Wave Propagation in Linear Media | re-examined

Preface
Our popular writers and reporters, when they have to deal with physics,
indulge in similies of all sorts; the trouble is that they leave the reader
helpless in nding out how far these pungent analogies cover the real issue,
and therefore more often lead him astray than enlighten him.
Hermann Weyl, The Mathematical Way of Thinking, reprinted in [1]
Rarely does theoretical physics attract the attention of a broad public. Even if news of this
branch ofscience works its way into the papers, it turns into margin notes rather than eyecatching
headlines. Of course, there are the annual review articles and features celebrating the
Nobel laureates, and occasionally there are obituaries of prominent physicists. These reports,
however, always hinge on the personalities themselves, and physics plays only a subordinate
role there | as opposed to the striking importance physics, as well as engineering, undeniably
have in modern life. One could blame the underrating of physics on a general scepticism about
science and technology. While this is certainly true, it can hardly be the only explanation.
If it was, whence would all the popular articles on biology, cosmology or geophysics come?
The revival of the dinosaurs, the pros and cons of genetic manipulation, the intricacies of the
weather, the possibilities of extraterrestrial life on mars or wherever, and naturally all shades
of medicine | the list of interesting topics wandering through the media is long and may be
extended arbitrarily. Theoretical physics, though, hardly ever turns up.
Another point: stories on physics seem to be relevant only if the reported achievements have
an impact on technology or | better still | on daily life. A better understanding of quantum
physics assists in the development of smaller microelectronic devices that permit the invention
of circuits with ever-increasing complexity, but decreasing power consumption. On the other
end of the scale, nuclear fusion is still believed to be a possible solution for the growing demand
for electric power. Now, one might argue that these topics do exert an in uence on our lives,
and therefore people have the right to be informed about them. This eventually comes down
to dividing science in two parts; the knowledge-oriented and the application-oriented. The
former is often regarded as science per se, whereas the latter is commonly labelled as (often
with a slightly derogatory undertone) engineering. I am not to discuss the gap that separates
the two sides, which, by the way, was chie y dug by the scientists themselves. I just want
to state that what is addressed to the broad public is mostly the application of physics and
rarely mere knowledge-oriented work. This is by no means so in other elds, or is there any
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