The consequences of the possibility of reducing the entropy in open systems, shown in Chapter 3, are considered. The notion of an "entropy pump", dissipative systems, energy, and structures is introduced. The classical examples of open systems from various fields of science illustrate the process of self-organization (Benard convective cells, turbulence, laser, optical transistor, Belousov-Zhabotinsky reaction) in dissipative systems and its features.

I. In an open system, far from equilibrium, with a large entropy outflow to the environment ("entropy pump"), the total entropy of the system decreases, and structure formation occurs.

Ii. For some critical values ​​of the external flow of energy or matter in a system from disordered states, as a result of loss of stability, ordered (dissipative structures) structures may arise.

Iii. Dissipative structures can occur in open systems that are far from equilibrium as a result of entropy exports; these are ordered self-organizing formations that are stable with respect to small perturbations; they can be spatial, temporal and spatial-temporal in nature. There is a certain basic set of dissipative structures, namely: the propagation of a single excitation front (for example, the phase transition boundaries), the propagation of a pulse of a stable form, standing waves, spiral waves (rotating vortices or reverberators).

Iv. Properties of dissipative systems:

• system properties are not derived from the properties of the elements;
• there is a cooperative interaction between the elements;
• uncontrolled fluctuations can increase and play the role of a decisive factor directing the evolution of the system;
• Systems can adapt to the environment in several different ways, and at the bifurcation point only the case decides which of these solutions will be implemented.

V. Examples of dissipative structures.

• Convective cells Benar. The upper temperature is greater by delta T in a liquid or gas located in the layer between the two horizontal parallel planes. Depending on the values ​​of the parameters of the medium and the interlayer, the heat between the plates is transferred either by molecular energy transfer by randomly moving molecules or, for some critical value parameters, convective motion arises and the medium is structured in the form of small cells (Benard cells). In the mechanism of self-organization, the distinction between the long-range nature of the process (about cm, m, km) and the small distances that the interaction forces between molecules (about angstroms) deserve particular attention. Here, not only the determinism of the process, but also the randomness (unpredictability) of the direction of rotation of the cells.
• Turbulence. When the flow velocity of a body exceeds a certain threshold, vortices appear in the initially laminar flow, alternately rotating in one direction or the other. The laminar flow rebuilds the structure and becomes turbulent.
• Laser. We consider the scheme of a typical laser and the process of its transition from the lamp mode (at different wavelengths and in different phases) to the laser mode (at the same wavelength and in one phase), i.e., to coherent
• The reaction of Belousov-Zhabotinsky. Occurs in a chemically dissipative system. At the same time, spatial and temporal structures appear. As a result of the implementation of the process in the thin layers of the solution between the plates, the phenomenon of formation of spiral waves (reverberators) is observed.

Entropy pump. Dissipative structures

From the above analysis, it follows that in an open system with a large outflow of entropy into the environment, i.e.

total entropy system:

decreases.

In this case, the chaos in the system decreases, that is, structure formation begins to occur in it. The condition | d _e S |> d _i S can occur only far from the equilibrium state, since near the equilibrium | d _e S | <d _i S. In order for structure formation to start, the entropy export must exceed a certain critical state, t. e. "entropy pump" is required. The growth of the orderliness of the system, the process of structure formation corresponds to the term ontogenesis (ontos - the real, genesis - the origin). The variety of forms that arise with this is described by the term morphogenesis (morphe - form). Ontogenesis is usually accompanied by morphogenesis. These processes are associated with the flow of entropy from the system, the work of the entropy pump. This is a general law applicable to the ontogenesis of the embryo, the emergence of stars, etc. In the course of the development of non-equilibrium processes, with a certain critical value of the external flow of energy or substance from disordered states, due to a loss of stability, there may be ordered. The latter may have a temporal, spatial, spatial-temporal character and are called dissipative structures; this is self-organization. Let us dwell on a number of terms widely used in synergetics.

A dissipative system is a mechanical system, the total mechanical energy of which decreases as it moves, changing into other forms, for example, into heat.

Dissipative energy is the transition of a part of the energy of an ordered process into the energy of a disordered and, finally, into heat.

Dissipative structures. In open systems that are far from equilibrium, new dynamic states of matter may arise, reflecting the interconnections of this system with the environment. These new structures are dissipative structures. These ordered self-organizing formations are stable with respect to small perturbations.