Story Behind the Atomic Bomb
TEAMWORK AMONG SCIENTISTS
By DR. REUBEN G. GUSTAVSON, Vice President and Dean of Faculties, University of Chicago
Delivered before the Executives' Club of Chicago, Chicago, Illinois, September 7, 1945
Vital Speeches of the Day, Vol. XI, pp. 762-767.
AS the Chairman has just stated, probably no event in the history of mankind has so challenged the imagination of men as the development of the atomic bomb. Mankind probably faced no more serious problem than the problem of what we are to do about it now that we have it.
It has been my privilege to know the men who have worked on this bomb rather intimately. I know that they have given a great deal of attention to the problem which every one of us faces—what are we to do about it. It is their very definite feeling that in a country like ours which is a democracy, and where the people in the last analysis, based on whatever information they may have, make decisions, it is most important that the citizens of our country should be informed about this new development because it is only as the citizens of a democracy are given accurate information by way of the press, by way of the radio, by way of the individuals who can speak to them, that we can hope that their decisions will be wise.
I want to trace for you in the moments that are available to me the general development of the atomic bomb, and then after we have discussed that, I should like to say something, about the great problems that face us as a result of the series of events which led to the manufacture of the bomb.
The notion that matter is made up of atoms is a very old one. It goes away back into Greek philosophic thought. Rather definite notions of the atom began to develop about the time of Sir Isaac Newton, and at that time our general notions were that the different elements were made up of atoms, and we conceived of these atoms as being something of a billiard ball character, hard masses which could be subjected to the greatest of mechanical and chemical forces without in any way destroying them.
Billiard Ball Conception of Atom
We had to have this notion of indestructibility of the atom in order to explain what we then thought of as one of the most fundamental properties of matter; namely, that matter could not be destroyed. So we start then with that billiard ball conception of the atom.
We thought that the atoms of the different elements had different weights, but that the atoms of any given element all had the same weight. We took for awhile as our unit a very light element, hydrogen, which we called (1). The atom of another element was 16 times as heavy as the hydrogen atom, and we called it (16), so we built up a series of weights which we called atomic weights, which represented the weights of individual atoms relative to the hydrogen atom.
That concept served us very well until about 1896 when, as a result of a series of epoch-making discoveries, we began to get acquainted with radio-activity, and here, thanks to the work of Becquerel, of Madame and Pierre Curie, and others that we could mention, we discovered elements which were not stable. We may take radium as an example. It had all the properties of an element, but it differed from the elements that we had previously known in that it was spontaneously going to pieces. It was throwing off from itself some particles of matter which were positively charged, which we called alpha particles; some particles which were negatively charged, which we now call electrons or beta particles; and then a type of radiation of the general nature of light, which we called gamma rays, and which were closely related to X-rays.
Now this discovery gave us our first jar with respect to our notions of the constitution of matter. In the first place, it was evident that the elements were not indestructible because here were elements that were spontaneously going to pieces. At the same time it became evident that the amount of energy that in some way was locked up in matter was enormous.
The Work That Steam Does
Steam does the work of the world. The work that steam does is due to the fact that the small particles of steam which we call molecules are in rapid motion, and the piston in the steam engine moves because literally billions of these particles pound on it. Now, how fast do they move? Well, they move with a velocity of about a quarter of a mile per second, which is pretty fast.
How much energy do they contain? Well, the energy of a moving particle, as you will remember from your physics—perhaps I should say, as you will have forgotten from your physics—is equal to one-half of its mass multiplied by the square of its velocity.
Well, let's figure that out for steam. The mass of the water particle is 18. One-half of it is 9. It moves with a velocity of a quarter of a mile per second. We square that, and we get one-sixteenth. The answer then becomes one-half of 18, which is nine, divided by 16. Let's call it roughly one-half. How much energy is there in this so-called alphaparticle positively charged thrown off from radium? Well, it is thrown off with a velocity of approximately 10,000 miles per second. Let's calculate its energy.
Comparing Radium Energy with Steam
It has a mass of 4, relative to 18 for water. One-half of 4 is 2. Two times 10,000 times 10,000. If my mathetmatics is any good, that is of the general order of 200,000,000. How does the ratio then of the energy of the particle thrown off from radium .compare with that of steam? Well, it is the ratio of 200,000,000 to 1/2 which, if my arithmetic is again right, is 400,000,000.
In other words, the particle thrown off from radium when it spontaneously goes to pieces is roughly 400,000,000 times the energy contained in the steam particle which does the work of the world. That jarred our imaginations. Radium is continually giving off heat. One ounce of radium, for example, will give off roughly about, let us say, 28,000 British thermal units per year. I am trying to stay with units that you are somewhat familiar with. Well, you say, that isn't so much. A ton of coal would contain about 9,000 British thermal units.
Well, let's look at it. Radium goes to pieces, but it loses half of its mass in about something like two thousand years, to stay with round numbers. It loses another half in another two thousand years. You can see then if you multiply the amount of energy given off by an ounce of radium, roughly 28,000 British thermal units per ounce per year, by the length of time which it lasts, again you run into this tremendous quantity of energy.
Scientists discovered then or realized at this time that in the particle that was shot off from radium they had the greatest concentration of energy known to man, a particle which contained roughly, as I have stated, 400,000,000 times the energy of the steam particle which does the work of the world.
As a result of that discovery, men began to wonder—since we have here a bullet, as it were, a particle which moves with this tremendous velocity—let's see if we could pound matter to pieces with it, and so we find Rutherford, for example, the great Canadian physicist, taking an element such as nitrogen and pounding it with the particle shot off from the sun, which was radium, with a velocity of 10,000 miles per second. Out of that grew a very interesting discovery; namely, that the nitrogen which we had theretofore thought of as an element would go to pieces and give off another element which we knew as hydrogen.
Our concepts began to get into difficulties. Then a very ingenious physicist by the name of C. T. R. Wilson conceived the notion of shooting these particles with this tremendous velocity through water vapor, under which conditions the water vapor would condense as a cloud and he could therefore follow its path. When he shot this alpha particle from radium through water vapor and photographed its pathway, he found that it would literally go through millions of particles of water as though nothing were present, and then it would suddenly be deviated as though it had struck something very hard and something very dense.
In other words, the path of the particle became something like the path of a high-speed automobile. It is going down the straightaway, and as long as everything is clear, all is well, and then suddenly if you find that happening (indicating) you know that something was hit where the angle of the pathway changes
New Atom Theory Evolved
That led to the question—what does this mean? Well, you can see it can't mean that the particles are like billiard balls. It can't mean that because we are shooting through millions of them without apparently being affected by them, so that gave rise to the notion that the atom must not be of billiard-ball-like structure, but perhaps it is something like the solar system with a central sun where most of the mass of the atom is located and which we called the nucleus, surrounded by planets similar to the planets which surround the sun.
That became the new kind of atom then that we began to deal with, and some chemists immediately became interested in these planetary particles, these electrons that occurred outside of the nucleus or the central sun. There were questions of arithmetic involved. How many planets did the different atoms have? There were questions of geometry involved. What kind of pathways do these particles follow? Do they go around in circles? Do they go around in elipses? Finally there was the question of the mechanics of these particles. Do they all stay in the same pathway, or do they jump from one path to another?
Discovery of Neutron
That became the kind of thing that chemists and physicists became interested in. Then we gradually turned our attention from the planetary structure of this miniature solar system back to that central sun or the nucleus. We began to make discoveries about its contents. We discovered, for example, that it contained in it a positively charged particle about the same weight as the hydrogen atom. We called that the proton, and then Chadwick in England, by bombarding an element called beryllium—which you will hear a lot about as time goes on—with this alpha particle, again from radium which is the shotgun of the physicist to knock things to pieces, discovered a particle which had no electrical charge and was therefore called the neutron.
The neutron then became a particle that began to be used by the physicist and the chemist. This particle had properties that were unique. Primarily the one we were interested in was that it had no charge. And why were we interested in that? Well, if you have the center of an atom which is positively charged, and you are shooting another positively charged particle at it, you can see what happens. You will again have forgotten from your elementary physics that positive charges repel each other with a force that varies directly as their charges, and inversely as the square of the distance.
In other words, the closer two positively charged particles come to each other, the greater is the repulsion between them. Therefore, if you attempt to shoot at this centra! sun or the nucleus of an atom which is positively charged, another positive particle, as it approaches the other, the repulsion becomes great, and probably it shoots off to one side.
This neutral particle, the neutron, had the advantage that we might shoot it at various atoms to see what would happen, and we would not have this repulsive force between the nucleus of the atom and this neutral particle which we call the neutron.
A number of workers began to use neutrons in their studies. Madame and Monsieur Joliot. the daughter and son-in-law of the great Madame and Pierre Curie, tried it on a number of elements and found that some elements which had heretofore been regarded as stable became unstable, became artificially, as it were, radioactive. Then a new kind of nuclear chemistry began to be born. It was an interesting kind of chemistry, but it was basically this: If you hit this nucleus, this central sun, with a small particle, it becomes unstable, and it gives smajl particles back. The energy involved in the liberated particle isn't any greater, if it is as great, as the energy that it took to drive the particle in.
Famous Italian Discovery
Professor Fermi, then at work in Italy, asked himself what would happen if you took this neutron, this neutral particle, and allowed it to hit one of the heaviest of our atoms; namely, uranium, which was already unstable, going to pieces spontaneously like radium. He tried the experiment. He found that there was a very definite increase in its radio-activity, in its instability, and for that discovery Fermi was given the Nobel Prize in physics.
Some German workers, one outstanding woman, Dr. Meitner, Hahn and Straussmann, examining this experiment of Fermi's, discovered that it involved something that was different from anything that had been heretofore discovered; namely, that when the neutron strikes the uranium atom, instead of giving off some small particle like the hydrogen particle or the helium particle, the uranium particle actually falls apart, goes to pieces, breaks up roughly in half, and the interesting thing was that when you added the weights of these fragments together, you didn't come out with the weight of the original uranium atom.
It is as though we have a sixteen-ounce loaf of bread, and we cut it in half. We weigh the two fragments, and instead of weighing sixteen ounces, they weigh thirteen ounces. Now, barring the possibility that some youngster stole a slice of bread, there is something wrong about that, isn't there? It ought to weigh sixteen ounces, but instead of that, it weighs, we will say, fifteen ounces.
What happened to that mass, that matter which was lost? Einstein years before, growing out of^some work that had been done on the electron in vacuum tubes, had come to the conclusion that if matter were destroyed, converted into energy, the energy which would be liberated when the matter would be destroyed would be given to you by this equation: that E—the energy—would be equal to M—the mass destroyed—multiplied by—and here is the amazing thing—the square of the velocity of light.
The velocity of light'is roughly 186,000 miles per second. When you square it, you See you get an enormous number. Therefore, even though the amount of matter destroyed might be small, when you multiply a small mass by the square of 186,000 miles per second, to keep it in these big units, the figure is enormous.
United States Gets Benefit of Foreign Experiments
When these German workers, Meitner particularly, saw that apparently in this experiment of Fermi's we had seen the actual destruction of matter, they realized, on the basis of the Einstein equation, the tremendous quantity of energy which must be liberated when that destruction takes place. Therefore, if you could make the mass destroy anything appreciable, the energy liberated would be tremendous.
You will remember, at that time Hitler was ruling the world or making a very brave attempt to. He made a number of mistakes. Among the great mistakes that he made was to persecute certain members of its population. Meitner went to Stockholm. She sent a telegram to Niels Bohr, who at that time was in this country, giving him the interpretation of the Fermi experiment.
That telegram probably caused more discussion than any telegram that has ever come across the sea because in that these scientists saw the possibilities of liberating the tremendous quantities of energy wrapped up in the atom, and immediately men began to speculate about this: What happens when the neutron strikes the uranium atom?
Well, as I told you, it falls apart, but something more than that happens. It liberates more neutrons. You can see that this is easily possible. One neutron strikes the uranium
atom. It goes to pieces and liberates more neutrons which might strike more uranium atoms which would fall apart, liberating tremendous quantities of energy, liberating more neutrons, and so the thing would go until you would have something of explosive violence.
When it looked, therefore, as though war were inevitable, a group of scientists in this country—two of whom were refugees from Hungary—went to President Roosevelt with an introduction from Dr. Einstein, saying that these men had something of the greatest importance to talk over with him. What they talked over with him was the possibility! of the creation of an atomic bomb which had to have the attention of the President for two reasons: First, if that discovery should be made by Germany, if Germany, the home of science and industry, were able to organize her forces so as to create an atomic bomb, then indeed it would be difficult to visualize how anybody could meet the German onslaught; and second, if such a bomb should be developed by our own scientists, we would possess one of the most powerful tools in modern warfare.
Permission was given to these men to go ahead and to investigate its possibilities. Now, the thing that I want to point out to you up to this stage in our discussion is that all that I have said up to this point is common knowledge to the whole world. As I have indicated to you, Germans first saw the significance of the Fermi experiment. Fermi was an Italian. Niels Bohr, with whom they communicated, is a Dane.
These notions are all written up, chain reaction so to speak, in the Russian journals, in the journals of the Swiss people, of the French, of the English, of the American, of the Japanese. It is common knowledge everywhere. As far as fundamental principles are concerned—and this is most important—as far as fundamental principles are concerned, they are now known to the entire scientific world. There is no secret as far as the fundamental principles of the atomic bomb are concerned.
The Atomic Bomb Takes Form
What became of our problem then at this point? It be came a problem of getting quantitative data. It became a problem of finding out under what conditions uranium would react with neutrons with such violence that this tremendous amount of energy is liberated. That became the problem then for these scientists. As you can readily see, it involved a number of things.
In the first place, at this stage in the game we recognized that one of the assumptions that we had made very early, namely, that all of the atoms of a given element have the same weight, was wrong, that the atoms differ slightly among themselves.
For example, it is as though you were to take 100,000 people in Chicago and weigh them and get their average weight and come out with—shall we say, to flatter us—150 pounds. Then you go out to Colorado, and you pick 100,000 people, and you determine their average weight, and you get 150 pounds. Since you do that all over the world, you say, "Well, all men weigh 150 pounds. That isn't true. . All men just average 150 pounds.
Uranium "235" Did It
It turns out these weights we have been determining were average weights. Uranium was made up of three kinds of atoms, 234, 235, 238. The question came up, what is the effect of this neutron on these three different kinds of uranium atoms? The 234 exists in such small quantities that we can neglect it. The 235 is less than one per cent of
the uranium. This turns out to be the one that goes to pieces when it is struck by the neutron. Obviously one method of making a bomb then is to separate out this less than one per cent of uranium 235, set up a series of conditions so that you will have a high concentration of neutrons striking a certain critical mass of uranium 235 so that the chain reaction takes place in a short time, which will give you the explosion.
How are you going to separate two things that way so close to one another as 235 and 238? You can't do it chemically because the chemistry of these atoms is identical. Whatever method of separation you use, it has to be based upon physical properties. You can immediately see some possibilities. We separate cream from skimmed milk by the centrifuge. Well, that was tried; the supercentrifuge. Don't ever think that they used a dairyman's apparatus, but in principle it is the same. It didn't work very well.
Then we know that gases that are made up of heavy particles move more slowly than gases made up of light particles. For example, the air particles in this room move with a velocity of roughly a quarter of a mile per second. Hydrogen moves with a velocity of a mile per second. It is easy to separate hydrogen from oxygen if you have them mixed as gases, just depending upon that fact.
What you do is set up a sort of a race track. I am sure that you would say that if School A has a bunch of kids that can run a mile a second, and School B has a bunch of kids that only run a quarter of a mile a second, it is easy to separate them. Let them run a race, and after awhile School A will be away out here (indicating), and School B away back here.
That is the way in principle they tried to do it. Only it turns out that the velocity varies inversely as the square root of the mass, and when you determine the difference in the rate at which a gas containing uranium 235 will move and that having 238 will move, it is very small.
In the first place, you have to find a gaseous compound of uranium. Well, that was known; it was well known. It is uranium hexafluoride. When you determine the difference in which the rate of the gaseous particle of U. 235 moves compared to 238, it turns out to be of the order of something like a few feet per second. You see then if you want to separate these particles from one another, you have to have a long race track. That was a part of the job.
By the so-called barrier methods, putting up a barrier, something like porous porcelain, let us say, in which the lighter particles would get through a little bit faster than the heavier particles—by having miles and miles and miles of that thing, you could gain something of a separation.
Another method that was tried was by the so-called electromagnetiC., and we will pass with that. That was developed by Lawrence, largely, out in California, and turned out to be a most successful method. The only trouble with it is that it yields only very, very small quantities of material.
University of Chicago Makes Important Discovery
This method of separating particles was well known before the war. In fact, it was this method that Dempster used when he discovered uranium 235, Dempster being the Professor of Physics at the University of Chicago, and I cannot help but stop for just a moment to say how little the world sometimes notices discoveries of tremendous importance. I am sure that when Dempster reported that he had found the uranium atom having a weight of 235 compared with the average one which was usually present, of 238, scientists were interested, but I am sure that if someone
had appeared at The Executives1 Club of Chicago and said, "Gentlemen, I just came to report to you that Dr. Dempster of the University of Chicago, using electromagnetic methods, has found that there is a particle of uranium which weighs 235 instead of 238," you would have said, "So what the hell!"
Well, the "what the hell" fell on Hiroshima and Nagasaki.
Having worked out methods of separating these two kinds of atoms, in the construction of a bomb, the first one which was used, was the question of getting enough 235 of high purity with the concentrated source of neutrons, details of which we are not privileged to give.
More Problems to Solve
Then the question became, what about 238? Well, it was found that when element 238 is struck by a neutron, it is converted into another element which is called neptunium, named after the planet Neptune because the planet Neptune was discovered in connection with the planet Uranus. It was found that this element goes to pieces in a few days, and forms another element which is called plu-tonium. The element plutonium turns out to be an element which is relatively stable. It goes to pieces in about 30,000 years, about half of it goes to pieces in that time, so for all practical purposes you can consider it stable.
This element plutonium, however, is interesting because it has the same properties as 235; that is, if it is struck by a neutron, it also goes to pieces, losing mass and liberating tremendous quantities of energy.
What became the problem them? The problem became one of setting up piles of uranium in such a way that neutrons would strike them and build the element plutonium. Now that turned out to be not as simple as one might think. It turned out that the neutron is going too fast and won't be captured, so you have to slow it down. It was slowed down by graphite and by heavy weights. The other interesting thing that turned up—and this apparently the Germans never knew-—is that impureness has a tremendous effect on those neutrons, capturing them and not allowing the uranium to capture them. Boron turns out to be one of the most vicious elements.
It was necessary to prepare graphite—graphite being used to slow down the neutron—that contained less than one part of boron in 500,000 parts of graphite in order to be successful in this project.
I think that all of you can realize that important as the basic work was, carried out at the University of Chicago and other places in the development of this bomb, that no one can give too much credit to industry which solved the gigantic problem of preparing chemicals in a state of purity heretofore known only in the laboratory in very small quantities, and yet industry was asked to deliver this high purity uranium and high purity graphite, not in dram lots, not in pound lots, but in ton lots, and American industry delivered it.
The problem then became one of setting up uranium in graphite sticks, the neutrons wandering around in the graphite sticks until their velocity was slowed to a critical velocity, captured by the uranium 238, converted into the element plutonium, and then the big problem of separating plutonium from the uranium. The amount of plutonium which is formed is practically infinitesimal in any given quantity of it, and yet that material was made—a man-made element—in pound lots. Again it took industry, working on a gigantic scale, to accomplish this result. You must remember that here we had a race going on.
Teamwork
Nobody knew what the Germans were doing. How far along were they? You couldn't leisurely work out in the laboratory a fundamental principle and then say, "Well, there are about four ways we can separate these isotropes. Let's try one, and if that doesn't work, let's try the other." We had to try all four of them at once. You couldn't take a chance on the Germans getting ahead of us. You couldn't wait until you had enough material accumulated so you could carry out a decent pilot plant experiment.
You first worked with infinitesimal quantities of material. You learned the properties of plutonium with quantities of material so small they defy description, and we built a pilot plant out near Stagg Field where this was tried out on a sort of semi-pilot scale. Then it was moved out to the outskirts of Chicago, and here again the Forest Preserve Commissioners made available some thousands acres of land and gave it the protection in order that this pilot plant might be utilized. Here again let me say that it was this team work, it was this cooperation between the citizens, people who made up the Commission of the Forest Preserve, recognizing what was involved here, that made this job possible
There were tremendous health hazards concerned in this project. Fluorine is one of the most poisonous elements known to man; plutonium is exceedingly poisonous. All of these radioactive substances are highly destructive of living tissue. We went to the Rockefeller Foundation and said, "We have to have a grant for a very secret project which we can't tell you anything about, but we have to have a lot of money in order to organize the health service., Here again this imagination of the American came into play. The Rockefeller Foundation said, "Here is your money. Tell us after a while what you did with it," and a health service was organized, and so efficiently was that carried out that as far as we know, not a single bit of damage has been done to any worker who worked on this project.
The Great Experiment
Then, of course, finally the great day came. I was down in Santa Fe the day after the bomb was tried out in that vicinity. I never want to play poker with Sam Allison or Enrico Fermi because, believe me, there wasn't a single thing on their faces that betrayed to me that they had the day before witnessed the destruction of matter in an explosion of such gigantic size that it defies description to measure it.
I was down there as a traveling salesman and I was trying to sign these boys up for the Institute of Nuclear Studies, and they are coming to Chicago. It might interest you to know that in the new Institute of Nuclear Studies and related institutes at the University of Chicago, you are going to have, without any question, the greatest concentration of scientific ability that is known any place in the world.
I have talked to the men who witnessed that explosion ; you have read about it in papers. It is difficult to imagine. Dr. Allison was six and a half miles away from the bomb. He had something to do with giving the time at which it was to explode. He was in a heavy cement dugout facing away from the bomb at six and a half miles distant. Dr. Allison told me that the light, the reflected light, which came into that cement dugout was the most intense light that he had ever witnessed—six and a half miles away.
The brilliance of this light, in Fermi's own words, was so great that Fermi, who was something like thirteen miles away, doesn't even remember the explosion, which gives you some idea of the intensity of the thing. Of course you have all read about that. The rest of the story we know.
Now We Must Have Peace or Die
Well, what are we going to do about it? It seems to me there are about three attitudes we can take. One is 1 that now that we possess the atomic bomb, we can take over! the world. We can say to Russia, "Surrender, or we'll bomb you." We know we are not going to do that.
The second is that we can say, "We have this secret; we shall keep it." But remember, all the fundamental principles of this bomb are well known, and even the most conservative of the scientists who have worked on the project] have said that Russia can do this in two to seven years with ease. She doesn't have to work as intensely as we worked. She doesn't have to try out four different things at once. She has the benefit of knowing that the thing will go, which we never had until it was tried.
That results in an armament race. That means that from here on out science devotes itself to greater and greater methods of destruction. Certainly we can't have that. It seems to me there is only one thing left; that is, some sort of international control of this weapon whose secrets must be known to all, and that our safety lies in our pledge to each other that we will learn to live in peace because surely the handwriting is on the wall. Unless we learn to live in peace, we shall surely die.
There is no security in secrecy. You cannot get scientists to work under conditions of secrecy indefinitely. Why? For the simple reason that science does not prosper under those conditions. If you set a group of scientists off by themselves to work and not even allow them to confer very much with one another and let the rest of the world have a free interplay of ideas, the progress made by the rest of the world will be so great, will outstrip the group of isolationists by such distances, that the imagination will never be able to describe it.
Possibilities of This New-Found Energy
You can't have secrecy. It isn't in the very nature of the problem, and then it seems to me there is something else here. Having succeeded in developing this weapon, what can we do with it? What can we do with this energy that we have learned to release in such a short period of time? Well, can it be used for power in general? There is no question about that.
And if any one of you people will give the University of Chicago from $50,000 to $100,000, we will have a place running for you by next April. Will it be economically possible, or will it be an economic adventure to do it? That is something that we cannot at the moment say. I would guess that the probabilities are that it will be, but that is a phase of the work which has yet to be done.
These various substances, elements that have been renered radio-active, may have great peacetime uses. Perhaps in these radiations we shall have the cure of cancer. Let's look at the cancer problem for just a minute. The cancer problem is an old one. A group of cells in some organism go on a rampage and divide without following any law. What is the cause of it? We know it isn't an organism | that is blocked out. The probabilities are that it isn't food.
In 1914 Yamagiwa and Ichikawa, two Japanese workers, showed us that if you paint coal tar on the skins of animals, they would develop tumors, and that gave us the notion that chemicals might be the cause of cancer. Then World War I came along, and all of that work stopped.
Then in about 1925 Kennawajr in England took up the problem and began to work on coal tar. He isolated a compound called benzpyrene. When this compound is applied
to the tissues of a living animal, it causes cancer. We now know some two hundred different chemical compounds which will produce cancer. We have every reason to believe it is a chemical disease.
Who is working on the problem? Wieland in Germany; Lacassagne in France; Kennaway fn England, a number of workers in the United States, and World War II came along—where are these workers? Wieland we don't hear from; Lacassagne we don't hear from; Kennaway in war work; workers in .this country in war work. Again the cancer problem is forgotten. Isn't the lesson of this tremendous success that we have had that if we will attack this problem with the same tenacity of purpose as we attacked the atomic bomb that there is no question' but what we will be successful?
People have asked, should the atomic bomb have been dropped. Let's remember the atomic bomb did not cause the war. It ended the war. We spent $2,000,000,000 on it, a lot of money; it cost that much money to run the war just nine days. If you shortened the war by just nine days, you are money ahead.
What is the difference whether you have a thousand planes carving ten-ton bombs with all the personnel necessary to manage a thousand planes dropping destruction on Hiroshima, or whether you risk the lives of one group of young men in one plane? When you are in war, you are in a dirty business. It doesn't make much difference how you do the killing, since victory depends on doing it effectively.
We have arrived at a stage in our discoveries where we have a weapon so terrible now that we cannot think of destruction any more without thinking of destroying ourselves. Let us here highly resolve that we shall learn to live in peace because if we don't make that resolve, and we don't live up to it, the echo will surely be* "Ye shall die."
Somebody who is a wisecracker said the other day, "Perhaps from here on we ought to say, 'I believe in one uranium atom, divisible, with oblivion for all.'"