### James Clerk Maxwell, R.I.P.

By Aussiegirl

In today's Scotsman.com Fact of the Day column is this short obituary:

*One of Scotland's most brilliant minds died today in 1879. Mathematical physicist James Clerk Maxwell died at the age of 48 of abdominal cancer. Maxwell had an incalculable effect on 20th century physics - so much that Albert Einstein declared his theories as the "most profound and the most fruitful that physics has experienced since the time of Newton."*

Here is the link to the Wikipedia article on this great scientist -- and what follows is that part of the article that describes his great achievement in formulating the equations that describe the electric and magnetic fields and their interactions with matter:

The greatest work of Maxwell's life was devoted to electricity. Maxwell's most important contribution was the extension and mathematical formulation of earlier work on electricity and magnetism by Michael Faraday, André-Marie Ampère, and others into a linked set of differential equations (originally, 20 equations in 20 variables, later re-expressed in quaternion and vector-based notations). These equations, which are now collectively known as Maxwell's equations (or occasionally, "Maxwell's Wonderful Equations"), were first presented to the Royal Society in 1864, and together describe the behaviour of both the electric and magnetic fields, as well as their interactions with matter.

Furthermore, Maxwell showed that the equations predict waves of oscillating electric and magnetic fields that travel through empty space at a speed that could be predicted from simple electrical experiments—using the data available at the time, Maxwell obtained a velocity of 310,740,000 m/s. Maxwell (1865) wrote:

This velocity is so nearly that of light, that it seems we have strong reason to conclude that light itself (including radiant heat, and other radiations if any) is an electromagnetic disturbance in the form of waves propagated through the electromagnetic field according to electromagnetic laws.

Maxwell proved correct, and his quantitative connection between light and electromagnetism is considered one of the great triumphs of 19th century physics.

At that time, Maxwell believed that the propagation of light required a medium for the waves, dubbed the luminiferous aether. Over time, the existence of such a medium, permeating all space and yet apparently undetectable by mechanical means, proved more and more difficult to reconcile with experiments such as the Michelson-Morley experiment. Moreover, it seemed to require an absolute frame of reference in which the equations were valid, with the distasteful result that the equations changed form for a moving observer. These difficulties inspired Einstein to formulate the theory of special relativity, and in the process Einstein abandoned the requirement of a luminiferous aether.

## 1 Comments:

Aussiegirl, I'm always delightfully surprised at the range of the science articles that you find to post, and I learn a lot of interesting stuff from them. By the way, in case you didn't know -- but you probably did -- Maxwell's middle name, "Clerk", is pronounced as if it were spelled "Clark".

Post a Comment

<< Home