## ENTROPY
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1) "The amount of disorder in a system, which by the 2nd law of thermodynamics will tend to increase unless the system is open to receive negentropy, which is information" (J.Z. YOUNG, 1978, p.292).

2) "Abstract quantity, which characterizes the disorder of positions, velocities or other variables of particles in a large system" (R. FIVAZ, 1991, p.31).

We may distinguish statistical entropy, which measures disordered dispersion, and thermodynamic entropy which corresponds to the degree of degradation of energy, i.e. measures its uselessness to produce some work.

The maximum entropy in a system corresponds to the complete disappearance of energy potentials, i.e. the final disappearance of any order, in which case the system ceases to be a system.

YOUNG's assimilation of negentropy with information is not universally accepted. The negentropy concept itself has been much debated as to its real significance.

R. FIVAZ explains: "… (entropy) is measured by the logarithm of the number of distinct configurations realized by permutations between all possible values of these variables" (Ibid).

Entropy is basically a relational notion which reflects the irreversible degradation of energy, through its transformations. The tendency of entropy is to increase monotonically and to reach a maximum as the (ideally isolated) system reaches its final equilibrium state.

I. PRIGOGINE writes: "As is well-known the basic importance of the second law (of thermodynamics) in the context of physical evolution was clearly recognized by CLAUSIUS who introduced the term "entropy" which in Greek means "evolution" (1973, p.561).

Entropy is originally a thermodynamic notion. It may be transposed to cybernetics and systemics. In this case, according to J.van GIGCH, it: "…refers to the amount of variety in a system, where variety can be interpreted as the amount of uncertainty prevailing in a choice situation with many alternatives" (1978, p.41).

In order to avoid ambiguity, let us remember however that:

1) variety, in a structured system, is obtained by defining constraints upon the relationships between elements. In this way a finite number of choices are possible.

2) excessive or total constraints reduce or destroy variety, as they diminish or suppress the number of autonomous subsystems. The number of possible choices tends to nil.

3) no constraints at all means total indefinition and thus the impossibility of any significant choice. Only in cases approaching this limit should variety be interpreted as entropy.

### Categories

- 1) General information
- 2) Methodology or model
- 3) Epistemology, ontology and semantics
- 4) Human sciences
- 5) Discipline oriented

### Publisher

Bertalanffy Center for the Study of Systems Science(2020).

To cite this page, please use the following information:

* Bertalanffy Center for the Study of Systems Science (2020).* Title of the entry. In Charles François (Ed.), International Encyclopedia of Systems and Cybernetics (2). Retrieved from www.systemspedia.org/[full/url]

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