Jfromm: New page: {{SelfOrg}} The abbreviation SOC is sometimes used for "Service Oriented Computing" or "System On Chip". It can also mean '''Self-Organized Criticality''', a concept coined by the Danish ...

2008-08-30T10:56:24Z

New page: {{SelfOrg}} The abbreviation SOC is sometimes used for "Service Oriented Computing" or "System On Chip". It can also mean '''Self-Organized Criticality''', a concept coined by the Danish ...

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{{SelfOrg}}

The abbreviation SOC is sometimes used for "Service Oriented
Computing" or "System On Chip". It can also mean '''Self-Organized Criticality''',
a concept coined by the Danish physicist Per Bak (1948-2002).
It is the most physical form of [[Self-Organization|self-organization]],
which can occur even in inanimate matter.
The term is closely related to the concept of the [[Edge of Chaos|edge of chaos]]
and means that a system evolves towards a critical state, where the state of
the systems can change suddenly. It is characterized by high
[[Complexity|complexity]], which means unity in diversity: stability in
instability, simplicity in intricacy, and predictability in
unpredictability. The price for this complexity is usually
low uniformity, it is a point of permanent change, continuous
fluctuations and constant variation.

The criticial point is point of high complexity, because it
combines stability and instability: the system evolves automatically
to a certain state (which increases stability, certainty, and
predictability), but at these state chain reactions can lead
to avalanches and cascades of any size (which increases instability,
uncertainty and unpredictability). Thus the criticial point in
self-organized criticality is a "metastable" and complex state
characterized by instability in stability, uncertainty in
certainty, or unpredictability in predictability.

The SOC concept can be applied for example to tectonic
plates (earthquakes) or to sand piles (avalanches). If grains
are added to a pile constantly, the slope of the sand pile
develops itself automatically towards a certain critical
value, where avalanches of all sizes can occur. Although the
system is stable (it develops towards a certain critical
point despite disturbances), it is instable at the same time
(there can be avalanches and cascades of all sizes). It shows a
high complexity in form of stability in instability.

SOC means also often a high complexity in form of simplicity
in intricacy. On the one hand the behavior is simple and
can be described by a few parameters, but on the other hand
the behavior is intricated, characterized by long-range
fluctuations and correlations, and can not be predicted at
all. Although the detailed behavior and the precise
occurence of avalanches is hard to predict, the
overall behavior of the system can be described by
a few parameters named "critical exponents". They
are typical for phase transitions. The distribution
of avalanches at a critical point follows typically a
power law. Small events are very frequent while large
events are rare.

Like other concepts, for example [[Autopoiesis]],
Self-Organized Criticality is not a complete science
or a theory, rather an observation, a phenomenon,
or a principle. The idea of SOC is useful to explain cascades
and avalanches (for example in sand-piles or producer-consumer
networks) that can be described well by simple power-laws.

== Books ==

* Per Bak, ''How Nature Works - The Science of Self-Organized Criticality'', Springer, 1996, ISBN 0387947914

== Links ==

* [http://en.wikipedia.org/wiki/Self-organised_criticality Wikipedia Entry for SOC]

* [http://cscs.umich.edu/~crshalizi/notebooks/soc.html SOC Notebook-Entry (C.R. Shalizi)]

[[Category:Basic Principles]]

Self-Organized Criticality - Revision history

Jfromm: New page: {{SelfOrg}} The abbreviation SOC is sometimes used for "Service Oriented Computing" or "System On Chip". It can also mean '''Self-Organized Criticality''', a concept coined by the Danish ...