A system that makes no exchange of any kind with any environment.
As stated by I. PRIGOGINE and P.M. ALLEN such a system: "… whatever its nature, will approach thermodynamic equilibrium, a state characterized by the maximum value of entropy, that is of "disorder" (1982, p.5).
This is a largely abstract concept. Indeed it is the model of a system rigorously submitted to the 2d law of thermodynamics.
By definition the isolated system does not absorb nor emit any energy, matter or information and could thus not even be observed. While useful in clasical physics and chemistry, it can not be used in biology nor social sciences (nor even, in some cases in physical sciences). This explains why classical thermodynamics had to be extended during this century to open and irreversible systems.
According to G. SOMMERHOFF: "An isolated physical system in the classical sense is determined by the initial state". This means "that the current state of the system can be expressed in terms of single-valued functions of the initial state and the time". SOMMERHOFF gives the example of the pendulum, for which the isolated system model does not take in account any friction or disturbance, which, of course, are always acting on concrete systems.
The isolated system, furthermore is practically always linear and generally deterministic. G. SOMMERHOFF writes about this point: "In a state-determined system every possible initial state determines a single line of behavior only. And although different lines of behavior may at one point or another fuse, they can never bifurcate" (1969, p.158).
The concept of isolated system is particularly confusing in the case of living and social systems. As stated by A. RAPOPORT: "an isolated system cannot be a living system (at least not for long)" (1966, p.6).
The misunderstanding of this aspect, very common since DRIESCH vitalism until the 1930es, blocked partly the development of biology during half a century, with among exceptions, WOODGER and von BERTALANFFY's work.
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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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