Maxwell's Equations — Unification of Electricity, Magnetism, and Light
James Clerk Maxwell, a Scottish physicist working at King's College London, published 'A Dynamical Theory of the Electromagnetic Field' in 1865. Building on the experimental work of Faraday (who discovered electromagnetic induction in 1831), Maxwell expressed the relationships between electric and magnetic fields in four elegant differential equations. The equations predicted that changing electric and magnetic fields would propagate through space as waves at the speed of light — proving that light itself was an electromagnetic wave. They also predicted the existence of electromagnetic radiation at other frequencies, which Heinrich Hertz confirmed experimentally in 1887–88 by producing radio waves in the laboratory. Maxwell's equations are regarded as the second great unification in physics (after Newton's) and Einstein described them as 'the most profound and most fruitful that physics has experienced since the time of Newton.' Their practical consequences are incalculable: radio, television, radar, mobile phones, wifi, and all electromagnetic technology rest on Maxwell's equations. Einstein's special relativity (1905) emerged from the realisation that Maxwell's equations are incompatible with Newtonian mechanics — Maxwell's theory was right and Newton's needed modification.
- Year: 1865 CE
- Category: Scientific
