How did William Thomson’s research influence James Clerk Maxwell’s electromagnetic theory of light?

William Thomson, Baron Kelvin, played a foundational role in the development of James Clerk Maxwell’s electromagnetic theory of light. When Maxwell began his research into electricity and magnetism, he studied all of Thomson’s papers on the subject and adopted him as a mentor.1

Thomson’s influence was rooted in his pioneering use of mathematical analogies to unify disparate areas of physics. Specifically, he established the mathematical relationship between the flow of heat in solids and the flow of electricity in conductors, a concept he applied to telegraphy. By demonstrating that mathematical techniques used for one form of energy could be applied to others, Thomson provided the framework for Maxwell’s own efforts to synthesize the known interrelationships between electricity, magnetism, and light.21

Maxwell’s monumental electromagnetic theory of light, widely considered the most significant scientific achievement of the 19th century, had its genesis in Thomson’s earlier work, a debt that Maxwell readily acknowledged.1