Maxwell’s Original Presentation of Electromagnetic Theory and Its Evolution

Abstract

One of the objectives of this presentation is to illustrate how Maxwell came to his mathematical constructs of the work done before him by Oersted , Ampère, Faraday, Gauss, and so on, into a concise and precise mathematical form. In addition, the chapter addresses two specific topics which are fundamental in engineering electromagnetic education: how did Maxwell reached the conclusion that light was electromagnetic in nature and thereby revolutionized the last-century physics and the concept of displacement current? Maxwell first published his famous equations 20 in number in the early 1860s, and yet they were not accepted by the scientific community and were not put in the proper form till the early 1880s. The question is why it took over 20 years for the scientific community to grasp Maxwell’s ideas. One of the reasons why Maxwell’s theory was so difficult to follow was due to the development of Maxwell’s thought process through different times. This made Maxwell not to identify his physical pictures with reality. Maxwell felt free to discard one picture and adopt another as often as expediency or convenience demanded. Maxwell’s theory over the years evolved in two different steps. That is the other subject matter of this chapter.

Maxwell never believed that light could be generated electromagnetically. In fact, he was always silent about electromagnetic waves and their generation and detection. It took almost 25 years before Hertz discovered electromagnetic waves, and his ingenious experiments confirmed Maxwell’s theory. Maxwell’s ideas and equations were expanded, modified, and made understandable by the efforts of Hertz, FitzGerald, Lodge, and Heaviside. The last three are being referred to as the “Maxwellians.” The early history of electromagnetic waves, up to the death of Hertz in 1894, is briefly discussed. The work of Hertz and the Maxwellians is briefly reviewed in the context of electromagnetic waves. It is found that historical facts do not support the views proposed by some, in the past, that Hertz’s epoch-making findings and contributions were “significantly influenced by the Maxwellians.” Finally, Maxwell’s macroscopic theory was transformed to the microscopic theory based on electrons as its discovery came 18 years after Maxwell’s death.