James Clerk Maxwell (1831-1879)
James Clerk Maxwell was one of the most influential scientists of the 19th century. His theoretical work on electromagnetism and light largely determined the direction that physics would take in the early 20th century. Indeed, according to Albert Einstein, “One scientific epoch ended and another began with James Clerk Maxwell.”
When he was born on June 13, 1831 in Edinburgh, Scotland, the scientist-to-be was only known as James Clerk, but the surname of Maxwell was added to his appellation when his father, an attorney, inherited an estate from ancestors with that name. Maxwell was an only child, and his mother died from cancer when he was 8 years old. A tutor was at first engaged to educate him, but then, in 1841, he was enrolled at the Edinburgh Academy. His interests were wide ranging, and at the age of 14 his first paper was published. The subject was geometry, and his skill in this and other mathematical spheres would aid him in his many scientific endeavors. Maxwell began studying at the University of Edinburgh in 1847 and published two more papers while still a teenager.
Maxwell transferred in 1850 to Cambridge University, where he was an exemplary student and won various awards, including the Smith’s Prize. He graduated in 1854 and accepted a Trinity College fellowship. As a fellow, Maxwell began research into two topics that he would investigate throughout his life: color and magnetism. This work resulted in the publication of two papers in 1855, “Experiments on Colour, as perceived by the Eye, with remarks on Colour-blindness” and “On Faraday’s Lines of Force.” That same year, Maxwell was elected a Fellow of the Royal Society of Edinburgh, and the following year he received an appointment as professor of natural philosophy at the University of Aberdeen’s Marischal College. His father, with whom he had been very close, died shortly before the appointment was made, and Maxwell inherited the family estate. In 1858, he married Katherine Mary Dewar, whom he met through a colleague at the college.
During his years at Aberdeen, Maxwell carried out research into a number of areas, but became particularly occupied with the nature of Saturn's rings, the subject of the Adams Prize of 1857. Deciding to compete for the prize, he spent two years attempting to find a way to accurately determine the composition of the rings. Eventually he theorized, using purely mathematical reasoning, that the rings could not be stable if they were comprised of a homogenous solid, leading him to conclude that the rings must be made of an unknown number of unconnected particles. Maxwell’s theory, finally proven a century later when the Voyager space probes were sent to Saturn, won him the prestigious prize. This research lead to more general inquiries into heat and the kinetics of gases. In 1859, Maxwell developed a statistical description of velocity distribution among the molecules comprising a gas, which would eventually be expanded into the Maxwell-Boltzmann distribution law.
Maxwell accepted a professorial position at King’s College, London in 1860. The five years he was associated with the institution are generally regarded as his most scientifically profitable. At this time, he applied his earlier studies of color vision and optics to photography, producing the world’s first color photograph in 1861. To do this he developed a trichromatic process, in which the same subject was photographed through red, blue and green color filters, and the three resulting images were combined into one. Also during his King’s College years, Maxwell continued his work with gases, which would culminate in his important treatise “On the Dynamical Theory of Gases” in 1867, and made groundbreaking advances in the area of electromagnetism.
It is for his electromagnetic theory that Maxwell is most commonly credited with fundamentally changing the course of physics. To arrive at his theory, Maxwell borrowed and extended ideas previously developed by several other scientists, including Michael Faraday, William Thomson (Lord Kelvin), and Carl Friedrich Gauss, among others. From his attempt to translate the experimental findings of Faraday into the language of mathematics, Maxwell arrived at a set of equations that comprehensively describe the production and the relationships between electric fields and magnetic fields. Based on the equations, simply known as Maxwell’s equations today, he was able to predict that waves of oscillating electric and magnetic fields travel in space at a particular speed, which he calculated was roughly equivalent to the speed of light (later, more accurate means of measurement confirmed exact equivalence). Subsequently, Maxwell theorized that light was just one of many possible types of electromagnetic radiation. Maxwell’s equations first appeared in 1864 in a paper entitled “A Dynamical Theory of the Electromagnetic Field,” but were more completely addressed in his Treatise on Electricity and Magnetism, published in 1873.
According to Maxwell’s theory (which, in its emphasis on fields, clearly opposed the theory of action at a distance that was popular at the time), electromagnetic waves should be able to be produced and studied in the laboratory. In fact, both infrared and ultraviolet radiation, which are just outside the visible electromagnetic spectrum, had already been discovered and investigated. However, it was not until William Heinrich Hertz discovered radio waves in 1887 that additional electromagnetic radiation even further outside the visible spectrum was proven to exist. In addition to anticipating this discovery, Maxwell’s theory greatly influenced the accepted understanding of the physical world and helped lead to Albert Einstein’s special theory of relativity and Max Planck’s quantum theory.
Maxwell resigned from King’s College in 1865 and relocated to the home in Scotland that been left to him by his father. He remained active in London academic circles, however, returning to England at least once every spring and continuing involvement in Cambridge University’s mathematical exams. Moreover, Maxwell continued his scientific work at home, completing much of his Treatise and penning works on gases, topology and heat theory during this time. He would become much more closely associated with Cambridge in 1871, when he was appointed the first Cavendish Professor of Physics at the institution. Included among his responsibilities in the new position were overseeing the foundation of the Cavendish Laboratory and editing the research papers of Henry Cavendish. Maxwell worked at the Cavendish Laboratory until 1879, when a bout with abdominal cancer, the same disease that had precipitated his mother’s death, rendered him too ill to continue. He died on November 5 of that year and was laid to rest in his native Scotland.