Excerpt of Truman's comments on the Manhattan Project fromMemoirs by Harry S. Truman Volume 1: Year of Decisions

Published in 1955

In the late 1930s Austrian and German physicists (scientists who study matter and forces) made major breakthroughs in the field of nuclear energy, the energy released during nuclear reactions. The term "nuclear" refers to the nucleus, or core, of an atom. Atoms, the building blocks of all elements, are held together by incredibly powerful forces.

Nuclear energy research in the early World War II era centered on experiments with uranium atoms. Firing just one neutron (an uncharged particle found within the nucleus of most atoms) at the nucleus of a uranium atom caused the release of three new neutrons and a large amount of energy. Physicists believed that bombarding a larger sample of uranium with neutrons would trigger a powerful chain reaction: an...