METASTABILITY
| Collection | International Encyclopedia of Systems and Cybernetics |
|---|---|
| Year | 2004 |
| Vol. (num.) | 2(1) |
| ID | ◀ 2110 ▶ |
| Object type | Methodology or model |
The condition of a system which remains stable only in the absence of even a slight stimulus.
As observed by E. JANTSCH: “Stability is not a notion which might govern (human) systems over very long periods… Systems of high complexity trade stability for richness in adaptability” (1975, p.62).
Metastability manifests a system's readiness to adopt alternate states of stability. It is a border condition, depending on merely marginal stability of the system's environment, which should remain “benign”, to use R.N. ADAMS word (1988, p.24).
Such a condition exists in a quite widespread variety of systems. The stimulus is generally the introduction into the system of some “seed” or “nucleus”. Once this occurs, the dynamics of the system suddenly changes, through a kind of flip-over (or “catastrophe”).
This phenomenon is well known in physics (condensation or crystallization of supersatured solutions); in epidemics (explosive pandemics); in economics (market reversals) and in societies (sudden surge or reversals in beliefs or collective behaviors).
The basic condition for metastability seems to be a relative independence of the elements of the system. See: \term“{Systems} (Composite)”.
A. LOTKA stated: “Dynamically, the characteristic of a metastable equilibrium is that the thermodynamic potential of the system, though a minimum, is not an absolute minimum” (1956, p. 151).
R. FIVAZ adds (quoting G. NICOLIS and I. PRIGOGINE -1977, as well as R. SWENSON — 1989, and J. WICKEN — 1989b): “In metastability regime, transitions from simple structures to more complex structures take place only if the rate of entropy production is increased. This theorem is central in the theory of spontaneous complexification and establishes the DARWIN-like relationship between structure and function: only structures with a superior functional time rate are selected. The corollary is that, in the long run, systems will acquire the best performing structures that their couplings can possibly support” (1991, p.24-25).
R. FIVAZ also emphasizes that metastability transitions are fast and global (p.21).
These views seem related to St KAUFFMAN's “edge of chaos” (1993), where the maximal instability results of dissipative structuration at thermodynamic instability thresholds leading to bifurcations, conducive in turn to higher levels of entropy production, somehow compensed by increased complexity.