The more I read of Michael Faraday's work, the more I am in awe of the scientist's insights and abilities. As evidence of the remarkable intuition he had regarding the forces of nature, consider the following passage:
I have long held an opinion, almost amounting to conviction, in common I believe with many others of natural knowledge, that the various forms under which the forces of matter are made manifest have one common origin; or, in other words, are so directly and mutually dependent, that they are convertible, as it were, one into another, and possess equivalents of power in their action. In modern times the proofs of their convertibility have been accumulated to a very considerable extent, and a commencement made of the determination of their equivalent forces.
Faraday wrote this as the introduction to the nineteenth series of his "Experimental Researches in Electricity," published in the Philosophical Transactions (vol 136, pp. 1-20) in 1846! It is an eloquent and remarkably timeless statement which could very well have been written by any modern physicist working on the foundations of a grand unified theory of forces.
As he himself notes in the passage above, Faraday was not alone in envisioning a single theory encompassing all physical phenomena. Indeed, once Ørsted discovered that a magnetic compass needle could be deflected by an electric current, the relationship of electricity and magnetism, as well as other forces, was very much on the minds of physicists. Faraday, however, led the charge in actually demonstrating these relations. As I have noted in previous blog posts, Faraday demonstrated experimentally that magnets could induce electric currents (Faraday induction) around 1831, and also compiled evidence demonstrating that the diverse sources of electricity were different manifestations of the same electrical phenomena around 1833.
Because of these discoveries (and other hugely important ones that I haven't had time yet to discuss), by 1845 Faraday was one of the most prestigious and famous scientists in England. He was by no means done with his research, however, and in that year he presented a paper describing his observations that a magnetic field can indirectly influence the behavior of a light wave. This was the first definitive evidence that light and electromagnetism are related, and helped pave the way for Maxwell's brilliant theoretical demonstration of the existence of electromagnetic waves, and their identity with light.
The effect that Faraday observed is now known as Faraday rotation, and we take a look at the experiments, and their reception, in this post.
Continue Reading »