PERTURBATION
| Collection | International Encyclopedia of Systems and Cybernetics |
|---|---|
| Year | 2004 |
| Vol. (num.) | 2(2) |
| ID | ◀ 2535 ▶ |
| Object type | General information, Methodology or model |
Any input that modifies the dynamic equilibrium of a system or a subsystem, be it in a reversible or irreversible way.
The concept of perturbation is somehow ambiguous.
J.A. GOGUEN and F.J. VARELA state: “If we stress the autonomy of a system… then the environmental influences become perturbations (rather than inputs) which are compensated for through the underlying recursive independence of the system's components” (1979, p.34).
The same situation exists between subsystems within the system. Each of them may receive from others inputs that perturb it.
There is however a considerable difference between so-called perturbing inputs: To ingest strychnine is not, as an input, in the same class than eating bread, as the first one will, irreversibly, kill the system while the second one will benefit it, allowing it to return to its own type of dynamic stability.
Perturbations play a very important role near an instability threshold in systems affected by giant fluctuations. Such a perturbation — in most cases a random environmental event, or noise — may destroy the former organized structure and induce a bifurcation, toward a different structuration through dissipation. However, a perturbation can have this effect only if it does not throw the system out of its historical macro-determinism, destroying it in the process.
- “Perturbation” seems to be frequently used as a near synonym of “disturbance”.