James Clerk Maxwell is generally regarded as the greatest theoretical physicist of the 19th century. Born in Edinburgh to a well-known Scottish family, he entered the University of Edinburgh at age 15, around the time that he discovered an original method for drawing a perfect oval. Maxwell was appointed to his first professorship in 1856 at Aberdeen. This was the beginning of a career during which he would develop the electromagnetic theory of light and explanations of the nature of Saturn's rings and contribute to the kinetic theory of gases.
Maxwell's development of the electromagnetic theory of light took many years and began with the paper "On Faraday's Lines of Force," in which Maxwell expanded upon Faraday's theory that electric and magnetic effects result from force fields surrounding conductors and magnets. His next publication, "On Physical Lines of Force," included a series of papers explaining the known effects and the nature of electromagnetism.
Maxwell's other important contributions to theoretical physics were made in the area of the kinetic theory of gases. Here, he furthered the work of Rudolf Clausius, who in 1858 had shown that a gas must consist of molecules in constant motion colliding with one another and with the walls of the container. This resulted in Maxwell's distribution of molecular speeds in addition to important applications of the theory to viscosity, conduction of heat, and diffusion of gases.
Maxwell's successful interpretation of Faraday's concept of the electromagnetic field resulted in the field equation bearing Maxwell's name. Formidable mathematical ability combined with great insight enabled Maxwell to lead the way in the study of the two most important areas of physics at that time. Maxwell died of cancer before he was 50.