James Clerk Maxwell Biography

World of Scientific Discovery on James Clerk Maxwell

James Clerk Maxwell is to electromagnetism what Isaac Newton is to gravity. Born on November 13, 1831, in Edinburgh, Scotland, Maxwell was the only son of a well-to-do family. He showed a brilliance for mathematics at an early age and, at fourteen, had a paper on geometry read at the University of Edinburgh. This, unfortunately, set him apart from his peers, who nicknamed him "Daffy." Maxwell was nonplussed; two years later, in 1847, he was attending lectures at the university, and in 1850, he entered Cambridge University, where he excelled. Six years later, he was back in Scotland and was appointed professor at Aberdeen University.

Maxwell began making contributions to science as early as the age of eighteen. In 1849, he resurrected a theory of Thomas Young regarding color vision and advanced the work of Hermann von Helmholtz. Young believed the eye had three types of receptors that were sensitive to three primary colors of light. Maxwell showed how any colors of the rainbow could be created by adding or subtracting the three primary colors of light: red, green, and blue. In 1861, he used his knowledge to make the first color photograph.

Maxwell's first major contribution to science related to the nature of the rings of Saturn. To Christiaan Huygens, who discovered them, the rings looked like a flat disc encircling the planet, but controversy regarding their composition had lasted well over a century. In 1857, Maxwell suggested that they were not solid or liquid; if either were the case, they would break up due to mechanical forces. However, he added, if they were composed of tiny particles, as Gian Dominico Cassini had guessed 150 years earlier, they would be stable.

Three years later, Maxwell turned his attention to the tiny particles of which gases are composed. That gases were composed of molecules in constant motion was not in question; how they moved was. Using his mathematical background, Maxwell concluded that the molecules in a given gas do not all travel at the same speed. By applying statistical concepts to show that the speeds of the molecules were random and related to probability theory, he became the father of statistical mechanics. His kinetic theory of gases showed that the motion of molecules was responsible for the production of heat; when the average velocity increased, so did temperature. This silenced the notion that heat was a kind of fluid.

It was with considerable reluctance that Maxwell agreed to be appointed professor of experimental physics at Cambridge in 1871, for he lacked sound teaching skills. On the plus side, he established the Cavendish Laboratory, named for the English scientist Henry Cavendish, which would make a great contribution to the study of radioactivity.

Between the years of 1864 and 1873, Maxwell made his greatest contribution to science--he devised equations that unified electrical and magnetic phenomena. In 1855-1856, he published his paper "On Faraday's Lines of Force." English physicist Michael Faraday had used iron filings to show magnetic lines of force above a magnet. Later he discovered that an electric current flowing in a wire caused "lines of force" to expand outward, inducing an electric flow in an intervening wire. Obviously, there was some kind of connection between electricity and magnetism; it just needed to be defined. Using a few simple equations, Maxwell proved that magnetism and electricity were distinctly related. His theory linking the two forces became known as the electromagnetic theory.

Maxwell discovered that the oscillation of an electric current would produce a magnetic field that expanded outward at a constant speed. By taking the ratio of the units of magnetic phenomena to the units of electrical phenomena, it was possible to calculate the speed of expansion. The calculation came out to around 186,300 miles (300,000 km) per second, nearly the speed of light. Maxwell couldn't believe that this was just coincidental; he theorized that light itself was a form of electromagnetic radiation that traveled in waves. Since electric charges could be made to oscillate at many velocities, there should be a corresponding number of electromagnetic radiations. Therefore, visible light would be just a small part of the electromagnetic spectrum.

It was already known that there were wavelengths of light beyond those visible to the human eye. In 1800, William Herschel had discovered infrared (IR) wavelengths; ultraviolet (UV) wavelengths had been discovered by Johann Ritter. George Gabriel Stokes (1819-1903) had shown that UV light behaved just like visible light; Macedonio Melloni (1798-1854) had done the same with infrared. What made Maxwell's theory remarkable was the prediction of electromagnetic radiation, of which no one had even dreamed; wavelengths below infrared (where radar and radio waves are found) and above ultraviolet (the location of x-rays and gamma rays). Interestingly, Heinrich Rudolph Hertz, who discovered radio waves in the 1880s, thereby confirming Maxwell's theory, had become interested in electromagnetism because of Maxwell's original equations.

As brilliant as he was, Maxwell was not infallible. The laws of electrolysis that had been established by Faraday indicated that electricity had a particulate nature. Maxwell did not agree; had he lived a little longer, he would have seen the confirmation of Faraday's laws. It was proven that electricity did consist of particles, but that had no bearing on Maxwell's equations. In addition, Maxwell accepted the concept that an invisible "ether" existed everywhere, and he believed that magnetic lines of force were due to disturbances in the ether. Later experimentation by Albert Abraham Michelson and Edward Morley disproved the concept of ether, but Maxwell's equations remained valid, regardless of whether or not the ether existed.

On November 5, 1879, just eight days before his 48th birthday, Maxwell died in Cambridge of cancer. Toward the end of his short life, he saw to the publication of the electrical experiments of Henry Cavendish, showing that Cavendish was a good fifty years ahead of his time. Maxwell also became an early, ardent supporter of American theoretical physicist and chemist Josiah Willard Gibbs, who was one of the founders of statistical mechanics.

Perhaps the greatest confirmation of Maxwell's equations came about following the work of Albert Einstein. Einstein managed to overturn nearly all of the principles of classical physics, yet Maxwell's equations remained unchanged.