Any description of the workings of nature by means of measurements and
ob- servations is beset with the problem of how to cope with an immense
amount of information. In physics, it is an established approach to
derive basic equations which then serve as cornerstones of what is
called a theory of the phenomena. This derivation is based on certain
characteristics of the phenomena, the refine- ment of which results from
a reduction of the amount of empirical information, with the reduction
leading to an enhancement of the very characteristics that are sought
for in the otherwise seemingly amorphous wealth of data. If physics is
mainly concerned with the derivation of equations, lately there has
emerged a conceptually different approach, which in a way is equivalent
to a reversal of the line of attack: here, the basic equations serve as
the point of departure and the aim is to demonstrate that the equations
are capable of de- to represent the essence of the scribing certain
characteristics which are thought phenomenon under investigation. By
definition, this variant approach must tran- scend the realm of pure
physics and could possibly be termed "applied mathe- matics" in a
broader sense. The phenomena it strives to characterize arise from a
range of influences such that a combination of theoretical concepts from
physics, chemistry, engineering, biology, etc., is called for.