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"...we should fittingly honour Maxwell as the great pioneer of radio communication, for he not only had the genius to forsee that electric waves must be produced, but had given (in 1864) the complete theory of their generation and propagation long before their existance had been suspected by science"

Ernest Rutherford, The Times

Maxwell's first major contribution to science was a study of the planet Saturn's rings, the nature of which was much debated. Maxwell showed that stability could be achieved only if the rings consisted of numerous small solid particles, an explanation still accepted. Maxwell next considered molecules of gases in rapid motion. By treating them statistically he was able to formulate (1866), independently of Ludwig Boltzmann, the Maxwell-Boltzmann kinetic theory of gases.

This theory showed that temperatures and heat involved only molecular movement. Philosophically, this theory meant a change from a concept of certainty--heat viewed as flowing from hot to cold--to one of statistics--molecules at high temperature have only a high probability of moving toward those at low temperature. This new approach did not reject the earlier studies of thermodynamics; rather, it used a better theory of the basis of thermodynamics to explain these observations.

Maxwell's most important achievement was his extension and mathematical formulation of Michael Faraday's theories of electricity and magnetic lines of force. In his research, conducted between 1864 and 1873, Maxwell showed that a few relatively simple mathematical equations could express the behavior of electric and magnetic fields and their interrelated nature; that is, an oscillating electric charge produces an electromagnetic field.

These four partial differential equations first appeared in fully developed form in Electricity and Magnetism (1873). Since known as Maxwell's equations they are one of the great achievements of 19th-century physics. Maxwell also calculated that the speed of propagation of an electromagnetic field is approximately that of the speed of light.

He proposed that the phenomenon of light is therefore an electromagnetic phenomenon. Because charges can oscillate with any frequency, Maxwell concluded that visible light forms only a small part of the entire spectrum of possible electromagnetic-radiation.

Maxwell used the later-abandoned concept of the ether to explain that electromagnetic radiation did not involve action at a distance. He proposed that electromagnetic-radiation waves were carried by the ether and that magnetic lines of force were disturbances of the ether. Subsequently, the experiments (1881, 1887) of Albert A. Michelson and Edward W. Morley and the advent (1905) of Albert Einstein's theory of relativity showed that the ether concept was untenable. Because their validity does not depend on the existence of the ether, Maxwell's equations have survived the demise of this concept.

Sheldon J. Kopperl

Source: The New Grolier Multimedia Encyclopedia

Scientists of the Royal Society of Edinburgh must have been stunned to discover that the paper submitted to them in 1845 was the work of a 14-year-old boy. James Clerk Maxwell' s first scientific paper, On the Description of Oval Curves, marked the beginning of an impressive career in science.

Maxwell was born in Edinburgh, Scotland, on Nov. 13, 1831. His family's original name was Clerk. "Maxwell" was added later. Maxwell' s mother died when he was 8 years old. He was sent to Edinburgh Academy in 1841, and at16 he entered the University of Edinburgh. In 1850 he went to the University of Cambridge. There he won honours and prizes in mathematics and became a lecturer at Trinity College. Maxwell obtained a mathematics degree in 1854.

Two years later he joined the faculty of King's College, London. He retired in 1865 to carry on his experimental work but returned to Cambridge in 1871 to plan the famous Cavendish laboratory and was its first professor of physics. Maxwell's theory of electromagnetic waves established him as one of the greatest scientists in history.

He also contributed to the study of colour blindness and colour vision and the study of Saturn' s rings. Maxwell's theory that the rings are composed of different masses of matter was confirmed 100 years later by the first Voyager space probe to reach Saturn. Although Maxwell did not originate the kinetic theory of gases, he was the first to apply methods of probability and statistics to describe the properties of gas molecules. Out of his investigation of the colour theory came the first colour photograph, which was produced by photographing one subject through filters of the three primary colours of light (red, green, and blue) and then recombining the images.

In his famous work with electricity and magnetism, he suggested that electromagnetism moved through space in waves that could be generated in the laboratory. By calculating their velocity he found that the speed of electromagnetic waves was the same as that of light waves. He concluded that light waves are electromagnetic in nature. At the time there was no evidence of comparable waves that could be transmitted or detected over any considerable distance. Maxwell died in Cambridge on Nov. 5, 1879, before this theory was successfully tested.

In 1888 Heinrich Hertz performed experiments based on Maxwell's theories and demonstrated that an electric disturbance is transmitted through space in the form of waves. Today electromagnetic waves are known to cover a wide spectrum of radiation. Maxwell expressed all the fundamental laws of light, electricity, and magnetism in a few mathematical equations, commonly called the Maxwell field equations. These equations were long considered a fundamental law of the universe, like Newton's laws of motion and gravitation. They do not apply, however, to phenomena that are governed by quantum theory, wave mechanics, and relativity.

Source: Compton's Encyclopaedia

The Scottish physicist and mathematician James Clerk Maxwell was born on November 13, 1831, the year that Samuel F.B. Morse first conceived the telegraph, and he died in Cambridge on November 5, 1879, the year that Thomas Edison was doing his first early work to invent the light bulb.

Maxwell was a precocious, natural-born scientist, always asking his dad, while just a tot, "What's the go of that?" Or, "But what's the particular go?". He made his own scientific toys before he was eight, and, at age 14, he wrote a paper on a method for constructing perfect oval curves, which was read to the Royal Society of Edinburgh by one Prof. James Forbes "for it was not thought proper for a boy in a round jacket to mount the rostrum there."

As a young man, Maxwell was something of a nerd. But, at Cambridge University, though he remained a prize-winning mathematics scholar, he became socialized and humanized. He was elected one of the 12 Apostles, a group of the university's most outstanding young men. He wrote poetry. He studied theology. And he pursued a number of scientific investigations that had little to do with mathematics. He did one study that answered the question, "Why does a cat always land on its feet, even when you turn it upside down and drop it from a height of two inches?"

Maxwell invented nothing. His major discovery of "the ether," the vast sea of space that made possible the transmission of light, heat and radio waves, was nothing more than a poetic metaphor. But Maxwell's ether, or "sea of space," made it possible for scientists and engineers who followed Maxwell to think of "waves," a move that gave them the imaginative model they needed to proceed with the experiments in electromagnetism that led to the wireless telegraph, radio, television, radar and the laser.

Maxwell's metaphor led to all the advances in electronic communication that followed. His extension of the electromagnetic theory of light led directly to Heinrich Hertz's discovery of radio waves and to related advances in science and technology which have transformed the modern world.

The reason for this: Maxwell's mathematical equations, expressing the behavior of electric and magnetic fields and their interrelated nature, his equations were valid, even though his theory of the ether was not. His calculations were not theories; they were scientific observations resulting in his conclusion that the speed of propagation of an electromagnetic field is approximately that of the speed of light. Maxwell's proposal, that the phenomenon of light is therefore an electromagnetic phenomenon, seemed to fit what he and other scientists could observe of the world around them.

Maxwell concluded that visible light forms only a small part of the entire spectrum of possible electromagnetic radiation. Put another way, Maxwell was saying that light is an electromagnetic vibration, just as radio or TV waves are electromagnetic vibrations. They are each different manifestations of the same phenomenon, not to be discovered for another 25 years: electrons in motion, whizzing along at different frequencies, in what Heinrich Hertz was to call "a mighty kingdom, the great domain of electricity." Commentators now agree that all modern electronics is based on the mathematical equations elaborated by Maxwell.

Source: http://www.wsone.com/fecha/max.htm

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