Frequency, theorem and formula: remembering Joseph Larmor in electromagnetic theory

Joseph Larmor (1857-1942) was one of the most distinguished British mathematical physicists of the late-nineteenth century. He introduced both the electron and the so-called Lorentz transformations into physics. His book of 1900, Aether and Matter, l helped to establish a research school that guided the development of mathematical electromagnetic theory in Cambridge until the end of World War I. Today, however, Larmor is widely remembered by scientists for just two formulae and one theorem which, although correctly attributed to him, have been seen by historians of science as tangential to his main research interests. Indeed, none of the recent scholarly studies of Larmor’s scientific work even mention the now famous formulae and theorem. In this essay I review Larmor’s contribution to post-Maxwellian electromagnetic theory and explain the origin of the specific results upon which his reputation now rests.