International Encyclopedia of Systems and Cybernetics

"…the ordered configuration that emerge beyond instability of the thermodynamic branch".

This G. NICOLIS and I. PRIGOGINE (1978, p.60) definition comes as a conclusion to their introductory chapter on nonlinear thermodynamics.

I. PRIGOGINE described dissipative structures as "… in far- from- equilibrium conditions, states of matter characterized by coherent space-time behavior" (1973, p.565). He also wrote: "… dissipative structures… are formed and maintained through the exchange of energy and matter in non-equilibrium conditions". He associates this with "creation of order" (p.581). However, in the very process of dissipative structuration, a stochastic event normally acts as a trigger (1976, p.93).

PRIGOGINE makes another very significant statement: "… the dimensions of the system play an essential role in the formation of dissipative structures. A sufficiently small system will always be dominated by the boundary conditions (NAZAREA, 1974). In order for the nonlinearities to be able to lead to a choice between various solutions, it is necessary to go beyond some critical spatial dimensions (HANSON, 1974). It is only then that the system acquires some autonomy with respect to the outside world" (p.1 01).

E.J. KROWITZ explicits the concept in the following way (after BAHG Chang Gen, 1990): "Three conditions identify a dissipative structure:

- The system is open with continual interchange with its environment;

- The system is in a state of damped instability;

- The evolutionary path of the system stems from fluctuations which push the dynamic structure from one state to another" (1991, p.47).

Dissipative structures were first observed in the opening years of 20th. Century by the French physicist H. BÉNARD, who observed the progressive emergence of hexagonal convective cells, replacing simple thermical agitation, in a heated liquid, once a critical temperature gradient is reached, i.e. when thermodynamic equilibrium is breached.

This corresponds to symmetry breaking resulting from a considerable input of energy.

Analogous phenomena were observed by PRIGOGINE and his groups in a wide variety of physical, chemical, biological, and even later in social systems, which receive increasing inputs of energy and, as a result, start to develop evergrowing fluctuations and react by creating organized (or more organized) macrostructures.

Starting from these observations, PRIGOGINE created his generalized thermodynamics, applied to all systems far away from equilibrium

"The stability of dissipative structures is different in kind of stability in steady states. It is not a result of a low production of entropy, but instead, of their ability to transfer to their environment great quantities of entropy, due to their greater complexity (for example under the guise of heat or degraded products). Consequently, when a system organized through dissipative structures does appear, its environment tends to become growingly disorganized…

"Dissipative structures result of great imbalances and maintain themselves as long as these imbalances subsist. Processes which reduce gradients, as for example diffusion, destroy these structures"(1992).

E. JANTSCH states: "The concept of dissipative structure also implies that the environment is necessary to maintain the dissipative structure; unlike equilibrium structures, dissipative structures cannot exist independently" (1976, p.40)

It is however very questionable if equilibrium structures could do without environment. Are they not stabilized former dissipative structures, i.e. having secured the needed permanent energy inputs… and even the result of a former stage of metastability?

As a result, a system whose organization has been upgraded through structuration by dissipation of supplementary energy, cannot anymore survive without this supplement.

Through dissipative structures a system is not merely able to absorb more energy and matter: it reacts to these excess inputs and becomes able to use them by reorganizing itself in its own ways. This may be considered as a generalization of the biological concepts of anabolism, metabolism and catabolism, in morphogenesis conditions.

The newly emerging structure finally finds its own permanence limits, according to the steadiness of the supplementary inputs it receives.

PRIGOGINE also states: "A system may undergo various succesive processes of structuration through crisis. A bifurcation of its evolution characterizes each of these processes" (1992).

The dissipative structure concept seems to be of utmost importance for the study of the man-planet system presently in course of shaping, specially in relation to:

- the growth and acceleration of flows through human organizations

- the very speedy shaping of new and evermore complex social structures

- the growing disruption of the global environment.