VII
The experimenter Faraday, being unskilled in math-
ematics, created simple pictorial concepts to help him
interpret his pioneering researches in electromagnet-
ism. The theorists had been content to find mathe-
matical, action-at-a-distance formulas for the forces
exerted by magnets and electric charges. But Faraday
created a revolution in physics by consistently envi-
sioning a magnet or charge as surrounded by a “field”
of tentacle-like lines of force reaching through space,
so that all space became the domain of the important
aspects of electromagnetic phenomena.
Building on Faraday's work, Maxwell imagined an
electromagnetic aether with a pseudo-mechanical
structure so bizarre that he himself did not take it
seriously. Nevertheless he took it just seriously enough
to extract from it electromagnetic field equations that
play a key role in the development of the theory of
relativity. Since Maxwell required an electric current
—his crucial “displacement current”—in free space,
where there was no electric charge, his theory hardly
seemed credible to physicists. Yet the displacement
current gave an elegant mathematical symmetry to
Maxwell's equations and because of it his theory pre-
dicted the existence of transverse electromagnetic
waves moving with the speed of light; and when in
1888, nine years after his death, these waves were
detected by Hertz, Maxwell's theory could no longer
be easily resisted. It yielded a superb unification of the
hitherto disparate disciplines of optics and electro-
magnetism, with visible light occupying a narrow band
of wavelengths in a broad spectrum of electromagnetic
radiation. It also dispensed with electromagnetic action
at a distance by having electromagnetic effects trans-
mitted by the aether acting as intermediary. As for
the all-important aether, Maxwell's equations deline-
ated for it an inner structure that could not be en-
visaged in credible Newtonian mechanical terms.
Gradually physicists, becoming accustomed to its
mathematical properties, learned to live with it, and
an era of mechanistic physics faded.
