LEGENDS: James Clerk Maxwell:IMAGINE AN ENCLOSED system, with two chambers separated by a frictionless door – inside the chambers are molecules, some moving fast, some moving slow.
Now conceive of a being who can open and close the door, putting the fast, hot molecules in one chamber, and the slow, cold ones in the other. A simple task, one might think, but the creature is actually defying the second law of thermodynamics – composing order out of disorder, reversing entropy.
It might not seem like much of a life, but the creature, known as Maxwell’s Demon, was one of the most enduring creations of 19th-century Scottish scientist James Clerk Maxwell, a feat of scientific imagination that deserves to share a mythical laboratory with Erwin Schrödinger’s cat.
But no more than Schrödinger, his demon is just one part of his extraordinary scientific legacy, which includes groundbreaking work on electromagnetic theory, astronomy, colour perception, gas composition, thermodynamics and many others. His theory of electromagnetic fields was a foundation stone of all subsequent physics – the sobriquet “the father of modern physics” is well deserved. In the pantheon of great physicists, Maxwell is deservedly considered a peer of both Newton and Einstein – his innovations and tireless experimentation brought revelations that had previously barely been guessed at.
Maxwell was born in 1831 in Edinburgh; his father, a lawyer, adopted the name Maxwell after inheriting a rural estate called Glenlair – the double-barrelled surname denoted refinement even then, it would seem.
Maxwell was taught by his mother until her premature death when he was only eight. He displayed precocious intelligence from a young age, with his paper on the problem of drawing ovals being presented to the Edinburgh Royal Society when he was just 15.
After a few years in Edinburgh University, he enrolled at Trinity College, Cambridge, in 1850, studying mathematics. Immediately after graduating in 1854, with an inevitable first, he became a lecturer at Trinity, but accepted a position in Marischal College, Aberdeen, in 1856 to be closer to his ailing father.
While in Aberdeen, he applied his mathematical skills to many disparate problems – he won a prize for determining that Saturn’s rings were not solid or fluid, but rather a plane of separate particles on a planar orbit, a problem that had mystified astronomers and scientists for centuries, and one which he solved with mathematical precision.
Other projects focused on the colour spectrum – he had a lifelong interest in the topic, and in fact, he effectively took the world’s first colour photograph in 1861, mixing three exposures in red, green and blue. Fittingly, the photograph depicted a tartan ribbon. Also while in Aberdeen, he met and married Katherine Mary Dewar, whose father was the college principal – productive years indeed.
In 1860, he became chair of natural philosophy at King’s College London, where he concentrated on his most important work – his theory of electromagnetism. Maxwell had been investigating the work of Michael Faraday since the mid-1850s, and while in London he became acquainted with the venerable scientist, 40 years his senior.
Maxwell’s research on Faraday’s discoveries led him to speculate on the nature of electric and magnetic effects, and eventually discover a mathematical relationship between the two – they travel in waves, and at a constant speed. It was when he realised that the constant speed was the same as the speed of light that the importance of his work became clear – light itself, he would hypothesise, was an electromagnetic phenomenon.
Maxwell retired to Glenlair in 1865, and once back in Scotland, he was able to refine further his discoveries and hypotheses. His classic text, Treatise on Electricity and Magnetism,published in 1873, elaborated on his electromagnetic theory. This work was, in effect, a unified theory of physics – the second after Newton's. He also focused on a kinetic theory of gas, prompting his involvement in thermodynamics, refining the discoveries of Rudolf Clausius and independently formulating what came to be known as the Maxwell-Boltzmann kinetic theory of gases. It was while working on this theory that he envisioned his thought experiment and created his Demon, to show the loss of usable energy in a closed system is statistical – that "a being whose faculties are so sharpened that he can follow every molecule in its course" could counteract entropy.
His Demon might be the ideal information sorter, an impossible actor defying physics at the molecular level, but Maxwell himself was a variety of scientific information Demon; imperfect and human, certainly, but capable of remarkable feats of deduction, creating theories that have remained critical to physics and our understanding of the world. He died in 1879, of stomach cancer, at the age of 48.
