Maxwell James Clerk (1831–79), Scottish physicist who made pioneering contributions to the theory of electromagnetism, the kinetic theory of gases, and the theory of color vision. His work on electromagnetism is summarized in his Treatise on Electricity and Magnetism (1873). In 1871 he became Cambridge University’s first professor of experimental physics and founded the Cavendish Laboratory, which he directed until his death.
Maxwell’s most important achievements were his field theory of electromagnetism and the discovery of the equations that bear his name. The field theory unified the laws of electricity and magnetism, identified light as a transverse vibration of the electromagnetic ether, and predicted the existence of radio waves. The fact that Maxwell’s equations are Lorentz-invariant and contain the speed of light as a constant played a major role in the genesis of the special theory of relativity. He arrived at his theory by searching for a ‘consistent representation’ of the ether, i.e., a model of its inner workings consistent with the laws of mechanics. His search for a consistent representation was unsuccessful, but his papers used mechanical models and analogies to guide his thinking. Like Boltzmann, Maxwell advocated the heuristic value of model building.
Maxwell was also a pioneer in statistical physics. His derivation of the laws governing the macroscopic behavior of gases from assumptions about the random collisions of gas molecules led directly to Boltzmann’s transport equation and the statistical analysis of irreversibility. To show that the second law of thermodynamics is probabilistic, Maxwell imagined a ‘neat-fingered’ demon who could cause the entropy of a gas to decrease by separating the faster-moving gas molecules from the slower-moving ones.
See also PHILOSOPHY OF SCIENCE , RELATIV- IT. M.C.