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Botnst · #1 12-12-2006, 04:48 PM

James Clerk Maxwell: a force for physics

Feature: December 2006

Born 175 years ago, James Clerk Maxwell carried out the first profound unification of nature's forces. Francis Everitt examines the immense contributions of the greatest mathematical physicist since Newton

Unless one is a poet, a war hero or a rock star, it is a mistake to die young. James Clerk Maxwell – unlike Isaac Newton and Albert Einstein, the two giants of physics with whom he stands – made that mistake, dying in 1879 at the age of just 48. Physicists may be familiar with Maxwell, but most non-scientists, when they switch on their colour TVs or use their mobile phones, are unlikely to realize that he made such technology possible. After all, in 1864 he gave us "Maxwell's equations" – voted by Physics World readers as their favourite equations of all time – from which radio waves were predicted.
Deserving recognition
Deserving recognition

Suppose Maxwell had lived one year beyond the biblical three score and ten. He would then have been alive on 12 December 1901, the day when Guglielmo Marconi, in St John's, Newfoundland, received the first transatlantic radio signal from a transmitter in Cornwall, UK, designed by Maxwell's former student Ambrose Fleming. Or consider relativity: mention it and everyone thinks of Einstein. Yet it was Maxwell in 1877 who introduced the term into physics, and had noticed well before then how the interpretation of electromagnetic induction was different depending on whether one considers a magnet approaching a wire loop or a loop approaching a magnet. It was from these "asymmetries that do not appear to be inherent in the phenomena" that Einstein began his work on special relativity.

Had he not died so young, Maxwell would almost certainly have developed special relativity a decade or more before Einstein. Moreover, it was through reading Maxwell's article "Ether" in the ninth edition of the Encyclopaedia Britannica that Albert Michelson came to invent the interferometer – a new kind of instrument that he and Edward Morley used in 1887 to discover that the speed of light is the same in all directions.
A man for all science

So what impression of Maxwell would you have gained if you had met him in his prime, as a young Scottish undergraduate Donald MacAlister did in Cambridge in 1877? You would surely have been charmed, but perhaps also surprised to meet – as MacAlister put it – "a thorough old Scotch laird in ways and speech". As the proprietor of an 1800 acre Scottish estate, Maxwell had all the qualities of the better kind of Victorian country gentleman: cultivated, considerate of his tenants, active in local affairs, and an expert swimmer and horseman too.

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Maxwell's legacy

When Einstein visited Cambridge in the 1920s, someone remarked, "You have done great things but you stand on Newton's shoulders." His reply was, "No, I stand on Maxwell's shoulders."

He was correct, but much else in modern physics also rests on Maxwell. It was after all Maxwell who introduced the methods that underlie not only Maxwell–Boltzmann statistics but the quantum-mechanical Fermi–Dirac and Bose–Einstein statistics governing photons and electrons. It was even he, in two innocent-seeming discussions in the 1870s, who first emphasized what we now call the "butterfly effect" – the fact that tiny differences in initial conditions can produce huge final effects, the starting point of chaos theory. In a similar vein, Maxwell's scientific contributions have had dramatic effects on the future course of physics, notably the quest to unify nature's fundamental forces. Sadly Maxwell died of cancer on 5 November 1879 and never lived to see the applications of radio or the demystifying of equipartition. But the power of his scientific insights lives on.

A colourful tale

Few people will be aware that James Clerk Maxwell produced the first ever colour photograph (left, of a tartan ribbon). But Maxwell had a life-long interest in optics and colour vision, beginning in 1849 when the Edinburgh University physicist David James Forbes spun a top with three adjustable coloured sectors. Both men knew that red, blue and yellow are primary colours. However, no combination of those colours produced grey. (Thomas Young knew this years earlier but that fact had been forgotten.)

What was needed were red, blue and green. Improving Forbes' top, Maxwell determined "colour equations", which give quantitative measurements of the ability of the eye to match real colours. But since light conditions vary for different observers, Maxwell realized that a more sophisticated instrument than a top was needed, which led to him inventing an ingenious "colour box". With it, he and his wife carried out detailed measurements of the variations of colour register across the retina for hundreds of observers – an achievement unmatched until the 1920s. On 17 May 1861 Maxwell gave a lecture on colour at the Royal Institution in London, during which he projected through red, green and blue coloured filters three photographs of a tartan ribbon taken through the same filters. This first-ever colour photograph was a surprisingly faithful reproduction of the original.

At a Glance: James Clerk Maxwell

• James Clerk Maxwell was born 175 years ago, in recognition of which 2006 has been dubbed Maxwell Year
• A child prodigy, he studied at Edinburgh and Cambridge universities and was appointed professor at Marischal College, Aberdeen, 150 years ago, aged just 25
• In 1865 Maxwell wrote down his famous equations, which related – or "unified" – electricity, magnetism and light for the first time
• He played a key role in the development of statistical mechanics, paving the way for the development of quantum mechanics
• Maxwell was a cultivated man who could speak on almost any intellectual topic, yet he also took a keen interest in the local affairs of his Scottish estate

http://physicsweb.org/articles/world/19/12/2/1

mgburg · #2 12-13-2006, 10:30 PM

...what did Maxell die of?

Not the "silver hammer" method?