Can You Name the Two People Who First Revolutionized Physics?tags: books, Physics
Basil Mahon is the author of "The Man Who Changed Everything: the Life of James Clerk Maxwell" (Wiley, 2003) and "Oliver Heaviside: Maverick Mastermind of Electricity" (IET, 2009), among other publications. With degrees in engineering and statistics, Mahon was formerly an officer in the Royal Electrical and Mechanical Engineers and until his retirement worked for the British Government Statistical Service
What will future historians, thousands of years from now, judge to be the most significant event of the nineteenth century? Nobel laureate Richard Feynman had no doubt that their choice will be James Clerk Maxwell’s discovery of the electromagnetic field. Feynman was an ardent physicist who enjoyed making provocative statements, and present-day historians might question his judgement in the matter. Nevertheless, the basis of his point is incontestable: Maxwell’s discovery (which was actually made possible by the earlier work of Michael Faraday) has had a momentous impact on human life.
Today we take the electromagnetic field for granted. We use it whenever we turn on a radio or television, make a call on a cell phone, or travel in a radar-guided aircraft. It’s hard for us to imagine living in a world where such things don’t exist, yet we rarely give thought to the two men who made them possible. By bringing the entirely new concept of the electromagnetic field into human knowledge Faraday and Maxwell have transformed our everyday lives. Still more significantly, they have changed the way that scientists think about the physical world. The story of their achievement deserves to be more widely known.
Michael Faraday was born in 1791. Son of a poor London blacksmith, he had only rudimentary schooling but took advantage of an apprenticeship with a bookbinder to read all the books on scientific topics that came into the shop and managed to get a humble job, designated “fag and scrub,” at the Royal Institution in London, where he rose to become the country’s foremost experimental scientist. In the course of an epic series of experiments, he discovered the principles of the electric motor and the dynamo, and began to form his own theory on why electricity and magnetism behaved as they did. He believed that electric and magnetic “lines of force” existed in space, but the idea was ridiculed by many of his contemporaries. Much as they admired Faraday’s experimental genius, they thought him ill-equipped to theorize because he knew no mathematics. Moreover, his ideas were heretical. Since Newton’s time, scientists had believed that only material bodies held energy and inflicted forces, and that the intervening space was nothing more than a passive backdrop.
It took another genius to show that Faraday’s extraordinary idea was correct: space itself held energy and transmitted forces. James Clerk Maxwell was born 40 years after Faraday and his upbringing could hardly have been more different. The son of a Scottish laird, he studied first at Edinburgh University and then at Cambridge, where he came second in the famous Mathematical Tripos exam. In an astonishing and short career (he died at age 48), Maxwell made fundamental discoveries in every branch of physics he turned his hand to - he even took the world’s first color photograph - but, as with Faraday, his greatest work was in electricity and magnetism.
To Maxwell, Faraday’s ideas about lines of force rang true. He set out to express them in mathematical terms and in three stages, spread over nine years, succeeded. By drawing analogies with imaginary mechanical models, first of fluid flow and then of tiny spinning cells interspaced with even smaller particles like ball-bearings, he showed not only that all the known properties of electricity and magnetism could be derived mathematically from Faraday’s ideas but also that every time an electric current was turned on or off a wave of electromagnetic energy would spread out through space at the speed of light. Finally, he dispensed with the models and derived all the equations, including the wave equation, using only the laws of dynamics. Faraday’s lines of electric and magnetic force had become the electromagnetic field.
Maxwell had united electricity, magnetism and light, a stupendous achievement. But his theory was so different from anything that had gone before that most of his contemporaries simply didn’t know what to make of it. Others actively opposed it: even his friend William Thomson (Lord Kelvin) remarked that Maxwell had “lapsed into mysticism.” Up to the time Maxwell died in 1879 and for some years afterwards, nobody else really understood his theory. For a while it sat like an exhibit in a glass case, admired by some but out of reach. Then, in 1885, a self-taught former telegraph operator called Oliver Heaviside made it accessible by condensing Maxwell’s expansive theory into the four now-famous equations that we now call Maxwell’s equations. Three years later the German physicist Heinrich Hertz emphatically verified the theory by producing and detecting the electromagnetic waves that Maxwell had predicted, and the world began to change. Wireless telegraphy came, then radio, television, radar, satellite navigation, and the other wonders of modern communication.
The most profound change, however, has been in the way scientists think of physical reality. Beneath what we think of as the “real” world of things we can touch or see lies another. This is the world of field quantities that are inaccessible to our senses. They form a deeper reality - they exist in space and time, and give rise to all the familiar forces that we experience - but we have no way of perceiving them directly. All we can do is represent them by abstract symbols in equations and describe their properties using mathematics.
Faraday and Maxwell’s theory of the electromagnetic field opened the door to vast new regions of scientific knowledge, from Einstein’s special theory of relativity to the Standard Model of particle physics. Its story, set in the society of nineteenth century Britain, has great scientific and historic significance but is also a remarkable tale of human endeavor, not only by Faraday and Maxwell but by a diverse set of supporting characters, including the American rake, Benjamin Thompson, who was instrumental in founding the Royal Institution, the brilliant but vain Humphry Davy, who was Faraday’s inspiring mentor, and the diligent but unlucky Oliver Lodge, who produced electromagnetic waves in his laboratory but found he had been scooped by Heinrich Hertz. Above all, it is the story of two modest and genial men of genius who formed an extraordinary cross-generational bond and changed the world.
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