One of the world’s foremost nuclear physicists reviews the recent past in an attempt to answer the question, “Can we ban the testing of nuclear explosives?” This expression of his views, initially presented in an address to the Fordham College Alumni Association in New York earlier this year, continues the running discussion of this important issue that has appeared in these pages. Last month, an article by Earl Voss cautioned against a complete ban under present conditions.
Peace is a topic which is uppermost in all our minds. I have some special reasons to love peace, to seek peace, to do whatever I can, little though it may be, to make it more probable that peace will endure. I have come from a country which, when I was born, was a country free and growing and hopeful. It is no longer, largely due to a great extent to the ravages of two terrible wars.
I have a second reason. During the late 1930s and early 1940s and ever since, I have been involved in the development of a terrible system of weapons. We who have been so involved have to think about the consequences of our acts; not that it is given to any of us to control these consequences, but just in order to act with our eyes open.
Let us go back into the past—the days when the atomic project was born. They were the days after Munich. They were the days when the free nations disarmed. They were the days when honest, well-meaning, and idealistic people sought peace along the road which we now call appeasement. And in those days it became clear to the scientific world that there the possibility of developing a new source o power, of energy whose first manifestations probably, almost certainly, could be turned into destructive channels. None of us undertook this task without worry. That worry, that fearful thought about the future, has never left us.
In the way in which success is measured, we were successful. This was proved in the last days of World War II in terrible flashes over Japan. I do not intend to criticize those who made the decision to use the weapons. We were involved in a war, the ferocity of which most of us still remember. It was a war in which lives were snuffed out every day by the thousands. To stop this slaughter nothing seemed too terrible. But I had a regret then, and I have a regret now. It is that we used this terrible weapon without attempting to demonstrate it first, without giving the Japanese a chance, having been shown the weapon, to surrender.
This has turned the minds of many people even with greater intensity to this determination: Never let the priceless gift of peace leave us again. How shall we do it? What can we do about it? What have we done about it
I must now turn to the recent past and to the present because there is where our decisions must lie and there is where our present thoughts must be concentrated. Our government made a courageous decision. Remembering the dangers of appeasement, remembering Munich, knowing that any halt in the further development of arms, of nuclear arms, could have most serious consequences, we still decided to stop and sit down and talk it over with the Russians.
Can we ban the testing of nuclear explosives
One thing was clear in all these negotiations, and that is one thing about which I think there have been no serious disagreements in principle: one-sided disarmament, one-sided cessation of testing, makes no sense. If we disarm, it must be on an honest basis of complete mutual guarantees; it must be with the understanding that treaties are carried out. To do otherwise would endanger our safety and would debase the idea of the treaty itself. The beginning seemed auspicious. In the summer of 1958 experts from our country, Great Britain, and the Soviet Union met. They agreed that it is feasible to police an agreement to ban nuclear tests.
At this point we must go into some technical details. This matter has been discussed, has been presented, and has been often misrepresented. The facts are simple, and on the purely technical side there is in this country no disagreement about these facts, only possibly about their interpretation.
When the experts met in the summer of 1958, they agreed on a number of things. First, tests carried out in the atmosphere with an adequate control system can be checked in a reasonable manner. Second, tests carried out under water, at any depth of the ocean, likewise can be checked. At least there is a very good chance of detecting a violator, if not immediately, nevertheless in the course of time.
Then came a harder nut to crack. What about tests underground? Tests underground create earthquake-like motions which can be noticed for thousands of miles. They can be detected. But can they be identified? There are a great her of natural earthquakes. How do we tell nuclear tests from natural earthquakes? Many people say it is simple: Just make sensitive instruments. Today we have sensitive instruments, and we work to develop more sensitive ones. But the crust of our earth is a noisy medium, and to distinguish the real danger signal from the noise is not simple.
So far only one method has been proposed. Within certain limits we have the feeling that it is reliable. A nuclear explosion produces at first an outward push. The first signal which arises from such an explosion is a motion of the earth’s crust in a direction away from the point of detonation. By contrast, an earthquake usually is created by something like a slippage in the earth’s crust The result is that the first motion noticed from an earthquake appears in some seismographs as a push outward, but in others as a motion inward toward the source.
Therefore, if we have enough seismographs and if observation shows that all motions recorded by all seismographs are motions outward, this need not be a nuclear explosion, but it is suspicious. If some motions are outward, some are inward; it looks like an earthquake although it still might be a nuclear explosion. Actually it turns out that it is not so easy to notice this first motion. The first motion may be submerged into the general noise which prevails in the crust of the earth. The result is that only in case of big nuclear explosions or only in ease of very closely spaced earthquake stations, can we make the distinction in a reasonable way.
After the Geneva discussions in the summer or 1958 were concluded, there was agreement that underground explosions could be detected and identified if they were greater than five kilotons. It would still he necessary to inspect and to verify, but the hope was expressed that explosions about five kilotons could be brought under control. Remember, this is five thousand tons of TNT, one-quarter of the nuclear explosive which was dropped over Hiroshima. Below the level of five kilotons the probability of detection rapidly decreases, and below one kiloton the probability of detection no longer exists.
There was one other serious deficiency. Nuclear tests in interplanetary space were not dismissed at the conference.
Developments were rapid in the next few months. Immediately following the conference there was a windup phase of our nuclear tests in Nevada. At that time we augmented our sparse knowledge of underground nuclear explosions. We had conducted but one underground test. In the fall of 1958, we added to this experience half a dozen more shots. When these shots were analyzed it turned out that the conclusions of the summer conference of 1958 were too optimistic.
After we were through with our painstaking studies, every informed person in the United States and Great Britain agreed that nuclear explosions underground can be detected and identified if they are greater than twenty kilotons. This is the full force of the Hiroshima explosion. As we fall below that limit the efficacy of detection and identification rapidly decreases.
We told the Russians, but they dismissed the matter out of hand. In America then commenced a concerted investigation of our own with a view to improving the detection system. The question of improving the seismic net was carefully examined. It was found that with enough additional apparatus one could detect and identify explosions of ten kilotons or maybe somewhat less. Thorough work, by many excellent people, went into these studies.
An excellent contribution was made by a young man from the RAND Corporation in California at about this point. This piece of research showed a surprising thing. If you set off a nuclear explosive in the center of a big cavity underground, at appropriate depth, the apparent size of the explosion as recorded on monitoring devices may be only one-hundredth the actual magnitude.
Of course the size of this hole would have to be quite big for it to hide a big explosion. To hide a
hundred-kiloton explosion one can build a hole which is inconspicuous and at an expense which is not high compared to the usual cost of testing. It would be quite easy to make cavities which will hide one to twenty kilotons. At these lower yields the masking of the nuclear explosion is so complete that in practically all cases, at least for few kilotons, none of the seismic recording stations would even respond, much less be able to distinguish the explosion from an earthquake.
Having found that in underground testing we were too optimistic we looked also at the possibility of testing in space. The unanimous conclusion was that it is possible to test in space and it is possible to detect such tests in space. But the hiding of space testing would be practical and effective up to one-half of a megaton, up to 500 kilotons. Only if a test exceeds this size, is it possible to detect and identify nuclear tests which your adversary did not want you to see.
In all these discussions, we have made the assumption, if there was a doubt whether a certain instrument of detection could be developed or not, that the instrument of detection could be developed. We have been optimistic about detection. In spite of this, severe limitations have been found.
It was decided to submit our findings to our Russian colleagues, As far as space testing was concerned, this was done in June and July of last year. The Russians agreed. The conclusions were released in somewhat complicated terms. It takes expert reading to understand what the agreement of last July means. But it means that one can test in space and hide the test in space up to half a megaton.
Last November and December we submitted to the Russians the findings about the seismic situation. Our men who went to this conference were devoted to the cause of nuclear test cessation, as a first step toward controlled disarmament They presented facts; the Russians would not accept them. The Soviet delegation had no valid counterargument. They simply said: “These facts don’t help to make an agreement; therefore, why do you present them? They accused our people of ill will, of an intention to get out of the test agreement, which I am sure was the farthest from the minds of those particular individuals who devotedly sought for some way of banning nuclear tests.
This is the impasse at which we find ourselves today. We can say simply, surely, and clearly that if we agree on test cessation today, we have no way of knowing whether the Russians are testing or not. There are no technical methods to police a test ban.
What shall we do? I believe that the cause of peace has to be pursued. How? Where do the Russians stand? Not long ago Khrushchev announced a reduction of Russian manpower because he said he can rely on improved weapons. Can we under these conditions stop our technical development? Can we halt the development, that of nuclear weapons? About the importance of this development I shall say a little later as much as I can.
Khrushchev followed up his statement early this year about reducing manpower by boasting about a fantastic and new weapon. What is this fantastic weapon? There are many possibilities in the nuclear field and in many other fields. There are surely many possibilities of which none of us has thought. What chance is there for disarmament by inspection when we do not even know what the inspectors are to inspect
But we should proceed along the road to peace as far and as fast as we can. If we can bring about a relaxation of the present tension by concluding an agreement which can be reliably controlled, then the very success of such action may generate some good will, some little progress toward mutual confidence. I say that we can stop nuclear testing in the atmosphere. We may do this unilaterally. We can then challenge the Russians to follow suit even if they won’t sign a treaty. We shall know whether they have followed suit or not.
We can do more, and we should do more. We should increase our research to find methods by which to detect and control underground tests and tests in interplanetary space. We should use our plentiful resources. We should do it publicly, under international inspection, and indeed with international cooperation. When and if methods are found which will reliably check underground explosions or any other kind of explosions, we shall be ready to enter into a reasonable treaty concerning that particular kind of test.
In the meantime we must remember that we have already lost lime. The Russians may or may not have been testing in the last year. We do not know. We have no way of knowing. We could not have developed any new weapons, let alone a fantastic one, without tests. Was Khrushchev’s “fantastic” weapon a nuclear one? Was it tested? We don’t know. It is dangerous to add to our many other handicaps a self-imposed ban in a field in which we do not know whether the Russians are moving forward or not. By testing underground and by testing in space we can make the necessary progress in nuclear weapons.
I would like to state simply, categorically, and with complete assurance that such tests will not add to the radioactive contamination of the atmosphere. The danger from contamination by nuclear tests has been grossly and improperly exaggerated. For practical purposes this danger does not exist. Still, can we abstain completely and reliably from releasing radioactivity into the atmosphere by future weapons development? A very small amount of radioactivity might get into the air in the execution of some peaceful work, which I consider important, like building harbors or canals. This radioactivity would certainly be harmless.
But why should we be testing? Don’t we have enough nuclear weapons to destroy the world? Do we need to proceed farther along this destructive road? I want to say a few simple things about this point. There is a popular misconception that in 1945 we tested an atomic bomb, and we had it. And then in 1952 we tested a hydrogen bomb, and then we possessed that. And that’s all there was to the development. This is a gross distortion of facts.
Year by year we were involved in the development of this new explosive power. Year by year we learned something new and important. I do not like the word “nuclear tests,” because it implies one is merely checking a device of known properties. What we have actually performed were experiments with nuclear explosives, experiments the results of which we could not foretell. Often we learned much more by failure than by success. These experiments pointed the way into the future. Without such experiments all development soon would stop. But what is the purpose of further development
At this point I have to leave the purely technical ground. I would first like to say something with which many may disagree. I don’t like the idea of massive retaliation. There is a Biblical thought—an eye for an eye, and a tooth for a tooth, which has been often misinterpreted as demanding hard and cruel justice. I do not understand it that way. I learned that what this statement means is: You must never exceed the measure of justice. Justice may be and should be tempered by mercy. But never are you allowed to take more than an eye for an eye, or more than a tooth for a tooth. It is unjust: it is cruel: and in the international scene it contributes to fatal instability. If we are to respond to a smaller aggression by all-out destruction, we would in my opinion, be committing an immoral action.
But if this premise is believed, if we take the statement seriously, then we must look in a hard and realistic way into the kind of future that we will have to fare. There are two simple conclusions.
One is: What If we are hit by an all-out attack? Then and only then are we justified to hit back. But we must be so prepared that under those conditions we should have the power to hit back with certainty. This is not easy. If rockets take only fifteen or twenty minutes in flight how can we protect our ability to retaliate? Nuclear experiments can provide us with smaller, more handy, more flexible tools which can more easily survive even the hardest attack. With more nuclear experimentation we can establish a system of retaliatory power, with which we can be satisfied because we can say to the Russians, “We won’t hit you first, but if you hit us first, you cannot escape.”
Without nuclear experimentation the same thing can be accomplished on the basis of our present arsenal. But without further nuclear experimentation it will cost many billions of dollars more to accomplish the same objective, because more experimentation means smaller nuclear warheads, smaller rockets, smaller bases, more mobile systems, easier disposition, greater flexibility, greater assurance. These are important considerations at a time when our efforts are taxing us to a very considerable extent.
There is one other point: What about our allies? If we do not defend them by the threat of massive retaliation, are we to abandon them? Here is the vigorous and so far victorious Communist empire—ambitious, expanding, grasping for world domination. This empire is supreme in conventional weapons, enjoys a central location, and possesses an initiative unhampered by moral scruples. How can we hope to stand up against them without turning the free world into a military camp
By one way and by one way alone, and that is by being prepared with the best and most modern weapons. These are nuclear weapons. With nuclear weapons we can achieve not victory, but we can deprive the Russians of the advantage of the element of surprise. We can prevent them from concentrating overwhelming power against defenseless nations. We can impose upon their forces utmost dispersion and thereby give a chance to people who are willing to defend their freedom.
In this sense nuclear weapons can become and should become weapons of real defense. We have made progress along the line of developing defensive, tactical weapons. We could make and we know how to make much more progress along this line. We can defend the free world provided we remain prepared. In our rapidly advancing world, technology becomes obsolete in a few years. To remain satisfied with our past great accomplishments will certainly ensure our defeat. We must continue our work. This is a hard thing to accept at the time when everybody is looking and should be looking for peace.
There is always the big, and to my mind, unanswered question: Where will it all end? More power, more weapons—this cannot be peace. All we can buy with more weapons is time. What we shall do with this time will determine the future. This is no theoretical question; this is no question that can be relegated to the unknown and distant posterity, to the next generation; this is a question to solve now and here. How shall we use time? How shall we ensure peace? By the only logical method by which peace can be ensured, by the removal of the causes of war.
I believe that we need something desperately, something that may be impossible to get, something that may come close to a miracle if we get it. We need an international authority which wields moral power and which wields physical power. We need an international authority which commands the loyalty of every human being. We need it and we need it not only because the weapons are getting ever more dangerous. We need it also because our world is becoming smaller.
Let me make a last detour and tell you about a fantasy. I don’t think it will happen, but it might. And something similar to it is almost sure to happen. We are learning more about the ways to predict weather. We are on the threshold, as far as decades go at least, of discovering methods by which we might control weather. If one nation manipulates the weather it may cause a drought in the neighboring country. Our world has become so small that we have become our brothers’
keepers and even more serious to contemplate, our brothers are our keepers. We can no longer separate and compartmentalize the world. Are we ready for it
I offer no concrete plan. We need moral power and we need physical power in an international authority. We need an international police force, but how shall we get it? Shall it be a UN police force? Shall it be a police force constituted by some other means? I do not know; nobody knows. Nobody is clever enough to dream up a solution. We do not even know what are the right steps leading in that direction, and I claim that this problem cannot be solved except by the devoted and intelligent and selfless labors of all of us.
This brings me to the end of what I want to say. Peace is the aim of our time, but peace is not just the absence of war. Peace like everything else that is really important; like life itself, cannot be ensured, cannot be maintained, without the utmost exertion of all our abilities, all our imagination, without the renunciation of many things that we all hold dear; it cannot be ensured without sacrifices. Peace will not be ensured if we seek easy and simple-looking remedies Yet, in our often erroneous ways we all must look for peace.
There are many of my friends who are trying to find a road to peace in a way which is mistaken. There are many of my good friends who think that what I am here proposing myself is mistaken. I am sure that we all are right in saying this about each other. The question is so difficult that I am sure that in one way or another we all are mistaken, and we cannot do better than to face the facts honestly, to think clearly, and then with all our minds and with all our hearts, work for peace.