Complementing the coverage of pure physics topics, concise, general entries discuss interdisciplinary subjects, such as applied physics, astrophysics, biophysics, chemical physics, geophysics, and medical physics. Biographical entries present personal profiles of important physicists, past and present, and list their accomplishments. Details about their achievements are presented in separate, cross-referenced entries. While the emphasis is on the present state of physics, the science's historical background and development are explained, as appropriate, to give perspective on current issues in physics. With more than 600 entries, 11 prose essays on particularly interesting topics in physics, and more than 180 black-and-white photographs and line illustrations, this is an ideal reference to this core area of science.