IASLonline NetArt: Theory
History of Computer Art
II. Cybernetics
II.1 Basics of Cybernetics
auf
Deutsch
The basics of cybernetics were presented by technically constructed models
(see chap. II.2). These models became fundamental for the development
of cybernetic sculptures (see Chap. II.3), meanwhile the information aesthetics
based on cybernetics offered criteria for the serial artists programming
computer graphics (see chap. III.2). This shows: There is no alternative
to an introduction to cybernetics.
In 1948/49 Norbert Wiener and Claude
Elwood Shannon published in their classic books on cybernetics and information
theory the basics of the American army´s ballistic research in the
Second World War. The calculation of the flight path of an enemy´s
airplane presupposed to know how pilots navigate to reach their target.
1 However, in practice, the pilots changed their approach
to targets according to their knowledge of the air defense and made forecasts
of the meeting between an airplane and a projectile impossible. 2
The problem to predict this crash made relevant the problem to calculate
the probability which flight path will be chosen (see chap. II.1.2).
The cybernetics´ basic texts are the fruits
of the research for air defense 3 being able to resolve
the feedback (see chap II.1.4) between the movements of the targets and
the projectile much later with the development of missiles.
At first the
integration of mathematics into engineering was discussed controversal
by researchers of ballistics and cryptography. 4 "It
was only in 1945, when the usefulness of mathematics was upgraded for
strategic and technic tasks." 5 Before 1945 Wiener
and Shannon investigated the fields of convergences between mathematics
and engineering, and in their later published writings they laid down
the basics for an understanding of the term information as integrating
the opposing research poles (see chap. II.1.3). For mainframe computers
the American and British army developed simultaneously uses in ballistics,
early warning systems, and cryptography. 6
Left: Norbert Wiener (Cover of "Cybernetics",
second edition, 1962).
Right: Claude Elwood Shannon with "Theseus" (1952) and the mouse
navigating itself through the labyrinth (compare chap. II.2.2).
(Credit: MIT Museum, Boston / Nixdorf MuseumsForum, Paderborn)
Stochastics combine calculations of probabilities and statistics of frequencies.
The possibilities of a system to combine its elements with each other
can be restricted to probabilities by statistics informing about the frequency
of their earlier occurrences. Predictions indicate the probability of
a systems´ elements by indicating how often they appeared in the
past and how these occurrences relate to all possible combinations : The
reappearance of a more frequent used element is more probable than the
reappearance of a seldom used element. Shannon used stochastics as a means
to construct the English language for a second time by generating combinations
of its elements and their combinations – following the frequencies
of their occurrences. The computer calculates the possibilities of combinations
fast and the frequency statistic of letters in units of a selected language
serves to restrict these possibilities. In the course of this selection
procedure the probability rises that the calculated possibilities and
the chosen language coincide (see chap. III.1.3).
The approximation to a language by the recombination
of its elements in regard to the frequencies´ statistics of their
occurrences in the everyday language recalls procedures of the cryptography:
The signs appearing often in a code are compared with the frequencies
of signs in the language of the message to be decoded. Shannon won the
characteristics of a not decryptable code with cryptographic methods:
It should be constructed only by chance operations, it should be as extensive
as the urtext, and it has to be kept secret. 7
For Shannon
and Wiener the term information serves to denote a measure of a technical
system´s capacity. A system´s technology can be able to transfer
a certain amount of information. There is a distinction to be made between
this measurement of its transmission capacity and the "semantic information"
(see chap. III.1.3). 8 The basis of a definition of "information"
is formed by the probable distribution of physical elements in a closed
system with its tendency to entropy ("particular disorder, mixture"),
as elaborated by Ludwig Boltzmann in his statistical thermodynamics 9,
and its opposite, the "segregation" and "demixing"
10: information as negentropy. Cybernetics use the negation
of entropy (negentropy) to develop a theory of information.
The alternative between two values is measured as
1 "bit". The relais of calculating machines and computers switch
between the two values "0" and "1". 11
The possibilities to select are calculated as 2^{n}. "n"
stands for a number of decisions to choose one of the values "0"
and "1". "Probabilities of selection" p_{1},
p_{2}...p_{n} belong to any independent, selectable sign.
The probability of selection specifies the probability of an element´s
occurrence (see chap. II.1.2). The probability of selection is multiplied
by the logarithm with the base 2 of the probability of selection (p_{n}log_{2}p_{n}).
The products calculated with each probability of selection are added.
The sum is negated to obtain the negentropy resp. the information "I":
I =  (p_{1}log_{2}p_{1} + p_{2}log_{2}p_{2} + ...p_{n}log_{2}p_{n})
I =  Σ p_{n}log_{2}p_{n} (Σ = sum
for n = 1 until n) 12
The systeminternal transmission,
its disturbances ("noise") and the feedback of the output into
the system belong to the processing of input: The system controls the
output by detecting the deviations and by reacting to them. This control
procedure is called "feedback" 13 and the
correcting technical element is named "observer". The "observer"
couples the output to a circuit integrating the output data and correcting
the subsequent output. In the case of deviations above a certain threshold
this corrective "observer" is activated. 14
The connection between a system
with an internal "observer" and its environment is recognized
by an "external observer" 15 integrated by
second order cybernetics as part of a more extensive system. This more
extensive system contains the environment of the first system as well
as its observer orienting himself by perceptions and moving himself in
this environment. 16 The external observer of the first
system becomes an internal observer of the more extensive system.
Shannon, Claude Elwood: A Mathematical Theory of Communication.
In: Bell System Technical Journal, Vol. 27/Nr.3, 1948, p. 409.
A system communicates with its
environment by trying to use the internal structures for accomodations
to disturbances being caused externally. William Ross Ashby´s cybernetic
model of a "homeostasis" (see chap. II.2.1) presents a system
with internal functions seeking equlibrium. 17 A multipartite
system uses its internal variability to react to external disturbances
with balancing moves by other parts than the disturbed part. In its stable
overall condition all parts are either in the middle or at the extreme
states balancing themselves reciprocally. This internal differentiation
constitutes the capability to react selfregulatory to external disturbances:
The "Homeostat" is a model for the "law of requisite variety".
18
William Ross Ashby beside the "Homeostat",
realised in 194647.
Niklas
Luhmann´s "autopoiesis" 19 presupposes
Ashby´s "law of requisite variety". The evolution of systeminternal
differentiations improves the capabilities of social, biologic and cognitive
systems to react to the environment. 20 Because systems
are not as complex as their environment they develop their complexity
reducing "selection strategies" 21 for the
observation of the environment. These developments presuppose a "requisite
variety" emerging in differentiations of "inter system relations".
22
Dr. Thomas Dreher
Schwanthalerstr. 158
D80339 München.
Homepage with numerous articles
on art history since the sixties, a. o. on Concept Art and Intermedia
Art.
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Annotations
1 Bluma: Wiener 2005, p.90s.; Wiener: Cybernetics 1948,
p.11ss. back
2 Roch: Shannon 2009, p.4382,125144,156162; Roch/Siegert:
Maschinen 1999, p.219,222229; Wiener: I 1956, p.243263. back
3 Roch: Shannon 2009, p.145: "Shannon worked out
first the answer for the discrete case of a secure communication in `A
Mathematical Theory of Cryptography´ (Shannon: Theory 1945), then
he prepared the continuous case of a disturbed transmission for `Transmission
of Information´ ([manuscript ]1947, [published with the title "Communication
in the Presence of Noise": Shannon: Communication 1949]). In 1948
Shannon brought the methods and results of all preparatory works together
in `A Mathematical Theory of Communication´ [Shannon/Weaver: Theory
1949/1998]. Shannon problematised not only the question of an effective
communication, but concretely the theoretical basics of a secure and effective
navigation of electronic air defence systems."
Roch: Shannon 2009, p.104, quoting Shannon: "`When I came out with
my paper in 1948, part of that was taken verbatim from the cryptography
report, which had not been published at that time.´ [Shannon quoted
in Price: Conversation 1985, p.170] For the scientific public Shannon
simply devided his 114 pages long `cryptography report´ in two parts:
one part more about communication theory and another one on codes."
Cf. Roch: Shannon 2009, p.82,120ss.,128ss.,144s.,159.
Norbert Wiener on feedback and the theory of prediction in its use in
antiaircraft fire in the Second World War: Wiener: Cybernetics 1948, p.1114,23s.,55;
Wiener: I 1956, p.249255,260265.
On Wiener´s antiaircraft research and its pioneering role in cybernetics:
Bluma: Wiener 2005, p.108ss.,116. back
4 Roch: Shannon 2009, p.5764. back
5 Roch: Shannon 2009, p.63. Cf. Wiener: Cybernetics
1949, p.20s. back
6 Augarten: Bit 1984, p.109112,120131,210ss.,195202;
Gere: Culture 2008, p.4650,65ss.; Roch: Shannon 2009, p.34; Wiener: Cybernetics
1949, p.22. back
7 Shannon on the reconstructability of languages using
stochastics: Bense: Aesthetica 1982, p.335s.; Roch: Shannon 2009, p.26s.;
Shannon: Communication Theory 1949, p.656s.; Shannon: Redundancy 1950,
p.249; Shannon/Weaver: Theory 1949/1998, p.3944; WardripFruin: Media
2007, p.236239.
Shannon on cryptography: Shannon: Communication Theory 1949. The unpublished
"A Mathematical Theory of Communication" of 1945: see ann.3.
Cf. Roch: Shannon 2009, p.96123; Rogers/Valente: History 1993, p.39,42ss.
For antiaircraft systems the security of the transmission of control signals
was crucial: Roch: Shannon 2009, p.144152. back
8 Shannon: Redundancy 1950, p.123/248; Wiener: Cybernetics
1949, p.18. back
9 Bense: Aesthetica 1982, p.153,160,211,325; Roch: Shannon
2009, p.115s. back
10 Bense: Aesthetica 1982, p.213. back
11 Cf. Roch: Shannon 2009, p.33s.; Wiener: Cybernetics
1949, p.22s.,139ss. (with comparisons between relais and nerve cells).
back
12 Bense: Aesthetica 1982, p.212s.; Porr: Systemtheorie
2002, p.6; Shannon/Weaver: Theory 1949/1998, p.14,32s. back
13 Wiener: Cybernetics 1949, p.13,113136. back
14 Roch: Shannon 2009, p.160s.; Shannon/Weaver: Theory
1949/1998, p.68. back
15 Bense: Aesthetica 1982, p.364s. back
16 Gregory Bateson and Margaret Mead in Brand: God
1976. back
17 Ashby: Design 1960, p.100121; Ashby: Introduction
1957, p.7385. Cf. Wiener: Cybernetics 1949, p.134ss. back
18 Ashby: Introduction 1957, p.202219; Ashby: Variety
1958; Porr: Systemtheorie 2002, p.11ss. back
19 Luhmann: Systeme 1984, p.60s. back
20 Porr: Systemtheorie 2002, p.13s.,18,41s.,51. Cf.
Ashby: Variety 1958, chap. Operational Research. back
21 Luhmann: Systeme 1984, p.47s. back
22 Luhmann: Systeme 1984, p.249. back
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