Clean, flexible and easily delivered weapons of all sizes would make it possible to use these bombs as we want to use them: as tools of defense. When stopping an aggressor we would not let loose great quantities of radioactive atoms which would spread death where we wanted to defend freedom. Clean nuclear weapons would be the same as conveniently packaged high explosives. They would be nothing more. The possibility of clean explosions opens up another development: the use of nuclear explosives for the purposes of peace. Conventional high explosives have been used in peace fully as much as in war. From mining to the building of dams there is a great variety of important jobs that dynamite has performed. Nuclear explosives have not been used in a similar way. The reason is the danger from radioactivity. Once we fully master the art of clean explosions peaceful applications will follow and another step will be made in controlling the forces of nature. All this is of course only a small part in the process of the increasing power of man and the increasing responsibility of man. As the impossible of yesterday becomes the accomplished fact of today we have to be more and more aware of our neighbors on this shrinking planet. The arts of peace may lead to conflicting interest as easily as they may lead to fruitful cooperation. If we ever learn to control the climate of the world, a nation may find itself in the same relation to another nation as two farmers who have to use the waters of the same river. Rivals are men who fight over the control of a river. When the same word “rivals” comes to mean cooperation for the best common use of the river or any other resource—that will be the time of law and of peace. Surely this sounds like Utopia and no one sees the way. But the general direction in which we should go is not to consider atomic explosives and radioactivity as the inventions of the devil. On the contrary, we must more fully explore all the consequences and possibilities that lie in nature, even when these possibilities seem frightening at first. In the end this is the way toward a better life. It may sound unusually optimistic in the atomic age, but we believe that the human race is tough and in the long run the human race is reasonable. GLOSSARY Activity: Short for radioactivity. Also the strength of a radioactive source measured in disintegrations per second. Air burst: A nuclear explosion at such an altitude that the fireball does not touch the earth’s surface. An air burst produces very little local fallout. Alpha ray (particle): Energetic but non-penetrating radiation emitted by heavy radioactive nuclei. An alpha particle consists of two neutrons and two protons, and is identical with the nucleus of the ordinary helium atom. Atom: A positively charged nucleus surrounded by negatively charged electrons. Atomic bomb: A fission bomb.