In 1922, when Einstein visited the University of Cambridge, he was told by his host that he had done great things because he stood on Newton’s shoulders; Einstein replied: “No I don’t. I stand on the shoulders of Maxwell”.

James Maxwell

James Clerk Maxwell was one of the most influential scientists of the 19th century. To him we owe one of the most significant discoveries of our age - the theory of electromagnetism. As Einstein rightly said, “The special theory of relativity owes its origins to Maxwell’s equations of the electromagnetic field.”

Maxwell’s interest in physics was a natural extension of his fascination with how things work, and his love for nature. At 14 he developed a new method of constructing some unusual geometric curves and the Edinburgh Royal Society declared “the simplicity and elegance of the method” worthy of publication in their proceedings. In his early 20s, Maxwell used Newton’s laws to mathematically prove that Saturn’s rings are not solid, as they appear through a telescope, but are made of many smaller bodies. His paper won him an award from the University of Cambridge.

Maxwell loved linguistics. He wrote numerous poems and lucid science articles. In 1860, he moved to London, after being granted the Chair of Natural Philosophy in King’s College. It was arguably the most productive period in his life. He was awarded the Royal Society’s Rumford Medal in 1860 for his work on chromatic photography and colour additivity. This period of his life would see him display the world’s first light-fast colour photograph, further develop his ideas on the viscosity of gases, and propose a system of defining physical quantities—now known as dimensional analysis. Maxwell would often attend lectures at the Royal Institution, where he came into regular contact with Michael Faraday.

In 1820, Oersted found that a compass needle brought near a current-carrying wire pointed at right angles to the direction of the current, which involved a twisting motion that could not be explained by any other force. Faraday sought to explain this by seeing the “lines of force”, revealed by sprinkling iron filings on a sheet of paper held over a magnet, not only as geometrical lines but also as physical lines explaining magnetic force.

Faraday used the term “field” to describe the space around magnets and currents, and he imagined the field as lines of force radiating from the electric and magnetic sources. However, most physicists believed “action at a distance” still applied. It was Maxwell who developed the mathematical description of various mechanical models to imagine how a field could transmit changing electromagnetic forces. Finally he found himself looking at the mathematical description of a transverse wave – the sort that travels along a plucked string, and realised that his purely electromagnetic wave had exactly the same signature as a light wave – the same form, the same speed.

In his 1865 paper, he announced with understated triumph: “We have strong reason to conclude that light itself (including radiant heat, and other radiation if any) is electromagnetic”.

More than just a new theory, it entailed revolutionary views of scientific explanation, unifying three different realms of physics – electricity, magnetism and light.

Happy birthday to James Maxwell, one of the greatest minds of all time, and whose discoveries paved the way for most of the technological advancements in the modern world.

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