Cybernetics
& Human Knowing - Thesaurus pilot project
|
|
Pertubation |
|
Definition |
|
|
|
Principia Cybernetica (web) |
|
| no def. | |
Encyclopedia Autopoietica |
|
| An
exogenous influence affecting an organizationally-closed system. The verb
"perturb" carries the connotations of : (1) indirect effect, or (2) the
effectuation of some change internal to an affected entity without having directly
manipulated that entity’s internal components. Both senses apply to the usage of this
term in autopoietic theory. With respect to (1), the end result of pertubation is
constrained by the structure of the pertubed system, not some strict and deterministic
cause/effect linkages extrinsic to it (cf. structural determination). With respect to (2),
interactions (with the medium or another system) are construed as
‘perturbations’ in the sense that the source induces an effect without having
penetrated the boundary of the affected system.
|
|
International Encyclopedia of Systems & Cybernetics |
|
| 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 pertubations (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 retum to its own type of dynamic stability. Pertubations 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 pertubation 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".
|
|
