Systems, Man & Cybernetics - July 2015 - 39

lated by electrical discharges without electromagnetic
waves penetrating outwardly. However, if an oscillating
circuit such as this is supplied with electromagnetic waves
of its own eigenfrequency, then special calibrated oscillations are enhanced, while others are inhibited. This effect
could be used to adjust certain frequencies on the transmitter and receiver side; a short time later, it proved to be
extraordinarily important in the further development of
communication engineering.
In 1915, Karl Wilhelm Wagner (1883-1953) in Germany
and George Ashley Campbell (1870-1954) in the United
States simultaneously discovered that it was possible
during the transmission of
electromagnetic waves to
use particular circuits to
favor not only a particular
frequency or an unlimited
number of frequencies but
even entire predetermined
When Communication
frequency ranges. In the
Became Mathematical
German milieu, these were
The mathematization proreferred to as filter circuits,
ce s s of com mu n ic a t ion
while the term electric filtech nolog y rea l ly bega n
ter was preferred among
with the discovery of filter
Americans. Wagner was
circuits, or electrical filable to show "how it is posters, in the 1920s. Because
sible to achieve a filtering
of pr o ble m s t h a t we r e
of predetermined frequency
observed in both conducted
ranges by starting with a
and wireless message transrelatively simple quadrumissions, scientists increaspole resonance circuit and
ingly analyzed the behavior
connecting it repeatedly in
of the communication techa series with itself (known
nology systems using the
as a ladder network). If
mathematical tools they had
the number of links in the
acquired during their studchain is allowed to increase
ies, although the engineer's
knowledge of them left quite Figure 1. Lotfi A. Zadeh (right) with his parents in New indefinitely, the transceiver
will no longer permit cera lot to be desired.
York in the 1950s. (Photo courtesy of Lotfi A. Zadeh.)
tain predeterminable freB e c a u s e ba s ic m a t h quency ranges to pass through at all" [7, p. 27f].
ematical-physical knowledge was often lacking or
However, as the distances between the sender and
insufficient, those involved sought analytical methods
receiver grew, the process of testing the communicathat would lead them to their goal, although they had
tion systems for functionality only after they had been
not mastered the Maxwellian equations and could not
installed became less practicable. The trial-and-error
employ corresponding calculations. The network and
method needed to be replaced by something better, as Vansystem theories represented a similar concept. Since
nevar Bush (1890-1974) wrote in 1931:
electrical engineers were interested merely in the input
Empiricism here would have been utterly hopeless and
and output behavior of the basic building blocks of comunjustifiably expensive. One cannot temporize with a
munication engineering and less in a physical explanalong transmission line running across actual country by
tion of what was happening inside such components of
trying this and replacing that. Haphazard work of that
electrical circuits, they were content with a correspondnature could have but resulted in discouragement and
ing black-box theory with which they could analyze the
failure. Procedure by thoroughly rigorous mathematical
real systems modeled in this way.
treatment to the condition where operation is underCarl Ferdinand Braun (1850-1918) discovered the
stood is the necessary step if the result is to be practicalclosed oscillating circuit in 1928, which, in contrast to the
ly accomplished. For this, Campbell, and almost alone,
open aerial circuit, consisted of a capacitor and a coil and
deserves the credit. He gave us the loaded line. [6]
slowly decayed in the high-frequency oscillations stimuthrough all the parts of the instrument, that we have
our present-day quality of telephone, phonograph,
and sound-picture reproduction. The promise for the
future rests in the existence of just such exact mathematical analysis to every problem in which there is a
translation of energy between mechanical and electrical forms. [1, p. 33f]
The foundations of mankind's communications structures-structures that still exist today-were created
during the 1930s. Much may have changed, yet the technological basis forged back then is still valid today, and
the trust placed in its mathematical exactness has also
been placed in the computability of physical systems.
These successes proved that
the scientists and engineers
were right.

Ju ly 2015

IEEE Systems, Man, & Cybernetics Magazine

Table of Contents for the Digital Edition of Systems, Man & Cybernetics - July 2015