Finally the cloud has gained its full height. Depending on the size of the bomb it may have grown to 20,000 feet, to 100,000 feet or more. Then the wind blowing at various levels in various directions tears the structure apart sweeping some of it to the east, some to the west. The radioactive debris in the cloud has started on its travel. What this radioactivity will do, how it can affect living beings, how dangerous it actually is, we shall discuss in succeeding chapters. But one thing is clear and remains present in the minds of all participants in an atomic test: The danger of the test is nothing compared to the catastrophe that may occur if great numbers of these weapons should be used in an unrestricted nuclear war. It has been frequently asserted that our present atomic explosives can wipe out the cities and industries of the greatest countries. Why continue with further development and testing? The answer is simple: The main purpose of a war is not to destroy the enemy’s civilian centers but rather to defeat his armed forces, and for this purpose we need flexible refined weapons of all kinds and sizes. We also need weapons with which to defend our own cities. We need weapons with which to defend our allies and in particular we need weapons which will do their job against an aggressor and will do the least possible damage to the innocent bystander. In this last respect, in particular, notable progress has been made. We are developing clean weapons which are effective by their blast and their heat, but which produce little radioactivity. Of course, blast and heat will do damage only near the point of detonation. Radioactivity may be carried by the winds and escape the control of man to a considerable extent. It is clear that war is and always has been terrible. We refuse to believe that wars will always be with us but we cannot disregard the danger of war as long as the world is half free and half slave. An atomic war, limited or even unlimited, need not be connected with more suffering than past wars. However, such a war would probably be more violent and it would be shorter. The story is told that a war which turned out to be perhaps the most dreadful in the history of mankind was started with this message: “Thou hast chosen war. That will happen which will happen and what is to be we know not. God alone knows.” Perhaps the only possible path for a free people is to be well prepared for war but never to choose war as long as the choice is free. But what will happen God alone knows. CHAPTER X The Radioactive Cloud