Physicists biographies

Maxwell, James (1831-1879) Scottish mathematician and physicist who published physical and mathematical theories of the electromagnetic field. When he first became interested in electricity, he wrote Kelvin asking how best to proceed. Kelvin recommended that Maxwell read the published works in the order Faraday, Kelvin, Ampere, and then the German physicists. Maxwell wanted to present electricity in its most simple form. He started out by writing a paper entitled "On Faraday's Lines of Force" (1856), in which he translated Faraday's theories into mathematical form, presenting the lines of force as imaginary tubes containing an incompressible fluid. He then published "On Physical Lines of Force" (1861) in which he treated the lines of force as real entities, based on the movement of iron filings in a magnetic field and using the analogy of an idle wheel. He also presented a derivation that light consists of transverse undulations of the same medium which is the cause of electric and magnetic phenomena. Finally, he published a purely mathematical theory in "On a Dynamical Theory of the Electromagnetic Field" (1865).

Maxwell's formulation of electricity and magnetism was published in A Treatise on Electricity and Magnetism (1873), which included the formulas today known as the Maxwell equations. Maxwell also showed that these equation implicitly required the existence of electromagnetic waves traveling at the speed of light. He also proposed a physical theory of ether. He abandoned attempts to formulate a specific mechanical model, instead using the formalism of Lagrangian mechanics.

With Clausius, he developed the kinetic theory of gases. In "Illustrations of the Dynamical Theory of Gases" (1860), he showed the velocity distribution of molecules was "Maxwellian ." His studies of kinetic theory led him to propose the Maxwell's demon paradox in a 1867 letter to Tait. Maxwell's demon (termed a "finite being" by Maxwell) is a tiny hypothetical creature that can see individual molecules. He can make heat flow from a cold body to a hot one by opening a door whenever a molecule with above average kinetic energy approaches from the cold body, or below average kinetic energy approaches from the hot body, then quickly closing it. This process appears to violate the second law of thermodynamics, but was used by Maxwell to show that the second law of thermodynamics is a statistical law describing the properties of a large number of particles. Maxwell also observed in private correspondence that the time reversal of all events was consistent with the laws of dynamics, but inconsistent with the Second Law of Thermodynamics. Maxwell published his views on the limitations of the Second Law in Theory of Heat (1871).

Maxwell made numerous other contributions to the advancement of science. He argued that the rings of Saturn were small individual particles, performed experiments which showed the viscosity varied directly with temperature, derived the equipartition theorem, and tried to describe spectral lines using a vibrational model.

Maxwell left King's College, London in the spring of 1865 and returned to his Scottish estate Glenlair. He made periodic trips to Cambridge and, rather reluctantly, accepted an offer from Cambridge to be the first Cavendish Professor of Physics in 1871. He designed the Cavendish laboratory and helped set it up. The Laboratory was formally opened on 16 June 1874.

The four partial differential equations, now known as Maxwell's equations, first appeared in fully developed form in Electricity and Magnetism (1873). Most of this work was done by Maxwell at Glenlair during the period between holding his London post and his taking up the Cavendish chair. They are one of the great achievements of 19th-century mathematics.

One of the tasks which occupied much of Maxwell's time between 1874 and 1879 was his work editing Henry Cavendish's papers. Cavendish,:-

... published only two papers [and] left twenty packages of manuscript on mathematical and experimental electricity. ... Maxwell entered upon this work with the utmost enthusiasm: he saturated his mind with the scientific literature of Cavendish's period; he repeated many of his experiments, and copied out the manuscript with his own hand. ... The volume entitled The Electrical Researches of the Honourable Henry Cavendish was published in 1879, and is unequalled as a chapter in the history of electricity.

Fleming attended Maxwell's last lecture course at Cambridge. He writes:-

During the last term in May 1879 Maxwell's health evidently began to fail, but he continued to give his lectures up to the end of the term. ... To have enjoyed even a brief personal acquaintance with Professor Maxwell and the privilege of his oral instruction was in itself a liberal education, nay more, it was an inspiration, because everything he said or did carried the unmistakable mark of a genius which compelled not only the highest admiration but the greatest reverence as well.

Maxwell returned with his wife, who was also ill, to Glenlair for the summer. His health continued to deteriorate and he suffered much pain although remained remarkably cheerful. On 8 October 1879 he returned with his wife to Cambridge but, by this time he could scarcely walk. One of the greatest scientists the world has known passed away on 5 November.