On July 16, 1945, a plutonium bomb, carefully assembled by another group of scientists at “Project Y,” Los Alamos, New Mexico, was successfully tested in the New Mexico desert. The heat from that first man-made nuclear explosion completely vaporized a tall steel tower and melted several acres of surrounding surface sand. The flash of light was the brightest the earth had ever witnessed. A ²³⁵U bomb was dropped on Hiroshima, Japan, on August 6, 1945. Three days later a plutonium bomb was dropped on Nagasaki, Japan. Hostilities ended on August 14, 1945. Nuclear Energy Is Needed for the Future The chief source of the enormous quantities of energy used daily by modern civilization is fossil fuels in the form of coal, petroleum, and natural gas. Concentrated sources of these fuels, though large, are far from inexhaustible, and it has been said that future historians may refer to the brief time when they were used as “the fossil-fuel incident.” [Illustration: _These lights of downtown Pittsburgh are symbolic of the generation of electricity by atomic power from Shippingport, Pennsylvania, the site of the world’s first full-scale atomic-electric generation station exclusively for civilian needs. Homes and factories of the greater Pittsburgh area are receiving the electricity produced at the plant and transmitted through the Duquesne Light Company system. The Shippingport plant is a joint project of Westinghouse Electric Corporation, U. S. Atomic Energy Commission, and the Duquesne Light Company._ Courtesy Westinghouse Electric Corporation] 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.