calmness. He was walking around as if he was simply waiting for the barber to say, Mr. Fermi, come have your hair cut. It took six weeks to assemble the final pile, from late October to the first days of December. 400 tons of graphite and 50 tons of uranium. It was a deceptively simple device, contrived to make a sufficient number of neutrons do their duty. When reactor engineers were stumped by the lack of nuclear data, they would put their problems to Fermi. Fermi would protest that he could not help them, because the number they wanted had not been measured and could not be predicted. The engineers, ignoring Fermi's protest, began reciting slowly a series of numbers while watching his eyes closely. The correct number would produce an involuntary twinkle in Fermi's eyes. On the night of December 1st, the control rods were locked. The 57th layer would make the pile go critical. Only little more material would be needed to finish it. Further work was postponed until the following day. On the morning of December 2nd, 1942, the steam lines under the stands were again out of commission. It was cold, drafty. The environment inside never created a false sense of security. Groups of scientists began to gather in the rackets court. On the balcony at the east end were Fermi, Zinn, and Anderson, grouped around some instruments. On the floor, beneath the balcony, young George Weil was standing by to handle the final control rod. On a platform above the pile stood the liquid control squad. Crawford Greenewalt describes the scene. The whole atmosphere there was one of calmly observing an experiment being made. To be sure, there was a suicide squad that you could see on the other end of the platform with their catapult and nitrate ready to pour in. If it didn't work, but it became obvious very quickly that it was going to be controlled. The experimental procedure was one of calm routine. The pile had been built up slowly, layer by layer. At 9.45 a.m., Fermi asked that the cadmium strips be pulled out and the neutron density checked. Next, he ordered the electrically operated control rods withdrawn. Shortly after 10 o'clock, he asked for the emergency rod to be pulled out and tied. Walter Zinn and Herb Anderson described the scene. He announced this. He said, now you look at this, and it will rise this high. And they pulled out the rod, and it went that high, and the counters clicked a little more, and kept this up a number of times, each time being right about it. Norman Hilberry contributes some insight to Fermi's uncanny accuracy. Fermi had, the night before, sat down and computed what the trace on the recording galvanometer would be. For every single position of the control rod, clearly, if there were any new law of physics, it would begin to show up in an actual deviation of the observed graphs from those he had computed. And each time, it hit absolutely right on the middle. I am sure that long before Fermi finally says, George, pull it out another 10 inches, the question had long since been settled in his mind, and long since settled mine, too. Fermi called a recess for lunch, and the group headed for the student cafeteria. Gus Newth recalls his surprise. By 2 p.m., the scientists were back in the racket's court. The experiment continued. Herb Anderson remembers Fermi's confidence. Then, back from lunch, he called for another increase in activity, again predicted it on the nose, you see. And then finally says, now we'll make a chain react. I mean, for the first time in the history of man, we'll pull the rod out. The nimble-minded Fermi, the infallible judge, had helped usher in the nuclear age. Dr. Compton recalls the moment. That was one of the great talents of the man. While Fermi's group had demonstrated and controlled fission, chemists at the Metallurgical Lab had successfully purified the first weighable amounts of plutonium, 2.77 micrograms. Each success only christened more effort. To scale up these laboratory experiments to industrial proportions might prove insurmountable. It seemed almost beyond human capability. Crawford Greenewald poses the question. was a problem which loomed, in my view, quite as large as the problem of building a reactor that would work. By January 1943, the Manhattan Project had grown in all directions. Project Y had been selected on an isolated mesa 35 miles northwest of Santa Fe, New Mexico. By February, engineers were building the Clinton Engineer Works between the Great Smoky and Cumberland Mountains in Tennessee. In March, 45,000 construction workers began building the largest site of all, the Hanford Engineer Works, along the Columbia River in the state of Washington. General Groves, who selected the sites, recalls his reasons for picking Hanford. There were several reasons. One was power, one was the Columbia River, and the other thing was that, which was all important, was an ability to construct the year-round. What started out as a small, intimate group of physicists designing a laboratory experiment had now grown into a large, diverse military and industrial project. Until the summer of 1944, Fermi kept his residence in Chicago. He made many long trips to Hanford, Los Alamos, and Oak Ridge, advising and assisting in all phases of research. General Groves had restricted top scientists from airplane travel. Fermi had to make these trips by train. On each visit, the scientists had to travel under assumed names. This led to a humorous incident that occurred to Fermi in Hanford. Colonel Frank Mathias remembers. The scientists that came here usually were here under assumed names. And Dr. Fermi became Dr. Farmer, and Dr. Wigner became Dr. Wagner, and Dr. Compton was, he was Dr. Comus here. They all had names. Dr. Wigner and Dr. Fermi, and I like to tell this story because Dr. Fermi was somebody we all loved and admired, went out to the area one day and they were challenged by a security guard, and Dr. Wigner couldn't quite satisfy the guard that he was acceptable. As this discussion went on, finally there was a question, is your name really Dr. Wagner? And Fermi stepped up and he says, his name is Dr. Wagner, just as sure as my name is Dr. Farmer. And the problem was solved. The Hanford project was a $350 million crash program to build the world's first plutonium production facility. DuPont was undertaking an engineering feat that would strain every fiber of their industrial resources. Fermi had some simple advice for accomplishing this miracle in the desert. I remember Fermi saying to me one time, he said, now you're going at this all wrong. What you should do is to build a unit just as quickly as you can. It won't work. You'll find out why it doesn't work, and then you'll build one that does. There in the Washington desert, isolated from the everyday demands of life, Fermi engaged his fellow scientists in mind games. It was a carryover trait from his days in Rome, when he played the game of two lira. John Wheeler recalls the sport. Of course I remember especially the penny that he would give out, a penny any time that anybody could find an error in his English. He was resolved to make himself good in English and not to leave any errors in what he said. But another feature of Fermi was the lunchtime. Lunch was not an occasion merely to relax and eat food. Lunch was an occasion to shoot puzzles at each other. It could be anything. You look out at the sky and you see the ripples in the sky. Why are these ripples there? That's the question. Any one of us might have stated it, and if somebody else could answer it, he got a penny for his answer. But if nobody could answer it, then it fell to the person who had originally asked the question to provide the answer. And if he couldn't provide the answer, he had to pay the penny. Although the magnitude and character of the Manhattan Project had changed abruptly since those early days in Chicago and Columbia, Fermi never lost his sense of humor. Dale Babcock of DuPont remembers. My last item will deal with Dr. Fermi. We all had a great amount of admiration for him, a tremendous figure in the physics world. But he also had a kind of a humorous side. One day he got we people that were driving back and forth between Richland and this area where we're in right now. He asked us to note when we were crossing a certain five-mile area out here, to note the number of coyotes that we saw crossing the road. Well, each morning we'd come in and we'd say we saw two coyotes between the time of 10 at night and 11 at night, or whatever his time period was. And someone else would say he saw none, and someone else would say as many as three or four. Well, after Fermi had enough data on this, he then decided that he would make some use of it. Well, what he said was he was determining the flux of coyotes, just exactly as we had been determining the flux of neutrons in a reactor. And the motion of the coyotes back and forth is a mechanism whereby you can calculate the number of coyotes that are in existence here. Well, the arithmetic that he went through to get that, I won't go through with it. But anyway, he told us that there was about one coyote per square mile on the project out here. And also, after we got this figure, he then had us count jackrabbits, and the number of jackrabbits he crossed gave the flux of jackrabbits, and he came up with a figure of about 300 rabbits per square mile. One final piece of calculation was, one day someone came in and said, I hit a coyote today. How do I count it? Does it cross the road, or does it not cross the road? Well, it so turned out that this was a very interesting item to Dr. Fermi. He says, this becomes a collision probability. And he did a little bit of arithmetic, and he says, well, that says that the cross-section of a coyote is only one square centimeter. In the summer of 1944, the Fermis were to move to Los Alamos. There, in the isolation of the New Mexico desert, the war project would come to fruition. Shortly before leaving for Los Alamos, the Fermis swore allegiance to the United States. On July 11, 1944, they became naturalized citizens. In Los Alamos, Fermi served as general consultant to the project, directing the Advanced Development Division. Here, he would remain for 17 months, a period of hard work and great happiness. He spent many leisure hours on frequent hiking trips into the nearby mountains around Los Alamos. During working hours, he was engaged in brainstorming discussions with Robert Oppenheimer, Hans Bethe, John von Neumann, Victor Weisskopf, Bruno Rossi, his old friend Emilio Segre, and many others. Slowly but surely, small amounts of purified plutonium began to arrive from the Hanford production reactors. The project, started in the summer of 1941, was now three and a half years along. Early one morning, on July 16, 1945, at 5.30 a.m., Fermi found himself ten miles from ground zero. He was gazing intently at the horizon, while busily dropping small pieces of paper to the ground from a height of six feet. Suddenly, the pre-dawn sky was ablaze with light. Forty seconds later, the front of the shockwave reached Fermi and his colleagues. By measuring the displacement of the confetti produced by the shockwave, Fermi was able to determine the energy release of the explosion. The same force as that produced by 10,000 tons of TNT. Project Trinity vividly demonstrated the long-suspected secret of the immense energy slumbering in the heart of the atom. Fermi again was displaying his uncanny clairvoyance. Herb Anderson, who knew him best, remembers. I think his great strength in his work was his clear thinking and instantaneous. I used to say that he had no inertia and he would start to work out a problem just as soon as he heard it. You give him a pose of problem, he immediately tries to solve it. He doesn't wait for the evening or when it's quiet or when there isn't any noise around. There could be any amount of din and you pose a problem to it and he immediately wants to solve it. Only 31 months had passed since Stagg Field. What followed the Trinity event is now history. Within 48 days of its demonstration near Alamogordo, the atomic bomb formally brought World War II to an abrupt end on September 2, 1945. It foreclosed the prospect of a long, bloody conflict. General Groves had never estimated the chance of success at more than 60%. Ironically, only six and a half years had elapsed since Bohr's arrival to America with the news of fission. John Wheeler characterizes the meaning of that eventful January day in 1939. It was purely an accident that fission should have come here, driven here really in some ways by Hitler. Yet we seized the opportunity. We didn't let it fall. We carried the ball. We ran with it. And we did things that we never knew we had it in our power to do. And as a result, we've achieved a position of responsibility in the world that no nation has ever had before at any time in history. There is one fact that most Americans never realized. Following the defeat of the Nazis in Europe on May 8, 1945, Allied military plans had set November 1, 1945 as the date for the invasion of the Japanese mainland. Troop ships were being loaded with war-weary soldiers from the European theater for combat in the Far East. Dr. Wheeler underscores the true meaning of the scientific success at Hanford and Los Alamos. And we see here also something that to me means very much the empty hospitals overseas prepared for the invasion of Japan that were never used tell only part of the story. The half million or more casualties that were expected on the American side are of course only a fraction of those that would have occurred altogether. So this reactor means a great deal to me. The long, arduous years of scientific endeavor had come to an end. Success was never preordained. It was an endeavor performed in wartime, in secrecy, almost in isolation. It was a story of many sacrifices. The Manhattan Project was a symbiosis between American and European scientists, a display of gratitude to a country that had offered aliens asylum. Walter Zinn, a Canadian himself, recalls perhaps the one subtle advantage that ensured success of the project. The United States Enterprise, however, had one asset which overbalanced all of the above. And that was Enrico Fermi. He guided the effort along the most direct path and by his great intuition of physical matters bypassed most of the false leads that nature puts in the way of any development. In the final analysis, the success of these six long years of concerted effort was directly related to people. People who had labored long and hard up the dark pathway behind them for a vision they could scarcely see. Walter Zinn and Crawford Greenewald remember. I wish I knew the secret of getting such an organization going because I think it would be wonderful to do anything, build power reactors or even space flight and so on if we really knew how to get it. But I don't think there was a formula for getting it. I think it was a matter of people. And you don't find Arthur Compton and Enrico Fermi in very many projects. But I think my own faith rested really more on people than it did on experiments. I think that really my own feeling at the time was that you really ought to have faith in people. Now I had accumulated in a very short period of time unbounded faith in Enrico Fermi. After four years of war work, Fermi and his family boarded still another train in Los Alamos on New Year's Eve, 30 minutes before 1946. He was returning to Chicago, eventually to accept a professorship in the newly created Institute for Nuclear Studies at the University of Chicago. He had declined the directorship, again a persistent reluctance to take on administrative responsibilities. Physics was the essence of his life. All he really wanted to do was to live in peace, to work, to teach. Fermi just loved to teach. He would always teach twice as much as anybody else and do it twice as easily, with less preparation, and felt it was an essential exercise. And he enjoyed the process of explaining things to people and making them clear. Here's a man that could give you answers when you needed them. You didn't have to get them yourself. Fermi led a simple, frugal life. His sincerity and integrity were immersed in a sea of understatement. He never truly had outgrown a severe industrious middle class upbringing. He was very regular in his habits. He used to leave promptly at 6 o'clock no matter what happened. If something had to go on, he would leave it to me. He would go home, have his dinner. And in the evening he would never work on physics. But he might get up at 4 in the morning, you see, and do a lot of... He used to come to work at 8 o'clock, but he'd already been working three hours. And so he'd already figured out everything that had to be figured out. He was already very well prepared. Home for the Fermi family was a large three-story house at 5327 University Avenue. His lectures at the university were always crowded. The constellation of students who studied under Fermi was immense. As C.N. Yang once remarked, his distillation, his simplicity of reasoning conveyed the impression of effortlessness. I think the impressive thing was that he was always very well prepared. And he'd always thought through everything that had to be done, and any question that anybody might conceivably answer. Because he always knew the answer, he'd already thought about it. And he always knew and was always accurate. He never had to reverse himself. And so it was natural that everybody came to see him. Everything he said would be very significant and reflect constructively on the work that they were doing. Fermi indeed worked hard, with an unbounded energy and physical stamina. He celebrated the sheer fact of being alive by physical exertion, by hiking, skiing, swimming. He certainly got a great deal of pleasure out of living and doing things. In a sense, this was very infectious. He loved to walk, to climb mountains, to swim. One thing we did in Chicago every day without fail during the summer, swim in Lake Michigan. Throughout his entire life, Fermi was eternally embarrassed by notoriety. He could never stand on ceremony. Eleven years after his hurried exodus from Italy, he finally returned to his homeland in 1949. Again, he was on the push, lecturing, discussing. A man on fire with ideas. He was one of a few physicists who were equally at home in theoretical and experimental physics. And he could do theoretical physics or experimental physics depending on the interest and the timing. So much so that when I came to the point of writing my thesis, he says, you write your thesis, which I had to do myself, and I'll do theoretical physics. So he stopped doing all experimental work, and he started to do theoretical physics and wrote some important papers. And then when I was through with my thesis, he started to work in experimental physics. His entire life was based upon an unstinting drive for simplicity. Perhaps it is the intuitive nature of all physicists to look for such simplicity and beauty. The path to his door was continually populated with a great number of visitors. So in his later years in Chicago, he almost never read anything. There was such a constant stream of physicists coming to see him. He'd ask them what they were doing, and then he would tell them, try to explain it to them in his own way. They would learn so much from that that they would go away very much enlightened, and he would know what was going on. He hardly ever had to read anything. It took too long to read. Much of this narrative has been based upon the unsolicited memories of the people who were fortunate to have worked with Fermi. The ever-recurring Fermi trait. His straightforward honesty, integrity, and total non-conceit. Emilio Segrè crystallizes a lifetime of having known the Pope. Well, first of all, foremost of all, he was a physicist. That was really his main interest and the main driving force in his life. He was a very nice person, very helpful if you had some physics problem. He was very ready to help and so on in physics. Outside of physics, he was very just, but not a particularly warm personality. Upon his return to academic life in Chicago, Fermi again spent his summers lecturing. In 1949, he visited the University of Basel, eventually returning to his native homeland for the first time in eleven years. He attended a conference on cosmic rays in Como, Italy, delivered six lectures in Rome, three in Milan. Science was a way of life, with its own rules, practices, and techniques, to be learned and transmitted from generation to generation. He once expounded upon the scientific method himself. What is the future path? Well, one can go back to the books on methods, which I doubt that many physicists actually do in practice, but anyway, if you go back to the books on methods, you will learn that you have to take experimental data, collect the experimental data, organize the experimental data, begin to make working hypotheses, trying to correlate, maybe not the whole field, but part of the field, until eventually a pattern springs to light, and you have just to pick up the result. Fermi was truly a child of Francis Bacon, who once remarked, science was not a belief to be held, but a work to be done. Fermi lifted the lantern of his intellect upon the scientific community. His performance took its breath away, altering the outlook of generations, the lightning flashes, the rare leaps of enlightenment. This was all Fermi, a man unique against the vast canvas of science. Leslie Groves put it rather succinctly, as to the scientific end of it, Fermi, of course, was outstanding. He just went along his even way, thinking of science and science only. Science was a constant experimental investigation for Fermi, a learned response, consciously practiced and stripped out of the sea of emotions and prejudices. His wide-ranging mind was a clear lens upon nature. Leona Woods Libby remembers. We were working very closely with him. He was a marvelously wise director of the scientific effort, in the sense that he knew exactly where to be careful, and he could very frequently guess when it was unnecessary to make more accurate measurements. And he had a very good sense of the degree of effort that would give the required result without wasting it. In the post-war years at Chicago, Fermi turned his energies more and more to high-energy physics. When the Chicago synchrocyclotron produced its first beam in 1951, he began investigating pion-nucleon interaction. During this time, he wrote many important papers, including one on the conservation of isotopic spin. In early 1954, Fermi's professional ire was aroused by the security risk investigations of his long-time colleague, Robert Oppenheimer. Fermi compassionately testified on Oppenheimer's behalf before the Personnel Security Board on April 20, 1954. Despite his objective testimony, the Atomic Energy Commissioners declared Oppenheimer to be a security risk by a vote of four to one. Fermi was beside himself, so much so that he called the only press conference of his life to publicly denounce the decision. Tired, depressed by the witch-hunting tactics of government, Fermi spent the summer of 1954 in southern France and Italy. He was lecturing as a guest of the Italian Physical Society. It proved to be the last summer of his life. Shortly after his return to America, he entered Billings Hospital complaining of severe stomach pains. An examination turned up a malignant tumor. Last-minute surgery merely confirmed that the end was near. It would be a sad loss to those who had come to admire him. I think that there were many friendships were formed during that transition period and afterwards. I remember particularly my own with Enrico Fermi, and I think when we finally parted company, we parted as really good friends with a considerable amount of mutual respect and perhaps even affection. I might add, somewhat parenthetically, that Enrico Fermi paid me what I consider to be the highest compliment I think I've ever had when he asked me to stay on at Chicago and work with him on nuclear problems. Despite knowledge of the impending end, Fermi's spirits remained buoyant. He resolutely received friends and visitors in the hospital. When his old colleague Emilio Segre heard the news, he quickly went to Chicago. As he entered the hospital room, there, in typical fashion, was Fermi with a stopwatch in his hand, timing and counting the drops of IV nutrient to determine its flux. He was released from the hospital shortly thereafter and died on Sunday morning, November 29, 1954, two months following his 53rd birthday. It was a sad, untimely departure for so great a man. Fermi had hurried through life, a man without inertia. The elegance of his thought and perception opened the minds of many others. He had apprehended the future with a revived humanism, characterized by what Thoreau had once written, if you would learn the secret of nature, you must practice more humanity than others. This essay cannot possibly capture the essence of the Fermi legacy. It is steeped in the same scientific tradition that took hold of Hahn and Strassman in their Berlin laboratory, that same innate clairvoyance that touched Meitner and Frisch on that snowy December day in Sweden, and the same knowing insight that Bohr carried across the Atlantic to the perceptive minds of Wheeler and Fermi. It is perhaps fitting that we return to the starting point of this treatise, the 10th anniversary celebration beneath the west stands of Stagg Field. Before a small knot of interested colleagues stands the solitary figure of the Italian navigator Enrico Fermi. It has been in science a tradition that has led to the unprecedented flourishing of this human activity to communicate freely among scientists all over the world. Scientific thinking and invention flourish best where people are allowed to communicate as much as possible unentered. From this point of view, complete secrecy would probably mean complete lack of progress, because no fact can be kept a secret better than one that is never discovered. I would like to end these remarks by expressing the great pleasure that I feel in seeing here united several of the people with whom I had the pleasure to work 10 years ago at the task of making a success of the experiment that is being commemorated today.