HUMAN-CAUSED AND NATURAL FISSION
 

The actual breaking up of atomic nuclei is not a simple business. A physicist can’t snap an atomic nucleus apart as if it were a toy. Nuclear reactions must take place under special conditions, and the results are not as straightforward as the foregoing problems suggest. To split atomic nuclei in the laboratory, a particle accelerator is employed. This machine uses electric charges, magnetic fields, and other effects to hurl subatomic particles at extreme speeds at the nuclei of atoms to split them apart. The result is a fission reaction, often attended by the liberation of energy in various forms.
Some fission reactions occur spontaneously. Such a reaction can take place atom-by-atom over a long period of time, as is the case with the decay of radioactive minerals in the environment. The reaction can occur rapidly but under controlled conditions, as in a nuclear power plant. It can take place almost instantaneously and out of control, as in an atomic bomb when two sufficiently massive samples of certain radioactive materials are pressed together.