Overview

Although the concept of the atom dates back to ancient Greece and the scientist/philosopher Democritus (c. 460-370 B.C.) who defined atoms as matter "unable to be cut," and since English scientist John Dalton's (1766-1844) articulation of atomic theory in 1803, the concept that matter consists of atoms and that atoms, in turn, are composed of smaller, subatomic particles has become an evolving but fundamental postulate of physical science. In the later half of the twentieth century as physicists explored the composition and properties of subatomic world, the impact of discoveries regarding subatomic particles bounded into the vastness of cosmological theory.

Background

The elegant simplicity of the indivisible atom was first shaken in the 1890s with English physicist J. J. Thomson's (1856-1940) discovery of the electron. Because electrons are negatively charged and atoms...