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James Clerk Maxwell


James Clerk Maxwell was a Scottish physicist and mathematician. He was born in 1831 and died in 1879. From an early age he showed his ability for mathematics. At the age of 15, he wrote a paper presenting a method for tracing oval curves and sent it to the Scottish branch of the Royal Society. The scholars in charge of analyzing it doubted that it had been done by someone so young.

A year later, Maxwell met the then very old Scottish Nicol, who had invented a polarized light detection instrument called Nicol's prism. Thanks to this contact, Maxwell would also be interested in Optics. At age 19, he studied mathematics at the University of Cambridge. Seven years later, it theoretically demonstrated that Saturn's rings must be made of solid particles, since if they were formed of liquids or gases, they would not have stability to keep rotating.

Shortly thereafter, studying the behavior of gases mathematically, he came to the theoretical conclusion that their molecules move in all directions and at all possible speeds, colliding with each other and against obstacles. It showed that most of them, however, would move at intermediate velocities, meaning that the best indicator of the internal agitation state of a gas would be the average velocity of its molecules. This allowed him to conclude that a body temperature could be interpreted in terms of this average molecular velocity. Such conclusions were decisive in abandoning the old theory of "caloric fluid," according to which heat would be a kind of substance that would transfer from the hottest to the coldest body.

At age 30 Maxwell became the first chair of the chair of Experimental Physics at Cambridge. Although his knowledge enabled him to do so, he was not enthusiastic about his job, as he did not appreciate the teaching profession.

From 1864 onwards, he devoted himself to mathematically formulating Faraday's theories of magnetism, obtaining simple equations that allowed describing both electrical and magnetic phenomena. it was thus theoretically demonstrated that electricity and magnetism are essentially one and the same thing. Moreover, Maxwell predicted with his formulations that the oscillation of an electric charge produces a magnetic field. In trying to calculate the velocity of propagation of this field, it was surprising to obtain the approximate value of 300 000 000 m / s: this was the speed of light itself, already experimentally calculated by Fizeau and Foucault!

He thought then that this could not be mere coincidence. On the contrary, he stated that light was nothing more than electromagnetic radiation. Moreover, if electric charges could oscillate at any speed, they could give rise to radiation of all wavelengths, with light being just a specific variety of those radiations.

It is interesting to note that all these unpublished conclusions were obtained exclusively from theoretical calculations and considerations, without yet being able to develop experiments to confirm them. Until then, apart from visible light, only infrared and ultraviolet radiation were known, but Maxwell predicted that there were others of different wavelengths, which would be confirmed later by Hertz.

However, Maxwell believed that electromagnetic waves did not propagate in a vacuum, but used the intermediation of ether, a fluid that would be present throughout the universe, in matter and in spaces devoid of it. This conception would be rejected by the succeeding researchers.

In Cambridge, Maxwell published Henry Cavendish's experimental work on electricity, done in the previous century and which was still unknown. In honor of him, he created at that university the Cavendish Laboratory, where years later important research on radioactivity would take place. Maxwell died a few days before his 48th birthday. He described himself as deeply religious and very happy in marriage.

Bibliography: Learning Physics, Scipione Publisher.