Overview

When Albert Einstein was asked if he had stood on the shoulders of Isaac Newton, he replied, “No, I stand on Maxwell’s shoulders.” Between 1855 and 1873, Maxwell stitched together the previously separate sciences of electricity and magnetism into a single tapestry—electromagnetic theory—showing that visible light itself is an undulating electric and magnetic field travelling at 299 792 458 m/s. The four compact Maxwell’s equations (first published in their modern vector form by Oliver Heaviside in 1885) are literally written on the back of T-shirts today, yet they contain everything needed to design radar, fibre-optic networks, microwave ovens and the Large Hadron Collider.

Maxwell did not stop at electromagnetism. While puzzling over Saturn’s rings he invented dimensional analysis, founded the modern kinetic theory of gases, introduced Maxwell–Boltzmann statistics, and demonstrated that the temperature of a body is nothing more than the average kinetic energy of its molecules. His 1861 paper “On Physical Lines of Force” even contained the first colour photograph—a tartan ribbon made by the three-colour method he invented, projected in London on 17 May 1861.

Background

James Clerk Maxwell was born on 13 June 1833 at 14 India Street, Edinburgh, into an aristocratic Scottish land-owning family. His mother, Frances Cay, died of abdominal cancer when he was eight; his father, John Clerk Maxwell, a lawyer and amateur inventor, raised him on the 1 500-acre estate of Glenlair in Galloway. Young James’s first scientific memory was tracing the patterns of light on a wall and asking, “Why are they so?“ At ten he was reciting the 119th psalm in Latin and building mechanical contraptions from gutta-percha and tin plate.

At 16 he entered the University of Edinburgh, publishing his first paper—“On the Description of Oval Curves”—at 18. In 1850 he migrated to Cambridge, graduating in 1854 as Second Wrangler (beaten by Edward Routh) but winning the far more demanding Smith’s Prize. Maxwell’s tutor, William Hopkins, said, “It is not possible for that man to think incorrectly on any physical subject.“

Key Facts

- 1855 (age 24): “On Faraday’s Lines of Force” translates Michael Faraday’s intuitive field lines into mathematical form. - 1859 (age 28): Derives the Maxwell distribution of molecular speeds, predicting that viscosity is independent of density—confirmed by himself and his wife Katherine in a decade-long series of rotating-cylinder experiments in the attic of Glenlair. - 1861–62 (age 28–29): Calculates that electromagnetic disturbances propagate at 310 740 000 m/s—within 3 % of the speed of light—leading to the immortal sentence: “We can scarcely avoid the inference that light consists in the transverse undulations of the same medium which is the cause of electric and magnetic phenomena.“ - 1865 (age 32): “A Dynamical Theory of the Electromagnetic Field” (Phil. Trans. R. Soc.) contains the 20 equations in 20 variables that Heaviside later compressed into the four vector equations we call Maxwell’s equations. - 1871 (age 38): Appointed first Cavendish Professor of Physics at Cambridge; designs and supervises construction of the Cavendish Laboratory, opened 16 June 1874. - 1873 (age 40): Publishes Treatise on Electricity and Magnetism, 1 000 pages that become the Principia of electromagnetism. - 1879 (age 48): Dies of abdominal cancer on 5 November at Cambridge, the same disease that had killed his mother.

Impact

Maxwell’s unification was the second great pillar of physics after Newton’s gravity; Einstein’s relativity and quantum electrodynamics both sprang from attempts to reconcile Maxwell with mechanics. Heinrich Hertz’s 1887 radio waves, Guglielmo Marconi’s trans-Atlantic transmission (1901), and every smartphone antenna are direct technological descendants. In 1931, on the centenary of Maxwell’s birth, Einstein wrote: “Before Maxwell people conceived physical reality as material points. Since Maxwell they have to take into account the electromagnetic field, which is something entirely different.“ Meanwhile, Maxwell’s 1872 Theory of Heat introduced the Maxwell’s demon thought-experiment that still fuels quantum information and thermodynamics today.