After he completes his formal education, the scientist sets about to investigate the world, for that’s what science is all about. The methods he uses to carry out his investigations depend on his particular field. It is impossible to outline what an individual scientist does because he may do any of a thousand things in any of a thousand ways. He may be concerned with nuclear energy almost totally, or he may be concerned with it only slightly. It is possible, however, to sketch examples of some of the activities undertaken by various members of the scientific community. Most people are familiar with the broad academic breakdown of the sciences into physics, chemistry, biology, geology, engineering, and mathematics. It is therefore convenient to examine the activities of scientific personnel in each of these areas, as well as medicine, with emphasis on the nuclear energy aspects of each. Physics The physicist is dedicated to investigating the laws that govern the universe. He explores gravity, motion, mass, energy, and the myriad interrelated ways that the world is constructed to gain an understanding of his physical surroundings. [Illustration: The very tiny world of the atom is invaded by very large tools such as particle accelerators, sometimes called “atom smashers.”] A nuclear physicist concentrates his investigations on the atom. The subject of his research is, of course, incredibly tiny, and therefore invisible to him, but he studies the atom by finding out how it behaves when certain things are done to it. To accomplish this, the nuclear physicist centers his day-to-day activities around equipment such as particle accelerators and nuclear reactors, which he uses to shoot nuclear particles into materials. What happens in these and many other processes provides him with information on the nature and behavior of atomic energy. Within the framework of his interest, the practicing nuclear physicist may conduct basic or theoretical research to add to the body of scientific knowledge. He may design equipment to carry out new types of research. He may apply the principles of his science to improving the standard of living, as he did by developing the nuclear-power plants. He may work to improve nuclear weapons, to aid space travel, or to devise nuclear medical instrumentation for use by physicians. He has a place in one of the countless efforts that involve nuclear reactions and radioactivity. Chemistry The chemist studies the composition of substances. For centuries man has known that various combinations and recombinations of substances produce other materials with different properties, and it is the chemist who combines and recombines. A nuclear chemist, or radiochemist, specializes just as his name implies. He studies the effects of radiation on chemical substances, notes how chemical reactions are altered by the introduction of radioactivity, and analyzes the nature of nuclear energy materials and products.