The next great source of energy will probably be nuclear reactors, in which controlled chain reactions release energy from the large store of fissionable materials in the world.[5]
The accomplishments of nuclear power in the propulsion of ships have already been noted. In addition, there is now going on in industrialized countries in different parts of the world a large-scale development of nuclear power plants for production of electricity. Nuclear electric power is approaching the point where it will be economically competitive with power from hydroelectric plants or those burning coal, oil, or gas as fuels. Improvements in nuclear power technology are rapidly being made, and it is now widely predicted that before the end of this century most new electric power plants will be nuclear.
Fusion Has Potential
One of the greatest puzzles to be solved by physicists arose from the work of geologists. When it became clear that coal and other fossil remains of living things date from many hundreds of millions of years ago, it was obvious that the earth’s sun had been shining at a quite steady rate for an extremely long time.
How does it manage to do it? What is its source of energy? Chemical energy supplied by combustion and gravitational potential energy supplied by contraction are thousands of times too small to have kept the sun going for such a long time.
The principle illustrated by [Figure 4] suggests the most probable source of energy for the sun and all the other stars as well. It is known that the sun consists chiefly of hydrogen and that it has a temperature of about 40,000,000 degrees Fahrenheit near its center. Several kinds of nuclear reactions produced in atom smashers have demonstrated that hydrogen nuclei, if energized by being heated to a very high temperature, can actually combine, or fuse, to form helium nuclei.
The accompanying loss of weight per particle indicated by [Figure 4] must result in the appearance of sufficient energy to balance Einstein’s famous equation. In fact, calculations by the German-born American physicist Hans A. Bethe and others show that, based on reasonable estimates of the conditions within the sun, familiar nuclear reactions account for its energy. The calculations predict, furthermore, that the sun can continue to operate at its present level for many billions of years.
Large loop prominences on the sun, caused by a locally intense magnetic field. Project Sherwood, the U. S. program in controlled fusion, is devoted to research on fusion reactions similar to those from which the sun derives its energy.
Courtesy Sacramento Peak Observatory, AFCRL
Since fusion of light nuclei is produced by extremely high temperatures, fusion events are called thermonuclear reactions. The possibility of bringing about thermonuclear reactions on earth to serve as a source of energy has naturally attracted much attention.