### Maxwell's Equations for Light & Other Electromagnetic Waves

"From a long view of the history of mankind - seen from, say, ten thousand

years from now - there can be little doubt that the most significant event of

the 19th century will be judged as Maxwell's discovery of the laws of

electrodynamics. The American Civil War will pale into provincial

insignificance in comparison with this important scientific event of the same

decade." — Richard Feynman,

The Nobel-Laureate Physicist of California Institute of Technology (Caltech)

Maxwell derived 4 equations which became so crucial for the development

of the understanding of physical phenomena. These equations were

repeatedly applied in developing newer and newer technology throughout

the Twentieth century. Radio, TV, Satelites, Radar .... the list will not end!

The year was 1864 when Maxwell presented those equations describing the

interaction among electricity and magnetism and matter. These studies

gave birth to a new field 'electromagnetism'.

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

that time, Maxwell obtained a velocity of 310,740,000 m/s. It was very close

to the speed of light and Maxwell could correctly make an educated guess

that light is indeed an 'electromagnetic' wave.

The quantitative connection that Maxwell established between light and

electromagnetism is considered one of the great triumphs of 19th century

physics. At that time, Maxwell believed that the propagation of electromagnetic

waves like light needed a medium called 'aether'. Over time, the existence of

such a medium, permeating all space and yet apparently undetectable by

mechanical means, proved to be more and more difficult to come in agreement

with experiments such as the Michelson-Morley experiment described in our

last posting. Moreover, it seemed to require an absolute frame of reference in

which the equations were valid. This was not reconciling well with the beauty

of a theory that Physicists strive for. The concept of 'aether' leads to the notion

that Maxwell's equations should change form for a moving observer.

These are the difficulties that inspired Einstein to come up with the theory of

special relativity and solve the Jigsaw puzzle of theoretical Physics at that time.

In that process Einstein abandoned the requirement of a luminiferous aether

and stated that time and space are not absolute.

Perhaps that's why Einstein later said, "The special theory of relativity owes

its origins to Maxwell's equations of the electromagnetic field."

The year was 1905 when Einstein forwarded that revolutionary theory.

Just 100 years back!

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