The Danish Peace Academy

SCIENCE AND SOCIETY

John Avery
H.C. Ørsted Institute, University of Copenhagen

Chapter 16 HIROSHIMA AND NAGASAKI

Chain reactions

Within hours of Bohr’s announcement, scientists in various parts of America had begun to set up experiments to look for high-energy fission fragments. On the evening of January 26, Bohr watched, while giant pulses of ionization produced by the fission fragments were recorded on an oscilloscope at the Carnegie Institution’s accelerator in Washington. Similar experiments were simultaneously being performed in New York and California.

At Columbia University, following Fermi’s suggestion, Dunning had performed the experiment a day earlier, on January 25. The news spread rapidly. On the 9th of February, the Austrian physicists, Jentschke and Prankl, reported to the Vienna Academy that they too had observed fission fragments. By March 8, which was Otto Hahn’s 60th birthday, an avalanche of papers on uranium fission had developed in the international scientific literature.

In the spring of 1939, Bohr and Wheeler published an important theoretical paper in which they showed that in nuclei with an even atomic mass numbers, the ground state energy is especially low because of pairing of the nuclear particles. For this reason, Bohr and Wheeler believed that it is the rare isotope, urnaium-235, which undergoes fission. They reasoned that when a slow neutron is absorbed by uranium-235, it becomes a highly-excited state of uranium-236. The extra energy of this excited state can deform the nucleus into a nonspherical shape, and the powerful electrostatic repulsive forces between the protons can then cause the nucleus to split.

During the early spring of 1939, a number of scientists, including Fermi, Szilard and the Joliot-Curies, were becoming acutely aware of another question: Are neutrons produced in uranium fission? This was a question of critical importance, because if more than one neutron was produced, a chain reaction might be possible.

At Columbia University, Enrico Fermi and Leo Szilard began experiments to determine whether neutrons are produced; and similar experiments were performed by the Joliot-Curies in Paris. Both groups found that roughly two neutrons are released. This meant that a nuclear chain reaction might indeed be possible: It might be possible to arrange the uranium in such a way that each neutron released by the fission of a nucleus would have a good chance of causing a new fission.

The possibility of nuclear power became clear to the physicists, as well as the possibility of a nuclear bomb many millions of times more powerful than any ordinary bomb. Leo Szilard (who had seen the atrocities of Hitler’s Germany at close range) became intensely worried that the Nazis would develop nuclear weapons. Therefore he proposed that the international community of physicists should begin a self-imposed silence concerning uranium fission, and especially concerning the neutrons produced in fission.

In Fermi’s words, Szilard “..proceeded to startle physicists by proposing to them that, given the circumstances of the period - you see it was early 1939, and war was very much in the air - given the circumstances of the period, given the danger that atomic energy, and possibly atomic weapons, could become the chief tool of the Nazis to enslave the world, it was the duty of the physicists to depart from what had been the tradition of publishing significant results as soon as the Physical Review or other scientific journals might turn them out, and that instead one had to go easy, keep back some of the results until it was clear whether these results were potentially dangerous...”

“He sent in this vein a number of cables to Joliot in France, but he did not get a favorable response from him; and Joliot published his results more or less like results in physics had been published until that day. So the fact that neutrons are emitted in fission in some abundance - the order of magnitude one or two or three - became a matter of general knowledge; and of course that made the possibility of a chain reaction appear to most physicists as a vastly more real possibility than it had until that time.”

On March 16, 1939, exactly two months after Bohr had arrived in America, he and Wheeler mailed their paper on uranium fission to a journal. On the same day, Enrico Fermi went to Washington to inform the Office of Naval Operations that it might be possible to construct an atomic bomb; and on the same day, German troops poured into Czechoslovakia.

A few days later, a meeting of six German atomic physicists was held in Berlin to discuss the applications of uranium fission. Otto Hahn, the discoverer of fission, was not present, since it was known that he was opposed to the Nazi regime. He was even said to have exclaimed: “I only hope that you physicists will never construct a uranium bomb! If Hitler ever gets a weapon like that, I’ll commit suicide.”

The meeting of German atomic physicists was supposed to be secret; but one of the participants reported what had been said to Dr. S. Flügge, who wrote an article about uranium fission and about the possibility of a chain reaction. Flügge’s article appeared in the July issue of Naturwissenschaften, and a popular version of it was printed in the Deutsche Allgemeine Zeitung. These articles greatly increased the alarm of American atomic scientists, who reasoned that if the Nazis permitted so much to be printed, they must be far advanced on the road to building an atomic bomb.

Einstein writes to Roosevelt

In the summer of 1939, while Hitler was preparing to invade Poland, alarming news reached the physicists in the United States: A second meeting of German atomic scientists had been held in Berlin, this time under the auspices of the Research Division of the German Army Weapons Department. Furthermore, Germany had stopped the sale of uranium from mines in Czechoslovakia.

The world’s most abundant supply of uranium, however, was not in Czechoslovakia, but in Belgian Congo. Leo Szilard was deeply worried that the Nazis were about to construct atomic bombs; and it occurred to him that uranium from Belgian Congo should not be allowed to fall into their hands.

Szilard knew that his former teacher, Albert Einstein, was a personal friend of Elizabeth, the Belgian Queen Mother. Einstein had met Queen Elizabeth and King Albert of Belgium at the Solvay Conferences, and mutual love of music had cemented a friendship between them. When Hitler came to power in 1933, Einstein had moved to the Institute of Advanced Studies at Princeton; and Szilard decided to visit him there. Szilard reasoned that because of Einstein’s great prestige, and because of his long-standing friendship with the Belgian Royal Family, he would be the proper person to warn the Belgians not to let their uranium fall into the hands of the Nazis.

It turned out that Einstein was vacationing at Peconic, Long Island, where he had rented a small house from a friend named Dr. Moore. Leo Szilard set out for Peconic, accompanied by the theoretical physicist, Eugene Wigner, who, like Szilard, was a Hungarian and a refugee from Hitler’s Europe.

For some time, the men drove around Peconic, unable to find Dr. Moore’s house. Finally Szilard, with his gift for foreseeing the future, exclaimed: “Let’s give it up and go home. Perhaps fate never intended it. We should probably be making a frightful mistake in applying to any public authorities in a matter like this. Once a government gets hold of something, it never lets go.” However, Wigner insisted that it was their duty to contact Einstein and to warn the Belgians, since they might thus prevent a world catastrophe. Finally they found the house by asking a small boy in the street if he knew where Einstein lived. Einstein agreed to write a letter to the Belgians warning them not to let uranium from the Congo fall into the hands of the Nazis. Wigner suggested that the American State Department ought to be notified that such a letter was being written.

On August 2, 1939, Szilard again visited Einstein, this time accompanied by Edward Teller, who (like Szilard and Wigner) was a refugee Hungarian physicist. By this time, Szilard’s plans had grown more ambitious; and he carried with him the draft of a letter to the American President, Franklin D. Roosevelt. Einstein made a few corrections, and then signed the fateful letter, which reads (in part) as follows:

“Some recent work of E. Fermi and L. Szilard, which has been communicated to me in manuscript, leads me to expect that the element uranium may be turned into an important source of energy in the immediate future. Certain aspects of the situation seem to call for watchfulness and, if necessary, quick action on the part of the Administration. I believe, therefore, that it is my duty to bring to your attention the following..”

“It is conceivable that extremely powerful bombs of a new type may be constructed. A single bomb of this type, carried by boat and exploded in a port, might very well destroy the whole port, together with some of the surrounding territory..”

“I understand that Germany has actually stopped the sale of uranium from Czechoslovakian mines which she has taken over. That she should have taken such an early action might perhaps be understood on the ground that the son of the German Under-Secretary of State, von Weizäcker, is attached to the Kaiser Wilhelm Institute in Berlin, where some of the American work is being repeated.”

On October 11, 1939, three weeks after the defeat of Poland, Roosevelt’s economic advisor, Alexander Sachs, personally delivered the letter to the President. After discussing it with Sachs, the President commented,“This calls for action.” Later, when atomic bombs were dropped on civilian populations in an already virtually-defeated Japan, Einstein bitterly regretted having signed the letter to Roosevelt.

The first nuclear reactor

As a result of Einstein’s letter, President Roosevelt set up an Advisory Committee on Uranium. On December 6, 1941, the day before the Japanese attack on Pearl Harbor, the Committee decided to make an all-out effort to develop atomic energy and atomic bombs. This decision was based in part on intelligence reports indicating that the Germans had set aside a large section of the Kaiser Wilhelm Institute for Research on uranium; and it was based in part on promising results obtained by Enrico Fermi’s group at Columbia University.

Enrico Fermi and his group at Columbia University had been exploring the possibility of building a chain-reacting pile using natural uranium, together with a moderator to slow the neutrons. Fermi’s own description of the research is as follows:

“...We soon reached the conclusion that in order to have any chance of success with natural uranium, we had to use slow neutrons. So there had to be a moderator. And this moderator could be water, or other substances. Water was soon discarded. It is very effective in slowing down the neutrons, but it absorbs a little bit too many of them, and we couldn’t afford that. Then it was thought that graphite might be a better bet...”

“This brings us to the fall of 1939, when Einstein wrote his now famous letter to Roosevelt, advising him of what was the situation in physics - what was brewing, and that he thought that the government had the duty to take an interest and to help along the development. And in fact, help came along to the tune of six thousand dollars a few months later; and the six thousand dollars were used to buy huge amounts - or what seemed at the time, when the eyes of physicists had not yet been distorted - what seemed at the time a huge amount of graphite.”

“So the physicists on the seventh floor of Pupin Laboratories started looking like coal miners, and the wives to whom these physicists came home tired at night were wondering what was happening. We know that there is smoke in the air, but after all...”

“We started to construct this structure that at that time looked again an order of magnitude larger than anything we had seen before. Actually, if anybody would look at this structure now, he would probably extract his magnifying glass and go close to see it. But for the ideas of the time, it looked really big. It was a structure of graphite bricks, and spread through these graphite bricks in some sort of pattern, were big cans, cubic cans, containing uranium oxide.”

Fermi’s results indicated that it would be possible to make a chainreacting pile using graphite as a moderator, provided that enough very pure graphite and very pure uranium oxide could be obtained. Leo Szilard undertook the task of procuring the many tons of these substances which would be required.

Work on the pile was moved to the University of Chicago, and the number of physicists employed on the project was greatly enlarged. Work preceeded with feverish speed, because it was feared that the Nazis would win the race. Leona Woods, one of the few women employed on the project, recalled later: “We were told, day and night, that it was our duty to catch up with the Germans.”

During the summer of 1942, Fermi succeeded in constructing a uranium-graphite lattice with a neutron reproduction factor greater than unity. In other words, when he put a radium-beryllium neutron source into the lattice, more neutrons came out than were produced by the source. This meant that a chain-reacting pile could definitely be built. It was only a matter of obtaining sufficient amounts of very pure graphite and uranium.

Fermi calculated that a spherical pile, 26 feet in diameter, would be sufficiently large to produce a self-sustained chain reaction. At first, it was planned that the pile should be built at Argonne Laboratory, just outside Chicago. However, the buildings were not yet ready, and therefore Fermi suggested that the pile should instead be built in a squash court under the abandoned football stadium at the University of Chicago. (Football had been banned by the university’s president, Robert Hutchens, who felt that it distracted students from their academic work.)

The squash court was not quite as high as Fermi would have liked it to be, and in case of a miscalculation of the critical size of the pile, it would be impossible to add extra layers. Therefore, Fermi and his young co-worker, Herbert Anderson, ordered an enormous cubical rubber balloon from the Goodyear Tyre Company, and the pile was built inside the balloon. The idea was that, if necessary, the air inside the pile could be pumped out to reduce the absorption of neutrons by nitrogen. This turned out not to be necessary; and the door of the balloon was never sealed.

The graphite-uranium lattice was spherical in shape, and it rested on blocks of wood. The physicists labored furiously, putting the tons of uranium and graphite into place, measuring and cutting the blocks of wood needed to support the pile, and swearing to ease the tension. Leona Woods, wearing goggles and overalls, was indistinguishable from the men as she worked on the pile. Everyone was covered from head to foot with black graphite dust, and graphite also made the floor treacherously slippery.

On December 1, 1942, Herbert Anderson stayed up all night putting the finishing touches on the pile. If he had pulled out the neutron absorbing cadmium control rods, Anderson would have been the first man in history to achieve a self-sustaining nuclear chain reaction. However, he had promised Fermi not to do so.

Enrico Fermi got a good night’s sleep; and on the next morning, December 2, he was ready to conduct the historic experiment. About forty people were present. Most of them were scientists who had worked on the pile; but there were a few visitors, including a representative of the giant DuPont chemical company, which was undertaking a contract to build more chain-reacting piles.

Fermi, and all the spectators, stood on the balcony of the squash court. On the floor of the court stood a single physicist, George Weil, who was ready to pull out the final control rod. On the top of the pile, crouched in the cramped space under the top of the balloon, was a “suicide squad” - three young physicists who had volunteered to sit there during the experiment with containers of cadmium salt solution, which they would pour into the pile if anything went wrong.

Fermi was confident that nothing would go wrong. He had calculated that even if the last control rod were removed completely, the neutron flux within the pile would not jump rapidly to a high level. Instead, it would begin to increase slowly and steadily. The slow response of the pile was due to the fact that much time was required for the fast neutrons released by fission to be slowed by collisions with carbon atoms in the graphite moderator.

Although, according to theory, there was no danger, Fermi approached the chain reaction with great caution. He explained to the spectators that George Weil would pull out the final control rod by very slow stages; and at each stage, measurements would be made to make sure that the behavior of the pile checked with calculations. The neutron flux was measured by Geiger counters, and recorded by a pen on a roll of paper.

“Pull it out a foot, George”, Fermi said; and he explained to the spectators: “Now the pen will move up to this point and then level off.” The response was exactly as predicted.

Throughout the morning, this procedure was repeated. However, by lunchtime, much of the control rod still remained within the pile. Fermi was a man of fixed habits, and although no one else showed any signs of being hungry, he said: “Let’s go to lunch.”

After lunch, the experiment was continued; and by 2:30 in the afternoon, the critical point was reached. “Pull it out another foot, George”, Fermi said, and then he added: “This will do it. Now the pile will chainreact.” The Geiger counters began to click faster and faster, and the recording pen moved upward with no sign of leveling off. On top of the pile, the suicide squad waited tensely with their containers of cadmium solution.

Leona Woods whispered to Fermi: “When do we get scared?” However, the pile behaved exactly as predicted, and after 28 minutes, the control rod was reinserted. Eugene Wigner then produced a bottle of Chianti wine which he had kept concealed until that moment, and everyone drank a little, in silence, from paper cups.

The atomic bomb

The chain-reacting pile had a double significance: Its first meaning was a hopeful one - It represented a new source of energy for mankind. The second meaning was more sinister - It was a step on the road to the construction of atomic bombs.

According to the Bohr-Wheeler theory, it was predicted that plutonium- 239 should be just as fissionable as uranium-235. Instead of trying to separate the rare isotope, uranium-235, from the common isotope, uranium-238, the physicists could just operate the pile until a sufficient amount of plutonium accumulated, and then separate it out by ordinary chemical means.

This was done on a very large scale by the Dupont chemical company. Four large chain-reacting piles were built beside the Colombia River at Hanford, Washington. Cold water from the river was allowed to flow through the piles to carry away the heat.

An alternative method for producing atomic bombs was to separate the rare fissionable isotope of uranium from the common isotope. Three different methods for isotope separation seemed possible: One could make a gaseous compound of uranium and allow it to diffuse through a porous barrier. (The lighter isotope would diffuse slightly faster.)

Alternatively, one could use a high-speed gas centrifuge; or one could separate the isotopes in a mass spectrograph.

All three methods of isotope separation were tried, and all proved successful. Under Harold Urey’s direction, a huge plant to carry out the gaseous separation methods was constructed at Oak Ridge Tennessee; and at the University of California in Berkeley, Ernest O. Lawrence and his group converted the new giant cyclotron into a mass spectrograph. Ultimately, 150,000 people were working at Hanford, Oak Ridge and Berkeley, producing material for atomic bombs. Of these, only a few knew the true purpose of the work in which they were engaged. Calculations performed in England by Otto Frisch and Rudolf Peierels showed that the critical mass of fissionable material needed for a bomb was about two kilograms. If this mass of material were suddenly assembled, a chain-reaction would start spontaneously. An avalanche of neutrons would develop with almost-instantaneous speed, because no time would be needed for the neutrons to be slowed by a moderator. The lower efficiency of the fast neutrons would be offset by the high concentration of fissionable nuclei, and the result would be a nuclear explosion.

Following a joint decision by Roosevelt and Churchill, English work on atomic bombs was moved to the United States and Canada, where it was combined with the research already being conducted there by American and refugee European scientists. Work on the bomb project was driven forward by an overpowering fear that the Nazis would be the first to construct nuclear weapons.

In July, 1943, Robert Oppenheimer of the University of California was appointed director of a secret laboratory where atomic bombs would be built as soon as material for them became available. At the time of his appointment, Oppenheimer was 39 years old. He was a tall, thin man, with refined manners, and a somewhat ascetic appearance. Oppenheimer was the son of a wealthy and cultured New York fi- nancier. He had graduated from Harvard with record grades, and had done postgraduate work in theoretical physics under Max Born at the University of Göttingen in Germany.

Robert Oppenheimer had then worked with E.O. Lawrence, who was separating the isotopes of uranium, using the Berkeley cyclotron, which had been converted to a mass spectrograph. After making a technical innovation which greatly reduced the cost of separation, Oppenheimer had been appointed the head of the theoretical group of the atomic bomb project. He proved to be a gifted leader. His charm was hypnotic; and under his leadership, “something got done, and done at astonishing speed”, as Arthur Compton said later.

Oppenheimer proposed that all work on building atomic bombs should be assembled in a secret laboratory. This proposal was adopted; and because Oppenheimer had shown such gifts as a leader, he was made head of the secret laboratory.

At first, it was planned that this laboratory should be located near to the huge isotope separation plant at Oak Ridge, Tennessee. However, spies often were set on shore on the Atlantic coast of the United States by German submarines; and a number of spies were captured near to Oak Ridge. Therefore, Oppenheimer and General Leslie Groves (the military director of the project) looked for a more isolated site in the western part of the country.

Oppenheimer had boyhood memories of New Mexico, where he and his brother, Frank, had spent their vacations. He took General Groves to a boy’s school, which he remembered, on a high plateau near the Los Alamos canyon. The mesa where the boy’s school was located was the flat top of a mountain, 7,000 feet above sea level, overlooking the valley of the Rio Grande River.

It was a completely isolated place. Apart from the few buildings of the school, one saw only scattered aspens and fragrant pines, the red rock of the mesa, and the Jemez mountains on the horizon, standing out sharply in the dry, transparent air. Sixty miles separated Los Alamos from the nearest railway station, at Santa Fe, New Mexico.

Oppenheimer and Groves decided that this would be an excellent place for the secret laboratory which they were planning; and they told the headmaster that the school would have to be closed. It would be bought for government war work. The buildings of the school would accommodate the first scientists arriving at Los Alamos while other buildings were being constructed. Within a year of the first visit to the lonely mesa by Oppenheimer and Groves, 3,500 people were working there; and in another year, the population of scientists and their families had grown to 6,000. More and more scientists received visits from the persuasive young director, Robert Oppenheimer; and more and more of them disappeared to the mysterious “Site Y”, a place so secret that its location and name could not be mentioned, and knowledge of its mere existence was limited to very few people.

Many of the scientists who had fled from Hitler’s Europe found themselves reunited with their friends at “Site Y”. Fermi, Segrè, Rossi, Bethe, Peierls, Chadwick, Frisch, Szilard and Teller all were there. Even Niels Bohr arrived at Los Alamos, together with his son, Aage, who was also a physicist.

Bohr had remained in Denmark as long as possible, in order to protect his laboratory and his co-workers. However, in 1943, he heard that he had been marked by the Germans for arrest and deportation; and he escaped to Sweden in a small boat. In Sweden, he helped to rescue the Jewish population of Denmark from the Nazis; and finally he arrived at Los Alamos.

As time passed, many of the scientists at Los Alamos, including Niels Bohr, became deeply worried about the ethical aspects of work on the atomic bomb. When the project had first begun, everyone was sure that the Germans had a great lead in the development of nuclear weapons. They were convinced that the only way to save civilization from the threat of Nazi atomic bombs would be to have a counterthreat.

In 1944, however, as the Allied invasion of Europe began, and no German atomic bombs appeared, this dogma seemed less certain. In 1943, a special intelligence unit of the American Army had been established. Its purpose was to land with the first Allied troops invading Europe, and to obtain information about the German atomic bomb project. The code-name of the unit was Aslos, a literal Greek translation of the name of General Groves. The Dutch refugee physicist, Samuel Goudschmidt, was the scientific director of the Aslos mission.

When Strasbourg fell to the Allies, Goudschmidt found documents which made it clear that the Germans had not even come close to building atomic bombs. While walking with one of his military colleagues, Goudschmidt exclaimed with relief, “Isn’t it wonderful? The Germans don’t have atomic bombs! Now we won’t have to use ours!” He was shocked by the reply of his military colleague: “Of course you understand, Sam, that if we have such a weapon, we are going to use it.” Goudschmidt’s colleague unfortunately proved to have an accurate understanding of the psychology of military and political leaders.

The news that the Germans would not produce atomic bombs was classified as a secret. Nevertheless, it passed through the grapevine to the scientists working on the atomic bomb project in America; and it reversed their attitude to the project. Until then, they had been worried that Hitler would be the first to produce nuclear weapons. In 1944, they began to worry instead about what the American government might do if it came to possess such weapons.

At Los Alamos, Niels Bohr became the center of discussion and worry about the ethics of continued work on the bomb project. He was then 59 years old; and he was universally respected both for his pioneering work in atomic physics, and for his outstandingly good character. Bohr was extremely worried because he foresaw a postwar nuclear arms race unless international control of atomic energy could be established.

Consequently, as a spokesman for the younger atomic scientists, he approached both Roosevelt and Churchill to urge them to consider means by which international control might be established. Roosevelt, too, was worried about the prospect of a postwar nuclear armaments race; and he was very sympathetic towards Bohr’s proposals for international control. He suggested that Bohr travel to England and contact Churchill, to obtain his point of view.

Churchill was desperately busy, and basically unsympathetic towards Bohr’s proposals; but on May 16, 1944, he agreed to a halfhour interview with the scientist. The meeting was a complete failure. Churchill and his scientific advisor, Lord Cherwell, spent most of the time talking with each other, so that Bohr had almost no time to present his ideas.

Although he could be very persuasive in long conversations, Bohr was unable to present his thoughts briefly. He wrote and spoke in a discursive style, similar to that of Henry James. Each of his long, convoluted sentences was heavily weighted with qualifications and dependent clauses. At one point in the conversation, Churchill turned to Lord Cherwell and asked: “What’s he talking about, physics or politics?”

Bohr’s low, almost whispering, way of speaking irritated Churchill. Furthermore, the two men were completely opposed in their views: Bohr was urging openness in approaching the Russians, with a view to establishing international control of nuclear weapons. Churchill, a defender of the old imperial order, was concerned mainly with maintaining British and American military supremacy.

After the interview, Churchill became worried that Bohr would give away “atomic secrets” to the Russians; and he even suggested that Bohr be arrested. However, Lord Cherwell explained to the Prime Minister that the possibility of making atomic bombs, as well as the basic means of doing so, had been common knowledge in the international scientific community ever since 1939.

After his disastrous interview with Churchill, Niels Bohr carefully prepared a memorandum to be presented to President Roosevelt. Realizing how much depended on its success or failure, Bohr wrote and rewrote the memorandum, sweating in the heat of Washington’s summer weather. Aage Bohr, who acted as his father’s secretary, typed the memorandum over and over, following his father’s many changes of mind.

Finally, in July, 1944, Bohr’s memorandum was presented to Roosevelt. It contains the following passages: “...Quite apart from the question of how soon the weapon will be ready for use, and what role it will play in the present war, this situation raises a number of problems which call for urgent attention. Unless, indeed, some agreement about the control of the new and active materials can be obtained in due time, any temporary advantage, however great, may be outweighed by a perpetual menace to human society.” “Ever since the possibilities of releasing atomic energy on a vast scale came into sight, much thought has naturally been given to the question of control; but the further the exploration of the scientific problems is proceeding, the clearer it becomes that no kind of customary measures will suffice for this purpose, and that the terrifying prospect of a future competition between nations about a weapon of such formidable character can only be avoided by a universal agreement in true confidence...”

Roosevelt was sympathetic with the ideas expressed in this memorandum. In an interview with Bohr, he expressed his broad agreement with the idea of international control of atomic energy. Unfortunately, the President had only a few months left to live.

At the University of Chicago, worry and discussion were even more acute than at Los Alamos. The scientists at Chicago had better access to the news, and more time to think. A committee of seven was elected by the Chicago scientists to draft their views into a report on the social and political consequences of atomic energy. The chairman of the committee was the Nobel-laureate physicist James Franck, a man greatly respected for his integrity.

The Franck Report was submitted to the American Secretary of War in June, 1945; and it contains the following passages:

“In the past, science has been able to provide new methods of protection against new methods of aggression it made possible; but it cannot promise such effective protection against the destructive use of nuclear energy. This protection can only come from the political organization of the world. Among all the arguments calling for an efficient international organization for peace, the existence of nuclear weapons is the most compelling one...”

“If no efficient international agreement is achieved, the race for nuclear armaments will be on in earnest not later than the morning after our first demonstration of the existence of nuclear weapons. After this, it might take other nations three or four years to overcome our present head start...”

“It is not at all certain that American public opinion, if it could be enlightened as to the effect of atomic explosives, would approve of our own country being the first to introduce such an indiscriminate method for the wholesale destruction of civilian life... The military advantages, and the saving of American lives, achieved by a sudden use of atomic bombs against Japan, may be outweighed by a wave of horror and revulsion sweeping over the rest of the world, and perhaps even dividing public opinion at home...”

“From this point of view, a demonstration of the new weapon might best be made, before the eyes of representatives of all the United Nations, on the desert, or on a barren island. The best possible atmosphere for.. an international agreement could be achieved if America could say to the world: ‘You see what sort of weapon we had but did not use. We are ready to renounce its use in the future, if other nations join us in this renunciation, and join us in the establishment of an efficient control’.”

“One thing is clear: Any international agreement on the prevention of nuclear armaments must be backed by actual and effective controls. No paper agreement can be sufficient, since neither this nor any other nation can stake its whole existence on trust in other nations’ signatures.” The Franck report then goes on to outline the steps which would have to be taken in order to establish efficient international control of atomic energy. The report states that the most effective method would be for an international control board to restrict the mining of uranium ore. This would also prevent the use of atomic energy for generating electrical power; but the price would not be too high to pay in order to save humankind from the grave dangers of nuclear war.

Unfortunately, it was too late for the scientists to stop the machine which they themselves had set in motion. President Franklin Roosevelt might have stopped the use of the bomb; but in August, 1945, he was dead. On his desk, unread, lay letters from Albert Einstein and Leo Szilard - the same men who had written to Roosevelt six years previously, thus initiating the American atomic bomb project. In 1945, both Einstein and Szilard wrote again to Roosevelt, this time desperately urging him not to use nuclear weapons against Japan; but their letters arrived too late.

In Roosevelt’s place was a new President, Harry Truman, who had been in office only a few weeks. He came from a small town in Missouri; and he was shocked to find himself suddenly thrust into a position of enormous power. He was overwhelmed with new responsibilities, and was cautiously feeling his way. Until Roosevelt’s death he had known nothing whatever about the atomic bomb project; and he therefore had little chance to absorb its full meaning.

By contrast, General Leslie Groves, the military commander of the bomb project, was very sure of himself; and he was determined to use atomic bombs against Japan. General Groves had supervised the spending of two billion dollars of the American taxpayers’ money. He was anxious to gain credit for winning the war, rather than to be blamed for the money’s misuse.

Under these circumstances, it is understandable that Truman did nothing to stop the use of the atomic bomb. In General Groves’ words, “Truman did not so much say ‘yes’, as not say ‘no’. It would, indeed, have taken a lot of nerve to say ‘no’ at that time.”

August 6

On August 6, 1945, at 8:15 in the morning, an atomic bomb was exploded in the air over Hiroshima. The force of the explosion was equivalent to twenty thousand tons of T.N.T.. Out of a city of two hundred and fifty thousand people, almost one hundred thousand were killed by the bomb; and another hundred thousand were hurt. In some places, near the center of the city, people were completely vaporized, so that only their shadows on the pavement marked the places where they had been. Many people who were not killed by the blast or by burns from the explosion, were trapped under the wreckage of their houses. Unable to move, they were burned to death in the fire which followed.

Some accounts of the destruction of Hiroshima, written by children who survived it, have been collected by Professor Arata Osada. Among them is the following account, written by a boy named Hisato Ito. He was 11 years old when the atomic bomb was exploded over the city: “On the morning of August 5th (we went) to Hiroshima to see my brother, who was at college there. My brother spent the night with us in a hotel... On the morning of the 6th, my mother was standing near the entrance, talking with the hotel proprietor before paying the bill, while I played with the cat. It was then that a violent flash of blue-white light swept in through the doorway.”

“I regained consciousness after a little while, but everything was dark. I had been flung to the far end of the hall, and was lying under a pile of debris caused by the collapse of two floors of the hotel. Although I tried to crawl out of this, I could not move. The fine central pillar, of which the proprietor was so proud, lay flat in front of me. ”

“I closed my eyes and was quite overcome, thinking that I was going to die, when I heard my mother calling my name. At the sound of her voice, I opened my eyes; and then I saw the flames creeping close to me. I called frantically to my mother, for I knew that I should be burnt alive if I did not escape at once. My mother pulled away some burning boards and saved me. I shall never forget how happy I felt at that moment - like a bird let out of a cage.”

“Everything was so altered that I felt bewildered. As far as my eyes could see, almost all the houses were destroyed and on fire. People passed by, their bodies red, as if they had been peeled. Their cries were pitiful. Others were dead. It was impossible to go farther along the street on account of the bodies, the ruined houses, and the badly wounded who lay about moaning. I did not know what to do; and as I turned to the west, I saw that the flames were drawing nearer..”

“At the water’s edge, opposite the old Sentai gardens, I suddenly realized that I had become separated from my mother. The people who had been burned were plunging into the river Kobashi, and then were crying our: ‘It’s hot! It’s hot!’ They were too weak to swim, and they drowned while crying for help.”

In 1951, shortly after writing this account, Hisato Ito died of radiation sickness. His mother died soon afterward from the same cause. When the news of the atomic bombing of Hiroshima and Nagasaki reached Albert Einstein, his sorrow and remorse were extreme. During the remainder of his life, he did his utmost to promote the cause of peace and to warn humanity against the dangers of nuclear warfare. When Otto Hahn, the discoverer of fission, heard the news of the destruction of Hiroshima, he and nine other German atomic scientists were being held prisoner at an English country house near Cambridge. Hahn became so depressed that his colleagues feared that he would take his own life.

Among the scientists who had worked at Chicago and Los Alamos, there was relief that the war was over; but as descriptions of Hiroshima and Nagasaki became available, there were also sharp feelings of guilt. Many scientists who had worked on the bomb project made great efforts to persuade the governments of the United States, England and Russia to agree to international control of atomic energy; but these efforts met with failure; and the nuclear arms race feared by Bohr developed with increasing momentum.

Chapter 17: GENESPLICING.

Suggestions for further reading

1. Robert Jungk, Brighter Than a Thousand Suns, Pennguin Books Ltd. (1964).
2. Werner Braunbeck, The Drama of the Atom, Oliver and Boyd, Edinburgh (1958).
3. Werner Heisenberg, Physics and Beyond; Memories of a Life in Science, George Allen and Unwin (1971).
4. Emilio Segrè, Enrico Fermi, Physicist, The University of Chicago Press (1970).
5. Laura Fermi, Atoms in the Family, The University of Chicago Press (1954).
6. O.R. Frisch, What Little I Remember, Cambridge University Press (1979).
7. James L. Henderson, Hiroshima, Longmans (1974).
8. Arata Osada, Children of the A-Bomb, The Testiment of Boys and Girls of Hiroshima, Putnam, New York (1963).
9. Michehiko Hachiya, M.D., Hiroshima Diary, The University of North Carolina Press, Chapel Hill, N.C. (1955).
10. Marion Yass, Hiroshima, G.P. Putnam’s Sons, New York (1972).
11. Robert Jungk, Children of the Ashes, Harcourt, Brace and World (1961).
12. Burt Hirschfield, A Cloud Over Hiroshima, Baily Brothers and Swinfin Ltd. (1974).
13. John Hersey, Hiroshima, Penguin Books Ltd. (1975).

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